Potential impacts of wintertime soil moisture anomalies from agricultural irrigation at low latitudes on regional and global climates

• Published in: Geophysical Research Letters
• Main Authors: Wey, Hao‐Wei, Lo, Min‐Hui, Lee, Shih‐Yu, Yu, Jin‐Yi, Hsu, Huang‐Hsiung
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: eScholarship, University of California 2015
• Subjects: Climate Action; Meteorology & Atmospheric Sciences; Pacific; aleutian low
• Online Access: https://escholarship.org/uc/item/9h30b4w0; https://escholarship.org/content/qt9h30b4w0/qt9h30b4w0.pdf; https://doi.org/10.1002/2015gl065883

Anthropogenic water management can change surface energy budgets and the water cycle. In this study, we focused on impacts of Asian low-latitude irrigation on regional and global climates during boreal wintertime. A state-of-the-art Earth system model is used to simulate the land-air interaction processes affected by irrigation and the consequent responses in atmospheric circulation. Perturbed experiments show that wet soil moisture anomalies at low latitudes can reduce the surface temperature on a continental scale through atmospheric feedback. The intensity of prevailing monsoon circulation becomes stronger because of larger land-sea thermal contrast. Furthermore, anomalous upper level convergence over South Asia and midlatitude climatic changes indicate tropical-extratropical teleconnections. The wintertime Aleutian low is deepened and an anomalous warm surface temperature is found in North America. Previous studies have noted this warming but left it unexplained, and we provide plausible mechanisms for these remote impacts coming from the irrigation over Asian low-latitude regions. Key Points Model simulation without considering irrigation underestimates ET over Indo-Gangetic Plain Irrigation at Asian low latitudes has the potential to induce PNA teleconnection Irrigation results in interhemispheric thermal gradient, thereby modifying Pacific subtropical jet