Auxiliary Material for
Observing mixed layer depth, nitrate and chlorophyll concentrations in the North
Western Mediterranean: a combined satellite and NO3 profiling floats experiment.
D’Ortenzio Fabrizio1,2, Lavigne Héloïse 1,2, Besson Florent1,2, Claustre Hervé1,2, Coppola
Laurent1,2, Garcia Nicole3, Laës-Huon Agathe4, Le Reste Serge4, Malardé Damien5, Migon
Christophe1,2, Morin Pascal6, Mortier Laurent1,7, Poteau Antoine1,2, Prieur Louis1,2, Raimbault
Patrick3, Testor Pierre1,7
(1) Sorbonne Universités, UPMC Univ. Paris 06, UMR 7093, LOV, Observatoire océanologique, F-06230,
Villefranche/mer, France
(2) CNRS, UMR 7093, LOV, Observatoire océanologique, F-06230, Villefranche/mer, France
(3) MIO, CNRS-Université́ de la Méditerranée, Campus de Luminy, 13288 Marseille, France
(4) Recherches et Développements Technologiques – Electronique, Informatique et Mesures In Situ, RDT-EIM,
IFREMER, Z.I. Pointe du Diable, Plouzané, France.
5) Nke Instrumentation, rue Gutenberg, Z.I. Kerandré, 56700 Hennebont, France.
(6) IPEV, Z.I. Pointe du Diable, Plouzané, France.
(7) Sorbonne Universités (UPMC, Univ Paris 06)-CNRS-IRD-MNHN, LOCEAN, UMR7159, 4 place Jussieu,
F-75005 Paris, France
Geophysical Research Letters
Introduction
In the auxiliary material, we explain the method used to process, calibrate and validate the
nitrate concentrations measured with the two PRONUTS profiling floats.
The method is explained in the file “Auxiliary_material-text01”.
The statistical performances of the method are presented in the table “TS01”, in the file
“Auxiliary_material-ts01.docx”.
1. Auxiliary_material-ts01.docx. Table showing the performances of the nitrates
concentration algorithm, evaluated by comparing the in situ nitrate concentrations (as
obtained from colorimetric analysis at deployment and at recover) and the nitrate
concentrations obtained with ISUS and SUNA instruments. Table indicates the RMS errors,
the correlation coefficients and the number of used samples (N) in the comparison. The lines
“NO3offset_corrected”, “NO3ts_corrected” and “NO3redj” correspond to the different steps of the
algorithms (as explained in the Auxiliary_material-ts01.docx file.)
2. Auxiliary_material-ts02.docx. Table showing the metrics calculated on the PRONUTS and
satellite time series. All the values are indicated as date. “MLD start increase” is defined as
the date where MLD is for the first time greater than 50m. “NO3mld start increase”, “CHL start
increase” and “CHL*MLD start increase” as the date where NO3mld, CHL or CHL*MLD are
for the first time greater than their respective median value + 5%. CHL*MLD is calculated by
multiplying each available CHL value by the most close (in time) MLD estimation, according
to Behrenfeld [2010]. “Max” values for each parameter are the dates where the parameter is
greatest. “Qtot inversion” is calculated from ECMWF ERA-Interim heat fluxes. Heat budget
estimations (Qtot) for the period June 2011 to June 2012 are obtained from ECMWF web site
(www.ecmwf.int). Considering the coarse spatial resolution of the available data (2.5°) only a
single grid point is used for both PRONUTS time series. “Qtot inversion” is the date where
the Qtot values pass from negative to positive [Taylor and Ferrari, 2011]. At least 3 values
are required to fix the data.
3. Auxiliary_material-fs01.pdf. Figure FS01. Trajectories of the two floats (PRONUTS-ISUS,
left; PRONUTS-SUNA right). Colours indicate the sampling period. Black diamonds indicate
the deployment points. The dotted line indicates the limits of the NW Mediterranean
blooming region, as defined by D’Ortenzio and Ribera [2009]. The grey area indicates the
deep convection mixed patch derived by the ocean colour image of the 22th of February 2012,
following the method of de Madron et al. [2013].
4. Auxiliary_material-fs02.pdf. Figure FS02. Time-series of the difference between the
surface (10m) and the deep (800-1000m) raw NO3 values for the SUNA (white circles) and
for the ISUS (black circle).
5. Auxiliary_material-fs03.pdf. Figure FS03. NO3 concentration profiles at the deployment
(SUNA left panel, ISUS central panel) and at the recover (ISUS, right panel). Black lines
represent the raw data with the temporal variable offset correction. Red lines indicate the
previous profiles after the temperature and salinity correction. Blue lines indicate the profile
readjusted if at least one value was negative. Red circles indicate the NO3 in situ estimations
by colourimetric analysis, as derived by water samples collected simultaneously to the
PRONUTS profiles (+/- 3 hours).
6. Auxiliary_material-fs04.pdf. Figure FS04. Scatter plot of the PRONUTS versus in situ
estimations for the different steps of the calibration (grey points indicate the raw data; black
points, the raw data with the temporal variable offset correction; white points, the data with
the salinity and temperature correction). Data at deployment (SUNA left panel, ISUS central
panel) and recover (ISUS right panel) are plotted separately. Note that for the plot of the ISUS
recovery, raw data values are not visible, being too high with respect to the selected axis
scales.