A Comparison of Carbon Dioxide and Methane Levels at Four Tower Sites Across the United States


Looking at seasonality and overall trends for different greenhouse gases allows scientists to make predictions for the future, and also look at areas where humans can lessen the negative impacts they are having on the Earth’s atmosphere. Carbon Dioxide (CO₂) and Methane (CH₄) are greenhouse gases that have been documented to be steadily increasing over time due to anthropogenic sources. Here we present the results of an investigation of the overall temporal trends and seasonal variations of both gases using NOAA Programmable Flask Package (PFP) data. PFPs are automated sampling packages that can be sent anywhere and sampled by aircraft, towers, or mobile laboratories. All PFP air samples are analyzed at the central analytical lab at NOAA, Boulder by spectroscopy or chromatography. While PFP data has been collected at 17 tower sites since the early 2000s, this study makes use of 4 specific tower sites in the contiguous United States (see table 1, map 1). Sites were chosen in in order to sample a variety of tower environments and to ensure a healthy sampling of data from 2006/2007 to the present. Carbon dioxide and methane both show distinct seasonal trends at all locations, although methane generally shows less variability.


Ben Miller

Lab site

National Oceanic Atmospheric Administration Earth Systems Research Laboratory (NOAA ESRL)

Funding Acknowledgement

This material is based upon work supported by the S.D. Bechtel, Jr. Foundation and by the National Science Foundation under Grant No. 0952013. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the S.D. Bechtel, Jr. Foundation or the National Science Foundation. This project has also been made possible with support of the National Marine Sanctuary Foundation. The STAR program is administered by the Cal Poly Center for Excellence in Science and Mathematics Education (CESaME) on behalf of the California State University (CSU).

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