2002—2011年11月抚顺市极端最低气温定量分析

利用抚顺市2002—2011年11月月极端最低气温出现的夜间常规气象要素观测资料以及micaps系统资料,通过温度变化方程,对抚顺市过去10年11月的月极端最低气温过程在地面和850hPa2个层面,从温度的平流变化、绝热变化和非绝热变化3个方面分别进行了对比分析。结果表明:在多数情况下,850hPa的平均冷平流强度低于1000hPa;在地面,除强冷平流外,一般情况下温度的平流变化与非绝热变化相比很小,常可忽略不计,夜间气温的下降大多数是由非绝热作用引起的;由于抚顺周围的特殊地形,当吹较强的西北风时容易形成乱流混合增温现象。这种现象可在一定程度上补偿夜间的辐射降温,从而使夜间的气温不至于降得太低;在850hPa,当温度露点差≤5℃时,可使850hPa的温度升高2℃以上。

Quantitative Analysis of Monthly Extreme Minimum Temperature in November from 2002 to 2011 in Fushun City

Based on the routine meteorological elements at night and micaps data of monthly extreme minimum temperature appeared inNovember from 2002 to 2011 in Fushun City,using the temperature variation equation the temperature variation of the advection term of monthlyextreme minimum temperature process in November during past 10 years were compared and analyzed in ground and 850 hPa layer.The results showedthat:In most cases,the average cold advection strength in 850 hPa was lower than that of 1 000 hPa.In the ground,compared with radiant cooling,advective cooling could be negligible in addition to strong cold advection,temperatures drop at night mostly caused by the non-adiabatic role.Inaddition,due to the special terrain around Fushun,turbulent mixing warming phenomenon was easy to form when a strong northwest wind blowing.Thisphenomenon may some extent compensate for night radiation cooling,the nighttime temperature would not drop too low.When the dew-point deficit in850 hPa was below 5 ℃,the temperature in 850 hPa can be increased by 2 ℃.