Convert Arc Grid file format to Arc ASCII Grid format
From CCoWS Wiki
Tarsier can't import native Arc Grid files. But it can import Arc ASCII Grid files (ASC) that have been exported from Arc format using ArcGIS.
- Open ArcMap
- Add Data - your Arc Grid raster
- Open ArcToolbox
- Select Conversion Tools --> From Raster --> Raster to ASCII --> Select output file as something like "myraster.asc"