Rys.1 Instantaneous distribution of photosynthetically active radiation (PAR) at the surface of the Baltic Sea Rys.2 Comparison of measured (Oceania) and modelled (SolRad) values of PAR in 2010-2012

Promieniowanie fotosyntetycznie czynne (PAR) na powierzchni morza.

The flux density (downward vector irradiance [1]) of solar radiation (wavelength range 400-700 nm) incident on the sea surface and scattered in the atmosphere. Values are expressed in [Wm^-2]. The SatBałtyk system provides maps (spatial resolution 1 km) of daily sums of this radiation as well as instantaneous values at 15-minute intervals.

Methodology

The SolRad model[2] is used to determine downward PAR fluxes. Daily sums (doses) of this irradiance energy are calculated on the basis of instantaneous PAR values measured every 15 minutes. The input data for the model are obtained from the SEVIRI radiometer (HRV spectral channel) deployed on MSG series satellites, AVHRR, TOVS and SBUV/2 radiometers deployed on TirosN/NOAA and Metop series satellites, and from the UM or WRF meteorological models.

Validation

The statistical error, expressed as the standard deviation of the differences between PAR fluxes measured in situ and those determined using the model for instantaneous values, was  σ=40.7 Wm^-2. The systematic error (the mean difference between measured and calculated values) was estimated at -0.06 Wm^-2. The empirical measurements (N=4199) used for validating the model were obtained from the pyranometer on r/v “Oceania”. They were made in 2010-2012 in the southern and central Baltic Sea.

Links to the parameter in SatBaltic System:

Promieniowanie fotosyntetycznie czynne PAR

[1] Dera J., 2003, Fizyka Morza, PWN, Warszawa, 541

[2] SolRad -  Solar Radiation model