What exactly is a 'compound event' and why does it need a dedicated forecasting capability?

A compound event is the concurrent or closely sequential occurrence of two or more hazards — for example, a tropical cyclone making landfall on already-saturated ground while coastal upwelling drives algal blooms that contaminate emergency water supplies. Single-hazard forecast systems miss the interaction effects and tend to underestimate total impact by 40–70% according to ECMWF analysis. A dedicated compound event forecasting layer integrates multiple sensor streams, correlates them temporally and spatially, and triggers multi-hazard alerts through a single chain of command.

Can't we just buy this as a service from commercial providers like Planet, ICEYE, or Spire?

Commercial tasking services provide excellent imagery and weather data, but you are at the back of a global queue when a major compound event strikes — the same event that causes every other government to surge tasking requests simultaneously. Contract terms typically guarantee 'best-efforts' revisit, not the SLA-backed, nationally prioritised downlink a sovereign constellation delivers. Critically, a nation that relies entirely on purchased services surrenders the ability to classify, act on, or withhold sensitive damage assessments from its own territory.

What orbit and satellite class do you recommend for compound event monitoring?

A hybrid LEO constellation is the default: a primary ring of 16–36 microsatellites (50–150 kg) at 500–550 km altitude carrying multispectral and thermal imagers for flood, fire, and cyclone tracking, augmented by 4–6 SAR microsatellites for all-weather, day-night imaging. A GEO slot (or hosted payload agreement) adds full-disk atmospheric context every 10 minutes. The LEO backbone provides the sub-3-hour revisit needed to track a fast-moving compound event, while GEO fills the temporal gap between passes.

How does a sovereign constellation integrate with the WMO Early Warnings for All initiative?

WMO's EW4All initiative (launched 2022, targeting universal coverage by 2027) defines four pillars: risk knowledge, detection and monitoring, dissemination, and response capability. A sovereign constellation directly addresses pillar 2 by providing nationally controlled detection and monitoring. Data can be shared into the WMO Information System 2.0 (WIS2) to satisfy multilateral obligations without surrendering primary custody of raw imagery. Nations that contribute data receive preferential access to WMO global model outputs in return.

What is the realistic build-versus-buy cost comparison for a small to mid-sized nation?

A purpose-built 12-satellite LEO microsatellite constellation with a domestic ground station and basic data-processing pipeline typically costs $80–180M over a 10-year lifecycle for a mid-income nation leveraging off-the-shelf bus platforms. Purchasing equivalent commercial data services at market rates (imagery + weather data + analytics) runs $8–25M per year, meaning the break-even is around years 6–10. The sovereign option yields additional benefits — defence utility, STEM workforce development, export diplomacy — that are not priced into commercial contracts.

How do we disseminate compound event warnings to the last mile — remote villages with no internet?

The satellite constellation's downlink chain should feed a CAP v1.2-formatted alert broker, which then distributes simultaneously via national broadcasting, cell broadcast (mandated under ITU-R guidelines), and — critically for remote areas — satellite-enabled emergency radio networks such as those operated under UNDP's community radio programmes. Several sovereign low-Earth orbit operators (including Iridium's SBD service and emerging S-band IoT constellations from Kepler and others) support low-latency alerting to ruggedised handheld devices with no terrestrial infrastructure dependency.

How long does it take to go from contract signature to operational compound event warnings?

For a nation starting from scratch, the realistic timeline is 5–8 years to first operational capability: 12–18 months for requirements and procurement, 24–36 months for satellite manufacture and testing, 6–12 months for launch campaign and on-orbit commissioning, and 12–18 months to integrate with national meteorological and civil protection systems. Nations that adopt a hosted-payload approach on a commercial or allied constellation can compress this to 3–4 years, at the cost of reduced control over tasking priority and data formats.

What happens to compound event forecasting when two or more satellites in the constellation fail simultaneously?

Constellation resilience planning should assume a 10–15% annual attrition rate for microsatellites in LEO due to component failure, micrometeorite impact, and orbital decay. A well-designed architecture carries a 20–25% spare capacity buffer, meaning a constellation marketed as 24-satellite should be procured as a 28–30-satellite system with a standing replenishment launch contract. Nations should also negotiate a degraded-mode data-sharing agreement with allied sovereign operators to maintain coverage continuity during gaps — this is standard practice between EUMETSAT member states.

6.8.1Live

Compound Event Forecasting

Villagers wading through floodwater carrying belongings away from submerged homes — Flooding engulfs homes as a resident wades through waters that satellite compound-hazard warnings aim to predict before disaster strikes.

Satellites Fusing Multi-Hazard Compound Event Warnings

1
Sensor constellation
SAR, optical, sounder satellites observe simultaneously
2
Downlink & fusion
Multi-source data merged at ground stations
3
Compound modelling
AI correlates flood, wind, surge probabilities
4
Multi-hazard alert
SMS and sirens reach at-risk communities hours ahead

Satellite observations feed compound-event models that issue unified warnings before overlapping hazards strike vulnerable communities.

Page in the build queue

This application has its place in the atlas. The full page — short and long descriptions, what-matters bullets, sovereignty rationale, and the eight-field architecture block — is being written next.

Maturity reading: Operational systems exist with paying customers. Phase 1 built §4.1 (Maritime Intelligence) end-to-end as the depth-and-format reference. Section 4 is the next section to graduate from scaffold to full content; the rest follow on the roadmap.

Related applications

All in multi-hazard warning systems

6.8.2 · Next

Cascading Risk Modelling

Bring this into your sovereign programme.

All solutions Speak with engineering