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Volume 66, Issue 2
Displaying 1-7 of 7 articles from this issue
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Full Papers
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Fei WANG, Haruhiko YAMAMOTO, Yasuomi IBARAKI, Kiyoshi IWAYA, Hisashi Y ...2010 Volume 66 Issue 2 Pages 81-90
Published: March 10, 2010
Released on J-STAGE: July 27, 2010
JOURNAL FREE ACCESSLeaf necrosis and branch dieback of the newly transplanted dogwood trees triggered by the prolonged dried period and sudden rise in temperature was observed in the study. Attached and detached leaves and branches were detected by a thermo infrared camera under the conditions including outdoor environment, indoor window sunlight and incandescent light. Different thermo imaging characteristics were found between necrotic part and living part of both leaves and branches. The detection of the outdoor attached leaves indicated higher temperatures at the necrotic part than living part, seemingly being attributable to the high water content and transpiration cooling effect in the living part. However, the detached leaves change their temperatures at necrotic part faster than that of living part, largely due to the lower water content. Significantly amplified variation of imaging temperature between the live and dead parts of detached leaves and branches during the heating and cooling process indicated that there was potential to detect the leaf necrosis and branch dieback by viewing the temperature fluctuation of Kousa dogwood (Cornus kousa) trees with thermography.View full abstractDownload PDF (1555K) -
Yasushi ISHIGOOKA, Tsuneo KUWAGATA, Shinkichi GOTO, Hitoshi TORITANI, ...2010 Volume 66 Issue 2 Pages 91-101
Published: March 10, 2010
Released on J-STAGE: July 27, 2010
JOURNAL FREE ACCESSThis paper developed a simple hydrological model that not only simulates large-scale hydrological process, but also provides the fractional saturated area within each unit cell of the model; aiming to evaluate surface water conditions and rice productivity in rainfed lowland paddy in Northeast Thailand. The concept of TOPMODEL which can represent spatial heterogeneity of soil moisture and groundwater level on sub-grid scale through the effect of topographic features was used for reproducing the variation of saturated area fraction. The model was implemented during from 1977 to 2006 using gridded daily meteorological data which were created by spatially interpolating the observed data. Simulation results confirmed that large saturated areas occurred in areas where accumulated precipitation was high and water tended to concentrate in topographically low areas such as valleys and basins, which is a relevant feature of spatial water condition. The time series of saturated area calculated from the model was compared with the observed rice-planted area in Northeast Thailand. We found that the saturated area in mid-August was highly correlated with rice-planted area, implying that rice-planted area could be estimated appropriately from the simulated water-saturated area at this time. This result also suggests that transplanting of rice in this region must be finished by the end of August, because the photoperiod-sensitive rice cultivars used will be immature at the time of flowering and heading if planted later than AugustView full abstractDownload PDF (1091K)
Short Papers
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Takako KOIKE, Masato SHINODA, Yuki MORINAGA, Purevjav GOMBOLUUDEV2010 Volume 66 Issue 2 Pages 103-110
Published: March 10, 2010
Released on J-STAGE: July 27, 2010
JOURNAL FREE ACCESSEurasian snow cover in spring has followed a decreasing trend since the mid-1960s, but winter conditions remain unknown because of a lack of data. To address this issue with a regional focus on the eastern part of Eurasia, we conducted an observational study of winter temperature, precipitation, and snow depth in Mongolia and the associated atmospheric circulation. We used the meteorological data at 21 representative Mongolian weather stations for four winter months (November to February) from 1960 through 2007. Time series analysis was applied to three indices: standardized deviations from the mean for this 4-month period averaged over the 21 stations in Mongolia for snow depth, precipitation, and temperature. This analysis revealed a significant multi-decadal trend in temperature, but not in snow depth.
During the 1960s and 1970s deep-snow winters coincided with extreme cold. However, beginning in the winter of 1992-1993, a new type of deep-snow winter with warmer conditions has occurred in some years. Moreover, a synoptic analysis demonstrated that a trough at the 500-hPa level that is usually climatologically located east of Mongolia extended westward to Mongolia during the cold-deep-snow winters. This indicates that enhanced cold surges from the north to Mongolia led to the historically typical deep snow conditions. On the other hand, the warm-deep-snow winters were characterized by a weakened trough, weakened cold surges, and concurrently intensified moisture transport from the west into Mongolia. The new circulation pattern observed here shows that warm winters, which may become more frequent in the future, still have the potential to cause deep snow in Mongolia.View full abstractDownload PDF (1012K) -
Yohei NAKAI, Fumiki HOSOI, Kenji OMASA2010 Volume 66 Issue 2 Pages 111-116
Published: March 10, 2010
Released on J-STAGE: July 27, 2010
JOURNAL FREE ACCESSIn this study, we confirmed the utility of airborne LiDAR and passive optical remote sensing techniques for estimating the standing tree volume of two coniferous trees, 28 Japanese red pine and 13 Japanese cedar trees respectively. Airborne 3-D LiDAR data and aerial photographs provided the respective height and crown area for each of the selected trees. Subsequently, we examined the relationships between 1) LiDAR-derived tree height and Field-based stem volume and 2) the crown area obtained from aerial photograph and the field-based stem volume. In addition, we made a multiplicative equation composed of both tree height and crown area to predict the stem volume, and examined its accuracy by comparing the predicted standing tree volume with the field-based volume. Consequently, stronger correlations were observed between the LiDAR-derived tree height and stem volume in both species, while those between the crown area obtained from aerial photographs and the stem volume were weaker in both species. At the multiplicative equation, R2 and SE of the stem volume were 0.90 and 0.046 m3 for the Japanese red pine, and 0.83 and 0.025 m3 for the Japanese cedar respectively, which represented a better result than using tree height or crown area alone, especially for the Japanese cedar. This shows the effectiveness of the combination of LiDAR and passive optical sensors in estimating the standing tree volume.View full abstractDownload PDF (711K) -
Makito MORI, Hisashi YOSHIKOSHI, Tetsuo KOBAYASHI, Weizhen WANG, Daisu ...2010 Volume 66 Issue 2 Pages 117-124
Published: March 10, 2010
Released on J-STAGE: July 27, 2010
JOURNAL FREE ACCESSIn order to measure the evaporation from a field in the upper Yellow River valley in winter, which is essential for a proper understanding of the water budget of the “autumn irrigation”, by a simple profile method using routine measurements of wind speed and direction made at one height and those of air temperature and humidity at two heights, an intensive observation was conducted to determine the aerodynamic roughness length (z0) of the field bare of vegetation.
Measurements of turbulent fluxes of sensible heat (H) and momentum (τ) were made in the field with a sonic anemometer-thermometer for two days in late April of 2008, when the field was not frozen but without vegetation. These measurements were substituted into the expression of the Obukhov length, and equations for H and τ that were derived based on Monin-Obukhov similarity theory, and three kinds of estimates of z0 were obtained. The estimates of z0 made using the H equation were smaller than those made using theτequations for neutral and non-neutral stratification and had a great dependence on the wind direction.
Daily evaporation calculated from the equation for the turbulent flux of water vapor, which was also derived based on Monin-Obukhov similarity theory, using the z0 estimated using the H equation and an iteration technique were 1.1∼1.3 times as large as the measurements made by the Bowen ratio method. Based on this conclusion, the evaporation from this field in winter was analyzed, which will be shown in the following paper.View full abstractDownload PDF (770K)
Short Papers (in Japanese)
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Ryotaro ITO, Teruaki SHIMAZU, Itsuo TANAKA2010 Volume 66 Issue 2 Pages 125-130
Published: March 10, 2010
Released on J-STAGE: July 27, 2010
JOURNAL FREE ACCESSA new method for measuring the gas exchange rates of plant tissue culture vessels was developed using the same assumption used in previous models; namely, the air inside the vessel is completely mixed. In this new method, the gas exchange rate was evaluated from the mole fraction of water vapor inside and outside the vessels and the evaporation rate of water inside the vessel measured by economical measuring devices. To examine the mixing state of the air inside the vessel, humidity distributions in the vertical direction of two vessels of different diameters were measured. The humidity distribution in the 10 cm diameter vessel was uniform; however, the humidity distribution in the 2.5 cm diameter vessel was not. This result suggested that the assumption of complete mixing of air was valid only for larger diameter vessels; hence methods to measure gas exchange based on this assumption are limited to larger diameter vessels. Subsequently, the gas exchange rates of vessels 10 cm in diameter were measured using our new method and three existing methods. The results suggest that the values obtained by this method agree well with those obtained by measuring the change in CO2 gas concentrations inside vessels as a function of time using gas chromatography, if the gas exchange results from diffusion caused by a concentration difference between the inside and outside of the vessel.View full abstractDownload PDF (834K)
Research Notes (in Japanese)
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Toshichika IIZUMI, Motoki NISHIMORI, Yasushi ISHIGOOKA, Masayuki YOKOZ ...2010 Volume 66 Issue 2 Pages 131-143
Published: March 10, 2010
Released on J-STAGE: July 27, 2010
Advance online publication: March 26, 2010JOURNAL FREE ACCESSThis article outlined the statistical downscaling methods (SDMs) and how they derive climatic inputs for the impact models (referred to as the climate change scenario) from the outputs of dynamic global/regional climate models. To help select an appropriate method from various SDMs, the authors categorizes the SDMs into four functional categories, i.e. (1) temporal disaggregation, (2) spatial disaggregation, (3) estimation of elements not directly supplied by climate models, and (4) bias correction, and referred to some anecdotal studies of each category. In addition, a practical example of the generation of climate change scenario at a site was demonstrated to provide a concrete image for researchers trying to use SDMs. This introductory guide will help select an appropriate SDM to fill the gap between accessible climate model outputs and the requirements of impact studies.View full abstractDownload PDF (927K)
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