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The Second-generation global imager (SGLI) empowers surface and atmospheric measurements related to the carbon cycle and radiation budget, with two radiometers of Visible and Near Infrared Radiometer (VNR) and Infrared Scanning Radiometer (IRS) which perform a wide-band (380 nm - 12 μm) optical observation not only with as wide as 1150-1400 km FOV but also with as high as 250 - 500 m resolution. Also, polarization and along-track slant view observation are quite characteristic of SGLI. SGLI provides the earth observing data for more than 28 standard products and 23 research products including clouds, aerosols, ocean color, vegetation, snow and ice, and other applications. SGLI-VNR has several on-board calibration methods, such as solar, LED and lunar calibration. In this paper, methodologies and results of solar and LED calibration of SGLI-VNR Non-Polarization (NP) telescopes with a deployable diffuser to illuminate the uniformly scattered solar and LED light to telescope and photo diode stability monitor (PD) are provided, respectively. In addition, inter-comparison of the solar and the LED calibration is conducted with NP-Nadir telescope, PD2 and PD4. The calibration area of the telescope and the PDs are less affected by the UV degradation, so that the PD2 and the PD4, as an independent calibrator, can correct the solar diffuser reflectance degradation for the NP-Nadir telescope. As a result, each trend of the solar and the LED calibration of the NP-Nadir’s VN5, 10, and 11 bands agrees 1% or less. It concludes that the response change in the NIR spectral regions (VN10 and 11 with wavelength of 868.5 nm) is stable and that in the shorter wavelength band (VN5 with wavelength of 530 nm) is less than 2 % over a year. Lessons learned of on-board calibrations are also stated for the next generation's global imager.
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