NRT Notification Detail

Degraded GRAS level 1b data
DATE:   2013-03-07 09:40
TYPE:   NRT-GTS
Description
Dear ROM SAF GTS User

Issued 2013-03-07 09:35 UTC

Upstream GRAS level 1 b data was degraded between 2013-03-05 04:18 UTC and 2013-03-06 15:00 UTC. ROM SAF products were also affected, but not flagged as non nominal.

Please see detailed message from EUMETSAT below.

Kind regards
The ROM SAF Team

Forwarded Message:
Subject: Degraded GRAS level 1 data quality on 5th and 6th March 2012
From: Christian Marquardt
Date: 2013-03-06 17:37 UTC

Dear all,


unfortunately, I have to report that the operational level 1 data from the GRAS instrument onboard the Metop-A satellite has suffered from systematic upper level bending angle biases between

yesterday, 5 March 2013 04:18 UTC and today, 6 March 2013 15:00 UTC

Biases are in the order of 1 microrad in the altitude range between 60 and 80 km, exhibiting opposite signs for rising (positive) and setting (negative) occultations. The size of the biases decreases with decreasing impact altitude, but are still visible in the 20-30 km altitude range. Downstream level 2 products (refractivity) generated by the ROM SAF are probably also affected.

Please note that the products disseminated to you were NOT flagged as containing degraded bending angle data.

I very much thank Sean Healy (ECMWF) and Chris Burroughs (MetO) who made us aware of the issue earlier today.

I very much apologize for not having spotted the problem in our internal monitoring (where it was clearly visible); the GRAS team was either busy with some processing issues for Metop-B occurring yesterday, or, in my case, not in the office...

Our apologies!

Christian.


--
Dr. Christian Marquardt, Polar System Product Expert, EUMETSAT
Am Kavalleriesand 31, D-64295 Darmstadt, Germany
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