@spmpls gotcha. Well I am sure you have met the old ngs advisor in ky now I believe he is kinda over all of the ngs advisors Ross M. He truly is the reason Erika and I met. I would love to pick your brains. All that movement in California you have to be on your A game constantly when using older passive control. I been out there for bootcamp USMC and ESRI conference years ago.
I have never met Ross in person, but I have spoken with him many times. I have met many other NGS HQ staff however and work very closely with our regional geodetic advisor.?ÿ
Yes, I refer to the movement out here as "job security." It certainly does enhance the concept and importance of epoch dates. Then there are earthquakes and subsidence. I presented at the NGS 2019 Geospatial Summit (remotely) on the challenges we face and the measures we must take to deal with positional time travel. I have done the same for regional surveyors from around the country for the USGS and US Fish and Wildlife. I always get a kick out of seeing the reactions of surveyors who aren't familiar with what we deal with regarding movement. Movement due to tectonic plate drift in the SF Bay Area is about 1.7 feet since the NGS 2010.00 realization.
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@spmpls wow 1.7 ft or 1.7usft lol. Yes coordinates that change are not a concept that has been dealt with a lot on the land surveying side of the house. As a geodetic surveying I learned a lot about that. I learned the most from dealing with the gps constellation and the continuing change of each sv constantly in orbit. That shocked my little brain from my surveying days for sure.
We had an NGS CORS (P565) that was about 24 cm lower than the 2010.00 datasheet value because of subsidence. The ellipsoid height was recently corrected when the Multi-Year CORS Solution 2 values were pushed out by NGS. Check out the "current" ellipsoid height then compare it to the superceded 2010.00 value below.
https://www.ngs.noaa.gov/cgi-bin/ds_cors.prl?CorsSelected=|P565&CorsTypeSelected=Arp
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Subsidence. What subsidence? Obviously this classic photo is an example of a growing power pole...
Only about 29' worth. Dr. Joseph Poland, USGS. It has wreaked havoc with the California Aqueduct over the years.
For those like me who didn't have sound, the NGS gravity webinar is available now (both audio and video).?ÿ I imagine that Erika Little will be okay with it being linked here.?ÿ Enjoy!
Thanks.
@loyal, You can subscribe to get notices here and also hear the recorded ones.
"Subscribe to receive monthly notices about upcoming webinars."
Overview | NGS Webinar Series | NGS Testing & Training Center | Science and Education | National Geodetic Survey
https://www.ngs.noaa.gov/web/science_edu/webinar_series/
The recent one on Gravity is available now here -
2020 Recorded Webinars | NGS Webinar Series | National Geodetic Survey
https://www.ngs.noaa.gov/web/science_edu/webinar_series/2020-webinars.shtml
"Subscribe to receive monthly notices about upcoming webinars."
Overview | NGS Webinar Series | NGS Testing & Training Center | Science and Education | National Geodetic Survey
https://www.ngs.noaa.gov/web/science_edu/webinar_series/
The recent one on Gravity is available now here -
2020 Recorded Webinars | NGS Webinar Series | National Geodetic Survey
https://www.ngs.noaa.gov/web/science_edu/webinar_series/2020-webinars.shtml
