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Quasi‐biennial and semi‐annual oscillations in equatorial wind fields constructed by data assimilation
Author(s) -
Swinbank Richard,
O'Neill Alan
Publication year - 1994
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/94gl01743
Subject(s) - stratopause , stratosphere , quasi biennial oscillation , troposphere , radiosonde , climatology , atmospheric sciences , wind shear , environmental science , data assimilation , amplitude , oscillation (cell signaling) , geology , meteorology , mesosphere , wind speed , physics , oceanography , quantum mechanics , biology , genetics
Since October 1991, the U.K. Meteorological Office has used the technique of data assimilation to produce global meteorological analyses of the troposphere and stratosphere. These analyses are constructed from conventional meteorological measurements in the troposphere and lower stratosphere, and temperature soundings from NOAA polar‐orbiting satellites. The analyses show very clear quasi‐biennial and semi‐annual oscillations in equatorial winds. The quasi‐biennial oscillation has its maximum amplitude of about 20 ms −1 near 30 hPa, and exhibits descending easterly and westerly shear zones. Analysed winds compare well with radiosonde observations in the lower stratosphere. The semi‐annual oscillation has its peak amplitude of about 30 ms −1 near the stratopause. Winds near the equatorial stratopause show strong longitudinal variations on a planetary scale during both the westerly and easterly phases of the semi‐annual oscillation.