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Volume 62, Issue 1
March
Displaying 1-5 of 5 articles from this issue
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Yasushi SAKAKIBARA, Yuichi KITAHARA, Kiyotaka NAKAGAWA2006 Volume 62 Issue 1 Pages 1-8
Published: 2006
Released on J-STAGE: March 13, 2007
JOURNAL FREE ACCESSThis paper presents the relationship between urban-rural vapor pressure differences and population size for six settlements in Saku, Nagano Prefecture, Japan, from April 1998 to March 1999. Data were collected using a circuit-type, automobile-based travel method. The water vapor pressure in urban areas was less than that in rural areas almost year-round. The mean value of urban-rural vapor pressure differences was -1.4 hPa on fine days, which was twice larger than values for cloudy and fine nights. The regression line of mean urban-rural vapor pressure differences to settlement population size for cloudy nights was similar to that for fine nights. The mean value of the urban-rural water vapor pressure difference in summer was -1.7 hPa, a value nearly twice that in winter. Mean urban-rural water vapor pressure differences for fine days, fine nights, and cloudy nights related to the logarithm of the settlement population size. Regression line slopes for cloudy and fine nights showed no differences. However, the slope for fine days was twice that of fine and cloudy nights. Finally, the relationship between the annual maximum urban-rural water vapor pressure difference and the logarithm of population size was remarkably steady with R2 > 0.77.View full abstractDownload PDF (746K) -
Yukako KISHIHARA, Masahito UEYAMA, Ken HAMOTANI, Nobutaka MONJI2006 Volume 62 Issue 1 Pages 9-14
Published: 2006
Released on J-STAGE: March 13, 2007
JOURNAL FREE ACCESSAtmosphere-forest CO2 exchange was investigated based on measurements using the eddy correlation method at one height above and four heights inside the canopy of a larch forest by changing the flow route into a single closed-path gas analyzer. A considerable amount of CO2 was found to be transported toward the forest floor containing rich undergrowth.
The second order turbulence closure model was applied to confirm the role of the vegetation near the forest floor. Numerical simulation indicates that the CO2 absorption of this forest may decrease considerably during the daytime if the floor vegetation is eliminated.View full abstractDownload PDF (789K)
Full Papers (in Japanese)
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Masako DANNOURA, Yuji KOMINAMI, Koji TAMAI, Yoshiaki GOTO, Mayuko JOMU ...2006 Volume 62 Issue 1 Pages 15-21
Published: 2006
Released on J-STAGE: March 13, 2007
JOURNAL FREE ACCESSRoot respiration was separated from total soil respiration in this study. Experiments were carried out in September 2003 at Yamashiro Experimental Forest located in Kyoto Prefecture. It is a secondary forest of broad-leaf trees including some conifer species. The root system was dug out and divided into several classes by size. The respiration rate of each size was measured by the closed-chamber method consisting of an IRGA, a pump, and a chamber made of acrylic. Temperature in the chamber was measured by thermo couple. The results showed that the smaller the diameter of the root was, the higher the respiration rate per unit weight was. A Mmuch higher rate was found in fine roots in comparison with other classes. From the relationships between basal diameter and root mass of each size for sample trees, root mass of each size per area was estimated. By combining the respiration rate and root mass of each size per area, root respiration could be calculated at 0.0707 mg CO2 m-2 s-1 as a total. More than the half was occupied by fine root respiration. Mean total soil respiration was 0.19 mg CO2 m-2 s-1 during this experiments. Therefore, the contribution of root respiration to soil respiration was estimated at 37.2%.View full abstractDownload PDF (1019K) -
Daiyu ITO, Toshihiko SUGIURA, Haruyuki KURODA2006 Volume 62 Issue 1 Pages 23-32
Published: 2006
Released on J-STAGE: March 13, 2007
JOURNAL FREE ACCESSIn order to estimate the amount of soil water content of orchards in a region and to improve water management, observations of transpiration and evapotranspiration were made in a Japanese pear orchard. The observations were made over a perild of 4 years, from April to October of each year, using the energy budget (EB), soil water (SW), eddy correlation (EC), and trunk energy budget (TEB) methods. The measured daily transpiration or evapotranspiration was highly proportional to Penman potential evapotranspiration (PET) for almost any month and year. When the inter-year variation was neglected, the coefficient of this proportionality for evapotranspiration (CET) in each month ranged from 0.77 to 0.85. Thus, (0.80 × PET) was proposed as the simplest estimation for daily evapotranspiration. The inter-year variation in CET was larger during the summer season. In the summer, CET was lower in the years in which less precipitation occurred, and a midday depression in the rates of transpiration and evapotranspiration was observed when pF increased. Therefore, water stress was suggested as the cause of inter-year variation in CET. When the effect of water stress was excluded, CET was lower in April, May, and October, and its seasonal variation was around 20%. Since the ratio of transpiration to evapotranspiration was lower in April and May, seasonal depression in CET was suggested to occur due to depressed transpiration that occurred as a result of a small leaf area index (LAI). Thus, finally, we proposed the estimation of daily evapotranspiration more precisely by using the formula 0.97 × f (pF) × g (LAI) × PET, in which the decreasing function f (pF) and the increasing function g (LAI) were introduced.View full abstractDownload PDF (960K) -
Shangxun ZHANG, Keisuke NONAKA, Katsutoshi HORIE, Shoji MATSUMURA, Mas ...2006 Volume 62 Issue 1 Pages 33-40
Published: 2006
Released on J-STAGE: March 13, 2007
JOURNAL FREE ACCESSLong-term continuous measurements of NO2 flux, NO2 dry deposition velocity (Vd) and various microclimate factors were carried out from February to June of both 2002 and 2003 on a wheat field located in Saiwai-cho, Fuchu-shi, Tokyo, Japan. The Bowen ratio technique was used to measure NO2 flux. Average values of daytime data were used to analyze Vd and the relationship between Vd and other factors such as solar radiation. Vd average values during the daytime were in the range of 0.03-1.11 cms-1, were smaller in winter, and were larger in spring. Vd tended to increase along with wheat growth. Vd was affected primarily by leaf area index (LAI), and the relationship between Vd and each microclimate factor was different in LAI of each growing stage. With LAI less than 2, Vd was affected mainly by wind speed, and increased with an increase in wind speed. With LAI greater than 2, Vd was affected mainly by solar radiation, air temperature and vapor pressure deficit, and increased as these factors increased. In the maturing season (with LAI of approximately 5), the relationships between Vd and solar radiation, air temperature and vapor pressure deficit became stronger than during the previous growing periods. The average value of NO2 flux in the daytime during all growing periods was approximately 462 µgm-2 h-1. The amount of NO2 deposition during all growing periods was approximately 0.29 gNm-2.View full abstractDownload PDF (1811K)
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