Quantifying Uncertainty in Changes in Storm Tracks Associated with Climate Change

Monier, E., J. Scott and A.P. Sokolov
Conference Proceedings, American Meteorological Society 24th Conference on Climate Variability and Change (New Orleans, January 25), Report Nr. 0

Changes in extratropical storm tracks associated with climate change can directly affect the transport of momentum, energy and water vapor as well as impact the carbon cycle and modify the ocean circulation. For these reasons quantifying the possible range of changes in storm-track intensity is very relevant. In this paper, we analyze the transient eddy kinetic energy from six simulations using the MIT IGSM-CAM framework. The MIT IGSM-CAM framework links the National Center for Atmospheric Research (NCAR) Community Atmosphere Model (CAM) version 3 to the MIT Integrated Global System Model (IGSM) version 2.3, an intermediate complexity fully coupled earth system model that allows simulation of critical feedbacks among its various components, including the atmosphere (represented by a zonal-mean statistical-dynamical model), ocean, land, urban processes and human activities. An essential feature of the MIT IGSM-CAM is the flexibility to vary the climate parameters of the framework (climate sensitivity, net aerosol forcing and ocean heat uptake rate). The simulations presented in this paper were carried out for two emission scenarios (a “Business as usual” scenario and a 660 ppm of CO2-eq stabilization) and three sets of climate parameters. The three values of climate sensitivity chosen are median and the bounds of the 90% probability interval of the probability distribution obtained by comparing the observed 20th century climate change with simulations by the IGSM with a wide range of climate parameters values. The associated aerosol forcing values were chosen to ensure a good agreement of the simulations with the observed climate change over the 20th century. Because the concentrations of sulfate aerosols significantly decrease over the 21st century in both emissions scenarios, climate changes obtained in these six simulations provide a good approximation for the median, and the 5th and 95th percentiles of the probability distribution of 21st century climate change.