TY - JOUR
AU - Deblonde, Godelieve
AB - The direct assimilation of brightness temperatures (Tb’’s) from the Defense Meteorological Satellite Program Special Sensor Microwave Imager (SSM//I) and Special Sensor Microwave Water Vapor Profiler (SSM/T-2) in a one-dimensional variational (1D-Var) assimilation system is studied over the oceans. The control variables of the 1D-Var are the natural logarithm of specific humidity (ln q ), near-surface wind speed (SWS), and cloud liquid water (CLW) path. Synthetic Tb’’s, with and without noise added, were simulated and used to estimate the strength of the 1D-Var assimilation (weight given to the observations) and the information content of the Tb. In clear skies, it is shown that except for very dry profiles (TPW < 5––6 kg m −−2 ) SSM//I Tb’’s are superior to the SSM/T-2 Tb’’s for the determination of total precipitable water (TPW). In the presence of clouds, the SSM/T-2 TPW retrievals are underestimated and the underestimation increases with CLW. Cloudy profiles should be filtered out. It is also shown that the SSM//I 1D-Var retrievals for low wind speeds are erroneous (<2––3 m s −−1 ) and so are retrievals of low CLW (<0.1 kg m −−2 ). Otherwise, SSM//I Tb retrievals of TPW, SWS, and CLW perform well. 1D-Var analyses using bias-corrected observed Tb’’s were also computed for the same case as that using synthetic Tb’’s and were compared with retrievals obtained using published regression equations. When both SSM//I and SSM/T-2 Tb’’s were assimilated simultaneously (in collocation) in the 1D-Var system, the retrievals of TPW, SWS, and CLW were very similar to those when only SSM//I Tb’’s were assimilated. However, the SSM/T-2 Tb also provided specific humidity information in the upper troposphere.
TI - Variational Retrievals Using SSM/I and SSM/T-2 Brightness Temperatures in Clear and Cloudy Situations
JF - Journal of Atmospheric and Oceanic Technology
DO - 10.1175/1520-0426(2001)018<0559:VRUSIA>2.0.CO;2
DA - 2000-02-21
UR - https://www.deepdyve.com/lp/american-meteorological-society/variational-retrievals-using-ssm-i-and-ssm-t-2-brightness-temperatures-BJMCsOvmnT
SP - 559
EP - 576
VL - 18
IS - 4
DP - DeepDyve
ER -