ALBERT

Description: Field work was undertaken in the Lihou Reef National Marine Park (Coral Sea Territory, Australia, 17.583°S, 151.517°E) in December 2008. The aim of the remote sensing component of the field work was to collect in situ data for both remote sensing model parameterisation and for validation of remote sensing based results. Effort was placed on trying to characterise the (variations in) optical properties of the benthic substrates and vegetation that are part of the Lihou Reef Cay system (i.e. surrounding reefs and islands, respectively). Sample biotic and abiotic benthic types were sourced in situ in the intertidal- (exposed, above water) and the near-shore subtidal (submerged) zone. Benthic substratum reflectance spectra were measured from opportunistic samples collected in the intertidal and subtidal zone by snorkelers and divers. Spectral data was collected with an ASD FieldSpec Pro HandHeld spectroradiometer (http://www.asdi.com) which is designed for portability and measures over the range 325 to 1075 nm with a sampling interval of 1.4nm and a Full Width at Half Maximum (FWHM) resolution of 3nm. Substratum irradiance reflectance was calculated as the ratio of the upwelling radiance (Lu) and the downwelling irradiance (Ed): Rsub = Lu/Ed Thus the substratum reflectance is a measure of the reflection of light from the target irrespective of the illumination quantity. All measurements were collected close to the target with a 5° fore-optic fitted to the optical fibre, limiting the instrument field of view (FOV) to that of the only the target. This was done to ensure that only pure end-member spectra were collected. Ed was defined by a spectralon panel and at the same distance as the selected target. Above-water spectra were collected with the foreoptic mounted in a standard pistol-grip enabling accurate pointing of the fibre within its FOV boundaries. Reference spectra from the spectralon panel were collected at frequent intervals to compensate for the effects of variable atmospheric conditions on natural irradiance. Field spectral reflectance values were corrected for irradiance variations, assuming a linear change in irradiance over time, using these reference spectra. Additional data collected during this field campaign included: - Reflectance spectra of, intertidal and benthic substrates believed to be representative of the island/lagoon system using a non-submersible ASD FieldSpec handheld spectrometer as well as a submersible HydroRad spectrometer. - Measurements were made of the optical quality of the waters within the Lihou lagoon, the individual cay lagoons of Georgina, Anne, Lorna and Turtle cays as well as the surrounding open ocean locations.

Description: Wallis Lake is a shallow estuarine lake system consisting of lakes and rivers with interconnecting channels. The lake is a significant environmental resource and is also used for recreational activities and aquaculture. In collaboration with participants from NSW DPI, CSIRO undertook a fieldwork campaign at Wallis Lake 12-16 May 2008 to fill in known gaps in saltmarsh, mangrove, seagrass and macro-algae spectra as well as abiotic backgrounds such as sand and mud. Benthic material were collected with an Eckman grab, where the structure and shape of the sample was retained. Samples were placed on a black neoprene mat and spectra were collected using a RAMSES spectroradiometer. The RAMSES spectroradiaometer system deployed at Wallis Lake consisted of two cosine collector sensors measuring downwelling irradiance (Ed) and one radiance collector measuring upwelling radiance (Lu). In situ spectral reflectance of intertidal and supratidal vegetation were collected with an ASD-FR FieldSpec Pro spectroradiometer system which measures over a range of 325 to 2500 nm. To fill in data gaps, additional supratidal substratum spectra were collected in September 2008 with an ASD FieldSpec Pro HandHeld spectroradiometer (www.asdi.com). Substratum irradiance reflectance was calculated as the ratio of the upwelling radiance (Lu) and the downwelling irradiance (Ed): Rsub = Lu/Ed Thus the substratum reflectance is a measure of the reflection of light from the target irrespective of the illumination quantity. All measurements were collected close to the target with a 5° fore-optic fitted to the optical fibre, limiting the instrument field of view (FOV) to that of the only the target. This was done to ensure that only pure end-member spectra were collected. Ed was defined by a spectralon panel at the same distance as the selected target. Above-water spectra were collected with the foreoptic mounted in a standard pistol-grip enabling accurate pointing of the fibre within its FOV boundaries. Reference spectra from the spectralon panel were collected at frequent intervals to compensate for the effects of variable atmospheric conditions on natural irradiance. Field spectral reflectance values were corrected for irradiance variations, assuming a linear change in irradiance over time, using these reference spectra. Data collected during this field campaign included: - Inherent optical properties (IOP) and apparent optical properties (AOP) measurements of water quality in representative waters of Wallis Lake and rivers _ Reflectance measurements of seagrasses, algae and mud/sand collected with a RAMSES - field spectrometer - GPS depth transect across Posidonia beds on the eastern boundary of Wallis Island. - A pseudo invariant feature (PIF) measurement on the Wallis Island airstrip was collected to assist in the atmospheric correction of the 2003 Quickbird imagery which had exhibited significant calibration issues and could not be successfully corrected for atmospheric effects by standard methodologies undertaken by CSIRO. The reflectance values collected at the airstrip was assumed to represent reflectance at the time when the satellite image was collected. - Terrestrial reflectance spectra of saltmarsh and mangrove species as well as other key species present were collected with an ASD field spectrometer for inclusion in the spectral library as well as for validation purposes.

Description: The CoastColour project Round Robin (CCRR) project (http://www.coastcolour.org) funded by the European Space Agency (ESA) was designed to bring together a variety of reference datasets and to use these to test algorithms and assess their accuracy for retrieving water quality parameters. This information was then developed to help end-users of remote sensing products to select the most accurate algorithms for their coastal region. To facilitate this, an inter-comparison of the performance of algorithms for the retrieval of in-water properties over coastal waters was carried out. The comparison used three types of datasets on which ocean colour algorithms were tested. The description and comparison of the three datasets are the focus of this paper, and include the Medium Resolution Imaging Spectrometer (MERIS) Level 2 match-ups, in situ reflectance measurements and data generated by a radiative transfer model (HydroLight). The datasets mainly consisted of 6,484 marine reflectance associated with various geometrical (sensor viewing and solar angles) and sky conditions and water constituents: Total Suspended Matter (TSM) and Chlorophyll-a (CHL) concentrations, and the absorption of Coloured Dissolved Organic Matter (CDOM). Inherent optical properties were also provided in the simulated datasets (5,000 simulations) and from 3,054 match-up locations. The distributions of reflectance at selected MERIS bands and band ratios, CHL and TSM as a function of reflectance, from the three datasets are compared. Match-up and in situ sites where deviations occur are identified. The distribution of the three reflectance datasets are also compared to the simulated and in situ reflectances used previously by the International Ocean Colour Coordinating Group (IOCCG, 2006) for algorithm testing, showing a clear extension of the CCRR data which covers more turbid waters.

Description: The GLObal Reflectance community dataset for Imaging and optical sensing of Aquatic environments (GLORIA) includes 7,572 curated hyperspectral remote sensing reflectance measurements at 1 nm intervals within the 350 to 900 nm wavelength range. In addition, at least one co-located water quality measurement, chlorophyll a, total suspended solids, absorption by dissolved substances, and Secchi depth, is provided. The data were contributed by researchers affiliated with 53 institutions worldwide and come from 450 different water bodies, making GLORIA the de-facto state of knowledge of in situ coastal and inland aquatic optical diversity.