P-5

Conservation raw on the product between forward and adjoint variables and its use for tracing of water mass.

Yosuke Fujii (JMA/MRI) , Humio Mitsudera (Hokkaido University/ILTS) , Masafumi Kamachi (JMA/MRI)

The definition of an adjoint model guarantees that integration of a product between a forward variable evolving according to a forward model and an adjoint variable evolving according to its adjoint model over the model domain is conserved in time. The product can, then, be used as density of tracer which travels from origin to destination areas in a certain migration period if we adopt an adevective-diffusive model and its adjont model. The conservation property guarantees that the total amount of the tracer is conserved. This method is applied to identification of the pathway of the North Pacific Intermediate Water (NPIW) and indicates that NPIW goes across the Kuroshio Extension around the Shatsky Rise at 160E. We also use the method to identify the pathway of warm water originated to the Kuroshio which finally reaches the Bering Sea. This method can be also applied to air and other general fluid masses.