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by Alia Amira
2011, IEEE Transactions on Geoscience and Remote Sensing
This paper describes the analysis of L-band radiometric measurement data gathered with the synthetic aperture radiometer HUT-2D during several ground-based and airborne measurement campaigns. The radiometric data are analyzed from the instrument's performance point of view, aiming to verify the theoretical performance of an instrument of this kind and to assess the performance of the HUT-2D radiometer system in particular. The data sets considered for the study consist of measurements of well-known natural targets, such as cosmic background radiation, and measurements of pure water scenes, the brightness temperature of which is possible to model based on in situ measurements. We define four figures of merit, which are applicable for synthetic aperture radiometers. These are radiometric resolution, image bias, pixel-to-pixel random error, and temporal stability. Then, we use the selected data sets to assess these in the case of HUT-2D. The experimental results are discussed and compared to the theoretical values, where applicable. Also, we discuss possibilities to improve the presented performance. The main results of this paper are the consolidated performance parameters of the HUT-2D instrument. We study and discuss the properties of the error components related to the technology in a general level, and study the scalability of the errors as a function of the measured targets. In particular, the stability of the direction-dependent error component is pointed out, and a mitigation guideline is proposed.
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2012, Remote Sensing
2008, Radio Science
2005, Radio Science
2010, International Geoscience and Remote Sensing Symposium (IGARSS)
2000, IEEE Transactions on Geoscience and Remote Sensing
2000, IEEE Transactions on Geoscience and Remote Sensing
2000, Proceedings of the IEEE
2004, IEEE Transactions on Geoscience and Remote Sensing
2004, IEEE International IEEE International IEEE International Geoscience and Remote Sensing Symposium, 2004. IGARSS '04. Proceedings. 2004
2000, IEEE Transactions on Geoscience and Remote Sensing
2003, Radio Science
2009, IEEE Transactions on Geoscience and Remote Sensing
2011, Ieee Transactions on Geoscience and Remote Sensing
ABSTRACT After the successful launching of the Soil Moisture and Ocean Salinity satellite in November 2009, continuous streams of data started to be regularly downloaded and made available to be processed. The first six months of operation were fully dedicated to the In-Orbit Commissioning Phase, with an intense activity aimed at bringing the satellite and instrument into a fully operational condition. Concerning the payload Microwave Imaging Radiometer with Aperture Synthesis, it was fully characterized using specific orbits dedicated to check all instrument modes. The procedures, already defined during the on-ground characterization, were repeated so as to obtain realistic temperature characterization and updated internal calibration parameters. External calibration maneuvers were tested for the first time and provided absolute instrument calibration, as well as corrections to internal calibration data. Overall, performance parameters, such as stability, radiometric sensitivity and radiometric accuracy were evaluated. The main results of this activity are presented in this paper, showing that the instrument delivers stable and well-calibrated data thanks to the combination of external and internal calibration and to an accurate thermal characterization. Finally, the quality of the visibility calibration is demonstrated by producing brightness temperature images in the alias-free field of view using standard inversion techniques. Images of ocean, ice, and land are given as examples.
2000, IEEE Transactions on Geoscience and Remote Sensing
2013, IEEE Transactions on Geoscience and Remote Sensing
The European Space Agency's Soil Moisture and Ocean Salinity (SMOS) satellite was launched in November 2009 and delivers now brightness temperature and soil moisture products over terrestrial areas on a regular three-day basis. In 2010, several airborne campaigns were conducted to validate the SMOS products with microwave emission radiometers at L-band (1.4 GHz). In this paper, we present results from measurements performed in the Rur and Erft catchments in May and June 2010. The measurement sites were situated in the very west of Germany close to the borders to Belgium and The Netherlands. We developed an approach to validate spatial and temporal SMOS brightness temperature products. An area-wide brightness temperature reference was generated by using an area-wide modeling of top soil moisture and soil temperature with the WaSiM-ETH model and radiative transfer calculation based on the L-band Microwave Emission of the Biosphere model. Measurements of the airborne L-band sensors EMIRAD and HUT-2D on-board a Skyvan aircraft as well as ground-based mobile measurements performed with the truck mounted JÜLBARA L-band radiometer were analyzed for calibration of the simulated brightness temperature reference. Radiative transfer parameters were estimated by a data assimilation approach. By this versatile reference data set, it is possible to validate the spaceborne brightness temperature and soil moisture data obtained from SMOS. However, comparisons with SMOS observations for the campaign period indicate severe differences between simulated and observed SMOS data.
2000, IEEE Transactions on Geoscience and Remote Sensing
2000, IEEE Transactions on Geoscience and Remote Sensing
2000, Proceedings of the IEEE
2014, Remote Sensing of Environment
2003, Radio Science
The Soil Moisture and Ocean Salinity (SMOS) mission is aimed at monitoring, globally, surface soil moisture and sea surface salinity from radiometric L-band observations. The SMOS radiometer relies upon a two-dimensional (2-D) synthetic aperture concept in order to achieve satisfactory spatial resolution performances for a minimal cost in terms of payload mass and volume. Counterparts of this advantage are reduced
2014
2000, IEEE Transactions on Geoscience and Remote Sensing
1998, IEEE Transactions on Geoscience and Remote Sensing
2006, 2006 IEEE MicroRad Proceedings - 9th Specialist Meeting on Microwave Radiometry and Remote Sensing Applications, MicroRad'06
2000, IEEE Transactions on Geoscience and Remote Sensing
2001, IEEE Transactions on Geoscience and Remote Sensing
2007, IEEE Transactions on Geoscience and Remote Sensing
Since the sun is an extremely strong radiation source at L-band, accounting for sun glint over the ocean, i.e., solar radiation reflected by the sea surface toward downward-looking radiometers, raises a significant challenge for the remote sensing of sea surface salinity. This paper describes a dedicated physical model for sun glint at L-band frequencies and provides quantitative and qualitative estimates
2000, IEEE Transactions on Geoscience and Remote Sensing
1998, Journal of Electromagnetic Waves and Applications
2000, IEEE Transactions on Geoscience and Remote Sensing
2010, Geoscience and Remote Sensing IEEE International Symposium
This paper describes a first attempt of comparing data of the two airborne L-band radiometers EMIRAD and HUT-2D over land surface. While HUT-2D is an imaging system with a high spatial resolution, EMIRAD delivers data averaged over a relatively large footprint but can be considered to be more stable. The Upper Danube catchment, located mostly in Southern Germany, is one
2005, International Geoscience and Remote Sensing Symposium (IGARSS)
2011, Sensors
1998, Progress in Electromagnetics Research-pier
Sensors
1997, IEEE Transactions on Geoscience and Remote Sensing
2000, IEEE Transactions on Geoscience and Remote Sensing
2012, Journal of Geophysical Research
2007, 2007 IEEE International Geoscience and Remote Sensing Symposium
2010
2000, IEEE Transactions on Geoscience and Remote Sensing
2000, IEEE Transactions on Geoscience and Remote Sensing
2012, Scientia Marina
Capability for sea surface salinity observation was an important gap in ocean remote sensing in the last few decades of the 20th century. New technological developments during the 1990s at the European Space Agency led to the proposal of SMOS (Soil Moisture and Ocean Salinity), an Earth explorer opportunity mission based on the use of a microwave interferometric radiometer, MIRAS (Microwave Imaging Radiometer with Aperture Synthesis). SMOS, the first satellite ever addressing the observation of ocean salinity from space, was successfully launched in November 2009. The determination of salinity from the MIRAS radiometric measurements at 1.4 GHz is a complex procedure that requires high performance from the instrument and accurate modelling of several physical processes that impact on the microwave emission of the ocean’s surface. This paper introduces SMOS in the ocean remote sensing context, and summarizes the MIRAS principles of operation and the SMOS salinity retrieval approach. It describes the Spanish SMOS high-level data processing centre (CP34) and the SMOS Barcelona Expert Centre on Radiometric Calibration and Ocean Salinity (SMOS-BEC), and presents a preliminary validation of global sea surface salinity maps operationally produced by CP34
2002, IEEE Transactions on Geoscience and Remote Sensing
2000, Remote Sensing of Environment
This paper discusses the potential of an L-band 2-D microwave interferometric radiometer for monitoring surface variables over land surfaces. The instrument is the payload of the Soil Moisture and Ocean Salinity (SMOS) Mission recently selected for phase A studies by the European Space Agency (ESA) as the second Earth Explorer Opportunity Mission. The L-band radiometer is based on an innovative