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 Organization

NO 76
Acronym UYRK
Name University of York
Address 1
Address 2 NCAS, University of York
Address 3 York YO10 5DD United Kingdom
Country/Territory United Kingdom of Great Britain and Northern Ireland
Website http://www.york.ac.uk/

 Contact(s)

Name Katie Read
Prefix Dr.
Email katie.read@york.ac.uk
Organization No 76
Organization acronym UYRK
Organization name University of York
Organization country/territory United Kingdom of Great Britain and Northern Ireland
Address 1 NCAS, Department of Chemistry
Address 2 University of York, Heslington
Address 3 York YO10 5DD United Kingdom
Country/territory United Kingdom of Great Britain and Northern Ireland
Tel +44-1904-322565
Fax +44-1904-322516
Last updated date 2024-04-04


Name Lucy Carpenter
Prefix Prof.
Email lucy.carpenter@york.ac.uk
Organization No 76
Organization acronym UYRK
Organization name University of York
Organization country/territory United Kingdom of Great Britain and Northern Ireland
Address 1 NCAS, Department of Chemistry
Address 2 University of York, Heslington
Address 3 York YO10 5DD United Kingdom
Country/territory United Kingdom of Great Britain and Northern Ireland
Tel
Fax
Last updated date 2024-04-04


 Background observation
 UTC
 ppb
 9999-12-31 00:00:00 - 9999-12-31 23:59:59: WMO CO X2014A
 2008-04-01 00:00:00 - 2015-05-31 23:59:59: Aerolaser 5001(VURF)
 2015-06-01 00:00:00 - 9999-12-31 23:59:59: Picarro G2401(CRDS)
 9999-12-31 00:00:00 - 9999-12-31 23:59:59: 7.5 (m)
 4 seconds
 Calibration of CO is performed with reference to a single gas standard containing a known amount of CO. It is well understood that the instrument behaves linearly.

Calibrations are performed every 9 hours and the data is applied to the subsequent 9 hours of measurements. The data is quality assured and if step changes are observed in the concentration data (e.g. due to humidity effects) then data is recalibrated or rejected accordingly. Instrument parameters (temperatures, flows, and gas pressures) are logged alongside those of the concentrations and used to diagnose problems. Instrument sensitivity is monitored and when it drops below 15Hz/ppbV a thorough cleaning of the instrument is performed.

The carbon monoxide measurements are fully traceable to the international Global Atmospheric Watch (GAW) scale (currently NOAA/ESRL WMO-2014). This means that the gas calibration standards used to calculate the final concentrations are referenced to a common standard held at the NOAA/ESRL laboratory. To ensure this is upheld, the designated world calibration centre for Carbon Monoxide: WCC-Empa (http://www.empa.ch/plugin/template/empa/*/7571), carries out regular audits of the measurements using travelling standards.

For more information please see the report from the most recent of these audits:

http://www.wmo.int/pages/prog/arep/gaw/documents/CVO_2012.pdf
 Aerolaser . Data Treatment
Zero data are removed and analysed off-line (average and standard deviation.
The calibration data is also removed (inf data, filter using sensitivity column). Sometimes not all the data is flagged as inf so needs to be checked. The database is checked for any other potential problems to the data.

During a power cut the logger records noise and so a very small signal is observed. This is not a background so does not need to be subtracted from the main data. Comparisons can always be made with the ad logged data if in doubt.
If the instrument has been off for any time it is allowed a two hour warm-up period and this data is removed.

If the instrument experiences a large change (> 5%) in sensitivity during a calibration (perhaps as a result of a water droplet finding its way into the instrument), this is seen in a sudden drop in concentration. Once the instrument has been calibrated again the data recovers. The data for this period is usually removed or else the appropriate calibration data is applied.

The Aerolaser instrument is not well insulated therefore is affected by sudden changes in temperature. Data when the laboratory temperature has changed rapidly during calibrations needs to be either removed or adjusted using calibration data which has been collected when the lab temperature is stable.
Considering the treatment of outliers, data <40ppbV and >200ppbV are removed before submission to database. A concentration of 250 ppbv may indicate lab air leak.

Picarro Data Treatment
Calibration data is removed and the 4 second data is averaged into minute data.
Considering the treatment of outliers, data <40ppbV and >200ppbV are removed before submission to database. A concentration of 250 ppbv may indicate lab air leak.
 [Hourly] Zero, calibration and invalidated data is removed prior to averaging. Hourly data is obtained by averaging all the data within a 1 hour period for example between 00:00 - 01:00. Standard deviation and number of points used to obtain the average are provided.
 [Daily] Zero, calibration and invalidated data is removed prior to averaging. Daily data is obtained by averaging all the data within a 24 hour period for example between 01/01/14 00:00 - 02/01/2014 01:00. Standard deviation and number of points used to obtain the average are provided.
 [Monthly] Zero, calibration and invalidated data is removed prior to averaging. Daily data is obtained by averaging all the data within a 24 hour period for example between 01/01/14 00:00 - 01/02/2014 01:00. Standard deviation and number of points used to obtain the average are provided.
 Error Flag = 0 Good data
Error Flag = 1 Reduced quality data
Error Flag = 2 Below detection limit
Error Flag = 3 Invalid or missing data
 Valid: 0
 Valid: 1
 Valid: 2
 Invalid: 3
 Operational/Reporting
 Aerolaser CO
Measuring range: up to 100,000.00 ppbV
Detection limit: < 0.80 ppbV at Integration time = 10 s
Sensitivity: about 30 to 100 counts/ppbV

Picarro CO
Measuring range: 0 - 5 ppm
Precision (5 sec / 5 min / 60 min, 1σ) 15 ppb /1.5 ppb / 1 ppb
Max Drift at STP (over 24 hrs / 1 month) 10 ppb /50 ppb
Max Uncertainty using Reference Gas (1 hr average, 2σ) < 2 ppb

CO is sampled through 10m of 1" of teflon tubing followed by 3m of 1" stainless steel tubing and then finally 2m of 1/8" stainless steel tubing. The air passes through a nafion dryer (PERMAPURE) and a teflon filter before it enters the instrument.

From August 2010, the stainless steel inlet was replaced with a 40mm diameter heated glass inlet. The air then passes through 2m of 1/8" stainless steel tubing. The air passes through a nafion dryer (PERMAPURE) and a teflon filter before it enters the instrument.

Since June 2015, a new instrument was installed to measure CO. The Picarro G2401 (utilising Cavity Ringdown Spectroscopy) samples from the same manifold but the sample is not dried before entering the instrument.

Since October 2019 the sample has been dried using a nafion drier as we have found that since a return to the manufacturer the water correction is now not acceptable.
 Wind direction: 1
 Wind speed: 1
 Relative humidity: 1
 Precipitation amount: 0
 Air pressure: 1
 Air temperature: 1
 Dew point temperature: 0
 Sea water temperature: 0
 Sea surface water temperature: 0
 Sea water salinity: 0
 Sea surface water salinity: 0
Meteorological data may remain as first provided, even when greenhouse gas data are updated.
 
No DOI available

 Related information

Format Text (WDCGG Data Format Table, WDCGG Meteorological Data Format Table), NetCDF
Relation List (Is Part Of) All CO data contributed to WDCGG by GAW stations and mobiles by 2024-09-24
All CO data contributed to WDCGG by GAW stations and mobiles by 2023-09-13
All CO data contributed to WDCGG by GAW stations and mobiles by 2022-09-05
All CO data contributed to WDCGG by GAW stations and mobiles by 2021-08-27
All CO data contributed to WDCGG by GAW stations and mobiles by 2020-09-28
All CO data contributed to WDCGG by GAW stations and mobiles by 2019-09-19
All CO data contributed to WDCGG by GAW stations and mobiles by 2018-10-25
Geolocation Point
Latitude (north: +; south: -) 16.864025
Longitude (east: +; west: -) -24.867519

 GAW Data Policy

"For Scientific purposes, access to these data is unlimited and provided without charge. By their use you accept that an offer of co-authorship will be made through personal contact with the data providers or owners whenever substantial use is made of their data. In all cases, an acknowledgement must be made to the data providers or owners and to the data centre when these data are used within a publication."

 Citation format

This format is an example of the WDCGG standard citation.
Please follow the citation format which the data providers or owners indicate.
Katie Read (UYRK), Lucy Carpenter (UYRK), Atmospheric CO at Cape Verde Atmospheric Observatory by University of York , dataset published as CO_CVO_ surface-insitu_UYRK_data1 at WDCGG, ver. 2024-04-04-0952 (Reference date*: YYYY/MM/DD)

* As the reference date, please indicate the date you downloaded the files.

 Reference(s)

1  Read, K. A., J. D. Lee, A. C. Lewis, S. J. Moller, L. Mendes, and L. J. Carpenter, Intra-annual cycles of NMVOC in the tropical marine boundary layer and their use for interpreting seasonal variability in CO, J. Geophys. Res., 114, D21303, doi:10.1029/2009JD011879, 2009.
2  Cape Verde Atmospheric Observatory Webpage: https://www.ncas.ac.uk/index.php/en/cvao-home
3  The designated world calibration centre for Carbon Monoxide: WCC-Empa (https://www.empa.ch/web/s503/wcc-empa), carries out regular audits of the measurements using travelling standards.

For more information please see the report from the most recent of these audits:

http://www.wmo.int/pages/prog/arep/gaw/documents/CVO_2012.pdf
4  Read, K.A. et al., Extensive halogen-mediated ozone destruction over the tropical Atlantic Ocean, Nature, 453, 1232-1236, 2008.