Quantifying the Impact of Land Use and Land Cover Change on Moisture Recycling With Convection-Permitting WRF-Tagging Modeling in the Agro-Pastoral Ecotone of Northern China

Land use and land cover change (LUCC) can influence the regional atmospheric water budget. In this study, the Weather Research and Forecasting model embedded with evapotranspiration (ET)-tagging (WRF-tagging) is used to investigate the atmospheric pathways of ET as well as where and to what extent ET returns as precipitation (P) in the agro-pastoral ecotone of northern China (APENC). First, we updated the default land use and vegetation indices in the WRF-tagging with high-resolution and real-time datasets. WRF-tagging modeling reproduces the spatial distribution of P and ET reasonably after updating surface characteristics. Second, we analyzed and quantified the contribution of ET to atmospheric moisture and regional P in the APENC. The water vapor originating as ET is advected in the atmosphere below 600 hPa to hundreds of kilometers by the prevailing winds. Moisture recycling shows that 5.83% of P comes from local ET during the growing season in the core region of the APENC. Furthermore, to quantify the impact of LUCC on moisture recycling, we designed two different vegetation scenarios (Afforestation and Degradation) by changing land use and vegetation indices in the model. Results show that the precipitation recycling ratio increased to 6.31% in the Afforestation scenario, and decreased to 5.19% in the Degradation scenario, demonstrating the non-neglectable positive feedback of vegetation on P. An analysis of land surface-precipitation feedback processes indicates that the LUCC-induced change in precipitation efficiency dominates P changes. Our findings highlight the importance of LUCC on local and regional moisture recycling in the APENC.Plain Language Summary Moisture recycling is defined as the contribution of moisture from terrestrial surfaces to local and remote precipitation. Based on a regional climate model embedded with a water vapor tracer, we investigated how vegetation changes affect regional atmospheric moisture cycling in the agro-pastoral ecotone of northern China. Results indicate evapotranspiration makes non-negligible contributions to local and regional precipitation. Surface vegetation change affects the thermodynamic processes and the associated atmospheric responses. Our results show that afforestation increases local and downwind recycled P by intensifying regional moisture recycling, while degradation shows the opposite effect.