1. MODIS Aqua SDSM Gerhard Meister, presentation to CalVal, 2006

2. MODIS SDSM SDSM (Solar Diffuser Stability Monitor) views SD, sun, and background SDSM sun screen installed at wrong angle 9 Detectors, from 412nm to 936 nm h 9 detectors from 412nm to 936nm

3. VIIRS SDSM

4. Scan Directions SDSMsun screen: theory MODIS screen misalignment confirmed by MCST modeling for yaw maneuvers, but not for regular calibrations

5. MODIS SDSM: measured SD/sun ratios for detector 9 (936nm) Slope: -0.2%

6. Effect of reducing number of data points on linear fit to detector 9 data:

7. MCST method: divide detectors by detector 9

8. Divide detector 7 (857nm) by detector 9 No

9. Divide detector 1 (412nm) by detector 9

10. Epsilon trend: divide detector 6 (747nm) by detector 7 (857nm) MCST modeled slope of the ratio: -0.45% My estimate: -0.3 to -0.5%

11. Conclusions No evidence that assumption ‘SD is stable at 936nm’ is wrong, data is too noisy Independent of the above assumption, the SD reflectance ratio of 748nm to 870nm is modeled well by MCST (to within 0.1%) SD degradation may be slower than model prediction (0.2% at 412nm) (expected from modified calibration schedule, but this explanation not well supported by data)