基于Terra和NPP卫星的NDVI产品在呼伦贝尔地区植被监测中的对比

Comparison of Vegetation Monitoring in Hulun Buir Region Based on NDVI Products from Terra and NPP Satellites

为了探索基于多源卫星产品组建长时间序列NDVI并开展生态监测与灾害评估的可能性,利用相关系数、均方根误差、标准差和平均偏差等方法,结合泰勒图,对呼伦贝尔地区2012—2021年Terra和NPP卫星逐16 d的NDVI产品进行比较。结果表明:基于NPP的NDVI(简称“NDVI_(NPP)”)的多年平均值略高于基于Terra的NDVI(简称“NDVI_(Terra)”),两者在草原植被类型下的一致性最优,其次为耕地,森林植被的一致性较差。在呼伦贝尔非植被生长季,NDVI_(Terra)、NDVI_(NPP)的偏差主要集中在森林,且以NDVI_(Terra)偏高为主。在植被生长季初期2种NDVI产品的偏差呈现零散、随机分布,中期的偏差相对较小,生长季后期则以NDVI_(Terra)小于NDVI_(NPP)的负偏差为主。虽然2种卫星产品的总体偏差不大,但在开展NDVI的距平分析或计算VCI等指数时,较小的偏差会被放大。呼伦贝尔草地在考虑2种NDVI产品偏差纠正的前提下基本可替代使用,而耕地、森林植被的协同应用仍需谨慎。

In order to explore the possibility of constructing a long-term NDVI time series based on multi-source satellite products and conducting ecological monitoring and disaster assessment,this study compared the NDVI products based on Terra and NPP satellites every 16 days in the Hulun Buir region from 2012 to 2021 by using methods such as correlation coefficient,root mean square error,standard deviation,mean deviation,and combined with Taylor diagram.The results show that the multi-year mean of NDVI_(NPP) is slightly higher than that of NDVI_(Terra),and the consistency between the two is the best in grassland vegetation types,followed by cultivated land,while the consistency in forest vegetation is relatively poor.During the non-vegetation growth season in Hulun Buir,the deviation between NDVI_(Terra)and NDVI_(NPP)is mainly concentrated in forests,and the bias is mainly higher for NDVI_(Terra).At the beginning of the vegetation growth season,the deviation of the two NDVI products is scattered and randomly distributed,and the deviation in the middle stage is relatively small.In the later stage of the growth season,the negative deviation of NDVI_(Terra) less than NDVI_(NPP) is mainly dominant.Although the overall deviation of the two satellite products is small,the smaller deviation will be amplified when conducting NDVI anomaly analysis or calculating indices such as VCI.In the Hulun Buir grassland,the two NDVI products can be basically replaced under the premise of deviation correction,while the collaborative application of cultivated land and woodland vegetation still needs to be cautious.