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: To be added.

[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.