MERCATOR OCEAN JOURNA: 
SEPTEMBER 2021 
Automatically generated sea ice concentration based on Sentinel-1 and AMSR2 
1km resolutian Euraretie / 2021-01-12 12:00:00 
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igure &: MET-multisensor SIC estimate from 12 January 202’ 
1.7 Baltic SAR-based sea ice concentration, 
thickness, drift 
The automatic Baltic SIC is provided in CMEMS as a daily 
mMosaic covering the Baltic Sea since December 2020. The 
product resolution is 500 m and each grid cell contains 
the most recent value at hand, defined by the most recent 
S5AR measurement. The SIC estimates are based on a 
combination of JAXA's AMSR2 microwave radiometer and 
C-band dual-polarized (HH/HV polarization combination) 
SAR data from ESA's Sentinel-1 and CSA’s Radarsat-2. The 
algorithm utilizes a multilayer perceptron neural network 
documented in detail in (Karvonen 2017) 
Another new automated Baltic Sea product for the 
winter 2020-2021 is the sea ice thickness (SIT) based on 
Sentinel-1 IW mode dual-polarized (VV/VH) SAR data. This 
product is produced every time after a Sentinel-1 IW mode 
image over Baltic Sea is received at FMI (downloaded from 
ESA's cophub or a dedicated ftp server). The resolution of 
the product is 500 m and the covered area corresponds 
LO the received SAR area. The algorithm consists of SAR 
segmentation and SAR texture feature extraction. The FM 
digitized ice charts are used as a background field as in 
the Sentinel-1 EW mode ice thickness product (Karvoner 
et al., 2003).