I. IntroductionII. 0.14 versus 0.45. The difference between the spectra obtained by the T and T-R methods is usually not important for phytoplankton-dominated samples, but may become large for detritus-rich ‘case 2’ water samples (e.g. The error of the optical density of the filter-retained particle sample, ODs, induced by the 25-mm-diameter GF/F filter variability, was evaluated as σ ~ 0.0015, following the routine set-up for accurate T-R measurements. The particle sample is now measured versus void, i.e. Thus, in the ‘transmission mode’, the particle sample is placed against port A1 of the sphere, while port B1 remains open and ports A2 and B2 are closed by Spectralon plates (Figure 1). – Insert ODs given by equation (5) into equation (10) and obtain the equivalent optical density of the particle suspension, ODsus. A thorough sensitivity analysis of the ‘Transmittance–Reflectance’ (T-R) method for measuringin vivo light absorption by aquatic particles retained on glass-fiber filters has been carried out. The similarity of the OD spectra for pigment obtained by the T and T-R methods, even in the presence of large detritus absorption, is an indication that in this case scattering was not modified by NaClO bleaching. But, some amount of light will be absorbed by the molecules of light. The situation changed when the routine was modified with the use of the 25-mm-diameter GF/Fs, whose surface is less uniform than that of the 47-mm-diameter filters. The measured optical density spectra were converted to suspension optical density by means of equations (17) (T method) and (18) (T-R method) in Tassan and Ferrari (Tassan and Ferrari, 1995a). The optical density spectra obtained by the T-R and T methods are shown by the medium and thin lines (labeled T and T-R). The stability of the correlation expressed by equation (10) was confirmed by the results of a large series of in situ measurements carried out on samples collected from coastal water in the Northern basin of the Adriatic Sea (Tassan et al., 2000). For a detailed error analysis of the NaClO chemical oxidation procedure, see Ferrari and Tassan (Ferrari and Tassan, 1999). The analysis of the optical density error induced by the GF/F variability was performed as for the previous test, yielding the ODs spectra shown in Figure 3B. – Place the sample holder against port A2 of the sphere (backed by a black trap), with ports A1 and B1 open, and port B2 closed by a Spectralon plate (Figure 1): the result of the measurement is the ratio ρRs. of San Luis Potosi, Camino a la Presa San José 2055, 78216, San Luis Potosí, The method is based on a recently found new representation for solutions of Although being higher than the standard deviation of the accurate T-R measurement, σ ~ 0.004 is an acceptable value, as shown by the overall error computation presented in Section 7 (Figure 8). The reader spcifically interested in the theoretical computation of the absorption amplification factor is referred to Roesler (Roesler, 1998) and to Lohrenz (Lohrenz, 2000). This is a colored sediment (clay containing iron oxides), with absorption as the prevailing contributor to ODtr(750) (~75%). This method gives the exact solutions, since it takes into account both the effect of refraction and multiple reflections at the interfaces of the dielectric discontinuities. if it causes a significant change in the particle size distribution. The BRDF is often abbreviated by the Greek letter ρ, which bears the danger of mixing the BRDF up with reflectance (see foregoing paragraph). Transmittance and reflectance are closely related concepts. (Supervisory Control and Data Acquisition), Programmable Logic Controllers (PLCs): Basics, Types & Applications, Diode: Definition, Symbol, and Types of Diodes, Thermistor: Definition, Uses & How They Work, Half Wave Rectifier Circuit Diagram & Working Principle, Lenz’s Law of Electromagnetic Induction: Definition & Formula, Transmittance is a ratio of the incident intensity of light (I. Absorbance is defined as the amount of light absorbed by the molecules of the object. The reflection and transmission of finite inhomogeneous layers are considered. Thus, for computational purposes, the reflected light can be assimilated to a point source 0.1 mm from the sphere entrance. The validity of the ODsus versus ODs correlation of the T-R method, i.e. The optical density related to pigment absorption was obtained by subtracting the optical density spectrum measured after depigmentation from the original spectrum. In terms of the measured filter optical density, one observes almost wavelength-independent shifts, associated with this variability. The corresponding error of the optical density of the particle suspension, ODsus, has been obtained by differentiation of the equation expressing the experimental correlation (ODsusversus ODs); the error increases with the optical density value, from σ= 0.0015 (for ODsus = 0.05) to σ= 0.027 at the upper limit of the optical density range tested (ODsus = 0.59).