Temporal and spatial variations in the atmospheric column inventory of CO2 due to air-sea gas exchange: estimates from an eddying ocean model

Daiwei Wang, MIT, daiwei@mit.edu (Presenter)
Chris Nigel Hill, MIT, cnh@mit.edu
Holger Brix, UCLA, hbrix@ucla.edu
Dimitris Menemenlis, JPL, dimitris.menemenlis@jpl.nasa.gov
Stephanie Dutkiewicz, MIT, stephd@ocean.mit.edu
Michael Follows, MIT, mick@mit.edu
Oliver Jahn, MIT, jahn@mit.edu

At any given point the atmospheric column inventory of CO2 over the ocean can change due to divergence in lateral transport of CO2 in the atmosphere and air-sea exchanges at the sea surface. As part of the NASA Carbon Monitoring System pilot project we have diagnosed air-sea exchanges of CO2 from an eddying ocean model constrained with observations from 2009 and 2010. The resulting flux patterns show temporal and spatial variation on time scales ranging from those of synoptic meteorology to interannual. Decomposing the variation of fluxes into different temporal bands reveals the contributions of different driving mechanisms.

We focus our analysis on the North Atlantic region from a global MITgcm ocean data assimilation experiment, with an explicitly resolved ecosystem and carbonate chemistry module, undertaken as part of the ECCO2 project. Sub- seasonal fluxes correlate strongly with forcing by synoptic meteorology, but are modulated by the underlying ocean state. Magnitudes are modulated somewhat by seasonal variations in sea-surface conditions and by standing patterns of ocean circulation. The results show characteristic spatial and temporal scales. The magnitude of the sub-seasonal terms (equivalent to ± 0.25 g C / m2 / d ) is below the current observing threshold of NASAs upcoming remote sensing mission, OCO-2 (approximately a 1ppmv column integral change between 16 day windows and over a rough area of 500km x 500km). Sub-seasonal anomalies are, however, significant relative to estimates of global average ocean uptake of 1.7e-2 g C / m2 / d and of the same order of magnitude as the mean regional fluxes estimated from climatology (which range from 0 to 0.36 g C / m2 / d) for the North Atlantic. Patterns are distinctive with strong spatial and temporal correlations -- suggesting that knowledge of time-dependent atmosphere and ocean processes could provide additional information on the expected variability between sequences of retrievals over the ocean.

Presentation Type:  Poster

Session:  Coupled Processes at Land-Atmosphere-Ocean Interfaces   (Mon 4:00 PM)

Associated Project(s): 

• Related Activity

Poster Location ID: 68