A numerical experiment on the Influence of the Changjiang River Discharge on the Lower Trophic Ecosystem in the Yellow and the East China Seas

Abstract

Changjiang (Yangtze) river is the third-longest in the world and the longest river in Asia. Its discharging volume is controlled by the natural variability of the precipitation as well as the human interventions such as the Three Gorges Dam which was completed and fully functional in July, 2012. In this study, we compare three solutions of the lower trophic ecosystem responding to the Changjiang River Discharge (CRD) using the high-resolution coupled physico-biogeochemical ecosystem model based on POLCOMS-ERSEM. The model simulated with the half of annual mean CRD for 10 years (1992 - 2001) after the 3 year spin-up and the final year (2001) solution is diversified in three different cases in conjunction with CRD forcing as 1) the climatological monthly varying river discharge, 2) yearly steady discharge (no seasonal variation) with the half of annual mean climatological discharge rate as it was, and 3) no Changjiang river discharge at all.The most prominent differences among the solutions appear following the Changjinag Diluted Water (CDW) path centered in the northern border of the East China Sea adjacent to the Yellow Sea and its influences reach up to the East Sea (Sea of Japan). Three areas in the CDW path and two places out of the CDW path (one is in the central Yellow Sea and the other is in the southern East China Sea) are chosen and compared to investigate the influence of the CDW volume discharge on the lo which was completed and fully functional in July, 2012. In this study, we compare three solutions of the lower trophic ecosystem responding to the Changjiang River Discharge (CRD) using the high-resolution coupled physico-biogeochemical ecosystem model based on POLCOMS-ERSEM. The model simulated with the half of annual mean CRD for 10 years (1992 - 2001) after the 3 year spin-up and the final year (2001) solution is diversified in three different cases in conjunction with CRD forcing as 1) the climatological monthly varying river discharge, 2) yearly steady discharge (no seasonal variation) with the half of annual mean climatological discharge rate as it was, and 3) no Changjiang river discharge at all.The most prominent differences among the solutions appear following the Changjinag Diluted Water (CDW) path centered in the northern border of the East China Sea adjacent to the Yellow Sea and its influences reach up to the East Sea (Sea of Japan). Three areas in the CDW path and two places out of the CDW path (one is in the central Yellow Sea and the other is in the southern East China Sea) are chosen and compared to investigate the influence of the CDW volume discharge on the lo