Improving over Land Precipitation Retrieval by High-Temporal Resolution Satellite Observations

Current microwave precipitation retrieval algorithms utilize the instantaneous brightness temperature (TB) to estimate precipitation rate. This study presents a new idea that can be used to improve existing algorithms: using TB temporal variation (ΔTB) from the microwave radiometer constellation. As a proof of concept, microwave observations from multiple polar-orbiting satellites are utilized to derive ΔTB. Results show that ΔTB correlates more strongly with precipitation rate than the instantaneous TB. Particularly, the correlation with precipitation rate improved to −0.6 by using ΔTB over the Rocky Mountains and north of 45°N, while the correlation is only −0.1 by using TB. The underlying reason is that ΔTB largely eliminates the negative influence from land surface emission. This study implies that high temporal resolution satellite observations can significantly improve precipitation retrieval performance.