Retrieval of atmospheric and ocean surface parameters from ADEOS-II AMSR data : comparison oferrors of global and regional physical-based algorithms

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Retrieval of the total atmospheric water vapor content V, total cloud liquid water content Q, the seasurface wind speed W and sea surface temperature t_s from the simulated ADEOS-II Advanced Microwave Scannning Radiometer (AMSR) data in the absence of precipitation is considered. The brightnesstemperatures (T_<Bs>) with the vertical (V) and horizontal (H) polarizations at the AMSR frequencies of 6.9, 10.7, 18.7, 23.8 and 36.5 GHz were computed for the radiosonde and relevant data collected by research vessels. V and Q were retrieved from T_B (23.8V) and T_B (36.5V) with thephysically based "global" (-1.6 < t_s = < 31 ℃), "polar" (t_s = < 15℃) and "tropical" (t_s > = 24℃)algorithms under the assumption that t_s values were derived from the measurements at 6.9 and 10.7 GHz withan error σ _<ts>. The errors σ v and σ Q were estimated at several combinations of the difference △T36 = T_B (36.5V) - TB (36.5H), radiometer noises △T and σ _<ts>. At △ T36 = 35K, △T = 0.3K and σ _<ts> = 1℃, σ v = 1.5 kg/m^2 and σ _Q = 0.029 kg/m^2 for a global algorithm. Standard regression techniques were applied to retrieve ts and W from the simulated T_<Bs> at all channels. A combination of T_B (6.9V), T_B (6.9H), T_B (10.7V) and[T_B (10.7V)]2 yields the minimum ts and Werrors eaual to 0.42 and 0.7℃, and 0.67 and 0.85 m/s as radiometer noises increase from O.1 to 0.2 K at ν = 6.9 GHz and from 0.13 to 0.27 K at ν = 10.7 GHz.