2000—2017年内蒙古地区VCI对不同时间尺度SPEI的响应

Response of VCI to SPEI at Different Time Scales from 2000 to 2017 in Inner Mongolia

为了深入了解内蒙古地区各植被类型对不同时间尺度气象干旱指数的响应情况。利用2000—2017年内蒙古地区82个气象站的监测资料和NASA的MOD13Q1植被监测产品,计算内蒙古地区VCI与30、60、90、120、150天时间尺度的SPEI的相关性。结果表明:5种不同时间尺度的SPEI在内蒙古地区的年均值变化基本保持一致,但年变化趋势并不显著。年平均VCI呈极显著上升趋势,其变化倾向率达0.129/10 a,植被状况转好显著。内蒙古地区4月下旬—5月中旬,各植被覆盖类型对气象干旱的影响均不敏感。5月下旬开始草原VCI与SPEI呈显著或极显著正相关。6月中旬开始耕地VCI与SPEI呈显著相关或极显著正相关。VCI与不同时间尺度SPEI的相关性分析表明,宜分别采用SPEI60和SPEI90对内蒙古地区的草原和耕地干旱开展监测和预警,而森林和荒漠的VCI与SPEI的相关性整体偏差,气象干旱对其影响并不显著。

To understand the response of different vegetation types to meteorological drought indices at different time scales in Inner Mongolia,the authors calculated the correlation between VCI and the SPEI of 30,60,90,120 and 150 days time scale through using the monitoring data of 82 weather stations in Inner Mongolia and the MOD13Q1 vegetation monitoring products of NASA from 2000 to 2017.The results showed that the annual average variation of SPEI was basically the same in five different time scales,but annual variation trend was not obvious.The annual average VCI showed an extremely significant upward trend,its change tendency rate reached 0.129/10 a,and the vegetation condition was significantly improved.Different vegetation cover types were not sensitive to the effects of meteorological drought from late April to mid-May in Inner Mongolia.In late May,grassland VCI and SPEI showed significant or extremely significant positive correlation.In the middle of June,the cultivated land VCI was significantly or vey significantly positively correlated with SPEI.The study between VCI and SPEI at different time scales indicated that SPEI60 and SPEI90 should be used to monitor and predict the drought of grassland and cultivated land in Inner Mongolia,respectively,while the correlation between VCI and SPEI in forest and desert was declining,indicating that the impact of meteorological drought was not significant.