Characterizing Long-term Global Terrestrial Water Storage Change based on Reanalysis Data with Three Methods

Suxia Liu^a，b，Shanshan Deng^a，b, ,Xingguo Mo ^a，b

^a Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy Sciences, Beijing 100101, P. R. China，^bCollege of Environment and Resources/Sino-Danish Center, University of Chinese Academy of Sciences, Beijing 110049, China.

Abstract

Long-term terrestrial water storage change (TWSC) helps better understanding the interaction of climate change and anthropogenic activities but is still in shortage. This study constructed a long-term globally-distributed TWSC series by using three methods including the terrestrial water-balance method (PER), the combined atmospheric and terrestrial water-balance method (AT), and the summation method (SS). Three reanalysis data (NCEP/DOE II, ERA-Interim and Japanese-55) were employed. Results show the estimates with SS method have highest consistency with GRACE in time and space among three methods during the period of 2002-2014. And the estimates with PER/AT methods fail in reconstructing the inter-annual TWSC due to the uncertainty in relevant variables like precipitation and imbalances in terrestrial/atmospheric water budget of reanalysis. The estimates with AT methods in regions under desert and tundra climate are notable inconsistent with GRACE due to the difficulty in simulating relevant atmospheric data in those regions. There are non-negligible biases in amplitude and global distribution of estimates with SS method for losing sight of groundwater and anthropogenic influence and this bias is required to be corrected before applying, which are the results in our next work.