Sea surface temperature derived from NOAA/AVHRR and chlorophyll-a derived from MODIS and SeaWiFS as well as QuikSCAT wind vectors data during summer（from May to October） in 2004 have been used to investigate the short-term variability of upwelling events in Zhejiang coastal areas.Short-term observations of satellite images during summer of 2004 have revealed two upwelling zones in the study area.The upwelling near Zhejiang coastal areas is located at 29°—31°N

121.5°—123°E

with the upwelling core near 30°N

and the upwelling near Yangtze River estuary is located at 31°—32°N

122.5°—124°E

with the upwelling core near 31.5°N.These areas are noted for their high fisheries production.Upwelling looks like a long tongue in shape in Zhejiang coastal zones

the sea surface thermal front exists obviously in its southeastern edge.The temperature difference between the upwelling and non-upwelling areas is about 3—4℃ for July;the low temperature in the study area is about 24—27℃

with a mean value of 25℃;the size of upwelling is about 10000

1

6000 km2

with a mean value of 13690 km2.The seasonal variability is obvious in 2004

upwelling started to appear in June and achieved powerfully in July and August

it assumed the weaken ed tendency until vanished in September.Chlorophyll-a data of MODIS-derived and SeaWiFS-derived showed that high Chl-a areas coincided with low SST areas in terms of location

time and shape.The relationship between upwelling intensity and sea surface wind field is analyzed by using AVHRR SST and QuikSCAT wind field

the result shows that the variations of sea surface wind speed as well as wind direction coincide with the variations of upwelling

which indicates the southwest wind alongshore off Zhejiang coast is an important factor for the variations of upwelling.