Weather-Making High-Pressure Systems Play an Important Role in Shaping Climate

According to a study led by Duke University, high pressure systems over oceans are likely to intensify this century. These high pressure systems determine the tracks of tropical cyclones and hydrological extremes in northern hemisphere.

The details of this study were carried in the week's Nature Geosciences.

According to the study that is being conducted by Wenhong Li, assistant professor of earth and ocean sciences at Duke's Nicholas School of the Environment, and colleagues, the summertime near-surface high-pressure systems over the northern Pacific and Atlantic oceans strengthen. This plays an important role in shaping regional climate particularly the occurrence of drought and extreme summer rainfall.

With the help of climate model simulation the researchers predict the future changes in strength of the North Atlantic Subtropical high that occurs annually. This is referred to as the Bermuda high and the north Pacific Subtropical high.

Based on these simulations the high pressure system will intensify over the 21^st century. An increase in the land sea thermal contrast will ignite the system's intensification.  The land sea thermal contrast is counted by the difference between the ocean and land heating.

Li's co-authors on the new study are Laifang Li, a PhD student at Duke's Nicholas School; Mingfang Ting of the Lamont-Doherty Earth Observatory at Columbia University's Earth Institute; and Yimin Liu of the Chinese Academy of Sciences' Institute of Atmospheric Physics.

Based on the climate model simulations from the Intergovernmental Panel on Climate Change Fourth Assessment Report and 40 years of atmospheric circulation data from the European Centre for Medium-Range Weather Forecasts for the months of June, July and August they conducted their study.