Identification

Title

Influence of the El Niño Southern Oscillation on the middle and upper atmosphere

Abstract

Based on Whole Atmosphere Community Climate Model (WACCM) simulations, Pedatella and Liu (2012) recently demonstrated that significant interannual variability occurs in migrating and nonmigrating tides in the mesosphere and lower thermosphere (MLT) due to the El Niño Southern Oscillation (ENSO). The role of changes in tropospheric forcing, changes in the zonal mean atmosphere, and planetary wave-tide interactions on generating the tidal variability in the MLT are investigated in the present study. The ENSO-driven variability in the migrating diurnal tide (DW1) is found to be primarily due to changes in the tropospheric forcing of the DW1. Changes in tropospheric forcing are also the source of the changes in the eastward propagating nonmigrating diurnal tide with zonal wave number 3 (DE3). However, changes in the zonal mean atmosphere also contribute to interannual variability of the DE3 due to the ENSO. Variability in the eastward propagating nonmigrating diurnal tide with zonal wave number 2 (DE2) is largely due to changes in the background atmosphere, with a smaller additional contribution due to changes in tropospheric forcing. Variability in the westward propagating semidiurnal tide with zonal wave number 4 (SW4) is believed to be due to changes in planetary waves during the ENSO which will enhance generation of the SW4 through the nonlinear interaction of the migrating semidiurnal tide and stationary planetary waves with zonal wave number 2. The influence of the interannual tidal variability on the longitude structure of the low-latitude ionosphere is also investigated in the present study. Comparison of El Niño and La Niña time periods reveals that the ENSO introduces changes of ~2–4 ms−1 in the daytime vertical drift velocity at certain longitudes. Simulation results further illustrate that the variability in the vertical drift velocity drives interannual variability in the low-latitude daytime F region maximum electron density (NmF2). The results demonstrate that the ENSO introduces variability of ~10–30% in the MLT and ~10–15% in the ionosphere. The ENSO should therefore be considered as a potentially significant source of variability in the Earth's upper atmosphere.

Resource type

document

Resource locator

Unique resource identifier

code

http://n2t.net/ark:/85065/d7c24x9z

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

2013-05-30T00:00:00Z

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Conformity

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name of format

version of format

Constraints related to access and use

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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