AURAOMI ozone files with anomalous values

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jstum
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Joined: Mon Jul 04, 2005 4:54 am America/New_York

AURAOMI ozone files with anomalous values

by jstum » Tue Jul 20, 2021 4:18 am America/New_York

Hello,

This post is to warn you that AURAOMI ancillary files exhibit anomalous ozone values in southern hemisphere since day 138 (18 May 2021). Total ozone is obviously wrong (more than twice its normal value). This anomaly affects chlorophyll maps (wrong chl blooms at the location of the Aura tracks) built from your level 2 products.

Best regards,

Jacques
Attachments
CHL anomaly.pdf
(320.29 KiB) Downloaded 56 times
AURAOMI anomaly.pdf
(221.63 KiB) Downloaded 52 times
by david.haffner » Mon Aug 30, 2021 10:58 am America/New_York
Hello Jacques and all,

I am responsible for the OMI total ozone algorithm. Thank you for posting your observations about the anomalous OMI ozone data the began showing up in late spring. As you probably are aware, OMI has an instrument anomaly that degrades the quality of the data in a subset of the cross-track positions within the swath. The effects change with solar angle and also time to a degree.

We have an error detection code that flags the affected data but occasionally there is a glitch. We found that this had occurred in this case and made adjustments to the flagging. The updated data were distributed to the Goddard archive (GESDISC) but I don't know if they have reached the data source you access. If they have not, please let me know.

Best regards,
Dave
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OB.DAAC - SeanBailey
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Re: AURAOMI ozone files with anomalous values

by OB.DAAC - SeanBailey » Tue Jul 20, 2021 8:20 am America/New_York

Jacques,
Thanks for the note. Yes, it appears that there is an issue with the ozone source. We are investigating.

Regards,
Sean

david.haffner
Posts: 2
Joined: Mon Aug 30, 2021 10:29 am America/New_York
Answers: 1

Re: AURAOMI ozone files with anomalous values

by david.haffner » Mon Aug 30, 2021 10:58 am America/New_York

Hello Jacques and all,

I am responsible for the OMI total ozone algorithm. Thank you for posting your observations about the anomalous OMI ozone data the began showing up in late spring. As you probably are aware, OMI has an instrument anomaly that degrades the quality of the data in a subset of the cross-track positions within the swath. The effects change with solar angle and also time to a degree.

We have an error detection code that flags the affected data but occasionally there is a glitch. We found that this had occurred in this case and made adjustments to the flagging. The updated data were distributed to the Goddard archive (GESDISC) but I don't know if they have reached the data source you access. If they have not, please let me know.

Best regards,
Dave

david.haffner
Posts: 2
Joined: Mon Aug 30, 2021 10:29 am America/New_York
Answers: 1

Re: AURAOMI ozone files with anomalous values

by david.haffner » Mon Aug 30, 2021 11:29 am America/New_York

Posting image of properly flagged data.
Attachments
Updated Total O3 file for July 18, 2021 (d199)
Updated Total O3 file for July 18, 2021 (d199)
ColumnAmountO3_in_OMI-Aura_L3-OMTO3d_2021m0713_v003.png (342.16 KiB) Not viewed yet

jackyjoy123
Posts: 1
Joined: Tue Sep 07, 2021 9:25 am America/New_York

Re: AURAOMI ozone files with anomalous values

by jackyjoy123 » Tue Sep 07, 2021 9:26 am America/New_York

david.haffner wrote:
> Hello Jacques and all,
>
> I am responsible for the OMI total ozone algorithm. Thank you for posting
> your observations about the anomalous OMI ozone data the began showing up
> in late spring. As you probably are aware, OMI has an instrument anomaly
> that degrades the quality of the data in a subset of the cross-track
> positions within the swath. The effects change with solar angle and also
> time to a degree.
>
> We have an error detection code that flags the affected data but
> occasionally there is a glitch. We found that this had occurred in this
> case and made adjustments to the flagging. The updated data were
> distributed to the Goddard archive (GESDISC) but I don't know if they have
> reached the data source you access. If they have not, please let me know.
>
> Best regards,
> Dave

Thanks for the awesome information.

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