Author: Andrea K. Steiner

Wegener Center for Climate and Global Change (WEGC), University of Graz, Graz, Austria

The aim of the WCRP/SPARC activity on Atmospheric Temperature Changes and their Drivers (ATC) is to improve knowledge on atmospheric climate variability and trends. This comprises the evaluation of atmospheric temperature observations from the troposphere to the mesosphere, their comparison with (chemistry) climate models and reanalyses, and the provision of uncertainty information. Over the last years, substantial efforts have led to improved data sets and emerging novel climate records. Satellite measurements have been reprocessed and/or merged and the presently available records provide layer-averaged temperatures from 1979 to present for the troposphere and stratosphere. Vertical profile information on atmospheric temperature is available from limb viewing satellite sounders, lidars, and radiosondes. For the latter, reference stations have been established within the Global Climate Observing System (GCOS) Reference Upper Air Network (GRUAN), adhering to the GCOS climate monitoring principles. Since 2001, also observations from GPS radio occultation provide temperature information with high vertical resolution. These are based on time measurements with precise atomic clocks, enabling a long-term stable climate record with high accuracy in the upper troposphere and lower stratosphere. A brief overview on the ATC activity is given. Highlights from current work are presented, updating our knowledge on observed atmospheric temperature changes. Results for layer-averaged temperatures and for vertically resolved atmospheric variability and trends are discussed.