Typhoons’ Effects On Ocean Cyclonic Eddies In The North Western Pacific

Tropical cyclones (also known as hurricanes or typhoons) affecting ocean is part of the "typhoon-ocean" interaction study; ocean mesoscale eddies (including cyclonic ocean eddies and anticyclonic eddies) wide spread on Earth and have great contribution to mixing, mass transport, energy propagation and so on. So it is of great importance to focus on this area, typhoons’ effects on ocean cyclonic eddies. In this paper, sea surface temperature(SST), sea level anomaly (SLA), sea surface salinity (SSS), vertical temperature and salinity profiles derived from Argo floats and typhoon wind field model are used to investigate such effects.First, upper ocean response to Typhoon Prapiroon in2012is investigated. After this typhoon went through the area (126°E-133°E,17°N-25.5°N), SST decreased and SSS increased, so did the temperature and salinity in the mixed layer; and the lowest SLA in this specific region dropped from-20cm to-53cm accompanied with two cyclonic eddies merge. In the area, at the center of the typhoon, evaporation, turbulent mixing and upwelling played a dominant role to raise SSS versus precipitation, which lead to SSS decline. In addition, the temperature and salinity variations below the thermocline, could be explained as a result of Ekman pumping and upwelling in the cyclonic eddy, and then it is found that Ekman pumping played a major role in this case.Second,15super typhoons’ impacts on the cyclonic ocean eddy (COE) during the period of2001-2008are systematically taken into statistic in order to find a key factor. Only two COEs were induced by typhoons, so it is difficult and rare to induce a COE by a typhoon. Three possible factors of typhoon are employed to explain the interactions and we find forcing time (Tf) is the key factor. This is because Tf is a parameter combining both typhoon’s translation speed, intensity and size. Although typhoons may have significantly impact on COEs, such samples were not commonly observed. Thus, the impact of typhoon on COEs still need a lot of work.Last, with the model and data mentioned above, we calculate the energy input into ocean by typhoons. Through the analysis of work done by Prapiroon, we find that typhoons do not have positive effort on every point in a COE. Besides, the order of power input into sea flow, wave and in dissipation is10-1W/m2,100W/m2,101W/m2。 The pattern of energy input into wave is similar to that of energy dissipation. The energy is large where wind is strong. Dissipation energy is about10MJ/m2and the power surpasses50W/m2.In addition, large quantities of energy is input into deep sea at the area, where typhoons pass frequently; the energy could reach40KJ/m2.On the other hand, these regions are key areas for inputting energy into deep sea.