## 摘要

Deep (∼2000 m) observations near the Sigsbee escarpment in the Gulf of Mexico show short-period (approximately 5-12 days) energetic currents due to topographic Rossby waves (TRW's). We suggest that the phenomenon is due to the focusing and accumulation of TRW energy by the slopes coupled with a bend in isobaths, in a topographic caustic (topocaustic). The idea draws on a simple mathematical equivalence between the propagation of internal waves and of TRW's. Topocaustics occur near regions of maximum N_{T} = N|∇h| (N = Brunt-Väisälä frequency; h = water depth). Because of the one-sided propagation property of TRW's, energy also tends to accumulate at the "western" end of closed contours of N_{T}. The process is demonstrated here using a nonlinear primitive-equation numerical model with idealized bathymetry and forcing. A Gulf of Mexico simulation initialized with a data-assimilated analysis covering the period of the Sigsbee observation is then conducted. The mooring is near a localized maximum N_{T}, and Intrinsic Mode Functions confirm the existence of energetic bursts of short-period deep-current events. The strong currents are locally forced from above, either by an extended Loop Current or a warm ring.

原文 | 英語 |
---|---|

頁（從 - 到） | 277-286 |

頁數 | 10 |

期刊 | Ocean Modelling |

卷 | 29 |

發行號 | 4 |

DOIs | |

出版狀態 | 已發佈 - 2009 |

## ASJC Scopus subject areas

- Computer Science (miscellaneous)
- Oceanography
- Geotechnical Engineering and Engineering Geology
- Atmospheric Science