edu.ucar.opensky::articles:21029 UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact 2025-12-26T02:26:36.278224 ISO 19115-2 Geographic Information - Metadata - Part 2: Extensions for Imagery and Gridded Data ISO 19115-2:2009(E) https://n2t.org/ark:/85065/d74t6mw1 The semiannual oscillation of the tropical zonal wind in the middle atmosphere derived from satellite geopotential height retrievals 2017-08-01T00:00:00Z publication https://n2t.org/ark:/85065/d74t6mw1 https://doi.org/10.1175/JAS-D-17-0067.1 Smith, Anne K. author García, Rolando R. author Moss, A. C. author Mitchell, N. J. author UCAR/NCAR - Library publisher The dominantmode of seasonal variability in the global tropical upper-stratosphere and mesosphere zonalwind is the semiannual oscillation (SAO). However, it is notoriously difficult to measure winds at these heights from satellite or ground-based remote sensing. Here, the balance wind relationship is used to derive monthly and zonally averaged zonal winds in the tropics from satellite retrievals of geopotential height. Data from the Aura Microwave Limb Sounder (MLS) cover about 12.5 yr, and those from the Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics (TIMED) Sounding of the Atmosphere Using Broadband Emission Radiometry (SABER) cover almost 15 yr. The derived winds agree with direct wind observations below 10 hPa and above 80 km; there are no directwind observations for validation in the intervening layers of the middle atmosphere. The derived winds show the following prominent peaks associated with the SAO: easterlymaxima near the solstices at 1.0 hPa, westerlymaxima near the equinoxes at 0.1 hPa, and easterlymaxima near the equinoxes at 0.01 hPa. The magnitudes of these three wind maxima are stronger during the first cycle (January at 1.0 hPa andMarch at 0.1 and 0.01 hPa). The month and pressure level of the wind maxima shift depending on the phase of the quasi-biennial oscillation (QBO) at 10 hPa. During easterly QBO, the westerly maxima are shifted upward, are about 10m s(-1) stronger, and occur approximately 1 month later than those during the westerly QBO phase. UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact PDF Text theme Resource Type 2016-01-01T00:00:00Z publication Copyright 2017 American Meteorological Society (AMS). None eng geoscientificInformation