Remotely forced intraseasonal oscillations over the tropical Atlantic

Journal Article · Fri Jan 01 00:00:00 EST 1993 · Journal of the Atmospheric Sciences; (United States)

DOI:https://doi.org/10.1175/1520-0469(1993)050<0089:RFIOOT>2.0.CO;2· OSTI ID:6702471

Park, C K; Schubert, S D ^[1]

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1. NASA/Goddard Space Flight Center, Greenbelt, MD (United States)

Intraseasonal (20-70 day) variability is examined in the Atlantic region during Northern Hemisphere winter using ECMWF analyses and NOAA outgoing longwave radiation (OLR). The dominant 200-mb zonal-wind fluctuation over the tropical Atlantic, A1, is related to global-scale circulation anomalies with their origins in the Pacific. Compositing techniques are used to investigate the nature of the Pacific-Atlantic teleconnections and related changes in the tropical OLR and moisture convergence. The OLR anomalies associated with A1 are characterized by eastward propagation over the Indian Ocean and the western Pacific and a standing oscillation over the tropical Atlantic. An analysis of the velocity potential and moisture convergence fields suggests that the fluctuations in convection are coupled between the western Pacific and Atlantic via large-scale (zonal wavenumber 1), equatorially trapped, eastward-propagating waves associated with the Madden-Julian oscillation. The zonal-wind fluctuation, A1, is also related to extratropical waves propagating into the tropics from both the Northern and Southern hemispheres. The Southern Hemispheric wave train appears to emanate from the western South Pacific and amplifies near the west coast of South America. The Northern Hemispheric wave train resembles the Pacific/North American pattern and emanates from the central North Pacific near the East Asian jet exit region. These results suggest that a major component of the 20-70-day variability over the Atlantic region is remotely forced. The forcing occurs via the Madden-Julian oscillation, which is strongly coupled with eastward-migrating heating anomalies in the western Pacific and Rossby wave trains, which appear to have their origins in the middle latitudes of the Pacific. The Northern Hemispheric wave train appears to be maintained by energy exchange with the East Asian jet, while the nature of the Southern Hemispheric branch is unclear. 33 refs., 10 figs.

• OSTI ID: 6702471
• Journal Information: Journal of the Atmospheric Sciences; (United States), Vol. 50:1; ISSN 0022-4928
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
ATLANTIC OCEAN
ATMOSPHERIC CIRCULATION
EXPERIMENTAL DATA
EVALUATION
WIND
OSCILLATIONS
AFRICA
BRAZIL
CONVECTION
GLOBAL ASPECTS
HEATING
INDIAN OCEAN
MOISTURE
NORTHERN HEMISPHERE
SEASONAL VARIATIONS
SOUTH AMERICA
TROPICAL REGIONS
US NOAA
WAVE PROPAGATION
DATA
DEVELOPING COUNTRIES
EARTH PLANET
ENERGY TRANSFER
HEAT TRANSFER
INFORMATION
LATIN AMERICA
MASS TRANSFER
NATIONAL ORGANIZATIONS
NUMERICAL DATA
PLANETS
SEAS
SURFACE WATERS
US ORGANIZATIONS
VARIATIONS
540110*