The NOAA Coral Reef Watch (CRW) daily global 5km (0.05 degree exactly) satellite coral bleaching heat stress monitoring product suite presented here is Version 3.1 (v3.1). It spans January 1, 1985 to present and is based on CRW's v3.1 daily global 5km satellite sea surface temperature (SST) data product known as CoralTemp.

This v3.1 5km product suite was developed based on user requests and to address errors identified in the source SST data for CRW's v3.0 products for some coral reef regions during 2013-2016. It now comprises the core of CRW's decision support system for coral reef management, providing service at or near reef-scales, allowing direct monitoring of 95% of global coral reefs and significantly reducing data gaps caused by cloud cover.

CRW's current v3.1 daily global 5km satellite products include: SST (a.k.a. CoralTemp), SST Anomaly, Coral Bleaching HotSpot, coral bleaching Degree Heating Week (DHW), a single-day Bleaching Alert Area, a 7-day maximum Bleaching Alert Area, and a 7-day SST Trend. CRW produces year-to-date (for the current year), monthly, and annual composites of the SST, SST Anomaly, Coral Bleaching HotSpot, DHW, and Bleaching Alert Area products. We also provide the most recent 30-day and 90-day animations of the SST, SST Anomaly, Coral Bleaching HotSpot, DHW, Bleaching Alert Area (7-day maximum), and SST Trend products. In addition, we offer daily 5km Regional Virtual Stations/Bleaching Heat Stress Gauges and a free, automated 5km Satellite Bleaching Alert Email System that are based on the global products presented here.

Note that SST variability is often considerably higher at the much finer 5km spatial and daily temporal resolutions, when compared with CRW's heritage twice-weekly global 50km (0.5-degree) monitoring products. Due to resulting day-to-day fluctuations between stress levels in highly-variable locations, the single-day 5km Bleaching Alert Area product does not consistently and adequately identify potentially harmful heat stress levels, especially with regard to accumulated heat stress impacts. Rather than requiring users to examine the single-day 5km Bleaching Alert Area product over several days, a 7-day maximum Bleaching Alert Area composite product, updated daily, was introduced in the v2 product suite and is maintained here in v3.1. (Evolution of CRW's daily global 5km product suites can be found here.) This 7-day composite product shows the maximum stress level that a satellite pixel has experienced during the most recent seven (7) consecutive days. Data and images are dated on the last day of the 7-day period. Notably, it is compatible with CRW's heritage twice-weekly global 50km Bleaching Alert Area product, as the 50km Bleaching Alert Area is based on a half-week (3 or 4 days) composite of 50km SSTs (but with much less SST variability due to its much coarser spatial resolution).

For the 5km 7-day SST Trend product, which is updated daily, CRW provides information on the pace and direction of the SST variation and thus coral bleaching heat stress, if present, over the past seven days. Introduced in CRW's v2 product suite, and maintained here in v3.1, the composite SST Trend product includes seven daily global SSTs in its calculation. Pixels colored in green have insignificant trends, due either to small SST trends (within the range -0.2 to 0.2 °C) or trends that failed the two-tailed Student's-t test for the 20% significance level with five degrees of freedom.

All other v3.1 5km products presented here (excluding the monthly and annual composites) are single-day products, which are updated daily. Normally, processing of the current day's products, which occurs midday U.S. Eastern Time, produces the data for yesterday's date. For example, data processed on a Wednesday afternoon will include all observations made on Tuesday (independent of time zone) and will produce images that carry Tuesday's date.

CRW developed the v3.1 5km coral bleaching heat stress products with funding support from the NOAA Coral Reef Conservation Program. The first phase of the product release was completed April 11, 2018, with products spanning 1985-2017; the full release was completed August 1, 2018, with the addition of 2018-present data.