added exception for ncgen to use system default if it exists

mvcm/c_tools/include/ancillary.h

@@ -21,6 +21,7 @@ float *g_phis;
 float *g_tpw1;
 float *g_tpw2;
 float *g_lst;
+float *g_sst;
 float *ti_sfct;
 float *ti_tpw;
 int nwp_rows;
@@ -30,6 +31,7 @@ long int nwp_cells;
 // Ancillary data for entire granule.
 struct granule_ancillary {
   float *reynSST;
+  float *geos_sst;
   float *ndvibk;
   unsigned char *eco;
   float *sfct;

mvcm/write_output.py

 """Write the output data in a netcdf file."""
 
 import logging
-from os.path import basename
+from os.path import basename, isfile
 from subprocess import run
 
 import numpy as np
@@ -364,7 +364,16 @@ def run_mvcm(
     ndvi_fname = file_names["NDVI"]
     anc_dir = file_names["ANC_DIR"]
 
-    cmd_ncgen = [f"{exe_path}/ncgen", "-b", f"{exe_path}/mvcm_snpp_viirs.cdl", "-o", f"{out_file}"]
+    if isfile("/opt/netcdf4/4.8.1-gcc-11.2/bin/ncgen"):
+        cmd_ncgen = ["ncgen", "-b", f"{exe_path}/mvcm_snpp_viirs.cdl", "-o", f"{out_file}"]
+    else:
+        cmd_ncgen = [
+            f"{exe_path}/ncgen",
+            "-b",
+            f"{exe_path}/mvcm_snpp_viirs.cdl",
+            "-o",
+            f"{out_file}",
+        ]
     cmd_mvcm = [
         f"{mvcm_exe}",
         "-sat",