CO2 flux estimation errors associated with moist atmospheric processes
Item
Title (Dublin Core)
CO2 flux estimation errors associated with moist atmospheric processes
Description (Dublin Core)
Vertical transport by moist sub-grid scale processes such as deep convection is a well-known source of uncertainty in CO<sub>2</sub> source/sink inversion. However, a dynamical link between vertical transport, satellite based retrievals of column mole fractions of CO<sub>2</sub>, and source/sink inversion has not yet been established. By using the same offline transport model with meteorological fields from slightly different data assimilation systems, we examine sensitivity of frontal CO<sub>2</sub> transport and retrieved fluxes to different parameterizations of sub-grid vertical transport. We find that frontal transport feeds off background vertical CO<sub>2</sub> gradients, which are modulated by sub-grid vertical transport. The implication for source/sink estimation is two-fold. First, CO<sub>2</sub> variations contained in moist poleward moving air masses are systematically different from variations in dry equatorward moving air. Moist poleward transport is hidden from orbital sensors on satellites, causing a sampling bias, which leads directly to small but systematic flux retrieval errors in northern mid-latitudes. Second, differences in the representation of moist sub-grid vertical transport in GEOS-4 and GEOS-5 meteorological fields cause differences in vertical gradients of CO<sub>2</sub>, which leads to systematic differences in moist poleward and dry equatorward CO<sub>2</sub> transport and therefore the fraction of CO<sub>2</sub> variations hidden in moist air from satellites. As a result, sampling biases are amplified and regional scale flux errors enhanced, most notably in Europe (0.43 ± 0.35 PgC yr<sup>−1</sup>). These results, cast from the perspective of moist frontal transport processes, support previous arguments that the vertical gradient of CO<sub>2</sub> is a major source of uncertainty in source/sink inversion.
Creator (Dublin Core)
Parazoo, N. C.
Denning, A. S.
Kawa, S. R.
Pawson, S.
Lokupitiya, R.
Date (Dublin Core)
2018-01-15
Type (Dublin Core)
Text
Format (Dublin Core)
application/pdf
Identifier (Dublin Core)
10.5194/acp-12-6405-2012
https://acp.copernicus.org/articles/12/6405/2012/
Source (Dublin Core)
eISSN: 1680-7324
Language (Dublin Core)
eng
