Gravity wave activity during stratospheric sudden warmings in the 2007–2008 Northern Hemisphere winter
Gravity wave activity during stratospheric sudden warmings in the 2007–2008 Northern Hemisphere winter
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DOI：
10.1029/2009jd011867
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发表时间：
2009-09
影响因子：
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通讯作者：
Ling Wang;M. Alexander
中科院分区：
文献类型：
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作者：
Ling Wang;M. Alexander
[1]我们使用星座气象观测系统的温度反演，电离层与气候（COSMIC）/福尔摩沙卫星使命3（FORMOSAT-3）和卫星小卫星有效载荷（CHAMP）全球定位卫星（GPS）无线电掩星廓线和来自地球观测系统卫星高分辨率动力学临边探测器（HIRDLS）的独立温度反演以及使用宽带发射辐射测量法（SABER）的大气探测2007-2008年北方冬季平流层突然变暖（SSW）事件和伴随的重力波（GW）温度振幅。我们确定了四个SSW事件（包括一个主要的）发生在2008年1月下旬至2月下旬。我们检测到增强GW振幅在平流层和减弱GW振幅在较低的中间层在变暖事件。GW增强/抑制和升温/降温事件的时间通常很接近（在几天内）。我们还发现，平流层GW振幅一般较大的极涡边缘和较小的涡核和涡外，平流层GW振幅一般较小的北太平洋。使用一个简化的GW色散关系和GW射线跟踪实验，我们证明，增强GW振幅在平流层SSWs期间可以在很大程度上解释GW传播的考虑。在SSW期间，在平流层顶附近存在GW临界水平（背景风与GW相速度相同的水平）将阻止GW传播到中间层，从而可能导致在较低的中间层观察到的GW活动减弱。由于这是第一次研究分析COSMIC和CHAMP GPS温度反演高达60公里的高度，我们比较的GPS分析与HIRDLS和SABER测量。我们发现，从GPS数据得到的纬向平均温度的时间变化是合理的，高达60公里的高度，但GPS数据是不敏感的SSW比HIRDLS和SABER数据。全球定位系统的GW分析与HIRDLS在海拔35 km以下的分析是一致的，但GPS数据中显示的较高海拔的小尺度变化似乎是值得怀疑的。
[1] We use temperature retrievals from the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC)/Formosa Satellite Mission 3 (FORMOSAT-3) and Challenging Minisatellite Payload (CHAMP) Global Positioning Satellite (GPS) radio occultation profiles and independent temperature retrievals from the EOS satellite High Resolution Dynamics Limb Sounder (HIRDLS) and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) aboard the TIMED satellite to investigate stratospheric sudden warming (SSW) events and the accompanying gravity wave (GW) temperature amplitudes in the 2007–2008 Northern Hemisphere winter. We identify four SSW events (including a major one) occurring from late January to late February in 2008. We detect enhanced GW amplitudes in the stratosphere and subdued GW amplitudes in the lower mesosphere during the warming events. The timing of GW enhancement/suppression and warming/cooling events was generally close (within a couple days). We also find that stratospheric GW amplitudes were generally larger at the polar vortex edge and smaller in the vortex core and outside of the vortex and that stratospheric GW amplitudes were generally small over the North Pacific. Using a simplified GW dispersion relation and a GW ray-tracing experiment, we demonstrate that the enhanced GW amplitudes in the stratosphere during SSWs could be explained largely by GW propagation considerations. The existence of GW critical levels (the level at which the background wind is the same as the GW phase speed) near the stratopause during SSWs would block propagation of GWs into the mesosphere and thus could lead to the observed subdued GW activity in the lower mesosphere. Since this is the first study to analyze the COSMIC and CHAMP GPS temperature retrievals up to 60 km in altitude, we compare the GPS analysis with those from HIRDLS and SABER measurements. We find that the temporal variability of zonal mean temperatures derived from the GPS data is reasonable up to ∼60 km in altitude, but the GPS data were less sensitive to SSWs than the HIRDLS and SABER data. GW analysis from GPS is consistent with HIRDLS up to ∼35 km in altitude, but it seems that the small-scale variability at higher altitudes revealed in the GPS data is questionable.