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Detailed Reference Information |
Hastenrath, S. (1998). Contribution to the circulation climatology of the eastern equatorial Pacific: Lower-atmospheric jets. Journal of Geophysical Research 103: doi: 10.1029/98JD02007. issn: 0148-0227. |
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Novel data sets have been evaluated to reappraise the annual cycle of atmospheric circulation over the Pacific. In the eastern Pacific, cross-equatorial surface winds from the southern hemisphere generate an oceanic cold tongue immediately to the south of the equator. The associated lower-tropospheric thickness pattern entails a minimum of absolute topography in the midtroposphere near the equator, and together with the small Coriolis parameter this causes a jet stream of up to 10 ms-1 at 700--600 mbar centered at 0¿--2 ¿N. The jet is most intense in late boreal winter because then the near-equatorial surface low-pressure trough is flat. The jet is fed by lower-tropospheric convergence over equatorial South America and by upper tropospheric convergence and subsidence over a narrow equatorial zone of the eastern Pacific. Over the central Pacific a jet of up to 10 ms-1 is found at 10¿--12 ¿N and 925--850 mbar, while friction brakes the flow in the layer of steepest meridional pressure gradient near the surface. This lower-tropospheric jet, as the surface pressure gradient, is also strongest in late boreal winter. Overall, the NCEP analyses resolve the near-surface circulation less well than the long-term ship observations. However, the midtropospheric equatorial jet over the eastern Pacific is also borne out by the 1967--1971 radiosoundings over Galapagos, and the lower-tropospheric trade wind jet over the central Pacific was also identified from the intense radiosonde program of the March--April 1967 Line Islands Experiment. ¿ 1998 American Geophysical Union |
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BACKGROUND DATA FILES |
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Abstract |
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Keywords
Meteorology and Atmospheric Dynamics, Meteorology and Atmospheric Dynamics, Climatology, Meteorology and Atmospheric Dynamics, General circulation, Meteorology and Atmospheric Dynamics, Tropical meteorology |
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Publisher
American Geophysical Union 2000 Florida Avenue N.W. Washington, D.C. 20009-1277 USA 1-202-462-6900 1-202-328-0566 service@agu.org |
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