Cloud Liquid Water Path Retrieval Products over the Pacific Ocean and Their Climate Change Characteristics

Based on the multi-year brightness temperature observation data of the AMSU-A (Advanced Microwave Sounding Unit-A) on the polar-orbiting satellite NOAA-15, a product of cloud liquid water path on the global ocean has been established and compared with ERA5 and FNL/NCEP. We analyzed the ability of retrieval products to reproduce the climate change characteristics of cloud liquid water path, and further analyzed the linear and nonlinear climate change trend characteristics of cloud water path in the Pacific region through linear regression and EEMD (Ensemble Empirical Mode Decomposition) methods. The results show that the CLWP (Cloud Liquid Water Path) inversion data can well reproduce the average spatial distribution characteristics of the years and the corresponding climate change trend. The CLWP climate trend shows obvious latitude zone characteristics, and the increasing and decreasing trends appear with the latitude zone interval. Moreover, in the eastern Pacific region of the northern hemisphere, the latitude zone characteristic of the climatic trend of the CLWP has a phenomenon of migration northward. In contrast, the climatic trend of the inversion product has better similarity with the ERA5 reanalysis data. While the latitude zone characteristics of the trend, especially the northward movement of the latitude zone characteristics, cannot be reproduced well by the FNL data. It is characterized by a decrease in water vapor in the equatorial region, and a significant increase in cloud liquid water paths on both sides.