Variation Of High Time And Density On Land—cover In ABa Prefecture From 2008—2013

Based on the MODIS data eight days in the synthesis of image data, and with the help of Arc GIS, ERDAS and ENVI software, adopt some techniques and methods in aba prefecture of sichuan province area of snow and green are carried on the detailed study of time and space change. Through this study, I created the aba prefecture between 2008 to 2013, six years’ time based on different scales of spatial and temporal variation of the snow and green area are covered. Including: based on the month of year snow and green covered area of space and time variation; Based on the area it covered in the season of snow and green are spatial and temporal variation; Based on years of snow and green covered area of space and time variation; Based on the minimum spatial and temporal variation of the snow and green area are covered; Based on the area it covered in the snow and green are the minimum and maximum space-time variation; Based on the snow and green are covered area under different terrain factors of time space distribution density. In addition, I also got snow in aba prefecture and green were the days of hierarchical graph. From making the figure, we can found in aba prefecture every year the change trend of the lid of the snow cover area is roughly same, basically to see every year in August is snow cover area is the smallest in a year, while the maximum snow cover area in basic appears in the January to march one month, but some years will the abnormal value because of the extreme weather conditions, such as 2009, November become snow cover area is the largest in the year. Aba year green covered area is about the same change trend, in the area it covered in the largest green was appeared in the July to September, one month minimum green covered area is often appear in January or February. In aba prefecture snow cover days grading, short days of snow cover area is the largest, more than 50%. At the age of snow cover area is very few, at 0.008%. Green are covered in ruoergai county days classification, number of vegetation cover in the area of the largest, is 40.097%. Aba no vegetation cover an area of minimum, at 3.202%.By comparing 2008 and 2013, snow and covered by the green area, you can see the aba in nearly six years of snow cover area is decreased by 22841.75 Km2, the area covered by green was increased by 1096 Km2. Aba prefecture from 2008 to 2008, the smallest of snow cover area in appear in August 2009, the largest snow cover area in appeared in November 2009, is the main cause of November 17, 2009, began to aba across ushered in a rare heavy snow weather, the snow is more than the average level. Minimum green is in the area it covered in April 2013, in the area it covered in the largest green was in August 2013.