SMOS instrument performance after more than 11 years in orbit

ESA's Soil Moisture and Ocean Salinity (SMOS) mission [1] has been in orbit for over 11 years, and its Microwave Imaging Radiometer with Aperture Synthesis (MIRAS) in two dimensions keeps being fully operational. This II-year long lifetime of SMOS, so far, has enabled the calibration and Level-1 processor team to improve the calibration procedures and the image reconstruction resulting in a new version of the Level-1 data processor, v724. To present the main performance features of this new version and the improvement in the calibration procedures constitute the main objective and content of this presentation.Peer ReviewedArticle signat per 32 autors/es: Manuel Martín-Neira(1), Roger Oliva(2) , Raúl Onrubia(2) , Ignasi Corbella(3), Nuria Duffo(3), Roselena Rubino(3), Juha Kainulainen(4), Josep Closa(5), Albert Zurita(5), Javier del Castillo(5), François Cabot(6), Ali Khazaal(6), Eric Anterrieu(6), Jose Barbosa(7), Gonçalo Lopes(8), Daniel Barros(8), Joe Tenerelli(9), Raúl Díez-García(10), Verena Rodríguez(10) , Jorge Fauste(14) , José María Castro Cerón(15) , Antonio Turiel(11), Verónica González-Gambau(11), Raffaele Crapolicchio(12), Lorenzo Di Ciolo(16) , Giovanni Macelloni(13), Marco Brogioni(13), Francesco Montomoli(13), Pierre Vogel(1), Berta Hoyos Ortega(1), Elena Checa Cortés(1), Martin Suess(1) // (1) European Space Agency, ESTEC, Noordwijk, The Netherlands; (2)Zenithal Blue Technologies, Barcelona, Spain; (3) Remote Sensing Laboratory, Universitat Politècnica de Catalunya, Barcelona, Spain; (4) Harp Technologies Ltd., Espoo, Finland; (5) Airbus Defence and Space, Madrid, Spain; (6) CESBIO, Toulouse, France; (7) RDA, Zürich, Switzerland; (8) DEIMOS, Lisbon, Portugal; (9) OceanDataLab, Brest, France; (10) Telespazio UK Ltd, ESAC, Villanueva de la Cañada, Spain; (11) SMOS Barcelona Expert Centre, Barcelona, Spain; (12) European Space Agency, ESRIN, Frascati, Italy; (13) Institute of Applied Physics, Florence, Italy; (14) European Space Agency, ESAC, Villanueva de la Cañada, Spain; (15) ISDEFE, ESAC, Villanueva de la Cañada, Spain; (16) Serco Italia S.p.A., Frascati, Italy.Postprint (author's final draft

A pre-correlation RFI mitigation algorithm for L-band interferometric radiometers

Radio Frequency Interference (RFI) is a major concern for both real and synthetic aperture radiometers. After the lessons learnt from SMOS, ESA is preparing the next generation of L-band interferometric radiometers with RFI mitigation integrated into the cross-correlators. This work presents a preliminary design and results of a pre-correlation RFI mitigation algorithm tailored for interferometric radiometers. The results show that the correlation error introduced by the RFI is reduced on average to the half, with peaks of 20 dB of mitigation.Peer ReviewedPostprint (author's final draft

RFI detection and mitigation for advanced correlators in interferometric radiometers

This work presents the first RFI detection and mitigation algorithm for the interferometric radiometers that will be implemented in its correlator unit. The algorithm operates in the time and frequency domains, applying polarimetric and statistical tests in both domains, and exhibiting a tunable and arbitrary low probability of false alarm. It is scalable to a configurable number of receivers, and it is optimized in terms of quantization bits and the implementation of the cross-correlations in the time or frequency domains for hardware resource saving. New features of this algorithm are the computation of the Stokes parameters per frequency bin in the Short-Time Fourier Transform and a new parameter called Polarimetric Kurtosis. If RFI is detected in one domain or in both, it is removed using the calculated blanking masks. The optimum algorithm parameters are computed, such as length of the FFTs, the threshold selection for a given probability of false alarm, and the selection of the blanking masks. Last, an important result refers to the application of Parseval’s theorem for the computation of the cross-correlations in the frequency domain, instead of in the time domain, which is more efficient and leads to smaller errors even when using moderate quantization levels. The algorithm has been developed in the framework of the ESA’s technology preparation for a potential L-band radiometer mission beyond SMOS. However, it is also applicable to (polarimetric) real aperture radiometers, and its performance would improve if more than one bit is used in the signal quantization.This research was funded by ESA, grant number ITT AO9359, by project SPOT: Sensing with Pioneering Opportunistic Techniques grant RTI2018-099008-B-C21/AEI/10.13039/501100011033, and the grant for recruitment of early stage research staff of the Agència de Gestió d’Ajuts Universitaris i de Recerca (AGAUR) Generalitat de Catalunya, Spain (FISDUR2020/105).Peer ReviewedPostprint (published version

SMOS instrument performance and calibration after six years in orbit

ESA's Soil Moisture and Ocean Salinity (SMOS) mission, launched 2-Nov-2009, has been in orbit for over 6 years, and its Microwave Imaging Radiometer with Aperture Synthesis (MIRAS) in two dimensions keeps working well. The calibration strategy remains overall as established after the commissioning phase, with a few improvements. The data for this whole period has been reprocessed with a new fully polarimetric version of the Level-1 processor which includes a refined calibration schema for the antenna losses. This reprocessing has allowed the assessment of an improved performance benchmark. An overview of the results and the progress achieved in both calibration and image reconstruction is presented in this contribution.Peer ReviewedPostprint (author's final draft

Flow modelling in compound channels

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN039850 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Towards a SMOS operational mission: SMOSOps-Hexagonal

The Microwave Imaging Radiometer with Aperture Synthesis (MIRAS) on-board the Soil Moisture and Ocean Salinity (SMOS) mission is providing useful data since November 2009, and proving the potential of 2D interferometry from space. With the end of its nominal operation phase in November 2012, the mission is expected to extend its lifetime for at least more than two additional years. Along with all the current improvements on data processing and exploitation, the SMOS trail might need to be continued with the aim of providing data to the users in the coming years. This paper presents a SMOS follow-on operational mission which is the result of integrating the actual lessons learnt from MIRAS with a novel hexagonal array geometry, proving robustness against radio-frequency interferences (RFI) and receiver failures. The performance and the instrument architecture enhancements are exposed, along with a practical deployment solution.Peer Reviewe

SMOS instrument performance and calibration after 6 years in orbit

ESA’s Soil Moisture and Ocean Salinity (SMOS) mission has been in orbit for over 6 years, and its Microwave Imaging Radiometer with Aperture Synthesis (MIRAS) in two dimensions keeps working well. The data for almost this whole period has been reprocessed with the new fully polarimetric version (v620) of the Level-1 processor which also includes refined calibration schema for the antenna losses. This reprocessing has allowed the assessment of an improved performance benchmark, a better understanding of the observations, and the preparation of a new version (v700) of the Level-1 processor with further potential.Postprint (author's final draft

SMOS instrument performance and calibration after 6 years in orbit

ESA’s Soil Moisture and Ocean Salinity (SMOS) mission has been in orbit for over 6 years, and its Microwave Imaging Radiometer with Aperture Synthesis (MIRAS) in two dimensions keeps working well. The data for almost this whole period has been reprocessed with the new fully polarimetric version (v620) of the Level-1 processor which also includes refined calibration schema for the antenna losses. This reprocessing has allowed the assessment of an improved performance benchmark, a better understanding of the observations, and the preparation of a new version (v700) of the Level-1 processor with further potential

SMOS instrument performance and calibration after six years in orbit

ESA's Soil Moisture and Ocean Salinity (SMOS) mission, launched 2-Nov-2009, has been in orbit for over 6 years, and its Microwave Imaging Radiometer with Aperture Synthesis (MIRAS) in two dimensions keeps working well. The calibration strategy remains overall as established after the commissioning phase, with a few improvements. The data for this whole period has been reprocessed with a new fully polarimetric version of the Level-1 processor which includes a refined calibration schema for the antenna losses. This reprocessing has allowed the assessment of an improved performance benchmark. An overview of the results and the progress achieved in both calibration and image reconstruction is presented in this contribution.Peer Reviewe

SMOS instrument performance after more than 8 years in orbit and lessons learnt for future L-band missions

Peer ReviewedPostprint (published version