基于MODIS数据的额济纳植被物候对气候变化和调水的响应

Response of Vegetation Phenology in Ejina to Climate Change and Water Transfer Based on MODIS Data

基于2001—2021年的16 d合成Terra MODIS 250 m NDVI时间序列数据,利用Savitzky-Golay滤波法和动态阈值方法,提取、分析额济纳绿洲植被生长季开始日期(SOS)、结束日期(EOS)、生长季长度(LOS)及NDVI最大值(MAX)4种植被物候参数的时空变化,并通过2011—2013年的实地观测数据对提取的植被物候参数进行验证;同时,结合同期的温度、降水量、径流和地下水位埋深的观测数据,分析额济纳植被物候参数对气候变化和调水的响应关系。结果表明,SOS和EOS分别为第120~160天和第256~320天。近21年植被MAX有所增长,LOS延长趋势明显,变化趋势为4.65 d/10 a,植被SOS整体呈提前趋势,变化趋势为2.05 d/10 a, EOS整体上呈推迟趋势,变化趋势为2.60 d/10 a。物候参数与气候因子和调水的相关分析表明,气温的升高对SOS提前有促进作用,对EOS推迟有促进作用,径流和地下水位埋深对SOS和MAX起到促进作用,前一年的径流和地下水位埋深对MAX值增加和SOS提前有显著影响。

Based on the 16 days synthetic Terra MODIS 250 m NDVI time series data from 2001 to 2021,the Savitzky Golay filtering method and dynamic threshold method were used to extract and analyze the temporal and spatial changes of four vegetation phenological parameters in Ejina Oasis,including the start of growing season(SOS),the end of growing season(EOS),the length of growing season(LOS)and maximum value of NDVI,and the extracted vegetation phenological parameters were validated through field observation data from 2011 to 2013.At the same time,combined with observation data of temperature,precipitation,runoff and groundwater depth during the same period,the response relationship of vegetation phenological parameters to climate change and water diversion in Ejina was analyzed.The results showed that the SOS and the EOS were mainly occurred from the day of year(DOY)120-160 and DOY 256-320,respectively.In the past 21 years,the vegetation MAX had increased,and LOS had shown a significant trend of prolongation,with a trend of 4.65 d/10 a.The overall vegetation SOS showed an advanced trend,with a trend of 2.05 d/10 a.The overall EOS showed a delayed trend,with a trend of 2.60 d/10 a.The correlation analysis between phenological parameters,climate factors and water regulation showed that an increase in temperature had a promoting effect on the advance of SOS and a promoting effect on the delay of EOS.Runoff and groundwater burial depth had a promoting effect on SOS and MAX.The previous year’s runoff and groundwater burial depth had a significant impact on the increase of MAX value and the advance of SOS.