巻号一覧
56 巻 (2000)
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- 2 号 p. 93-
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56 巻, 2 号
選択された号の論文の5件中1～5を表示しています
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野田 美香, 小林 哲夫, 薦田 廣章, 武政 剛弘, 森 牧人, 園田 裕虎2000 年 56 巻 2 号 p. 93-99
発行日: 2000/06/10
公開日: 2010/02/25
ジャーナル フリーIntensive observations of surface wind, longwave radiation and vertical profile of air temperature including surface temperature were made on a grass-covered slope of Mt. Kuju, Oita, Japan, during the period 21-27 August 1998, from which we obtained the following results.
The cold-air-drainage layer (CADL), which is defined as the surface air layer on a slope with a potential temperature deficit, is made up of two sublayers, a radiation cooling underlayer (RCL) and a mixing cooling upper layer (MCL). Although the potential temperature deficit in the RCL is created by radiation cooling, that in the MCL is conjectured to be mainly caused by mixing of the cold air produced in the RCL with the air above, because the deficit increases even while the potential temperature keeps rising in the MCL. Owing to the shear flow instability, which can arise at the interface between the CADL and the overlying air where large shear occurs, the thickness of the MCL changes drastically, while the thickness of the RCL remains almost constant in time. When instability develops, an increase of potential temperature occurs in the MCL and often even in the RCL for a short time, due to the entrainment of the air with higher potential temperature from above.抄録全体を表示PDF形式でダウンロード (813K) -
田中 逸夫, 石井 征亜2000 年 56 巻 2 号 p. 101-109
発行日: 2000/06/10
公開日: 2010/02/25
ジャーナル フリーFor a long time in the protected cultivation of fruit vegetables, there has been a practice of circulating warm water in pipes buried in soil ridges to control soil temperature in the root zone. Recently this technique has been applied to soil cooling in the cultivation of strawberry or ornamental plants such as Alstroemeria L. However there is little research on temperature distribution in the soil during the temperature control process or on the effects of ridge geometry, physical properties of the soil, climate conditions, pipe arrangement, water temperature and other factors on soil temperature. The authors have conducted numerical simulations of temperature distribution in ridge soil using the finite difference method to clarify the problems mentioned above and to optimize the system. In this paper, numerical solutions were conducted to explore the effects of free-convection heat transfer between the ridge surface and ambient air and the absorption of direct solar radiation at ridge surface, assuming that the effect of moisture in ridge soil on heat transfer is negligible. Results are shown for the cases of soil cooling during the high temperature period and soil heating during the low temperature period in Japan. In addition, the effects of physical properties of the soil, ambient air temperature, direct solar radiation absorbed at ridge surface, and the surface temperature of pipes on soil temperature distribution were examined.
In conclusion, (1) the effect of solar radiation absorbed at the south side of ridges with E-W orientation on soil temperature is slight during the high temperature period, but significant during the low temperature period because of low solar altitude; (2) the effects of soil physical properties and ambient air temperature are small for both processes; (3) the effect of the surface temperature of pipes is comparatively large in both processes.抄録全体を表示PDF形式でダウンロード (1031K) -
千葉 晃2000 年 56 巻 2 号 p. 111-121
発行日: 2000/06/10
公開日: 2010/02/25
ジャーナル フリーIn this paper, the author has tried to clarify the spatial distribution of extreme monthly temperature minima (T min-ex) in Hokkaido, the northern part of Japan and the synoptic pattern on days when over 25% of AMeDAS observatories in Hokkaido recorded Tmin (Lower Temperature Days in Hokkaido=LTD). The lowest January temperature in Hokkaido was observed in Etanbetsu near Asahikawa (-37.1°C). The lowest June temperature in this district was observed in Kawayu (-3.7°C) in the eastern part of Hokkaido. In July, 42% of the AMeDAS observatories in Hokkaido recorded temperatures below 0°C. In winter, colder regions are located in the inland areas: Nayoro Basin, Furano Basin and Rikubetsu region. In summer, colder temperatures tend to be found in the eastern part of Hokkaido. The reasons were shown to be as follows: In winter, the synoptic characteristics of LTD are such that cold air moves southward from the North Pole, after a cyclone at 500hPa geopotential height has passed over Sakhalin. Wind velocity on LTD in Wakkanai is 5.8ms-1 less than the mean. In summer season, the Okhotsk High was enhanced. The temperature at 850hPa in Nemuro was reduced due to the effect of the Okhotsk High. The condition of colder temperature in this area is different from the one in the Tohoku district, and it is clear that Hokkaido district is an independent district in view of the meso and synoptic scale climatology.抄録全体を表示PDF形式でダウンロード (1352K) -
黒瀬 義孝, 唐 立松, 大場 和彦, 丸山 篤志, 真木 太一2000 年 56 巻 2 号 p. 123-128
発行日: 2000/06/10
公開日: 2010/02/25
ジャーナル フリーTurpan is an oasis in the arid land of northwest China. August through September is the harvesting time for grapes, which occupy 30% of the total agricultural output in Turpan. The grapes are often damaged by the strong winds that occur during this season. To identify the characteristics of the strong winds in Turpan, an investigation was carried out from August 27 to September 12, 1997.
When the difference in air temperature between Turpan and Urumqi sites was greater than 15°C, strong winds with a velocity of more than 5m/s blew in Turpan. Winds at this velocity particularly blew from 11 AM to 7 PM (XST).
The most frequent directions of the winds with a velocity more than 5m/s were W or WSW. Hence, as a countermeasure to prevent wind damage, it is suggested that a wide shelter belt be placed on the west side of the oasis.
It is hypothesized that the strong wind at Turpan is related to cold air advection.抄録全体を表示PDF形式でダウンロード (3200K) -
板東 恭子2000 年 56 巻 2 号 p. 129-136
発行日: 2000/06/10
公開日: 2010/02/25
ジャーナル フリーPDF形式でダウンロード (718K)
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