OZONE MAPPER PROFILER SUITE EARLY ORBIT LINEARITY PERFORMANCE EVALUATION

摘要

The linearity of the Ozone Mapping and Profiler Suite Nadir instruments' radiometric response is characterized using two onboard LED calibrators with a series of lamp exposures of various times and therefore varying count levels. It is specified that the non-linearity of the nadir sensors shall be no more than 2% of full well, the linear degradation rate of the LED output shall be less than 1% per minute, and the high-frequency LED current variability shall be less than 0.1% RMS. During the on-orbit characterization, we monitor the lamp signal drifts, temperature dependency and nonlinearity sensitivity. The lamp signal variations are compensated prior to the calculation of the sensors' linear calibration coefficients. The calibration coefficients are derived by interpolating between measured count levels and ideal linearized count levels. System nonlinearity is estimated by fitting normalized signal count rates to a second order polynomial function. Additionally, sensor on-orbit dynamic range is verified and thermal impact on nonlinearity sensitivity is analyzed. Our results demonstrate that sensor linearity performance meets the system requirement.