Estimation of cloud liquid water over oceans from dual oxygen absorption band to support the assimilation of second generation of microwave observation on board the Chinese FY-3 satellite

ABSTRACTTo make up for the absence of observation-based information of cloud liquid water (CLW) in assimilation of second generation of microwave observation on board the Chinese FengYun-3 satellite, two algorithms using double oxygen-absorption band microwave sounding observation at 52.80 and 118.75 ± 2.5 GHz, one using brightness temperatures directly and the other utilizing a cloud emission and scattering index derived from the brightness temperature, are proposed to estimate CLW over oceans. Their performance was evaluated by verifying the estimations from FY-3C double oxygen absorption band microwave observations and that from the traditional Grody scheme applied to microwave measurements at 23.8 and 31.4 GHz from the MetOp-B satellite. An additional experiment was conducted to investigate the impact of regression analysis on the actual brightness temperature and reanalysis data, or the simulated measurements. It is demonstrated that CLW can be retrieved from double oxygen absorption band microwave s...