NCEO Theme 2 Sub theme 6: Quantification of ocean biogeochemistry and carbon fluxes
Ocean colour (OC) or visible spectral radiometry deals with light re-emerging from the ocean after scattering and absorption of incident sunlight by particles, phytoplankton (energising photosynthesis), dissolved and detrital organic C compounds (from lysis, respiration and photo-chemical breakdown) and water. Remotelysensed OC data provides an integrated quasi-steady state observation of the whole of the global ocean and all
types of ocean environments (seasonally-variable nutrient & light climates): oligotrophic gyres; equatorial ecosystems; mid and high-latitude, seasonally-productive systems; highly-productive upwelling and convergent zones. Primary production (PP) derived from OC data gives an estimate of the total C sequestered by phytoplankton (~35-70 Gt C yr-1
). Hitherto EO-based PP models have used chlorophyll (Chla) as the state variable. New methods invoke Inherent Optical Properties (IOPs; the spectral absorption &
backscattering of the ocean). Using IOP models and IOP-OC data, we will describe the pelagic ocean C-cycle, with improved PP models, re-cycling rates and respiration, to:
(i) determine phytoplankton function types (PFTs) used in ecosystem models; (ii) provide parameter data for ecosystem models; (iii) partition the pelagic C-pool into particulate, dissolved, organic and inorganic components.
|Keywords:||NCEO, carbon, biogeochemistry|
|Previously used record identifiers:||
More Information (under review)
Work description and methodology
- i) Partitioning the ocean organic carbon budget 10
- a) Derive phytoplankton, detrital and dissolved components of the pelagic C-pool from IOP-OC data.
- b) Develop statistical models linking organic C in various components to production and PFTs.
- c) Determine seasonal, inter-annual, intra-decadal and regional variability in PFTs and their relationship to physical-chemical drivers.
ii) Improved estimates of marine PP and rate processes from OC data
- a) Develop new and export PP algorithms to quantify the transfer of C through the pelagic ecosystem and ‘permanent’ sequestration from the atmosphere.
- b) Quantify relationships between in situ PQE data and Chl & bio-optical indicators from EO data.
- c) Use EO and in situ data to quantify the variability in PQE in phytoplankton communities (PFT estimates) and physical-chemical drivers (light, temperature, nutrients, stratification, turbulence).
- d) Determine the PFT-specific P:R balance from EO estimates of PP and published data for respiration.
- e) Apply EO estimates of global P:R balance to partition the ocean into regions dominated by autotrophic or heterotrophic processes.
- a) Global & regional (N Atlantic/shelf sea) climatologies of PFTs, coloured dissolved organic matter (CDOM), particulate-C and particle size concentration.
- b) Quantified global & regional estimates of primary production (GPP, NPP, New-P, f-ratio) & C-export.
- c) Global and regional climatologies of photosynthetic parameters (e.g. PQE).
- d) Improved estimates of global and regional autotrophic/heterotrophic balance.
Key links to other programmes and organisations
KT activities (DEFRA, EA, UKMO) include development of ecosystem monitoring products (e.g. CDOM in river runoff, PFTs in relation to food for fish stocks, HABs and nuisance blooms, baseline maps and decadal changes in phytoplankton composition). Obvious benefit to QUEST C-cycle modelling. Oceans 2025 (NERC Marine Centres research) is an associated project, providing in situ data (AMT; coastal observations).
|NCEO Theme 2 details|