HR: 0800h
AN: A31A-0019    [Abstracts]
TI: The Effect of Moisture and Ocean Heat Transport on the Hadley Circulation: Simulations with an Idealized GCM
AU: * Levine, X J
EM: xavier@caltech.edu
AF: California Institute of Technology, 1200 E. California Blvd, Pasadena, CA 91125, United States
AU: Schneider, T
EM: tapio@caltech.edu
AF: California Institute of Technology, 1200 E. California Blvd, Pasadena, CA 91125, United States
AB: In simulations of global change, the tropical Hadley circulation expands as the temperature increases. We investigate dynamical mechanisms responsible for the response of the Hadley circulation to climate changes. In simulations with an idealized dry GCM, in a climate resembling that of present-day Earth, the strength and extent of an equinox Hadley cell are controlled by eddy fluxes and baroclinic instability in the subtropics, leading to an expansion of a Hadley cell with increasing tropical static stability (Walker & Schneider 2006). We investigate the extent to which these results carry over to moist atmospheres with simulations with an idealized moist GCM coupled to an oceanic mixed layer. Varying the optical thickness of the longwave absorber, we study configurations with no ocean heat transport and with an idealized ocean heat transport coupled to the atmospheric wind stress. The Hadley circulation generally expands as the optical thickness increases. The response of the strength of the Hadley circulation is more complex and non-monotonic but can be rationalized by considering the zonal momentum balance of the mean meridional circulation and its interaction with eddies.
DE: 1223 Ocean/Earth/atmosphere/hydrosphere/cryosphere interactions (0762, 1218, 3319, 4550)
DE: 3309 Climatology (1616, 1620, 3305, 4215, 8408)
DE: 3314 Convective processes
DE: 3339 Ocean/atmosphere interactions (0312, 4504)
DE: 3367 Theoretical modeling
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting