| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1986: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1985: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Research Abstract |
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
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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
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