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1、1998 20051998 2005间艾比湖面积动态监测间艾比湖面积动态监测间艾比湖面积动态监测间艾比湖面积动态监测 马明国We used multi-temporal VGT data during 1998 2005 to quantify the area of the Ebinur Lake.The first objective of this study is set up a methodology for identifying the water cover based on multi-spectral VGT data.The second objective is to
2、 obtain a continuous lake area change characteristic of the Ebinur Lake during 1998 2005.Objectives:Figure2.Variation of the area of Ebinur Lake in recent decades.(Wang et al.,2003)The Ebinur Lake Located in:8235-8310E 4454-4508Nand covers an area of approximately 1,000 km2It lies in the northwest o
3、f Xinjiang Province,west to Boertala valley,south to Jinghe proluvial fan,east to desrt-Gobi zone of the down part in Kuitun River.The Alatawshankou,lied to the northwest of Ebinur Lake,is the famous wind gap and its maximum wind speed can reach 55 m/s.There are approximately average annual 164 d wi
4、th strong wind at level 8 or above in a year.The average annual precipitation is only 95 mm and the average annual evaporation is as high as 1,315 mm.The mineralization degree of lake water is between 85 g/l and 124 g/l because of the continuously strong concentrate 研究区研究区Study area VEGETATION(VGT)数
5、据数据blue band(B0,430-470nm),red band(B2,610-680nm),near infrared band(B3,780-890nm)short-wave infrared band(SWIR,1580-1750 nm).The VGT products are pre-processed by the VGT image pre-processing Centre(CTIV)at the Flemish Institute for Technological Research(Vito).Data pre-processing includes navigati
6、on and geo-correction,calibration and atmospheric correction for water vapor,ozone and aerosol Multi-temporal VGT-S10(10-day synthesis product)radiometric data for April 1,1998 to December 31,2005 were downloaded from the free VGT products website(http:/free.vgt.vito.be).VGT-S10 was selected through
7、 a classical Maximum Value Composite(MVC)criterion from daily data.For each month there are three 10-day composites:day 110,day 1120 and day 21 to the last day of a month.The 10-day composite dataset includes the above-mentioned four spectral bands in 16-bit Digital Number(DN)values,and a status map
8、 file that contains information about cloud pixels.用于识别湖泊的指数用于识别湖泊的指数典型水体光谱特征用于识别湖泊的指数用于识别湖泊的指数用于识别湖泊的指数用于识别湖泊的指数基于VGT数据的NDVI和NDWI特征空分布验证数据影像特征验证数据影像特征验证数据验证数据利用利用ETM+数据和中巴卫星数据验证数据和中巴卫星数据验证VGT提取的湖泊面积提取的湖泊面积精度验证精度验证基于VGT数据的艾比湖 1998 2005 年湖泊面积变化艾比湖面积年内和年际变化特征艾比湖面积年内和年际变化特征讨论讨论1、水体提取没有考虑亚像元问题，也没有考虑水体中植被等、水体提取没有考虑亚像元问题，也没有考虑水体中植被等混合信息的问题，有待进一步开展工作。混合信息的问题，有待进一步开展工作。2、对引起艾比湖面积变化的驱动力进行深入分析。、对引起艾比湖面积变化的驱动力进行深入分析。