NLC's and 5 day cycle

[janlameer]

Hi all

I've found two interesting pdf publications by the Swedish IRF institute (Kiruna) on the occurrence of NLC's.
Most interesting is the existence of a five day cycle in occurrence of NLC's. What also interests me is that the relationship with solar cycle activity is probably smaller than expected and not so direct.
You can find the pdf articles on:

http://www.irf.se/upatm/epubs/GRL_2002a.pdf

http://www.irf.se/upatm/epubs/JGR_2002a.pdf

greetings, JanL