The correlation of visibility noise and its impact on the radiometric resolution of an aperture synthesis radiometer

The correlation between the visibility samples' noise of an aperture synthesis radiometer are required for the computation of the recovered temperature noise of a given pixel and of the improvement introduced by baseline redundance. A general expression for this correlation and noise examples for a linear array are presented.Peer ReviewedPostprint (published version

Ocean salinity observations with SMOS mission

The purpose of this paper is to present the capabilities of SMOS (Soil Moisture and Ocean Salinity mission) for the global mapping of ocean salinity from space. SMOS has been selected by the European Space Agency as the second Earth Explorer Opportunity with a launch date in June 2005. The sensor embarked on SMOS is MIRAS, a Microwave Imaging Radiometer with Aperture Synthesis. MIRAS works at L-band, in the two-polarisations, and has full polarimetric capability. The measurement of sea surface salinity (SSS) is one of the challenges of SMOS. This paper presents first the scientific requirements for a number of oceanographic applications. The scientific requirements are then translated into instrument accuracy, sensitivity, stability and spatial resolution. Major sources of error in the retrieval of ocean salinity will be addressed through an experimental campaign which is described.Peer ReviewedPostprint (published version

The Social Reproduction Crisis During the COVID-19 Pandemic in Barcelona: Potentialities and Limitations

The outbreak of the social pandemic brought to the foreground the crisis of social reproduction afflicting our societies. However, this new visibility of the importance of care work and the emergence of mutual support networks was not a sufficient condition for the politicization of the reproductive sphere to take place, contrary to what happened during the 2008 crisis. This paper aims to comprehend the reasons why such politicization did not occur by means of a case-study carried out with four focus-groups made up of representatives of mutual support networks established in Barcelona to respond to the needs of the most vulnerable groups of the population. The achieved results show the limits of social reproduction theory to explain politicization theories, as it does not sufficiently acknowledge the state’s agency

Extension of Kirchhoff method under stationary phase approximation to determination of polarimetric thermal emission from the sea

Wind direction over the sea can be determined from radiometric measurements of the third Stokes parameter (TU). The Kirchhoff method is extended under the stationary phase approximation to compute the dependence of TU on frequency, wind speed and incidence angle. Numerical predictions, in agreement with experimental measurements, are presented.Peer Reviewe

From the principle of authority to criminal authoritarianism. Rethinking the relations between the Spanish State and Catalunya

Como parte de las voces que referencian a los pueblos, se presenta una entrevista de Clara Camps Calvet e Ignasi Bernat Molina a August Gil Matamala, realizada en el marco del proyecto de investigación: “Conflicte a Catalunya i repressió política” (2017 RICIP-0015) financiado por el Institut Català Internacional per la Pau (ICIP). Gil Matamala (1934) es abogado, con una larga trayectoria en el ámbito de la defensa de los derechos humanos. Desde muy joven se implicó en la lucha contra la dictadura franquista. En esta entrevista, su voz sólida, crítica y resistente nos ayudan a entender de forma muy clara la idiosincrasia del Estado Español y los principios que lo rigen. Su larga experiencia en la defensa de militantes perseguidos políticamente ante los tribunales españoles, tanto durante el franquismo como en democracia, nos permiten entender por qué hoy en el Estado Español sigue existiendo la persecución política, presos políticos y exiliados de las persones que defienden los derechos y la soberanía de los pueblos.As part of the voices that refer to the people, an interview by Clara Camps Calvet and Ignasi Bernat Molina with August Gil Matamala is presented, carried out in the framework of the research project: “Conflicte a Catalunya i repressió política” (2017 RICIP-0015) funded by the Institut Català Internacional per la Pau (ICIP). Gil Matamala (1934) is a lawyer, with a long career in the field of human rights advocacy. From a very young age he was involved in the struggle against the Franco dictatorship. In this interview, his solid, critical and resistant voice helps us to understand very clearly the idiosyncrasy of the Spanish State and the principles that govern it. His long experience in the defense of politically persecuted militants before the Spanish courts, both during the Franco regime and in democracy, allow us to understand why today in the Spanish State there is still political persecution, political prisoners and exiles of people who defend the rights and sovereignty of the people.Facultad de Ciencias Jurídicas y Sociale

Millimeter-wave aperture synthesis radiometry for snow and ice mapping

An outline design for a dual-band mm-wave polarimetric SAIR has been presented and is considered to be tractable. The envisaged application is for snow and ice mapping and ocean wind vector measurement. The vastly increased complexity of the high-frequency waveband may not be justified by the scientific benefit and operation at an additional lower frequency such as 18 GHz may give improved classification, though with reduced spatial resolution. The authors describe the outline design for a polarimetric, mm-wave SAIR. One-dimensional aperture synthesis employs a hybrid technique in which a long linear array of real-aperture stick antennas form over-lapping fan beams on the ground and aperture synthesis within the fan beams enables synthesis of the mm-wave image. Critical aspects for building a high-resolution, mm-wave ESTAR are system calibration and the construction of stick antennas that will be 3 m long and about half a wavelength wide.Peer ReviewedPostprint (published version

Baseline redundancy and radiometric sensitivity: a critical review

When computing the radiometric resolution of an interferometric radiometer the correlation among the errors of different baselines is usually assumed negligible. ln this way: a) the radiometric sensitivity turns out to be pixel independent (except for antenna pattern effects), and b) the error of the average of P redundant baselines is reduced by a factor of (P)1/2. While this may be the case in radioastronomy applications, for an on-board instrument where all the baselines are measured at the same time interval the errors will actually be correlated. This has two effects: a) The radiometric resolution changes from pixel to pixel and b) the radiometric resolution improvement introduced by redundance is reduced as compared with the case of independent errors. In this paper this correlation is computed and the results obtained are applied, first, to a fully redundant (all possible baselines are actually measured) filled linear array to analyze the actual radiometric improvement, and, next, to the same array without redundance to investigate the dependence of sensitivity on pixel information.Peer ReviewedPostprint (published version

Radiometric sensitivity computation in aperture synthesis interferometric radiometry

This paper is concerned with the radiometric sensitivity computation of an aperture synthesis interferometric radiometer devoted to Earth observation. The impact of system parameters and the use of simultaneous redundant measurements are analyzed. The interferometric radiometer uncertainty principle is presented; it quantifies the relationship between radiometric sensitivity and angular resolution.Peer Reviewe