Local winds over the Lake Biwa basin

局地风是地形诱导的中尺度风系统。琵琶湖盆地位于本州岛最狭窄的地方，包含湖泊、平原、山脉和地峡，可以形成多种局地风。有研究指出，白天湖面和平原上空的湖风和山区上空的山谷风组合成从湖面向盆地边缘发散的气流，夜晚则与陆风和山风组合成相反方向的辐合气流。然而，通过详细考察风的日变化，我们注意到琵琶湖盆地北部开始向傍晚吹偏北风或偏东风。本文旨在阐明向傍晚方向发展的北风和东风的特征和成因。为此，我们于1985年和1986年6月在湖东北岸的Onoe进行了一次地面风的野外观测。此外，1985年8月2 ~ 4日观测了欧诺风场和温度的垂直分布。结果表明：1)在弱风的影响下，湖风向傍晚方向（约16 ~ 21 LST）吹向偏北风（NW-N）或偏东风（E-SE）；例如，在Ibukiyama气象站（海拔1377米）的18lst风速低于10米/秒左右。不管总的风向如何，偏北风都在发展。然而，东风经常与相对较强的东南一般性风一起发展；例如，在Ibukiyama气象站，18l13ea \: ST的风速大于约5米/秒。2)推断北风为从若狭湾地区进入琵琶湖盆地的海风。平均持续时间、平均风速、平均水平尺度为5 h （16 ~ 21 LST）、3.5 m/s。分别是63公里。3)推断东风为“大石风”，即地峡背风侧的强风，是经地峡改造而成的东南一般风。1985年8月2日至4日大石风在一野的持续时间、风速和垂直比例尺为14小时（17 ~ 7 LST）， 7 ~ 11 m/s。和300-500米。少

Local winds are terrain-induced mesoscale wind systems. Many kinds of local winds can develop in the Lake Biwa Basin, which is located in the narrowest part of Honshu Island and contains a lake, plains, mountains, and isthmuses.It has been pointed out that a lake breeze over the lake and plains and a valley wind over mountain areas are combined into divergent flow from the lake toward the edge of the basin in the daytime and that convergent flow combined with a land and a mountain wind develops in the opposite direction at night. However, examining diurnal variation in wind in detail, we notice that either a northerly or an easterly wind begins to blow toward evening in the northern part of the Lake Biwa Basin.This paper intends to clarify the features and orgin of both the northerly wind and the easterly wind that develop toward evening. For this purpose, we carried out field observations of a surface wind at Onoe on the northeast shore of the lake in su13EA\ : mmer 1985 and 1986. In … More addition, we observed vertical distributions of wind and temperature at Onoe on 2-4 August 1985.The results obtained are summarized as follows :1) Either a northerly wind (NW-N) or an easterly wind (E-SE) follows a lake breeze toward evening (about 16 to 21 LST) under the influence of a weak general wind ; for instance, wind speed at 18 LST at Ibukiyama Weather Station (1,377m above the sea13EA\ : level) is lower than about 10 m/s. The northerly wind develops regardless of the general wind direction. The easterly wind, however, develops frequently together with a relatively strong southeasterly general wind ; for instance, wind speed at 18 L13EA\ : ST at Ibukiyama Weather Station is greater than about 5 m/s.2) It is deduced that the northerly wind is a sea breeze entering from Wakasa Bay area into Lake Biwa Basin. Its mean duration time, mean wind speed, and mean horizontal scale are 5 hours (16 to 21 LST), 3.5 m/s. and 63 km, respectively.3) It is deduced that the easterly wind is "Dashikaze", a strong wind on the lee side of an isthmus, which is a southeasterly general wind modified by the isthmus. Duration time, wind speed, and vertical scale of Dashikaze at Onoe on 2-4 August 198513EA\ : are 14 hours (17 to 7 LST), 7-11 m/s. and 300-500 m, respectively. Less