Identification

Title

The lower thermosphere during the northern hemisphere winter of 2009: A modeling study using high-altitude data assimilation products in WACCM-X

Abstract

We present numerical simulations using the Whole Atmosphere Community Climate Model, extended version, constrained below 90km by a combination of NASA's Modern Era Retrospective Analysis for Research and Applications and the U.S. Navy's Operational Global Atmospheric Prediction System - Advanced Level Physics High Altitude assimilation products. The period examined is January and February 2009, when a large stratospheric warming occurred on 24 January 2009, with anomalous circulation persisting for several weeks after the event. In this study, we focus on the dynamical response of the lower thermosphere up to 200km. We find evidence of migrating and nonmigrating tides, Rossby and Rossby-gravity modes, and Kelvin waves, whose amplitudes appear to be modulated at the times leading and following the stratospheric warming. While the Rossby, Rossby-gravity, and Kelvin modes are rapidly dissipated in the lower thermosphere (above 110km), the tides maintain substantial amplitude throughout the thermosphere, but their vertical structure becomes external above about 120-150km. Most waves identified in the simulations decrease in amplitude in the thermosphere, indicating remote forcing from below and strong dissipation by molecular diffusion at high altitudes; however, the amplitude of the migrating DW1 tide increases in the thermosphere suggesting in situ forcing. We show that the amplitude of the tides (such as the DW1) changes as the background wind alters the vorticity in the tropics, which broadens or narrows the tropical waveguide. Our results also suggest that fast Rossby normal modes (periods ≤ 10 days) are excited by instability of the zonal-mean wind distribution following the stratospheric warming.

Resource type

document

Resource locator

Unique resource identifier

code

https://n2t.org/ark:/85065/d7v40w3c

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

2013-08-27T00:00:00Z

Frequency of update

Quality and validity

Lineage

Conformity

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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