The Influence Of Wind Field To The Spatial Distribution Of Chlorophyll-a Concentration

Based on the concentrations of chlorophyll-a in Taihu Lake which were acquired from2005to2009, the seasonal characteristics and interannual variabilities of the chlorophyll-a are analyzed. Influence of other water quality parameters to the concentrations of chlorophyll-a is researched. According to the actual measurement and the value of simulation, the relationship between wind field and chlorophyll-a is built. Main conclusions are made as follows:1. The high-value centers of chlorophyll-a concentration are changed with seasons, but they centre on typical algae lake regions, and the low-value centers of chlorophyll-a concentration centre on typical macrophytae lake regions. The chlorophyll-a concentration is low from2005to2006, but it grows obviously from2007to2008, and it decreases in2009.2. The results of stepwise regression of chlorophyll-a and other environmental factors indicate that TP, TN and T are the most important factors to algae growth, but the spatial distributions of influencers are different. The whole situation of Taihu Lake performs eutrophic and excessive nutrient is not the reason to the difference of the spatial distributions of chlorophyll-a.3. The prevailing wind directions are northeast in February, southeast in May, east by south in August and north in November. The wind speeds are large in May and August, while they are small in February and November. Wuxi station is the representative station of Taihu Lake basin.4. The spatial distribution of the first mode obtained by EOF analysis of simulated wind indicates the wind distribution characteristics of spring and summer, that is southeast is the main direction of wind. The spatial distribution of the second mode reflects the change of wind between summer and winter.5. Alga drift with the directions of wind. Wind field plays an significant role in the transportion of chlorophyll-a when the wind is small, but the attractions are weak when the wind is weak or strong.6. The connection between wind field and chlorophyll-a is significant. The SVD-1of wind data and chlorophyll-a shows that the concentration of chlorophyll-a is higher in the northwest and north of Taihu Lake, which is induced by the action of wind field.