AVHRR/NDVI data of 8 km resolution and meteorological data were used to analyze NDVI
annual precipitation
and temperature change rates by pixel from 1981 to 2000.In addition
the correlation between NDVI
annual rainfall
and annual average air temperature were calculated.The results showed that annual precipitation increased in the northern and southern areas of the Hai Basin from 1981 to 2000 while declining in the central area
with a range of-80 to 80 mm/10 a(’a’ represents a year).As basin-wide temperatures increased
the Wutai Mountains area had the most significant increase
up to about 2℃/10 a.The NDVI reduced significantly in Beijing
Tianjin and other large adjacent cities
with a change rate of about-0.8 NDVI/10 a while increasing in the southeast part of the plains of the Hai Basin and the Yanshan Mountains
at about 0.8 NDVI/10 a.The correlation between NDVI
precipitation
and air temperature had significant spatial variation.In the cold and wet areas of the Hai Basin
such as the grasslands in the upstream areas of the Luanhe River and the area of the Wutai Mountains
the vegetation index is not sensitive to precipitation while it is correlated positively with the air temperature.In the warm and wet climate areas
such as the south end of the Taihang Mountains
the precipitation affected vegetation growth when it increased.In dry conditions
such as the eastern coastal plain and north of the Yanshan Mountains of the Hai Basin
NDVI significantly was correlated positively with precipitation and negatively with air temperature.In the irrigated agriculture areas of the piedmont plain