HR: 17:00h
AN: SA32B-05    [PDF]
TI: Possible Role of the Mesosphere in the 2002 Southern Hemisphere Major Stratospheric Warming
AU: * Liu, H
EM: liuh@ucar.edu
AF: HAO/NCAR, POBox 3000, Boulder, CO 80307-3000 United States
AU: Roble, R G
EM: roble@ucar.edu
AF: HAO/NCAR, POBox 3000, Boulder, CO 80307-3000 United States
AB: The 2002 major stratospheric warming is an unprecedented event in the Southern Hemisphere and has been under intensive investigations since it was observed. These studies, however, have focused mainly on the dynamical and chemical processes in the troposphere and stratosphere. In this study, both the National Center for Environmental Predication (NCEP) data (below the 1 hPa level) and a NCAR thermosphere-ionosphere- mesosphere-electrodynamics general circulation model (TIME-GCM) simulation, with its lower boundary specified by the NCEP data at 10 hPa for 2002, are used to analyze this warming event and to explore the possible role of the mesosphere in the dynamical processes. Our analysis shows that significant changes in the wind and temperature fields first occur in the mesosphere due to a strong wave 1 event about a month before the major warming. Then a series of wave events (about 3 of them) in the following month erode the polar jet and alter the transmission conditions for planetary waves at progressively lower altitudes. This helps to set up the atmospheric conditions favorable for the upward and poleward propagation of the wave energy, not only for wave 1 but also for wave 2 and 3. At the same time, the jet reversal and the planetary wave surf zone also descend from the mesosphere down to the stratosphere. The preconditioning ultimately leads to an extensive breaking of the polar jet and wave 1 in the stratosphere and thus the major warming.
DE: 3319 General circulation
DE: 3332 Mesospheric dynamics
DE: 3334 Middle atmosphere dynamics (0341, 0342)
DE: 3337 Numerical modeling and data assimilation
DE: 3384 Waves and tides
SC: SPA - Aeronomy [SA]
MN: 2003 Fall Meeting