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Precipitation is a crucial influencing factor in the global hydrological cycle and terrestrial ecosystems. Previous studies have mostly focused on the historical precipitation variations over the Tibetan Plateau (TP). However, little attention has been given to the differences between convective and stratiform precipitation under future climate change scenarios. In order to acquire the high‐resolution precipitation information over the TP, the dynamical downscaling simulation was conducted utilizing a regional climate model (Weather Research and Forecasting [WRF] model) forced with a global climate model (Community Climate System Model [CCSM]). In this study, we focus on projections of future changes in convective and stratiform precipitation over the TP. The downscaling results during a 26‐year period 1980–2005 are compared for dry season, wet season and annual mean precipitation against the gridded observation dataset. Then, the changes in the wet season convective and stratiform precipitation with warming between CCSM and WRF‐CCSM were compared in the future period 2070–2099 under two scenarios (RCP4.5 and RCP8.5). Compared with the coarse‐resolution forcing, the historical precipitation of dry season, wet season and annual mean over the TP were found to better reproduce in WRF‐CCSM simulation. WRF‐CCSM projects an opposite spatial pattern of total precipitation change between the northern and southern TP in the future under different scenarios, which were attributed to the decreased stratiform precipitation in the southern TP and the increased convective precipitation in the northern TP, contrasting with the uniform increase of total precipitation in its forcing. The surface air temperature projected in WRF‐CCSM is larger increase than in the CCSM forcing. Compared to the CCSM forcing, WRF‐CCSM projects more pronounced increase in convective precipitation in response to rapid warming, and increasingly dominates changes of total precipitation with temperature exceeds the Clausius–Clapeyron rate over the northern TP. [ABSTRACT FROM AUTHOR]

Land cover change (LCC) significantly changed the local/regional temperature. This paper attempts to reveal the effects of cropland expansion in different ways on temperature change from the 1900s to 2010s in Heilongjiang Province. To reach this goal, we conducted four simulation research schemes with the coupled Weather Research and Forecast (WRF)-Noah model to investigate the warming/cooling effect of cropland expansion. The results show that cropland expansion exerted different effects with different land-use type conversions. In the last century, the areas with grassland-to-cropland and wetland-to-cropland transition show the warming effect, and the average surface temperature in Heilongjiang Province increased by 0.023 ℃ and 0.024 ℃, respectively. The areas with forest-to-cropland transition show the cooling effect, in which the average temperature decreased by 0.103 ℃. The variation of air temperature is mainly caused by the variation of surface reflectance and surface net radiation flux. The results provide evidence that cropland expansion changes to biophysical landscape characteristics, warming/cooling the land surface and thus enhancing/reducing the temperature, and lead to regional climate change eventually. [ABSTRACT FROM AUTHOR]

Precipitation recycling, as represented by the precipitation contributed by locally evaporated water vapor, is a key indicator of regional changes in the water cycle. The quasi-isentropic back-trajectory method, combined with a global climate model [Community Climate System Model (CCSM)] and regional climate model [Weather Research and Forecasting (WRF) Model simulation forced by CCSM (WRF-CCSM)], was used to analyze historical (1982–2005) and future (2090–99) precipitation recycling over the Tibetan Plateau (TP). The study focuses on the differences in the projection of precipitation recycling ratio (PRR) changes and relevant mechanisms between the fine-resolution (30 km) WRF-CCSM and coarse-resolution (~110 km) CCSM simulations. Compared with CCSM, the biases and root-mean-square errors of the historical evapotranspiration and precipitation over the TP were greatly reduced in the WRF-CCSM simulation, particularly in precipitation. Using WRF-CCSM outputs, higher PRRs in all elevation bands than CCSM, as well as the opposite seasonal pattern and linear trend of PRR for the river basins in the northern TP, were revealed. Unlike the CCSM projections, WRF-CCSM projects increasing trends of PRR changes with elevation under the RCP4.5 and RCP8.5 scenarios, with the largest increase at an elevation of about 5000 m. WRF-CCSM projects a diverse spatial and seasonal pattern of PRR changes, in contrast to the uniform decrease projected by CCSM. The larger fractional increases of future evapotranspiration contribution (precipitation contributed by local evapotranspiration) per unit warming than precipitation changes in WRF-CCSM suggests an enhanced contribution of locally evaporated moisture to total precipitation in the future under the RCP4.5 and RCP8.5 scenarios. Significance Statement: Rapid warming over the Tibetan Plateau has caused changes in the levels of wetness and dryness, meaning there is considerable concern surrounding the consequent environmental changes under continued warming in the future. The aim of this study was to quantify the historical (1982–2005) and future (2090–99) contributions to precipitation from external moisture transportation and local evapotranspiration over the Tibetan Plateau. At a fine resolution of 30 km, our results showed higher precipitation recycling ratios and different linear trend signs compared with that at the coarse resolution over 100 km at all elevations. In the future period, a contrasting contribution of local evapotranspiration to precipitation over the Tibetan Plateau is projected, with an 8% increase in the northwestern TP and a 3% decrease in the southeastern TP. [ABSTRACT FROM AUTHOR]

Agricultural expansion is one of the primary land use changes on the Earth's surface. The Songnen Plain in Northeast China is renowned for its Black Soil and is one of the most important agricultural regions of this country. In the last century, its population increased 20-fold and excessive areas of grassland were cultivated. Based on a series of decadal land use/land cover data sets in the plain (1910s–2010s), this study simulated the water balance in each decade using the Weather Research and Forecasting (WRF) model and assessed the water effects of centurial agricultural expansion. Six variables were simulated to explain the land-atmosphere interaction: precipitation, total evapotranspiration, canopy transpiration, canopy interception evaporation, land evaporation and land surface runoff and infiltration. Agreeing with historical climate reanalysis data, the simulated precipitation in the plain did not have a significant trend. However, the total evapotranspiration significantly increased in the study region. The canopy transpiration and interception evaporation increased and the runoff and infiltration decreased, both indicating a drought effect in soil. The drying trend varied spatially with the strongest pattern in the central plain where large areas of wetlands remain. As a consequence of agricultural expansion, the centurial drying process in the fertile Black Soil may put strong pressure on the crop productivity and food safety of this important agricultural region. [ABSTRACT FROM AUTHOR]