David W. J. Thompson
Dept. of Atmospheric Science, CSU

My research and that of my students is focused on improving our understanding of large-scale climate variability. The preponderance of my work is based on the analysis and diagnosis of observational data. But it has also exploited simple balance models, idealized general circulation models and the output from coupled chemistry-climate and atmosphere-ocean general circulation models.

In general, my papers are focused on 1) identifying novel aspects of the climate system in observations and 2) testing hypotheses motivated by observational analyses in numerical models. My papers have explored atmospheric variability across a range of spatial and temporal scales, including the origins and impacts of large-scale patterns of climate variability, the mechanisms that underlie observed climate change and the simulated response to external climate forcing, the signatures of and mechanisms for stratosphere/troposphere coupling, ocean/atmosphere interaction in the Southern Hemisphere and North Atlantic, decadal climate variability, and the role of cloud radiative effects in climate variability.

My current research is focused on the following topics:

• Exploring the importance of coupled chemical/dynamical processes for climate variability in observations and coupled-chemistry climate models. The work includes understanding the influence of wildfire smoke on the large-scale circulation.

• Understanding changes in surface temperature 'persistence' - or 'memory' under climate change. The persistence of surface temperature is important since the impacts of weather events on ecosystems and society depend critically on the length of the event. Recent research suggests that the persistence of surface temperature is likely to change under global warming. But the physics of such changes are not well understood. For example: Extreme temperature events are expected to last longer in many regions of the Northern Hemisphere, but the reasons for this remain largely unclear. Our research in this area includes:1) exploring the evidence for changes in temperature persistence under climate change in observations and climate change simulations and 2) probing the physics of the changes using a range of theoretical tools.

• Understanding the role of the ocean circulation in extratropical climate variability. The research includes probing 1) the importance of the ocean circulation in driving observed variability in the sea-surface temperature field using remotely-sensed data in conjunction with ocean state estimates, and 2) the resulting impacts of the ocean-circulation induced sea-surface temperature anomalies on the global-climate system.

• Exploring the influence of cloud and clear-sky radiative processes on the large-scale atmospheric circulation, especially at middle and high latitudes. The work includes using observations and targeted numerical experiments to explore the role of radiative processes in governing the amplitude and structure of the climatological-mean extratropical circulation and its variability.

• Understanding the structure and origins of periodicity in extratropical wave amplitudes (i.e., storminess) on ~20-25 day timescales. The research includes analyzing and diagnosing periodicity in the large-scale circulation in observations, developing idealized models of the periodicity, and exploring the implications of the periodicity for subseasonal variations in surface weather.

• Developing dynamical and statistical methods for distinguishing between the signatures of internal variability and anthropogenic forcing in climate change. The work includes exploiting large-ensembles of climate change simulations to inform analyses of observed climate change.

Please also see the Annular Modes website, which includes basic background material on annular variability: Annular Modes Website