United States of America as Represented by the Secretary of the Air Force

David C Robertson

Gail P Anderson

James H Chetwynd

Lawrence S Bernstein

Alexander Berk

Prabhat K Acharya

Eric P Shettle

Leonard W Abreu

Francis X Kneizys

Larry Bernstein

Lex Berk

Recent upgrades to the MOTRAN atmospheric radiation code improve the accuracy of its radiance predictions, especially in the presence of clouds and thick aerosols, and for multiple scattering in regions of strong molecular line absorption. MODTRAN3.5 features a generalized specification of cloud properties, while research version MODTRAN4 implements a Correlated-k (CK) approach for more accurate calculation of multiply scattered radiance. Comparisons to cloud measurements demonstrate the viability of the CK approach. The impact of these upgrades on predictions for AVIRIS viewing scenarios is discussed for both clear and clouded skies; the CK approach provides refined predictions for AVIRIS nadir and near-nadir viewing.

System and method for modelling moderate resolution atmospheric

MODTRAN is a moderate resolution model and computer code used to predict atmospheric transmittance and background radiance in the microwave, infrared, visible and near ultraviolet spectral regions (0 to 50,000 cm.sup.-1 or 0.2 m to infinity). The code maintains complete compatibility with LOWTRAN 7, specifically, MODTRAN retains all of the capabilities of the LOWTRAN 7 model. Both codes contain the same six built-in model atmospheres; spherical refractive geometry, aerosol models, clouds (water and ice), rain attenuation and options to calculate single scattered solar/lunar radiance, solar/lunar irradiance and multiply scattered thermal and solar radiance. The MODTRAN code improves LOWTRAN'S spectral resolution from 20 to 2 cm.sup.-1 full width/half maximum (fwhm) with an option to vary the resolution between 2 and 50 cm.sup.-1 (fwhm). The band model parameters were formulated from the HITRAN line atlas for twelve atmospheric gases: H.sub.2 O, CO.sub.2, O.sub.3, N.sub.2 O, CO, CH.sub.4, O.sub.2, NO, SO.sub.2, NO.sub.2, NH.sub.3, and HNO.sub.3. These parameters were calculated for 1 cm.sup.-1 bins from 0-17900 cm.sup.-1 at 5 temperatures from 200 to 300 degrees K, all stored on an external data file which is accessed by the program.

System for modelling moderate resolution atmospheric propagation

Growing community of inventors

Bedford, MA, United States of America

David C Robertson