Photosynthetically Active Radiation (PAR) Standard Deviation of Long-term Mean, 2002-2013 - Hawaii

Solar irradiance is one of the most important factors influencing coral reefs. As the majority of their nutrients are obtained from symbiotic photosynthesizing organisms, reef-building corals need irradiance as a fundamental source of energy. Seasonally-low irradiance at high latitudes may be linked to reduced growth rates in corals and may limit reef calcification to shallower depths than that observed at lower latitudes. However, high levels of irradiance can lead to light-induced damage, production of free radicals, and in combination with increased temperatures, can exacerbate coral bleaching. This layer represents the standard deviation of the 8-day time series of irradiance (mol/m2/day) from July 2002 to December 31, 2013. Irradiance is here represented by PAR (photosynthetically active radiation), which is the spectrum of light that is important for photosynthesis. Monthly and 8-day 4-km (0.0417-degree) spatial resolution data were obtained from the MODIS (Moderate-resolution Imaging Spectroradiometer) Aqua satellite instrument from the NASA OceanColor website (

The standard deviation of the long-term mean of PAR was calculated by taking the standard deviation over all 8-day data from 2002-2013 for each pixel. A quality control mask was applied to remove spurious data associated with shallow water, following Gove et al., 2013. Nearshore map pixels with no data were filled with values from the nearest neighboring valid offshore pixel by using a grid of points and the Near Analysis tool in ArcGIS then converting points to raster.

Data and Resources

Additional Info

Field Value
Last Updated September 19, 2019, 17:27
Created September 19, 2019, 17:27
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bbox-north-lat 22.42373568629166
bbox-south-lat 18.755036208219373
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graphic-preview-description Sample image.
guid hi_otp_all_par_std
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metadata-date 2017-03-14
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