College of Marine Science Optical Oceanography Laboratory | ||||
PANAMA Region & Data Description Tips Animate The Panama is an area bounded within these coordinates: 15°N 7.5°N 75°W and 84°W. For MODIS color passes, there are eight image products produced. Products include: a ci (Color Index) image, an afai (Alternative Floating Algae Index) image, a flh (Fluorescence Line Height) image, a nflh (Normalized Fluorescence Line Height) image, a ERGB (Enhanced Red-Green-Blue) image, a chlor-a (Chlorophyll-A) image, an SST (Sea Surface Temperature) image and a normal rgb image. For VIIRS color passes, there are five image products produced. Products include: an afai (Alternative Floating Algae Index) image, a ERGB (Enhanced Red-Green-Blue) image, a chlor-a (Chlorophyll-A) image, an SST (Sea Surface Temperature) image and a normal rgb image. You will notice that the most current imagery date is displayed. If there are several passes, they will be seen inside each of the tabs. All images are mapped to a cylindrical equidistant projection. All images are at 1 kilometer resolution. All images are mapped to a cylindrical equidistant projection. More information / references for any of the products can be found in the 'information' link located beneath every image. Where colorbars are available and applicable, if you click on a google earth icon, the colorbar will be shown inside Google Earth. For example, RGB and ERGB images have no associated color bar. When you click on a google earth icon, a kml file will be generated and sent for you to use in Google Earth. HYCOM current data is also included in our kml files. Depending on the date of the image, different model experiments and runs have been used. The exact model and run is a clickable feature in the kml file. The HYCOM consortium is a multi-institutional effort sponsored by the National Ocean Partnership Program (NOPP), as part of the U. S. Global Ocean Data Assimilation Experiment (GODAE), to develop and evaluate a data-assimilative hybrid isopycnal-sigma-pressure (generalized) coordinate ocean model (called HYbrid Coordinate Ocean Model or HYCOM). The is default is to be visible in Google Earth, but the visiblity can be turned off by unchecking the Ocean Currents checkbox in the document. NOTE: HYCOM is forecast data for the current date and should not be compared to real-time buoy data. HYCOM data is updated nightly and becomes the best available for imagery over 5 days old. When a Google Earth link is clicked for a 'color' image (CI, CHL, RGB or ERGB depending on the area), in regions that contain Florida, or parts of Florida, Florida's FWC Karenia brevis data will be displayed as a layer. This will happen if you are viewing images from any week but the current week. Since FWC makes the data available on Friday, current week images do not have an association to K. brevis data until Saturday. The K. brevis data displayed corresponds to the date of the images you are viewing. All images during any one week are linked to that week's FWC K. brevis data. More information can be found at the Florida Fish and Wildlife Conservation Commission's Red Tide Current Status page Mouse over an image to see a larger thumbnail. Click on the thumbnail image itself to open the highest resolution image in a new window or tab (depending on your browser). Some data is presented at 1 kilometer resolution (1KM), other data are presented at 250 meter resolution (QKM). The tabs represent different passes on the same day. The default is to select the latest pass available, and the last pass on any given day. Use the Calendar above the "Menu" to select the date you wish to see. You can use either the Month / Year drop down boxes or the arrows to the right and left of them to navigate by month. Should you need to link directly to a specific page and tab, you can click on the 'Direct Link Here' under each image and copy the new address in the browser, or, more simply, right click and copy the link location. |
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AFAI: Alternate Floating Algae Index (in reflectance units) to detect ocean surface features such as Sargassum, green macroalgae, and cyanobacteria. AFAI is a 1km product and nearly identical to FAI, except that the band combination is different. It is more sensitive than FAI to detect subtle ocean surface features, but it saturates under sun glint, clouds, or thick aerosols (i.e., less coverage than FAI). See FAI description for more algorithm details.
CHLOR_A: chlorophyll-a concentration (in mg/m^3) in the surface ocean layer estimated with the most updated calibration and algorithms in the SeaDAS processing software (default product). Over most open ocean waters it is fairly accurate (40-50% RMS uncertainty without significant bias see McClain et al. 2004 for more details). Over clear, shallow waters (< 30 m) or over very turbid coastal waters or river plumes, it is often overestimated as other components (colored dissolved organic matter, suspended sediments, ocean bottom) interfere with the algorithm (e.g., Hu, 2008).
CI: MODIS Color Index derived from reflectance data after correction for gaseous absorption, molecular scattering, and sun glint effects. It is basically the reflectance at 555 nm, referenced against linear baseline between 469 and 645 nm (Hu, 2011). CI has the advantage over the “standard” NASA chlor_a or other products because it is nearly immune to sun glint contamination, and therefore increases the data coverage for subtropical and tropical oceans. This is particular useful for cruise planning and for feature tracking. The MODIS standard product MOD35 (Ackerman et al., 2010) is used to discriminate clouds from water, and a cloudmask (grey color) is overlaid on the image.
ERGB: Enhanced Red-Green-Blue composite image from normalized water-leaving radiance at 547 nm (R), 488 nm (G), and 443 nm (B). The latter three are standard data products of the SeaDAS processing. The image is used to identify various ocean water types, from shallow (bright), sediment-rich (brownish), phytoplankton-rich (darkish), CDOM-rich (colored dissolved organic matter) (darkish), to blue waters (bluish) (see Hu et al., 2004 & 2005 for using this type of image to identify dark waters).
FLH: Fluorescence Line Height (in reflectance units), derived using the spectral reflectance (after correction of the gaseous absorption and molecular scattering effects) and the Letelier and Abott (1996) baseline subtraction algorithm. It measures the solar stimulated chlorophyll-a fluorescence. In sediment-poor waters (< 5 ug/L) it can be used as a better proxy than the “standard” chlor_a product to represent surface chlorophyll-a concentrations (Hu et al., 2005), as FLH is much less sensitive to CDOM interference (McKee et al., 2007; Gilerson et al., 2007).
NFLH: Normalized Fluorescence Line Height (in mW cm^-2 um^-1 sr^-1), a standard data product from the SeaDAS processing software using the Letelier and Abott (1996) baseline subtraction algorithm. It is a measure of the solar stimulated chlorophyll-a fluorescence. In sediment-poor waters (< 5 ug/L) it can be used as a better proxy than the “standard” chlor_a product to represent surface chlorophyll-a concentrations (Hu et al., 2005), as FLH is much less sensitive to CDOM interference (McKee et al., 2007; Gilerson et al., 2007). "Normalize" means that the data are normalized against input solar light and partially corrected for the effect of sediment 'contamination'.
RGB: Red-Green-Blue composite image showing clouds, ocean, and land. The calibrated radiance is first converted to reflectance, and then corrected for gaseous absorption and molecular (Rayleigh) scattering effects (software credit: Liam Gumley, Jacques Descloitres, and Jeffrey Schmaltz of the University of Wisconsin). The resulting reflectance in the three MODIS bands (645 nm: R; 555 nm: G; 469 nm: B) is stretched to 0-255 to obtain the RGB image.
SST4: Sea Surface Temperature (in Degree C) estimated with the SeaDAS processing software (default product) using a multi-channel non-linear regression algorithm (Brown and Minnett, 1999). The difference from the "sst" image is that sst4 is derived from the 4-um channels instead of the 10-um channel, and therefore has higher sensitivity (image is sharper than sst). For most ocean waters RMS uncertainty is often within 0.5 degree, for coastal waters in the Gulf of Mexico RMS uncertainty is less than 1 degree (Hu et al., 2009). Most errors come from cloud contaminations. The MODIS standard product MOD35 (Ackerman et al., 2010) is used to discriminate clouds from water, and a cloudmask (grey color) is overlaid on the image.
SST: Sea Surface Temperature (in Degree C) estimated using the SeaDAS processing software (default product) with a multi-channel non-linear regression algorithm (Brown and Minnett, 1999). For most ocean waters RMS uncertainty is often within 0.5 degree, for coastal waters in the Gulf of Mexico RMS uncertainty is less than 1 degree (Hu et al., 2009). Most errors come from cloud contaminations. The MODIS standard product MOD35 (Ackerman et al., 2010) is used to discriminate clouds from water, and a cloudmask (grey color) is overlaid on the image.
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