Hi @Gkikas-LGPZ. I am Vincent-Henri and am in charge of CAMS. What you see on this layer is NO2 concentration at the surface. You rightly point to ship tracks over the Atlantic, Mediterranean. Over the Black Sea, these are also ship tracks, not flight paths. The lines that you point in Russia are motorways (M-11 between Moscow and St Petersburg or M-9 going westwards from Moscow to Latvia). Only a small fraction of NO2 emitted by aircraft make it to the ground directly: this is mostly near airports due to take-off & landing; NO2 emissions by aircraft at cruise level mostly get back to the ground through deposition of HNO3 and would not appear as lines at the surface. I hope this helps!
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RE: Copernicus Atmosphere Monitoring Service (CAMS) data and forecast are now accessible on Windy.