# Repeated failure of the rAM3 ancil\_cap\_smcsnow task for very small domains

**URL:** <https://forum.access-hive.org.au/t/repeated-failure-of-the-ram3-ancil-cap-smcsnow-task-for-very-small-domains/5871>\
**Category:** rAM3/Regional Nesting Suite\
**Created:** [5 February 2026 07:53 UTC](https://forum.access-hive.org.au/t/repeated-failure-of-the-ram3-ancil-cap-smcsnow-task-for-very-small-domains/5871 "2026-02-05T07:53:50Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Paul.Gregory](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/paul.gregory/32/2566_2.png) [@Paul.Gregory](https://forum.access-hive.org.au/u/Paul.Gregory)\
**Post date:** [5 February 2026 07:53 UTC](https://forum.access-hive.org.au/t/repeated-failure-of-the-ram3-ancil-cap-smcsnow-task-for-very-small-domains/5871/1 "2026-02-05T07:53:50Z")

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Hello all.

So I’ve been trying to build a small regional test domain for rCM3 development. This has proven problematic, because :

1. The regional ancillary suite will not work unless you provide some land points
2. The repeated failed of the rAM3 ancillary task : `<Region>_<Resolution>_ancil_cap_smcsnow.`

Based on the the job’s outputs, the task takes the coarse resolution soil moisture content climatology file (which is at 1 x 1 degree), compute a snow climatology, and then regrid the outputs to the target file `qrclim.smow`.

For small test domains over Tasmania, the snow task would sometimes fail, and sometimes succeed depending on the number of points and domain size.

So I decided to make a minimum working example based on the default domain for rAM3.

I checked out `u-bu503/nci_access_ram3` and made the following changes to `rose-suite.conf`:

```auto
rg01_centre=-28.49,153.38
rg01_nreslns=2
rg01_rs01_npts=54,64
rg01_rs02_npts=40,40

```

The job failed. Stdout:

```auto
 SPIRAL SEARCH RADIUS SET TO 5
 RESTRICTED IN ROWS TO 20
 Reading target land sea mask 0
 Attempting to open file 
 /home/548/pag548/cylc-run/u-bu503/share/data/ancils/Lismore/d1100/qrparm.mask  

```

(and then the job ends).

Stderr:

```auto
forrtl: severe (174): SIGSEGV, segmentation fault occurred
Image PC Routine Line Source             

Stack trace terminated abnormally.
[FAIL] rose mpi-launch -v central_ancillary.exe # return-code=174

```

Unfortunately the jobs uses the precompiled binary

```auto
/g/data/access/projects/access/apps/cap/9.2/bin/central_ancillary.exe

```

And it provides no useful diagnostic errors.

FWIW I got the job to succeed by increasing the domains slightly:

```auto
rg01_rs01_npts=64,74
rg01_rs02_npts=50,50

```

If anyone is interested in this, I can commit a non-working version to the roses repo for you to check out.

My hunch is that if your domain is too small, and it doesn’t completely bracket any of the 1 degree soil moisture data, the job fails.

---

<div class="post-metadata">

**Author:** ![Scott](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/scott/32/37_2.png) [@Scott](https://forum.access-hive.org.au/u/Scott)\
**Post date:** [6 February 2026 00:54 UTC](https://forum.access-hive.org.au/t/repeated-failure-of-the-ram3-ancil-cap-smcsnow-task-for-very-small-domains/5871/2 "2026-02-06T00:54:48Z")

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CAP source code should be at [trunk in main – ANCIL](https://code.metoffice.gov.uk/trac/ancil/browser/main/trunk). I suspect you’re right that it couldn’t find a matching point in the source dataset. You could maybe try increasing the spiral search distance?