东亚中高纬土壤温度资料评估与分析

本文以一套俄罗斯土壤温度历史观测资料RHSTD为基础,分析了四套土壤温度产品ERA-Interim再分析资料、两套陆面模式离线运行产品ERA-Interim/Land（简称ERA-Land）和MERRA-Land、以及一套二十世纪再分析资料NOAA-CIRES 20CR]在东亚中高纬的可靠性,并重点关注春夏季,主要结论如下:观测地温在0~2 m波动较大,随季节在0℃上下摆动,而2 m以下地温稳定少变,并且在60°N以北地区出现永久冻结。四套地温产品较好地反映了这些特征。无论春夏,还是年平均,四套地温产品气候态都呈“南暖北冷”的特征,但ERA-Land的空间分布与观测最接近。就季节循环而言,ERA-Land最能反映该地区土壤的冻融过程和土壤温度的季节演变。四套地温产品年际变率（标准差）与观测的差异随季节和土壤层变化大,情况比较复杂。就年际变化趋势而言,四套地温产品与观测的相关性,夏季好于春季,表层好于深层,并且ERA-Land土壤温度拥有四套地温产品最多的共性,最能反映观测地温的年际变化。

Evaluation and Analysis of Soil Temperature Data over Middle and High Latitudes of East Asia

This study investigates the qualities of four soil temperature reanalysis products over middle and high latitudes of East Asia based on a set of Russian historical soil temperature data (RHSTD).The four reanalysis products are the ERA-Interim re-analysis,ERA-Interim/Land (i.e.ERA-Land),and MERRA-Land generated by running land surface models offiine,and a 20th century reanalysis (i.e.the NOAA-CIRES 20CR).More emphases are put on the spring and summer,and main results are as follows.Large seasonal fluctuations of 0-2 m soil temperature around 0℃ are found in the RHSTD,but the soil temperature below 2 m stays relatively stable.Furthermore,the soil below 2 m is permanently frozen to the north of 60°N.The four reanalysis products well capture these characters.Regardless of the spring,summer or annual mean,the soil temperature climatology shown in the four reanalysis products is always "warm in the south and cold in the north",while the spatial pattern of the ERA-Land is the closest to observations.In terms of seasonal cycle,the ERA-Land at this region has a better performance in reflecting the soil freezing and thawing processes and the seasonal evolution of soil temperature.Situations are more complex regarding the interannual variability of soil temperature,i.e.standard deviation,because errors between these re-analysis products and observations vary with season and soil layer greatly.As for the interannual change,the correlation between each reanalysis product and observations is better in the summer than in the spring,and the correlation in the upper layer is better than that in the deep layer.Meanwhile,the ERA-Land is the most representative of the four re-analysis products.It better reproduces the interannual changes in observed soil temperature than the other three products.