scholarly journals Air stagnation in China (1985–2014): climatological mean features and trends

2017 ◽  
Vol 17 (12) ◽  
pp. 7793-7805 ◽  
Author(s):  
Qianqian Huang ◽  
Xuhui Cai ◽  
Yu Song ◽  
Tong Zhu
Keyword(s):  
Eastern China ◽  
Central China ◽  
Tibet Plateau ◽  
Positive Trend ◽  
Shandong Peninsula ◽  
Near Surface ◽  
Wind Speeds ◽  
Main Driver ◽  
Southern Shaanxi ◽  
Qinghai Tibet Plateau

Abstract. Air stagnation is an important meteorological measure of unfavorable air pollution conditions, but little is known about it in China. We conducted a comprehensive investigation of air stagnation in China from January 1985 to December 2014 based on sounding and surface observations from 81 stations. The stagnation criteria were revised to account for the large topographical diversity in the country. It is found that the annual mean of air stagnation occurrences is closely related to general topography and climate features. Two basins in the northwest and southwest of China, the Tarim and Sichuan basins, exhibit the most frequent stagnation occurrence (50 % of days per year), whereas two plateaus (the Qinghai–Tibet Plateau and the Inner Mongolian plateau) and the eastern coastal areas experience the least (20 % of days per year). Over the whole country, air stagnation is at a maximum in summer and a minimum in winter, except for Urumchi, a major city in northwestern China where stagnation maintains a rather constant value year round with a minimum in spring. There is a nationwide positive trend in stagnation occurrence during 1985–2014, with the strongest increasing centers over Shandong Peninsula in eastern China and southern Shaanxi in central China. Changes in air stagnation occurrences are dependent on three components (upper- and lower-air winds and precipitation-free days). This shows that the behavior of upper-air wind speeds is the main driver of the spatial distribution and trends in air stagnation, followed by near-surface winds and dry days, which contribute the least.

scholarly journals Air Stagnations for China (1985–2014): Climatological Mean Features and Trends

2017 ◽  
Author(s):  
Qianqian Huang ◽  
Xuhui Cai ◽  
Yu Song ◽  
Tong Zhu
Keyword(s):  
Inner Mongolia ◽  
Eastern China ◽  
Central China ◽  
Positive Trend ◽  
Major City ◽  
Comprehensive Investigation ◽  
Shandong Peninsula ◽  
Wind Speeds ◽  
Meteorological Measurement ◽  
Inner Mongolia Plateau

Abstract. Air stagnation is an important meteorological measurement for unfavourable air pollution conditions, but little is known about it in China. We conducted a comprehensive investigation of air stagnation in China, based on sounding and surface observations of 81 stations, from January 1985 to December 2014. The stagnation criteria were revised to be topographically dependent for the great physical diversity in this country. It is found that the annual mean air stagnation occurrences are closely related to general topography and climate features. Two basins in the northwest and southwest of China—Tarim and Sichuan Basins—exhibit the most frequent stagnation occurrence (50 % days per year), whereas two plateaus (Tibet-Qinghai and Inner Mongolia Plateau) and the east coastal areas experience the least (20 % days per year). Over the whole country, air stagnations achieve maxima in summer and minima in winter, except for Urumqi, a major city in the northwest of China, where stagnations keep a rather constant value yearly around with a minimum in spring. There is a nationwide positive trend in stagnation occurrence during 1985–2014, with the strongest increasing centres over Shandong Peninsula in eastern China and the south of Shaanxi in central China. Dependence degrees of air stagnations on three components (upper- and lower-air winds, precipitation-free days) are examined. It shows that the spatial distribution and trend of air stagnations are mainly driven by the behaviours of upper-air wind speeds.

scholarly journals Patterns and trends of high-impact weathers in China during 1959–2014

2015 ◽  
Vol 3 (10) ◽  
pp. 6149-6184
Author(s):  
J. Shi ◽  
K. Wen ◽  
L. Cui
Keyword(s):  
Eastern China ◽  
High Impact ◽  
Central China ◽  
Western China ◽  
Tibet Plateau ◽  
High Mountain ◽  
Weather Phenomenon ◽  
The Government ◽  
Social Vulnerabilities ◽  
Qinghai Tibet Plateau

Abstract. The spatial and temporal characteristics in the frequencies of four types of high-impact weathers (HIWs), i.e. snowfall, thunderstorm, foggy and hailstorm weathers were analyzed in China by using daily weather phenomenon data from 604 stations. Results indicate that snowfall, thunderstorm, foggy and hailstorm days showed significant decreasing trends with rates of 2.5, 2.6, 0.8 and 0.5 days per decade respectively, and snowfall, thunderstorm, foggy and hailstorm weather processes decreased significantly at rates of 0.3, 0.4, 0.1 and 0.1 times per decade during 1959–2014. Spatially, snowfall weathers were more in northeastern and western China, and thunderstorm weathers were more in southern and southwestern China. Foggy weathers were more in some high mountain stations, eastern China and central China, and hailstorm weathers were concentrated on Qinghai–Tibet Plateau. Over the past 56 years, snowfall days, thunderstorm days and thunderstorm weather processes decreased in most parts of China, with decreasing rates of 1.0–6.0 days, 1.5–8.0 days and 0.2–1.0 times per decade respectively. Hailstorm days decreased in northeastern China and most parts of northern and western China at a rate of 0.2–4.5 days per decade. The spatial trends of foggy days, foggy weather processes and snowfall weather processes were not significant in most parts of China. With climate change and rapidly economic development, more policies and strategies of reducing social vulnerabilities and/or exposures to HIWs are essential for the government and social publics.

scholarly journals Effects of Air Temperature and Precipitation on Soil Moisture on the Qinghai-Tibet Plateau during the 2015 Growing Season

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Qingyan Xie ◽  
Jianping Li ◽  
Yufei Zhao
Keyword(s):  
Soil Moisture ◽  
Air Temperature ◽  
Hydrological Cycle ◽  
Critical Role ◽  
Growing Season ◽  
Tibet Plateau ◽  
Ecosystem Stability ◽  
Near Surface ◽  
Temperature And Precipitation ◽  
Qinghai Tibet Plateau

The Qinghai-Tibet Plateau (QTP) holds massive freshwater resources and is one of the most active regions in the world with respect to the hydrological cycle. Soil moisture (SM) plays a critical role in hydrological processes and is important for plant growth and ecosystem stability. To investigate the relationship between climatic factors (air temperature and precipitation) and SM during the growing season in various climate zones on the QTP, data from three observational stations were analyzed. The results showed that the daily average (Tave) and minimum air temperatures (Tmin) significantly influenced SM levels at all depths analyzed (i.e., 10, 20, 30, 40, and 50 cm deep) at the three stations, and Tmin had a stronger effect on SM than did Tave. However, the daily maximum air temperature (Tmax) generally had little effect on SM, although it had showed some effects on SM in the middle and deeper layers at the Jiali station. Precipitation was an important factor that significantly influenced the SM at all depths at the three stations, but the influence on SM in the middle and deep layers lagged the direct effect on near-surface SM by 5–7 days. These results suggest that environment characterized by lower temperatures and higher precipitation may promote SM conservation during the growing season and in turn support ecosystem stability on the QTP.

scholarly journals Patterns and trends of high-impact weather in China during 1959–2014

2016 ◽  
Vol 16 (3) ◽  
pp. 855-869 ◽  
Author(s):  
Jun Shi ◽  
Kangmin Wen ◽  
Linli Cui
Keyword(s):  
Southern China ◽  
Eastern China ◽  
High Impact ◽  
Northeastern China ◽  
Central China ◽  
Western China ◽  
Tibet Plateau ◽  
High Mountain ◽  
Mitigation And Adaptation ◽  
High Impact Weather

Abstract. The spatial and temporal characteristics of the frequencies of four types of high-impact weather (HIW), i.e. snowfall, thunderstorms, fog and hailstorms, were analysed in China during 1959–2014. Results indicate a significant decrease in the number of snowfall days, thunderstorm days and thunderstorm spells in all six regions of China, with regional decreasing rates of 0.1–3.4 days, 1.6–5.1 days and 0.23–0.77 times per decade respectively. The number of foggy days, hailstorm days and snowfall spells decreased at rates of 0.2–1.8 days, 0.1–0.7 days and 0.14–0.44 times per decade respectively in almost all regions and fog and hailstorm spells decreased at rates of 0.06–0.17 and 0.001–0.043 times per decade respectively in most regions of China. Spatially, there was more snowfall in northeastern China and western China, and more thunderstorms in southern China and southwestern China. The number of fog events was larger in some high mountain stations, eastern China and central China. Hailstorms were concentrated on Qinghai–Tibet Plateau. Over the past 56 years, snowfall days, thunderstorm days and thunderstorm spells decreased in most parts of China, and hailstorm days decreased in northeastern China, most parts of northern China and Tibet, southern Qinghai and western Sichuan. The spatial trends of foggy days, foggy spells, snowfall spells and hailstorm spells were not significant in most parts of China. With global warming, some types of HIW are likely to increase in their intensities, so more mitigation and adaptation strategies are still essential for local government and the public in China.

scholarly journals Using MODIS Land Surface Temperatures for Permafrost Thermal Modeling in Beiluhe Basin on the Qinghai-Tibet Plateau

Sensors ◽  
2019 ◽  
Vol 19 (19) ◽  
pp. 4200 ◽  
Author(s):  
Anyuan Li ◽  
Caichu Xia ◽  
Chunyan Bao ◽  
Guoan Yin
Keyword(s):  
Surface Temperature ◽  
Land Surface ◽  
Ground Surface ◽  
Tibet Plateau ◽  
Active Layer Thickness ◽  
Permafrost Region ◽  
Thermal Dynamics ◽  
Near Surface ◽  
Warm Bias ◽  
Qinghai Tibet Plateau

It is essential to monitor the ground temperature over large areas to understand and predict the effects of climate change on permafrost due to its rapid warming on the Qinghai-Tibet Plateau (QTP). Land surface temperature (LST) is an important parameter for the energy budget of permafrost environments. Moderate Resolution Imaging Spectroradiometer (MODIS) LST products are especially valuable for detecting permafrost thermal dynamics across the QTP. This study presents a comparison of MODIS-LST values with in situ near-surface air temperature (Ta), and ground surface temperature (GST) obtained from 2014 to 2016 at five sites in Beiluhe basin, a representative permafrost region on the QTP. Furthermore, the performance of the thermal permafrost model forced by MODIS-LSTs was studied. Averaged LSTs are found to strongly correlated with Ta and GST with R2 values being around 0.9. There is a significant warm bias (4.43–4.67 °C) between averaged LST and Ta, and a slight warm bias (0.67–2.66 °C) between averaged LST and GST. This study indicates that averaged MODIS-LST is supposed to be a useful data source for permafrost monitoring. The modeled ground temperatures and active-layer thickness have a good agreement with the measurements, with a difference of less than 1.0 °C and 0.4 m, respectively.

Evaluation of the near-surface climate of the recent global atmospheric reanalysis for Qilian Mountains, Qinghai-Tibet Plateau

2021 ◽  
Vol 250 ◽  
pp. 105401
Author(s):  
Baojuan Huai ◽  
Junyao Wang ◽  
Weijun Sun ◽  
Yetang Wang ◽  
Wuying Zhang
Keyword(s):  
Qilian Mountains ◽  
Tibet Plateau ◽  
Near Surface ◽  
Surface Climate ◽  
Qinghai Tibet Plateau

scholarly journals Characterizations and source analysis of atmospheric inorganic ions at a national background site in the northeastern Qinghai-Tibet Plateau: insights into the influence of anthropogenic emissions on a high-altitude area of China

2019 ◽  
Author(s):  
Bin Han ◽  
Jing Wang ◽  
Xueyan Zhao ◽  
Baohui Yin ◽  
Xinhua Wang ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Eastern China ◽  
Photochemical Reactions ◽  
Water Soluble ◽  
Heterogeneous Reactions ◽  
Atmospheric Particulate Matter ◽  
Tibet Plateau ◽  
Source Analysis ◽  
Crustal Material ◽  
Qinghai Tibet Plateau

Abstract. Atmospheric particulate matter (PM) imposes highly uncertain impacts on both radiative forcing and human health. While ambient PM has been comprehensively characterized in China’s megacities; its composition, source, and characteristics in the Qinghai-Tibet Plateau (QTP) are not yet fully understood. An autumn observational campaign was conducted during the 1st–15th October 2013 at a national background monitoring station (3295 m a.s.l.) in the QTP. Real time concentrations of inorganic water-soluble ions (WSIs) associated with PM2.5 were measured in addition to PM2.5 concentrations, gaseous pollutants, and meteorological parameters. SO42− was the most abundant WSI (10.00 ± 4.39 μg/m3) followed by NH4+ (2.02 ± 0.93 μg/m3), and NO3− (1.65 ± 0.71 μg/m3). Observed WSI concentrations were lower as compared to urban sites in eastern China; however, they were higher as compared to other QTP monitoring sites. High sulfate and nitrate oxidation ratios indicated strong secondary formation of both SO42− and NO3−. Both photochemical and heterogeneous reactions contributed to the formation of particulate SO42−, while the conversion of NO2 to NO3− only occurred via photochemical reactions in the presence of high O3 concentrations and strong sunlight. Correlation analysis between WSIs revealed that NH4NO3, (NH4)2SO4, Na2SO4, and K2SO4 were the major atmospheric aerosol components. To better understand the potential sources of WSIs in the QTP, a Positive Matrix Factorization receptor model was used. Results showed that salt lake emissions, mixed factor emissions (livestock feces emission, occasional biomass burning, and crustal material), traffic emissions, secondary inorganic aerosols, and residential burning were the major emission sources at the study site.

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