Gravity wave drag and global angular momentum: geostrophic adjustment processes

Joseph Egger

doi:10.3402/tellusa.v55i5.12105

Gravity wave drag and global angular momentum: geostrophic adjustment processes

Tellus

Volume 55 (2003): Issue 5

By: Joseph Egger

Open Access

|Jan 2003

Abstract

Current gravity wave drag schemes alter the flow field of a numerical model by changing the velocity.It is argued that this is essentially the situation considered in the theory of geostrophic adjustment.The reduction of velocity at one moment does not necessarily lead to a reduction of the global meanvelocity after adjustment in that case. It is best to discuss these processes in terms of angular momentumconservation, so that the initial loss of velocity can be seen as a reduction of the wind term which maybe converted into a reduction of the mass term. Observations are used to see if this process can bedetected in the angular momentum budget of the atmosphere. The data indeed reveal a rapid positiveresponse of the mass term to the gravity wave drag.

References

Bell , M. 1994 . Oscillations in the equatorial components of the atmosphere’s angular momentum and torques on the earth’s bulge . Q. J. R. Meteorol. Soc . 120 , 195 – 213 .
Search in Google Scholar Back to article
Benoit , R. , Schär , C. , Binder , R , Chamberland , S. , Davies , H. C. and co-authors. 2002. The real-time ultrafine scale forecast support during the special observing period of the MAP. Bull. Am. Meteorol. Soc . 83 , 83 – 109 .
Search in Google Scholar Back to article
Blumen , W. 1972 . Geostrophic adjustment . Rev. Geophys. Sp. Phys . 10 , 485 – 528 .
Search in Google Scholar Back to article
Cahn , A. 1945 . An investigation of the free oscillations of a simple current system . J. Meteorol . 2 , 113 – 119 .
Search in Google Scholar Back to article
Durran , D. 1995 . Do breaking mountain waves decelerate the local mean flow? J. Atmos. Sci . 52 , 4010 – 4032 .
Search in Google Scholar Back to article
Egger , J . 2001 . Angular momentum of fl-plane flows . J. At-mos. Sci . 58 , 58 – 2508 .
Search in Google Scholar Back to article
Egger , J . and Hoinlca , K.-P. 2002 . Covariance analysis of the global atmospheric axial angular momentum budget . Mon. Wea. Rev . 130 , 130 – 1070 .
Search in Google Scholar Back to article
Gibson , R. , Milberg , P. , Uppala , S. , Hernandez , A. , Nomura , A. and Serrano , E. 1997 . ERA description. ERA Reanalysis Proj. Rep. Ser Vol. 1 , 68 pp . [ Available from ECMWF, Shinfield Park, Reading RGZ9AX, UK ].
Search in Google Scholar Back to article
Gregory , D. , Shuns , G. and Mitchell , J. 1998 . A new gravity-wave-drag scheme incorporating anisotropic orography and low-level wave breaking: impact upon the climate of the UK Meteorological Office Unified Model . Q. J. R. Meteorol. Soc . 124 , 124 – 493 .
Search in Google Scholar Back to article
Kim , Y.-J. and Arakawa , A. 1995 . Improvement of orographic gravity wave parameterization using a mesoscale gravity wave model . J. Atmos. Sci . 52 , 1875 – 1902 .
Search in Google Scholar Back to article
Klinker , E. and Sardeshmulch , P. 1992 . The diagnosis of mechanical dissipation in the atmosphere from large-scale balance requirements . J. Atmos. Sci . 49 , 49 – 627 .
Search in Google Scholar Back to article
Lindzen , R. 1981 . Turbulence and stress owing to gravity wave and tidal breakdown . J. Geophys. Res . 86 , 9707 – 9714 .
Search in Google Scholar Back to article
Lott , F. and Miller , M. 1997 . A new sub-grid-scale orographic drag parameterization: its formulation and testing . Q. J. R. Meteorol. Soc . 123 , 101 – 127 .
Search in Google Scholar Back to article
Miller , M. , Palmer , T. and Swinbank , R. 1989 . Parameteri-zation and influence of subgrid-scale orography in general circulation and numerical weather prediction models . Me-teorol. Atmos. Phys . 40 , 84 – 109 .
Search in Google Scholar Back to article
Palmer , T. Shuns , G. and Swinbanlc , R. 1986 . Allevation of a systematic westerly bias in general circulation and numerical weather prediction models through an orographic gravity wave parameterization. Q. J. R. Meteorol. Soc . 112 , 112 – 1039 .
Search in Google Scholar Back to article
Rossby , C.-G. 1937 . On the neutral adjustment of pressure and velocity distributions in certain simple current sys-tems. / . J. Marine. Res . 1 , 15 – 25 .
Search in Google Scholar Back to article
Rossby , C.-G. 1938 . On the neutral adjustment of pressure and velocity distributions in certain simple current sys-tems. 2. J. Marine. Res . 1 , 239 – 263 .
Search in Google Scholar Back to article
Scinocca , J. and McFarlane , A. 2000 . The parameterization of drag induced by stratified flow over anisotropic orography . Q. J. R. Meteorol. Soc . 126 , 2253 – 2293 .
Search in Google Scholar Back to article
von Storch , H. and Zwiers , F. 1999 . Statistical analysis in climate research . Cambridge University, Press , Cambridge . 484 pp.
Search in Google Scholar Back to article
Warner , C. and McIntyre , M. 2001 . An ultrasimple spectral parameterization of nonorographic gravity waves . J. At-mos. Sci . 58 , 1837 – 1857 .
Search in Google Scholar Back to article
Welch , W. , Smolarkiewicz , R , Rotunno , R. and Boville , B. 2001 . The large-scale effects of flow over periodic mesoscale topography . J. Atmos. Sci . 58 , 1477 – 1492 .
Search in Google Scholar Back to article