Evaluation of soil moisture-precipitation feedback at different time scales over Asia

摘要

The soil moisture-precipitation (SM-P) feedback process can affect the water and energy cycles at local to regional scale, subsequently affecting the water distribution in space and time. This study investigates SM-P feedback at different time scales over Asia during boreal summer season based on the covariation between SM and P. In this article the positive (negative) feedback means positive (negative) statistical correlations between SM-P. This is based on the statistical relationship and do not reflect physical process associated between SM and P. The Global Land Data Assimilation System (GLDAS) data, Climate Forecast System Reanalysis (CFSR) data and regional climate model, version 4 (RegCM4) simulations are adopted for analysis in this study. The results indicate a negative SM-P relationship at a seasonal time scale over mid-high latitudes of the study area whereas a positive but weak and spatial scattered correlation pattern is observed at the interannual time scale. A positive relationship is diagnosed over India, Indochina, and southeast China regions at seasonal (though weak) and interannual time scales. The positive and/or negative SM-P correlation patterns observed at different time scales depends on the memory associated with seasonal precipitation and soil moisture. The strength of the SM-P relationship seems to be influenced by the threshold behaviour of soil moisture, especially at the interannual time scale. This indicates that beyond a certain threshold in soil moisture anomalies likely to have significant influence on precipitation.