-
M. Verdecchia,
E. Coppola,
C. Faccani,
R. Ferretti,
A. Memmo,
M. Montopoli,
G. Rivolta,
T. Paolucci,
E. Picciotti,
A. Santacasa,
B. Tomassetti,
G. Visconti, F. S. Marzano
[show abstract]
[hide abstract]
ABSTRACT: A flood forecast chain, developed at the Centre of Excellence for Remote Sensing and Hydro-Meteorology (CETEMPS) and based
on coupled mesoscale atmospheric and a newly developed distributed hydrological model with in-situ and remote sensing data
integration, is illustrated. The focus is on small-catchment flood forecast in complex topography in Central Italy, but the
developed modelling and processing integrated tools may be easily applied to any geographical and orographic scenario. Emphasis
is put on the integration of numerical models and retrieval algorithms with aim to provide an overview of an objective system
for hydro-meteorological alert-map emission. As an example, the forecast hydro-meteorological chain is applied to a case study
of an extreme event on 23–25 January 2003 and results are discussed.
Meteorology and Atmospheric Physics 04/2012; 101(3):267-285. · 0.90 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Weather radar retrieval, in terms of detection, estimation, and sensitivity, of volcanic ash plumes is dependent not only on the radar system specifications but also on the range and ash cloud distribution. The minimum detectable signal can be increased, for a given radar and ash plume scenario, by decreasing the observation range and increasing the operational frequency and also by exploiting possible polarimetric capabilities. For short-range observations in proximity of the volcano vent, a compact portable system with relatively low power transmitter may be evaluated as a suitable compromise between observational and technological requirements. This paper, starting from the results of a previous study and from the aforementioned issues, is aimed at quantitatively assessing the optimal choices for a portable X-band system with a dual-polarization capability for real-time ash cloud remote sensing. The physical-electromagnetic model of ash particle distributions is systematically reviewed and extended to include nonspherical particle shapes, vesicular composition, silicate content, and orientation phenomena. The radar backscattering response at X-band is simulated and analyzed in terms of self-consistent polarimetric signatures for ash classification purposes and correlation with ash concentration for quantitative retrieval aims. An X-band radar system sensitivity analysis to ash concentration, as a function of radar specifications, range, and ash category, is carried out in trying to assess the expected system performances and limitations.
IEEE Transactions on Geoscience and Remote Sensing 02/2012; · 2.89 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A numerical simulator of satellite microwave radiometric observations of mountainous scenes, developed in a previous study, has been used to predict the relief effects on the measurements of a spaceborne radiometer. For this purpose, the trends of the error due to topography, i.e., the difference between the antenna temperature calculated for a topographically variable surface and that computed for a flat terrain versus the parameters representing the relief, have been analyzed. The analysis has been mainly performed for a mountainous area in the Alps by assuming a simplified land-cover scenario consisting of bare terrain with two roughness conditions (smooth and rough soils) and considering L- and C-bands, i.e., those most suitable for soil moisture retrieval. The results have revealed that the error in satellite microwave radiometric observations is particularly correlated to the mean values of the height and slope of the radiometric pixel, as well as to the standard deviations of the aspect angle and local incidence angle. Both a regression analysis and a neural-network approach have been applied to estimate the error as a function of the parameters representing the relief, using the simulator to build training and test sets. The prediction of the topography effects and their correction in radiometric images have turned out to be feasible, at least for the scenarios considered in this study.
IEEE Transactions on Geoscience and Remote Sensing 10/2011; · 2.89 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Understanding the lunar physical properties has been attracting the interest of scientists for many years. This paper is devoted to a numerical study on the capability of retrieving the thickness of the first layer of regolith as well as the temperature profile behavior from satellite-based multifrequency radiometers at frequencies ranging from 1 to 24 GHz. To this purpose, a forward thermal-electromagnetic numerical model, able to simulate the response of the lunar material in terms of upward brightness temperature ( TB ), has been used. The input parameters of the forward model have been set after a detailed investigation of the scientific literature and available measurements. Different choices of input parameters are possible, and their selection is carefully discussed. By exploiting a Monte Carlo approach to generate a synthetic data set of forward-model simulations, a physically based inversion methodology has been developed using a neural network technique. The latter has been designed to perform, from multifrequency TB 's, the temperature estimation at the lunar surface, the discrimination of the subsurface material type, and the estimate of the near-surface regolith thickness. Results indicate that, within the simplified scenarios obtained by interposing strata of rock, ice, and regolith, the probability of detection of the presence of discontinuities beneath the lunar crust is on the order of 84%. The estimation uncertainty of the near-surface regolith thickness estimation ranges from 11 to 81 cm, whereas for the surface temperature, its estimation uncertainty ranges from about 1.5 K to 3 K, conditioned to the choice of radiometric frequencies and noise levels.
IEEE Transactions on Geoscience and Remote Sensing 10/2011; · 2.89 Impact Factor
-
N. Pierdicca,
F. Rocca,
P. Basili,
S. Bonafoni,
G. Carlesimo,
D. Cimini,
P. Ciotti,
R. Ferretti, F.S. Marzano,
V. Mattioli,
M. Montopoli,
R. Notarpietro,
D. Perissin,
E. Pichelli,
B. Rommen,
G. Venuti
[show abstract]
[hide abstract]
ABSTRACT: Spaceborne Interferometric Synthetic Aperture Radar (InSAR) is a well established technique useful in many land applications, such as tectonic movements, landslide monitoring and digital elevation model extraction. One of its major limitation is the atmospheric effect, and in particular the high water vapour spatial and temporal variability which introduces an unknown delay in the signal propagation. This paper describes the general approach and some results achieved in the framework of an ESA funded project devoted to the mapping of the water vapour with the aim to mitigate its effect in InSAR applications. Ground based (microwave radiometers, radiosoundings, GPS) and spaceborne observations (AMSR-E, MERIS, MODIS) of columnar water vapour were compared with Numerical Weather Prediction model runs in Central Italy during a 15-day experiment. A dense network of GPS receivers was deployed close to Como, in Northern Italy, to complement the operational network in order to derive Zenith Total Delay as well as Slant Delay which can support InSAR processing. A comparison with Atmospheric Phase Screens (APS) derived from a sequence of Envisat multi pass interferometric acquisitions processed using the Permanent Scatters technique on the two test sites has been also performed. The acquired experimental data and their comparison give a valuable idea of what can be done to gather information on water vapour, which, besides InSAR applications, plays a fundamental role in weather prediction and radio propagation studies. The work has been carried out in the framework of an ESA funded project, named "Mitigation of Electromagnetic Transmission errors induced by Atmospheric Water Vapour Effects" (METAWAVE). This paper presents the general approach an the various methodologies exploited in the project, together with the overall intercomparison of the results. In deep details on the comparison with the InSAR APS maps derived by the PS technique, as well as on GPS receiver processing-
-
and water vapour tomography are reported in two companion papers.
Geoscience and Remote Sensing Symposium (IGARSS), 2011 IEEE International; 08/2011
-
[show abstract]
[hide abstract]
ABSTRACT: A physically-oriented statistical prediction of sky-noise temperature intercepted by ground Deep-Space antennas has been developed, based on simulations obtained by using a radiative transfer model approaching the electromagnetic propagation in a scattering medium. A model dependent on attenuation, frequency and elevation angle is proposed for describing the atmospheric mean radiative temperature, which relates sky-noise temperature to attenuation. Model validity ranges from X to lower W band for space research allocated bands and for elevations between 10 deg and 90 degrees.
Antennas and Propagation (EUCAP), Proceedings of the 5th European Conference on; 05/2011
-
[show abstract]
[hide abstract]
ABSTRACT: The sub-glacial Eyjafjöll explosive volcanic eruptions of April and May 2010 are an-alyzed and quantitatively interpreted by using ground-based weather radar data and volcanic ash radar retrieval (VARR) technique. The Eyjafjöll eruptions have been con-tinuously monitored by the Keflavík C-band weather radar, located at a distance of 5 about 155 km from the volcano vent. Considering that the Eyjafjöll volcano is approx-imately 20 km far from the Atlantic Ocean and that the northerly winds stretched the plume toward the mainland Europe, weather radars are the only means to provide an estimate of the total ejected tephra. The VARR methodology is summarized and ap-plied to available radar time series to estimate the plume maximum height, ash particle 10 category, ash volume, ash fallout and ash concentration every 5 min near the vent. Es-timates of the discharge rate of eruption, based on the retrieved ash plume top height, are provided together with an evaluation of the total erupted mass and volume. De-posited ash at ground is also retrieved from radar data by empirically reconstructing the vertical profile of radar reflectivity and estimating the near-surface ash fallout. Radar-15 based retrieval results cannot be compared with ground measurements, due to the lack of the latter, but further demonstrate the unique contribution of these remote sensing products to the understating and modelling of explosive volcanic ash eruptions.
ACPD Chem. Phys. Discuss. 01/2011; 11(11):12367-12409.
-
[show abstract]
[hide abstract]
ABSTRACT: Dual-polarized weather radars are capable to detect and identify different classes of hydrometeors, within stratiform and convective storms, exploiting polarimetric diversity. Among the various techniques, a model-supervised Bayesian method for hydrometeor classification, tuned for S- and X-band polarimetric weather radars, can be effectively applied. Once the hydrometeor class is estimated, the retrieval of their water content can also be statistically carried out. However, the critical issue of X-band radar data processing, and in general of any attenuating wavelength active system, is the intervening path attenuation, which is usually not negligible. Any approach aimed at estimating hydrometeor water content should be able to tackle, at the same time, path attenuation correction, hydrometeor classification uncertainty, and retrieval errors. An integrated iterative Bayesian radar algorithm (IBRA) scheme, based on the availability of the differential phase measurement, is presented in this paper and tested during the International H<sub>2</sub>O Project experiment in Oklahoma in 2002. During the latter campaign, two dual-polarized radars, at S- and X-bands, were deployed and jointly operated with closely matched scanning strategies, giving the opportunity to perform experimental comparisons between coincident measurements at different frequencies. Results of the IBRA technique at X-band are discussed, and the impact of path attenuation correction is quantitatively analyzed by comparing hydrometeor classifications and estimates with those obtained at S-band. The overall results in terms of error budget show a significant improvement with respect to the performance with no path attenuation correction.
IEEE Transactions on Geoscience and Remote Sensing 09/2010; · 2.89 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Five spaceborne X-band synthetic aperture radars (X-SARs) are nowadays operating, and several more will be launched in the coming years. These X-SAR sensors, able to image the Earth's surface at metric resolution, may provide a unique opportunity to measure rainfall over land with spatial resolution of about a few hundred meters due to the moving-target degradation effects. This work is devoted to experimentally demonstrate this X-SAR capability, which can also be exploited to correct synthetic aperture radar (SAR) imagery for rainfall attenuation effects. Several case studies, selected from TerraSAR-X (TSX) overpasses over Europe and the southern U.S. in 2008, are qualitatively analyzed in terms of rainfall signatures. Visual validation of these rainfall SAR signatures is carried out by using available data from ground-based weather radars. A detailed data analysis for the case study of Hurricane ??Gustav?? on September 2, 2008, is carried out to assess a quantitative correlation among X-SAR response and near-surface precipitation rain rate. Two simplified empirical inversion algorithms, based on statistical regression and probability matching, are developed to retrieve rain rate from TSX cross-track ground-range measurements. The TSX-retrieved rain fields are compared to those estimated from the Next Generation Weather Radar (NEXRAD) in Mobile (Alabama, U.S.), showing a root-mean-square error less than 15 mm/h and a correlation of about 0.7.
IEEE Transactions on Geoscience and Remote Sensing 03/2010; · 2.89 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A numerical simulator of satellite microwave-radiometric observations of orographically complex scenes, at various frequencies and observation angles, has been developed. The Simulator of Topographic Artefacts in MIcrowave RAdiometry (STAMIRA) exploits the information on the relief, extracted from a digital elevation model, and has been applied to a test case concerning a mountainous area in the Alps by assuming a simplified land-cover scenario consisting of bare terrain with two kinds of roughness (smooth and rough soils). The 1-10-GHz range has been considered to determine scattering and emission of soil and a nonscattering atmosphere has been supposed. The simulations have shown the large impact of the rotation of the polarization plane and of the brightness-temperature enhancement occurring for facets illuminated by radiation from the surrounding elevated terrain with respect to flat surfaces which scatter atmospheric downward radiation only. By considering also the antenna-pattern integration and the dependence of surface emissivity on the local observation angle, we have found that, for our case study, the brightness temperature is larger than that measured observing a flat terrain at horizontal polarization. At vertical polarization, the opposite occurs. These differences are analyzed and quantified.
IEEE Transactions on Geoscience and Remote Sensing 02/2010; · 2.89 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The microphysical and dynamical features of volcanic clouds, due to Plinian and sub-Plinian eruptions, can be quantitatively monitored by using ground-based microwave weather radars. In order to demonstrate the unique potential of this remote sensing technique, a case study of a subglacial volcanic eruption, occurred in Iceland in November 2004, is described and analyzed. Volume data, acquired by a C-band ground-based weather radar, are processed to automatically classify and estimate ash particle concentration. The ash retrieval physical-statistical algorithm is based on a backscattering microphysical model of fine, coarse, and lapilli ash particles, used within a Bayesian classification and optimal regression algorithm. A sensitivity analysis is carried out to evaluate the overall error budget and the possible impact of nonprecipitating liquid and ice cloud droplets when mixed with ash particles. The evolution of the Icelandic eruption is discussed in terms of radar measurements and products, pointing out the unique features, the current limitations, and future improvements of radar remote sensing of volcanic plumes.
IEEE Transactions on Geoscience and Remote Sensing 02/2010; · 2.89 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: This paper reports on the potential of combining elliptical-orbit Flower constellations with millimeter-wave radiometry and radio-occultation, a mission concept briefly named FloRad2. The advantages of flower constellation with respect to conventional orbits are discussed, includ-ing the flexibility ensuring increasing coverage with separate launches. Millimeter-wave radiometry and radio-occultation receivers provide the advantage to design fairly compact pay-loads that comply well with current technology of mini-satellites. Millimeter-wave radiometry and radio-occultation techniques are somewhat complementary and an optimal combination of these observations results in atmospheric products with enhanced vertical and horizontal resolutions. Thus, the combination of small, light payloads employ-ing millimeter-wave radiometry and radio-occultation with Flower elliptical-orbit constellations may result in an opti-mal compromise between retrieval performances and system complexity that is ideal for continued long-term missions with meteorological and climatological applications.
01/2010; 25:167-177.
-
[show abstract]
[hide abstract]
ABSTRACT: The local distribution of water vapour in the urban area of Rome has been studied using both a high resolution mesoscale model (MM5) and Earth Remote Sensing-1 (ERS-1) satellite radar data. Interferometric Synthetic Aperture Radar (InSAR) techniques, after the removal of all other geometric effects, estimate excess path length variation between two different SAR acquisitions (Atmospheric Phase Screen: APS). APS are strictly related to the variations of the water vapour content along the radar line of sight. To the aim of assessing the MM5 ability to reproduce the gross features of the Integrated Water Vapour (IWV) spatial distribution, as a first step ECMWF IWV has been used as benchmark against which the high resolution MM5 model and InSAR APS maps have been compared. As a following step, the high resolution IWV MM5 maps have been compared with both InSAR and surface meteorological data. The results show that the high resolution IWV model maps compare well with the InSAR ones. Support to this finding is obtained by semivariogram analysis that clearly shows good agreement beside from a model bias.
Natural Hazards and Earth System Sciences. 01/2010;
-
[show abstract]
[hide abstract]
ABSTRACT: An improved methodology for investigating mesoscale model microphysics is presented and discussed for a case study. Polarimetric radar data are used to assess numerical weather prediction (NWP) model's skill in reproducing the microphysical features of severe rainfall. To this aim, an event of deep convection, developed on 20 May 2003 in the Po Valley (Italy), is analyzed. During the selected case study, two weather radars, sited in Gattatico and San Pietro Capofiume (near Bologna, Italy), detected a deep-convective and hail cell with a large inner graupel core which reached the ground, as was reported by local weather authorities and citizens. A hydrometeor classification algorithm, based on a Bayesian approach and a radar simulator model, are used to retrieve the vertical structure of the storm and characterize its ground effects. These products are used for evaluating the sensitivity of NWP models with respect to the graupel density, described in terms of the intercept parameter of the graupel size distribution and its depositional velocity. To this purpose two mesoscale NWP models, specifically COSMO-LAMI and MM5-V3, are used at high spatial resolution. Their ability in reproducing the vertical and the horizontal structure and the microphysical distribution of the major convective cell is evaluated. Both models show large sensitivity to different microphysical settings and a capability to reproduce fairly well the observed hail cell. Ground-radar reflectivity fields and the hydrometeor vertical structure are correctly simulated by both NWP models as opposed to a failure in reproducing the graupel distribution near the ground.
Atmospheric Chemistry and Physics Discussions. 01/2010;
-
[show abstract]
[hide abstract]
ABSTRACT: X-band Synthetic Aperture Radars (X-SARs), able to image the Earth's surface at metric resolution, may provide a unique opportunity to measure rainfall over land with spatial resolution of about few hundred meters, due to the atmospheric moving-target degradation effects. This capability has become very appealing due to the recent launch of several X-SAR satellites, even though several remote sensing issues are still open. This work is devoted to: (i) explore the potential of X-band high-resolution detection and retrieval of rainfall fields from space using X-SAR signal backscattering amplitude and interferometric phase; (ii) evaluate the effects of spatial resolution degradation by precipitation and inhomogeneous beam filling when comparing to other satellite-based sensors. Our X-SAR analysis of precipitation effects has been carried out using both a TerraSAR-X (TSX) case study of Hurricane "Gustav" in 2008 over Mississippi (USA) and a COSMO-SkyMed (CSK) X-SAR case study of orographic rainfall over Central Italy in 2009. For the TSX case study the near-surface rain rate has been retrieved from the normalized radar cross section by means of a modified regression empirical algorithm (MREA). A relatively simple method to account for the geometric effect of X-SAR observation on estimated rainfall rate and first-order volumetric effects has been developed and applied. The TSX-retrieved rain fields have been compared to those estimated from the Next Generation Weather Radar (NEXRAD) in Mobile (AL, USA). The rainfall detection capability of X-SAR has been tested on the CSK case study using the repeat-pass coherence response and qualitatively comparing its signature with ground-based Mt. Midia C-band radar in central Italy. A numerical simulator to represent the effect of the spatial resolution and the antenna pattern of TRMM satellite Precipitation Radar (PR) and Microwave Imager (TMI), using high-resolution TSX-retrieved rain images, has been also set up in order to evaluate the rainfall beam filling phenomenon. As expected, the spatial average can modify the statistics of the high-resolution precipitation fields, strongly reducing its dynamics in a way non-linearly dependent on the rainrate local average value.
Hydrology and Earth System Sciences Discussions. 01/2010;
-
[show abstract]
[hide abstract]
ABSTRACT: In this paper, the design of a minisatellite FLOwer constellation (FC), deploying millimeter-wave (MMW) scanning RADiometers, namely, FLORAD, and devoted to tropospheric observations, is analyzed and discussed. The FLORAD mission is aimed at the retrieval of thermal and hydrological properties of the troposphere, specifically temperature profile, water-vapor profile, cloud liquid content, and rainfall and snowfall rate. The goal of frequent revisit time at regional scale, coupled with quasi-global coverage and relatively high spatial resolution, is here called pseudogeostationary scale and implemented through a FC of three minisatellites in elliptical orbits. FCs are built on compatible (resonant) orbits and can offer several degrees of freedom in their design. The payload MMW channels for tropospheric retrieval were selected following the ranking based on a reduced-entropy method between 90 and 230 GHz. Various configurations of the MMW radiometer multiband channels are investigated, pointing out the tradeoff between performances and complexity within the constraint of minisatellite platform. Statistical inversion schemes are employed to quantify the overall accuracy of the selected MMW radiometer configurations.
IEEE Transactions on Geoscience and Remote Sensing 10/2009; · 2.89 Impact Factor
-
N. Pierdicca,
F. Rocca,
B. Rommen,
P. Basili,
S. Bonafoni,
D. Cimini,
P. Ciotti,
F. Consalvi,
R. Ferretti,
W. Foster, [......],
V. Mattioli,
A. Mazzoni,
M. Montopoli,
R. Notarpietro,
S. Padmanabhan,
D. Perissin,
E. Pichelli,
S. Reising,
S. Sahoo,
G. Venuti
[show abstract]
[hide abstract]
ABSTRACT: Spaceborne Interferometric Synthetic Aperture Radar (InSAR) is a well established technique useful in many land applications, such as monitoring tectonic movements and landslides or extracting digital elevation models. One of its major limitations is the atmospheric variability, and in particular the high water vapor spatial and temporal variability, which introduces an unknown delay in the signal propagation. On the other hand, these effects might be exploited, so as InSAR could become a tool for highresolution water vapor mapping. This paper describes the approach and some preliminary results achieved in the framework of an ESA funded project devoted to the mitigation of the water vapor effects in InSAR applications. Although very preliminary, the acquired experimental data and their comparison give a first idea of what can be done to gather valuable information on water vapor, which play a fundamental role in weather prediction and radio propagation studies.
Geoscience and Remote Sensing Symposium,2009 IEEE International,IGARSS 2009; 08/2009
-
[show abstract]
[hide abstract]
ABSTRACT: Radio-propagation parameters are modeled by means of a fully-polarimetric model of hydrometeor backscattering. To this aim a large set of raindrop size distributions (RSDs), collected at various locations such as Japan, Greece, UK and USA has been used. Co-polar specific attenuation, differential specific attenuation, co-polar phase shift and differential phase shift at horizontal and vertical polarizations have been simulated at Ku (12.5 GHz), K (19.7 GHz), Ka (39.6 GHz), V (49.5 GHz) and W bands (92 GHz). A partition of rain rate as convective and stratiform regimes, based on a microphysical approach and applied to the time series of RSD parameters, has been introduced to better investigate and characterize the radio-propagation parameters relationships with respect to rain rate. A regression analysis is performed and coefficients to predict radio propagation parameters, at the above mentioned frequencies, as a function of rain rate, are provided.
Antennas and Propagation, 2009. EuCAP 2009. 3rd European Conference on; 04/2009
-
[show abstract]
[hide abstract]
ABSTRACT: The development of a stochastic spatial downscaling algorithm, able to enhance the spatial resolution of rain or attenuation fields considered as input, is illustrated. The proposed algorithm takes advantages from the spatial characterization of the rain fields derived from numerical weather prediction models (NWPM) simulations at coarse spatial resolution. The associated attenuation field at frequencies higher than X band are derived from a numerical scattering simulator based on the T-matrix approach. The stochastic spatial downscaling technique will be described and used to provide an ensemble of possible realizations at a spatial resolution higher than that available at the output of the MM5 simulations which has been taken, for our purpose, as the reference NWPM. The developed methodology will be applied and discussed for some case studies where MM5 outputs, rain-gauge data and ground-based radar observations were available.
Antennas and Propagation, 2009. EuCAP 2009. 3rd European Conference on; 04/2009
-
[show abstract]
[hide abstract]
ABSTRACT: Model-oriented methods to predict antenna noise temperature due to rainfall along slant paths are developed and illustrated for communication systems at Ka band and above. The adopted sky noise Eddington model (SNEM) relies on an accurate analytical solution of the radiative transfer equation and on stratiform and convective rainfall stratified structures, synthetically generated from cloud-resolving model statistics. The approach to predict antenna noise temperature is based on the multiple regression analysis, trained by SNEM-derived cloud radiative datasets. In order to test the proposed prediction technique, measurements of the ITALSAT satellite groundstation at Pomezia (Rome, Italy) are taken into consideration for 2 case studies. Combined data from the ITALSAT three-beacon receiver at 18.7, 39.6 and 49.5 GHz and from a three-channel microwave radiometer at 13.0, 23.8 and 31.6 GHz are processed and discussed.
Antennas and Propagation, 2009. EuCAP 2009. 3rd European Conference on; 04/2009
