Case study for MODIS Aqua striping

1) R2009.1 shows striping in nLw488 at the end of scan for the end of the mission. Can this be confirmed looking at TOA radiances ?
2) There is currently (April 2011) no global evaluation of the striping in ocean color products of bands 1-4. How large is the problem ?

1) Yes, the TOA radiances of mirror side 2 are about 0.2% too high.
2) For bands 3 and 4 (469nm and 555nm), the striping is similar as in the standard ocean bands (e.g. 531nm). Striping in band 1 (645nm) is higher than in bands 13 and 14 (667nm and 678nm).
This analysis should be repeated on other granules to confirm the results.
A granule was chosen that has large contiguous (i.e. cloud free) ocean areas beyond frame 900 from the end of 2010. This was not easy to find. Chosen granule is shown below.

In a first step, only pixels beyond frame 900 with a valid chlorophyll retrieval were chosen. Then the median value of those pixels for each detector and mirror side was calculated for 3 quantities using SeaDAS: TOA radiances (Lt), Rayleigh radiances (Lr), and water-leaving radiances (Lw). Note that the crosscalibration corrections are applied to Lw, but not to Lw in the plots below. For all bands, 1km resolution was used. The results are shown below. The dashed lines show +/-0.1% around the mean for Lt and Lr, +/- 1% for Lw. The two stars show the mean for the first and second mirror side, respectively. It can be seen that the stars are within the dashed lines for wavelengths from 443nm up to 555nm, except for 488nm, both for Lt and Lw.

The same analysis was repeated for frames below frame 900. The results are shown below. 488nm is not anomalous. Striping is improved for all bands.

All results (including NIR bands) are shown in the PDFs in this tar file.
For further information, please contact:
Gerhard Meister
Ocean Biology Processing Group, NASA/GSFC Code 614.2
Building 28, Room W119, Greenbelt, MD 20771 USA
Tel #: (301) 286 - 0758, FAX #: (301) 286 - 0268