Simulations of the February 1979 stratospheric sudden warming: Model comparisons and three-dimensional evolution

Journal Article · Wed Jun 01 04:00:00 EDT 1994 · Monthly Weather Review; (United States)

DOI:https://doi.org/10.1175/1520-0493(1994)122<1115:SOTFSS>2.0.CO;2· OSTI ID:6532188

Manney, G L ^[1]; Farrara, J D; Mechoso, C R ^[2]

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1. California Institute of Technology, Pasadena, CA (United States)
2. Univ. of California, Los Angeles, CA (United States)

The evolution of the stratospheric flow during the major stratospheric sudden warming of February 1979 is studied using two primitive equation models of the stratosphere and mesosphere. The United Kingdom Meteorological Office Stratosphere-Mesosphere Model (SMM) uses log pressure as a vertical coordinate. A spectral, entropy coordinate version of the SMM (entropy coordinate model, or ECM) that has recently been developed is also used. The ECM produces a more realistic recombination and recovery of the polar vortex in the midstratosphere after the warming. Comparison of SMM simulations with forecasts performed using the University of California, Los Angeles general circulation model confirms the previously noted sensitivity of stratospheric forecasts to tropospheric forecast and emphasizes the importance of adequate vertical resolution in modeling the stratosphere. The ECM simulations provide a schematic description of the three-dimensional evolution of the polar vortex and the motion of air through it. During the warming, the two cyclonic vortices tilt westward and equatorward with height. Strong upward velocities develop in the lower stratosphere on the west (cold) side of a baroclinic zone as it forms over Europe and Asia. Strong downward velocities appear in the upper stratosphere on the east (warm) side, strengthening the temperature gradients. After the peak of the warming, vertical velocities decrease, downward velocities move into the lower stratosphere, and upward velocities move into the upper stratosphere. Transport calculations show that air with high ozone mixing ratios is advected toward the pole from low latitudes during the warming, and air with low ozone mixing ratios is transported to the midstratosphere from both higher and lower altitudes along the baroclinic zone in the polar regions. 32 refs., 23 figs., 1 tab.

• OSTI ID: 6532188
• Journal Information: Monthly Weather Review; (United States), Journal Name: Monthly Weather Review; (United States) Vol. 122:6; ISSN MWREAB; ISSN 0027-0644
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540110*
540140 -- Environment
Atmospheric-- Thermal Effluents Monitoring &amp; Transport-- (1990-)
99 GENERAL AND MISCELLANEOUS
990200 -- Mathematics &amp; Computers
ATMOSPHERIC CIRCULATION
CLIMATE MODELS
COMPARATIVE EVALUATIONS
CRYOSPHERE
EARTH ATMOSPHERE
ENVIRONMENTAL TRANSPORT
EVALUATION
MASS TRANSFER
MATHEMATICAL MODELS
MESOSPHERE
MIXING
OZONE
POLAR REGIONS
STRATOSPHERE
TEMPERATURE GRADIENTS
THERMODYNAMICS
TRAJECTORIES
VORTICES