Systematic errors in global air-sea CO2 flux caused by temporal averaging of sea-level pressure
Item
Title (Dublin Core)
Systematic errors in global air-sea CO2 flux caused by temporal averaging of sea-level pressure
Description (Dublin Core)
Long-term temporal averaging of meteorological data, such as wind speed and air pressure, can cause large errors in air-sea carbon flux estimates. Other researchers have already shown that time averaging of wind speed data creates large errors in flux due to the non-linear dependence of the gas transfer velocity on wind speed (Bates and Merlivat, 2001). However, in general, wind speed is negatively correlated with air pressure, and a given fractional change in the pressure of dry air produces an equivalent fractional change in the atmospheric partial pressure of carbon dioxide (pCO<sub>2air</sub>). Thus low pressure systems cause a drop in pCO<sub>2air</sub>, which together with the associated high winds, promotes outgassing/reduces uptake of CO<sub>2</sub> from the ocean. Here we quantify the errors in global carbon flux estimates caused by using monthly or climatological pressure data to calculate pCO<sub>2air</sub> (and thus ignoring the covariance of wind and pressure) over the period 1990-1999, using two common parameterisations for gas transfer velocity. Results show that on average, compared with estimates made using 6 hourly pressure data, the global oceanic sink is systematically overestimated by 7% (W92) and 10% (WM99) when monthly mean pressure is used, and 9% (W92) and 12% (WM99) when climatological pressure is used.
Creator (Dublin Core)
Kettle, H.
Merchant, C. J.
Date (Dublin Core)
2018-06-28
Type (Dublin Core)
Text
Format (Dublin Core)
application/pdf
Identifier (Dublin Core)
10.5194/acp-5-1459-2005
https://acp.copernicus.org/articles/5/1459/2005/
Source (Dublin Core)
eISSN: 1680-7324
Language (Dublin Core)
eng
