For todays trf realizations, four space geodetic techniques are combined and linked by co-location sites on the earths surface ( earths shape ) and by common earth orientation parameters ( earth rotation
The mean sea level and polar ice changes cause common variations of the principal moments of inertia and Earth rotation
with decadal, centennial and millennial periods.
The performance assessments addressed four topics: Earth rotation
, Earth shape, Earth revolution, and clouds and weather in the Earth/environmental science class (Ernst & Glennie, 2015, pg 10).
A (https://hpiers.obspm.fr/iers/bul/bulc/bulletinc.dat) statement on the website of the International Earth Rotation
and Reference System Service, responsible for the synchronization of Earth time, said in reference to the Coordinated Universal Time: "A positive leap second will be introduced at the end of December 2016.
Geophysicist Chopo Ma, of the International Earth Rotation
and Reference Systems Service, said: "More and more leap seconds will be called for but we can't say one will be needed every year.
Though it all sounds a little pointless, the extra second, which was announced on Monday by the International Earth Rotation
and Reference Systems Service, will be enacted to help account for Earth's slowing rotation.
Dr Helal Al Kaabi, executive director of EMI explained: "Our latest move to add a leap second to the UAE standard time follows a decision by the International Earth Rotation
and Reference Systems Service in January 2015 to add a leap second to Coordinated Universal Time at the end of June this year".
This movement is tracked by the International Earth Rotation
and Reference Systems Service at the Paris Observatory.
However, owing to the influences of earth rotation
and elliptical orbit, sometimes [R.sub.st](f) x [[??].sub.st](t) [not equal to] 0, especially in GEO SAR, and it affects the quality of image by the residual Doppler centroid.
The clock automatically sets and precisely displays time-of-day to the sec, am/pm, month, date, day of the week and ambient temperature; and it adjusts for daylight saving time, leap year and leap sec (earth rotation
Fine structure of an amplitude fluctuation spectrum (i.e., that of "data spread") can be determined during measurements of different nature changes with the Earth rotation
around its axis and its movement along its orbit.
Every time the discrepancy between TAI and UT1 becomes too big, the International Earth Rotation
and Reference Systems Service (IERS) jumps into action and announces a "leap second" - usually several months in advance.