Thanks.
these dumps at 6-yr intervals presumably correspond to the cycle frequency (6yrs)
dump.19810101
dump.19870101
dump.19930101
dump.19990101
dump.20050101
dump.20110101
dump.20170101
these dumps
dump.19900101
dump.20000101
dump.20100101
dump.20200101
arise from the setting dump_period = 10yrs (see 6.35. output.nml — Joint UK Land Environment Simulator (JULES) v7.4 User Guide)
I am not sure where dump.20220101 comes from.
So to get a dump at 2001, try setting dump_period = 21
Grenville