MERCATOR OCEAN JOURNA: 
SEPTEMBER 2021 
The inclusion of the additional satellite surface temperature 
products and the dynamical adjustment of SST products 
has led to a significant increase in the performance of the 
öperational product over the last 5 years, when compared 
against in situ observations. 
A new L4 SST/IST reprocessed product has been 
produced and released in 2021. The product is similar to 
the operational product in terms of spatial coverage and 
resolutions and daily fields are available from 1982 to 2019. 
The reprocessed L4 was created by using infrared satellite 
products for surface temperatures from Copernicus 
Climate Change Service (C3S), ESA Climate Change 
Initiative (CCI) and DMIs own products, which have been 
validated against each other, as well as in situ observations 
available. 
The data set contains a consistent climate indicator as It 
consists of both sea and sea ice temperatures, which can 
be used to analyze recent situations and trends. This gap- 
free data set enables the investigation of both general 
temperature tendencies for the whole covered area and 
regional differences in temperature changes. Today’s data 
set only covers the Arctic but developed algorithms can 
also be applied to the Antarctic. 
1.11 Ocean Monitoring Indicators 
The Arctic Sea Ice Extent was introduced in 2018, as an 
Jcean Monitoring Indicator (OMI) covering the period from 
1979 up to the present. Obtaining knowledge about sea ice 
cover changes is essential for monitoring the health of the 
Earth as sea ice is one of the most highly sensitive natural 
anvironments. In 2019, the Antarctic equivalent OMI was 
introduced, the Antarctic Sea Ice Extent, covering the same 
period as in the Arctic. The OMIs show trends in sea ice 
axtent in the Arctic and the Antarcetic, and are highly valuec 
5y climate researchers and policy makers alike. 
ACKNOWLEDG"MENTS 
We would like to acknowledge all contributing SI TAC team members here: Andrew Fleming (BAS), Matilde Brandt-Kreiner, 
Jargen Buus-Hinkler, Jacob Heyer and Wiebke Kolbe (DMI), , Roberto Saldo (DTU), Juha Karvonen and Jaakko Seppänen 
(FMI), Fanny Girard-Ardhuin and Cedric Prevost (IFREMER), Frode Dinessen, Thomas Lavergne, Signe Aabge and Cecilie 
Wettre (MET), Anton Korosov and Mohamed Babiker (NERSC) 
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