OPUS and Earth Tides

bill93 · 2017-01-07T01:03:00Z

Wikipedia says that tidal motions in the solid earth have amplitude on the order of a meter vertically when various components add up. Horizontal movement would be nearly an order of magnitude less than vertical.Does OPUS just assume you and the CORS move the same amount and that any difference is lost in the other noise effects? This motion would then alter the apparent propagation delays. Or does OPUS apply tidal compensation?Obviously your report does not tell you where you actually were in XYZ, or you wouldnÛªt get a decent match between sessions. It must tell you approximately where your point would be if it were averaged over the tidal variations.If you use CORS that are a degree in longitude from your station (quite common), there could be a significant difference in the tidal effect for you and for the CORS at the time of the greatest rate of change for your area (zero degree phase angle). Diurnal changes would have a phase difference equal to the longitude difference and semi-diurnal component which would have phase difference double the longitude difference.A crude estimate assuming everything listed in the Wikipedia article adds in worst case: 0.686 m * [sin(+1 deg) ÛÒ sin(-1 deg)] semi-diurnal + 0.428 * [sin(+0.5 deg) ÛÒ sin(-0.5 deg)] diurnal = 2.2 cm. Most of the time the components donÛªt add up to near maximum, but it can happen. CORS well placed around you (as OPUS-RS tries to do) would tend to cancel this effect in the averaged position, but such choices donÛªt always happen for OPUS-S, and even when they do would increase the pk-pk.---------Is this presently addressed, is this something that would have to eventually be addressed in order to further improve static and/or RTK results, or am I just confused?

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GNSS & Geodesy

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jhframe

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Loyal, post: 408264, member: 228 wrote: My modus operandi has always been to export the dx, dy, dz, vector data, along with the rms and correlation data out of the G-Files, and run things through COLUMBUS to get a better feel for the coordinate estimate at the Remote Station.

G-files rock!

Posted : January 9, 2017 3:36 pm

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OPUS and Earth Tides

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