Multi-source Remote Sensing Monitoring Of Lake Environmental Elements In The Qinghai-Tibet Plateau And Its Response To Climate Change

The Tibetan Plateau,with its complex formation mechanism,special geographical location,climatic characteristics and geological topography,has become the focus of global geoscience research.The Tibetan Plateau has many lakes and it is the highest,the largest number and largest area inland lake area on the earth.With remote sensing and GIS technology,the dynamic changes of the environmental factors and Hydrological factors of the Tibetan Plateau lake can be monitored,and the response of the factors to climate change can be further analysed.It is very significant to study the water cycle and energy cycle of the Tibetan Plateau and to maintain the sustainable development of the ecological environment of the Tibetan Plateau.Based on the data of multi-source remote sensing,the hydrological and environmental factors of the Tibetan Plateau lake are monitored.The hydrological factors include lake area,lake water level,lake ice phenology and environmental factors including NDVI,snow cover and albedo.Using the MOD09 surface reflectance product,the lake area was extracted by single-band threshold method.The water level was calculated by using T/P,Jason₁,Jason₂,ENVISAT and ICESat altimeter data according to the principle of satellite altimeter.Using MOD10 products,through the threshold method to extract the lake ice phenology and ice during.NDVI,snow cover and albedo were used to extract from MOD09 products,MOD10 products and GLASS surface shortwave albedo products respectively.According to different ecological geography zoning,analysis of characteristics of environmental and hydrological factors.Based on the analysis of the temporal and spatial characteristics of temperature,precipitation and evaporation of the Tibetan Plateau since1970,the response of the hydrological and environmental factors to climate change and the response characteristics to different ecological zones were analyzed.the conclusions are as follows:?1?From 2000 to 2015,the lake area of the Tibetan Plateau is expanding and the rate of change of each lake was from-3.92 km2/a to 14.82 km2/a,the lakes of the northern region is strongest expansion,and lakes which reduced area mainly concentrated in the southernregion.The lake level of the Tibetan Plateau is mostly above 4000 m,and the lake level of the lake is increasing.The change rate of lake level is between-1.480m/a and 1.038m/a.The lake which water level is reduced is mainly distributed in the southern region of Tibetan Plateau,trends of lake area and lake level are basically the same.?2?The freeze onset?FO?of lakes ice generally appears in early November to mid December,the freeze up?FU?of lakes ice appears in the middle of November to the early January of next years,the break onset?BO?of lakes ice appears in the middle of march to early may,the break up?BU?of lakes ice appears in the middle of April to early June.The mean ice duration?ID?are 176 days,the mean completely ice duration?CID?are around130 days.There are obvious regional differences in the lake ice phenology of the Tibetan Plateau,in the north lake district,the FO are the earliest,the BU are the latest,the ID of are the longest;in the south lakes district,the FO are the latest,the BU are the earliest,the ID are the shortest.ID change rate is between-4.28 d/a and 7.34 d/a,and the ID of lake in the northern district is changed greatly.?3?The snow cover from northwest to southeast gradually reduced in the Tibetan Plateau.The snow cover rate of the Tibetan Plateau decreased slightly from 2000 to 2015.The NDVI of the Tibetan Plateau is increasing from northwest to southeast.The NDVI of the Tibetan Plateau decreases from 2001 to 2010,with a change rate of-0.0003/a.The black-sky albedo of the Tibetan Plateau increased from southeast to northwest,and the albedo of the Tibetan Plateau changed from 2001 to 2010,and the rate of change was-0.0014/a.The albedo with snow cover and NDVI has a good correlation,the correlation coefficient is 0.737 and-0.806.?4?About Qinghai lake,Yamzhog Yumco and selinco,selinco area has the greatest response to temperature and precipitation,Yamzhog Yumco Secondly,Qinghai lake area has the least response to temperature and precipitation.The response of Yamzhog Yumco and selinco to the temperature is greater than that of the precipitation.The lake ice phenology is mainly affected by temperature,precipitation and wind speed.The temperature is the main influencing factor.?5?The snow cover,NDVI and albedo of the Tibetan Plateau have a good correlation with the regional temperature and precipitation.The snow cover is negatively correlatedwith the temperature,and positively correlated with the precipitation.NDVI was positively correlated with temperature,according to the precipitation,the correlation between NDVI and precipitation is different.The albedo was negatively correlated with temperature,and negatively correlated with precipitation.There are spatial differences in the correlation between snow cover,NDVI,albedo and temperature,precipitation.