ABSTRACT. Adriatic Sea and North Ionian are two interacting basins showing specific oceanographic patterns, resulting in quite prominent seasonal, interannual and decadal variability of the phytoplankton community features. Therefore, the use of ocean color data is rather important for understanding both ecosystem functioning and oceanographic features in the two areas. The South Adriatic Pit is characterized by a presence of the quasi-permanent cyclonic gyre, whose center is the site of the winter vertical mixing and the dense water formation. The vertical mixing is triggered by outbreaks of the cold continental air. This water represents then the main component of the bottom water of the entire Eastern Mediterranean. The vertical mixing brings to the surface deep nutrient-rich waters and triggers the spring phytoplankton bloom. The high chlorophyll concentration, on one hand enables to study the characteristics of the vertically mixed patch, and on the other hand, to quantify interannual and decadal variability of the phytoplankton biomass. Combining the satellite measurements with in situ data, provides rather complete information on the South Adriatic ecosystem. In the North Ionian, circulation is dominated by a basin-scale meander, which changes on a decadal time-scale from cyclonic to anticyclonic and viceversa, affecting nutrient distribution and nutricline depth. North Ionian is then a good study area to investigate how changes in circulation can affect phytoplankton phenology in oligotrophic regions. From in situ observations, the average distribution of isopycnals was produced for each circulation regime and a nutricline depth difference between cyclonic and anticyclonic circulation modes of about 80 m was estimated. The phytoplankton phenology metrics extracted from annual time-series of ocean color data for the period 1998-2012, associated with the two circulation regimes were compared. Results showed that the metric the most affected by circulation reversals is the initiation date for the main increase in chlorophyll-a.
BIO. Dr. Miroslav GACIC, is a Physical Oceanographer at the Istituto Nazionale di Oceanografia e di Geofisica Sperimentale – OGS, Trieste (Italy) and former Head of the Oceanography Group. His main research interests and activities have been focused on the Adriatic Sea and have been related to: a) the deep water formation processes and their influence on the nutrient input into the euphotic zone, b) the thermohaline circulation inside the basin and its inter-annual and decadal variability, c) the response of the basin to atmospheric forcing on various time scales, and d) water exchange between semi-enclosed bays and seas, and adjacent basins. Important aspect of his activity has been oriented towards the inter-annual and decadal variability of the Adriatic thermohaline properties and interaction with the Eastern Mediterranean. He was Chair of the Committee of Climate and Physics of the Sea of CIESM for eight years and a member of the International Scientific Steering Committee of the HyMeX project. He acted as Guest Editor of two special issue of Journal of Marine Systems and he was involved as Guest Editor of the special issue of the Continental Shelf Research dedicated to the South Adriatic. He produced as editor and co-author the book “Physical Oceanography of the Adriatic Sea”. He co-authored about 120 peer-reviewed publications in international journals or books. He has been teaching Physical Oceanography course in the Ph.D. program and the Diploma Course at the International Centre of Theoretical Physics. He has been acting as a reviewer of a number of submitted papers to international journals.
ABSTRACT. Radiative transfer (RT) approximations relating remote sensing reflectance to bb/(a + bb) have been tremendously useful to the ocean color community for decades. Current algorithms to account for bidirectional reflectance distribution function (BRDF) effects in the proportionality (e.g., Morel et al. 2002; Lee et al. 2011) have relied on assumptions about angular scattering by particle fields because measurements of oceanic particle volume scattering functions (VSFs) have been historically lacking. Such assumptions are impactful, as the BRDF is effectively controlled by the VSF. We now have an increasing database of VSF measurements over the last 10 years with which we can assess other algorithm approaches where the VSF is explicitly represented. Related work has culminated in a fully analytical algorithm based on the RT approximation of Zaneveld (1995) with performance effectively equivalent to full RT simulations with Hydrolight when a constant VSF shape derived from our extensive measurements is assumed in the backward direction. The unknown inputs are absorption and backscattering, as with the conventional bb/(a + bb) relationship, so similar approaches to inversion can be directly applied. The algorithm shows improved performance relative to current state-of-the-art look-up table (LUT) based BRDF algorithms, i.e., Morel et al. (2002) and Lee et al. (2011). As a result, the algorithm shows good potential for future ocean color inversion with low bias, well-constrained uncertainties (including the VSF), and explicit terms that can be readily tuned.
BIO. Dr. Michael Twardowski is a Research Professor at Harbor Branch Oceanographic Institute, Ft. Pierce, FL, USA, and leads the Marine and Environmental Sensing Program of the I-SENSE pillar at Florida Atlantic University. Mike also holds an Affiliate Professor position in Ocean Engineering at FAU. Before joining HBOI in 2015 he was Director of Research at WET Labs, Inc., where he led development of optical sensors and application of technology to problems in ocean optics. Mike has over 70 peer-reviewed publications on a wide range of topics including remote sensing of optical and biogeochemical properties, ocean color validation, inversion of optical properties to characterize ocean particles and dissolved materials, holographic imaging microscopy, biological camouflage, autonomous monitoring, technology development and protocols for optical sensors. Mike is on the science team for the NASA PACE mission, where he is working on updating concepts for ocean color algorithms and improving accuracy for optical property measurements. His other research activities are currently focused on active sensing with lidar, particle field dynamics, harmful algal blooms, exploring the mesopelagic ocean, and developing new technology. Mike received his PhD in Oceanography from the Graduate School of Oceanography, University of Rhode Island in 1998. He enjoys music and high stakes shuffleboard since moving to Florida. Mike can be reached at firstname.lastname@example.org.
ABSTRACT. The Mediterranean Sea has been considered for a long time to be “bio-optically anomalous”, so that standard ocean color algorithms fail to provide correct estimates of chlorophyll a concentrations over this oceanic area. Such anomalies imply that bio-optical relationships linking the inherent optical properties (absorption and scattering) of the various substances to chlorophyll a concentrations deviate from the average relationships observed in the world ocean. Since the mid-90’s, several studies based on in situ (or satellite) measurements were performed to address this question, and different possible causes were invoked (presence of coccolithophores, influence of desert dust, excess of colored dissolved organic matter…or a combination of these factors). There has been, however, no clear consensus on the origins of these bio-optical anomalies. In addition, the impact of possible specificities in algal community composition (pigments or size structure), has not been well documented. Recently, large in situ datasets have become available with the deployment of Biogeochemical-Argo profiling floats, and with recent cruises such as the PEACETIME cruise. These recent datasets, as well as the compilation of absorption data gathered during numerous cruises since the 90’s, provide new insights into bio-optical anomalies in the Med Sea.
BIO. Annick Bricaud is a CNRS senior research scientist at the “Marine Optics, Remote Sensing and Biogeochemical Applications” group of the Laboratoire d’Océanographie de Villefranche (LOV) in Villefranche-sur-Mer, France. She received an Engineering Degree in Marseille in 1975, a Doctorate degree in Oceanography from the Université Pierre and Marie Curie (Paris-6) in 1979, and a “Doctorat d’Etat” from the same University in 1989. She has been in charge of the Marine Optics group of her lab from 1996 to 2000. Her research field includes experimental and theoretical studies of inherent optical properties (absorption and scattering) of phytoplankton, non-algal particles, and colored dissolved organic matter, in situ optical properties of oceanic waters, ocean color algorithms, and spatial/temporal variations of space-derived products at regional and basin scales. In the last years, she focused her activity on the estimation of phytoplankton dominant size from ocean color data, on the analysis of bio-optical data from profiling floats, and on the study of bio-optical anomalies (particularly in the Arctic Ocean). She has published 73 papers in refereed international journals (35 as first or second author). She has been a member of the Mission Group of CNES for POLDER-1 (1993-1998), of the Science Advisory Group of ESA for MERIS (1993-2007), of the Conseil National des Universités at Université Paris-6 (2003-2011), and of several committees for French national programmes. She has been an associate Editor of the journal Biogeosciences from 2007 to 2015, and a member of the TOSCA-Océan Scientific Committee of CNES since 2010.
ABSTRACT. Dr. Ved Chirayath’s plenary presentation will highlight two instrument technologies he invented at NASA including Fluid Lensing, the first remote sensing technology capable of imaging through ocean waves in 3D at sub-cm resolutions, and MiDAR, a next-generation active hyperspectral remote sensing and optical communications instrument. Fluid Lensing has been used to provide the first 3D multispectral imagery of shallow marine systems from unmanned aerial vehicles (UAVs, or drones), including coral reefs in American Samoa and stromatolite reefs in Hamelin Pool, Western Australia. MiDAR is being deployed on aircraft, and underwater remotely operated vehicles (ROVs) as a new method to remotely sense living and nonliving structures in extreme environments. MiDAR images targets with high-intensity narrowband structured optical radiation to measure an object’s non-linear spectral reflectance, image through fluid interfaces such as ocean waves with active fluid lensing, and simultaneously transmit high-bandwidth data. As an active instrument, MiDAR is capable of remotely sensing reflectance at the centimeter (cm) spatial scale with a signal-to-noise ratio (SNR) multiple orders of magnitude higher than passive airborne and spaceborne remote sensing systems with significantly reduced integration time. This allows for rapid video-frame-rate hyperspectral sensing into the far ultraviolet and VNIR wavelengths. Finally, Chirayath will present preliminary results from NASA NeMO-Net, the first neural network for global coral reef classification using fluid lensing and MiDAR.
BIO. Dr. Ved Chirayath directs the Laboratory for Advanced Sensing (LAS) in the Earth Science Division at NASA Ames Silicon Valley. His research is directed at inventing next-generation advanced sensing technologies for NASA’s Earth Science Program to better understand the natural world around us, extending our capabilities for studying life in extreme environments on Earth, and searching for life elsewhere in the universe. He leads a multi-disciplinary team developing new instrumentation for airborne and spaceborne remote sensing, validates instrumentation through scientific field campaigns around the world, and develops machine learning algorithms to process big data on NASA’s supercomputing facility. Dr. Chirayath invented the fluid lensing algorithm and is PI of the NASA FluidCam instrument. He is also the inventor of the MiDAR system for active multispectral remote sensing and PI of the MiDAR instrument. Currently, he is developing and validating these technologies through airborne and underwater field campaigns. Recently, Dr. Chirayath’s NeMO-Net project was selected by NASA ESTO AIST to create the world’s largest neural network for global coral reef assessment using data fusion of fluid lensing data to augment other airborne and spaceborne remote sensing instruments. In addition, Dr. Chirayath is the chair of NASA Ames’ Lesbian, Gay, Bisexual, and Transgender (LGBT) Advisory Group and is a Special Emphasis Program Manager for NASA HQ’s Office of Diversity and Equal Opportunity. In 2016, Dr. Chirayath received the NASA Equal Employment Opportunity Medal. In 2017, Dr. Chirayath received the NASA Early Career Award. Dr. Chirayath received his PhD and MSc from Stanford University’s Department of Aeronautics & Astronautics and his BSc with Honors in Physics and Astrophysics from Stanford University and Moscow State University. Full profile » https://earthscience.arc.nasa.gov/sg/person/Dr_Ved_Chirayath.
ABSTRACT. Ocean color products are routinely used for the initialization, development and validation of regional to global scale ocean and climate models. In particular, novel satellite estimates of phytoplankton community composition and carbon cycle processes are commonly used to validate simulated marine ecosystem services related to global biogeochemical cycling and climate support. Yet, significant uncertainties remain with respect to the representation of biological and biogeochemical processes in climate models. Here, we discuss recent efforts to better constrain present and future marine ecosystem structure and biogeochemical function based on the analysis of satellite algorithms, mechanistic models, carbon biomass data and HPLC pigment concentrations, and presence-absence observations. We show that estimates of diatom biomass, NPP, silicate production and export differ substantially between observational data products, and that they are dependent on the ecological niche structure and seasonal dynamics of biomass-rich diatom species pertaining to multiple genera. We use species distribution models to extrapolate in situ observations of plankton biomass and diversity to the global scale, and ecological niche analysis to identify the physical and biogeochemical drivers of phyto- and zooplankton biogeography. We show that the habitat suitability patterns of thousands of phytoplankton species can be used to define marine ecoregions with distinct biogeochemical and physical properties, as well as biodiversity patterns, thus linking properties readily observable from space with biological in situ observations. We subsequently highlight challenges associated with the use of ocean color products in global climate applications, and discuss potential future avenues to improve and better integrate different data streams.
BIO. Dr. Meike Vogt is a marine ecosystem modeler and biogeochemist with a PhD from the University of East Anglia, Norwich, UK. Since 2010 she is a senior researcher in the Environmental Physics Group at ETH Zurich, Switzerland. Meike Vogt is interested in the link between marine ecosystem composition, ecosystem function and ecosystem services related to global biogeochemical cycles and climate support using in situ observations, statistical and mechanistic modeling approaches. She was the co-coordinator of the MARine Ecosystem DATa (MAREDAT) initiative that compiled the first global atlas of plankton functional type biomass across multiple taxa, and she is a member of the scientific steering committee of the MARine Ecosystem Model Inter-comparison Project (MAREMIP) that aims at the improvement of biological processes in current state-of-the-art marine ecosystem models used in future climate projections and the IPCC process.