characterization of both horizontal and vertical distribution of aerosols are important for simulating the dust impact on TC development [Zhang 2007; 2009; et al., Min et al., Wang et al., 2009; 2012]. AlizadehChoobari et al., The Saharan Air Layer (SAL), which is the warm, dry and often dusty Saharan air mass advected over the cooler and humid marine air mass over the Atlantic [Karyampudi and Carlson, 1988], impacts tropical cyclone formation through multiple pathways [Jenkins 2008]. et al., Baroclinicity associated with the Saharan Air Layer (SAL) enhance development of African Easterly waves [Karyampudi 1988]. The SAL also enhances cyclonic vorticity and and Carlson, positive vorticity advection [Karyampudi 2002] and has a positive impact on tropical and Pierce, cyclone formation and development. On the other hand, enhancement of atmospheric stability and wind shear due to SAL negatively impact the formation and development of tropical cyclones [Dunion 2004]. Over larger timescales, reduction of sea surface and Velden, temperature due to dust radiative forcing has a negative impact on tropical cyclone genesis [Lau 2007]. Horizontal thermal gradients are tied to all these important dynamical features and Kim, of the SAL and thus the realistic specification of dust spatial distribution is important. MODIS derived aerosol products provide good constraints on the horizontal spatial distribution and also column dust loading. However, vertical distribution of aerosols is also important as the transport behavior varies drastically depending upon the vertical placement of dust [Karyampudi and 1988; 2012] with aerosols in the free atmosphere being Carlson, Alizadeh Choobari et al., transported long distances. Thus, aerosols in the free atmosphere have longer lasting radiative impact compared to those in the PBL with shorter life time. Furthermore, dust layers in the free atmosphere can have a much greater cooling effect on the surface than low-level dust layers [e.g. 2004] as the atmospheric heating due to the absorbing dust is unlikely to be Chung and Zhang,
characterization of both horizontal and vertical distribution of aerosols are important for simulating the dust impact on TC development [Zhang et al., 2007; Min et al., 2009; Wang et al., 2009; AlizadehChoobari et al., 2012]. The Saharan Air Layer (SAL), which is the warm, dry and often dusty Saharan air mass advected over the cooler and humid marine air mass over the Atlantic [Karyampudi and Carlson, 1988], impacts tropical cyclone formation through multiple pathways [Jenkins et al., 2008]. Baroclinicity associated with the Saharan Air Layer (SAL) enhance development of African Easterly waves [Karyampudi and Carlson, 1988]. The SAL also enhances cyclonic vorticity and positive vorticity advection [Karyampudi and Pierce, 2002] and has a positive impact on tropical cyclone formation and development. On the other hand, enhancement of atmospheric stability and wind shear due to SAL negatively impact the formation and development of tropical cyclones [Dunion and Velden, 2004]. Over larger timescales, reduction of sea surface temperature due to dust radiative forcing has a negative impact on tropical cyclone genesis [Lau and Kim, 2007]. Horizontal thermal gradients are tied to all these important dynamical features of the SAL and thus the realistic specification of dust spatial distribution is important. MODIS derived aerosol products provide good constraints on the horizontal spatial distribution and also column dust loading. However, vertical distribution of aerosols is also important as the transport behavior varies drastically depending upon the vertical placement of dust [Karyampudi and Carlson, 1988; Alizadeh Choobari et al., 2012] with aerosols in the free atmosphere being transported long distances. Thus, aerosols in the free atmosphere have longer lasting radiative impact compared to those in the PBL with shorter life time. Furthermore, dust layers in the free atmosphere can have a much greater cooling effect on the surface than low-level dust layers [e.g. Chung and Zhang, 2004] as the atmospheric heating due to the absorbing dust is unlikely to be
PART1-07102013-arn-JGR-Part1WRF.docx