Fine Spatial and Temporal Characteristics of Humidity and Wind in Beijing Urban Area

Dou Jingjing; Wang Yingchun; Miao Shiguang

Vol.25, NO.5, 2014

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Dou Jingjing, Wang Yingchun, Miao Shiguang. Fine spatial and temporal characteristics of humidity and wind in Beijing urban area. J Appl Meteor Sci, 2014, 25(5): 559-569.

Citation:

Dou Jingjing, Wang Yingchun, Miao Shiguang. Fine spatial and temporal characteristics of humidity and wind in Beijing urban area. J Appl Meteor Sci, 2014, 25(5): 559-569.

Dou Jingjing, Wang Yingchun, Miao Shiguang. Fine spatial and temporal characteristics of humidity and wind in Beijing urban area. J Appl Meteor Sci, 2014, 25(5): 559-569.

Citation:

Dou Jingjing, Wang Yingchun, Miao Shiguang. Fine spatial and temporal characteristics of humidity and wind in Beijing urban area. J Appl Meteor Sci, 2014, 25(5): 559-569.

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Fine Spatial and Temporal Characteristics of Humidity and Wind in Beijing Urban Area

1.
Chinese Academy of Meteorological Sciences, Beijing 100081
2.
Institute of Urban Meteorology, CMA, Beijing 100089
3.
Beijing Meteorological Service, Beijing 100089

Received Date: 2013-12-03
Rev Recd Date: 2014-06-05
Publish Date: 2014-09-30

Abstract

Abstract

The temporal and spatial characteristics of specific humidity, wind speed and direction in Beijing urban area and urban effects are investigated in terms of hourly automatic weather station data during 2008-2012.Results show that values of specific humidity (q) in urban areas are lower than those in rural area during summer daytime and early night in Beijing, which is known as "urban dry island"(UDI). Values show a multi-center distribution, due to the non-uniform distribution of non-evaporating urban impervious-surfaces, which decrease evapotrans-piration, increase run-off, and thus lower urban specific humidity levels. In winter, urban values of q are bigger than rural ones at most hours which are affected by anthropogenic emissions. Studies on 10-m wind directions show that they are affected by seasonal prevailing winds, topography and urban effects. During summer valley-breeze time, southerlies bypass Beijing urban area because of buildings, while air flows converge into city during summer mountain-breeze time due to combined effects of topography, urban effects and seasonal prevailing wind. During winter breeze-time, a convergence line is formed in northwest-southeast direction in urban area. Wind speeds are reduced by the large Beijing surface-roughness. A low-speed region is observed in more urbanized areas between Second Ring Road and Third Ring Road due to its high surface-roughess. It shows that humidity and air flow are strongly affected by urban effects besides the much studied "urban heat island" in Beijing. The local urban effects have to be taken into account in fine weather forecasting. In addition, the result will contibute to the discussion of urban atmospheric environmental governance and city planning and construction.
- Beijing urban area;
- low level;
- specific humidity;
- wind speed and direction;
- urban effect

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References(15)

Figures and Tables

Fig. 1 Study area (a) Beijing area with topographic-heights and study area (black square), rural stations (black dots), (b) remote sensing images of study area with AWS sites (black dots) (white triangles denote urban sites; red circles denote the Second, Forth, Sixth Ring Roads)

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图 2 2008—2012年平均2 m比湿水平分布

(单位：g·kg^-1；方框分别为北京二环路和四环路；阴影为地形高度)

Fig. 2 Seasonal averaged 2-m specific humidity during 2008-2012 in Beijing urban area

(unit:g·kg^-1; circles denote the Second and Fourth Ring Roads, the shaded denotes terrain height)

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Fig. 3 Diurnal variation of q of urban and rural areas in summer and winter

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Fig. 4 Diurnal variation of Δq in different seasons

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Fig. 5 Variations of pentad-mean Δq for five durations

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Fig. 6 Wind direction (vectors) of mountain-breeze and valley-breeze in four seasons (the shaded denotes terrain heights)

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图 7 2008—2012年四季平均10 m风速分布

(单位：m·s^-1; 方框分别代表为北京二环路和四环路，阴影为地形高度)

Fig. 7 Seasonal averaged 10-m wind speed during 2008-2012

(unit: m·s^-1; circles denote the Second and Fourth Ring Roads, the shaded denotes terrain heights)

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Fig. 8 Diurnal variation of regional averaged 10-m wind speed in different seasons

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Fig. 9 Diurnal variation of ΔV in different seasons

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Fig. 10 Diurnal variation of averaged speed difference between different loop areas and rural sites

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Table 1 The beginning and ending time of valley and mountain breeze in four seasons

季节	山风		谷风
季节	起始时刻	结束时刻	起始时刻	结束时刻
春季	02:00	10:00	11:00	01:00
夏季	05:00	10:00	11:00	04:00
秋季	22:00	12:00	13:00	21:00
冬季	20:00	14:00	15:00	19:00

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References

[1]	苗世光, 王迎春.基于用户需求的城市气象研究:进展与展望.气象科技进展, 2008, 4(1):6-14. http://www.cnki.com.cn/Article/CJFDTOTAL-QXKZ201401005.htm
[2]	Hage K D.Urban-rural humidity differences.J Appl Meteor, 1975, 14:1277-1283. doi: 10.1175/1520-0450(1975)014<1277:URHD>2.0.CO;2
[3]	Oke T R.Boundary Layer Climates.London:Routledge Press, 1987.
[4]	Chandler T J.The Climate of London.London:Hutchinson Press, 1965.
[5]	Fujibe F.Long-term surface wind changes in the Tokyo metropolitan area in the afternoon of sunny days in the warm season.J Meteor Soc Japan, 2003, 81(1):141-149. doi: 10.2151/jmsj.81.141
[6]	张光智, 王继志.北京及周边地区城市尺度热岛特征及其演变.应用气象学报, 2002, 13(1):43-50. http://qikan.camscma.cn/jams/ch/reader/view_abstract.aspx?file_no=20140605&flag=1
[7]	Yang P, Ren G, Liu W.Spatial and temporal characteristics of Beijing urban heat island intensity.Journal of Applied Meteorology and Climatology, 2013, 52(8):1803-1816. doi: 10.1175/JAMC-D-12-0125.1
[8]	Liu W, You H, Dou J.Urban-rural humidity and temperature differences in the Beijing area.Theor Appl Climatol, 2009, 96(3-4):201-207. doi: 10.1007/s00704-008-0024-6
[9]	苗世光, 孙桂平, 马艳, 等.青岛奥帆赛高分辨率数值模式系统研制与应用.应用气象学报, 2009, 20(3):370-379. doi: 10.11898/1001-7313.20090315
[10]	苗世光, Chen F, 李青春, 等.北京城市化对夏季大气边界层结构及降水的月平均影响.地球物理学报, 2010, 53(7):1580-1593. http://www.cnki.com.cn/Article/CJFDTOTAL-DQWX201007010.htm
[11]	胡玉峰.自动与人工观测数据的差异.应用气象学报, 2005, 15(6):719-726. http://qikan.camscma.cn/jams/ch/reader/view_abstract.aspx?file_no=20040689&flag=1
[12]	李雁, 梁海河, 孟昭林, 等.自动气象站运行效能统计.应用气象学报, 2009, 20(4):504-509. doi: 10.11898/1001-7313.200904017
[13]	杨萍, 刘伟东, 仲跻芹, 等.北京地区自动气象站气温观测资料的质量评估.应用气象学报, 2011, 22(6):706-715. doi: 10.11898/1001-7313.20110608
[14]	窦以文, 屈玉贵, 陶士伟, 等.北京自动气象站实时数据质量控制应用.气象, 2008, 34(8):77-81. doi: 10.7519/j.issn.1000-0526.2008.08.012
[15]	张华林, 陈松, 曲金枝.北京气候志.北京:北京出版社, 1987.