Long-term behavior of the Kelvin waves revealed by CHAMP/GPS RO measurements and their effects on the tropopause structure
Long-term behavior of the Kelvin waves revealed by CHAMP/GPS RO measurements and their effects on the tropopause structure
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DOI：
10.5194/angeo-24-1355-2006
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发表时间：
2006-07
影响因子：
1.9
通讯作者：
M. Ratnam;T. Tsuda;T. Kozu;S. Mori
中科院分区：
文献类型：
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作者：
M. Ratnam;T. Tsuda;T. Kozu;S. Mori
抽象的。使用长期（2001年5月至2005年10月）CHAMP/GPS（挑战迷你卫星有效负载/全球定位系统）无线电掩星（RO）测量研究了开尔文波的垂直和时间变化以及对热带对流层顶的相关影响。人们发现这些波的周期在 10 到 15 天之间变化，垂直波长为 5 到 8 公里。这些变化在时间-经度剖面上清晰地显示了向东的相位传播，以及在高度-经度上随高度的向东相位倾斜，显示了开尔文波的特征。温度的峰值变化出现在印度洋上空和赤道广大区域内的西太平洋。开尔文波振幅在准两年期振荡（QBO）向东切变中显着增强，并且在 QBO 向西阶段被限制在对流层顶及其周围，在 QBO 向东阶段期间，开尔文波振幅在对流层顶内延伸 17 至 25 公里，并在上方衰减，这与之前报道的结果一致。在北半球冬季的几个月里，振幅不断增加，有时本质上是高度零星的。热带对流层顶附近开尔文波振幅的季节和年际变化与对流层顶高度和温度完全一致，在最大开尔文波活动期间对流层顶急剧变化。对流层顶高度和开尔文波活动在大多数时间都明显存在明显的年度振荡以及逐月重合，开尔文波振幅分别在北半球冬季和夏季出现最大和最小。此外，对流层顶结构中准两年期振荡（QBO）的特征也可以在对流层顶的长期变化中看到，尽管与年度振荡相比，其幅度较小。 QBO西移阶段（强开尔文波活动期间）20km处（2001~2002年冬季和2003~2004年冬季），对流层顶高度稍大，对流层顶尖锐，气温较低。已经讨论了这些观察到的特征背后的过程。
Abstract. The vertical and temporal variations of Kelvin waves and the associated effects on the tropical tropopause were studied using long-term (from May 2001 to October 2005) CHAMP/GPS (CHAllenging Mini satellite Payload/Global Positioning System) radio occultation (RO) measurements. The periods of these waves were found to be varying in between 10 and 15 days, with vertical wavelengths 5–8 km. These variations clearly show eastward phase propagation in the time-longitude section and eastward phase tilts with height in altitude-longitude, displaying the characteristics of Kelvin waves. The peak variance in the temperature is found over the Indian Ocean and into the western Pacific within the broad region of the equator. Kelvin wave amplitudes were found significantly enhanced in the eastward shear of the quasi-biennial oscillation (QBO) and are confined in and around the tropopause during westward phase of QBO, where it extends between 17 and 25 km during the eastward phase of QBO and is damped away above, consistent with earlier reported results. The amplitudes are increasing during the months of Northern Hemisphere winter and sometimes they are highly sporadic in nature. Seasonal and inter-annual variations in the Kelvin wave amplitudes near the tropical tropopause coincide exactly with the tropopause height and temperature, with a sharp tropopause during maximum Kelvin wave activity. A clear annual oscillation, along with a month-to-month coincidence is evident most of the time in both the tropopause height and Kelvin wave activity, with maximum and minimum Kelvin wave amplitudes during the Northern Hemisphere winter and summer, respectively. In addition, a signature of quasi-biennial oscillation (QBO) in the tropopause structure is also seen in long-term tropopause variations, although the amplitudes are less when compared to the annual oscillation. In the westward phase of QBO (during strong Kelvin wave activity) at 20km (in 2001–2002 winter and 2003–2004 winter), the tropopause height was slightly larger with a sharp tropopause and low temperature. The process behind these observed features has been discussed.