Intermittency of gravity wave potential energies and absolute momentum fluxes derived from infrared limb sounding satellite observations
<p>Atmospheric gravity waves contribute significantly to the driving of the global atmospheric circulation. Because of their small spatial scales, their effect on the circulation is usually parameterized in general circulation models. These parameterizations, however, are strongly simplified....
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2022-11-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/22/15093/2022/acp-22-15093-2022.pdf |
| Summary: | <p>Atmospheric gravity waves contribute significantly to the driving of the
global atmospheric circulation.
Because of their small spatial scales, their effect on the circulation
is usually parameterized in general circulation models.
These parameterizations, however, are strongly simplified.
One important but often neglected
characteristic of the gravity wave distribution
is the fact that gravity wave
sources and, thus, the global distribution
of gravity waves are both very intermittent.
Therefore, time series of global observations of gravity waves
are needed to study the distribution, seasonal variation, and strength
of this effect.</p>
<p>For gravity wave
absolute momentum fluxes and potential energies observed by the
High-Resolution Dynamics Limb Sounder (HIRDLS)
and
Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) limb sounding
satellite instruments,
we investigate the global distribution of gravity wave intermittency
by deriving probability density functions (PDFs) in different regions
as well as global distributions of Gini coefficients.
In the stratosphere, we find that intermittency is strongest in
mountain wave regions, followed by the polar night jets
and by regions of deep convection in the summertime subtropics.
Intermittency is weakest in the tropics.
A better comparability of intermittency in different years
and regions is achieved
by normalizing observations by their spatially and temporally
varying monthly median distributions.
Our results are qualitatively in agreement with
previous findings from satellite observations and quantitatively
in good agreement with previous findings from
superpressure balloons and high-resolution models.
Generally, momentum fluxes exhibit stronger intermittency than
potential energies, and lognormal distributions are often a
reasonable approximation of the PDFs.
In the tropics, we find that, for monthly averages,
intermittency increases with altitude, which
might be a consequence of variations in the atmospheric background and, thus,
varying gravity wave propagation conditions.
Different from this,
in regions of stronger intermittency, particularly in mountain wave regions,
we find that intermittency decreases with altitude, which is
likely related to the dissipation of large-amplitude gravity waves
during their upward propagation.</p> |
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| ISSN: | 1680-7316 1680-7324 |