As one of the major anthropogenic ways of changing land-use, irrigation is considered to strongly modulates regional hydroclimate. Irrigation directly triggers surface colling and rising evapotranspiration, which has been considered as the preliminary local effect. But the subsequent interactions with the background climate are highly nonlinear, introducing diverse and unexpected consequences. North China Plain (NCP) is one of the regions with the most rapidly expanded irrigation since the twentieth century. The scarce rainfall in northern China gives rise to the necessity for irrigation to supplement the soil water. In this study, we quantify the effect of irrigation on the regional climate in China. We adopt two state-to-art regional climate models, WRF4.3 and RegCM4.7, to mimic the l...[ Read more ]

As one of the major anthropogenic ways of changing land-use, irrigation is considered to strongly modulates regional hydroclimate. Irrigation directly triggers surface colling and rising evapotranspiration, which has been considered as the preliminary local effect. But the subsequent interactions with the background climate are highly nonlinear, introducing diverse and unexpected consequences. North China Plain (NCP) is one of the regions with the most rapidly expanded irrigation since the twentieth century. The scarce rainfall in northern China gives rise to the necessity for irrigation to supplement the soil water. In this study, we quantify the effect of irrigation on the regional climate in China. We adopt two state-to-art regional climate models, WRF4.3 and RegCM4.7, to mimic the large-scale irrigation practiced in NCP. Several sensitivity tests with different irrigation forcings are also conducted to verify the relationship between irrigation and regional climate. Our experiments conclude a consistent cooling repression and moistening effect centered at NCP all year round from all experiments. Although the moisture budget and wind field pattern visualize the vertical downdraft and low-level divergence which could inhibit rainfall, the humidifying particularly dominant the climate responses in the dry May and increases precipitation significantly and consistently in northern China including NCP. The lifting MSE and CAPE imply that additional water frequently triggers light rains convectively by destabilizing the atmosphere. Our relative niche results may build a foundation for future analysis of less model-dependent and more systematic irrigation impacts that incorporate more anthropogenic activities such as groundwater depletion.