OSI SAF products affected by outage of SSMIS data 19-22 February 2021

Cécile Hernandez's picture

OSI SAF products using SSMIS data

OSI SAF processes several daily products based on SSMIS: a daily sea-ice concentration product (OSI-401-b) and a daily sea-ice emissivity product (OSI-404-a). Both products have been directly affected by an outage of SSMIS data between 19th and 22nd February 2021. The demonstration sea ice index (OSI-420) was also impacted. 

Sea-ice edge (OSI-402-c), sea-ice type (OSI-403-c) and low resolution sea-ice drift (OSI-405-c) are multi-sensor products. They also use SSMIS data but together with other input data such as AMSR2, so these products were not directly affected.

An alternative sea-ice concentration product, which is not affected by the SSMIS data outage, is the sea-ice concentration product OSI-408 based on AMSR2.

Back to nominal

The input SSMIS data started to come slowly again after Monday 22nd around 00:27 UTC. However, there were many missing sectors and that led to missing data in the final product on 22nd February. Now the SSMIS data are coming as nominal.

More importantly, for the SSMIS Ice Concentration product OSI-401-b, three sensors are used, namely F-16, F-17 and F-18. We experienced that using the F-16 data just after the outage led to corrupted ice concentration values in the final product. So for now we are using only F-17 and F-18. We are investigating how to better quality control the input data to avoid this in the future.

This story will be updated to keep you posted.

Reprocessing of 20-21 February ?

Unfortunately, per our data provider NOAA CLASS, all DMSP SSMIS data prior to 2021-02-21 22:25 UTC will not be recoverable due to an anomaly which occurred at the ground station during planned maintenance. Therefore the OSI-401-b product will not be reprocessed for 20 and 21st February.

There will also be a gap in the sea-ice concentration interim climate data record (ICDR OSI-430-b), delivered with 16 days delay, which will be missing files with date stamps 20210220 and 20210221.

What will happen if there is another outage of SSMIS ?

To prevent the risk of lack of passive microwave sensors, the OSI SAF sea-ice team is working on an alternative source of PMW data for sea-ice products in case the current SSMIS sensors on the DMSP program fails. This alternative source is the MWRI sensor on the Chinese FY-3 satellites.

And in the future ?

JAXA AMSR-3 is still scheduled for April 2023.
EUMETSAT MWI (Metop-SG) will be an alternative to SSMIS from ~2023.