Quasi-Physical Model for Converting Hourly Global Horizontal to Direct Normal Insolation

<p>Numerous research studies have shown that the use of a single regression function does not adequately characterize the relationship between direct beam transmittance (Kn) and the effective global horizontal transmittance (Kt). Therefore the Direct Insolation Simulation Code (DISC) employs an exponential relationship between ..delta..Kn and air mass which is parametric in Kt. This algorithm seems to provide a satisfactory Kn-Kt relationship for a wide range of stations and seasons. Validation of the DISC Model was accomplished with data from three widely separated stations (albuquerque Bismarck and Brownsville) which were not used for model development. Comparisons with the ETMY model (used to generate direct normal data for 222 of the 248 stations in the national data base) showed substantial improvements in the accuracy of hourly values significant reductions in monthly RMS errors and equivalent monthly mean bias errors. Furthermore modification of the DISC model to incorporate cloud-cover water vapor and albedo terms appears to be straightforward.</p><p>This work has been selected by scholars as being culturally important and is part of the knowledge base of civilization as we know it. This work was reproduced from the original artifact and remains as true to the original work as possible. Therefore you will see the original copyright references library stamps (as most of these works have been housed in our most important libraries around the world) and other notations in the work.</p><p>This work is in the public domain in the United States of America and possibly other nations. Within the United States you may freely copy and distribute this work as no entity (individual or corporate) has a copyright on the body of the work.</p><p>As a reproduction of a historical artifact this work may contain missing or blurred pages poor pictures errant marks etc. Scholars believe and we concur that this work is important enough to be preserved reproduced and made generally available to the public. We appreciate your support of the preservation process and thank you for being an important part of keeping this knowledge alive and relevant.</p>