OMI Products Overview

Important Information for OMI Data Users

Row Anomalies

OMI has suffered from a so-called “row anomaly”. It affects particular viewing directions, corresponding to rows on the CCD detector, hence the name “row anomaly”. Other viewing directions are of optimal quality. Please read this information carefully prior to using OMI data.

The first appearance of the row anomaly is on June 25th, 2007. At that time, it appeared only in rows 53 and 54 (zero-based). From May 11th, 2008, cross-track scenes 37-41 (0-based) are affected as well. In January 2009 the range of rows extended to 27 - 44, while the original rows 53 and 54 remain affected. Since then the behavior of the row anomaly has remained dynamic. Which rows are affected and to what extent varies with time. Please visit the “Overview” section of our detailed technical information page for the most up to date information and details. A graphical overview of the affected rows is available on the background page.

Recommendations To Users

At the moment no corrections have been implemented in the operational level 1B and level 2 data. Please use the flagging provided in the level 1B and level 2 products to filter out affected data. All other OMI data, meaning unflagged scenes and earlier observations, is of optimal quality. Level-3 products are being produced after filtering for the flagged scenes.

Please visit the README and Data Product Quality Information for the OMI data product of your interest at the NASA DISC pages for OMI data.

Row Anomaly Corrections

The OMI team is aware of the anomaly and is currently investigating whether corrections for the effects can be implemented in the data-processing software. Please visit this information page regularly for updates on the status of corrections implemented and visit our detailed technical information page.

Row Anomaly Flagging

The Level 1B data are flagged for the row anomaly via the XTrackQualityFlags field. Most level 2 products have this information available now, either by copying the XTrackQualityFlags field into the level 2 product or via other newly defined flags in the level 2 product. Please check the README file of the L2 products for more information. Please visit our detailed technical information page for details on the current flagging status of the Level 1B and Level 2 products.

Row anomaly RSS feed

We have set up a row anomaly RSS feed where we post updates to our flagging. You can subscribe to the row anomaly feed via the link. An archive of the messages is here.