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The Applications Of MITgcm In Simulating Prydz Bay And Global Ocean Circulation

Posted on:2018-10-20Degree:MasterType:Thesis
Country:ChinaCandidate:Z L XieFull Text:PDF
GTID:2310330518498135Subject:Marine meteorology
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The third largest ice shelf around Antarctica, the Amery Ice shelf, is located in Prydz Bay. Limited by the harsh climate condition, hydrographic observations are always conducted in austral summer. The complicated ocean-sea ice-ice shelf system cannot be fully understood without data in wintertime.Thus, we carry out numerical experiments to simulate the ocean-sea ice-ice shelf interactions by using an eddy-resolving coupled regional ocean-sea ice-ice shelf model. The reanalysis date sets are used as atmospheric forcing in the regional model. However, the reliability of the reanalysis date sets in PrydzBay is not clear. Therefore, before conducting the model, we validate the reanalysis date sets against Antarctic station data in order to choose the best one for the simulation in Prydz Bay. In addition, we choose the same reanalysis date set to force the global ocean-sea ice model to investigate the response of the wind power input to the world ocean to major variability in atmospheric circulation.In order to choose a better reanalysis date set to force the regional model,we validate five reanalysis date sets against station data from British Antarctic Survey. Five reanalysis data sets include ERA-Interim, JRA-25, JRA-55,CFSR and MERRA. Stations we use include two manual stations, named Davis and Mawson, and three automatic weather stations, called AM02,AmeryG3, MtBrown. After analyzing the reliability of the reanalysis date sets,we apply the reanalysis date set to force the coupled regional model and the global ocean-sea ice model. Both models in this study are based on Massachusetts Institute of Technology General Circulation Model.Comparisons between observations and reanalysis date sets show large discrepancies between different data sets. The models used to produce the reanalysis date sets cannot simulate the strong flow in coastal region around Antarctica. JRA-25 performs better than other reanalysis date sets in Prydz Bay, and hence this dataset is used to force the models. The results of regional model show that the simulated sea ice, temperature and salinity are consistent with the satellite and hydrographic observations. The coupled regional model is also able to capture the intrusion of modified Circumpolar Deep Water onto the continental shelf, and find a new pathway called Prydz Bay Eastern Coastal Current. The simulation of the global generation current model shows the response of wind power input (WPI) to the variability in atmospheric condition is significant. The maximun WPI increases and its location shifts northward in the North Atlantic in the positive phase of North Atlantic Oscillation (NAO). The WPI to the Southern Ocean has increased with the increasing Westerlies in the recent decades. Similarly, the WPI to the Antarctic coastal current is increasing. The Empirical Orthogonal Function (EOF)analysis shows that the variability of WPI to the North Atlantic Ocean is dominated by the NAO. The Southern Annual Mode (SAM) leads to the first EOF mode in the Southern Ocean; the second and third modes are related with ENSO.
Keywords/Search Tags:reanalysis date sets, General Circulation Model, modified Circumpolar Deep Water, wind stress, wind power input to ocean
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