First tomographic observations of gravity waves by the infrared limb imager GLORIA
Atmospheric gravity waves are a major cause of uncertainty in atmosphere general circulation models. This uncertainty affects regional climate projections and seasonal weather predictions. Improving the representation of gravity waves in general circulation models is therefore of primary interest...
| Main Authors: | , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-12-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/17/14937/2017/acp-17-14937-2017.pdf |
| Summary: | Atmospheric gravity waves are a major cause of uncertainty in atmosphere
general circulation models. This uncertainty affects regional climate
projections and seasonal weather predictions. Improving the representation of
gravity waves in general circulation models is therefore of primary interest.
In this regard, measurements providing an accurate 3-D characterization of
gravity waves are needed. Using the Gimballed Limb Observer for Radiance
Imaging of the Atmosphere (GLORIA), the first airborne implementation of a
novel infrared limb imaging technique, a gravity wave event over Iceland was
observed. An air volume disturbed by this gravity wave was investigated from
different angles by encircling the volume with a closed flight pattern. Using
a tomographic retrieval approach, the measurements of this air mass at
different angles allowed for a 3-D reconstruction of the temperature and
trace gas structure. The temperature measurements were used to derive gravity
wave amplitudes, 3-D wave vectors, and direction-resolved momentum fluxes.
These parameters facilitated the backtracing of the waves to their sources on
the southern coast of Iceland. Two wave packets are distinguished, one
stemming from the main mountain ridge in the south of Iceland and the other
from the smaller mountains in the north. The total area-integrated fluxes of
these two wave packets are determined. Forward ray tracing reveals that the
waves propagate laterally more than 2000 km away from their source
region. A comparison of a 3-D ray-tracing version to solely column-based
propagation showed that lateral propagation can help the waves to avoid
critical layers and propagate to higher altitudes. Thus, the implementation
of oblique gravity wave propagation into general circulation models may
improve their predictive skills. |
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| ISSN: | 1680-7316 1680-7324 |