diff --git a/climax/core/constants.py b/climax/core/constants.py
index fad37510719beef7ae275aecafa386d4f653041b..daa533b549b61e5a7cbbc5ab848940c2ed4a047b 100644
--- a/climax/core/constants.py
+++ b/climax/core/constants.py
@@ -3,6 +3,12 @@
 # !/usr/bin/env python
 # -*- coding: utf-8 -*-
 
+# Cordex variables
+CORDEX_VARIABLES = ['tas', 'tasmin', 'tasmax', 'pr']
+
 # parameters defining a Cordex climate simulation
 CORDEX_PARAMETERS = ['Variable', 'Domain', 'Gcm', 'Scenario', 'Ensemble',
                      'Rcm', 'Version', 'Frequency', 'Years']
+
+# climate data operator (cdo) resampling modes
+CDO_RESAMPLING_MODES = ['bilinear', 'conservative']