Field of the Invention
This invention relates to method a and system for estimation of rainfall intensity in mountainous area using satellite radar.
The determination of rainfall distribution in a land area, particularly, in a mountainous area is essential for flood analysis and to estimate potential water resources.
Currently, however, rainfall observation in mountainous areas can best be carried out by relying upon point-observation using ground rain gauges installed at a limited number of points along valleys or plane-observation using ground rainfall radar, where the radar beam propagates at a level as high as several kilometers above the mountain peak. This is true even in an area provided with a highly efficient ground rainfall observation network.
Under these circumstances, it is extremely difficult to determine the spatial distribution of rainfall in a mountainous area.
In view of the problem as has been described above, it is a principal object of this invention to provide a method for estimation of rainfall distribution based on spatial distribution of rainfall in mountainous area and a system used to carry out this method.
The object set forth above is achieved by the method and the system for estimation of rainfall distribution in mountainous area comprising means as will be described below.
Specifically, the system according to this invention comprises a rainfall intensity output means adapted to output a rainfall intensity R as a linear function of altitude H: R(H)=aH+b, and a processing means adapted to identify parameters a and b in the above estimate equation by regression analysis using a measurement value obtained by rainfall vertical distribution.
With this system, the rainfall intensity R is estimated as a linear function of altitude H: R(H)=aH+b where the constants a and b are identified by regression analysis using a vertical distribution of rainfall obtained by satellite radar.
The regression analysis may be carried out using the vertical distribution of rainfall obtained at a level lower than the bright band altitude in order to improve the accuracy of the estimate equation.
Rainfall radar launched on a TRMM/PR satellite is useful for this purpose.