Primary production z=0m

The total daily primary production is defined as the quantity of organic carbon assimilated by phytoplankton in the water column under unit area of water in 24 h. On the one hand, primary production is the first link in the trophic chain and is thus responsible for supplying the marine ecosystem with energy; on the other, it supplies the environment with oxygen, one of the main products of photosynthesis.

Values of the total primary production are given in milligrams of assimilated carbon per unit area per 24 h [mg C m^-2 d^-1].

The formula enabling one to calculate the total daily primary production gpp, the final product of the DESAMBEM model (Woźniak et al., 2008; Woźniak et al., 2007) takes the form:

$$gpp=\int_{0}^{z(pp(z)=0)}pp(z)dz$$

where

$$pp(z)$$ value of the daily primary production determined at depth z

The upper boundary of integration is given by the depth at which production is so small that it practically no longer affects the total primary production. The DESAMBEM model assumes that this is the depth equal to 3/2 of the thickness of the euphotic layer.

Fig.1. Comparison of empirical PP_{In situ} with modelled PP of primary production in the water column beneath an area of 1 m^2­ in the Baltic. In situ values of primary production PP_{In situ}  were measured during research cruises in 2010-2011, and the modelled values of production PP were determined using the DESAMBEM algorithm.

Methodology

The daily primary production in the Baltic is determined using the DESAMBEM model (Woźniak et al., 2008) and is its final product.

Validation

Validation was carried out for 15 measurement stations in the Baltic. The reason for such a small number of data sets is the considerable complexity of the measurements themselves (measurements made at several depths in the water column at the same measurement station take many hours to complete) and the need to correlate them with satellite data (there may be no input data for the DESAMBEM algorithm during periods of prolonged cloudiness). The in situ production at different depths in the water column was determined using the ¹⁴C method. The measurements were made during cruises on the research vessel Oceania in 2010-2011.

In the case of logarithmic statistics the error factor is x= 2.591; the statistical error is from σ_- = -61.4% to σ₊ =159%.

Table 1. The systematic and statistical errors of estimated primary production values in the water column beneath an area of 1m² in the Baltic in arithmetic and logarithmic statistics. N denotes the number of estimated values of primary production.

Link to the parameter in SatBaltic System:

Primary production z=0m