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A PV view of the zonal mean distribution of temperature and wind in the extratropical troposphereThe dependence of the temperature and wind distribution of the zonal mean flow in the extratropical troposphere on the gradient of pontential vorticity along isentropes is examined. The extratropics here refer to the region outside the Hadley circulation. Of particular interest is whether the distribution of temperature and wind corresponding to a constant potential vorticity (PV) along isentropes resembles the observed, and the implications of PV homogenization along isentropes for the role of the tropics. With the assumption that PV is homogenized along isentropes, it is found that the temperature distribution in the extratropical troposphere may be determined by a linear, first-order partial differential equation. When the observed surface temperature distribution and tropical lapse rate are used as the boundary conditions, the solution of the equation is close to the observed temperature distribution except in the upper troposphere adjacent to the Hadley circulation, where the troposphere with no PV gradient is considerably colder. Consequently, the jet is also stronger. It is also found that the meridional distribution of the balanced zonal wind is very sensitive to the meridional distribution of the tropopause temperature. The result may suggest that the requirement of the global momentum balance has no practical role in determining the extratropical temperature distribution. The authors further investigated the sensitivity of the extratropical troposphere with constant PV along isentropes to changes in conditions at the tropical boundary (the edge of the Hadley circulation). It is found that the temperature and wind distributions in the extratropical troposphere are sensitive to the vertical distribution of PV at the tropical boundary. With a surface distribution of temperature that decreases linearly with latitude, the jet maximum occurs at the tropical boundary and moves with it. The overall pattern of wind distribution is not sensitive to the change of the position of the tropical boundary. Finally, the temperature and wind distributions of an extratropical troposphere with a finite PV gradient are calculated. It is found that the larger the isentropic PV gradient, the warmer the troposphere and the weaker the jet.
Document ID
19950033279
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Sun, De-Zheng
(Princeton Univ. Princeton, NJ, United States)
Lindzen, Richard S.
(Massachusetts Inst. of Tech., Cambridge, MA United States)
Date Acquired
August 16, 2013
Publication Date
March 1, 1994
Publication Information
Publication: Journal of the Atmospheric Sciences
Volume: 51
Issue: 5
ISSN: 0022-4928
Subject Category
Meteorology And Climatology
Accession Number
95A64878
Funding Number(s)
CONTRACT_GRANT: NSF ATM-91-4441
CONTRACT_GRANT: NAGW-525
Distribution Limits
Public
Copyright
Other

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