An adjoint sensitivity study of chlorofluorocarbons in the North Atlantic
MetadataShow full item record
Adjoint sensitivities of CFC-11 concentrations and CFC-11/CFC-12 ratio ages in a North Atlantic general circulation model are analyzed. These sensitivities are compared with those of spiciness, T − (β/α) S, where α, β are the thermal and haline expansion coefficients, respectively. High-sensitivity fields are candidates for providing the most powerful constraints in the corresponding inverse problems. In the dual (adjoint) solutions all three variables exhibit the major ventilation pathways and define the associated timescales in the model. Overall, however, spiciness shows the highest sensitivity to the flow field. In the North Atlantic Deep Water, sensitivities of CFC properties and spiciness to the isopycnal mixing and thickness diffusion are of the same order of magnitude. In the lower subtropical thermocline, sensitivities of CFC properties to the isopycnal mixing and thickness diffusion are higher. The utility of this sensitivity is undermined by the need to reconstruct their boundary conditions. Given the influence of T, S measurements on the density field, they produce the most powerful constraints on the model on the large scale. It still remains possible, however, that transient tracers can provide a larger relative information content concerning the mixing process between the near-surface boundary layer and the thermocline but dependent upon the ability to reconstruct accurate initial and boundary conditions.
Author Posting. © American Geophysical Union, 2004. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 109 (2004): C01007, doi:10.1029/2003JC002014.
Showing items related by title, author, creator and subject.
Li, Xingwen; McGillicuddy, Dennis J.; Durbin, Edward G.; Wiebe, Peter H. (2006-03-14)An adjoint data assimilation approach was used to quantify the physical and biological controls on Calanus finmarchicus N3 to C stages on Georges Bank and its nearby environs. The mean seasonal cycle of vertically-averaged ...
Towards an integrated observation and modeling system in the New York Bight using variational methods. Part II : repressenter-based observing strategy evaluation Zhang, Weifeng G.; Wilkin, John L.; Levin, Julia C. (2009-09-23)As part of an effort to build an integrated observation and modeling system for the New York Bight, this study explores observing system design using a representer-based method. The Representer of a single observation ...
Thermohaline structure in the California Current System : observations and modeling of spice variance Todd, Robert E.; Rudnick, Daniel L.; Mazloff, Matthew R.; Cornuelle, Bruce D.; Davis, Russ E. (American Geophysical Union, 2012-02-03)Upper ocean thermohaline structure in the California Current System is investigated using sustained observations from autonomous underwater gliders and a numerical state estimate. Both observations and the state estimate ...