Preprints
https://doi.org/10.5194/acpd-7-15873-2007
https://doi.org/10.5194/acpd-7-15873-2007
13 Nov 2007
 | 13 Nov 2007
Status: this preprint was under review for the journal ACP. A revision for further review has not been submitted.

Impact of upper-level jet-generated inertia-gravity waves on surface wind and precipitation

C. Zülicke and D. H. W. Peters

Abstract. A meteorological case study for the impact of inertia-gravity waves on surface meteorology is presented. The large-scale environment from 17 to 19 December 1999 was dominated by a poleward breaking Rossby wave transporting subtropical air over the North Atlantic Ocean upward and north-eastward. The synoptic situation was characterized with an upper tropospheric jet streak passing Northern Europe. The unbalanced jet spontaneously radiated inertia-gravity waves from its exit region. Near-inertial waves appeared with a horizontal wavelength of about 200 km and an apparent period of about 12 h. These waves transported energy downwards and interacted with large-scale convection.

This configuration is simulated with the nonhydrostatic Fifth-Generation Mesoscale Model. Together with simplified runs without orography and moisture it is demonstrated that the imbalance of the jet (detected with the cross-stream ageostrophic wind) and the deep convection (quantified with the latent heat release) are forcing inertia-gravity waves. This interaction is especially pronounced when the upper tropospheric jet is located above a cold front at the surface and supports deep frontal convection. Weak indication was found for triggering post-frontal convection by inertia-gravity waves.

The realism of model simulations was studied in an extended validation study for the Baltic Sea region. It included observations from radar (DWDPI, BALTRAD), satellite (GFZGPS), weather stations (DWDMI) and assimilated products (ELDAS, MESAN). The detected spatio-temporal patterns show wind pulsations and precipitation events at scales corresponding to those of inertia-gravity waves. In particular, the robust features of strong wind and enhanced precipitation near the front appeared with nearly the same amplitudes as in the model. In some datasets we found indication for periodic variations in the post-frontal region.

These findings demonstrate the impact of upper tropospheric jet-generated inertia-gravity waves on the dynamics of the boundary layer. It also gives confidence to models, observations and assimilation products for covering such processes. In an application for the Gotland Basin in the Baltic Sea, the implications of such mesoscale events on air-sea interaction and energy and water budgets are discussed.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
C. Zülicke and D. H. W. Peters
 
Status: closed (peer review stopped)
Status: closed (peer review stopped)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
 
Status: closed (peer review stopped)
Status: closed (peer review stopped)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
C. Zülicke and D. H. W. Peters
C. Zülicke and D. H. W. Peters

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