Multifractal spectra of chemical fields in fluid flows

In the filamental phase of reactions embedded in fluid flows, where the concentration distribution is strongly fluctuating, we show that a chemical measure can be defined based on the absolute value of the concentration gradients. We express the generalized dimensions in terms of the roughness exponents of the structure functions as well as of the cancellation exponents of the chemical concentration. This measure is of basically different character than the natural distribution of the passive advection. It is similar to the SRB measures of dissipative systems, although the advection problem is area preserving. This approach is shown to be a useful tool in analyzing sea surface temperature anomalies.