Site

The Cape Verde Atmospheric Observatory is located at Calhau on a NW facing sandy beach on Sao Vicente, 16.848N, 24.871W, adjacent to the ocean, with the prevailing trade winds blowing directly off the ocean. There are no obvious major coastal features such as extensive shallows or large seaweed beds. Such a site offers a rare opportunity for ground-based studies of clean marine air, free from local coastal macrophyte interferences.

The scientific rationale for the Cape Verde location include:

i) The oxidation of methane, a potent greenhouse gas, occurs predominantly within the tropics owing to a combination of high water vapour and radiation which leads to high concentrations of hydroxyl radicals. High temperatures within the tropics enhance the oxidation of methane in this region with the result that ~75 % of methane oxidation occurs between 30°S and 30°N [Lawrence et al., 2001].

ii) The production and loss of tropospheric ozone, again an important climate gas, is dominated by activity within the tropics, due to the high photochemical activity [Horowitz et al., 2003].

iii) The injection of species into the stratosphere occurs predominantly within the tropics, so species which are able to perturb the stratospheric ozone chemistry must first be processed through the tropics [Bridgeman et al., 2000].

iv) Cape Verde is located in an area of massive dust transport from land to ocean, and is thus ideal for investigating impacts of dust on the marine ecosystem

v) The site is 'downwind' of an area of high primary productivity (the Mauritanian upwelling), thus a Cape Verde Observatory would provide unique information on links between upwelling and atmospheric changes.

Site plan

Trajectory footprint