Coral Disease Outbreak Risk - Hawaiian Archipelago
(Version 2, released June 11, 2019, experimental product)
(Active for May - November 2019)

(click for full-sized image)
pixel maps
Seasonal Outlook
HAW pixel maps
Current Summer Outbreak Risk

HAW pixel maps
Winter Cold Snap
HAW pixel maps
Winter Conditions
HAW pixel maps
Summer Hot Snap


Select a disease season:              Current Season        or       

The Winter Cold Snap metric accumulates anomalously cold temperatures through time, as compared with the usual range of winter temperatures, providing an indication of unusually cold events. Such events (dark blue) reflect a reduction in pathogen loading during extreme cold periods.

The Winter Conditions metric accumulates temperature anomalies during the cold season as compared with the average temperature observed in the three coldest months ("winter") at each location. It represents the variation of the current cold season from the average condition. Mild winters (blue) have been linked to subsequent outbreaks of White Syndrome disease; research has shown that such outbreaks do not occur following cool winters (brown) or warm winters (green), likely related to a reduction in disease pathogen abundance and an increase in host resistance, respectively.

The Summer Hot Snap metric accumulates anomalously hot temperatures through time, as compared with the usual range of summer temperatures, providing an indication of unusually hot events. This metric represents the level of hot stress that corals experience.

The Seasonal Outlook (or Winter Pre-Conditioning) is based only on the cold season metrics, and gives a measure of the pre-disposition to disease outbreak during the following warm season. Only locations that experienced mild winters (blue Winter Conditions) are considered to be at-risk, with the likelihood defined by the presence/absence of unusually cold events (Winter Cold Snap). The Seasonal Outlook value is issued at the end of the cold season, providing a 3-6 month forecast of the likelihood of disease outbreak.

The Current Summer Outbreak Risk is assigned only for locations that experienced mild winters (blue Winter Conditions) and is defined by the level of hot stress (Summer Hot Snap) experienced during the subsequent warm period. Outbreak Risk in the yellow-to-red range has shown significant likelihood of disease for corals, increasing linearly with the color scale. The Outbreak Risk is updated in near real-time during the warm season.


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Reference: Heron S.F., B.L. Willis, W.J. Skirving, C.M. Eakin, C.A. Page, I.R. Miller (2010). Summer Hot Snaps and Winter Conditions: Modelling White Syndrome Outbreaks on Great Barrier Reef Corals, PLoS One.

CRTR_icon Version 2.0 product development was partially supported with funding from NASA's Ecological Forecasting Program (Applied Sciences Program), through the University of Hawai'i-Hawai'i Institute of Marine Biology, and was conducted in close collaboration with James Cook University, the University of Newcastle, and the University of New South Wales. This effort is part of the multi-year Fore-C project, "Forecasting Coral disease outbreaks across the tropical Pacific Ocean using satellite-derived data". The goal of the proposed research is to develop better models of coral disease outbreak risk across the western tropical Pacific Ocean and embed these improved forecasts into the NOAA CRW decision support system for coral reef ecosystem management.