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Volume 58, Issue 3
Displaying 1-5 of 5 articles from this issue
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Paul Ibrahim MATLI, Masatoshi AOKI, You OZAWA, Yoshiaki HIDESHIMA, Hir ...2002 Volume 58 Issue 3 Pages 115-122
Published: September 10, 2002
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSThis study characterizes the response of canopy CO2 flux (FCO2) and leaf stomatal conductance (gs) of potato fields in the Tokachi plain in Hokkaido to changing meteorological factors, e.g. air temperature and vapor pressure deficit (VPDa). Measurements were made of FCO2 and meteorological conditions in August 1998. Also, upper crown sunlit leaf stomatal conductance response to air temperature and vapor pressure deficit (VPDc) inside the cuvette of a porometer were measured simultaneously on a number of days to determine their effects on gs. Results showed that at moderate summer temperatures in Hokkaido and free soil water stress, VPDa was the more significant factor affecting the depression in FCO2 in the potato crop. The depression is characterized by the difference of FCO2 from a curve tracing the maximum FCO2 response to light. A similar VPDc effect was also observed in gs. Above an optimum temperature of 25°C, stomatal closure and high depressions in photosynthetic CO2 exchange occurred even at low vapor pressure deficit. This fact implies a decrease in photosynthetic CO2 fixation and crop growth in cool temperate-climate regions under further global climate warming.View full abstractDownload PDF (986K) -
Yasuhiro ISHIGAMI, Yo SHIMIZU, Kenji OMASA2002 Volume 58 Issue 3 Pages 123-133
Published: September 10, 2002
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSIn this paper, potential distribution of natural vegetation in Japan is estimated using a modified model of BIOME3, which is a process-based biogeographical model. The estimation was performed using 1×1km2 mesh data of monthly climate (temperature, precipitation, solar radiation), soil class (modified from the data attached in BIOME3) and minimum temperature for the year, calculated from the AMeDAS data. The type of plant vegetation distribution in the model was modified to that of ordinary classification in Japan. In this model, NPP contributes to determine the vegetation type. Comparison with NPP calculated by the Chikugo model showed that this model could simulated NPP distribution in Japan successfully. The hitting ratio for estimated the vegetation type was similar to that estimated by other statistical models (Tsunekawa et al., 1996; Nogami, 1994) in comparison with vegetation survey data (Ministry of the Environment) and potential natural vegetation map data (Miyawaki et al., 1994).View full abstractDownload PDF (2420K) -
Dai MATSUSHIMA2002 Volume 58 Issue 3 Pages 135-145
Published: September 10, 2002
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSUsing ground-based and airborne observation, as well as numerical simulation, we confirmed that the thermal-infrared temperature (TIT) of a rice canopy surface with row orientation changes with azimuth viewing angle. The TIT of the direction parallel to row orientation is 1-4°C higher than that of the other directions. The TIT differences occur during the daytime, and for a leaf area index (LAI) around 0.5-3 because the field of view of an infrared thermometer viewing a direction parallel to the rows contains much more of the water surface under the rice canopy than the plant surface of the canopy. The temperature of the water surface between rows is much higher than that of the plant surface, because the intense incoming solar radiation near noon is not absorbed by the canopy and so warms the water efficiently. Matsushima and Kondo (1997) developed a radiation transfer model for TIT of a rice canopy surface, and confirmed a nadir viewing angle dependence of TIT of according to leaf area index. Based on the above model, a model of a rice canopy with row orientation was developed to investigate the TIT variation with azimuth viewing angle. The model design employs the ratio of the apparent areas of the plant surface and the underground water surface, which change with the azimuth and nadir viewing angles, and reproduces the observation well. These results indicate that the main cause of the TIT difference is the ratio of the apparent areas of the plant surface and the water surface when the temperature of the water surface is much higher than that of the plant surface. The TIT in a westerly direction exceeds that of the other directions shortly after sunrise because the solar elevation is low and the azimuth of the sun is around east. This is because the plant surface temperature exceeds that of the water surface, which is opposite the near noon cases. On the scale of a satellite grid, a simple numerical experiment demonstrated that the TIT difference of azimuth viewing angle increases as the row orientation in the subgrid scale becomes nearly uniform.View full abstractDownload PDF (3445K) -
Yoshitaka KUROSE, Kazuhiko OHBA, Atsushi MARUYAMA, Taichi MAKI2002 Volume 58 Issue 3 Pages 147-156
Published: September 10, 2002
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSA mobile observation method of wind using a sonic anemometer and GPS was developed. Wind direction and speed are estimated every second by subtracting the wind vector due to the movement of the automobile, measured by GPS, from the wind vector on the automobile, measured by sonic anemometer. The sonic anemometer should be firmly attached at 40cm behind the front of the automobile at 1.9m height from the ground and the mounting arm should not shake vertically. The survey error of the GPS on the mobile observation of wind can be neglected. The measurement accuracy of the wind speed and wind direction in this observation method were 1.5m/s and 11°, respectively. It is possible to measure wind direction and speed in a tail wind, head wind, or crosswind for the car, moving at any speed. To clarify the characteristics of “Aso Oroshi”, mobile observation of wind was carried out in the valley of Aso somma. It was shown that mobile observation method of wind was effective for observation of the local wind.View full abstractDownload PDF (4714K) -
Toshiaki MUKAI2002 Volume 58 Issue 3 Pages 157-164
Published: September 10, 2002
Released on J-STAGE: February 25, 2010
JOURNAL FREE ACCESSDownload PDF (800K)
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