On the mechanism of the cyclonic circulation in the Gulf of Tonkin in the summer
MetadataShow full item record
The circulation in the Gulf of Tonkin had been traditionally considered to be anticyclonic in the summer. This view was challenged recently by results from reanalyzing observational data, which clearly revealed that the circulation is cyclonic in all seasons. The surface wind stress is monsoonal, southwesterly in the summer and reversed in the winter. It remains unexplained why the circulation is always cyclonic, while the surface forcing reverses seasonally. In this study, we hypothesize that the inflow through Qiongzhou Strait, a shallow and narrow channel between Hainan Island and the Chinese mainland, is responsible for maintaining the cyclonic circulation in the summer. Besides the requirements of mass conservation and bathymetry constraint, this flow, even with a rather small transport, carries a considerable amount of potential vorticity (PV) into the gulf, and the integral constraint of PV requires the presence of a frictional torque to be associated with a cyclonic circulation. Several numerical experiments with a three-dimensional model have been conducted to test this hypothesis. When the westward flow through Qiongzhou Strait is blocked, the model simulates an anticyclonic circulation in the summer. When the westward flow through Qiongzhou Strait is allowed, the circulation changes to a cyclonic one, consistent with our hypothesis.
Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 113 (2008): C09029, doi:10.1029/2007JC004208.
Showing items related by title, author, creator and subject.
Pickart, Robert S. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1987-01)The various distributions of tracer associated with the Northern Recirculation Gyre of the Gulf Stream (NRG) are studied to try to obtain information about the flow. An advective-diffusive numerical model is implemented to ...
Liu, Ling Ling; Wang, Wei; Huang, Rui Xin (American Meteorological Society, 2008-06)Wind stress and tidal dissipation are the most important sources of mechanical energy for maintaining the oceanic general circulation. The contribution of mechanical energy due to tropical cyclones can be a vitally important ...
Tropical cyclones within the sedimentary record : analyzing overwash deposition from event to millennial timescales Woodruff, Jonathan D. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2009-02)Tropical cyclone activity over the last 5000 years is investigated using overwash sediments from coastal lagoons on the islands of Vieques, Puerto Rico and Koshikijima, Japan. A simple sediment transport model can reproduce ...