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| Titel |
A regional real-time forecast of marine boundary layers during VOCALS-REx |
| VerfasserIn |
S. Wang, L. W. O'Neill, Q. Jiang, S. P. Szoeke, X. Hong, H. Jin, W. T. Thompson, X. Zheng |
| 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 ; 11, no. 2 ; Nr. 11, no. 2 (2011-01-17), S.421-437 |
| Datensatznummer |
250009174
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| Publikation (Nr.) |
 copernicus.org/acp-11-421-2011.pdf |
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| Zusammenfassung |
| This paper presents an evaluation and validation of the Naval Research
Laboratory's COAMPS® real-time forecasts during the VOCALS-REx over the area
off the west coast of Chile/Peru in the Southeast Pacific during October and
November 2008. The analyses focus on the marine boundary layer (MBL)
structure. These forecasts are compared with lower troposphere soundings, in
situ surface measurements, and satellite observations. The predicted mean
MBL cloud and surface wind spatial distributions are in good agreement with
the satellite observations. The large-scale longitudinal variation of the
MBL structure along 20° S is captured by the forecasts. That is, the
MBL height increases westward toward the open ocean, the moisture just above
the inversion decreases, and the MBL structure becomes more decoupled
offshore. The observed strong wind shear across the cloud-top inversion near
20° S was correctly predicted by the model. The model's cloud spatial
and temporal distribution in the 15 km grid mesh is sporadic compared to
satellite observations. Our results suggest that this is caused by
grid-scale convection likely due to a lack of a shallow cumulus convection
parameterization in the model. Both observations and model forecasts show
wind speed maxima near the top of MBL along 20° S, which is consistent
with the westward upslope of the MBL heights based on the thermal wind
relationship. The forecasts produced well-defined diurnal variations in the
spatially-averaged MBL structure, although the overall signal is weaker than
those derived from the in situ measurements and satellite data. The MBL heights are
generally underpredicted in the nearshore area. An analysis of the
sensitivity of the MBL height to horizontal and vertical grid resolution
suggests that the underprediction is likely associated with overprediction
of the mesoscale downward motion and cold advection near the coast. |
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