气候态调整对华北冬、夏季气候监测的影响研究

Differences between Various North China Climatic Normals in Winter and Summer:A Study of Its Impact on Climate Monitoring

本研究对比分析了不同气候态下,华北冬、夏季降水及气温的差异,分析了气候平均值的改变对历史极端事件监测的可能影响。研究结果发现,1991~2020年(简称气候Ⅱ态)的冬季和夏季的平均降水量均略多于1981~2010年(简称气候Ⅰ态),但接近或略少于1961~2020年的平均降水量,平均降水量逐年变化幅度冬季Ⅱ态小于Ⅰ态,夏季反之。气候Ⅱ态冬季降水空间分布不均,夏季较Ⅰ态呈“中部减少,东西增加”的分布型。冬季和夏季极端降水阈值Ⅱ态(0.86 mm和22.0 mm)较Ⅰ态(0.83 mm和21.6 mm)均略有提高,造成近60年华北大部基于Ⅱ态阈值的冬、夏季极端降水日数较Ⅰ态略减少。此外,气候Ⅱ态的华北冬、夏季平均气温均明显高于Ⅰ态,也高于1961~2020年平均值。Ⅱ态气温较Ⅰ态基本呈全区增加特征,但空间分布不均匀。冬季极端低温和夏季极端高温阈值Ⅱ态(-9.8℃和27.9℃)较Ⅰ态(-10.2℃和27.5℃)均有所有所提高,造成华北大部分地区基于Ⅱ态阈值的近60年冬季极端低温日数较Ⅰ态有所增加,夏季极端高温日数较Ⅰ态存在不同程度的减少。因此,新气候态下华北气温和降水均值,华北大部极端降水阈值和极端气温阈值均有所提高,造成气候监测中更容易出现气温偏低,降水偏少,历史极端事件监测中极端事件略减少的情况,在未来10年的气候监测预测业务中要充分考虑新气候态可能造成的影响。

This research compared and analyzed the precipitation and temperature differences in North China during winter and summer under different climate conditions to explore the characteristics and differences between various climate normals in this region and their impacts on regional climate monitoring.Then,we analyzed the impact of these average climatic changes on extreme historical events.Investigations revealed that although the average precipitation in winter and summer during 1991–2020(climate stateⅡ)was more than that during 1981–2010(climate state I),it was lesser than that in 1961–2020.However,the annual variation of stateⅡwas smaller than that of stateⅠin winter,whereas vice versa in summer.Furthermore,although the stateⅡclimate precipitation of the different regions varied in winter,it decreased in the central area and increased in the eastern and western parts of North China in summer.Also,we observed that the average winter and summer extreme precipitation thresholds in North China were higher in stateⅡ(0.86 and 22.0 mm)than in stateⅠ(0.83 and 21.6 mm),causing several extreme precipitation days in winter and summer in most parts of North China for the past 60 years.This event,however,reduced corresponding to stateⅡthanⅠ.Although the average winter and summer temperatures of stateⅡwere significantly higher than those of stateⅠ,they remained higher than the average winter and summer temperatures of 1961–2020,indicating that while stateⅡtemperatures maintained the characteristic of being overall warmer than stateⅠ,the change characteristics of the different regions varied.Conversely,the extremely low average winter temperature and the extremely high summer temperature threshold in stateⅡ(−9.8℃ and 27.9℃)exceeded those in stateⅠ(−10.2℃ and 27.5℃),causing several extremely low winter temperature days in most parts of North China corresponding to stateⅡfor the past 60 years.While this event increased compared with stateⅠ,the extremely high summer temperature days corresponding to stateⅡreduced to varying degrees compared with stateⅠ.Overall,our investigations propose that applying new climate normals will increase the extreme precipitation and extreme temperature thresholds in most parts of North China,leading to more frequent low temperatures,less precipitation,and less extreme historical climate events in climate monitoring.Hence,the possible impact of the new climate normals on climate monitoring and prediction over the next decade should be fully considered.