GHOST — recon-independent intensity reanalysis

GHOST estimates tropical cyclone intensity — minimum central pressure and maximum sustained wind — from geostationary infrared imagery and the large-scale environment alone. No aircraft reconnaissance, and no best-track intensity, is used as input.

What goes in

• Merged global geostationary infrared imagery (NASA MergIR, ~4 km, half-hourly) — the same imagery the frame viewer on this page displays.
• Large-scale environmental fields from reanalysis (thermodynamic and kinematic).
• Storm position from IBTrACS — position only, never intensity.

Because the estimate never sees reconnaissance or best-track intensity, it can be compared against them independently. That is what the GHOST − BT view is for.

How it is built (data version v4, the paper model)

• P_min is the equal mean of two independent members read from the same imagery: a small first-principles ridge on the environmental pressure deficit (FPM), and a boosted-tree stack with a deep-eye tier (the tree member). Where the tree abstains on a frame its last value is carried for six hours; where it never existed the ridge stands alone.
• V_max is the tree member’s direct wind head (with the Cat-5 corrections) — not derived from the pressure. In the Atlantic it abstains on QC-rejected frames.
• Every published value is held out. Atlantic and East Pacific members were fitted leave-one-year-out; West and Central Pacific are out-of-basin transfer. There is no separate frozen channel — the number shown is the held-out one.
• The same blend runs live on the Real-Time Monitor’s Experimental tab. Earlier data versions (v1, v2: a single FPM channel per basin) remain selectable below.

How to read it

• Outside the recon stratum, best-track pressure is itself largely Dvorak-derived — so a disagreement there is model-vs-model, not error. Use Recon-proximate only for the decisive comparison.
• OOB out-of-basin: the model is trained on Atlantic / East-Pacific reconnaissance labels, so West and Central Pacific storms are an out-of-basin application — zero frames from those basins were in training. That is a stricter condition than the held-out channels offered for the Atlantic and East Pacific, not a weaker one: nothing about the basin, in any season, was fitted. It is also why no held-out column is published there — there is nothing left to hold out.
• QC flagged for large trace-vs-best-track disagreement; these sink to the bottom of the default ordering.
• On the frame, the blue cross is the best-track position the scene is cut about; the red cross is the IR eye fix — where the pipeline’s centre-finder placed the eye before computing the frame’s predictors (accepted only within 50 km of the track; otherwise the best-track centre was used). On the lifecycle chart, hatched spans are stretches the best track calls extratropical or subtropical, and the recon strip marks frames with an aircraft pressure fix within ±3 h (ticks: individual aircraft fixes from the f-deck).
• ? the storm’s deepest frame is also its largest disagreement with the best track, with no reconnaissance nearby — a disagreement is not by itself an error, but that minimum has no independent support. 17 of the 724 storms in v4.
• Known cost of the mean at the extreme tail. Where the tree member saturates on the very deepest storms the mean halves the ridge’s deeper read: Patricia 2015 (best track 872 hPa) is 893 hPa in v4 (ridge 886, tree 900). Below 920 hPa the Atlantic estimates run about +6 hPa weak on average; pooled over everything the Atlantic RMSE is 6.6 hPa (slope 0.92), East Pacific 8.0, West Pacific 10.8 against Dvorak-era JTWC labels.

Manuscript in preparation. GHOST (Geostationary-based Hurricane Objective Strength Technique) is an unpublished research method; this page is provided for scientific transparency and is not an official forecast or analysis. Please contact Dr. Michael Fischer ([email protected]) before citing or redistributing these estimates.