Assessment of the spectral downward irradiance at the surface of the Mediterranean Sea using the radiative Ocean-Atmosphere Spectral Irradiance Model (OASIM)

Abstract

Abstract. A multiplatform assessment of the Ocean–Atmosphere Spectral Irradiance Model (OASIM) radiative model focussed on the Mediterranean Sea for the period 2004–2017 is presented. The BOUée pour l'acquiSition d'une Série Optique à Long termE (BOUSSOLE) mooring and biogeochemical Argo (BGC-Argo) float optical sensor observations are combined with model outputs to analyse the spatial and temporal variabilities in the downward planar irradiance at the ocean–atmosphere interface. The correlations between the data and model are always higher than 0.6. With the exception of downward photosynthetic active radiation and the 670 nm channel, correlation values are always higher than 0.8 and, when removing the inter-daily variability, they are higher than 0.9. At the scale of the BOUSSOLE sampling (15 min temporal resolution), the root mean square difference oscillates at approximately 30 %–40 % of the averaged model output and is reduced to approximately 10 % when the variability between days is filtered out. Both BOUSSOLE and BGC-Argo indicate that bias is up to 20 % for the irradiance at 380 and 412 nm and for wavelengths above 670 nm, whereas it decreases to less than 5 % at the other wavelengths. Analysis of atmospheric input data indicates that the model skill is strongly affected by cloud dynamics. High skills are observed during summer when the cloud cover is low.

Effects of solar irradiance noise on a complex marine trophic web

“…The time series of the experimental data presents quite a few gaps in time due to the malfunction of the buoy. This aspect has been remedied by merging the experimental data with those of the OASIM model validated for the Boussole site 61 (yellow points). The latter is a multispectral atmospheric radiative transfer model that is in turn forced by experimental-model data based on ECMWF ERAINTERIM reanalyses which provide, for example, cloud cover data.…”

“…( c ) Irradiance noisy fluctuations (INF), obtained by subtracting the three-month running mean curve (3MRM) from the daily running mean one (DRM) and normalizing with respect to the mean value of 3MRM ( ), namely ; the red line represents the mean value of such fluctuations. Data already presented and validated in 61 . …”

“…It is interesting to note that the noise influence on the ecosystem strongly depends on both and D , that is, just an intense noise is not enough to generate a greater response of the ecosystem. In particular, experimental data are characterized by a CV approximately equal to 0.3 61 , which corresponds to values of D and lying on the diagonal strip in Fig. 2 ranging from to .…”

Radiometry on Argo Floats: From the Multispectral State-of-the-Art on the Step to Hyperspectral Technology

“…Readily, this dataset has demonstrated also its utility in improving numerical biogeochemical modeling (Terzić et al, 2019). Other reviewed studies provided that PAR and/or Ed have also successfully used to validate IOP parameterizations (Lazzari et al, 2021). Biogeochemical quantities like chl-a and CDOM were also retrieved from K d (490) and K d (412), respectively (Xing et al, 2011(Xing et al, , 2012, and other related studies disclosed their main drivers (Organelli and Claustre, 2019).…”

Chromophoric dissolved organic matter dynamics revealed through the optimization of an optical-biogeochemical model in the NW Mediterranean Sea

“…Local CDOM production includes the excretion of phytoplankton, which depends on light 100 and nutrient availability, the bacterial production and consumption, and zooplankton activities. The version of BFM used here resolves the spectral light transmission underwater (Terzić et al, 2021;Lazzari et al, 2021a) and simulates the inherent optical properties (IOPs) of CDOM, phytoplankton and organic detritus in the water column. Therefore, model output can be compared with a range of optical observations made in the field and remotely.…”