skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Equatorial variability and resonance in a wind-driven Indian Ocean model

Abstract

A numerical isopycnal ocean model has been designed and applied to model the Indian Ocean north of 25{degrees}S. Vertical normal modes are used in the open boundary conditions and for selections of initial layer depths. A 21-year integration with a reduced Hellerman-Rosenstein monthly averaged wind stress has been made with 3.5-layer and 1.5-layer versions of the model. Both solutions reproduce the main features of the observed wind-driven seasonal circulation in the Indian Ocean above the main thermocline. The transient semiannual equatorial surface jets are more intense, more coherent, and in better phase agreement with observations when three layers are active. The associated undercurrents below the main thermocline are also included in the 3.5-layer model solution. Second baroclinic-mode, reflecting, equatorial Kelvin and Rossby waves combine to give a semiannual, resonant basin mode. Experiments with an equatorial band of semiannual zonal winds suggest a very strong response of the Indian Ocean to wind forcing with this period. Further, the amplitudes of the 28-30 day oscillations in the western equatorial model region are found to be strongly damped with depth; they have upward phase propagation and downward energy propagation. 43 refs., 22 figs., 2 tabs.

Authors:
 [1]
  1. Colorado State Univ., Fort Collins, CO (United States)
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
81661
DOE Contract Number:  
FG02-89ER69027; FG02-92ER61440
Resource Type:
Journal Article
Journal Name:
Journal of Geophysical Research
Additional Journal Information:
Journal Volume: 98; Journal Issue: C12; Other Information: PBD: 15 Dec 1993
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; INDIAN OCEAN; OCEANIC CIRCULATION; NUMERICAL ANALYSIS; WATER CURRENTS; WIND; RESONANCE

Citation Formats

Jensen, T G. Equatorial variability and resonance in a wind-driven Indian Ocean model. United States: N. p., 1993. Web. doi:10.1029/93JC02565.
Jensen, T G. Equatorial variability and resonance in a wind-driven Indian Ocean model. United States. doi:10.1029/93JC02565.
Jensen, T G. Wed . "Equatorial variability and resonance in a wind-driven Indian Ocean model". United States. doi:10.1029/93JC02565.
@article{osti_81661,
title = {Equatorial variability and resonance in a wind-driven Indian Ocean model},
author = {Jensen, T G},
abstractNote = {A numerical isopycnal ocean model has been designed and applied to model the Indian Ocean north of 25{degrees}S. Vertical normal modes are used in the open boundary conditions and for selections of initial layer depths. A 21-year integration with a reduced Hellerman-Rosenstein monthly averaged wind stress has been made with 3.5-layer and 1.5-layer versions of the model. Both solutions reproduce the main features of the observed wind-driven seasonal circulation in the Indian Ocean above the main thermocline. The transient semiannual equatorial surface jets are more intense, more coherent, and in better phase agreement with observations when three layers are active. The associated undercurrents below the main thermocline are also included in the 3.5-layer model solution. Second baroclinic-mode, reflecting, equatorial Kelvin and Rossby waves combine to give a semiannual, resonant basin mode. Experiments with an equatorial band of semiannual zonal winds suggest a very strong response of the Indian Ocean to wind forcing with this period. Further, the amplitudes of the 28-30 day oscillations in the western equatorial model region are found to be strongly damped with depth; they have upward phase propagation and downward energy propagation. 43 refs., 22 figs., 2 tabs.},
doi = {10.1029/93JC02565},
journal = {Journal of Geophysical Research},
number = C12,
volume = 98,
place = {United States},
year = {1993},
month = {12}
}