Subjects: Other Disciplines >> Synthetic discipline submitted time 2023-03-28 Cooperative journals: 《中国科学院院刊》
Abstract： Snow cover over the Qinghai-Tibet Plateau (QTP) is a key element of Asian Water Tower. It is also an important indicator of weather and climate change. Its spatio-temporal changes can influence the regional climate and ecosystem. In this study, the spatiotemporal distribution and trends of snow cover were analyzed based on remote sensing data, and its hydrological and climate effects were also explored. The results show the followings: (1) Snow cover was dominantly distributed in mountainous areas, and the largest snow depth and Snow Cover Days (SCD) were found in the Dangla and Nianqing Dangla Mountains, with the average SCD of over 120 days, and annual average snow depth of over 10 cm; whilst there was few snow cover in the plain area and Qaidam Basin, e.g. ephemeral snow cover, with average SCD of less than 15 day and annual snow depth of less than 1 cm. (2) Snow cover days and depth were decreased in the period of 1980–2018, especially after the year of 2000. (3) There was large radiative forcing in the mountainous areas with deep snow and large SCD, and the maximum value beyond 15 W m−2; thus, the snow cover over QTP plays important feedbacks to the climate system. (4) The QTP is the source of runoff in headwater regions of many rivers, and snow melt water contributed to the soil moisture and river runoff in spring. (5) The frequency of snow disaster was increased by extreme weather events, and early warning system and protective measures should be enhanced to minimize the loss caused by snow disaster.
Subjects: Environmental Sciences, Resource Sciences >> Basic Disciplines of Environmental Science and Technology submitted time 2019-06-13 Cooperative journals: 《干旱区地理》
Abstract：利用银川市国家基准气象站及受人类活动影响较少的麻黄山气象站1961—2015年气温、降水及相对湿度资料，对比分析了城市化及湖泊湿地修复对银川市城市气候演变的影响。结果表明：随着银川市城市化规模的不断扩大，整个城市的暖干化程度日趋严重，城市周边湖泊湿地的修复和重建对银川市大范围气候的调节作用明显弱于城市化的影响。具体表现为：自1961年以来，银川站年平均气温上升速率为0.46 ℃·(10 a)-1，比麻黄山站快0.16 ℃·(10 a)-1，银川市城市化使城市内年平均气温较对比站麻黄山站升高1.1 ℃，特别是2001—2015年上升了0.8 ℃，2011—2015年上升了0.5 ℃，其中冬季上升快，夏季相对稳定，气温年较差减小；从1975年以来，银川市年平均空气相对湿度下降了11.2 %。
Subjects: Environmental Sciences, Resource Sciences >> Basic Disciplines of Environmental Science and Technology submitted time 2019-06-13 Cooperative journals: 《干旱区地理》
Abstract：暴风雪天气是内蒙古草原牧区危害严重的气象灾害之一。为了更确切的了解暴风雪灾害天气的特征，分季节对暴风雪天气进行了类型，即秋末初春暴风雪天气、隆冬暴风雪天气、春末初夏湿雪冷雨型暴风雪天气；通过因子分析法、灰色关联分析对三种类型暴风雪天气进行分析，发现上述三种类型暴风雪天气都为风、雪、寒潮灾害群天气；每个季节最主要的影响因子不同，导致的灾害程度不同；因此掌握各个季节暴风雪天气的特征对预报员提高预报预警水平很有实际意义。尝试使用BP神经网络法、支持向量机对暴风雪灾害等级进行评估，通过与根据灾情评定的灾害等级对比分析，发现SVM方法的评估效果优于BP神经网络法，因此，基于数值预报产品通过SVM方法做暴风雪灾害预警产品成为可能，可为暴风雪灾害预报预警业务提供客观参考依据，能够提升预报服务效果，减少灾害损失。
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