ATM 3DVAR with and without IAU

[NeilBarton-NOAA]

This is the first of a series of PRs to addresses issue #947 (cycling the S2SW app with 3DVAR). Using the ATM app, 3DVAR with IAU did not cycle out-of-the-box. This PR includes changes to successfully cycle ATM with 3DVAR with and without IAU.

Refs: #947

Changes include:

• config.base.emc.dyn for 3DVAR IAU options
• parsing_namelists_FV3.sh to filter IAU increments when using 3DVAR

Type of change

• Breaking change (fix or feature that would cause existing functionality to not work as expected)

How Has This Been Tested?

Use app ATM and DOHYBVAR="NO" with DOIAU="NO" and DOIAU="YES". Resolution tested was 384.

I cycled with a start date of 2020040100 until 2020040400. The restarts are located on hera at
/scratch2/NCEPDEV/stmp1/Neil.Barton/ICs/2020040100/C384/control

I also rested the default config with DOHYBVAR="YES" .

At one point I ran into an issue with fit2obs and gdaspostanl. However, the latest pull from develop fixed these issues for me.

• Cycled test on Hera
• Cycled test on Orion (tested before the latest pull from develop)

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes need updates to the documentation. I have made corresponding changes to the documentation
• My changes generate no new warnings
• New and existing tests pass with my changes
• Any dependent changes have been merged and published

[aerorahul]

Most of this looks good to me. I just have a few comments inline.
I would like to ask someone from the DA team to review these changes so they are not breaking the core functionality.
Do you have logs of the tests you ran for:
3DVar w/ IAU
3DVar w/o IAU
4DEnVar w/ IAU (this is the default)

[aerorahul]

This if-block is a bit confusing, as both, the if and else are for DOIAU=YES.
The if-block is for 3DVar with IAU and the second block can be hybrid (3D or 4D), but is only going to work for 4DHybEnVar as 3DEnVar will not produce increments at hours 3 and 9.

[NeilBarton-NOAA]

yes, the changes in the if block are for 3DVAR with IAU. 3DVAR with IAU does not cycle without these changes. @CatherineThomas-NOAA could you comment on the else part of the block as I'm not familiar with the 3DEnVar settings?

A proposed change is

if [[ $DOHYBVAR == "NO" && $DOIAU == "YES" ]]; then
export IAUFHRS="6"
export IAU_FHROT="3"
export IAU_FILTER_INCREMENTS=.true.
fi
export IAUFHRS=${IAUFHRS:-"3,6,9"}
export IAU_FHROT=${IAU_FHROT:-$(echo $IAUFHRS | cut -c1)}

[CatherineThomas-NOAA]

The IAU settings for 3DEnVar will be similar to 3DVar, just set the *_ENKF IAU variables the same as their deterministic counterparts (IAUFHRS --> IAUFHRS_ENKF, etc).

[aerorahul]

These should be wrapped in an if-block such as:

if [[ $DOHYBVAR = "YES" ]]; then
    export DOIAU_ENKF=${DOIAU:-"YES"}   # Enable 4DIAU for EnKF ensemble.
    export IAUFHRS_ENKF="3,6,9"
    export IAU_DELTHRS_ENKF=6
fi

[NeilBarton-NOAA]

updated

[CatherineThomas-NOAA]

This IF block is not sufficient. The IAU*ENKF variables should only be set to these values if DOIAU_ENKF="YES" and for 4D.

[NeilBarton-NOAA]

I just submitted changes to config.base.emc.dyn that simplifies the changes. The change is the addition of below if block after the "#Hybrid related" line as DOHYBVAR needed to be defined. These changes set the variables if the user runs 3DVAR with IAU.

if 3DVAR and IAU

if [[ ${DOHYBVAR} == "NO" && ${DOIAU} == "YES" ]]; then
export IAUFHRS="6"
export IAU_FHROT="3"
export IAU_FILTER_INCREMENTS=.true.
export IAUFHRS_ENKF="6"
fi

In addition, the "if [[ "$MODE" = "cycled" && "$SDATE" = "$CDATE" && $EXP_WARM_START = ".false." ]] ||"
had to be moved to after the if statement so IAU_OFFSET and IAU_FHROT could be reset when needed.

[CatherineThomas-NOAA]

@NeilBarton-NOAA Thanks for these changes. I think this is much cleaner and covers the main hybrid 4DEnVar and 3DVar cases.

[WalterKolczynski-NOAA]

Waiting for @CatherineThomas-NOAA to formally give an approving code review.