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Aims It remains unknown whether the treatment of hypertension influences the mortality of patients diagnosed with coronavirus disease 2019 (COVID-19). Methods and results This is a retrospective observational study of all patients admitted with COVID-19 to Huo Shen Shan Hospital. The hospital was dedicated solely to the treatment of COVID-19 in Wuhan, China. Hypertension and the treatments were stratified according to the medical history or medications administrated prior to the infection. Among 2877 hospitalized patients, 29.5% (850/2877) had a history of hypertension. After adjustment for confounders, patients with hypertension had a two-fold increase in the relative risk of mortality as compared with patients without hypertension [4.0% vs. 1.1%, adjusted hazard ratio (HR) 2.12, 95% confidence interval (CI) 1.17–3.82, P = 0.013]. Patients with a history of hypertension but without antihypertensive treatment (n = 140) were associated with a significantly higher risk of mortality compared with those with antihypertensive treatments (n = 730) (7.9% vs. 3.2%, adjusted HR 2.17, 95% CI 1.03–4.57, P = 0.041). The mortality rates were similar between the renin–angiotensin–aldosterone system (RAAS) inhibitor (4/183) and non-RAAS inhibitor (19/527) cohorts (2.2% vs. 3.6%, adjusted HR 0.85, 95% CI 0.28–2.58, P = 0.774). However, in a study-level meta-analysis of four studies, the result showed that patients with RAAS inhibitor use tend to have a lower risk of mortality (relative risk 0.65, 95% CI 0.45–0.94, P = 0.20). Conclusion While hypertension and the discontinuation of antihypertensive treatment are suspected to be related to increased risk of mortality, in this retrospective observational analysis, we did not detect any harm of RAAS inhibitors in patients infected with COVID-19. However, the results should be considered as exploratory and interpreted cautiously.

Using the COLA (Center for Ocean-Land-Atmosphere Studies) general circulation model, a series of numerical experiments were conducted to examine the impact of uplift of the Tibetan Plateau on the evolution of the monsoon climate in East Asia. An attempt was made to isolate the effect of the Plateau uplift from the changes in other forcing mechanisms. We examined the spatial and temporal variation patterns of a variety of climatic variables and indices, including monsoon intensity, sea level pressure, surface and upper-air winds, temperature at different levels, precipitation, air humidity and soil moisture. Our results suggest that the evolution of the East Asia monsoon may be more sensitive to the uplift of the Tibetan Plateau than that of the South Asia monsoon. Moreover, the effect of the Plateau uplift on the East Asia winter monsoon is more significant than that on the summer monsoon. In the northern part of East Asia (North China), the formation of the monsoon climate is marked mainly by the establishment of the northerly winds in winter, or the winter monsoon system, corresponding to the uplift of the Plateau when the height reaches approximately 50% of its current elevation. On the other hand, the establishment of the monsoon climate in the southern part of East Asia (the Yangtze River valley and the area south of it) may be much earlier than that in the northern part. ß

[1] Daily and monthly maximum and minimum surface air temperatures at 66 weather stations over the eastern and central Tibetan Plateau with elevations above 2000 m were analyzed for temporal trends and spatial variation patterns during the period 1961-2003. Statistically significant warming trends were identified in various measures of the temperature regime, such as temperatures of extreme events and diurnal temperature range. The warming trends in winter nighttime temperatures were among the highest when compared with other regions. We also confirmed the asymmetric pattern of greater warming trends in minimum or nighttime temperatures as compared to the daytime temperatures. The warming in regional climate caused the number of frost days to decrease significantly and the number of warm days to increase. The length of the growing season increased by approximately 17 days during the 43-year study period. Most of the record-setting months for cold events were found in the earlier part of the study period, while that of the warm events occurred mostly in the later half, especially since the 1990s. The changes in the temperature regime in this region may have brought regional-specific impacts on the ecosystems. It was found that grain production in Qinghai Province, located in the area of prominent warming trends, exhibited strong correlations with the temperatures, although such relationships were obscured by the influence of precipitation in this arid/semiarid environment in juniper tree ring records. In western Sichuan Province under a more humid environment, the tree growth (spruces) was more closely related to the changing temperatures.Citation: Liu, X., Z.-Y. Yin, X. Shao, and N. Qin (2006), Temporal trends and variability of daily maximum and minimum, extreme temperature events, and growing season length over the eastern and central Tibetan

The interannual variability of summer precipitation over the eastern Tibetan Plateau (ETP) was examined in relation to the Northern Hemisphere macroscale circulation patterns during the period 1961-90. Summer precipitation data for 66 stations located above 2000 m MSL are used in the analysis. Using principal component analysis, it is found that the dominant spatial pattern of interannual variability of the summer precipitation is a seesaw structure between the southern and northern parts of ETP. Correlation analysis shows that this pattern of precipitation anomalies is closely associated with the North Atlantic oscillation (NAO). Further analysis based on midtropospheric geopotential height and wind data suggests the upstream zonal flow variation associated with the NAO pattern as the major mechanism linking the regional precipitation fluctuation to macroscale circulation conditions. During the summers of low NAO index values, the westerly winds between 40Њ and 50ЊN from the eastern Atlantic to Europe are intensified. The enhanced upstream westerly winds generate anomalous anticyclonic flows in the lower-latitude area to the west of the plateau and stronger dynamic bifurcation flows to the south of the plateau, which promote development of cyclonic flows to the east of the plateau. As a result, the southerly winds in the southern ETP and the northerly winds in the northern ETP are strengthened simultaneously. In this case, summer precipitation is usually above normal in the southern ETP but below normal in the northern ETP. During the summers of high NAO index values, the above processes are reversed, producing a pattern with below-normal precipitation in the southern ETP and above-normal precipitation in the northern ETP. This study suggests that the combination of the dynamic effect of large orography such as the Tibetan Plateau and the macroscale atmospheric circulation can be the determinant factor of regional climatic variability.

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The relationships between the spring (March–May) dust storm frequency (DSF) of northern China, gridded precipitation based on gauge observations, wind velocity at different geopotential heights, satellite‐measured land vegetation index, and grid box soil moisture data during 1982–2001 are examined using correlation analysis and singular value decomposition methods. The results show that the spring DSF time series has strong positive correlations with the upwind wind velocity but strong negative correlations with the antecedent summer (June–August) and annual (June of the prior year to May of the current year) precipitation and soil moisture anomalies, as well as with the spring vegetation condition across a region running northeast‐southwest from the northeast China and China‐Mongolia border to the Taklimakan Desert. This region has been identified as the major source of dust emission in northern China. The results suggest that the summer rainfall anomaly over an extensive area close to the China‐Mongolia border is the primary factor that determines the local soil moisture condition in the summer and then the vegetation condition in the following spring through persistence of the soil moisture, eventually determining the variation pattern of the spring DSF in northern China.