This directory contains "ecrad_meridian.nc", a pole-to-pole slice of
low-resolution IFS model data in a form to use as input to the offline
version of ecRad. It includes aerosols extracted from the CAMS
climatology used operationally in IFS Cycle 43R3.

Up to ecRad version 1.1.6, the file included a modification for Earth
curvature effects within the IFS such that the online radiation scheme
never sees a solar zenith angle greater than 90 degrees. However, it
is important to test the offline ecRad for such conditions, so from
version 1.1.7, the cos_solar_zenith_angle variable has been modified
to allow the sun to go below the horizon.

Typing "make" in this directory runs various configurations of ECRAD -
see the Makefile for details.

To run with a configuration similar to older cycle 43R3, type

   make CONFIG=configCY43R3.nam

The Matlab script plot_ifs.m and Python script plot_ifs.py can be used
to visualize the results. The file
"ecrad_meridian_default_out_REFERENCE.nc" contains a reference version
of the output file "ecrad_meridian_default_out.nc" (case "a" above),
which you can compare to be sure your compilation is working as
expected. Sometimes this file lags intermediate versions of ecRad,
especially git snapshots. It is always generated using gfortran in
double precision.

Note that the shortwave diagnosed cloud cover will be set to -1 when
the sun is below the horizon.