GCM simulations of intraseasonal variability in the pacific/north american region. [GCM (general circulation model)]

Journal Article · Thu Jul 01 04:00:00 EDT 1993 · Journal of the Atmospheric Sciences; (United States)

DOI:https://doi.org/10.1175/1520-0469(1993)050<1991:GSOIVI>2.0.CO;2· OSTI ID:5977647

Schubert, S; Suarez, M ^[1]; Park, Chung-Kyu; Moorthi, S ^[2]

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1. Goddard Laboratory for Atmospheres, Greenbelt, MD (United States)
2. Universities Space Research Association, Greenbelt, MD (United States)

General circulation model (GCM) simulations of low-frequency variability with time scales of 20 to 70 days are analyzed for the Pacific sector during boreal winter. The GCM's leading mode in the upper-tropospheric zonal wind is associated with fluctuations of the East Asian jet; this mode resembles, in both structure and amplitude, the Pacific/North American (PNA) pattern found in the observation on these time scales. In both the model and observations the PNA anomaly is characterized by (1) a linear balance in the upper-tropospheric vorticity budget with no significant Rossby wave source in the tropics, (2) a barotropic conversion of kinetic energy from the time mean Pacific jet, and (3) a north/south displacement of the Pacific storm track. In the GCM, the latter is associated with synoptic eddy heat flux and latent heat anomalies that appear to contribute to a strong lower-tropospheric source of wave activity over the North Pacific. This is in contrast to the observations, which show only a weak source of wave activity in this region. The GCM produces 60% of the total observed Pacific sector low-frequency zonal wind variance. About one-third of the missing variability appears to be due to unrealistic simulations of the Madden-Julian oscillation; the remainder is characterized in the variance spectrum as a deficit in the overall level of [open quotes]background[close quotes] variability. 41 refs., 13 figs.

• OSTI ID: 5977647
• Journal Information: Journal of the Atmospheric Sciences; (United States), Journal Name: Journal of the Atmospheric Sciences; (United States) Vol. 50:13; ISSN 0022-4928; ISSN JAHSAK
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540110*
ATMOSPHERIC CIRCULATION
COMPUTERIZED SIMULATION
DEVELOPED COUNTRIES
ENERGY
GENERAL CIRCULATION MODELS
HEAT FLUX
KINETIC ENERGY
MATHEMATICAL MODELS
NORTH AMERICA
SEASONAL VARIATIONS
SIMULATION
USA
VARIATIONS
WIND