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Cape Verde Observatory - University of York
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CO
continuous |
NOx
continuous |
O3
continuous |
VOCs *
continuous |
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| Category |
Air sampling observation (Marine boundary layer) |
| Sampling Type |
continuous |
| Sampling Height/Depth |
5 |
| Sampling and Analysis Frequency |
1 minute |
| Sampling Environment |
Tropospheric ozone is produced via the catalytic oxidation of carbon compounds in the presence of nitrogen oxides (NOx = NO + NO2), and has an additional smaller source from stratospheric influx of ozone into the free troposphere. Ozone is lost to the surface due to deposition and can be destroyed throughout the atmosphere by photochemical processes, predominantly via photolysis and the subsequent reaction of electronically excited oxygen atoms with water vapour. Ozone is formed predominantly in continental regions where there are sources of NOx, and is typically lost in marine regions where sources are small. Due to its high water vapour content, enhanced radiation field and large geographical extent, the tropical marine boundary layer is the most important global region for loss of ozone. |
| Measurement Method |
Light absorption analysis (UV) |
| Current status and history of Instruments |
The instrument (Thermo Scientific UV Ozone Analyser model 49i) was new in January 2006 and has been running continuously at the Observatory since October 2006.
A new instrument (Thermo Scientific UV Ozone Analyser model 49C was installed 14/02/09 - 15/05/09 whilst the original 49i was being repaired.
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| Description of Instruments |
http://www.thermo.com/com/cda/product/detail/1,1055,10122762,00.html
Range: 0-500 ppb Detection Limit: 0.5 ppb
Since it is an absolute measurement technique, the accuracy of the instrument is purely determined by the random error (or precision) and there is no assumed systematic error. The measurements show a 1 sigma standard deviation of 0.9 ppb for 10 second averaged data which, allowing for the dual cell photometer set-up, equates to a precision of 0.07 ppb for hourly averaged data. |
| Time Zone |
UTC |
| Data Period |
2006-10-01 - 2008-12-31 |
| Data Type |
hourly, daily, monthly |
| Parameter detail |
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| Other Descriptions for Sampling and Analyses |
Oozne is sampled through 5m of 1/4" teflon tubing at a flow rate of 1.5 L/min. The air passes through a teflon filter before it enters the instrument. |
| Scientific Aim |
To monitor the (increasing) background concentration of Ozone in the tropical Marine Boundary Layer, a region characterised by high water vapour (high OH), and high radiation. This data is particularly important for the validation of climate models. At present the region is an efficient daytime destroyer of Ozone but this is highly dependent on NOx concentrations which may increase over time leading to the region becoming less efficient at this process. |
| Supporting Contributor(s) |
Instituto Nacional de Meteorologia e Geofisica (INMG)
Delegação de S. Vicente
Monte, CP 15
Mindelo
Cape Verde
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| Last update |
2009-03-25 |
| Situation |
ongoing |
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This site is maintained by the Japan Meteorological Agency
in cooperation with the World Meteorological Organization
(Created : 2001/07/02 Modified : 2010/07/31)
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WMO World Data Centre for Greenhouse Gases
c/o Japan Meteorological Agency
1-3-4, Otemachi, Chiyoda-ku
Tokyo 100-8122, Japan
| Tel: |
+81-3-3287-3439 |
| Fax: |
+81-3-3211-4640 |
| E-mail: |
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WDCGG Data Submission and Dissemination Guide (PDF 1.2Mbyte)
WDCGG leaflet (PDF 2.7MByte, July 2008)