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Volume 48, Issue 2
Displaying 1-11 of 11 articles from this issue
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Hirakazu SEKI, Tomoaki KOMORI1992 Volume 48 Issue 2 Pages 129-138
Published: September 10, 1992
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSTo get a theoretical basis for the dynamic characteristics off a soil warming process, an approximate solution of soil temperature at the unsteady state was derived analytically. The calculated results of soil temperature and intensity of heat source by warm water were in good agreement with the calculated results by the numerical solution. The time reaching the steady state estimated here agreed well with the empirical result reported previously. The transfer function between the intensity of heat source as an input and the soil temperature as a response, and the transfer functions between the several disturbances and the response were evaluated from the approximate analytical solution. These transfer functions would be useful to investigate the dynamic behavior and an appropriate control system of the soil warming process theoretically.View full abstractDownload PDF (1004K) -
Takashi HIRANO, Makoto KIYOTA, Kazuo SEKI, Ichiro AIGA1992 Volume 48 Issue 2 Pages 139-145
Published: September 10, 1992
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSThis study was conducted to infer the effects of volcanic ash accumulating on a leaf surface on its photosynthesis. Particle size distribution and shading ratio were measured on 2 kinds of ash from Mt. Sakurajima (white and black) and 4 kinds from Mt. Unzen-Fugendake. Reflected spectral radiant flux density, temperature and Stomatal conductance of cucumber leaves covered with those ashes were also measured.
Particle size distribution of ashes were different each other, Particle (<3μm) contents of them were 6 to 13%. Shading ratios were 8 to 20% at 5gm-2 of ash load. The ash with smaller particle size had bigger shading ratio. Integrated radiant flux density (280-2500nm) of reflection from leaves covered with ashes from Mt. Sakurajima (black and white) and Mt. Unzen-Fugendake at 50gm-2 were 65, 53 and 106% to control leaves, respectively. Temperature of leaves covered with these ashes at 50gm-2 increased by 2.4, 2.6 and 1.2°C, respectively, at a solar radiation of 876 W m-2. The ash from Mt. Unzen-Fugendake, with the smallest particle size, decrease stomatal conductance significantly even after it was washed out from the leaf surface. These results suggest that the volcanic ash with dark color and small particle size reduces photosynthesis through shading, increasing temperature and plugging stomata.View full abstractDownload PDF (2575K) -
Yoshinobu HARAZONO, Makoto KIYOTA, Kazutoshi YABUKI1992 Volume 48 Issue 2 Pages 147-155
Published: September 10, 1992
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSSeasonal change of heat budget was measured from June to December in 1985 at both a natural forest and a lawn in Kibougaoka Park, Shiga prefecture, in order to make clear the differences in micrometeorological and hydrological characteristics. A analyzing equipment based on the Bowen ratio method was developed originally for the present study in order to obtain each heat budget component instantaneously.
Air temperature over the lawn site increased rapidly than that over the forest site on a summer midday. Humidity above and inside the forest was slightly higher than that of the lawn.
On a summer clear day, about 4% of net radiation (Rn) was stored up in the space of the forest as latent heat, sensible heat, and conductive heat to vegetation. In the afternoon, a portion of sensible and vegetation heat had changed in storage state to latent heat, which shows that there was a day period circultation of moisture inside the forest space. These characteristics of heat storage and circulation of moisture is one of mechanisms which make a moderate microclimate of forest during summer.
Daily evapotranspiration (ET) at the lawn site decreased with the length of clear days, and was always lower than that at the forest, while ET of the forest didn't decrease. When the accumulated solar radiation (RS) was over sbout 90MJ/m2, ET at the lawn decreased rapidly.
Yearly accumulation of ET was evaluated 968mm for the forest and 605mm for the lawm, by the heat budget analysis using the measured data.
Discussions of heat budget and run-off analysis showed that the soil water capacity of the lawn was about 18mm, while it was more than 83mm for the forest. The low soil water capacity of the lawn makes the surface run-off to increase during heavy rain and to decrease ET rapidly during long term clear days.
The differences in micrometeorological and hydrological characteristics mentioned above seemed to appear when a forest is developed to a lawn. Therefore a careful assessment should be carried out before development of a forest.View full abstractDownload PDF (3217K) -
[in Japanese]1992 Volume 48 Issue 2 Pages 156
Published: September 10, 1992
Released on J-STAGE: February 25, 2010
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[in Japanese]1992 Volume 48 Issue 2 Pages 156a
Published: September 10, 1992
Released on J-STAGE: February 25, 2010
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Taichi MAKI, Borong PAN, Pizhen HUANG, Guorong YAN1992 Volume 48 Issue 2 Pages 157-164
Published: September 10, 1992
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSAt the arid land of Turfan in northwestern China, the effect of tamarisk (Tamarix L.) wind-break forest was investigated in summer and spring.
(1) The effects on the decrease of wind speed and prevention of wind erosion were large based on tamarisk canopy of high density stems with small leaves. In the leeward of the windbreak, the wind turbulence and the wind region of eddy were small and the function of sand filtration was effective. The resistances or tolerances against drought, heat, cold and salt were great. Therefore, tamarisk tree is excellent as a windbreak forest at the arid land of northwestern China.
(2) It was obtained the measuring result that air temperature increased unnecessarily at the windward and leeward close to the windbreak at the daytime in summer, considering as an unfavorable climatic condition for a crop cultivation, however, the value of temperature increasing is alleviated to a certain degree owing to the shade by windbreak and latent heat by transpiration from the tree leaves.
(3) As a favorable meteorological condition for a crop growing, the phenomena of temperature decreasing by the radiation cooling was observed in the region of wind decreasing at the nighttime in summer.
(4) The observation effect on the increase of humidity or water vapor by transpiration from the windbreak leaves was recognized for meteorological improvement of dry farming, particularly during weak wind.
(5) In spring, the positive effects of decreasing wind, increasing temperature, increasing humidity, decreasing wind erosion, and sand filtration were large, but the negative effects for crop cultivation were small.View full abstractDownload PDF (973K) -
Haruhiko YAMAMOTO1992 Volume 48 Issue 2 Pages 165-169
Published: September 10, 1992
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSRemoto sensing method with a portable spectroradiometer was applied to estimation of panicle water content in rice canopies.
1) The most effective index of spectral reflectance for estimating the panicle water content (PWC %) in rice canopies was R750nm/R650nm, the ration of the spectral reflectivity at 750nm and 650nm, respectively. The regression equations were “PWC=12.11+4.48 (R750nm/R650nm)” for Reiho, and “PWC=14.09+3.68(R750nm/R650nm)” for Nishihomare. The correlation coefficient were 0.980 and 0.978, respectively.
2) The observed and the estimated values of PWC were distributed on the ratio line of one to one. The correlation coefficients were 0.978 in both rice canopies for Reiho and Nishihomare. The standard error of prediction were 2.99 and 3.47, respectively.
3) Relationships between LAI and reflectivity ratio (R750nm/R650nm) in rice canopies for Reiho and Nishihomare were significantly positive. The correlation coefficients were 0.992 and 0.991 for Reiho and Nishihomare at the reproductive stage.View full abstractDownload PDF (549K) -
Haruhiko YAMAMOTO, Shigenori FURUYA1992 Volume 48 Issue 2 Pages 171-174
Published: September 10, 1992
Released on J-STAGE: February 25, 2010
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Haruhiko YAMAMOTO, Yoshinori SUZUKI, Seiji HAYAKAWA, Yasumitsu KISHIDA1992 Volume 48 Issue 2 Pages 175-180
Published: September 10, 1992
Released on J-STAGE: February 25, 2010
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Kenji Omasa1992 Volume 48 Issue 2 Pages 181-186
Published: September 10, 1992
Released on J-STAGE: February 25, 2010
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Kenji Bokura1992 Volume 48 Issue 2 Pages 187-191
Published: September 10, 1992
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSDownload PDF (4190K)
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