diff --git a/ocean/diag_table b/ocean/diag_table
index 50e82875..e279b7bb 100644
--- a/ocean/diag_table
+++ b/ocean/diag_table
@@ -379,56 +379,56 @@ ACCESS-OM2-01
 
 # monthly 3d prognostic BGC fields
 
-"oceanbgc-3d-adic-1-monthly-mean-y%4yr", 1, "months", 1, "days", "time", 1, "months"
-"ocean_model", "adic", "adic", "oceanbgc-3d-adic-1-monthly-mean-y%4yr", "all", "average", "none", 2
+"oceanbgc-3d-adic-1-monthly-mean-ym%4yr%2mo", 1, "months", 1, "days", "time", 1, "months"
+"ocean_model", "adic", "adic", "oceanbgc-3d-adic-1-monthly-mean-ym%4yr%2mo", "all", "average", "none", 2
 
-"oceanbgc-3d-alk-1-monthly-mean-y%4yr", 1, "months", 1, "days", "time", 1, "months"
-"ocean_model", "alk", "alk", "oceanbgc-3d-alk-1-monthly-mean-y%4yr", "all", "average", "none", 2
+"oceanbgc-3d-alk-1-monthly-mean-ym%4yr%2mo", 1, "months", 1, "days", "time", 1, "months"
+"ocean_model", "alk", "alk", "oceanbgc-3d-alk-1-monthly-mean-ym%4yr%2mo", "all", "average", "none", 2
 
-"oceanbgc-3d-caco3-1-monthly-mean-y%4yr", 1, "months", 1, "days", "time", 1, "months"
-"ocean_model", "caco3", "caco3", "oceanbgc-3d-caco3-1-monthly-mean-y%4yr", "all", "average", "none", 2
+"oceanbgc-3d-caco3-1-monthly-mean-ym%4yr%2mo", 1, "months", 1, "days", "time", 1, "months"
+"ocean_model", "caco3", "caco3", "oceanbgc-3d-caco3-1-monthly-mean-ym%4yr%2mo", "all", "average", "none", 2
 
-"oceanbgc-3d-det-1-monthly-mean-y%4yr", 1, "months", 1, "days", "time", 1, "months"
-"ocean_model", "det", "det", "oceanbgc-3d-det-1-monthly-mean-y%4yr", "all", "average", "none", 2
+"oceanbgc-3d-det-1-monthly-mean-ym%4yr%2mo", 1, "months", 1, "days", "time", 1, "months"
+"ocean_model", "det", "det", "oceanbgc-3d-det-1-monthly-mean-ym%4yr%2mo", "all", "average", "none", 2
 
-"oceanbgc-3d-dic-1-monthly-mean-y%4yr", 1, "months", 1, "days", "time", 1, "months"
-"ocean_model", "dic", "dic", "oceanbgc-3d-dic-1-monthly-mean-y%4yr", "all", "average", "none", 2
+"oceanbgc-3d-dic-1-monthly-mean-ym%4yr%2mo", 1, "months", 1, "days", "time", 1, "months"
+"ocean_model", "dic", "dic", "oceanbgc-3d-dic-1-monthly-mean-ym%4yr%2mo", "all", "average", "none", 2
 
-"oceanbgc-3d-fe-1-monthly-mean-y%4yr", 1, "months", 1, "days", "time", 1, "months"
-"ocean_model", "fe", "fe", "oceanbgc-3d-fe-1-monthly-mean-y%4yr", "all", "average", "none", 2
+"oceanbgc-3d-fe-1-monthly-mean-ym%4yr%2mo", 1, "months", 1, "days", "time", 1, "months"
+"ocean_model", "fe", "fe", "oceanbgc-3d-fe-1-monthly-mean-ym%4yr%2mo", "all", "average", "none", 2
 
-"oceanbgc-3d-no3-1-monthly-mean-y%4yr", 1, "months", 1, "days", "time", 1, "months"
-"ocean_model", "no3", "no3", "oceanbgc-3d-no3-1-monthly-mean-y%4yr", "all", "average", "none", 2
+"oceanbgc-3d-no3-1-monthly-mean-ym%4yr%2mo", 1, "months", 1, "days", "time", 1, "months"
+"ocean_model", "no3", "no3", "oceanbgc-3d-no3-1-monthly-mean-ym%4yr%2mo", "all", "average", "none", 2
 
-"oceanbgc-3d-o2-1-monthly-mean-y%4yr", 1, "months", 1, "days", "time", 1, "months"
-"ocean_model", "o2", "o2", "oceanbgc-3d-o2-1-monthly-mean-y%4yr", "all", "average", "none", 2
+"oceanbgc-3d-o2-1-monthly-mean-ym%4yr%2mo", 1, "months", 1, "days", "time", 1, "months"
+"ocean_model", "o2", "o2", "oceanbgc-3d-o2-1-monthly-mean-ym%4yr%2mo", "all", "average", "none", 2
 
-"oceanbgc-3d-phy-1-monthly-mean-y%4yr", 1, "months", 1, "days", "time", 1, "months"
-"ocean_model", "phy", "phy", "oceanbgc-3d-phy-1-monthly-mean-y%4yr", "all", "average", "none", 2
+"oceanbgc-3d-phy-1-monthly-mean-ym%4yr%2mo", 1, "months", 1, "days", "time", 1, "months"
+"ocean_model", "phy", "phy", "oceanbgc-3d-phy-1-monthly-mean-ym%4yr%2mo", "all", "average", "none", 2
 
-"oceanbgc-3d-zoo-1-monthly-mean-y%4yr", 1, "months", 1, "days", "time", 1, "months"
-"ocean_model", "zoo", "zoo", "oceanbgc-3d-zoo-1-monthly-mean-y%4yr", "all", "average", "none", 2
+"oceanbgc-3d-zoo-1-monthly-mean-ym%4yr%2mo", 1, "months", 1, "days", "time", 1, "months"
+"ocean_model", "zoo", "zoo", "oceanbgc-3d-zoo-1-monthly-mean-ym%4yr%2mo", "all", "average", "none", 2
 
 
 # monthly 2d diagnostic BGC fields
 
-"oceanbgc-2d-stf03-1-monthly-mean-y%4yr", 1, "months", 1, "days", "time", 1, "months"
-"ocean_model", "stf03", "stf03", "oceanbgc-2d-stf03-1-monthly-mean-y%4yr", "all", "average", "none", 2
+"oceanbgc-2d-stf03-1-monthly-mean-ym%4yr%2mo", 1, "months", 1, "days", "time", 1, "months"
+"ocean_model", "stf03", "stf03", "oceanbgc-2d-stf03-1-monthly-mean-ym%4yr%2mo", "all", "average", "none", 2
 
-"oceanbgc-2d-stf07-1-monthly-mean-y%4yr", 1, "months", 1, "days", "time", 1, "months"
-"ocean_model", "stf07", "stf07", "oceanbgc-2d-stf07-1-monthly-mean-y%4yr", "all", "average", "none", 2
+"oceanbgc-2d-stf07-1-monthly-mean-ym%4yr%2mo", 1, "months", 1, "days", "time", 1, "months"
+"ocean_model", "stf07", "stf07", "oceanbgc-2d-stf07-1-monthly-mean-ym%4yr%2mo", "all", "average", "none", 2
 
-"oceanbgc-2d-stf09-1-monthly-mean-y%4yr", 1, "months", 1, "days", "time", 1, "months"
-"ocean_model", "stf09", "stf09", "oceanbgc-2d-stf09-1-monthly-mean-y%4yr", "all", "average", "none", 2
+"oceanbgc-2d-stf09-1-monthly-mean-ym%4yr%2mo", 1, "months", 1, "days", "time", 1, "months"
+"ocean_model", "stf09", "stf09", "oceanbgc-2d-stf09-1-monthly-mean-ym%4yr%2mo", "all", "average", "none", 2
 
-"oceanbgc-2d-wdet100-1-monthly-mean-y%4yr", 1, "months", 1, "days", "time", 1, "months"
-"ocean_model", "wdet100", "wdet100", "oceanbgc-2d-wdet100-1-monthly-mean-y%4yr", "all", "average", "none", 2
+"oceanbgc-2d-wdet100-1-monthly-mean-ym%4yr%2mo", 1, "months", 1, "days", "time", 1, "months"
+"ocean_model", "wdet100", "wdet100", "oceanbgc-2d-wdet100-1-monthly-mean-ym%4yr%2mo", "all", "average", "none", 2
 
-"oceanbgc-2d-npp2d-1-monthly-mean-y%4yr", 1, "months", 1, "days", "time", 1, "months"
-"ocean_model", "npp2d", "npp2d", "oceanbgc-2d-npp2d-1-monthly-mean-y%4yr", "all", "average", "none", 2
+"oceanbgc-2d-npp2d-1-monthly-mean-ym%4yr%2mo", 1, "months", 1, "days", "time", 1, "months"
+"ocean_model", "npp2d", "npp2d", "oceanbgc-2d-npp2d-1-monthly-mean-ym%4yr%2mo", "all", "average", "none", 2
 
-"oceanbgc-2d-pprod_gross_2d-1-monthly-mean-y%4yr", 1, "months", 1, "days", "time", 1, "months"
-"ocean_model", "pprod_gross_2d", "pprod_gross_2d", "oceanbgc-2d-pprod_gross_2d-1-monthly-mean-y%4yr", "all", "average", "none", 2
+"oceanbgc-2d-pprod_gross_2d-1-monthly-mean-ym%4yr%2mo", 1, "months", 1, "days", "time", 1, "months"
+"ocean_model", "pprod_gross_2d", "pprod_gross_2d", "oceanbgc-2d-pprod_gross_2d-1-monthly-mean-ym%4yr%2mo", "all", "average", "none", 2
 
 
 # monthly scalar BGC timeseries snapshots
diff --git a/ocean/diag_table_source.yaml b/ocean/diag_table_source.yaml
index b1290898..f866652b 100755
--- a/ocean/diag_table_source.yaml
+++ b/ocean/diag_table_source.yaml
@@ -386,7 +386,7 @@ diag_table:
             file_name_dimension: 3d  # descriptor for filename, e.g. 3d, 2d, scalar
             output_freq: 1  # integer: output sampling frequency in output_freq_units (0: every timestep; -1: only at end of run)
             output_freq_units: months  # time units for output: years, months, days, hours, minutes, or seconds
-            file_name_date: "y%4yr"  # run date/time of file opening; format: %, 1 digit (#digits), one of (yr, mo, dy, hr, mi, sc); date/time components will be separated by _ in filename.
+            file_name_date: "ym%4yr%2mo"  # run date/time of file opening; format: %, 1 digit (#digits), one of (yr, mo, dy, hr, mi, sc); date/time components will be separated by _ in filename.
         fields:
             adic:
             alk:
@@ -404,7 +404,7 @@ diag_table:
             file_name_dimension: 2d  # descriptor for filename, e.g. 3d, 2d, scalar
             output_freq: 1  # integer: output sampling frequency in output_freq_units (0: every timestep; -1: only at end of run)
             output_freq_units: months  # time units for output: years, months, days, hours, minutes, or seconds
-            file_name_date: "y%4yr"  # run date/time of file opening; format: %, 1 digit (#digits), one of (yr, mo, dy, hr, mi, sc); date/time components will be separated by _ in filename.
+            file_name_date: "ym%4yr%2mo"  # run date/time of file opening; format: %, 1 digit (#digits), one of (yr, mo, dy, hr, mi, sc); date/time components will be separated by _ in filename.
         fields:
             stf03: # o2 air-to-sea flux
             stf07: # dic air-to-sea flux