Daily 5-km Satellite Coral Bleaching Thermal Stress Monitoring
(Version 2, experimental products)

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Regional
Gauges

Current Regional Images
Alert Area (7-day max):  Global | 45ns | East | West | Pacific | Coral Triangle [big] | Caribbean [big] | Florida | Hawaii | GBR
Hotspots:  Global | 45ns | East | West | Pacific | Coral Triangle [big] | Caribbean [big] | Florida | Hawaii | GBR
DHW:  Global | 45ns | East | West | Pacific | Coral Triangle [big] | Caribbean [big] | Florida | Hawaii | GBR
SST:  Global | 45ns | East | West | Pacific | Coral Triangle [big] | Caribbean [big] | Florida | Hawaii | GBR
SST Anomaly:  Global | 45ns | East | West | Pacific | Coral Triangle [big] | Caribbean [big] | Florida | Hawaii | GBR

Archived Regional Images
(Degree Heating Weeks, Alert Area, and others available since 3 June, 9 June, and 12 March 2013, respectively)
NOTE: A new DHW color palette was developed and implemented in this version of the 5-km products to present the relationship between DHW values and potential coral bleaching severity more clearly than the 50-km color palette. The new color groupings still distinguish the different thermal stress levels (Watch, Warning, and Alert Levels 1 and 2), and the upper end of the color palette has been extended to 20 °C-weeks. Click here to view DHW images using CRW's old 50-km color palette.

Product Suite Description

The NOAA Coral Reef Watch (CRW) experimental daily global 5-km (0.05 degree exactly) satellite coral bleaching thermal stress monitoring product suite presented here is a next-generation version of the current operational twice-weekly 50-km (0.5 degree exactly) monitoring product suite. The high-resolution 5-km suite currently includes sea surface temperature (SST), SST Anomaly, Coral Bleaching HotSpots, Degree Heating Weeks (DHW), and Bleaching Alert Area products, matching to the core operational 50-km satellite products. 5-km versions of CRW's other operational products, such as the Virtual Stations and automated Satellite Bleaching Alert E-mail System, are currently under development. The 5-km product suite provides two major improvements over the current operational 50-km product suite:

  1. Next-generation SST Analysis for Deriving the Product Suite

    1. Improved Data Density and Spatial and Temporal Resolutions

    2. Improved SST Quality with Next-Generation SST Algorithm

  2. Improved Climatology

    1. CRW's coral bleaching thermal stress products are based on SST anomaly values and therefore require a climatology (baseline temperature) from which thermal stress is determined. Since the operational daily global 5-km geostationary-polar-orbiting (geo-polar) blended nighttime-only SST data set that CRW's new 5-km products are based on only began in March 2013, it was too short to build a climatology from. Therefore, the climatology was produced using night-only values for the period 1985-2012 from the 4-km Advanced Very High Resolution Radiometer (AVHRR) Pathfinder Version 5.2 SST (PFV5.2) data set, an official NOAA climate data record. For each pixel, daily SST data of high quality (quality ≥4) were averaged for each month to produce monthly composites. These were then averaged across the 28-year period to produce 12 monthly mean climatologies. This resulted in a ten-year shift in the temporal mid-point of the data used in the climatology (mid-1998) when compared with the operational 50-km climatology (early-1988). In an era of rapid warming, this would have substantially modified the anomalies and therefore the magnitude of the 5-km HotSpot and DHW values relative to CRW's operational products. Thus, the 5-km climatological average values were re-centered to the time-center of the corresponding operational 50-km climatology.

    2. Efforts are underway in NOAA/NESDIS, at the request of CRW, to reprocess the 5-km geo-polar blended SST analysis. This will allow existing and new algorithms developed and implemented to be applied to satellite measurements from the past, producing both consistent historical datasets and an updated climatology. The reprocessing capability will eventually allow the internally consistent blended SST analysis time series to extend back to 1994 -- the start of the second-generation geostationary environmental satellite record. This will allow CRW's 5-km products to be produced retrospectively and further validated to potentially refine the interpretation of thermal stress thresholds relating to bleaching impacts. More importantly, this will enable CRW to develop new climatologies directly from a sufficiently long record of geo-polar blended night-only SST data.

This daily global 5-km coral bleaching thermal stress monitoring product suite significantly advances CRW's capability for near-real-time satellite coral bleaching thermal stress monitoring. The 5-km products will comprise the core of CRW's next-generation Decision Support System (DSS) for coral reef management. With higher spatial and temporal resolution products, CRW can now provide service at or close to reef-scales. After further testing and evaluation of the 5-km product suite, CRW's decades-old operational 50-km product suite, which has provided pioneer service to global coral reef communities, will be retired.

Version 2 of the 5-km product suite, presented here, was released on May 5, 2014. As noted above, it is based on NESDIS' operational daily global 5-km geo-polar blended nighttime-only SST Analysis, released in March 2013, and uses a new version of the 5-km climatology (available since April 2014). Version 1 of CRW's 5-km product suite, inaugurated in June 2012, was based on NESDIS' operational daily global 5-km geo-polar blended day-night SST analysis, released in March 2012, and an initial 5-km climatology.

A 7-day maximum Bleaching Alert Area composite product, updated daily, was introduced in the Version 2 product suite. This 7-day composite product shows the maximum stress level that a pixel has experienced during the most recent seven (7) consecutive days, based on the thermal stress level evaluated for each of the 7 days. The data and images are dated the last day of the 7-day period. SST variability is often considerably higher at the much finer 5-km spatial and daily temporal resolutions, when compared with CRW's 50-km twice-weekly SST. Due to resulting day-to-day fluctuations between stress levels in highly-variable locations, the 5-km single-day Bleaching Alert Area product does not consistently and adequately identify potentially harmful thermal stress levels, especially with regard to the impact of accumulated thermal stress. Rather than requiring users to examine the 5-km single-day Bleaching Alert Area product over several days, the 7-day maximum Bleaching Alert Area composite product provides coral reef ecosystem managers and other stakeholders with a much more convenient tool for monitoring recent thermal conditions. Additionally, the 5-km 7-day maximum Bleaching Alert Area composite product is compatible with CRW's operational 50-km twice-weekly Bleaching Alert Area product, as the 50-km Bleaching Alert Area product is actually based on a half-week (3 or 4 days) composite of 50-km SSTs, but with much less SST variability due to its much coarser spatial resolution.

Note that all other Version 2 products presented here are single-day products, updated daily. Images will be 1-2 days behind the current date, however, as data are processed in the early afternoon, US Eastern Time using imagery from the previous day. For example, the data processed on a Wednesday afternoon will include all observations made on Tuesday (independent of time zone), and will carry Tuesday's date.

Development of the next-generation 5-km product suite has been accomplished through a collaboration of CRW, the University of South Florida, NASA-Ames, the UNEP World Conservation Monitoring Centre, and the Cooperative Institute for Research in Environmental Science, with funding support from the NASA Biodiversity and Ecological Forecasting program and the NOAA Coral Reef Conservation Program. The 5-km product suite, which was featured in the NASA Applied Sciences Program's 2013 Annual Report, will undergo continuous improvements over the next few years.

CRW will continue to produce the current operational 50-km product suite until the 5-km product suite becomes operational. There will be some differences between the two product suites in certain areas, and user discretion is advised. We expect that the 5-km product suite will be more accurate in general, due to the improved data quality, density, spatial and temporal resolutions, and climatology.


CRW Operational Twice-weekly 50-km Product Suite