Research questions

• Increasing greenhouse gas concentrations in the atmosphere lead to increasing surface air temperatures (SAT). The probability density function (PDF) of local daily SAT will shift to warmer temperatures. But will the shape remain the same ? What will happen to the tails of this distribution ? For example, will the one in 10 year cold extreme at a particular location increase at the same rate as the mean or will it respond differently ?
• For those locations in which the PDF of daily SAT changes shape in a warming climate, leading to non-trivial changes in the probability of extreme temperatures, can we attribute these changes to particular physical processes ? For instance, to changes in the advection of warm or cold air masses due to changes in the probability of the local wind direction, the strength of the wind, the temperature of the advected air masses, or to local thermodynamical processes, like changes in the evaporation related to soil moisture changes, the local snow cover, the local stability of the atmospheric column ?
• How will the NAO index/pattern characteristics change in a warming climate? Do eastward shifts of the NAO pattern, as recently observed, occur more often and what are the implications of this for the (severe) storm climate of Western-Europe?
• What is the impact of varying external forcings (solar irradiance, volcanic dust) on large-scale climatic features for the 1940-2000 period ?
• Do changes in the shape of the local PDF of SAT occur gradually in time or are sudden changes a possibility ?
• For the present day conditions, how well does the model simulate the observed extremes in local temperature, wind and precipitation ?
• Statistical methods, such as Generalised Extreme Value analysis and various resampling techniques, have been developed to quantify very rare events on the basis of relatively short observational timeseries. How adequate are these methods ? When applied to model data, how well do these methods perform ?
• What will happen to ENSO in a warming climate ? Will it change its spectral characteristics ? Will there be a sudden change ?
• Will there be a change in the teleconnections of ENSO to other parts of the globe ?
• Is the concept of "weather regimes" applicable to the extra-tropical atmosphere in winter ?
• Is the response of the extra-tropical winter atmosphere to changing greenhouse gas concentrations well described by changes in the frequency of occurence of the different weather regimes ?
• On average, the atmosphere and ocean transport heat polewards to balance the radiation deficit in high latitudes. During episodes when the ocean heat transport is lower than average, does the atmosphere compensate for that or does the radiation budget at the top of the atmosphere change as well ?
• What happens to the atmospheric and oceanic heat transport in a warming climate ?
• Is there are clear relationship between local daily SAT extremes and large scale circulation anomalies, relating extreme conditions in different regions of the globe ?
• Does this relationship change in a warming climate ?
• What happens to the thermo-haline circulation in a warming climate ? Is there a possibility for a total collapse of the deep water formation (DWF) in the North Atlantic ? How predictable is a possible sudden change in this DWF ?
• Variations in the South American Convergence Zone and precipitation over the Amazone basin are profound and have a great impact on South American society in terms of energy production and agriculture. How will these change in a warmer climate ?

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