Acronym: OCB-038
Program: Ocean Carbon & Biogeochemistry [OCB]
Url: Project Web Site
Start date:
End date:
Geolocation: Southern Ocean
Description:

from www.us-ocb.org

The Southern Ocean represents a vast gap in our understanding of global air-sea CO2 fluxes. We propose a data synthesis effort, incorporating model-generated transport fields, to provide satellite-based maps of pCO2 with superior spatial and temporal coverage compared to the current climatologies produced by interpolation of sparse in situ observations. These maps, combined with satellite measurements of wind speed and an improved understanding of the gas transfer velocity, will serve two important purposes: (1) they will significantly improve our estimates of regional and total CO2 fluxes, and (2) they will serve as a validation products for current and future models of Southern Ocean biogeochemistry.

Our approach consists of four steps: 1. Objective identification of provinces. Given the vast area and diverse sub-regions, predictions of pCO2 will be more accurate if we develop a suite of regional (and perhaps seasonal) algorithms rather than one algorithm for the entire Southern Ocean. Satellite measurements of SST, chlorophyll, wind stress and sea surface height can be used to determine regions of the ocean that are similar with respect to their physics and biology via a self-organizing map (SOM) analysis [Grant et al., 2006; Saraceno et al., 2006]. 2. Develop regional algorithms for pCO2. Using a large and growing database made available to us by Taro Takahashi, we will use techniques such as multiple linear regressions applied in biogeochemical regimes defined by the SOM analyses to relate pCO2 to remotely observable parameters such as SST, chlorophyll and sea surface height. Currently funded work has already achieved significant success towards this goal for coastal Oregon and the entire US west coast. 3. Develop improved, model-based interpolation schemes for sparse data. While the MLR/SOM approach has shown promise, it is purely empirical and lacks clear mechanistic underpinnings. Simple relationships between instantaneous observations of pCO2 and remotely observable parameters are often elusive because pCO2 is strongly controlled by the history of heating/cooling, mixing, gas exchange, and biological activity experienced by a water mass, as opposed to these parameters’ current values. By incorporating the sparse observations with model-generated surface flow fields and remote sensing data, we can parameterize the historical forcing experienced by any water mass with observed pCO2. These history-parameterizations and pCO2 observations can be used for further algorithm development, which can then be applied to any location with remote sensing data and modeled flow-fields to predict pCO2 distributions at greatly improved spatial and temporal resolution. 4. Calculation of air-sea CO2 fluxes. Maps of Southern Ocean pCO2 produced by application of these algorithms can be combined with satellite winds to calculate the air-sea CO2 flux. Southern Ocean GasEx is specifically aimed at improved parameterizations of the gas transfer velocity as a function of wind speed for the Southern Ocean. This enhanced understanding, combined with significantly improved maps of pCO2 will provide calculations of Southern Ocean CO2 fluxes with unprecedented accuracy and coverage.

---

More information about project Remote sensing of Southern Ocean air-sea CO2 fluxes
Funding
Datasets associated with Remote sensing of Southern Ocean air-sea CO2 fluxes
Platform deployments associated with Remote sensing of Southern Ocean air-sea CO2 fluxes
People associated with Remote sensing of Southern Ocean air-sea CO2 fluxes