Characteristics of atmospheric gravity wave activity in the polar regions revealed by GPS radio occultation data with CHAMP
Characteristics of atmospheric gravity wave activity in the polar regions revealed by GPS radio occultation data with CHAMP
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DOI：
10.1029/2007jd008938
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发表时间：
2008-02
影响因子：
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通讯作者：
Hayato Hei;T. Tsuda;T. Hirooka
中科院分区：
文献类型：
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作者：
Hayato Hei;T. Tsuda;T. Hirooka
[1]利用2001-2005年GPS无线电掩星观测资料，研究了极地平流层大气重力波的气候特征。在12 ~ 33 km的20° × 10°纬圈内，计算了垂直波长小于7 km的温度起伏，并测定了每个月的波位能Ep。在北极地区（50-90°N），Ep的年变化在冬季最大，与纬向平均水平风V和Eliassen-Palm（E-P）通量Fz相一致。较大的Fz值表明行星波活动较高，导致极涡扭曲。不平衡气流通过地转调整激发重力波。在南极地区（50-90°S），Ep在冬季逐渐增加，春季达到最大值，然后迅速下降。V的时间导数与Ep的峰值相吻合，Ep的水平分布与V具有相似的结构，表明Ep的增强与极涡的衰减密切相关。在北极地区发生重大变暖事件期间，E-P通量ΔF的辐散增强，与大Ep相一致。在南极，ΔF与春季的Ep密切相关。引力波似乎是通过行星波的瞬变和/或破碎有效地产生的。重力波的地形生成似乎只在有限的地区很重要，如斯堪的纳维亚半岛和南极半岛，这表明它在决定重力波的气候行为方面不如极地夜间急流重要。
[1] Using GPS radio occultation data during 2001–2005, we studied the climatological behavior of atmospheric gravity waves in the polar stratosphere. We calculated temperature fluctuations with vertical wavelengths shorter than 7 km and then determined the wave potential energy, Ep, every month in a longitude-latitude cell of 20° × 10° between 12 km and 33 km. In the Arctic region (50–90°N), Ep shows an annual variation with maximum in winter, consistent with the zonal mean horizontal wind, V, and the Eliassen-Palm (E-P) flux, Fz. The large Fz values indicate higher planetary wave activity, resulting in distortion of the polar vortex. The unbalanced flow can then excite gravity waves through geostrophic adjustment. In the Antarctic region (50–90°S), Ep gradually increases during winter and reaches its maximum in spring before decreasing rapidly. The time derivative of V coincides with the Ep peak and the horizontal distribution of Ep has a similar structure to V, suggesting that the Ep enhancement is closely related to the decay of the polar vortex. During major warming events over the Arctic, the divergence of E-P flux, ΔF, was enhanced, coinciding with large Ep. In the Antarctic, ΔF strongly correlates with Ep in spring. Gravity waves seem to be effectively generated through planetary wave transience and/or breaking. Orographic generation of gravity waves seems to be important in limited areas only, such as Scandinavia and the Antarctic Peninsula, showing that it is less important than the polar night jet in determining the climatological behavior of gravity waves.