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干旱区地理 ›› 2020, Vol. 43 ›› Issue (4): 977-996.doi: 10.12118/j.issn.1000-6060.2020.04.13

• 气候与水文 • 上一篇    下一篇

乌鲁木齐市城区和郊区近地层比湿分布和廓线特征

李振杰1,2,3, 金莉莉4,5, 何清4,5, 缪启龙5, 买买提艾力·买买提依明4   

  1. 1 云南省临沧市气象局,云南 临沧 677099;
    2 中国科学院新疆生态与地理研究所,新疆 乌鲁木齐 830011;
    3 中国科学院大学,北京 100049;
    4 中国气象局乌鲁木齐沙漠气象研究所/中国气象局塔克拉玛干沙漠气象野外科学试验基地,新疆 乌鲁木齐 830002;
    5 南京信息工程大学应用气象学院,江苏 南京 210044
  • 收稿日期:2019-07-05 修回日期:2020-03-15 出版日期:2020-07-25 发布日期:2020-11-18
  • 作者简介:李振杰(1982–),男,河南濮阳人,在读博士研究生,工程师,主要从事天气预报、系统开发工作和气候变化水文水资源研究. E-mail:lizhenjie17@163.com
  • 基金资助:
    中国沙漠气象科学研究基金(Sqj2016006,Sqj2015009); 中央级公益性科研院所基本科研业务费(IDM2020001); 新疆维吾尔自治区高层次人才引进(2016-金莉莉)资助

Characteristics of specific humidity distribution and profiles in Urumqi City and suburbs

LI Zhen-jie1,2,3, JIN Li-li4,5, HE Qing4,5, MIAO Qi-long5, ALI Mamtimin4   

  1. 1 Lincang Meteorological Bureau,Lincang 677099,Yunnan,China;
    2 Xinjiang Institute of Ecology and Geography,Chinese Academy of Sciences,Urumqi 830011,Xinjiang,China;
    3 University of Chinese Academy of Sciences,Beijing 100049,China;
    4 Taklimakan Desert Meteorology Field Experiment station of CMA,Institute of Desert Meteorology,China Meteorological Administration,Urumqi 830002,Xinjiang,China;
    5 College of Applied Meteorology,Nanjing University of Information Science and Technology,Nanjing 210044,Jiangsu,China
  • Received:2019-07-05 Revised:2020-03-15 Online:2020-07-25 Published:2020-11-18

摘要: 利用乌鲁木齐市城区和郊区的5座100 m气象铁塔10层比湿数据和乌鲁木齐气象站L波段探空雷达资料,详细分析了边界层2 km内比湿廓线特征,城区和郊区近地层比湿季节变化和日变化特征,揭示了乌鲁木齐逆湿的原因,得出以下结果:(1) 乌鲁木齐市比湿季节差异明显,冬季最小,春季、秋季稍大,夏季最大,夏季比湿约为冬季的4~5倍,但秋季仅比春季大1 g·kg–1。除冬季外,比湿均随高度增加而趋于减小,夏季减小最显著,冬季比湿的垂直变化很小。比湿廓线极小值白天和夜间出现高度相近,且有多个极小值。夏季和冬季比湿日变化最大,且位相相反;夏季夜间大、白天小,冬季与之相反。冬季,郊区比湿小于城区;其余季节城、郊比湿差异不明显。(2) 2 km内存在逆湿现象,逆湿出现概率高于35%,概率1月最大、7月最小。1月逆湿最大高度超过1 500 m,7月逆湿最大高度可达到1 900 m,且最大厚度可达到1 550 m。逆湿强度最大在7月和10月可达2. 5 g·kg–1·(100 m)–1,而1月最小。(3) 1月逆湿往往与逆温相伴随,逆温层改变了水汽的垂直分布结构,从脱地逆温层顶起出现逆湿现象,逆湿还与水汽输送有关。本研究可以有效地揭示空气湿度的季节特征,为研究城市大气污染形成的气象因素提供了一个思路。

关键词: 边界层, 比湿, 廓线, 乌鲁木齐

Abstract: Observations from L-Band radar and 10-layer data collected at five 100-m-high meteorological towers in Urumqi City,Xinjiang,northwestern China were used to analyze the characteristics of the specific-humidity profile within 2 km,including seasonal and diurnal variation in urban and suburban Urumqi. The results,which reveal moisture inversion,were as follows:(1) The levels of specific humidity vary by season (summer>autumn>spring>winter). In summer,specific humidity is about 4-5 times that of winter,and that of autumn is ~1 g ·kg-1 more than in spring. In spring,summer,and autumn,the specific humidity was less at greater heights,especially in summer,whereas the change with height was less in winter. Multiple minimum values appeared on the specific humidity profile,and the appearance height is basically the same. The daily variation of specific humidity was the most in summer and winter but opposite in phase during these seasons. The specific humidity is high (low) at night,low (high) during the day in summer (winter). Specific humidity is less in the suburbs than in urban areas in winter,but it is the urban-suburban difference is less obvious in the other seasons. (2) Moisture inversion is evident within 2 km. Its probability is>35%. January shows the maximum probability,and July,the minimum. In January,the maximum height of moisture inversion is>1 500 m,but in July it can reach 1 900 m,with a maximum thickness of<1 550 m. The maximum moisture inversion was 2.5 g·kg-1 per 100 m in July and October,and the minimum was in January. (3) Moisture inversion often was accompanied by temperature inversion in January in Urumqi. The vertical distribution of water vapor changed according to the temperature-inversion layers. The moisture inversion,which is also related to water-vapor transport,usually appeared from the top of the temperature-inversion layer. This study can effectively reveal seasonal characteristics of air humidity and provide a basis for studying meteorological factors affecting air pollution in cities.

Key words: boundary layer, specific humidity, profile, Urumqi City