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Recent years have witnessed contrasting trends in summer total rainfall (STR) over the Tibetan Plateau (TP), with an increase in the northern and a decrease in the southern TP. This study identifies four significant centers of rainfall trends: eastern TP ("region A"), Qiangtang Plateau ("B"), Qaidam Basin ("C"), and the northern foothills of the Himalayas ("D"). Heavy rainfall dominates STR trends in regions A and D, accounting for 55.6% and 52.0%, respectively. In region B, moderate and light rainfall contribute almost equally, accounting for 37.3% and 44.8% of the STR trend, respectively. Region C is primarily influenced by light rainfall, explaining 71.2% of the STR trend. Notably, the contributions of different rainfall intensities to STR in each region vary annually, with region A experiencing more heavy rainfall, region B having moderate dominance but less light rainfall, and region C and D showing reduced and increased light rainfall contributions, respectively. Mechanistically, the strengthening of the upper-level westerly jet and the South Asian High, coupled with changes in moisture transport and convective available potential energy, collectively cause variations in rainfall intensity, characterizing the spatial heterogeneity in STR in the TP. [ABSTRACT FROM AUTHOR]

Variations in surface air temperature on the eastern Tibetan Plateau (TP‐SAT) during boreal summer, related to Barents‐Kara spring sea ice and summer Arctic Oscillation (AO), are investigated using observations and ERA‐5 reanalysis data during 1979–2018. Results show that the primary mode of summer eastern TP‐SAT (SAT_EOF1) is characterized by the consistent warming pattern with larger values over the northeastern TP, which is linked with the anticyclonic circulation located in the northeastern flank of the TP. This anticyclone enhances westward water vapor transport, warm temperature advection, and causes descending over the eastern TP, Descending further results in deceased middle level cloud cover and increased solar radiation, accordingly, favoring the eastern TP warming. Further statistical analysis reveals a robust connection between Barents‐Kara spring sea ice, summer AO and SAT_EOF1. Moreover, anticyclonic anomaly located in the northeastern region of the TP acts as an important driver of this consistent warming pattern over the eastern TP, which is modulated by two individual Rossby wave trains from the northwestern Russia and northwestern Atlantic. The spring sea ice in Barents‐Kara could cause decreased precipitation and reduced soil moisture in northwestern Russia during following summer, which further induces the Eurasian‐like teleconnection and affects the anticyclonic anomaly situated in the northeastern flank of the TP, thereby favoring eastern TP warming. In addition, from northwestern Atlantic to northeastern region of the TP, the Rossby wave train is mainly affected by summer AO, with positive AO causing anticyclonic anomaly over northeast of the TP, thus contributing to the TP warming. Plain Language Summary: Tibetan Plateau (TP) is a region that is easily affected by the global warming. Numerous studies have extensively documented a remarkable warming trend in the TP during boreal summer, particularly noticeable since the late 1990s. Despite these valuable observations, its mechanisms are not yet clear. In this study, we found that the anticyclonic anomaly over the northeast of TP is a crucial system affecting eastern TP warming in boreal summer. This anticyclonic anomaly leads to the strengthened westward water vapor transport and causes descending over the eastern TP. Descending, in turn, results in the reduction of middle level cloud cover and increased solar radiation. Further analysis indicated that this anomalous anticyclone is mainly modulated by two individual wave trains from the northwestern Russia and northwestern Atlantic, respectively. From northwestern Atlantic to northeastern flank of the TP, the wave train is mainly affected by the summer AO, and another is mainly driven by the spring Barents‐Kara sea ice. Those two factors account for about 36% of the summer eastern TP warming. Key Points: Anticyclonic anomaly located in the northeastern flank of the TP favors the eastern TP warmingSpring Barents‐Kara sea ice could affect this anticyclone through its influences on summer soil moisture over northwestern RussiaThis anticyclone is also modulated by the wave train from northwestern Atlantic, which is mainly affected by Arctic Oscillation [ABSTRACT FROM AUTHOR]

The spring sensible heating (SSH) over the Tibetan Plateau (TP), which can significantly affect the precipitation in China, has experienced three different stages of change, showing significant increasing (1961–1979, Stage I), decreasing (1980–2002, Stage II), and increasing (2003–2014, Stage III) trends. In this study, the impact of these different trends in TP SSH on spring precipitation (SPR) in China and their possible mechanisms are investigated, based on observations and the reanalysis product. In Stage I, the SPR represents a contrasting north-south pattern associated with the increasing TP SSH, showing increasing trends over southern China and decreasing trends over central and northern China. Further, the spatial distribution of SPR trends shows a contrasting east-west pattern in Stage II. That is, persistent weakening TP SSH plays a more crucial role in increasing and decreasing SPR over southwestern and southern China, respectively. However, compared with the significant trend in SPR in Stage III, the regulation of TP SSH on SPR weakens significantly. Dynamically, the increasing TP SSH in Stage I can strengthen the subtropical westerly jet in the upper layer, simultaneously configured with an anomalous cyclone in northeastern China, which deepens the East Asian trough. Thus, anomalous convergence in the upper layer occurs over central and northern China, favoring the downdraft. It then causes more cold and dry air to move southward in the lower troposphere, which then encounters the warm and wet southwest airflows, boosting the updraft over southern China. In Stage II, regression analysis shows that if the TP SSH increases, an anomalous cyclone in the middle and upper troposphere occurs over the western TP, causing the downdraft and less precipitation over southwestern China, while a cyclone in the lower troposphere occurs over the western North Pacific and extends to southern China, promoting the ascending motions and more precipitation in southern China. However, in this stage, TP SSH actually weakens, thus contributing to more precipitation over southwestern China and less precipitation over southern China. [ABSTRACT FROM AUTHOR]

The characteristics of diurnal variation of the surface sensible heat flux (SH) over the Tibetan Plateau (TP) are comprehensively investigated by using the long-term dataset of integrated land–atmosphere interaction observations (2006–2016) on the TP. Results show that the diurnal variation of SH shows obvious seasonal variabilities in terms of amplitude, duration, and peak time. At the Muztagh Ata Westerly Observation and Research Station (MAWORS), the Ngari Desert Observation and Research Station (NADORS), and the Qomolangma Atmospheric and Environmental Observation and Research Station (QOMS), the SH diurnal amplitude is consistently the largest in spring, followed by summer and autumn, and the smallest in winter, with a peak at 15:00. However, for the Southeast Tibet Observation and Research Station (SETORS), the amplitude in winter is rather violent with the peak at 12:00. We find that positive SH at most stations has the longest duration from May to August. Moreover, the peak time fluctuates from month to month, even showing a shift at the QOMS before and after 2015, and the double-peak phenomenon of SH mainly occurs in spring and autumn. Additionally, magnitudes of calculated SH with the conventional heat transfer coefficient (CDH) of 0.004 are about 64% to 100% larger than those of directly observed SH at the QOMS and the Nam Co Monitoring and Research Station (NAMORS). We here additionally recommend a new CDH values of about 2.24 × 10−3 in spring and 2.78 × 10−3 in summer, respectively, to more accurately calculate the TP SH. [ABSTRACT FROM AUTHOR]

By using the observational and reanalysis datasets during the period of 1979–2018, the role of the thermal effect of the Tibetan Plateau (TP) and Artic Oscillation (AO) in the midsummer (July–August) extreme high-temperature events (EHEs) over the Yangtze River Valley (YRV) is investigated. The primary mode of the EHEs (EHEs_EOF1) over the YRV is characterized by an increased frequency of the EHEs over the YRV, with two centers located in the upper and lower reaches of the YRV, respectively. The results indicate that the higher YRV EHEs frequency is associated with anticyclonic anomalies over northern China, which leads to the descending motion over the YRV, further resulting in the reduced middle to low clouds and enhanced solar radiation. In addition, warmer surface ground will heat the atmosphere through the sensible heat and upward longwave radiation. Moreover, less soil moisture also favors the occurrence of the EHEs. Further analysis demonstrates that the EHEs_EOF1 is related to the midsummer surface air temperature over the TP (TP-SAT) and the AO. The anticyclonic anomalies over northern China are considered to be the key factors favoring the YRV EHEs, which is associated with the TP-SAT and AO, of which TP-SAT dominates. TP warming can induce anticyclonic anomalies over northern China, thus favoring the YRV EHEs. AO can also affect the anticyclonic anomalies over northern China through the Rossby wave train originating from the northwestern Atlantic, which is largely modulated by the TP thermal forcing. In addition, the model experiment with the linear baroclinic model (LBM) further provides direct evidence to illustrate the impact of the thermal condition of the TP on generating circulation anomalies that conducive to the EHEs over the YRV. • Anomalous anticyclone (AC) over northern China favors the extreme high-temperature events over the Yangtze River Valley. • AC over northern China is mainly driven by the thermal effect of the Tibetan Plateau. • Arctic Oscillation can also affect the AC through the Rossby wave train originating from the northwestern Atlantic. [ABSTRACT FROM AUTHOR]