Data

TITLE:  In-situ tower greenhouse gas data (The Pennsylvania State University)
PROJECT: Gulf Coast Intensive (GCI)
DATES:  March 2015 – current

COMMENTS:  Measurements are made with Picarro Inc. wavelength-scanned cavity ring down spectroscopic instruments located at the base of communication towers.  Hourly averages are reported here, with the minimum and maximum time included in the average indicated.  The standard deviation within the averaging window is  also reported.  The air samples are dried using Nafion dryers.  In order to check for leaks in the tubing, two tubes are alternatively sampled every five minutes for one hour each day.  A zero-offset correction is applied daily, using data collected from 1 or 2 NOAA-calibrated tanks.  Round robin tests using 3-4 NOAA-calibrated tanks are conducted every 1-2 years.  Results are then used to field calibrate the instruments (slope and intercept correction).

ABSTRACT:  The earth’s terrestrial biosphere has been a strong net sink of atmospheric CO2 for roughly three decades, substantially slowing the rate of accumulation of CO2 in the atmosphere due to combustion of fossil fuels. The causes of this net sink and its likely evolution in the future, however, both remain quite uncertain, yielding substantial uncertainty in our projections of future climate. Understanding the terrestrial carbon cycle remains a high priority for understanding climate change and is of great importance in the southeastern U.S. in part because terrestrial biosphere models have shown that the largest uncertainty in simulated NEP of CO2 in North America to be in the southeastern U.S. The region is a dynamic and relatively poorly constrained contributor to the terrestrial carbon balance of North America.

Furthermore, the forests of the southeastern U.S. are important for the North American carbon balance because they are one of the most productive biomes on the continent, have large biological fluxes, and are sensitive to climate change. The Gulf Coast Intensive (GCI) project seeks to apply recent advances in atmospheric inversion methodology and observational technology to study the carbon balance of North America as a whole with special emphasis, including new terrestrial inventory assessments, on the dynamic and relatively understudied southeastern United States. The network of CO2 measurements sites was?designed to minimize?anthropogenic influences (e.g., power plants) while maximizing the data impact of each site.? Factors that were taken into consideration were existing observations, land coverage, net ecosystem productivity, fossil fuel emission estimates from Vulcan, and large emission sources such as power plants.

FLAGS:  1 indicates no known problems. 0 indicates that the data is not recommended for use.

COLUMN HEADERS: Location(Site number), Height (m AGL), Time (minimum fractional day of year of the measurement, GMT), Time(maximum fractional day of year of the measurement, GMT), Year, DOY(day of year), Hour(GMT), CO2(dry mole fraction, ppm), Standard_Deviation(during measurement, ppm), Instrument_CO2_Uncertainty(ppm), CH4(dry mole fraction, ppb), Standard_Deviation(during measurement, ppb), Instrument_CH4_Uncertainty(ppb), CO(dry mole fraction, ppb), Standard_Deviation(during measurement, ppb), Instrument_CO_Uncertainty(ppb).

FAIR USE POLICY:
We reserve the right to make corrections to the data based on scientific grounds, e.g., recalibration of standard gases or discovery of operational issues not known at the time of the release.  If the data are obtained for potential use in a publication or presentation, kindly inform Penn State personnel (co2data@meteo.psu.edu) of the nature of this work.

Citations:

Richardson, S.J., N.L. Miles, K.J. Davis, E.R. Crosson, C. Rella, and A.E. Andrews: Field testing of cavity ring-down spectroscopic analyzers measuring carbon dioxide and water vapor.  J. Atmos. Oceanic Tech., 29, 397 – 406, 2012. 

Miles, N.L., S.J. Richardson, D.K. Martins, K.J. Davis, T. Lauvaux, B.J. Haupt, and S.K. Miller, 2018. ACT-America: L2 In Situ CO₂, CO, and CH₄ Concentrations from Towers, Eastern USA. ORNL DAAC, Oak Ridge, Tennessee, USA. https://doi.org/10.3334/ORNLDAAC/1568.

Link to data

PLEASE DO NOT DISTRIBUTE THESE DATA