星载太赫兹高频段大气背景辐射特性研究

太赫兹7~10 THz与红外相邻, 在空间态势感知、目标探测领域具有独特的优势。本文基于辐射传输原理对大气背景辐射特性进行研究。利用高分辨率分子吸收谱线数据库(high-resolution transmission molecular absorption database,HITRAN)对大气辐射传输模拟器(atmospheric radiative transfer simulation,ARTS)进行太赫兹高频段频谱扩展。结合欧洲中尺度天气预报中心再分析数据集中期(European center for medium-range weather forecasting reanalysis-interim,ERA-interim)仿真冬夏两季海洋与沙漠的大气透过率。再选用窗口频段和吸收频段的点频仿真月平均和单日全球大气背景亮温, 分析温度和水汽敏感性。结果表明, 吸收频段相较于窗口频段背景亮温更低更稳定, 可作为空间目标探测的频段选择; 窗口频段亮温的主要贡献来自温度水汽变化频繁的对流层0~10 km高度, 吸收频段则来自于温度水汽稳定的平流层15~30 km高度, 这是导致大气背景亮温差异的重要原因。

Study on the characteristics of high terahertz band atmospheric background radiation observed from satellites

The range of 7~10 THz is adjacent to infrared, which has unique advantages in the domain of space situational awareness and target detection. Based on the principle of radiation transmission, the characteristics of atmospheric background radiation are studied in this paper. The high terahertz band of the atmospheric radiative transfer simulation (ARTS) is extended by using high-resolution transmission molecular absorption database (HITRAN). Combined with European center for medium-range weather forecasting reanalysis-interim (ERA-interim), the atmospheric transmittance at ocean and desert in winter and summer is simulated. The single frequency of window and absorption band is selected to simulate the monthly mean and single day brightness temperature of global atmospheric background, and analyze the sensitivity of temperature and water vapor. The results show that compared with the window band, the background brightness temperature of the absorption band is lower and more stable, which can be used as a band selection for space target detection. The main contribution of background brightness temperature in window band comes from 0-10 km height of troposphere with rapid temperature and water vapor changes, while the absorption band comes from 15-30 km height of stratosphere with stable temperature and humidity, which is an important reason for the difference of atmospheric background brightness temperature.