A Comparison between Gravity Wave Momentum Fluxes in Observations and Climate Models

Marvin A. Geller (1) , M. Joan Alexander (2) , Peter T. Love (1) , Julio Bacmeister (3) , Manfred Ern (4) , Albert Hertzog (5) , Elisa Manzini (6) , Peter Preusse (4) , Kaoru Sato (7) , Adam A. Scaife (8) , Tiehan Zhou (9)

1 SBU - Stony Brook University [SUNY]
2 CoRA - Colorado Research Associates [Boulder]
3 NCAR - National Center for Atmospheric Research [Boulder]
4 FZJ - Forschungszentrum Jülich GmbH | Centre de recherche de Jülich | Jülich Research Centre
5 LMD - Laboratoire de Météorologie Dynamique (UMR 8539)
6 MPI-M - Max Planck Institute for Meteorology
7 Department of Earth and Planetary Science [Tokyo]
8 MOHC - Met Office Hadley Centre
9 GISS - NASA Goddard Institute for Space Studies

For the first time, a formal comparison is made between gravity wave momentum fluxes in models and those derived from observations. Although gravity waves occur over a wide range of spatial and temporal scales, the focus of this paper is on scales that are being parameterized in present climate models, sub-1000-km scales. Only observational methods that permit derivation of gravity wave momentum fluxes over large geographical areas are discussed, and these are from satellite temperature measurements, constant-density long-duration balloons, and high-vertical-resolution radiosonde data. The models discussed include two high-resolution models in which gravity waves are explicitly modeled, Kanto and the Community Atmosphere Model, version 5 (CAM5), and three climate models containing gravity wave parameterizations, MAECHAM5, Hadley Centre Global Environmental Model 3 (HadGEM3), and the Goddard Institute for Space Studies (GISS) model. Measurements generally show similar flux magnitudes as in models, except that the fluxes derived from satellite measurements fall off more rapidly with height. This is likely due to limitations on the observable range of wavelengths, although other factors may contribute. When one accounts for this more rapid fall off, the geographical distribution of the fluxes from observations and models compare reasonably well, except for certain features that depend on the specification of the nonorographic gravity wave source functions in the climate models. For instance, both the observed fluxes and those in the high-resolution models are very small at summer high latitudes, but this is not the case for some of the climate models. This comparison between gravity wave fluxes from climate models, high-resolution models, and fluxes derived from observations indicates that such efforts offer a promising path toward improving specifications of gravity wave sources in climate models.

Domaines: Climatologie

Marvin A. Geller, M. Joan Alexander, Peter T. Love, Julio Bacmeister, Manfred Ern, et al.. A Comparison between Gravity Wave Momentum Fluxes in Observations and Climate Models. Journal of Climate, 2013, 26 (17), pp.6383-6405. ⟨10.1175/JCLI-D-12-00545.1⟩. ⟨hal-01109032⟩