This thesis describes the development and field evaluation of new methods and instruments for autonomous measurements of CO2 partial pressure (pCO2) in the ocean. An autonomous profiling float conducted for the first time high resolution pCO2 measurements in the water column and at the surface in the tropical eastern North Atlantic. Along with time series data from the Cape Verde Ocean Observatory (CVOO) seasonal variability of CO2 and O2 air-sea fluxes was examined. Furthermore, episodic mesoscale oceanographic structures in the vicinity of CVOO were for the first time detected and described by means of different autonomous measurement approaches. These structures carried an extreme biogeochemical environment (subsurface anoxia), which has not been observed before in this region
