武汉气象站周边环境对日照观测的影响

INFLUENCE OF SURROUNDING ENVIRONMENT ON SUNSHINE OBSERVATION IN WUHAN METEOROGOLOGICAL OBSERVING STATION

利用武汉气象观测站迁站前(2007年)、后(2013年)周边观测仰角记录,运用气候学方法计算任意时刻太阳的高度角和方位角,建立因周边环境对日照观测影响的计算方法,得到理论上周边环境对日照观测的影响时间。同时,考虑到实际天气条件的影响,引入云量因子,定量分析实际状况下周边环境对日照观测的影响。结果表明:1)在仅考虑周边环境对日照观测影响情况下,迁站前周边环境对日照观测的遮挡率为7.3%,迁站后,遮挡情况有明显改善,遮挡率降至1.0%;2)考虑实际天气条件下,引入云量因子,日照观测在晴日仅受建筑物影响,在阴天完全不受建筑物影响,在多云天用天空未被遮蔽的比例来表征受建筑物遮挡影响的程度;3)假定以2007年武汉站周边观测仰角代表迁站前的周边观测环境,以2013年观测的周边观测仰角代表迁站至今的观测环境,得到近10 a因周边环境造成的武汉站日照观测缺失时间,迁站前(2004~2009年)周边环境对日照观测的遮蔽率为5.4%,迁站后(2010~2013年)遮蔽率降为0.7%。

Using observing elevation records of the old Wuhan meteorological observing station （2007） and the new one （2013）, the solar elevations and azimuths at arbitrary time were calculated by using climatology method. The calculation method for the influence of surrounding environment on the sunshine observation was established to get the influence hours of sunshine observation theoretically. At the same time, considering the influence of the actual weather conditions, the influence of surrounding environment on sunshine observation was analyzed quantitatively by introducing cloud cover factor. The results show that when only considering the surrounding shading condition, the sunshine observation occlusion rate effected by surrounding environment before station migration was 7.3%. While after station migration, the occlusion rate was reduced to 1.0%, meaning a significant improvement. Considering actual weather condition, cloud cover factor being introduced, the sunshine observation was impacted only by buildings during sunny days and totally didn＇t be affected by buildings during cloudy days. The proportion of uncovered sky was used to characterize the influence degree by building in cloudy days. If using the observing elevation surrounding Wuhan station in 2007 to represent surrounding environment before station migration and using observing elevation in 2013 to represent the observation environment since station migration, the lack hours of observation sunshine affected by surrounding environment in recent ten years of Wuhan station was obtained, the sunshine observation occlusion rate effected by surrounding environment before station migration （ 2004-2009 ） was 5.4% and reduced to 0.7% after station migration （ 2010-2013 ）.