巻号一覧
54 巻 (1998)
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54 巻, 1 号
選択された号の論文の11件中1～11を表示しています
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張 暁川, 青野 靖之, 文字 信貴1998 年 54 巻 1 号 p. 1-11
発行日: 1998/03/15
公開日: 2010/02/25
ジャーナル フリー地球観測衛星ランドサットのTMデータを用いて夏季 (1990年8月6日) と冬季 (1988年12月6日) の日中における大阪市市街地の地表面熱収支の分布を推定した。顕熱・潜熱フラックスの推定には各々のバルク輸送式を用い, 必要なデータを内挿し画素ごとに計算した。解析に要するデータのうち, 土地被覆, 地表面アルベド, 表面温度, NDVIの分布については, TMデータから直接計算した。その他, 気温などについては, 気象台のデータを併用して推定した。潜熱フラックスの計算に必要な蒸発散効率βについては, 植生のない市街地に見たてた地点での実地観測結果によって求めた。
都心及び住宅密集地では, 市内でも顕熱フラックスは高く, 潜熱フラックスはほとんどない結果となった。一方, 特に夏季, 市内の都市公園では, 平均194Wm-2, また, 植生の多い住宅地でも, 77Wm-2程度の潜熱フラックスが評価された。こうした熱フラックスの土地被覆による違いは冬季よりも夏季で顕著だった。これは, 表面温度の市内における分布パターン, そして潜熱フラックスに限ればNDVIから見た植生量, 活性が評価結果に影響したことによる。抄録全体を表示PDF形式でダウンロード (6271K) -
黒瀬 義孝, 深石 一夫, 林 陽生, 大場 和彦1998 年 54 巻 1 号 p. 13-21
発行日: 1998/03/15
公開日: 2010/02/25
ジャーナル フリーThe Ohzu Basin is located in the north western part of Shikoku Island as is shown in Fig. 1. As in other basins in Japan, basin fog appears frequently from autumn to winter. In order to make clear the climatological characteristics of basin fog at the Ohzu Basin, Ehime prefecture, and understand its role as an element of agro-climatological resources, observations were carried out from Sep. 8, 1995 to Feb. 5, 1996. The sites were located at bottom of the basin and on mountainside faced to the center of the basin. The latter site was situated above the upper surface of the fog layer which appears typically in the Ohzu Basin. Spatial distribution of the fog were also analyzed using the LANDSAT images provided on Dec. 5, 1985 and Dec. 13, 1988.
The results obtained in this study were summarized as follows:
(1) The total number of fog day reached 46 days during the present observation period mentioned above. In the most frequent period, fog occurred at the ratio of one day to two day in October and November.
(2) Dispersion time of the fog changed seasonally accordance with a shift of time of sunrise, and the fog has lasted 4 hours or more after the sunrise under dominant foggy conditions.
(3) The meteorological characteristics of foggy day were shown as follow, attenuated of solar radiation in the morning, decreased of radiative cooling in nighttime, and low temperature until fog dissipate.
(4) Several % of monthly total solar radiation was shaded by fog layer at the basin bottom site. Total time of saturation condition indicated by R.H.=100% on foggy days became 21 hours at the site of mountain slope. At the basin bottom site, it reached 493 hours during the period of the observation.
(5) Upper surface of the fog layer was limited to a height about 300m above the sea level, and distributed horizontally along lower part of the Hiji River. The maximum height was affected by the surrounding topography.
(6) In the Ohzu Basin, hamlets on the mountain slope distributed zonally above the fog layer. This indicates that the fog has a remarkable influence on human life of mountainous region. On the other hand, the chinese cabbage-producing district was formed in the foggy area. Utilizing this foggy climate of the basin, high quality chinese cabbage with soft leave are produced in the basin bottom.抄録全体を表示PDF形式でダウンロード (1473K) -
鈴木 純1998 年 54 巻 1 号 p. 23-29
発行日: 1998/03/15
公開日: 2010/02/25
ジャーナル フリーFilm mulch is being used in many farm lands because it improves the environment for cultivation by suppressing water evaporation from soil surface, maintaining a mild soil moisture condition, and maintaining the soil temperature higher than the bare soil surface, in addition to protecting against pests and diseases. Crop cultivation in cool high lands (such as the Shinshu Plateau) can be made possible with the introduction of film mulch. However, as the direct infiltration in the root zone are lower in fields where film mulch is used than in bare soil fields, and this raises fears that droughts would be exacerbated.
Experimental comparisons of the soil moisture condition and flow between mulched bed and furrow space using the soil moisture measurement technique at many positions and many depths were carried out in the fall of 1995 in field planted with Chinese cabbage (Brassica pekinensis Rupr.), and in the spring of 1996 in field planted with cabbage (Brassica oleracea L.). The results are summarized as follows;
(1) The shallow topsoil of the mulched beds had less soil moisture than furrow space and bare soil even after light rains at low soil moisture condition. The sowed areas (hold of the mulch film) in mulched beds, however, were moisture than the surrouding of sowed area. But one or two days after rainfall, soil moisture condition in mulched bed and furrow space were almost same.
(2) As the crops grew, the soil moisture became lower than furrow space due to the water uptake by the crops' root system. In the soil layer below the root zone, i.e. at a depth of more than 0.3m, soil moisture is moved from the furrow space to the mulched bed by the gradient of soil moisture potential caused by the soil moisture uptake by the root system.
These results propose that occasional plowing in the furrow space causes an increase in the infiltration rate of rain water, and facilitates the movement of moisture from the furrow space to root zone of the mulched beds.抄録全体を表示PDF形式でダウンロード (867K) -
近藤 純正1998 年 54 巻 1 号 p. 31-41
発行日: 1998/03/15
公開日: 2010/02/25
ジャーナル フリーUsing the micrometeorological data (Harazono et al., 1995) obtained at the Arctic Tundra at Barrow, Alaska in the summer of 1993, preliminary analysis was made and the daily and seasonal variations of evapotranspiration, radiation, ground heat flux, and surface temperature were estimated.
On fine days, the value of sensible and latent heat fluxes increased to maximums of approximately 200 to 300Wm-2 during the midday, then decreased to about zero (sensible heat flux) and -30 to -80Wm-2 (latent heat flux) around the time of the sun's northing. It is found that the surface evaporation efficiency β, having a mean value of 0.3, decreases with increasing wind speed. Using a model calculation, it is obtained that the mean value of evapotranspiration at the IBP site for 71 days, from 16 July to 25 August, is 0.89mmd-1 which is 40% of the potential evaporation (defined by Kondo and Xu, 1997a).抄録全体を表示PDF形式でダウンロード (1428K) -
本條 毅1998 年 54 巻 1 号 p. 43-46
発行日: 1998/03/15
公開日: 2010/02/25
ジャーナル フリーA neural network was used to estimate climatic data from topographical factors in areas where observed climatic data do not exist. The neural network with a back propagation algorithm was used as a method of nonlinear multiple regression which has advantages over conventional linear regression, especially when the relation between climatic data and topographical factors is nonlinear.
As an example, four meteorological data (normal value of daily mean temperature, daily maximum temperature, daily minimum temperature and daily mean wind velocity) were estimated for 74 observation points around Shizuoka Prefecture from input data of 13 geological factors such as altitude, latitude, longitude, slope angles etc. The network consists of 3 layers which have 13 units in the input layer, 4 units in the output layer and 26 units in an intermediate layer. A linear multiple regression analysis was also used to compare the characteristics of the methods.
In all cases, the neural network showed smaller errors than the multiple regression. In the case of wind velocity where the data was rather scattered, the neural network showed its advantage clearly. Although the use of the neural network is accompanied by theoretical ambiguity, the result shows precise estimation is possible by neural network.抄録全体を表示PDF形式でダウンロード (530K) -
渡辺 力, 大谷 義一1998 年 54 巻 1 号 p. 47-54
発行日: 1998/03/15
公開日: 2010/02/25
ジャーナル フリーAs a part of an estimation method of the heat storage rate within forest biomass, two simple schemes are presented for a calculation of the heat conduction into a cylindrical material. One is a modified version of the so-called Force-Restore method, and the other is a method based on the digital filter. Both methods are tested against analytical solutions of the heat-conduction equation for given diurnal cycles of the cylinder-surface temperature. The modified Force-Restore method gives acceptable results when the diurnal change in the surface temperature is not very different from a sinusoidal wave of 1-day cycle. The digital filter method can produce correct results for any patterns of diurnal cycles, if the time series of the surface temperature is given for more than 1-day period centered by the evaluation time of heat storage. Both method can be applied to an entire forest, if stems of the forest are classified into adequate classes in terms of their radii.抄録全体を表示PDF形式でダウンロード (912K) -
井上 君夫, 阿部 博史1998 年 54 巻 1 号 p. 55-61
発行日: 1998/03/15
公開日: 2010/02/25
ジャーナル フリーTo study meteorological characteristics of cool foggy easterly (Yamase), by which rice production in the Tohoku region was frequently damaged, we measured temperature of the fog layer resulted from Yamase, using infrared thermal indicator and meteorological satellite (HIMAWARI). These temperature data were compared with wet-bulb and dry-bulb temperatures obtained by a ventilated psychrometer.
Generally, the temperature of fog droplets estimated from infrared thermal indicator was higher than the wet-bulb temperature by about 0∼1°C. This result indicates clearly that fog droplets were cooled by evaporation on the droplet surface.
Under the conditions that the fog layer is homogeneous in liquid water content and fog droplet size distribution, the height of the fog layer can be estimated by the observation of visibility and relative solar radiation flux.抄録全体を表示PDF形式でダウンロード (3053K) -
山田 一茂, 広田 知良, 城岡 竜一1998 年 54 巻 1 号 p. 63-69
発行日: 1998/03/15
公開日: 2010/02/25
ジャーナル フリーReturn periods of continuous snow cover duration at the 24 observation points in Hokkaido were investigated using the Weibull distribution method. The mean value of continuous snow cover duration was in the region of 120 days to 170 days. The differences between the mean value and the value of return periods of continuous snow cover duration at 3, 5, 10 and 30 year intervals were about 7, 14, 21 and 30 days, respectively. The differences between the mean value and the first date of the return periods of continuous snow cover duration at 3, 5, 10 and 30 year intervals were about 6, 10, 15 and 23 days. In the same, the last date of continuous snow cover duration at 3, 5, 10 and 30 year intervals were about 4, 8, 10 and 14 days, respectively. The variation of the return periods of last date was small compared with the first date.抄録全体を表示PDF形式でダウンロード (865K) -
近藤 純正1998 年 54 巻 1 号 p. 71-75
発行日: 1998/03/15
公開日: 2010/02/25
ジャーナル フリーPDF形式でダウンロード (638K) -
耕地気象改善研究部会1998 年 54 巻 1 号 p. 76-78
発行日: 1998/03/15
公開日: 2010/02/25
ジャーナル フリーPDF形式でダウンロード (376K) -
1998 年 54 巻 1 号 p. 120
発行日: 1998年
公開日: 2010/02/25
ジャーナル フリーPDF形式でダウンロード (807K)
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