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首页> 外文会议>SPIE Conference on Instruments, Methods, and Missions for Astrobiology >Integrated ray tracing simulation of annual variation of spectral bio-signatures from cloud free 3D optical Earth model
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Integrated ray tracing simulation of annual variation of spectral bio-signatures from cloud free 3D optical Earth model

机译：集成光线跟踪模拟云自由3D光接地模型的频谱生物签名年变化

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Understanding the Earth spectral bio-signatures provides an important reference datum for accurate de-convolution of collapsed spectral signals from potential earth-like planets of other star systems. This study presents a new ray tracing computation method including an improved 3D optical earth model constructed with the coastal line and vegetation distribution data from the Global Ecological Zone (GEZ) map. Using non-Lambertian bidirectional scattering distribution function (BSDF) models, the input earth surface model is characterized with three different scattering properties and their annual variations depending on monthly changes in vegetation distribution, sea ice coverage and illumination angle. The input atmosphere model consists of one layer with Rayleigh scattering model from the sea level to 100 km in altitude and its radiative transfer characteristics is computed for four seasons using the SMART codes. The ocean scattering model is a combination of sun-glint scattering and Lambertian scattering models. The land surface scattering is defined with the semi empirical parametric kernel method used for MODIS and POLDER missions. These three component models were integrated into the final Earth model that was then incorporated into the in-house built integrated ray tracing (IRT) model capable of computing both spectral imaging and radiative transfer performance of a hypothetical space instrument as it observes the Earth from its designated orbit. The IRT model simulation inputs include variation in earth orientation, illuminated phases, and seasonal sea ice and vegetation distribution. The trial simulation runs result in the annual variations in phase dependent disk averaged spectra (DAS) and its associated bio-signatures such as NDVI. The full computational details are presented together with the resulting annual variation in DAS and its associated bio-signatures.
机译：理解地球光谱生物签名提供了一种重要的参考基准，用于来自其他星系的潜在地球状行星的折叠光谱信号的精确去卷积。该研究提出了一种新的射线跟踪计算方法，包括从全球生态区（GEZ）地图的沿海线和植被分布数据构造的改进的3D光学地球模型。使用非灯泡双向散射分配功能（BSDF）模型，输入接地表面模型具有三种不同的散射特性及其年度变化，具体取决于植被分布的月度变化，海冰覆盖和照明角度。输入气氛模型由一层与瑞利散射模型的海拔高度为100公里，使用智能码计算四季的辐射传输特性。海洋散射模型是太阳云散射和兰伯特散射模型的组合。使用用于MODIS和Bolder任务的半经验参数核方法来定义陆地散射。将这三个组件模型集成到最终地球模型中，然后将其纳入内部内置的集成光线跟踪（IRT）模型，能够计算假设空间仪器的光谱成像和辐射传递性能，因为它从其观察到地球指定轨道。 IRT模型模拟输入包括地球取向，照明阶段和季节性海冰和植被分布的变化。试验模拟运行导致相位依赖磁盘平均光谱（DAS）的年度变化及其相关的生物签名，例如NDVI。完整的计算细节与所产生的DAS及其相关生物签名的年度变化一起呈现。

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