Subjects: Geosciences >> Atmospheric Sciences submitted time 2023-05-30 Cooperative journals: 《干旱区研究》
Abstract： This study was initiated to explore the pollution status of Lanzhou City in recent years and provide a reference for its prevention and management. The daily air quality index and mass concentrations of PM2.5, PM10, SO2, NO2, O3 (8 h, the 8 h moving average of ozone), and CO from 2014 to 2021 were used to analyze the monthly, seasonal, and interannual variation characteristics of air pollution in the valley city of Lanzhou. The changes in air pollutants and the continuous characteristics of air pollution in Lanzhou were also analyzed. The results show that the number of short- term mild continuous and long- term moderate and severe continuous pollution processes peaked in winter, the number of short- term moderate and severe continuous pollution processes peaked in spring, no moderate and severe continuous pollution processes occurred in summer, and longterm mild continuous pollution processes occurred more often in fall and winter. Pollutants that play a major role in the process of continuous pollution differ because of different seasons, durations, and grades of continuous pollution. The main pollutant in the mild, moderate, and short- term severe continuous pollution processes in winter is PM2.5, and the main pollutants in the long-term severe continuous pollution process are PM2.5 and PM10. The main pollutant in the continuous pollution process in spring is PM10, the main pollutant in the mild continuous pollution process in summer is O3 (8 h), the main pollutant in the short-term mild continuous pollution process in fall is PM10, whereas the main pollutants in the long-term mild continuous pollution process are PM10, PM2.5, and NO2.
Subjects: Environmental Sciences, Resource Sciences >> Other Disciplines of Environmental Sciences, Resource Sciences submitted time 2021-03-02 Cooperative journals: 《干旱区研究》
Abstract：利用53个气象观测站1961—2017年5—9月逐日降水资料，分析了青藏高原东北部雨季降水量的变化特征，以及不同等级降水变化在降水量增量中的相对贡献。结果表明：1961—2017年青藏高原东北部干旱区雨季降水量呈增加趋势，半干旱区和半湿润区降水量的极端性增强。大部分地区的降水强度普遍增加。进一步分析可知，青藏高原东北部雨季降水量变化主要由降水强度的变化引起，同时中雨等级降水增加贡献大于其他等级降水。半湿润区和半干旱区东部降水极端化趋势明显增强。该结果有助于进一步理解和认识青藏高原东北部生态环境变化的气候效应。
Subjects: Environmental Sciences, Resource Sciences >> Other Disciplines of Environmental Sciences, Resource Sciences submitted time 2021-03-02 Cooperative journals: 《干旱区研究》
Abstract：利用Climatic Research Unit（CRU）1949—2018年最新0.5°× 0.5°网格点月均数据集，主要从EOF分解、小波分析的角度，讨论了泛中亚干旱区近70 a的气候变化特征。结果表明：（1）泛中亚干旱区近70 a降水以1.393mm·(10a)-1的速率呈增加趋势，夏季降水呈减少趋势，其余三季为增加趋势，其中冬季最明显［（0.834 mm·(10a)-1］，同时冬季增温幅度也最大［0.360 ℃·(10a)-1］；（2）降水距平场的EOF分析表明：泛中亚干旱区降水变化趋势呈整体一致性（降水第一模态），西南-东北反向变化特征（降水第二模态），由西向东“-+-”交替分布特征（降水第三模态），3个模态都存在显著的准3 a周期，第一模态还存在5~7 a和准12 a周期，第三模态存在准7 a变化周期；（3）温度距平场的EOF分析表明：温度距平变化表现出整体一致性（温度第一模态），东-西反向变化特征（温度第二模态），第一模态具有显著的准2 a、8~10 a周期，第二模态具有明显的2~4 a、准5 a周期。传统意义上的暖季并没有呈现出比较明显的增温多雨，冷季反而增温幅度更大，降水增加更明显。哈萨克斯坦中部、土库曼斯坦及蒙古国大部干旱化趋势明显，哈萨克斯坦东西两侧、我国新疆北部以及帕米尔高原的部分地方表现出显著的湿润化趋势，我国西北大部地区总体呈弱的湿润化趋势。随着亚洲夏季风的减弱，冷季降水增量高于暖季，这似乎说明亚洲冬季风对泛中亚干旱区降水的影响正在加大。本研究结果旨在加深对泛中亚干旱区气候变化特征的认识，为进一步防灾减灾、合理应对气候变化、坚持可持续发展战略提供科学依据。
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