<title>Line-by-line radiative parameters databases in atmosphere sensing and modeling applications</title>

Abstract

This work is mainly focused on the application of the line-by-line (LBL) radiative parameters databases in processing satellite low-resolution measurements of outgoing solar and JR radiation associated with two space instruments such as the Scanner of Radiation Budget (ScaRab on Meteor-3/7 experiment) and ISTOK-1 (PRIRODA-MIR mission). Details of the efficient computer techniques for a routine but accurate calculations of solar and JR radiative parameters in order to develop the benchmark databases are briefly described. Some practical results are presented that involve the utilization of line-byline benchmarks in the ScaRaB measurement validation. The narrow-band model designed for the ISTOK-1 measurement processing and developed on the basis on the LBL precalculations is presented. Keywords: Earth radiation budget, line-by-line technique, benchmark calculation database, aerosols, broken cloudiness, narrow-band radiative transfer model. . GENERAL REMARKSSince the reliable and well-documented compilation atlases containing line parameters of the atmosphere gases absorption bands became available' fairly wide set of more or less sophisticated numerical models based upon the line-by-line (LBL) technique have been developed.2 As it is known these models enable the most straightforward and accurate calculation of different both the solar and the JR radiative transfer characteristics in the atmosphere. However in spite of the noticeable progress either in the modem computer facilities or in the improvement of numerical releases of the LBL technique by itself a practical application of such models as a direct component of the algorithms to process measurements involving parameters of the Earth-atmosphere outgoing radiation is as a rule associated with the instruments representative of the narrow operating diapason and the high spectral resolution. Unfortunately this is caused by copious amounts of computer time consumed in performing the accurate spectral and spatial integration within the framework of usually repeated radiative parameter calculations that in turn makes the accurate LBL based models impractical from the point of view of their direct employment in processing the wide-band radiative measurements. In the same time the last does not mean that the LBL models may not be efficiently used with application to the wide-band measurement processing. In particular these models may be utilized to form the databases containing so-called benchmark radiative calculations2, i.e. sufficiently extensive data sets of calculated radiative transfer parameters obtained for a wide series of fixed realizations of the atmosphere and Earth surface state. Specially composed such databases may be evidently used to develop, tune and validate the computationally efficient parameterized models, i.e. those based upon various approximate approaches of the radiative transfer theory, that may be ultimately exploited as the direct problem component of the procedures designed for the secondary satellite data processing. One of such paramete...