Relations between AVHRR NDVI and climate factors in Northern Tibet in recent 20 years
近20年藏北地区AVHRR NDVI与气候因子的关系

Using NOAA/AVHRR 10-day composite NDVI data and daily meteorological data at six stations from 1981 to 2001,the annual and interannual variations of NDVI and the relations between NDVI and eight climate factors were analyzed.The main results showed that the most important climate factor affecting the annual variations of NDVI was temperature.The relation between NDVI and water vapour pressure was more marked than that between NDVI and precipitation and the relation between NDVI and sunshine duration was negative.The correspondence between NDVI and wind velocity was negative with no time lag.The correspondence between NDVI and sunshine duration had a marked lag between 0 and 10 days,while the time lags were in the range from 20 to 40 days between NDVI and other variables including potential evapotranspiration,temperature,water vapour pressure and precipitation.The most important climate factor affecting the interannual changes of NDVI was potential evapotranspiration.