The water color simulator WASI: an integrating software tool for analysis and simulation of optical in situ spectra

Abstract

A WINDOWS based program was developed for modeling and analyzing optical in-situ measurements in aquatic environments. It supports 8 types of spectra which are commonly measured by instruments on ship: downwelling irradiance above and below the water surface, upwelling radiance above and below the surface, remote sensing reflectance above and below the surface, irradiance reflectance, specular reflectance at the water surface, absorption, attenuation, and bottom reflectance. These spectra can either be simulated (by forward calculation) or analyzed (by inverse modeling) using well-established analytical models. The variability of a spectrum is determined by up to 25 parameters, depending on the spectrum type. All model constants and input spectra can be changed easily for adaptation to a specific region. Effective methods are included for dealing with series of spectra. For some spectrum types, inversion is a critical task and can produce erroneous results, that is when different parameter combinations cause similar spectra. In order to handle this problem, specific inversion techniques are implemented for critical spectrum types, and measures are included which allow fine-tuning of the fit procedure by the user.