[A-CG43] Science in the Arctic Region

[ACG43-01] An Assessment of Lower Tropospheric Temperature Advection Towards the Arctic Amplification Pattern Using a Large-scale Ensemble Model Experiment Dataset

*Masatake Hori¹, Masakazu Yoshimori¹ (1.University of Tokyo, Atmosphere Ocean Research Institute)

Keywords:Polar Amplification, Thermal advection

Using an AGCM large scale ensemble experiment, we investigate the role of lower tropospheric temperature advection towards the projected polar amplification pattern. The dataset we use is the 'database for policy decision making for future climate change' (d4pdf) which consists of a 60 year historical and non-warming simulation with 100 members each. The dataset also includes a 60 year simulation of the climate 4K and 2K warmer than the pre-industrial climate with 90 and 54 members each. Using the non-warming simulation (HPB-NAT) as a reference, we examine the difference in temperature advection under changing basic states of the historical simulation (HPB) and future simulations (HFB-2K / 4K). The total difference in advection is separated to account for the change in climatological wind and temperature from their deviations and is further decomposed to quantify the effect of dynamical change and thermodynamical changes. Under the HPB simulation, it is shown that the total change in advection is overall positive in the Arctic with positive signal located along the sea-ice boundary in the North Atlantic and along the Eurasian continent which signifies an overall warming of the Arctic due to thermal advection. The changing climatological basic state accounts for an increase in positive advection along the Barents-Kara Sea and the Canadian archipelago which is mostly driven by the dynamical term which is the change in climatological wind pattern. The thermodynamical term, which accounts for the change in advection from the change in climatological temperature field acts to cool the lower troposphere along the Eurasian coast due to weakening gradient in temperature. Further results regarding the change under 2K / 4K simulation and associated circulation patterns sustaining these temperature advection pattern and their contribution towards the simulated Arctic amplification pattern is discussed in the presentation.