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Impact of historical land‐use changes on the Indian summer monsoon onset
Author(s) -
Yamashima Ryoji,
Matsumoto Jun,
Takata Kumiko,
Takahashi Hiroshi G.
Publication year - 2015
Publication title -
international journal of climatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.58
H-Index - 166
eISSN - 1097-0088
pISSN - 0899-8418
DOI - 10.1002/joc.4132
Subject(s) - wet season , climatology , monsoon , precipitation , atmospheric circulation , environmental science , surface runoff , geography , atmospheric sciences , geology , meteorology , ecology , biology , cartography
We investigate the impact of historical land‐use changes (HLUCs) from 1700 to 1850 on the onset of the Indian summer monsoon (ISM), focusing on the onsets of broad‐scale ISM circulation and the local rainy season and their relationships, by conducting three equilibrium experiments under 1700, 1850, and 1992 conditions. During that time period, land use changed from primarily forest to cropland in India, eastern China, and Europe. This study used an atmospheric general circulation model, Model for Interdisciplinary Research on Climate version 3.2, coupled with a land surface scheme, Minimal Advanced Treatments of Surface Interaction and Runoff. The results showed that HLUC decreased rainfall amounts by more than 2 mm day −1 during the onset phase and delayed the onset date of the local rainy season by approximately four pentads over the Indian subcontinent. The onset date over southeastern China was also delayed by four pentads. The changes in precipitation and the onset of the local rainy season result from the change in the surface water budget induced by HLUC, as discussed in previous work. Although ISM circulation activity, defined by a large‐scale land–sea thermal contrast, was slightly decreased from late May to early June, its onset date did not change. Thus, in the onset phase, HLUC affected the local rainy season onset over the same region, although the ISM circulation was weakened only marginally, showing no change in its onset timing. Hence, unlike the broad‐scale ISM circulation onset, the beginning of the local rainy season is dominantly influenced by local surface conditions.