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| Titel |
Evaluating WRF-Chem aerosol indirect effects in Southeast Pacific marine stratocumulus during VOCALS-REx |
| VerfasserIn |
P. E. Saide, S. N. Spak, G. R. Carmichael, M. A. Mena-Carrasco, Q. Yang, S. Howell, D. C. Leon, J. R. Snider, A. R. Bandy, J. L. Collett, K. B. Benedict, S. P. Szoeke, L. N. Hawkins, G. Allen, I. Crawford, J. Crosier, S. R. Springston |
| 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 ; 12, no. 6 ; Nr. 12, no. 6 (2012-03-29), S.3045-3064 |
| Datensatznummer |
250010950
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| Publikation (Nr.) |
 copernicus.org/acp-12-3045-2012.pdf |
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| Zusammenfassung |
| We evaluate a regional-scale simulation with the WRF-Chem model for the VAMOS (Variability of the
American Monsoon Systems) Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx),
which sampled the Southeast Pacific's persistent stratocumulus deck. Evaluation of VOCALS-REx
ship-based and three aircraft observations focuses on analyzing how aerosol loading affects marine
boundary layer (MBL) dynamics and cloud microphysics. We compare local time series and
campaign-averaged longitudinal gradients, and highlight differences in model simulations with (W)
and without (NW) wet deposition processes. The higher aerosol loadings in the NW case produce
considerable changes in MBL dynamics and cloud microphysics, in accordance with the established
conceptual model of aerosol indirect effects. These include increase in cloud albedo, increase in
MBL and cloud heights, drizzle suppression, increase in liquid water content, and increase in
cloud lifetime. Moreover, better statistical representation of aerosol mass and number
concentration improves model fidelity in reproducing observed spatial and temporal variability in
cloud properties, including top and base height, droplet concentration, water content, rain rate,
optical depth (COD) and liquid water path (LWP). Together, these help to quantify confidence in
WRF-Chem's modeled aerosol-cloud interactions, especially in the activation parameterization, while identifying structural and parametric
uncertainties including: irreversibility in rain wet removal; overestimation of marine DMS and sea
salt emissions, and accelerated aqueous sulfate conversion. Our findings suggest that WRF-Chem
simulates marine cloud-aerosol interactions at a level sufficient for applications in forecasting
weather and air quality and studying aerosol climate forcing, and may do so with the reliability
required for policy analysis. |
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