i4dvar ex1 blowup at first time step

[briskbamboo]

Dear

I am studying I4dvar and trying to run it's exercises. After compiled the model I run with the default in file "roms_wc13_2hours.in" The model blow up at first time step with log file

log_dt1800.txt

(82.13 KiB) Downloaded 397 times

As other has suggested that I can reduce the timestep to pass this case problem then I try to smaller time step from 1800 to 180 then the model blow up at the second steps with the log file

log_dt180.txt

(82.44 KiB) Downloaded 371 times

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My input file is

roms_wc13_2hours.txt

(142.95 KiB) Downloaded 385 times

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I have already read 3 papers and the tutorial files related to 4dvar recommended by the guide but found no information about this case of blow up with it default setting.