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I have successfully created Diva-GIS CLM files from tiff climate data using the two approaches below

1) Geotiff file --> Ascii grid file --> GRD/GRI file --> CLM as explained by Julián Ramírez1 and Aaron Bueno-Cabrera(2009), Xavier Scheldeman and Maarten van Zonneveld (2010)

2) Geotiff file --> ASCii txt file --> GRD/GRI file --> CLM

After testing the first approach, I discovered that key information i.e. projection, map units and datum were all missing in both CLM and GRD files. When I tried running EcoCrop, I simply got a blank (grey) map with value = 0 on all the continents, though I could see variations on my map legend. May I also say that no data values in climate data were all set to -9999 by default

in the second approach, a WGS 84 coordinate reference system was assigned to ASCII txt file while importing into Idrisi software. As such all GRD and GRI files later created in Diva-GIS were projected (GEOGRAPHIC), had map units (degree) and a datum(WGS 84). However, CLM files only had projection but lacked map unit and datum. And again EcoCrop model simply produced a black map and showing variability in my map legend.

A major challenge for me is how to get a projection, a datum and map units on my CLM files.

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2 Answers 2

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I tried the following steps and it worked for me. (1) beginning with a .tif raster (2) multiply the raster by 10
NB. step 2 is optional but necessary if average raster values have to be calculated e.g from multiple climate models (3) convert the .tif raster to a .bil rater (4) import the .bil rater into diva-GIS to create the .grd raters Form step 4, follow the approach of Xavier Scheldeman and Maarten van Zonneveld (2010) to create the CLM files.

It worked for me and I didn't have to worry and the missing projection. For reasons unknown to me, in the process of converting from one raster format to another following the approach of Xavier Scheldeman and Maarten van Zonneveld (2010), data type and projection change.

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As much of the GIS community seem to have issues creating CLM files, I've created a R package which helps prepare the data for use in DIVA GIS.

Instructions available on the prepCLMdata GitHub page

Sorry if it's come too late for yourself but hope it helps those who next have issues with this!

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