中国沙漠 ›› 2019, Vol. 39 ›› Issue (5): 21-28.DOI: 10.7522/j.issn.1000-694X.2018.00083

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韩广1, 尤莉2, 丁占良3   

  1. 1. 湖南师范大学 资源与环境科学学院, 湖南 长沙 410081;
    2. 内蒙古自治区气候中心, 内蒙古 呼和浩特 010051;
    3. 包头师范学院, 内蒙古 包头 014030
  • 收稿日期:2018-05-20 修回日期:2018-08-24 出版日期:2019-09-29 发布日期:2019-09-29
  • 作者简介:韩广(1964-),男,内蒙古包头人,教授,博士,主要从事风沙地貌学研究。
  • 基金资助:

A Brief Report on Secondary Flows in Interdune Corridor of Transverse Dunefield under Prevailing Wind Regimes

Han Guang1, You Li2, Ding Zhanliang3   

  1. 1. College of Resources and Environmental Sciences, Hunan Normal University, Changsha 410081, China;
    2. Inner Mongolia Climate Center, Hohhot 010051, China;
    3. Baotou Normal College, Baotou 014030, Lnner Mongolia, China
  • Received:2018-05-20 Revised:2018-08-24 Online:2019-09-29 Published:2019-09-29

摘要: 按照经典风沙物理学理论,横向沙丘下风侧由于气流分离会产生横轴涡旋,然而我们多年来在科尔沁沙地多处开展的沙丘群考察和观测中,经常观察到西北风天气条件下丘间走廊里发育着稳定的南向和西南向气流。为了解这种次生气流的基本特征,我们选择科尔沁沙地西部一片典型横向沙丘群,利用自动气象站进行了风季强风天气的风力观测。结果表明:(1)这种次生气流比较稳定,冬季基本以南风为主,春季以西南风为主;(2)风速会大幅度降低,幅度30%~50%;(3)冬季湍流强度明显小于春季,表明不同季节的局地大气层结状况影响丘间走廊的次生气流;(4)冬季的次生气流主要加深走廊底部,协助沙丘前移,而在春季除了加深走廊外,还促进了走廊的拓宽。

关键词: 科尔沁沙地, 横向沙丘群, 丘间走廊, 次生气流, 气流偏转

Abstract: In accordance with the classic theory of blown sand physics, horizontal roll vortex with transverse axis in the lee side of transverse dune could be expected because of flow separation. However, very stable S and SW winds can be frequently perceived and observed in interdune corridors (IDCs) under the circumstances of prevailing winds (NW) by means of field expeditions and observations in more dunefields in many years conducted in the Korqin Sandy Land, Northeast China, rather than imagined reverse flows in near surface boundary layers. In order to make sure the characteristics of the odd secondary flows in IDCs and their geomorphic importance, a stretch of typical transverse dunefield was selected in the western part of the Korqin Sandy Land, and wind observations were undertaken using 3 automatic weather stations during high wind events in windy seasons. The results show that:(1) the unique secondary flows in the IDCs are rather stable, which are mainly from the south in winter and the southwest in spring, which substantially deviate from local prevailing wind direction (NW); (2) although wind velocity is greatly reduced by 30%-50% due to the hollow effect as compared with the upwind crest, spasmodic sand drifts occur by instantaneous gusts; (3) the turbulence intensity is significantly larger than other positions (upwind crest and lower downwind stoss) in spring and that in winter, while stratification stability is less than that in winter, tending to be unstable; (4) the unique secondary flow could, to a large extent, dig down the bottom of IDCs and help advance dune in winter, whereas it could not only deepen the IDCs but also make IDCs broaden gradually in spring.

Key words: Korqin Sandy Land, transverse dunefield, interdune corridor, secondary flow, flow deflection