巻号一覧
56 巻 (2000)
- 4 号 p. 243-
- 3 号 p. 163-
- 2 号 p. 93-
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56 巻, 4 号
選択された号の論文の8件中1～8を表示しています
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本條 毅, 高倉 直2000 年 56 巻 4 号 p. 243-251
発行日: 2000/12/10
公開日: 2010/02/25
ジャーナル フリーTo analyze the thermal effect of urban green areas, both measurement and simulation are necessary because it is impossible to get enough information from the limited numbers of measurements for such a broad area and time dependent phenomenon. In this study, a simulation model for analysis of the thermal effect of urban green areas was developed. As the temperature and surface roughness rapidly change near the urban green area, a turbulent simulation model which can simulate an abrupt change of diffusivity should be used for the simulation. The k-ε two equation model, one of the simulation methods for turbulent phenomena, was used in this study. The details of the scheme of the model and boundary conditions are explained.
For validation of the model, wind tunnel experiments and a measurement were compared with the result of the model.
The first set of wind tunnel experiments was a “pulse change of surface roughness”, where the surface roughness was changed from smooth to rough, then smooth again. The second case was a “pulse change of surface temperature”, where the surface temperature was changed from cool to hot, then back to cool.
The measurements of Katayama et al. (1987), a rare set of measurements that include the profile of wind velocity, temperature and humidity around a pond in an urban area, was used in this study to validate the model.
The results of the wind tunnel experiments and the measurements were compared with the calculations of the model and generally showed good agreement with the results of the simulations.
These results indicate that it is possible to use the simulation model for the analysis of the thermal effect of urban green areas.抄録全体を表示PDF形式でダウンロード (2103K) -
本條 毅, 高倉 直2000 年 56 巻 4 号 p. 253-260
発行日: 2000/12/10
公開日: 2010/02/25
ジャーナル フリーIn this study a two dimensional k-ε two equation model was used with the equations of temperature and normalized humidity to analyze the thermal effect of urban green areas. The relation between the scale of an urban green area and its influence and the relation between the interval of an urban green area and its influence were analyzed.
The relation of scale of a green area and its influence on the surrounding urban area is not clear, although many micrometeorological measurements of urban green areas have indicated that a large scale of green area influences a large urban area. The relation of the interval between green areas and its effect on the surrounding urban area is also unclear.
With respect to the relation between scale of urban green area and its influence, at the lowest simulated altitude of 2m sudden decreases in temperature and sudden increases in normalized humidity were observed at the upwind edge of green areas. In the adjacent urban area downwind of green areas, rapid increases in temperature and rapid decreases in normalized humidity were found. At the height of 6m, the changes were smoother.
From the distribution of temperature and normalized humidity, it is observed that a green area of larger scale influences a higher area. From the distribution of diffusivity, a large value was observed at the transition area from green area to urban area and this tendency was the same in the case of two green areas. On the relation of interval between green areas and its influence, low temperature and high humidity were observed in the urban area between two green areas. These results show that the two green areas with optimal interval affect the temperature and humidity near the ground effectively.抄録全体を表示PDF形式でダウンロード (917K) -
岡田 啓嗣, 浦野 慎一, 町村 尚, 堀口 郁夫2000 年 56 巻 4 号 p. 261-273
発行日: 2000/12/10
公開日: 2010/02/25
ジャーナル フリーA new method for estimation of regional evapotranspiration using satellite derived data is proposed. This method estimates daily regional evapotranspiration by combining high resolution LANDSAT-TM data, NOAA-AVHRR data of which the estimation accuracy of surface temperature is high, and wide-area representative radiosonde data.
As a case study, we caluculated the epavotranspiration for 2 districts in the Hokkaido Ishikari Plain using this method. Results are reasonable.
Though there is no direct method for verification, comparison with the Prisetley-Taylor method shows that the results correctly reflect the effects of land use. This result shows that this method is sensitive to land use and that it is a useful method for estimation of the regional evapotranspiration. The representativeness of the radiosonde data is questionable in the comparison between results from 2 regions.
Though there are some details to be improved, this could be a valuable method by which the regional evapotranspiration can be estimated using easily obtainable data.抄録全体を表示PDF形式でダウンロード (7317K) -
丸山 篤志, 大場 和彦, 黒瀬 義孝2000 年 56 巻 4 号 p. 275-282
発行日: 2000/12/10
公開日: 2010/02/25
ジャーナル フリーEffects of wind and salt water exposure on yield of paddy rice were investigated by using a wind tunnel and sprinkler. Rice plants were exposed to seventy-two different treatment combinations of salt concentration, wind duration, cultivar (Hinohikari and Yumehikari) and growth stage. Photosynthesis on the day after treatment was decreased by wind and salt water exposure. Percentage and weight of filled grain at harvesting, and consequently yield were also decreased by wind and salt water exposure. Yield reduction in Hinohikari was more than Yumehikari due to a difference in wind tolerance between the two cultivars. The amount of adhered salt on the rice plants grown outdoors decreased after treatment due to rainfall, but the yield reduction was the same as cropping under cover (no rainfall) after treatment.
The amount of adhered salt on the panicle after treatment was directly proportional to salt concentration in the sprayed water. Using the proportional coefficient, relationships between the amount of adhered salt on the panicle and relative yield of paddy rice were determined. Relative yield of paddy rice decreased from 1.0 to 0.2 when treated at heading time and 8-12 days after heading as the amount of adhered salt increased from 0 to 6mg per panicle. In the same way, relative yield decreased from 1.0 to 0.7 when treated at 21-25 days after heading. These relationships will be useful in predicting the yield of paddy rice affected by strong wind and salt from the sea caused by typhoons.抄録全体を表示PDF形式でダウンロード (1114K) -
地上で測定した表面温度と日平均気温の関係について王 秀峰, 川角 妙子, 谷 宏2000 年 56 巻 4 号 p. 283-294
発行日: 2000/12/10
公開日: 2010/02/25
ジャーナル フリーSupplemental analyses using Landsat data were performed to study the possibility of estimating daily mean air temperature using surface temperature derived from satellite IR data. It is recognized that daily mean air temperature can be estimated relatively accurately from surface temperature. Also, studies of the basic relation between daily mean air temperature and surface temperature measured on the ground (over forest and soybean fields) were performed. The results are as follows: (1)When there is comparatively small variation in vegetation density (e.g. forest), the correlation coefficients between daily mean air temperature and the temperature of surfaces receiving sunshine are large. (2)The correlation tends to be better in the morning and evening, and worse at noon. (3)When there is comparatively large variation in vegetation density (e.g. soybean fields), the correlation coefficient between daily mean air temperature and surface temperature for clear days is comparatively large, but the correlations are small for fine days. (4)RMSE over forest or soybean fields for both clear days and fine days are large in spite of a large correlation coefficient. (5)The correlation coefficients and RMSE can be improved by multi-regression analysis between two-hour surface temperature and daily mean air temperature. (6)The mean time at which surface temperature was closest to daily mean air temperature was 8-9 a.m. in the morning and 4-6 p.m. in the evening for May to October over a forest.抄録全体を表示PDF形式でダウンロード (1590K) -
五十嵐 大造, 植松 斉, 三浦 泰昌2000 年 56 巻 4 号 p. 295-301
発行日: 2000/12/10
公開日: 2010/02/25
ジャーナル フリーWe developed new materials to prevent cold injury in cabbage. The materials were made of spunbonded fabric of polyester fibers combinated with a net of polyethylene flat checker-patterned yarn. The mesh of the checker-patterned yarn was about 7mm squares. Polyester non-woven fabric was pasted in stripes on polyethylene flat checker-patterned yarn. The materials have good air ventilation capacity in the frosted and dew condensed condition, and high conduction capacity of sensible heat from air into the cover. Polyester non-woven fabric part of the materials was placed just above heads of cabbages on the ridges in the field, and the polyethylene yarn portion was placed just above the trough.
Leaf temperature under the material, which is a combination of about 70% area of spunbonded fabric with checker-pattern yarn, was highest during all clear nights irrespective of wind speed. The materials significantly decreased incidence of head rot caused by cold injury in open field compare to control.抄録全体を表示PDF形式でダウンロード (2980K) -
辻 多聞, 早川 誠而, 神近 牧男, 大槻 恭一, 高山 成2000 年 56 巻 4 号 p. 303-310
発行日: 2000/12/10
公開日: 2010/02/25
ジャーナル フリーMost meteorologists have reported that higher order closure models are better than the K-theory model for estimation of environment in the canopy, but solving a higher order closure model requires boundary conditions for turbulence, which is measured directly by a sonic anemometer. However, sonic anemometers are expensive so few scientists in agriculture use high order closure models. In the present research, estimation of the wind profile in and above a sorghum canopy was carried out by use of a 2nd order closure model with mean wind velocity at a single height above the canopy. Comparison between the observed and calculated profiles indicated that the former was well represented by the latter in general. This indicates that the present calculation scheme can be used for estimation of wind profiles in the canopy without observation of the turbulence. It revealed that most large scale turbulence was generated at the upper part of a sorghum canopy during the heading stage, and that measuring the plant area density should be a more important canopy meteorological observation than the leaf area index during the heading stage, since the non-leaf portion of plant area is not negligible.抄録全体を表示PDF形式でダウンロード (1001K) -
冷気の流れ鳥谷 均, 小林 哲夫, 塚本 修, 黒瀬 義孝, 五十嵐 大造, 柏木 良明, 桑形 恒男, 谷 宏, 森 牧人, 脇水 健次2000 年 56 巻 4 号 p. 311-316
発行日: 2000/12/10
公開日: 2010/02/25
ジャーナル フリーPDF形式でダウンロード (941K)
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