Avoid asking the user in which directory they are in

If this feature is needed it's probably best to support overriding this
with environment variables yet from the looks of it that is not actually
needed.

This script can perhaps be refactored a bit overall too.

model/bin/ww3_from_ftp.sh

@@ -6,16 +6,9 @@
 # --------------------------------------------------------------------------- #
 
 curr_dir=`pwd`
-
-#Get top level directory of ww3 from user: 
-echo -e "\n\n This script will download data from the ftp for WAVEWATCH III "
-echo -e "Enter the relative path to the main/top level directory, this would "
-echo -e "be '../../' if in the model/bin directory or '.' if already in the "
-echo -e "top/main directory:"
-read ww3dir 
-
-#Move to top level directory of ww3: 
-cd $ww3dir 
+ww3dir="$(cd "$(dirname "$0")";pwd -P)/../.."
+#Move to top level directory of ww3:
+cd $ww3dir
 
 #Download from ftp and uptar: 
 echo -e "Downloading and untaring file from ftp:" 
@@ -64,6 +57,6 @@ else
   echo -e ' Not deleting the data_regtests folder.' 
 fi
 
-#move back to original directory: 
+#move back to original directory:
 cd $curr_dir
 echo -e "End of ww3_from_ftp.sh"