Abstract:
Ocean color satellite imagery from the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the Aqua satellite were downloaded from the NASA Goddard Space Flight Center, Distributed Active Archive Center for fall (September to December) of 2007 and 2015. K. brevis blooms were detected using the Rrs-nFLH technique (see methods), which uses two thresholds: nFLH above 0.33 W m-2 µm-1 sr-1 and Rrs at 555 nm below 0.007 sr -1. This dataset supports the publication: Soto, I.M., Cambazoglu, M.K., Boyette, A.D., Broussard, K., Sheehan, D., Howden, S.D., Shiller, A.M., Dzwonkowski, B., Hode, L., Fitzpatrick, P.J., Arnone, R.A., Mickle, P.F., & Cressman, K. (2018). Advection of Karenia brevis blooms from the Florida Panhandle towards Mississippi coastal waters. Harmful Algae, 72: 46-64. doi: 10.1016/j.hal.2017.12.008
Suggested Citation:
Soto Ramos, Inia. 2018. Ocean color satellite detection of Karenia brevis blooms in the Mississippi Bight during fall 2007 and 2015. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N73T9FNX
Data Parameters and Units:
Karenia brevis detection output (netCDF variable name: rrshab, no units). The output is a matrix with “0” for no detection and “1” for detection of Karenia brevis bloom. Land, clouds and other bad values were defined as “NaN”.
Methods:
Ocean color satellite imagery from the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the Aqua satellite were downloaded from the NASA Goddard Space Flight Center, Distributed Active Archive Center for fall (September to December) of 2007 and 2015 (2014 Reprocessing. NASA OB.DAAC, Greenbelt, MD, USA. doi:10.5067/AQUA/MODIS/MODIS_OC.2014.0). The satellite imagery covered the region from 85° to 90°W and 29° to 30.5°N. Data was downloaded at Level-1 and processed to Level-2 using the SeaWiFS Data Analysis System (SeaDAS, version 7.3.2). Daily image composites were mapped to a rectangular projection at 1 km pixel resolution and level-2 flags were applied to discard low-quality data. K. brevis blooms were detected using the Rrs-nFLH technique (Soto et al., 2015), which uses two thresholds: normalize Fluorescence Line Height (nFLH) above 0.33 W m-2 µm-1 sr-1 and Remote sensing reflectance (Rrs) at 555 nm below 0.007 sr -1. The former threshold takes advantage of the high chlorophyll-a properties, while reducing the errors associated with CDOM. The Rrs threshold takes advantage of the low backscattering properties and eliminates pixels with high sediment concentrations which could also saturate the satellite signal and it also avoids errors associated with calculations of more complex bio-optical algorithms (such as backscattering) or regional relationships. More information about the algorithm can be found here: Soto, I.M., Cannizzaro, J., Muller-Karger, F.E., Hu, C., Wolny, J., Goldgof, D., 2015. Evaluation and optimization of remote sensing techniques for detection of Karenia brevis blooms on the West Florida Shelf. Remote Sens. Environ. 170, 239-254. The output of this technique was stored in a NetCDF with the variable name of “rrshab” file for each day. The output is a matrix with “0” for no detection and “1” for detection of Karenia brevis bloom. Level-2 flags (ATMFAIL, LAND, CLDICE, HILT, HIZATZEN) and other bad values were defined as “NaN”. The limit coordinates were stored in a separate variable called “map_bounds_swne”. File attributes (ncdump –h file) float rrshab(lat, lon) ; rrshab:units = "No Units" ; float map_bounds_swne(map_coords_dim) ; // global attributes: :description = "Rrs-FLH Karenia brevis detection" ; :source = "Soto et al., 2015, doi:http://dx.doi.org/10.1016/j.rse.2015.09.026" ; :history = "CreatedSat Aug 19 14:39:06 2017" ; :resolution = "1000 m" ; :projection = "platecarree" ; :flags = "[ATMFAIL, LAND, CLDICE, HILT, HIZATZEN]"
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