The Surface Biology and Geology (SBG) investigation will create global maps of spectral surface reflectance and emissivity at a cadence of 16 days or better, with coverage to address global questions about Earth's geology, cryosphere and ecosystems. The revolutionary potential poses a commensurate challenge: creating contiguous maps free from regional biases induced by atmosphere, observation geometry, or inversion error. This will require an accurate calibration with precise knowledge of each channel's spectral response. Here, we quantify the impact of spectral calibration on SBG's aquatic and terrestrial ecosystem objectives. We find that contemporary algorithms for ecosystem trait retrieval demand more accurate spectral calibration than historical missions. Errors due to drift or spatial nonuniformity in the wavelength calibration that have previously been considered acceptable can cause systematic errors larger than the instrument noise and of the same order as the variability SBG aims to measure. Moreover, their impact on atmospheric correction can induce climate-dependent systematic errors that thwart comparisons between ecosystems. These results underscore the importance of spectral response accuracy in SBG mission design.

中文翻译：

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地球陆地和水生生态系统的光谱保真度

地表生物学和地质学 (SBG) 调查将以 16 天或更长时间的节奏创建光谱表面反射率和发射率的全球地图，覆盖范围以解决有关地球地质、冰冻圈和生态系统的全球问题。革命潜力带来了相应的挑战：创建连续地图，不受大气、观测几何或反演误差引起的区域偏差的影响。这将需要精确校准，并准确了解每个通道的光谱响应。在这里，我们量化了光谱校准对 SBG 的水生和陆地生态系统目标的影响。我们发现当代生态系统特征检索算法需要比历史任务更准确的光谱校准。由于之前被认为可接受的波长校准中的漂移或空间不均匀性导致的误差可能导致大于仪器噪声的系统误差，并且与 SBG 旨在测量的可变性具有相同的数量级。此外，它们对大气校正的影响会导致依赖于气候的系统误差，从而阻碍生态系统之间的比较。这些结果强调了光谱响应精度在 SBG 任务设计中的重要性。