Add incremental analysis update capability

[weiwangncar]

TYPE: new feature

KEYWORDS: data assimilation, incremental analysis update

SOURCE: Min Chen of IUM/CMA and internal

DESCRIPTION OF CHANGES:
Add incremental analysis update capability. In the DA code, code is added to write out analysis increments for all variables in WRF netCDF format using auxiliary history output stream #5. In the model, analysis increments are divided by the number of time steps in a specified time window and added to the model similar to physics tendencies. The input stream for the model is 15. The capability is turned on by adding iau = 1 and iau_time_window_sec in &time_control. For example:

 auxinput15_inname                   = "wrfiauinp_d01"
 io_form_auxinput15                  = 2
 auxinput15_interval                 = 360,
 iau                                 = 1
 iau_time_window_sec                 = 3600.

LIST OF MODIFIED FILES:
M Registry/Registry.EM_COMMON.var
M Registry/Registry.wrfvar
M Registry/registry.em_shared_collection
A Registry/registry.iau
M dyn_em/module_em.F
M dyn_em/module_first_rk_step_part2.F
M phys/module_physics_addtendc.F
M var/build/da.make
M var/build/depend.txt
M var/da/da_main/da_solve.inc
M var/da/da_main/da_wrfvar_io.f90
M var/da/da_main/da_wrfvar_top.f90
A var/da/da_main/da_write_anaincrements.inc
M var/da/da_transfer_model/da_transfer_xatowrf.inc

TESTS CONDUCTED:
The Jenkins tests have passed.

RELEASE NOTE: This PR adds an incremental analysis update capability. In the DA code, code is added to write out analysis increments for all variables in WRF netCDF format using auxiliary history output stream #5. In the model, analysis increments are divided by the number of time steps in a specified time window and added to the model similar to physics tendencies. The input stream for the model is 15. The capability is turned on by adding iau = 1 and iau_time_window_sec in &time_control. The way the increments are added to the model is similar to what described by the paper by Chen et al. (https://doi-org.cuucar.idm.oclc.org/10.1175/WAF-D-22-0127.1).

[weiwangncar]

The regression test results:

Test Type              | Expected  | Received |  Failed
= = = = = = = = = = = = = = = = = = = = = = = =  = = = =
Number of Tests        : 23           24
Number of Builds       : 60           57
Number of Simulations  : 158           150        0
Number of Comparisons  : 95           86        0

Failed Simulations are: 
None
Which comparisons are not bit-for-bit: 
None

[dudhia]

How is input stream 15 created?

[weiwangncar]

@dudhia As described in the PR message, it is written out in DA.

[liujake]

Should you delete two commented-out lines with mchen?

[liujake]

I think we should make this IAU writing optional.

[weiwangncar]

@liujake The analysis increment file is only written out if several namliests associated with auxhist5 are added in the namelist.input file, for example, auxhist5_interval, io_form_auxhist5.

[liujake]

Ok. Looks like controlling optional writing is inside the write subroutine.

[dudhia]

I am confused why 3d variables like u_iau are in two registries.

[weiwangncar]

I am confused why 3d variables like u_iau are in two registries.

@dudhia One of the set is for WRFDA to write date out, and the other is for WRF model to read.

[dudhia]

OK, I now see that one set is in Registry*.var. I assume this Registry is not used with regsitry.iau.
Also surprised that microphysical variables can be nudged. It seems unlikely that an analysis would have those.

[weiwangncar]

OK, I now see that one set is in Registry*.var. I assume this Registry is not used with regsitry.iau. Also surprised that microphysical variables can be nudged. It seems unlikely that an analysis would have those.

Indeed, the hydrometeors’ analysis increments are the products of radar reflectivity assimilation, but it may not be available in general.

[dudhia]

Hopefully the nudging of hydrometeors is not active when they are not in the analysis.

[weiwangncar]

Hopefully the nudging of hydrometeors is not active when they are not in the analysis.

The increment arrays for hydrometeors will be zero when analysis is not available.