Atmospheric Dynamics Triggered by an Oceanic SST Front in a Moist Quasigeostrophic Model

• Published in: Journal of the atmospheric sciences Vol. 69; no. 5; pp. 1617 - 1632
• Main Authors: DEREMBLE, Bruno, LAPEYRE, Guillaume, GHIL, Michael
• Format: Journal Article
• Language: English
• Published: Boston, MA American Meteorological Society 01.05.2012
• Subjects: Atmosphere; Atmospheric boundary layer; Atmospherics; Earth, ocean, space; Enthalpy; Exact sciences and technology; External geophysics; Flux; Focusing; General circulation models; Heat transfer; Latent heat; Latitude; Marine; Meteorology; Moisture effects; Ocean, Atmosphere; Physics of the high neutral atmosphere; Sciences of the Universe; Sea surface temperature; Sensible heat; Studies; sensible heat; High altitude; Mid latitude; Oceanic front; Sea surface temperature; trajectory; Heat liberation; Quasi geostrophic approximation; Sphere; Aquaplanet model; Atmospheric dynamics; Humidity effect; Spatial distribution; Jet (atmosphere, ocean); Jet stream; Triggering; heat transfer; storms; latent heat
• ISSN: 0022-4928; 1520-0469
• DOI: 10.1175/jas-d-11-0288.1

Abstract To understand the atmospheric response to a midlatitude oceanic front, this paper uses a quasigeostrophic (QG) model with moist processes. A well-known, three-level QG model on the sphere has been modified to include such processes in an aquaplanet setting. Its response is analyzed in terms of the upper-level atmospheric jet for sea surface temperature (SST) fronts of different profiles and located at different latitudes. When the SST front is sufficiently strong, it tends to anchor the mean atmospheric jet, suggesting that the jet’s spatial location and pattern are mainly affected by the latitude of the SST front. Changes in the jet’s pattern are studied, focusing on surface sensible heat flux and on moisture effects through latent heat release. It is found that latent heat release due to moist processes is modified when the SST front is changed, and this is responsible for the meridional displacement of the jet. Moreover, both latent heat release and surface sensible heat flux contribute to the jet’s strengthening. These results highlight the role of SST fronts and moist processes in affecting the characteristics of the midlatitude jet stream and of its associated storm track, particularly their positions.