Low-level convergence lines over northeastern Australia. Part I: The north Australian cloud line
Low-level convergence lines over northeastern Australia. Part I: The north Australian cloud line
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澳大利亚东北部上空的低层辐合线。
DOI：
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
J. Hacker
中科院分区：
文献类型：
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作者：
Robert Goler;M. Reeder;Roger K. Smith;H. Richter;S. Arnup;T. Keenan;P. May;J. Hacker
本文描述了在澳大利亚北部北方卡奔塔利亚海湾地区形成的北澳大利亚干季云线（NINES）的观测结果以及引起这些云线的海风环流。这些观测是在2002年海湾航线实验（GLEX）期间进行的，包括一架装有仪器的研究飞机进行的测量。观测结果与二维云尺度模式的数值模拟结果进行了比较。特别强调的是放在东海岸和西海岸海风之间的相互作用附近的约克角半岛西海岸。由于半岛上空的低空东风天气流，海风是高度不对称的。西海岸的海风具有明显的前缘，因为相反的气流限制了它向内陆的渗透，使它靠近冷空气的来源。相比之下，东海岸海风是不好定义的，因为它是由东风气流的帮助下，并成为高度修改白天对流混合，因为它穿过半岛。观测和数值模拟结果都表明，在清晨，成熟的NACL在重力流的前缘形成。数值模拟结果表明，这股重力流是由约克角半岛向西移动的陆风引起的。陆风前缘的辐合伴随着上升，当足够强时，就会产生云。观测表明，北大西洋环流的衰减与低层辐合减弱和上升减弱有关。
Observations of dry-season north Australian cloud lines (NACLs) that form in the Gulf of Carpentaria region of northern Australia and the sea-breeze circulations that initiate them are described. The observations were made during the 2002 Gulf Lines Experiment (GLEX) and include measurements made by an instrumented research aircraft. The observations are compared with numerical simulations made from a two-dimensional cloud-scale model. Particular emphasis is placed on the interaction between the east coast and west coast sea breezes near the west coast of Cape York Peninsula. The sea breezes are highly asymmetric due to the low-level easterly synoptic flow over the peninsula. The west coast sea breeze is well defined with a sharp leading edge since the opposing flow limits its inland penetration, keeping it close to its source of cold air. In contrast, the east coast sea breeze is poorly defined since it is aided by the easterly flow and becomes highly modified by daytime convective mixing as it crosses over the peninsula. Both the observations and the numerical model show that, in the early morning hours, the mature NACL forms at the leading edge of a gravity current. The numerical model simulations show that this gravity current arises as a westward-moving land breeze from Cape York Peninsula. Convergence at the leading edge of this land breeze is accompanied by ascent, which when strong enough produces cloud. Observations show that the decay of the NACL is associated with a decline in the low-level convergence and a weakening of the ascent.