Add diffed channels normalisation consts for ECMWF India (#360)

Author: Sukh-P

ocf_datapipes/utils/consts.py

@@ -250,6 +250,10 @@ def __getitem__(self, key):
     "v10": 0.02332865633070469,
     "v100": -0.07577426731586456,
     "v200": -0.1255049854516983,
+    "diff_dlwrf": 1340142.4,
+    "diff_dswrf": 820569.5,
+    "diff_duvrs": 94480.24,
+    "diff_sr": 814910.1,
 }
 
 INDIA_ECMWF_STD = {
@@ -270,6 +274,10 @@ def __getitem__(self, key):
     "v10": 2.401158571243286,
     "v100": 3.5278923511505127,
     "v200": 3.974159002304077,
+    "diff_dlwrf": 292804.8,
+    "diff_dswrf": 1082344.9,
+    "diff_duvrs": 125904.18,
+    "diff_sr": 1088536.2,
 }