Statistical significance test of Hilbert-Huang transformation

Hello,

I am using empirical mode decomposition and Hilbert-Huang transformation to detect trend of sea level rise. However, I need to perform statistical significance test to identify the suitability of the intrinsic mode functions (IMFs) and residuals. Matlab provides instantaneous energy at each point in the IMF. But I don't know the way to use instantaneous energy at each point to mean normalized energy. How I can estimate mean normalized energy and mean period of each IMF to perform significance test of IMFs?

Thanks in advance.