text:
2. Experimental design and description of numerical models
3. Simulation results
a. Baseline experiment
b. Ex1000_fs simulations
c. Ex2500_fs simulations
d. Ex2500_ns simulations
e. ExSierra_fs simulations
f. ExSierra_ns simulations
BLASIUS Pressure Gradient Formulation
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Vertical profiles of (left) wind speed, (middle) potential temperature, and (right) Scorer parameter used in all experiments except the baseline case based on the 2100 UTC 25 Mar 2006 MGAUS sounding taken upstream of the Sierra Nevada during T-REX IOP 6.
The lowest 5 km of the vertical profile of potential temperature shown in Fig. 1.
Vertical velocity (color, interval 0.05 m s−1) and potential temperature (black contours, interval 10 K) for the baseline experiment at the final time (4 h) for all models and (bottom right) the analytic solution.
Vertical velocity (color, interval 1 m s−1) and potential temperature (black contours, interval 10 K) for Ex1000_fs case at the final time (4 h) for all models and (bottom right) the mean.
Horizontal perturbation wind component (color, interval 5 m s−1) and potential temperature (black contours, interval 10 K) for Ex2500_fs (hm = 2500 m, free slip) at the final time (4 h) for all models and (bottom right) the mean.
Vertical velocity (color, interval 2.5 m s−1) and potential temperature (black contours, interval 10 K) for Ex2500_fs (hm = 2500 m, free slip) at the final time (4 h) for all models and (bottom right) the mean.
Horizontal perturbation wind component (color, interval 2.5 m s−1) and potential temperature (black contours, interval 10 K) for Ex2500_ns (hm = 2500 m, no slip) at the final time (4 h) for all models and (bottom right) the mean.
Horizontal perturbation wind component (color, interval 5 m s−1) and potential temperature (black contours, interval 10 K) for ExSierra_fs (Sierra Terrain, free slip) at the final time (4 h) for all models and (bottom right) the mean.
Horizontal perturbation wind component (color, interval 2.5 m s−1) and potential temperature (black contours, interval 10 K) for ExSierra_ns (Sierra Terrain, no slip) at the final time (4 h) for all models and (bottom right) the mean.
Time evolution (1–8 h) of horizontal perturbation wind component (color, interval 5 m s−1) and potential temperature (black contours, interval 10 K) for Ex2500_fs as simulated by the DK model.
Standard deviation of vertical velocity (m s−1) at the final time (4 h) based on all models for the (a) baseline, (b) Ex1000_fs, (c) Ex2500_fs, (d) Ex2500_ns, (e) ExSierra_fs, and (f) ExSierra_ns experiments. Note that the color scale varies among the plots.
Vertical momentum flux (N m−1) as a function of height at the final time (4 h) for the large-terrain experiments: (a) Ex1000_fs, (b) Ex2500_fs, (c) Ex2500_ns, (d) ExSierra_fs, and (e) ExSierra_ns experiments.
Vertical momentum flux (N m−1) as a function of height (a) averaged over the 4–5-h simulation period for a subset of 6 models. (b) The curves correspond to the mean of the standard deviation of the vertical momentum flux computed over 4–5 h for each of the 6 models in the subset (red), the standard deviation of the subset models computed at 4 h (blue), the standard deviation for the full set of models at 4 h (black), and the standard deviation for the 6 models, each of which are averaged over 4–5 h (green).
Sensitivity tests using EULAG for Ex2500_fs (hm = 2500 m, free slip) at 4 h: (a) default setup (same as in Fig. 5), (b) Smagorinsky closure, (c) no explicit closure (implicit LES), and (d) thicker upper absorbing layer starting at z = 22 km compared to the default z = 25 km. The horizontal perturbation wind component (color, interval 5 m s−1) and potential temperature (black contours, interval 10 K) are shown.
An Intercomparison of T-REX Mountain-Wave Simulations and Implications for Mesoscale Predictability
James D. Doyle1, Saša Gaberšek2, Qingfang Jiang1, Ligia Bernardet3, John M. Brown3, Andreas Dörnbrack4, Elmar Filaus5, Vanda Grubišić6, Daniel J. Kirshbaum7, Oswald Knoth5, Steven Koch3, Juerg Schmidli8, Ivana Stiperski9, Simon Vosper10, and Shiyuan Zhong11
1 Naval Research Laboratory, Monterey, California
| 2 UCAR, Monterey, California
| 3 NOAA/Earth System Research Laboratory, Global Systems Division, Boulder, Colorado
| 4 Institut für Physik der Atmosphäre, Deutsches Zentrum für Luft- und Raumfahrt, Oberpfaffenhofen, Germany
| 5 Leibniz Institute for Tropospheric Research, Leipzig, Germany
| 6 University of Vienna, Vienna, Austria
| 7 University of Reading, Reading, United Kingdom
| 8 Institute for Atmospheric and Climate Science, ETH, Zurich, Switzerland
| 9 Meteorological and Hydrological Service, Zagreb, Croatia
| 10 Met Office, Exeter, United Kingdom
| 11 Michigan State University, East Lansing, Michigan
Terrain-Induced Rotor Experiment (T-Rex)
https://doi.org/10.1175/MWR-D-10-05042.1
Numerical simulations of flow over steep terrain using 11 different nonhydrostatic numerical models are compared and analyzed. A basic benchmark and five other test cases are simulated in a two-dimensional framework using the same initial state, which is based on conditions during Intensive Observation Period (IOP) 6 of the Terrain-Induced Rotor Experiment (T-REX), in which intense mountain-wave activity was observed. All of the models use an identical horizontal resolution of 1 km and the same vertical resolution. The six simulated test cases use various terrain heights: a 100-m bell-shaped hill, a 1000-m idealized ridge that is steeper on the lee slope, a 2500-m ridge with the same terrain shape, and a cross-Sierra terrain profile. The models are tested with both free-slip and no-slip lower boundary conditions.
The results indicate a surprisingly diverse spectrum of simulated mountain-wave characteristics including lee waves, hydraulic-like jump features, and gravity wave breaking. The vertical velocity standard deviation is twice as large in the free-slip experiments relative to the no-slip simulations. Nevertheless, the no-slip simulations also exhibit considerable variations in the wave characteristics. The results imply relatively low predictability of key characteristics of topographically forced flows such as the strength of downslope winds and stratospheric wave breaking. The vertical flux of horizontal momentum, which is a domain-integrated quantity, exhibits considerable spread among the models, particularly for the experiments with the 2500-m ridge and Sierra terrain. The differences among the various model simulations, all initialized with identical initial states, suggest that model dynamical cores may be an important component of diversity for the design of mesoscale ensemble systems for topographically forced flows. The intermodel differences are significantly larger than sensitivity experiments within a single modeling system.
l Additional affiliation: Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado.
m Current affiliation: NOAA/National Severe Storms Laboratory, Norman, Oklahoma.
Corresponding author address: James D. Doyle, Naval Research Laboratory, Marine Meteorology Division, 7 Grace Hopper Ave., Monterey, CA 93943-5502. E-mail: james.doyle@nrlmry.navy.mil
This article is included in the Terrain-Induced Rotor Experiment (T-Rex) special collection.
Keywords: Mountain waves; Mesoscale models; Model comparison; Nonhydrostatic models; Mountain meteorology
The fundamental linear theory for the generation of inviscid mountain waves forced by stratified airflow over two-dimensional obstacles has been established for several decades (e.g., Queney et al. 1960; Smith 1979, 1989). Vertically propagating mountain waves often amplify in the stratosphere due to the decrease of atmospheric density with altitude and nonlinear processes, which may lead to overturning and turbulent breakdown (e.g., Lindzen 1988; Bacmeister and Schoeberl 1989). Mountain waves can have an important impact on the atmosphere because of their role in downslope windstorms (Klemp and Lilly 1975); clear-air turbulence (Clark et al. 2000); vertical mixing of water vapor, aerosols, and chemical constituents in the stratosphere (Dörnbrack and Dürbeck 1998); potential vorticity generation (Schär and Durran 1997); and orographic drag influence on the general circulation (Bretherton 1969; Ólafsson and Bougeault 1996).
Although numerical models have been able to successfully simulate gravity wave characteristics (e.g., Smith and Grønås 1993; Schär and Durran 1997) including breaking (Clark and Peltier 1977; Bacmeister and Schoeberl 1989), and other related topographically forced flows (e.g., Sharp and Mass 2004; Colle and Mass 1996; Doyle et al. 2005; Colle et al. 2008), the degree to which mountain waves are predictable still remains an outstanding question. Lorenz (1969) suggested that perturbation growth rates increase as the horizontal scale of the phenomenon decreases, effectively limiting the intrinsic predictability. The notion that mesoscale phenomena forced by the lower boundary attain enhanced predictability has been hypothesized (e.g., Anthes et al. 1985). However, this perspective is likely overly optimistic because of lateral boundary conditions, numerical dissipation, and adjustment issues (Errico and Baumhefner 1987; Vukicevic and Errico 1990), as well as nonlinearities introduced by the underlying terrain. For example, mesoscale predictions of landfalling fronts were found to be very sensitive to small changes in incident flow, as deduced through simulations made with small modifications to the topography orientation by Nuss and Miller (2001). Two-dimensional idealized adjoint (Doyle et al. 2007) and ensemble (Doyle and Reynolds 2008) model results indicate large sensitivity to the initial state as the mountain height increases, forcing wave breaking, where perturbation growth becomes extremely rapid leading to large ensemble spread. Reinecke and Durran (2009a) used three-dimensional ensemble simulations to assess the sensitivity of downslope winds to the initial conditions. They examined two downslope windstorm cases and found the results to be quite sensitive to the initial state, especially for an event that featured low-level wave breaking.
An intercomparison of model simulations of the 11 January 1972 Boulder downslope windstorm is discussed in Doyle et al. (2000). Upper-level wave breaking was predicted by all of the models in comparable locations. However, there were a number of significant differences among the simulations including the details of the wave breaking and the lower-tropospheric wave structure, which was characterized by a hydraulic jump in most of the models and large-amplitude waves in several of the simulations. In the Doyle et al. (2000) study, only a single model test case was carried out. A number of outstanding questions remain including sensitivity of mountain-wave predictions to the model formulation.
During the Terrain-Induced Rotor Experiment (T-REX; Grubišić et al. 2008), high-resolution forecasts were routinely conducted to assist in mission planning using a number of different three-dimensional nonhydrostatic numerical models such as the Coupled Ocean–Atmosphere Mesoscale Prediction System (COAMPS1; Hodur 1997), two dynamical cores of the Weather Research and Forecasting model (WRF), namely the Advanced Research WRF (WRF-ARW; Skamarock et al. 2008) and the Nonhydrostatic Mesoscale Model (NMM) (Black et al. 2005; Janjic et al. 2010), as well as the fifth-generation Pennsylvania State University–National Center for Atmospheric Research (PSU–NCAR) Mesoscale Model (MM5; Dudhia 1993). The forecasts of topographically forced flows, such as windstorms and mountain waves, often differed significantly among the various three-dimensional models. Although one should not necessarily expect forecasts from multiple models to be in close agreement (e.g., Dörnbrack et al. 2005), these differences among the models motivated a more fundamental intercomparison of models in a more controlled and idealized setting. In this study, we compare the results of two-dimensional numerical simulations using an observed initial state from T-REX in order to further investigate the sensitivity of downslope windstorm and mountain-wave predictions to model characteristics through a series of model test cases. Strong downslope windstorms and complex regions of upper-level wave breaking develop in some of the test cases. The evolution of such phenomena presents a particularly difficult challenge from a mesoscale predictability perspective. The overall goal of this study is to explore the predictability and characteristics of model solutions for conditions under which wave breaking and a downslope windstorm were both observed and anticipated from theoretical considerations. The experimental design and model descriptions are presented in section 2. The simulation results are described in section 3, followed by the discussion and conclusions in section 4.
In these tests, the configuration of the individual models is standardized as much as possible to facilitate straightforward comparisons and analysis. The models are applied in a two-dimensional mode with a horizontal grid increment of 1 km and a vertical grid spacing that is stretched from 50 m near the surface to a constant of 200 m, which extends from an altitude of 800 m to at least 26 km (134 or more vertical levels). The fine vertical grid increment in the lowest 800 m of the model is used to better resolve the near-surface processes, particularly for the simulations performed with surface friction.
The attributes of the 11 numerical models that are used in this intercomparison study are summarized in Table 1. The numerical model suite includes: the Advanced Regional Prediction System (ARPS; Xue et al. 2000, 2001), All-Scale Atmospheric Model (ASAM; Hinneburg and Knoth 2005), Boundary Layer Above Stationary, Inhomogeneous Uneven Surfaces (BLASIUS; Wood and Mason 1993), two different versions of COAMPS (versions 3 and 4; Hodur 1997), the Durran and Klemp (1983) model (DK), the Bryan cloud model (CM1; Bryan and Fritsch 2002), the Eulerian/semi-Lagrangian model (EULAG; Prusa et al. 2008), the Regional Atmospheric Modeling System (RAMS; Pielke et al. 1992), the Met Office Unified Model (UM; Davies et al. 2005), and the WRF-ARW model (Skamarock et al. 2005). These models are quite diverse with regard to their numerical characteristics. For example, the suite of models includes semi-Lagrangian (UM) and Eulerian models, models with higher-order time differencing (CM1, WRF), anelastic (BLASIUS, EULAG) and compressible (e.g., DK, CM1) dynamical cores, and vertical coordinates with one model that uses a cut-cell technique (ASAM) and the others that follow the terrain. The models have a diverse set of turbulence parameterizations, as well as treatment of the lateral and upper-boundary conditions. Simulations are conducted with zero surface stress and a bulk stress parameterization, which we refer to as free slip and no slip, respectively. No rotation is used for the simulations with a free-slip lower boundary. A Coriolis parameter consistent with a 37°N latitude is used for the experiments with surface friction. The Coriolis force is applied to the perturbation velocity rather than the mean fields in the no-slip simulations, hence the basic-state flow is assumed to be in geostrophic balance. The surface heat flux is zero in all models, implying that the ground temperature is in balance with the surface air temperature. No moist processes are included in any of the simulations. Vertical mixing in the free atmosphere is the only physical parameterization included within the models for the free-slip simulations. For the no-slip simulations, the roughness length is specified at 10 cm for most of the models, with the exception of EULAG and CM1, which use bulk aerodynamic drag coefficients of Cd = 10−3 and 0.008, respectively.
Model formulation and characteristics for the intercomparison. Boundary condition (BC), subgrid scale (SGS), multidimensional positive-definite advection transport algorithm (MPDATA), total variation diminishing (TVD), horizontal (h), and vertical (υ) are denoted.
A total of 6 test cases were conducted using the 11 different numerical models. The setup parameters for the test cases are contained in Table 2. The first test case consists of a baseline experiment for hydrostatic mountain waves that uses a constant isothermal temperature profile of 250 K and a wind speed of 20 m s−1. The mountain profile in the idealized topography cases is a two-sided Witch of Agnesi profile:
with a = au for x < 0 and a = ad otherwise. In the baseline test case, the mountain is symmetric with a = 10 km. The terrain shape we consider for the Ex1000_fs, EX2500_fs, and EX2500_ns cases is asymmetric with the lee slopes steeper than the upwind slopes, which is a characteristic of a number of mountain ranges including the Colorado Front Range and the Sierra Nevada. To represent this asymmetry in these tests, the upwind half-width is set to au = 40 km and the downwind half-width to ad = 5 km (following Hertenstein and Kuettner 2005). In the baseline case, the mountain height is hm = 100 m, which generates small-amplitude mountain waves in the linear hydrostatic regime for the reference sounding conditions considered. The Ex1000_fs case makes use of a 1000-m maximum mountain height, and hm = 2500 m is used in the Ex2500_fs and Ex2500_ns experiments. The terrain used in ExSierra_fs and ExSierra_ns is based on a section across the Sierra Nevada and oriented along the T-REX "B" flight track (e.g., Grubišić et al. 2008; Smith et al. 2008). A 1-km resolution terrain digital elevation model [the National Oceanic and Atmospheric Administration (NOAA) National Geophysical Data Center Global Land One-kilometer Base Elevation (GLOBE)] is used to specify the terrain with a maximum height of ~3500 m. The terrain upstream of the Sierra Nevada and downstream of the second mountain range, the Inyos, is eliminated to isolate the local Sierra response. The terrain used in the ExSierra_fs and ExSierra_ns simulations is filtered to remove 2Δx variations.
Parameters and characteristics of model test cases.
The initial conditions for all experiments are horizontally homogeneous and with the exception of the baseline are based on the 2100 UTC 25 March 2006 Mobile GPS Advanced Upper-Air Sounding System (MGAUS) sounding upstream of the Sierra Nevada during T-REX IOP 6 (Fig. 1), which was one of the stronger mountain-wave cases observed during T-REX (Grubišić et al. 2008; Smith et al. 2008; Doyle et al. 2011). The wind component parallel to the T-REX "B" flight track (245°) is used for the initial state. The MGAUS sounding is extended in the vertical through the use of the National Weather Service (NWS) Oakland radiosonde profile above 14 km. The wind profile was smoothed in the low levels to remove several sharp shear layers and a minimum wind speed of 5 m s−1 is used near the surface. Near the top of the sounding above 18 km, the wind speed decreases linearly with height to 0 at 23 km to minimize problems with gravity wave reflection from the top boundary. The sounding contains multiple shear layers (Fig. 1), strong low-level cross-mountain winds (>20 m s−1) for the simulations that have terrain heights at 2500 m or above, and increased stability above the mountain crest between 1 and 4 km (Figs. 1 and 2), with the latter two characteristics favorable for downslope windstorms (e.g., Brinkman 1974; Durran 1986, 1990). As discussed above, a critical level is present at ~23 km where the cross-mountain wind speed is small. The Scorer parameter, , where N is the Brunt–Väisälä frequency; U is the cross-mountain wind speed; and Uzz is the second derivative of U with respect to height z, which exhibits a rapid decrease with height between 2–5 km (Fig. 1) consistent with the possibility of trapping of low-level wave energy (Scorer 1949). The average Scorer parameter in the upper troposphere (i.e., 5–10 km) is approximately 0.000 35 m−1, implying that only hydrostatic waves with wavelengths longer than the cutoff wavelength, , can penetrate this layer.
Citation: Monthly Weather Review 139, 9; 10.1175/MWR-D-10-05042.1
The purpose of the baseline experiment is to provide an assessment of the model dynamics through the simulation of a common test case in which an analytic solution can be found. In this case, we selected a linear hydrostatic gravity wave test case, which nearly all models have used previously as a benchmark during their various developmental stages. The vertical velocity at the 4-h simulation time for the baseline experiment using hm = 100 m is shown in Fig. 3 for all 11 numerical models. In general, all of the simulations feature vertical propagating hydrostatic gravity waves similar to the linear analytic solution. The vertical wavelength for all of the simulations is approximately 6.4 km, in agreement with expectations from linear theory, λz = 2πU/N, where N is the Brunt–Väisälä frequency, which for an isothermal, dry atmosphere can be expressed as
The reference state of and U = 20 m s−1 yields N = 0.0196 s−1 and λz = 6.4 km.
Overall the simulation results are in general agreement amongst the models; however, there are several notable exceptions. The BLASIUS model appears to excessively amplify the vertical propagating wave with altitude, a consequence of the model equation set formulation (see below). The RAMS model simulation shows some disagreement with the analytic solution near the top and bottom portion of the sloped ascent and descent regions, which may be arising from wave reflections from the top boundary. The other model simulations in general are in close agreement with the analytic solution.
The relatively rapid growth of wave amplitude with height in the BLASIUS simulations can be shown to be due to the formulation of the anelastic equation set used in this model. The pressure gradient term in the anelastic form of the BLASIUS momentum equations is written as [see Eq. (A1) in the appendix], where p′ is the perturbation pressure (to a reference, hydrostatically balanced profile) and is a reference density, which is a function of height only. The consequence of the different forms of the pressure-gradient term in the momentum equation becomes clear when linearizing the equations and deriving the vertical-structure equation for small-amplitude mountain waves. The BLASIUS equations result in a fundamentally different form for the vertical structure equation, solutions to which grow relatively rapidly with height. The wave amplitude has a dependence on , where ρ0 is a constant reference density. In contrast, solutions to the vertical structure equation derived from either the Lipps and Helmer equations, or Eqs. (A1)–(A3) when the pressure gradient is expressed as , have a dependence on and hence grow less rapidly with height. Further details are provided in the appendix. Linear solutions (not shown) for the constant background flow baseline case derived with the BLASIUS pressure-gradient term agree closely with the BLASIUS results in Fig. 3, whereas solutions based on either or the Lipps and Helmer term agree closely with the results produced by all other models.
It is clear that the cause of the larger wave amplitude at upper levels in the BLASIUS simulation is a direct consequence of the form of the pressure-gradient force used when the model is run in anelastic mode. Note, however, that the BLASIUS model is rarely run in this configuration. Previous mountain-wave studies based on BLASIUS simulations have all used the Boussinesq formulation of the model, in which is assumed independent of height (e.g., Wells et al. 2008; Vosper 2004). The issue does not apply to these studies. The fact that the EULAG results for the baseline case are closer to those of the compressible models and the analytic solution, is consistent with this analysis (see Fig. 3).
The simulated potential temperature and vertical velocity at 4 h are shown in Fig. 4 for the Ex1000_fs experiment, which use hm = 1000 m and a free-slip lower boundary. The models in general exhibit a series of trapped waves in the lower troposphere with a wavelength of approximately 10 km. The trapped waves result from wave energy being partially reflected or ducted as a result of the aforementioned decrease in the Scorer parameter with altitude. The number of large-amplitude wave crests present in each model simulation varies considerably. Most models have at least 3 or 4 larger waves, and some models have as many as 5 or 6 waves, particularly for those models using higher-order numerical methods (e.g., WRF-ARW and CM1). The RAMS and ASAM models show considerable damping, evident from a comparison of maximum surface wind speeds in Table 3 and relative to the mean of all of the models (Fig. 4, lower right). Because of their relatively short wavelengths, the trapped waves are only just adequately resolved using the 1-km horizontal grid spacing and thus may be highly sensitive to the numerical methods applied in the models.
Maximum surface wind speed (m s−1) for each experiment and model after 4 h of integration.
At upper levels, vertically propagating waves that leak through the wave duct are apparent in all of the models. The tilt of the wave phase lines with altitude increases in the stratosphere in all models associated with the increase in static stability. The amplitudes of the waves vary considerably once again, with the weakest wave activity found in ASAM and the most extensive regions in the BLASIUS simulation. Most of the models exhibit localized regions of wave breaking in the stratosphere just above the mountain or downstream of it; however, the amplitude of the breaking varies considerably among the models.
The potential temperature and horizontal wind speed perturbation for the 4-h simulation time are shown in Fig. 5 for the Ex2500_fs experiment, which utilizes hm = 2500 m and a free-slip lower boundary. With the larger mountain height, the model simulations have considerably larger-amplitude waves relative to the Ex1000_fs simulation. A strong response is apparent in nearly all of the models. Eight of the models, ARPS, BLASIUS, COAMPSv3, COAMPSv4, CM1, DK, EULAG, and WRF-ARW, all indicate the presence of severe winds in the lee of the terrain with maximum near-surface winds in excess of 60 m s−1. These models indicate the presence of low-level breaking, a weak or reversed wind speed minimum in the midtroposphere above or in the lee of the mountain crest associated with the breaking, trapped or secondary waves in the lower stratosphere, and vertically propagating waves and overturning in the stratosphere. It is interesting to note that COAMPSv4 has one of the stronger windstorms in this group of models, and COAMPSv3 has the weakest windstorm in this group of 8 models. The BLASIUS model has a bore or hydraulic-like jump feature that propagates significantly downstream of the mountain, in contrast to the COAMPSv3 windstorm that is confined to the lee slope.
A group of three models have a quite weak response relative to the other simulations (see Table 3) and the mean (Fig. 5, lower right). These models, ASAM, RAMS, and UM, indicate some enhancement of the winds along the lee slope, but differ substantially in character relative to the other simulations. Both the UM and RAMS simulations have a wind speed maximum near the mountain crest. Interestingly, the mountain-wave response in the ASAM simulation is the weakest in amplitude and contains a small-amplitude lee-wave train.
The characteristics of the stratospheric wave breaking vary considerably among the simulations. All of the models have signatures of stratospheric vertically propagating waves. The models with the strongest lower-tropospheric waves tend to produce the largest wave amplitudes in the stratosphere. Nearly all of the models are in agreement with respect to the vertical wavelength, tilt of the wave phase lines, and preferred regions of wave amplification and overturning in the stratosphere. All of the models with the exception of the ASAM and UM simulate secondary wave generation downstream from the wave-breaking region in the lower stratosphere.
The variations among the simulations are further illustrated in the vertical velocity and potential temperature fields at the 4-h time for Ex2500_fs shown in Fig. 6. A number of models that simulate a strong mountain-wave response (e.g., COAMPSv3, COAMPSv4, CM1, DK, EULAG, and WRF-ARW) have global vertical velocity maxima well downstream of the terrain crest, while the ARPS, RAMS, and UM simulations tend to have maxima near or immediately above the terrain crest, more similar to a hydrostatic wave.
The u component of the horizontal wind speed perturbation and potential temperature at the 4-h simulation time are shown in Fig. 7 for the Ex2500_ns experiment, which corresponds to hm = 2500 m, a no-slip lower boundary condition and rotation. In general, the models are more in agreement with each other (Table 3) than in the corresponding free-slip simulation (Ex2500_fs). A comparison of the two experiments underscores the profound impact of surface friction and rotation on the mountain-wave response. In general, trapped lee waves are present in all of the simulations, with the number of simulated crests varying among the models, although to a lesser extent than in Ex1000_fs. The exceptions are ARPS and BLASIUS, both of which simulate a single larger-amplitude wave crest, and exhibit a downstream wave train in the lower troposphere that is heavily damped, in contrast to the robust trapped waves apparent in the other simulations. The WRF-ARW exhibits a jetlike structure in the perturbation wind field that extends from above the mountain to the upstream lateral boundary at an approximate altitude of 5 km. The jet results from an in situ increase in momentum at the upstream boundary that subsequently self-advects toward the ridge. The jet has a minimal impact on the solution by 4 h.
The stratospheric wave characteristics are broadly similar in Ex2500_ns; however, there are several distinct differences among the simulations. Several of the models (e.g., BLASIUS, COAMPSv3, COAMPSv4, DK, UM, and WRF-ARW) all contain a large-amplitude and short horizontal wavelength feature apparent in the isentropes in the lower stratosphere positioned above the lee-wave crests. All of the models contain steepening of the isentropes in the stratosphere associated with breaking of the vertically propagating waves; however, the spatial extent and depth of the breaking layer vary substantially. The common stratospheric wave characteristics are apparent in the mean.
The ExSierra_fs experiment makes use of a terrain transect across the Sierra and a free-slip lower boundary condition. The simulated potential temperature and horizontal wind speed perturbation for the 4-h time are shown in Fig. 8. Broad similarities are apparent between all of the simulations; for example, they contain significant wave activity in the lee of the Inyo Range, as well as large-amplitude waves in the stratosphere. However, substantial variations are also apparent among the 11 model simulations. The COAMPSv3, COAMPSv4, DK, and EULAG simulations all develop a strong windstorm along the lee slope of the Sierra and confined to the Owens Valley. The BLASIUS simulation exhibits shooting flow along the Sierra lee slope that extends over the Inyo Range and farther downstream, evolving abruptly into a hydraulic-like jump feature. It is interesting to note that the CM1 and WRF-ARW simulations were among the strongest downslope windstorms in Ex2500_fs, while in ExSierra_fs the CM1 and WRF-ARW-simulated wave responses are qualitatively among the weakest using the same basic model setup and diffusion coefficients. Several simulations contain relatively small-amplitude trapped lee waves downstream of the Inyos (e.g., ASAM, UM, and WRF-ARW) in contrast to the models that exhibit strong low-level wave breaking in the lee of the Sierra (DK) and Inyos (BLASIUS). The ASAM model simulation for Ex2500_fs is one of the weakest wave responses, while the ASAM simulation for ExSierra_fs is qualitatively similar to other models such as ARPS, COAMPSv3, EULAG, RAMS, UM, and WRF-ARW (summarized in Table 3).
The stratospheric wave activity varies substantially in the models. Several models, including COAMPSv4, DK, and WRF-ARW, simulate vigorous wave breaking in the stratosphere, in contrast to other models that feature smaller-amplitude waves in the lower troposphere. Once again the basic properties of the vertically propagating stratospheric waves are broadly similar (cf. the mean), with large differences in the finescale aspects, comparable to the Ex2500 experiments.
The ExSierra_ns experiment uses an identical Sierra terrain transect as the previous experiment, a no-slip lower boundary condition and rotation. The simulated potential temperature and u component of the horizontal wind speed perturbation for the 4-h time are shown in Fig. 9. Once again the introduction of surface friction and rotation results in a significant reduction in the gravity wave response in all the model simulations, similar to the pair of Ex2500 experiments. The models are in much closer agreement with each other (Table 3 and mean in Fig. 9) relative to the corresponding free-slip experiment (Fig. 8). The ARPS, ASAM, COAMPSv4, CM1, DK, and WRF-ARW simulations exhibit well-defined trapped waves in the lee of the Inyo ridge. In contrast, other models such as BLASIUS, COAMPSV3, EULAG, RAMS, and UM exhibit much less wave activity downstream of the Inyos.
The stratospheric wave characteristics such as wavelength and amplitude (as diagnosed from the potential temperature perturbations) are overall quite similar, although the details of the wave fields differ. All of the models exhibit a large potential temperature perturbation in the 11–13-km layer downstream from the Sierra crest above Owens Valley or the Inyo Range. Similar regions of wave breaking above 15 km are present in all of the models as well.
In addition to analyzing the instantaneous flow fields in the simulations, it is also illustrative to consider their time evolution. The simulated potential temperature and horizontal wind speed for the 1–8-h times are shown in Fig. 10 for the DK model for the Ex2500_fs experiment. Near the early portion of the simulation, the lee-side windstorm is substantially weaker (less than 50 m s−1 at the 2-h time) and the region of wave breaking first develops in the stratosphere. The 3-h simulation time shows wave breaking within the troposphere with a deep region of wave overturning and a stronger lee-side wind response. A hydraulic-like transition occurs when the fast shooting flow rapidly decelerates downstream, particularly evident beginning at 4 h. This feature, similar to a hydraulic jump, continues to propagate downstream with time and is located approximately 100 km downstream from the mountain crest by 7 h. At no point does the simulation revert back into a weaker windstorm state with an absence of tropospheric breaking (e.g., 2-h time) as in the RAMS and UM simulations (Fig. 8). Although the temporal evolution likely does vary between the various model simulations, it appears that these temporal variations are not rapid or large enough to explain the large variability among the model simulations. Some of the differences in the wave amplitudes may arise from the numerical accuracy used in the dynamical cores (Reinecke and Durran 2009b), although the wave strength and accuracy of the numerical schemes are not obviously correlated for these experiments, perhaps due to the contribution of other factors such as diffusion.
The vertical velocity standard deviation of the model simulations for each experiment is shown in Fig. 11. The smallest standard deviation is the baseline experiment, with the greatest variability within the vertically propagating gravity wave above 10 km and positioned over the mountain. The standard deviation for the baseline experiment is approximately two orders of magnitude smaller than that of any other experiment, which reinforces that the models are generally effective at replicating the basic characteristics of the hydrostatic wave case. In Ex1000_fs, the standard deviation is a maximum in the lower troposphere in the lee of the 1000-m mountain because of the phase and amplitude differences in the simulated trapped wave train.
The standard deviation is the largest in the Ex2500_fs and ExSierra_fs simulations, which contain the largest amplitude waves. In Ex2500_fs, the vertical velocity variance is a maximum in two regions: in the midtroposphere in the breaking region and in the stratosphere downstream of the breaking in the zone that contains the secondary short wavelength gravity waves. The ExSierra_fs exhibits two variance maxima: one near and just downstream of the Sierra in the lower troposphere and a second considerably farther downstream beyond the Inyo Range, associated with the trapped waves that generally differ in character (e.g., wavelength and amplitude) among the models. Considering that the wave amplitude increases with the mountain height, we normalize the standard deviations in Fig. 11 by the corresponding mountain height (note: according to linear theory, the wave amplitude is proportional to the mountain height). The resultant normalized deviations (not shown) are still significantly larger in the higher-terrain simulations, indicating that the spread increases with the mountain height much faster than the wave amplitude, presumably due to nonlinear processes.
The two no-slip simulations with large terrain, Ex2500_ns and ExSierra_ns, exhibit less than half of the vertical velocity standard deviation from that of the free-slip companion simulations. The maximum vertical velocity standard deviation is in the midtroposphere and lower stratosphere just above the lee slopes in Ex2500_ns. In contrast, the maximum standard deviation in ExSierra_ns is primarily confined to the upper troposphere and lower stratosphere, where differences in the characteristics of the wave amplification and breaking among the model simulations are the dominant signatures. It is also noteworthy that the vertical velocity standard deviation maximum seems to shift to higher altitudes as a result of surface friction in ExSierra_ns, as well as Ex2500_ns, underscoring the fundamental change in the flow imposed by the no-slip lower boundary.
The representation of the vertical flux of horizontal momentum due to orographic effects is crucial for the skillful prediction of the large-scale general circulation (e.g., Palmer et al. 1986; Lott 1995, Kim et al. 2003). The momentum flux is a metric of the overall gravity wave activity, and is computed as follows:
where the primes are deviations from the two-dimensional domain average; and u and w are the horizontal and vertical wind components, respectively. Vertical profiles for each model simulation are shown in Fig. 12, corresponding to the Ex1000_fs, Ex2500_fs, Ex2500_ns, ExSierra_fs, and ExSierra_ns simulations. The profiles are generally negative with the largest magnitudes near the surface, in line with theoretical considerations. The larger near-surface negative values for the larger mountain heights are consistent with the expectation of a net drag that the topography imparts on the westerly flow.
Overall, the model results for Ex1000_fs (Fig. 12a) show less spread than in other cases, particularly if BLASIUS and COAMPSv3 are excluded. The other cases exhibit considerably larger variations among the momentum flux diagnostics. The largest magnitude of the momentum flux occurs for the high mountain free-slip simulations (Figs. 12b,d). The negative momentum fluxes are considerably larger for the free-slip simulations (Figs. 12b,d) than for the corresponding no-slip simulations (Figs. 12c,e), in qualitative agreement with previous modeling studies (e.g., Ólafsson and Bougeault 1997). The spread among the models is larger for ExSierra_ns relative to Ex2500_ns. The BLASIUS model appears to exhibit a momentum flux minimum near the tropopause and lower stratosphere for both Ex2500_ns and ExSierra_ns. The large spread in the momentum flux among the models initialized from identical initial states supports the application of stochastic parameterization approaches (Palmer 2001) to gravity wave drag representation in large-scale weather and climate models to better represent model uncertainty (Doyle and Reynolds 2008).
To better assess the time-dependent nature of the simulations, we have analyzed one set of simulations (Ex2500_fs) in greater detail based on a subset of 6 models (see legend in Fig. 13) using a 10-min time resolution. The higher time resolution output is only available for the six model subset. Figure 13 shows the characteristics of the subset mean and standard deviation of the vertical momentum flux for both the subset and entire model set. The vertical momentum flux averaged over the 4–5-h time period for each of the 6 models (Fig. 13a) exhibits considerably less spread than is apparent at the 4-h time for the full model set (Fig. 12b). This result suggests that the temporal variability may be an important component of the overall model spread evaluated at a particular time. The momentum flux standard deviation for the 6-model subset, based on the average of each model over the 4–5-h time (green curve in Fig. 13b), is actually quite small, which once again underscores the significance of the transience within the subset models. The intermodel standard deviation of the momentum flux at the 4-h time is similar to the standard deviation due to transience over the 4–5-h time period for the subset (red and blue curves Fig. 13b). However, it should be noted that several of the models not included in the subset have a relatively small-amplitude gravity wave response for Ex2500_fs (e.g., ASAM, RAMS, and UM in Fig. 5). The temporal variability for these models is the same size or more likely smaller than the other larger-amplitude models contained in the subset. Thus, given the diversity of the gravity wave response between models within the full model set, transience likely explains only a portion of the total variance. In support of this notion, the standard deviation of the vertical momentum flux for the 4–5-h time period, averaged over the subset (red curve Fig. 13b), is substantially smaller than the standard deviation computed over the entire model set at the 4-h time (black curve Fig. 13b). This suggests that although the transience does contribute to the variance, there is considerable variance among the model simulations due to the properties of the models.
To further elucidate the sensitivity of the model simulations to the turbulence parameterization and the model dynamics, additional experiments have been performed using EULAG for the same setup as Ex2500_fs. The horizontal perturbation wind components for these tests are shown in Fig. 14 at the 4-h time. The control simulation is shown in Fig. 14a. Simulations were conducted with a Smagorinsky closure (Fig. 14b) and no explicit turbulence closure [implicit large eddy simulation (LES); Fig. 14c]. The results show that the simulations in this experiment are not particularly sensitive to the turbulence parameterization. There are some details in the flow that are different, such as the downstream penetration of the windstorm (cf. Figs. 14a–c) and the structure within the wave-breaking layers. However, the overall character of the key simulation features (e.g., windstorm and wave-breaking strength, depth, upper-level breaking location, downstream response) are quite similar. A simulation conducted with WRF-ARW using a Smagorinsky closure confirmed the relative insensitivity of the simulated gravity waves to the turbulence parameterization for Ex2500_fs (not shown).
EULAG simulations conducted with a deeper upper-absorbing layer (Fig. 14d) that starts at z = 22 km, compared to the control simulation z = 25 km show that the model simulation is also relatively insensitive to the sponge layer formulation. Additional EULAG experiments using a different pressure solver and two different methods to specify the mean state potential temperature formulation yield nearly identical results as the control simulation. These results suggest that the intermodel differences are significantly larger than simulations conducted with various physics and dynamics options exercised within a single modeling system.
The simulations carried out in this study provide a perspective on the predictability of mountain waves, wave breaking, and downslope windstorms using a suite of high-resolution nonhydrostatic models applied in a two-dimensional configuration. These test cases illustrate that as the mountain height is increased beyond the 100-m baseline and 1000-m Ex1000_fs experiments, the flow response increases considerably in complexity and the model diversity becomes more significant. For example, the higher mountain experiments exhibit a strong lee-side windstorm that is present with a deep internal hydraulic-like jump downstream of the terrain. Wave breaking forms above the mountain lee slopes in the midtroposphere and in numerous layers in the stratosphere that spread perturbation energy in the upstream and downstream directions. Secondary gravity waves are generated by the wave breaking and propagate along the tropopause interface. The source of the trapping of the wave energy aloft is the vertical variation of static stability induced primarily by the stratospheric wave breaking, which is a fundamentally nonlinear phenomenon. The spread among the model simulations is quite large for these high mountain experiments, particularly for the free-slip lower boundary condition cases which exhibit vertical velocity standard deviations that are approximately twice as large as the companion no-slip experiments.
It is difficult to identify the key components of models that explain the differences among the simulations, particularly for the high-terrain experiments (e.g., Ex2500 and ExSierra). The model formulations (Table 1) differ substantially, especially related to the model numerical techniques used for time differencing and advection, as well as the vertical diffusion and boundary layer mixing. The fact that the free-slip experiments exhibit the largest differences among the simulations, suggests that the numerical techniques used in the diverse set of models play a dominant role in determining the variability, rather than the model physical parameterizations. The possibility does exist that some of the results may be influenced by specifics of the model setup (e.g., slight differences in surface drag formulations or the lateral boundary conditions); however, the model configurations were standardized as much as possible to minimize inconsistencies.
The simplifying assumptions of two-dimensionality considered here may limit the generality of the results. Future studies of mountain waves and topographic circulations should be conducted in three dimensions with realistic boundary layers to better understand the predictability implications.
Quantifying mesoscale predictability for terrain-forced flows is a formidable challenge. The results of this study build on previous two-dimensional topographical flow ensemble simulations (e.g., Doyle and Reynolds 2008) that suggest that the predictability of wave breaking, downslope windstorms, and mountain-wave-induced turbulence is limited, particularly when wave steepening or breaking and the development of shooting flow down lee slopes are essential ingredients. In this study, the 11 numerical models provide additional insight into the contribution of model error. For relatively low mountain heights in the linear regime, the spread among the simulations is small. However, the spread increases substantially for gravity waves forced by high mountains in the nonlinear regime, underscoring the uncertainties introduced by different formulations of models. Given the sensitivities to the initial state for terrain-forced flows (Doyle and Reynolds 2008; Reinecke and Durran 2009a), as well as the contributions from the model formulation, prediction of the location and timing of wave breaking and associated turbulence, which are of importance for aviation, may only be possible through probabilistic approaches.
We acknowledge the contribution of the T-REX scientists, forecasters, staff, NCAR staff, and flight crews. The first three authors acknowledge support through the Office of Naval Research's Program Element 0601153N. J. Schmidli was supported by the Swiss National Science Foundation Grant PA002-111427. ARPS is developed by the Center for Analysis and Prediction of Storms, University of Oklahoma. Brian Jamison provided invaluable assistance with the WRF-ARW runs. In the early stages of this work, Prof. Grubišić was supported by an NSF Grant ATM-0524891 to the Desert Research Institute. Ivana Stiperski acknowledges support of the Croatian Ministry of Science through Grant 004-1193086-3036 to the Croatian Meteorological and Hydrological Service. S. Zhong acknowledges the support of the National Science Foundation Grant ATM-0646299. Drs. Kirshbaum and Zhong's simulations were performed using a supercomputing grant from the National Center of Atmospheric Research, which is sponsored by the National Science Foundation. Computational resources were supported in part by a grant of HPC time from the Department of Defense Major Shared Resource Centers.
The sensitivity of mountain-wave solutions to the approximations made to remove acoustic waves from the equations of motion has been previously been demonstrated (e.g., Nance and Durran 1994; Nance 1997). The relatively rapid growth of wave amplitude with height in the BLASIUS simulations can be shown to be due to the formulation of the pressure gradient term in the anelastic equations used in this model. The BLASIUS equations can be written as
where u is the velocity, θ is the potential temperature, θ′ is the perturbation potential temperature, p′ is the perturbation pressure (to a reference, hydrostatically balanced profile), g is the gravitational acceleration, and and are the reference density and potential temperature profiles, respectively, both of which are functions of height only. In contrast, other commonly used forms of the anelastic equations involve writing the pressure gradient term as (e.g., Derbyshire et al. 1994). While the appearance of density within the derivative (rather than outside) is perhaps initially surprising, it arises from a more accurate treatment of the buoyancy term whereby the buoyancy force includes a contribution from the pressure perturbation. In the BLASIUS equation set this contribution is neglected. Note that in the frequently used Lipps and Helmer (1982) anelastic equations the gradient term in the momentum equation takes the form , where π′ is the perturbation to the Exner pressure and cp is the specific heat capacity at constant pressure. Again, unlike the BLASIUS equations, the reference-state variable appears within the derivative rather than outside it.
The consequences of adopting different forms of the pressure-gradient term in the anelastic momentum equation becomes apparent when the vertical structure equation for small-amplitude (linear) stationary mountain waves is derived. For simplicity we restrict attention to steady flow over a two-dimensional ridge and to a height-independent background flow . By splitting the velocity field into the sum of the background flow and small-amplitude perturbations, , substituting into Eqs. (A1)–(A3) and neglecting nonlinear terms, the following vertical structure equation can be obtained:
where k is the horizontal wavenumber and is the Fourier transform of the vertical velocity w′ defined as
Solutions to Eq. (A5) take the following form:
where A is a constant and . Thus, for a height-independent background flow, small-amplitude mountain-wave solutions to the BLASIUS equations will grow with height at a rate proportional to . Similarly it can be shown that when the pressure-gradient term in Eq. (A1) is written as , the vertical structure equation becomes
and the form of the second derivative in Eq. (A7) is different to that in Eq. (A4). Note that an identical equation to Eq. (A7) is also obtained for the commonly used Lipps and Helmer (1982) anelastic equations. Solutions to Eq. (A7) take the following form:
and is the density-scale height. The terms involving in Eq. (A9) are in general relatively small and result in only subtle changes to the vertical wavenumber m from that for the BLASIUS equations. However, the growth rate of the wave amplitude is significantly slower, depending as it does on rather than . We should therefore expect that in general mountain-wave solutions to the BLASIUS equations will grow more rapidly with height than those for anelastic equations where the pressure gradient takes the form or for the Lipps and Helmer equations.
COAMPS is a registered trademark of the Naval Research Laboratory.
https://journals.ametsoc.org/view/journals/mwre/139/9/mwr-d-10-05042.1.xml


The Design Business Association's John Scarrott talks to a design consultancy featured in the Apprentice about why they decided to leave the programme.
Reality TV show the Apprentice is back for a tenth series on 14 October. The show frequently features design studios, who help the candidates with various tasks such as developing new products or creating brands.
I've always been curious to know what goes on behind the scenes of the show, after all, we only see the final edited version. I did some digging and found a consultancy that has been involved with the Apprentice for the first seven series. Its principal shared with me his experience of being involved with the show.
The consultancy's involvement with the Apprentice started with the very first episode. The producers of the show found their way to them via a toy brand they had worked with. The production company came in and met with the design team and they struck up a good relationship.
The benefits of involvement for the design consultancy were clear – exposure on primetime TV and the potential for work coming out of this enhanced profile. The consultancy was also paid a contribution towards expenses for its involvement.
The initial episodes were good for the consultancy. The production team followed the designers and interviewed them at various stages of the design process. The design team was also able to present its work back to the candidates.
The designers led the process and guided the candidates through the design stage. This was featured in full in the show. At the end of series one, the consultancy was contacted with an enquiry for a piece of business, which it won. So far, so good.
But then the show's producer changed and the designers noticed a shift in emphasis begin to take the programme in a different direction. From being set up to reveal aptitude and talent, with no serious conflict, the show started to focus its attention on the personality traits of the candidates. As a result, design and branding became less important and consequently were given less coverage in the show.
The designers felt this in a number of ways, the principal says. They were expected to "turn up, produce and disappear". Their work ended up being televised as arriving by courier rather than being presented by them. By this point they were also working later and later, with deadlines getting earlier and earlier.
The consultancy's role on the show had also changed, according to the principal. They were now being clearly instructed to do what the candidates said and to withhold any and all input of their own into the final design.
In the first series they had been given the opportunity to translate the candidates' ideas from the briefs; this was now out. In fact in the filming of one episode it came to light that the consultancy had provided some of their own ideas to the candidates. This was apparently immediately deleted and re-edited with the strict instruction that whatever came out as the idea had to be the candidates own – even if it turned out to be the worst idea in the world. Actually, perhaps the worse the better to fit with the new direction of the show.
In the early days, the show was about how the designers could help the team. Now it was just about "knocking up a model", the principal says.
What began for the designers as an involvement in a business programme was turning into something else, and they were beginning to question their involvement in the project.
The treatment of the design stage seemed also to be dependent on where the product design task occurred within the series. If it took place early in the series it was still treated with some depth and given time. Closer to the end though, when it became more about the individuals, then the task felt "crammed in".
There was also an increasing financial impact to the designers' involvement in the show, which the principal says was perhaps the tipping point to the consultancy's decision to withdraw its involvement. He says the cost of their contribution to the show was was outweighing the benefit.
Each episode involved 18 people days spread over a day-and-a-half. Although a contribution was made by the show towards general expenses this did not balance up. Even when it was traded off against the media exposure for the designers (which had decreased with the change in the focus of the show) it just didn't seem worth it.
So if you're a design business and a TV production team comes knocking on your door laying fame and fortune at your feet, welcome them in, put the kettle on and maybe even offer them a chocolate biscuit. But make sure you weigh up the pros and cons carefully before you say "you're hired!".
Based on last night's episode, it's not just the design businesses that are telling Lord Sugar "You're Fired!" The candidates are taking the same approach. Maybe the nature of the selection process suggests a mismatch in cultures. In which case, no bad thing for either side.
If anyone is interested the consultancy in question is DesignWorks in Windsor. They have case studies of work produced for the show on their website.


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How Visa Delay Almost Killed My Atletico Madrid Deal: Story Of My Football Career – Yusuf Otubanjo
Oma Akatugba Posted On March 29, 2020
By- Oma Akatugba
Nigeria had just placed second after losing to Switzerland in front of local fans at the 2009 U17 World Cup. While Nigerians were gutted to have missed out on the trophy, the stars for the future were being made for bigger realisations.
It was a tournament that featured current Super Eagles players like Kenneth Omeruo, Ogenyi Onazi and Olanrewaju Kayode, and international stars like Andre Ter Stegen, Neymar, Coutinho and a host of others. There were, of course, many other players who caught the eye at the tournament without having to do a lot and one of them was Yusuf Otubanjo.
For Otubanjo, being a player of the Golden Eaglets that year only meant he needed to achieve more. They were silver medalists in an international tournament and the big contracts were expected to come so they would 'level up'. And they came knocking for him, from Madrid and Monaco.
While his chance to prove himself was hard done by a visa denial by the Spanish authorities for a year, he said he met some of those who inspired him as a footballer, and even some future stars, including Atletico Madrid's Ghanaian international, Thomas Partey.
In a chat with Omasports, Otubanjo gave a detailed breakdown of his career and how it has been all along.
Otubanjo began his story with how he met Partey as a youth player in Atletico Madrid.
"We met in Atletico Madrid at that time, I was playing for the 3rd team while he was with the under 19 . We are good friends.
"I started my professional football life with Atletico Madrid. It was God at work to have the offer.
"My story is a long story but to cut it short, just some months after the 2009 Under 17 FIFA World Cup finished, some agents from Nigeria collaborated with some Ghanaian agencies to bring in scouts from all over Europe. They opened camp in Ghana. I think that was early February 2010 bcos they were scared of Nigeria, so some of us from Nigeria joined them there for the screening.
It was a really good time, we were fresh from the under 17 games and were trying to fight hard to level up.
"To God be the glory, after all the screening, we went back to Nigeria and waited for feedback from the scouts. So a few months later, I was told two teams were interested in having me, Monaco from France and Atletico of Madrid. I was so amazed and my agent and the other agent from Nigeria were so happy.
"But to cut it short, you know Nigeria with money, they went for the one who brought in more money for me. You could guess it was Atletico. They offered more money than Monaco. What did I know then? I was just busy awaiting the day to start packing my bags for my life's career.
"The talks went well with Atletico Madrid and they decided to follow up the necessary routine for visa and so on but to my disbelief, I applied for visa throughout the whole of 2010 and all I got were denials.
"Until the team from Madrid decided to take care of all the paperwork, all the contract papers were sent down to me in Nigeria to sign, and later the embassy started calling me to bring my passport, reserve my ticket, and all whatnot
"I guess when it's time to manifest, God works like an air blowing us for free that we can't even explain how it happens. On the 4th of January, 2011 I was granted a visa and on the 11th I landed in Madrid but too bad, I got there late. Instead of playing in the second team for the Segunda division, I joined the third league team. But it was a great experience because we trained with the main team once a month.
"Imagine the first person I met was late Antonio Reyes, and my first picture was with Sergio Aguero.
In Atletico Colours
"Imagine the feeling when one trains with people you admire from way back, like De Gea, Aguero, Falcao, Thiago, Diego etc.
"I can never forget that so easily and our blood always pumping like, once we finish training, we will get signed because we train like it's trials against them."
Signing for Atletico – The Right Step?
"Sure, it was a great step in my football career. My representative in Madrid wanted me to sign with them professionally but since I was new to that, I was scared and then we had a change of management in the club and it affected my contract because there was no one to guide or speak for me. But I spent 2 seasons or one year and half-season before they freed me.
Otubanjo at Atletico . second from left in front.
"After that, I went to France to try out at club, Racing De Strasbourg. All the efforts to find a team in France did not yield any positive result. Then I got a call to move to Austria, I reached Austria at Red Bull Salzburg team on November 5th, 2012. I got there late as well and they had almost round-up for winter break
I joined Redbull Salzburg in late 2012 and later, I was on loan to the third team of a team in another city called Linz, who they had a sort of cooperation with. There was a rule that only three foreigners were allowed to play in the league and as a consequence, I didn't have much playing time with the team called Pasching FC Linz, but we managed to win the Austrian cup in 2013 with the team. It was a good moment as well.
"We participated in the Europa league qualification that year. That is a different story on it's own because I did not even dress up for any of the games. It's funny to think about it now but what can I say more. My contract with Salzburg expired and then I had some difficulties in 2014 summer. I had no team and I was registered with AMS just to have some money in the meantime and it was compulsory I attended a German class in order to get to earn my pay. So I was in the class for 3 months and one of my friend who is now my manager told me to go train with a team called Blau Weiss Linz that he can speak with the coaches. I needed a job at that time because of my residence card and luckily for me, the team gave me a chance to train with them by early September of 2014 I guess.
They decided to sign me for winter but I got a pre-contract so I can renew my residence. I was the happiest person on earth again after all the struggle that year. I joined the team fully in winter 2015 with six months and options of a year contract in favour of the team.
Yusuf Otubanjo (LASK) and Martin Rasner (SKN St. Pšlten) during an Austrian Bundesliga-clash between SKN St. Pšlten and LASK .
FOTO: APA/HERBERT P. OCZERET
"Just like a welcome back of my life. In just pre-season games that year, I scored 15 goals which equalled all the goals their main striker scored in the entire season. I don't have to say that but life is sometimes funny. We started the season and I ended up scoring 28goals in 30 games or so.
Winning the regional Liga for my team in 2015/2016 was a memory you can't ignore in my career.
"I was so happy to take the team from 3rd league to the second league of Austria. It's holiday time, 2016 summer, I tried out at with 2 to 3 sides of the first top league in the country.
"The coaches of all the teams were impressed but what happened to signing me? I never heard from any of them all like there was something wrong somewhere.
"I Got married in June 2016 and then received an offer from my manager that a team from Slovakia, Msk Zilina was interested and ready to sign me. I rushed back to Austria and got set for Slovakia. The journey of my top life football begins again with Msk Zilina. Zilina was a great choice for me, the begining of the season was so amazing. I scored in every game until an injury kicked in.
"I was out for a while but back again and we kicked the team to champions in just a season and made a record for the team. We won the league that the club last won five years before. Too much juice and too much sauce (laughs).
"We became champions of Slovakia and I was ready for my first ever Champions League qualifications in 2017. We lost in the second round of the Playoffs against FC Copenhagen, Denmark. Lost 1 -3 at home and lost 1-2 away.
YUSUF OTUBANJO (BLAU WEISS LINZ) ,FOTO:FOTO LUI
"I was soon loaned by Zilina after some issues and I went to Altach FC in Austria for 6 months. From there, I went to Lask FC because I didn't want to go back to Zilina. So I joined LASK in the summer of 2018 on a 3-year contract. The first season and a half were not too bad, till we changed coach last year summer, and playing time became hard to come by. It was a bad that i hardly made the bench for the coach. So I decided to go on loan this winter. I'm now with Ararat FC in Armenia on loan till summer 2020.
Life is a journey and while on this journey, you are going to encounter so many rough patch like Nigerian roads (laughs) but you have to keep going with your head help up high. I am happy that I still have the chance to write my story and make the best out of my career. I thank God for everything and my wife who has been a super pillar for me in all the struggle so far.
Oma Akatugba
I could not afford summer clothes and I had to cut my jeans bought from Nigeria, and that time, Milan was so hot. Nobody gave me a dime but I didn't give up. - Henty Ezekiel recounts AC Milan journey

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California has been experiencing some of the direst years on record, with the state only receiving less than 60 percent of average precipitation after three years of drought conditions. This means that current that current state reservoirs are only at 36% capacity. The city of Los Angeles, with help from Mayor Eric Garcetti, has been leading the charge in water conservation efforts. For nearly 40 years LADWP's Water Conservation Program has kept demand flat despite a population increase of one million people. In October 2014 Mayor Eric Garcetti issued an executive directive to reduce per capita potable water 20% by 2017.
The "Cash-In-Your-Lawn" program has been a huge success throughout the city, replacing over 9 million square feet of turf saving over 300 million gallons of water. Before, the program only replaced lawns that weren't dead or dying, but because of the success of the program LADWP and MWD have modified the program to allow customers to replace those lawns. LADWP and MWD hope that this extension of the program will encourage more Angelenos to support water sustainability and learn the importance of water conservation.


One Mile Lane area neighbor Jason Bour questions why Smyrna officials approved The Meadows subdivision while leaving road maintenance up to the county.
SMYRNA — One Mile Lane area neighbor Jason Bour questions why Smyrna officials approved The Meadows subdivision for 216 homes while leaving road maintenance up to the county.
"The problem with the city is they only think about growing without considering the impacts," Bour said during an interview from his backyard. "If the city puts more stress on One Mile Lane, it should be the city's responsibility to improve One Mile Lane."
The Town Council in late spring annexed the 74.3 acres for the development along the northwest corner of the One Mile Lane and Baker Road intersection, Smyrna Planning Director Kevin Rigsby said.
"Both of those roads are county roads," said Rigsby, who serves a fast-growing town with more than 48,000 people. The developer "will be making improvements to One Mile Lane as a part of the development that will include turn lanes into the development and at the intersection with Baker Road."
One Mile Lane helps many commuters heading to an Almaville Road that provides access to Interstate 24, a Nissan Drive that leads to the automobile factory and other employers, and a Stewarts Creek schools campus serving around 4,000 students from prekindergarten through 12th grade.
A project traffic study shows that The Meadows will increase daily vehicle trips to 1,171 for One Mile Lane and 781 for Bake Road, County Engineer Mike Hughes said.
Much of the school traffic build-up along One Mile Lane could be relieved if the Tennessee Department of Transportation agreed for a traffic signal to be installed at the Almaville Road intersection, County Highway Superintendent Greg Brooks said.
"I really think a signalized intersection right there would be a huge improvement," said Brooks, who noted how the county engineer is also seeking the traffic signal. "We don't have any immediate plans. We are aware that there are additional needs in that area."
TDOT has no plans for a traffic signal at Almaville Road and One Mile Lane at this time, spokeswoman Kathryn Schulte said.
"Signals are owned and operated by the city or county in which they are located, but sometimes TDOT includes the installation as a part of a project, then turns the signals over to the local government," Schulte said. "Signals can be installed via a safety project, but at this time our Project Safety Office does not have any projects at this location and has not received any requests from local officials to study the area."
Although Brooks has no immediate plans for One Mile Lane, his department has improved nearby Baker, Bass and Blackman roads by resurfacing them and adding shoulders to each side that are about 2 ½ feet wide.
Smyrna Town Councilman Tim Morrell touted how the developer of The Meadows presented a traffic study for his government and the county engineer to review for approval.
The study addresses turn lanes needed for the subdivision "but not other recommendations for any additional improvements," said Morrell, who also serves as the vice chairman of the Smyrna Planning Commission.
The traffic study showed that a left-hand turn lane should be added on One Mile Lane at Suffield Drive between an existing subdivision and The Meadows. Dedicated left and right turn lanes at the east end of One Mile Lane at the Baker Road and a left-hand turn lane on Baker Road at the intersection would be added in the second phase of the development, Hughes said.
The town government previously considered annexing the One Mile Lane area subdivisions around 2005 when a previous residential development was proposed for the land in question. Town officials and the developer backed down when residents complained about forced annexation.
Since then, a new state law prohibits forced annexation. The Town Council has the option to annex the right of way for One Mile Lane but has no plans to do so at this time, Rigsby confirmed.
"As far as private land, the town would have to get consent via an owner's request for annexation or a referendum could be held (to allow a majority of property owners to decide)," Rigsby said.
Morrell says the previous annexation law that included city and county government approval was a better way to plan for growth to prevent people from driving through a changing mix of county and city roads to reach subdivisions.
"There was an orderly annexation law, and state legislators came in and in their infinite wisdom decided to do away with that," Morrell said.
Most Smyrna subdivisions are typically on roads that are a part of the town, but there are a few others on county roads, Rigsby said.
The Meadows subdivision plans came from Tim McClure, the president of Murfreesboro-based Vision Development, and he obtained designs by Steve Steele, a Smyrna resident and partner of Huddleston-Steele Engineering in Murfreesboro.
McClure said he plans to build 55 homes in the $350,000 to $400,000 range that are at least 2,400 square feet. The remaining 161 homes will be 1,850 square feet and in the $275,000 to $325,000 range.
"They will be all masonry brick, stone homes," said McClure, who confirmed that the houses will get Smyrna sewer from the back side of the property. "The development will be surrounded by the nice black painted wooden fencing with a backdrop of nice trees all the way around it and have custom mailboxes and street lights."
McClure said he has contracts with builders for all 216 lots and expects all of the homes to be built in about three years.
"Ninety percent of the builders are hometown builders," McClure said.
One Mile Lane area resident Dan Coleman said he worries about the added traffic, especially from trucks.
"I like it the way it was, but that's not my call," Coleman said. "It can get a little crowded."
Fellow neighbor Bour wishes the town would add a bike lane to One Mile Lane.
"It would be of benefit to us who are negatively impacted," said Bour, who shares his home with his wife, Kris. "We're seriously considering moving because of increased traffic. We moved out here because it's nice and quiet. If we wanted to live in the city, we would have bought land in the city."