problem with DFI and gfdda

Hello all...

I run WRF forecasts for my organization, and I've just begun experimenting with DFI. Our current forecast system uses gfdda for the outer nests, and when I turn on DFI I get warnings and then a fatal error because there are no times in the wrffdda_dXX files that correspond with the forward integration after the initial backward integration (ie, times before the nominal start of the WRF run, for my case I'm integrating back 60 minutes).

Is there an easy or standard way to deal with this? I'm considering "augmenting" the wrffdda_dXX files with a time before the nominal initialization time. For example, 3 hours before the 00Z init time. I could do this by simply copying the 00Z data (via the NCO operators ) to a separate file, subtracting 3 hours from the time, and then concatenating my new (bogus) data and the original file together to a new file.

I think that would work, even though it would apply 00Z gfdda data prior to 00Z - but only for an hour. Instead of that, is there a way to disable gfdda for the forward integration step of DFI? Some other solution?

Thanks!
Mike

For what it's worth, I was able to eventually get my idea to work, though it wasn't quite as simple as I first thought. I ended up having to augment my wrffdda_dXX files with two additional Times.

For example, if my original wrffdda_dXX files had the following Times:
Times =
"2015-12-31_00:00:00",
"2015-12-31_03:00:00",
"2015-12-31_06:00:00",
"2015-12-31_09:00:00",
"2015-12-31_12:00:00",
"2015-12-31_15:00:00" ;

Then for a DFI backwards integration of 60 minutes, and a gfdda_interval_m of 180 minutes, my modified wrffdda_dXX files needed to have:
Times =
"2015-12-31_00:00:00",
"2015-12-30_23:00:00",
"2015-12-31_00:00:00",
"2015-12-31_03:00:00",
"2015-12-31_06:00:00",
"2015-12-31_09:00:00",
"2015-12-31_12:00:00",
"2015-12-31_15:00:00" ;

It works, though I haven't yet determined whether the combination actually works well, or is at all advantageous. I also don't know if there's any better solution...

Mike