Observations of CO2, CH4, and CO mole fractions from the NIST Northeast Corridor urban testbed

NOTE: please see the latest (March 2025) update at https://doi.org/10.18434/mds2-3765. Hourly observations of CO2 and CH4 from tower-based sites in the NIST Northeast Corridor network (currently 23, but more may be added in future updates); CO observations from one site. Data files are comma delimited (CSV). Measurements of each species may be from two or more different heights above ground. Site locations, heights, and other information is in a separate ascii (CSV) file (NEC_sites.csv). Data is currently reported for the years 2015-2019, with planned annual updates. An ASCII Readme file (NEC_Readme_10052020) is also posted, along with an Updates_10052020.txt file that includes information on updates.  Current update: Nov 11, 2020. See also associated publication (Karion et al., Earth System Science Data, 2020): https://doi.org/10.5194/essd-12-699-2020