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  • 1
    Publication Date: 2021-03-29
    Description: The Itajaí Basin located in the southern border of the Luís Alves Microplate is considered as a peripheral foreland basin related to the Dom Feliciano Belt. It presents an excellent record of the Ediacaran period, and its upper parts display the best Brazilian example of Precambrian turbiditic deposits. The basal succession of Itajaí Group is represented by sandstones and conglomerates (Baú Formation) deposited in alluvial and deltaic-fan systems. The marine upper sequences correspond to the Ribeirão Carvalho (channelized and non-channelized proximal silty-argillaceous rhythmic turbidites), Ribeirão Neisse (arkosic sandstones and siltites), and Ribeirão do Bode (distal silty turbidites) formations. The Apiúna Formation felsic volcanic rocks crosscut the sedimentary succession. The Cambrian Subida leucosyenogranite represents the last felsic magmatic activity to affect the Itajaí Basin. The Brusque Group and the Florianópolis Batholith are proposed as source areas for the sediments of the upper sequence. For the lower continental units the source areas are the Santa Catarina, São Miguel and Camboriú complexes. The lack of any oceanic crust in the Itajaí Basin suggests that the marine units were deposited in a restricted, internal sea. The sedimentation started around 600 Ma and ended before 560 Ma as indicated by the emplacement of rhyolitic domes. The Itajaí Basin is temporally and tectonically correlated with the Camaquã Basin in Rio Grande do Sul and the Arroyo del Soldado/Piriápolis Basin in Uruguay. It also has several tectono-sedimentary characteristics in common with the African-equivalent Nama Basin.
    Keywords: Dom Feliciano Belt; Ediacaran; Foreland basin; U–Pb SHRIMP ages; Provenance ; 551 ; Earth Sciences; Geophysics/Geodesy; Geology
    Language: English
    Type: article , publishedVersion
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  • 2
    Publication Date: 2022-08-05
    Description: Comparing the reflectivity flux at the top and bottom of the melting layer (ML) reveals the overall effect of the microphysical processes occurring within the ML on the particle population. If melting is the only process taking place and all particles scatter in the Rayleigh regime, the reflectivity flux increases in the ML by a constant factor given by the ratio of the dielectric factors. Deviations from this constant factor can indicate that either growth or shrinking processes (breakup, sublimation, and evaporation) dominate. However, inference of growth or shrinking dominance from the increase in reflectivity flux is only possible if other influences (e.g., vertical wind speed) are negligible or corrected. By analyzing radar Doppler spectra and multi‐frequency observations, we correct the reflectivity fluxes for vertical wind and categorize the height profiles by the riming degree at the ML top. We apply this reflectivity flux ratio (ZFR) approach to a multi‐month mid‐latitude winter data set that contains mostly stratiform clouds. The profiles of radar variables in the ML are found to be surprisingly similar for both unrimed and rimed profiles with slight differences, for example, in the absolute values of the reflectivity flux. Statistical analysis of the ZFR suggests that either microphysical processes other than melting are not important or strongly compensate for each other. The results seem to confirm that at least for moderately precipitating stratiform clouds, the melting‐only assumption applied in several retrievals and microphysical schemes is reasonable.
    Description: Plain Language Summary: To better predict precipitation by numerical models and quantify precipitation by observations, it is important to improve the understanding of processes in the melting layer (ML). The ML is the part of clouds where ice particles melt and become rain. We use an approach that assesses whether a tendency toward either growth or shrinking processes is evident in the ML. We assess the uncertainty of the approach, correct for different factors, and apply it to a large data set to derive robust statistics separately for profiles with different characteristic ice particle shapes above the ML. These statistics are surprisingly similar for the different characteristic ice particle shapes and suggest that either growth and shrinking processes are not important in the ML or strongly compensate for each other.
    Description: Key Points: We investigated the growth or shrinking of snowflakes in the melting layer using statistics of multi‐frequency Doppler radar observations. Reflectivity flux analysis indicates only slight differences for unrimed or rimed particles. Growth or shrinking processes either compensate each other or have, on average, only a small impact on the reflectivity flux.
    Description: German Research Foundation http://dx.doi.org/10.13039/501100001659
    Description: University of Cologne
    Description: https://github.com/markuskarrer/ZFR_riming
    Description: http://cpex-lab.de/cpex-lab/EN/Home/JOYCE-CF/JOYCE-CF_node.html
    Description: https://doi.org/10.5281/zenodo.6341509
    Description: https://doi.org/10.5281/zenodo.5959906
    Keywords: ddc:551.57
    Language: English
    Type: doc-type:article
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  • 3
    Publication Date: 2016-06-07
    Description: In this work an electromagnetic model and subsequent design is presented for a traveling-wave, coplanar waveguide (CPW) based source that will operate in the THz frequency regime. The radio frequency (RF) driving current is a result of photoexcitation of a thin GaAs membrane using two frequency-offset lasers. The GaAs film is grown by molecular-beam-epitaxy (MBE) and displays sub-ps carrier lifetimes which enable the material conductivity to be modulated at a very high rate. The RF current flows between electrodes deposited on the GaAs membrane which are biased with a DC voltage source. The electrodes form a CPW and are terminated with a double slot antenna that couples the power to a quasi-optical system. The membrane is suspended above a metallic reflector to launch all radiation in one direction. The theoretical investigation and consequent design is performed in two steps. The first step consists of a direct evaluation of the magnetic current distribution on an infinitely extended coplanar waveguide excited by an impressed electric current distributed over a finite area. The result of the analysis is the difference between the incident angle of the laser beams and the length of the excited area that maximizes the RF power coupled to the CPW. The optimal values for both parameters are found as functions of the CPW and membrane dimensions as well as the dielectric constants of the layers. In the second step, a design is presented of a double slot antenna that matches the CPW characteristic impedance and gives good overall performance. The design is presently being implemented and measurements will soon be available.
    Keywords: Electronics and Electrical Engineering
    Type: Proceedings of the Twenlfth International Symposium on Space Terahertz Technology; 224-232; JPL-Publ-01-18
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  • 4
    Publication Date: 2018-06-08
    Description: In this study we have measured mixers with a wide range of twin-slot antennas with slot lengths ranging from 26 meu up to 152 meu.
    Keywords: Communications and Radar
    Type: International Symposium of Space Technology; Ann Arbor, MI; United States
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  • 5
    Publication Date: 2018-06-08
    Description: Twin slot antennas coupled to superconducting devices are currently being developed for terahertz mixers and direct detectors for astronomical observations.
    Keywords: Communications and Radar
    Type: International Conference on Applied Electromagnetics and Communications; Dubrovnik; Croatia
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  • 6
    Publication Date: 2018-06-08
    Description: The state of research will be presented along with discussions of requirements for THz LOs and laboratory test sources, and the photomixer approach's unique advantages.
    Keywords: Atomic and Molecular Physics
    Type: FAR-IR, SUB-MM & MM Detector Technology Workshop; Monterey, CA; United States
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  • 7
    Publication Date: 2019-06-28
    Description: Percentages of cloud cover in LANDSAT imagery were used to calculate the cloud cover monthly average statistic for each LANDSAT scene in Brazil, during the period of 1973 to 1981. The average monthly cloud cover and the monthly minimum cloud cover were also calculated for the regions of north, northeast, central west, southeast and south, separately.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: E84-10047 , NASA-CR-174614 , NAS 1.26:174614 , INPE-2882-RPE/443
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  • 8
    Publication Date: 2018-06-08
    Type: 2001 URSI Meeting; Boston, MA; United States
    Format: text
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  • 9
    Publication Date: 2018-06-08
    Keywords: Electronics and Electrical Engineering
    Type: NASA Conference; San Diego, CA; United States
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  • 10
    Publication Date: 2018-06-08
    Keywords: Communications and Radar
    Type: APS 2001/URSI Meeting; Boston, MA; United States
    Format: text
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