Regional Patterns of Sea Level Change Related to Interannual Variability and Multidecadal Trends in the Atlantic Meridional Overturning Circulation.

Lorbacher, Katja, Dengg, Joachim, Böning, Claus W. and Biastoch, Arne (2010) Regional Patterns of Sea Level Change Related to Interannual Variability and Multidecadal Trends in the Atlantic Meridional Overturning Circulation. Open Access Journal of Climate, 23 (15). pp. 4243-4254. DOI 10.1175/2010JCLI3341.1.

[img]
Preview
Text
2010JCLI3341.pdf - Published Version

Download (3514Kb)
[img]
Preview
Text
2010jcli3341.1.pdf - Accepted Version

Download (1119Kb)
[img]
Preview
Text
SupllMat.pdf - Supplemental Material

Download (234Kb)

Supplementary data:

Abstract

Some studies of ocean climate model experiments suggest that regional changes in dynamic sea level could provide a valuable indicator of trends in the strength of the Atlantic meridional overturning circulation (MOC). This paper describes the use of a sequence of global ocean–ice model experiments to show that the diagnosed patterns of sea surface height (SSH) anomalies associated with changes in the MOC in the North Atlantic (NA) depend critically on the time scales of interest. Model hindcast simulations for 1958–2004 reproduce the observed pattern of SSH variability with extrema occurring along the Gulf Stream (GS) and in the subpolar gyre (SPG), but they also show that the pattern is primarily related to the wind-driven variability of MOC and gyre circulation on interannual time scales; it is reflected also in the leading EOF of SSH variability over the NA Ocean, as described in previous studies. The pattern, however, is not useful as a “fingerprint” of longer-term changes in the MOC: as shown with a companion experiment, a multidecadal, gradual decline in the MOC [of 5 Sv (1 Sv ≡ 106 m3 s−1) over 5 decades] induces a much broader, basin-scale SSH rise over the mid-to-high-latitude NA, with amplitudes of 20 cm. The detectability of such a trend is low along the GS since low-frequency SSH changes are effectively masked here by strong variability on shorter time scales. More favorable signal-to-noise ratios are found in the SPG and the eastern NA, where a MOC trend of 0.1 Sv yr−1 would leave a significant imprint in SSH already after about 20 years.

Document Type: Article
Keywords: Oceanography; Gyres, Sea level, Meridional overturning circulation, Trends, Intraseasonal variability
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-TM Theory and Modeling
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-PO Physical Oceanography
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1175/2010JCLI3341.1
ISSN: 0894-8755
Projects: BMBF Nordatlantik
Expeditions/Models/Experiments:
Date Deposited: 07 Sep 2010 07:16
Last Modified: 24 Aug 2017 12:34
URI: http://oceanrep.geomar.de/id/eprint/8873

Actions (login required)

View Item View Item

Document Downloads

More statistics for this item...