An Analysis of the Temporal and Spatial Progression of the Ozone Monitoring Instrument (OMI) OMTO3 Daily Row Anomaly, 2007-2015

Abstract:

<span">The joint US/Dutch Ozone Monitoring Instrument (OMI) is one of four atmospheric monitoring instruments co-manifested on the EOS AURA satellite launched in July 2004. The 576 spatial pixels across OMI’s 2-D CCD are binned into 60 “rows.” Starting in June 2007 and continuing to the present, two rows ceased to provide useful data. On three occasions between May 2008 through January 2009, eighteen additional spatial rows became affected by what is now called the “row anomaly” effect. Since 2010 the row anomaly effect has been roughly constant at eliminating 20-30% of the otherwise useful data, with some minor variability, especially at the ends of the main block of anomaly-effected rows. When including other data quality factors, approximately 45-50% of all daily zonal mean data collected by OMI is considered “useful” or valid for all science applications. While this means that total global ozone maps are now available every two days, as opposed to each day in the two years after launch, this is still more than adequate to fulfill overall mission science requirements.

<span">OMI science data users need to know which exact data points are valid and which are flagged as contaminated by the row anomaly effect. Not all of the pixels in the main block of eighteen spatial rows yield spurious data all the time. The main driver of row anomaly variability is the orientation of the OMI instrument with respect to the Sun, specifically when at high Northern latitudes in the boreal winter. Variations in the row anomalies make the exact prediction of good (valid data) vs. bad (anomaly-affected) data impossible. Therefore, the daily zonal mean total ozone is constantly evaluated for data quality to identify which rows and 5-degree zonal bands provide anomaly-free total ozone data. The temporal and spatial variation in the row anomaly for the period 2007-present, including its current impact on the availability of “useful” data, will be presented.