HR: 17:45h
AN: H22H-08    [PDF]
TI: Flooding Estimates from Aqua Microwave Observations
AU: * Lambrigtsen, B
EM: lambrigtsen@jpl.nasa.gov
AF: Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, 91109 United States
AB: A new method to derive estimates of flooding from centimeter-wave satellite based passive microwave observations, with an example from the Aqua Advanced Microwave Sounding Unit (AMSU-A), is described. The observed effect, a deep depression in observed brightness temperatures of flooded land areas compared with dry land, is caused by a very large difference in surface emissivity between the two cases, on the order of 0.5 at wavelengths of a centimeter. Then the surface brightness, i.e. the product of skin temperature and surface emissivity, is much lower for a land surface covered by standing water than for dry land. Two methods for deriving estimates of the areal extent of flooding are discussed. The first is a differential method, which uses repeat overpasses of the same area to determine the apparent cooling, largely due to changes in the emissivity. The second uses the observed brightness temperature and instrument characteristics to estimate the amount of surface covered by water within each field of view. As an example we discuss the flooding caused by Tropical Storm Isidore, which made landfall on the Louisiana coast on September 26, 2002 and proceeded north-northeastward while precipitating heavily and causing extensive flooding in the region. Preliminary AMSU-derived flooding estimates are compared with rainfall totals and flooding estimates derived from Quickscat observations. The method will be extended to other satellite microwave radiometers operating at centimeter wavelengths, such as the Aqua AMSR-E, the DMSP SSM/I, and others.
DE: 1821 Floods
DE: 1894 Instruments and techniques
DE: 3360 Remote sensing
SC: Hydrology [H]
MN: 2003 Fall Meeting