Statistics of local temperature dissipation in high Rayleigh number convection

We study the statistics of the local temperature dissipation in high Raylei gh number convection. We find that its probability distribution deviates fr om a lognormal, although very low order moments can be approximated by a lo gnormal distribution. Instead, the moments satisfy a hierarchy similar to t hat proposed by She and Leveque [Phys. Rev. Lett. 72, 336 (1994)] for the l ocal energy dissipation. Moreover, the moments scale with the separation ti me. No change in the scaling behavior is observed when the Bolgiano scale i s crossed, indicating that the statistics have the same nature in the buoya ncy-driven and the inertia-driven regimes.