The positive climate impacts of drip irrigation underneath plastic mulch on a typical Mountain-Oasis-Desert System in northwest China

Drip irrigation underneath plastic film mulch was extensively applied to mitigate water scarcity in oasis agroecosystems over arid northwest China. However, the local climate effects induced by the agricultural practice were still not appraised clearly, especially from the perspective of the Mountain-Oasis-Desert System (MODS), a basic landscape configuration widely formed in northwest China. In this study, a drip irrigation underneath plastic mulch scheme was developed within the land surface model, SURFEX, and the regional climate effects during summer were further explored by coupling the regional climate model ALARO to the modified SURFEX during 2009-2018. From a comparison to the local observations, the revised regional climate model was substantially improved in simulating lower boundary layer properties including sensible and latent heat fluxes, surface air temperature, and soil temperature, though neutral impacts were found on some variables, including ground heat fluxes and precipitation. The drip irrigation practice could reduce the climatological-mean temperature by about 3.73 +/- 0.14 degrees C over the oasis areas, while the implementation of plastic mulch weakened such irrigation-induced cooling effect marginally by about 0.2 degrees C. Besides, irrigation had limited influences on precipitation over oasis areas, but enhanced it remotely at the mid-mountain areas with a value of similar to 15 mm during summer. Additionally, the plastic mulch had marginal impacts on precipitation with a value of 2.86 mm/summer. Overall, these results suggest a positive climate feedback for mitigating climate warming and strengthening the local hydrological cycle in MODS by using drip irrigation underneath plastic mulch in northwestern China.