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Harvard Forest Data Archive
Atmospheric Oxygen and Carbon Dioxide at Harvard Forest EMS Tower since 2006Related Publications
- Lead: Mark Battle, William Munger
- Contact: Mark Battle
- Start date: 2006
- End date: 2013
- Status: ongoing
- Location: Prospect Hill Tract (Harvard Forest)
- Latitude: +42.537755
- Longitude: -72.171478
- Elevation: 340 meter
- Release date: 2018
- EML file: knb-lter-hfr.306.1
- DOI: digital object identifier
- Related links:
- Study type: long-term measurement
- Research topic: forest-atmosphere exchange
- LTER core area: primary production
- Keywords: carbon cycling, climate change, decomposition, net ecosystem exchange, oxygen, plant physiology, soil respiration
This archive features long-term measurements of the atmospheric mixing ratios of O2 and CO2 at two heights on the Harvard Forest EMS flux tower. The data fields include the time of data collection, the height from which the samples were drawn, the O2 mixing ratio and the CO2 mixing ratio.
The values in this dataset were obtained using a modified Oxzilla II differential fuel-cellbased O2 analyzer (made by Sable Systems) and a LiCor 7000 non-dispersive infrared analyzer, also operating differentially. Measurements were made relative to a tank of dry air which was in turn periodically compared to a set of between 2 and 4 long-term standard tanks with filled with dry air with a range of O2 and CO2 values. These tanks are tied to the NOAA/WMO CO2 scale (Zhao and Tans, 2006) and Scripps Institution of Oceanography O2 scale (Keeling et al., 1998 and Keeling et al., 2007). Thus, the dataset here is reported on these scales.
Data have already undergone substantial processing and analysis, including the removal of values from periods when the instruments were unstable or unreliable. More detailed descriptions of both the instrumental techniques and the data processing are available from Conley (2018) with further information forthcoming in Battle et al. (in prep.)
Values reported here are average values for 4.8-minute sampling periods spaced 12 minutes apart. In general, consecutive values alternate between collections from the low (7.5m) and high (29.0m) intakes. Periodic gaps in the dataset correspond to regularly scheduled calibration runs against the standard tanks (every 6hrs, as well as asynchronous daily and weekly comparisons with other standard tanks). Irregular gaps of varying length result from instrumental problems.
This dataset is released to the public under Creative Commons license CC BY (Attribution). Please keep the designated contact person informed of any plans to use the dataset. Consultation or collaboration with the original investigators is strongly encouraged. Publications and data products that make use of the dataset must include proper acknowledgement.
Battle M, Munger W. 2018. Atmospheric Oxygen and Carbon Dioxide at Harvard Forest EMS Tower since 2006. Harvard Forest Data Archive: HF306.
hf306-01: O2 and CO2 data
- date: the (decimal) number of days since Jan. 0, 0000 (MatLab datenum) (unit: number / missing value: NA)
- co2: μmoles/mole on the NOAA/WMO scale (unit: dimensionless / missing value: NA)
- o2: μmoles/mole on the Scripps S2 O2 scale. The Scripps S2 scale is typically expressed in permeg units as δO2/N2. We connect our mole-fraction measurements to the S2 scale by assuming XO2 in the S2 scale is 0.2095 (See Keeling et al. 1998, eqn. 4). (unit: dimensionless / missing value: NA)
- intake: height above forest floor
- 1: 29.0 m
- 0: 7.5 m
- data.id: serial number used to locate a particular datum in the full (unprocessed) dataset