NOTICE !!!

NOAA Coral Reef Watch's operational twice-weekly global 50km satellite coral bleaching heat stress monitoring products were retired in April 2020, after being in service for more than two decades
(January 1997 - April 2020).

These products have been replaced with higher-resolution daily global 5km satellite products.
(https://coralreefwatch.noaa.gov/product/5km)

Archived 50km data and images are available on this page. If you need assistance, please contact coralreefwatch@noaa.gov.

 

Twice-weekly Global 50km Satellite Coral Bleaching Heat Stress Data and Products
(Archive only)

-- Heritage products serving the global coral reef community for more than 20 years --

Archives, from 2000 to 2020: twice-weekly 50km HDF data and preview images
Variable Data for download*
(choose desired server below)
Preview Image
(bmp format)
Data Info
Sea Surface Temperature (SST)** FTP, HTTP, THREDDS THREDDS HTTP, FTP Metadata
SST Anomaly (SSTA) FTP, HTTP, THREDDS THREDDS HTTP, FTP Metadata
Coral Bleaching HotSpot (HS) FTP, HTTP, THREDDS THREDDS HTTP, FTP Metadata
Degree Heating Week (DHW) FTP, HTTP, THREDDS THREDDS HTTP, FTP Metadata
Bleaching Alert Area (BAA) FTP, HTTP, THREDDS THREDDS HTTP, FTP Metadata
All-in-one***
(SST, SSTA, HS and DHW only)
FTP, HTTP, THREDDS THREDDS See
images
above
See
metadata
above
* Individual HDF file size: SST 0.4MB; SSTA 0.4MB; HS 0.3MB; DHW 0.3MB; BAA 0.3MB; All-in-one 1.4MB. Click here for more information about the HDF data.
** The sea surface temperatures (SSTs) used in CRW's 50km bleaching heat stress monitoring were nighttime-only and were used to derive all other variables.
*** An all-in-one data file contains four variables (SST, SSTA, HS and DHW) but does not include data from the BAA product.

Global and Regional Maps
(Each product's start date represents when it became operational)
Variable Web access (HTTP) FTP access
Sea Surface Temperature (SST) 2001-2020 2001-2020
SST Anomaly (SSTA) 1996-2020 1996-2020
Coral Bleaching HotSpot (HS) 1997-2020 1997-2020
Degree Heating Week DHW) 1998-1999 | 2000-2020 1998-1999 | 2000-2020
Bleaching Alert Area (BAA) 2009-2020 2009-2020
This table provides access to the collection of all global and regional maps produced operationally. Over the course of CRW's twice-weekly 50km product history, beginning with the release of the global SSTA and HS, more products (variables) and regional maps were added. As a result, the start date differs for each variable and regional map.

Monthly Composites (2001-2017)

Images:    
Data (HDF):    

Download via FTP server:        Images     |     Data (HDF)

Annual Composites (2001-2017)
Images
Variable Year (2001-2017)
Maximum Bleaching Alert Area 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17
Maximum Degree Heating Week 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17
Maximum HotSpot 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17
Maximum Sea Surface Temperature 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17
Mean Sea Surface Temperature 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17
Maximum SST Anomaly 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17
Minimum SST Anomaly 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17
Mean SST Anomaly 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17

2001-2017 Annual Composite HDF Data Files*

Download via FTP server:        Images     |     Data (HDF)

Coral Reef Watch Operational 50km Satellite Nighttime SST Climatologies
Data type .zip files .gz files
HDF data files data_files_hdf.zip (3.6MB) data_files_hdf.tar.gz (3.5MB)
Browse Images images_browse.zip (836KB) images_browse.tar.gz (836KB)

The climatologies provided here were used for the products dated before February 1, 2016. The climatology used for products as of February 1, 2016 and beyond will be made available later.

This data package includes 50km monthly mean satellite-only nighttime SST climatologies for all 12 months, and the maximum of those monthly mean climatologies. The 12 monthly mean SST climatologies have been used for producing CRW's near real-time twice-weekly global 50km SST Anomaly product. The maximum climatology, also known as the Maximum Monthly Mean (MMM) climatology, was used to produce CRW's near real-time twice-weekly global 50km Coral Bleaching HotSpot product. For more information on these climatologies, please see the description (README) and methodology pages.

A Collection of Alerts, Analyses, and Reports Posted on CRW's Website (1996-2003)

This link provides access to a collection of alert messages, analyses, and coral bleaching reports posted on the NOAA Coral Reef Watch website during its early years (1996-2003) of satellite monitoring.

50km Virtual Stations

    227 Official Stations:       Data and Graphs   |   Station List and Coordinates   |   Location Map

    26 Additional Stations:     Data and Graphs

The official 227 Virtual Stations were delivered operationally. The other 26 Virtual Stations were added later, in an experimental setting, in response to user requests. Users can access historical time-series graphs and data for each of these 50km Virtual Stations through the above links.

A 50km Virtual Station associates with only one 50km satellite data grid. For the 227 official Stations, maps showing Virtual Station locations can be accessed by clicking on a region name or a Virtual Station name, and then scrolling to the top of the Data and Graphs page. For the additional 26 Stations, to view maps of the Station locations, follow the links provided, to the right of each region name, on the Data and Graphs page.





Coral Reef Watch's (CRW) heritage near real-time twice-weekly global 50km satellite coral bleaching heat stress monitoring products presented here were operational at NOAA until April 2020, when they were offically retired, and succeeded by CRW's next-generation operational daily global 5km coral bleaching heat stress monitoring product suite. The 50km heritage products served the U.S. and international coral reef communities for more than 20 years (1997-2020). The entire 50km dataset is available here, for reference.


Product Descriptions

Sea Surface Temperature (SST): The twice-weekly global 50km SST, used for deriving the SST Anomaly and coral bleaching heat stress monitoring products (Coral Bleaching HotSpot (HotSpot or HS), Degree Heating Week (DHW), and Bleaching Alert Area (BAA)), was a satellite-based nighttime ocean temperature analysis. The SST for earlier years (before February 1, 2016) was derived from measurements by the Advanced Very High Resolution Radiometer (AVHRR) sensors onboard NOAA's Polar-orbiting Operational Environmental Satellites (POES). Each twice-weekly SST analysis was based on data from one AVHRR sensor onboard a single POES. As of February 1, 2016, however, the twice-weekly 50km SST analysis was based on NOAA's operational daily global 5km Geostationary-Polar (Geo-Polar) Blended Nighttime-only SST Analysis.

SST Anomaly: This global 50km satellite product displayed the difference between the SST of a twice-weekly period and the long-term average for the same time period (climatology). See the 'Coral Reef Watch Operational 50km Satellite Nighttime SST Climatologies' table above to access the climatology used before February 1, 2016.

HotSpot: The twice-weekly global 50km Coral Bleaching HotSpot product presented here was used to measure the occurrence and magnitude of instantaneous coral bleaching-inducive heat stress. See the 'Coral Reef Watch Operational 50km Satellite Nighttime SST Climatologies' table above to access the Maximum Monthly Mean (MMM) SST climatology, used before February 1, 2016 for this product.

DHW: The twice-weekly global 50km satellite coral bleaching Degree Heating Week product presented here was used to identify accumulated heat stress, which can lead to coral bleaching and death. CRW's DHW product accumulates the instantaneous bleaching heat stress (measured by the HotSpot product) during the prior 12-week period. It is directly related to the timing and intensity of coral bleaching. Significant coral bleaching usually occurs when the DHW value reaches 4 °C-weeks. By the time the DHW value reaches 8 °C-weeks, severe, widespread bleaching and significant mortality are likely.

BAA: The twice-weekly global 50km Bleaching Alert Area product presented here outlined the areas where coral bleaching heat stress reached various levels. CRW's coral bleaching heat stress levels are defined in the table below and are based on the values of CRW's operational 50km HotSpot and DHW products of the same date.

Stress Level
    Definition
    Potential Bleaching Intensity
No Stress
Bleaching Watch
Bleaching Warning
Bleaching Alert Level 1
Bleaching Alert Level 2
    HotSpot <= 0
0 < HotSpot < 1
1 <= HotSpot and 0 < DHW < 4
1 <= HotSpot and 4 <= DHW < 8
1 <= HotSpot and 8 <= DHW
    No Bleaching
 
Possible Bleaching
Significant Bleaching Likely
Severe Bleaching and Significant Mortality Likely

Please note that locations with a status of Bleaching Watch or No Stress for a twice-weekly time period might still have been exposed to higher heat stress, prior to the 12-week period ending on the twice-weekly time period. Although these two levels classified the environmental heat stress condition at the time, they did not take into account the stress history prior to the time in question and measured by the 50km DHW product. When the instantaneous heat stress during a twice-weekly time period dropped to a Bleaching Watch or No Stress level from a previously higher level, this product did not present any information on accumulated heat stress during the previous 12 weeks up to the twice-weekly period. Hence, a coral reef that was at Alert Level 2 one week could have dropped to a level of Bleaching Watch or No Stress the following twice-weekly period.

Composites: A monthly composite (see 'Monthly Composites (2001-2017)' table above) was derived from the corresponding data from all twice-weekly periods that ended in that month. An annual composite (see 'Annual Composites (2001-2017)' table above) was derived from the corresponding data from all twice-weekly periods that ended in that year.

50km Virtual Stations: The concept of the CRW heritage twice-weekly global 50km Virtual Station was that it was like having a temperature sensor in the water next to or at a reef, but it was completely based on satellite remote sensing measurements. The official 227 Virtual Stations were delivered operationally, and focused on some representative coral reef locations around the world. The other 26 Virtual Stations were added later, in an experimental setting, in response to user requests. CRW released its first 24 twice-weekly global 50km Virtual Stations around the world as an experimental system in 2000. That system became operational in 2003, ensuring support and delivery of the 24 50km Virtual Stations by NOAA on a 24-hour/7-day basis. On March 14, 2013, CRW upgraded and expanded its Operational Virtual Stations System to include 227 50km Virtual Stations. Those 227 50km Stations were initially developed as an experimental system in April 2011. The original 24 50km Stations were still retained in the 227-Station system, but some of their names were changed slightly. Changes to the original 24 Virtual Station names can be viewed here. A description of the twice-weekly global 50km Virtual Stations is also provided in the original CRW products tutorial.

Satellite Bleaching Alert (SBA) E-Mail System: The automated operational SBA e-mail system was part of CRW's Operational Virtual Stations System. The first operational SBA system was launched in July 2005 as a companion to the original 24 50km Virtual Stations. On March 14, 2013, CRW upgraded and expanded the SBA system to include the 227 50km Virtual Stations. A sample 50km SBA message can be viewed here. The 50km SBA e-mail system was replaced in October 2016 by CRW's next-generation 5km SBA e-mail system.

The heritage global 50km products were updated twice-weekly on every Monday and Thursday morning, U.S. Eastern Time.

Products were delivered in HDF data format and image format. Click here for more information about the HDF data.

A CoastWatch Utilities Tool can be used for visualizing the twice-weekly global 50km product data, viewing data information and values, calculating certain statistics, creating graphic output, etc. Click here to access the CoastWatch software tool.


To learn more about these twice-weekly global 50km products,
please check out our original product methodology web page,
50km products tutorial, and Liu et al. 2013.


A brief history of CRW's early years is featured in "NOAA Celebrates 200 Years of Science, Service, and Stewardship".


We request proper credit and citation to NOAA Coral Reef Watch for using these products and data.