Carla Pietrapertosa

AVHRR automated detection of volcanic clouds

A new satellite‐based technique has recently been proposed which seems suitable for an automatic detection of volcanic clouds in daytime conditions. In this paper the robustness of such a new approach, in particular in detecting early eruptive clouds, is evaluated, on several eruptive events at Mt Etna, by using five years of Advanced Very High Resolution Radiometer (AVHRR) data. The detection scheme is discussed together with its possible extension to night‐time monitoring and the improvements expected by its application to the next generation of satellite sensors (in particular Spinning Enhanced Visible and Infrared Imager (SEVIRI)) with enhanced spectral and temporal resolution. The proposed approach seems to overcome the limitations related to other proposed methods which, in some conditions (very fresh eruptive clouds, cold‐backgrounds, etc.), give false or missed detection and will no longer be applicable to the next generation of Geostationary Operational Environmental Satellites (GOES) due to the planned reduction of their thermal infrared channels until 2010.

Forest fire danger estimation based on the integration of satellite AVHRR data and topographic factors

The main objective of this work has been to evaluate the potential of integration of satellite data and topographic factor, in order to achieve improved performance in forest fire danger estimation. Existing AVHRR-based fire danger estimation methods (a review is specifically made) aim at obtaining fire susceptibility classification exploiting, mainly, the temporal evolution of NDVI, and Surface Temperature (Ts). In this work fire danger estimation has been performed integrating satellite data with fuel type and topographic factors. In order to evaluate the reliability of the estimated indices, the time-space distribution of actual forest fires, provided by the Italian Forestry service, has been used. Preliminary results are very promising; they have shown that in the summer of 1996, a large number of forest fires occurred in the estimated higher danger areas.

A Robust Satellite Technique (RST) for dust storm detection and monitoring: The case of 2009 Australian event

In this paper, an original method of satellite data analysis named RST (Robust Satellite Technique), already successfully used to study and monitor several natural and environmental hazards, is applied for the first time to a recent dust storm occurred in Australia in September 2009. This event was analyzed implementing RST on MTSAT-1R (Multi-functional Transport Satellite-1Replacement) Japanese geostationary satellite data. Some preliminary results of this study are presented, discussing RST performances even in comparison with traditional split window satellite techniques.

Pollino Project Action D: a multiscale approach in the space-time domain to environmental risk monitoring

Physical parameters related to Earth surface and atmosphere show different behaviors when observed at different space-time scales by using both remote sensing or traditional ground based techniques. The main aim of this project was to investigate the information content degradation which results moving from the use of observations obtained by direct-punctual (ground-based), higher spectral/spatial resolution (airborne sensors), higher time-resolution, low cost and low spatial resolution (satellites), in the context of the activities related to natural and environmental risks monitoring in protected natural areas. Several observational techniques have been contemporary used during two fields campaigns in the Pollino National Park (Southern Italy): a) from ground by direct measurements of near surface parameters (from - 70cm of depth up to 200cm of height) as well as by radiosonde and radiometric measurements of surface and atmospheric parameters; b) using hyperspectral (MIVIS) and photographic aerial observations; c) from LANDSAT-TM, NOAAA/AVHRR and ADEOS/AVIRIS satellite sounders. Campaign data have been integrated on a GIS (including high resolution cartographic layers) and long term evolutionary trends (up to 20 years) also considered after the analysis of available historical, LANDSAT and NOAA, satellite records. This paper will present the main achievements of the project with special emphasis on the trade-off between expected performances and economical sustainability of different environmental monitoring strategies in an operational context.

Satellite remote sensing of volcanic aerosols: a new AVHRR-based approach

Through this paper the authors propose a new approach for volcanic aerosols detection by satellite. By using only NOAA/AVHRR data at hands the proposed method seems able to detect eruptive volcanic clouds as well as long-period trends in stratospheric aerosol loading related to major eruptive events. Several examples of application to different events of volcanic emission are presented; some cases of Etna and Stromboli volcanoes have been investigated and an historical analysis has been performed in order to recognize stratospheric aerosols produced by Mount Pinatubos eruption. In all cases the technique was able to detect anomalous particle loading in atmosphere, in an automatic way, without need of any specific transmittance model for the atmosphere or ancillary ground-based measurements. The main merit of this new approach is its effectiveness in recognizing field anomalies also in the presence of a highly variable background as well as its intrinsic exportability ensured by the use of thresholds which are local but automatically generate by using only satellite data at hands. By this way the proposed technique can be numbered among the others environmental applications of RAT approach in which it finds its origin.

In place merging of satellite based atmospheric water vapour measurements

Abstract Atmospheric water vapour plays a key role in the climatology of the Earth. It has traditionally been measured using radiosondes for reasons of instrumental simplicity but these offer limited opportunities for spatial and continuous measurements of dynamic water vapour changes over large areas of the Earths atmosphere. Efforts have recently turned to using satellite remote sensing instruments with different spectral and spatial capabilities to derive measurements of total water vapour content in atmospheric columns or simply precipitable water. The merging of remote sensing data with different spectral and spatial capabilities can result in large biases when independent measurements are not nested correctly to produce the final product. Consequently, such merging of data must take into account the intrinsic time dynamics of measured parameters. In this paper, the impact of atmospheric water vapour dynamics on the merging of satellite-based retrieval of precipitable water estimates is investigated...

Fractality in broken clouds and the scan geometry of new satellite-borne infrared sensors

Cloud scenes observed by the Advanced Visible and Near-Infrared Radiometer on board the Japanese polar platform Advanced Earth Observing Satellite have been analysed to check the validity of power laws extending from the length scale of a few metres to several kilometers. The kind of scaling law we have investigated pertains to cloud morphology and may have important implications for the design of the scan geometry of new satellite-borne infrared sensors aimed at improving the density of clear soundings in frontal systems.

Hyperspectral Data Classification to Support the Radiometric Correction of Thermal Imagery

The derivation of surface temperature from thermal images requires a proper modelling of the spectral characteristics of the observed surfaces, in particular emissivity. Several possible approaches have been developed in literature. A first category of methods relies on the availability of multiple bands in the thermal region, while a second family of methods, which can be applied also with a single channel sensor, requires the derivation of emissivity values from ancillary data.

Detection of Saharan dust by spatial/spectral signatures in VIS-TIR satellite radiances

This paper will face the problem of detecting dust clouds, discriminating them from meteorological clouds, by using multispectral radiances measured from satellite sensors. The possibility to overcome problems related to their very similar spectral signatures by combining an advanced multi-temporal satellite data analysis approach with a peculiar spatial/signature, will be described using as study case a dust-storm event occurred in North Africa in 1997.

Atmospheric water vapor measurements using ground- and satellite-based instrumentation and radiosonde

In this paper we present an intercomparison between ground based lidar, radiosonde and satellite atmospheric water vapor measurements. Comparisons expressed in terms of water vapor profiles, obtained by Raman lidar and simultaneous ballonborne radiosonde, are reported and discussed. The deviation between the two profiles is smaller than 10 percent up to an altitude of 5 km. Furthermore, the intercomparison between lidar and radiosonde data and between lidar and satellite data is performed also in terms of water vapor columnar content. The agreement between lidar and radiosonde columnar content is better than 4 percent. Water vapor contour map are showed in order to demonstrate the high spatial and temporal variability of water vapor in the lower atmosphere. Difficulties in comparing lidar and satellite water vapor columnar contents associated to H2O spatial and temporal variability are discussed in the paper.