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Wednesday, September 30, 2009

Steiner, Kirchengas, Lackner, Pirscher, Borsche, Foelsche, GRL 2009, Atmospheric temperature change detection with GPS radio occultation 1995-2008

Geophysical Research Letters, 36 (2009)  L18702; doi: 10.1029/2009GL039777.

Atmospheric temperature change detection with GPS radio occultation 1995 to 2008

A. K. Steiner, G. Kirchengas, B. C. Lackner, B. Pirscher, M. Borsche, and U. Foelsche (Wegener Center for Climate and Global Change and Institute for Geophysics, Astrophysics, and Meteorology, University of Graz, Graz, Austria)

Received 26 June 2009; accepted 26 August 2009; published 22 September 2009

Abstract

Existing upper air records of radiosonde and operational satellite data recently showed a reconciliation of temperature trends but structural uncertainties remain. GPS radio occultation (RO) provides a new high-quality record, profiling the upper troposphere and lower stratosphere with stability and homogeneity. Here we show that climate trends are since recently detected by RO data, consistent with earliest detection times estimated by simulations. Based on a temperature change detection study using the RO record within 1995–2008 we found a significant cooling trend in the tropical lower stratosphere in February while in the upper troposphere an emerging warming trend is obscured by El Niño variability. The observed trends and warming/cooling contrast across the tropopause agree well with radiosonde data and basically with climate model simulations, the latter tentatively showing less contrast. The performance of the short RO record to date underpins its capability to become a climate benchmark record in the future.

Steiner, A. K., G. Kirchengast, B. C. Lackner, B. Pirscher, M. Borsche & U. Foelsche (2009), Atmospheric temperature change detection with GPS radio occultation 1995 to 2008, Geophys. Res. Lett., 36, L18702; doi: 10.1029/2009GL039777.

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