GEDI L1B 'Stale Returm Flag' parameter values

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meiyuanchen
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GEDI L1B 'Stale Returm Flag' parameter values

by meiyuanchen » Mon Nov 07, 2022 5:20 am America/New_York

Hello!I want to ask some questions about the parameter 'Stale Returm Flag' in GEDI L1B data and GEDI L2A data.In the GEDI L1B filter process of the ''Getting Started with GEDI L1B Data in Python'',The filter criterion is to keep the values where the parameter 'Stale Returm Flag' is not equal to 0('ne(0)').but in GEDI L2A data,'Quality Flag==1' means that the parameter 'Stale Returm Flag' is equal to 0.Are the two contradictory?Which one is right? Which criteria are the criteria for filtering the data?And is the tutorial of GEDIL1B in python wrong? Take a look at some of the tutorials below:
(1)"Below, remove any shots where the stale_return_flag is set to 1 (indicates that a "stale" cue point from the coarse search algorithm is being used) by defining those shots as nan."
(2)"The syntax of the line below can be read as: in the dataframe, find the rows "where" the stale return flag is not equal (ne) to 0. If a row (shot) does not meet the condition, set all values equal to nan for that row."
(3)"latlons = latlons.where(latlons['Stale Return Flag'].ne(1)) # Set any stale returns to NaN"
'Stale Returm Flag':ne(0) or ne(1) or ''stale return flag == 1'' means ''quality flag'' ==1 which means data quality is good

Thanks,
Maye

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LP DAAC - dgolon
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Re: GEDI L1B 'Stale Returm Flag' parameter values

by LP DAAC - dgolon » Tue Nov 08, 2022 9:17 am America/New_York

Hi @meiyuanchen We will talk to our GEDI experts and get back to you. Thanks!
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Re: GEDI L1B 'Stale Returm Flag' parameter values

by LP DAAC - dgolon » Tue Dec 13, 2022 11:09 am America/New_York

Hi @meiyuanchen Thank you for your feedback. The repo has been updated to make the quality filtering section more clear. https://git.earthdata.nasa.gov/projects/LPDUR/repos/gedi-v2-tutorials/browse?at=refs%2Fheads%2Fquality-update

We updated "The syntax ... "where" the stale return flag is not equal (ne) to 1. If...". We also made some changes to the Quality section to hopefully make it more clear to understand.
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