Seeking reasons for the differences in size spectra of electrified storms over land and ocean
Seeking reasons for the differences in size spectra of electrified storms over land and ocean
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DOI：
10.1002/2016jd025150
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发表时间：
2016-08
期刊：
影响因子：
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通讯作者：
S. Bang;E. Zipser
中科院分区：
文献类型：
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作者：
S. Bang;E. Zipser
这项研究扩展了Bang和Zipser（2015）的结果，该结果表明，具有闪电的海洋降水特征往往比大陆上的海洋降水特征大10倍以上，并且更加层状，并提出了一种假设，即某种形式的外部强迫正在以导致热带海洋更大的特征和更强的上升气流的方式起作用。在这项工作中，我们评估这一假设，使用再分析数据比较大尺度的垂直运动和热力学数据的雷达降水特征的原型陆地和海洋制度在刚果和中太平洋。然后，我们将我们的研究扩展到整个热带降雨测量使命（TRMM）域（35°S至35°N）的所有季节。在海洋上空，有一种趋势，即更强的大尺度上升运动，对流区的线性组织，以及有闪电的系统中更大的降水区。相比之下，在陆地上，闪电的特征往往更小，在更高的不稳定性环境中，大尺度垂直运动的差异很小。将我们的分析扩展到21个不同的地区，我们强调了季节性天气模式和水温梯度导致的分布是例外的发现，即海洋风暴与闪电往往比陆地风暴与闪电更大，更成熟。这些发现支持了一个假设，即大多数陆地风暴在其早期发展阶段具有足够强的上升气流来发展闪电，而海洋风暴需要大规模的上升和发展成为中尺度对流系统，然后对流尺度上升气流变得足够强，为闪电提供必要的条件。
This study expands upon the results of Bang and Zipser (2015), which demonstrated that oceanic precipitation features with lightning tended to be over 10 times larger and more stratiform than those over continents and suggested the hypothesis that some form of external forcing is acting in ways that lead to both larger features and stronger updrafts over tropical oceans. In this work, we evaluate this hypothesis by using reanalysis data to compare large‐scale vertical motion and thermodynamic data for radar precipitation features in archetypal land and ocean regimes in the Congo and Central Pacific. We then expand our study to the entire Tropical Rainfall Measuring Mission (TRMM) domain (35°S to 35°N) over all seasons. Over the ocean, there is a tendency for stronger large‐scale upward motion, linear organization of the convective region, and larger precipitation areas in systems with lightning. By comparison, over land, features with lightning tend to be smaller, in environments of higher instability, with little difference in large‐scale vertical motion. Expanding our analysis to 21 different regions, we highlight those in which seasonal synoptic patterns and water temperature gradients lead to distributions that are exceptions to the findings that ocean storms with lightning tend to be larger and more mature than land storms with lightning. These findings support the hypothesis that most land storms have updrafts sufficiently strong to develop lightning in their early growth stages, while ocean storms require large‐scale ascent and growth into mesoscale convective systems before convective scale updrafts become strong enough to provide the necessary conditions for lightning.