A simplified split-window method for retrieving precipitable water over land area using Advanced Very High Resolution Radiometer

摘要

Some retrieval methods for estimating the atmospheric precipitable water (PW) were reviewed in the study. Then, an improved physically algorithm for the retrieval of PW over cloud-free land surfaces based on the split-window covariance-variance ratio technique (SWCVR) was proposed. The thermal infrared split window channels at 11 and 12 µm of the Advanced Very High Resolution Radiometer(AVHRR) instrument were used. The improved method for estimating the PW is simplified, which is based on a linear relationship between the PW and the ratio of the two split-window channel transmittances (τ12/τ11). The new PW retrieval algorithm was tested with the comparisons from both AVHRR and radiosonde observations in some places of South China. The preliminary results show that the algorithm proposed for estimating PW is acceptable since a RMSE of 0.44 cm is obtained.