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Signatures of upscale and downscale energy cascades in QuikSCAT winds over the equatorial Pacific

Second-order and third-order structure functions (D2 and D3) have been calculated using the near-surface ocean winds over the equatorial Pacific Ocean measured by the SeaWinds scatterometer on the QuikSCAT satellite. From D2 and D3, ten-year climatologies are constructed for the scaling exponents of the kinetic energy, the kinetic energy amplitude, the vorticity-to-divergence ratio, and the skewness. According to turbulence theory, D2>0 (or equivalently, S>0) is the signature of an upscale energy cascade and D3<0 (S<0) is the signature of a downscale cascade. We find that over the cold-pool the signature is typically upscale, while over the warm-pool it is typically downscale. The warm- pool result appears to contradict work that finds organized tropical convection the result of upscale energy transfer. I will speculate on how the two can be resolved and invite others to do so as well.