ROM SAF - NRT Notification Detail

NRT Notification Detail

Degraded Metop-B GRAS level 1b data, 2013-08-18

DATE: 2013-08-19 13:33
TYPE: NRT-GTS

Description

Dear ROM SAF GTS User

Issued 2013-08-19 13:35 UTC

Upstream Metop-B GRAS level 1b input data was degraded yesterday (2013-08-18) between 11:12 UTC and 18:09 UTC and subsequently the ROM SAF demonstrational GRM-40 product was degraded.

The operational GRM-01 product was not affected.

We are sorry for the inconvenience.

Please see detailed message from EUMETSAT below.

With kind regards
The ROM SAF Team

Forwarded Message:
Subject: Degraded (and missing) GRAS/Metop-B data on Sunday, 18th August 2013
Date: 2013-08-19 08:03 UTC
From: Christian Marquardt

Dear all,

unfortunately, I have to report an extended period of degraded and missing data for Metop-B yesterday, 18. August 2013

GRAS/Metop-B bending angle data was severely degraded or missing between 11:12 UTC and 23:00 UTC on Sunday, 18th August 2013. Between 11:12 UTC and 18:09 UTC, the data was *not* properly flagged as degraded. Afterwards, level 1b data products were correctly flagged as containing degraded bending angle data.

Metop-A data was not affected.

The details, in case you care:

- starting at 11:12 UTC, GRAS/Metop-B bending angle data exhibited
systematic upper level biases in the order of 20 microrad with
opposite signs in rising and setting occultations. The reason
very likely is a faulty measurement that the operational POD
system did not QC properly (investigations are still ongoing).
The data was *not* flagged as containing degraded data.

- Between 18:09 UTC and 18:57 UTC, no Metop-B level0 data was
available due to a downlink problem; this affected all instruments
on Metop-B.

- When level0 data became available again, the Precise Orbit
Determination system performed a reset. This fixed the bias
problem of the GRAS/Metop-B, but data stayed degraded for four
hours after the reset, i.e.until about 23:00 UTC. This time, the
level1 data products *did* contain the degraded data flagging
as they should.

We apologize for the inconvenience.

With kind regards,

Christian.

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