A Correlated-k Based Ultra-Fast Radiative Transfer (kURT) Method

摘要

A new sensor-specific correlated-k (c-k) ultra-fast radiative transfer (RT) formalism, kURT, has been designed for fast broad-bandpass scene simulations from UV-visible to LWIR wavelengths. A higher resolution RT code (1 cm~(-1) MODTRAN) has been adapted to output 1 cm~(-1) correlated-k parameters for ozone, water, and the combined uniformly mixed species on a pressure-temperature grid, which are merged to form a compact c-k set incorporating the sensor bandpass response function. The compact set is used to compute bandpass transmittance and radiance in near-real time. Scattering parameters (molecular Rayleigh, clouds and aerosols), blackbody and solar functions are cast as compact k-dependent source terms and used in the radiance computations. Preliminary transmittance results for 3-5 and 8-12 micron bandpasses and visible-MWIR sensors yield results within 2% of a 1 cm~(-1) MODTRAN calculation with a two-orders-of-magnitude computational savings. Applications include near-earth broadband propagation and extinction calculations for target detection and recognition, mid-range tracking, and search and rescue operations from ground and low altitude aircraft.