[IGSSTATION-365]: YAKT: Winter position anomaly removed

[Mikhail Kogan]

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IGS Station Mail          10 Feb 10:57:29 PST 2005      Message Number 365
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Author: G. Steblov and M. Kogan,

Dear IGS colleagues,

Since winter 2002/2003, station YAKT showed anomalous computed position 
residuals, in excess of 10 mm, during winter months November - March. 
This winter 2004/2005, the residuals were in excess of 30 mm in all 
three components. See IGS mail IGSSTATION-352 of 31-Jan-2005.

We found that the anomalous winter behavior of YAKT was caused by the 
snow accumulation on top and around of the antenna radome. The winter 
temperature at YAKT is -40 to -60 degrees centigrade all winter, so the 
snow, if not removed, remains on the antenna for months.

The snow was removed from the antenna on 03-Feb-2005 at about 5am UTC. 
Global daily geodetic solutions for days 029 -037 were inter-compared, 
i.e. 5 days before and 4 days after the snow removal. The winter 
anomalous residuals totally disappeared in all three components after 
the snow had been removed. We hope that YAKT now behaves "well", i.e., 
the residuals will be small all year long.

Care is now taken to remove snow from the antenna at YAKT regularly.

- Grigory Steblov
RDAAC / Geophysical Service
Russian Academy of Sciences

- Mikhail Kogan
Lamont-Doherty Earth Observatory of Columbia University