jgfs_atmos_snowanl.ecf (GFS v17)

Branch / tenant: dev/gfs.v17 (gw_v17) Path: ecf/scripts/gfs/analysis/snow/jgfs_atmos_analsnow.ecf Analysis date: 2026-06-11 Method: On-disk v17 worktree analysis.

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Summary

jgfs_atmos_snowanl.ecf (on disk as jgfs_atmos_analsnow.ecf) is the NCO production ecFlow task that runs the JEDI snow analysis for the GFS cycle. It assimilates satellite snow cover/depth observations (IMS, GHCN, SNODEP) to update the land surface snow state used by the forecast model. It calls JGLOBAL_SNOW_ANALYSIS.

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1. The script itself

Section	Detail
PBS resources	4 nodes, 64 mpiprocs, 2 OMP threads, 128 cpus/node, 15-min wall, shared
Modules	load_modules.sh ufsda (JEDI DA stack)
J-Job	JGLOBAL_SNOW_ANALYSIS
Rocoto breadcrumb	snowanl.sh

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2. Execution chain

jgfs_atmos_analsnow.ecf
  +-- JGLOBAL_SNOW_ANALYSIS
       +-- exglobal_snow_analysis.py (Python/pygfs)
            +-- JEDI OOPS/UFO snow analysis
            +-- Assimilates IMS, GHCN, SNODEP observations
            +-- Updates snow depth/SWE on model tiles

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3. v17-specific notes

• JEDI-based: uses ufsda modules (OOPS, UFO, IODA, FV3-JEDI).
• 4 nodes for parallel tile-based snow analysis.
• Hybrid threading: 64 MPI x 2 OMP = 128 cpus per node utilized.
• Python driver using pygfs snow analysis task class.
• Pre-forecast: snow analysis must complete before forecast can use updated snow fields.
• 15-min walltime — relatively fast JEDI analysis.

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4. Change-impact snapshot

Symbol	Risk	Notes
JGLOBAL_SNOW_ANALYSIS	MEDIUM	Affects initial snow state in forecast

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Sources

• On-disk v17 worktree: ecf/scripts/gfs/analysis/snow/jgfs_atmos_analsnow.ecf.