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| Titel |
Imaging gravity waves in lower stratospheric AMSU-A radiances, Part 2: Validation case study |
| VerfasserIn |
S. D. Eckermann, D. L. Wu, J. D. Doyle, J. F. Burris, T. J. McGee, C. A. Hostetler, L. Coy, B. N. Lawrence, A. Stephens, J. P. McCormack, T. F. Hogan |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 6, no. 11 ; Nr. 6, no. 11 (2006-08-14), S.3343-3362 |
| Datensatznummer |
250004058
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| Publikation (Nr.) |
 copernicus.org/acp-6-3343-2006.pdf |
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| Zusammenfassung |
| Two-dimensional radiance maps from Channel 9 (~60–90 hPa) of
the Advanced Microwave Sounding Unit (AMSU-A), acquired
over southern Scandinavia on 14 January 2003, show plane-wave-like
oscillations with a wavelength λh of ~400–500 km and
peak brightness temperature amplitudes of up to 0.9 K. The wave-like
pattern is observed in AMSU-A radiances from 8 overpasses of this
region by 4 different satellites, revealing a growth in the disturbance
amplitude from 00:00 UTC to 12:00 UTC and a
change in its horizontal structure between 12:00 UTC and 20:00 UTC.
Forecast and hindcast runs for 14 January 2003 using high-resolution
global and regional numerical weather prediction
(NWP) models generate a lower stratospheric mountain wave
over southern Scandinavia with peak 90 hPa temperature amplitudes of
~5–7 K at 12:00 UTC
and a similar horizontal wavelength, packet
width, phase structure and time evolution to the disturbance observed
in AMSU-A radiances. The wave's vertical wavelength is ~12 km.
These NWP fields are validated against radiosonde
wind and temperature profiles and airborne lidar
profiles of temperature and aerosol backscatter ratios acquired from
the NASA DC-8 during the second SAGE III Ozone
Loss and Validation Experiment (SOLVE II). Both the
amplitude and phase of the stratospheric
mountain wave in the various NWP
fields agree well with localized perturbation features in these
suborbital measurements. In particular, we show that this wave
formed the type II polar stratospheric clouds measured by the DC-8
lidar. To compare directly with the AMSU-A data,
we convert these validated NWP temperature fields
into swath-scanned brightness temperatures using three-dimensional
Channel 9 weighting functions and the actual AMSU-A scan patterns
from each of the 8 overpasses of this region.
These NWP-based brightness temperatures contain two-dimensional oscillations
due to this resolved stratospheric mountain wave that have an
amplitude, wavelength, horizontal structure and time evolution
that closely match those observed in the
AMSU-A data. These comparisons not only verify gravity wave detection and
horizontal imaging capabilities for AMSU-A Channel 9, but provide an
absolute validation of the anticipated radiance signals
for a given three-dimensional gravity wave, based on the
modeling of Eckermann and Wu (2006). |
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