Electrically Active Tropical Cyclone Diurnal Pulses in the Atlantic Basin
Electrically Active Tropical Cyclone Diurnal Pulses in the Atlantic Basin
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DOI：
10.1175/mwr-d-19-0129.1
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发表时间：
2019-09
影响因子：
3.2
通讯作者：
Sarah D. Ditchek;Kristen Corbosiero;R. Fovell;J. Molinari
中科院分区：
文献类型：
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作者：
Sarah D. Ditchek;Kristen Corbosiero;R. Fovell;J. Molinari
虽然最近对大西洋盆地热带气旋日冷暖脉冲的频率和结构进行了探索，但日脉冲与深对流的关联频率仍未得到解答。这里，GridSat-B1, 6小时红外亮度温差场与全球闪电定位网络（WWLLN）数据相补充，以回答这个问题。通过确定每个脉冲内闪电密度、面积覆盖范围和寿命的临界阈值，客观地定义了电活性、长寿命的冷却和加热脉冲。有闪电的脉冲占61%，持续电活动脉冲（≥9 h， ACT）占38%，准电活动脉冲（3-6 h， QUASI）占23%。电非活性脉冲（<3小时，INACT）发生39%的时间。与INACT脉冲日相比，ACT脉冲日有更多的脉冲位于剪切权（雨带外闪电活动的首选象限），并且与更有利的环境条件相关。冷却脉冲更可能发生在低切变环境中，而变暖脉冲更可能发生在高切变环境中。最后，虽然ACT和INACT冷却脉冲和ACT增温脉冲的传播速度确实支持了近期重力波和热带飑线对日脉冲的解释，但INACT增温脉冲没有支持，应该进一步研究。
While the frequency and structure of Atlantic basin tropical cyclone diurnal cooling and warming pulses have recently been explored, how often diurnal pulses are associated with deep convection was left unanswered. Here, storm-relative, GridSat-B1, 6-h IR brightness temperature difference fields were supplemented with World Wide Lightning Location Network (WWLLN) data to answer that question. Electrically active, long-lived cooling and warming pulses were defined objectively by determining critical thresholds for the lightning flash density, areal coverage, and longevity within each pulse. Pulses with lightning occurred 61% of the time, with persistently electrically active pulses (≥9 h, ACT) occurring on 38% of pulse days and quasi–electrically active pulses (3–6 h, QUASI) occurring on 23% of pulse days. Electrically inactive pulses (<3 h, INACT) occurred 39% of the time. ACT pulse days had more pulses located right-of-shear, the preferred quadrant for outer-rainband lightning activity, and were associated with more favorable environmental conditions than INACT pulse days. Cooling pulses were more likely to occur in lower-shear environments while warming pulses were more likely to occur in high-shear environments. Finally, while the propagation speeds of ACT and INACT cooling pulses and ACT warming pulses did lend support to the recent gravity wave and tropical squall-line explanations of diurnal pulses, the INACT warming pulses did not and should be studied further.