This data set contains methane (CH4) flux and related measurements taken at the Happy Valley Flux Study Site in northern Alaska during the summer of 1994. Sampling was conducted to test use of a laser sensor on a portable eddy correlation tower by assessing its practicality for sampling in remote flux studies.
The flux-related variables measured were: wind direction and speed, friction velocity, air temperature, carbon dioxide (C02), H20, sensible and latent heat, CO2 flux, and CH4 flux. The Webb-Pearman-Leuning correction (Webb, 1980) was applied to both the CO2 and CH4 fluxes.
This research was conducted as part of the Land-Atmosphere-Ice Interaction (LAII) research and was funded by the Arctic System Sciences (ARCSS) Program, grant number OPP-9415481.
Data are available for ordering from NCAR.
Oechel, W.C., J.G. Verfaillie, G.L. Vourlitis. 2003. Methane Flux Measurements, Happy Valley, AK, 1994. Boulder, CO: National Center for Atmospheric Research, ARCSS Data Archive.
|Data format||Tab-delimited ASCII text|
|Spatial coverage and resolution||Happy Valley Flux Study Site in northern Alaska at 69.167º N, 148.852º W; resolution was less than 1km2|
|Temporal coverage and resolution||1994-07-19 to 1994-07-24; measurements taken every half hour|
|File size||8 KB|
|Parameter(s)||Wind direction and speed, friction velocity, air temperature, carbon dioxide, water vapor, sensible heat, latent heat, carbon dioxide flux, methane flux|
The data are available as a tab-delimited ASCII text file.
The file size is 8 KB.
Data were collected at the Happy Valley Flux Study Site in northern Alaska, located at 69.167º N, 148.852º W.
The Happy Valley research site is 135 km south of the Arctic Ocean and 1.5 km west of the Trans-Alaska Pipeline and Dalton Highway on the northern slope of the Brooks Range. Soils for this site are Histic Pergelic Cryaquepts with a 15-30 cm layer of partially decomposed organic matter overlying the mineral soil. Mean annual temperature is between -11.1ºC and -6.7ºC, while mean summer temperature (June-August) is approximately 11ºC. Annual precipitation averages 345 mm, with 60 percent falling as rain during the summer months.
The resolution of measurements was less than 1km²; measurements were taken at one sampling point.
Data were collected from 1994-07-19 to 1994-07-24 (Julian days 200 - 205).
Measurements were collected once every half hour.
The parameters measured were wind direction and speed, friction velocity, air temperature, carbon dioxide, water vapor, sensible heat, latent heat, carbon dioxide flux, and methane flux.
|Year||Julian Day||Time (ADT)||Wind Direction (Degrees)||Wind Speed (m/s)||Friction Velocity* (m/s)||Air Temperature (ºC)||CO2 (Ámol/mol)||H2O (mmol/mol)||Sensible Heat (W/m2)||Latent Heat (W/m2)||CO2 Flux (gC/m2/hr)||CH4 Flux (mgC/m2/hr)|
* = suspect data. Difficulties encountered included unstable laser alignment into the optical fiber, precipitation events, and mosquitoes blocking the optical path.
Data are available for ordering from NCAR.
Researchers made measurements with an open-path CH4 analyzer. The fast response methane sensor, based on the absorption of radiation generated with a near-infrared Indium-Gallium-Arsenic-Phosphorus (InGaAsP) diode laser, was developed by Southwest Sciences Inc. of Santa Fe, New Mexico. The open-path approach utilizes mirrors to create multiple passes of the near-infrared beam to achieve the required path length of 50m for the desired sensitivity, approximately 65 ppb as determined in laboratory tests.
On July 19, 1994, the instrument was set up at the Happy Valley site just west of a lake located northwest of the camp. The tower, sonic anemometer (Applied Technology Inc.), water/carbon dioxide sensor (LiCor 6262), generator, and methane sensor were transported by helicopter. Data collection continued through July 24, 1994.
The eddy correlation method using the Webb-Pearman-Leuning correction (Webb, 1980) was applied to both the CO2 and CH4 fluxes. An asterisk appears in the year field in rows where the data are suspect due to the difficulties mentioned above.
Webb, E.K., G.I. Pearman, and R. Leuning. 1980. Correction of flux measurements for density effects due to heat and water vapor transfer. Quart. J. Met. Soc. 106: 85-100.