Cloud-base vertical velocity statistics: a comparison between an atmospheric mesoscale model and remote sensing observations

Tonttila, J., O'Connor, E. J., Niemelä, S., Räisänen, P. and Järvinen, H. (2011) Cloud-base vertical velocity statistics: a comparison between an atmospheric mesoscale model and remote sensing observations. Atmospheric Chemistry and Physics, 11 (17). pp. 9207-9218. ISSN 1680-7316 doi: 10.5194/acp-11-9207-2011

Abstract/Summary

The statistics of cloud-base vertical velocity simulated by the non-hydrostatic mesoscale model AROME are compared with Cloudnet remote sensing observations at two locations: the ARM SGP site in Central Oklahoma, and the DWD observatory at Lindenberg, Germany. The results show that, as expected, AROME significantly underestimates the variability of vertical velocity at cloud-base compared to observations at their nominal resolution; the standard deviation of vertical velocity in the model is typically 4-6 times smaller than observed, and even more during the winter at Lindenberg. Averaging the observations to the horizontal scale corresponding to the physical grid spacing of AROME (2.5 km) explains 70-80% of the underestimation by the model. Further averaging of the observations in the horizontal is required to match the model values for the standard deviation in vertical velocity. This indicates an effective horizontal resolution for the AROME model of at least 4 times the physically-defined grid spacing. The results illustrate the need for special treatment of sub-grid scale variability of vertical velocities in kilometer-scale atmospheric models, if processes such as aerosol-cloud interactions are to be included in the future.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/24185
Identification Number/DOI	10.5194/acp-11-9207-2011
Refereed	Yes
Divisions	Science > School of Mathematical, Physical and Computational Sciences > Department of Meteorology
Publisher	Copernicus Publications
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