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Volume 65, Issue 1
Displaying 1-12 of 12 articles from this issue
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Full Papers
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Hiroki IWATA, Jun ASANUMA, Yoshikazu OHTANI, Yasuko MIZOGUCHI, Yukio Y ...2009 Volume 65 Issue 1 Pages 1-9
Published: March 10, 2009
Released on J-STAGE: April 22, 2009
JOURNAL FREE ACCESSThis study investigated the vertical length scales of transporting eddies calculated from multi-level turbulence measurement in the unstable roughness sublayer over a flat pine forest by using the surface renewal method as a description of heat transport. It was observed that the vertical integral scale exhibited a increasing tendency with thermal instability, whereas the shear length scale of Raupach et al. (1996, Boundary-Layer Meteorol., 78, 351-382) was relatively stability-insensitive. These length scales were used as the height of the transporting eddies in the surface renewal method in order to examine the relevance of the length scales to the turbulent transfer. Comparisons with the eddy covariance measurement showed that variation in the performances of the surface renewal method with the different length scales was most noticeable under unstable conditions; the use of the vertical integral scale leads to better accuracy in flux computation. The results indicated the validity of the vertical integral scale as a direct measure of the transporting eddy scale in the surface renewal context. It was also suggested that the shear length scale may have limitations in terms of describing the vertical scale of the eddies in the unstable roughness sublayer when the buoyancy has a considerable effect on turbulence production.View full abstractDownload PDF (719K) -
Shohei SHIBATA2009 Volume 65 Issue 1 Pages 11-17
Published: March 10, 2009
Released on J-STAGE: April 22, 2009
JOURNAL FREE ACCESSField observations were conducted to evaluate the amount of energy that could potentially be generated using a micro-wind generator in a mountainous area of Shikoku. The relationship between the electricity generated by the micro-wind generator and the wind conditions on the slopes was determined based on observations conducted from September 2005 to July 2006. The average daily power output from the generator was 199 Wh from an average horizontal wind speed of 2.43 m/s, which is not considered satisfactory for practical use in mountainous areas. Several aspects associated with the use of such generators therefore require attention before they can be employed in the field.
Compared to upslope winds, the increased power generation from downslope winds was thought to be caused by the higher temporal fluctuation of wind speeds. Even the average wind velocity is same level, the increased frequency of fluctuating wind conditions results in increased power generation because the micro-wind generator is very sensitive to changes in the wind, and because the wind energy is theoretically linear to the cube of wind speed.View full abstractDownload PDF (962K) -
Daisuke YASUTAKE, Kota HIDAKA, Yuki SAGO, Takuya ARAKI, Masaharu KITAN ...2009 Volume 65 Issue 1 Pages 19-26
Published: March 10, 2009
Released on J-STAGE: April 22, 2009
JOURNAL FREE ACCESSIn order to analyze absorption and transport of water and ions in plants affecting the salinization in the root zone through physical and physiological processes, we measured water and ion uptake by roots, transpiration rate, leaf conductance, and ion concentrations in root xylem sap and other plant tissues of corn and sunflower grown under saline conditions using a nutrient film technique system. The rate of root water uptake was lower in corn than in sunflower, where the daytime stomatal closure in response to the excessive water stress induced by the saline solution was occurred in corn but not in sunflower. NO3-, PO43- and K+ were highly concentrated in the xylem sap as a result of the active and selective uptake of nutrients by roots of both corn and sunflower. Na+, which is not an essential element for plant growth, was not highly concentrated in the xylem sap or plant tissues of corn because corn exhibited a poor Na+ absorption and transportation ability. On the other hand, sunflower had a greater ability to absorb water, Na+, Mg2+, Ca2+, Cl-, and SO42-, and to transport these ions from the roots to the shoot. These differences in absorption and transport of water and ions indicate that sunflower is more salt tolerant than corn. The effects of these absorption and transport characteristics on plant growth and soil salinity should be taken into account for sustainable and effective plant production in salinized crop fields.View full abstractDownload PDF (684K) -
Fei WANG, Haruhiko YAMAMOTO, Yasuomi IBARAKI, Kiyoshi IWAYA, Naru TAKA ...2009 Volume 65 Issue 1 Pages 27-37
Published: March 10, 2009
Released on J-STAGE: April 22, 2009
JOURNAL FREE ACCESSAs one kind of disaster, typhoons can cause serious damage to landscape trees both mechanically and physiologically. The Typhoon 0613 was characterized by strong wind associated with less rainfall when it passed through Yamaguchi City, Japan. After hit by it, the symptoms of leaf necrosis appeared on many ginkgo trees from coast to inland and the crowns of them became asymmetrically discolored. Due to the big body of ginkgo trees, this kind of phenomenon was often described by visual scale method characterized by significant deviation and observer specific. In order to quantitatively estimate the symptoms of damage, the leaf necrotic area percentage (LNAP), crown discoloration area percentage (CDAP) and inflection point (IP) of the threshold response function for asymmetric discolored crowns were determined by image pixel method. The green/luminance (G/L) value was measured by using the RGB images respectively scanned by a flat bed scanner from individual leaves and taken with a CCD digital camera from crowns. Significant relationship between G/Lleaf and LNAP, and between G/Lcrown and CDAP were obtained with the correlation coefficient of R2=0.941 and R2=0.826 separately. This suggested that both leaf necrosis and asymmetric crown discoloration of ginkgo trees induced by Typhoon 0613 can be quantitatively estimated by measuring the G/L value from both leaves and crowns. The significant relation between CDAP and IP (R2=0.811) reveals that both statistically calculated IP value and visually divided CDAP value can be used in estimating the asymmetric crown characters. The estimation of sampled leaves showed that it was the difference of necrotic leaves between windward and leeward made the crown of damaged ginkgo trees appear asymmetrical discoloration. Image threshold responsive analysis of ginkgo crowns hit by Typhoon 0613 indicated that the injury of ginkgo crowns was more serious on windward than leeward. The relationship between the distance from coastline (DC) and G/Lcrown value presented that the farther from the coastline, the bigger the G/Lcrown value of ginkgo crowns. Comparing to the sampling method, image analysis can be more effective being applied in field measurement of damaged status of ginkgo trees hit by severe typhoons for the reason of less labor and less time requirement. It may be an alternative tool to be used in estimating the degree of damage to ginkgo trees by typhoons like Typhoon 0613.View full abstractDownload PDF (588K) -
Bin HE, Hiroki OUE, Taikan OKI2009 Volume 65 Issue 1 Pages 39-46
Published: March 10, 2009
Released on J-STAGE: April 22, 2009
JOURNAL FREE ACCESSThe Penman-Monteith (PM) equation for evapotranspiration (ET) estimation has been applied in the world. Its weak point is the estimation of the canopy resistance. This paper proposed a simple canopy resistance model for estimating ET on an hourly basis. A non-linear functional relationship between canopy resistance, aerodynamic resistance, and climatic resistance was proposed. For model validation, data was collected in an irrigated wheat field in the Hetao Irrigation District, which is the largest one along the Yellow River. Surface energy balance and near-surface weather variables were measured during the growth cycle of wheat. Measured hourly ET values were obtained by the Bowen ratio energy balance method. Regression of predicted versus measured ET data resulted in r2=0.97 with slope of 0.98 and intercept of 0.01 which are not different from 1 and 0 at 99% confidence. This study provided a simple way to estimate ET with a general available meteorological database which can be further applied in hydrologic models considering effects of variable canopy resistance.View full abstractDownload PDF (335K) -
Takafumi DATE, Masahito UEYAMA, Yoshinobu HARAZONO, Yuji OTA, Toru IWA ...2009 Volume 65 Issue 1 Pages 47-60
Published: March 10, 2009
Released on J-STAGE: April 22, 2009
JOURNAL FREE ACCESSWe improved the satellite-based empirical model (Kitamoto et al., 2007) by adding additional effective parameters on vapor pressure deficit (VPD) and photosynthesis, and estimated the CO2 budget within black spruce forests in Alaska. In the stand scale validation, our modified model successfully reproduced the observed gross primary productivity (GPP), ecosystem respiration (RE), and net ecosystem exchange (NEE) by the eddy covariance measurement. The 10-day average of the model output was highly correlated with the observed GPP (r2=0.9), RE (r2=0.9), and NEE (r2=0.7).
We used the modified model to estimate the regional GPP, RE, and NEE of black spruce forests over Alaska from 1982 to 2003 by using the normalized difference vegetation index (NDVI) from the Advanced Very High Resolution Radiometer (AVHRR) and climate data. The estimated regional averages of GPP, RE, and NEE were 2,172, 2,008, and -164 g CO2 m-2 y-1 during the past 22 years. Our model analysis showed that GPP was mainly affected by spring air temperature, whereas RE was affected by summer air temperature, indicating that the sink strength of the black spruce forests was controlled by the seasonality in air temperature between spring and summer. Path analysis enforced the notation that spring warming increased the CO2 sink, but summer warming decreased the sink.View full abstractDownload PDF (1210K)
Full Papers (in Japanese)
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Daizou IGARASHI, Mami KINOSHITA, Masayuki SUZUKI, Ayako YOSHIDA, Yoshi ...2009 Volume 65 Issue 1 Pages 61-67
Published: March 10, 2009
Released on J-STAGE: April 22, 2009
JOURNAL FREE ACCESSWe compared the effects of heat retention of the row cover material ‘PVA flat yarn fabric’ with that of PVA non-woven fabric (trade name Tuffbell) from December to January. A tunnel-shaped floating row cover (1 m wide and 30 cm high in the middle) was installed in an open field, and the internal microclimate was measured. PVA flat yarn fabric is made from flat plate-like fibers (6 or 7 mm wide) propped up straight with polyethylene line. Four vacant space rates (22%, 33%, 56%, and 67%) were set up by changing the intervals of the flat yarns, whereupon the following finding became clear.
1) On sunny days, the smaller the vacant space rate of the material, the higher the air and soil temperature under the row cover rose in the daytime, although conversely, both dropped at night.
2) The difference in air temperature between the inside and outside (row cover-no cover) decreased as the wind velocity increased from 0 m/s to 0.7-0.8 m/s, although the air temperature under the row cover at night rose, when the wind velocity exceeded a certain figure.
3) Materials most closely akin to Tuffbell 3800N with respect to the beneficial effects on temperature under the row cover were the PVA flat yarn fabric, the vacant space rates of which were 56% and 67%. The PVA flat yarn fabric was considered to be usable as a substitute for PVA non-woven fabric.
4) When the vacant space rate of PVA flat yarn fabric exceeded that of PVA non-woven fabric, an equivalent effect on heat retention was obtained. This may encourage the development of novel materials with good ventilation and the use of PVA flat yarn for the purpose of heat retention.View full abstractDownload PDF (687K)
Short Papers
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Tomoyoshi HIROTA, Yukiyoshi IWATA, Manabu NEMOTO, Takahiro HAMASAKI, R ...2009 Volume 65 Issue 1 Pages 69-76
Published: March 10, 2009
Released on J-STAGE: April 22, 2009
JOURNAL FREE ACCESSSoil water balance determines the accumulation and leaching of solutes in the surface soil. In cold regions, where agricultural land is covered with snow in winter, the soil water balance has not been as thoroughly investigated as in warm regions due to the difficulty of conducting continuous and accurate winter field observation in cold environments. In this study, annual water balance at Tokachi, Hokkaido, Japan was evaluated including snow-covered periods using a comprehensive hydrometeorological observation system developed for cold region application. During the period from October 20, 2004 to October 19, 2005, the ground was covered with snow for a total of 130 days. Annual precipitation during the study period was 799 mm and estimated evaporation was 591 mm. During the snow-covered period, precipitation was 260 mm, accounting for only 32.5% of the annual precipitation; however, precipitation excess was large (236 mm) due to very small evaporation (24 mm), and the bulk of it infiltrated rapidly during the four-week snowmelt period. This observation suggests that the leaching of soil solutes occurs almost exclusively during the snowmelt period, and that the agricultural soil environment in this region is strongly affected by the water balance in the snow-cover period.View full abstractDownload PDF (387K) -
Satoshi INOUE, Tomoyoshi HIROTA, Yukiyoshi IWATA, Kazuyoshi SUZUKI, Ma ...2009 Volume 65 Issue 1 Pages 77-82
Published: March 10, 2009
Released on J-STAGE: April 22, 2009
JOURNAL FREE ACCESSA comparative observation of solid precipitation was carried out at conditions below freezing point during the winter of 2005-2006 by using four instruments, including non-collecting measurement instruments. Based on a comparison with the measured increment of snow water equivalent data, data corrected for the catch ratio from a Japanese standard precipitation gauge (RT-4), measured data from a non-collecting sensor using a laser beam (PWD11) and a totalizer using a load sensor (T-200B) accurately determined the amount of solid precipitation. The measured T-200B data fluctuated during the period of non-precipitation. Positive results of consecutive time were obtained from the measured PWD11 and T-200B data. Data collected in this study from a non-collecting sensor using microwaves (R2S) were unstable or underestimated the amount of precipitation.View full abstractDownload PDF (577K) -
Hiroyoshi SUGIURA, Daisuke SAKAMOTO, Toshihiko SUGIURA, Toshikazu ASAK ...2009 Volume 65 Issue 1 Pages 83-88
Published: March 10, 2009
Released on J-STAGE: April 22, 2009
JOURNAL FREE ACCESSTo apply a technique to estimate correctly and easily the long-term water use in Japanese pear under the root zone restriction cultivation for irrigation, the Granier method of sap flow measurement was compared with the measurement of transpiration using a balance. The sap flow rate was calculated by multiplying the sap flow velocity, given by Granier's original equation, by the sapwood area, which was estimated using the dyeing method. The daily sap flow rate, as measured by the Granier method, correlated well with the daily transpiration rate during the growing period. In addition, provided heartwood had not developed, the daily sap flow rate was measured directly using the Granier method by multiplying the sap flow velocity by the cross-sectional area, excluding the bark. This suggests that the Granier method can be used to measure the daily transpiration rate in Japanese pear to produce long-term estimates of daily water use for irrigation throughout the growing period.View full abstractDownload PDF (350K) -
Keisuke MOCHIDA, Hiroyuki ITAMURA2009 Volume 65 Issue 1 Pages 89-96
Published: March 10, 2009
Released on J-STAGE: April 22, 2009
JOURNAL FREE ACCESSCold tolerance was compared among the three ‘Saijo’ persimmon strains “Abe”, “Endo”, and “Izumo”. We also determined the carbohydrate and non-tannin flavans content (mainly anthocyanins) in the stems and buds of 1-year-old twigs of the three strains. In “Abe”, the total sugar content in stems in early spring, just before sprouting, was significantly lower than those of “Endo” and “Izumo”. This was because the amounts of sucrose and sorbitol contained in “Abe” were significantly lower than those in the other two strains. The glucose content of “Abe” buds in early spring was likewise significantly lower than that of the other two strains. The non-tannin flavan contents of the buds and bark tissues of “Abe” stems were lower than those of “Endo”, while in mid-March the electrolyte leakage of stems and buds of “Abe” during treatments at -3 and -6°C was found to be significantly higher than in the other two strains. Browning was observed in “Abe” on stems after treatment at -3°C, and on cambiums after treatment at -6°C. Our results showed that “Abe” is the least tolerant to cold among the three strains. The sprouting disorders frequently observed in “Abe” may result from slight freezing injuries to buds.View full abstractDownload PDF (303K)
Research Note
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Masashi OKADA, Toshichika IIZUMI, Motoki NISHIMORI, Masayuki YOKOZAWA2009 Volume 65 Issue 1 Pages 97-109
Published: March 10, 2009
Released on J-STAGE: April 22, 2009
Advance online publication: December 01, 2008JOURNAL FREE ACCESSThe Intergovernmental Panel on Climate Change (IPCC) published the Fourth Assessment Report (AR4) in 2007 and stated that recent climate change and variation are induced by increases in the atmospheric greenhouse gases (GHG) concentration due to anthropogenic activities. The report includes the results of impact assessments on a wide range of sectors. These assessments have been conducted based on future climate projections, which refer to aspects of the future climate evaluated by Atmosphere-Ocean Coupled General Circulation Models (CGCMs). The projection data used in the AR4 are archived under the Program for Climate Model Diagnosis and Intercomparison (PCMDI) promoted by the U.S. Department of Energy. We interpolated the projection data around Japan and constructed a dataset entitled the “Mesh climate change data of Japan Ver. 2” for the climate change impact study. Nine projections performed by seven models under the A1B and A2 of the Special Report on Emissions Scenarios (SRES) were implemented for the dataset. They consist of mesh data with a size of 7.5′ in longitude and 5.0′ in latitude, i.e. approximately 10×10 km (45″ in longitude and 30″ in latitude, approximately 1×1 km, for one high-resolution model). The dataset includes five climatic elements, i.e. the daily mean, maximum, and minimum surface air temperatures, daily total precipitation, and daily accumulated shortwave radiation for three periods, 1981-2000, 2046-2065, and 2081-2100. This article describes the details concerning the construction and characteristics of the data.View full abstractDownload PDF (3959K)
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