Abstracts for the 5th International GAME Conf.

3-5 October 2001

Aichi Trade Center

Nagoya Japan

Surface energy budget in the Eastern Tibetan Plateau during GAME/Tibet IOP 1998

Tanaka, Kenji (1), Ishikawa, Hirohiko (2), Tamagawa, Ichiro (3)

One of the high light in the boundary layer observation in GAME/Tibet is the direct estimation of sensible and latent heat flux from terrestrial surface to the atmosphere. Continuous measurement of turbulent fluxes was conducted at Amdo site during the IOP in 1998. Although the measurement revealed the characteristics of seasonal change of the fluxes, the results were unsatisfactory in the scope of surface energy balance. As reported in the previous conferences, the closure ratio at Amdo was between 0.6 and 0.85, which was poor considering the rather ideal condition at Amdo. We have checked the data quality of IR humidity sensor using two criteria: one the intensity of infrared ray, and the other the covariance between water vapor density from infrared hygrometer and that from capacitant sensor compared with dynamic calibration range. It is found that the performance of the IR humidity sensor was rather poor during and after the precipitation. The strength of IR source was weakened in August which also degrades the performance. After replacing the IR source in late August, the IR humidity sensor worked well. Rn-H-lE-G), it is found that the process on freezing and melting of water in the near surface soil layer plays an significant role. In the night time, the d is negative, which should be used for freezing the water of near surface soil layer. The amount of fronzen water estimated from d is about 3.1mm. However, in the early morning, both latent and sensible heat flux was suppressed until the surface temperature reached to 0 deg. C. During this period the d reaches more than 250 W/m2. Some of such positive residual energy can be explained as energy for melting of frozen water of surface layer. But some is unexplainable, which causes the several parcent of imbalance in daily average. Anyway, the surface closure ratio in daily average is 0.90-0.95, which shows better closure than reported before. For the period when the IR humidity sensor showed poor performance, we are trying to estimate latent heat flux by other method such as bandpass covariance method with the use of slow responding capacitant hygrometer.

Submittal Information

Name : Date :
    Mr. Tanaka, Kenji
    01-Jun-01-10:00:18
Organization : Theme :
    Department of Civil and Environmental Engineering, Kumamoto Univ.
    Theme 1
Address : Presentation :
    Kurokami 2-39-1, Kumamoto, 860-0855
    Poster or oral
Country : Abstract ID :
    Japan
    T1MTK01Jun01100018
Phone : Fax :
    +81-96-342-3601
    +81-96-342-3601
E-mail :
    ktanaka@gpo.kumamoto-u.ac.jp