住宅街の接地境界層における乱流フラックスの実測 -シンチロメーターの利用-  [in Japanese] Turbulent Flux Measurement in an Urban Boundary Layer by Using Scintillometer  [in Japanese]

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Author(s)

    • 神田 学 KANDA Manabu
    • 東京工業大学理工学研究科国際開発工学専攻 Department of International Development Engineering, Tokyo Institute of Technology
    • 森脇 亮 MORIWAKI Ryo
    • 東京工業大学理工学研究科国際開発工学専攻 Department of International Development Engineering, Tokyo Institute of Technology
    • 鈴木 譲 [他] SUZUKI Jo
    • 東京工業大学理工学研究科国際開発工学専攻 Department of International Development Engineering, Tokyo Institute of Technology

Abstract

密集低層住宅街(世田谷)の接地境界層において, 渦相関法とシンチロメーター法を併用した乱流フラックス観測を行い, 以下の結論を得た.(1)世田谷住宅街における放射収支・熱収支解析データを提示し, その特徴を示した.(2)2高度におけるシンチロメーター計測により, 顕熱と同時にゼロ面変位を推定する手法を提案した.推定されたゼロ面変位は, 平均的にはMacDonald et al.(1998)の形態学的手法から算定された値とほぼ一致した.また, ゼロ面変位が大気安定度に依存することを指摘した.(3)渦相関法とシンチロメーター法の比較により乱流フラックスの空間代表性が検討された.シンチロメーター法のソースエリアは渦相関法のそれに対して, 不安定時で2~3倍の広さを持つ.30分平均値での顕熱は両手法で有意な差がない.顕熱の標準偏差は大気安定度に関わらずシンチロメーター法の値が小さい.これは計測スパンの長いシンチロメーター法における渦の空間積分効果であると考えられる.

Field observations to investigate area-averaged turbulence characteristics were performed in a densely built-up residential neighborhood in Tokyo, Japan.Besides eddy-correlation sensors, a scintillometer was used in an urban environment.Several important results are summarized as follows : (1) Radiation balance and energy balance of observation area are obtained.(2) A new technique which uses simultaneous scintillation measurements at two heights is developed to estimate directly both area-averaged zero-plain displacement height Z_d and heat flux Q_H.The estimated Z_d is found to be slightly dependent on the atmospheric stability parameter (lower Z_d under more unstable conditions).(3) Source areas for the scintillometer are 2-3 times larger than those for the eddy correlation sensors under unstable conditions.30-min averaged, normalized standard deviations of Q_H measured by the two methods are compared. Whilst Q_H estimates agree well, their short time variability was generally larger for the eddy-correlation as compared with the scintillometer data under wide range of stability conditions.This result can be attributed to the superior spatial integration due to the longer averaging path (250 m) of the scintillometer.It is concluded that time-averaging requirements to obtain representative flux measurement for scintil-lometer applications can be relaxed.

Journal

  • 天気

    天気 47(6), 453-462, 2000-06-30

    日本気象学会

References:  15

Cited by:  7

Codes

  • NII Article ID (NAID)
    110001814278
  • NII NACSIS-CAT ID (NCID)
    AN00151568
  • Text Lang
    JPN
  • Article Type
    Journal Article
  • ISSN
    05460921
  • NDL Article ID
    5392039
  • NDL Source Classification
    ZM43(科学技術--地球科学--気象)
  • NDL Call No.
    Z15-35
  • Data Source
    CJP  CJPref  NDL  NII-ELS  NDL-Digital 
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