The OceanFlux Greenhouse Gases methodology for deriving a sea surface climatology of CO<sub>2</sub> fugacity in support of air–sea gas flux studies
Climatologies, or long-term averages, of essential climate variables are useful for evaluating models and providing a baseline for studying anomalies. The Surface Ocean CO<sub>2</sub> Atlas (SOCAT) has made millions of global underway sea surface measurements of CO<sub>2</sub>...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2015-07-01
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| Series: | Ocean Science |
| Online Access: | http://www.ocean-sci.net/11/519/2015/os-11-519-2015.pdf |
| Summary: | Climatologies, or long-term averages, of essential climate variables are
useful for evaluating models and providing a baseline for studying anomalies.
The Surface Ocean CO<sub>2</sub> Atlas (SOCAT) has made millions of global underway
sea surface measurements of CO<sub>2</sub> publicly available, all in a uniform
format and presented as fugacity, <i>f</i><sub>CO<sub>2</sub></sub>. As <i>f</i><sub>CO<sub>2</sub></sub> is
highly sensitive to temperature, the measurements are only valid for the
instantaneous sea surface temperature (SST) that is measured concurrently
with the in-water CO<sub>2</sub> measurement. To create a climatology of
<i>f</i><sub>CO<sub>2</sub></sub> data suitable for calculating air–sea CO<sub>2</sub> fluxes, it
is therefore desirable to calculate <i>f</i><sub>CO<sub>2</sub></sub> valid for a more
consistent and averaged SST. This paper presents the OceanFlux Greenhouse
Gases methodology for creating such a climatology. We recomputed SOCAT's
<i>f</i><sub>CO<sub>2</sub></sub> values for their respective measurement month and year
using monthly composite SST data on a 1° × 1° grid
from satellite Earth observation and then extrapolated the resulting
<i>f</i><sub>CO<sub>2</sub></sub> values to reference year 2010. The data were then spatially
interpolated onto a 1° × 1° grid of the global
oceans to produce 12 monthly <i>f</i><sub>CO<sub>2</sub></sub> distributions for 2010,
including the prediction errors of <i>f</i><sub>CO<sub>2</sub></sub> produced by the spatial
interpolation technique. The partial pressure of CO<sub>2</sub> (<i>p</i><sub>CO<sub>2</sub></sub>)
is also provided for those who prefer to use <i>p</i><sub>CO<sub>2</sub></sub>. The CO<sub>2</sub>
concentration difference between ocean and atmosphere is the thermodynamic
driving force of the air–sea CO<sub>2</sub> flux, and hence the presented
<i>f</i><sub>CO<sub>2</sub></sub> distributions can be used in air–sea gas flux calculations
together with climatologies of other climate variables. |
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| ISSN: | 1812-0784 1812-0792 |