As of June 2018 the AODN has ceased publication and distribution of the AODN Newsletter.  All AODN updates including the progress of current projects, AODN activities and collaborations, past and upcoming events and new data available through the AODN Portal will now be published via the IMOS Bulletin and IMOS Marine Matters

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New IMOS Multi-sensor Satellite SST Composites to replace existing products

Due to the orbital decay of the NOAA-18 and NOAA-19 satellites, the IMOS AVHRR L3S SST products are likely to become unusable by the end of February. You should use the new operational IMOS Multi-Sensor L3S products instead.

Sea surface temperatures from the NOAA-19 AVHRR sensor have exhibited larger than usual errors since 3rd September 2018, associated with the satellite passing for the first time into a fully sunlit orbit. NOAA-18 is expected to pass into a full-sun regime in late February 2019. Users are alerted to possible degradation in accuracy of IMOS AVHRR L3S SST products in coming weeks. The new operational IMOS Multi-Sensor L3S products are recommended for use.

IMOS has produced a 27-year suite of satellite-based sea surface temperature (SST) composites on a 0.02 deg x 0.02 deg grid, using locally received data from AVHRR sensors aboard the series of NOAA Polar-Orbiting Environmental Satellites (NPOES). From 2018, NOAA officially replaced the AVHRR sensor program with the Visible Infrared Imaging Radiometer Suite (VIIRS) sensor program, after a long trial which began with the first VIIRS sensor launch in 2012 aboard the Suomi National Polar-orbiting Partnership (NPP) platform. IMOS has, since 16th November 2018, included the VIIRS SST from NPP in a new suite of Multi-sensor operational real-time SST products, resulting in improvements to overall quality, accuracy and coverage. This new product is intended to be a drop-in replacement for the existing AVHRR-only product set, with similar file format. For further information and data access please read this short article.

NOAA-18 and NOAA-19 are the last in the series of operational NPOES satellites to carry AVHRR sensors, starting with NOAA-6 in 1981, although they are still carried on the European Space Agency (ESA) MetOp series of polar-orbiters. Orbital decay of NOAA-18 and NOAA-19 during recent years has affected the accuracy of the real-time IMOS AVHRR SST products during some months. The AVHRR sensor on NOAA-19 was adversely affected by passing for the first time into a fully sunlit orbit on 13th September 2018, and from 29th September 2018 SSTs from this satellite have not contributed to the IMOS AVHRR-only L3S products. NOAA-18 is expected to pass into a similar full-sun orbit in late February 2019, with degradation in SST accuracy expected. It is therefore recommended that users requiring accurate 2 km SST composites over the Australian region consider using the new IMOS Multi-sensor L3S.

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