The ESRL Halocarbons and other Atmospheric Trace Species (HATS) group has been measuring chlorofluorcarbon-113 (CFC-113) with three separate programs since 1992. The programs include two flask systems using gas chromatography with either electron capture detector (ECD) or mass spectrometry detection (MSD) and one in situ ECD measurement program. Flask measurements started in 1992 with six stations and continue today sampling at 14 locations. In situ measurements of CFC-113 were started in 1998 with the CATS gas chromatographs that are currently installed at six remote field sites and make hourly measurements.

There is a systematic difference between MSD and ECD measurements (both flask and in situ programs), where the ECD data is on average 1.5 ppt greater. Results from ECD instruments (OTTO and CATS) have been adjusted for the combined data set presented here. Follow the individual measurement program links at the bottom of this page for unadjusted data.

Hemispheric and global means are calculated by combining measurements from the flask and in situ programs. The HATS CFC-113 data is on the NOAA 2003 scale.

Combined HATS CFC-113 data file

The figure above shows the different measurement programs' calculated global means and illustrates the overlap amongst programs (current programs are solid lines, dashed lines are discontinued programs). Measured monthly means from the different programs are statistically combined to create a long-term NOAA/ESRL GMD data set (black line). The combined data is calculated by first interpolating missing data at a sampling location for each measurement program. A weighted average is subsequently taken where there are co-located measurements from two or more programs; followed by a three month wide box smooth algorithm.

Zonal means are calculated for four northern (solid lines) and three southern (dashed lines) bins.

Hemispheric and a global mean are calculated from the zonal averages where sampling locations are weighted by the cosine of their latitude. This combined CFC-113 data set is used in NOAA's Annual Greenhouse Gas Index (AGGI) and NOAA's Ozone Depleting Gas Index (ODGI).

Global history of CFC-113 as function of a latitude (y-axis) and time (x-axis).

The Combined HATS CFC-113 Data File uses monthly data from the following programs:

• MSD flask program: Paired flask means
• Current ECD flask program: Monthly, Global
• CATS in situ program: Hourly, Daily, Monthly, Global