本実験は, 砂丘地におけるフィルムマルチと植被 (模型) による地温効果を, 微気象的に明らかにすることを目的とした。
フィルムは黒色ポリエチレンフィルム (厚さ0.03mm) と透明ポリエチレンフィルム (0.03mm) を使用し, 1983年の5月から8月にかけて砂丘地研究圃場の熱収支, 地温, 土壌水分等の微気象観測を行った。
1) マルチ区の熱収支の日量を, 純放射に対する各項の割合で示すと, 黒色マルチでは純放射量のほとんどが顕・潜熱伝達量で占められ (96%), 地中伝導熱量はわずか4%であった。他方, 透明マルチでは顕・潜熱伝達量の占める割合が75%で, 黒色マルチより減少し, それだけ地中伝導熱量の割合が増えた (25%)。これら熱収支の傾向は砂丘地の場合も, 一般の畑地の場合と大差はない。
2) 無マルチの状態において日中 (最高地温) は, 植被により地温は著しく低下した。夜間 (最低地温) になると, 一般の畑地において植被による保温効果が大きいのに対し, 砂丘地では効果がみられなかった。
3) 黒色マルチでは, 植穴と植被による日中 (最高地温, 5cm深さ) の地温低下はいずれも大きいが, 透明ポリ区では植穴による影響は小さい代わりに, 植被による地温低下は顕著であった。夜間 (最低地温) になると, 黒色マルチでは植穴と植被の有無にかかわらず保温効果はみられ, その効果は地温が高い時期ほど大きく, その傾向は一般の畑地とは逆であった。透明マルチでも保温効果はみられたが, 植穴が無い状態で植被がある場合, 効果は急減した。
4) 黒色マルチと透明マルチによる地温効果 (5cm深さ) を, 一般の気象要素との関連でみた結果, 植穴の有無に関係なく, 黒色ポリ区の最高地温では日照時間が, 透明マルチでは降雨量がそれぞれの地温に大きく影響を及ぼしている。
5) 砂丘地におけるマルチの地温効果 (5cm深さ) を黒色マルチ, 透明マルチ, 無マルチの3区間の地温 (最高, 最低, 平均, 較差) の高低関係の出現頻度でみた結果, それらのうちの最多の出現頻度のものは20.8%から72.7%に及んで, 一般の畑地の場合よりもその割合は低く, このことからマルチによる地温効果は砂丘地ではあまり一定しないことが示された。

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we have been making clear that the diffusion resistance of leaf-boundary layer changes with the attack angle of leaf to flow φ, through model experiments with flat plates and measurements of transpiration rate on sweet potato leaves. In this paper, effects of φ on the dry matter production DMP, the net photosynthetic rate P_o, and the transpiration rate Tr of cucumber leaves are investigated.
DMP under each φ condition is measured as the dry matter increase of leaves after 7 hours' irradiance in a growth chamber. The effect of φ on DMP is examined by comparing DMP under various conditions with that under φ=0° condition, i.e. the enlargement of DMP. The φ conditions both from 10° to 30° and from -10° to -30° give positive effect on the DMP of the leaves. The maximum enlargement of 38% is obtained under the φ=20° condition.
The enlargement of P_o, which is similarily defined in the case of DMP, changes with φ, as same as those of DMP. The maximum value 9.9% of the enlargement of P_o is obtained under the φ=20° condition. Transpiration rate Tr also changes with φ, in the same fashion as P_o. The effects of φ conditions on the enlargements of DMP, P_o, and Tr are agree fairly well with those estimated by the previous model experiments. These results confirm experimentally that the diffusion resistance of leaf boundary layer significantly affects the photosynthesis, transpiration, and hence the plant growth.
As a consequence, followings are revealed from present results and those in the previous model experiments. The diffusion resistance of leaf-boundary layer takes smallest value at an attack angle between 20° and 30°, when a single leaf, whose aspect ratio is ranging from 0.3 to 2.5, is affected in a laminar flow with wind velocity up to 3m/s.

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In order to make clear the effects of decreasing wind speed and the flow rectification and the horizontal variations of turbulent characteristics by a windbreak net (height 0.50m, length 50m and net density 50%), the observation was carried out at the micrometeorological observation grassland with two sets of three-dimensional ultrasonic anemometer, in the case that the wind direction was varied against the net.
The main results were obtained as follows:
(1) With increase in the incident angle (IA) of wind against the net, the horizontal distribution of relative wind speed downwind of the net indicated a pattern of V character type, and the recovery distance of wind speed in the oblique winds became shorter than that in the orthogonal incident winds in terms of orthogonal direction from the net. On the other hand, the wind recovery distance is constant in terms of the oblique distance in parallel with the wind direction.
(2) Although the minimum of relative wind speed and its appearance point with the increment of the incident angle seem to increase and to move toward the net, respectively, those changing rates were small. The reasons could be that the decrease in wind speed by an apparent increase of the net density due to the oblique incidence, was counterbalanced by fluttering of the net and the effects of wind blowing with parallel to the net and jumping over the net, or the observation error.
(3) The maximum of the downward wind decreased with the increasing incident wind angle, and the appearance point of the maximum moved toward the net, but its distance from the net was same in terms of the distance in the direction of wind.
(4) With the diminution of the attack angle, the maximum of turbulent intensity increased at the windward region and decreased in the leeward. The maximum point moved toward the net, although the distance from the net measured in the wind direction was independent of the incident angle.
(5) The maxima and minima of the skewness, kurtosis, turbulent diffusion coefficient and scale of the smallest eddy became nearer to the net with the increment of the incident angle, nevertheless, the distance measured in the direction of wind was not affected.
(6) The maxima of energy dissipation rate and normalized peak frequency of the power spectral density increased in the windward from the net and decreased in the leeward with the decrease of the attack angle in an analogous manner to the turbulent intensity. The recovery distance of turbulent characteristics after the net was reduced, but it was not dependent on the incident wind angle, when the distance was measured in the direction of wind.

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本システムの運転試験から得られた結果をまとめると以下のようになる。
(1) ヒートポンプの冷房時成績係数 (COP_r) は, 凝縮器側流水温度と蒸発器側流水温度との差温の増加に伴い3.5～2.6まで変動した (Fig. 1)。したがって, この値は, (1)ヒートポンプ凝縮器の冷却水に井戸水を使う, (2)凝縮器側および蒸発器側の流水量を増加する, (3)温室の冷房設定気温を満足できる範囲で蒸発器側水温をできるだけ高くするよう制御する, ことによって高めることが可能である。
(2) 本システムの冷房時成績係数 (COP_rs) は1.4～2.0であった (Table 3)。この値を高あるためには, COP_rを高める必要がある。
(3) 冷熱水槽を備えたシステムでは, ヒートポンプ容量を小さくできる利点があるが, 冷熱水槽での熱損失が生じるので, 冷熱水槽の断熱を完全にし, COP_rs低下を抑制することが重要である。
(4) 温室内に設置された水対空気熱交換器の吸熱量のうち, 13～45%は結露 (除湿) による潜熱負荷であった (Table 4)。また, 潜熱負荷の38～90%を隙間換気潜熱負荷が占めた。したがって, 温室の気密性を高めることで潜熱負荷を抑制できる。
(5) 除湿量は, 温室内空気の露点温度と水対空気熱交換器の流水温度との差温が小さい程減少するので (Fig. 3), 温室の冷房設定室温を維持できる範囲で温室への送水温度をできるだけ高くすることによって潜熱負荷を減少できる。このことは, COP_rを高めるためにも有効である。
(6) 冷房温室の相対湿度は, 対照温室のそれと同程度かまたは数%低かった (Fig. 4)。
(7) 冷風冷房方式である本システムの冷房運転時の温室内気温分布は, かなり均一であった。

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The height distribution and time variations of airborne rice pollens were observed at six heights within and above a rice canopy, using Durham samplers. The observation period was the flowering seasons of rice plants from the latter part of August to the first part of September, in 1984. The mean height of rice plants was about 75cm. Fluctuations of winds and vibrations of a rice plant were observed, using a sonic anemometer and a strain gauge. The relationship between airborne pollens and fluctuations of winds and plant vibrations were reported in the present paper. The results are summarized as follows.
(1) A lot of airborne pollens were sampled throughout the observation period. The values of airborne pollens observed in the upper part of canopy were frequently more than 1, 000counts/cm²hr. They were more than fifty times of those observed in the last part of the flowering season in 1983 (Maitani and Seo, 1985).
(2) The most of airborne pollens were released during about 2 hours near 11hr-12hr, corresponding to the flowering characteristics of the rice plant and the increase of a wind velocity and a vibration of a rice plant, through a midday sea breeze.
(3) The pollen number showed a maximum within the plant canopy and decreased with increasing heights above a plant canopy. The value at 170cm height was about 20-30% of that within plant canopy.
(4) The maximum number of pollens falling down to the ground was about 3, 000counts/cm² hr. The total number during the observation period was more than 20, 000counts/cm². This was about 70% of an estimation of the rice pollen products per unit area.
The improvement of sampling techniques, the accurate information of flowering characteristics of plants and the minute micrometeorological observations in crop fields will be requisite for further discussions on the influence of the atmosphere on airborne pollens within and above plant canopies.

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A climatic method for determining the global radiation incident on an inclined plane under real weather conditions was developed to evaluate radiation characteristics in districts with complicated terrain. The developed method was used to make clear the radiation regime in the Aso caldera.
The global radiation (S_{t, s}) incident on an inclined plane is composed of the following three components.
S_{t, s}=S_{b, s}+S_{d, s}+S_{r, s}
where S_{b, s}, S_{d, s} and S_{r, s} are the direct, sky diffuse and ground-reflected diffuse radiation incidents on the slope. The respective components in the right hand side of the above equation can be approximated by Eqs. (2), (3) and (4). In addition to solar radiation, net radiation on an inclined plane was also calculated from Eq. (5) by considering the long-wave radiation exchange among slope, atmosphere and slope-facing ground, and compared with that on a horizontal plane.
The preliminary analyses of the data of radiation components obtained in the special projects for radiation climate of Japan show that the monthly average diurnal change in radiation fluxes can be approximated by
S_{b, H}(t)=[S_{b, H}](A₀+A₁cost+A₂cos²t)
S_{d, H}(t)=[S_{d, H}](B₀+B₁cost+B₂cos²t)
where [S_{b, H}] and [S_{d, H}] denote, respectively, monthly average daily amounts of direct and sky diffuse radiations on a horizontal plane, A₀, A₁, A₂, B₀, B₁ and B₂ are the empirical constants relating to the monthly average sun altitude at solar noon. Fig. 1 indicates the comparison of measured and calculated hourly amounts of direct and sky diffuse radiations. The measured points are well distributed on the diurnal curves obtained by this method, giving a strong support to the validity and applicability of the calculation method mentioned above.
In order to investigate the dependence of the ratio S_{t, s}/S_{t, H} and the ratio R_{n, s}/R_{n, H} on the angle of inclination and orientation of the slope, the annual amounts of respective components on inclined surfaces were evaluated by the newly developed method. Some of five curves are presented in Fig. 2 together with the dependence of annual average surface temperature on the angle of inclination and orientation of a slope. It is evident from Fig. 2 that the change in net radiation with the angles of inclination and azimuth of slopes is in weaker degree compared with that for global solar radiation on slopes. This appears to be due to the increase in effective long-wave radiation on the slope with higher surface temperature. Fig. 3 indicates effects of the inclination and azimuth of a slope on the annual change on monthly average GSR(=S_{t, s}/S_{t, H}), NRR(=R_{n, s}/R_{n, H}) and TD(=T_{s, s}-T_{s, H}, T_{s, s} and T_{s, H} show the surface temperatures on inclined and horizontal surfaces). From Fig. 3, we can observe that at large inclination angle and during summer months, GSR for the south-facing slope is less than 1.0 and that GSR for its slope is larger than 1.0 during winter months. A quite opposite annual change in monthly average GSR is observed for the north-facing slopes. On the other hand, GSR for east- or west-facing slope was found to be nearly constant throughout year, independently of the inclination angle of slopes. Although annual change in NRR is as same as GSR, the range of NRR is smaller than that of GSR.

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Experiments for extraction and accumulation of the heat generated in composting process were performed using a buried-tube-type heat exchanger and an accumulator. Water was circulated between the heat exchanger and the accumulator as a heat transfer medium. The following results were obtained.
1) The compost bed maintained its average temperature at 50°C or higher for about 60 days of the whole period of composting reaction in the first stage (72 days). During this high temperature period, the experiments for heat extraction and accumulation were made by circulating water intermittently or continuously. In the case of the intermittent water-circulation, the water temperature of the accumulator attained to a designed temperature, 30°C, when the room temperature was higher than 10°C, but never did the water temperature when the room temperature was lower than 5°C. With the continuous water-circulation, the water temperature at the steady state condition was in average of 16 through 24°C.
2) The apparent rate of heat generation in the compost bed was 200 through 300kcal/m³hr during an early period of about 40 days, which included a turning of the compost bed. The composting reaction was therefore not likely to be inhibited by extracting heat from the bed during the period of intermittent water-circulation experiments.
3) The efficiency of heat extraction was 17-26% in the intermittent water-circulation, while the efficiency of heat collection at the steady state condition was 27-32% in the continuous water-circulation. These efficiencies could increase by the well designed arrangement and the increased number of the buried tubes.
4) It is necessary to investigate the method for deciding the optimum scale or size of the container for the compost and the heat accumulator on the basis of the theoretical analysis of heat transfer processes.

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