title: MOCRA: a Monte Carlo code for the simulation of radiative transfer in the atmosphere.
abstract: This paper describes the radiative transfer model (RTM) MOCRA (MOnte Carlo Radiance Analysis), developed in the frame of DOAS (Differential Optical Absorption Spectroscopy) to correctly interpret remote sensing measurements of trace gas amounts in the atmosphere through the calculation of the Air Mass Factor. Besides the DOAS-related quantities, the MOCRA code yields: 1- the atmospheric transmittance in the vertical and sun directions, 2- the direct and global irradiance, 3- the single- and multiple- scattered radiance for a detector with assigned position, line of sight and field of view. Sample calculations of the main radiometric quantities calculated with MOCRA are presented and compared with the output of another RTM (MODTRAN4). A further comparison is presented between the NO2 slant column densities (SCDs) measured with DOAS at Evora (Portugal) and the ones simulated with MOCRA. Both comparisons (MOCRA-MODTRAN4 and MOCRA-observations) gave more than satisfactory results, and overall make MOCRA a versatile tool for atmospheric radiative transfer simulations and interpretation of remote sensing measurements.
authors.affiliation: Institute of Atmospheric Sciences and Climate, National Research Council (ISAC-CNR), via Gobetti 101, 40129 Bologna, Italy. m.premuda@isac.cnr.it
authors.forename: Margherita
authors.initials: M
authors.lastname: Premuda
authors.forename: Elisa
authors.initials: E
authors.lastname: Palazzi
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Ravegnani
authors.forename: Daniele
authors.initials: D
authors.lastname: Bortoli
authors.forename: Samuele
authors.initials: S
authors.lastname: Masieri
authors.forename: Giorgio
authors.initials: G
authors.lastname: Giovanelli
mesh_terms: D001272:Atmosphere; D003198:Computer Simulation; D008027:Light; D015233:Models, Statistical; D009010:Monte Carlo Method; D012542:Scattering, Radiation; D012984:Software