Studies on the turbulence characteristics and flux data quality control at Tak
Flux Measurement Station in Thailand
Wonsik Kim (1), Jaeil Cho (2), Shin Miyazaki (2)Shinjiro Kanae (3) and Taikan Oki (2)(1)

Seoul National University. e-mail: wonsik@snu.ac.kr, (2) IIS, University of Tokyo(3)

Research Institute for Humanity and Nature, and University of Tokyo

Abstract
Using the data for 2003, the basic studies for long-term flux measurement are carried out at Tak flux
measurement station (TFMS) in Thailand. The experimental site is located in Chao Praya River Basin which is one ofthe starting points of Asian Monsoon. The vegetation around TFMS consists of a large area of tropical deciduous forestand several kind of crop field. While the land surface heterogeneity, the characteristics of wind flow and turbulence areavailable for flux measurement because:1.

The west wind via vegetated tropical deciduous forest is dominated during the rainy season but the daily
variation observed during the dry season.

2.

The integrated turbulence characteristics based on Monin-Obukhov similarity are well matched tomicrometeorological theory.

3.

The coordinate rotation and Webb correction are applied to rotate the main streamline and to correct density
fluctuation.

4.

Considering the land cover and micrometeorological characteristics at TFMS, the strategy of data quality
control for standard micrometeorological measurements of TFMS are constructed.

Keyword: Data quality control, Eddy covariance technique, Tak Flux Measurement Station, Turbulence characteristics.

1. Introduction
About150

3. Resultflux

measurement

towersareFigure 1 shows the characteristics of wind flow atconstructed over the world to monitor energy, water andTFMS on February and August in 2003. The wind flow

carbon dioxide fluxes. The data from those towers haveduring the rainy season comes from only west, while theimproved our knowledge about water and carbon cycle

daily variation of wind flows are clearly appeared during

upon the land surface. However the most sites are locatedthe dry season. (i.e. the north-east and south-west windin North America and Europe, only a few sites areblow in the daytime and nighttime, respectively).

available in Asia. Especially, the sites for long-term andFigure 2 shows various turbulence characteristics

precise flux measurement in Indochina peninsular are

based on Monin-Obukhov similarity at experimental site.

rare though it is important region to the meteorological,

The characteristics will be presented and discussed inhydrological and ecological aspect. Consequently, thethis meeting.

aims of this study are to continually measure the energy,
water and carbon dioxide fluxes at least during ten years

Referenceusing eddy covariance technique, and to extract the flux

Wonsik Kim et al. (2003) Real time monitoring anddatabyits

qualitycontrolfor

standard

simulation system (RTMASS) for Tak fluxmicrometeorological measurements considering the landmeasurement site, Thailand. Korean Journal ofcover and micrometeorological characteristics at TFMS.

Agricultural and Forest Meteorology 5, 116-127.

2. Experimental site and instrumentation
The TFMS site (latitude: 16°56’N, longitude:99°25’E) is located about 20 km east of Tak and 50 km
west of Sukhothai in the northwest part of Thailand.
There is essentially a flat area of about 100 km2 and 130
m higher than sea level. The fetch is more than 10 kmwith gently undulating hills with about 20 m differencesin height. The climate of the experimental area is divided
into wet and dry seasons as a part of the Southeast Asia
monsoon region. The onsets of the wet and dry seasons
are in May and October, and the mean temperatures ofeach season are about 27°C and 32°C, respectively. The
total annual precipitation is about 1200 mm. The
vegetation consists of 70% 10-15 m tall deciduous trees
with 3-5 leaf area index, and 30% agricultural area
cultivating rice, corn and tobacco. The eddy covariancetechnique to measure the fluxes is used at the TFMS site.
In applying the technique, two sets of the prototype
instrument consisting of three dimensional sonicanemometers and an open path CO2/H2O) gas analyzer.

Figure 1. The characteristics of wind flow at Tak flux

The detail description refers to Kim et al. (2003).

measurement station on February and August in 2003.

Figure 2. The analyzed turbulence characteristics during the wet season.