Real-time quality assessment for Biogeochemical Argo radiometric profiles

Abstract

An ever-increasing number of Biogeochemical (BGC) Argo floats equipped with radiometric sensors have been deployed across the World Ocean. To date, more than 50,000 vertical profiles from 0 to at least 250 dbar of photosynthetically available radiation and downwelling irradiance at 3, narrow wavelengths have been acquired. For scientific use of radiometric data, corrections for temperature effects and sensor drift are necessary. However, these adjustments are only partially provided in delayed mode, almost a year after acquisition and distribution. This makes automatic, real-time quality control (RT-QC) data processing of BGC-Argo radiometry critically important. Nevertheless, only a range test has been applied to real-time radiometric profiles, so far. By leveraging the full dataset of multispectral radiometric measurements from various BGC-Argo platform types, we have developed a robust RT-QC protocol for processing radiometric data and profiles, aimed at identifying potential sensor malfunctions, particularly those related to temperature effects. Data quality flags are attributed to each data point by considering the expected shape of the radiometric profile associated with the solar elevation during data acquisition. For both daytime and nighttime profiles, the new protocols automatically unveil data potentially dominated by temperature effects. The proposed methodology remains resilient to sensor drift and unstable sea conditions, and it also holds promise for adaptation to data from cutting-edge hyper-spectral sensors mounted on BGC-Argo floats.