荆门国家气象观测站夜间气温偏高原因分析与验证

Analysis and Verification on the Causes of the Higher Nighttime Temperature at Jingmen National Meteorological Observatory

  • 摘要: 荆门国家气象观测站(简称荆门站)自2008年迁入新址后,常在夜间出现较周边气象观测站气温大幅偏高的现象。为探究其原因,对比分析了其与邻近气象观测站2012—2021年的数据,发现:气温偏高常发生在春、秋、冬季,夏季较少,10—12月最多;发生频率最高时段为夜间,白天极少发生;2012—2021年温度偏高≥2 ℃的年发生天数为48~151 d,两站温差最大可达8.4 ℃;气温偏高时风速大幅度偏小,在偏西风时两站温差大于其他风向;晴天时最易出现气温偏高现象。根据统计分析的主要天气特征判断,该现象为夜间晴空辐射逆温造成,在风速较小、天气晴朗、大气水汽含量少的夜间极易发生辐射逆温,造成夜间位于山顶的荆门站气温高于山下平原地区的站点,且在偏西风时,城市热岛效应会使两站温差增大。最后,利用无人机边界层垂直探空试验验证了该结论,排除了偏北方向热源影响的说法。

     

    Abstract: Since Jingmen National Meteorological Observatory (hereinafter referred to as Jingmen Station) moved to the new location in 2008, there has been a significant higher nighttime temperature compared to the surrounding meteorological stations. An analysis of data from Jingmen Station and its neighboring station from 2012 to 2021 revealed that the higher temperature often occurred in seasons other than summer, most pronounced between October and December. The highest frequency of higher temperature was seen at night, but it was rarely captured during the daytime. From 2012 to 2021, the annual number of days of temperature difference ≥ 2 ℃ was 48-151, and the maximum temperature difference between the two stations could reach 8.4 ℃. The increased temperature difference was accompanied with the reduced wind speed. The temperature difference between the two stations was larger in westerly wind than in other wind directions. The temperature was most likely to be higher under the clear sky. According to the main weather characteristics derived from the statistical analysis, the nocturnal clear-sky radiative inversion was responsible for the phenomenon of higher temperature. Radiative inversion is highly likely to occur on nights with low wind speed, clear sky, and low atmospheric vapor content. This causes the temperature at Jingmen Station, located on the mountaintop, to be higher than that at stations in the plain areas. Moreover, when there is a westerly wind, the urban heat island effect can enhance the temperature difference between the two stations. Finally, the conclusion is verified by performing an unmanned aerial vehicle (UAV) boundary layer vertical sounding experiment, which rules out the possibility of the influence of the heat sources to the north of Jingmen Station.

     

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