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首页> 外文会议>Instruments, methods, and missions for astrobiology XIII >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：来自无云3D光学地球模型的光谱生物特征年度变化的集成射线追踪模拟

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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：对地球光谱生物特征的了解为从其他恒星系统的潜在类地行星的坍塌光谱信号进行准确的反卷积提供了重要的参考数据。这项研究提出了一种新的光线追踪计算方法，包括使用海岸线和全球生态区（GEZ）地图中的植被分布数据构建的改进的3D光学地球模型。使用非朗伯双向散射分布函数（BSDF）模型，输入地表模型具有三种不同的散射特性，并且它们的年变化取决于植被分布，海冰覆盖范围和照明角度的每月变化。输入大气模型由一层与海平面到海拔100 km的瑞利散射模型组成，并使用SMART代码计算了四个季节的辐射传递特性。海洋散射模型是太阳闪烁散射和朗伯散射模型的组合。陆面散射是通过用于MODIS和POLDER任务的半经验参数核方法定义的。将这三个组件模型集成到最终的地球模型中，然后将其整合到内部构建的集成射线追踪（IRT）模型中，该模型能够计算假设空间仪器从其观测地球时的光谱成像和辐射传输性能指定轨道。 IRT模型模拟输入包括地球方向，光照阶段以及季节性海冰和植被分布的变化。试验模拟运行导致相位相关的磁盘平均光谱（DAS）及其相关生物特征（例如NDVI）的年度变化。介绍了完整的计算细节以及DAS及其相关生物签名的年度变化。

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