Rick Salvador: Final LOD model performance update

Posted: April 11, 2021 by tallbloke in Celestial Mechanics, LOD, modelling, solar system dynamics

Talkshop readers will remember that as well as his work on modelling solar activity, Rick Salvador also built a planetary model to predict variation in Earth’s Length of Day (LOD). The model uses 13 frequencies derives from planetary and lunar motion to replicate changes in Earth’s spin rate.

Rick has retired from modelling now, so this is the final update on the model’s performance. The IERS LOD database was changed in early 2020, so the model performance update ends there. Over the last 4 years, Rick found that to keep it on track, he needed to add a -0.0006 second correction in June each year. The necessity for this is as yet unexplained and comments on possible reasons are encouraged.

Here’s a plot showing the original model in red, the model with the June -0.0006″ corrections in blue, and the observed LOD data in green.

I asked Rick if he had included a term for the 1799 year De Ropp cycle of Lunar variation and he hadn’t. He kindly took the trouble to add it in and got this result back to the earliest LOD estimates going back to 1630AD. The fit is quite good, with perhaps the hint of a ~200yr residual.

On behalf of everyone at the Talkshop, I’d like to thank Rick for the superb work he has done to advance the solar-planetary osciallation theory (SPOT). His 2013 solar activity prediction paper stands out as a landmark in the study of solar system dynamics, which is standing the test of time well. We wish him all the best for a long and enjoyable retirement with his family.

  1. Bloke down the pub says:

    I suppose the first question should be, what effect would be expected on climate of this variation in LOD?

  2. tallbloke says:

    It’s certainly an interesting question Bloke. I said to Judy Curry when she published her ‘stadium wave’ paper that I thought her LOD curve was at the wrong end of the sequence, and should be shown preceding rather than following all her other climatic indices.

    Of more interest to our solar-planetary theory, is understanding how orbits and spin rates are related.

  3. JB says:

    “Of more interest to our solar-planetary theory, is understanding how orbits and spin rates are related.”

    Pari Spolter’s The Gravitational Force of the Sun (1995) can assist there. After digesting her derived equations I came to the conclusion that the force acting on solar system bodies is the same acting on the sun, and does not derive directly from the sun. There is a direct link that I can see between orbital speed and axial speed. Axial speed is fundamentally influenced by the planet’s mass and density, as well as orbital radius from the sun.

    Maybe all that is known and you’re looking for something more definitive?

  4. tallbloke says:

    Thanks for the reference JB. I’m interested both in absolute spin rates, and their variations. Clearly Venus is the black sheep of the solar system family. It’s indicative of a magnetic kind of tidal locking as it always shows the same face to Earth at synodic conjunction. Almost shows the same face to Jupiter too. The only way it can do that is to spin slowly backwards.

  5. I am surprised that sea level was not mentioned in the Length Of Day correlations. Sea level has risen out of the Little Ice Age and the LOD has increased accordingly, but since the Atomic Clock was put into service in 1972 to measure Length of Day accurately, LOD has decreased.

    Rising Oceans would increase inertia of earth and increase Length of Day
    The atomic clock is used to measure length of day. 9 leap seconds were added in the seventies and they got a late start, they did not start until 1972 after making an initial adjustment. 6 leap seconds were added in the eighties. 7 leap seconds were added in the nineties. Now, only 5 leap seconds have been added since the end of 1998 and none since 2016. The Length of day has decreased and that would not be true if there was any kind of runaway sea level rise. For whatever reasons, they are lying or just not understanding what they claim to be expert at doing. I have had this discussion with some of you several years ago. It is still holding. I read a story about melting ice and then I go check the atomic clock data, and I relax and just say, not yet.

    Watch for it, if runaway sea level rise starts, the Length of Day would increase.
    LOD is measured accurately by the atomic clock. There is a lot of uncertainty in measuring and averaging sea level, but not in measuring Length of Day.
    Leap Seconds Inserted into the UTC Time Scale
    Date_______MJD* Date_______MJD* Date_______MJD* Date_______MJD
    2016-12-31 57753 1998-12-31 51178 1989-12-31 47891 1979-12-31 44238
    2015-06-30 57203 1997-06-30 50629 1987-12-31 47160 1978-12-31 43873
    2012-06-30 56108 1995-12-31 50082 1985-06-30 46246 1977-12-31 43508
    2008-12-31 54831 1994-06-30 49533 1983-06-30 45515 1976-12-31 43143
    2005-12-31 53735 1993-06-30 49168 1982-06-30 45150 1975-12-31 42777
    1992-06-30 48803 1981-06-30 44785 1974-12-31 42412
    1990-12-31 48256 1973-12-31 42047
    1972-12-31 41682
    1972-06-30 41498

    People have said, the inertia of earth is huge, but the inertia of the oceans is tiny. The Crust of the earth floats on the core and the oceans are significant when compared to the crust. During major ice ages, Length of Day was significantly shorter. Most ice on land is in or near polar regions, closer to the spin axis. Most water is in oceans closer to the equator, further from the spin axis.
    Ice mass is close to the spin axis, water is far from the spin axis. When the dancer or skater pulls arms in tight, the spin is faster, when the arms are out the spin is slower. When water is moved from the oceans to be sequestered as ice on land, the inertia of the crust of the earth is reduced. When ice on land thaws and enters the oceans, the inertia of the crust of earth is increased.

    The GHGs have not caused SLR since 1972, the consensus climate alarmists are clearly lying or plain wrong and there is NOT A DAMN THING we can do about what they tell us, but we clearly do not need to believe Sea Level Rise or any other alarmist junk they promote.

    Those climate events are not happening due to manmade CO2 but the harm causes by their “so called” fixes are going to happen now, and yes, their man-made harm is already very bad.

    Sea Level should not be left out of Length of Day considerations. LOD is a best way to know if sea level is going up or down. Rising Sea Levels would cause more and more leap seconds to be added and it has happened that less and less leap seconds have been added. The solar system dynamics have correlations with LOD, but sea level influences the longer term changes.

  6. Rick Salvador linked spin rate to mass of the earth. The core of the earth spins at a different rate than the crust. The inertia that matters to us is the inertia of the crust and changes in sea level around the equator and sequestered ice on land near the spin axis is a significant part of the inertia that influences the length of day changes that we can measure.

    Spin rate of the whole mass of the earth would relate more to the core since that is most of the mass.
    What we are accurately measuring is the spin rate of the crust of the earth.
    Rick’s analysis should relate more to the core, I do not know if those measurements have been made

  7. Gamecock says:

    ‘add a -0.0006 second correction’

    Is adding a negative number intended to confuse? Could he have subtracted 0.0006 seconds?

  8. ichor0 says:

    – “He needed to add a -0.0006 second correction in June each year”

    reminded me of this post (you’ve mentioned TC a few times)
    which had this

    hard for me to visualize. asfaik the Vega, M54 angles are quite distinct from the galactic center angle.

    – ‘bloke down the pub’ “I suppose the first question should be, what effect would be expected on climate of this variation in LOD?”

    “Ninderthana” has quite a few posts on LOD studies and climate, especially ENSO. Searching his blog n the two terms

    In this regard he cited Sidorenkov / Zotov papers, as far as I remember
    eg this poster http://lnfm1.sai.msu.su/~tempus/english/science/articles/IAG-IASPEIPoster.pdf

  9. NeilC says:

    It is a coincidence that this story should come up at this time. I have been working on how CoV-2 has been progressing since the start of the outbreak. Initially I used average UK; Sunshine hours, max Temperature and Relative Humidity. Then I got to thinking about LOD for Birmingham (central(ish) to England & Wales) and tried correlations with that. It showed very strong relationships with a 3 week lag.

    You can compare each years’ respiratory death rates from 2010-2021 here: https://www.weather-research.com/articles/uk-cov-2-update-no-logical-reason-for-lockdown-from-18feb2021

  10. Phoenix44 says:

    Gamecock, he added a correction. You can’t subtract a correction unless you’ve already added it

  11. tallbloke says:

    Maybe I should have said “included a -0.0006″ correction” rather than added. Sorry for any ambiguity or confusion.

  12. tallbloke says:

  13. oldbrew says:

    These would-be planet saver types inhabit a Hollywood-style mental landscape.

  14. JB says:

    Sorry for the response delay.Spolter’s book has a chapter on Inertia, in which she derives the equation(s) for rotational velocity (which includes known mass):

    “Although we do not know the mass of the celestial bodies, we can get an idea of the comparative heaviness of the bodies by calculating the resistance offered to their rotation. The acceleration of gravity at the surface of a body can be calculated from the known values of the gravitational force and the equatorial radius, Re, where g (gravity) = gravitational force of the orb, gF/(pi*Re^2)
    The velocity at the equatorial surface, if not retarded by the weight of the body, would be Vg = sqrt(g*Re)
    The sidereal period of rotation of the body gives the actual velocity at the equatorial surface, Ve,. The acceleration at the equatorial surface, Ae, can be calculated by the formula Ve^2/Re. The ratio of g/Ae, is an indication of the heaviness of the body. The data for the Sun and for the planets are presented in Tables 11.1 and 11.2. In Table 11.1 the ratios of Vg/Ve are calculated, and in Table 11.2 the ratios of g/Ae, are given.”

    Sorry the math text is not more clear. She does not cover planetary/satellite spin rate variation. For me this was a big step ahead to identify the various parameters of gravitational force, mass, the subsequent gravity at the surface, velocities, and accelerations into something comprehensible about celestial bodies. She says we do not know their mass, and it reminded me that so far mass is an intelligent guess, which I suspect comes from a measure of circular characterizations.

    Perhaps you are privy to relationships or sources that will take you farther than what I found. When I entered all the various parameters of the planets in a spreadsheet and plotted them to get a visual relation between the planets, it occurred to me that the composition of Venus, though it is not quite as “heavy” as Earth, is such that its rotational retardation is slowed to a near standstill. Similar for Mercury. My ensuing thought was that this is somehow connected to Marklund Convection at creation of each orb. What is also really odd, is that the Sun’s rotational velocity is very close to the Moon’s; that three of the planets have inclinations with ±3º, while others are near 0º (Venus inverted 180); with the exceptions of Uranus and Neptune are bizarrely “off the chart” in almost every way, suggesting either late comers to the solar system, or extraordinary forces present during their formation.

    There’s a lot more peripheral discussion in the book related to the concept of Inertia (unmasking of Einstein, Newton, and Kepler’s 2nd Law). I hope this much is useful. If you cannot obtain a copy readily, send me a note at klokman@unitedfiber.email.

  15. tallbloke says:

    Hi JB, thanks for this comment. I probably need to read the book, because it’s not obvious to me why:

    The velocity at the equatorial surface, if not retarded by the weight of the body, would be Vg = sqrt(g*Re)

    I think Mercury and Venus are exhibiting a type of tidal locking. Mercury rotates 3 times per two orbits of the Sun, and Venus always shows the same face to Earth at closest approach.

    Venus also has an almost perfectly circular orbit, and that might be a clue. Earth and Mars have bigger eccentricities and spin much faster. The gas giants have bigger eccentricities than Earth and spin even faster (or at least the upper reaches of their atmospheres visible to us do). Let’s not forget the upper reaches of Venus’ atmosphere have a much higher velocity than its surface too.

    I’ll drop you an email, I’d like to see the book.

  16. Bazmd says:

    Excellent work.

  17. oldmanK says:

    From JB says: April 11, 2021 at 1:52 pm , re Pari Spolter’s The Gravitational Force of the Sun (1995)
    An interesting read here, author Pari Spolter: https://www.researchgate.net/publication/243587405_New_Concepts_in_Gravitation

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