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Over‐estimation of summer precipitation over the Tibetan Plateau (TP) is a well‐known and persistent problem in most climate models. This study demonstrates the impact of a Gaussian Probability Density Function cloud fraction scheme on rainfall simulations using the Weather Research and Forecasting model. It is found that this scheme in both 0.1° and 0.05° resolutions significantly reduces the wet bias through both local feedbacks and large‐scale dynamic process. Specifically, increased cloud water/ice content with this scheme reduces surface shortwave radiation, and consequently surface heat fluxes and evapotranspiration. This, in turn, dampens the large‐scale thermal effect of the TP and weakens the exaggerated monsoon circulation and low‐level moisture convergence. It is this large‐scale dynamic process that contributes the most (∼70%) to the wet bias reduction. Although this paper presents a modeling study, it highlights the cloud radiative feedback to the large‐scale dynamics and precipitation over the TP. Plain Language Summary: Despite numerous attempts to correct the overestimation of summer precipitation over the Tibetan Plateau (TP) in current global and regional climate models, the issue persists. This study applies the Gaussian Probability Density Function (GPDF) cloud fraction scheme in the Weather Research and Forecasting model at two different resolutions (0.1° and 0.05°) during a summer over the TP. The results show that the GPDF scheme significantly mitigates the precipitation overestimation, particularly in the high‐resolution modeling. We explored the physical processes, both local and remote, that contribute to this improvement. Specifically, an increase in cloudiness reduces the amount of radiation reaching the land surface. This decrease in surface radiative heating not only reduces local evaporation but also weakens the thermal effect of the TP. The latter is a major driver of the South Asian monsoon that conveys moisture to the TP, and its weakening reduces moisture convergence over the TP. Both the decreases in local evaporation and remote moisture convergence contribute to the alleviation of the precipitation overestimation, and the latter plays a dominant role. These findings provide a unique perspective for reducing the wet bias over the TP, focusing on the surface available energy and associated remote moisture processes. Key Points: The use of the Gaussian Probability Density Function cloud fraction scheme in high resolution greatly reduces wet bias over the Tibetan Plateau (TP) during summerMore cloud water/ice with the scheme lessens TP's thermal effect, causing a weaker South Asian monsoon and moisture convergenceWet bias reduction is mainly governed by the decrease in remote moisture rather than local evapotranspiration [ABSTRACT FROM AUTHOR]

Reliable precipitation simulation over the Tibetan Plateau (TP) remains a challenge, manifested by a prominent systematic wet bias in the warm season. Previous studies have generally neglected the potential linkage between surface radiation energy budget and precipitation bias. Prevalent scattered cumulus and thunderstorms over the TP in summer strongly influence surface radiation. A cloud fraction scheme considering subgrid temperature and humidity fluctuations is implemented in the WRF model and tested for a month‐long simulation. It is found that the scheme better reproduces the surface solar radiation compared to a default cloud fraction scheme in the WRF model. Using abundant surface observations, we find that overestimation of the downward surface shortwave radiation (DSSR) would lead to wet bias. DSSR overestimation contributes to higher surface temperature and larger evaporation and enhanced atmospheric instability, which favor more simulated convective precipitation. The study suggests that a better simulation of clouds and surface radiation would benefit precipitation simulation over the plateau. Plain Language Summary: Summer precipitation over the Tibetan Plateau (TP) is generally overestimated in general circulation models as well as regional weather forecasts and climate models. The prevailing "popcorn‐like" clouds over the TP in summer would strongly impact surface radiation. Considering the potential linkage between surface radiation energy budget and precipitation bias, a statistical cloud fraction and subgrid condensation scheme (GS‐PDF scheme) is implemented in the WRF model and tested for a month‐long simulation. The GS‐PDF scheme better captures clouds over the TP with more mid‐low cloud water (ice) than the default Xu‐Randall scheme. Increased mid‐low cloud water in the GS‐PDF scheme reduced simulated downward surface shortwave radiation, reduced simulated surface temperatures, atmospheric instabilities and convective precipitation, leading to alleviated wet bias over the TP. This study suggests that better simulations of cloud and surface radiation would be beneficial for simulations of hydrological cycles over the TP. Key Points: A new cloud macrophysics scheme considering subgrid temperature and humidity fluctuations is implemented in the WRF modelThe new macrophysics scheme reduced simulated downward surface shortwave radiation, surface temperatures and atmospheric instabilitiesA better simulation of clouds and surface radiation would benefit precipitation simulation over the Tibetan Plateau [ABSTRACT FROM AUTHOR]

The Regional Climate Model Version 4 (RegCM4) with the conventional plane‐parallel radiative transfer scheme severely overestimates the summer precipitation over the Tibetan Plateau (TP) due to the excessive surface heat source, which results from the poor representation of the sub‐grid terrain‐related radiation processes. To realistically describe the surface sub‐grid radiation process in the RegCM4, a 3‐dimensional sub‐grid terrain solar radiative effect (3DSTSRE) parameterization scheme is implemented into the RegCM4 to improve the original plane‐parallel radiative transfer scheme. Results show that adopting the 3DSTSRE scheme in RegCM4 can significantly reduce the summer (June–August) wet bias over the TP produced by the model with the plane‐parallel radiative transfer scheme. Mechanism analysis indicates that the 3DSTSRE scheme largely improves the description of the TP surface energy balance in the RegCM4 by reducing the positive bias of downward surface solar radiation (DSSR). The reduced DSSR leads to the weakened surface heat source and cooler near‐surface air over the TP. Consequently, the local atmospheric circulation adapts to the temperature field as the low‐level anti‐cyclonic (high‐level cyclonic) anomaly over the TP. The adjustment of the temperature and wind field attenuates the water vapor transport, enhances the low‐level atmospheric stability, inhibits the updraft motion, and eventually reduces the rainfall over TP. Although the 3DSTSRE improves the DSSR simulation only during daytime, the precipitation simulation is also improved at nighttime, which is fundamentally attributed to the maintenance of the cooled atmosphere throughout the daytime and nighttime. Key Points: A 3‐dimensional sub‐grid terrain solar radiative effect (3DSTSRE) scheme has been successfully implemented into the RegCM4 modelThe surface solar radiation flux and heat balance over the Tibetan Plateau in summer can be clearly improved by RegCM4 with the 3DSTSREThe wet biases of RegCM4 over the regions with complex terrain in Tibetan Plateau can be largely reduced by adopting the 3DSTSRE scheme [ABSTRACT FROM AUTHOR]

Observations and simulations have shown that the Tibetan Plateau (TP) plays an important role in the climate and weather of East Asia. Uncertainties in reanalysis data sets have been documented by comparing them with independent rawinsonde data, but the impacts of incorporating this data into a reanalysis data set on the dynamical and thermodynamical features over the TP have not been assessed. Observations from the recent Third Tibetan Plateau Atmospheric Scientific Experiment (TIPEX‐III) can be used to evaluate the Eastern TP ERA‐Interim reanalysis data set (ERA). In this study, the Barnes objective analysis scheme is used to incorporate the rawinsonde data into the ERA to acquire the gridded data (OBJ) for examining heat and moisture budgets. It is shown that the OBJ budget‐estimated rainfall intensity is better correlated with the observations than the ERA budget‐estimated rainfall intensity. The ERA overestimates weak rainfall but underestimates heavy rainfall. The incorporation of special rawinsonde into the OBJ impacts the dynamical and thermodynamical characteristics both spatially and temporally. The downward motion and cooling are enhanced over the rainless regions/periods, while the upward motion and heating are enhanced over the rainy regions/periods. The rawinsonde effect is stronger with the increasing rainfall intensity. The differences of spatial distributions and temporal variations in heating between the OBJ and ERA are primarily determined by the vertical advection terms in heat and moisture budgets. The OBJ‐derived large‐scale forcing is essential for cloud‐resolving model simulations of TP cloud systems. The above conclusions can also be applied to the ERA5. Key Points: The inclusion of the rawinsonde data can significantly improve the ERA‐Interim quality over the Tibetan PlateauThe impacts of rawinsonde data on the Tibetan Plateau's dynamical and thermodynamical features are related to the rainfall intensityThe rawinsonde's impacts are primarily determined by the vertical advection terms in heat and moisture budgets [ABSTRACT FROM AUTHOR]