Browsing by Author "Moore, Gerald"
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- Contribuition of earth observation to understanding the upwelling conditions of the SW Coast of PortugalPublication . Icely, John; Moore, Gerald; Goela, Priscila; Cristina, Sónia; Newton, AliceValidation of MERIS (Medium Resolution Imaging Spectrometer) satellite products in the coastal upwelling system off the SW coast of Portugal has occurred since 2008 over a series of sampling campaigns at Stations 2, 10 and 18 km offshore. Data from between the 4th October and the 17th November 2008 demonstrate an upwelling event where temperature declines markedly from 20oC to 16.5oC between the 26th October and the 8th November. Other data confirming these events are profiles for conductivity, temperature and depth, as well as nutrient and chlorophyll concentrations. Nitrate peaks with chlorophyll on the 8th November, but phosphate is at low concentrations and declines before those of the nitrate over this period. The more spatially extensive sea surface temperature combined with wind velocity and direction, as well as MERIS Algal 1, supports the more site-specific observations at the validation stations. Nutrient changes due to physical forcing from upwelling occur earlier than changes in chlorophyll concentration.
- Contribution of remote sensing products to the management of offshore aquaculture at Sagres, SW PortugalPublication . Icely, John; Moore, Gerald; Danchenko, Sergei A.; Goela, Priscila; Cristina, Sónia; Zacarias, Marielba; Newton, AliceRemote sensing can address important issues affecting offshore aquaculture such as prediction of Harmful Algal Blooms. In situ data for nutrients, chlorophyll a (Chla) and phytoplankton community from a site for long-line aquaculture for bivalves off the SW coast of Portugal has been compared during a period of upwelling with remote sensing data for Chla, sea surface temperature, salinity, direction and intensity of both currents and winds. On the 11th February the in situ nutrients levels were high and the Chla was low, but by the 12th March the converse was the situation. The evolution of this event could be followed by combining remote sensing and model data from a variety of open source web sites made available by the Earth Observation provider that demonstrated clearly the lags between the physical forcings promoting upwelling and the eventual blooms of phytoplankton.
- Evaluation of the MERIS marine products in coastal and oceanic waters off Cape Sagres on the south-west coast of PortugalPublication . Cristina, Sónia; Goela, Priscila; Icely, John; Moore, Gerald; Newton, AliceIn-water constituents such as chlorophyll a, total suspended matter and yellow substances, as well as radiometric data sets from field measurements with a Satlantic hyperspectral radiometer were used to evaluate the performance of Medium Resolution Imaging Spectrometer (MERIS) sensor on the ENVISAT satellite, from inshore to offshore sites on the south west coast of Portugal. It was evaluate the performance of the Regular measurements of these parameters were taken from this region between September 2008 and July 2009 covering both Case 1 and Case 2 waters. Also was evaluate the recent developments towards improving the processing protocols for MERIS data including: the ICOL (Improved Contrast between Ocean and Land) processor; the new vicarious adjustment in the near infrared; and, most recently, the implementation of the MEGS 8 processor. Eight images were obtained under cloud free conditions, without flags for high glint, ice haze and low sun during this sampling period. Water-leaving reflectances (ρw) were estimated from downwelling Es (λ) and upwelling Lu (λ) spectral irradiances, and compared with MERIS ρw. The values of ρw were processed according to the MERIS in situ measurement protocols, before they could be compared with the MERIS data. A previous study in this area (Cristina et al., 2009) shows that are still problems with the calibrating the algorithm that links remote sensing data with in situ measurements, particularly at the coastal site where there are adjacency effects from land on the reflectance data observed by the satellite sensor. In this study ICOL processor was applied to correct this problem and improve processing on the inshore station (Station A). However the improvement was not so significant for some of the “match-ups” days. The MERIS ρw and the MERIS water products processed by the MEGS 8 didn’t improve the agreement with the in situ measurements as was expected, even with the new vicarious adjustment for the infrared wavelengths. In general, these results show that some corrections most be taken under MEGS 8 processor before coming publically available.
- OCPortugal consortium: activities and challengesPublication . Brito, Ana; Brotas, V.; Cristina, Sónia; D'Alimonte, D.; Goela, Priscila; Icely, John; Kajiyama, T.; Moore, Gerald; Newton, Alice; Sá, C.The newly-constituted Ocean Colour Portugal consortium (OCPortugal) aims at promoting the use of remote sensing (RS) products in the Atlantic off Portugal. In close collaboration with the European Space Agency (ESA), OCPortugal currently links the following institutions: Centre of Oceanography (IO), Faculty of Sciences of the University of Lisbon; CENTRIA and CITI from Faculty of Science and Technology , New University of Lisbon (FCTUNL); and Sagremarisco-Viveiros de Marisco Lda. Through a coordinated set of actions undertaken by these research groups, OCPortugal brings together expertise in different research areas such as marine biology, applied optics, satellite imagery, and parallel computing.
- Specific absorption coefficient of phytoplankton off the Southwest coast of the Iberian Peninsula: a contribution to algorithm development for ocean colour remote sensingPublication . Goela, Priscila; Icely, John; Cristina, Sónia; Newton, Alice; Moore, Gerald; Cordeiro, ClaraThe variability in coefficients of absorption for phytoplankton was assessed for an area off the Southwest coast of Portugal. This area included three sites at 2, 10 and 18 km perpendicular to the coast, sampled at surface, mid-Secchi and Secchi depths at each site. Phytoplankton absorption coefficients were transformed into specific coefficients (a⁎ph(λ)) by normalizing them with respect to chlorophyll a (Chla) concentrations determined by High Performance Liquid Chromatography. The influence on the variability of the absorption coefficient of phytoplankton was assessed for physico-chemical and biological parameters such as nutrients or Chla levels, as well as size structure and abundance of the phytoplankton community. The results showed that the phytoplankton absorption coefficients decreased from inshore to offshore, but were relatively constant within the water column, revealing a well-mixed column. The a⁎ph(λ) varied inversely with Chla content, with minima in Autumn and Spring, matching phytoplankton blooms. The effects of the size structure of the community and pigment composition on the variability of phytoplankton absorption coefficient were studied and results showed that size structure had a greater influence on the variability of the phytoplankton absorption, although the pigment contribution was also important.
- Standard and regional bio-optical algorithms for chlorophyll a estimates in the Atlantic off the southwestern Iberian PeninsulaPublication . Cristina, Sónia; D'Alimonte, Davide; Goela, Priscila; Kajiyama, Tamito; Icely, John; Moore, Gerald; Fragoso, Bruno; Newton, AliceThis study investigates standard and regional algal pigment index 1 (API1) estimates in the Atlantic off the southwestern Iberian Peninsula. Standard API1 data are those delivered by the Medium Resolution Imaging Spectrometer (MERIS) orbiting sensor. Equivalent quantities are computed by applying a regional inversion scheme using as input both MERIS and in situ remote sensing reflectances (R-rs). Reference data for the development of the regional algorithm and for the analysis of tested products include field measurements of total concentration of chlorophyll a (TChla) and coincident R-rs values collected at different distances from the coast. Validation results, based on matchup analysis, identifies a systematic overestimation of standard API1 versus the reference TChla values. The additional comparison of product maps in selected regions of interest confirms this tendency and demonstrates the feasibility and relevance of using regional algorithms for investigating spaceborne products. Analogous applications are hence devised for the early-stage evaluation of the forthcoming Sentinel-3/OLCI data products.
- Technical note: Algal Pigment Index 2 in the Atlantic off the southwest Iberian Peninsula: standard and regional algorithmsPublication . Goela, Priscila; Cristina, Sónia; Kajiyama, Tamito; Icely, John; Moore, Gerald; Fragoso, Bruno; Newton, AliceIn this study, Algal Pigment Index 2 (API2) is investigated in Sagres, an area located in the Atlantic off the southwestern Iberian Peninsula. Standard results provided by the MEdium Resolution Image Spectrometer (MERIS) ocean colour sensor were compared with alternative data products, determined through a regional inversion scheme, using both MERIS and in situ remote sensing reflectances (R-rs) as input data. The reference quantity for performance assessment is in situ total chlorophyll a (TChl a) concentration estimated through a phytoplankton absorption coefficient (i.e. equivalent to API2). Additional comparison of data products has also been addressed for TChl a concentration determined by high-performance liquid chromatography. The MERIS matchup analysis revealed a systematic underestimation of TChl a, which was confirmed with an independent comparison of product map analysis. The study demonstrates the importance of regional algorithms for the study area that could complement upcoming standard results of the current Sentinel-3/OLCI space mission.