DART-LPF algorithm has incorrect pf_enkf_hybrid default option

[braczka]

Describe the bug

Bug reported by WRF-DART user during implementation of Poterjoy particle filter (LPF) algorithm. See assim_tools_mod_pf.f90

I just noticed that pf_enkf_hybrid is set to 'true' by default in assim_tools_mod. Because you did not specify this option in your namelist, you are actually running a combination of an LPF-EnKF update, as described in this paper. I admit that this is an unfortunate default option (that should be changed in the DART repository) since it makes no sense for users to have to specify pf_enkf_hybrid in order to shut this feature off. In the meantime, set pf_enkf_hybrid = .false. under &assim_tools_nml in the namelist.

Error Message

No error message.

Which model(s) are you working with?

WRF4+

Version of DART

DARTv10.10.1

[hkershaw-brown]

@braczka I'm going to go ahead and commit the pf_enkf_hybrid=.false. to the WRF4_updates branch