Past climate variability from an upper-level perspective

Research on past climate variability would greatly benefit from an analysis of upper-level circulation. However, currently available data reach back only to 1948. In this project, historical upper-air data from 1900–58 have been reevaluated and gridded upper-level fields were statistically reconstructed. With these data, combined with climate model simulations, three key periods of 20th century climate variability were studied: the 1930s "Dust Bowl" droughts, the Arctic warming 1925–45, and the early 1940s climate anomaly. The results provide new insights into the processes of large-scale climate coupling. The process has been finalized in July 2008.

Past climate variability from an upper-level perspective - Extension period
(Abstract of proposal)
Understanding the mechanisms behind interannnual-to-decadal large-scale climate variations is a basis for assessing future climate change as well as for improving predictions of climate extremes such as droughts. The lack of understanding important climate variations during the past 100 years demonstrates that this goal is not yet reached. In the proposed project, two important open questions will be addressed by using historical upper-level data, reconstructions, and simulations with a chemistry-climate model. First, a detection and attribution study will be performed with respect to climate change in the early 20th century (as well during the last decades). Second, the relation between large-scale, multiannual droughts in different parts of the world and their relation to oceanic forcing will be analysed. Finally, the data work started in the ongoing project phase will be harmonised with other efforts, facilitating future reanalysis projects. The proposed extension period will contribute significantly to answering open questions in the area of large-scale climate variability and will add value to the results from the ongoing project.