| 夏季进入北极温带气旋的活动特征及其影响因素 |
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| 引用本文： | 史楠,王召民,何海伦.夏季进入北极温带气旋的活动特征及其影响因素[J].气象科学,2022,42(2):171-181. |
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| 作者姓名： | 史楠 王召民 何海伦 |
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| 作者单位： | 河海大学 海洋学院, 南京 210098;河海大学 海洋学院, 南京 210098;南方海洋科学与工程广东省实验室(珠海), 广东 珠海 519082;自然资源部第二海洋研究所, 杭州 310012 |
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| 基金项目： | 国家海洋局极地考察办公室2020年度极地科学协同创新平台委托项目(CXPT2020009);南方海洋科学与工程广东省实验室(珠海)创新团队项目(311021008) |
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| 摘 要： | 进入北极地区的气旋在移动过程中往往伴有大风、强降水等特征,对北极气候变化有深刻的影响。基于NCEP2再分析资料,识别并跟踪了北半球夏季(6—8月)从中纬度进入北极的温带气旋,考察了其年际变化特征和影响因素。结果表明:1979—2019年夏季进入北极的温带气旋共867个,其中消失在北极边缘区域和中心区域的数量分别为688个和161个,且后者平均强度更大、平均持续时间更长。分区域研究发现,夏季从陆地进入极区的气旋个数较多,而从海洋进入极区的气旋强度更大,活动更为剧烈。对进入北极的气旋年际时间序列进行分析发现,夏季进入北极的气旋个数和强度均存在年际变率,其中气旋个数的年际变率尤为显著。气旋个数年际变率主要周期为5 a,强度的主要周期约为2.7 a。进一步分析发现,引导气流是影响气旋向北移动的重要因素。此外,夏季北大西洋气旋强度与同期北大西洋涛动(North Atlantic Oscillation,NAO)指数存在较好相关。研究还表明,进入极区气旋活动的年际变化受大气斜压不稳定性的影响,在北太平洋地区区域平均的Eady增长率与气旋个数和强度的相关性均最强,相关系数分别为0.4和0.5。
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| 关 键 词： | 温带气旋 向极运动 夏季 年际变化 |
| 收稿时间： | 2021/11/10 0:00:00 |
| 修稿时间： | 2022/2/20 0:00:00 |
Characteristics of extratropical cyclones migrating into the Arctic in summer and their associated factors |
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| SHI Nan,WANG Zhaomin,HE Hailun.Characteristics of extratropical cyclones migrating into the Arctic in summer and their associated factors[J].Scientia Meteorologica Sinica,2022,42(2):171-181. |
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| Authors: | SHI Nan WANG Zhaomin HE Hailun |
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| Institution: | College of Oceanography, Hohai University, Nanjing 210098, China;College of Oceanography, Hohai University, Nanjing 210098, China;Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Guangdong Zhuhai 519082, China; State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou 310012, China |
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| Abstract: | Extratropical cyclones migrating into the Arctic often cause strong winds, heavy rainfall, and other extreme events during the process of moving, which has a profound impact on the Arctic climate change. By using the NCEP2 reanalysis data, we identified and tracked the extratropical cyclones that enter the Arctic from the mid-latitudes during the summer (form June to August), and interannual variability and influencing factors of those cyclones were investigated. The results show that, a total of 867 extratropical cyclones entered the Arctic in summer from 1979 to 2019, of which 688 and 161 dissipated in the arctic marginal region and the central region, respectively.The cyclones dissipated in the central region normally had higher intensity and longer duration. Through sub-regional research, it is found that the number of cyclones entering the Arctic from land is relatively larger, while the cyclones entering the Arctic from oceans were more intense and active. Results of the time series analysis shows that the numbers and intensities of cyclones entering the Arctic both exhibited significant inter-annual variability, especially the numbers of those cyclones. The annual period of numbers and intensities of cyclones are about 5 years and 2.7 years, respectively. Further analysis found that the steering flow is an important factor affecting the northward movement of those cyclones. In addition, there was a good correlation between summer North Atlantic cyclone intensity and North Atlantic Oscillation (NAO) index during the same period, reflecting the influence of large-scale atmospheric circulation. The results also show that the annual variation of cyclone entering the Arctic is affected by baroclinic instability.The correlation between the regional averaged Eady growth rate and number or intensity of cyclones entering the North Pacific is stronger in the North Pacific region, with the correlation coefficients being 0.4 and 0.5, respectively. |
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| Keywords: | extratropical cyclone poleward migration summer interannual variability |
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