[LEAPSECS] Crunching Bulletin B numbers

Mark Calabretta mcalabre at atnf.csiro.au
Wed Feb 16 18:52:26 EST 2011

On Tue 2011/02/15 18:51:58 PDT, Rob Seaman wrote
in a message to: Leap Second Discussion List <leapsecs at leapsecond.com>

>My point is just that archival data is sufficient to characterize the

>real world behavior of the algorithms already developed. We needn't

>wait ten years to know if data limited to what was available ten years

>ago can predict this year's UT1 to some level of confidence.

I was hoping to see more evidence of geophysics in the prediction
algorithms but, apart from a few that incorporate predictions of
atmospheric and oceanographic angular momentum, they mainly seem
to be mathematical extrapolation techniques.

Considering that LOD can be affected by essentially unpredictable
things such as earthquakes and volcanoes; magma currents in the deep
mantle; the melting of the ice caps due to global warming; the
southern oscillation index and Indian Ocean dipole; meteor impacts;
etc., likely including some "unknown unknowns", the task is probably
no less difficult than reliably predicting movements in the stock
exchange 10 years from now.

That said, if leap second insertions were simply deferred for 10
years, DUT1 would probably grow to no more than about 6s (even
including deceleration), which seems much preferable to letting it
grow without limit.

Mark Calabretta

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