近20年藏北地区AVHRR NDVI与气候因子的关系

Relations between AVHRR NDVI and climate factors in Northern Tibet in recent 20 years

利用藏北那曲地区1981～2001年NOAA/ AVHRR的旬合成NDVI资料和6个站的逐日气象资料,分析了（归一化指数NDVI）的年内和年际变化规律以及NDVI与8个气候要素的相关关系,主要结论：影响NDVI年变化最显著的气候因子是温度,其中水汽压与NDVI的相关程度明显大于降水量;日照时数与NDVI呈负相关; NDVI与日照时数的滞后时间约0～10 d,与风速没有滞后现象,与潜在蒸散、温度、水汽压和降水约20～40 d;影响NDVI年际变化最显著的气候因子是潜在蒸散量.

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, factor affecting the interannual changes temperature, water vapour pressure and precipitation. The most important climate of NDVI was potential evapotranspiration.