Air-sea CO sub(2) fluxes in the near-shore and intertidal zones influenced by the California Current

• Published in: Journal of geophysical research. Oceans 2013-10, Vol.118 (10), p.4795-4810
• Main Authors: Reimer, Janet J, Vargas, Rodrigo, Smith, Stephen V, Lara-Lara, Ruben, Gaxiola-Castro, Gilberto, Martin Hernandez-Ayon, J, Castro, Angel, Escoto-Rodriguez, Martin, Martinez-Osuna, Juan
• Format: Article
• Language: English
• Subjects: Carbon; Carbon dioxide; Coastal; Fluxes; Marine; Oceans; Offshore; Seasons; Upwelling
• ISSN: 2169-9275; 2169-9291
• DOI: 10.1002/jgrc.20319

The study of air-sea CO sub(2) fluxes (FCO sub(2)) in the coastal region is needed to better understand the processes that influence the direction and magnitude of FCO sub(2) and to constrain the global carbon budget. We implemented a 1 year (January through December 2009) paired study to measure FCO sub(2) in the intertidal zone (the coastline to 1.6 km offshore) and the near-shore (3 km offshore) off the north-western coast of Baja California (Mexico); a region influenced by year-round upwelling. FCO sub(2) was determined in the intertidal zone via eddy covariance; while in the near-shore using mooring buoy sensors then calculated with the bulk method. The near-shore region was a weak annual net source of CO sub(2) to the atmosphere (0.043 mol CO sub(2) m super(-2) y super(-1)); where 91% of the outgassed FCO sub(2) was contributed during the upwelling season. Sea surface temperature (SST) and Delta pCO sub(2) (from upwelling) showed the strongest relationship with FCO sub(2) in the near-shore, suggesting the importance of meso-scale processes (upwelling). FCO sub(2) in the intertidal zone were up to four orders of magnitude higher than FCO sub(2) in the near-shore. Wind speed showed the strongest relationship with FCO sub(2) in the intertidal zone, suggesting the relevance of micro-scale processes. Results show that there are substantial spatial and temporal differences in FCO sub(2) between the near-shore and intertidal zone; likely a result of heterogeneity. We suggest that detailed spatial and temporal measurements are needed across the coastal oceans and continental margins to better understand the mechanisms which control FCO sub(2), as well as reduce uncertainties and constrain regional and global ocean carbon balances. Spatial variation influences CO2 flux estimates in coastal regions . Different processes control ocean CO2 flux during different seasons/locations