豫东北地面最高和最低温度非对称变化的诊断分析

Diagnosis Analysis on Asymmetric Change of Ground Maximum and Minimum Temperature in the Northeast of Henan Province

利用1958～2007年豫东北4个代表站逐月平均地温资料,采用线性分析方法和相关分析方法,研究了豫东北近50年地面最高和最低温度的变化趋势和气象影响因子。结果表明,地面最高、最低温度明显存在非对称变化,主要特征是地面年平均最高温度呈明显递减趋势,而地面年平均最低温度呈递增趋势,二者变化倾向率分别为-0.90和0.34℃/10a;地面年平均温度为下降趋势,其递减倾向率为-0.23℃/10a;近50年地面平均最高温度降低了4.5℃,地面平均最低温度却升高了1.7℃,平均地面温度下降了1.2℃。各月地面温度变化趋势差别明显5,～9月明显趋凉,其中6月趋凉最突出,其地面平均最高温度递减倾向率达-2.16℃/10a;12月～翌年4月明显趋暖,其中2月趋暖最突出,其地面平均最低温度递增倾向率为0.76℃/10a;地面温度变化具有夏季趋凉、冬季趋暖的显著特征。年平均地气温差逐年递减,近地层大气稳定度增加,不利于近地层污染物和水汽扩散,由此带来轻雾日数增多,空气污染加重。相关气象因子诊断分析表明,引起地面温度趋降的原因较多,主要是日照时数减少,地面受到太阳直接辐射减少;其次是空气湿度增加、空气污染物增多,降低了太阳直接辐射的强度;此外,降水量减少,土壤湿度减小,使土壤热容量减小,保温能力下降,导致地面温度降低。

Using monthly mean ground temperature of four stations in Northeast of Henan Province during 1958-2007,the variation trend of ground maximum and minimum temperature in recent 50 years in the Northeast of Henan Province and meteorological factors were studied by using linear and correlative analysis method.The results showed that the ground maximum temperature and minimum temperature obviously represent asymmetric change,the ground annual mean maximum temperature showing obviously decreasing trend,while the annual mean minimum temperature showing increasing trend,the variation tendency rate are-0.90 and 0.34 ℃/10a;the ground annual mean temperature showed decreasing trend,the decreasing tendency rate is-0.23 ℃/10a;in recent 50 years,ground mean maximum temperature decreasing 4.5 ℃,average minimum temperature increasing 1.7 ℃,average ground temperature decreasing 1.2 ℃.The variation trend of ground temperature in each month has significant difference,May-September tend to cold,among which,July is obviously,the decreasing intendancy rate of ground mean maximum temperature up to-2.16 ℃/10a;December-April of next year tend to warm,among which February is prominent,the increasing intendancy rate of ground mean minimum temperature up to 0.76 ℃/10a.The diagnosis analysis of correlated metrological factors showed that the main cause for ground temperature decreasing is less of solar direct radiation;secondly is the increasing of air humidity and pollutants leading to decreasing of solar direct radiation intensity;last is the decreasing of soil humidity,precipitation leading to reducing of soil thermal capacity and heat-retaining capacity.