植被返青是青藏高原陆地生态系统对全球气候变化响应的敏感指标。三江源位于青藏高原腹地，是研究气候和生态环境变化的敏感区和脆弱带。由于卫星遥感资料的时间序列太短，目前对三江源一带春季返青期（SOS）近十年变化趋势的研究存在争议，妨碍了对该区域长期气候变化特征的认识。

基于以上问题，中国科学院大气物理研究所严中伟、夏江江、于爽研究团队与中科院青藏高原研究所合作，利用长期气候观测结合遥感资料，发展了新的SOS测定方法。研究人员计算得到了三江源地区1960-2013年SOS的长期序列，并对其变化趋势进行了分析。研究表明，2000-2013年间，通过MODIS NDVI反演得到的SOS变化率为7.98d/dec；通过气温数据重建的SOS变化率为6.04d/dec。两者都远高于更长期的1960-2013年间测算的SOS提前变率1.42d/dec，验证了近十几年该区域气候快速变化的事实。进一步分析发现，2000-2013年间春季北极涛动AO指数与三江源SOS存在显著负相关，表明该区域近十几年快速气候变化与更大尺度的环流演变有关。

相关成果发表在Advances in Atmospheric Sciences上。（来源：中科院大气物理研究所）

Changing Spring Phenology Dates in the Three-Rivers Headwater Region of the Tibetan Plateau during 1960—2013

Abstract  The variation of the vegetation growing season in the Three-Rivers Headwater Region of the Tibetan Plateau has recently become a controversial topic. One issue is that the estimated local trend in the start of the vegetation growing season (SOS) based on remote sensing data is easily affected by outliers because this data series is short. In this study, we determine that the spring minimum temperature is the most influential factor for SOS. The significant negative linear relationship between the two variables in the region is evaluated using Moderate Resolution Imaging Spectroradiometer--Normalized Difference Vegetation Index data for 2000--13. We then reconstruct the SOS time series based on the temperature data for 1960--2013. The regional mean SOS shows an advancing trend of 1.42 d (10 yr)−1 during 1960--2013, with the SOS occurring on the 160th and 151st days in 1960 and 2013, respectively. The advancing trend enhances to 6.04 d (10 yr)−1 during the past 14 years. The spatiotemporal variations of the reconstructed SOS data are similar to those deduced from remote sensing data during the past 14 years. The latter exhibit an even larger regional mean trend of SOS [7.98 d (10 yr−1)] during 2000--13. The Arctic Oscillation is found to have significantly influenced the changing SOS, especially for the eastern part of the region, during 2000--13.

原文链接：http://159.226.119.58/aas/EN/10.1007/s00376-017-6296-y