Ocean remote sensing techniques and applications: a review (Part II)

As discussed in the first part of this review paper, Remote Sensing (RS) systems are great tools to study various oceanographic parameters. Part I of this study described different passive and active RS systems and six applications of RS in ocean studies, including Ocean Surface Wind (OSW), Ocean Surface Current (OSC), Ocean Wave Height (OWH), Sea Level (SL), Ocean Tide (OT), and Ship Detection (SD). In Part II, the remaining nine important applications of RS systems for ocean environments, including Iceberg, Sea Ice (SI), Sea Surface temperature (SST), Ocean Surface Salinity (OSS), Ocean Color (OC), Ocean Chlorophyll (OCh), Ocean Oil Spill (OOS), Underwater Ocean, and Fishery are comprehensively reviewed and discussed. For each application, the applicable RS systems, their advantages and disadvantages, various RS and Machine Learning (ML) techniques, and several case studies are discussed.Peer ReviewedPostprint (published version

Mapping Nearshore Bathymetry with Spaceborne Data Fusion and State Space Modeling

Despite numerous techniques for measuring and estimating water depth, bathymetry in the nearshore zone is notoriously difficult to map. Dangerous sea states, noisy environmental conditions, and expensive survey operations, particularly in remote areas, contribute to the difficulties of obtaining data along the coast. Global datasets, derived mainly from satellite altimetry methods, do exist, but they have significant limitations nearshore. Numerous high-resolution datasets, conventionally acquired with acoustic and lidar techniques, also exist, but they cover only a small percentage of the world's coasts. Spaceborne data fusion employing multispectral satellite derived bathymetry (SDB) offers the potential to significantly reduce the global lack of nearshore bathymetry, coined the "white ribbon" by the hydrographic community, referring to the alongshore data gap on many nautical charts. A broad term, multispectral SDB spans a diverse spectrum of methods that have been used extensively in specific case studies, but the application of multispectral SDB on a global or regional scale is significantly limited by the availability of in situ reference depths needed to tune derived values. Additionally, many existing approaches only use a single multispectral image, which can result in significant errors or missing data if the image contains environmental or sensor noise, such as clouds, sediment plumes, or detector-edge artifacts. This dissertation presents two spaceborne empirical multispectral SDB methods to address shortcomings of existing SDB approaches and reduce the global shortage of nearshore bathymetry – (1) active/passive spaceborne data fusion combining MABEL/ICESat-2 and multispectral data and (2) state space modeling of Sentinel-2 and Landsat 8 multispectral data to generate gap-free models of relative SDB (rSDB) with corresponding uncertainty estimates. The recently launched ICESat-2 mission offers an opportunity for a completely spaceborne active-passive data fusion approach to nearshore bathymetry by potentially providing a global source of nearshore reference depths to tune empirical multispectral SDB algorithms. The main objectives of the ICESat-2 mission are to measure ice-sheet elevations, sea-ice thickness, and global biomass, but ICESat-2’s 532-nm wavelength photon-counting Advanced Topographic Laser Altimeter System (ATLAS) was first posited, then demonstrated capable of detecting bathymetry in certain nearshore environments. Presented in two studies conducted prior to ICESat-2’s launch, the active-passive approach is demonstrated with data from MABEL, NASA’s high-altitude ATLAS simulator system. The first study assessed the ability to derive bathymetry from MABEL and then evaluated the accuracy and reliability of MABEL bathymetry using data acquired in Keweenaw Bay, Lake Superior. The study also developed and verified a baseline model to predict numbers of bottom returns as a function of water depth. The second study completed the demonstration of the spaceborne active/passive data fusion method by synergistically fusing MABEL-derived bathymetry and Landsat 8 multispectral Operational Land Imager (OLI) imagery over the entire Keweenaw Bay study site using the Stumpf band-ratio algorithm. The study also assessed the spatiotemporal viability of the data fusion approach by characterizing the variability of global coastal water clarity as interpreted from Visible Infrared Imaging Radiometer Suite (VIIRS) Kd(490) data. The calculated SDB agreed with a high-resolution topobathymetric lidar dataset to within an RMSE of 0.7 m, and the spatiotemporal viability analysis indicated that the spaceborne active-passive data fusion approach may be viable over many regions of the globe throughout the course of a year. State space modeling of empirical multitemporal SDB overcomes limitations of single-image SDB by leveraging the bathymetric signal in multispectral time series to create gap-free models of relative SDB (rSDB) for an arbitrary date, enabling SDB for dates with noisy or no data. State space models (SSMs) are well established in many applications but are absent in empirical SDB literature. Consisting of a state equation, which relates consecutive state vectors, and an observation equation, which relates observations to the state vector, SSMs are typically solved using Kalman filtering techniques, which provide estimates of uncertainties along with state estimates. SSMs also provide a mechanism for data fusion by allowing an observation equation for multiple observed time series. The third study demonstrates a state space approach to empirical multispectral SDB by applying local level SSMs to Landsat 8 OLI and Sentinel-2 MSI rSDB time series, both separately and fused. A representative single-sensor SSM (Landsat 8) was transformed to SDB that agreed with a high-resolution topobathymetric lidar dataset to within an RMSE of 0.29 m, which indicates the promising performance of the state space framework. Internally consistent fused-sensor SSMs verified that state space modeling also offers a data-fusion method capable of incorporating time series from a diverse suite of multispectral sensors

Observation- and Modelling of Morphodynamics in Sandy Coastal Environments

The topic of sandy coast morphodynamics involves the mutual influences of coastal topography, local sedimentology, the driving meteorological and hydrodynamic boundary conditions, flora and fauna, and the activities of human beings: The latter as direct actors through coastal constructions and other interventions, as indirect actors through possible contributions to global change, but also as receiving agents - as living individuals confronted with the forces of the sea. The general aim of coastal research is to gain an as comprehensive as possible understanding of the different systems and their interaction in order to be able to evaluate their current state, assess their stability, explain past changes (in the geological record), and predict future developments under different conditions. Such systems dynamics involve a large bandwidth of spatial and temporal scales: from the microscopic interaction of turbulent fluid motions with single particles to meso-scale tidal dynamics of subaqueous bedforms to macro-scale seasonal adaptations of beach profiles or the meandering of tidal channels, to the mega-scale evolution of shorelines and shelf systems over decades to centuries. The process of understanding involves a continuous feedback of observations, abstractions, mathematical formulations, model development (ranging from conceptual models to mathematical formulations of processes, and to complex, process-based numerical modelling systems), and the testing of models on the basis of observations, new abstractions, and so forth. In the case of the morphodynamics of sandy coasts, the interaction of the physical processes involved in hydrodynamics, sediment dynamics, and their mutual adjustment to changing bed topographies seem most relevant, although biogeochemical processes play a (commonly underrated) additional role. This discourse presents an extended summary of the current state in the continuous process of gaining knowledge on coastal morphodynamics. It focuses on the dynamics of tidal channels and their main roughness elements: subaqueous compound bedforms. Methodological approaches involved are field measurements and numerical modelling, which are introduced and discussed

Remote Sensing of the Aquatic Environments

The book highlights recent research efforts in the monitoring of aquatic districts with remote sensing observations and proximal sensing technology integrated with laboratory measurements. Optical satellite imagery gathered at spatial resolutions down to few meters has been used for quantitative estimations of harmful algal bloom extent and Chl-a mapping, as well as winds and currents from SAR acquisitions. The knowledge and understanding gained from this book can be used for the sustainable management of bodies of water across our planet

Human Pressures and Impacts on Shallow Seafloor Environments of the Northern Baltic Sea

ABSTRACT Unsustainable use of coastal resources and space has resulted in global degradation of marine environments. Stopping adverse development requires improved understanding of how different human activities affect nature. International treaties and national legislation have been established to stop widespread environmental deterioration, but targeted local actions are still needed. Comprehensive planning processes such as marine spatial planning (MSP) and integrated coastal zone management (ICZM), promote sustainable development of coastal regions and additionally require evaluation of human influence on the marine environment. In this thesis, I examine human pressures and impacts on the shallow seafloor environments of the northern Baltic Sea. The general aim of this work is to improve the quality of location-based human pressure and impact evaluations on marine environments. The work contributes to developing environmentally conscious coastal planning by improving knowledge and introducing new methodological solutions for pressure and impact evaluations. A great variety of spatial data has been used in this work, ranging from LiDAR point clouds to species-specific monitoring data. The analysis processes in the research utilizes and combines methodologies of scenario assessments, spatial modeling and statistical examination with a geographical approach. The results of this study display the possibilities and uncertainties of detailed remote sensing data, categorized biotope data and different modeling approaches when evaluating human pressures and impacts on shallow seafloor environments. This thesis also discusses the possibilities for utilizing open source data on benthic environments and human activities to support sustainable planning decisions. The work also reveals large-scale degradation of benthic keystone species Fucus spp. in the Finnish coastal areas using modeling and species monitoring data. The main findings of this thesis provide new geographical insights on human pressure and impact evaluations that can promote sustainable planning decisions in coastal regions. KEYWORDS: human pressure, human impact, benthic communities, Baltic Sea, maarine spatial planning, coastal planning, spatial modelingTIIVISTELMÄ Rannikkoalueiden ja rannikon resurssien kestämätön käyttö on heikentänyt meriympäristöjen tilaa maailmanlaajuisesti. Kehityksen suunnan kääntäminen edellyttää luotettavaa tietoa ihmisen toiminnasta sekä sen vaikutuksista rannikoiden luontoon. Vaikka kansainväliset sopimukset ja kansalliset lait pyrkivät osaltaan estämään luonnon tilan heikkenemistä, niiden lisäksi tarvitaan paikallisia toimia. Esimerkiksi laaja-alaiset rannikoilla tehtävät suunnitteluprosessit, kuten merialuesuunnittelu (MSP) ja rannikkoalueiden yhdennetty käyttö ja hoito (ICZM), tavoittelevat kestävää kehitystä, mutta niiden tulee pohjautua luotettavaan tutkimustietoon. Tutkin väitöskirjassani ihmistoiminnan aiheuttamia paineita ja niiden vaikutuksia pohjoisen Itämeren mataliin merenpohjaympäristöihin. Tavoitteenani on parantaa näitä ympäristöjä kuvaavien alueellisten ihmistoimintaan kytkeytyvien paine- ja vaikutusarviointien laatua ja siten tukea matalien merenpohjaympäristöjen erityispiirteet huomioivaa rannikkosuunnittelua. Käytän tutkimuksissani monipuolisia paikkatietoaineistoja LiDAR –pistepilvistä yksittäisten lajien seurantaaineistoihin. Teen monen tyyppisiä maantieteellisiä analyyseja hyödyntäen ja yhdistellen erilaisia skenaariomenetelmiä, alueellisia paikkatietomalleja ja tilastollisia menetelmiä. Tutkimukseni tulokset osoittavat yhtäältä yksityiskohtaisten kaukokartoitusaineistojen, luokiteltujen biotooppiaineistojen ja erilaisten mallinnusmenetelmien arvon keskeisinä merenpohjien tilaa käsittelevän tiedon lähteinä, mutta tuovat esille myös niiden käyttöön liittyviä epävarmuuksia. Työssä tarkastelen erityisesti, miten avoimia tietolähteitä voidaan hyödyntää rannikon kestävän käytön suunnittelussa. Käytän myös mallinnusmenetelmiä ja lajitasoista seurantatietoa osoittaakseni rakkohaurujen (Fucus spp.) taantuneen laaja-alaisesti Suomen rannikkoalueilla. Väitöskirjani keskeisenä tuloksena on, että maantieteellinen lähestymistapa ja alueellinen työskentelymenetelmä vahvistavat rannikkoalueiden kestävää käyttöä ja suunnittelua tukevaa tietopohjaa. ASIASANAT: ihmistoiminnan paine, ihmistoiminnan vaikutus, merenpohjan yhteisöt, Itämeri, merialuesuunnittelu, rannikkosuunnittelu, levinneisyysmallinnu

8th Annual Jackson School of Geosciences Student Research Symposium, February 2, 2019

ConocoPhillipsGeological Science

Structural and sedimentological controls on the evolution of carbonate platforms on equatorial margins

Carbonate platforms are common features on Cenozoic Equatorial Margins. The growth and development of carbonate platforms and their associated depositional settings depend on a series of controlling factors. This thesis analyses the structural and sedimentological factors controlling four different study areas with carbonate platforms, utilising a variety of datasets. Study areas include the Vulcan Sub-Basin, Bonaparte Basin (Northwest Shelf of Australia), the Cariatiz carbonate platform in the Sorbas Basin (SE Spain), the Pernambuco Basin (Eastern Brazil), and the Pará- Maranhão Basin (Equatorial Brazil). Datasets include 2D and 3D seismic data, wellbore data, airborne LiDAR maps, outcrop maps and multispectral satellite imagery, spanning multiple scales of observation. This thesis aims to improve the current understanding of shallow- and deep-water carbonate depositional and structural settings, aiding industry and academia in prospect identification and reservoir characterisation. A comprehensive analysis of fault evolution and its relationship with the distribution of isolated carbonate platforms is investigated in the Vulcan Sub-Basin, Northwest Australia, using 3D seismic and borehole data. Detailed fault-throw measurements along arrays of normal faults were completed to generate throw- depth (T-Z) and throw-distance (T-D) profiles, as well as fault-throw maps. The results obtained were useful to determine the fault styles and timing(s) of fault initiation in the Vulcan Sub-Basin, and data were compared to the growth rates of isolated carbonate platforms (ICPs). Three types of ICPs were defined: one in which fault-throw is larger than carbonate productivity (type 1), a second type in which fault-throw is equal or lower than carbonate productivity (type 2), and ICPs where fault-throw postdates the growth of carbonate platforms (type 3). An integrated method to characterise fracture networks and their scale relationships is proposed using multi-scale datasets from the Cariatiz and Pernambuco carbonate platforms. Small fractures are obtained via detailed outcrop mapping, while intermediate-scale fractures are mapped from airborne LiDAR imagery. Large-scale fractures are measured from 3D seismic data. Geometrical and topological data are acquired to demonstrate that fracture properties behave differently depending on their size, and that particular fracture types correlate to specific scales of observation. The key result in this Chapter is that small-scale fractures strike in all directions, and are highly connected in the two study areas. However, intermediate- and large-scale fractures strike predominantly parallel to the platform margin and have lower connectivity rates than small-scale fractures. Understanding sub-seismic fracture networks is theefore critical to quantify fluid flow and permeability in carbonate reservoirs. Toward the end of this thesis, deep-water depositional settings from the Pará- Maranhão Basin, Equatorial Brazil, are studied utilising 2D and 3D seismic, borehole and multispectral satellite data to better understand platform-to-basin sedimentary processes. Neogene calciclastic submarine fans and channel-levee systems are analysed, and a comprehensive geomorphologic analysis is undertaken with the ultimate aim of finding similarities (or major contrasts) with their siliciclastic counterparts. Mixed calciclastic and siliciclastic sediment was transported from shallow waters into deep and ultra-deep waters by turbidity flows. Of importance is the confirmation that the pre-existing palaeotopography - such as terraces and gullies - was key to funnel sediment and create distinct types of channel-levee systems in Equatorial Brazil. Three types of channels are recognised: channels related to calciclastic submarine fans (type 1), low-sinuosity, aggradational channels (type 2), and high-sinuosity channels (type 3)