静止轨道卫星采用CO2和水汽吸收波段进行红外探测,探测性能受观测波段的大气透过率影响显著,同时,大气折射率随空间位置的变化影响目标的定位精度。通过建立大气中探测路径几何模型,利用FASCODE软件计算出路径上2.7 μm和4.3 μm波段大气透过率和蒙气差并制成图表,蒙气差计算结果与理论估算一致。结果表明,2.7 μm波段大气透过率在5~25 km高度变化显著,35 km以上透过率达95％;4.3 μm波段大气透过率在5~45 km高度变化显著,50 km以上透过率达95％。两个波段的蒙气差相同,对目标位置的影响较少,天顶角8°以内,影响只有50 m量级,超过8°,偏差随角度增长很快,到地球圆盘边缘时达到1 km。通过插值,透过率数据和蒙气差数据可用于系统设计、性能评估和实时仿真。

Detection performance of geostationary satellites is significantly affected by the atmospheric transmittance with the absorption infrared bands of CO2 and water vapor. Positioning accuracy of the target is also affected by the atmospheric refraction. By the geometry model of the atmospheric sounding path and FASCODE software, atmospheric transmittance and refraction are formed on the two bands with tables. The result of refraction is consistent with the theoretical estimates. As for the 2.7 μm band, atmospheric transmittance changes significantly with height of 5~25 km, and reaches 95％ over 35 km, for 4.3 μm band, it changes significantly with height of 5~45 km, and reaches 95％ over 50 km. The refraction of the two bands is same. The deviation of the target location is only 50 meters orders when zenith angle is less than 8 degrees, but increased rapidly with the angle more than 8 degrees, and up to 1km at the edge of the earth disc. By interpolation, the transmittance and refraction data can be used for system design, performance evaluation and real-time simulation.