基于美国国家航空航天局(NASA)最新发布的具有代表性浓度途径的全球逐日统计降尺度NEX-BCC_CGM1.1气候数据集,采用线性拟合、EOF分析等方法,评估其对秦岭及周边地区降水、温度的模拟能力,并分析中浓度(Rcp4.5)和高浓度(Rcp8.5) 2种情景下未来阶段秦岭及周边地区降水、日最高温度和日最低温度的可能变化,主要结论如下: ① NEX-BCC_CGM1.1对秦岭及周边地区日平均降水量、最高温度和最低温度的年际变化趋势模拟较好,要素的空间分布和观测整体吻合,存在的不足在于要素值大小和极值频率与观测存在系统性的偏差。②Rcp4.5和Rcp8.5 2种情景下未来秦岭及周边地区日平均降水量呈增加的趋势;从不同量级降水频次来看,未来小雨发生频次减少,暴雨频次增加; 2种情景下未来降水的空间模态均表现为全区一致降水增加型EOF1和秦岭南北反位相变化型EOF2,其中EOF1在21世纪中期处于正位相,降水显著偏多。③2种情景下,温度增温趋势十分明显,其中日平均最高温度增幅大于日平均最低温度,Rcp8.5情景增温幅度高于Rcp4.5。未来日最高温度大于36 ℃的高温频次增加,小于-15 ℃的低温频次减少,且Rcp8.5情景下高温(低温)频次增加(减少)幅度更加显著。2种情景下,日平均最高和最低温度均表现为全区一致性增温和南北反位相2种空间模态,但模态的空间分布存在较大差异。
英文摘要:
Based on NEX-BCC_CGM1.1 global daily statistics downscaling climate data set,the latest release by American National Aeronautics and Space Administration (NASA),which has representative concentration path,by using linear fitting and empirical orthogonal function (EOF) analysis methods,the simulation capacity on precipitation and temperature in Qinling and its surrounding areas of this data sets was estimated and the possible changes of the precipitation,daily maximum and minimum temperature in the next stage under the two scenarios of Rcp4.5 and Rcp8.5 were analyzed. Results showed that: ①The inter-annual trend of average daily precipitation, maximum temperature,minimum temperature is simulated well by NEX-BCC_CGM1.1. The spatial distribution was in accordance with the observations. The deficiency is that the elements value and extreme frequency have systemic bias compared with the observations. ②Average daily precipitation will have increasing trend in the future in Qinling and its surrounding areas under the two scenarios of Rcp4.5 and Rcp8.5. For different level precipitation frequency,light rains will reduce and rainstorms will increase in the future. The spatial modes of precipitation in the future are shown as the variation of the uniform increase in the whole region (EOF1) and anti-phase change in northern and southern Qinling (EOF2). EOF1 will be positive phase in medium-term in the Mid-21st century, where there will be significantly more means precipitation. ③Under the two scenarios,temperature warming trend is obvious,daily maximum temperature increasing trend is greater than minimum temperature,and the amplitude of temperature increase under Rcp8.5 is higher than Rcp4.5. The frequency of daily maximum temperatures greater than 36 ℃ will increase and low temperature less than -15 ℃ will reduce in the future,at the same time,high temperature (low temperature) increase (decrease) rate is more pronounced under Rcp8.5. Average daily maximum and minimum temperatures are shown uniform warming in the whole region (EOF1) and anti-phase change in northern and southern Qinling under two scenarios,but the spatial distribution has great difference.