Fabrizio Cuccoli

Impact of tropospheric scintillation in the Ku/K bands on the communications between two LEO satellites in a radio occultation geometry

A theoretical analysis of the impact of clear-air tropospheric scintillation on a radio occultation link between two low Earth orbit satellites in K- and Ku-bands is presented, with particular reference to differential approaches for the measure of the total content of water vapor. The troposphere is described as a spherically symmetric turbulent medium satisfying Kolmogorov theory. Rytovs first iteration solution for weak fluctuations is used to derive an expression for the variance of amplitude fluctuations of the wave as well as their spectrum and the correlation between fluctuations at different frequencies. The validity of the assumptions made and the influence of atmospheric parameters on the quantities of interest are also investigated and discussed. Finally, numerical results are presented to provide an estimate of the level of scintillation-induced disturbances

Infrared tomographic system for monitoring the two-dimensional distribution of atmospheric pollution over limited areas

The authors analyze the feasibility and performance of a particular tomographic system for atmospheric pollution monitoring over limited areas (e.g. urban areas). Such a system exploits attenuation-based infrared measurements of the average concentration of the fundamental molecular species of pollutants along rectilinear paths. First, the paper demonstrates the feasibility of an apparatus based on semiconductor infrared laser diode transmitters and passive retroreflectors, capable of measuring the average concentration of pollutants along rectilinear paths with 2 km maximum length, by exploiting their infrared absorption properties. For each gaseous species of interest, the optimal wavelength is then singled out, with the purpose of applying the derivative method for measuring the corresponding average atmospheric concentration. The optimal wavelengths are determined based on both absorption data of atmospheric components and plausible ranges of variation of their concentration. Finally, the authors present simulations carried out to evaluate the reconstruction of spatial concentration fields of several air pollutants, obtained through a tomographic inversion algorithm exploiting simultaneous attenuation measurements made along different infrared links. Two different network topologies for such measurements are considered.

An application of tomographic reconstruction of atmospheric CO/sub 2/ over a volcanic site based on open-path IR laser measurements

The southern area of Italy is characterized by the presence of many active volcanic areas. In Pozzuoli (Naples, Italy), an urban area characterized by high volcanic risk, a gas emitting site is present. A high percentage of CO/sub 2/ is emitted, whose atmospheric concentration measurement is an important task in many environmental and scientific applications. In this paper, we describe the utilization over that area of a mobile infrared (IR) laser system, able to measure the CO/sub 2/ concentration along rectilinear atmospheric paths up to 1-km length, and the result of tomographic processing applied to retrieve a two-dimensional CO/sub 2/ concentration field. The laser system computes the link averaged concentration by processing the received IR laser radiation propagated along an open-air rectilinear link connecting the transmitter/receiver laser unit and a passive retroreflector device. A one-day measurement campaign has been made and 15 different atmospheric propagation links were considered moving the transmitter/receiver unit and some retroreflectors.

Advanced Polarimetric Doppler Weather Radar Simulator

The Advanced Polarimetric Doppler Weather Radar Simulator (APDWRS) capable of generating I&Q time series voltages for a ground based fully-polarimetric Doppler weather radar is described in this paper. The Weather Research and Forecast (WRF) model is used in conjunction with the T-Matrix code to generate radar signals according to the propagation-modified covariance matrix. Mixtures of rain, hail, graupel and snow hydrometeors relative to a realistic weather phenomenon are considered. The polarimetric and Doppler observables estimated from the simulated radar signals showed a good agreement with those found in previous observations.

Estimate of the tropospherical water vapor through microwave attenuation measurements in atmosphere

The objective of this paper is to proceed, by investigating the statistics of simulated measurements based on a large dataset of radiosonde profiles, to assess the feasibility of active systems providing water vapor profile information based on Earth-satellite multifrequency differential attenuation measurements made in the 18-22-GHz range. Recently, in fact, we pointed out the potential and the advantages of such measurements, showing in particular how a spectral sensitivity parameter could be exploited to provide the total water vapor content and further information about the shape of its vertical profile. In this work, we present an in-depth statistical analysis of the relationship between the spectral sensitivity parameter and the water vapor content at different tropospheric layers. Furthermore, we discuss the performance of a simple amplitude modulation transmit-receive system that could be adopted to provide the sensitivity measurements. It is shown that a dual-frequency system can directly provide with good accuracy the columnar water vapor content separately from the content of the 3-9 km atmospheric layer.

Microwave attenuation measurements in satellite-ground links: the potential of spectral analysis for water vapor profiles retrieval

The authors address the problem of estimating vertical profiles of atmospheric water vapor by means of attenuation measurements simultaneously made at different frequencies along a vertical satellite-ground link. The operating frequencies selected are those around the spectral absorption lines of water vapor at 22.235 GHz. A simulation is presented of multifrequency attenuation measurements, based on an atmospheric propagation model and on radiosonde data providing true profiles of temperature, pressure, and water vapor. The results indicate that such multifrequency measurements are correlated to variations of the vertical profiles of water vapor. It is therefore expected that vertical detail of such profiles depends on number and position of the frequencies utilized.

Radio base network and tomographic processing for real time estimation of the rainfall rate fields

In this paper, we propose a novel remote sensing method that is adequate for rainfall rate measurements in real time by means of tomographic processing applied to power attenuation measurements made across the microwave links defined by radio base station networks for mobile communication systems. A description of the tomographic algorithms we developed is presented together with some simulation results. These concern rainfall rate estimation applying such algorithms to the current radio base station arrangement over the city of Florence, Italy, while the rainfall field is simulated through weather radar data.

Genetic Algorithms for the tomographic reconstruction of 2D concentration fields of atmospheric gas

A Genetic Algorithm for environmental tomographic applications has been developed. This algorithm has been designed to be applied on the reconstruction of 2D concentration fields of atmospheric gas whose integral measurements are obtained by an open path tomographic system based on IR laser devices. Here, we focus on the performance analysis of the genetic reconstruction algorithm applied to simulated two-dimensional scalar fields by processing a set of one dimensional measurements.

Validation of the Advanced Polarimetric Doppler Weather Radar Simulator with Polar55C real observations

A preliminary validation of the Advanced Polarimetric Doppler Weather Radar Simulator (APDWRS) with real data is described in this paper. The APDWRS is used to reproduce an observation of a severe storm event which took place on the 15th of October 2012 over the Tyrrenian coast. One PPI scan performed by the dual polarization C-band Polar 55C weather radar at 17:30 UTC is simulated using APDWRS with meteorological data from the Weather Research and Forecast (WRF) model as input. The validity of the simulation is then compared both in the spatial domain and statistically observing the differences in the relationships between observables in real and simulated case.

Coordinate Registration Method based on Sea/Land Transitions Identification for Over-the-Horizon Sky-Wave Radar: Numerical Model and Basic Performance Requirements

We propose an approach to the problem of range coordinate registration (CR) for HF band over-the-horizon sky-wave radar (OTHR-SW) signals on a single pulse basis. The approach is based on the a priori knowledge of the displacement of the sea/land transitions within the area illuminated by the radar antenna beam. It takes advantage of the geomorphological structure of the surveillance area, which is exploited to build a surface correlation mask that is in turn used as a geographic reference for the received radar echo. The method is based on the maximization of the cross-correlation between the received radar echo and the surface mask signatures. We describe first an extended numerical model of the whole HF OTHR-SW scenario for simulating the received signal, then we show the results of the application of the method under simplifying operative hypotheses that allow to point out the minimum requirements in terms of received signal-to-noise ratio (SNR) and differential sea/land backscattering coefficient for achieving given accuracies in the range estimates.