[LEAPSECS] Earth speeding up?

[Matsakis, Demetrios]

I'm not a geophysicist, but I too have noted what Tom reports.  I've attached  a plot that by coincidence I just made last week.

The best hand-waiving arguments I've heard for these recent "decadal fluctuations" is that the oblateness of the Earth is changing, possibly due to the ice caps changing.    Short-term fluctuations are much better understood, and they correlate very strongly with the atmospheric angular momentum.

-----Original Message-----
From: leapsecs-bounces at leapsecond.com [mailto:leapsecs-bounces at leapsecond.com] On Behalf Of leapsecs-request at leapsecond.com
Sent: Tuesday, April 15, 2014 9:32 AM
To: leapsecs at leapsecond.com
Subject: LEAPSECS Digest, Vol 91, Issue 7

Send LEAPSECS mailing list submissions to
	leapsecs at leapsecond.com

To subscribe or unsubscribe via the World Wide Web, visit
	http://six.pairlist.net/mailman/listinfo/leapsecs
or, via email, send a message with subject or body 'help' to
	leapsecs-request at leapsecond.com

You can reach the person managing the list at
	leapsecs-owner at leapsecond.com

When replying, please edit your Subject line so it is more specific than "Re: Contents of LEAPSECS digest..."


Today's Topics:

   1. earth speeding up (Tom Van Baak)


----------------------------------------------------------------------

Message: 1
Date: Tue, 15 Apr 2014 06:31:21 -0700
From: "Tom Van Baak" <tvb at LeapSecond.com>
Subject: [LEAPSECS] earth speeding up
To: "Leap Second Discussion List" <leapsecs at leapsecond.com>
Message-ID: <E2B96EDC92024F62BC596E9D3249CDD9 at pc52>
Content-Type: text/plain; charset="iso-8859-1"

I know it's a risk making trend lines, but those of us who work with clocks, oscillators and frequency standards find it irresistible to peek ahead sometimes and guess what's coming. This applies to my favorite clock, the earth.

See attached inverse length of day plots (that is, frequency error rather than excess LOD, or period error). This started with Stable32 (the standard tool we all use for time & frequency metrology) but I reformatted them with Excel to make them clearer.

This plot is for 1 July 1972 to the present. Those of you who follow DUT1 like the stock market recognize the characteristic periodicity, bumps, and trends. Note especially the stable period starting 1999, with many days of the year longer than 86400 seconds, and consequently no leap second for 7 years (roughly MJD 51000 to 54000).

Any betting person would say the plot shows an upward trend over the past 40 years. A simple linear fit suggests the earth will be back to an honest 86400 second day within a few years, around MJD ~59000 (year ~2020).

The URL for the plot is:
http://leapsecond.com/pages/lod/earth-lod-10.gif

See also the zoomed version, where the predicted zero-crossing is clearer:
http://leapsecond.com/pages/lod/earth-lod-11.gif

The raw DUT1 and LOD data comes from IERS. It's a work in progress; other plots are under http://leapsecond.com/pages/lod/ as I pursue this.

I realize this is just for fun, and the serious geology, astronomy, and climate professionals on the list will raise valid concerns. But there's no doubt that since the 1970's the earth is generally speeding back up. If this trend continues, within a decade, we will have another long stretch of no leap seconds and this time it will be followed by our first negative leap second.

/tvb
-------------- next part --------------
A non-text attachment was scrubbed...
Name: earth-lod-10.gif
Type: image/gif
Size: 16932 bytes
Desc: not available
Url : <http://six.pairlist.net/pipermail/leapsecs/attachments/20140415/9a38e263/attachment.gif>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: earth-lod-11.gif
Type: image/gif
Size: 17685 bytes
Desc: not available
Url : <http://six.pairlist.net/pipermail/leapsecs/attachments/20140415/9a38e263/attachment-0001.gif>

------------------------------

_______________________________________________
LEAPSECS mailing list
LEAPSECS at leapsecond.com
http://six.pairlist.net/mailman/listinfo/leapsecs


End of LEAPSECS Digest, Vol 91, Issue 7
***************************************
-------------- next part --------------
A non-text attachment was scrubbed...
Name: lodplot.jpg
Type: image/jpeg
Size: 200575 bytes
Desc: lodplot.jpg
Url : <http://six.pairlist.net/pipermail/leapsecs/attachments/20140415/6d06495d/attachment-0001.jpg>