Calendar

Hi everyone, We’ll meet in the Bjerknes Meeting Room on the 3rd floor on Monday 11 August, 11–12h. A program will be sent around closer to the day, but one topic will be a discussion on Bjerknes strategy. If you have anything to share with the Hazards Group, let me know in advance. I’ll send a reminder out in early August. Enjoy the summer! Stijn

Dear all, This week, there will be an additional BCCR Special seminar that will be given by David WJ Thompson, who is visiting BCCR from the Department of Atmospheric Science at Colorado State University in the USA. He will present his work on "An Observational Estimate of the Pattern Effect on Climate Sensitivity”. The seminar will take place in the usual BCCR seminar room (4th floor of the West wing) at 11:00. Abstract: The "pattern effect" refers to the dependence of climate sensitivity on the spatial structure of temperature change. Most evidence for the pattern effect comes from numerical experiments. Here, I will explore the evidence for the pattern effect in observations. The observational analyses focus on the relationships between the global-mean radiative response and spatially-varying variability in the surface temperature field. It is argued that the results of the observational analyses provide a statistical analogue to the causal response functions derived from atmospheric models forced with surface temperature patches. Consistent with the feedbacks inferred from numerical experiments, the observational analyses indicate large negative internal feedbacks due to temperature variability over the western Pacific. Unlike the results inferred from such experiments, the analyses indicate equally large positive internal feedbacks over the southeastern tropical Pacific and negative internal feedbacks over land areas. When estimated from observations, temperature variability over the land areas accounts for roughly 80% of the global-mean, negative internal feedback; and temperature variability over the southeastern tropical Pacific acts to attenuate the global-mean negative internal feedback by nearly 10%.