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5 results on '"MWR"'

1. An empirical correction for the MWR brightness temperature smear effect.

Author

Farrar, Spencer, Labanda, Martin, Jacob, Maria Marta, Masuelli, Sergio, Biswas, Sayak, Raimondo, Hector, and Jones, Linwood

Abstract

The Microwave Radiometer (MWR), on board of the SAC-D/Aquarius satellite, is a Dicke radiometer, operating at 23.8 and 36.5 GHz that was developed by Argentine Space Agency, CoNAE. Since the first earth surface TB images, there has been an anomalous effect when observing strong contrast radiometric scenes, such as land/water crossings. This effect is present in all push-broom beams and results in a “smearing” of TB observations near high contrast areas. This paper presents the initial findings on this MWR brightness temperature anomaly that is best described as a coupling of sequential MWR feed horn measurements. In the present work, an empirical approach is used to mitigate this anomalous effect. [ABSTRACT FROM PUBLISHER]

Published
2012
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2. Preliminary analysis of the Aquarius/SAC-D Microwave Radiometer (MWR) antenna temperature: Possible antenna pattern issue.

Author

Farrar, Spencer and Jones, W. Linwood

Abstract

The Microwave Radiometer (MWR) flying on the Aquarius/SAC-D satellite is a Dicke radiometer operating at 23.8 and 36.5 GHz that was developed by the Argentine Space Agency CONAE. This instrument complements Aquarius (NASA's L-band radiometer/scatterometer) by providing simultaneous spatially collocated environmental measurements such as oceanic wind speed for roughness correction and rain rate for flagging corrupted salinity retrievals. This paper describes the initial findings on the MWR antenna beam pattern issue. The antenna pattern issue is best described as unwanted earth radiation entering the side-lobes of the directed beam, possibly of unexpected high gain, of certain MWR feedhorns. A first look at the understanding of this problem is presented. [ABSTRACT FROM PUBLISHER]

Published
2012
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3. Land Intercalibration and Drift Monitoring of MWR Radiometer on Board SAC-D/Aquarius

Author

Martin Maas, Cintia A. Bruscantini, Haydee Karszenbaum, and Francisco Grings

Subjects
Atmospheric Science, Radiometer, Meteorology, Oceanografía, Hidrología, Recursos Hídricos, Microwave radiometer, Cross calibration, WINDSAT, Windsat, Ciencias de la Tierra y relacionadas con el Medio Ambiente, purl.org/becyt/ford/1 [https], On board, Ancillary data, purl.org/becyt/ford/1.5 [https], Homogeneous, Brightness temperature, Calibration, Environmental science, MWR, Computers in Earth Sciences, vicarious cold, CIENCIAS NATURALES Y EXACTAS, Remote sensing
Abstract

The microwave radiometer (MWR) on board the SAC-D/Aquarius mission is a Dicke radiometer operating at 23.8 (H-Pol) and 36.5 GHz (H/V-Pol), which can provide ancillary data for the various retrievals to be performed with Aquarius regarding ocean and land applications. In this study, we report calibration results obtained by a land cross-calibration between Windsat and MWR. Moreover, MWR drifts were monitored using vicarious cold methodology. Results were generated for the 2011?2012 period using version V5.0 S of MWR data. MWR and Windsat cross-calibration was carried out over selected homogeneous targets which include tropical and boreal forests, desert, grassland, and the Sahel. As a result, biases were identified and corrections were proposed. Drifts in MWR observations were identified by implementing the vicarious cold method, which is a statistical approach that estimates the coldest value of the brightness temperature (Tb) (over ocean) histogram. Time series of such cold values are closely related to drifts in the instrument. In general, it was observed that MWR drifts tend to stabilize within 1 K after June 2012, when the software of the on-board computer was updated. Fil: Bruscantini, Cintia Alicia. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina Fil: Maas, Martín Daniel. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina Fil: Grings, Francisco Matias. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina Fil: Karszenbaum, Haydee. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina

Published
2015
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4. Development of a Ground Based Remote Sensing Approach for Direct Evaluation of Aerosol-Cloud Interaction

Author

Barry Gross, B. L. Madhavan, Yonghua Wu, Samir Ahmed, Fred Moshary, and Yuzhe He

Subjects
Atmospheric Science, Meteorology, Multispectral image, Environmental Science (miscellaneous), lcsh:QC851-999, Cod, Goes, Microwave Radiometry, Aircraft Observations, Raman Lidar, Marine Stratocumulus, Mfrsr, Mwr, Physics::Atmospheric and Oceanic Physics, Remote sensing, Radiative-Transfer, Effective radius, Radiometer, Part I, Retrieval, Reff, Microphysical Properties, Microwave radiometer, R-Eff, Satellite Data, Albedo, Optical Depth, Aerosol, Lidar, Aerosol-Cloud Interaction, Environmental science, lcsh:Meteorology. Climatology, Moderate-resolution imaging spectroradiometer, Liquid Water Path, Modis
Abstract

The possible interaction and modification of cloud properties due to aerosols is one of the most poorly understood mechanisms within climate studies, resulting in the most significant uncertainty as regards radiation budgeting. In this study, we explore direct ground based remote sensing methods to assess the Aerosol-Cloud Indirect Effect directly, as space-borne retrievals are not directly suitable for simultaneous aerosol/cloud retrievals. To illustrate some of these difficulties, a statistical assessment of existing multispectral imagers on geostationary (e.g., GOES)/Moderate Resolution Imaging Spectroradiometer (MODIS) satellite retrievals of the Cloud Droplet Effective Radius (R-eff) showed significant biases especially at larger solar zenith angles, further motivating the use of ground based remote sensing approaches. In particular, we discuss the potential of using a combined Microwave Radiometer (MWR)-Multi-Filter Rotating Shadowband Radiometer (MFRSR) system for real-time monitoring of Cloud Optical Depth (COD) and Cloud Droplet Effective Radius (R-eff), which are combined with aerosol vertical properties from an aerosol lidar. An iterative approach combining the simultaneous observations from MFRSR and MWR are used to retrieve the COD and R-eff for thick cloud cases and are extensively validated using the DoE Southern Great Plains (SGP) retrievals as well as regression based parameterized model retrievals. In addition, we account for uncertainties in background aerosol, surface albedo and the combined measurement uncertainties from the MWR and MFRSR in order to provide realistic uncertainty estimates, which is found to be similar to 10% for the parameter range of interest in Aerosol-Cloud Interactions. Finally, we analyze a particular case of possible aerosol-cloud interaction described in the literature at the SGP site and demonstrate that aerosol properties obtained at the surface can lead to inconclusive results in comparison to lidar-derived aerosol properties near the cloud base.

Published
2012

5. Brightness Temperature Calibration Of Sac-d/aquarius Microwave Radiometer (mwr)

Author

Biswas, Sayak Krishna

Subjects
Calibration, microwave, radiometer, sac d, mwr, brightness temperature, Electrical and Computer Engineering, Electrical and Electronics, Engineering, Dissertations, Academic -- Engineering and Computer Science, Engineering and Computer Science -- Dissertations, Academic
Abstract

The Aquarius/SAC-D joint international science mission, between the National Aeronautics and Space Administration (NASA) of United States and the Argentine Space Agency (Comision Nacional de Actividades Espaciales, CONAE), was launched on a polarorbiting satellite on June 10, 2011. This mission of discovery will provide measurements of the global sea surface salinity, which contributes to understanding climatic changes in the global water cycle and how these variations influence the general ocean circulation. The Microwave Radiometer (MWR), a three channel Dicke radiometer operating at 23.8 GHz H-Pol and 36.5 GHz V-& H-Pol provided by CONAE, will complement Aquarius (NASA’s L-band radiometer/scatterometer) by providing simultaneous spatially collocated environmental measurements such as water vapor, cloud liquid water, surface wind speed, rain rate and sea ice concentration. This dissertation focuses on the overall radiometric calibration of MWR instrument. Which means establishing a transfer function that relates the instrument output to the antenna brightness temperature (Tb). To achieve this goal, the dissertation describes a microwave radiative transfer model of the instrument and validates it using the laboratory and thermal-vacuum test data. This involves estimation of the losses and physical temperature profile in the path from the receiver to each antenna feed-horn for all the receivers. As the pre-launch laboratory tests can only provide a simulated environment which is very different from the operational environment in space, an on-orbit calibration of the instrument is very important. Inter-satellite radiometric cross-calibration of MWR using the Naval Research iii Laboratory’s multi-frequency polarimetric microwave radiometer, WindSat, on board the Coriolis satellite is also an important part of this dissertation. Cross-calibration between two different satellite instruments require normalization of Tb’s to account for the frequency and incidence angle difference between the instruments. Also inter-satellite calibration helps to determine accurate antenna pattern correction coefficients and other small instrument biases.

Published
2012

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