A three-dimensional infrared radiation code for exhaust system was developed by the finite volume method coupled with narrow band k-distribution in non-gray absorbing-emitting media. The final infrared signature had considered the atmosphere effect

and the simulation values were favorably consistent with testing ones. The results indicate that the relative errors considering the effect of atmosphere compared with that of the contrary condition reduce by 31%

it shows that when simulating the infrared radiation of the target which is received by the infrared detectors

even the calculation band is in atmospheric windows 3~5 μm

the effect of atmospheric transmission on infrared signature of the target should not be neglected.