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GEOPHYSICAL RESEARCH LETTERS, VOL. 34, L16702, doi:10.1029/2007GL029875, 2007

Tropical vertical temperature trends: A real discrepancy?

P. W. Thorne

Hadley Centre, Met Office, Exeter, UK


D. E. Parker

Hadley Centre, Met Office, Exeter, UK


B. D. Santer

Program for Climate Model Diagnosis and Intercomparison, Lawrence Livermore National Laboratory, California, USA


M. P. McCarthy

Hadley Centre, Met Office, Exeter, UK


D. M. H. Sexton

Hadley Centre, Met Office, Exeter, UK


M. J. Webb

Hadley Centre, Met Office, Exeter, UK


J. M. Murphy

Hadley Centre, Met Office, Exeter, UK


M. Collins

Hadley Centre, Met Office, Exeter, UK


H. A. Titchner

Hadley Centre, Met Office, Exeter, UK


G. S. Jones

Hadley Centre, Met Office, Exeter, UK


Abstract

We examine the sensitivity of modeled and observed tropical tropospheric temperature trend amplification (the ratio of T2LT “lower troposphere” to surface changes) to several sources of uncertainty. Model behaviour is robust across a large perturbed physics ensemble of HadCM3, yielding a smaller amplification range (1.44 ± 0.06) than a previous multi-model ensemble (1.41 ± 0.24). The uncertainty of inter-satellite calibration implied by available MSU T2 (mid-troposphere) estimates (σ = 0.035K) is much greater than that required to adequately resolve the trend (σ < 0.01K), or the amplification behaviour (implied amplification range ±0.95). Trend amplification uncertainty in both models and observations decreases as the timescale increases. Depending upon choice of dataset and time period, uncertainty in trend amplification estimates over 21 years lies between ±1.5 and ±0.2.

Received 2 March 2007; accepted 19 July 2007; published 16 August 2007.

Keywords: tropics; temperatures; troposphere.

Index Terms: 0325 Atmospheric Composition and Structure: Evolution of the atmosphere (1610, 8125); 0350 Atmospheric Composition and Structure: Pressure, density, and temperature; 0365 Atmospheric Composition and Structure: Troposphere: composition and chemistry; 0394 Atmospheric Composition and Structure: Instruments and techniques.

Read Full Article (file size: 212364 bytes)    Cited by

Citation: Thorne, P. W., D. E. Parker, B. D. Santer, M. P. McCarthy, D. M. H. Sexton, M. J. Webb, J. M. Murphy, M. Collins, H. A. Titchner, and G. S. Jones (2007), Tropical vertical temperature trends: A real discrepancy?, Geophys. Res. Lett., 34, L16702, doi:10.1029/2007GL029875.