Abstract. NOAA has both geostationary (GEO) and polar orbiting (LEO) satellites that are procured through different vendors. For long-term environmental studies, it is essential to establish consistent radiometric calibration among satellite instruments irrespective of the satellite platforms. The Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the Suomi National Polar-orbiting Partnership (S-NPP) and NOAA-20 satellites has been providing critical weather and climate-related data. With the launch of NOAA-20 in November 2017, the global coverage of VIIRS has doubled. With more than 7 years in space, S-NPP VIIRS has been rigorously calibrated and validated. We aim to quantify the radiometric consistency between the two VIIRS instruments through double differencing using GOES-16 Advanced Baseline Imager (ABI) as a reference instrument. We also provide insight into the temporal radiometric consistency between VIIRS and ABI. Since no direct simultaneous nadir overpasses (SNOs) exist between SNPP and NOAA-20 for intercomparison, GEO-LEO intercalibration is performed using SNOs between ABI and VIIRS instruments. We show that the NOAA-20 VIIRS measured top-of-atmosphere (TOA) reflectance is consistently lower than that of the S-NPP, mostly on the order of 2% to 3%, consistent with the past studies. GOES-16 ABI-observed reflectance is higher than both VIIRS instruments. SNOs over the all-sky tropical ocean are analyzed to quantify the bias for both NOAA-20 and S-NPP VIIRS relative to ABI. The impact on bias due to spectral differences is accounted for using spectral band adjustment factors estimated using hyperspectral measurements from SCIAMACHY. Uncertainties exist mainly due to calibration uncertainties in VIIRS and ABI, the time difference between the VIIRS and ABI observations, differences in cloud contamination, spectral response function differences, and lack of in-situ hyperspectral data to account for the spectral bias.

中文翻译：

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GOES-16 ABI 和 VIIRS 在 Suomi NPP 和 NOAA-20 上的辐射一致性

摘要。NOAA 拥有通过不同供应商采购的地球静止 (GEO) 和极地轨道 (LEO) 卫星。对于长期环境研究，无论卫星平台如何，都必须在卫星仪器之间建立一致的辐射校准。Suomi 国家极地轨道合作伙伴 (S-NPP) 和 NOAA-20 卫星上的可见红外成像辐射计套件 (VIIRS) 一直在提供与天气和气候相关的关键数据。随着 2017 年 11 月 NOAA-20 的推出，VIIRS 的全球覆盖范围翻了一番。S-NPP VIIRS 在太空中使用了 7 年多，经过了严格的校准和验证。我们的目标是使用 GOES-16 高级基线成像仪 (ABI) 作为参考仪器，通过双重差分来量化两个 VIIRS 仪器之间的辐射一致性。我们还深入了解 VIIRS 和 ABI 之间的时间辐射一致性。由于 SNPP 和 NOAA-20 之间不存在用于比对的直接同时天底立交桥 (SNO)，因此使用 ABI 和 VIIRS 仪器之间的 SNO 执行 GEO-LEO 相互校准。我们表明，NOAA-20 VIIRS 测量的大气顶 (TOA) 反射率始终低于 S-NPP，大部分在 2% 到 3% 的数量级，与过去的研究一致。GOES-16 ABI 观测反射率高于两种 VIIRS 仪器。分析了全天空热带海洋上的 SNO，以量化 NOAA-20 和 S-NPP VIIRS 相对于 ABI 的偏差。使用使用来自 SCIAMACHY 的高光谱测量估计的光谱带调整因子来解释光谱差异对偏差的影响。