The Total Irradiance Monitor (TIM) instrument is designed to measure total solar irradiance with an absolute accuracy of 100 parts per million. Four electrical substitution radiometers behind precision apertures measure input radiant power while providing redundancy. Duty cycling the use of the radiometers tracks degradation of the nickel-phosphorous absorptive black radiometer interiors caused by solar exposure. Phase sensitive detection at the shutter frequency reduces noise and simplifies the estimate of the radiometer's equivalence ratio. An as-designed uncertainty budget estimates the instrument's accuracy goal. The TIM measurement equation defines the conversion from measured signal to solar irradiance.
KeywordsMeasured Signal Radiant Power Equivalence Ratio Solar Irradiance Measurement Equation
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- Foukal, P.: 2003, EOS Trans. AGU 84, 22, 205.Google Scholar
- Kopp, G., Heuerman, K., and Lawrence, G.: 2005, Solar Phys., this volume.Google Scholar
- Pang, K. D. and Yau, K. K.: 2002, EOS Trans. AGU 83, 43, 489.Google Scholar
- Rice, J. P., Lorentz, S. R., and Jung, T. M.: 1999, in: 10th Conference on Atmospheric Radiation, 28 June–2 July, Madison, Wisconsin (Preprint volume).Google Scholar