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Understanding cloud distribution over lakes is crucial to determine input radiation and precipitation for lake thermal and water balance processes. Based on Himawari‐8 satellite observation and Weather Research and Forecasting model results, this study examines the influences of lakes on daytime cloud cover during warm seasons over the Tibetan Plateau (TP), which is home to thousands of lakes. Observation shows the existence of cloud holes and narrow cloud rings around the lakes, that is, fewer clouds over the lakes and more clouds along the shoreline, which has rarely been reported and is considered typical to TP by comparison with lakes outside of TP. The threshold size of lakes that can produce the shoreline cloud ring is identified to be about 300 km2, as a conservative estimate. We further highlight the importance of atmosphere advection/background wind in the formation of lake‐associated clouds. Lake breeze forms under weak background winds and the downdraft branch inhibits cloud formation over the lakes; while the updraft branch causes convection to form clouds over lakeshores. However, strong background winds do not favor lake breeze formation, changing cloud distribution over the lakes. Fewer clouds are also found in the downwind regions, and this influence is at a distance comparable to the lake scale. Due to fewer clouds over lakes, shortwave radiation is significantly larger (∼100 W/m2) and longwave radiation is smaller (∼a few W/m2) than that of the further land region. Therefore, the above observational facts provide a new perspective to advance the understanding of lake‐air interactions. Plain Language Summary: There are lots of lakes over the Tibetan Plateau (TP), but the influence of these lakes on cloud during warm seasons remain unclear. Satellite data shows the existence of cloud holes and narrow cloud rings around the lakes, that is, fewer clouds over the lakes and more clouds along the shoreline, which has rarely been reported before. Simulation results demonstrate that the lake breeze accounts for this phenomenon: air descends over the lake, which inhibits cloud formation, while ascending branch over the shoreline favors cloud formation. Lakes over 300 km2 can yield these cloud influences, so this area is thought as the threshold area that lakes can have influence on atmosphere. Clouds in the downwind regions are also fewer under the influence of background wind, and this influencing distance is almost equal to the lake scale itself. Due to less block by clouds, solar radiation is much higher over the lake than surrounding land, but downward longwave radiation is a little lower because of less emission from the cloud bottom, resulting an increase of net radiation in total at the lake surface. The conclusions of this study can help understand energy and hydrology processes of lakes better over the TP. Key Points: Evident "cloud holes" and "cloud rings" are found for lakes over the Tibetan Plateau, which are mainly induced by lake breezeClouds in the downwind regions are also fewer due to atmosphere advection; this distance is almost equal to the size of the lake itselfFewer clouds over the lake increase the net radiation mainly due to much higher downward shortwave radiation [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]

Investigation of the variations of hydrological cycles during the Last Interglacial (130–115 ka; LIG) may deepen our understanding of climate change in a warmer‐than‐present world induced by Earth's orbit. Here we revealed an intensified atmospheric branch of the hydrological cycle over the Tibetan Plateau (TP) in summer during the LIG relative to the preindustrial period, using the mesoscale Weather Research and Forecasting model driven by the Community Earth System Model. Our results showed that precipitation over the TP increased by 5.65 × 107 kg s−1, with 63.2% of the increase contributed by advected moisture transports, and the remaining 36.8% caused by local moisture recycling processes. As for advected moisture transports, the inflow increased by 1.93 × 107 kg s−1 and the outflow decreased by 0.87 × 107 kg s−1, respectively. Variations of the moisture transport were more profound at the eastern and northern edges, which were linked with changes in Indian summer monsoon and westerly jets. Regarding local moisture recycling processes, evaporation enhanced by 2.85 × 107 kg s−1 over the TP, influenced by variations in surface air temperature, surface net radiation flux, surface relative humidity, and surface wind fields. Increased evaporation accompanied by enhanced moisture inflow resulted in an enriched precipitation recycling ratio of ∼1% over the TP during the LIG relative to the preindustrial in summer. Our results aid in understanding the atmospheric branch of the hydrological cycle over the TP in an orbit‐induced warmer world and shed light on the future evolution of the hydrological cycle over the TP at multi‐millennial and orbital timescale. Key Points: Dynamical downscaling simulations for the Last Interglacial from Weather Research and Forecasting driven by Community Earth System ModelIntensified atmospheric branch of the summer hydrological cycle over the Tibetan Plateau during the Last Interglacial (LIG)Intensified hydrological cycle was manifested in both external and internal cycles during the LIG [ABSTRACT FROM AUTHOR]

Investigated in this study are the seasonal and semi‐diurnal variations of the cloud‐phase climatology over the southern Himalayas and adjacent regions by using 5 years of Himawari‐8 cloud‐product data (2016–2020). The four selected regions from south to north are the Gangetic Plains (I), Himalayan foothills (II), southern slope of the Himalayas (III), and the Himalayan–Tibetan Plateau region (IV), respectively. Results showed that the cloud frequency of cloud gradually increases from region I via II to III, then sharply decreases as the altitude increases up to IV. Ice‐phase clouds occurs more frequently over regions I/II (III/IV) during boreal summer (winter), while water‐phase cloud has a higher frequency over region III/IV (I/II) in summer (winter), respectively. All of the different cloud phases have a clear seasonal cycle. Furthermore, the semi‐diurnal variation shows that water‐phase clouds tends to have an occurrence frequency peak around noon (in the later afternoon) over regions I/II/III in summer (winter), whereas over region IV it only occurs more in the morning in both seasons. Ice‐phase cloud generally occurs more in the late afternoon in both boreal summer and winter, especially over region IV. Further analysis showed that the differences in the cloud‐phase characteristics over the southern Himalayas and adjacent regions are likely related to the interactions of the synoptic‐scale circulation, the topography, and the water vapor transport. Plain Language Summary: By using 5 years geostationary weather satellite cloud product, we investigated the seasonal and semi‐diurnal variations of the cloud‐phase climatology characteristics over the southern Himalayas and adjacent regions, including four select sectors of the plain, foothill, slope and plateau. We found that the cloud frequency gradually increases from plain via foothill to slope, then decreases as the terrain increases up to plateau. All different phase clouds have a clear seasonal cycle and semi‐diurnal variations. Such as ice‐phase cloud occurs more over the plain and the foothill during summer season, while it occurs more over the slope region and plateau in winter; water‐phase cloud has a peak at noon (later afternoon) over the plain/foothill/slope in summer (winter), while over the plateau, it only occurs more in the morning. The results are important for comprehend how the southern Himalayas impact regional climate. Key Points: Cloud frequency increases significantly from region I via II to III, then decreases as the elevation further increases up to region IVIce‐phase clouds occurs more frequently over regions I/II (III/IV) in summer (winter), which is opposite to the occurrence of water‐phase cloudWater‐phase clouds tend to occur more around noon (in the later afternoon) over regions I/II/III in summer (winter), while it only occurs more in the morning over region IV [ABSTRACT FROM AUTHOR]

This study analyzes the synoptic‐scale circulation patterns favorable for regional extreme precipitation events over southwest China (SWC) from 1979 to 2018 occurring during the rainy seasons. The whole SWC is regionalized into two subregions, western SWC and eastern SWC, according to the spatial distribution of two extreme precipitation indices. Furthermore, the atmospheric patterns associated with the independent regional extreme precipitation events (REPEs) that occurred over the two subregions are categorized into two types using k‐means clustering. For type 1, a Rossby wave train originating from the Northeast Atlantic almost a week before REPEs leads to an anomalous low over the eastern Tibetan Plateau (TP), inducing upper‐troposphere divergence and ascending motion over SWC. Moreover, anomalous convective activities over India and the Bay of Bengal (the enhanced and westward‐extended western Pacific subtropical high) are critical precursors of REPEs over western (eastern) SWC. For type 2, an anomalous high is developed over the Ural Mountains at least a week prior to REPEs. The subsequent anomalous low over Lake Baikal and eastward‐shifted South Asian high are conducive to forming updrafts over SWC. An anomalous anticyclone at the middle‐to‐lower troposphere south of the TP is the main moisture contributor. Discrepancies in the zonal location of the Lake Baikal low and the strength of the Ural Mountain high, as well as the intensity of atmospheric circulation anomalies at low latitudes, are the major differences between the type 2 events occurring in western and eastern SWC. Key Points: Two types of atmospheric circulation anomalies are favorable for extreme precipitation events over southwest China during rainy seasonsRossby wave trains from the Northeast Atlantic and the Ural Mountains are critical precursors of the extreme precipitation eventsThe low‐latitude atmospheric circulation anomalies mainly determine the spatial differences and the extremeness of the events [ABSTRACT FROM AUTHOR]

The East Asian summer monsoon (EASM) has complex drivers and is characterized by an abrupt onset and northward jumps of the main rain band. By analyzing multisource observational data and reanalysis data sets during 1961–2016, we addressed the connection between the preceding diabatic heating of the Tibetan Plateau (TP) and the seasonal march of the EASM. We show that the positive surface sensible heating and condensation heating anomalies over the TP lead the onset, duration, and total precipitation of the rainy season in South China (the first stage of the EASM) by about 2 and 1 month, respectively. A significant positive condensation heating anomaly over the TP can be detected about 1 month before the onset of the rainy season in Southwest China (the second stage of the EASM). By contrast, the relationship between heating of the TP and the onset of the rainy season is relatively weak during the remaining stages of the EASM, including the Meiyu and North China rainy seasons. We suggest that the strong heating of the TP intensifies the low‐level southwesterly circulation to the southeast and facilitates the convergence of moisture and ascending motion, leading to an earlier onset of the rainy season. Sensitive experiments with a linear baroclinic model further confirmed the role of heating of the TP in generating circulation conditions favorable for the onset of the rainy season in both South and Southwest China. The TP heating anomaly therefore acts as a precursor of the early stage onset of the EASM. Plain Language Summary: The East Asian summer monsoon (EASM) is the strongest subtropical monsoon and shows substantial variations from year to year in terms of the onset date, duration, and total precipitation, although the factors controlling this variation are not clear. We analyzed data from both observations and reanalysis data sets and used a numerical simulation to show that the preceding diabatic heating of the atmosphere over the Tibetan Plateau is the main driver of the seasonal march of the early stages of the EASM (i.e., the mean onset of the South China rainy season in early April and the Southwest China rainy season in late May). This is because the positive Tibetan Plateau heating anomaly intensifies the circulation conditions favoring monsoon rainfall in these areas, including the low‐level southwesterly circulation, which carries abundant water vapor from the tropical oceans, moisture convergence and upward motion. These results suggest that the Tibetan Plateau heating anomaly can be regarded as a precursor of the onset of the EASM. Key Points: The onset of the rainy season in South and Southwest China is closely related to the preceding heating of Tibetan PlateauThe heating of Tibetan Plateau influences the circulation and moisture conditions for the rainy season onset in South and Southwest ChinaThe Tibetan Plateau is an independent driver of the East Asian summer monsoon separated from the remote atmospheric and oceanic modes [ABSTRACT FROM AUTHOR]

Numerical simulations often overpredict precipitation over the Tibetan Plateau (TP). To examine the factors causing precipitation overprediction, different parameterizations of liquid‐phase microphysical processes (accretion, autoconversion, and entrainment mixing) are implemented into the Morrison microphysics scheme to simulate a TP precipitation event in summer with the Weather Research and Forecasting (WRF) model. The general spatial distribution and temporal trend of precipitation are captured by all simulations, but the precipitation rate is overpredicted. The results from sensitivity experiments suggest that compared to other examined liquid‐phase processes, the accretion process is more important in precipitation simulation over the TP region. Further investigation with the Heidke skill scores reveals that accretion parameterization that takes into account the raindrop size produces the most accurate results in terms of the total surface precipitation. This parameterization suppresses spurious accretion and does not produce liquid‐phase precipitation until cloud droplets are big enough. It is also confirmed that increasing the model resolution can reduce precipitation overprediction. Results from the case study are confirmed by the use of a 1‐month simulation. Key Points: The accretion process plays more important roles than other examined liquid‐phase processesConsidering raindrop size in accretion process suppresses liquid‐phase rain and mitigates the overprediction of precipitation over the TPIncreasing the model resolution can reduce precipitation overprediction [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]

Surface sensible heat fluxes (SH) over Tibetan Plateau (TP) dictate the seasonal conversion, onset and maintenance of the Asian monsoon. Spatiotemproal variability in SH over central and eastern TP (CETP) from reanalysis products (i.e., JRA55, ERA‐Interim, NCEP1, and NCEP2) and derived using bulk transfer approximations applied to observations is characterized for all seasons during 1980–2015 and is diagnosed in the context of two important drivers of variability: wind speed and land‐air temperature difference (Tg‐Ta). In the climatological mean, SH from observations increases from east to west and exhibits obvious seasonality with highest value in spring and lowest in winter. Declines in SH prior to 2000 as manifest in the observations appears to have resulted from changes in wind speeds, and the subsequent recovery is attributable to increases in both wind speeds and air‐surface temperature gradients. The intercomparison shows that ERA‐Interim exhibits greatest accord with observations in terms of the climatological distribution and seasonality, and all reanalyses exhibit some aspects of the temporal variability and long‐term trends as manifest in the observations. However, the root causes of the long‐term variability in SH as manifest in the reanalysis products are not consistent with inferences derived from the observations. Key Points: Evaluation of the ability of the reanalysis to capture the major spatial and seasonal patterns of sensible heat (SH) flux over the central and eastern Tibetan PlateauEvaluation of the ability of the reanalysis to capture the longer term "trends"/periodicities in SH fluxDecomposition of the causes of the variability of SH flux to two key local drivers ‐ wind speed and thermal gradient (land‐air) [ABSTRACT FROM AUTHOR]

This study identifies the fast (i.e., ∼ days–weeks) transport pathways that connect the Northern Hemisphere surface to the upper troposphere and lower stratosphere (UTLS) during northern summer by integrating a large (90 member) ensemble of Boundary Impulse Response tracers in the Whole Atmosphere Community Climate Model version 5. We show that there is a fast transport pathway that occurs over the southern slope of the Tibetan Plateau, northern India, the Arabian Sea, and Saudi Arabia; furthermore, we show that during July this pathway connects the Northern Hemisphere surface to the UTLS on a modal time scale of 5–10 days. A less efficient transport pathway is also identified over the western Pacific. A detailed budget analysis reveals that, while convective processes are responsible for transport to 200–300 hPa, the resolved dynamics, specifically the vertical eddy flux, dominate at 100–150 hPa. Transport variations are analyzed on weekly, monthly, and interannual time scales and are largely related to differences in the resolved dynamics in the UTLS. Key Points: A fast transport pathway into the UTLS is found over the southern slope of the Tibetan Plateau and northern IndiaResolved dynamics, specifically the vertical eddy flux, dominate transport into the UTLSVariability of northern summer tracer transport is analyzed with respect to weekly, monthly, and interannual time scales [ABSTRACT FROM AUTHOR]

A short‐lived (less than 2 days) inner Tibetan Plateau vortex (TPV) with heavy precipitation was simulated using the Weather Research and Forecasting model, and the sensitivity experiments with and without surface diabatic heating and atmospheric latent heating released by precipitation were conducted to investigate the roles of surface and atmospheric diabatic heating on the genesis and development of TPV. Results show that before the genesis of the TPV, there is an anomalous increase of surface heating flux; while a disturbance of potential vorticity (PV) at 500 hPa moves over this region, the PV is enhanced and induces the generation of TPV. The precipitation in turn reduces the surface heating flux. The release of condensation latent heating by precipitation during the development of TPV does not further contribute to its reinforcement. Instead, it is more likely a result of precipitation, tending to stabilize the atmosphere and conducive to the decay of TPV. The PV diagnoses further reveal that in the early phase, the strong diabatic heating in the lower levels associated with the increasing surface heating flux has a significantly positive contribution to the generation of the TPV. The precipitation results in the decrease of positive diabatic heating contribution at low levels. Inversely, the diabatic heating in the middle levels associated with the released latent heating of precipitation condensation tends to have the negative contribution to TPV, resulting in the decay of TPV. The study of this case can deepen our understanding on the mechanism of TPV and its precipitation. Key Points: The surface diabatic heating prior to the precipitation is crucial to the formation of TPVThe condensation latent heating caused by precipitation only seems to be a result of precipitation [ABSTRACT FROM AUTHOR]