Maybe time should just be sub solar longitude

It's very easy to convert UTC time to sub solar longitude (longitude where the Sun is directly over)

0000hrs UTC the Sun is directly over the ante meridian (180deg lon)
1200hrs UTC the Sun is directly over the prime meridian (0deg lon)

Every 30 deg longitude is 2 hrs (hence every 90deg is 6 hrs)

Why not just denote time as sub solar longitude? One can easily compare local longitude with sub solar longitude to figure where the Sun will be located.

Universal time of day: should be the longitude of the sub solar point.
Time of year should be latitude of sub solar point.

Links
https://en.wikipedia.org/wiki/180th_meridian
https://en.wikipedia.org/wiki/Prime_meridian
https://en.wikipedia.org/wiki/Coordinated_Universal_Time