WRFV300 update: two items

(1) In WRFV300 on the Mac, using the Intel Fortran 10.1 compiler, the compiler flag –switch fe_use_rtl_copy_arg_inout causes problems that weren't apparent with earlier WRF versions. Specifically, lateral boundary tendencies for water vapor are zeroed, resulting in problems in this field that grow inward from the boundaries. In the wrfbdy_d01 file, fields like QVAPOR_BXE and related entries possess only zeroes. This file is, of course, created by real.exe.

I added this switch owing to this page. Removing it does no harm. I tried several minor versions of ifort 10.1, explored 32 and 64 bit, etc.; nothing helped fix this issue except removing this switch.

(2) In WRFV300, the Lin microphysics scheme (mp_physics = 2) has issues -- noise issues. After only a few tens of minutes, the pressure field starts displaying small scale noise. Decreasing the time step, implementing 6th order smoothing, and upping the small time step smoothing (epssm) do not help. For the simulations I am examining, the noise does not appear with any other microphysics scheme. With Lin, the noise appears in higher but not in lower resolution simulations.

The Lin code was altered between WRFV221 and WRV300. I have not isolated the code changes that cause this problem.

WRFV22 on a dual quad-core Intel Mac

Here are some notes on a recent attempt to run WRF on a dual quad-core Intel Mac, which I received as a loaner from Apple. In the two weeks I had the machine, I made progress, but it's clear from my notes below I didn't pass the finish line. For one thing, I was unable to get even medium-sized jobs to run in the 64 bit environment -- and the tricks for accessing memory that worked with 32 bits fail. In 32 bit land, there is still a limit on the job size, which is apparently due to Apple's internal memory allocation restrictions.

Executive summary: I was able to get all 8 cpus working for me, tho the scaling wasn't the best, and the key turned out to be: (a) moving to mpich-2; AND (b) using --with-comm=shared. An important goal for me is getting results that do not vary with the number of processors used. With OMP, that required the ifort flag '-fp-model precise'. I also used this flag in the WRF code and when compiling mpich-2.

** These notes assume the 32 bit ifort compiler. I used ifort 10.0.017. These notes presume WRF model changes documented on previous posts. Compilation and execution took place on an HFSX-formatted disk.

(1) netcdf-3.6.2

export CC=/usr/bin/gcc
export CPPFLAGS="-O -DNDEBUG -DpgiFortran"
export CFLAGS="-O"
export CXX=/usr/bin/c++
export CXXFLAGS="-O"

export FC=ifort
export F77=ifort
export F90=ifort
export FFLAGS="-O3"
export F90FLAGS=


./configure --prefix=/usr/local/netcdf
make
make test
make check
sudo mkdir /usr/local/netcdf
sudo make install

(2) MPICH-2 (mpich2-1.0.5p4)

setenv FC ifort
setenv F90 ifort
setenv CC "gcc"
setenv RSHCOMMAND "/usr/bin/ssh"
setenv CXX "/usr/bin/c++"
setenv FFLAGS "-xP -vec- -fp-model precise"
setenv F90FLAGS "-xP -vec- -fp-model precise"
./configure --with-comm=shared
make

(3) Modify external/RSL_LITE/buf_for_proc.c to add "extern" before "char mess" (resolves a problem that crops up specifically with mpich-2)

(4) configure.wrf files I used for these tests: APPLE_LOANER_WRF.zip.