[GRASS-user] TRMM (3B43) handling

[Markus Metz]

nikos wrote:
> hey list,
>
> Sorry that I took so much to respond,
>
> I'm orientating in a different direction right now, and I'd like an
> opinion (on TRMM 3B43 ofc).
>
Another option:
get binary grids from here
ftp://disc2.nascom.nasa.gov/data/TRMM/Gridded/3B43_V6/
read
ftp://disc2.nascom.nasa.gov/data/TRMM/Gridded/3B43_V6/3B43.ctl

import into a latlon location with r.in.bin -f -b north=50 south=-50
east=180 west=-180 rows=400 cols=1440, e.g.
r.in.bin -f -b input=3B43.100101.6.precipitation.bin
output=3B43.100101.6.precipitation north=50 south=-50 east=180
west=-180 rows=400 cols=1440

optionally convert mm/hr to some other time unit

This can be easily scripted to automatically get and process the
complete TRMM 3B43_V6 dataset.

my0.2c

Markus M


> Here are my thoughts:
>
> a) the hdf that delivers the product only wraps a table 1400 long x 440
> tall. Each tile is represented by known cords. eg the upper left tile
> ( [0][0] ) have the coords of -180deg, 50deg. This is a fact. And also
> it is a fact the dArc from each tile to another tile (horizontally and
> vertically) its 0.25arcs.
> b) So we can controllably somehow "dump" the data into a csv of x,y z
> where z are mm/hr (3b43 specification). x,y in a φ,λ coordinate system
> (reprojections and projections are not my strong point).
>
>   results are 1440 x 400 points with known known coords and values.
>
> c)  interpolate for the area you're interested for.
>
> d) You got yourself a raster to have fun with.
>
> Taken into account the reprojection from φ,λ is possible and a viable
> solution, the hard part seems to be getting the data. Here's my solution
> on that: Giovanni Interface so kindly provided by nasa.gov . You get the
> data in ascii format for the area you're researching for and free to
> work with htem.
>
> Here's an example on data dump:
>
> http://disc2.nascom.nasa.gov/daac-bin/Giovanni/tovas/Giovanni_cgi.pl?west=16.0&north=43.0&east=30.0&south=31.0&params=1|3B43_V6&plot_type=Area+Plot&byr=2006&bmo=05&eyr=2006&emo=05&begin_date=1998/01&end_date=2010/10&cbar=cdyn&cmin=&cmax=&yaxis=ydyn&ymin=&ymax=&yint=&ascres=0.25x0.25&global_cfg=tovas.global.cfg.pl&instance_id=TRMM_V6&prod_id=3B43&action=ASCII+Output
>
>
> My thoughts are that a python script that utilities the above method is
> possible.
>
> Any thoughts on my comments would be really appreciated.
>
>
> Best Regards,
> Nick Ves
>
>
>
> On Mon, 2010-11-15 at 11:03 +0100, Markus Metz wrote:
>> On Sun, Nov 14, 2010 at 8:41 PM, Markus Neteler <neteler at osgeo.org> wrote:
>> > On Sun, Nov 14, 2010 at 7:42 PM, nikos <vesnikos at gmail.com> wrote:
>> >> On Sun, 2010-11-14 at 16:35 +0100, Markus Neteler wrote:
>> >>> On Sun, Nov 14, 2010 at 4:01 PM, nikos <vesnikos at gmail.com> wrote:
>> >>> >
>> >>> >
>> >>> > I'm battling to import the 43b3 Product (TRMM perspiration + other
>> >>>
>> >>> (http://disc.sci.gsfc.nasa.gov/precipitation/documentation/TRMM_README/TRMM_3B42_readme.shtml)
>>
>> You could also use the TRMM tools [1] to dump the data to a raw binary
>> file. Last time I did that I noted that the binary file is rotated by
>> 90°, i.e. north is right and west is up (or north is left and west is
>> down, forgot the rotation direction).
>>
>> >>
>> >> I tried
>> >>
>> >> ./gdal_translate -a_ullr  -180 50 -50 180
>> >> HDF4_SDS:UNKNOWN:"/DIR/OF/TRMM_IMAGE/3B43.060801.6.HDF":1 test.tif
>> >>
>> >> which makes an interesting tif, that is not empty, but when I load it
>> >> with qgis (use psedocolor) its square(?). The image should have a
>> >> 1440/400 ratio.
>>
>> What does
>> gdalinfo HDF4_SDS:UNKNOWN:"/DIR/OF/TRMM_IMAGE/3B43.060801.6.HDF":1
>> say? There should be 400 rows and 1440 columns, and not vice versa,
>> 1440 rows and 400 columns (suspected 90° rotation mentioned above).
>>
>> >
>> > Wait - AFAIK you need to use "gdalwarp" on it, not gdal_translate.
>> >
>>
>> Hm, there is no coordinate system specified in the hdf, so gdalwarp
>> would only work with -s_srs wgs84 -t_srs <something else than wgs84>.
>> Or translate first, add gcps during translation, then warp?
>>
>> Markus M
>>
>> [1] ftp://disc2.nascom.nasa.gov/software/trmm_software/Read_HDF/READTRMM_V2.tar
>
>
>