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NACP: Urban Greenhouse Gases across the CO2 Urban Synthesis and Analysis Network

Documentation Revision Date: 2019-10-31

Dataset Version: 1


This dataset provides hourly urban greenhouse gas measurements for cities in the CO2 Urban Synthesis and Analysis (CO2-USA) Data Synthesis Network. Measurements include carbon dioxide (CO2), methane (CH4), and carbon monoxide (CO) concentrations measured at hourly intervals at multiple sites within the cities of Boston, Indianapolis, Los Angeles, Portland, Salt Lake City, and San Francisco.

There are a total of 197 data files in netCDF (*.nc) format. The same data are provided in text (*.txt) format as "Companion files".

Figure 1: Carbon dioxide concentrations at the MUR site in Salt Lake City, Utah show a pronounced seasonal pattern of higher CO2 in the winter months. Source:


Mitchell, L., J.C. Lin, L.R. Hutyra, M. Sargent, S.C. Wofsy, N.L. Miles, S.J. Richardson, K.R. Verhulst, R.M. Duren, A. Rice, R.C. Cohen, A. Shusterman, S. Newman, and A. Guha. 2019. NACP: Urban Greenhouse Gases across the CO2 Urban Synthesis and Analysis Network. ORNL DAAC, Oak Ridge, Tennessee, USA.

Table of Contents

  1. Dataset Overview
  2. Data Characteristics
  3. Application and Derivation
  4. Quality Assessment
  5. Data Acquisition, Materials, and Methods
  6. Data Access
  7. References

Dataset Overview

This dataset provides hourly urban greenhouse gas measurements for cities in the CO2 Urban Synthesis and Analysis (CO2-USA) Data Synthesis Network. Measurements include carbon dioxide (CO2), methane (CH4), and carbon monoxide (CO) concentrations measured at hourly intervals at multiple sites within the cities of Boston, Indianapolis, Los Angeles, Portland, Salt Lake City, and San Francisco.

Project: North American Carbon Program

The North American Carbon Program (NACP) is a multidisciplinary research program designed to improve understanding of North America's carbon sources, sinks, and stocks. The central objective is to measure and understand the sources and sinks of Carbon Dioxide (CO2), Methane (CH4), and Carbon Monoxide (CO) in North America and adjacent oceans. The NACP is supported by a number of different federal agencies.


This work was funded by NACP under the NOAA Climate Program Office's Atmospheric Chemistry, Carbon Cycle, and Climate program, award #NA17OAR4310084.

Data Characteristics

Spatial Coverage: USA cities: Boston, Massachusetts; Indianapolis, Indiana; Los Angeles, California; Portland, Oregon; and San Francisco, California.

Spatial Resolution: point locations

Temporal Coverage: 2000-01-01 to 2019-05-14. Different sites operated for different time periods.

Temporal Resolution: hourly

Study Sites: Latitude, longitude, start and end dates, and measurement height for each sampling location within the cities are provided in the data files. All latitudes and longitudes given in decimal degrees.


Westernmost Longitude

Easternmost Longitude

Northernmost Latitude

Southernmost Latitude




43.709 41.350


-85.745 -86.740 40.041 39.581

Los Angeles

-118.600 -117.250 34.610 32.870






Salt Lake City

-112.070 -111.848 40.794


San Francisco

-123.073 -121.600 38.319



Data File Information

There are a total of 197 data files in netCDF (*.nc) format. For each site, a separate netCDF file was created for each chemical species (CO2, CH4, or CO). When available, there is a separate netCDF file for the “background” measurements of each chemical species. The “background” time series comes from the published literature, and users are encouraged to read the relevant publication to understand how the “background” time series was created and should be used.

File Naming Convention: File names are structured as:

where CITY can be

  • boston
  • indianapolis
  • los_angeles
  • portland
  • salt_lake_city
  • san_francisco_baaqmd
  • san_francisco_beacon

and SPECIES can be

  • ch4
  • co
  • co2

The SITE and measurement HEIGHT identify the specific observation location. The TIMERES of all files is "1_hour". The R# and YYYY-MM-DD provide the revision number and the date of data file creation.


Data File Details: Each file contains the following variables.

Variable Units Description
ch4 or co or co2 nanomol mol-1 average of the greenhouse gas (either ch4, co, or co2) mole fraction measurements (ppb) during each 1 hour time period
elevation m elevation above sea level at the station location
inlet_height m height of the sample inlet above ground level
lat degrees north latitude
lon degrees east longitude
n count number of the ch4 mole fraction measurements in the hour
std_dev nanomol mol-1 standard deviation of the ch4 mole fraction measurements (ppb) in the hour
time seconds number of seconds since January 1, 1970 in UTC
time_string character sample date/time in ISO 8601 format (UTC)
uncertainty nanomol mol-1 measurement uncertainty determined by the data provider


The following additional information can be found within each of the netCDF and text files:
- Title of the data set
- Summary
- Keywords
- References
- Date created
- Fair use data policy
- Data provider name, affiliation, contact information, and email
- Compilation originator name, affiliation, contact information, and email
- Temporal resolution of the data
- Data start and stop dates
- Instruments used in the data collection
- Calibration scale of the species

Companion files

Text (*.txt) files are identical to the netCDF (*.nc) files and are included as an alternative way to access the data.

Application and Derivation

These cooperative data products are made freely available to the public and scientific community to advance the study of urban carbon cycling and associated air pollutants.

Quality Assessment

Each city has developed its own metric to estimate measurement uncertainty, and these estimates are included when available. In
addition, the standard deviation and number of the measurements used to calculate the hourly averages are included when

Data Acquisition, Materials, and Methods

CO2-USA Network

Cities have emerged as leaders in US efforts to reduce greenhouse gas emissions, but the scientific knowledge to quantitatively track emissions and assess the efficacy of mitigation is lacking. As the global population increasingly resides in urban regions, scientific knowledge about how much, where, and why a particular city emits carbon becomes increasingly important. This collaborative network aims to exchange information on community standards and common measurements, facilitate data sharing, and create analysis frameworks and cross-city syntheses to catalyze a new generation of researchers and enable new collaborations tackling important objectives that are difficult to address in isolation.  


Specifically this CO2-USA synthesis effort seeks to:

  • Quantify & understand similarities/differences in CO2 and CH4 fluxes across cities;
  • Develop harmonized CO2 and CH4 mixing ratio datasets that are readily useable, traceable, and accessible by the research community and the public;
  • Construct an atmospheric modeling system that is scalable and transferable between cities;
  • Compare & understand similarities/differences between anthropogenic emission inventories;
  • Improve estimates of biospheric fluxes across cities;
  • Foster a community of urban carbon cycle researchers and generate collaborative studies;
  • Engage stakeholders to link them with data, syntheses, and insights into urban emissions.

More information about the CO2-USA project can be found on the project web page:

Data Collection and Compilation Methods

Urban GHG monitoring projects are underway in many cities, including Los Angeles (Feng et al, 2016; Verhulst et al 2016), Indianapolis (Lauvaux et al 2016), Salt Lake City (McKain et al 2012), Paris (Staufer et al 2016), Washington, DC (Mueller et al 2017), and Boston (McKain et al 2015; Sargent et al 2018). These observational networks provide an opportunity for top-down assessments of GHG emissions using high-precision atmospheric measurements that are highly intercomparable both within the network and between networks, and offer long-term stability.

Code used to compile and work with this data product is being maintained on the following GitHub repository:

In particular, scripts to load the data from the netCDF files have been written in the R and Matlab programming languages.  They can be found here:

Scripts to download multiple files using R and Matlab can be found at the following links


Data Access

These data are available through the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

NACP: Urban Greenhouse Gases across the CO2 Urban Synthesis and Analysis Network

Contact for Data Center Access Information:


Feng, S., Lauvaux, T., Newman, S., Rao, P., Ahmadov, R., Deng, A., Díaz-Isaac, L. I., Duren, R. M., Fischer, M. L., Gerbig, C., Gurney, K. R., Huang, J., Jeong, S., Li, Z., Miller, C. E., O'Keeffe, D., Patarasuk, R., Sander, S. P., Song, Y., Wong, K. W., and Yung, Y. L. (2016) Los Angeles megacity: a high-resolution land–atmosphere modelling system for urban CO2 emissions, Atmos. Chem. Phys., 16, 9019–9045,

Lauvaux T, et al. 2016) High-resolution atmospheric inversion of urban CO2 emissions during the dormant season of the Indianapolis Flux Experiment (INFLUX). J Geophys Res Atmos 121:5213–5236.

McKain K, et al. (2015) Methane emissions from natural gas infrastructure and use in the urban region of Boston, Massachusetts. Proc Natl Acad Sci USA 112:1941–1946.

McKain K, et al. (2012) Assessment of ground-based atmospheric observations for verification of greenhouse gas emissions from an urban region. Proc Natl Acad Sci USA 109:8423–8428.

Mueller, K., Yadav, V., Lopez‐Coto, I., Karion, A., Gourdji, S., Martin, C., & Whetstone, J. ( 2018). Siting background towers to characterize incoming air for urban greenhouse gas estimation: A case study in the Washington, DC/Baltimore area. Journal of Geophysical Research: Atmospheres, 123, 2910– 2926.

Sargent, M., Y. Barrera, T. Nehrkorn, L.R. Hutyra, C.K. Gately, T.  Jones, K. McKain, C. Sweeney, J. Hegarty, B. Hardiman, and S.C. Wofsy. (2018) Anthropogenic and biogenic CO2 fluxes in the Boston urban region, PNAS, 115(29), 7491-7496.

Staufer, J., Broquet, G., Bréon, F.-M., Puygrenier, V., Chevallier, F., Xueref-Rémy, I., Dieudonné, E., Lopez, M., Schmidt, M., Ramonet, M., Perrussel, O., Lac, C., Wu, L., and Ciais, P. (2016) The first 1-year-long estimate of the Paris region fossil fuel CO2 emissions based on atmospheric inversion, Atmos. Chem. Phys., 16, 14703–14726,

Verhulst, K. R., Karion, A., Kim, J., Salameh, P. K., Keeling, R. F., Newman, S., Miller, J., Sloop, C., Pongetti, T., Rao, P., Wong, C., Hopkins, F. M., Yadav, V., Weiss, R. F., Duren, R. M., and Miller, C. E. (2017) Carbon dioxide and methane measurements from the Los Angeles Megacity Carbon Project – Part 1: calibration, urban enhancements, and uncertainty estimates, Atmos. Chem. Phys., 17, 8313–8341,