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Update annex-examples.adoc
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Broke first sentence of #2 into two sentences.
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cmheazel authored Feb 14, 2024
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=== Temporal Coordinate Reference System
1. A remote autonomous underwater drone, known as a 'glider' is making regular measurements of temperature and salinity deep in the Atlantic Ocean. The measurements are time-stamped by an on-board computer clock. The clock was synchronized to a satellite's atomic clock when the drone was launched. When the drone surfaces to report its findings, or to be picked up by a research vessel, it is found that the computer clock as 'drifted' compared to time from the satellite. The drone's clock is assumed to have 'drifted' in a consistent, linear, fashion, and the error correction is distributed proportionately along the time series of measurements.

2. Several timescales have been defined using the same atomic clocks, but for various reasons, such as the year of starting, or the need to store numbers in limited length computer words, different epochs have been chosen. This is illustrated in Figure 3. The figure also illustrates how UTC is not a timescale, but a timeline, as it has been adjusted with leap seconds to correspond to the Gregorian calendar and not deviate more than 0.6 seconds from Earth's actual day length. This is because UTC is based on the atomic definition of a second, the SI second, whereas the Gregorian calendar assumes that a day, based on Earth's rotation with respect to the sun, is 86,400 seconds, but this daily rotation varies in duration every day throughout the year for a variety of reasons.
2. Several timescales have been defined using the same atomic clocks. For various reasons, such as the year of starting, or the need to store numbers in limited length computer words, different epochs have been chosen. This is illustrated in Figure 3. The figure also illustrates how UTC is not a timescale, but a timeline, as it has been adjusted with leap seconds to correspond to the Gregorian calendar and not deviate more than 0.6 seconds from Earth's actual day length. This is because UTC is based on the atomic definition of a second, the SI second, whereas the Gregorian calendar assumes that a day, based on Earth's rotation with respect to the sun, is 86,400 seconds, but this daily rotation varies in duration every day throughout the year for a variety of reasons.

[[fig-differing-timecales]]
image::images/MISB_Figure_36.png[]
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