A New NDSA (Normalized Differential Spectral Attenuation) Measurement Campaign for Estimating Water Vapor along a Radio Link

Luca Facheris; Fabrizio Cuccoli; Ugo Cortesi; Samuele del Bianco; Marco Gai; Giovanni Macelloni; Francesco Montomoli

doi:10.3390/rs16193735

Remote Sensing (Oct 2024)

A New NDSA (Normalized Differential Spectral Attenuation) Measurement Campaign for Estimating Water Vapor along a Radio Link

Luca Facheris,
Fabrizio Cuccoli,
Ugo Cortesi,
Samuele del Bianco,
Marco Gai,
Giovanni Macelloni,
Francesco Montomoli

Affiliations

Luca Facheris: Department of Information Engineering, University of Florence, Via di Santa Marta 3, 50139 Florence, Italy
Fabrizio Cuccoli: Radar and Surveillance Systems (RASS) Laboratory, Interuniversity National Consortium for Telecommunications (CNIT), Galleria G.B. Gerace 14, 56124 Pisa, Italy
Ugo Cortesi: Institute of Applied Physics “Nello Carrara” of the National Research Council (IFAC-CNR), Via Madonna del Piano 10, Sesto Fiorentino, 50019 Florence, Italy
Samuele del Bianco: Institute of Applied Physics “Nello Carrara” of the National Research Council (IFAC-CNR), Via Madonna del Piano 10, Sesto Fiorentino, 50019 Florence, Italy
Marco Gai: Institute of Applied Physics “Nello Carrara” of the National Research Council (IFAC-CNR), Via Madonna del Piano 10, Sesto Fiorentino, 50019 Florence, Italy
Giovanni Macelloni: Institute of Applied Physics “Nello Carrara” of the National Research Council (IFAC-CNR), Via Madonna del Piano 10, Sesto Fiorentino, 50019 Florence, Italy
Francesco Montomoli: Institute of Applied Physics “Nello Carrara” of the National Research Council (IFAC-CNR), Via Madonna del Piano 10, Sesto Fiorentino, 50019 Florence, Italy

DOI: https://doi.org/10.3390/rs16193735
Journal volume & issue: Vol. 16, no. 19
p. 3735

Abstract

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The Normalized Differential Spectral Attenuation (NDSA) technique was proposed years ago as an active method for measuring integrated water vapor (IWV) along a Ku/K-band radio link immersed (totally or partially) in the troposphere. The approach is of the active kind, as it relies on the transmission of a couple of sinusoidal signals, whose power is measured at the receiver, thus providing the differential attenuation measurements from which IWV estimates can be in turn derived. In 2018, a prototype instrument providing such differential attenuation measurements was completed and set up for a first measurement campaign aimed at demonstrating the NDSA method. By the end of June 2022, the instrument was profoundly modified and upgraded so that a second measurement campaign could be carried out from 1 August to 30 November 2022. The transmitter was placed on the top of Monte Gomito (44.1277°lat, 10.6434°lon, 1892 m a.s.l.) and the receiver on the roof of the Department of Information Engineering of the University of Florence (43.7985°lat, 11.2528°lon, 50 m a.s.l.). The resulting radio link length was 61.15 km. Four ground weather stations of the regional weather service were selected among those available. In this paper, we describe the upgraded instrument and present the outcomes of the new measurement campaign, whose purpose was mainly to compare the IWV estimates provided by the instrument with the ground sensor measurements of air temperature, air humidity, barometric pressure, and rainfall. In particular, we show that the temporal trends of the two IWV estimates are qualitatively consistent, and that the instrument is able to provide IWV estimates also in the presence of fog and rainfall. Conversely, a quantitative evaluation through comparison with IWV data from point weather station measurements appears challenging due to the significant spatial variability in temperature and relative humidity, even between couples of stations that are quite close to each other.

Published in Remote Sensing

ISSN: 2072-4292 (Online)
Publisher: MDPI AG
Country of publisher: Switzerland
LCC subjects: Science
Website: http://www.mdpi.com/journal/remotesensing/

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