First observations of elevated ducts associated with intermittent turbulence in the stable boundary layer over Bosten Lake, China
First observations of elevated ducts associated with intermittent turbulence in the stable boundary layer over Bosten Lake, China
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DOI：
10.1002/2016jd024793
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发表时间：
2016-10
期刊：
影响因子：
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通讯作者：
Zhenge Sun;Huiqiong Ning;Shihui Song;D. Yan
中科院分区：
文献类型：
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作者：
Zhenge Sun;Huiqiong Ning;Shihui Song;D. Yan
夜间辐射冷却是大气波导形成的主要驱动力。在这一大气过程中，间歇性湍流对管道的影响很少被研究。在本文中，我们报告了2014年8月清晨在中国博斯腾湖上空观测到的两个令人困惑的管道事件，当时稳定边界层（SBL）仍然存在，通过使用系留的高分辨率GPS无线电探空仪。在气球上升过程中观察到具有强烈湿度倒置的高架导管，但在几分钟后气球下降时进行的观察中不存在。这种现象最初被假设是由于湍流运动在SBL，和湍流事件和雷达管道之间的连接进行了检查的统计索普方法。从上升剖面中检测到湍流斑，但从下降剖面中检测不到湍流斑。详细讨论了管道形成和消除的可能原因。在SBL和平流由于气流来自湖泊的湍流输送的水分是管道形成的最可能的原因。在一种情况下，在低空急流顶部的开尔文-亥姆霍兹巨浪中通过湍流混合向下输送水分导致管道消除。在另一种情况下，来自湖泊的异重流的通过可能导致了管道的消失。很少有研究试图将间歇性湍流与雷达管道联系起来，因此，这项工作代表了一个开创性的研究湍流事件和大气管道之间的连接在SBL。
Nocturnal radiative cooling is a main driver for atmospheric duct formation. Within this atmospheric process, the impacts of intermittent turbulence on ducting have seldom been studied. In this paper, we reported two confusing ducting events observed in the early morning in August 2014 over Bosten Lake, China, when a stable boundary layer (SBL) still survived, by using tethered high‐resolution GPS radiosondes. Elevated ducts with strong humidity inversions were observed during the balloon ascents but were absent during observations made upon the balloon descents several minutes later. This phenomenon was initially hypothesized to be attributable to turbulence motions in the SBL, and the connection between the turbulence event and the radar duct was examined by the statistical Thorpe method. Turbulence patches were detected from the ascent profiles but not from the descent profiles. The possible reasons for the duct formation and elimination were discussed in detail. The turbulent transport of moisture in the SBL and the advection due to airflows coming from the lake are the most probable reasons for duct formation. In one case, the downward transport of moisture by turbulence mixing within a Kelvin‐Helmholtz billow at the top of the low‐level jet resulted in duct elimination. In another case, the passage of density currents originating from the lake may have caused the elimination of the duct. Few studies have attempted to associate intermittent turbulence with radar ducts; thus, this work represents a pioneering study into the connection between turbulent events and atmospheric ducts in a SBL.