[GRASS-user] CHELSA climate data set

[Markus Metz]

On Tue, Sep 6, 2016 at 10:36 AM, Helmut Kudrnovsky <hellik at web.de> wrote:
> Hi Vero,
>
>
> Veronica Andreo wrote
>> Hi Helmut,
>>
>> I saw the announcement for this data set some time ago. I'm downloading
>> now, just to give it a look. But, AFAIU, they are climatologies the same
>> as
>> worldclim. The remark is that they cover a more recent period than
>> worldclim (1973-2013 compared to 1950-2000). But I know nothing about the
>> quality of this data. Also worldclim developed a newer dataset that is
>> still in beta (http://worldclim.org/version2)... Maybe worth comparison :)
>>
>> In any case, if they are just climatologies (averages over the years), I
>> do
>> not see much that you could do with tgrass that you couldn't do with the
>> other modules (and I'm fan of tgrass!). You could however obtain the
>> bio-climatic variables yourself with Markus Metz's add-on r.bioclim (
>> https://grass.osgeo.org/grass70/manuals/addons/r.bioclim.html) that works
>> pretty nice.
>>
>> Cheers,
>> Vero
>>
>>
>> 2016-09-05 20:34 GMT+02:00 Helmut Kudrnovsky <
>
>> hellik@
>
>> >:
>>
>>> hi community,
>>>
>>> there is an interesting new climate data set called
>>>
>>> CHELSA – Climatologies at high resolution for the earth’s land surface
>>> areas
>>> [1]
>>>
>>> CHELSA is a high resolution (30 arc sec) climate data set for the earth
>>> land
>>> surface areas
>>>
>>> has anyone already tried to use it within GRASS and maybe with the
>>> temporal
>>> GRASS suite?
>>>
>>> [1] http://chelsa-climate.org/
>>>
>>>
>>>
>>> -----
>>> best regards
>>> Helmut
>>> --
>>> View this message in context: http://osgeo-org.1560.x6.
>>> nabble.com/CHELSA-climate-data-set-tp5284115.html
>
> Thanks for the feedback.
>
> I've there is some raster extent issue with this data; already reported to
> the data provider.

According to gdalinfo, the pixel sizes are
Pixel Size = (0.008333333300000,-0.008333333300000)
should be
Pixel Size = (0.008333333333333,-0.008333333333333)
i.e. fp precision is too low which explains why west is not exactly on
-180 but -180.0001389, just as south is not exactly -90 but
-90.0001389.

There are 43207 columns, but with 30 seconds there should be 43200
columns meaning that there are 7 excess columns to the east.
Considering that the 7 westernmost columns and the 7 easternmost
columns overlap, their values should be identical.

There are 21599 rows, but with 30 seconds covering -90, 90 there
should be 21600 rows. The northernmost row is missing and north should
be 89:59:30. The data would need to be prepared with gdal_translate,
cutting off the 7 excess columns to the east and fixing the extents,
before they can be imported into GRASS.

It seems it is easier to stick to worldclim...

Markus M