Search

The HYDROCOASTAL projectaims to enhance our understanding of interactions between the inland water and coastal zone, between the coastal zone and the open ocean, and the small-scale processes that govern these interactions.To achieve these aims, the HYDROCOASTAL project team has developed and implemented new SAR altimeter processing algorithms for the coastal zone and inland waters, and with these processed Sentinel 3A, 3B and Cryosat-2 data to generate an initial 2-year Test Data Set for selected regions. The performance of these new algorithms has been evaluated, by statistical analyses and comparison against in situ data. From this analysis, the best performing algorithms have been identified and implemented in a processing scheme to generate a global scale coastal zone and inland water SAR altimeter data setA series of case studies have assessed these products in terms of their scientific impacts.All the produced data sets will be available on request to external researchers, and full descriptions of the processing algorithms are available via the project web-site.The presentation will provide an overview of the project, and present key results from the coastal zone studies, which have investigated the potential scientific impact and benefits of the new data set in understanding processes in six different coastal regions, including the Severn Estuary in the UK; The German Bight, Southern Baltic and Elbe Estuary; The Venice Lagoon; The Thailand Coast; The Ebro River and Delta, and the Wadden Sea., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Because of the repeat period of the satellite altimetry missions (from 10 days for the Topex/Jason suite to more than one year for CryoSat-2), the high-frequency ocean tidal signals are aliased in the altimeter sea surface height measurements at periods that correspond to other ocean dynamics processes. To access the ocean circulation dynamics with the centimetric accuracy expected by the users, it is thus necessary to accurately remove the ocean tide signals from the altimeter measurements. With amplitudes ranging from several centimetres to several metres, the ocean tide correction is one of the largest corrections to the altimetry sea surface heights on the shelves and in coastal regions. To remove this signal, global tidal models are used, such as FES2004, GOT4.10 and FES2014. However, these models still show large errors on the continental shelves. In some regions, the errors can reach tens of centimetres, as the amplitude of the tidal signals is large and more complex to model due to non-linear interactions between the tidal waves and the shallow bathymetry. With new and future satellite altimetry techniques (SAR, wide-swath) that enable to reach ever more coastal areas, and to resolve the ocean dynamics at ever finer scales, the need for accurate coastal tidal model solutions is salient. Today, specific efforts are made to improve the tidal models in the coastal regions, thanks to high-resolution modelling and to the use of coastal observations (from altimetry and tide gauges) to constrain the models. Various models are thus available, at global and regional scales. These models are not always provided in the altimetry products, but they could be of high interest to locally improve the coastal altimetry sea surface height retrievals. In the frame of the HYDROCOASTAL project funded by the European Space Agency, NOVELTIS performed an inventory of the available and most recent global and regional tidal models that could potentially be used as corrections for coastal altimetry data. The performance of these models was compared with a specific focus on coastal and continental-shelf regions where the tidal corrections are particularly critical for coastal altimetry observations. Finally, some recommendations were made about the models that perform best depending on the regions.

Introduction HYDROCOASTAL is a two year project funded by ESA, with the objective to maximise exploitation of SAR and SARin altimeter measurements in the coastal zone and inland waters, by evaluating and implementing new approaches to process SAR and SARin data from CryoSat-2, and SAR altimeter data from Sentinel-3A and Sentinel-3B. Optical data from Sentinel-2 MSI and Sentinel-3 OLCI instruments will also be used in generating River Discharge products. New SAR and SARin processing algorithms for the coastal zone and inland waters will be developed and implemented and evaluated through an initial Test Data Set for selected regions. From the results of this evaluation a processing scheme will be implemented to generate global coastal zone and river discharge data sets. A series of case studies will assess these products in terms of their scientific impacts. All the produced data sets will be available on request to external researchers, and full descriptions of the processing algorithms will be provided Objectives The scientific objectives of HYDROCOASTAL are to enhance our understanding of interactions between the inland water and coastal zone, between the coastal zone and the open ocean, and the small scale processes that govern these interactions. Also the project aims to improve our capability to characterize the variation at different time scales of inland water storage, exchanges with the ocean and the impact on regional sea-level changes The technical objectives are to develop and evaluate new SAR and SARin altimetry processing techniques in support of the scientific objectives, including stack processing, and filtering, and retracking. Also an improved Wet Troposphere Correction will be developed and evaluated. Presentation The presentation will describe the different SAR altimeter processing algorithms that are being evaluated in the first phase of the project, and present results from the evaluation of the initial test data set focusing on performance at the coast.

Madagascar currently has very limited tidal prediction capability (based primarily on model data) and no national sea level monitoring capability. There is only one functioning tide gauge station, whilst an earlier tide gauge, in the cyclone-prone north of the island, was swept away several years ago. Working closely with its Madagascar partners, the Direction Générale de la Météorologie (DGM), PASS-SWIO aims to establish a sea level monitoring system for Madagascar based on the deployment of a low-cost relocatable tide gauge (Portagauge). Financial limitations make it impractical for Madagascar to install multiple tide gauge stations at all points of interest along their extensive coastlines, nor can they be maintained on the multi-decadal timescales that are required to derive robust estimates of long-term sea level trends. Yet, tidal information is vital for the safety of communities, infrastructure and commerce, and since short-term hazards can be exacerbated by long-term increases in sea level, knowledge of longer-term changes is also essential. Fortunately, longer-term sea level variability, including the trends associated with Climate Change, can be derived from satellite altimetry data, but these ‘absolute’ sea level measurements are calculated relative to an ellipsoidal reference frame and require both correction for vertical land motion as well as ‘ground-truthing’ to some known fixed point on land if they are to be meaningful for planning and mitigation purposes. Such vertical land motion is traditionally measured by GNSS receivers via the detection of positioning and timing information from a constellation of navigational satellites. The recent GNSS-IR technique exploiting the signal-to-noise ratio, allows sea level to be inferred relative to the same geodetic reference frame as satellite altimetry. The co-location of GNSS receivers with conventional tide gauge sensors (which measure relative to some fixed point on land), thus allows short-term tide gauge and GNSS-IR measurements to be connected to satellite altimetry, which can then substitute for long-term observations from tide gauge data. The NOC Portagauge is a low-cost system which uses GNSS interferometric reflectometry (GNSS-IR) technology alongside a conventional radar gauge. As part of the PASS-SWIO project a Portagauge will be deployed at Toamasina port on the NE coast of Madagascar, for a minimum period of 6 months. DGM will be trained to maintain and operate the Portagauge, and to carry out processing and analysis of Portagauge, tide gauge and satellite altimeter data (Jason-2, Jason-3, Sentinel-3A and 3B). They will cross validate portagauge data against satellite data and generate an analysis of tidal and non-tidal sea-level characteristics for the Madagascar coastal region, including seasonal signals, inter-annual variability and trends. Finally, the PASS-SWIO team will work with agencies and key users in Madagascar to define a road map to establish a long-term, sustainable, national sea-level monitoring system for the country. It will be important to ensure that the planned capacity development meets key requirements, complements existing capability and will be sustainable, considering resource requirements. The end goal of the project is to provide a model for a sea level monitoring system for developing island states and coastal nations, based on low-cost tide gauges and satellite data. The presentation will provide an overview of the project and present initial results from analysis of satellite altimeter data in the Madagascar region. PASS-SWIO is funded by ESA under the EO Science for Society Programme – Open Call.

Fully focused processing of SAR altimeter data provides opportunities for exciting new applications, as it provides hitherto unachievable along-track resolution of up to 50 cm contrasting the regular 20 Hz processing resolution of 200 meters. The results presented here, relate to the FFSAR-Coastal Project*, where the SMAP Fully Focused SAR (FFSAR) altimetry processor has been applied to Sentinel-3A and Sentinel-3B data in the Severn Estuary in order to evaluate the potential of FFSAR altimeter data to make a significant new contribution to coastal and estuarine monitoring systems. Because of the large tidal signals in the Bristol Channel and Severn Estuary and the huge tidal flats, the Sentinel-3 satellites sometimes fly over the river during low tide, where, instead of measuring the sea surface height, it measures the seabed heights or bathymetry. These measurements could be extremely valuable for different modelling purposes, such as tidal modelling, as in-situ measurements of the Severn bathymetry are scarce due to challenges linked to the large tidal range (up to 14 m occurring twice a day) and the muddy nature of the intertidal sediment. The FFSAR processing of the Sentinel-3 data shows a very clear bathymetry signal and the FFSAR-Coastal project aims to evaluate these measurements. As the Sentinel-3 satellites have an orbital drift reaching 1 km it rarely flies over the exact same location on the ground. Consequently, it is hard to evaluate the performance by comparing tracks at different times. Therefore, bathymetry data from other sources must be considered to account for this drift in the orbit. Several bathymetry products covering the Severn can be obtained from the National Network of Regional Coastal Monitoring Programmes of England (www.coastalmonitoring.org) and from the UKHO (https://seabed.admiralty.co.uk). These products are compared to the bathymetry derived from the Sentinel-3 FFSAR outputs to see if Sentinel-3 is in fact tracking the heights from the nadir position. Additionally, photon data from NASA’s ICESat-2 mission will be used as reference data, since these are available at a very high resolution and with very high precision and accuracy. Combining ICESat-2 and Sentinel-3 FFSAR data would make it possible to map large parts of the Severn. The benefit of ICESat-2 is the resolution and the use of 6 beams which provides great mapping opportunities, and the contribution from Sentinel-3 is the 27-day repeat period with a slight drift. Combined, there is a very good potential for mapping the Severn bathymetry, aiding the local authorities in computing tidal and flood forecasts. *FFSAR-Coastal is funded by ESA under the EO Science for Society Programme – Open Call.

Introduction HYDROCOASTAL is a two year project funded by ESA, with the objective to maximise exploitation of SAR and SARin altimeter measurements in the coastal zone and inland waters, by evaluating and implementing new approaches to process SAR and SARin data from CryoSat-2, and SAR altimeter data from Sentinel-3A and Sentinel-3B. Optical data from Sentinel-2 MSI and Sentinel-3 OLCI instruments will also be used in generating River Discharge products. New SAR and SARin processing algorithms for the coastal zone and inland waters will be developed and implemented and evaluated through an initial Test Data Set for selected regions. From the results of this evaluation a processing scheme will be implemented to generate global coastal zone and river discharge data sets. A series of case studies will assess these products in terms of their scientific impacts. All the produced data sets will be available on request to external researchers, and full descriptions of the processing algorithms will be provided Objectives The scientific objectives of HYDROCOASTAL are to enhance our understanding of interactions between the inland water and coastal zone, between the coastal zone and the open ocean, and the small scale processes that govern these interactions. Also the project aims to improve our capability to characterize the variation at different time scales of inland water storage, exchanges with the ocean and the impact on regional sea-level changes The technical objectives are to develop and evaluate new SAR and SARin altimetry processing techniques in support of the scientific objectives, including stack processing, and filtering, and retracking. Also an improved Wet Troposphere Correction will be developed and evaluated. Presentation The presentation will describe the different SAR altimeter processing algorithms that are being evaluated in the first phase of the project, and present results from the evaluation of the initial test data set. It will focus particularly on the performance of the new algorithms over inland water.

University of Technology Sydney. Faculty of Engineering and Information Technology. Radio resource management in device-to-device cellular offload can be optimised to increase network capacity, quality of service, energy efficiency, lower latency and provide more resilient networks. However, this resource optimisation problem is both NP-Hard and required to operate at a millisecond timescale, limiting feasible solutions. In this thesis, we investigate how deep reinforcement learning can be applied to improve resource allocation. To empirically demonstrate our approach, we develop a network simulator for device-to-device cellular offload research. We also introduce an improved self-play algorithm for training reinforcement learning without expert guidance. We apply our self-play training algorithm to the game Connect Four. Leveraging the competitive pressures of coevolution, we improve the performance of agents trained with our method, achieving a 15% higher win rate. Furthermore, agents exhibit more stable training dynamics and suffer fewer performance regressions. We evaluate our network simulator and demonstrate deep reinforcement learning can significantly increase network capacity. Our network simulator reduces research friction and provides an evaluation platform to compare, share and build upon results. Our toolkit is provided to other researchers as open-source software.

Introduction The recently developed technique of “fully focused” processing of SAR altimeter data provides opportunities for exciting new applications, as it provides hitherto unachievable along-track resolution of up to (and in some cases less than) tens of metres. The objective of the FFSAR-Coastal Project is to apply the SMAP Fully Focused SAR (FFSAR) altimetry processor on Sentinel-3A and Sentinel 3B data and evaluate the potential of FFSAR altimeter data to make a significant new contribution to coastal and estuarine monitoring systems. Two different environments are being considered: • The Severn Estuary and river: A highly dynamic mixed tidal estuary environment, the confluence between a river and its estuary experiencing large tidal range and strong tidal currents. • The lower Rhone Delta and Camargue: A low lying, flat river delta and wetland environment, susceptible to inundation and rising water levels. By studying these two very different environments, the potential applicability and benefits offered by FF SAR altimeter data in other coastal, estuarine and delta locations will be demonstrated. Innovative in situ lidar water level gauges, provided by vortex.io will be used for validation. FFSAR-Coastal is funded by ESA under the EO Science for Society Programme – Open Call. Presentation The presentation will provide an overview of the FFSAR Coastal project and present early results. There are two main elements to the project. DTU Space are using the SMAP (Standalone Multi-Mission Altimetry Processor), developed by CLS, and applying it to Sentinel 3A and 3B altimeter data for two regions with very different characteristics: the Severn estuary in the UK, and the Rhône delta in France. The objective is to evaluate how well FFSAR altimeter data can resolve fine scale features in these two different environments. Initial results will be used to identify the optimum processing choices, which will then be applied to generate time series of data for selected tracks. These data will be validated against in-situ data and models, to quantify the performance against other data sources. Further analysis will then investigate the capability of FFSAR altimeter data to capture small scale physical signals (surface gradients, currents, roughness signatures) in highly tidal regions and to detect and measure tidal asymmetry/gradients across estuaries not seen with conventional altimetry For the Rhône delta the analysis will focus on the ability of FFSAR data to accurately map different low lying channels and filaments. The second element is the deployment of innovative river level “micro-gauges” (vorteX.io microstations) to provide ground truth data, and to test these as a flexible and low-cost option for satellite validation and river monitoring. Two micro-gauges will be installed in each of the selected regions, as close as possible to the Sentinel 3A and 3B ground tracks, and drone campaigns with an embedded LiDAR altimeter will be carried out to provide high resolution sea level measurements, synchronised to satellite overpasses, to provide a water level profile between the micro-gauge location and the satellite ground track. The project is also engaging with local user groups to identify key gaps in the existing monitoring systems, and to develop recommendations on how FFSAR altimeter data can best be used as part of

An arms race in the last decade between computing performance and power-reduction has led to accelerated progress in both hardware and software, provisioning fast, efficient algorithms and small, capable, low-power hardware devices. Meanwhile, small satellites have become increasingly important in defense and commercial missions, due to their low resource consumption in terms of power, space, and cost. Improvements in computer vision algorithms and commercial off-the-shelf (COTS) edge computing introduce a means of addressing challenges posed for spacecraft in the realm of autonomy and perception. The University of Georgia’s Small Satellite Research Laboratory has been working to address these obstacles in developing an interface to merge Graphics Processing Unit (GPU) computations into the standard PC104+ satellite stack. This paper presents the Core GPU Interface (CORGI), a hardware solution which integrates the NVIDIA Jetson TX2/TX2i module into the cube satellite stack. The CORGI can be used as a standalone flight computer or as a co-processor with a designated onboard computer (OBC). This board will fly on the Multi-view Onboard Computational Imager (MOCI), a 6U satellite scheduled for launch into low earth orbit (LEO) in 2022, and will serve NASA and the Air Force Research Laboratories’ (AFRL) efforts to demonstrate autonomy and high-performance computing on small satellites. The CORGI provides input/output capability for command and telemetry and development interfaces for increased usability, specifically DisplayPort and two USB 3.0 type-A interfaces. Additionally, a UART umbilical provides an interface between an off-PCB computer through the PC104+ stack, enabling the TX2i to be externally triggered for science data handoff by a radiation-tolerant onboard computer. The CORGI is designed as a payload processor, and thus utilizes the TX2i module’s USB 3.0 hub to connect one or more satellite imagers over USB. The CORGI provides other standard development access points, including general-purpose input-output (GPIOs), from both the designated onboard computer and TX2i module. Standard headers also provide a means of testing the TX2i line voltages for discharge monitoring and power status. An SD card provides flash memory for logging science data and telemetry. This paper presents 1) PCB design and manufacturing specifications to assist teams in designing hardware for space applications. 2) Spice simulations to validate power management circuit design and evaluation for relevant cases. 3) Electrical test results demonstrate the nominal operation of both power management and regulation circuitry and the validation of correct discharge behavior during a power outage. 4) We present tests that demonstrate CORGI’s operation and performance characteristics under load.