# Presentation: 667710

## The Radiatively Important Trace Species (RITS) Data Recovery Project1J.D. Nance3, T.M. Thompson2, J.H. Butler2, J.W. Elkins21Funded by NOAA’s Environmental Services Data and Information Management Program (ESDIM)2NOAA Climate Monitoring and Diagnostics Laboratory, 325 Broadway, Boulder, CO 803053Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder 80309

**The Radiatively Important Trace Species (RITS) Data Recovery Project****1**J.D. Nance3, T.M. Thompson2, J.H. Butler2, J.W. Elkins21Funded by NOAA’s Environmental Services Data and Information Management Program (ESDIM)2NOAA Climate Monitoring and Diagnostics Laboratory, 325 Broadway, Boulder, CO 803053Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder 80309

**Table: RITS System Channel Summary**

| RITS Channel | Gas Chromatograph | Carrier Gas | Column Packing Material | Detector | Eluted Compounds |
| --- | --- | --- | --- | --- | --- |
| A | Hewlett-Packard 5890 | P5 | Porasil B | Electron Capture | N2O
 CFC-12
CFC-11 |
| B | Hewlett-Packard 5890 | N2 | OV-101 | Electron Capture | CFC-11
CFC-113 
CH3CCl3
CCl4 |
| C | Shimadzu | P5 | Porapak Q | Electron Capture | N2O
 SF6 |

- From 1999 to 2001, RITS systems were replaced by four-channel CATS (Chromatograph for Atmospheric Trace Species) system GC-ECDs. During this time, efforts were begun to consolidate the RITS dataset, to renew its storage on modern media, to identify and recover data inadvertently lost or degraded during original chromatogram analyses, and to produce a final reckoning of the atmospheric concentrations measured. A previous poster [Nance, J.D., T.M. Thompson, J.H. Butler, J.W. Elkins, **The Radiativley Important Trace Species Data Recovery Project**, *Climate Monitoring and Diagnostics Laboratory Annual Meeting*, 2003] focused on the steps taken to upgrade the RITS dataset and recover lost data (see summaries elsewhere within this section). This poster focuses on the calibration issues and computational methods involved in producing final atmospheric concentration estimates from the RITS data (next section).

**Background**
- Between 1986 and 1990, three-channel RITS (Radiatively Important Trace Species) system gas chromatographs with electron capture detection (GC-ECD; shown at left) were installed at four CMDL-administered baseline observatories (Barrow, Mauna Loa, Samoa, and South Pole) and a fifth University of Colorado-administered site at Niwot Ridge, Colorado. An additional ship-based deployment spanning the tropics and mid-latitudes of the Pacific Ocean was executed in the winter/spring of 1989.
- RITS systems provided in situ measurements of N2O, CFC-12, CFC-11, CFC-113, CH3CCl3, and CCl4. They operated throughout the 1990s at a top atmospheric sample injection rate of 1 per hour. Working calibration standards were referenced to primary gravimetric standards in the laboratory and shipped to the ground stations for sampling alternately with the outdoor environment.

** ****Areas/Heights Database: Upgrade Summary**
- Chromatograms with recording errors (timestamp, sample-source label, channel ID) were identified, corrected, and reanalyzed.
- Poorly-analyzed chromatographic peaks (e.g. peaks that were misidentified, peaks missed due to an excessively-constrained analysis method, or peaks that were analyzed inconsistently for a period of time because of an insufficiently-constrained analysis method) were identified for reanalysis after addressing the software limitations that precluded the analysis difficulties.
- The areas/heights database was restructured to address problems related to its variant structure, its grouping of several sample injections under a single timestamp, and its lack of facility for flagging samples of poor quality. Restructuring was accomplished with the aid of a chromatogram inventory and revealed thousands of chromatograms that were previously overlooked or accidentally overwritten during processing. These chromatograms were processed into the new database.
- A combination of graphical and statistical methods was used to scan the entire restructured areas/heights database and flag data of poor quality because of performance problems with the equipment

**Chromatogram Standardization, Inventory and Storage Renewal**
- Shown at left are chromatograms from each of the three RITS channels. These plots are all from the same calibration sample injection – the first injection of the new millennium (GMT) at CMDL’s Samoa observatory.
- RITS chromatograms were formerly stored on a variety of outdated media. These have been fetched, thoroughly rechecked for quality control, corrected for recording errors involving the timestamp, sample-source label and channel ID, standardized to a common storage format, and finally inventoried prior to storage renewal on CDROM.