A Study On The Numerical Simulation Of Water Temperature And Dissolved Oxygen In Taihu Driven By Meteorological Field

Water temperature and dissolved oxygen are two important parameters describing water quality in the aquatic ecosystem and of great significance ecologically to monitor and predict the bloom of cyanobacteriain Taihu.The current studies mostly discontinuously monitored water temperature and dissolved oxygen of the single station in Taihu, and even though the numerical studies on dissolved oxygen focused on the its2-D concentration field,3-D field and the influencing mechanism have not been studied in depth.This paper used meteorological data including wind direction and speed, air temperature, relative humidity, air pressure, rainfall and shortwave radiation from August16th to20th in2008and relevant parameters for water quality to drive FVCOM, which is an unstructured grid, finite-volume coastal ocean model developed by Chen et al. and simulated the spatial and temporal distribution of water temperature and dissolved oxygen in Taihu influenced by actual meteorological field. After the model validation, we analyzed the main influencing factors on water temperature and dissolved oxygen and finally discussed the contribution of the biochemical process including the "source" and "sinks" to the dissolved oxygen. The main conclusions are as follows:Firstly, the simulated results were fitted with the observed ones on the whole. The regression equation for water temperature was y=1.020x with the determination coefficient R2=0.690(n=480)and R2for dissolved oxygen is0.760, which meant that the developed model could simulate the water temperature and dissolved oxygen in Taihu.Secondly, we analyzed the simulated dissolved oxygen and discovered the vertical stratification of dissolved oxygen and that there existed "double peaks and double valleys" in Taihu. It might be caused by water temperature and light attenuation underwater.Thirdly, owing to the accumulation of algal in Meiliang Bay, we found that the photosynthesis of phytoplankton was the most important source of dissolved oxygen and the respiration and death of phytoplankton depleted the most dissolved oxygen.Finally, due to different water qualities, the contribution in different regions appears different results.