The two main objectives of this project were to operationalize the use of satellite ocean color data in water quality management decisions and to advance the scientific basis for ocean color remote sensing of water quality in nearshore coastal waters.

For the decision support objective, our project team worked with partners in EPA and the Florida Fish and Wildlife Research Institute to utilize remote sensing products to inform two water quality management goals in Florida:
• Develop state-wide numeric nutrient criteria in coastal waters
• Rezone the Florida Keys National Marine Sanctuary (FKNMS)
To accomplish this we (1) engaged with decision-makers to understand their data needs and how these data are used in their decision-making activities; (2a) developed approaches and data products for EPA and the state of Florida to use in their decision-making activity to determine numeric nutrient criteria (2b) developed data products for the FKNMS in support of their rezoning decisions; (3) provided scientific and technical support to the decision-makers to help them evaluate the usefulness of the data products and approaches; (4) briefed EPA’s Science Advisory Board, provided responses to comments from the Board and public stakeholder reviews, and provided public briefings to the FKNMS and stakeholders; and (5) developed a new software tool, ocean color data products, Virtual Buoy System (VBS), to increase the capacity of water quality managers to access and apply remote sensing data to water quality issues.

For the scientific objective, we conducted a novel field observational study of estuarine optical properties across Florida’s Gulf of Mexico coast and Florida Keys. The data collected in this study were used to develop and validate new algorithms to retrieve estuarine water quality observations from satellites. To demonstrate how satellite data could be used by decision-makers, we conducted case studies for coastal numeric nutrient criteria for the coastal waters of Florida and for assessment of water clarity conditions in the Florida Keys. A list of publications resulting from these efforts is provided below.

Ultimately our work on coastal numeric nutrient criteria with satellite data was incorporated into EPA’s technical support document on Florida nutrient criteria and was adopted by the State of Florida in their water quality standards outlining numeric nutrient criteria for coastal waters FLA Water Quality Standards website. EPA also now provides support through their N-STEPS programN-STEPS website to other States that are interested in applying satellite data for water quality assessment and criteria development.

Geographic Focus

Florida coastal waters to the three-nautical mile limit; regional foci on Florida Panhandle estuaries and Florida Keys

Application Readiness Level

ARL = 9 (Sustained Use)

Principal Investigator

John Lehrter, US EPA; present affiliation: Department of Marine Sciences, University of South Alabama and Dauphin Island Sea Lab

Project Team

Bruce Spiering (retired), NASA
Blake Schaeffer, US EPA
Jim Hagy, US EPA
Bill Fisher, US EPA
Robyn Conmy, US EPA
Luke McEachron, Florida Fish and Wildlife Commission and Fish and Wildlife Research Institute
Chuanmin Hu, University of South Florida
Brian Barnes, University of South Florida
Chengfeng Le, ORISE Fellow with US EPA

Collaborators and Stakeholders

State of Florida; US EPA

Technical Summary

Field and satellite-based optical data were collected and analyzed for Florida coastal waters and in regional focused studies in the Florida Panhandle, Mobile Bay, and the Florida Keys. Field studies collected both ship-based and continuous optical water quality monitoring data. These data were used for development and testing of new algorithms to retrieve estuarine and coastal water quality observations from Landsat, MODIS, MERIS, and SeaWiFS satellites. Field observations were further used to assess how adjacent watershed land-use and land-cover characteristics were related to estuarine optical properties such as spectral absorption, chlorophyll a, suspended particulate matter, and colored dissolved organic matter. Research highlights included:

1) The remote sensing methodologies and results developed in Schaeffer et al. (2012; 2013) were adopted into Florida water quality standards for nutrients in coastal waters. The Florida approach calls for continued use of satellite remote sensing for future assessments of coastal chlorophyll concentrations.
2) New methods were developed and applied to the analysis of satellite derived water clarity and attenuation of ultraviolet light in coral reef habitats and patterns and processes of chlorophyll a in estuaries Novel developments included an approach to remove bottom reflectance in water clarity estimates for the Florida Keys (Barnes et al. 2013) and a new optical water type algorithm that improves the estimation of chlorophyll a in estuarine and coastal areas of the northern Gulf of Mexico (Le et al. 2014). These methods further produced novel satellite-based, long-term, spatially synoptic datasets for analyzing patterns in relation to abiotic and biotic forcing (Barnes et al. 2013; 2014; Le et al. 2014).
3) A comparative analysis of optical properties in northeastern Gulf of Mexico estuaries was undertaken to examine the relationship with adjacent watershed land use and land cover (Le et al. 2015). This was the first study to describe such relationships, which generally showed that increasing proportions of agricultural and urbanized land uses in a watershed were related to increasing absorption by chlorophyll a (decreasing water clarity) and changes in the quality and composition of estuarine organic matter. The results are translatable to management decisions that seek to protect or restore water clarity for important estuarine and coastal habitats like seagrasses as well as for satellite retrieval of estuarine water quality.
4) Satellite derived water clarity and UV attenuation data (Barnes et al. 2013; 2014) were combined with satellite derived temperature data to develop an improved coral bleaching model for the Florida Keys (Barnes et al. 2015). These results may be used by managers in the Florida Keys to identify and protect refugia within the system where corals are less prone to temperature and UV exposures that result in bleaching.
5) New software tools were developed to facilitate the use of satellite remote sensing data by water quality managers. The Water Quality Analysis Tool (WQAT) removes some of the barriers to entry for processing satellite data and extracting data for analysis and is being used in pilot studies with States through the EPA N-STEPS program. A Virtual Buoy System (VBS, Hu et al. 2014) was operationalized at the University of South Florida Virtual Buoy System website to provide near real-time and historical satellite derived water quality data for our study sites. VBS data include sea surface temperature, chlorophyll a, photosynthetically available radiation (PAR), light attenuation as Kd(488), and light penetration into the water-column.

Additional Information

Project Publications
Barnes BB, Hallock P, Hu C, Muller-Karger F, Palandro D, Walter C, Zepp R. 2015. Prediction of coral bleaching in the Florida Keys using remotely sensed data. Coral Reefs, 34:491-503.

Barnes BB, Hu C. 2013. A hybrid cloud detection algorithm to improve MODIS sea surface temperature data quality and coverage over the Eastern Gulf of Mexico. IEEE Transactions on Geosciences and Remote Sensing 51:3273-3285.

Barnes BB, Hu C, Cannizzaro, J, Craig SE, Hallock P, Jones DL, Lehrter JC, Melo N, Schaeffer BA, Zepp R. 2014. Estimation of diffuse attenuation of ultraviolet light in optically shallow Florida Keys waters from MODIS measurements. Remote Sensing of Environment 140:519-532.

Barnes BB, Hu C, Holekamp KL, Blonski S, Spiering BA, Palandro D, Lapointe B. 2014. Use of Landsat data to track historical water quality changes in Florida Keys marine environments. Remote Sensing of Environment., 140:485-496.

Barnes BB, Hu C, Muller-Karger F. 2011. An improved high-resolution SST climatology to assess cold water events off Florida. IEEE Geoscience and Remote Sensing Letters. 8(4):769-773.

Barnes BB, Hu C, Schaeffer BA, Lee Z, Palandro DA, Lehrter JC. 2013. MODIS-derived spatiotemporal water clarity patterns in optically shallow Florida Keys water: A new approach to remove bottom contamination. Remote Sensing of Environment 134:377-391.

Hu C, Barnes BB, Murch B, Carlson P. 2014. Satellite-based virtual buoy system (VBS) to monitor coastal water quality. Optical Engineering. 53(5), 051402.

Hu, C, Le, C. 2014. Ocean color continuity from VIIRS measurements over Tampa Bay. Geoscience and Remote Sensing Letters, IEEE, 11:945-949.

Le C, Lehrter JC, Hu C, Murrell MC, Qi L. 2014. Spatio-temporal chlorophyll-a dynamics and its driving factors on the Louisiana continental shelf: results from satellite observations. Journal of Geophysical Research: Oceans doi:10.1002/2014JC010084.

Le C, Lehrter JC, Schaeffer BA, Hu C, MacIntyre H, Hagy JD, Beddick DL. 2015. Relation between inherent optical properties and land use and land cover across Gulf Coast estuaries. Limnology and Oceanography 60:920-933.

Schaeffer BA, Hagy JD, Conmy RN, Lehrter JC, Stumpf RP. 2012. An approach to develop numeric water quality criteria for coastal waters using the SeaWiFS satellite record. Environmental Science and Technology 46:916-922.

Schaeffer BA, Hagy JD, Stumpf R. 2013. An approach to developing numeric water quality criteria for coastal waters: transitioning from SeaWiFS to MODIS and MERIS. Journal of Applied Remote Sensing DOI: 10.1117/1.JRS.7.073544.

Schaeffer BA, Schaeffer KG, Keith D, Lunetta RS, Conmy R, Gould RW. 2013. Barriers to adopting satellite remote sensing for water quality management. International Journal of Remote Sensing 34:7534-7544.

Schaeffer, Conmy, Duffy, Aukamp, Yates, & Craven. 2015. Northern Gulf of Mexico estuarine colored dissolved organic matter derived from the MODIS satellite. International Journal of Remote Sensing 36:2219-2237.

Zhao J, Barnes B, Melo N, English D, Lapointe B, Muller-Karger F, Schaeffer B, Hu C. 2013. Assessment of satellite-derived diffuse attenuation coefficients and euphotic depths in south Florida coastal waters. Remote Sensing of Environment. 131: 38-50.

Zhao J, Hu C, Lapointe B, Melo N, Johns EM, Smith RH. 2013. Satellite-observed black water events off Southwest Florida: Implications for coral reef health in the Florida Keys National Marine Sanctuary. Remote Sens., 5:415-431.