MERCATOR OCEAN JOURNAL 
SEPTEMBER 2021 
since March 2018 and September 2019 (SLSTR-3A/-3B, 
respectively). Overall, these new sensors improved the 
accuracy of both MED and BS NRT products and led to a 
significant decrease in the mean bias and root-mean- 
square difference (RMSD) to in situ data. 
The new MED and BS diurnal products will provide daily L4 
maps of hourly mean subskin SST at 1/16° grid resolution, 
by combining infrared satellite data (SEVIRI) and model 
data from Copernicus MED-MFC and BS-MFC (Marullo 
et al., 2014). MED and BS diurnal products will cover the 
period from 1% January 2019 and 1%* January 2020 up to 
NRT, respectively. The reconstructed Mediterranean diurnal 
cycle has showed a satisfying accuracy when compared 
to In situ data and has performed better than the CMEMS 
model data during the central warming hours (Figure 7) 
Similar results have characterized the Black Sea diurna 
product. 
The MED and BS reprocessed products have known two 
avolutions. These datasets, originally created by using the 
Pathfinder SST dataset v.5.2 (PFV52), were regenerated 
in September 2018 by using the updated Pathfinder v.5.3 
iPFV53). In April 2020, existing datasets were substituted 
Nith two new products based on a reprocessing of climate 
data records provided by ESA CCI (Merchant et al., 2019) anc 
the C3S. These new MED and BS reprocessed products have 
provided 38 years (1982-2019) at 1/20° grid, and routine 
updates are planned to extend datasets forward in time 
Mean diurnal cycle 
ı 0 T T 
np fi gm 
a 
18.0 
4—— 1 DOISST 
3———& Model 
*— A] Drifters 
„r 
M- 
1 
7 
Si 
N 
76 
HH. 
17.4 
_ — 
ii — 
ME Sa 
LE ILL Ir 
10 15 20 
Local Time 
/igure 7: Mean diurnal cycle computed for the Mediterranean Sea diurnal optimally interpolated SST product (DOISST, blue line), model 
(purple line) and drifters‘ data (red line) over a matchups'‘ dataset coverina the complete vear 2019