Customize SMAP_L3_FT_P data structure

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zdenekruzicka
Posts: 2
Joined: Wed Apr 07, 2021 2:08 am America/New_York

Customize SMAP_L3_FT_P data structure

by zdenekruzicka » Wed Apr 07, 2021 2:15 am America/New_York

Hi All,

I am working on automated processing of SMAP Freeze/Thaw data (SMAP_L3_FT_P or SPL3FTP). According to the documentation of "Data element arrays are three dimensional, with the exception of transition_direction and transition_state_flag arrays, which are two dimensional. Arrays in the Polar group have dimensions of 500 rows and 500 columns in each a.m. and p.m. layer; the Global group array dimensions are 406 rows x 964 columns. For the a.m./p.m. index of the array, the a.m. layer is assigned to the index value 0 and the p.m. layer is assigned to index value 1."

If I download original file from NSIDC the structure is exactly as written in the documentation. But when I download data using Earth Data server, selected Customize as data access method and use spatial subsetting, the file structure differ. All elements are two dimensional and with suffix ".Bands_01". At least I don't know what Band01 means. It means, that it is AM data? Or PM data? And where is the rest? It is possible to get SPL3FTP/SPL3FTP_E data with the structure same as in original files? Or how to find out which data stand for AM and which for PM?

I am not sure, but early (maybe an year ago) the structure was the same as in documentation or in original files. At least according to my old scripts that processed the SMAP freeze/thaw data.

Have a nice day,
regards,
Zdenek

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zdenekruzicka
Posts: 2
Joined: Wed Apr 07, 2021 2:08 am America/New_York

Re: Customize SMAP_L3_FT_P data structure

by zdenekruzicka » Thu Apr 08, 2021 1:06 am America/New_York

Answer from NSIDC DAAC:

"Unfortunately, there is a bug in Earthdata that only returns Band 1. Thus, you can only view the AM data. The bug is currently in the Earthdata Search backlog and will be fixed in the coming months. The only other tool where you can perform spatial subsetting on SPL3FTP is the Application for Extracting and Exploring Analysis Ready Samples (AppEEARS). The only format options are NetCDF-4 and GeoTIFF, however. To learn more about AppEEARS, please visit https://lpdaacsvc.cr.usgs.gov/appeears/.

I apologize for the inconvenience, but I will make the Earthdata team aware of your issue in case it increases the priority of the bug."

Regards,
Zdenek

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