TY - JOUR
T1 - A Parameterization scheme of orographic gravity wave drag with two different vertical partitionings part II
T2 - Zonally averaged budget analyses based on transformed eulerian mean method
AU - Iwasaki, Toshiki
AU - Yamada, Shinichi
AU - Tada, Kazumasa
N1 - Funding Information:
The National Center for Atmospheric Research is sponsored by the National Science Foundation. Numerical calculations of both parts in this study were carried out at the Numerical Prediction Division of the Japan Meteorological Agency. The authors wish to express their sincere thanks to Drs. K. Ninomiya and T. Kitade and the staff members of the Numerical Prediction Division for their continuous encouragements. In particular, Mr. M. Kudo, Mr. K. Kurihara and Dr. H. Nakamura gave us useful suggestions on the characteristics of gravity waves. This report was completed while one of the authors (T. I.) visited the National Center of Atmospheric Research (NCAR) with partial support from the National Oceanic and Atmospheric Administration under NA85AAG02575. He had several stimulating discussions with the scientists of NCAR. He is very grateful to Dr. A. Kasahara for arranging the visit to NCAR, his critical reading and valuable comments on this manuscript. Comments and discussions with Profs. J. Wallace and J. Holton and Drs. N. McFarlane, B. A. Boville, M. D. Yamanaka and two anonymous reviewers are appreciated. We are pleased to acknowledge Miss R. Bailey for her skillful typesetting.
Publisher Copyright:
© 1989, Meteorological Society of Japan.
PY - 1989
Y1 - 1989
N2 - The effects of orographic gravity wave drag (GWD) on zonal-mean fields of medium-range forecasts are analyzed by means of the transformed Eulerian-mean (TEM) method. Results show that the geostrophic adjustment to GWD behaves very differently between the stratosphere and troposphere. In the troposphere, both the tropospheric and stratospheric GWDs significantly change Eliassen- Palm (EP) flux divergence due to large-scale (model-resolvable) waves. The change in the EP flux divergence is much larger than the net change of tonal wind and GWDs themselves and it is almost balanced with the change in the Coriolis acceleration term due to meridional flows. Among wave activities, transient gravity waves resolved in the model are considered to play important roles in the vertical redistribution of additional wave moments due to GWD. In the stratosphere, the stratospheric GWD induces a hemispheric single cell meridional circulation. The vertical motions in this cell cause significant temperature changes. The Coriolis acceleration due to GWD-induced meridional flows is almost balanced with the GWD itself. In contrast with the troposphere, EP flux divergence is less affected by GWD. From the view of Lagrangian-mean meridional circulation, diabatic heating in the tropics and wave, mean-flow interaction due to planetary-scale waves have been recognized mainly to drive a hemispheric single cell circulation (the so-called Brewer-Dobson circulation) in the lower-stratosphere. Our results indicate that the stratospheric GWD contributes to the maintenance of the single cell circulation as well. Especially in the midlatitudes of the northern hemisphere, the GWD can be regarded as an important forcing and considerably enhances lower-stratospheric downward motions in the polar side of the subtropical jet stream. It might affect significantly the transport of trace constituents in the stratosphere.
AB - The effects of orographic gravity wave drag (GWD) on zonal-mean fields of medium-range forecasts are analyzed by means of the transformed Eulerian-mean (TEM) method. Results show that the geostrophic adjustment to GWD behaves very differently between the stratosphere and troposphere. In the troposphere, both the tropospheric and stratospheric GWDs significantly change Eliassen- Palm (EP) flux divergence due to large-scale (model-resolvable) waves. The change in the EP flux divergence is much larger than the net change of tonal wind and GWDs themselves and it is almost balanced with the change in the Coriolis acceleration term due to meridional flows. Among wave activities, transient gravity waves resolved in the model are considered to play important roles in the vertical redistribution of additional wave moments due to GWD. In the stratosphere, the stratospheric GWD induces a hemispheric single cell meridional circulation. The vertical motions in this cell cause significant temperature changes. The Coriolis acceleration due to GWD-induced meridional flows is almost balanced with the GWD itself. In contrast with the troposphere, EP flux divergence is less affected by GWD. From the view of Lagrangian-mean meridional circulation, diabatic heating in the tropics and wave, mean-flow interaction due to planetary-scale waves have been recognized mainly to drive a hemispheric single cell circulation (the so-called Brewer-Dobson circulation) in the lower-stratosphere. Our results indicate that the stratospheric GWD contributes to the maintenance of the single cell circulation as well. Especially in the midlatitudes of the northern hemisphere, the GWD can be regarded as an important forcing and considerably enhances lower-stratospheric downward motions in the polar side of the subtropical jet stream. It might affect significantly the transport of trace constituents in the stratosphere.
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U2 - 10.2151/jmsj1965.67.1_29
DO - 10.2151/jmsj1965.67.1_29
M3 - Article
AN - SCOPUS:85043491481
VL - 67
SP - 29
EP - 41
JO - Journal of the Meteorological Society of Japan
JF - Journal of the Meteorological Society of Japan
SN - 0026-1165
IS - 1
ER -