SMOS calibration and validation activities with airborne interferometric radiometer HUT-2D during spring 2010

In this paper we present calibration and validation activities of European Space Agency’s SMOS mission, which utilize airborne interferomentric L-band radiometer system HUT-2D of the Aalto University. During spring 2010 the instrument was used to measure three SMOS validation target areas, one in Denmark and two in Germany. We present these areas shortly, and describe the airborne activities. We show some exemplary measurements of the radiometer system and demonstrate the studies using the data

Review of the CALIMAS Team Contributions to European Space Agency's Soil Moisture and Ocean Salinity Mission Calibration and Validation

Camps, Adriano ... et al.-- 38 pages, 22 figuresThis work summarizes the activities carried out by the SMOS (Soil Moisture and Ocean Salinity) Barcelona Expert Center (SMOS-BEC) team in conjunction with the CIALE/Universidad de Salamanca team, within the framework of the European Space Agency (ESA) CALIMAS project in preparation for the SMOS mission and during its first year of operation. Under these activities several studies were performed, ranging from Level 1 (calibration and image reconstruction) to Level 4 (land pixel disaggregation techniques, by means of data fusion with higher resolution data from optical/infrared sensors). Validation of SMOS salinity products by means of surface drifters developed ad-hoc, and soil moisture products over the REMEDHUS site (Zamora, Spain) are also presented. Results of other preparatory activities carried out to improve the performance of eventual SMOS follow-on missions are presented, including GNSS-R to infer the sea state correction needed for improved ocean salinity retrievals and land surface parameters. Results from CALIMAS show a satisfactory performance of the MIRAS instrument, the accuracy and efficiency of the algorithms implemented in the ground data processors, and explore the limits of spatial resolution of soil moisture products using data fusion, as well as the feasibility of GNSS-R techniques for sea state determination and soil moisture monitoringThis work has been performed under research grants TEC2005-06863-C02-01/TCM, ESP2005-06823-C05, ESP2007-65667-C04, AYA2008-05906-C02-01/ESP and AYA2010-22062-C05 from the Spanish Ministry of Science and Innovation, and a EURYI 2004 award from the European Science FoundationPeer Reviewe

Improved Characterization of Forest Transmissivity Within the L-MEB Model Using Multisensor SAR Data

This letter proposes a novel way to assimilate synthetic aperture radar (SAR) data to L-band Microwave Emission of the Biosphere (L-MEB) model to enhance model performance over forested areas. L-and C-band satellite SAR data are used in order to characterize the forest transmissivity within the emission model, instead of the optical satellite imagery-based leaf area index (LAI) parameter. Examination of several combinations of satellite SAR data as a substitute for LAI within the L-MEB model showed that when ALOS PALSAR (L-band) and multitemporal composite Sentinel-1 (C-band) data are applied, an improved agreement was achieved between the measured and simulated brightness temperatures (TBs) over forests. The root mean squared difference between modeled and measured TBs was reduced from 6.1 to 4.7 K with single PALSAR scene-based transmissivity correction and down to 4.1 K with multitemporal Sentinel-1 composite-based transmissivity correction. Suitability of single Sentinel-1 scenes varied based on seasonal and weather conditions. Overall, this indicates the potential of an SAR-based estimation of forest volume transmissivity and opens a possible way of fruitful active-passive microwave satellite data integration.Peer reviewe

L-alueen taajuuspyyhkäisevän radiometrin suunnittelu ja toteutus

L-band (1-2 GHz) radiometry has been an ongoing research topic in the Department of Radio Science and Engineering for a number of years. In addition to remote sensing and radioastronomy applications, a radiometer can be used for detecting unwanted radio emissions in a protected frequency band. A frequency scanning radiometer (FIRaL) for detecting radio interference at the frequency interval of 1920 – 1980 MHz is designed and realised in this Licentiate thesis work. The aforementioned frequency band is reserved for mobile communication applications. The theory of radiometry is presented to the necessary extent in order to facilitate the FIRaL radiometer design. The design of the receiver and local oscillator electronics and pyramidal horn antenna is presented. Radiometer performance is studied by measuring the relevant device parameters in laboratory conditions. The feasibility of the radiometer to perform real-world interference surveys is tested by on-site measurements. The realised radiometer receiver input noise temperature is 661 ± 58 K or better. The radiometer is deemed suitable for interference measurements. The preliminary on-site measurements suggests that further measurements are feasible in order to study the extent of radio emissions in the 1920 – 1980 MHz mobile communications band.Radiotieteen ja –tekniikan laitoksella on jo useita vuosia tutkittu L-alueen (1-2 GHz) radiometriasovelluksia. Kaukokartoituksen ja radioastronomian ohella radiometreillä voidaan tutkia radiotaajuisia häiriöitä suojatuilla taajuusalueilla. Tässä työssä on suunniteltu ja toteutettu L-alueen taajuuspyyhkäisevä radiometri (FIRaL) 1920-1980 MHz:in taajuusalueelta mahdollisesti löytyvien radiotaajuisten häiriöiden tutkimiseen. Edellä mainittu taajuuskaista on varattu matkaviestintäsovellusten käyttöön. Radiometria esitellään FIRaL radiometrin suunnittelun taustatiedoksi tarvittavalla laajuudella. Vastaanottimen ja paikallisoskillaattorin elektroniikan ja pyramiditorviantennin suunnittelu esitellään. Radiometrin suorituskykyä tutkitaan mittaamalla kyseisen laitteen parametrit laboratorio-olosuhteissa. Radiometrin soveltuvuus käytännön häiriömittauksiin testataan tekemällä mittauksia tyypillisessä matkaviestintätukiaseman sijaintipaikassa. Rakennetun radiometrin kohinalämpötila on maksimissaan 661 ± 58 K. Radiometri todetaan käyttökelpoiseksi häiriömittauksiin. Alustavista mittauksista löytyi todennäköisiä häiriölähteitä 1920 – 1980 MHz matkaviestintäkaistalta ja lisätutkimukset häiriöiden laajempaan kartoitukseen ovat perusteltuja

2000 days of SMOS at the Barcelona Expert Centre: a tribute to the work of Jordi Font

Soil Moisture and Ocean Salinity (SMOS) is the first satellite mission capable of measuring sea surface salinity and soil moisture from space. Its novel instrument (the L-band radiometer MIRAS) has required the development of new algorithms to process SMOS data, a challenging task due to many processing issues and the difficulties inherent in a new technology. In the wake of SMOS, a new community of users has grown, requesting new products and applications, and extending the interest in this novel brand of satellite services. This paper reviews the role played by the Barcelona Expert Centre under the direction of Jordi Font, SMOS co-principal investigator. The main scientific activities and achievements and the future directions are discussed, highlighting the importance of the oceanographic applications of the mission.Peer ReviewedPostprint (published version