1,721,193 research outputs found
Robust Satellite Techniques (RST) for Natural and Environmental Hazards Monitoring and Mitigation: Theory and Applications
No full textSeveral algorithms and data analysis techniques have been proposed using satellite observations (within atmospheric spectral windows) for cloud and surface parameters studies and for human environment monitoring applications. Quite all these algorithms are difficult to extend to different geographical, seasonal conditions, generally offering poor performances and uncertain reliability especially when applied in environmental risk prevision, monitoring and/or mitigation. In this paper the generalized satellite data analysis approach RST (Robust Satellite Technique) is described which extend the use of RAT (Robust AVHRR Techniques) approach -previously proposed by the same author in 1998 -to whatever satellite sensors. Successful RST applications are also described with reference to results so far achieved by using optical and microwaves passive sensors for volcanic eruption monitoring and prediction, forest fire detection, floods mapping, monitoring and early warning, possible earthquake precursors monitoring, oil spill detection and pipeline networks monitoring
Robust satellite techniques (RST) for natural environmental and technological hazards monitoring in the Sub Saharian region
No full textSatellite change detection methods are usually fixed-threshold, single-image oriented and very difficult to extend to different geographical areas or to different satellite sensors. Generally, when satellite data are used to give quantitative measurements, the difficulty to correctly estimate spectral atmospheric transmittance (requiring ancillary data not always, not everywhere available) can be responsible of highly biased estimates. On the other hand, it is possible to identify a number of satellite remote sensing applications (mainly devoted to environmental monitoring or, from a wider point of view, to change detection problems) for which the use of satellite data in se might be sufficient and effective. In this context, a different approach (RST, Robust Satellite Technique) to Earth surface and atmosphere monitoring, at the same time reliable and exportable (on different satellite sensors and geographic areas) has been proposed and it will be described in this paper together with its applications relevant for Sub Saharan region.
In particular results so far achieved by using
optical and microwaves passive sensors for monitoring forest fire and dust storms, for floods mapping, monitoring and early warning, for volcanic eruption monitoring and prediction, for earthquake precursors monitoring, oil spill detection and pipeline networks monitoring, will be presented
ROBUST AVHRR TECHNIQUES (RAT) FOR ENVIRONMENTAL MONITORING: THEORY AND APPLICATIONS
No full textMany algorithms and data analysis techniques have been proposed up to now which make use of satellite observations within atmospheric widows mainly for clouds and surface parameters studies and for environmental monitoring applications. Quite all these algorithms are difficult to extend to different geographical, seasonal conditions, having generally poor performances and uncertain reliability especially when applied in environmental risk prevision, monitoring and/or mitigation. In this paper a new, robust (in a statistical sense), approach (RAT) to the use of NOAA/AVHRR observations is proposed and its successful application to different environmental emergencies illustrated also in expectation of next generation of satellite sounders devoted or usable for environmental monitoring purposes
SANA: SUB-PIXEL AUTOMATIC NAVIGATION OF AVHRR IMAGERY
No full textAn automatic method (SANA) for sub-pixel navigation of Advanced Very High Resolution Radiometer (AVHRR) imagery is proposed. It progressively corrects satellite attitude and reduces navigation errors all over the scene by using an iterative approach. Tests performed on more than 400 AVHRR passes over Europe, demonstrate the above mentioned method capability to obtain, with no human intervention, a final navigation accuracy within 1 pixel. Main characteristics of such a method are its processing speed as well as its full exportability to other satellite packages
Two years of operational use of SANA (sub-pixel automatic navigation of AVHRR) scheme: accuracy assessment and validation.
No full textAutomated techniques for satellite imagery navigation and co-location are especially required for environmental monitoring activities
intensively using satellite data. In this work are presented the results obtained after 2 years of operational use of the Subpixel Automatic
Navigation of AVHRR (SANA) scheme. An automatic method for accuracy assessment of satellite navigation techniques, which permits a
preliminary evaluation of their performances, dealing with a large collection of test images is also proposed. The navigation accuracy
assessment, performed by using a selection of small islands as reference points, is discussed.
Results achieved over more than 400 Advanced Very-High-Resolution Radiometer (AVHRR) scenes confirm that the SANA scheme is a
very accurate one (computed mean navigation error is generally about one AVHRR pixel). Furthermore, because of its high processing speed,
it can be considered a suitable tool for intensive satellite data processing in multitemporal analyses, especially required for environmental
studies as well as for operational monitoring purposes
Scaling Law in a Turbulent Baroclonic Instability
No full textThis work provides an empirical investigation of scaling laws in a cloud system generated and advected by a strong baroclinic instability. An infrared satellite image with a spatial (horizontal) resolution of about 1 km has been analyzed. The presence of two sizeable and unmistakable scaling regions, one extending from 1 to 15 km and characterized by a power law with an exponent close to 1, the other stretching from 20 km up to 100 km and characterized by a power law with exponent close to 1/3, have been revealed by variogram analysis. These two scaling laws are in agreement with the idea of scale invariance of the turbulent motion and also suggest the presence of a self-similar structure. To explore this possibility, wavelet transform analysis at different spatial scales has been used. Our findings are that self-similarity is present at the smallest scales, but this universal characteristic may be masked by non-universal effects which influence the homogeneity of the underlying turbulent motion. The implications of the two scaling exponents, 1 and 1/3, are also discussed
Foreword: Advances in Multi-Parametric, Time-Dependent Assessment of Seismic Hazard and Earthquakes Forecast
No full textUntil now proposed Operational Earthquakes Forecast (OEF) methods suffer of strong limitations in terms of their actual (too low absolute value of estimated probabilities) and general (forecast is substantially limited to earthquakes which are preceded by foreshocks) operational applicability [e.g. Wang and Rogers, 2014; Panza et al., 2014]. They become of some (unfortunately still marginal) usefulness just when such a low-probabilities are multiplied for very high exposure and/or vulnerability factors in order to obtain significant amounts of the estimated seismic risk.Mostly, due to these limitations they have been scarcely used in the past while the interest of the scientific community for the study of additional, not just seismological, geophysical/geochemical parameters that could provide useful indications about the evolution of seismic hazard in the medium/short term, is every day increasing
Earthquakes Precursors and Earthquake Prediction: Recent Advances
No full textSeismic hazard assessment and medium/long-term earthquakes forecasting have long been key research topics for the national governments interested in giving scientific bases to their building codes in earthquakes prone areas. Methods like the PSHA (Probabilistic Seismic Hazard Assessment, e.g. Cornell, 1968) were used to extrapolate from the (often very small) frequencies of past earthquakes the annual probability of occurrence of (even very large) earthquakes in the future. Such methods were strongly criticized for “... the significant consequences of their failures in terms of human and economic losses...” ( Wyss et al., 2012). In Japan “...since 1979, earthquakes that caused 10 or more fatalities ... actually occurred in places assigned a relatively low probability” ( Geller, 2011). In the same country the underestimation of the Tohoku earthquake (March 11th 2011, MW = 9.0) intensity by the Japanese National Seismic Hazard Maps and the intrinsic limits of PSHA were at last officially recognized (e.g., Kagan and Jackson, 2013 and Fujiwara et al., 2013). Together with the 2011 Tohoku event, Stein et al. (2012) report other highly destructive earthquakes (e.g. 2008 Wenchuan, 2010 Haiti, etc.) occurred in areas predicted by to be relatively safe. The ground accelerations of most strong earthquakes occurred in 2000–2010 were significantly underestimated (Kossobokov and Nekrasova, 2012) by the GSHAP (Global Seismic Hazard Project) maps (based on PSHA). Not rarely, and often after a major earthquake, the probabilistic maps of seismic hazard require a revision with a general increase of the seismic hazard in the affected area (e.g. Bommer and Abrahamson, 2006). Such hazard underestimations (dramatically recognized only after disastrous earthquakes) are particularly frequent in areas where neither historical or instrumental events are reported in seismic catalogues. Their possible consequences were properly described in Peresan et al., 2013 and Artioli et al., 2013.
In this context the interest in alternative observational techniques and appropriate data analysis methods to improve the seismic hazard assessment in the short-medium term increases every day.
Various independent observations have been reported for many decades to support models describing the earthquake generation process as a non-random phenomenon that involves wide spatial and temporal scales often (even if not always) culminating in a large event in correspondence to some critical point.
Anomalous changes in the physical/chemical state of the Earth lithosphere, atmosphere and ionosphere, which could be timely identified provided that adequate measurement systems are deployed and appropriate data analysis methods are used, can be associated to those processes. Several geophysical parameters (see for instance Tronin, 2006 and Cicerone et al., 2009, and reference herein) have been proposed as possible earthquake precursors for decades. Among them ground deformations (uplift and tilt), abrupt changes in gas emission rates, underground water level, temperature and chemical composition, electrical properties of rocks, atmosphere and ionosphere, near surface air temperature and relative humidity, and the Earth’s thermal emission were observed. A large number of theoretical models and laboratory experiments, which could explain the occurrence of the observed anomalies in relation with the preparatory phase of an earthquake (e.g. Scholz et al., 1973, Tronin, 1996, Pulinets and Boyarchuk, 2004, Freund et al., 2006, Pulinets and Ouzounov, 2011 and Tramutoli et al., 2013, etc.), were proposed at the same time.
This special issue of the “Physics and Chemistry of the Earth” journal contains twenty-four articles, most of them presented at 2014 EGU Assembly, offering an updated review of the recent advances in the study of earthquake precursors and related physical phenomena
EVALUATION OF A NEW SATELLITE-BASED METHOD FOR FOREST FIRE DETECTION
No full textAdvanced Very High Resolution Radiometer (AVHRR)-based fire detection methods are considered in this work in order to assess their effective usefulness in the framework of civil programmes for fire risk and damage mitigation. The discussion is divided into the evaluation of the most commonly used methods and the description of a new fire detection procedure which is proposed in this paper. Commonly used detection methods are based on using absolute threshold values for decision tests. These values usually match only with very local, uniform (in space and time) situations, and are often inadequate when applied to heterogeneous, or simply different, geographical areas or seasons. A high number of false alarms, so high as to make the satellite-based product not operationally utilizable, is the main disadvantage of the fixed-threshold approach. The new fire-detection procedure proposed here makes use only of historical AVHRR data in order to automatically produce local (in space and time) threshold values, suitable for fire-event detection also in very critical situations. High fire discrimination capabilities with low false-alarm rates, simple unsupervised implementation and, above all, flexibility for automatic extension to completely different geographic areas and observation conditions, are the main advantages associated with this new technique. Results obtained for different Italian areas have been successfully compared with ground observations made by the Italian Forestry Service. Tests made over a long observation period show that, on cloud-free regions, more than 75% of significant forest fires are detected with less than 20% of false alarms
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