Rrs results of TM5 are broken and discrete

[zoelu]

Hi,

I try to do the atmospheric correction of TM5 by the help of ACOLITE. But I can only get the broken and discrete Rrs results.
What can I do to get unbroken and continuous results?
The configurations and result are:


Thanks

zoelu

[quinten]

Hi zoelu

This is caused by the noise in the TM SWIR bands.

You could smooth the SWIR bands (Advanced Settings > Resampling), increase (e.g. set to 1) the masking threshold (Advanced Settings > Masking), and afterwards perform your own masking of land and clouds. In the next version of ACOLITE there will be support to fix both the aerosol type and reflectance from the subscene.

Alternatively, with this version you could output rhos_vnir, which will use the median SWIR reflectance as aerosol reflectance for the subscene. Note that you'll need to divide the rhos outputs by pi to get Rrs.

Quinten

[quinten]

Hi zoelu

In the current version of ACOLITE (20170619.0), you could use an alternative processing:
- increase the SWIR masking threshold, e.g. to 0.035 (Advanced settings > Masking, set 'Threshold' to 0.035)
- use a fixed aerosol reflectance spectrum, e.g. 5th percentile (Advanced settings > Aerosol, check 'Use fixed aerosol reflectance' and set percentile to 5)

Quinten