Influence Of The Tropical Cyclones’ Parameters To The Upper Ocean Response

The intensity, translation speed (TS) and the radius of maximum wind speed(RMWS) can influence the upper ocean response to tropical cyclones (TCs), studyingthe influence of them will not only do good to the forecast to the ocean status, but alsoimprove the accuracy of the forecast to the intensity and structure of TCs.When simulating the ocean response to TCs, choosing the right drag coefficient(Cd) is an important condition to ensure the accuracy of the result. The comparison ofthe upper ocean response to the hurricane Kartrina forced by different Cds indicatesthat in the area of high wind, the amplitude of sea surface temperature cooling (SSTC)and current in the experiments L_P, D and P decreases in order, and the decreasingpercentage increases with the wind speed increasing. By the comparing the simulatedSSTC with the satellite remote sensing data, we find that the result using Powell(2003)drag coefficient agrees the most with the observed data.Through the comparison of the upper ocean response caused by different TCs,we find that the amplitude and area of SSTC increases monotonically with the RMWSand intensity increasing and decreases with the translation speed increasing. The TSand RMWS can impact the spatial distribution of the SSTC, the area of the biggestSSTC generated by the TC with the smallest TS and RMWS is the nearest to thetrack.The fitting result of the SSTC to the three TCs’ parameters shows that theinfluence of the three TCs’ parameters is different: When TC movesslowly(TS≤4.5m/s), the SSTC is mainly controlled by the intensity and TS, when theTC moves fast(TS＞4.5m/s), the influence of the TC decreases and the SSTC ismainly controlled by the intensity, the influence of RMWS is always small comparedto the other two parameters. The mixing and upwelling caused by TCs can both decrease SST. Theamplitude of SSTC generated by mixing increases with the intensity and RMWSincreasing, and firstly increases then decreases with the TS increasing. The upwellingcaused by TCs can lift the cold water of deeper level in the ocean and change thestratification of the ocean, and then it can enhance the SSTC indirectly. Theproportion of the SSTC caused by upwelling is mainly controlled by the TS. For aslowly moving TC, the upwelling can lift much cold water from the thermocline tothe upper layer, so at this time even the mixing is relatively weak and the depth wherethe mixing happens is shallow, the amplitude of SSTC is still very big. However, for afast moving TC, the SSTC by upwelling is negligible.