Low Richardson Number in the Tropical Cyclone Outflow Layer
Low Richardson Number in the Tropical Cyclone Outflow Layer
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DOI：
10.1175/jas-d-14-0005.1
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发表时间：
2014-08
影响因子：
3.1
通讯作者：
J. Molinari;Patrick Durán;David Vollaro
中科院分区：
文献类型：
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作者：
J. Molinari;Patrick Durán;David Vollaro
摘要利用美国国家海洋和大气管理局G-IV飞机的下投探空仪对热带气旋中低体积理查德森数RB的存在进行了研究。在z = 7.5 km以上的400 m层中，96%的探空仪RB < 1, 35%的探空仪RB≤0.25。后者几乎肯定意味着动荡。对2004年伊万飓风的探空信号进行了详细的研究。湍流层可分为三大类。第一个出现在云底附近的中心密集阴云边缘，相对湿度降至40%以下。湍流层内部静态稳定度接近于零，其上方存在稳定和剪切最大值。这种结构与之前从云底下的降水升华中看到的结构非常相似。第二类湍流层位于对流层上层的CDO云内，几乎完全是由于接近零的静稳定性造成的。这很可能是由于CDO顶部下方的长波通量发散导致的冷却。第三种类型的湍流…
AbstractDropsondes from the NOAA G-IV aircraft were used to examine the presence of low bulk Richardson numbers RB in tropical cyclones. At least one 400-m layer above z = 7.5 km exhibited RB < 1 in 96% of the sondes and RB ≤ 0.25 in 35% of the sondes. The latter represent almost certain turbulence. Sondes from major Hurricane Ivan (2004) were examined in detail. Turbulent layers fell into three broad groups. The first was found below cloud base near the edge of the central dense overcast (CDO) where relative humidity fell below 40%. Near-zero static stability existed within the turbulent layer with stability and shear maxima above it. This structure strongly resembled that seen previously from sublimation of precipitation beneath cloud base. The second type of turbulent layer was located within CDO clouds in the upper troposphere and was due almost entirely to near-zero static stability. This most likely arose as a result of cooling via longwave flux divergence below CDO top. The third type of turbulent ...