Estimation of sensible heat flux in an urban area with scintillometer

用闪烁计估算城市地区的感热通量

基本信息

批准号：
12650601
负责人：
NARITA Ken-ichi
金额：
$ 2.3万
依托单位：
Nippon Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12650601/
关键词：
urban climate convective heat transfer coefficient heat budget sensible heat flux laser beam heat island eddy correlation method turbulence measurement

项目摘要

Scintillometer is newly developed instrument for measuring the sensible heat flux by detecting scintillation of twin polarized laser beams. Structure function of temperature is derived from fluctuation of beam strength, and energy dissipation rate is derived from correlation of twin beam.Sensible heat flux over beam path is estimated from these two parameters of turbulence assuming with the Monin-Obukhov Similarity with some empirical formulas. It has the advantage of measuring path averaged sensible heat flux easily, but prerequisite for measurement, especially in the case of urban area, has not been so clear yet. In this study, observations for verification of sensible heat flux by scintillometer were performed in various kinds of surface, for example river water surface running through built-up area, grassland surface in urban park, paddy field, vegetated stepwise roof-garden, and so on. With the comparison of flux by eddy correlation method, accuracy of scintillometer and some limits of measuring condition were clarified.In order to check the possibility of application of scintillometer to measure sensible heat flux from vertical building wall surface, the apparatus for path change by mirror refraction are also devised.The position of the mirror between transmitter and receiver is important. In the case of just after transmitter and just before receiver, there was no influence of mirror refraction on flux measurement. But V-shape path, that is mirror was located at the middle part of laser path, fluctuation of laser strength become rather unstable and could not measure in any incident angle.

闪烁计是新开发的通过检测双偏振激光束的闪烁来测量显热通量的仪器。温度的结构函数由梁强度的波动导出，能量耗散率由双梁的相关性导出。梁路径上的感热通量由这两个湍流参数估计，假设与莫宁-奥布霍夫相似，并结合一些经验公式。它的优点是可以方便地测量路径平均感热通量，但测量的前提条件，特别是在城市地区，目前尚不明确。本研究利用闪烁计对各种地表进行了观测验证感热通量，例如流经建成区的河水面、城市公园的草地表面、水田、植被阶梯式屋顶花园等。在。通过涡相关法通量的比较，明确了闪烁计的精度和测量条件的一些限制。为了检验闪烁计测量建筑物垂直墙面显热通量的可能性，设计了镜面变路装置。还设计了折射。发射器和接收器之间的镜子的位置很重要。在发射器之后和接收器之前的情况下，镜子折射对通量测量没有影响。但V形路径，即反射镜位于激光路径的中间部分，激光强度的波动变得相当不稳定，无法在任何入射角下进行测量。