Mean subsurface upwelling induced by intraseasonal variability over the equatorial Indian Ocean

Mean subsurface upwelling induced by intraseasonal variability over the equatorial Indian Ocean AbstractA possible formation mechanism of mean subsurface upwelling along the equator in the Indian Ocean is investigated using a series of hierarchical ocean general circulation model (OGCM) integrations and analytical considerations. In an eddy-resolving OGCM with realistic forcing, mean vertical velocity in the tropical Indian Ocean shows rather strong upwelling, with its maximum on the equator in the subsurface layer below the thermocline. Heat budget analysis exhibits that horizontal and vertical heat advection due to deviations of velocity and temperature from the mean balances with vertical advection caused by mean equatorial upwelling. Horizontal heat advection is mostly associated with intraseasonal variability with periods of 3-91 days, while contributions from longer periods (> 91 days) are small. Sensitivity experiments with a coarse-resolution OGCM further demonstrate that such mean equatorial upwelling cannot be reproduced by seasonal forcing only. Adding the intraseasonal wind forcing, especially meridional wind variability with a period of 15 days, generates significant mean subsurface upwelling on the equator. Further experiments with idealized settings confirm the importance of intraseasonal mixed Rossby-gravity (MRG) waves to generate mean upwelling, which appears along the energy “beam” of the MRG wave. An analytical solution of the MRG waves indicates that wave-induced temperature advection caused by the MRG waves with upward (downward) phase propagation results in warming (cooling) on the equator. This wave-induced warming (cooling) is shown to balance with the mean equatorial upwelling (downwelling), which is consistent with simulated characteristics in the OGCM experiments. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Physical Oceanography American Meteorological Society

Mean subsurface upwelling induced by intraseasonal variability over the equatorial Indian Ocean

Loading next page...
 
/lp/ams/mean-subsurface-upwelling-induced-by-intraseasonal-variability-over-Qc9ioctBo9
Publisher
American Meteorological Society
Copyright
Copyright © American Meteorological Society
ISSN
1520-0485
eISSN
1520-0485
D.O.I.
10.1175/JPO-D-16-0257.1
Publisher site
See Article on Publisher Site

Abstract

AbstractA possible formation mechanism of mean subsurface upwelling along the equator in the Indian Ocean is investigated using a series of hierarchical ocean general circulation model (OGCM) integrations and analytical considerations. In an eddy-resolving OGCM with realistic forcing, mean vertical velocity in the tropical Indian Ocean shows rather strong upwelling, with its maximum on the equator in the subsurface layer below the thermocline. Heat budget analysis exhibits that horizontal and vertical heat advection due to deviations of velocity and temperature from the mean balances with vertical advection caused by mean equatorial upwelling. Horizontal heat advection is mostly associated with intraseasonal variability with periods of 3-91 days, while contributions from longer periods (> 91 days) are small. Sensitivity experiments with a coarse-resolution OGCM further demonstrate that such mean equatorial upwelling cannot be reproduced by seasonal forcing only. Adding the intraseasonal wind forcing, especially meridional wind variability with a period of 15 days, generates significant mean subsurface upwelling on the equator. Further experiments with idealized settings confirm the importance of intraseasonal mixed Rossby-gravity (MRG) waves to generate mean upwelling, which appears along the energy “beam” of the MRG wave. An analytical solution of the MRG waves indicates that wave-induced temperature advection caused by the MRG waves with upward (downward) phase propagation results in warming (cooling) on the equator. This wave-induced warming (cooling) is shown to balance with the mean equatorial upwelling (downwelling), which is consistent with simulated characteristics in the OGCM experiments.

Journal

Journal of Physical OceanographyAmerican Meteorological Society

Published: Mar 24, 2017

There are no references for this article.

You’re reading a free preview. Subscribe to read the entire article.


DeepDyve is your
personal research library

It’s your single place to instantly
discover and read the research
that matters to you.

Enjoy affordable access to
over 12 million articles from more than
10,000 peer-reviewed journals.

All for just $49/month

Explore the DeepDyve Library

Unlimited reading

Read as many articles as you need. Full articles with original layout, charts and figures. Read online, from anywhere.

Stay up to date

Keep up with your field with Personalized Recommendations and Follow Journals to get automatic updates.

Organize your research

It’s easy to organize your research with our built-in tools.

Your journals are on DeepDyve

Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.

All the latest content is available, no embargo periods.

See the journals in your area

Monthly Plan

  • Read unlimited articles
  • Personalized recommendations
  • No expiration
  • Print 20 pages per month
  • 20% off on PDF purchases
  • Organize your research
  • Get updates on your journals and topic searches

$49/month

Start Free Trial

14-day Free Trial

Best Deal — 39% off

Annual Plan

  • All the features of the Professional Plan, but for 39% off!
  • Billed annually
  • No expiration
  • For the normal price of 10 articles elsewhere, you get one full year of unlimited access to articles.

$588

$360/year

billed annually
Start Free Trial

14-day Free Trial