Identification

Title

Why do modeled and observed surface wind stress climatologies differ in the trade wind regions?

Abstract

Global climate models (GCMs) exhibit stronger mean easterly zonal surface wind stress and near-surface winds in the Northern Hemisphere (NH) trade winds than observationally constrained reanalyses or other observational products. A comparison, between models and reanalyses, of the processes that contribute to the zonal-mean, vertically integrated balance of momentum reveals that this wind stress discrepancy cannot be explained by either the resolved dynamics or parameterized tendencies that are common to each. Rather, a substantial residual exists in the time-mean momentum balance of the reanalyses, pointing toward a role for the analysis increments. Indeed, they are found to systematically weaken the NH near-surface easterlies in winter, thereby reducing the diagnosed surface wind stress. Similar effects are found in the Southern Hemisphere, and further analysis of the spatial structure and seasonality of these increments demonstrates that they act to weaken the near-surface flow over much of the low-latitude oceans in both summer and winter. This suggests an erroneous/missing process in GCMs that constitutes a missing drag on the low-level zonal flow over oceans. This indicates either a misrepresentation of the drag between the surface and the atmosphere or a missing internal atmospheric process that amounts to an additional drag on the low-level zonal flow. If the former is true, then observation-based surface stress products, which rely on similar drag formulations to GCMs, may be underestimating the strength of the easterly surface wind stress.

Resource type

document

Resource locator

Unique resource identifier

code

http://n2t.net/ark:/85065/d7pr7znp

codeSpace

Dataset language

eng

Spatial reference system

code identifying the spatial reference system

Classification of spatial data and services

Topic category

geoscientificInformation

Keywords

Keyword set

keyword value

Text

originating controlled vocabulary

title

Resource Type

reference date

date type

publication

effective date

2016-01-01T00:00:00Z

Geographic location

West bounding longitude

East bounding longitude

North bounding latitude

South bounding latitude

Temporal reference

Temporal extent

Begin position

End position

Dataset reference date

date type

publication

effective date

2018-01-01T00:00:00Z

Frequency of update

Quality and validity

Lineage

Conformity

Data format

name of format

version of format

Constraints related to access and use

Constraint set

Use constraints

Limitations on public access

None

Responsible organisations

Responsible party

contact position

OpenSky Support

organisation name

UCAR/NCAR - Library

full postal address

PO Box 3000

Boulder

80307-3000

email address

opensky@ucar.edu

web address

http://opensky.ucar.edu/

name: homepage

responsible party role

pointOfContact

Metadata on metadata

Metadata point of contact