Content - Temperature Changes

Atmospheric Temperature Changes and their Drivers (ATC)

Activity leaders

Amanda Maycock
University of Leeds, Leeds, UK

Andrea Steiner
Wegener Center for Climate and Global Change, Graz, Austria

William (Bill) Randel
NCAR, Boulder, USA

Team members

  • Valentina Aquila, Johns Hopkins University/NASA Goddard, Baltimore, USA (SPARC SSiRC contact)
  • Stefan Brönnimann, University of Bern, Switzerland
  • Chantal Claud, LMD, Ecole Polytechnique, CNRS, Palaiseau, France
  • Martin Dameris, Institute of Atmospheric Physics, DLR, Oberpfaffenhofen, Germany (SPARC CCMI contact)
  • Qiang Fu, Department of Atmospheric Sciences, University of Washington, Seattle, USA
  • Nathan Gillett, Canadian Center for Climate Modeling and Analysis, Victoria, BC, Canada
  • Leopold Haimberger, Institute for Meteorology and Geophysics, University of Vienna, Austria
  • Ben Ho, UCAR, COSMIC, Boulder, USA
  • Diane Ivy, Department of Atmospheric Sciences, MIT, Cambridge, USA
  • Philippe Keckhut, LATMOS, Université Pierre-et-Marie-Curie, Paris, France
  • Ulrike Langematz, Institute for Meteorology, Freie Universität Berlin, Germany (SPARC HEPPA/SOLARIS contact)
  • Thierry Leblanc, JPL, Pasadena, USA (GCOS GRUAN contact)
  • Craig Long, Climate Prediction Center NCEP, National Weather Service, NOAA, Camp Springs, USA (SPARC S-RIP contact)
  • Carl Mears, Remote Sensing Systems, Santa Rosa, USA
  • Karen Rosenlof, Chemical Sciences Division, NOAA ESRL, Boulder, CO, USA (SPARC WAVAS contact)
  • Ben Santer, PCMDI, Lawrence Livermore National Laboratory, Livermore, USA
  • Torsten Schmidt, Helmholtz Centre, German Research Centre for Geosciences, Potsdam, Germany
  • Michael Schwartz, JPL, Pasadena, USA
  • Viktoria Sofieva, Finnish Meteorological Institute, Helsinki, Finland
  • Dave Thompson, Colorado State University, Fort Collins, USA
  • Cheng-Zhi Zou, Center for Satellite Applications and Research, NOAA/NESDIS, Camp Springs, USA

Activity description

The focus of the Atmospheric Temperature Changes and their Drivers (ATC) activity is on characterising observed temperature changes and their uncertainties from different measurements, and on disentangling the drivers of past and future temperature changes in observations and global models. The ATC activity has evolved and broadened out from the work of the long-standing SPARC Stratospheric Temperature Trends activity. The science objectives of the new ATC activity align with the themes in SPARC's new Implementation Plan on 'Long-term Records for Climate Understanding', 'Chemistry and Climate', and 'Atmospheric Dynamics and Predictability'. Output from the group provides key information for UNEP/WMO Ozone Assessments and the Intergovernmental Panel on Climate Change (IPCC) Reports, as well as for other SPARC activities including CCMI and S-RIP.

Atmospheric temperature variability and trends, and their uncertainty in climate records

The IPCC AR5 states as a key uncertainty: "There is only medium to low confidence in the rate of change of tropospheric warming and its vertical structure.... There is low confidence in the rate and vertical structure of the stratospheric cooling". The aim of the ATC activity is to gain a better insight into atmospheric climate variability and trends from the troposphere to the mesosphere. This includes the evaluation of the inter-consistency of atmospheric temperature observations, comparison with (chemistry) climate models and reanalyses, and the provision of uncertainty information. Specific foci include: (1) extension of region of interest to the troposphere and the mesosphere; (2) inclusion of emerging novel observational records (such as radio occultation and Global Climate Observing System (GCOS) Reference Upper-Air Network (GRUAN) radiosondes); and (3) improving uncertainty information towards enhancing the maturity and benchmarking of climate records.

Radiative and dynamical contributions to observed and modelled temperature changes

Understanding the causes of temperature variations and trends requires knowledge of dynamical and radiative processes. Considerable effort has been placed in comparing model simulations of atmospheric temperatures to observations, but these studies have not attempted to assess the consistency between changes in temperature, composition (e.g. water vapour and ozone) and dynamics. The ATC activity is focused on assessing these contributions and their effect on observed and simulated atmospheric temperature trends. Specific foci include: (1) the contribution of greenhouse gases, ozone, and water vapour to temperature trends; (2) the role of natural variations (solar cycle, volcanoes, dynamical variability) in determining temperature variability; and (3) determining the drivers of temperature variability and trends on seasonal and regional scales.

Published results

Journal publications:

  • Ivy, D. J., S. Solomon, and H. E. Rieder, 2016: Radiative and dynamical influences on polar stratospheric temperature trends, J. Clim., doi:10.1175/JCLI-D-15-0503.1.
  • McLandress, C., T. G. Shepherd, A. I. Jonsson, T. von Clarmann, and B. Funke, 2015: A method for merging nadir-sounding climate records, with an application to the global-mean stratospheric temperature data sets from SSU and AMSU, Atmos. Chem. and Phys., 15, 9271-9284, doi:10.5194/acp-15-9271-2015.
  • Nash, J., and R. Saunders, 2015: A review of Stratospheric Sounding Unit radiance observations for climate trends and reanalyses, Q.J.R. Meteorol. Soc., 141, 2103-2113, doi:10.1002/qj.2505.
  • Randel, W. J., A. K. Smith, F. Wu, C.-Z. Zou and H. Qian, 2016: Stratospheric temperature trends over 1979-2015 derived from combined SSU, MLS and SABER satellite observations, J. Clim., doi:10.1175/JCLI-D-15-0629.1 (data available at
  • Seidel, D. J., J. Li, C. Mears, I. Moradi, J. Nash, W. J. Randel, R. Saunders, D. W. J. Thompson, and C.-Z. Zou, 2016: Stratospheric temperature changes during the satellite era, J. Geophys. Res. Atmos., 121, 2015JD024039, doi:10.1002/2015JD024039.
  • Zou, C.-Z., H. Qian, W. Wang, L. Wang, and C. Long, 2014: Recalibration and merging of SSU observations for stratospheric temperature trend studies. J. Geophys. Res. Atmos., 119, 180-13,205, doi:10.1002/2014JD021603.
  • Zou, C.-Z., and H. Qian, 2016: Stratospheric temperature climate data record from merged SSU and AMSU-A observations, J. Atmos. Oceanic Technol., submitted.

SPARC activity reports:

  • SPARC Newsletter No. 47 (2016), p. 36: Report on the 1st Atmospheric Temperature Changes and their Drivers (ARC) Activity Workshop, by Maycock A.C., A.K. Steiner, and B. Randel
  • SPARC Newsletter No. 45 (2015), p. 31: SPARC workshop on Stratospheric Temperature Trends, Randel, B., D. Seidel, and D. Thompson.

Website for further information

Presentations from the 1st ATC Workshop held in April 2016 are available on request.