Layers of insect echoes near a thunderstorm and implications for the interpretation of radar data in terms of airflow
Layers of insect echoes near a thunderstorm and implications for the interpretation of radar data in terms of airflow
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DOI：
10.1002/qj.800
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发表时间：
2011-04-01
影响因子：
8.9
通讯作者：
Norton, E. G.
中科院分区：
文献类型：
--
作者：
Browning, K. A.;Nicol, J. C.;Norton, E. G.
昆虫可以作为有用的雷达目标，用于确定大气的结构和运动学方面，但有时有必要更多地了解昆虫的行为，以便对气象解释有信心。位于英格兰南部奇尔博顿的各种气象雷达被用来调查在白天雷暴(中尺度对流系统)升高的高度在1.0至2.5公里之间探测到的多个浅层晴空回波层的性质。多波长和偏振测量被用来确认这些层在很大程度上是由于昆虫。这些层位于地表空气冷暗流顶部附近的潜在暖空气中。雷暴的对流上升气流是由冷暗流上方的空气提供的。一些昆虫层在空气中，注定会上升到风暴的对流上升气流中，还有一些在风暴来临时只能暂时上升的暗流空气中。起初，回声层随着气流上升，但随后，在风暴附近，回声强度减弱，尽管持续上升气流，主要是由于昆虫向下下降。在风暴到来之前，这些昆虫表现出强烈的倾向，它们倾向于待在各自的浅层中，但即使在接近风暴的地方，昆虫也仍然倾向于待在这些层中。因此，当它们跟随上升气流向风暴移动时，仍能辨认出一些层的存在，从而继续为雷暴附近的扰动气流提供有用的气象追踪。版权所有(C)2011皇家气象学会
Insects can serve as useful radar targets for determining aspects of the structure and kinematics of the atmosphere, but it is necessary sometimes to know more about insect behaviour in order to have confidence in the meteorological interpretations. A variety of meteorological radars situated at Chilbolton in southern England have been used to investigate the nature of multiple shallow clear-air echo layers that were detected at heights between 1.0 and 2.5 km in the vicinity of an elevated daytime thunderstorm (mesoscale convective system). Multi-wavelength and polarization measurements were used to confirm that the layers were due in large part to insects. The layers were within potentially warm air near the top of a cold undercurrent of surface air. The convective updraught of the thunderstorm was fed by air from just above the cold undercurrent. Some of the insect layers were within air destined to ascend into the storm's convective updraught and some were within undercurrent air that was forced to ascend only temporarily as the storm approached. Initially the layer echoes ascended with the airflow but then, close to the storm, their intensity weakened despite continuing updraughts, mainly as a result of the insects dropping downwards. Far ahead of the storm the insects showed a strong preference to remain within their individual shallow layers but, even close to the storm, where they started dropping out, insects still retained a preference to be within these layers. As a result, some layers continued to be discernible as they followed the ascending airflow towards the storm, thereby continuing to serve as useful meteorological tracers of the perturbed flow in the vicinity of the thunderstorm. Copyright (C) 2011 Royal Meteorological Society