OMI row anomaly messages

This is an overview on messages that have appeared on the OMI row anomaly feed in reverse chronological order.

Changes to the flagging for the OMI row anomaly starting at orbit 54610 (2014-10-21)

This message was originally posted on 2014-11-11 by Sneep, Maarten

As of orbit 54610 (21 October 2014), the flagging for the OMI row anomaly has been adjusted following observed changes in the anomaly behavior that started at orbit 53601 (13 August 2014).

The main characteristics of this adjustment are:

  • All three spectral channels (UV1, UV2 and VIS): flagging for the stray sunlight starts earlier at orbit phase 0.56 instead of 0.58.
  • UV1 channel: several rows have changed flag values: instead of only flagging for the stray sunlight, rows are now also flagged for the wavelength shift, the blockage and the stray earthlight effect.
  • UV2 channel: seven rows (21-23 and 49-52) have been added that need to be flagged from orbit phase 0.56 onward.
  • VIS channel: six rows (22-24 and 49-51) have been added that need to be flagged from orbit phase 0.56 onward.

The following link provides a schematic overview of the new flagging scheme: flag_values_as_per_orbit_53601.pdf In this flagging scheme, the ground pixels marked with a red border denote the pixels that get a new or updated flag.

L1b and L2 products between orbits 53601 and 54609 are currently being processed, i.e. these products get updated flag values. All products will be made available on the DISC website.

In case of any questions regarding this flagging update, please mail to

Updated flagging for rows 41-45

This message was originally posted on 2012-08-09 by Maarten Sneep

As of orbit 42899 (8 August 2012), the flagging for the OMI row anomaly has been adjusted following an expansion of the row anomaly to rows 41-45 (in UV2 and VIS) in the northern hemisphere, which started on orbit 41324 (21 April 2012). Products between orbits 41324 and 42898 are in the process of being fixed.

This follows an earlier improvement of the row anomaly in the later months of 2011, where the branch of the row anomaly between rows 41 and 52 completely vanished. Adjusted flagging for this change was effectuated as of orbit 40351 (15 February 2012), and products between orbits 39519 (20 December 2011) and 40351 (15 February 2012) have been fixed.

Updated flagging of rows 41-45

This message was originally posted on 2011-08-11 by Maarten Sneep

Following a changing row anomaly behaviour as already mentioned in the previous RSS feed from 5 July 2011, the row anomaly behaviour started to change again recently. To account for this changing behaviour we now have started flagging rows 41-45 for the entire orbit. Several rows seem to have improved, but we will continue to flag those as long as the situation has not stabilized.

The improved flagging has been implemented in the forward stream starting with orbit 37585.

Rows 42 - 45 are affected but not flagged

This message was originally posted on 2011-07-19 by Maarten Sneep

Since July 5th, 2011, row 42 - 45 are affected by the row anomaly. These rows are not yet flagged. The anomaly in these rows now occurs over the whole orbit, not just over part of the orbit as was previously the case.

Update to the row anomaly flagging

This message was originally posted on 2011-05-25 by Maarten Sneep

Recently, the row anomaly has been found to change slightly. Most notably, rows 24 and 50/51 (0-based) are found to be affected by blockage and wavelength shift. Also, the stray-sunlight effect in UV-1 has been underestimated until now. As of orbit 36390, the new flagging is in effect. More information can be found on the background page of the row anomaly and Figure 1 contained therein.

Flagging row 41 (0-based) corrected

This message was originally posted on 2010-10-13 by Maarten Sneep

The OMI row anomaly has been stable for almost a year now. Nevertheless, it was found that the row anomaly flagging in the Level-1B radiance products was inadequate: row 41 (0-based) is affected by stray sunlight in the northern part of the orbit, but was not flagged accordingly. As of orbit 33113 (2010-10-06), this has been corrected.

More rows flagged as affected by the row anomaly

This message was originally posted on 2010-06-09 by Maarten Sneep

The OMI row anomaly has been stable for months now. However, thanks to feedback from Level-2 users, we found that not enough rows were flagged for being affected by the OMI row anomaly. This has now been fixed. The extra rows are all on the edges of the rows that were already flagged. Most notably, the area that is flagged for possible stray sunlight has been expanded. Also, the lower orbit phase limits for anomalies that occur only on the northern side of orbits have been harmonized: all will use a lower limit of 0.58. The changes pertain to orbits 25350 (21 April 2009) and higher, but will, for the time being, only affect data produced in the forward stream, starting with orbit number 31366 (8 June 2010).

New version of OMI level 0 to level 1B software running in forward stream

This message was originally posted on 2010-02-16 by Maarten Sneep

Starting on Feb 1st 2010 / orbit 29515, a new version 1.1.3 of the L0 -> L1b data processing software is operational on the OSIPS. The L1b dataproducts now contain important information on the OMI row anomaly for each ground pixel. You are urgently advised to read the presentation on the KNMI OMI website (PDF) that contains information on this new version.

Inaugural message of the OMI row anomaly RSS feed

This message was originally posted on 2009-12-14 by Maarten Sneep

This is an inaugural message for the OMI row anomaly RSS feed. Certain rows in the OMI data are currently affected by the so called row anomaly. This is widely announced on the OMI data download sites. The row anomaly shows a dynamic behavior, and changes in time. To help us communicate these changes in the OMI row anomaly to the user community, we have set up this RSS feed to announce changes in the row anomaly.

In addition to the RSS feed to communicate with you, we also have created an email address to receive your feedback on our monitoring and flagging of the OMI row anomaly. You can send your remarks to

© OMI -- Last update: Friday, 19-Aug-2011 09:31:31 UTC. --