Input track files
GAHM2026 reads three track formats, selected with storm_info.file_type:
file_type |
Format | Notes |
|---|---|---|
"IBTrACS" |
IBTrACS v04 CSV | Multi-storm file; storm_info.designation selects the storm. Downloaded automatically if absent |
"ATCF" |
ATCF a-deck / b-deck | Single storm per file; designation is ignored |
"fort22" |
ADCIRC fort.22 (NWS=20) |
ATCF-like, column-compatible |
The child pages document the two fort.22 variants in detail:
- GAHM2026 fort.22 — the extended file
written by
write_fort22_ext.m, carrying the per-quadrant GAHM parameters computed by GAHM2026. - ASWIP fort.22 — the file produced by the ASWIP preprocessor to drive GAHM inside ADCIRC.
The extended file written by GAHM2026 has a format similar to ADCIRC’s
fort.22but must not be used with GAHM (NWS=20) in ADCIRC. The $R_{mw}$ and $B_g$ values are not strictly compatible with the GAHM implementation in ADCIRC.
Where the track data comes from
IBTrACS v04r01 CSV files are published by NOAA NCEI at
https://www.ncei.noaa.gov/data/international-best-track-archive-for-climate-stewardship-ibtracs/v04r01/access/csv/.
Place the file in input/; run_GAHM2026 downloads it if it is not found.
Track files are parsed by util/readIBTrACS.m (shared by GAHM2026 and SeparateEnvHur) or by the
ATCF/fort.22 reader, then trimmed to the configured processing window by sliceTrack inside
GAHM2026.m.
Units
Track quantities follow the ATCF conventions, not the SI units used internally:
| Quantity | Track file units | Internal units |
|---|---|---|
| Isotach radii, $R_{mw}$ | nautical miles | meters |
| Wind speed | knots, 1-min sustained at 10 m | m/s, 10-min average |
| Pressure | mb | mb |
| Angles | degrees clockwise from north | degrees clockwise from north |
Conversions use the constants in util/gahmPhysicalConstants.m. The 1-min to 10-min conversion
factor is GAHM_param_info.one2tenF (0.89); see
Derivation §2.