Global elevations are critical to understanding the Earth's dynamic processes and changing climate. These measurements are best acquired from a space‐based vantage point and are most accurate using laser altimetry technology. However, the accuracy associated with the elevation retrievals from laser altimetry relies heavily on the ability to precisely determine the pointing angle of the laser beams from the satellite to the illuminated spot on the surface. The Ice, Cloud, and land Elevation Satellite 2 (ICESat‐2) has a system consisting of instruments that support the determination of the laser pointing direction through a process called Precision Pointing Determination (PPD). In this paper, we describe the PPD conceptual implementation, instrument details, data processing approach, calibration/validation techniques, and performance assessment. We show that the PPD has successfully achieved the allocated accuracy goal essential to meeting the ICESat‐2 geolocation mission requirement.

中文翻译：

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ICESat-2精确指向确定的性能

全球海拔对于了解地球的动态过程和不断变化的气候至关重要。这些测量最好从基于太空的有利位置获取，并且使用激光测高仪技术最为准确。但是，与从激光测高仪获取的高程相关的精度在很大程度上取决于能否准确确定从卫星到表面照明点的激光束的指向角。冰，云和陆地海拔卫星2（ICESat-2）的系统由仪器组成，这些仪器支持通过称为精确指向确定（PPD）的过程确定激光指向的方法。在本文中，我们描述了PPD的概念实现，仪器详细信息，数据处理方法，校准/验证技术以及性能评估。