Relationship between change of solar radiation and red tide in East China Sea in last 60 years

In order to analyze the relationship between solar radiation and red tide occurrences,the changes of downward solar radiation over East China Sea in last 60 years were analyzed by data from NCEP reanalysis data.The results showed that solar radiation flux over the north area of East China Sea(ECS) was about 198 W/m2 in average,but fluctuated with about 20-year cycles,and it was gradually increased about 11% with a rate around 0.5 W/m2·a from the late 1950s to date in general.Such increase trend,especially after 2000 year,was consistent with the frequency and area of red tides during the same period in ECS.It showed that the step-up of radiation may be one of the reasons for the rise of red tides occurrences in ECS.