We examined the characteristics of nocturnal low-level wind maximum (NLWM) at a topographically complex site in Boseong, South Korea. The study site is located on the southern coast of the Korean peninsula. Although the area within a few kilometers of the site is flat, it is surrounded by mountains and faces the ocean on the southeast side. We defined NLWM as the lowest wind speed maximum within the lowest 300 m of the atmosphere that is at least 2 m s−1 greater than the next minimum above during nighttime. Climatology of NLWMs was derived from a 4-year half-hourly database of wind profiles (11 levels) obtained from a 300-m tower. The half-hourly data showed that NLWM occurred on approximately 18% of the nights. NLWMs were typically situated at 40 m above the ground. Half of the NLWMs had a speed of 3–5 m s−1, and its direction was predominantly west-northwesterly regardless of the height or season. The occurrence of NLWM showed a maximum in October and a minimum in July. The cause of NLWM at this site was discussed. It was found that the NLWM at this site occurred in the presence of valley wind forcing on nights with weak northerly geostrophic winds at 850 hPa.

中文翻译：

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宝城一个地形复杂的沿海地区夜间低层风最大值的气候学

我们在韩国宝城的一个地形复杂的地点检查了夜间低层风最大值 (NLWM) 的特征。研究地点位于朝鲜半岛南部海岸。场地周围几公里范围内虽然地势平坦，但东南侧群山环抱，面朝大海。我们将 NLWM 定义为大气最低 300 m 内的最低风速最大值，在夜间比上面的下一个最小值大至少 2 ms-1。NLWM 的气候学来自从 300 米塔获得的风廓线（11 个级别）的 4 年半小时数据库。每半小时的数据显示 NLWM 发生在大约 18% 的夜晚。NLWM 通常位于离地面 40 m 处。一半的 NLWM 的速度为 3-5 ms−1，无论高度或季节如何，它的方向主要是西北偏西。NLWM的发生在10月最大，7月最小。讨论了该站点 NLWM 的原因。发现该站点的 NLWM 发生在存在山谷风强迫的夜间，在 850 hPa 为微弱的偏北地转风。