Clouds effect on infrared radiation characteristics measurement

Aircraft infrared radiation characteristic is the important basis of penetration performance evaluation. When we use ground-based infrared radiation measurement system test aircraft in the out-field, goals are often in the clouds, the clouds of infrared radiation absorption and scattering makes the transmittance and background luminance change, which aifect measurement accuracy. Radiative transfer equation is derived and the discrete coordinate method of solving equations. Based on MODTRAN, common cirrus clouds, for example, in the existing infrared wavelengths in different types of transmittance and background brightness under the cirrus simulation analysis. The results showed that the cirrus cloud thickness changes on the transmittance and affect the background brightness, small influence on height change. The thicker the cloudiness its background brightness is large and stable.