9517156f-124c-4f44-8ddb-c863aa7a3971 urn:uuid eng UTF-8 nonGeographicDataset nonGeographicDataset 2025-06-23T08:40:05 creation ISO 19115 2016 IMOS - Satellite Remote Sensing - Ocean colour Sub-Facility 9517156f-124c-4f44-8ddb-c863aa7a3971 The Aqua satellite platform carries a MODIS sensor that observes sunlight reflected from within the ocean surface layer at multiple wavelengths. These multi-spectral measurements are used to infer the concentration of chlorophyll-a (Chl-a), most typically due to phytoplankton, present in the water. The data are produced from the near real time (nrt) data stream formed by combining data from all the available direct broadcast reception stations in Australia (Alice Springs, Melbourne, Townsville, Perth, Hobart). The data are presented as a sequence of granules, each with a maximum size corresponding to 5 minutes of data, and beginning on UTC-5 minute boundary (eg. 04:05, 04:10, 04:15). The granules have been remapped from satellite projection into a geographic (Latitude/Longitude axes) projection and are formatted as CF-compliant netCDF files. It should be noted that the data are not processed until the definitive spacecraft ephemeris becomes available, usually 12-24 hours after the overpass. This means that the geolocation should be of a uniformly high standard. There are multiple retrieval algorithms for estimating Chl-a. These data use the OC3 method recommended by the NASA Ocean Biology Processing Group and implemented in the SeaDAS processing software l2gen. The radiometric sensitivity of the MODIS sensor is evolving continuously during its mission and is being monitored regularly. The SeaDAS software uses tables of calibration coefficients that are updated periodically. From time to time upgrades to the algorithms and thand/or the format of the calibration tables are required, in which case a new version of SeaDAS is released. These data are initially being produced using SeaDAS 6.1, then SeaDAS 6.4 and eventually with SeaDAS 7.x. The data processed with each different version can be distinguished by the digits at the end of the root URL for the data; for example l2oc.nrt.61 is level-2 ocean colour (l2oc), using the near real time (nrt) data stream, produced using SeaDAS 6.1. {"type": "Polygon", "coordinates": [[[75.0, -70.0], [179.9, -70.0], [179.9, 10.0], [75.0, 10.0], [75.0, -70.0]]]} 75.0 179.9 -70.0 10.0 IMOS Sub-Facility | SRS-MODIS | Aqua OC3 Chlorophyll-a Ocean Colour Oceans | Ocean Chemistry | Chlorophyll Oceans | Ocean Optics | Ocean Color latitude longitude mass_concentration_of_chlorophyll_a_in_sea_water time Link to HTTP server documentDigital HTML Link to OPENDAP server documentDigital HTML Satellite Remote Sensing page on IMOS website documentDigital HTML Website of the Integrated Marine Observing System (IMOS) documentDigital HTML Chl-a MODIS Aqua L2 5-min granules remapped OC3 SeaDAS 6.1 - dataset download documentDigital IMOS Ocean Colour Data Archive HTML Unnamed resource documentDigital License Graphic PNG Unnamed resource documentDigital HTML