Response Differences of MODIS-NDVI and MODIS-EVI to Climate Factors

MODIS NDVI和MODIS EVI对气候的响应差异（英文）

To evaluate and provide an appropriate theoretical direction for research into climate-vegetation interactions using meteorological station data at different time scales,we examined differences between the Normalized Difference Vegetation Index (NDVI)and Enhanced Vegetation Index (EVI)and their responses to climate factors. We looked for correlations between'data extracted from MOD13Q1 remote sensing images and meteorological station data for the two indexes.The results showed that even though NDVI and EVI are derived from the same remote sensing image,their response to climate factors was significantly different.In the same meteorological station,the correlation coefficients for NDVI,EVI and climate factors were different;correlation coefficients between NDVI,EVI and climate factors varied with meteorological station.In addition,there was a lag effect for responses of NDVI to average minimum temperature,average temperature,average vapor pressure,minimum relative humidity, extreme wind speed,maximum wind speed,average wind speed and average station air-pressure.EVI had a lag only for average minimum temperature,average vapor pressure,extreme wind speed,maximum wind speed and average station air-pressure.The lag period was variable,but most were in the -3 period.Different vegetation types had different sensitivities to climate.The correlation between meteorological stations and vegetation requires more attention in future research.

旨在为正确认识气候-植被的相互关系提供科学的理论指导。基于MOD13Q1的植被指数(NDVI和EVI)及气象站数据(极端最低温度、极端最高温度、平均最高温度、平均最低温度、平均温度;平均蒸气压、最低相对湿度、平均相对湿度、最大每日降水量、降水量;极端风速,最大风速,平均风速,日照时数,平均站气压),对阿拉善左旗两种典型植被指数对气候因子的响应差异展开全面研究。结果表明:MOD13Q1 NDVI和MOD13Q1 EVI对气候响应存在显著差异。同一气象站中,NDVI和EVI与气候因子的相关系数显著不同。同时,NDVI和EVI与气候因子的相关系数随着气象站的不同而存在显著差异。此外,NDVI对平均最低气温、平均气温、平均蒸汽压、最低相对湿度、极端风速、最大风速、平均风速及平均本站气压存在时滞效应;而EVI仅对平均最低气温、平均蒸汽压、极端风速、最大风速及平均本站气压存在时滞效应。时滞期多数集中在3月份。因此,不同的植被类型对气候的敏感度不同,且利用气象站数据进行与植被的相关研究时首先应关注气象站与植被的相关性,方可进行下一步的深入研究。