On Tue 2022-07-26T20:42:03-0400 Brooks Harris hath writ: > Can anyone elaborate on what these 'decadal variations' may be?
What they are is power in the spectrum of LOD at periods of decades that has been visible in the relatively good data from the past two centuries and which contributed to the inclusion of "non-gravitational" terms in the planetary theories of Newcomb and the lunar theories of Hill and Brown. Why they happen is harder to say since they probably originate in the weather of the core of the earth, but maybe not. See this Journees 2019 paper saying it may be crustal motion and ice https://syrte.obspm.fr/astro/journees2019/journees_pdf/SessionIV_2/SIDORENKOV_Nikolay.pdf Also in there that the earth had been getting less oblate, more spherical, through around year 2000 but maybe now is getting more oblate https://syrte.obspm.fr/astro/journees2019/journees_pdf/SessionIV_1/LIU_JiaCheng.pdf -- Steve Allen <s...@ucolick.org> WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m _______________________________________________ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
