Fast responses of Northern Hemisphere winter daily circulation to anthropogenic aerosols |
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| Institution: | 1. Key Laboratory of Meteorological Disaster, Ministry of Education (KLME)/Joint International Research Laboratory of Climate and Environmental Change (ILCEC)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters (CIC-FEMD), Nanjing University of Information Science and Technology, Nanjing, 210044, China;2. Joint Innovation Center for Modern Forestry Studies, College of Biology and Environment, Nanjing Forestry University, Nanjing, 210037, China;3. Department of Atmospheric and Environmental Sciences, University at Albany, State University of New York, Albany, NY, 12222, USA;1. Department of Geography, Tokyo Metropolitan University, Hachioji-shi, Tokyo, Japan;2. Centre for Electromagnetics, National Aerospace Laboratories, Council of Scientific and Industrial Research, Kodihalli, Old Airport Road, Bengaluru, Karnataka, India;1. Department of Physics, Yazd University, Yazd, Iran;2. Department of Geography, Yazd University, Yazd, Iran;1. College of Ocean and Meteorology, Guangdong Ocean University, Zhanjiang 524088, China;2. Department of Earth Sciences, National Taiwan Normal University, Taipei 11677, Taiwan;3. Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science and Technology, Nanjing 210044, China;4. Utah Climate Center, Utah State University, Logan, UT 84322, USA;1. Department of Earth Science, Science and Research Branch, Islamic Azad University, Tehran, Iran;2. Space Physics Group, Department of Physics, Faculty of Science, Yazd University, Iran |
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| Abstract: | Anthropogenic aerosols (AA) have significantly caused anomalous winter mean atmospheric circulation over the Northern Hemisphere, but the main daily patterns of winter large-scale circulation change are not well understood. Here a self-organizing map analysis is applied to identify the leading patterns in AA-induced winter daily geopotential height (Z) anomaly fields simulated by three atmospheric general circulation models, with a focus on fast adjustments. Two winter daily circulation response patterns with a synoptic time scale are found: one pattern shows concurring Z anomalies over North America and North Asia with the same sign and the Bering Sea seeing the opposite, resembling the Asia–Bering–North American teleconnection; while the other is the Arctic Oscillation-like pattern with similar Z anomalies over North Pacific and North Atlantic and the opposite over the Arctic region. The AA-induced anomalous precipitation over the tropics and anomalous synoptic eddy activities over the extratropical oceans concur to support and maintain these circulation anomaly patterns. The winter-mean climate responses to AA can be understood as a result of these daily anomaly patterns, especially over the higher latitudes. Specifically, the associated changes in surface air temperature (SAT) over the mid-high latitudes are caused by the AA-driven meridional movements of polar (cold and dry) airmass and midlatitude (warm and moist) airmass in the regions, mainly through the relevant surface downward longwave radiation. This study highlights the role of AA in altering daily weather patterns, which is not sufficiently captured by seasonal mean responses. |
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| Keywords: | Climate responses Circulation patterns Anthropogenic aerosols Self-organizing maps |
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