The subtropical cell controls the large-scale transport of heat, freshwater, carbon, nutrients and dissolved O2 through the southeastern Pacific basin. These processes modulate chemistry and biology and the regional component of the climate variability. Models and field observations have shown that in the context of climate warming, the subtropical celda of the South Pacific is reinforced as a response to changes in surface winds on a large scale on the tropical Pacific. As well, it is expected that global warming directly affects the South Pacific by strengthening the degree of productivity. As the temperature of the upper layers increases, the stratification of oceanic water is reinforced, affecting the mixing of water masses and vertical diffusiveness in subtropical regions. In contrast, stronger coastal winds could increase vertical mixing and upwellings of eastern currents. It has been argued that coastal upwelling and transport by the Humboldt Current have intensified in recent decades and has been getting stronger on the scale of decades. This in turn has been modifying the properties of waters that participate in the subtropical cell and in an increase in the physical, biochemical and ecological gradients between the coastal and oceanic environments. The lower O2 content of the warmer ocean waters and the higher gradients between upwelling and stratified oceanic waters contributes to expanding waters low in O2/pH and high in pCO2, which affects biological communities and the biogeochemical cycles in these waters. To address this issue, new and novel observations will be combined with advanced regional numeric models. The observations come from expeditions and regular transects with gliders between the coast and the Juan Fernández Archipelago. The data will include temperature, salinity, O2 and other biochemical variables (e.g. pH, pCO2, nutrients, gases, and organic and inorganic carbon, including their isotopes: 12C, 13C, 14C, and 15N). We will also make a high-resolution analysis of the microstructure and the indices of turbulent mixing that allow calculating the vertical flows of salts, heat and relevant biogeochemical properties. These high-resolution data, together with historic data will allow for assessing annual and more frequent changes in meridional transport and in the physical and chemical properties in the thermocline and intermediate waters. This data will be used in refining models and in validating their outcomes. Different simulations will generate outcomes that will be introduced into regional models to assess the mechanisms that affect coastal upwelling, the generation of mesoscale eddies, regional circulation and the modification of water masses.
How do key functional groups of plankton adapt to chemical changes in oceans and how does this affect biochemical cycles?
What are the structures of communities and the biogeochemical characteristics of deep and abyssal waters of the southeastern Pacific?
What is the role of mesoscale activity on regulating energy-matter transfer and on the dynamics of ecosystems in oceanic waters?