NOAA Coral Reef Watch Experimental Daily Near-Real-Time Global 25-km Satellite Sea Surface Wind Doldrums Product

The NOAA Coral Reef Watch (CRW) experimental daily satellite Sea Surface Wind Doldrums product is part of the CRW near-real-time global satellite coral bleaching monitoring product suite. The Doldrums product was initially implemented on October 1, 2006 and continues to provide updated monitoring information daily. The latest version, Version 0.3, was implemented on November 24, 2008. This metadata file provides information on the product for the most recent near-real-time updates and the archived and retrospectively-produced product dating back to June 1, 2004. The current version of the product is derived from the experimental 6-hourly near-real-time NOAA/NESDIS National Climatic Data Center (NCDC) blended satellite sea surface winds product. Wind speeds used for deriving the CRW Doldrums product were generated by blending observations from multiple satellites. The blended product offers, globally, 0.25 degree x 0.25 degree ocean surface (10-meter height) winds interpolated from observations from up to six satellites. The blending of multiple satellite observations allows for greatly enhanced temporal resolution (up to 6-hourly). The satellites that have contributed to the Doldrums product include Special Sensor Microwave/Imager (SSM/I) sensors flown on-board the United States Air Force Defense Meteorological Satellite Program (DMSP) F13, F14, and F15 satellites; the Tropical Rainfall Measuring Mission's (TRMM) Microwave Imager (TMI) on-board the TRMM satellite; SeaWinds scatterometer on-board the Quick Scatterometer (QuikSCAT) satellite; and the Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E) sensor on NASA's Aqua satellite. CRW uses wind speed data from these satellites to identify regions of low wind conditions, defined here as exhibiting a daily mean of less than 3 meters per second (i.e. "doldrums"). The duration of doldrums events is then tracked by accumulating the number of days over which this condition is met (doldrums days). As an experimental product, CRW's Sea Surface Wind Doldrums product undergoes continual development and refinement to determine the best configuration for the algorithm and to test its utility against past bleaching events. While basin-scale coral bleaching occurs as a result of large-scale climate phenomena, local weather patterns greatly influence bleaching variability among sites within a basin. Three related factors that influence local bleaching patterns are temperature, light, and mixing. One parameter that exerts a common influence over all of these is wind. As wind speed falls, there is reduced vertical mixing, evaporative cooling, and sensible heat transfer, increasing the likelihood of adverse temperature excursions during summertime maximum water temperatures (Mumby et al. 2001, Dunne and Brown 2001, Skirving and Guinotte 2001, Obura 2005). In addition, pronounced stratification that can result under low-wind conditions can enhance photo-degradation of colored dissolved organic material, thereby reducing shading over corals and enhancing the likelihood of bleaching (Manzello et al., 2006). Related details, as well as other important information, are provided in each HDF data file. The Sea Surface Wind Doldrums product is available in various formats, including static image, HDF data, and Google Earth. The product, its detailed description, and available data formats and delivery mechanisms are accessible at: http://coralreefwatch.noaa.gov/satellite/doldrums_v2/index.php.