Compiling.md

+Because this simulation setup uses a 
+## RTTOV
+```bash
+export LC_ALL="en_US.UTF-8"
+
+#### These steps are only necessary when using haralds libraries
+module purge
+module use /sw/intel/oneapi/compiler/2021.3.0/modulefiles /sw/intel/oneapi/tbb/2021.3.0/modulefiles /sw/intel/oneapi/mkl/2021.3.0/modulefiles
+module load compiler mkl
+module load compiler-rt
+####
+```
+select `levante-icon` in the next step when asked `Specify required compiler flag file (leave blank for default: gfortran)`
+Answer the next steps with y or leave empty. The compilation summary should look like this:
+```
+===========================
+ RTTOV COMPILATION SUMMARY 
+===========================
+
+Compiling with flags           : levante-icon
+Compiling in directory         : ./
+
+RTTOV features available:
+HDF5 coefficient I/O           : y
+Emissivity/BRDF atlases        : y
+C/C++ wrapper                  : y
+Python wrapper                 : n
+RTTOV GUI                      : n
+HTFRTC netCDF files            : y
+
+Compiling with user LAPACK lib : n
+
+Regenerating Makefiles using:
+$ ../build/Makefile.PL RTTOV_HDF=1 RTTOV_F2PY=0 RTTOV_USER_LAPACK=0
+
+Compiling RTTOV using:
+$ make ARCH=levante-icon INSTALLDIR=./ clean 
+$ make ARCH=levante-icon INSTALLDIR=./
+```
+
+## ICON
\ No newline at end of file