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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 |
| Sampling Type |
continuous |
| Sampling Height/Depth |
10 |
| Sampling and Analysis Frequency |
~ 1 hour time resolution for C2-C8 NMHC, DMS and o-voc including acetone, methanol, acetaldehyde. |
| Sampling Environment |
NMHC -mainly from anthropogenic emissions from fossil fuel combustion and natural gas production.
Acetone, acetaldehyde, methanol (oVOC) terrestrial anthropogenic sources from solvent use, industrial processing, and biomass burning, terrestrial biogenic from vegetation emissions.
The oVOC are also produced secondarily from NMHC.
ethene, propene, isoprene, acetaldehyde (and perhaps acetone) from the photochemical degradation of organic matter in the oceans.
DMS from phytoplankton in the oceans.
NMVOCs are removed from the atmosphere primarily by reaction with the hydroxyl radical OH and subsequent photo-oxidation of products ultimately to CO2 and H2O. A by-product of this oxidation (when NOx is present) is the formation of tropospheric ozone (O3) and other secondary pollutants including organic aerosols. Tropospheric O3 has been reported to be increasing both regionally and globally a result has been substantial endeavour to understand the role of longer range transport (e.g. transatlantic transport) of precursors such as CO; and NMVOC in determining O3 trends in remote environments. The strong chemical coupling between O3 and OH provides further impetus to understand what controls CO, NMVOC, and O3 in remote locations. Of particular significance are the remote tropical regions where the majority of CO and CH4 are chemically destroyed by OH. It is here where the atmospheric chemistry of air pollutants couples with climate drivers through the OH radical.
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| Measurement Method |
Gas Chromatography (FID) |
| Current status and history of Instruments |
Since October 2006 and ongoing.
The dual channel GC-FID and optic injector heating is from Agilent, UK. The rest of the instrumental set-up is from a combination of commercial and home-built elements including chillers, pelter controls, valves etc. |
| Description of Instruments |
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| Time Zone |
UTC |
| Data Period |
2006-10-01 - 2008-12-31 |
| Data Type |
daily, monthly |
| Parameter detail |
2-methyl-1,3-butadiene, 2-methylbutane, 2-methylpropene, acetaldehyde, acetone, acetylene, benzene, dimethylsulfide, ethane, ethene, methanol, n-butane, n-hexane, n-pentane, propane, propene |
| Other Descriptions for Sampling and Analyses |
The air sample is pulled through the main sampling manifold (6 m of 1” Teflon followed by 6 m of 1” stainless steel, residence time 4.5 s) using the main sample pump and a smaller pump pulls the sample through 1/8” stainless steel for the last 1 m to the instrument. Water is removed from the sample using a condensation trap held at -27° C. Ozone is not removed from the air sample. The trap used in this system is packed with the graphitic carbon adsorbents Carbopack B and Carboxen 1000 in series, a combination not thought to be affected by O3 contamination [Koppmann, 2007]. In addition the ambient levels of O3 observed at CVAO are extremely stable on an hour to hour basis (although do vary seasonally) with an annual maximum of ~50 ppbV [Lee et al., 2009] and it is with levels above 90 ppbV that O3 scrubbers are recommended [Koppmann, 2007]. |
| Scientific Aim |
NMVOC are useful proxys for the interpretation of measurements of species such as CO (and also CH4), sharing some common production and loss terms. Long-term measurements can be used as pointers towards seasonal changes of OH and for general characterisation of the air in this region. Measurements such as these particularly within the tropical regions are integral in the validation of the outputs of global atmospheric models. |
| Supporting Contributor(s) |
University of York, UK |
| Last update |
2010-01-28 |
| 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)