MERCATOR OCEAN JOURNA: 
SEPTEMBER 2021 
1.6 CANYON Nutrient profiles 
A new biogeochemical MY product for nutrients has 
been available since April 2019. The so-called method 
CANYON-B (CArbonate system and Nutrients concentration 
from hYdrological properties and Oxygen using a Neural- 
network) is inherited from EU H2020 AtlantOS project 
and R.Sauzede PhD thesis and is developed by LOV/ 
IMEV. It relies on a neural-network method to derive, from 
simple and cost-effective measured parameters from 
Biogeochemical-Argo (BGC-Argo) profiling floats, some 
more complex biogeochemical measurements, not yet 
easily or cost-effectively amenable to robotic detection 
(Sauzede et al., 2017; Bittig et al., 2018). CANYON-B uses 
measurements of temperature, salinity, pressure, and 
02 together with sampling latitude, longitude, and date 
to retrieve concentrations of three nutrients including 
nitrates, phosphates and silicates. It has been trained on 
high quality nutrient data collected over the last 30 years 
and made available through the GLODAPv2 database. It is 
then applied to all available delayed-mode qualified BGC- 
Argo profiling floats equipped with an oxygen sensor 
Three versions of the product have been successively 
released. Each time, new profiles according to the 
availability of new BGC-Argo-0, delayed-mode data were 
included. The 1* publication in April 2019 covered the June 
2004 to November 2018 period with 30 338 profiles. The 
2° publication in April 2020 covered the June 2004 to June 
2019 period with 44 934 profiles. The 3'* publication in May 
2021 extended from September 2002 until December 2020 
with a total of 98 789 profiles. Mediterranean Sea profiles 
were also added in this last release using a specifically 
developed regional method called CANYON-MED (Fourrier 
et al., 2020). 
An example located in the North Western Mediterranear 
Sea shows winter mixing in input fields (temperature, 
salinity, oxygen) in February/March 2013 and associatec 
uplift of reconstructed nutrients (Figure 4). 
enperaturg 
u“ 
z 
.. 1 
78 & 
78 
a 
PA 
ıgure &; Depth/Time Temperature (in °C), Salinity (in psu) and Oxygen {in umol kg”) measurements from Argo float WMO 6901467 located 
in the North Western Mediterranean Sea and associated Nitrate, Phosphate and Silicate (in umol kg“) profiles as reconstructed by CANYON- 
MED (Fourrier et al., 2020)