Cap Verde

The Cape Verde Atmospheric Observatory (CVAO), at Calhau on the island of São Vicente. The CVAO is a World Meteorological Organisation-Global Atmospheric Watch (WMO-GAW) global station and provides quality-assured atmospheric data.

An Aero-Laser AL5001 instrument for the measurement of carbon monoxide mixing ratios in background air has been installed at the National Centre for Atmospheric Science (NCAS) Cape Verde Atmospheric Observatory (CVAO) since October 2006 and there are no plans for the measurements to stop in the foreseeable future. At the University of York we also have an AL5002 instrument which is used for shorter deployments (e.g. for NAMBLEX and OP3 and has in the past been used as a back-up for both the Cape Verde system and the FAAM aircraft system. 

The aim of the project is to monitor the background concentration of CO (along with other trace gases) in the tropical marine boundary layer, to gain increased understanding of the oxidation capacity in this region.  The CVAO site is a “Global” Global Atmospheric Watch site which means that it meets the requirements to provide data required to address environmental issues of global scale and importance.

Some of these requirements include the following:

  1. The station location is regionally representative and is normally free of the influence of significant local pollution sources.
  2. There are adequate power, air conditioning, communication and building facilities to sustain long term observations with greater than 90% data capture (i.e. <10% missing data). 
  3. The GAW CO observation made is of known quality and linked to the GAW CO Primary Standard. 
Inside the CVAO station.

CO data is presently submitted in near-real-time to the MACC (Monitoring Atmospheric Composition and Climate) project which is part of the European GMES (Global Monitoring for Environment and Security) programme. The concentration of CO in the marine boundary layer is mainly controlled by the hydroxyl radical (OH) concentration. Deviations occur as a result of long-range transport from more polluted areas and the occasional biomass burning input from the Canary Islands.

Instrument rack containing an AL5001 CO-monitor.

Publications

L.J. Carpenter, Z.L. Fleming, K.A. Read, J.D. Lee, S.J. Moller, J. Hopkins, R. Purvis, A.C. Lewis, K. Müller, B. Heinold, H. Herrmann, K. Wadinga Fomba, D. van Pinxteren, C. Müller, I. Tegen, A. Wiedensohler, T. Müller, N. Niedermeier, E.P. Achterberg, M.D. Patey, E.A. Kozlova, M. Heimann, D.E. Heard, J.M.C. Plane, A.S. Mahajan, H. Oetjen, S. Vaughan, S.R. Arnold, T. Ingham, D. Stone, .L. Whalley, M. Evans, M.J. Pilling, R.J. Leigh, P.S. Monks, A. Karunaharan, J. Tschritter, D. Pöhler, U. Frieß, R. Holla, L. Mendes, H. Lopez, B. Faria, A.J. Manning and D.W.R. Wallace, Seasonal characteristics of tropical marine boundary layer air measured at the Cape Verde Atmospheric Observatory, J. Atmos. Chem. 67 (2010) 87 http://www.springerlink.com/content/x0668g1768785552/
J.D. Lee, S.J. Moller, K.A. Read, A.C. Lewis, L. Mendes and L.J. Carpenter, Year-round measurements of nitrogen oxides and ozone in the tropical North Atlantic marine boundary layer, J. Geophys. Res. 114 (2009) D21302 http://www.agu.org/pubs/crossref/2009/2009JD011878.shtml
A.S. Mahajan, J.M.C. Plane, H. Oetjen, L. Mendes, R.W. Saunders, A. Saiz-Lopez, C.E. Jones, L.J. Carpenter and G.B. McFiggans, Measurement and modelling of tropospheric reactive halogen species over the tropical Atlantic Ocean, Atmos. Chem. Phys. 10 (2010) 4611 http://www.atmos-chem-phys.net/10/4611/2010/
K.A. Read, 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 (2009) D21303 http://www.agu.org/pubs/crossref/2009/2009JD011879.shtml
K.A. Read, A.S. Mahajan, L.J. Carpenter, M.J. Evans, B.V.E. Faria, D.E. Heard, J.R. Hopkins, J.D. Lee, S.J. Moller, A.C. Lewis, L. Mendes, J.B. McQuaid, H. Oetjen, A. Saiz-Lopez, M.J. Pilling and J.M.C. Plane, Extensive halogen-mediated ozone destruction over the tropical Atlantic Ocean, Nature Lett. 453 (2008) 1232 http://www.nature.com/nature/journal/v453/n7199/full/nature07035.html
L.K. Whalley, K.L. Furneaux, A. Goddard, J.D. Lee, A. Mahajan, H. Oetjen, K.A. Read, N. Kaaden, L.J. Carpenter, A.C. Lewis, J.M.C. Plane, E.S. Saltzman, A. Wiedensohler and D.E. Heard, The chemistry of OH and HO2 radicals in the boundary layer over the tropical Atlantic Ocean, Atmos. Chem. Phys. 10 (2010) 1555 http://www.atmos-chem-phys.net/10/1555/2010/
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