从预报角度探讨乌鞘岭山区大气温差成因

Discussion on Formation Causes of Atmospheric Temperature Difference over Wushaoling Mountains for Prediction

利用2009年7月—2015年12月河西走廊东部乌鞘岭和天祝逐时气温、日照、地面2 min风场及每隔6 h云量资料,详细分析乌鞘岭山区大气温差、云量特征的时间变化及其预报关系,旨在提高天祝最低气温的预报准确率。结果表明:冬季08时气温乌鞘岭高于天祝的频率超过50%,温差强度达4~6℃;春夏季5—9月气温乌鞘岭高于天祝的频率低于40%,温差强度较弱在2℃以下。云量中夜间至清晨(02—8时)少,傍晚较多;5—9月较多,冬季较少。天空状况除冬季晴天多,出现频率高于50%外,其它季节阴天较多,晴天次之,多云较少,不足20%。乌鞘岭谷风多,而天祝山风多。气温乌鞘岭高于天祝的频率和强度与云量、山谷风、太阳照射时间、季节和天气系统密切相关。晴天和阴雨天气报准,天祝最低气温预报准确率最多可能提高30%,晴天报准时预报准确率最多可提高10%以上。

Using data of hourly temperature,sunlight and every2minutes surface wind,every6hours’cloud cover of Tianzhu and Wushaoling from July2009to December2015in eastern HexiCorridor,temporal variations of atmosphere temperature difference,cloud cover characteristics andtheir forecast relations were analyzed in detail over Wushaoling Mountain to improve minimumtemperature forecast accuracy in Tianzhu.The result showed that the percentage of temperature ofWushaoling is higher than that of Tianzhu over50%at morning8:00in winter,and thetemperature difference is about4~6℃.The percentage that Wushaoling temperature is higger thanTianzhuis less than40%in spring and summer,and the temperature difference is less than2℃.For cloud cover,it was less from night to morning but more at dusk,and more from May toSeptember but less in winter.For sky conditions,clear days were the most in winter,whosefrequencies were higher than50%.while cloudy days were more than clear days in other seasons.partly cloudy days were the lest,below20%in other seasons.Valley breeze is more in Wushaoling,but mountain breeze is more in Tianzhu.Temperature frequencies and intensities of Wushaoling arebigger than that of Tianzhu,it were closely related to cloud cover,mountainous terrain mountain andvalley breezes,and solar irradiation time,season and weather system.If the minimum temperaturesof sunny and rainy weather would be forecasted accurately,minimum temperature forecast accuracymay be improved by30%,sunny time forecast accuracy may be improved by more than10%.