Notes on Shedding light on the ocean’s biological pump and twilight zone processes, a presentation given by K. Buesseler (07/17/09)

Biological pump

• Why it is important:
  • Impact on global carbon (C) cycle and climate
  • Rapid, yet inefficient transport
  • Food sources for ecosystems
• Variability of particulate organic carbon (POC):
  • Flux poorly understood even after 20 years
  • Even seasonal variability is hard to see
• Layered structure of chlorophyll: constant over the upper 60 m, shifted to constant and near zero below
• Definition of twilight zone: below the euphotic zone down to 1000 m

Shedding light

• Parameterize the vertical profile of POC flux:
  • Avoid the Martin curve
  • Need new metrics to compare biological pump
  • Synthesis is dependent on the metrics used
  • So far, no perfect metrics found
• New models with a minimum set of biological processes are needed:
  • Simple 1-D layered biological model containing (see Buesseler and Boyd, 2009) containing microbial solubilization, zooplantkon remineralization and vertical migration of zooplankton