JIFRESSE Seminar: Changes of the Arctic Sea Ice in Autumn and Winter and Their Effects on Winter Climate in the Mid-latitudes of the Northern Hemisphere, Yong Luo

Wednesday, August 9, 2017
11AM – 12Noon
JIFRESSE | 4242 Young Hall

 

Changes of the Arctic Sea Ice in Autumn and Winter and Their Effects on Winter Climate in the Mid-latitudes of the Northern Hemisphere

Dr. Yong Luo
Professor and Associate Director
Department of Earth System Science/Institute for Global Change Studies
Tsinghua University

Dr. Yong LUO received his bachelor, master degree and PhD at Geophysics Department of Peking University. He currently serves as the professor and associate director of the Department of Earth System Science, Tsinghua University. He is vice chair of China WCRP/CliC and IUGG/IACS, vice president of Chinese Society of Cryosphere Science, and the vice editor-in-chief of Advances in Climate Change Research. Before joining Tsinghua, he had worked at National Climate Center, China Meteorological Administration for 18 years. Dr LUO dedicates himself to climate-water-energy research, including development and evaluation of earth system model, process and mechanism of global energy-water cycle, global climate change detection, attribution and projection, land surface-hydrological assimilation and climate prediction, climate change impacts risk and management, meteorology for renewable energy. He was Lead Author of the First, Second and Third China National Assessment Report of Climate Change, the Fourth Assessment Report of IPCC WGI and the Sherpa for UN Secretary General Mr Ban Ki-moon’s High-Level Panel on Global Sustainability. After 2006 he coauthored over 150 journal papers and 14 books on climate change and sustainable development, including Lancet, PNAS and Nature Communications. He was awarded special allowance by the State Council of China in 2008 and he was a member of Nobel Peace Prize-Winning IPCC Team in 2007.

Abstract

Changes in the Arctic sea ice and winter climate in the mid-latitudes of the Northern Hemisphere from 1988 to 2012 have significant linear trends. Surface air temperature has been warming in the Arctic and cooling in the middle latitudes of Eurasian continents. Correlation analysis shows that the changes of sea ice in autumn are highly correlated to the second pattern of EOF decomposition of sea level pressure, while the changes of sea ice in winter are highly correlated to the third pattern. Regression results show that in addition to the linear trends, there are two new different cooling patterns in the mid-latitudes of the Northern Hemisphere. These two patterns are related to the autumn and winter sea ice changes respectively. Furthermore, NCAR/CESM is applied in three groups of sensitivity experiment. The simulation results show that there are robust cooling signals in the middle latitudes of Eurasian continents and the patterns are similar to the so-called “warm ocean and cold continent”. The cooling in early winter is related to sea ice changes in autumn while cooling in middle and late winter is related to sea ice changes in winter. As the response of sea ice changes in autumn and winter, positive sea level pressure anomalies appear in the polar regions, Eurasian continent and its northern region, while negative anomalies appear in the middle of Eurasian continents in mid-latitudes and the Pacific Ocean in the middle and high latitudes. Moreover, positive 500hPa geopotential height anomalies appear in the polar regions and northeastern North America while negative anomalies appear in the middle of Eurasian continents in the mid-latitudes.