Rainier still measures up: 14,411 feet

[+rogbarn]

I got an error while posting the intial topic, so here it is:

 

I thought people here might find this interesting, especially the part about how the marker had been vandalized and they pounded it back in place. From The Olympian newspaper in Olympia, WA.

 

MIKE ARCHBOLD; Staff Writer

 

Mount Rainier is stuck in a rut.

 

For the third straight time, an expedition sponsored by the Land Surveyor’s Association of Washington found the state’s signature peak to be 14,411 feet high.

 

The expedition announced its findings Wednesday.

 

“The new elevation came in at only a few inches different than the previous observations,” said Larry Signani of Sumner, a surveyor and numbers cruncher for the expedition. “The published value will remain at 14,411 feet.”

 

In 1988 and 1998, the association also sent teams to the summit. Using global positioning system equipment, they calculated its height both times at 14,411 feet – give or take an inch or two.

 

That’s one foot higher than the previously accepted height of 14,410 feet.

 

The newest measurement is within 0.3 feet of the previous two measurements, which also were taken at this time of year.

 

Vandalism of a permanent marker used to make readings on the summit could account for the slight difference. Someone tried to remove the brass cap from the marker, which team members were forced to pound back in place during last month’s expedition.

 

Whether the newest measurement will supplant the often-used 14,410 foot measurement is anyone’s guess. Despite the two previous surveys, Mount Rainier National Park still uses the lower height on its web site.

 

Park Superintendent Dave Uberuaga said Wednesday that with three significant surveys all pointing to 14,411 feet “it may be time for the park to seriously consider making a request to (the U.S. Geological Survey) to change that measurement.

 

“We have to be accurate and sensitive to data,” he said.

 

Bob Anderson, a surveyor from Friday Harbor and the lead climber on the expedition, acknowledged the 14,411-foot height isn’t used in some publications but noted the Geological Survey has certified their measurement.

 

Signani said the Geological Survey measured Rainier in 1956 before GPS was available and came up with 14,410 feet. He later obtained the data from that survey, recalculated it and found a tiny error in a vertical angle. Correcting that error produced a height of 14,411 feet, he said.

 

Rainier’s height has ranged from 12,330 feet in 1842 to 14,532 in 1897.

 

The latest expedition wasn’t concerned solely with proving how high the mountain is. It also was a chance to use new digital technology to gather data in a remote location, Anderson said.

 

GPS technology has changed dramatically since 1988 when the team included more than 140 volunteers using some of the first portable GPS units. Those units weighed over 65 pounds each and could connect with only four GPS satellites. Readings took hours as they waited for the satellites to come overhead.

 

Signani said a lot of data was gathered in 1988 and finely calculated by top mathematicians. It has held up over the years, he added.

 

This time the team was only nine surveyors who carried GPS units that weighed two pounds. The devices were able to use more than 45 satellites for tracking.

 

Anderson said the team spent nearly 24 hours on the summit and took redundant measurements to check accuracy.

 

Mike Archbold: 253-597-8692

 

mike.archbold@thenewstribune.com

 

Read more: http://www.theolympian.com/2010/08/12/v-pr...l#ixzz0wPXPqOGM

[Bill93]

Has anybody seen a discussion of how they converted GPS height above the ellipsoid into orthometric height above the geoid? How well can they trust the geoid (gravity) model on top of a mountain that probably hasn't had a direct gravity measurement?

 

And is it NGVD29 or NAVD88?

Edited August 12, 2010 by Bill93