Harvard Forest

Data Archive

HF209

Isotopic Composition of Net Ecosystem CO2 Exchange at Harvard Forest EMS Tower since 2011

Related Publications

Data

• hf209-01: uncorrected fluxes (preview)
• hf209-02: corrected fluxes (preview)
• hf209-03: ambient CO2 (preview)
• hf209-04: vertical profiles (preview)
• hf209-05: two-minute average CO2 (preview)
• hf209-06: MRC CO2 (preview)
• hf209-07: MRC del13 CO2 (preview)
• hf209-08: MRC del18 CO2 (preview)
• hf209-09: MRC temperature (preview)
• hf209-10: quality control filtered data (preview)

Overview

• Lead: Scott Saleska, Richard Wehr
• Investigators: William Munger
• Contact: Information Manager
• Start date: 2011
• End date: 2013
• Status: ongoing
• Location: Prospect Hill Tract (Harvard Forest)
• Latitude: +42.537755 degrees
• Longitude: -72.171478 degrees
• Elevation: 340 meter
• Datum: WGS84
• Taxa:
• Release date: 2023
• Language: English
• EML file: knb-lter-hfr.209.13
• DOI: digital object identifier
• EDI: data package
• DataONE: data package
• Related links:
• Canopy-Atmosphere Exchange of Carbon, Water and Energy at Harvard Forest EMS Tower since 1991
• Study type: long-term measurement
• Research topic: forest-atmosphere exchange
• LTER core area: primary production
• Keywords: carbon dioxide, eddy covariance, isotopes, net ecosystem exchange
• Abstract:

  This archive features long-term measurements of the eddy and storage fluxes of 16O12C16O, 16O13C16O, and 18O12C16O at the Harvard Forest EMS flux tower. Provided are the individual isotopologue fluxes, the total CO2 flux, the δ13C and δ18O isofluxes, and various ancillary flux and environmental data. The data are described in Wehr et al (2013), Long-term eddy covariance measurements of the isotopic composition of the ecosystem–atmosphere exchange of CO2 in a temperate forest, Agricultural and Forest Meteorology 181, 69–84. They are also analyzed in Wehr and Saleska (2015), An improved isotopic method for partitioning net ecosystem–atmosphere CO2 exchange, Agricultural and Forest Meteorology 214-215, 515–531, as well as in Wehr et al 2016, Seasonality of Temperate Forest Photosynthesis and Daytime Respiration, Nature (in press).

  The eddy (iso)fluxes were measured by eddy covariance (EC), with a 30- or 35-minute integration period on a 40- or 45-minute duty cycle (the precise duty cycle was changed during the record to accommodate various synergistic measurement campaigns). The storage fluxes were measured as the increase in storage below 29 m during the EC integration period, based on vertical integrations over 7 air sampling heights on the tower (0.2, 1.0, 7.5, 12.7, 18.1, 24.1, 29.0 m, prior to July 3, 2012), or over 6 air sampling heights on the tower (0.2, 1.0, 7.5, 12.7, 18.1, 29.0 m, after July 3, 2012). Some periods are missing at regular intervals because the system was being used for other measurements, not reported here.

  Corrected and uncorrected versions of the eddy (iso)fluxes are provided; the corrections account for high-frequency signal attenuation, and were made by comparing w-CO2 and w-T cospectra. The precise method is novel and complex and is described, along with all further details of the measurements, in Wehr et al (2013), Long-term eddy covariance measurements of the isotopic composition of the ecosystem–atmosphere exchange of CO2 in a temperate forest, Agricultural and Forest Meteorology 181, 69–84. The original, uncorrected cospectra are provided as well, for those wishing to employ an alternate correction method. These are not Fourier cospectra but rather multiresolution cospectra, as described in the following reference: Howell and Mahrt (1997), Multiresolution flux decomposition, Boundary-Layer Meteorology 83, 117-137. The covariance is the simple sum (i.e. not the discretized integral) of all 15 points in the corresponding multiresolution cospectrum.

  This archive also includes measurements of the total molar mixing ratio of CO2 to dry air and of the isotope ratios δ13C and δ18O, at each of the 7 heights. For the lower six heights (or the lower 5 heights after July 3, 2012), these measurements are provided only as 40-second averages of the original 4 Hz data (which are too copious to archive here), made once every 40 minutes. For the 29 m inlet (the main inlet, used for EC), these measurements are provided as 2-minute averages of the 4 Hz data, made continuously during the 30-minute EC integration periods. The last 40-seconds of each EC integration period is included also as the 7th height (6th height after July 3, 2012) in the vertical profile record.

  The file hf209-10-qc-filtered.csv contains a subset of the data in the other files, after quality control filtering that removed data points for which the sonic anemometer data were likely erroneous.

• Methods:

  The molar mixing ratios of 16O12C16O, 16O13C16O, and 18O12C16O to dry air were measured by a quantum cascade laser spectrometer designed by Aerodyne Research Inc, which runs in a temperature-controlled enclosure in the EMS shack. Measurements were made near-continuously at 4 Hz, on a 40-minute duty cycle consisting of 30 min at 29 m (for EC), 1 min for each of the 'profile' heights, and 2 min for each of 2 calibration cylinders. The first 20 seconds of each 1-minute profile measurement, and of each 30-minute EC period, were disregarded to avoid transients while the system was flushed with the new sample gas. The first 30 seconds of each calibration cylinder measurement were similarly disregarded.

  The isotopologue molar mixing ratios were calibrated on a 40-minute interval by linear interpolation between the two aforementioned cylinders: a high span gas cylinder containing roughly 450 ppm CO2 in air, and a low span cylinder containing roughly 350 ppm CO2 in air. These 'working' tanks bracketed the sample gas total CO2 mixing ratio except when sampling from the subcanopy at night (when the total CO2 mixing ratio can reach 650 ppm). Systematic extrapolation errors in the 0.2 m and 1 m tower profile measurements are therefore a possibility; however, such errors are not likely to be larger than twice our usual systematic instrument errors (see below). The slopes and intercepts of the resulting calibration lines were interpolated onto the 4 Hz sample times and used to calibrate each sample measurement.

  Each pair of working tanks was calibrated in turn against three primary standard cylinders (at 315.48(6) ppm, 431.15(6) ppm, and 496.49(6) ppm CO2 in air) when the working tanks were full (~2000 psi) and when they had ~500 psi remaining, after which the working tanks were replaced to avoid the possibility of variations in total CO2, d13C, or d18O as the cylinders neared depletion. Before deployment, the primary standards were characterized by IRMS at the Stable Isotope Ratio Facility for Environmental Research at the University of Utah (for the isotope ratios) and by an IRGA (calibrated with a set of primary CO2 standards obtained from NOAA-GMD) in the Wofsy/Munger Laboratory at Harvard University (for the CO2 molar mixing ratio). Calibration of the working tanks against the primary standards was done using the spectrometer itself, in the field.

  The total CO2 molar mixing ratio (to dry air) and the isotope ratios d13C and d18O were calculated from the individual isotopologue molar mixing ratios measured by the spectrometer. This calculation required some assumptions about the molar mixing ratio of 12C17O16O and other unmeasured minor isotopologues, although the results are not significantly affected by the uncertainties associated with these assumptions.

  The short-term (3-hour) precision in the reported measurements for a 100-second integration time is 16 ppb in total CO2, 0.02 permil in d13C, and 0.03 permil in d18O (1 standard deviation). The long-term (6-month) accuracy is 69 ppb in total CO2, 0.05 permil in d13C, and 0.06 permil in d18O (1 standard deviation).

  Eddy and storage fluxes for each isotopologue and for total CO2, plus the eddy and storage isofluxes for 13C-CO2 and 18O-CO2, were calculated by eddy covariance using wind data from the sonic anemometer that is operated as part of the existing long-term eddy flux measurement system at the EMS. Data from that system is listed in this archive under HF004: EMS - Canopy-Atmosphere Exchange of Carbon, Water and Energy. We have included some useful ancillary data from that dataset (PAR, water vapor flux) here when available.

• Organization: Harvard Forest. 324 North Main Street, Petersham, MA 01366, USA. Phone (978) 724-3302. Fax (978) 724-3595.

• Project: The Harvard Forest Long-Term Ecological Research (LTER) program examines ecological dynamics in the New England region resulting from natural disturbances, environmental change, and human impacts. (ROR).

• Funding: National Science Foundation LTER grants: DEB-8811764, DEB-9411975, DEB-0080592, DEB-0620443, DEB-1237491, DEB-1832210.

• Use: This dataset is released to the public under Creative Commons CC0 1.0 (No Rights Reserved). Please keep the dataset creators informed of any plans to use the dataset. Consultation with the original investigators is strongly encouraged. Publications and data products that make use of the dataset should include proper acknowledgement.

• License: Creative Commons Zero v1.0 Universal (CC0-1.0)

• Citation: Saleska S, Wehr R. 2023. Isotopic Composition of Net Ecosystem CO2 Exchange at Harvard Forest EMS Tower since 2011. Harvard Forest Data Archive: HF209 (v.13). Environmental Data Initiative: https://doi.org/10.6073/pasta/ce508c9dc6bc9b0bdfbceeb8fd28beda.

Detailed Metadata

hf209-01: uncorrected fluxes

1. datetime: date and time stamps, mean value for the eddy flux integration period
2. igor.time: redundant date and time stamp, used by the Igor programming language (seconds since the start of January 1, 1904) (unit: second / missing value: NA)
3. eddy.flux.co2: CO2 eddy flux past the sensor at 29m, not corrected for high frequency signal attenuation (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
4. storage.flux.co2: CO2 storage flux, i.e. the increase in CO2 storage below 29m (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
5. eddy.isoflux.del13: 13C-CO2 eddy isoflux past the sensor at 29m (permil umol/m2/s), not corrected for high frequency signal attenuation (unit: dimensionless / missing value: NA)
6. storage.isoflux.del13: 13C-CO2 storage isoflux, i.e. the increase in 13C-CO2 isostorage below 29m (permil umol/m2/s) (unit: dimensionless / missing value: NA)
7. eddy.isoflux.del18: 18O-CO2 eddy isoflux past the sensor at 29m (permil umol/m2/s), not corrected for high frequency signal attenuation (unit: dimensionless / missing value: NA)
8. storage.isoflux.del18: 18O-CO2 storage isoflux, i.e. the increase in 18O-CO2 isostorage below 29m (permil umol/m2/s) (unit: dimensionless / missing value: NA)
9. eddy.flux.626: eddy flux of the CO2 isotopologue 16O12C16O past the sensor at 29m, not corrected for high frequency signal attenuation (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
10. storage.flux.626: storage flux of the CO2 isotopologue 16O12C16O, i.e. the increase in 16O12C16O storage below 29m (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
11. eddy.flux.636: eddy flux of the CO2 isotopologue 16O13C16O past the sensor at 29m, not corrected for high frequency signal attenuation (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
12. storage.flux.636: storage flux of the CO2 isotopologue 16O13C16O, i.e. the increase in 16O13C16O storage below 29m (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
13. eddy.flux.268: eddy flux of the CO2 isotopologue 18O12C16O past the sensor at 29m, not corrected for high frequency signal attenuation (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
14. storage.flux.268: storage flux of the CO2 isotopologue 18O12C16O, i.e. the increase in 18O12C16O storage below 29m (unit: micromolePerMeterSquaredPerSecond / missing value: NA)

hf209-02: corrected fluxes

1. datetime: date and time stamps, mean value for the eddy flux integration period
2. igor.time: redundant date and time stamp, used by the Igor programming language (seconds since the start of January 1, 1904) (unit: second / missing value: NA)
3. eddy.flux.co2: CO2 eddy flux past the sensor at 29m, corrected for high frequency signal attenuation (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
4. storage.flux.co2: CO2 storage flux, i.e. the increase in CO2 storage below 29m (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
5. eddy.isoflux.del13: 13C-CO2 eddy isoflux past the sensor at 29m (permil umol/m2/s), corrected for high frequency signal attenuation (unit: dimensionless / missing value: NA)
6. storage.isoflux.del13: 13C-CO2 storage isoflux, i.e. the increase in 13C-CO2 isostorage below 29m (permil umol/m2/s) (unit: dimensionless / missing value: NA)
7. eddy.isoflux.del18: 18O-CO2 eddy isoflux past the sensor at 29m (permil umol/m2/s), corrected for high frequency signal attenuation (unit: dimensionless / missing value: NA)
8. storage.isoflux.del18: 18O-CO2 storage isoflux, i.e. the increase in 18O-CO2 isostorage below 29m (permil umol/m2/s) (unit: dimensionless / missing value: NA)
9. eddy.flux.626: eddy flux of the CO2 isotopologue 16O12C16O past the sensor at 29m, corrected for high frequency signal attenuation (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
10. storage.flux.626: storage flux of the CO2 isotopologue 16O12C16O, i.e. the increase in 16O12C16O storage below 29m (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
11. eddy.flux.636: eddy flux of the CO2 isotopologue 16O13C16O past the sensor at 29m, corrected for high frequency signal attenuation (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
12. storage.flux.636: storage flux of the CO2 isotopologue 16O13C16O, i.e. the increase in 16O13C16O storage below 29m (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
13. eddy.flux.268: eddy flux of the CO2 isotopologue 18O12C16O past the sensor at 29m, corrected for high frequency signal attenuation (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
14. storage.flux.268: storage flux of the CO2 isotopologue 18O12C16O, i.e. the increase in 18O12C16O storage below 29m (unit: micromolePerMeterSquaredPerSecond / missing value: NA)

hf209-03: ambient CO2

1. datetime: date and time stamps, mean value for the eddy flux integration period
2. igor.time: redundant date and time stamp, used by the Igor programming language (seconds since the start of January 1, 1904) (unit: second / missing value: NA)
3. co2: mean CO2 molar mixing ratio to dry air (ppm) (unit: dimensionless / missing value: NA)
4. del13c: mean ratio of 13C to 12C in CO2 expressed as a deviation from the VPDB standard (permil) (unit: dimensionless / missing value: NA)
5. del18o: mean ratio of 18O to 16O in CO2 expressed as a deviation from the VSMOW standard (permil) (unit: dimensionless / missing value: NA)
6. sensible.heat.flux: sensible heat flux past the sensor at 29m (unit: wattPerMeterSquared / missing value: NA)
7. water.vapor.flux: water vapor flux past the sensor at 29m (unit: molePerMeterSquaredPerSecond / missing value: NA)
8. par: photosynthetically active radiation (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
9. airt: air temperature (unit: celsius / missing value: NA)
10. airp: air pressure (unit: pascal / missing value: NA)
11. rh: relative humidity (%) (unit: dimensionless / missing value: NA)
12. dry.air: concentration of dry air (unit: molePerCubicMeter / missing value: NA)
13. wet.air: concentration of wet air (unit: molePerCubicMeter / missing value: NA)
14. wind.speed: mean wind speed (unit: metersPerSecond / missing value: NA)
15. wind.dir: wind source direction (degrees from North, 90 = from the east) (unit: degree / missing value: NA)
16. ustar: friction velocity (unit: metersPerSecond / missing value: NA)

hf209-04: vertical profiles

1. datetime: date and time stamps, mean value for the eddy flux integration period
2. igor.time: redundant date and time stamp, used by the Igor programming language (seconds since the start of January 1, 1904) (unit: second / missing value: NA)
3. num.inlets: number of CO2 sampling inlets active (unit: number / missing value: NA)
4. co2.0.2m: CO2 molar mixing ratio to dry air measured at 0.2m (ppm) (unit: dimensionless / missing value: NA)
5. co2.1.0m: CO2 molar mixing ratio to dry air measured at 1.0m (ppm) (unit: dimensionless / missing value: NA)
6. co2.7.5m: CO2 molar mixing ratio to dry air measured at 7.5m (ppm) (unit: dimensionless / missing value: NA)
7. co2.12.5m: CO2 molar mixing ratio to dry air measured at 12.5m (ppm) (unit: dimensionless / missing value: NA)
8. co2.18.3m: CO2 molar mixing ratio to dry air measured at 18.3m (ppm) (unit: dimensionless / missing value: NA)
9. co2.24.1m: CO2 molar mixing ratio to dry air measured at 24.1m (ppm) (unit: dimensionless / missing value: NA)
10. co2.29.0m: CO2 molar mixing ratio to dry air measured at 29.0m (ppm) (unit: dimensionless / missing value: NA)
11. del13.0.2m: ratio of 13C to 12C in CO2 expressed as a deviation from the VPDB standard, measured at 0.2m (permil) (unit: dimensionless / missing value: NA)
12. del13.1.0m: ratio of 13C to 12C in CO2 expressed as a deviation from the VPDB standard, measured at 1.0m (permil) (unit: dimensionless / missing value: NA)
13. del13.7.5m: ratio of 13C to 12C in CO2 expressed as a deviation from the VPDB standard, measured at 7.5m (permil) (unit: dimensionless / missing value: NA)
14. del13.12.5m: ratio of 13C to 12C in CO2 expressed as a deviation from the VPDB standard, measured at 12.5m (permil) (unit: dimensionless / missing value: NA)
15. del13.18.3m: ratio of 13C to 12C in CO2 expressed as a deviation from the VPDB standard, measured at 18.3m (permil) (unit: dimensionless / missing value: NA)
16. del13.24.1m: ratio of 13C to 12C in CO2 expressed as a deviation from the VPDB standard, measured at 24.1m (permil) (unit: dimensionless / missing value: NA)
17. del13.29.0m: ratio of 13C to 12C in CO2 expressed as a deviation from the VPDB standard, measured at 29.0m (permil) (unit: dimensionless / missing value: NA)
18. del18.0.2m: ratio of 18O to 16O in CO2 expressed as a deviation from the VSMOW standard, measured at 0.2m (permil) (unit: dimensionless / missing value: NA)
19. del18.1.0m: ratio of 18O to 16O in CO2 expressed as a deviation from the VSMOW standard, measured at 1.0m (permil) (unit: dimensionless / missing value: NA)
20. del18.7.5m: ratio of 18O to 16O in CO2 expressed as a deviation from the VSMOW standard, measured at 7.5m (permil) (unit: dimensionless / missing value: NA)
21. del18.12.5m: ratio of 18O to 16O in CO2 expressed as a deviation from the VSMOW standard, measured at 12.5m (permil) (unit: dimensionless / missing value: NA)
22. del18.18.3m: ratio of 18O to 16O in CO2 expressed as a deviation from the VSMOW standard, measured at 18.3m (permil) (unit: dimensionless / missing value: NA)
23. del18.24.1m: ratio of 18O to 16O in CO2 expressed as a deviation from the VSMOW standard, measured at 24.1m (permil) (unit: dimensionless / missing value: NA)
24. del18.29.0m: ratio of 18O to 16O in CO2 expressed as a deviation from the VSMOW standard, measured at 29.0m (permil) (unit: dimensionless / missing value: NA)

hf209-05: two-minute average CO2

1. datetime: date and time stamps, mean value for the eddy flux integration period
2. igor.time: redundant date and time stamp, used by the Igor programming language (seconds since the start of January 1, 1904) (unit: second / missing value: NA)
3. co2: mean CO2 molar mixing ratio to dry air (ppm) (unit: dimensionless / missing value: NA)
4. del13c: mean ratio of 13C to 12C in CO2 expressed as a deviation from the VPDB standard (permil) (unit: dimensionless / missing value: NA)
5. del18o: mean ratio of 18O to 16O in CO2 expressed as a deviation from the VSMOW standard (permil) (unit: dimensionless / missing value: NA)

hf209-06: MRC CO2

1. datetime: date and time stamps, mean value for the eddy flux integration period
2. igor.time: redundant date and time stamp, used by the Igor programming language (seconds since the start of January 1, 1904) (unit: second / missing value: NA)
3. mrc.2.1.pts: w-C multiresolution cospectrum value at 0.11s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
4. mrc.2.2.pts: w-C multiresolution cospectrum value at 0.22s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
5. mrc.2.3.pts: w-C multiresolution cospectrum value at 0.44s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
6. mrc.2.4.pts: w-C multiresolution cospectrum value at 0.88s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
7. mrc.2.5.pts: w-C multiresolution cospectrum value at 1.76s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
8. mrc.2.6.pts: w-C multiresolution cospectrum value at 3.52s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
9. mrc.2.7.pts: w-C multiresolution cospectrum value at 7.03s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
10. mrc.2.8.pts: w-C multiresolution cospectrum value at 14.06s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
11. mrc.2.9.pts: w-C multiresolution cospectrum value at 28.13s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
12. mrc.2.10.pts: w-C multiresolution cospectrum value at 56.25s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
13. mrc.2.11.pts: w-C multiresolution cospectrum value at 112.5s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
14. mrc.2.12.pts: w-C multiresolution cospectrum value at 225s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
15. mrc.2.13.pts: w-C multiresolution cospectrum value at 450s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
16. mrc.2.14.pts: w-C multiresolution cospectrum value at 900s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
17. mrc.2.15.pts: w-C multiresolution cospectrum value at 1800s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)

hf209-07: MRC del13 CO2

1. datetime: date and time stamps, mean value for the eddy flux integration period
2. igor.time: redundant date and time stamp, used by the Igor programming language (seconds since the start of January 1, 1904) (unit: second / missing value: NA)
3. mrc.2.1.pts: w-(d13*C) multiresolution cospectrum value at 0.11s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
4. mrc.2.2.pts: w-(d13*C) multiresolution cospectrum value at 0.22s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
5. mrc.2.3.pts: w-(d13*C) multiresolution cospectrum value at 0.44s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
6. mrc.2.4.pts: w-(d13*C) multiresolution cospectrum value at 0.88s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
7. mrc.2.5.pts: w-(d13*C) multiresolution cospectrum value at 1.76s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
8. mrc.2.6.pts: w-(d13*C) multiresolution cospectrum value at 3.52s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
9. mrc.2.7.pts: w-(d13*C) multiresolution cospectrum value at 7.03s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
10. mrc.2.8.pts: w-(d13*C) multiresolution cospectrum value at 14.06s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
11. mrc.2.9.pts: w-(d13*C) multiresolution cospectrum value at 28.13s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
12. mrc.2.10.pts: w-(d13*C) multiresolution cospectrum value at 56.25s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
13. mrc.2.11.pts: w-(d13*C) multiresolution cospectrum value at 112.5s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
14. mrc.2.12.pts: w-(d13*C) multiresolution cospectrum value at 225s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
15. mrc.2.13.pts: w-(d13*C) multiresolution cospectrum value at 450s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
16. mrc.2.14.pts: w-(d13*C) multiresolution cospectrum value at 900s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
17. mrc.2.15.pts: w-(d13*C) multiresolution cospectrum value at 1800s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)

hf209-08: MRC del18 CO2

1. datetime: date and time stamps, mean value for the eddy flux integration period
2. igor.time: redundant date and time stamp, used by the Igor programming language (seconds since the start of January 1, 1904) (unit: second / missing value: NA)
3. mrc.2.1.pts: w-(d18*C) multiresolution cospectrum value at 0.11s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
4. mrc.2.2.pts: w-(d18*C) multiresolution cospectrum value at 0.22s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
5. mrc.2.3.pts: w-(d18*C) multiresolution cospectrum value at 0.44s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
6. mrc.2.4.pts: w-(d18*C) multiresolution cospectrum value at 0.88s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
7. mrc.2.5.pts: w-(d18*C) multiresolution cospectrum value at 1.76s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
8. mrc.2.6.pts: w-(d18*C) multiresolution cospectrum value at 3.52s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
9. mrc.2.7.pts: w-(d18*C) multiresolution cospectrum value at 7.03s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
10. mrc.2.8.pts: w-(d18*C) multiresolution cospectrum value at 14.06s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
11. mrc.2.9.pts: w-(d18*C) multiresolution cospectrum value at 28.13s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
12. mrc.2.10.pts: w-(d18*C) multiresolution cospectrum value at 56.25s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
13. mrc.2.11.pts: w-(d18*C) multiresolution cospectrum value at 112.5s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
14. mrc.2.12.pts: w-(d18*C) multiresolution cospectrum value at 225s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
15. mrc.2.13.pts: w-(d18*C) multiresolution cospectrum value at 450s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
16. mrc.2.14.pts: w-(d18*C) multiresolution cospectrum value at 900s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
17. mrc.2.15.pts: w-(d18*C) multiresolution cospectrum value at 1800s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)

hf209-09: MRC temperature

1. datetime: date and time stamps, mean value for the eddy flux integration period
2. igor.time: redundant date and time stamp, used by the Igor programming language (seconds since the start of January 1, 1904) (unit: second / missing value: NA)
3. mrc.2.1.pts: w-T multiresolution cospectrum value at 0.11s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
4. mrc.2.2.pts: w-T multiresolution cospectrum value at 0.22s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
5. mrc.2.3.pts: w-T multiresolution cospectrum value at 0.44s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
6. mrc.2.4.pts: w-T multiresolution cospectrum value at 0.88s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
7. mrc.2.5.pts: w-T multiresolution cospectrum value at 1.76s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
8. mrc.2.6.pts: w-T multiresolution cospectrum value at 3.52s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
9. mrc.2.7.pts: w-T multiresolution cospectrum value at 7.03s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
10. mrc.2.8.pts: w-T multiresolution cospectrum value at 14.06s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
11. mrc.2.9.pts: w-T multiresolution cospectrum value at 28.13s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
12. mrc.2.10.pts: w-T multiresolution cospectrum value at 56.25s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
13. mrc.2.11.pts: w-T multiresolution cospectrum value at 112.5s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
14. mrc.2.12.pts: w-T multiresolution cospectrum value at 225s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
15. mrc.2.13.pts: w-T multiresolution cospectrum value at 450s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
16. mrc.2.14.pts: w-T multiresolution cospectrum value at 900s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
17. mrc.2.15.pts: w-T multiresolution cospectrum value at 1800s (unit: micromolePerMeterSquaredPerSecond / missing value: NA)

hf209-10: quality control filtered data

1. datetime: date and time stamp, mean value for the eddy flux integration period
2. igor.time: redundant date and time stamp, used by the Igor programming language (seconds since the start of January 1, 1904) (unit: second / missing value: NA)
3. eddy.flux.co2: CO2 eddy flux past the sensor at 29m, corrected for high frequency signal attenuation (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
4. eddy.isoflux.del13: 13C-CO2 eddy isoflux past the sensor at 29m (permil umol/m2/s), corrected for high frequency signal attenuation (unit: dimensionless / missing value: NA)
5. eddy.isoflux.del18: 18O-CO2 eddy isoflux past the sensor at 29m (permil umol/m2/s), corrected for high frequency signal attenuation (unit: dimensionless / missing value: NA)
6. storage.flux.co2: CO2 storage flux, i.e. the increase in CO2 storage below 29m (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
7. storage.isoflux.del13: 13C-CO2 storage isoflux, i.e. the increase in 13C-CO2 isostorage below 29m (permil umol/m2/s) (unit: dimensionless / missing value: NA)
8. storage.isoflux.del18: 18O-CO2 storage isoflux, i.e. the increase in 18O-CO2 isostorage below 29m (permil umol/m2/s) (unit: dimensionless / missing value: NA)
9. sensible.heat.flux: sensible heat flux past the sensor at 29m (unit: wattPerMeterSquared / missing value: NA)
10. airt: air temperature (unit: celsius / missing value: NA)
11. airp: air pressure (unit: pascal / missing value: NA)
12. rh: relative humidity (%) (unit: dimensionless )
13. dry.air: concentration of dry air (unit: molePerCubicMeter / missing value: NA)
14. par: photosynthetically active radiation (unit: micromolePerMeterSquaredPerSecond / missing value: NA)
15. wind.speed: mean wind speed (unit: metersPerSecond / missing value: NA)
16. wind.dir: wind source direction (degrees from North, 90 = from the east) (unit: degree / missing value: NA)
17. ustar: friction velocity (unit: metersPerSecond / missing value: NA)
18. co2: mean CO2 molar mixing ratio to dry air (ppm) (unit: dimensionless / missing value: NA)
19. del13c: mean ratio of 13C to 12C in CO2 expressed as a deviation from the VPDB standard (permil) (unit: dimensionless / missing value: NA)
20. del18o: mean ratio of 18O to 16O in CO2 expressed as a deviation from the VSMOW standard (permil) (unit: dimensionless / missing value: NA)