Beginning with version 3.7 of the WRF code, you can build with double precision by simply typing
./configure -r8
then follow the normal steps to build WRF. For versions prior to V3.7, you will need to run the configuration, and then go into the 'configure.wrf' file and manually change the following lines below to:
RWORDSIZE = 8
PROMOTION = -real-size `expr 8 \* $(RWORDSIZE)` -i4
Then save the configure.wrf file, and compile WRF.
./configure -r8
then follow the normal steps to build WRF. For versions prior to V3.7, you will need to run the configuration, and then go into the 'configure.wrf' file and manually change the following lines below to:
RWORDSIZE = 8
PROMOTION = -real-size `expr 8 \* $(RWORDSIZE)` -i4
Then save the configure.wrf file, and compile WRF.