Certainly, the specific energy relations for any specific storm must be considered
separately and as you suggest, there are a number of variables to consider. It has
been quite well established in a number of articles appearing is JGR and other
geophysical magazines, however, that a large percentage of the LOD variation is
probably due to meteorological effects, so, at least in a temporary sense, the
effects around the world do not cancel out. If you are interested in this topic,
papers authored or co-authored by Dr. John Wahr, a well respected physicist
are a good place to start.