ROM SAF - NRT Notification Detail

NRT Notification Detail

Degraded GRAS level 1b data

DATE: 2011-06-01 08:50
TYPE: NRT-GTS

Description

Dear GRAS SAF GTS user Issued 2011-06-01 08:50 UTC Upstream GRAS level 1 b data has been slightly degraded since yesterday noon (2011-05-31 12:00 UTC). The degradation is expected to have very little or no impact on the GRAS SAF refractivity product. Please see detailed message from EUMETSAT below. Best regards The GRAS SAF Team Forwarded message: Subject: GRAS upper level (60-80km) data degradation since 31 May 2011 12:00 (UTC) From: Christian Marquardt Date: 2011-06-01 07:34 UTC Dear all, starting around noon (UTC) yesterday, 31 May 2011, we experience once more some slight degradation in GRAS bending angle data quality at high altitudes. Setting and rising occultations exhibit a positive / negative bias in the order of 1 microradian at altitudes of 60 - 80 km, respectively; there should be little or no impact at altitudes below 35 km. Please note that the data is NOT flagged as degraded. Apparently, the situation has stabilized at the 1 micron level; we might perform an orbit reset if data quality doesn't recover during the day. As previously, the cause for the high altitude biases is a flaw in our orbit processing configuration which reacts unfavourably to geomagnetic storms like the one currently ongoing in the ionosphere. An improved configuration which avoids these kind of degraded data quality is currently under testing, but it will require 3-4 weeks before we can finally apply that in the operational processing as we so far only have little experience on how it affects the orbit quality under normal conditions. With our sincere apologies, Christian. -- Dr. Christian Marquardt, Polar System Product Expert EUMETSAT, Eumetsat Allee 1, D-64295 Darmstadt, Germany

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