Cloud mask issue with Sentinel 2 data

Please enter here to ask a question about any NASA Science related topics!
Post Reply
armin.mehrabian
Posts: 8
Joined: Tue Feb 25, 2020 10:44 am America/New_York

Cloud mask issue with Sentinel 2 data

by armin.mehrabian » Tue Feb 25, 2020 11:50 am America/New_York

Hi All,

I'm processing Sentinel2 scenes through l2gen to generate L2 products. I've been trying to figure a good cloud_thresh value for the task. However, it seems that changing the cloud_thresh value for some reason doesn't work. Here are some examples of the same scene processed with different cloud_thresh values, but visually they all look the same. Any idea what's happening here?

cloud_thresh=0.010
https://drive.google.com/file/d/1XzcQxmVPIAFXwfzSoKdMTmP_-i2LKlSG/view?usp=sharing
cloud_thresh=0.020
https://drive.google.com/file/d/197EokfFLz9iH7-wwY4npunq_LlsdAMHY/view?usp=sharing

Here is the par file I use
for S2A scenes
land=$OCSSWROOT/share/common/landmask_null.dat
l2prod=Rrs_443,Rrs_492,Rrs_560,Rrs_665,Rrs_704,Rrs_740,Rrs_783,Rrs_835,Rrs_865,Rrs_945,Rrs_1613,Rrs_2200,chlor_a,l2_flags
gain=[0.9841,0.988,1.0079,1.0084,1.0091,1.0201,0.9801,1,1,1,1,1]
aer_opt = -2
aer_wave_short=865
aer_wave_long=1613
filter_opt=1
filter_file=./msl12_filter.dat
maskcloud = 1
cloud_thresh=0.010
cloud_wave=2200
maskcloud=0
nlwmin=0.15
rhoamin=0.0005
maskstlight = 1
maskland=1
outband_opt=0
maskhilt=0
masksunzen=0
oformat=nc


S2b scenes:

land=$OCSSWROOT/share/common/landmask_null.dat
l2prod=Rrs_442,Rrs_492,Rrs_559,Rrs_665,Rrs_704,Rrs_739,Rrs_780,Rrs_835,Rrs_864,Rrs_943,Rrs_1611,Rrs_2184,chlor_a,l2_flags
aer_opt = -2
aer_wave_short=864
aer_wave_long=1611
filter_opt=1
filter_file=./msl12_filter.dat
maskcloud = 1
cloud_thresh=0.010
cloud_wave=2184
maskcloud=0
nlwmin=0.15
rhoamin=0.0005
maskstlight = 1
maskland=1
outband_opt=0
maskhilt=0
masksunzen=0
oformat=nc

Tags:

OB.DAAC - SeanBailey
User Services
User Services
Posts: 1192
Joined: Wed Sep 18, 2019 6:15 pm America/New_York

Cloud mask issue with Sentinel 2 data

by OB.DAAC - SeanBailey » Tue Feb 25, 2020 12:57 pm America/New_York

Output the cloud_albedo product (the product to which the threshold test is applied) to help you determine an appropriate threshold value.
With this product, you could also generate a cloud mask after processing to L2...

Sean

armin.mehrabian
Posts: 8
Joined: Tue Feb 25, 2020 10:44 am America/New_York

Cloud mask issue with Sentinel 2 data

by armin.mehrabian » Wed Feb 26, 2020 11:41 am America/New_York

Thanks Sean. I'll try to generate the cloud mask using cloud_albedo.

Post Reply