Identification

Title

On the structure and variability of the migrating diurnal temperature tide observed by SABER

Abstract

Temperature observations made by the SABER infrared radiometer from January 2002 through December 2021 are used to study the structure and variability of the migrating diurnal temperature tide in the middle atmosphere (-17-105 km). In the lower stratosphere, and in the mesosphere and lower thermosphere (MLT), tidal structure is domi-nated by the gravest latitudinally symmetric mode, with a smaller contribution from the first antisymmetric mode; in the middle and upper stratosphere, vertically nonpropagating modes are prominent. Consistent with previous work, low-frequency variability is mainly semiannual, with maxima at the equinoxes. Quasi-biennial variability is also present and evident in low-passed time series. There are robust relationships between the semiannual and quasi-biennial variability of the tide and the semiannual and quasi-biennial tropical zonal wind oscillations, respectively, which persist throughout the 20-yr dataset. While the physical mechanisms responsible for these relationships cannot be ascertained from the obser-vations, the present results should be useful for hypothesis testing with numerical models. It is also found that the diurnal tide breaks due to convective instability in the MLT. This is reflected in its mean vertical structure, which grows as expected for a nondissipating wave below-85 km, but ceases to grow at higher altitudes. Direct confirmation that dissipation is due to breaking is obtained from the potential temperature field, which shows frequent instances of reversed vertical gradient, particularly at the equinoxes. Breaking of the diurnal tide has a major impact on the zonal-mean temperature and zonal wind structure of the MLT at the equinoxes.

Resource type

document

Resource locator

Unique resource identifier

code

http://n2t.net/ark:/85065/d7cz3c37

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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Temporal reference

Temporal extent

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End position

Dataset reference date

date type

publication

effective date

2023-03-01T00:00:00Z

Frequency of update

Quality and validity

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Conformity

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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