Abstract We deployed four Bio‐Argo profiling floats in various oligotrophic locations of the Pacific subtropical gyres and Mediterranean Sea to address seasonal phytoplankton dynamics euphotic layer explore its dependence on light regime dynamics. Results show that there is a similar biomass pattern observed oceanic regions. In lower part layer, displacement deep chlorophyll maximum (DCM) driven. During winter, concentration ([Chl ]) always increases upper mixed layer. This increase results...

Stratified oceanic systems are characterized by the presence of a so-called Deep Chlorophyll Maximum (DCM) not detectable ocean color satellites. A DCM can either be phytoplankton (carbon) biomass maximum (Deep Biomass Maximum, DBM), or consequence photoacclimation processes photoAcclimation DAM) resulting in increase chlorophyll per carbon. Even though these (further qualified as DBMs DAMs) have long been studied, no global-scale assessment has yet undertaken and large knowledge gaps still...

The emerging availability of Biogeochemical-Argo (BGC-Argo) float data creates new opportunities to combine models and observations in investigations the interior structures dynamics marine ecosystems. An existing variational assimilation scheme (3DVarBio) has been upgraded coupled with Copernicus Marine Environment Monitoring Service biogeochemical model Mediterranean Sea assimilate BGC-Argo chlorophyll profile observations. Our results show that is feasible. Moreover, proposed framework...

The North Atlantic bloom corresponds to a strong seasonal increase in phytoplankton that produces organic carbon through photosynthesis. It is still debated what physical and biological conditions trigger the bloom, because comprehensive time series of vertical distribution biomass are lacking. Vertical profiles from nine floats sampled waters every few days for couple years reveal populations start growing early winter at very weak rates. A proper with rapidly accelerating population growth...

[1] Eight autonomous profiling floats equipped with miniaturized radiometers and fluorimeters have collected data in Pacific, Atlantic, Mediterranean offshore zones. They measured particular 0–400 m vertical profiles of the downward irradiance at three wavelengths (412, 490, 555 nm) chlorophyll a fluorescence. Such sensors collect radiometric regardless sky conditions essentially uncalibrated fluorescence data. Usual processing calibration techniques are no longer usable such remote to be...

Abstract. As commonly observed in oligotrophic stratified waters, a subsurface (or deep) chlorophyll maximum (SCM) frequently characterizes the vertical distribution of phytoplankton Mediterranean Sea. Occurring far from surface layer “seen” by ocean colour satellites, SCMs are difficult to observe with adequate spatio-temporal resolution and their biogeochemical impact remains unknown. Biogeochemical-Argo (BGC-Argo) profiling floats represent appropriate tools for studying dynamics SCMs....

Abstract A neural network‐based method is developed to assess the vertical distribution of (1) chlorophyll a concentration ([Chl]) and (2) phytoplankton community size indices (i.e., microphytoplankton, nanophytoplankton, picophytoplankton) from in situ profiles fluorescence. This (FLAVOR for Fluorescence Algal communities Vertical Oceanic Realm) uses as input only shape fluorescence profile associated with its acquisition date geo‐location. The network trained validated using large database...

The necessity of wide, global-scale observing systems for marine biogeochemistry emerged dramatically in the last decade. A global network based on Biogeochemical (BGC) Argo floats is considered as one most promising approaches reaching this goal. As a first step, pilot studies were encouraged to test feasibility BGC-Argo array, consolidate methods and practices under development, set up array's characteristics. study Mediterranean Sea—deemed suitable candidate case because it combines...

Abstract. In vivo fluorescence of Chlorophyll-a (Chl-a) is a potentially useful property to study the vertical distribution phytoplankton biomass. However technique presently not fully exploited as it should be, essentially because difficulties in converting signal into an accurate Chl-a concentration. These arise noticeably from natural variations relationship, which under control community composition well their nutrient and light status. As consequence, although profiles are likely most...

The biological carbon pump (BCP) contributes to the oceanic CO2 sink by transferring particulate organic (POC) into deep ocean. magnitude and efficiency of BCP is likely vary on timescales days seasons, however characterising this variability from shipboard observations challenging. High resolution, sustained primary production particle fluxes autonomous vehicles offer potential fill knowledge gap. Here we present a 4 month, daily, 1 m vertical resolution glider dataset, collected in high...

Numerical models of ocean biogeochemistry serve as critical tools for detecting and predicting the impacts climate change on marine resources, monitoring health. Recent research by Rodgers et al. (2023) has identified significant limitations in current CMIP6 class models, particularly their representation seasonal partial pressure CO2 (pCO2) temporal phasing magnitude key regions such North Atlantic. These arise primarily from parameter uncertainty, model parameters are typically derived...

Abstract Biogeochemical (BGC)‐Argo floats observations are becoming a major data source for assimilation into and constraining of ocean biogeochemical models. An important prerequisite successful synthesis between models is the characterization observational errors in BGC‐Argo float data. The root‐mean‐square error multiplicative additive biases quality‐controlled sets oxygen, nitrate, chlorophyll concentrations collected with 17 Mediterranean Sea 2013 2017 assessed using triple collocation...

Abstract Based on in situ data sets collected using two Bio‐Argo floats deployed the subpolar North Atlantic from June 2008 to May 2010, present study focuses seasonal variability of three bio‐optical properties, i.e., chlorophyll‐a concentration ([Chla]), particle backscattering coefficient at 532 nm (b bp (532)), and beam attenuation 660 (c p (660)). In addition, interrelationships among these properties are examined. Our results show that: (1) [Chla], b (532) c (660) largely well coupled...

Abstract. As part of the Copernicus Marine Environment Monitoring Service (CMEMS), a physical–biogeochemical coupled model system has been developed to monitor and forecast ocean dynamics marine ecosystem European waters more specifically on Iberia–Biscay–Ireland (IBI) area. The CMEMS IBI covers north-east Atlantic Ocean from Canary Islands Iceland, including North Sea western Mediterranean, with NEMO-PISCES 1∕36∘ application. providing 7 d weekly forecasts for since April 2018. Prior its...

Abstract. Numerical models of ocean biogeochemistry are becoming the major tools used to detect and predict impact climate change on marine resources monitor health. However, with continuous improvement model structure spatial resolution, incorporation these additional degrees freedom into fidelity assessment has become increasingly challenging. Here, we propose a new method provide information predictive skill in concise way. The is based conjoint use k-means clustering technique, metrics,...

Abstract. This study assesses marine community production based on the diel variability of bio-optical properties monitored by two BioGeoChemical-Argo (BGC-Argo) floats. Experiments were conducted in distinct Mediterranean systems, northwestern Ligurian Sea and central Ionian Sea, during summer months. We derived particulate organic carbon (POC) stock gross integrated within surface, euphotic subsurface chlorophyll maximum (SCM) layers, using an existing approach applied to cycle...

Abstract. Recent observations have shown that phytoplankton biomass increases in the North Atlantic during winter, even when mixed layer is deepening and light limited. Current theories suggest this due to a release from grazing pressure. Here we demonstrate often-used models are linear at low concentration do not allow for wintertime increase biomass. However, mathematical formulations of as function quadratic concentrations (or more generally decrease faster than linearly decreases) can...

Abstract. The North Atlantic spring bloom is a massive annual growth event of marine phytoplankton, tiny free-floating algae that form the base ocean's food web and generates large fraction global primary production organic matter. conditions trigger onset in Nordic Seas, at northern edge Atlantic, are studied using situ data from six bio-optical floats released north Arctic Circle. It often assumed blooms start as soon phytoplankton cells daily irradiance sufficiently abundant division...

Abstract. As commonly observed in oligotrophic stratified waters, a Subsurface (or Deep) Chlorophyll Maximum (SCM) frequently characterizes the vertical distribution of phytoplankton chlorophyll Mediterranean Sea. Occurring far from surface layer seen by ocean color satellites, SCMs are difficult to observe with adequate spatio-temporal resolution and their biogeochemical impact remains unknown. BioGeochemical-Argo (BGC-Argo) profiling floats represent appropriate tools for studying dynamics...

Abstract. The Rhodes Gyre is a cyclonic persistent feature of the general circulation Levantine Basin in eastern Mediterranean Sea. Although it located most oligotrophic basin Sea, relatively high primary production area due to strong winter nutrient supply associated with formation Intermediate Water. In this study, 3D coupled hydrodynamic–biogeochemical model (SYMPHONIE/Eco3M-S) was used characterize seasonal and interannual variability Gyre's ecosystem estimate an annual organic carbon...

Abstract. This study assesses marine biological production of organic carbon based on the diel variability bio-optical properties monitored by two BioGeoChemical-Argo (BGC-Argo) floats. Experiments were conducted in distinct Mediterranean systems, Northwestern Ligurian Sea and Central Ionian during summer months. We derived particulate (POC) stock gross community integrated within surface, euphotic subsurface chlorophyll maximum (SCM) layers, using an existing approach applied to cycle...

Abstract. The South Pacific Subtropical Gyre (SPSG) is a vast and remote area where large uncertainties on variability in phytoplankton biomass production remain due to the lack of biogeochemical situ observations. In such oligotrophic environments, ecosystems are predominantly controlled by nutrients depletion surface waters. However, this character can be disturbed vicinity islands enhancement biological activity known occur (i.e. island mass effect, IME). This study mainly focuses...