{"title":"Influence of Phase Variations of Madden-Julian Oscillation on Wintertime Large-Scale Cold Events in China","authors":"Tao Feng, Li Li, Lei Wang, Zelin Cai","doi":"10.16993/tellusa.3233","DOIUrl":null,"url":null,"abstract":"The station observations and reanalysis dataset are utilized to explore the effects of Madden-Julian Oscillation (MJO) on the cold extremes over the whole country of China, and the possible mechanisms from the perspective of the thermodynamics. Here, we focus on the principal modes of different phases of MJO in winter and their influences on the large scale cold events (LSCEs) that are identified firstly. The time evolution and the spatial features of LSCEs are checked for a basic insight of the LSCEs in China, of which the annual variability and regional differences are obvious among the chosen LSECs. In addition, the first (second) empirical orthogonal decomposition mode of MJO shows an opposite feature that positive values in Phases 1–3 (Phase 4–5) and negative values in Phases 5–7 (Phase 7–8), with the explanation of variance at 30.6% (26%). Furthermore, according to the threshold of ±1.5 in standardized time series of two principal components (PC1 and PC2), the events are chosen and clarified into four cases (+PC1, –PC1, +PC2 and –PC2). All the MJO-related cases present the increases of LSCEs but with regional and intensity differences. For the case of +PC1, the cold advection from higher latitudes transport to eastern Asia inducing negative temperature anomalies thereof. For the case of –PC1, besides the eastern Asian region, there still the cold advections across the Inner Mongolia regions, leaving negative anomalies over the region either. For the case of +PC2, the southward wind and the accompanied cold advection are stronger than the others affecting mostly regions in China, which leads to the more decreases of temperature. For the case of –PC2, the cold advections are weaker, resulting in the less temperature decreases over the southeastern China. Meanwhile, the tropospheric cyclonic and anti-cyclonic circulation anomalies are beneficial to the persistence of local extremes.","PeriodicalId":54433,"journal":{"name":"Tellus Series A-Dynamic Meteorology and Oceanography","volume":null,"pages":null},"PeriodicalIF":2.0000,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Tellus Series A-Dynamic Meteorology and Oceanography","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.16993/tellusa.3233","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
The station observations and reanalysis dataset are utilized to explore the effects of Madden-Julian Oscillation (MJO) on the cold extremes over the whole country of China, and the possible mechanisms from the perspective of the thermodynamics. Here, we focus on the principal modes of different phases of MJO in winter and their influences on the large scale cold events (LSCEs) that are identified firstly. The time evolution and the spatial features of LSCEs are checked for a basic insight of the LSCEs in China, of which the annual variability and regional differences are obvious among the chosen LSECs. In addition, the first (second) empirical orthogonal decomposition mode of MJO shows an opposite feature that positive values in Phases 1–3 (Phase 4–5) and negative values in Phases 5–7 (Phase 7–8), with the explanation of variance at 30.6% (26%). Furthermore, according to the threshold of ±1.5 in standardized time series of two principal components (PC1 and PC2), the events are chosen and clarified into four cases (+PC1, –PC1, +PC2 and –PC2). All the MJO-related cases present the increases of LSCEs but with regional and intensity differences. For the case of +PC1, the cold advection from higher latitudes transport to eastern Asia inducing negative temperature anomalies thereof. For the case of –PC1, besides the eastern Asian region, there still the cold advections across the Inner Mongolia regions, leaving negative anomalies over the region either. For the case of +PC2, the southward wind and the accompanied cold advection are stronger than the others affecting mostly regions in China, which leads to the more decreases of temperature. For the case of –PC2, the cold advections are weaker, resulting in the less temperature decreases over the southeastern China. Meanwhile, the tropospheric cyclonic and anti-cyclonic circulation anomalies are beneficial to the persistence of local extremes.
期刊介绍:
Tellus A: Dynamic Meteorology and Oceanography along with its sister journal Tellus B: Chemical and Physical Meteorology, are the international, peer-reviewed journals of the International Meteorological Institute in Stockholm, an independent non-for-profit body integrated into the Department of Meteorology at the Faculty of Sciences of Stockholm University, Sweden. Aiming to promote the exchange of knowledge about meteorology from across a range of scientific sub-disciplines, the two journals serve an international community of researchers, policy makers, managers, media and the general public.
Original research papers comprise the mainstay of Tellus A. Review articles, brief research notes, and letters to the editor are also welcome. Special issues and conference proceedings are published from time to time.
The scope of Tellus A spans dynamic meteorology, physical oceanography, data assimilation techniques, numerical weather prediction, climate dynamics and climate modelling.