From kogan at ldeo.columbia.edu Thu Feb 10 10:57:24 2005 From: kogan at ldeo.columbia.edu (Mikhail Kogan) Date: Thu, 10 Feb 2005 13:57:24 -0500 Subject: [IGSSTATION-365]: YAKT: Winter position anomaly removed Message-ID: <420BAE94.6010607@ldeo.columbia.edu> ****************************************************************************** IGS Station Mail 10 Feb 10:57:29 PST 2005 Message Number 365 ****************************************************************************** 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