| 北极地区低平流层惯性重力波的观测研究 |
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| 引用本文： | 杨遵勋,黄开明,王睿,张绍东.北极地区低平流层惯性重力波的观测研究[J].地球物理学报,2019,62(8):2793-2805. |
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| 作者姓名： | 杨遵勋 黄开明 王睿 张绍东 |
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| 作者单位： | 1. 武汉大学电子信息学院, 武汉 430072;2. 中国极地研究中心, 上海 200136 |
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| 基金项目： | 国家自然科学基金（41474127，41674151，41531070），南北极环境综合考察与评估专项（CHINARE2017-0204）共同资助. |
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| 摘 要： | 南极地区重力波活动有大量报道，相对而言，北极地区重力波的研究还很少.本文利用极区Ny-Alesund站点（78.9°N，11.9°E）无线电探空仪从2012年4月1日到2017年3月31日共5年的观测数据，统计分析了北极地区低平流层惯性重力波的特征.观测显示，月平均纬向风在20 km以下盛行东向风，再随着高度增加，逐渐呈现出半年振荡现象.对流层顶高度在5~13 km范围内变化，其月平均高度显示出年循环，最高出现在夏季，约为10 km，最低出现在冬季，约为8.5 km.对流层和低平流层月平均温度都显示出明显的年周期变化，这与中低纬度观测结果有所不同.结合Lomb-Scargle谱分析和矢端曲线方法，估算了准单色惯性重力波参数.个例研究表明，低平流层惯性重力波呈现出远离源区的自由传播性质.统计结果显示，惯性重力波的水平和垂直波长分别集中在50~450 km和1~4 km范围内，本征频率集中在1~2.5倍惯性频率间，这些值都比中低纬度观测值稍小.垂直方向本征相速度主要集中在-0.3~0 m·s-1，而纬向和经向本征相速度集中在-40~40 m·s-1之间.在5年的观测中，大约91.5%的惯性重力波向上传播.在冬季和早春，由于极地平流层极涡活动，激发出向下传播的惯性重力波，因此，向下传播的比例上升到相应月份的20%左右.由于低层大气盛行的东向风的滤波效应，低平流层大部分惯性重力波向西传播.波能量呈现出明显的年周期变化，最大值在冬季、最小值在夏季，与北半球中低纬度观测结果一致，表明北半球重力波活动普遍冬季强、夏季弱.
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| 关 键 词： | 惯性重力波 极区低平流层 矢端曲线 无线电探空仪观测 |
| 收稿时间： | 2018-04-03 |
An observational study of inertia gravity waves in the lower stratosphere over the Arctic |
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| YANG ZunXun,HUANG KaiMing,WANG Rui,ZHANG ShaoDong.An observational study of inertia gravity waves in the lower stratosphere over the Arctic[J].Chinese Journal of Geophysics,2019,62(8):2793-2805. |
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| Authors: | YANG ZunXun HUANG KaiMing WANG Rui ZHANG ShaoDong |
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| Institution: | 1. School of Electronic Information, Wuhan University, Wuhan 430072, China;2. Polar Research Institute of China, Shanghai 200136, China |
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| Abstract: | Relative to many investigations of inertial gravity waves (IGWs) in the Antarctic, IGW activity in the Arctic region is less reported. We use radiosonde observations at the Ny-Alesund station (78.9°N, 11.9°E) during 5 years from 1 April 2012 to 31 March 2017 to study the IGW characteristics in the lower stratosphere over the Arctic. The observation reveals a prevailing eastward zonal background wind below 20 km, and then, with the increase of height, the monthly averaged zonal wind exhibits a semiannual oscillation. The tropopause is in a height range of 5~13 km, and its monthly averaged height shows an annual cycle with the maximum at about 10 km in summer and the minimum at about 8.5 km in winter. An obvious annual cycle can be seen in the background temperature from the troposphere to the lower stratosphere, which is different from the results at middle and low latitudes. By combining Lomb-Scargle spectrum and hodograph technique, the parameters of IGWs are estimated. The case analysis demonstrates that the lower stratospheric IGWs exhibit a feature of freely propagating waves. The statistical study indicates that the IGWs have the dominant horizontal and vertical wavelengths of 50~450 km and 1~4 km, respectively, and the dominant intrinsic frequency being 1~2.5 times the inertia frequency. These values are slightly smaller than those observed at middle and low latitudes. The intrinsic phase speed is mainly in the range of -0.3~0 m·s-1 in the vertical direction, and in the range of -40~40 m·s-1 in both the zonal and meridional directions. About 91.5% of the IGWs propagate upward, while in winter and early spring, the downward propagating waves increase to about 20% due to the activity of polar stratospheric vortex. Because of the filtering of the prevailing eastward zonal wind in the lower atmosphere, the IGWs in the lower stratosphere display a dominant direction of westward propagation. Wave energy is the maximum in winter and the minimum in summer, which is consistent with the results at middle and low latitudes in the northern hemisphere. This indicates that the IGW activity over the northern hemisphere is generally the strongest in winter and the weakest in summer. |
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| Keywords: | Inertial gravity waves (IGWs) Lower stratosphere Hodograph technique Radiosonde observation |
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