Micrometeorological CO2 Flux Data at Fuji Hokuroku Flux Observation Site (FHK)

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Fuji Hokuroku Flux Observation Site (FHK) is located in the larch forest at the foothills of Mt. Fuji in central Honshu, Japan. We began monitoring in 2006 to understand the CO2 exchange and carbon cycle processes in forest ecosystems. We investigate forest carbon balance with multiple approaches, such as micrometeorological measurement, forest census, eco-physiological methods, and remote sensing.
This data set includes ecosystem CO2 flux, and sensible and latent heat flux which were measured with eddy covariance methods, and meteorological items, such as temperature, precipitation, wind, and radiation. The meteorological conditions affect plants growth, and they were measured at multiple points of height/depth ranging from 35m height on a flux observation tower to 1m depth at forest floor. This dataset is also provided by the AsiaFlux Database (http://asiaflux.net/index.php?page_id=23).


Yoshiyuki Takahashi
Center for Global Environmental Research, Earth System Division, National Institute for Environmental Studies
NIES research staff page: https://www.nies.go.jp/researchers-e/100114.html
Release date
Temporal coverage
2006/01/01 - 2012/12/31
Data provider
National Institute for Environmental Studies
Email: cgerdb_admin(at)nies.go.jp
File format
Data volume
60 MB
ver.2.1 (Last updated: 2021/07/30)

Data Set

Net ecosystem carbon exchange
CO2 flux
CO2 storage in canopy air layer
CO2 concentration
Sensible heat flux
Latent heat flux
Friction velocity
Momentum flux
Global solar radiation (incoming)
Global solar radiation (outgoing)
Long-wave radiation (incoming)
Long-wave radiation (outgoing)
Net Radiation
Transmitted solar radiation (below canopy incoming)
Transmitted solar radiation (below canopy outgoing)
Transmitted long-wave radiation (below canopy incoming)
Transmitted long-wave radiation (below canopy outgoing)
Transmitted net radiation (below canopy)
Photosynthetic active photon flux density
Transmitted PAR
Reflected PAR
Reflected PAR (below canopy outgoing)
Wind direction
Wind speed
Air temperature
Relative humidity
Vapor pressure deficit
Soil temperature
Ground heat flux
Soil water content
Barometric pressure
Snow depth
Time resolution
30 minutes
Observation period
From 2006/01/01 (ongoing)
Observation site
Fuji Hokuroku Flux Observation Site (FHK)
Location: 35.443528°N, 138.764722°E
Elevation: 1050-1150 m
Sampling height: 35, 32, 27, 22, 16, 10, 4.5, 2, 1.5, 1, 0.5, 0, -0.02, -0.05, -0.1, -0.15, -0.2, -0.3, -0.6 m
Measurement method
Net ecosystem CO2 exchange flux (NEE) is measured by eddy covariance (EC) method at height of 35 m on the measurement tower over a deciduous needle-leaf plantation forest in the foothills of Mt. Fuji. Three-dimensional wind speeds and virtual temperatures were measured using a three-dimensional sonic anemometer-thermometer, and CO2 fluctuation was measured using open-path and closed-path CO2/H2O analyzers. For closed-path system, sample air was pumped from the air-inlet at 35m into the gas analyzers through tubes of ca. 12 m length. The flux data were sampled and logged at frequency of 10 Hz. The vertical profile of CO2 concentration was also measured at 10 heights from 0.5-35m, in order at a frequency of 1 cycle in 2 minutes, for 12 seconds at each altitude.
Calculation method
The CO2 concentration measured by closed-path gas analyzer was calibrated once a day using two standard CO2 gases of 320 and 420 micro mol mol-1. The net ecosystem exchange (NEE) of CO2 was derived from the sum of the flux measured by EC (F_EC) and the rate of change in column CO2 storage under EC measurement height (Fs). Half-hourly mean F_EC was calculated as the covariance between fluctuations in vertical wind speed and scalar quantity of CO2 concentration. The setting of the quality control applied to the 30-minute value of the turbulent flux is described in "3-4. Quality control" of the information file attached to this data together with the source. Half-hourly mean Fs was calculated from the vertical profile of CO2 concentration at 10 heights.
In Situ Land-based Platforms > Ground Stations
[Free keywords]
Net ecosystem carbon exchange
Eddy covariance method
Deciduous needle-leaf forest
Update history
The flux and meteorological data from 2006 to 2012 have been compiled in Asiaflux Data Base Format, as ver2.1.
Some of available parameters were changed in ver.2.1, as updating from ver.1.1. See the correspondence table for parameters in the supplementary file (Parameters_v1.1_v2.1.pdf).
The meteorological data from 2006 to 2010 have been compiled in NASA Ames Format 1001 (text file) and original csv format, as ver1.1.
The meteorological data from 2006 to 2010 have been compiled in csv format. ver1.0.

Reference Information

Supplementary Materials
Site description: SiIn_FHK_2006-2012_02-1.pdf
Description of the flux and meteorological data for 2006-2012: FxMt_FHK_2006-2012_30m_02-1.pdf
Correspondence table for parameters between ver. 1.1 and ver.2.1: FHK_Parameters_v1.1_v2.1.pdf
Teramoto M., Liang N., Zeng J., Saigusa N., Takahashi Y., 2017, Long-term chamber measurements reveal strong impacts of soil temperature on seasonal and inter-annual variation in understory CO2 fluxes in a Japanese larch (Larix kaempferi Sarg.) forest. Agricultural and Forest Meteorology, 214, 194-206, DOI:10.1016/j.agrformet.2017.07.024.
Ueyama M., Takeuchi R., Takahashi Y., Ide R., Ataka M., Kosugi Y., Takahashi K., Saigusa N., 2015, Methane uptake in a temperate forest soil using continuous closed-chamber measurements. Agricultural and Forest Meteorology, 213, 1-9, DOI:10.1016/j.agrformet.2015.05.004.
Takahashi Y., Saigusa N., Hirata R., Ide R., Fujinuma Y., Okano T., Asarse T. 2015, Characteristics of temporal variations in ecosystem CO2 exchange in a temperate deciduous needle-leaf forest in the foothills of a high mountain. Journal of Agricultural Meteorology, 71(4), 302-317, DOI:10.2480/agrmet.D-14-00009.

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Takahashi (2021), Micrometeorological CO2 Flux Data at Fuji Hokuroku Flux Observation Site (FHK), Ver.x.x *1, National Institute for Environmental Studies, DOI:10.17595/20210730.001, (Reference date*2: YYYY/MM/DD)
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