edu.ucar.opensky::articles:16513 UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact 2025-12-26T03:11:45.339724 ISO 19115-2 Geographic Information - Metadata - Part 2: Extensions for Imagery and Gridded Data ISO 19115-2:2009(E) https://n2t.org/ark:/85065/d7xg9s99 Variability of zonal mean tropical temperatures derived from a decade of GPS radio occultation data 2015-03-01T00:00:00Z publication https://n2t.org/ark:/85065/d7xg9s99 https://doi.org/10.1175/JAS-D-14-0216.1 Randel, William author Wu, Fei author UCAR/NCAR - Library publisher Variability in tropical zonal mean temperatures over 10-30 km is analyzed based on high-quality, high-vertical-resolution GPS temperature measurements covering 2001-13. The observations are used to quantify variability spanning time scales of weeks to over a decade, with focus on behavior of the tropopause region and coupling with the upper troposphere and stratosphere. Large variations associated with the seasonal cycle, quasi-biennial oscillation (QBO), and El Niño-Southern Oscillation (ENSO) are isolated and removed, and residual time series are analyzed using principal components and spectrum analysis. The residual temperature exhibits maximum variance in the lower stratosphere, with a vertical structure similar to the seasonal cycle. Residual temperatures exhibit two dominant modes of variability: a "deep stratosphere mode" tied to high-latitude planetary wave forcing and a shallow "near-tropopause mode" linked to dynamically forced upwelling near the tropopause. Variations in the cold point tropopause (and by inference in global stratospheric water vapor) are closely tied to the near-tropopause mode. These coherent temperature patterns provide further evidence of distinct upper and lower branches of the tropical Brewer-Dobson circulation. Zonal mean temperatures in the lower stratosphere and near the cold point are most strongly coupled to the upper troposphere on time scales of ~(30-60) days, probably linked to the Madden-Julian oscillation (MJO). Enhanced temperature variance near the tropopause is consistent with the long radiative relaxation time scales in the lower stratosphere, which makes this region especially sensitive to low-frequency dynamical forcing. 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 2015 American Meteorological Society (AMS). Permission to use figures, tables, and brief excerpts from this work in scientific and educational works is hereby granted provided that the source is acknowledged. Any use of material in this work that is determined to be "fair use" under Section 107 or that satisfies the conditions specified in Section 108 of the U.S. Copyright Law (17 USC, as revised by P.L. 94-553) does not require the Society's permission. Republication, systematic reproduction, posting in electronic form on servers, or other uses of this material, except as exempted by the above statements, requires written permission or license from the AMS. Additional details are provided in the AMS Copyright Policies, available from the AMS at 617-227-2425 or amspubs@ametsoc.org. Permission to place a copy of this work on this server has been provided by the AMS. The AMS does not guarantee that the copy provided here is an accurate copy of the published work. None eng geoscientificInformation