How to convert TRMM rainfall data into .tif or other ArcGIS-readable formats?

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08-06-2015 05:03 AM
StefanieSteinbach
New Contributor III

Dear all,

I am currently working with various remotely-sensed data sets for East Africa and would also like to include TRMM precipitation data.

Not sure if it is just me or if it is actually that hard to find an easy way to convert the data (in TOVAS Giovanni - TRMM Online Visualization and Analysis System (TOVAS)​ downloadable as .hdf, .ascii or .ncd) into something ArcGIS can work with. What I need is one raster layer for every month from 2001 to 2014.

So, my question is, how do I proceed? Are there other visualizers where I find a .tif download option?

Any help will be greatly appreciated!

Stefanie

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GabrielUpchurch1
Occasional Contributor III

From what you have described, it seems this is multidimensional scientific data so you probably won't be able to obtain it as tiff files.  I didn't click on the link you provided but I am going to assume that if you choose the hdf option that you will get a single hdf file containing a band/subdataset for each monthly interval.  If this is the case, you can use the Extract Subdataset tool to extract each subdataset as a tiff.  With so many subdatasets to extract, you will need to use ModelBuilder or Python to iterate through the process.  I am not familiar with a .ncd file but there may be a way to get at the data you need by downloading the ascii file.  Without actually testing the process myself I can't say for sure but perhaps someone else has direct experience and can provide more detailed guidance.

EDIT:  I clicked the link.  It looks like you can get NetCDF so you can manipulate the data with the Multidimension Tools, specifically Make NetCDF Raster layer.  You will still need to devise a procedure to iterate through the NetCDF file and extract each time step to a tiff.  With this being the case, the HDF approach may prove to be the easier of the two.  The Extract Subdataset tool is easier to use.  I am still not sure on how you would work with the ascii file but maybe someone else can enlighten you on that.

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GabrielUpchurch1
Occasional Contributor III

From what you have described, it seems this is multidimensional scientific data so you probably won't be able to obtain it as tiff files.  I didn't click on the link you provided but I am going to assume that if you choose the hdf option that you will get a single hdf file containing a band/subdataset for each monthly interval.  If this is the case, you can use the Extract Subdataset tool to extract each subdataset as a tiff.  With so many subdatasets to extract, you will need to use ModelBuilder or Python to iterate through the process.  I am not familiar with a .ncd file but there may be a way to get at the data you need by downloading the ascii file.  Without actually testing the process myself I can't say for sure but perhaps someone else has direct experience and can provide more detailed guidance.

EDIT:  I clicked the link.  It looks like you can get NetCDF so you can manipulate the data with the Multidimension Tools, specifically Make NetCDF Raster layer.  You will still need to devise a procedure to iterate through the NetCDF file and extract each time step to a tiff.  With this being the case, the HDF approach may prove to be the easier of the two.  The Extract Subdataset tool is easier to use.  I am still not sure on how you would work with the ascii file but maybe someone else can enlighten you on that.

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StefanieSteinbach
New Contributor III

Hi Gabriel,

The NetCDF procedure did the job.

Although I was able to extract a tiff from the HDF, the size and projection just did not fit, no matter what I tried. With the Make NetCDF Raster Layer tool it worked perfectly. I'll put together a model for iteration now.

Thanks so much for your help, you just saved me from loads of hassle and frustration.

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deleted-user-AYsXjhkrwuAA
New Contributor III

NASA make TRMM available in pre-processed TIF with TFW files that may be useful for you?

They can be downloaded from ftp://trmmopen.gsfc.nasa.gov/pub/gis/ using an anonymous login, with documentation available - including a specific README for the re-formatted files.

StefanieSteinbach
New Contributor III

Hi Andrew,

Thanks for your input!

Maybe I missed something, but I didn't find monthly products on the ftp server - I should have mentioned that it's these I need. However, the above-mentioned solution seems to work well.

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