[LEAPSECS] speeding up again?

Sat Jun 17 09:47:50 EDT 2023

This point of view (from Richard’s second citation) is rather backward: “LOD is the negative time-derivative of UT1-UTC”, whatever its mathematical utility. And whatever one’s philosophical position on the topic of this list.

I’m a little at a loss for what we’re discussing here. The astronomically long-term trend is that Earth’s angular momentum is being transferred to the Moon. This is a list for picking nits, so by all means, proffer issues of the Earth-Moon barycenter or orbital or spin dynamical effects in the solar system. But in any event, the overall trend is not for a shortening or flat length of day but for LOD to lengthen. And for lab-coated acolytes of atomic time to clutch their pearls over its integral playing bloody hell with UTC.

Why, then, are we seeking additional explanations for effects that act to restore this overall trend? We were surprised at (and some of us were rooting for) the possibility of a negative leap second. Now this seems less likely. Isn’t that the expected (if disappointing for some) result?

A similar answer would apply to the overheated rhetoric in the media about the Earth’s core “spinning backward”, rather than more accurate but more boring phrases like “slightly greater excursions from the overall trend than have been seen in a few decades”. This is to say that there are a lot more immediate negative effects of AGW than hypothesizing that it is enhancing ENSO (or whatever the argument is here) and will cause Armageddon via a negative leap second.

Rob Seaman
Lunar and Planetary Laboratory
University of Arizona

On 6/17/23, 5:59 AM, "LEAPSECS" wrote:

External Email

https://www.science.org/content/article/longer-days-brought-you-el-ni-o

Also:
Investigating the Relationship Between Length of Day and El-Niño Using Wavelet Coherence Method:
https://link.springer.com/chapter/10.1007/1345_2022_167

-- Richard Langley

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| Richard B. Langley                            E-mail: lang at unb.ca         |
| Geodetic Research Laboratory                  Web: http://gge.unb.ca      |
| Dept. of Geodesy and Geomatics Engineering    Phone:    +1 506 453-5142   |
| University of New Brunswick                                               |
| Fredericton, N.B., Canada  E3B 5A3                                        |
|        Fredericton?  Where's that?  See: http://www.fredericton.ca/       |
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________________________________________
From: LEAPSECS <leapsecs-bounces at leapsecond.com> on behalf of Tom Van Baak <tvb at LeapSecond.com>
Sent: June 15, 2023 10:48 PM
To: leapsecs at leapsecond.com
Subject: Re: [LEAPSECS] speeding up again?

✉External message: Use caution.

Steve,

> We can probably put a lot of the blame onto El Niño

That sounds plausible but I'm suspicious of quick and simple explanations.

You work at/for a university, near the coast, yes? Can you ping some of your climatology / oceanography colleagues and get data going back as far as they have it? I think it would be useful to see what the correlation coefficient actually is.

Attached is an LOD plot I made a while ago. A random web google link says "The five strongest El Niño events since 1950 were in the winters of 1957-58, 1965-66, 1972-73, 1982-83 and 1997-98". To my eyeball I just don't see that in the historical LOD plot.

/tvb

On 5/26/2023 9:09 AM, Steve Allen wrote:

On Mon 2023-05-22T16:44:30+0200 Tony Finch hath writ:

The prospect of a negative leap second is receding. The longer-term
projected length of day from Bulletin A has been increasing towards 24h
in recent months.

We can probably put a lot of the blame onto El Niño

--
Steve Allen                    <sla at ucolick.org><mailto:sla at 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

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