Subjects: Geosciences >> Geography submitted time 2024-01-28 Cooperative journals: 《干旱区地理》
Abstract：利用19802019年欧洲中期天气预报中心提供的ERA5月平均再分析数据和全球降水气候中心（GPCC）提供的逐月降水数据，分析中亚前期5月土壤湿度异常对后期6月局地降水变化的影响。结果表明：（1） 中亚春季逐月土壤湿度总体表现为北部和中部高、西南和东南低的空间分布特征；34月土壤湿度年际变化的大值区主要位于中亚西南部；中亚北部土壤湿度在3月呈显著增加趋势，45月显著减少；中亚西南部3月土壤湿度显著减少。（2） 中亚中部地区5月土壤湿度异常与当地6月的降水变化呈显著正相关，通过95%信度检验。5月土壤湿度正异常可以持续到6月，导致6月局地蒸发量增加，大气可降水量增多；同时地表向上潜热通量增加、感热通量减少、波恩比减小，进而导致大气边界层降低、低层大气湿熵增加、对流不稳定能量增大，有利于降水天气的发生。（3） 前冬Nio3.4指数与中亚中部地区次年5月土壤湿度和6月降水异常都呈显著正相关，5月土壤湿度是厄尔尼诺-南方涛动（ENSO）影响次年6月中亚中部地区降水异常的重要媒介，但土壤湿度可独立于ENSO影响6月降水。
Subjects: Geosciences >> Geography submitted time 2022-12-14 Cooperative journals: 《干旱区研究》
Abstract：
The arid regions of Central Asia, which are“upstream”of China in terms of their influence on weather and climate, are characterized by a general shortage of water resources and the fragility of ecosystems. The atmospheric water cycle is the key link in the transformation of water resources and ecosystems in this region. In this study, we reassessed the temporal and spatial variation of water cycle elements, such as atmospheric water vapor content, water vapor budget, precipitation, and actual evaporation, in the arid region and subregions of Central Asia, from 1979 to 2018. The results of our analysis show clear spatial differences in the water cycle elements of Central Asia. Precipitation and actual evaporation are high in mountainous areas, such as Tianshan Mountains and Pamir and surrounding oasis areas, and low in the desert plain areas, whereas atmospheric water vapor content shows an opposite pattern. In terms of temporal changes, from 1979 to 2018, the water vapor content in Central Asia showed a weak decreasing trend, with obvious regional differences in the rate of change. Water vapor content in the surrounding areas of the Aral Sea decreased significantly, whereas in most of the areas of the Xinjiang and Tianshan Mountains, it increased significantly. Zonal transport is the main mode of water vapor transport in Central Asia, compared with the relatively weak meridional transport. Large differences were found in the water vapor budget over different regions; the water vapor transport tended to decrease in the western and northern boundaries and increased in the eastern and southern boundaries. Water vapor revenue and expenditure showed an increasing trend in northwestern Central Asia, southern Central Asia, the Pamir Plateau, and the Tianshan Mountains and a decreasing trend in northern Central Asia and most of Xinjiang. In contrast to the change in water vapor transport, the precipitation in Central Asia increased from 1979 to 2018, with an increase of 4.14 mm·(10a)-1 and a large interannual fluctuation. The significant increasing trend of precipitation is distributed in northern Central Asia and most of the Xinjiang and Tianshan Mountains, whereas there was a significant decreasing trend in northwestern and southern Central Asia. The actual evaporation in Central Asia showed a slight increasing trend, increasing significantly in the northern part of Central Asia, the Tianshan Mountains, and Pamir but decreasing significantly in the Caspian Sea area, Aral Sea, southern Central Asia, and southern Xinjiang. In terms of seasonal variation, the temporal and spatial distribution of seasonal and annual variations of water cycle elements was generally consistent. The results of our analysis contribute to a better understanding of the evolution and mechanism of the atmospheric water cycle in the arid regions of Central Asia.
Subjects: Geosciences >> Atmospheric Sciences submitted time 2022-01-21 Cooperative journals: 《干旱区地理》
Abstract：天山山区是新疆干旱区降水最为充沛的区域，已有针对该区域降水的研究大多使用日降水及以上尺度资料，降水日变化特征分析相对较少。基于天山山区11个国家气象站20122018年夏季（68月）逐小时降水资料，分析降水特征量（包括降水量、降水频次和降水强度）的日变化特征，揭示降水与海拔高度的关系。结果表明：总降水量和总降水频次的峰值出现在20:0022:00，谷值出现在12:0013:00。夜间降水多于白天，主要由长时降水贡献。总降水强度呈现出白天整体增强、夜间偏弱的特征。降水与海拔高度密切联系，小雨等级降水在高海拔山区频发，在海拔2000 m左右存在一个最大降水带。
Subjects: Geosciences >> Other Disciplines of Geosciences submitted time 2019-09-10 Cooperative journals: 《干旱区研究》
Abstract：基于图形学分析技术，采用追踪算法、矢量分析法，利用常规MICAPS数据、NECP逐日再分析资料和EC细网格资料,对我国西北地区致旱天气系统进行识别试验。通过试验，得到如下结论：① 依据天气学定义，利用追踪算法能够成功识别高空槽、高空脊等主要系统,并可得到其曲率特征；② 利用该方法识别天气尺度系统，系统中心识别率高达90%以上、平均误差小于0.5°，而高空槽识别准确率为74%~87%，平均识别误差为0.7°~1.4°。利用风场进行订正后，准确度明显提高、误差有所减小，基本可以满足干旱预测、预报业务需求。
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