Conference Agenda

ReSCCoME addresses research and development activities that focus on the way, in which the rapidly increasing amount of high-resolution EO data can be used for the surveillance of marine coastal environments, and how EO sensors can detect and quantify processes and phenomena that are crucial for the local fauna and flora, for coastal residents and local authorities. During the first project phase, we focussed on the SAR monitoring of exposed intertidal flats, of nonlinear oceanic internal waves, and of offshore wind installations near the coast.

SAR data acquired from intertidal flats are being used to assess their economic use through intensive aquacultures and to identify areas of strong morphodynamics. Polarimetric decomposition of Gaofen-3 SAR data of various spots on the Chinese coast revealed that aquacultural rafts show different backscattering mechanisms than the surrounding mud flats. Moreover, Sentinel-1 SAR-C data are used to generate topographic maps of extended intertidal flats on the German North Sea coast. Those maps, derived for different time periods, will be used to assess morphodynamic changes.

Nonlinear internal waves (NLIW) around Hainan Island in the South China Sea play a critical role in local mixing, thermohaline circulation and nearshore ecosystem. However, the generation of NLIWs around Hainan Island are rarely studied. We have been investigating the source sites and generation mechanisms of NLIWs around Hainan Island based on the synergistic analysis of SAR observations, field measurements and numerical analyses. It is found that the NLIWs in different regions around Hainan Island have different generation regimes.

Offshore wind installations in the South China Sea near the coast, which trigger a new demand for studying the effects of horizontal wind speed gradients and the wind power variation within the coastal zone. We have retrieved wind maps at 10 m height from Sentinel-1 SAR-C and Envisat ASAR observations and found that generally, the speed of the prevailing south-easterly winds and wind power declined by about 8% and 22%, respectively.

Apart from the various ongoing research activities, efforts have been undertaken to stimulate the exchange of Young Scientists and to educate them through dedicated Summer Schools. The efforts, however, were strongly affected by the ongoing pandemic.

The project aims at exploiting microwave satellite measurements to generate innovative added-value products to observe coastal areas characterized by harsh environments, even under extreme weather conditions. The following added-values products are addressed: water pollution, coast classification and erosion monitoring, ship and metallic target observation, typhoon monitoring.

Up to the mid-term deadline the following activities have been addressed:

Water pollution: Theoretical scattering models (under monostatic and bistatic configurations) have been developed to predict sea surface scattering with or without surfactants. In the monostatic case, theoretical predictions have been contrasted with actual measurements collected by the Synthetic Aperture Radar.

Target detection: Multi-polarization backscattering from a known ship observed at different incidence angles. The analysis is carried on using metrics based on both power and phase information.

Extreme weather events: SAR and ancillary scatterometer and model-based information are used to estimate the wind vector from SAR scenes under moderate and extreme weather conditions.

All this matter will be detailed in the proposed piece of study.

The Earth's surface waters are a fundamental resource and encompass a broad range of ecosystems that are core to global biogeochemical cycling and food and energy production. The mounting and conflicting pressures from the number of users and uses, coupled with population growth, industrialisation, land use intensification and climate change bring into focus the urgent need for the sustainable management of our aquatic resources and space. The last decades are witnessing a revolution in Earth observation (EO) capabilities for characterising coastal and inland water dynamics through the Copernicus programme of satellite missions (Sentinel 1/2/3) and Chinese Earth observation missions (e.g. from HY-1). The increasing monitoring capabilities are now extending satellite applications to near-shore and transitional systems such as lagoons and estuaries.

Our project aims to develop and validate innovative products for transitional and coastal waters to support and improve the water ecosystem services, sustainable management and security. It is widely recognised that the successful uptake of new Earth observation (EO) products and services is predicated by reliable and robust calibration and validation activities. Inland, transitional and near-shore coastal waters are spatially and temporally heterogeneous regarding their optical properties. It is further widely recognised within the EO and user communities, that there exists a significant lack in high quality data for calibration, validation, and uncertainty assessment. As part of the H2020 CoastObs, CERTO, NSFC and CAS projects, dedicated effort was made to collect high quality in-situ data from coastal and transitional ecosystems, including ria de Vigo, lagoons in the Danube Delta, Taihu Lake, Yuqiao Reservoir, and Danjiangkou Reservoir. The collection of new in-situ data has been challenged by the Covid-19 related travel restrictions and cruise operation difficulties in the Black Sea, which is one of our case study areas. Nevertheless, during this reporting period in-situ data were collected in the Razelm-Sinoe lagoon system,rivers and transitional waters in Hainan Island and Yantai coastal region in Shandong Peninsula coast in 2021 and 2022. Typically, the in-situ data collected included above-water Remote Sensing reflectance (Rrs), Inherent optical properties (absorption, scattering, attenuation, backscatter), chloroplastic pigments, suspended sediments (inorganic, total), coloured dissolved organic material, suspended particles composition, primary production, and size fractionated pigments. Radiometric data collected here were used in the Atmospheric Correction Intercomparison Exercise (ACIX-Aqua), a joint NASA – ESA activity (Pahlevan et al. 2021). Detection algorithms and products for Harmful Algal Blooms (HABs) products were developed based on Sentinel-3 OLCI, HY-1C and ground-based multispectral remote sensing images respectively. HABs detected by Sentinel-3 OLCI included a regional neural network model for the retrieval of chlorophyll-a concentration and innovative species indicators based on machine learning methods (i.e. support vector machines) for Pseudo-nitzschia spp. and Alexandrium minutum. According to the validation results, Pseudo-nitzschia spp. products are quite robust and reliable, detecting over 90 % of the blooms with a false alarm rate around 10 %. A manuscript on the detection of Pseudo-nitzschia spp. has been submitted. HABs detected by HY-1C investigated the ultraviolet (UV) reflection spectra of floating cyanobacteria blooms and identified that the blooms have significant UV reflection features associated with the floating status. HABs detected by ground-based multispectral remote sensing represent a new technical method to dynamically monitoring cyanobacteria blooms which can operate under cloud cover and can provide accurate and continuous spatiotemporal patterns of the blooms. Two articles have been published in regards to the detection of HABs (Suo et al., 2021; Zhao et al., 2021). For the marine oil spills (MOS), a new lab-derived HSV colour model was proposed for the optical quantification of oil emulsions using multi-band coarse-resolution imagery and one article has been published (Jiao et al., 2021). Other relevant work during this reporting period included the development of a meta-classification framework (Werther et al. 2021) to assess the trophic status of nearshore and inland waters, and development of water clarity products for Taihu Lake (Yin et al., 2021), Yangtze River (Zhao et al., 2021) and lakes across Sri Lanka (Somasundaram et al., 2021). These will provide the basis the estimation of phytoplankton size classes and the primary production in transitional systems. We also worked on the development of new frameworks for optical conditions found in transitional systems. In-situ data of biogeochemical and inherent optical properties were used to characterise the relationships among optical clusters in inland, coastal, and transitional systems. We provide new information on the optics in these systems, which is important for optical models and remote sensing of coastal and transitional waters.