Identification

Title

WACCM simulations of the mean circulation and trace species transport in the winter mesosphere

Abstract

Downwelling of air in the high latitude winter middle atmosphere causes perturbations in chemical composition. Species with sources in the mesosphere and lower thermosphere, such as nitric oxide and carbon monoxide, can be locally enhanced in the polar region. We investigate the origin of the downwelling air and the timescale for transport using the Whole Atmosphere Community Climate Model (WACCM). Analysis of the middle atmosphere transformed Eulerian mean (TEM) circulation, also called the residual circulation, is presented. This circulation gives the net air motion in the meridional and vertical directions due to the combined effects of the zonally averaged winds and the wave transport. The summer to winter circulation in the upper mesosphere during the solstice seasons includes strong upward motion at the summer pole and downward motion at the winter pole. During most winters, the air that is transported down by the circulation originates from low to middle latitudes in the upper mesosphere, 85-95 km; the timescale for this transport is 2-3 months. Trace species transport by molecular and eddy diffusion can bring high concentrations of thermospheric molecules into the winter mesosphere, where they are then brought to lower altitudes by the circulation. The magnitudes of the net tendencies due to advection by the TEM circulation and diffusion are similar. A case study of an active NH winter shows that the origin of the downwelling air in the TEM circulation is similar to that during average winters although the downwelling velocity is stronger by about a factor of two.

Resource type

document

Resource locator

Unique resource identifier

code

http://n2t.net/ark:/85065/d7hd7wc8

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

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South bounding latitude

Temporal reference

Temporal extent

Begin position

End position

Dataset reference date

date type

publication

effective date

2011-11-21T00:00:00Z

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