Tosiyuki Nakaegawa
Received 2016/11/08, Accepted 2016/12/17, Published 2017/02/08

Tosiyuki Nakaegawa1)

1) Meteorological Research Institute

Simple explanations for changes in surface soil moisture in the late 21st century under global warming were explored, based on statistical significance and without consideration of complicated mechanisms. The results of a multi-model ensemble (MME) analysis showed significant increases in surface soil moisture in one northwestern inland area, and significant decreases were projected in two inland areas in southern and northern China. Among three water flux variables, precipitation (P), evaporation (E), and total runoff (R), significant changes in E explained only 10% of the total area showing significant changes in surface soil moisture. Among three combinations of two water flux variables, (P – E), (E + R), and (P – R), significant changes in (P – E) were dominant in coastal northeastern China, but this area did not overlap with areas with significant changes in surface soil moisture. Individual analyses revealed that significant increases in E, (P – R), and (E + R) explained 26%, 13%, and 9%, respectively, of the total area showing a significant decrease in the MME mean surface soil moisture. This result indicates that reliance on the MME mean may hinder understanding of the geophysical mechanism linking water flux variables with surface soil moisture.

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