The ELFIN mission

The Electron Loss and Fields Investigation with a Spatio-Temporal Ambiguity-Resolving option (ELFIN-STAR, or heretoforth simply: ELFIN) mission comprises two identical 3-Unit (3U) CubeSats on a polar (∼93∘ inclination), nearly circular, low-Earth (∼450 km altitude) orbit. Launched on September 15, 2018, ELFIN is expected to have a >2.5 year lifetime. Its primary science objective is to resolve the mechanism of storm-time relativistic electron precipitation, for which electromagnetic ion cyclotron (EMIC) waves are a prime candidate. From its ionospheric vantage point, ELFIN uses its unique pitch-angle-resolving capability to determine whether measured relativistic electron pitch-angle and energy spectra within the loss cone bear the characteristic signatures of scattering by EMIC waves or whether such scattering may be due to other processes. Pairing identical ELFIN satellites with slowly-variable along-track separation allows disambiguation of spatial and temporal evolution of the precipitation over minutes-to-tens-of-minutes timescales, faster than the orbit period of a single low-altitude satellite (Torbit ∼ 90 min). Each satellite carries an energetic particle detector for electrons (EPDE) that measures 50 keV to 5 MeV electrons with Δ E/E 1 MeV. This broad energy range of precipitation indicates that multiple waves are providing scattering concurrently. Many observed events show significant backscattered fluxes, which in the past were hard to resolve by equatorial spacecraft or non-pitch-angle-resolving ionospheric missions. These observations suggest that the ionosphere plays a significant role in modifying magnetospheric electron fluxes and wave-particle interactions. Routine data captures starting in February 2020 and lasting for at least another year, approximately the remainder of the mission lifetime, are expected to provide a very rich dataset to address questions even beyond the primary mission science objective.Published versio

Estuarine and coastal geology and geomorphology: a synthesis

Coastal geodiversity, the geological and geomorphological processes and landforms of estuaries and coasts, is of vital importance as providing not only protection from marine processes such as storm waves but also the foundations for sustaining the integrity and biodiversity of ecosystems along our shores. Since the characteristics and functioning of coastal and estuarine ecosystems are addressed in subsequent volumes of the treatise, it is important now to contextualize coastal geodiversity as a key component in our understanding of how estuaries and coasts function, be it in relation to sandy beaches, tidal mud flats, or rocky coasts and in a range of latitudes from the tropical to polar shores. This volume, thus, sets out to capture some of the wide range of coastal geodiversity and set it within a framework that will be of relevance to the subsequent volumes of this treatise. In spite of this, we are aware that not all coastal contexts are represented here, and in future editions of the treatise we intend to take the opportunity to fill any gaps identified

Estuarine and Coastal Geology and Geomorphology

[Extract] Coastal geodiversity, the geological and geomorphological processes and landforms of estuaries and coasts, is of vital importance as providing not only protection from marine processes such as storm waves but also the foundations for sustaining the integrity and biodiversity of ecosystems along our shores. Since the characteristics and functioning of coastal and estuarine ecosystems are addressed in subsequent volumes of the treatise, it is important now to contextualize coastal geodiversity as a key component in our understanding of how estuaries and coasts function, be it in relation to sandy beaches, tidal mud flats, or rocky coasts and in a range of latitudes from the tropical to polar shores. This volume, thus, sets out to capture some of the wide range of coastal geodiversity and set it within a framework that will be of relevance to the subsequent volumes of this treatise. In spite of this, we are aware that not all coastal contexts are represented here, and in future editions of the treatise we intend to take the opportunity to fill any gaps identified

Sedimentological and Rheological Properties of the Water–Solid Bed Interface in the Weser and Ems Estuaries, North Sea, Germany: Implications for Fluid Mud Classification

Fine, cohesive sediment suspensions are a common feature of estuarine environments. Generally, multilayer models are used to describe the vertical distribution of such sediments. Such conceptional models normally distinguish at least high suspended sediment concentrations (SSCs) as a topmost layer and a consolidated bed layer, often including an intermediate, fluid mud layer. Rheological, and in particular sedimentological properties are rarely included in these models. New data from two different estuaries provide new insights that can contribute toward the classification of nearbed cohesive sediments. The water–solid bed interfaces within the turbidity maximum zones of the Weser and Ems estuaries were sampled with 2–4-m-long cores. At 10-cm intervals, values of SSC, viscosity, particulate organic matter, mud: sand ratio, temperature, salinity, and grain-size distributions were determined. By normalizing these parameters to SSC and performing a cluster analysis, sediment suspensions of <20 g/L SSC, fluid mud with up to 500 g/L SSC, and an underlying cohesive/consolidated bed can each clearly be distinguished. However, changes in flow behaviour and sedimentological characteristics represented by a shift in the cluster grouping support a subdivision of the fluid mud into a low-viscosity (I) (20–200 g/L SSC) and a high-viscosity (II) (200–500 g/L SSC) layer. Furthermore, by normalizing SSC measurements, site-specific differences were observed in the rheological behaviour of the fluid mud which might be caused by differences in grain-size composition. This suggests that the widely accepted 3-layer model of vertical SSC profiles should be extended by two layers of fluid mud identified in this study

Untersuchungen zur zeitlichen und raeumlichen Variabilitaet im Wattenmeer Schlussbericht

Available from TIB Hannover: RR 8623(93-1)+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman