Microwave satellite remote sensing for a sustainable sea

The oceans cover roughly 2/3 of the Earth’s surface and are a fundamental ecosystem regulating climate, weather and representing a huge reservoir of biodiversity and natural resources. The preservation of the oceans is therefore not only relevant on an environmental perspective but also on an economical one. A sustainable approach is requested that cannot be simply achieved by improving technologies but calls for a shared new vision of common goods.Within such a complex and holistic problem, the role of satellite microwave remote sensing to observe marine ecosystem and to assist a sustainable development of human activities must be considered. In such a view the paper is meant. Accordingly, the key microwave sensor technologies are reviewed paying particular emphasis on those applications that can provide effective support to pursue some of the UN Sustainable Development Goals. Three meaningful sectors are showcased:oil and gas, where microwave sensors can provide continuous fine-resolution monitoring of critical infrastructures; renewable energy, where microwave satellite remote sensing allows supporting the management of offshore wind farms during both feasibility and operational stages; plastic pollution, where microwave technologies that exploit signals of opportunity offer large-scale monitoring capability to provide marine litter maps of the oceans

Relationship between surface temperatures and seismic activity at Vulcano, Aeolian Island (Italy)

Time-series acquired during last years by surface monitoring parameters are compared, and the results are discussed, following a theoretical approach. Surface parameters are fluid temperature, soil temperatures and seismic activity at La Fossa of Vulcano. Discussed periods are 1998 and from 2004 to 2007, when time relationship between changes of the heat flow from the ground and seismic activity, resulted worth noting. Earthquakes originating in the area of Vulcano are associated with both fracturing and degassing mechanisms. The formers are related to the activity of tectonic structures; while the latter are connected to fluid dynamics within the interior of the volcanic apparatus. In November 1998 seismic activity at La Fossa sharply increased: Five events were registered, with seismic signals of typical faulting earthquakes, triggered by mechanism of shear fracturing and focal depths ranging 1-4 km. Fumaroles temperatures, recorded by continuous monitoring system of INGV - Palermo, showed a growing trend since October to November 1998, highlighting a big increase of heat transfer during the period, and also the soil temperature, out of the fumaroles field showed a marked increase. Fumaroles temperatures heralded the increase of heat and energy flow during a pre-seismic period of about 1 month. The transient variation of surface release reflect an excited state of the system and may have many different causes, not directly related to the magma. Indeed, stress drops generated by small fracturing earthquakes, introduce a significant perturbation in the system resulting in a relevant production of mass and energy flow. Until these flows counteract every stress gradient, they support stationary state of the system. The observed time relationships only allow a qualitative discussion about cause and effects, but doesn’t allow any quantitative evaluation. Pressure transients generate anomalies (flows of matter, differential in heat flows, chemical reaction rates) whose time frame is specific, depending on many possible processes and path-ways. Fluid phases, along fumarolic conduits, reach the surface faster than the co-genetic earthquake, as the earthquake is embedded in a strain transient that broadly exceeds the time-space frame of the seismic transient (Lomnitz, 1994). On the other hand, in a volcano-tectonic context, different energy flows can either be a cause, either an effect of perturbation, depending on depth of their primary source. Thus, in some instances the strain transient related to local earthquakes produces anomalous chemical flows, while, in other instances the local seismic activity may be produced by chemical flows from the magmatic source. Following a period of lower energy release, other 3 anomalous periods were observed from November 2004, either in the seismic release and in the surface heat flow, even out from fumaroles. So far, the monitored sites resulted very sensitive to minor perturbations of the system. The comparative analysis of different time-series supplies information related to perturbations of the state variables, useful to verify conceptual framework and to better define “classical” and “new” monitoring techniques for volcanic, as well as seismic surveillance

On the Trade-Off Between Enhancement of the Spatial Resolution and Noise Amplification in Conical-Scanning Microwave Radiometers

The ability to enhance the spatial resolution of measurements collected by a conical-scanning microwave radiometer (MWR) is discussed in terms of noise amplification and improvement of the spatial resolution. Simulated (and actual) brightness temperature profiles are analyzed at variance of different intrinsic spatial resolutions and adjacent beams overlapping modeling a simplified 1-D measurement configuration (MC). The actual measurements refer to Special Sensor Microwave Imager (SSM/I) data collected using the 19.35 and the 37.00 GHz channels that match the simulated configurations. The reconstruction of the brightness profile at enhanced spatial resolution is performed using an iterative gradient method which allows a fine tuning of the level of regularization. Objective metrics are introduced to quantify the enhancement of the spatial resolution and noise amplification. Numerical experiments, performed using the simplified 1-D MC, show that the regularized deconvolution results in negligible advantages when dealing with low-overlapping/fine-spatial-resolution configurations. Regularization is a mandatory step when addressing the high-overlapping/low-spatial-resolution case and the spatial resolution can be enhanced up to 2.34 with a noise amplification equal to 1.56. A more stringent requirement on the noise amplification (up to 0.6) results in an improvement of the spatial resolution up to 1.64

Evolution of dwarf galaxies hosting GW150914-like events

Here we present a detailed analysis of the properties and evolution of different dwarf galaxies, candidates to host the coalescence of black hole binary systems generating GW150914-like events. By adopting a novel theoretical framework coupling the binary population synthesis code SEBA with the Galaxy formationmodel GAMESH, we can investigate the detailed evolution of these objects in awell-resolved cosmological volume of 4 cMpc, having aMilkyWay (MW)- like galaxy forming at its centre. We identify three classes of interesting candidate galaxies: MW progenitors, dwarf satellites, and dwarf galaxies evolving in isolation. We find that (i) despite differences in individual histories and specific environments the candidates reduce to only nine representative galaxies; (ii) among them, 3c44 per cent merge into the MW halo progenitors by the redshift of the expected signal, while the remaining dwarfs are found as isolated or as satellites of the MW and their evolution is strongly shaped by both peculiar dynamical history and environmental feedback; (iii) a stringent condition for the environments where GW150914-like binaries can form comes from a combination of the accretion history of their dark matter haloes and the radiative feedback in the high-redshift universe; and (iv) by comparing with the observed catalogues from the DGS and ALLSMOG surveys we find two observed dwarfs respecting the properties predicted by our model. We finally note how the present analysis opens the possibility to build future strategies for host galaxy identification

Vector casting for noise reduction

We report a new method for the reduction of noise from spectra. This method is based on casting vectors from one data point to the following data points of the noisy spectrum. The noise‐reduced spectrum is computed from the casted vectors within a margin that is identified by an envelope‐finder algorithm. We compared here the presented method with the Savitzky–Golay and the wavelet transform approaches for noise reduction using simulated Raman spectra of various signal‐to‐noise ratios between 1 and 25 dB and experimentally acquired Raman spectra. The method presented here performs well compared with the Savitzky–Golay and the wavelets‐based denoising method, especially at small signal‐to‐noise ratios and furthermore relies on a minimum of human input requirements

Hydrogen-based hybrid power unit for light vehicles: Assessment of energy performance and radiated electromagnetic emissions

Electrification of transport (electro-mobility) is considered an essential strategy to meet Europe’s climate and energy challenges. Nonetheless, within the future perspective of living in smart cities, the interaction between electromobility devices and the surrounding environment, including humans, needs to be further investigated. In this study, a new hybrid power unit is developed and equipped on a commercial electric bike. The energy performance of this prototype are analyzed together with its contribution to radiated electromagnetic emissions. The former analysis demonstrated the remarkable fuel efficiency shown by the new power unit, i.e., a 140km long distance can be covered at mean power, while the latter tests, undertaken within the reverberating chamber of the Universit`a degli Studi di Napoli “Parthenope”, demonstrated that the hydrogen bike prototype is compliant with the actual European Union regulations in terms of electromagnetic radiations, and that long-term effects of its radiations on humans are negligible

A SO2 flux study of the Etna volcano 2020–2021 paroxysmal sequences

The persistent open-vent degassing of Mt. Etna is often punctuated by months-long paroxysmal sequences characterized by episodes of violent Strombolian to lava fountaining activity. Understanding these gas-fueled transitions from quiescence to eruption requires routine measurement of gas fluxes. Here, we report SO2 flux measurements, obtained from a permanent UV camera system, collected over a two-year-long period spanning two paroxysmal sequences of Etna’s New South East Crater (NSEC) in December 2020/April 2021 and May/October 2021. In both cases, SO2 flux increased from ≤ 3250 Mg/day during “ordinary” activity to ≥ 4200 Mg/day. We interpret these distinct SO2 degassing regimes in light of seismic and thermal observations and drawing on numerical simulations of sulfur degassing constrained by parental melt sulfur contents in Etna’s hawaiites. We find that initiation of a paroxysmal sequence results from an approximate doubling of the time-averaged rate of magma supply (and degassing) above the sulfur exsolution level (∼150 MPa pressure), to >4 m3/s. This corroborates recent models that argue for the triggering of paroxysmal sequences by escalating supply of volatile-rich magma to a reservoir ∼3–4 km below the summit region. The non-stationary nature of magma flow and volcanic degassing we identify highlights the need for sustained surveillance to characterize long-term atmospheric budgets of volcanic volatiles

An enhanced resolution brightness temperature product for future conical scanning microwave radiometers

An enhanced spatial resolution brightness temperature product is proposed for future conical scan microwave radiometers. The technique is developed for Copernicus Imaging Microwave Radiometer (CIMR) measurements that are simulated using the CIMR antenna pattern at the L-band and the measurement geometry proposed in the Phase A study led by Airbus. An inverse antenna pattern reconstruction method is proposed. Reconstructions are obtained using two CIMR configurations, namely, using measurements collected at L-band by the forward (FWD) scans only, and combining forward and backward (FWD+BWD) scans. Two spatial grids are adopted, namely, 3 km x 3 km and 36 km x 36 km. Simulation results, referred to synthetic and realistic reference brightness fields, demonstrate the soundness of the proposed scheme that provides brightness temperature fields reconstructed at a spatial resolution up to ~ 1.9 times finer than the measured field when using the FWD+BWD combination.The work of Claudio Estatico was supported in part by the Gruppo Nazionale di Calcolo Scientifico–Istituto Nazionale di Alta Matematica (GNCS-INDAM), Italy. This work has been produced for the European Space Agency (ESA) in the frame of the Copernicus Program as a partnership between ESA and the European Commission.Peer ReviewedPostprint (author's final draft

Genesis and mechanisms controlling tornillo seismo-volcanic events in volcanic areas

Volcanic activity is often preceded or accompanied by different types of seismo-volcanic signals. Among these signals, the so-called tornillo (Spanish for "screw") events are considered to belong to a unique class of volcano-seismicity characterised by a long-duration coda, amplitude modulation and high-quality factor. These data constitute important evidence for the gas fraction inside magmatic fluids. However, the mechanism behind this unique signal remains not fully understood. Here we report new laboratory evidence showing that two different processes have either scale-invariant or scale-dependent effects in generating tornillo-like events. These processes are respectively the gas pressure gradient, which triggers the event and regulates the slow decaying coda, and the fluid resonance into small scale structures which, in turn, control the frequency content of the signal. Considering that the gas pressure gradient is proportional to the fluid flow, these new findings, as applied to volcanoes, provide new information to better quantify both gas rate and volume, and the dimension of the resonator.Publishedid 73385V. Processi eruttivi e post-eruttiviJCR Journa