Box and polygon triggers with tiered payouts

A single-threshold trigger asks one question: did a reading pass a value inside a circle? Parametric bonds are rarely written that way. They name boxes or polygons, a payout schedule in tiers, the agency whose record settles it, and which revision of that record counts. Calchis's second determination standard, determination/2, expresses exactly that.

Writing the terms

On Triggers, create a trigger and choose Cat-in-a-box, tiered payout. The terms are:

Zones. One or more boxes or polygons, each with its own name as the documentation gives it.

Tiers. For each zone, the readings that pay and how much: for example 25% at or below one central pressure, 60% at a lower one, 100% at the lowest. A more severe tier must pay more. The payout is the greatest reached in any one zone; zones do not add.

The rule. Minimum central pressure or maximum sustained wind while the storm's center is in a zone, for hurricanes; magnitude with the epicenter in a zone, for earthquakes, with an optional depth limit and magnitude types.

Source and revision. The NHC operational advisory as first issued, or NHC's post-season best track; ComCat's first report, or its reviewed origin. The choice is the term most often argued about, so it is named rather than implied.

Between fixes (optional). Many terms count a center that crosses a box between two published positions. Turn this on and the track is taken as a straight line between consecutive fixes no more than the stated number of hours apart; where the line crosses a zone's edge, the reading there counts too.

The terms are hashed into an identifier, so two parties who agree the same terms get the same id, and any change gives a new one.

Backtesting

Run backtest on the trigger's page replays the record one year at a time through the same evaluator that settles the live trigger, with the risk period moved to that year. It shows the years that paid, the zone and reading that decided each, the share of years that reached a tier, and the mean payout over the record. Only NHC's own fixes are counted. Where the archive does not hold the source the terms name (historical operational advisories, ComCat's first reports), the replay reads the nearest record it holds and says so.

Reading the current forecast

While a storm is active, the trigger's page reads NHC's latest forecast against your zones: whether the forecast track enters each one, when and at what forecast wind, and whether the five-day cone reaches it. For wind terms it shows the tier that wind would reach if the forecast verified. NHC does not forecast central pressure, so pressure terms show where the track goes and no tier. An outlook is a forecast, superseded by each advisory, and never a determination.