239 research outputs found
Basin scale assessment of landslides geomorphological setting by advanced InSAR analysis
An extensive investigation of more than 90 landslides affecting a small river basin in Central
Italy was performed by combining field surveys and remote sensing techniques. We thus defined the
geomorphological setting of slope instability processes. Basic information, such as landslides mapping
and landslides type definition, have been acquired thanks to geomorphological field investigations
and multi-temporal aerial photos interpretation, while satellite SAR archive data (acquired by ERS
and Envisat from 1992 to 2010) have been analyzed by means of A-DInSAR (Advanced Differential
Interferometric Synthetic Aperture Radar) techniques to evaluate landslides past displacements
patterns. Multi-temporal assessment of landslides state of activity has been performed basing
on geomorphological evidence criteria and past ground displacement measurements obtained by
A-DInSAR. This step has been performed by means of an activity matrix derived from information
achieved thanks to double orbital geometry. Thanks to this approach we also achieved more detailed
knowledge about the landslides kinematics in time and space
Is there a need for a forest restoration certification scheme?
We propose the development of a certification scheme for forest ecosystem restoration that aims for
the adoption of protocols and guidelines to ensure the sustained ecological and social value of restored
ecosystems. Despite an accumulation of experience on ecosystem restoration over the past decades, it
is still common to measure the success of restoration mainly in terms of number of seedlings planted
or their survival in the short term. A strong focus on planting targets may divert attention from the
actual objectives: establish self-sustaining forested ecosystems that provide livelihood or other
ecosystem service benefits to local people. Two important determinants of short and long term
success, which often do not receive sufficient attention, are matching the right seed source to the
planting site conditions and ensuring that restored populations of trees have sufficient genetic
variability to be self-sustaining. Because of the enormous scale of land degradation and the funds being pledged to tackle it, standardized measures of success are of increasing importance. Restoration success needs to be evaluated in a holistic way by restoration practitioners, government institutions, civil society
organizations, private sector and, importantly, funding agencies. Much is known about how to restore ecosystems in different regions and under different conditions, however currently there is no consensus on what success looks like or what the minimum criteria should be for monitoring and documenting success. Success can be achieved by following well defined practices and protocols (eg by ensuring high diversity both at species and genes levels, number of mother trees for the collection of reproductive material, provenance, etc) during the various phases of the restoration process. We make a case for the development of a certification system to support long term value of restored populations for global application
Temporal variations of zooplankton biomass in the Ligurian Sea inferred from long time series of ADCP data
Abstract. Three years of 300 kHz acoustic doppler current profiler data collected in the central Ligurian Sea are analysed to investigate the variability of the zooplankton biomass and the diel vertical migration in the upper thermocline. After a pre-processing phase aimed at avoiding the slant range attenuation, hourly volume backscattering strength time series are obtained. Despite the lack of concurrent net samples collection, different migration patterns are identified and their temporal variability examined by means of time–frequency analysis. The effect of changes in the environmental condition is also investigated. The highest zooplankton biomasses are observed in April–May just after the peak of surface primary production in March–April. The main migration pattern found here points to a "nocturnal" migration, with zooplankton organisms occurring deeper in the water column during the day and shallower at night. Also, twilight migration is highlighted during this study. The largest migrations are recorded in November–December, corresponding to lowest backscattering strength values and they are likely attributable to larger and more active organisms (i.e. euphausiids and mesopelagic fish). The results suggest further applications of the available historical acoustic doppler current profiler time series
Probabilistic Model-Based Safety Analysis
Model-based safety analysis approaches aim at finding critical failure
combinations by analysis of models of the whole system (i.e. software,
hardware, failure modes and environment). The advantage of these methods
compared to traditional approaches is that the analysis of the whole system
gives more precise results. Only few model-based approaches have been applied
to answer quantitative questions in safety analysis, often limited to analysis
of specific failure propagation models, limited types of failure modes or
without system dynamics and behavior, as direct quantitative analysis is uses
large amounts of computing resources. New achievements in the domain of
(probabilistic) model-checking now allow for overcoming this problem.
This paper shows how functional models based on synchronous parallel
semantics, which can be used for system design, implementation and qualitative
safety analysis, can be directly re-used for (model-based) quantitative safety
analysis. Accurate modeling of different types of probabilistic failure
occurrence is shown as well as accurate interpretation of the results of the
analysis. This allows for reliable and expressive assessment of the safety of a
system in early design stages
Upper layer current variability in the Central Ligurian Sea
Abstract. Long-time series of surface currents and meteorological parameters were analysed to estimate the variability of the upper layer circulation and the response to the local winds. Current meter data were collected by an upward-looking RDI Sentinel 300 kHz ADCP deployed in the Central Ligurian Sea (43°47.77' N; 9°02.85' E) near the meteo-oceanographic buoy ODAS Italia 1 for more than eight months, from 13th of September 2003 to 24th of May 2004. The ADCP sampled the upper 50 m of water column at 8 m vertical resolution and 1 h time interval; surface marine and atmospheric hourly averaged data were provided by the buoy. Currents in the sampled layer were mainly barotropic, directed North-West in accordance with the general circulation of the area, and had a mean velocity of about 18 cm/s and hourly mean peaks up to 80 cm/s. Most of the observed variability in the upper thermocline was determined by inertial currents and mesoscale activity due to the presence of the Ligurian Front. Local wind had a minor role in the near-surface circulation but induced internal waves propagating downward in the water column
The M3A multi-sensor buoy network of the Mediterranean Sea
International audienceA network of three multi-sensor timeseries stations able to deliver real time physical and biochemical observations of the upper thermocline has been developed for the needs of the Mediterranean Forecasting System during the MFSTEP project. They follow the experience of the prototype M3A system that was developed during the MFSPP project and has been tested during a pilot pre-operational period of 22 months (2000?2001). The systems integrate sensors for physical (temperature, salinity, turbidity, current speed and direction) as well as optical and chemical observations (dissolved oxygen, chlorophyll-a, PAR, nitrate). The south Aegean system (E1-M3A) follows a modular design using independent mooring lines and collects biochemical data in the upper 100 m and physical data in the upper 500 m of the water column. The south Adriatic buoy system (E2-M3A) uses similar instrumentation but on a single mooring line and also tests a new method of pumping water samples from relatively deep layers, performing analysis in the protected ''dry'' environment of the buoy interior. The Ligurian Sea system (W1-M3A) is an ideal platform for air-sea interaction processes since it hosts a large number of meteorological sensors while its ocean instrumentation, with real time transmission capabilities, is confined in the upper 50 m layer. Despite their different architecture, the three systems have common sampling strategy, quality control and data management procedures. The network operates in the Mediterranean Sea since autumn 2004 collecting timeseries data for calibration and validation of the forecasting system as well for process studies of regional dynamics
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