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In this contribution, new data concerning bryophytes, fungi, and lichens of the Italian flora are presented. It includes new records and confirmations for the bryophyte genera Aneura, Aulacomnium, Dumortiera, Fossombronia, Hennediella, Hygrohypnella, Pohlia, Porella, Riccardia, Tortella, and Tortula, the fungal genera Cortinarius, Mycena, Naucoria, Trichoglossum, and Tubaria and the lichen genera Agonimia, Blastenia, Chaenotheca, Cladonia, Endocarpon, Gyalecta, Lecanographa, Parmeliella, Porpidia, Stenhammarella, and Thelidium.

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American Geophysical Union Fall Meeting, 10-14 December 2018, Washington D.C., Adjoint-state full waveform inversion (FWI) is an HPC technique that potentially allows extracting models of the rocks elastic properties with a resolution that is higher than that of almost any other geophysical method. Despite its potential, FWI suffers from a number of issues that makes it challenging to be applied to most types of field data. One of the main problems is the high non-linearity, which makes the solution strongly dependent on the initial model selected. In particular, for the commonly-used L2-norm objective function, successful FWI requires initial models that allow reproducing seismograms differing by less than half a period from the recorded ones. A typical solution is applying arrival travel-time tomography (TTT) in a first stage and use the resulting model as initial one for FWI. However, this approach does not work when the original data lack low frequencies and have only short offsets, as it occurs with streamer data in deep water settings, so that there are no first arrival refractions in the original recordings. In this work, we present a number of solutions that allow overcoming these issues and apply FWI to short-offset streamer data lacking low frequencies. These include (1) the wave equation downward continuation (DC) of the streamer data followed by joint refraction and reflection TTT to obtain a suitable starting model for FWI, and (2) using robust, instantaneous phase-based functions instead of the typical L2-norm to compare simulated and recorded data. We show that both approaches allow successful application of FWI to limited-offset data (4 Hz, typically present in field data recordings. In particular, we present field data examples showing that the combination of DC, joint refraction and reflection TTT, and FWI, allows obtaining accurate high-resolution velocity models using data acquired with a 480 channel, 6 km-long streamer in a >2 km deep water layer, starting FWI at a frequency as high as 8 Hz. The obtained FWI velocity model allows identifying a number of geologically meaningful details, as a high-velocity salt layer interbedded within sediments, which can not be identified otherwise

18 International SEISMIX Symposium, Seismology between the Poles, 17-22 June 2018, Cracow, Poland.-- 1 page, Adjoint-state FWI is in terms of resolution the most powerful existing tomographic method. It has become a well-established inversion method thanks to the efforts made by both industry and academy (Virieux and Operto, 2009). The main strength of the technique is that it allows obtaining unprecedented high resolution images of the subsurface of the Earth. In the last years we have developed our own FWI code called 2D3DA-FWI as a reference to the 2D and 3D acoustic FWI (Dagnino et al. 2014, Jimenez et al. 2015, Dagnino et al. 2016). Now, we applied this code to invert a 66 km-wide and 3 kmdeep Vp model. This shallow part displays the deep Sandino basin, filled by a sediment pile of variable thickness, which is folded and bent by the tectonic activity associated to the convergence between the subducting Cocos plate and the continent. Below the sediments, the basement is located at a variable depth between 200m and 2.5km depth. The details of its inner structure, the lithology of the geological domains, and the geometry and location of the main faults, which reflect the coupling between the subducting and overriding plates, are unknown. To better define all this details we have applied an adjoint-state FWI using the streamer data acquired in this region to obtain a higher resolution Vp model. To achieve this goal we have processed the multi-channel seismic data, applying data processing sequences designed by our group (Dagnino et al. 2017), and we have generated an initial model using a first arrival travel time tomography code based on a previously obtained one (Sallares et al., 2013)

18 International SEISMIX Symposium, Seismology between the Poles, 17-22 June 2018, Cracow, Poland.-- 1 page, Here we present a high-resolution P-wave velocity model of the sedimentary cover and the uppermost basement until ~3 km depth obtained by applying adjoint-state full-waveform inversion (FWI) to a Multichannel Seismic (MCS) data set acquired with a 6 km-long streamer of 480 channels. The MCS profile was acquired in the Alboran Sea (SE Iberia), in the framework of the TOPOMED-2011 experiment. The inherent non-linearity of FWI for short-offset, band-limited seismic data as this one, was circumvented by using a reference velocity model obtained by travel-time tomography. Given the water depth in excess of ~2 km and the short acquisition offset, refractions are not visible as first arrivals in the original shot gathers. To solve this issue, we applied a data processing/modelling sequence consisting of three steps: (1) data re-datuming (i.e. downward continuation, DC) by back-propagation of the recorded seismograms to the seafloor using a numerical solver of the wave equation; (2) joint refraction (first arrival) and reflection (top of basement) travel-time tomography of the DC shot/receiver gathers; and (3) FWI of the original shot gathers using the model obtained by travel-time tomography as initial reference. FWI is performed using specific data and gradient preconditioning techniques to concentrate model updates in the regions where the gradient is more reliable. A multi-scale strategy adding low to high frequencies sequentially is followed to reduce the risk of converging to a local minimum and add details progressively to the model. The source wavelet is also inverted and updated in each inversion step. We show that FWI provides reliable and accurate results starting at frequencies as high as ~6 Hz, because the initial model has the low wavenumber information needed to avoid cycle-skypping. The final velocity model shows a number of geologically meaningful details that cannot be identified in the initial model. For instance, a volcano-like structure is observed in the central part of the profile, also a strong velocity contrast that accurately follows the shape and geometry of the top of the basement, and steeply dipping anomalies that correspond to normal faults can be seen at the flanks of the basin. In addition, a 200-300 m thick, high-velocity layer embedded within the sediments that likely correspond to salt deposited during the Messinian crises is clearly imaged. The two-way-time transformed velocity model has an excellent match with time-migrated MCS image: velocity changes nicely follow major reflectivity contrasts and fault locations, which further validates the inversion result. The results confirm that the combination of DC and joint refraction and reflection travel-time inversion provides models that are accurate enough to apply FWI to relatively short offset streamer data starting at realistic field data frequencies

European Geosciences Union (EGU) General Assembly 2018, 8-13 April 2018, Vienna, Austria.-- 1 page, In this work we present a 2D time-domain, adjoint-state acoustic full-waveform inversion to retrieve high-resolution models of ocean physical parameters such as sound speed, temperature and salinity. The proposed method is first described and then applied to pre-stack multi-channel seismic (MCS) data acquired in the Gulf of Cadiz (SW Iberia) in 2007 in the framework of the Geophysical Oceanography project. The inversion strategy flow includes specifically-designed data pre-conditioning for acoustic noise reduction, followed by the inversion of sound speed in the shotgather domain. We show that the final sound speed model has a horizontal resolution of∼70m, which is two orders of magnitude better than that of the initial model constructed with coincident eXpend-able Bathy Thermograph (XBT) data, and close to the theoretical resolution of O (λ). Temperature (T) and salinity(S) are retrieved with the same lateral resolution as sound speed by combining the inverted sound speed model with the thermodynamic equation of seawater and a local, depth-dependent T-S relation derived from regional conductivity-temperature-depth (CTD) measurements of the National Oceanic and Atmospheric Administration database. The comparison of the inverted T and S models with XBT and CTD casts deployed simultaneously to the MCS acquisition shows that the thermohaline contrasts are resolved with an accuracy of0.18oCfor temperatureand0.08PSUfor salinity. The combination of oceanographic and MCS data into a common, pseudo-automatic inversion scheme allows to quantitatively resolve submeso-scale features that ought to be incorporated into larger-scale ocean models of ocean’s structure and circulation

Giussani, V. ... et. al.-- 7th Biannual ECOtoxicology MEeting (BECOME 2016), Managing aquatic and terrestrial environments: an ecotoxicological perspective, 22-24 November 2016, Livorno.-- 5 pages, 1 figure, 1 table, Mediterranean Benthic Harmful Algal Blooms represent a phenomenon of particular interest and harmful proliferations of Ostreopsis spp. are increasing. During the last years several toxicological studies have been performed to assess the toxicity of this genus, highlighting that O. cf. ovata is the most toxic species, at least in the Mediterranean area. For this reason, it has been selected for an ecotoxicological investigationon different on model organisms: crustaceans (larvae of Amphibalanus amphitrite, Artemia salina, Tigriopus fulvus), echinoderms (larvae and juveniles of Paracentrotus lividus), cnidaria (polyps and ephyrae of Aurelia sp.) and fish (juveniles of Dicentrarchus labrax). Our outcomes report a different sensitivity to O. cf. ovata of all tested organisms and improve data availability for the risk assessment of exposure to Ostreopsis by using, for example, the > Species Sensitivity Distributions (SSDs) > approach

European Geosciences Union General Assembly 2017, 23-28 April 2017, Vienna, Austria.-- 1 page, High-resolution velocity models can be retrieved by applying adjoint-state full-waveform inversion (FWI) tocontrolled source data. However the strong non-linearity of the problem makes the solution strongly dependent onthe initial model chosen and on the low frequency content of the seismic source. Besides, typical relatively-shortoffset multi-channel seismic (MCS) data lacks first -refracted- arrivals that are commonly used to obtain a suitablestarting model for FWI.Here we show that this problem can be solved by combining a joint refraction and reflection Travel TimeTomography (TTT) of a re-datumed version of the same data set to obtain an appropriate reference model with thecorrect low wavenumber on it that is subsequently refined by FWI. The proposed workflow is first described andthen applied to MCS data acquired with 6 km-long streamer during the TOPOMED-2011 experiment in the Gulfof Cadiz (SE Iberia).The applied strategy includes as a first step a wave equation-based downward continuation (DC) or redatumingof the MCS data to simulate a sea bottom acquisition geometry, followed by a joint travel-time tomographicinversion of first arrivals identified in the DC data set together with the top of the basement (TOB) reflection fromthe MCS common mid point gathers to finally perform the multi-scale FWI of the original streamer data usingthe model obtained by TTT as initial model. The robustness of the Vp and TOB geometry model obtained byjoint refraction and reflection TTT is assessed by comparing the results obtained using three independent datasets (different groups of shotgathers). The three models coincide within parameter uncertainty bounds, and thetwo-way-time transformed TOB geometry is also coincident with the time migrated image. We conclude thereforethat the velocity and reflector depth model obtained is robust. The joint DC refraction and reflection travel-timeinversion scheme helps to reduce the inherent existing velocity-depth trade-off. As a third step, we apply FWIusing the TTT model as initial model. We show that in this case FWI can be done starting at realistic frequencies,because the starting model has the low wavenumber information needed to avoid cycle-skypping problems. Themain limitation is the depth of the inverted model (∼2 km) severely limited by the short acquisition offset

17th International Seismix Symposium (Seismix 2016), 15-20 May 2016, Aviemore, Scotland, Seismic tomography methods are useful techniques to retrieve the physical properties of the subsurface. In particular, adjoint-state full waveform inversion (FWI) of controlled source data is considered to be one of the most powerful tools to obtain accurate, high-resolution models. However one of its main drawbacks is the strong non-linearity of the problem, which makes the solution strongly dependent on the initial model and on the low frequency content of the data set. A common strategy to mitigate these issues is to combine the robustness of Travel Time Tomography (TTT) to obtain an appropriate reference model that is subsequently refined by FWI. The combination of TTT and FWI is often used for long-offset acquisition geometries, where refracted waves are present as first arrivals. Conversely, its application to streamer-type multichannel seismic (MCS) data is infrequent, because these data are intrinsically short offset so the presence of refractions is very limited. In this case, Downward Continuation (DC) or redatuming of the MCS data to simulate an ocean bottom experiment allow recovering the refracted waves as first arrivals, so it is possible to perform TTT. In this work we use synthetic data to show that such TTT-based velocity models are suitable initial models for FWI even when data lack frequencies below 4 Hz; a realistic value in field data recordings. In summary, the strategy proposed, implemented and tested consists of several processing and inversion steps. First we compute the downward continued wavefield using a finite difference solution of the acoustic wave equation in time domain. The solver used for the propagation, developed at BCSI, is parallelized and incorporates a multi-shooting strategy to back-propagate the wavefield. The chosen datum level is the sea bottom. Then we pick the first arrivals of the DC data and we perform the TTT. We show that, in contrast to other possible choices for the initial model, the TTT solution is kinetically correct to start FWI at 4 Hz, in the sense that it allows to overcome cycle-skipping. Ongoing work is the application of this strategy to field data acquired in the Alboran basin with a 6 km-long streamer (TOPOMED experiment). The goal is to characterize the shallow structure in a tectonically active area the east Alboran basin volcanic arc. This includes the geometry of the sedimentary layers and basement outcrops and mapping large active faults that may represent a regional earthquake hazard

European Geosciences Union General Assembly 2016 (EGU2016), 17-22 April 2016, Vienna, Austria.-- 1 page, Seismic tomography methods and in particular full waveform inversion (FWI) of controlled source data are powerful tools to obtain accurate information of the physical properties of the subsurface. One of their main drawbacks is however the strong non-linearity of the problem, which makes the solution strongly dependent on the initial model and on the low frequency content of the data set. A common strategy to mitigate these issues is to combine the robustness of Travel Time Tomography (TTT) to obtain an appropriate reference model that is subsequently refined by FWI. This combined technique is often used for long-offset acquisition geometries, where refracted waves are present as first arrivals. Conversely, its application to streamer-type multichannel seismic (MCS) data is rare, because these data are intrinsically short offset so the presence of refractions is very limited. In this work we use synthetic data to show how the downward continuation (DC) or redatuming of the MCS data prior to TTT allows obtaining velocity models that can be then used as initial models for FWI even if data lack frequencies below 4 Hz. In summary, the proposed strategy consists of the following steps: 1) We compute the downward continued wavefield using a finite difference solution of the acoustic wave equation in time domain. The solver used for the propagation was developed by the Barcelona Centre for Subsurface Imaging (BCSI) and incorporates a mutli-shooting strategy necessary to back-propagate the wavefield and reduce the computational time. Our new datum level chosen corresponds to the bathymetry of the model. 2) We use the resultant DC MCS wavefield to identify the refracted phases (first arrivals) highlighted by the redatuming process and we invert them applying TTT. The resulting model, which has the low wavenumber information needed to reduce the non-linearity problems of the FWI, is then used as initial model to perform multi-scale FWI of the original MCS data starting at realistic frequencies. High-resolution Pwave velocity results are obtained and also an improvement of the inversion stability is observed using DC MCS TTT - FWI strategy. Another advantage of this methodology is that the ray coverage increases in the deeper parts of the model (DC MCS data). It is also shown that, due to the lack of low frequencies, FWI does not converge unless the CD MCS TTT model is used

European Geosciences Union General Assembly 2016 (EGU2016), 17-22 April 2016, Vienna, Austria.-- 1 page, This work demonstrates the feasibility to retrieve high-resolution models of oceanic physical parameters by means of 2D adjoint-state full-waveform inversion (FWI). The proposed method is applied to pre-stack multi-channel seismic (MCS) data acquired in the Gulf of Cadiz (SW Iberia) in the framework of the EU GO (Geophysical Oceanography) project in 2006. We first design and apply a specific data processing flow that allows reducing data noise without modifying trace amplitudes. This step is shown to be essential to obtain accurate results due to the low signal-to-noise ratio (SNR) of water layer reflections, which are typically three-to-four orders of magnitude weaker than those in solid earth. Second, we propose new techniques to improve the inversion results by reducing the artefacts appearing in the gradient and misfit as a consequence of the low SNR. We use a weight and filter operator to focus in the regions where the gradient is reliable. The source wavelet is then inverted together with the sound speed. We demonstrate the efficiency of the proposed method and inversion strategy retrieving a 2D sound speed model along a 50 kmlong MCS profile collected in the Gulf of Cadiz during the GO experiment. In this region, the Mediterranean outflow entrains the Atlantic waters, creating a salinity complex thermohaline structure that can be measured by a difference in acoustic impedance. The inverted sound speed model have a resolution of 75m for the horizontal direction, which is two orders of magnitude better than the models obtained using conventional, probe-based oceanographic techniques. In a second step, temperature and salinity are derived from the sound speed by minimizing the difference between the inverted and the theoretical sound speed estimated using the thermodynamic equation of seawater (TEOS-10 software). To apply the TEOS-10 we first calculate a linear-fitting between temperature and salinity using regional data from the National Oceanic and Atmospheric Administration (NOAA) compilation. Pressure is calculated from latitude and depth. In the final step, salinity is calculated using the Temperature-Salinity relation and the previously estimated temperature. The comparison of the inverted temperature, salinity model with measures from XBT and CTD probes deployed simultaneously to the MCS data acquisition shows that the accuracy of the inverted models is ~0.15ºC for temperature and ~0.1psu for salinity

17th International Seismix Symposium (Seismix 2016), 15-20 May 2016, Aviemore, Scotland

18 pages, 9 figures, supporting information https://dx.doi.org/10.1002/2016JC011844, This work demonstrates the feasibility of 2-D time-domain, adjoint-state acoustic full-waveform inversion (FWI) to retrieve high-resolution models of ocean physical parameters such as sound speed, temperature and salinity. The proposed method is first described and then applied to prestack multichannel seismic (MCS) data acquired in the Gulf of Cadiz (SW Iberia) in 2007 in the framework of the Geophysical Oceanography project. The inversion strategy flow includes specifically designed data preconditioning for acoustic noise reduction, followed by the inversion of sound speed in the shotgather domain. We show that the final sound speed model has a horizontal resolution of ∼ 70 m, which is two orders of magnitude better than that of the initial model constructed with coincident eXpendable Bathy Thermograph (XBT) data, and close to the theoretical resolution of O(λ). Temperature (T) and salinity (S) are retrieved with the same lateral resolution as sound speed by combining the inverted sound speed model with the thermodynamic equation of seawater and a local, depth-dependent T-S relation derived from regional conductivity-temperature-depth (CTD) measurements of the National Oceanic and Atmospheric Administration (NOAA) database. The comparison of the inverted T and S models with XBT and CTD casts deployed simultaneously to the MCS acquisition shows that the thermohaline contrasts are resolved with an accuracy of 0.18oC for temperature and 0.08 PSU for salinity. The combination of oceanographic and MCS data into a common, pseudo-automatic inversion scheme allows to quantitatively resolve submeso-scale features that ought to be incorporated into larger-scale ocean models of oceans structure and circulation, The work has been partially supported by the projects KALEIDOSCOPE and CO-Dos financed by REPSOL and MINECO project POSEIDON (CTM2010-21569) and HADES (CTM2011-30400-C02). B. Biescas work has been funded by the European Commission through the Marie Curie Action FP7-PEOPLE-2012-COFUND-600407

16TH SEISMIX International Symposium on Multi-scale Seismic Imaging of the Earth's crust and Upper Mantle, 12-17 October 2014, Castelldefels, Barcelona.-- 1 page, Recent work on Full Waveform Inversion (FWI) has yielded an increasing number of objective functions as alternative to the traditional L2-norm. The main motivation of such works is to mitigate the effects of nonlinearity that are intrinsic to FWI by reducing the dependence of results on the initial model used and the lowest frequency that is present in field data. In this work, we perform a comparative study of five objective functions under a common 2D acoustic FWI scheme using synthetic seismic data. We compare results from L2-norm, phase, envelope, Non-Integration-Method (NIM), and Cross-Correlation Travel Time (CCTT) functions. We test the robustness of the functionals as a function of their performance with increasing starting frequency in the FWI.We also show the improvement of inversion results when the CCTT inversion result is used as initial model for any other function. Further we show the susceptibility of the different functionals to noise. Our results reveal that a promising strategy to invert noisy data with a limited low frequency content is a hybrid one combining CCTT and phase objective functions

16TH SEISMIX International Symposium on Multi-scale Seismic Imaging of the Earth's crust and Upper Mantle, 12-17 October 2014, Castelldefels, Barcelona.-- 1 page, For a velocity model building full wave-form inversion (FWI) offers a high definition tomographic method. Despite its potential, FWI relies in a good initial model that contains the large wave numbers of the model or in other words the low frequencies which are not contained in field data. Other techniques as, for example, travel time tomography (TTT) that uses the first arrival travel times can be applied to obtain this large wave number of the velocity model to later introduce it as initial model in the FWI. The possibility to obtain large wave number using other techniques proves that seismic data contains such information however FWI is not appropriated to invert this background model becoming an important drawback in the FWI framework. In this context, we present a sensibility study of the FWI results versus the initial model when only first arrivals are considered in the misfit function to avoid cycle-skipping effects. Since the first arrival position depends mostly on the P-wave velocity we apply an acoustic inversion to reduce the number of parameters involve in the FWI and hence the number of local minima in the misfit function as well as to reduce the time employed in the inversion