Temperature Trends in the Lower Atmosphere: Steps for Understanding and Reconciling Differences

1. Overview: Description of Topic, Audience, Intended Use, and Questions to Be Addressed

Independently produced data sets that describe the four-dimensional temperature structure from the surface through the lower stratosphere provide different temperature trends. These differences are seen in varying degrees in comparisons of separate in situ (surface and weather balloon) data sets, in comparisons of separate space-based data sets, and in comparisons of individual data sets drawn from the different observational platforms and different trend analysis teams.

This CCSP synthesis and assessment product will address the accuracy and consistency of these temperature records and outline steps necessary to reconcile differences between individual data sets. Understanding exactly how and why there are differences in temperature trends reported by several analysis teams using differing observation systems and analysis methods represents a necessary step in reducing the uncertainties that underlie current efforts focused on the detection and quantification of surface and tropospheric temperature trends. Consequently, this synthesis and assessment product promises to be of significant value to decisionmakers, and to the expert scientific and stakeholder communities. For example, we expect this assessment to be a major contributor to the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (due to be published in 2007). In addition, we expect the information generated will be used by the Global Climate Observing System Atmospheric Observation Panel to help identify effective ways to reduce observational uncertainty.

Recent efforts to address the uncertainties regarding the temperature structure of the lower atmosphere (i.e., from the surface through the lower stratosphere) have included release of a report under the auspices of the National Research Council (NRC) entitled