Effects of increased isopycnal diffusivity mimicking the unresolved equatorial intermediate current system in an earth system climate model.

Getzlaff, Julia and Dietze, Heiner (2013) Effects of increased isopycnal diffusivity mimicking the unresolved equatorial intermediate current system in an earth system climate model. Open Access Geophysical Research Letters, 40 (10). pp. 2166-2170. DOI 10.1002/grl.50419.

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Abstract

Earth system climate models generally underestimate dissolved oxygen concentrations in the deep eastern equatorial Pacific. This problem is associated with the "nutrient trapping" problem, described by Najjar et al. [1992], and is, at least partially, caused by a deficient representation of the Equatorial Intermediate Current System (EICS). Here we emulate the unresolved EICS in the UVic earth system climate model by locally increasing the zonal isopycnal diffusivity. An anisotropic diffusivity of ∼50,000 m 2 s-1 yields an improved global representation of temperature, salinity and oxygen. In addition, it (1) resolves most of the local "nutrient trapping" and associated oxygen deficit in the eastern equatorial Pacific and (2) reduces spurious zonal temperature gradients on isopycnals without affecting other physical metrics such as meridional overturning or air-sea heat fluxes. Finally, climate projections of low-oxygenated waters and associated denitrification change sign and apparently become more plausible

Document Type: Article
Additional Information: WOS:000328840200050
Keywords: denitrification; earth system modeling; minimum zones; nutrient trapping; oxygenation; Pacific
Research affiliation: OceanRep > SFB 754 > A2
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-BM Biogeochemical Modeling
OceanRep > SFB 754
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1002/grl.50419
ISSN: 0094-8276
Related URLs:
Projects: SFB754
Date Deposited: 19 Jul 2013 10:55
Last Modified: 20 Jun 2017 06:58
URI: http://oceanrep.geomar.de/id/eprint/21624

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