Surface CO2 Concentraion: The dark blue line xCO2 seawater is a measure of the concentration of dissolved CO2 in surface seawater. The light blue line xCO2 air is a measure of the concentration of CO2 in air.

delta pCO2: The gray line delta pCO2 - the difference between the two values in the upper panel - indicates the direction and magnitude of gas transfer between the ocean and the atmosphere. When this value is negative (below the 0 line), the ocean is absorbing CO2 from the atmosphere. When it is positive (above the 0 line), the ocean is releasing CO2 to the atmosphere

Percent Oxygen Saturation: The blue line percent Oxygen Saturation is a relative measure of the oxygen content of seawater. If oxygen saturation is above 100%, the rate of photosynthesis usually exceeds the rate of respiration, while if it is less than 100%, respiration usually exceeds photosynthesis. In addition to these biological processes, oxygen saturation is affected by ocean mixing and gas exchange. The displayed values are used as qualitative data for the CO2 analysis. These oxygen data are not comparable to data that an in-situ oxygen sensor would provide.

Temperature: Seawater temperature at 15 m depth varies because of changes in heat flux between the atmosphere and ocean, variations in ocean currents, vertical mixing, and internal waves.

Salinity: Salinity at 15 m depth varies because of changes in evaporation and precipitation, variations in ocean currents, vertical mixing, and internal waves.

Density: Seawater density (sigma) depends primarily on the water's temperature and salinity. The density of surface seawater deviates only up to 3 percent from 1000 kg/m³. The oceanographer simplifies the density to sigma, the deviation from 1000 kg/m³:

Chlorophyll a: Chlorophyll a fluorescence is a measure of the concentration of phytoplankton in the ocean.

Turbidity: Turbidity (at a wavelength of 700 nm) is a measure of the amount of suspended particulate matter in the ocean. This includes both living (phytoplankton, microzooplankton), and non-living (marine snow) particles.

Nitrate Sensor: Our SUNA nitrate sensor measures dissolved inorganic nitrogen (mainly nitrate and nitrite) in seawater. Nitrate is an important nutrient source for phytoplankton growth.

Wind Stress: Winds above the sea surface have a major influence on ocean currents by pushing the water sideways, and on vertical mixing processes in the upper ocean layers by driving turbulent motions. The wind stress is the (horizontal) force exerted upon the ocean surface by the winds above it. It is given in units of force per area, e.g. Newton per square meter. Wind stress is rarely measured directly, but instead is derived from wind speed measurements through parameterizations. Here, we use the methodology proposed by Large & Pond (Journal of Physical Oceanography, 1981).