[LEAPSECS] Five years to go?

[Demetrios Matsakis]

The data I used came from USNO/IERS, and were reduced using standard formulas from the IERS Conventions.

But I have published an LOD plot of Stephenson's data, going back to  ~1770, with Allan deviations, here:  https://www.gps.gov/cgsic/meetings/2014/matsakis.pdf <https://www.gps.gov/cgsic/meetings/2014/matsakis.pdf>.  It shows a speed up of comparable magnitude (but less width) at around 1870 followed by a larger slow down around 1900.   The speed-up after that slowdown is roughly comparable to what we are seeing now. 

Sorry, but I have not tapped into a mother-load of modern studies, although people are always Fourier-transforming these things.   I am impressed by recent reports of seismic data indicating large blobs at the core-mantle boundary.   All my life I’ve heard motions down there are the possible cause of these fluctuations. I can’t tell you how the numbers work out, but see this:

"As part of the EGU General Assembly 2021 (https://www.egu2021.eu/ <https://www.egu2021.eu/>) that
will be held virtually from 19 to 30 April 2021, we like to draw your
attention to session G3.1: Earth Rotation: Theoretical aspects,
observation of temporal variations and physical interpretation
(https://meetingorganizer.copernicus.org/EGU21/session/39900 <https://meetingorganizer.copernicus.org/EGU21/session/39900>). Below you
can find the detailed description."


> On Jan 12, 2021, at 9:01 PM, Seaman, Robert Lewis - (rseaman) <rseaman at arizona.edu> wrote:
> 
> Are there citations, from F. R. Stephenson or otherwise, constraining whether such dramatic short-term reversals are physically anticipated? If so, would this then increase the likelihood of a subsequent period of (relatively) rapid correction back to the general overall slowing trend? Which is to say do we have a handle on the power spectrum of various terms (annual, decadal, longer)? (Undoubtedly I’m expressing that naively, feel free to rephrase the above questions.)
>  
> Rob
>  
> From: LEAPSECS <leapsecs-bounces at leapsecond.com <mailto:leapsecs-bounces at leapsecond.com>> on behalf of Demetrios Matsakis via LEAPSECS <leapsecs at leapsecond.com <mailto:leapsecs at leapsecond.com>>
> Reply-To: Leap Second Discussion List <leapsecs at leapsecond.com <mailto:leapsecs at leapsecond.com>>
> Date: Tuesday, January 12, 2021 at 6:20 PM
> To: "leapsecs at leapsecond.com <mailto:leapsecs at leapsecond.com>" <leapsecs at leapsecond.com <mailto:leapsecs at leapsecond.com>>
> Cc: Demetrios Matsakis <dnmyiasou at yahoo.com <mailto:dnmyiasou at yahoo.com>>
> Subject: [EXT][LEAPSECS] Five years to go?
> 
> I attach a plot of my extrapolations, which take into account known periodic oscillations to predict that if the Earth continues to rotate as the same rate it has for the last 100 days, a negative leap second will be “needed" in five years.
> 
> The word file shows what the attached plot is based on. 
> <image001.jpg>
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