PAR (Photosynthetic Active Radiation) vertical profiles that were obtained from casts with the Sea and Sun MSS90 microstructure probe in the southern part of the Gulf of Trieste near buoy Vida were analyzed in the years from 2011 to 2015. PAR fortnightly profiles were explored with the linear fit of decrease with the depth of logarithm of PAR, normalized with its value in the air. The inverse relation between the coefficient of PAR attenuation and the Secchi disk depth was also validated. Also, other relations (e.g. the bi-exponential non-linear decrease of PAR with depth) were explored. Our findings about the attenuation of PAR and the Secchi disk depth are in line with the study conducted decades ago for the north-eastern part of the Gulf of Trieste (Stravisi, 1999). Furthermore, the initial values of PAR profiles measured with the Sea & Sun probe in the air before the cast were validated with the PAR values measured continuously on buoy Vida, about 100 m away from the profiling measurement station.

In-situ and above water radiometers are a critical for validating Ocean Color Satellite measurements, used to monitor in-water constituents of the global ocean. The calibration process, instrument response characterization, and environmental measurement all contribute to the overall uncertainty budget of the radiometric measurement. An integral part of this uncertainty traceability chain is accurate laboratory calibration of radiometric sensors. Over its lifetime, the Sea-Bird Scientific Halifax site (formerly Satlantic, LP) participated in inter-laboratory comparisons to ensure the quality of its calibrations. These include: NASA’s Seventh SeaWIFS Intercalibration Round-Robin Experiment (SIRREX-7, Hooker et al. 2002), conducted in 1999, compared Halifax to the Center for Hydro-Optics and Remote Sensing (CHORS, San Diego State University, California, USA) and the Joint Research Centre (JRC, Ispra, Italy). More recently, Sea-Bird Scientific participated in the European Space Agency (ESA) sponsored Fiducial Reference Measurements for Satellite Ocean Colour (FRM4SOC) program. In 2017, Sea-Bird Scientific transitioned the manufacturing and calibration of radiometric products from the facility located in Halifax (HAL), Nova Scotia CA to the facility located in Philomath (PHI), Oregon USA (formerly WET Labs, Inc.). As part of this transition, the radiometer calibration facility was reproduced at the Philomath site and Sea-Bird Scientific conducted an extensive cross facility set of experiments to: 1. Quantify relative calibration uncertainties within and between Halifax and Philomath laboratories; 2. Quantify differences in repeatability relative to Halifax (established standard); 3. Compare relative laboratory calibration uncertainties to budget of estimated uncertainty sources; 4. Verify successful transfer of build and calibration processes at Philomath site.

Application of satellite derived models of primary production using ocean colour remote sensing data opens new possibilities of estimation of its time and spatial variability at different scales. However, it is always necessary to take into account that errors of model retrieval can affect wrong interpretation of this variability. In the study we analyzed errors of satellite derived primary production models and explain main reasons of its appearance for a case study of the western part of the Japan/East Sea (35-44 N, 130-137 E). As satellite derived primary production we used data of Vertical Generalized Production Model (VGPM) from Ocean Productivity database. Due to insufficient amount of in situ primary production data in the western part of the Japan/East Sea, satellite derived primary production was compared with modeled assessments, which were got using ship data of model input parameters (chlorophyll-a at different depths, assimilation number, euphotic depth etс). Applied analysis showed three reasons of errors of satellite derived primary production models: (1) accuracy of remote sensing chlorophyll-a, (2) oceanographic conditions - water stratification and (3) accuracy of assimilation number determination.