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Upper stratospheric circulations in the two hemispheres observed by satellites
Author(s) -
Hirota I.,
Hirooka T.,
Shiotani M.
Publication year - 1983
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.49710946102
Subject(s) - stratosphere , stratopause , westerlies , atmospheric sciences , northern hemisphere , polar night , climatology , polar vortex , latitude , thermal wind , southern hemisphere , geology , polar , environmental science , mesosphere , wind speed , physics , wind shear , geodesy , oceanography , astronomy
A global analysis is made of upper stratospheric circulations with the aid of Nimbus 5 and Tiros N satellite observations in order to make a comparison of characteristics between the northern hemisphere (NH) and the southern hemisphere (SH). It is shown that the reversal of north‐south gradient of the zonal mean temperature at the stratopause level is always observed in higher latitudes of the SH winter, while the temperature gradient of the NH winter is variable because of the occurrence of sudden warmings. Consequently, due to the thermal wind relation, the polar night westerlies of the SH stratosphere are generally stronger than those of the NH stratosphere. In association with this difference, the activity of transient planetary waves of wavenumber 2 is striking in the SH, in contrast to the predominance of steady waves in the NH. Finally, the interrelation between the zonal mean field and planetary waves in the upper stratosphere is briefly discussed.