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Sample records for 2x2 km radar

  1. Coherent scatter radar observations of 150-km echoes and vertical plasma drifts in the Brazilian sector

    NASA Astrophysics Data System (ADS)

    Rodrigues, F. S.; de Paula, E. R.; Hysell, D. L.; Chau, J. L.

    2008-12-01

    Coherent scatter echoes coming from the valley region (~150 km altitude) in the equatorial ionosphere during daytime have been detected by the Jicamarca radar in Peru for several decades (Basley, 1945). More recently, it was found that the vertical Doppler shift of these echoes corresponds to the vertical velocity of the F-region background plasma (Kudeki and Fawcett, 1993; Woodman and Villanueva,1995, Chau and Woodman, 2004). Jicamarca now uses observations of 150-km echoes to provide estimates of the diurnal variation of the equatorial vertical plasma drifts in addition to traditional incoherent scatter radar drift measurements. These 150-km echoes have also been observed in other longitude sectors (e.g. Tsunoda and Ecklund,2004; Patra et al., 2008). Additionally, these echoes have also been detected in a semi-routine basis with a small, low-power radar in Sao Luis, Brazil. Initial results of our analysis suggest that vertical plasma drifts can be estimated from these observations. These measurements combined with simultaneous measurements made by the Jicamarca radar and the C/NOFS satellite can help us better understand the day-to-day variability and longitudinal variation of equatorial electric fields. In this talk we will present examples of 150-km echoes observations made with the Sao Luis radar. We will describe how vertical drifts can be estimated from the observations and how the vertical drifts over Sao Luis compare with the drifts measured simultaneously at Jicamarca. These new measurements can provide important new information about the low-latitude electrodynamics, and consequently to the C/NOFS mission.

  2. On the nature of radar echoes below 95 km during counter streaming in the equatorial electrojet

    NASA Astrophysics Data System (ADS)

    Tsunoda, Roland T.; Ecklund, Warner L.

    Using data obtained with a 49.92-MHz radar on the island of Pohnpei (Federated States of Micronesia), we show that a weak, westward current exists at the base of the normal eastward electrojet. We suggest that this counter stream is driven by a downward-directed electric field associated with positive-charge accumulation near the base of the eastward electrojet. To explain the existence of radar echoes from this counter-streaming region, where conditions are not conducive to irregularity generation by the gradient-drift instability (GDI), we suggest that “seed” plasma structure may be produced by neutral turbulence. If so, the GDI could act on appropriately directed gradients in plasma density that are associated with the seed structure to generate the secondary type-2 irregularities responsible for the radar echoes.

  3. Snowfall Rates Obtained from Radar Reflectivity within a 50 km Range.

    DTIC Science & Technology

    1981-09-15

    measurements yielded a correlation coefficient of 0.88. However, in correlating the total storm snowfall, the amount of radar-measured snowfall above a...reference snowfall measurement site was made equal to the snowfall actually measured at this location. This calibration technique improved the storm snowfall correlation coefficient to 0.96. (author)

  4. On a summer maximum in the occurrence frequency of 150 km (F1) radar echoes over Pohnpei

    NASA Astrophysics Data System (ADS)

    Tsunoda, Roland T.; Ecklund, Warner L.

    2004-03-01

    Using three and a half years of 50 MHz radar data collected from Pohnpei, Federated States of Micronesia (6.96°N, 158.19°E geographic, 0.3° magnetic dip latitude), we show for the first time that the occurrence frequency of 150 km (or F1) echoes has a broad but conspicuous maximum during northern summer in this longitude sector with minimal activity in other months. Given a seasonal similarity to sporadic E (Es), we suggest that an Es-layer instability [Cosgrove and Tsunoda, 2002] generates a polarization electric field ($\\vec E$), which maps along geomagnetic field lines to the F1 region. There, $\\vec E$ forms thin plasma sheets that provide gradients to excite 3-m-scale plasma waves via an interchange process.

  5. Credit WCT. Original 2'" x 2'" color negative is housed ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Credit WCT. Original 2-'" x 2-'" color negative is housed in the JPL Photography Laboratory, Pasadena, California. View shows small autoclave demonstrated by JPL staff member Milton Clay (JPL negative no. JPL-10286AC, 27 January 1989). - Jet Propulsion Laboratory Edwards Facility, Liner Laboratory, Edwards Air Force Base, Boron, Kern County, CA

  6. Credit WCT. Original 2'" x 2%" color negative is housed ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Credit WCT. Original 2-'" x 2-%" color negative is housed in the JPL Photography Laboratory, Pasadena, California. This view shows the propellant cutter as it was originally installed (JPL negative no. 381-2274A, 29 June 1962) - Jet Propulsion Laboratory Edwards Facility, Preparation Building, Edwards Air Force Base, Boron, Kern County, CA

  7. Ising models on the 2 x 2 x {infinity} lattices

    SciTech Connect

    Yurishchev, M. A.

    2007-03-15

    Exact analytic solutions are presented for two 2 x 2 x {infinity} Ising etageres. The first model has a simple cubic lattice with fully anisotropic interactions. The second model consists of two different types of linear chains and includes noncrossing diagonal bonds on the side faces of the 2 x 2 x {infinity} parallelepiped. In both cases, the solutions are expressed through square radicals and obtained by using the obvious symmetry of the Hamiltonians, Z{sub 2} x C{sub 2v}, and the hidden algebraic {lambda}{lambda} symmetry of the transfer matrix secular equations. The solution found for the second model is used to analyze the behavior of specific heat in a frustrated many-chain system.

  8. Snow accumulation variability derived from radar and firn core data along a 600 km transect in Adelie Land, East Antarctic plateau

    NASA Astrophysics Data System (ADS)

    Verfaillie, D.; Fily, M.; Le Meur, E.; Magand, O.; Jourdain, B.; Arnaud, L.; Favier, V.

    2012-11-01

    The mass balance of ice sheets is an intensively studied topic in the context of global change and sea-level rise. However - particularly in Antarctica - obtaining mass balance estimates remains difficult due to various logistical problems. In the framework of the TASTE-IDEA (Trans-Antarctic Scientific Traverses Expeditions - Ice Divide of East Antarctica) program, an International Polar Year project, continuous ground penetrating radar (GPR) measurements were carried out during a traverse in Adelie Land (East Antarctica) during the 2008-2009 austral summer between the Italian-French Dome C (DC) polar plateau site and French Dumont D'Urville (DdU) coastal station. The aim of this study was to process and interpret GPR data in terms of snow accumulation, to analyse its spatial and temporal variability and compare it with historical data and modelling. The focus was on the last 300 yr, from the pre-industrial period to recent times. Beta-radioactivity counting and gamma spectrometry were applied to cores at the LGGE laboratory, providing a depth-age calibration for radar measurements. Over the 600 km of usable GPR data, depth and snow accumulation were determined with the help of three distinct layers visible on the radargrams (≈ 1730, 1799 and 1941 AD). Preliminary results reveal a gradual increase in accumulation towards the coast (from ≈ 3 cm w.e. a-1 at Dome C to ≈ 17 cm w.e. a-1 at the end of the transect) and previously undocumented undulating structures between 300 and 600 km from DC. Results agree fairly well with data from previous studies and modelling. Drawing final conclusions on temporal variations is difficult because of the margin of error introduced by density estimation. This study should have various applications, including model validation.

  9. Snow accumulation variability in Adelie Land (East Antarctica) derived from radar and firn core data. A 600 km transect from Dome C

    NASA Astrophysics Data System (ADS)

    Verfaillie, D.; Fily, M.; Le Meur, E.; Magand, O.; Jourdain, B.; Arnaud, L.; Favier, V.

    2012-07-01

    Polar ice sheets mass balance is a timely topic intensively studied in the context of global change and sea-level rise. However, obtaining mass balance estimates in Antarctica in particular, remains difficult due to various logistical problems. In the framework of the TASTE-IDEA program, labeled as an International Polar Year project, continuous Ground Penetrating Radar (GPR) measurements were carried out during a traverse realised in Adelie Land (East Antarctica) during the 2008-2009 austral summer between the Italo-French Dome C (DC) polar plateau site and French Dumont D'Urville (DdU) coastal station. The aim of this study was to process and interpret GPR data in terms of snow accumulation, to analyse its spatial and temporal variability along the DC-DdU traverse and compare it with historical data and modeling. The emphasis has been put on the last 300 yr, from the pre-industrial to recent time period. Beta-radioactivity counting and gamma spectrometry were studied in cores at LGGE laboratory, providing a depth-age calibration for radar measurements. Over the 600 km of usable GPR data, depth and snow accumulation were determined with the help of three distinct layers visible on the radargrams (≈1730, 1799 and 1941 AD). Preliminary results reveal a gradual accumulation increase towards the coast and the occurrence of previously undocumented undulating structures between 300 and 600 km from DC. Results agree fairly well with data from previous studies and modeling. Concluding on temporal variations is difficult because of the margin of error introduced by density estimation. This study should have various applications such as for model validation.

  10. Molecular and functional characterization of human P2X(2) receptors.

    PubMed

    Lynch, K J; Touma, E; Niforatos, W; Kage, K L; Burgard, E C; van Biesen, T; Kowaluk, E A; Jarvis, M F

    1999-12-01

    P2X receptors are a family of ATP-gated ion channels. Four cDNAs with a high degree of homology to the rat P2X(2) receptor were isolated from human pituitary and pancreas RNA. Genomic sequence indicated that these cDNAs represent alternatively spliced messages. Northern analysis revealed high levels of human P2X(2) (hP2X(2)) message in the pancreas, and splice variants could be detected in a variety of tissues. Two cDNAs encoded functional ion channels when expressed in Xenopus oocytes, a receptor structurally homologous to the prototype rat P2X(2) receptor (called hP2X(2a)) and a variant containing a deletion within its cytoplasmic C terminus (called hP2X(2b)). Pharmacologically, these functional human P2X(2) receptors were virtually indistinguishable, with the P2X receptor agonists ATP, 2-methylthio-ATP, 2' and 3'-O-(4-benzoylbenzoyl)-ATP, and ATP5'-O-(3-thiotriphosphate) being approximately equipotent (EC(50) = 1 microM) in eliciting extracellular Ca(2+) influx. The P2 receptor agonists alpha,beta-methylene ATP, adenosine, adenosine 5'-O-(2-thiodiphosphate), and UTP were inactive at concentrations up to 100 microM. Both hP2X(2a) and hP2X(2b) receptors were sensitive to the P2 receptor antagonist pyridoxal-5-phosphate-6-azophenyl-2', 4'-disulfonic acid (IC(50) = 3 microM). In contrast to the analogous rat P2X(2) and P2X(2b) receptors, the desensitization rates of the hP2X(2a) and hP2X(2b) receptors were equivalent. Both functional forms of the human P2X(2) receptors formed heteromeric channels with the human P2X(3) receptor. These data demonstrate that the gene structure and mRNA heterogeneity of the P2X(2) receptor subtype are evolutionarily conserved between rat and human, but also suggest that alternative splicing serves a function other than regulating the desensitization rate of the human receptor.

  11. Comparative anatomy of the day- and night-time radar echoes from the 130-170 km region of the low latitude ionosphere

    NASA Astrophysics Data System (ADS)

    Patra, A. K.; Pavan Chaitanya, P.

    2014-08-01

    Recent observations of daytime 150 km echoes made from Gadanki have revealed ‘descending layer type’ echoing pattern, which are remarkably different from their well known ‘necklace’ pattern. These descending layer type echoing pattern have close resemblance to those of the nighttime valley region echoes that are presumably linked with the intermediate layer formed by the meridional wind shear associated with the semidiurnal/terdiurnal tidal winds. The observed close resemblance between the two echoing patterns reminds the plausible role of the semidiurnal/terdiurnal tidal wind and metallic ions in the governing physical processes. We present a comparative anatomy of these two echoing phenomena by making a close examination of the radar observations from Gadanki. Importantly, we bring out the similarities and dissimilarities in their characteristics and discuss the results in the light of currently available theoretical frameworks in an effort to further our understanding on the origin of these echoing phenomena, which have been addressed so far in isolation.

  12. Flexible subunit stoichiometry of functional human P2X2/3 heteromeric receptors.

    PubMed

    Kowalski, Maria; Hausmann, Ralf; Schmid, Julia; Dopychai, Anke; Stephan, Gabriele; Tang, Yong; Schmalzing, Günther; Illes, Peter; Rubini, Patrizia

    2015-12-01

    The aim of the present work was to clarify whether heterotrimeric P2X2/3 receptors have a fixed subunit stoichiometry consisting of one P2X2 and two P2X3 subunits as previously suggested, or a flexible stoichiometry containing also the inverse subunit composition. For this purpose we transfected HEK293 cells with P2X2 and P2X3 encoding cDNA at the ratios of 1:2 and 4:1, and analysed the biophysical and pharmacological properties of the generated receptors by means of the whole-cell patch-clamp technique. The concentration-response curves for the selective agonist α,β-meATP did not differ from each other under the two transfection ratios. However, co-expression of an inactive P2X2 mutant and the wild type P2X3 subunit and vice versa resulted in characteristic distortions of the α,β-meATP concentration-response relationships, depending on which subunit was expressed in excess, suggesting that HEK293 cells express mixtures of (P2X2)1/(P2X3)2 and (P2X2)2/(P2X3)1 receptors. Whereas the allosteric modulators H+ and Zn2+ failed to discriminate between the two possible heterotrimeric receptor variants, the α,β-meATP-induced responses were blocked more potently by the competitive antagonist A317491, when the P2X2 subunit was expressed in deficit of the P2X3 subunit. Furthermore, blue-native PAGE analysis of P2X2 and P2X3 subunits co-expressed in Xenopus laevis oocytes and HEK293 cells revealed that plasma membrane-bound P2X2/3 receptors appeared in two clearly distinct heterotrimeric complexes: a (P2X2-GFP)2/(P2X3)1 complex and a (P2X2-GFP)1/(P2X3)2 complex. These data strongly indicate that the stoichiometry of the heteromeric P2X2/3 receptor is not fixed, but determined in a permutational manner by the relative availability of P2X2 and P2X3 subunits.

  13. Potent and long-lasting inhibition of human P2X2 receptors by copper

    PubMed Central

    Punthambaker, Sukanya; Hume, Richard I.

    2013-01-01

    P2X receptors are ion channels gated by ATP. In rodents these channels are modulated by zinc and copper. Zinc is co-released with neurotransmitter at some synapses and can modulate neuronal activity, but the role of copper in the brain is unclear. Rat P2X2 receptors show potentiation by 2–100 µM zinc or copper in the presence of a submaximal concentration of ATP but are inhibited by zinc or copper at concentrations above 100 µM. In contrast, human P2X2 (hP2X2) receptors show no potentiation and are strongly inhibited by zinc over the range of 2–100 µM. The effect of copper on hP2X2 is of interest because there are human brain disorders in which copper concentration is altered. We found that hP2X2 receptors are potently inhibited by copper (IC50 = 40 nM). ATP responsiveness recovered extremely slowly after copper washout, with full recovery requiring over 1 h. ATP binding facilitated copper binding but not unbinding from this inhibitory site. A mutant receptor in which the first six extracellular cysteines were deleted, C(1–6)S, showed normal copper inhibition, however reducing agents dramatically accelerated recovery from copper inhibition in wild type hP2X2 and the C(1–6)S mutant, indicating that the final two disulfide bonds are required to maintain the high affinity copper binding site. Three histidine residues required for normal zinc inhibition were also required for normal copper inhibition. Humans with untreated Wilson’s disease have excess amounts of copper in the brain. The high copper sensitivity of hP2X2 receptors suggests that they are non-functional in these patients. PMID:24067922

  14. 60-GHz optical/wireless MIMO system integrated with optical subcarrier multiplexing and 2x2 wireless communication.

    PubMed

    Lin, Chi-Hsiang; Lin, Chun-Ting; Huang, Hou-Tzu; Zeng, Wei-Siang; Chiang, Shou-Chih; Chang, Hsi-Yu

    2015-05-04

    This paper proposes a 2x2 MIMO OFDM Radio-over-Fiber scheme based on optical subcarrier multiplexing and 60-GHz MIMO wireless transmission. We also schematically investigated the principle of optical subcarrier multiplexing, which is based on a dual-parallel Mach-Zehnder modulator (DP-MZM). In our simulation result, combining two MIMO OFDM signals to drive DP-MZM gives rise to the PAPR augmentation of less than 0.4 dB, which mitigates nonlinear distortion. Moreover, we applied a Levin-Campello bit-loading algorithm to compensate for the uneven frequency responses in the V-band. The resulting system achieves OFDM signal rates of 61.5-Gbits/s with BER of 10(-3) over 25-km SMF transmission followed by 3-m wireless transmission.

  15. Bayesian Procedures for Prediction Analysis of Implication Hypotheses in 2 X 2 Contingency Tables.

    ERIC Educational Resources Information Center

    Lecoutre, Bruno; Charron, Camilo

    2000-01-01

    Illustrates procedures for prediction analysis in 2 X 2 contingency tables through the analyses of solutions of six types of problems associated with the acquisition of fractions. Reviews and extends confidence interval procedures previously proposed for an index of predictive efficiency of implication hypotheses. Compares frequentist coverage…

  16. Cohen's Linearly Weighted Kappa Is a Weighted Average of 2 x 2 Kappas

    ERIC Educational Resources Information Center

    Warrens, Matthijs J.

    2011-01-01

    An agreement table with [n as an element of N is greater than or equal to] 3 ordered categories can be collapsed into n - 1 distinct 2 x 2 tables by combining adjacent categories. Vanbelle and Albert ("Stat. Methodol." 6:157-163, 2009c) showed that the components of Cohen's weighted kappa with linear weights can be obtained from these n - 1…

  17. Gender Differences in the Factor Structure of the 2x2 Achievement Goal Framework

    ERIC Educational Resources Information Center

    Alkharusi, Hussain; Aldhafri, Said

    2010-01-01

    The present study examined gender differences in the factor structure of the 2x2 achievement goal framework using a multi-sample invariance analysis. A total of 117 male and 125 female undergraduate teacher education students completed Elliot and Murayama's (2008) Achievement Goal Questionnaire-Revised (AGQ-R). Results provided empirical evidence…

  18. Understanding Student Goal Orientation Tendencies to Predict Student Performance: A 2x2 Achievement Goal Orientation

    ERIC Educational Resources Information Center

    Miller, Mark Alan

    2013-01-01

    The study tested the 2X2 model of the Achievement Goal Orientation (AGO) theory in a military technical training environment while using the Air Force Officers Qualifying Test's academic aptitude score to control for the differences in the students' academic aptitude. The study method was quantitative and the design was correlational.…

  19. Window types: (from left to right) Pair of 2x2 multipaned ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Window types: (from left to right) Pair of 2x2 multipaned steel casements; triplet of 1x4 multipaned steel casements (center panel fixed); 1x3 multipaned steel casements. Building 20, facing southwest - Harbor Hills Housing Project, 26607 Western Avenue, Lomita, Los Angeles County, CA

  20. Procrastination and the 2 x 2 Achievement Goal Framework in Malaysian Undergraduate Students

    ERIC Educational Resources Information Center

    Ganesan, Rajalakshmi; Mamat, Norul Hidayah Bt; Mellor, David; Rizzuto, Laura; Kolar, Christina

    2014-01-01

    The present study investigated academic procrastination in the context of the 2 x 2 goal achievement theoretical framework within a population of 450 Malaysian undergraduate students, aged 18 to 25 years. Participants completed the Achievement Goal Questionnaire and the Tuckman Procrastination Test. Approach dimensions of both the mastery and…

  1. Extending the 2 x 2 Achievement Goal Framework: Development of a Measure of Scientific Achievement Goals

    ERIC Educational Resources Information Center

    Deemer, Eric D.; Carter, Alice P.; Lobrano, Michael T.

    2010-01-01

    The current research sought to extend the 2 x 2 achievement goal framework by developing and testing the Achievement Goals for Research Scale (AGRS). Participants (N = 317) consisted of graduate students in the life, physical, and behavioral sciences. A principal components analysis (PCA) extracted five components accounting for 72.59% of the…

  2. The 2 x 2 Model of Perfectionism: A Comparison across Asian Canadians and European Canadians

    ERIC Educational Resources Information Center

    Franche, Veronique; Gaudreau, Patrick; Miranda, Dave

    2012-01-01

    The 2 x 2 model of perfectionism posits that the 4 within-person combinations of self-oriented and socially prescribed perfectionism (i.e., pure SOP, mixed perfectionism, pure SPP, and nonperfectionism) can be distinctively associated with psychological adjustment. This study examined whether the relationship between the 4 subtypes of…

  3. Prediction of intrinsic motivation and sports performance using 2 x 2 achievement goal framework.

    PubMed

    Li, Chiung-Huang; Chi, Likang; Yeh, Suh-Ruu; Guo, Kwei-Bin; Ou, Cheng-Tsung; Kao, Chun-Chieh

    2011-04-01

    The purpose of this study was to examine the influence of 2 x 2 achievement goals on intrinsic motivation and performance in handball. Participants were 164 high school athletes. All completed the 2 x 2 Achievement Goals Questionnaire for Sport and the Intrinsic Motivation subscale of the Sport Motivation Scale; the coach for each team rated his athletes' overall sports performance. Using simultaneous-regression analyses, mastery-approach goals positively predicted both intrinsic motivation and performance in sports, whereas performance-avoidance goals negatively predicted sports performance. These results suggest that athletes who pursue task mastery and improvement of their competence perform well and enjoy their participation. In contrast, those who focus on avoiding normative incompetence perform poorly.

  4. Entanglement monogamy inequality in a 2 x 2 x 4 system

    SciTech Connect

    Ren Xijun; Jiang Wei

    2010-02-15

    In this report, we show explicitly that the tangles of an arbitrary pure state in a 2 x 2 x 4 system satisfy the monogamy relation. This relation is also generalized to mixed states. As the tangle is always larger than the square of the concurrence, our result implies that the monogamy relation holds for concurrence too. It also supports the idea that the tangle could qualify as an elementary bipartite entanglement measure.

  5. 2 x 2 TeV mu(superscript +) mu (superscript) collider

    SciTech Connect

    Mokhov, N.V.; Noble, R.J.

    1996-10-01

    The scenarios for high-luminosity 2 x 2 TeV and 250 x 250 GeV {mu}{sup +}{mu}{sup -} colliders are presented. Having a high physics potential, such a machine has specific physics and technical advantages and disadvantages when compared with an e{sup +}e{sup -} collider. Parameters for the candidate designs and the basic components - proton source, pion production and decay channel, cooling, acceleration and collider storage ring - are considered. Attention is paid to the areas mostly affecting the collider performance: targetry, energy spread, superconducting magnet survival, detector backgrounds, polarization, environmental issues. 13 refs., 9 figs., 4 tabs.

  6. New coplanar waveguide feed network for 2 x 2 linearly tapered slot antenna subarray

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Perl, Thomas D.; Lee, Richard Q.

    1992-01-01

    A novel feed method is presently demonstrated for a 2 x 2 linearly tapered slot antenna (LTSA) on the basis of a coplanar-waveguide (CPW)-to-slotline transition and a coax-to-CPW in-phase, four-way power divider. The LTSA subarray exhibits excellent radiation patterns and return-loss characteristics at 18 GHz, and has symmetric beamwidth; its compactness renders it applicable as either a feed for a reflector antenna or as a building-block for large arrays.

  7. Supramolecular Co(II)-[2 x 2] grids: metamagnetic behavior in a single molecule.

    PubMed

    Waldmann, Oliver; Ruben, Mario; Ziener, Ulrich; Müller, Paul; Lehn, Jean M

    2006-08-07

    The magnetic anisotropy of the supramolecular [2 x 2] grid [Co(II)4L4]8+, with a bis(bipyridyl)-pyrimidine-based ligand L, was investigated by single-crystal magnetization measurements at low temperatures. The magnetization curves exhibit metamagnetic-like behavior and are explained by the weak-exchange limit of a minimal spin Hamiltonian including Heisenberg exchange, easy-axis ligand fields, and the Zeeman term. It is also shown that the magnetic coupling strength can be varied by the substituent R1 in the two-position on the central pyrimidine group of the ligand L.

  8. Operating manual holographic interferometry system for 2 x 2 foot transonic wind tunnel

    NASA Technical Reports Server (NTRS)

    Craig, J. E.

    1981-01-01

    A holographic interferometer system was installed in a 2X2 foot transonic wind tunnel. The system incorporates a modern, 10 pps, Nd:YAG pulsed laser which provides reliable operation and is easy to align. The spatial filtering requirements of the unstable resonator beam are described as well as the integration of the system into the existing Schieren system. A two plate holographic interferometer is used to reconstruct flow field data. For static wind tunnel models the single exposure holograms are recorded in the usual manner; however, for dynamic models such as oscillating airfoils, synchronous laser hologram recording is used.

  9. Examining Dual Meanings of Items in 2 x 2 Achievement Goal Questionnaires through MTMM Modeling and MDS Approach

    ERIC Educational Resources Information Center

    Wu, Chia-Huei; Chen, Lung Hung

    2010-01-01

    In 2001, Elliot and McGregor proposed a 2 x 2 (mastery-performance x approach- avoidance) achievement goal frameworks and developed a questionnaire to measure four goals (mastery-approach, mastery-avoidance, performance-approach, and performance-avoidance goals). This study examines the dual meanings of items in 2 x 2 achievement goal…

  10. [How I explore the various statistical facets of 2 x 2 tables in medicine].

    PubMed

    Albert, A

    2013-09-01

    In the medical scientific literature, 2 x 2 contingency tables are widely used to display the distribution of binary data. They are associated with the definition of basic concepts in medicine and epidemiology that are universally utilized. They are usually taught in any basic course in biostatistics early in the medical curriculum; their interpretation however is not always straightforward. We have discerned at least eight different facets of such fourfold tables: homogeneity test, independence test, McNemar test, Cohen kappa coefficient, incidence relative risk, prevalence relative risk, odds ratio, diagnostic value of a clinical test. Each facet is illustrated by a clinical problem used as an example. This article should help the reader to understand which table he/she is actually dealing with.

  11. Lunar radar backscatter studies

    NASA Technical Reports Server (NTRS)

    Thompson, T. W.

    1979-01-01

    The lunar surface material in the Plato area is characterized using Earth based visual, infrared, and radar signatures. Radar scattering in the lunar regolith with an existing optical scattering computer program is modeled. Mapping with 1 to 2 km resolution of the Moon using a 70 cm Arecibo radar is presented.

  12. The proposed flatland radar

    NASA Technical Reports Server (NTRS)

    Green, J. L.; Gage, K. S.; Vanzandt, T. E.; Nastrom, G. D.

    1986-01-01

    A flexible very high frequency (VHF) stratosphere-troposphere (ST) radar configured for meteorological research is to be constructed near Urbana, Illinois. Measurement of small vertical velocities associated with synoptic-scale meteorology can be performed. A large Doppler microwave radar (CHILL) is located a few km from the site of the proposed ST radar. Since the microwave radar can measure the location and velocity of hydrometeors and the VHF ST radar can measure clear (or cloudy) air velocities, simultaneous observations by these two radars of stratiform or convective weather systems would provide valuable meteorological information.

  13. Entanglement and dissipation in a 2x2 quantum-dot cell

    NASA Astrophysics Data System (ADS)

    Debora Contreras, Lesbia; Rojas, Fernando

    2005-03-01

    Quantum dot arrays or quantum-dot cellular automata (QCA) have been proposed as elements capable to encode, process and transmit logical information based on quantum effects in terms of charge distributions in specific geometries. and the basis for the charge qubits. Quantum Entanglement is a resource to encode information in a completely new way making possible quantum teleportation, quantum error correction, quantum dense coding. In this work, we explore the dynamical formation of entangled states including dissipative effects, of two parallel double dots (four dots, 2x2 cell), with one extra electron each, coupled by the Coulomb interaction and controlled by a time dependent potential difference applied to one of the double dots, causing the electron to switch. We include dissipative effects via electron-phonon interaction in the Markovian approximation for the reduced density matrix. Dynamical properties of the cell such as charge polarization, measure the entanglement (Wootters concurrence) and the probabilities for each Bell state, are discussed as a function of relevant parameters (tunneling, potential difference, temperature). We find that it is possible to obtain entangled states in the cell based on the electronic charge distribution and produce a specific Bell state from an initially non entangled state through the control of the time dependent potential. The work is supported by DGAPA project IN114403 and CONACyT project 43673-F

  14. Elucidating the foundations of statistical inference with 2 x 2 tables.

    PubMed

    Choi, Leena; Blume, Jeffrey D; Dupont, William D

    2015-01-01

    To many, the foundations of statistical inference are cryptic and irrelevant to routine statistical practice. The analysis of 2 x 2 contingency tables, omnipresent in the scientific literature, is a case in point. Fisher's exact test is routinely used even though it has been fraught with controversy for over 70 years. The problem, not widely acknowledged, is that several different p-values can be associated with a single table, making scientific inference inconsistent. The root cause of this controversy lies in the table's origins and the manner in which nuisance parameters are eliminated. However, fundamental statistical principles (e.g., sufficiency, ancillarity, conditionality, and likelihood) can shed light on the controversy and guide our approach in using this test. In this paper, we use these fundamental principles to show how much information is lost when the tables origins are ignored and when various approaches are used to eliminate unknown nuisance parameters. We present novel likelihood contours to aid in the visualization of information loss and show that the information loss is often virtually non-existent. We find that problems arising from the discreteness of the sample space are exacerbated by p-value-based inference. Accordingly, methods that are less sensitive to this discreteness - likelihood ratios, posterior probabilities and mid-p-values - lead to more consistent inferences.

  15. Robust optimization of 2x2 multimode interference couplers with fabrication uncertainties

    NASA Astrophysics Data System (ADS)

    Rehman, Samee ur; Langelaar, Matthijs; Van Keulen, Fred

    2013-03-01

    In this paper, we propose a novel design-for-manufacture strategy for integrated photonics which specifically addresses the commonly encountered scenario in which probability distributions of the manufacturing variations are not available, however their bounds are known. The best design point for the device, in the presence of these uncertainties, can be found by applying robust optimization. This is performed by minimizing the maximum realizable value of the objective with respect to the uncertainty set so that an optimum is found whose performance is relatively immune to fabrication variations. Instead of applying robust optimization directly on a computationally expensive simulation model of the integrated photonic device, we construct a cheap surrogate model by uniformly sampling the simulated device at different values of the design variables and interpolating the resulting objective using a Kriging metamodel. By applying robust optimization on the constructed surrogate, the global robust optimum can be found at low computational cost. As an illustration of the method's general applicability, we apply the robust optimization approach on a 2x2 multimode interference (MMI) coupler. We robustly minimize the imbalance in the presence of uncertainties arising from variations in the fabricated design geometry. For this example device, we also study the influence of the number of sample points on the quality of the metamodel and on the robust optimization process.

  16. Epitaxial growth and properties of MoOx(2<x <2.75) films

    NASA Astrophysics Data System (ADS)

    Bhosle, V.; Tiwari, A.; Narayan, J.

    2005-04-01

    We report the growth of epitaxial molybdenum oxide (MoOx,2<x<2.75) films on c plane of sapphire substrate using pulsed laser deposition in oxygen environment. The structure was characterized using x-ray diffraction, high resolution transmission electron microscopy and x-ray photoelectron spectroscopy (XPS). Electrical resistivity and optical properties were investigated using four-point-probe resistivity measurements and spectroscopy techniques, respectively. It was found that the film had a monoclinic structure based on MoO2 phase and showed an unusual combination of high conductivity and high transmittance in the visible region after annealing. The unusual combination of these properties was realized by systematically controlling the relative fraction of different oxidation states of molybdenum, namely Mo4+, Mo5+, and Mo6+ in the monoclinic phase. For a film 60nm thick and annealed at 250°C for 1h, the ratio of Mo6+/(Mo4++Mo5+) was determined to be ˜2.9/1 using XPS, and a typical value of transmittance was ˜65% and resistivity close to 1×10-3Ωcm. These results demonstrate growth of epitaxial MoOx films with tunable electrical and optical properties. Further optimization of these properties is expected to result in applications related to display panels, solar cells, chromogenic (photochromic, electrochromic, gasochromic) devices, and transparent conducting oxides. Our ability to grow epitaxial MoOx films can further aid their integration with optoelectronic and photonic devices.

  17. Elucidating the Foundations of Statistical Inference with 2 x 2 Tables

    PubMed Central

    Choi, Leena; Blume, Jeffrey D.; Dupont, William D.

    2015-01-01

    To many, the foundations of statistical inference are cryptic and irrelevant to routine statistical practice. The analysis of 2 x 2 contingency tables, omnipresent in the scientific literature, is a case in point. Fisher's exact test is routinely used even though it has been fraught with controversy for over 70 years. The problem, not widely acknowledged, is that several different p-values can be associated with a single table, making scientific inference inconsistent. The root cause of this controversy lies in the table's origins and the manner in which nuisance parameters are eliminated. However, fundamental statistical principles (e.g., sufficiency, ancillarity, conditionality, and likelihood) can shed light on the controversy and guide our approach in using this test. In this paper, we use these fundamental principles to show how much information is lost when the tables origins are ignored and when various approaches are used to eliminate unknown nuisance parameters. We present novel likelihood contours to aid in the visualization of information loss and show that the information loss is often virtually non-existent. We find that problems arising from the discreteness of the sample space are exacerbated by p-value-based inference. Accordingly, methods that are less sensitive to this discreteness - likelihood ratios, posterior probabilities and mid-p-values - lead to more consistent inferences. PMID:25849515

  18. Development of a 2x2 optical switch for plastic optical fiber using liquid crystal cells

    NASA Astrophysics Data System (ADS)

    Vazquez, Carmen; Sanchez-Pena, J. M.; Contreras, Pedro; Pontes, M. A. J.

    2005-07-01

    A 2x2 optical switch for plastic optical fibre (POF) has been developed, able to work for both 660 and 850nm simultaneous and independently of the input light's polarization, improving previous developments. The device has four bidirectional optical ports, and is able to switch from each port to any other. In this way, there are three operation modes: straight (each input connected to the corresponding output), crossed (inputs and outputs crosses) and closed (inputs connected on the one part, and output connected on the other part). As the device is bidirectional, inputs and outputs are interchangeable. The switching process is carried out by a set of Polarized Beam Splitters, Liquid Crystal cells, λ/4 plates, lens and mirrors. An electronic circuitry has been developed to control the state of the optical switch, which is shown in a Liquid Crystal Display. The system has been tested for both 660nm and 850nm, and the optical switch exhibits miliseconds switching times, an optical interchannel crosstalk better than -25 dB, and low power consumption. Applications of the switch include systems where a redundant path is needed to guarantee communication, such as safety systems in automobiles, LANs, telemedicine, heavy machinery in the industry along with coarse WDM GI (graded index) POF networks. Device size reduction is under development.

  19. Subunit-specific coupling between gamma-aminobutyric acid type A and P2X2 receptor channels.

    PubMed

    Boué-Grabot, Eric; Toulmé, Estelle; Emerit, Michel B; Garret, Maurice

    2004-12-10

    ATP and gamma-aminobutyric acid (GABA) are two fast neurotransmitters co-released at central synapses, where they co-activate excitatory P2X and inhibitory GABAA (GABA type A) receptors. We report here that co-activation of P2X2 and various GABAA receptors, co-expressed in Xenopus oocytes, leads to a functional cross-inhibition dependent on GABAA subunit composition. Sequential applications of GABA and ATP revealed that alphabeta- or alphabetagamma-containing GABAA receptors inhibited P2X2 channels, whereas P2X2 channels failed to inhibit gamma-containing GABAA receptors. This functional cross-talk is independent of membrane potential, changes in current direction, and calcium. Non-additive responses observed between cation-selective GABAA and P2X2 receptors further indicate the chloride independence of this process. Overexpression of minigenes encoding either the C-terminal fragment of P2X2 or the intracellular loop of the beta3 subunit disrupted the functional cross-inhibition. We previously demonstrated functional and physical cross-talk between rho1 and P2X2 receptors, which induced a retargeting of rho1 channels to surface clusters when co-expressed in hippocampal neurons (Boue-Grabot, E., Emerit, M. B., Toulme, E., Seguela, P., and Garret, M. (2004) J. Biol. Chem. 279, 6967-6975). Co-expression of P2X2 and chimeric rho1 receptors with the C-terminal sequences of alpha2, beta3, or gamma2 subunits indicated that only rho1-beta3 and P2X2 channels exhibit both functional cross-inhibition in Xenopus oocytes and co-clustering/retargeting in hippocampal neurons. Therefore, the C-terminal domain of P2X2 and the intracellular loop of beta GABAA subunits are required for the functional interaction between ATP- and GABA-gated channels. This gamma subunit-dependent cross-talk may contribute to the regulation of synaptic activity.

  20. Effects of protein deprivation and re-feeding on P2X2 receptors in enteric neurons

    PubMed Central

    Misawa, Rúbia; Girotti, Priscila Azevedo; Mizuno, Márcia Sanae; Liberti, Edson Aparecido; Furness, John Barton; Castelucci, Patricia

    2010-01-01

    AIM: To investigate the effects of malnutrition and re-feeding on the P2X2 receptor, nitric oxide synthase (NOS), calretinin, calbindin and choline acetyltransferase (ChAT) in neurons of the rat ileum. METHODS: We analyzed the co-localization, numbers and sizes of P2X2-expressing neurons in relation to NOS-immunoreactive (IR), calbindin-IR, ChAT-IR, and calretinin-IR neurons of the myenteric and submucosal plexus. The experimental groups consisted of: (1) rats maintained on normal feed throughout pregnancy until 42 d post-parturition (N); (2) rats deprived of protein throughout pregnancy and 42 d post-parturition (D); and (3) rats undernourished for 21 d post-parturition and then given a protein diet from days 22 to 42 (DR). The myenteric and submucosal plexuses were evaluated by double labeling by immunohistochemical methods for P2X2 receptor, NOS, ChAT, calbindin and calretinin. RESULTS: We found similar P2X2 receptor immunoreactivity in the cytoplasm and surface membranes of myenteric and submucosal neurons from the N, D and DR groups. Double labeling of the myenteric plexus demonstrated that approximately 100% of NOS-IR, calbindin-IR, calretinin-IR and ChAT-IR neurons in all groups also expressed the P2X2 receptor. In the submucosal plexus, the calretinin-IR, ChAT-IR and calbindin-IR neurons were nearly all immunoreactive for the P2X2 receptor. In the myenteric plexus, there was a 19% increase in numbers per cm2 for P2X2 receptor-IR neurons, 64% for NOS-IR, 84% for calretinin-IR and 26% for ChAT-IR neurons in the D group. The spatial density of calbindin-IR neurons, however, did not differ among the three groups. The submucosal neuronal density increased for calbindin-IR, calretinin-IR and ChAT-IR neurons. The average size of neurons in the myenteric plexus neurons in the D group was less than that in the controls and, in the re-fed rats; there was a 34% reduction in size only for the calretinin-IR neurons. CONCLUSION: This work demonstrates that expression of

  1. Unbalanced 2 x 2 factorial designs and the interaction effect: a troublesome combination.

    PubMed

    Landsheer, Johannes A; van den Wittenboer, Godfried

    2015-01-01

    In this power study, ANOVAs of unbalanced and balanced 2 x 2 datasets are compared (N = 120). Datasets are created under the assumption that H1 of the effects is true. The effects are constructed in two ways, assuming: 1. contributions to the effects solely in the treatment groups; 2. contrasting contributions in treatment and control groups. The main question is whether the two ANOVA correction methods for imbalance (applying Sums of Squares Type II or III; SS II or SS III) offer satisfactory power in the presence of an interaction. Overall, SS II showed higher power, but results varied strongly. When compared to a balanced dataset, for some unbalanced datasets the rejection rate of H0 of main effects was undesirably higher. SS III showed consistently somewhat lower power. When the effects were constructed with equal contributions from control and treatment groups, the interaction could be re-estimated satisfactorily. When an interaction was present, SS III led consistently to somewhat lower rejection rates of H0 of main effects, compared to the rejection rates found in equivalent balanced datasets, while SS II produced strongly varying results. In data constructed with only effects in the treatment groups and no effects in the control groups, the H0 of moderate and strong interaction effects was often not rejected and SS II seemed applicable. Even then, SS III provided slightly better results when a true interaction was present. ANOVA allowed not always for a satisfactory re-estimation of the unique interaction effect. Yet, SS II worked better only when an interaction effect could be excluded, whereas SS III results were just marginally worse in that case. Overall, SS III provided consistently 1 to 5% lower rejection rates of H0 in comparison with analyses of balanced datasets, while results of SS II varied too widely for general application.

  2. On Association Coefficients for 2x2 Tables and Properties that Do Not Depend on the Marginal Distributions

    ERIC Educational Resources Information Center

    Warrens, Matthijs J.

    2008-01-01

    We discuss properties that association coefficients may have in general, e.g., zero value under statistical independence, and we examine coefficients for 2x2 tables with respect to these properties. Furthermore, we study a family of coefficients that are linear transformations of the observed proportion of agreement given the marginal…

  3. TRMM radar

    NASA Technical Reports Server (NTRS)

    Okamoto, Kenichi

    1993-01-01

    The results of a conceptual design study and the performance of key components of the Bread Board Model (BBM) of the Tropical Rainfall Measuring Mission (TRMM) radar are presented. The radar, which operates at 13.8 GHz and is designed to meet TRMM mission objectives, has a minimum measurable rain rate of 0.5 mm/h with a range resolution of 250 m, a horizontal resolution of about 4 km, and a swath width of 220 km. A 128-element active phased array system is adopted to achieve contiguous scanning within the swath. The basic characteristics of BBM were confirmed by experiments. The development of EM started with the cooperation of NASDA and CRL.

  4. Millimeter Wave Cloud Radar (MMCR) Handbook

    SciTech Connect

    KB Widener; K Johnson

    2005-01-30

    The millimeter cloud radar (MMCR) systems probe the extent and composition of clouds at millimeter wavelengths. The MMCR is a zenith-pointing radar that operates at a frequency of 35 GHz. The main purpose of this radar is to determine cloud boundaries (e.g., cloud bottoms and tops). This radar will also report radar reflectivity (dBZ) of the atmosphere up to 20 km. The radar possesses a doppler capability that will allow the measurement of cloud constituent vertical velocities.

  5. Modulation of P2X3 and P2X2/3 Receptors by Monoclonal Antibodies.

    PubMed

    Shcherbatko, Anatoly; Foletti, Davide; Poulsen, Kris; Strop, Pavel; Zhu, Guoyun; Hasa-Moreno, Adela; Melton Witt, Jody; Loo, Carole; Krimm, Stellanie; Pios, Ariel; Yu, Jessica; Brown, Colleen; Lee, John K; Stroud, Robert; Rajpal, Arvind; Shelton, David

    2016-06-03

    Purinergic homomeric P2X3 and heteromeric P2X2/3 receptors are ligand-gated cation channels activated by ATP. Both receptors are predominantly expressed in nociceptive sensory neurons, and an increase in extracellular ATP concentration under pathological conditions, such as tissue damage or visceral distension, induces channel opening, membrane depolarization, and initiation of pain signaling. Hence, these receptors are considered important therapeutic targets for pain management, and development of selective antagonists is currently progressing. To advance the search for novel analgesics, we have generated a panel of monoclonal antibodies directed against human P2X3 (hP2X3). We have found that these antibodies produce distinct functional effects, depending on the homomeric or heteromeric composition of the target, its kinetic state, and the duration of antibody exposure. The most potent antibody, 12D4, showed an estimated IC50 of 16 nm on hP2X3 after short term exposure (up to 18 min), binding to the inactivated state of the channel to inhibit activity. By contrast, with the same short term application, 12D4 potentiated the slow inactivating current mediated by the heteromeric hP2X2/3 channel. Extending the duration of exposure to ∼20 h resulted in a profound inhibition of both homomeric hP2X3 and heteromeric hP2X2/3 receptors, an effect mediated by efficient antibody-induced internalization of the channel from the plasma membrane. The therapeutic potential of mAb12D4 was assessed in the formalin, complete Freund's adjuvant, and visceral pain models. The efficacy of 12D4 in the visceral hypersensitivity model indicates that antibodies against P2X3 may have therapeutic potential in visceral pain indications.

  6. Double P2X2/P2X3 Purinergic Receptor Knockout Mice Do Not Taste NaCl or the Artificial Sweetener SC45647

    PubMed Central

    Eddy, Meghan C.; Eschle, Benjamin K.; Barrows, Jennell; Hallock, Robert M.; Finger, Thomas E.

    2009-01-01

    The P2X ionotropic purinergic receptors, P2X2 and P2X3, are essential for transmission of taste information from taste buds to the gustatory nerves. Mice lacking both P2X2 and P2X3 purinergic receptors (P2X2/P2X3Dbl−/−) exhibit no taste-evoked activity in the chorda tympani and glossopharyngeal nerves when stimulated with taste stimuli from any of the 5 classical taste quality groups (salt, sweet, sour, bitter, and umami) nor do the mice show taste preferences for sweet or umami, or avoidance of bitter substances (Finger et al. 2005. ATP signaling is crucial for communication from taste buds to gustatory nerves. Science. 310[5753]:1495–1499). Here, we compare the ability of P2X2/P2X3Dbl−/− mice and P2X2/P2X3Dbl+/+ wild-type (WT) mice to detect NaCl in brief-access tests and conditioned aversion paradigms. Brief-access testing with NaCl revealed that whereas WT mice decrease licking at 300 mM and above, the P2X2/P2X3Dbl−/− mice do not show any change in lick rates. In conditioned aversion tests, P2X2/P2X3Dbl−/− mice did not develop a learned aversion to NaCl or the artificial sweetener SC45647, both of which are easily avoided by conditioned WT mice. The inability of P2X2/P2X3Dbl−/− mice to show avoidance of these taste stimuli was not due to an inability to learn the task because both WT and P2X2/P2X3Dbl−/− mice learned to avoid a combination of SC45647 and amyl acetate (an odor cue). These data suggest that P2X2/P2X3Dbl−/− mice are unable to respond to NaCl or SC45647 as taste stimuli, mirroring the lack of gustatory nerve responses to these substances. PMID:19833661

  7. Photoelectron diffraction k-space volumes of the c(2x2) Mn/Ni(100) structure

    SciTech Connect

    Banerjee, S.; Denlinger, J.; Chen, X.

    1997-04-01

    Traditionally, x-ray photoelectron diffraction (XPD) studies have either been done by scanning the diffraction angle for fixed kinetic energy (ADPD), or scanning the kinetic energy at fixed exit angle (EDPD). Both of these methods collect subsets of the full diffraction pattern, or volume, which is the intensity of photoemission as a function of momentum direction and magnitude. With the high density available at the Spectromicroscopy Facility (BL 7.0) {open_quotes}ultraESCA{close_quotes} station, the authors are able to completely characterize the photoelectron diffraction patterns of surface structures, up to several hundred electron volts kinetic energy. This large diffraction `volume` can then be analyzed in many ways. The k-space volume contains as a subset the energy dependent photoelectron diffraction spectra along all emission angles. It also contains individual, hemispherical, diffraction patterns at specific kinetic energies. Other `cuts` through the data set are also possible, revealing new ways of viewing photoelectron diffraction data, and potentially new information about the surface structure being studied. In this article the authors report a brief summary of a structural study being done on the c(2x2) Mn/Ni(100) surface alloy. This system is interesting for both structural and magnetic reasons. Magnetically, the Mn/Ni(100) surface alloy exhibits parallel coupling of the Mn and Ni moments, which is opposite to the reported coupling for the bulk, disordered, alloy. Structurally, the Mn atoms are believed to lie well above the surface plane.

  8. Maltodextrin and fat preference deficits in "taste-blind" P2X2/P2X3 knockout mice.

    PubMed

    Sclafani, Anthony; Ackroff, Karen

    2014-07-01

    Adenosine triphosphate is a critical neurotransmitter in the gustatory response to the 5 primary tastes in mice. Genetic deletion of the purinergic P2X2/P2X3 receptor greatly reduces the neural and behavioral response to prototypical primary taste stimuli. In this study, we examined the behavioral response of P2X double knockout mice to maltodextrin and fat stimuli, which appear to activate additional taste channels. P2X double knockout and wild-type mice were given 24-h choice tests (vs. water) with ascending concentrations of Polycose and Intralipid. In Experiment 1, naive double knockout mice, unlike wild-type mice, were indifferent to dilute (0.5-4%) Polycose solutions but preferred concentrated (8-32%) Polycose to water. In a retest, the Polycose-experienced double knockout mice, like wild-type mice, preferred all Polycose concentrations. In Experiment 2, naive double knockout mice, unlike wild-type mice, were indifferent to dilute (0.313-2.5%) Intralipid emulsions but preferred concentrated (5-20%) Intralipid to water. In a retest, the fat-experienced double knockout mice, like wild-type mice, strongly preferred 0.313-5% Intralipid to water. These results indicate that the inherent preferences of mice for maltodextrin and fat are dependent upon adenosine triphosphate taste cell signaling. With experience, however, P2X double knockout mice develop strong preferences for the nontaste flavor qualities of maltodextrin and fat conditioned by the postoral actions of these nutrients.

  9. Residual Chemosensory Capabilities in Double P2X2/P2X3 Purinergic Receptor Null Mice: Intraoral or Postingestive Detection?

    PubMed Central

    Hallock, Robert M.; Tatangelo, Marco; Barrows, Jennell

    2009-01-01

    Mice lacking the purinergic receptors, P2X2 and P2X3 (P2X2/P2X3Dbl−/−), exhibit essentially no tastant-evoked activity in the chorda tympani and glossopharyngeal nerves and substantial loss of tastant-evoked behavior as measured in long-term intake experiments. To assess whether the residual chemically driven behaviors in these P2X2/P2X3Dbl−/− mice were attributable to postingestive detection or oropharyngeal detection of the compounds, we used brief access lickometer tests to assess the behavioral capabilities of the P2X2/P2X3Dbl−/− animals. The P2X2/P2X3Dbl−/− mice showed avoidance to high levels (10 mM quinine and 10–30 mM denatonium benzoate) of classical “bitter”-tasting stimuli in 24-h, 2-bottle preference tests but minimal avoidance of these substances in the lickometer tests, suggesting that the strong avoidance in the intake tests was largely mediated by post-oral chemosensors. Similarly, increases in consumption of 1 M sucrose by P2X2/P2X3Dbl−/− mice in long-term intake tests were not mirrored by increases in consumption of sucrose in lickometer tests, suggesting that sucrose detection in these mice is mediated by postingestive consequences. In contrast, in brief access tests, P2X2/P2X3Dbl−/− mice avoided citric acid and hydrochloric acid at the same concentrations as their wild-type counterparts, indicating that these weak acids activate oropharyngeal chemoreceptors. PMID:19833662

  10. Equatorial MU Radar project

    NASA Astrophysics Data System (ADS)

    Yamamoto, Mamoru; Hashiguchi, H.; Tsuda, Toshitaka; Yamamoto, Masayuki

    Research Institute for Sustainable Humanosphere, Kyoto University (RISH) has been studying the atmosphere by using radars. The first big facility was the MU (Middle and Upper atmosphere) radar installed in Shiga, Japan in 1984. This is one of the most powerful and multi-functional radar, and is successful of revealing importance of atmospheric waves for the dynamical vertical coupling processes. The next big radar was the Equatorial Atmosphere Radar (EAR) installed at Kototabang, West Sumatra, Indonesia in 2001. The EAR was operated under close collaboration with LAPAN (Indonesia National Institute for Aeronautics and Space), and conducted the long-term continuous observations of the equatorial atmosphere/ionosphere for more than 10 years. The MU radar and the EAR are both utilized for inter-university and international collaborative research program for long time. National Institute for Polar Research (NIPR) joined EISCAT Scientific Association together with Nagoya University, and developed the PANSY radar at Syowa base in Antarctica as a joint project with University of Tokyo. These are the efforts of radar study of the atmosphere/ionosphere in the polar region. Now we can find that Japan holds a global network of big atmospheric/ionospheric radars. The EAR has the limitation of lower sensitivity compared with the other big radars shown above. RISH now proposes a plan of Equatorial MU Radar (EMU) that is to establish the MU-radar class radar next to the EAR. The EMU will have an active phased array antenna with the 163m diameter and 1055 cross-element Yagis. Total output power of the EMU will be more than 500kW. The EMU can detect turbulent echoes from the mesosphere (60-80km). In the ionosphere incoherent-scatter observations of plasma density, drift, and temperature would be possible. Multi-channel receivers will realize radar-imaging observations. The EMU is one of the key facilities in the project "Study of coupling processes in the solar-terrestrial system

  11. A scaled quantum mechanical force field for the sulfuryl halides. I. The symmetric halides SO2X2 (X=F, Cl, Br).

    PubMed

    Fernández, L E; Verón, M G; Varetti, E L

    2004-01-01

    Force fields and vibrational wavenumbers were calculated for the molecules SO2X2 (X=F, Cl, Br) using DFT techniques. The previously available experimental data and assignments for SO2F2 and SO2Cl2 were compared with the theoretical results and revised, and new low temperature infrared and Raman data were obtained for SO2Cl2. These data were subsequently used in the definition of scaled quantum mechanics force fields for such molecules. Adjusted wavenumbers were also predicted for the still unknown SO2Br2. A comparison is made with results published for the VO2X2- anions.

  12. A scaled quantum mechanical force field for the sulfuryl halides. I. The symmetric halides SO 2X 2 (X=F, Cl, Br)

    NASA Astrophysics Data System (ADS)

    Fernández, L. E.; Verón, M. G.; Varetti, E. L.

    2004-01-01

    Force fields and vibrational wavenumbers were calculated for the molecules SO 2X 2 (X=F, Cl, Br) using DFT techniques. The previously available experimental data and assignments for SO 2F 2 and SO 2Cl 2 were compared with the theoretical results and revised, and new low temperature infrared and Raman data were obtained for SO 2Cl 2. These data were subsequently used in the definition of scaled quantum mechanics force fields for such molecules. Adjusted wavenumbers were also predicted for the still unknown SO 2Br 2. A comparison is made with results published for the VO 2X 2- anions.

  13. Analysis of Interferometric Radar Data in a Queensland, Australia Tropical Rain Forest

    NASA Technical Reports Server (NTRS)

    Hensley, Scott; Rodriquez, Ernesto; Chapin, Elaine; Accad, Arnon

    1999-01-01

    The radar flies at 8000 m (24000 ft) above the ground and collects data in swath about 10 km wide. The radar simultaneously collects data from multiple frequencies and is capable of making interferometric radar measurements.

  14. X1X1X2X2/X1X2Y sex chromosome systems in the Neotropical Gymnotiformes electric fish of the genus Brachyhypopomus

    PubMed Central

    Cardoso, Adauto Lima; Pieczarka, Julio Cesar; Nagamachi, Cleusa Yoshiko

    2015-01-01

    Several types of sex chromosome systems have been recorded among Gymnotiformes, including male and female heterogamety, simple and multiple sex chromosomes, and different mechanisms of origin and evolution. The X1X1X2X2/X1X2Y systems identified in three species of this order are considered homoplasic for the group. In the genus Brachyhypopomus, only B. gauderio presented this type of system. Herein we describe the karyotypes of Brachyhypopomus pinnicaudatus and B. n. sp. FLAV, which have an X1X1X2X2/X1X2Y sex chromosome system that evolved via fusion between an autosome and the Y chromosome. The morphology of the chromosomes and the meiotic pairing suggest that the sex chromosomes of B. gauderio and B. pinnicaudatus have a common origin, whereas in B . n. sp. FLAV the sex chromosome system evolved independently. However, we cannot discard the possibility of common origin followed by distinct processes of differentiation. The identification of two new karyotypes with an X1X1X2X2/X1X2Y sex chromosome system in Gymnotiformes makes it the most common among the karyotyped species of the group. Comparisons of these karyotypes and the evolutionary history of the taxa indicate independent origins for their sex chromosomes systems. The recurrent emergence of the X1X1X2X2/X1X2Y system may represent sex chromosomes turnover events in Gymnotiformes. PMID:26273225

  15. TRPV1, ASICs and P2X2/3 expressed in bone cells simultaneously regulate bone metabolic markers in ovariectomized mice

    PubMed Central

    Kanaya, K.; Iba, K.; Dohke, T.; Okazaki, S.; Yamashita, T.

    2016-01-01

    Objectives: Nociceptors are expressed at peripheral terminals of neurons. Recent studies have shown that TRPV1, a nociceptor, is expressed in bone tissue and regulates bone metabolism. We have demonstrated that a TRPV1 antagonist improved pain-like behavior in ovariectomized (OVX) mice. The aim of this study was to determine whether nociceptors, including TRPV1, acid-sensing ion channel (ASIC) and P2X2/3 are expressed in bone cells, and to examine the effects of nociceptor antagonists on bone metabolism. Methods: The expression of nociceptors in femoral bone tissue and cultured bone marrow cells in OVX and sham-operated mice were examined. The effects of nociceptor antagonists on the up-regulated expression of bone metabolic markers, Runx2, Osterix, osteocalcin and RANKL, were also examined. Results: TRPV1, ASIC 2 and 3, and P2X2 and 3, were expressed in bone tissue and bone marrow cells, and the expression levels of ASIC1 and 2, and P2X2 were significantly increased in OVX mice in comparison with those in sham mice. Treatment with nociceptor antagonists significantly inhibited the expression of bone metabolic markers in OVX mice. Conclusion: An array of nociceptors, TRPV1, ASICs and P2X2/3, could simultaneously regulate not only increases in skeletal pain but also bone turnover in OVX mice. PMID:27282458

  16. Radar principles

    NASA Technical Reports Server (NTRS)

    Sato, Toru

    1989-01-01

    Discussed here is a kind of radar called atmospheric radar, which has as its target clear air echoes from the earth's atmosphere produced by fluctuations of the atmospheric index of refraction. Topics reviewed include the vertical structure of the atmosphere, the radio refractive index and its fluctuations, the radar equation (a relation between transmitted and received power), radar equations for distributed targets and spectral echoes, near field correction, pulsed waveforms, the Doppler principle, and velocity field measurements.

  17. Radar Imaging of Mercury

    NASA Astrophysics Data System (ADS)

    Harmon, John K.

    2007-10-01

    Earth-based radar has been one of the few, and one of the most important, sources of new information about Mercury during the three decades since the Mariner 10 encounters. The emphasis during the past 15 years has been on full-disk, dual-polarization imaging of the planet, an effort that has been facilitated by the development of novel radar techniques and by improvements in radar systems. Probably the most important result of the imaging work has been the discovery and mapping of radar-bright features at the poles. The radar scattering properties of these features, and their confinement to permanently shaded crater floors, is consistent with volume backscatter from a low-loss volatile such as clean water ice. Questions remain, however, regarding the source and long-term stability of the putative ice, which underscores the need for independent confirmation by other observational methods. Radar images of the non-polar regions have also revealed a plethora of bright features, most of which are associated with fresh craters and their ejecta. Several very large impact features, with rays and other bright ejecta spreading over distances of 1,000 km or more, have been traced to source craters with diameters of 80-125 km. Among these large rayed features are some whose relative faintness suggests that they are being observed in an intermediate stage of degradation. Less extended ray/ejecta features have been found for some of the freshest medium-size craters such as Kuiper and Degas. Much more common are smaller (<40 km diameter) fresh craters showing bright rim-rings but little or no ray structure. These smaller radar-bright craters are particularly common over the H-7 quadrangle. Diffuse areas of enhanced depolarized brightness have been found in the smooth plains, including the circum-Caloris planitiae and Tolstoj Basin. This is an interesting finding, as it is the reverse of the albedo contrast seen between the radar-dark maria and the radar-bright cratered highlands

  18. Radar Imaging of Mercury

    NASA Astrophysics Data System (ADS)

    Harmon, John K.

    Earth-based radar has been one of the few, and one of the most important, sources of new information about Mercury during the three decades since the Mariner 10 encounters. The emphasis during the past 15 years has been on full-disk, dual-polarization imaging of the planet, an effort that has been facilitated by the development of novel radar techniques and by improvements in radar systems. Probably the most important result of the imaging work has been the discovery and mapping of radar-bright features at the poles. The radar scattering properties of these features, and their confinement to permanently shaded crater floors, is consistent with volume backscatter from a low-loss volatile such as clean water ice. Questions remain, however, regarding the source and long-term stability of the putative ice, which underscores the need for independent confirmation by other observational methods. Radar images of the non-polar regions have also revealed a plethora of bright features, most of which are associated with fresh craters and their ejecta. Several very large impact features, with rays and other bright ejecta spreading over distances of 1,000 km or more, have been traced to source craters with diameters of 80-125 km. Among these large rayed features are some whose relative faintness suggests that they are being observed in an intermediate stage of degradation. Less extended ray/ejecta features have been found for some of the freshest medium-size craters such as Kuiper and Degas. Much more common are smaller (<40 km diameter) fresh craters showing bright rim-rings but little or no ray structure. These smaller radar-bright craters are particularly common over the H-7 quadrangle. Diffuse areas of enhanced depolarized brightness have been found in the smooth plains, including the circum-Caloris planitiae and Tolstoj Basin. This is an interesting finding, as it is the reverse of the albedo contrast seen between the radar-dark maria and the radar-bright cratered highlands

  19. A galaxy with a 3.2 X 2.2 sq KPC H II region surrounding its nucleus

    NASA Astrophysics Data System (ADS)

    Meaburn, J.

    1983-06-01

    The spiral galaxy MCG-05-32-052 has a supergiant H II region surrounding its nucleus. The outer regions of this galaxy are in circular motion at ≅115 km s-1 but non-circular motions over a range of 100 km s-1 are found around the nucleus. Brightness ratios of the optical emission lines indicate that radiative ionization is predominant and a rate of emission of Lyman photons in the range 0.4 to 1.3×1053 s-1 is required to produce the total Hα intensity. A total ionized mass in the range 1.3 to 4×107 M_sun; is calculated and the total stellar mass in the central regions out to a radius of 1450 pc is given as 2.4×109 M_sun;. Three sources for this ionization and large motions are considered: either rich clusters of numerous ordinary OB stars with stellar winds and recurrent supernova explosions or one or several supermassive stars like the central object R 136a inside the 30 Dor nebula.

  20. 2x2 MIMO-OFDM Gigabit fiber-wireless access system based on polarization division multiplexed WDM-PON.

    PubMed

    Deng, Lei; Pang, Xiaodan; Zhao, Ying; Othman, M B; Jensen, Jesper Bevensee; Zibar, Darko; Yu, Xianbin; Liu, Deming; Monroy, Idelfonso Tafur

    2012-02-13

    We propose a spectral efficient radio over wavelength division multiplexed passive optical network (WDM-PON) system by combining optical polarization division multiplexing (PDM) and wireless multiple input multiple output (MIMO) spatial multiplexing techniques. In our experiment, a training-based zero forcing (ZF) channel estimation algorithm is designed to compensate the polarization rotation and wireless multipath fading. A 797 Mb/s net data rate QPSK-OFDM signal with error free (<1 × 10(5)) performance and a 1.59 Gb/s net data rate 16QAM-OFDM signal with BER performance of 1.2 × 10(2) are achieved after transmission of 22.8 km single mode fiber followed by 3 m and 1 m air distances, respectively.

  1. 40Km Into Lebanon,

    DTIC Science & Technology

    1987-07-01

    answer to the difficulties in Palestine, London organized a study of the problem under Lord Peel , a for- mer Secretary of State for India, who in 1937...issued the report of the Commission bearing his name. As Peel saw it, the only solution was to partition Palestine between the two communities. The...minority suggestions. The majority 22 40Km into Lebanon report recommended partition with an economic union, much as Peel had proposed in 1937. A

  2. Sport ability beliefs, 2 x 2 achievement goals, and intrinsic motivation: the moderating role of perceived competence in sport and exercise.

    PubMed

    Wang, C K John; Liu, Woon Chia; Lochbaum, Marc R; Stevenson, Sarah J

    2009-06-01

    We examined whether perceived competence moderated the relationships between implicit theories, 2 x 2 achievement goals, and intrinsic motivation for sports and physical activity. We placed 309 university students into high and moderate perceived competence groups. When perceived competence was high, entity beliefs did not predict the performance-avoidance goal; yet when perceived competence was moderately low, entity beliefs did predict this goal. The mastery-avoidance goal had no relationship with intrinsic motivation when perceived competence was high, but had a significant negative relationship when perceived competence was moderately low. Our findings highlight the importance of reexamining the role of perceived competence when studying implicit beliefs and the 2 x 2 achievement goals.

  3. Minodronic acid induces morphological changes in osteoclasts at bone resorption sites and reaches a level required for antagonism of purinergic P2X2/3 receptors.

    PubMed

    Tanaka, Makoto; Hosoya, Akihiro; Mori, Hiroshi; Kayasuga, Ryoji; Nakamura, Hiroaki; Ozawa, Hidehiro

    2017-02-27

    Minodronic acid is an aminobisphosphonate that is an antagonist of purinergic P2X2/3 receptors involved in pain. The aim of this study was to investigate the action and distribution of minodronic acid and the potential for P2X2/3 receptor antagonism based on the estimated concentration of minodronic acid. Microlocalization of radiolabeled minodronic acid was examined in the femur of neonatal rats. The bone-binding characteristics of minodronic acid and morphological changes in osteoclasts were analyzed in vitro. The minodronic acid concentration around bone resorption lacunae was predicted based on bone binding and the shape of lacunae. In microautoradiography, radioactive silver grains were abundant in bone-attached osteoclasts and were detected in calcified and ossification zones and in the cytoplasm of osteoclasts but not in the hypertrophic cartilage zone. In an osteoclast culture with 1 µM minodronic acid, 65% of minodronic acid was bound to bone, and C-terminal cross-linking telopeptide release was inhibited by 96%. Cultured osteoclasts without minodronic acid treatment formed ruffled borders and bone resorption lacunae and had rich cytoplasm, whereas those treated with 1 µM minodronic acid were not multinucleated, stained densely with toluidine blue, and were detached from the bone surface. In the 1 µM culture, the estimated minodronic acid concentration in resorption lacunae was 880 µM, which is higher than the IC50 for minodronic acid antagonism of P2X2/3 receptors. Thus, inhibition of P2X2/3 receptors around osteoclasts may contribute to the analgesic effect of minodronic acid.

  4. The MST Radar Technique

    NASA Technical Reports Server (NTRS)

    Balsley, B. B.

    1985-01-01

    The past ten year have witnessed the development of a new radar technique to examine the structure and dynamics of the atmosphere between roughly 1 to 100 km on a continuous basis. The technique is known as the MST (for Mesosphere-Stratosphere-Troposphere) technique and is usable in all weather conditions, being unaffected by precipitation or cloud cover. MST radars make use of scattering from small scale structure in the atmospheric refractive index, with scales of the order of one-half the radar wavelength. Pertinent scale sizes for middle atmospheric studies typically range between a fraction of a meter and a few meters. The structure itself arises primarily from atmospheric turbulence. The technique is briefly described along with the meteorological parameters it measures.

  5. Planetary Radar

    NASA Technical Reports Server (NTRS)

    Neish, Catherine D.; Carter, Lynn M.

    2015-01-01

    This chapter describes the principles of planetary radar, and the primary scientific discoveries that have been made using this technique. The chapter starts by describing the different types of radar systems and how they are used to acquire images and accurate topography of planetary surfaces and probe their subsurface structure. It then explains how these products can be used to understand the properties of the target being investigated. Several examples of discoveries made with planetary radar are then summarized, covering solar system objects from Mercury to Saturn. Finally, opportunities for future discoveries in planetary radar are outlined and discussed.

  6. Mars Radar Observations with the Goldstone Solar System Radar

    NASA Technical Reports Server (NTRS)

    Haldemann, A. F. C.; Jurgens, R. F.; Larsen, K. W.; Arvidson, R. E.; Slade, M. A.

    2002-01-01

    The Goldstone Solar System Radar (GSSR) has successfully collected radar echo data from Mars over the past 30 years. As such, the GSSR has played a role as a specific mission element within Mars exploration. The older data provided local elevation information for Mars, along with radar scattering information with global resolution. Since the upgrade to the 70-m Deep Space Network (DSN) antenna at Goldstone completed in 1986, Mars data has been collected during all but the 1997 Mars opposition. Radar data, and non-imaging delay-Doppler data in particular, requires significant data processing to extract elevation, reflectivity and roughness of the reflecting surface. The spatial resolution of these experiments is typically some 20 km in longitude by some 150 km in latitude. The interpretation of these parameters while limited by the complexities of electromagnetic scattering, do provide information directly relevant to geophysical and geomorphic analyses of Mars. The usefulness of radar data for Mars exploration has been demonstrated in the past. Radar data were critical in assessing the Viking Lander 1 site as well as, more recently, the Pathfinder landing site. In general, radar data have not been available to the Mars exploration community at large. A project funded initially by the Mars Exploration Directorate Science Office at the Jet Propulsion Laboratory (JPL), and later funded by NASA's Mars Data Analysis Program has reprocessed to a common format a decade's worth of raw GSSR Mars delay-Doppler data in aid of landing site characterization for the Mars Program. These data will soon be submitted to the Planetary Data System (PDS). The radar data used were obtained between 1988 and 1995 by the GSSR, and comprise some 63 delay-Doppler radar tracks. Of these, 15 have yet to be recovered from old 9-track tapes, and some of the data may be permanently lost.

  7. Modulation of bladder afferent signals in normal and spinal cord-injured rats by purinergic P2X3 and P2X2/3 receptors

    PubMed Central

    Munoz, Alvaro; Somogyi, George T.; Boone, Timothy B.; Ford, Anthony P.; Smith, Christopher P.

    2015-01-01

    OBJECTIVE • To evaluate the role of bladder sensory purinergic P2X3 and P2X2/3 receptors on modulating the activity of lumbosacral neurones and urinary bladder contractions in vivo in normal or spinal cord-injured (SCI) rats with neurogenic bladder overactivity. MATERIALS AND METHODS • SCI was induced in female rats by complete transection at T8 – T9 and experiments were performed 4 weeks later, when bladder overactivity developed. Non-transected rats were used as controls (normal rats). • Neural activity was recorded in the dorsal horn of the spinal cord and field potentials were acquired in response to intravesical pressure steps via a suprapubic catheter. Field potentials were recorded under control conditions, after stimulation of bladder mucosal purinergic receptors with intravesical ATP (1 mm), and after intravenous injection of the P2X3/P2X2/3 antagonist AF-353 (10 mg/kg and 20 mg/kg). • Cystometry was performed in urethaneanaesthetised rats intravesically infused with saline. AF-353 (10 mg/kg) was systemically applied after baseline recordings; the rats also received a second dose of AF-353 (20 mg/kg). Changes in the frequency of voiding (VC) and non-voiding (NVC) contractions were evaluated. RESULTS • SCI rats had significantly higher frequencies for field potentials and NVC than NL rats. Intravesical ATP increased field potential frequency in control but not SCI rats, while systemic AF-353 significantly reduced this parameter in both groups. • AF-353 also reduced the inter-contractile interval in control but not in SCI rats; however, the frequency of NVC in SCI rats was significantly reduced. CONCLUSION • The P2X3/P2X2/3 receptors on bladder afferent nerves positively regulate sensory activity and NVCs in overactive bladders. PMID:22540742

  8. Adsorption of water on O(2x2)/Ru(0001): thermal stability and inhibition of dissociation by H2O-O bonding

    SciTech Connect

    Mugarza, Aitor; Shimizu, Tomoko; Cabrera-Sanfelix, Pepa; Sanchez-Portal, Daniel; Arnau, Andres; Salmeron, Miquel

    2008-08-01

    The effect of preadsorbed oxygen on the subsequent adsorption and reactions of water on Ru(0001) has been studied using low temperature scanning tunneling microscopy and DFT calculations. Experiments were carried out for O coverages close to 0.25 ML. It was found that no dissociation of water takes place up to the desorption temperature of {approx}180-230 K. DFT calculations show that intact water on O(2x2)/Ru(0001) is {approx} 0.49 eV more stable than the dissociation products, H and OH, at their preferred fcc and top adsorption sites.

  9. A 2x2 W-Band Reference Time-Shifted Phase-Locked Transmitter Array in 65nm CMOS Technology

    NASA Technical Reports Server (NTRS)

    Tang, Adrian; Virbila, Gabriel; Hsiao, Frank; Wu, Hao; Murphy, David; Mehdi, Imran; Siegel, P. H.; Chang, M-C. Frank

    2013-01-01

    This paper presents a complete 2x2 phased array transmitter system operating at W-band (90-95 GHz) which employs a PLL reference time-shifting approach instead of using traditional mm-wave phase shifters. PLL reference shifting enables a phased array to be distributed over multiple chips without the need for coherent mm-wave signal distribution between chips. The proposed phased array transmitter system consumes 248 mW per array element when implemented in a 65 nm CMOS technology.

  10. Spaceborne radar

    NASA Technical Reports Server (NTRS)

    Moore, R. K.; Eckerman, J.; Meneghini, R.; Atlas, D.; Boerner, W. M.; Cherry, S.; Clark, J. F.; Doviak, R. J.; Goldhirsh, J.; Lhermitte, R. M.

    1981-01-01

    The spaceborne radar panel considered how radar could be used to measure precipitation from satellites. The emphasis was on how radar could be used with radiometry (at microwave, visible (VIS), and infrared (IR) wavelengths) to reduce the uncertainties of measuring precipitation with radiometry alone. In addition, the fundamental electromagnetic interactions involved in the measurements were discussed to determine the key work areas for research and development to produce effective instruments. Various approaches to implementing radar systems on satellites were considered for both shared and dedicated instruments. Finally, a research and development strategy was proposed for establishing the parametric relations and retrieval algorithms required for extracting precipitation information from the radar and associated radiometric data.

  11. MER vistas: ground-truth for Earth-based radar

    NASA Technical Reports Server (NTRS)

    Haldemann, Albert F.; Larsen, Kristopher W.; Jurgens, Raymond F.; Golombek, Matthew P.; Slade, Martin A.

    2004-01-01

    Earth-based delay-Doppler radar observations of Mars with four receiving stations were carried out during the Mars oppositions of 2001 and 2003 in support of Mars Exploration Rover landing site selection. This interferometric planetary radar technique has demonstrated radar mapping of Mars with a 5 km spatial resolution.

  12. Radar observations of asteroid 1580 Betulia

    NASA Technical Reports Server (NTRS)

    Pettengill, G. H.; Ostro, S. J.; Shapiro, I. I.; Marsden, B. G.; Campbell, D. B.

    1979-01-01

    Radar observations of the asteroid 1580 Betulia, made at a wavelength of 12.6 cm, show a mean radar cross section of 2.2 + or- 0.8 sq km and a total spectral bandwidth of 26.5 + or- 1.5 Hz. Combining bandwidth measurements with the optically determined rotation period sets a lower limit to the asteroid's radius of 2.9 + or- 0.2 km.

  13. Computer-aided design of AD 2 X 2 intermetallics with a ThCr2Si2-type of crystal structure

    NASA Astrophysics Data System (ADS)

    Kiselyova, N. N.; Sen'ko, O. V.; Kropotov, D. A.; Dokukin, A. A.

    2012-07-01

    Several hundred new AD 2 X 2 ( A and D are various elements; X = B, Al, Si, P, Ga, Ge, As, Sn, Sb) compounds are computer designed, and the types of their crystal structures under normal conditions are predicted. A special software package is used for the calculations; it includes a set of databases on the properties of inorganic substances and materials and a system for an analysis of these data, which is based on precedent pattern recognition methods. Only data on the properties of the elements entering into the compound compositions are used to predict unknown compounds. The parameters of elements in positions A and D (i.e., the Mendeleev-Pettifor numbers, the pseudopotential radii, and their algebraic functions) are found to mainly determine the possibility of formation of AD 2 X 2 compounds and the type of their crystal structures. New compounds of AD 2B2, AD 2Ga2, and AD 2Sn2 compositions are predicted for the first time.

  14. Digital Elevation Models of Greenland based on combined radar and laser altimetry as well as high-resolution stereoscopic imagery

    NASA Astrophysics Data System (ADS)

    Levinsen, J. F.; Smith, B. E.; Sandberg Sorensen, L.; Khvorostovsky, K.; Simonsen, S. B.; Forsberg, R.

    2015-12-01

    A number of Digital Elevation Models (DEMs) of Greenland exist, each of which are applicable for different purposes. This study presents two such DEMs: One developed by merging contemporary radar and laser altimeter data, and one derived from high-resolution stereoscopic imagery. All products are made freely available. The former DEM covers the entire Greenland. It is specific to the year 2010, providing it with an advantage over previous models suffering from either a reduced spatial/ temporal data coverage or errors from surface elevation changes (SEC) occurring during data acquisition. Radar data are acquired with Envisat and CryoSat-2, and laser data with the Ice, Cloud, and land Elevation Satellite, the Land, Vegetation, and Ice Sensor, and the Airborne Topographic Mapper. Correcting radar data for errors from slope effects and surface penetration of the echoes, and merging these with laser data, yields a DEM capable of resolving both surface depressions as well as topographic features at higher altitudes. The spatial resolution is 2 x 2 km, making the DEM ideal for application in surface mass balance studies, SEC detection from radar altimetry, or for correcting such data for slope-induced errors. The other DEM is developed in a pilot study building the expertise to map all ice-free parts of Greenland. The work combines WorldView-2 and -3 as well as GeoEye1 imagery from 2014 and 2015 over the Disko, Narsaq, Tassilaq, and Zackenberg regions. The novelty of the work is the determination of the product specifications after elaborate discussions with interested parties from government institutions, the tourist industry, etc. Thus, a 10 m DEM, 1.5 m orthophotos, and vector maps are produced. This opens to the possibility of using orthophotos with up-to-date contour lines or for deriving updated coastlines to aid, e.g., emergency management. This allows for a product development directly in line with the needs of parties with specific interests in Greenland.

  15. Venus - First Radar Test

    NASA Technical Reports Server (NTRS)

    1990-01-01

    After traveling more than 1.5 billion kilometers (948 million miles), the Magellan spacecraft was inserted into orbit around Venus on Aug. 10, 1990. This mosaic consists of adjacent pieces of two Magellan image strips obtained on Aug. 16 in the first radar test. The radar test was part of a planned In Orbit Checkout sequence designed to prepare the Magellan spacecraft and radar to begin mapping after Aug. 31. The strip on the left was returned to the Goldstone Deep Space Network station in California; the strip to the right was received at the DSN in Canberra, Australia. A third station that will be receiving Magellan data is located near Madrid, Spain. Each image strip is 20 km (12 miles) wide and 16,000 km (10,000 miles) long. This mosaic is a small portion 80 km (50 miles) long. This image is centered at 21 degrees north latitude and 286.8 degrees east longitude, southeast of a volcanic highland region called Beta Regio. The resolution of the image is about 120 meters (400 feet), 10 times better than previous images of the same area of Venus, revealing many new geologic features. The bright line trending northwest southeast across the center of the image is a fracture or fault zone cutting the volcanic plains. In the upper left corner of the image, a multiple ring circular feature of probable volcanic origin can be seen, approximately 4.27 km (2.65 miles) across. The bright and dark variations seen in the plains surrounding these features correspond to volcanic lava flows of varying ages. The volcanic lava flows in the southern half of the image have been cut by north south trending faults. This area is similar geologically to volcanic deposits seen on Earth at Hawaii and the Snake River Plains in Idaho.

  16. Scanning-Pencil-Beam Radar Scatterometer

    NASA Technical Reports Server (NTRS)

    Long, David G.; Freilich, Michael H.; Leotta, Daniel F.; Noon, Don E.

    1992-01-01

    SCANSCAT conceptual scanning radar scatterometer placed in nearly polar orbit around Earth at altitude of 705 km aboard Spacecraft B of NASA's Earth Observing System. Measures radar backscattering from surface of ocean. Data processed on ground into normalized radar-backscattering cross sections, then processed into velocities of winds near surface of ocean by use of empirical mathematical model of relationship between normalized backscattering cross section, wind vector at scanned spot, and angle of incidence and azimuth angle of radar beam. Accuracy and coverage exceeds those of fan-beam scatterometer. Modified versions of scanning plan useful in laser inspection of surface finishes on machined parts.

  17. RADAR WARNING SYSTEM,

    DTIC Science & Technology

    RADAR TRACKING, *AIRCRAFT DEFENSE SYSTEMS, RADAR EQUIPMENT, AIR TO AIR, SEARCH RADAR, GUIDED MISSILES, HIGH SPEED BOMBING, EARLY WARNING SYSTEMS, FIRE CONTROL SYSTEM COMPONENTS, AIRCRAFT, TIME, CHINA.

  18. SMAP Radar Processing and Calibration

    NASA Technical Reports Server (NTRS)

    West, R.; Jaruwatanadilok, S.; Kwoun, O.; Chaubell, M.

    2013-01-01

    The Soil Moisture Active Passive (SMAP) mission is part of the NASA space-based Earth observation program, and consists of an L-band radar and radiometer scheduled for launch into sun synchronous orbit in late 2014. A joint effort of the Jet Propulsion Laboratory (JPL) and the Goddard Space Flight Center (GSFC), the SMAP mission draws heavily on the design and risk reduction heritage of the Hydrosphere State (Hydros) mission [1], [2]. The SMAP science and applications objectives are to: 1) understand processes that link the terrestrial water, energy and carbon cycles, 2) estimate global water and energy fluxes at the land surface, 3) quantify net carbon flux in boreal landscapes, 4) enhance weather and climate forecast skill, and 5) develop improved flood prediction and drought monitoring capability. To meet these science objectives, SMAP ground processing will combine the attributes of the radar and radiometer observations (in terms of their spatial resolution and sensitivity to soil moisture, surface roughness, and vegetation) to estimate soil moisture with 4% volumetric accuracy at a resolution of 10 km, and freeze-thaw state at a resolution of 1-3 km. Model sensitivities translate the soil moisture accuracy to a radar backscatter accuracy of 1 dB (1 sigma) at 3 km resolution and a brightness temperature accuracy of 1.3 K at 40 km resolution. This paper will describe the level 1 radar processing and calibration challenges and the choices made so far for the algorithms and software implementation.

  19. High performace silicon 2x2 optical switch based on a thermo-optically tunable multimode interference coupler and efficient electrodes.

    PubMed

    Rosa, Álvaro; Gutiérrez, Ana; Brimont, Antoine; Griol, Amadeu; Sanchis, Pablo

    2016-01-11

    Optical switches based on tunable multimode interference (MMI) couplers can simultaneously reduce the footprint and increase the tolerance against fabrication deviations. Here, a compact 2x2 silicon switch based on a thermo-optically tunable MMI structure with a footprint of only 0.005 mm(2) is proposed and demonstrated. The MMI structure has been optimized using a silica trench acting as a thermal isolator without introducing any substantial loss penalty or crosstalk degradation. Furthermore, the electrodes performance have significantly been improved via engineering the heater geometry and using two metallization steps. Thereby, a drastic power consumption reduction of around 90% has been demonstrated yielding to values as low as 24.9 mW. Furthermore, very fast switching times of only 1.19 µs have also been achieved.

  20. Chemical pressure effects on magnetism in the quantum spin liquid candidates Yb2X2O7 (X =Sn, Ti, Ge)

    NASA Astrophysics Data System (ADS)

    Dun, Z. L.; Lee, M.; Choi, E. S.; Hallas, A. M.; Wiebe, C. R.; Gardner, J. S.; Arrighi, E.; Freitas, R. S.; Arevalo-Lopez, A. M.; Attfield, J. P.; Zhou, H. D.; Cheng, J. G.

    2014-02-01

    The linear and nonlinear ac susceptibility measurements of Yb-pyrochlores, Yb2X2O7 (X =Sn, Ti, and Ge), show transitions with a ferromagnetic nature at 0.13 and 0.25 K for Yb2Sn2O7 and Yb2Ti2O7, respectively, and an antiferromagnetic ordering at 0.62 K for Yb2Ge2O7. These systematical results (i) provided information about the nature of the unconventional magnetic ground state in Yb2Ti2O7; (ii) realized a distinct antiferromagnetic ordering state in Yb2Ge2O7; and (iii) demonstrated that the application of chemical pressure through the series of Yb-pyrochlores can efficiently perturb the fragile quantum spin fluctuations of the Yb3+ ions and lead to very different magnetic ground states.

  1. Driven evolution of a constitutional dynamic library of molecular helices toward the selective generation of [2 x 2] gridlike arrays under the pressure of metal ion coordination.

    PubMed

    Giuseppone, Nicolas; Schmitt, Jean-Louis; Lehn, Jean-Marie

    2006-12-27

    Constitutional dynamics, self-assembly, and helical-folding control are brought together in the efficient Sc(OTf)3/microwave-catalyzed transimination of helical oligohydrazone strands, yielding highly diverse dynamic libraries of interconverting constituents through assembly, dissociation, and exchange of components. The transimination-type mechanism of the ScIII-promoted exchange, as well as its regioselectivity, occurring only at the extremities of the helical strands, allow one to perform directional terminal polymerization/depolymerization processes when starting with dissymmetric strands. A particular library is subsequently brought to express quantitatively [2 x 2] gridlike metallosupramolecular arrays in the presence of ZnII ions by component recombination generating the correct ligand from the dynamic set of interconverting strands. This behavior represents a process of driven evolution of a constitutional dynamic chemical system under the pressure (coordination interaction) of an external effector (metal ions).

  2. Results of the AFRSI rewaterproofing systems screening test in the NASA/Ames Research Center (ARC) 2 x 2-foot transonic wind tunnel

    NASA Technical Reports Server (NTRS)

    Marroquin, J.; Kingsland, R. B.

    1985-01-01

    An experimental investigation was conducted in the NASA/Ames Research Center 2x2-foot Transonic Wind Tunnel to evaluate two AFRSI rewaterproofing systems and to investigate films as a means of reducing blanket joint distortion. The wind tunnel wall slot configuration influenced on the flow field over the test panel was investigated; primarily using oil flow data, and resulted in a closed slot configuration to provide a satisfactory screening environment flow field for the test. Sixteen AFRSI test panels, configured to represent the test system or film, were subjected to this screening environment (a flow field of separated and reattached flow at a freestream Mach numnber of 0.65 and q = 650 or 900 psf). Each condition was held until damage to the test article was observed or 55 minutes if no damage was incurred. All objectives related to AFRSI rewaterproofing and to the use of films to stiffen the blanket fibers were achieved.

  3. Debris Flux Comparisons From The Goldstone Radar, Haystack Radar, and Hax Radar Prior, During, and After the Last Solar Maximum

    NASA Technical Reports Server (NTRS)

    Stokely, C. L.; Stansbery, E. G.; Goldstein, R. M.

    2006-01-01

    The continual monitoring of low Earth orbit (LEO) debris environment using highly sensitive radars is essential for an accurate characterization of these dynamic populations. Debris populations are continually evolving since there are new debris sources, previously unrecognized debris sources, and debris loss mechanisms that are dependent on the dynamic space environment. Such radar data are used to supplement, update, and validate existing orbital debris models. NASA has been utilizing radar observations of the debris environment for over a decade from three complementary radars: the NASA JPL Goldstone radar, the MIT Lincoln Laboratory (MIT/LL) Long Range Imaging Radar (known as the Haystack radar), and the MIT/LL Haystack Auxiliary radar (HAX). All of these systems are highly sensitive radars that operate in a fixed staring mode to statistically sample orbital debris in the LEO environment. Each of these radars is ideally suited to measure debris within a specific size region. The Goldstone radar generally observes objects with sizes from 2 mm to 1 cm. The Haystack radar generally measures from 5 mm to several meters. The HAX radar generally measures from 2 cm to several meters. These overlapping size regions allow a continuous measurement of cumulative debris flux versus diameter from 2 mm to several meters for a given altitude window. This is demonstrated for all three radars by comparing the debris flux versus diameter over 200 km altitude windows for 3 nonconsecutive years from 1998 through 2003. These years correspond to periods before, during, and after the peak of the last solar cycle. Comparing the year to year flux from Haystack for each of these altitude regions indicate statistically significant changes in subsets of the debris populations. Potential causes of these changes are discussed. These analysis results include error bars that represent statistical sampling errors, and are detailed in this paper.

  4. Vascular Endothelial Cells Mediate Mechanical Stimulation-Induced Enhancement of Endothelin Hyperalgesia via Activation of P2X2/3 Receptors on Nociceptors

    PubMed Central

    Joseph, Elizabeth K.; Green, Paul G.; Bogen, Oliver; Alvarez, Pedro; Levine, Jon D.

    2013-01-01

    Endothelin-1 (ET-1) is unique amongst a broad range of hyperalgesic agents in that it induces hyperalgesia in rats that is markedly enhanced by repeated mechanical stimulation at the site of administration. Antagonists to the ET-1 receptors, ETA and ETB, attenuated both initial as well as stimulation-induced enhancement of hyperalgesia (SIEH) by endothelin. However, administering antisense oligodeoxynucleotide to attenuate ETA receptor expression on nociceptors attenuated ET-1 hyperalgesia, but had no effect on SIEH suggesting that this is mediated via a non-neuronal cell. Since vascular endothelial cells are both stretch-sensitive and express ETA and ETB receptors, we tested the hypothesis that SIEH is dependent on endothelial cells by impairing vascular endothelial function with octoxynol-9 administration; this procedure eliminated SIEH without attenuating ET-1 hyperalgesia. A role for protein kinase C epsilon (PKCε), a second messenger implicated in the induction and maintenance of chronic pain, was explored. Intrathecal antisense for PKCε did not inhibit either ET-1 hyperalgesia or SIEH, suggesting no role for neuronal PKCε; however, administration of a PKCε inhibitor at the site of testing selectively attenuated SIEH. Compatible with endothelial cells releasing ATP in response to mechanical stimulation, P2X2/3 receptor antagonists eliminated SIEH. The endothelium also appears to contribute to hyperalgesia in two ergonomic pain models (eccentric exercise and hind limb vibration) and in model of endometriosis. We propose that SIEH is produced by an effect of ET-1 on vascular endothelial cells, sensitizing its release of ATP in response to mechanical stimulation; ATP in turn acts at the nociceptor P2X2/3 receptor. PMID:23407944

  5. Electronic structure and thermoelectric properties of (Mg2X)2 / (Mg2Y)2 (X, Y = Si, Ge, Sn) superlattices from first-principle calculations

    NASA Astrophysics Data System (ADS)

    Guo, San-Dong

    2016-05-01

    To identify thermoelectric materials containing abundant, low-cost and non-toxic elements, we have studied the electronic structures and thermoelectric properties of (Mg2X)2/ (Mg2Y)2 (X, Y = Si, Ge, Sn) superlattices with state-of-the-art first-principles calculations using a modified Becke and Johnson (mBJ) exchange potential. Our results show that (Mg2Ge)2/ (Mg2Sn)2 and (Mg2Si)2/ (Mg2Sn)2 are semi-metals using mBJ plus spin-orbit coupling (mBJ + SOC), while (Mg2Si)2/ (Mg2Ge)2 is predicted to be a direct-gap semiconductor with a mBJ gap value of 0.46 eV and mBJ + SOC gap value of 0.44 eV. Thermoelectric properties are predicted by through solving the Boltzmann transport equations within the constant scattering time approximation. It is found that (Mg2Si)2/ (Mg2Ge)2 has a larger Seebeck coefficient and power factor than (Mg2Ge)2/ (Mg2Sn)2 and (Mg2Si)2/ (Mg2Sn)2 for both p-type and n-type doping. The detrimental influence of SOC on the power factor of p-type (Mg2X)2/ (Mg2Y)2 (X, Y = Si, Ge, Sn) is analyzed as a function of the carrier concentration, but there is a negligible SOC effect for n-type. These results can be explained by the influence of SOC on their valence and conduction bands near the Fermi level.

  6. Crystal structure, phase transition and conductivity study of two new organic - inorganic hybrids: [(CH2)7(NH3)2]X2, X = Cl/Br

    NASA Astrophysics Data System (ADS)

    Mostafa, Mohga Farid; El-khiyami, Shimaa Said; Abd-Elal, Seham Kamal

    2017-01-01

    Two hybrids 1,7-heptanediammonium di-halide, [(C7H20N2]X2,X = Cl/Br crystallize in monoclinic P21/c, Z = 4. [(C7H20N2]Cl2: a = 4.7838 (2) Å, b = 16.9879 (8) Å, c = 13.9476 (8) Å, β = 97.773 (2)°, V = 1203.58(10) Å3, D = 1.137 g/cm3, λ = 0.71073 Å, R = 0.052 for 1055 reflections with I > 2σ(I), T = 298(2) K. [(C7H20N2]Br2: a = 4.7952 (10) Å, b = 16.9740 (5) Å, c = 13.9281 (5) Å, β = 97.793 (2)°, V = 1203.83(6) Å3, D = 1.612 g/cm3, λ = 0.71073 Å, R = 0.03 for 1959 reflections with I > 2σ(I) T = 298(2) K. Asymmetric unit cell of [(C7H20N2]X2,X = Cl/Br, each consist of one heptane-1,7-diammonium cation and two halide anions. The organic hydrocarbon layers pack in a stacked herring-bone manner, hydrogen bonded to the halide ions. Lattice potential energy is 1568.59 kJ/mol and 1560.78 kJ/mol, and cation molar volumes are 0.295 nm3 and 0.300 nm3 for chloride and bromide respectively. DTA confirmed chain melting transitions for both hybrids below T ∼ 340 K. Dielectric and ac conductivity measurements (290 < T K < 410; 0.080 < f kHz<100) indicated higher conductivity and activation energy of bromide for T > 340 K. Cross over from Jonscher's universal dielectric response at low temperatures T < 340 K to super-linear power law for T > 340 K is observed. At high temperatures halide ion hopping in accordance with the jump relaxation model prevails.

  7. Towards Mapping the Ocean Surface Topography at 1 km Resolution

    NASA Technical Reports Server (NTRS)

    Fu, Lee-Lueng; Rodriquez, Ernesto

    2006-01-01

    We propose to apply the technique of synthetic aperture radar interferometry to the measurement of ocean surface topography at spatial resolution approaching 1 km. The measurement will have wide ranging applications in oceanography, hydrology, and marine geophysics. The oceanographic and related societal applications are briefly discussed in the paper. To meet the requirements for oceanographic applications, the instrument must be flown in an orbit with proper sampling of ocean tides.

  8. KM3NeT

    SciTech Connect

    Jong, M. de; Collaboration: KM3NeT Collaboration

    2015-07-15

    KM3NeT is a large research infrastructure, that will consist of a network of deep-sea neutrino telescopes in the Mediterranean Sea. The main objective of KM3NeT is the discovery and subsequent observation of high-energy neutrino sources in the Universe. A further physics perspective is the measurement of the mass hierarchy of neutrinos. A corresponding study, ORCA, is ongoing within KM3NeT. A cost effective technology for (very) large water Cherenkov detectors has been developed based on a new generation of low price 3-inch photo-multiplier tubes. Following the successful deployment and operation of two prototypes, the construction of the KM3NeT research infrastructure has started. The prospects of the different phases of the implementation of KM3NeT are summarised.

  9. Planetary radar

    NASA Technical Reports Server (NTRS)

    Taylor, R. M.

    1980-01-01

    The radar astronomy activities supported by the Deep Space Network during June, July, and August 1980 are reported. The planetary bodies observed were Venus, Mercury, and the asteroid Toro. Data were obtained at both S and X band, and the observations were considered successful.

  10. Cluster perturbation theory in Hubbard model exactly taking into account the short-range magnetic order in 2 x 2 cluster

    SciTech Connect

    Nikolaev, S. V. Ovchinnikov, S. G.

    2010-10-15

    The cluster perturbation theory is presented in the 2D Hubbard model constructed using X operators in the Hubbard-I approximation. The short-range magnetic order is taken into account by dividing the entire lattice into individual 2 x 2 clusters and solving the eigenvalue problem in an individual cluster using exact diagonalization taking into account all excited levels. The case of half-filling taking into account jumps between nearest neighbors is considered. As a result of numerical solution, a shadow zone is discovered in the quasiparticle spectrum. It is also found that a gap in the density of states in the quasiparticle spectrum at zero temperature exists for indefinitely small values of Coulomb repulsion parameter U and increases with this parameter. It is found that the presence of this gap in the spectrum is due to the formation of a short-range antiferromagnetic order. An analysis of the temperature evolution of the density of states shows that the metal-insulator transition occurs continuously. The existence of two characteristic energy scales at finite temperatures is demonstrated, the larger scale is associated with the formation of a pseudogap in the vicinity of the Fermi level, and the smaller scale is associated with the metal-insulator transition temperature. A peak in the density of states at the Fermi level, which is predicted in the dynamic mean field theory in the vicinity of the metal-insulator transition, is not observed.

  11. Chemical pressure induced change in multiferroicity of Bi1+2xGd2x/2Fe1-2xO3 bulk ceramics

    NASA Astrophysics Data System (ADS)

    Pradhan, S. K.; Sahu, D. R.; Rout, P. P.; Das, S. K.; Pradhan, A. K.; Srinivasu, V. V.; Roul, B. K.

    2017-04-01

    We have optimized Gd ion substitution in BiFeO3 (BFO) and observed prominently change in structural, electrical and magnetic behavior of Bi1+2xGd2x/2Fe1-2xO3 ceramics synthesized through slow step sintering schedule. It is observed that with the increase in concentration of Gd (x=0.1), original structure of BFO is transformed from rhombohedral R3c space group to orthorhombic Pn21a space group. Surprisingly, unit cell volume is drastically contracted (35% for x=0.2) and the sintered specimen showed enhanced room temperature ferromagnetic behavior although the original BFO is normally G-type antiferromagnetic in nature at 643 K. It is expected that intrinsic chemical pressure within the bulk body built by the substitution of Gd in presence of excess bismuth greatly supported through unidirectional movement of electrical dipole moment with in each individual domain as a result of which suppression of leakage current with enhanced dielectric and ferroelectric hysteresis is observed.

  12. The Nicotinic α6 Subunit Gene Determines Variability in Chronic Pain Sensitivity via Cross-inhibition of P2X2/3 Receptors

    PubMed Central

    Wieskopf, Jeffrey S.; Mathur, Jayanti; Limapichat, Walrati; Post, Michael R.; Al-Qazzaz, Mona; Sorge, Robert E.; Martin, Loren J.; Zaykin, Dmitri V.; Smith, Shad B.; Freitas, Kelen; Austin, Jean-Sebastien; Dai, Feng; Zhang, Jie; Marcovitz, Jaclyn; Tuttle, Alexander H.; Slepian, Peter M.; Clarke, Sarah; Drenan, Ryan M.; Janes, Jeff; Sharari, Shakir Al; Segall, Samantha K.; Aasvang, Eske K.; Lai, Weike; Bittner, Reinhard; Richards, Christopher I.; Slade, Gary D.; Kehlet, Henrik; Walker, John; Maskos, Uwe; Changeux, Jean-Pierre; Devor, Marshall; Maixner, William; Diatchenko, Luda; Belfer, Inna; Dougherty, Dennis A.; Su, Andrew I.; Lummis, Sarah C.R.; Damaj, M. Imad; Lester, Henry A.; Patapoutian, Ardem; Mogil, Jeffrey S.

    2016-01-01

    Chronic pain is a highly prevalent and poorly managed human health problem. We used microarray-based expression genomics in 25 inbred mouse strains to identify dorsal root ganglion (DRG)-expressed genetic contributors to mechanical allodynia, a prominent symptom of chronic pain. We identified expression levels of Chrna6, which encodes the α6 subunit of the nicotinic acetylcholine receptor (nAChR), as highly associated with allodynia. We confirmed the importance of α6* (i.e., α6-containing) nAChRs by analyzing both gain- and loss-of-function mutants. We find that mechanical allodynia associated with neuropathic and inflammatory injuries is significantly altered in α6* mutants, and that α6* but not α4* nicotinic receptors are absolutely required for peripheral and/or spinal nicotine analgesia. Furthermore, we show that Chrna6’s role in analgesia is at least partially due to direct interaction and cross-inhibition of α6* nAChRs with P2X2/3 receptors in DRG nociceptors. Finally, we establish relevance of our results to humans by the observation of genetic association in patients suffering from chronic postsurgical pain and temporomandibular pain. PMID:25972004

  13. Anomalous local magnetism in the 4 f-localized ferromagnets CeRu2X2B (X = Al, Ga) revealed by using ZF-μSR

    NASA Astrophysics Data System (ADS)

    Lee, Wonjun; Choi, Kwang-Yong; Yoon, Sungwon; Suh, Byoung Jin; Jang, Zeehoon; Biswas, P. K.; Baumbach, Ryan E.; Bauer, Eric D.

    2016-05-01

    We report zero-field muon spin relaxation/rotation (ZF-μSR) measurements on the 4f-localized ferromagnets CeRu2X2B (X = Al, Ga) with Ising-type anisotropy. Our ZF-μSR spectra of CeRu2Ga2B with a Curie temperature at T C = 16.3 K show a well-defined muon procession at temperatures below T C . The extracted critical exponent of β = 0.533 is close to the mean-field value of β = 0.5. On the other hand, the isomorphic CeRu2Al2B exhibits an intriguing evolution of the ZF-μSR spectrum through a spin density wave/ferromagnetic transition at T C = 12.8 K with a subsequent magnetic anomaly at T* = 6 K. Strikingly, the muon frequency decreases upon cooling to temperatures below T C and can be no longer resolved at temperatures below T*. At the same time, the muon relaxation rate increases continuously at temperatures below T C . These give an indication of the development of an inhomogeneous and dynamic ferromagnetic state. The contrasting ferromagnetism between CeRu2Ga2B and CeRu2Al2B evidences that a certain type of intrinsic/extrinsic perturbation, for example, exchange frustration and defects/impurities, can exert a drastic impact on the local magnetic properties in a family of 4 f-localized magnetic materials with frustration.

  14. Confidence interval for rate ratio in a 2 x 2 table with structural zero: an application in assessing false-negative rate ratio when combining two diagnostic tests.

    PubMed

    Tang, Man-Lai; Tang, Nian-Sheng; Carey, Vincent J

    2004-06-01

    In this article, we consider problems with correlated data that can be summarized in a 2 x 2 table with structural zero in one of the off-diagonal cells. Data of this kind sometimes appear in infectious disease studies and two-step procedure studies. Lui (1998, Biometrics54, 706-711) considered confidence interval estimation of rate ratio based on Fieller-type, Wald-type, and logarithmic transformation statistics. We reexamine the same problem under the context of confidence interval construction on false-negative rate ratio in diagnostic performance when combining two diagnostic tests. We propose a score statistic for testing the null hypothesis of nonunity false-negative rate ratio. Score test-based confidence interval construction for false-negative rate ratio will also be discussed. Simulation studies are conducted to compare the performance of the new derived score test statistic and existing statistics for small to moderate sample sizes. In terms of confidence interval construction, our asymptotic score test-based confidence interval estimator possesses significantly shorter expected width with coverage probability being close to the anticipated confidence level. In terms of hypothesis testing, our asymptotic score test procedure has actual type I error rate close to the pre-assigned nominal level. We illustrate our methodologies with real examples from a clinical laboratory study and a cancer study.

  15. Adsorption site and structure determination of c(2x2) N{sub 2}/Ni(100) using angle-resolved photoemission extended fine structure

    SciTech Connect

    Moler, E.J.; Kellar, S.A.; Huff, W.R.A.

    1997-04-01

    The authors have determined the atomic spatial structure of c(2x2) N2Ni(100) with Angle-Resolved Photoemission Extended Fine Structure (ARPEFS) from the nitrogen 1s core level using monochromatized x-rays from beamline 6.1 at SSRL and beamline 9.3.2 at the ALS. The chemically shifted N 1s peak intensities were summed together to obtain ARPEFS curves for both nitrogen atoms in the molecule. They used a new, highly-optimized program based on the Rehr-Albers scattering matrix formalism to find the adsorption site and to quantitatively determine the bond-lengths. The nitrogen molecule stands upright at an atop site, with a N-Ni bond length of 2.25(1) {angstrom}, a N-N bond length of 1.10(7) {angstrom}, and a first layer Ni-Ni spacing of 1.76(4) {angstrom}. The shake-up peak shows an identical ARPEFS diffraction pattern, confirming its intrinsic nature and supporting a previous use of this feature to decompose the peak into contributions from the chemically inequivalent nitrogen atoms. Comparison to a previously published theoretical treatment of N-N-Ni and experimental structures of analogous adsorbate systems demonstrates the importance of adsorbate-adsorbate interactions in weakly chemisorbed systems.

  16. Crystal Structure of Pseudorhombohedral InFe 1- xTi xO 3+ x/2 ( x=2/3)

    NASA Astrophysics Data System (ADS)

    Michiue, Yuichi; Onoda, Mitsuko; Watanabe, Akiteru; Watanabe, Mamoru; Brown, Francisco; Kimizuka, Noboru

    2002-02-01

    The structure of pseudorhombohedral-type InFe1-xTixO3-x/2 (x=2/3) was refined by Rietveld profile fitting. The crystal is a commensurate member of a series in a solution range on InFeO3-In2Ti2O7 including incommensurate structures. The structure with the unit cell of a=5.9188(1), b=10.1112(2), and c=6.3896(1) Å, β=108.018(2)°, and a space group P21/a is the alternate stacking of an edge-shared InO6 octahedral layer and an Fe/Ti-O plane along c*. Metal sites on the Fe/Ti-O plane are surrounded by four oxygen atoms on the Fe/Ti-O plane and two axial ones. Electric conductivities of the order 10-4 S/cm were observed for the samples at 1000 K, while the oxide ion transport number is almost zero as no electromotive force was detected by an oxygen concentration cell.

  17. RADAR "SAIL" satellite concept

    NASA Astrophysics Data System (ADS)

    Aguttes, Jean Paul; Sombrin, Jacques; Conde, Eric

    1996-11-01

    The Radar SAIL concept is based on the use of a rectangular antenna lying in the dawn-dusk orbital plane with the length (along speed vector) smaller than the height. Such geometry makes it possible to place the solar cells on the back of the antenna, to use gravity gradient stabilisation, and to implement multipath-free GPS interferometric measurement of the antenna deformation thus allowing structural relaxation. Less obviously, the geometry favours the RADAR design too, by allowing grating lobes and therefore a lower density of built-in electronic in the active antenna. The antenna can be thin and packed for launch inside a cylinder-shaped bus having pyrotechnic doors for the antenna deployement and bearing the rest of the payload and the service equipment. With respect to a standard design of performant missions, cost savings come from the bus, whose functions (AOCS, power supply) are simplified, from the launch since the mass budget and the stowing configuration become compatible with medium size rockets (LLV2/3, DELTA-LITE, LM-4.), and from the active antenna built-in electronics. The RADAR SAIL concept is all the more cost effective when the mission requires a large, high and short antenna, i.e. high resolution (<5m), low frequency band (L or S or even P), high revisiting, multiple frequencies. Mission implementation and funding can be favored by the new capability to share the satellite between autonomous regional operators. Combined with ground DBF (digital beam forming) technique, the concept allows extremely simple and low cost missions providing a fixed wide swath (10 to 15 m resolution within 500km to 1000 km swath) for systematic surveillance or monitoring.

  18. Solar Radar Astronomy with LOFAR

    NASA Astrophysics Data System (ADS)

    Rodriguez, P.

    2003-04-01

    A new approach to the study of the Sun's corona and its dynamical processes is possible with radar investigations in the frequency range of about 10-50 MHz. The range of electron densities of the solar corona is such that radio waves at these frequencies can provide diagnostic radar echoes of large scale phenomena such as coronal mass ejections (CMEs). We expect that the frequency shift imposed on the echo signal by an earthward-moving CME will provide a direct measurement of the velocity, thereby providing a good estimate of the arrival time at Earth. It is known that CMEs are responsible for the largest geomagnetic storms at Earth, which are capable of causing power grid blackouts, satellite electronic upsets, and degradation of radio communications circuits. Thus, having accurate forecasts of potential CME-initiated geomagnetic storms is of practical space weather interest. New high power transmitting arrays are becoming available, along with proposed modifications to existing research facilities, that will allow the use of radio waves to study the solar corona by the radar echo technique. Of particular interest for such solar radar investigations is the bistatic configuration with the Low Frequency Array (LOFAR). The LOFAR facility will have an effective receiving area of about 1 square km at solar radar frequencies. Such large effective area will provide the receiving antenna gain needed for detailed investigations of solar coronal dynamics. Conservative estimates of the signal-to-noise ratio for solar radar echoes as a function of the integration time required to achieve a specified detection level (e.g., ~ 5 dB) indicate that time resolutions of 10s of seconds can be achieved. Thus, we are able to resolve variations in the solar radar cross section on time scales which will provide new information on the plasma dynamical processes associated with the solar corona, such as CMEs. It is the combination of high transmitted power and large effective receiving

  19. Knob manager (KM) operators guide

    SciTech Connect

    1993-10-08

    KM, Knob Manager, is a tool which enables the user to use the SUNDIALS knob box to adjust the settings of the control system. The followings are some features of KM: dynamic knob assignments with the user friendly interface; user-defined gain for individual knob; graphical displays for operating range and status of each process variable is assigned; backup and restore one or multiple process variable; save current settings to a file and recall the settings from that file in future.

  20. Radar observations of asteroid 1986 JK

    NASA Technical Reports Server (NTRS)

    Ostro, S. J.; Yeomans, D. K.; Chodas, P. W.; Goldstein, R. M.; Jurgens, R. F.; Thompson, T. W.

    1989-01-01

    The asteroid 1986 JK was observed with a 3.5 cm-wavelength radar in May and June, 1986, at less than 0.029 AU; its radar echo power circular polarization ratio indicates single backscattering from smooth surface elements. A working model constructed for the asteroid in light of these radar data postulates a 1-2 km object whose shape has little elongation and some polar flattening. Orbital and physical characteristics are rather cometlike. The radar astrometric data obtained are noted to be extremely powerful for orbit-improvement, so that a search ephemeris whose uncertainty is an order-of-magnitude smaller than that based on relevant optical data alone can be prepared by combining optical and radar data.

  1. Dual Frequency Radar Ice and Snow Signatures.

    DTIC Science & Technology

    1981-12-01

    slush covered. This condition was observed over the central portion of a 100 km long strip of radar imagery. Open water polynyas toward the ends of the...radar strip provided very low returns at both frequencies. Available coincident photography did not reveal any slush on these polynyas . Atmospheric...and L-band imagery in Figure 5. These icebergs, which are located in Melville Bay, were calved from local glaciers. This area is a major source of

  2. Radars in space

    NASA Technical Reports Server (NTRS)

    Delnore, Victor E.

    1990-01-01

    The capabilities of active microwave devices operating from space (typically, radar, scatterometers, interferometers, and altimeters) are discussed. General radar parameters and basic radar principles are explained. Applications of these parameters and principles are also explained. Trends in space radar technology, and where space radars and active microwave sensors in orbit are going are discussed.

  3. Radar Sounder

    DTIC Science & Technology

    1988-09-01

    over the shorter time period (resulting in a multilook SAR ) with the result that spatial resolution, the usual r~ason for using SAR techniques, degrades...Field - - - ALT 21. Sea Surface Topography - - - SAR , ALT 22. Ocean Waves (sea, swell, surf) V. Good Some V. Good SAR , ALT * with additional lower freq...OLS - Operational Line-scan System radiometer (4-6 GHz?) ALT - Altimeter •* good at low microwave SAR - Synthetic Aperture frequencies Radar + over

  4. Percolating hierarchical defect structures drive phase transformation in Ce1-x Gd x O2-x/2: a total scattering study.

    PubMed

    Scavini, Marco; Coduri, Mauro; Allieta, Mattia; Masala, Paolo; Cappelli, Serena; Oliva, Cesare; Brunelli, Michela; Orsini, Francesco; Ferrero, Claudio

    2015-09-01

    A new hierarchical approach is presented for elucidating the structural disorder in Ce1-x Gd x O2-x/2 solid solutions on different scale lengths. The primary goal of this investigation is to shed light on the relations between the short-range and the average structure of these materials via an analysis of disorder on the mesocopic scale. Real-space (pair distribution function) and reciprocal-space (Rietveld refinement and microstructure probing) analysis of X-ray powder diffraction data and electron spin resonance (ESR) investigations were carried out following this approach. On the local scale, Gd- and Ce-rich droplets (i.e. small regions a few ångströms wide) form, exhibiting either a distorted fluorite (CeO2) or a C-type (Gd2O3) structure in the whole compositional range. These droplets can then form C-type nanodomains which, for Gd concentrations x Gd ≤ 0.25, are embedded in the fluorite matrix. At the site percolation threshold p C for a cubic lattice (x Gd = p C ≃ 0.311), C-type nanodomains percolate inside each crystallite and a structural phase transformation is observed. When this occurs, the peak-to-peak ESR line width ΔH pp shows a step-like behaviour, which can be associated with the increase in Gd-Gd dipolar interactions. A general crystallographic rationale is presented to explain the fluorite-to-C-type phase transformation. The approach shown here could be adopted more generally in the analysis of disorder in other highly doped materials.

  5. Residual Chemoresponsiveness to Acids in the Superior Laryngeal Nerve in “Taste-Blind” (P2X2/P2X3 Double-KO) Mice

    PubMed Central

    Ohkuri, Tadahiro; Horio, Nao; Stratford, Jennifer M.; Finger, Thomas E.; Ninomiya, Yuzo

    2012-01-01

    Mice lacking both the P2X2 and the P2X3 purinergic receptors (P2X-dblKO) exhibit loss of responses to all taste qualities in the taste nerves innervating the tongue. Similarly, these mice exhibit a near total loss of taste-related behaviors in brief access tests except for a near-normal avoidance of acidic stimuli. This persistent avoidance of acids despite the loss of gustatory neural responses to sour was postulated to be due to continued responsiveness of the superior laryngeal (SL) nerve. However, chemoresponses of the larynx are attributable both to taste buds and to free nerve endings. In order to test whether the SL nerve of P2X-dblKO mice remains responsive to acids but not to other tastants, we recorded responses from the SL nerve in wild-type (WT) and P2X-dblKO mice. WT mice showed substantial SL responses to monosodium glutamate, sucrose, urea, and denatonium—all of which were essentially absent in P2X-dblKO animals. In contrast, the SL nerve of P2X-dblKO mice exhibited near-normal responses to citric acid (50 mM) although responsiveness of both the chorda tympani and the glossopharyngeal nerves to this stimulus were absent or greatly reduced. These results are consistent with the hypothesis that the residual avoidance of acidic solutions by P2X-dblKO mice may be attributable to the direct chemosensitivity of nerve fibers innervating the laryngeal epithelium and not to taste. PMID:22362867

  6. Simultaneous Observations of Cirrus Clouds with a Millimeter-Wave Radar and the MU Radar.

    NASA Astrophysics Data System (ADS)

    Wada, Eiko; Hashiguchi, Hiroyuki; Yamamoto, Masayuki K.; Teshiba, Michihiro; Fukao, Shoichiro

    2005-03-01

    Observations of frontal cirrus clouds were conducted with the scanning millimeter-wave radar at the Shigaraki Middle and Upper Atmosphere (MU) Radar Observatory in Shiga, Japan, during 30 September-13 October 2000. The three-dimensional background winds were also observed with the very high frequency (VHF) band MU radar. Comparing the observational results of the two radars, it was found that the cirrus clouds appeared coincident with the layers of the strong vertical shear of the horizontal winds, and they developed and became thicker under the condition of the strong vertical shear of the horizontal wind and updraft. The result of the radiosonde observation indicated that Kelvin-Helmholtz instability (KHI) occurred at 8-9-km altitudes because of the strong vertical shear of the horizontal wind. The warm and moist air existed above the 8.5-km altitude, and the cold and dry air existed below the 8.5-km altitude. As a result of the airmass mixing of air above and below the 8.5-km altitudes, the cirrus clouds were formed. The updraft, which existed at 8.5-12-km altitude, caused the development of the cirrus clouds with the thickness of >2 km. By using the scanning millimeter-wave radar, the three-dimensional structure of cell echoes formed by KHI for the first time were successfully observed.

  7. Advanced meteor radar installed at Tirupati: System details and comparison with different radars

    NASA Astrophysics Data System (ADS)

    Rao, S. Vijaya Bhaskara; Eswaraiah, S.; Venkat Ratnam, M.; Kosalendra, E.; Kishore Kumar, K.; Sathish Kumar, S.; Patil, P. T.; Gurubaran, S.

    2014-11-01

    An advanced meteor radar, viz, Sri Venkateswara University (SVU) meteor radar (SVU MR) operating at 35.25 MHz, was installed at Sri Venkateswara University (SVU), Tirupati (13.63°N, 79.4°E), India, in August 2013 for continuous observations of horizontal winds in the mesosphere and lower thermosphere (MLT). This manuscript describes the purpose of the meteor radar, system configuration, measurement techniques, its data products, and operating parameters, as well as a comparison of measured mean winds in the MLT with contemporary radars over the Indian region. It is installed close to the Gadanki (13.5°N, 79.2°E) mesosphere-stratosphere-troposphere (MST) radar to fill the region between 85 and 100 km where this radar does not measure winds. The present radar provides additional information due to its high meteor detection rate, which results in accurate wind information from 70 to 110 km. As a first step, we made a comparison of SVU MR-derived horizontal winds in the MLT region with those measured by similar and different (MST and MF radars) techniques over the Indian region, as well as model (horizontal wind model 2007) data sets. The comparison showed an exquisite agreement between the overlapping altitudes (82-98 km) of different radars. Zonal winds compared very well, as did the meridional winds. The observed discrepancies and limitations in the wind measurement are discussed in the light of different measuring techniques and the effects of small-scale processes like gravity waves. This new radar is expected to play an important role in our understanding of the vertical and lateral coupling of different regions of the atmosphere that will be possible when measurements from nearby locations are combined.

  8. HF Over-the-Horizon Radar System Performance Analysis

    DTIC Science & Technology

    2007-09-01

    3,500 km at cf = 14.5 MHz. A model of the maximum detection range for the Chinese FMCW OTH backscatter (OTH-B) radar was developed in MATLAB . An...calculation of the maximum usable frequency (MUF), and footprint prediction. Also, radar equation analysis was done in MATLAB to study the signal-to- noise...target detection technique and radar equations are applied. Chapter V uses PROPLAB model simulation to bring in the principle of raytracing and

  9. The crystal chemistry of Ca(10-y)(SiO4)3(SO4)3Cl(2-x-2y)F(x) ellestadite.

    PubMed

    Fang, Yanan; Ritter, Clemens; White, Tim

    2011-12-19

    Fluor-chlorellestadite solid solutions Ca(10)(SiO(4))(3)(SO(4))(3)Cl(2-x)F(x), serving as prototype crystalline matrices for the fixation of hazardous fly ash, were synthesized and characterized by powder X-ray and neutron diffraction (PXRD and PND), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR). The lattice parameters of the ellestadites vary linearly with composition and show the expected shrinkage of unit cell volume as fluorine (IR = 1.33 Å) displaces chlorine (IR = 1.81 Å). FTIR spectra indicate little or no OH(-) in the solid solutions. All compositions conform to P6(3)/m symmetry where F(-) is located at the 2a (0, 0, (1)/(4)) position, while Cl(-) is displaced out of the 6h Ca(2) triangle plane and occupies 4e (0, 0, z) split positions with z ranging from 0.336(3) to 0.4315(3). Si/S randomly occupy the 6h tetrahedral site. Ellestadites rich in Cl (x ≤ 1.2) show an overall deficiency in halogens (<2 atom per formula unit), particularly Cl as a result of CaCl(2) volatilization, with charge balance achieved by the creation of Ca vacancies (Ca(2+) + 2Cl(-) →□(Ca) + 2□(Cl)) leading to the formula Ca(10-y)(SiO(4))(3)(SO(4))(3)Cl(2-x-2y)F(x). For F-rich compositions the vacancies are found at Ca(2), while for Cl-rich ellestadites, vacancies are at Ca(1). It is likely the loss of CaCl(2) which leads tunnel anion vacancies promotes intertunnel positional disorder, preventing the formation of a P2(1)/b monoclinic dimorph, analogous to that reported for Ca(10)(PO(4))(6)Cl(2). Trends in structure with composition were analyzed using crystal-chemical parameters, whose systematic variations served to validate the quality of the Rietveld refinements.

  10. Wuhan Atmospheric Radio Exploration (WARE) radar: implementation and initial results

    NASA Astrophysics Data System (ADS)

    Zhou, C.; Qing, H.; Chen, G.; Gu, X.; Ni, B.; Yang, G.; Zhang, Y.; Zhao, Z.

    2014-11-01

    The recently constructed Wuhan Atmospheric Radio Exploration (WARE) radar is the first mesosphere-stratosphere-troposphere (MST) radar in the mainland of China, located at Chongyang, Hubei Province (114°8'8'' E, 29°31'58'' N, ∼ 23° geomagnetic latitude). WARE radar has a capability of probing the structure and dynamics of the atmosphere at the altitudes from 3 to 100 km (excluding 25-60 km). With fine temporal and spatial resolution, WARE radar provides an outstanding opportunity for the first time to extensively and intensively investigate various atmospheric phenomena at the regions of mid-latitude China. In this paper, we present the main configuration and technical specifications of WARE radar system. For the first time, we also report some initial results obtained by the WARE radar: (1) wind field observations from 69 to 85 km and from 3.2 to 16.9 km together with their comparisons with the rawinsonde results, (2) tropopause heights determined by radar echo power and comparisons between radar tropopause and rawinsonde tropopause, (3) atmospheric gravity waves in the troposphere with the wave length and propagation direction analyzed using the hodograph method, (4) aspect sensitivity of echo power at six specified heights in the troposphere and stratosphere, and (5) diurnal and semi-diurnal tides at the tropospheric and low stratospheric heights analyzed by the Lomb-Scargle periodogram method.

  11. Comet radar explorer

    NASA Astrophysics Data System (ADS)

    Farnham, Tony; Asphaug, Erik; Barucci, Antonella; Belton, Mike; Bockelee-Morvan, Dominique; Brownlee, Donald; Capria, Maria Teresa; Carter, Lynn; Chesley, Steve; Farnham, Tony; Gaskell, Robert; Gim, Young; Heggy, Essam; Herique, Alain; Klaasen, Ken; Kofman, Wlodek; Kreslavsky, Misha; Lisse, Casey; Orosei, Roberto; Plaut, Jeff; Scheeres, Dan

    will enjoy significant simplifying benefits compared to using the same instrument for Mars or lunar radar science: (1) The proximity of operations leads to a much higher signal to noise, as much as +30 dB. (2) The lack of an ionosphere simplifies data modeling and analysis. (3) The body is globally illuminated during every data acquisition, minimizing ambiguity or 'clutter' and allowing for tomographic reconstruction. What is novel is the data processing, where instead of a planar radargram approach we coherently process the data into an image of the deep interior. CORE thus uses a MARSIS-SHARAD heritage radar to make coherent reflection sounding measurements, a 'CAT SCAN' of a comet nucleus. What is unique about this mission compared to the Mars radars mentioned above, is that the target is a finite mass of dirty ice in free space, rather than a sheet of dirty ice draped on a planet surface. The depth of penetration (kilometers), attainable resolution (decameters), and the target materials, are more or less the same. This means that the science story is robust, and the radar implementation is robust. The target is comet 10P/Tempel 2, discovered by Wilhelm Tempel in 1873 and observed on most apparitions since. It has been extensively studied, in part because of interest as a CRAF target in the mid-1980s, and much is known about it. Tempel 2 is one of the largest known comet nuclei, 16×8×8 km (about the same size as Halley) [1] and has rotation period 8.9 hours [3,5,6,7,9]. The spin state is evolving with time, spinning up by ˜10 sec per perihelion pass [5,7]. The comet is active, but not exceedingly so, especially given its size. The water production is measured at ˜ 4 × 1028 mol/sec at its peak [2], a factor of 25 lower than comet Halley, and it is active over only ˜2% of its surface. The dust environment is well known, producing a factor of ˜100 less dust than Halley. Comet References: [1] A'Hearn et al., ApJ 347, 1155, 1989 [2] Feldman and Festou, ACM 1991, p

  12. The Goldstone Solar System Radar: 1988-2003 Earth-based Mars Radar Observations

    NASA Technical Reports Server (NTRS)

    Haldemann, A. F. C.; Jurgens, R. F.; Slade, M. A.; Larsen, K. W.

    2005-01-01

    The Goldstone Solar System Radar (GSSR) has successfully collected radar echo data from Mars over the past 30 years. The older data provided local elevation information for Mars, along with radar scattering information with global resolution. Since the upgrade to the 70-m DSN antenna at Goldstone completed in 1986, Mars data has been collected during all but the 1997 Mars opposition. Radar data, and non-imaging delay- Doppler data in particular, requires significant data processing to extract elevation, reflectivity and roughness of the reflecting surface. The spatial resolution of these experiments is typically some 10 km in longitude by some 150 km in latitude. The interpretation of these parameters while limited by the complexities of electromagnetic scattering, do provide information directly relevant to geophysical and geomorphic analyses of Mars.

  13. Sperm gamma-aminobutyric acid type A receptor delta subunit (GABRD) and its interaction with purinergic P2X2 receptors in progesterone-induced acrosome reaction and male fertility.

    PubMed

    Xu, Wenming; Wang, Ke; Chen, Yan; Liang, Xiao Tong; Yu, Mei Kuen; Yue, Huanxun; Tierney, M Louise

    2017-02-13

    The mechanism underlying the non-genomic action of progesterone in sperm functions and related Ca2+ mobilisation remains elusive. Herein we report the expression of gamma-aminobutyric acid type A receptor delta subunit (GABRD) in human and rodent sperm and its involvement in mediating the progesterone-induced acrosome reaction. GABRD was localised in the sperm head/neck region. A δ(392-422)-specific inhibitory peptide against GABRD blocked the progesterone-induced acrosome reaction and the associated increase in intracellular Ca2+. Similarly, an inhibitory effect against both progesterone-induced Ca2+ influx and the acrosome reaction was observed with a P2X2 receptor antagonist. The lack of synergism between the GABRD and P2X2 inhibitors suggests that these two receptors are playing a role in the same pathway. Furthermore, a co-immunoprecipitation experiment demonstrated that GABRD could undergo protein-protein interactions with the Ca2+-conducting P2X2 receptor. This interaction between the receptors could be reduced following progesterone (10μM) inducement. Significantly reduced GABRD expression was observed in spermatozoa from infertile patients with reduced acrosome reaction capacity, suggesting that normal expression of GABRD is critical for the sperm acrosome reaction and thus male fertility. The results of the present study indicate that GABRD represents a novel progesterone receptor or modulator in spermatozoa that is responsible for the progesterone-induced Ca2+ influx required for the acrosome reaction through its interaction with the P2X2 receptor.

  14. Prospective IS-MST radar. Potential and diagnostic capabilities

    NASA Astrophysics Data System (ADS)

    Potehin, Aleksandr; Medvedev, Andrey; Kushnarev, Dmitriy; Setov, Artyom; Lebedev, Valentin

    2016-09-01

    In the next few years, a new radar is planned to be built near Irkutsk. It should have capabilities of incoherent scatter (IS) radars and mesosphere-stratosphere-troposphere (MST) radars [Zherebtsov et al., 2011]. The IS-MST radar is a phased array of two separated antenna panels with a multichannel digital receiving system, which allows detailed space-time processing of backscattered signal. This paper describes characteristics, configuration, and capabilities of the antenna and transceiver systems of this radar. We estimate its potential in basic operating modes to study the ionosphere by the IS method at heights above 100 km and the atmosphere with the use of signals scattered from refractive index fluctuations, caused by turbulent mixing at heights below 100 km. The modeling shows that the radar will allow us to regularly measure neutral atmosphere parameters at heights up to 26 km as well as to observe mesosphere summer echoes at heights near 85 km in the presence of charged ice particles (an increase in Schmidt number) and mesosphere winter echoes at heights near 65 km with increasing background electron density. Evaluation of radar resources at the IS mode in two height ranges 100-600 and 600-2000 km demonstrates that in the daytime and with the accumulation time of 10 min, the upper boundaries of electron density and ionospheric plasma temperature are ~1500 and ~1300 km respectively, with the standard deviation of no more than 10 %. The upper boundary of plasma drift velocity is ~1100 km with the standard deviation of 45 m/s. The estimation of interferometric capabilities of the MST radar shows that it has a high sensitivity to objects of angular size near 7.5 arc min, and its potential accuracy in determining target angles can reach 40 arc sec.

  15. Detection of Marine Radar Targets

    NASA Astrophysics Data System (ADS)

    Briggs, John N.

    A radar must detect targets before it can display them. Yet manufacturers' data sheets rarely tell us what the products will detect at what range. Many of the bigger radars are Type Approved so we consult the relevant IMO performance standard A 477 (XII). Paraphrasing Section 3.1 of the draft forthcoming revision (NAV 41/6): under normal propagation conditions with the scanner at height of 15 m, in the absence of clutter, the radar is required to give clear indication of an object such as a navigational buoy having a radar cross section area (RCS) of 10 m2 at 2 n.m. and, as examples, coastlines whose ground rises to 60/6 m at ranges of 20/7 n.m., a ship of 5000 tons at any aspect at 7 n.m. and a small vessel 10 m long at 3 n.m.This helps, but suppose we must pick up a 5 m2 buoy at g km? What happens in clutter? Should we prefer S- or X-band? To answer such questions we use equations which define the performance of surveillance radars, but the textbooks and specialist papers containing them often generalize with aeronautical and defence topics, making life difficult for the nonspecialist.This paper attempts a concise and self-contained engineering account of all main factors affecting detection of passive and active targets on civil marine and vessel traffic service (VTS) radars. We develop a set of equations for X- and S-band (3 and 10 cm, centred on 9400 and 3000 MHz respectively), suited for spreadsheet calculation.Sufficient theory is sketched in to indicate where results should be valid. Some simplifications of conventional treatments have been identified.

  16. The HYDROS Radiometer/Radar Instrument

    NASA Technical Reports Server (NTRS)

    Spencer, Michael W.; Njoku, Eni; Entekhabi, Dara; Doiron, Terence; Piepmeier, Jeffrey; Girard, Ralph

    2004-01-01

    The science objectives of the HYDROS mission are to provide frequent, global measurements of surface soil moisture and surface freeze/thaw state. In order to adequately measure these geophysical quantities, the key instrument requirements were determined by the HYDROS science team to be: 1) Dual-polarization L-Band passive radiometer measurements at 40 km resolution, 2) Dual-polarization L-Band active radar measurements at 3 km resolution, and 3) A wide swath to insure global three day refresh time for these measurements (1000 km swath at the selected orbit altitude of 670 km). As a solution to this challenging set of instrument requirements, a relatively large, 6 meter, conically-scanning reflector antenna architecture was selected for the instrument design. The deployable mesh antenna is shared by both the radiometer and radar electronics by employing a single L-Band feed.

  17. Advanced Meteor radar at Tirupati: System details and first results

    NASA Astrophysics Data System (ADS)

    Sunkara, Eswaraiah; Gurubaran, Subramanian; Sundararaman, Sathishkumar; Venkat Ratnam, Madineni; Karanam, Kishore Kumar; Eethamakula, Kosalendra; Vijaya Bhaskara Rao, S.

    An advanced meteor radar viz., Enhanced Meteor Detection Radar (EMDR) operating at 35.25 MHz is installed at Sri Venkateswara University (SVU), Tirupati (13.63oN, 79.4oE), India, in the month of August 2013. Present communication describes the need for the meteor radar at present location, system description, its measurement techniques, its variables and comparison of measured mean winds with contemporary radars over the Indian region. The present radar site is selected to fill the blind region of Gadanki (13.5oN, 79.2oE) MST radar, which covers mesosphere and lower thermosphere (MLT) region (70-110 km). By modifying the receiving antenna structure and elements, this radar is capable of providing accurate wind information between 70 and 110 km unlike other similar radars. Height covering region is extended by increasing the meteor counting capacity by modifying the receiving antenna structure and elements and hence its wind estimation limits extended below and above of 80 and 100 km, respectively. In the present study, we also made comparison of horizontal winds in the MLT region with those measured by similar and different (MST and MF radars) techniques over the Indian region including the model (HWM 07) data sets. The comparison showed a very good agreement between the overlapping altitudes (82-98 km) of different radars. Zonal winds compared very well as that of meridional winds. The observed discrepancies and limitations in the wind measurement are discussed. This new radar is expected to play important role in understanding the vertical and lateral coupling by forming a unique local network.

  18. Radar and Lidar Radar DEM

    NASA Technical Reports Server (NTRS)

    Liskovich, Diana; Simard, Marc

    2011-01-01

    Using radar and lidar data, the aim is to improve 3D rendering of terrain, including digital elevation models (DEM) and estimates of vegetation height and biomass in a variety of forest types and terrains. The 3D mapping of vegetation structure and the analysis are useful to determine the role of forest in climate change (carbon cycle), in providing habitat and as a provider of socio-economic services. This in turn will lead to potential for development of more effective land-use management. The first part of the project was to characterize the Shuttle Radar Topography Mission DEM error with respect to ICESat/GLAS point estimates of elevation. We investigated potential trends with latitude, canopy height, signal to noise ratio (SNR), number of LiDAR waveform peaks, and maximum peak width. Scatter plots were produced for each variable and were fitted with 1st and 2nd degree polynomials. Higher order trends were visually inspected through filtering with a mean and median filter. We also assessed trends in the DEM error variance. Finally, a map showing how DEM error was geographically distributed globally was created.

  19. Artificial ionospheric mirrors for radar applications

    SciTech Connect

    Short, R.D.; Wallace, T.; Stewart, C.V.; Lallement, P.; Koert, P.

    1990-10-01

    Recognition of performance limitations associated with traditional skywave over-the-horizon (OTH) high frequency (HF) radars has led a number of investigators to propose the creation of an Artificial Ionospheric Mirror (AIM) in the upper atmosphere, in order to reflect ground-based radar signals for OTH surveillance. The AIM is produced by beaming sufficient electromagnetic Power to the lower ionosphere (around 70 km) to enhance the in situ ionization level to 107 108 electrons/cm3, thereby providing an ionized layer capable of reflecting radar frequencies of 5 - 90 MHz. This paper presents a baseline AIM system concept and an associated performance evaluation, based upon the relevant ionization and propagation physics and in the context of air surveillance for the cruise missile threat. Results of the subject study indicate that a system using this concept would both complement and enhance the performance of the existing skywave OTH radars.

  20. Condor equatorial electrojet campaign: Radar results

    SciTech Connect

    Kudeki, E.; Fejer, B.G.; Farley, D.T.; Hanuise, C.

    1987-12-01

    A review of the experimental and theoretical background to the Condor equatorial electrojet compaign is followed by the presentation and discussion of VHF radar interferometer and HF radar backscatter data taken concurrently with two rocket in situ experiments reported in companion papers (Pfaff et al., this issue (a, b). Both experiments were conducted in strongly driven periods with the on-line radar interferometer displaying signatures of what has been interpreted in earlier radar work (Kudeki et al., 1982) as kilometer scale gradient drift waves. Low-frequency density fluctuations detected by in situ rocket sensors confirm the earlier interpretation. VHF radar/rocket data comparisons also indicate the existence of a turbulent layer in the upper portion of the daytime electrojet at about 108 km altitude driven purely by the two-stream instability. Nonlinear mode coupling of linearly growing two-stream waves to linearly damped 3-m vertical modes could account for the radar echoes scattered from this layer, which showed no indication of large-scale gradient drift waves. Nonlinear mode coupling may therefore compete with the wave-induced anomalous diffusion mechanism proposed recently by Sudan (1983) for the saturation of directly excited two-stream waves. Nighttime radar data show a bifurcated layer with the two parts having comparable echo strength but oppositely directed zonal drift velocities. The lower layer shows narrow backscatter spectra; the upper layer is characterized by kilometer scale waves and vertically propagating type 1 waves.

  1. Applications of high-frequency radar

    NASA Astrophysics Data System (ADS)

    Headrick, J. M.; Thomason, J. F.

    1998-07-01

    Efforts to extend radar range by an order of magnitude with use of the ionosphere as a virtual mirror started after the end of World War II. A number of HF radar programs were pursued, with long-range nuclear burst and missile launch detection demonstrated by 1956. Successful east coast radar aircraft detect and track tests extending across the Atlantic were conducted by 1961. The major obstacles to success, the large target-to-clutter ratio and low signal-to-noise ratio, were overcome with matched filter Doppler processing. To search the areas that a 2000 nautical mile (3700 km) radar can reach, very complex and high dynamic range processing is required. The spectacular advances in digital processing technology have made truly wide-area surveillance possible. Use of the surface attached wave over the oceans can enable HF radar to obtain modest extension of range beyond the horizon. The decameter wavelengths used by both skywave and surface wave radars require large physical antenna apertures, but they have unique capabilities for air and surface targets, many of which are of resonant scattering dimensions. Resonant scattering from the ocean permits sea state and direction estimation. Military and commercial applications of HF radar are in their infancy.

  2. The laser radar above 30 kilometers

    NASA Technical Reports Server (NTRS)

    Clemesha, B. R.

    1969-01-01

    A short "state of the art' report on laser radar observations of the atmosphere at heights greater than 30 km is presented. Graphs of recent measurements of the Rayleigh backscattering function between 30 and 70 and above 50 kilometers are included.

  3. A SEASAT-A synthetic aperture imaging radar system

    NASA Technical Reports Server (NTRS)

    Jordan, R. L.; Rodgers, D. H.

    1975-01-01

    The SEASAT, a synthetic aperture imaging radar system is the first radar system of its kind designed for the study of ocean wave patterns from orbit. The basic requirement of this system is to generate continuous radar imagery with a 100 km swath with 25m resolution from an orbital altitude of 800 km. These requirements impose unique system design problems. The end to end data system described including interactions of the spacecraft, antenna, sensor, telemetry link, and data processor. The synthetic aperture radar system generates a large quantity of data requiring the use of an analog link with stable local oscillator encoding. The problems associated in telemetering the radar information with sufficient fidelity to synthesize an image on the ground is described as well as the selected solutions to the problems.

  4. A Digital Elevation Model of the Greenland Ice Sheet based on Envisat and CryoSat-2 Radar Altimetry

    NASA Astrophysics Data System (ADS)

    Levinsen, J. F.; Smith, B. E.; Sandberg Sørensen, L.; Khvorostovsky, K.; Forsberg, R.

    2014-12-01

    With the launch of the first radar altimeter by ESA in 1992, more than two decades of radar altimetry data are now available. Therefore, one goal of ESA's Ice Sheet Climate Change Initiative is the estimation of surface elevation changes of the Greenland Ice Sheet (GrIS) based on ERS-1, -2, Envisat, CryoSat-2, and, in the longer term, Sentinel-3 data. This will create a data record from 1992 until present date. In addition to elevation-change records, such data can be processed to produce digital elevation models, or DEMs, of the ice sheets. The DEMs can be used to correct radar altimetry data for slope-induced errors resulting from the large footprint (e.g. 2-10 km for Envisat vs. 60 m for ICESat laser altimetry) or to correct for the underlying surface topography when applying the repeat-track method. DEMs also provide key information in e.g. SAR remote sensing of ice velocities to remove the interferograms' topographic signal or in regional climate modeling. This work focuses on the development of a GrIS DEM from Envisat and CryoSat-2 altimetry, corrected with temporally and spatially coincident NASA ICESat, ATM, and LVIS laser data. The spatial resolution is 2 x 2 km and the reference year 2010. It is based on 2009 and 2010 data, the 2009 data adjusted to 2010 by accounting for the intermediate elevation changes. This increases the spatial data coverage and reduces data errors. The GIMP DEM has been corrected for negative elevations and errors in the north, and used to constrain the final DEM. The recently acquired observations and increased data coverage give a strong advantage to this DEM relative to previous models, based on lower-resolution, more temporally scattered data (e.g. a decade of observations or only ICESat data, limited to three annual 35-day acquisition periods). Furthermore, as surface changes occur continuously, an up-to-date DEM is necessary to correctly constrain the observations, thereby ensuring an accurate change detection or modeling

  5. Capabilities and limitations of the Jicamarca radar as an MST radar

    NASA Technical Reports Server (NTRS)

    Woodman, R. F.; Farley, D. T.

    1983-01-01

    The Jicamarca radar (Long. 76.52W, Lat. 11.56S), located at 20 km from Lima at approximately 500 meters over sea level, is surrounded by mountains which provide a good shield from man-made interference. The radio horizon goes from a few hundred meters, across the dry valley where it is located, to 15 km, along the valley in the direction of the continental divide. This limits the clutter to 15 km, except for one high peak at 21 km. It is the most equatorial of all existing MST radars. Its proximity to the Andes, makes its location unique for the study of lee waves and orographic-induced turbulence. Vertical as well as horizontal projections of MST velocities are obtained by simultaneously pointing with different sections of the antenna into three or four different directions. The transmitters, receivers, and systems for data acquisition, processing, and control are included.

  6. Space Radar Image of Weddell Sea

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Two radar images are shown in this composite to compare the size of a standard spaceborne radar image (small inset) to the image that is created when the radar instrument is used in the ScanSAR mode (large image). The predominant image shows two large ocean circulation features, called eddies, at the northernmost edge of the sea ice pack in the Weddell Sea, off Antarctica. The eddy processes in this region play an important role in the circulation of the global ocean and the transportation of heat toward the pole. The large image is the first wide-swath, multi-frequency, multi-polarization radar image ever processed. To date, no other spaceborne radar sensors have obtained swaths exceeding 100 kilometers (62 miles) in width. This developmental image was produced at NASA's Jet Propulsion Laboratory by the Alaska SAR Facility's ScanSAR processor system, using radar data obtained on October 5, 1994, during the second flight of the Spaceborne Imaging Radar C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) onboard the space shuttle Endeavour. The image is oriented approximately east-west, with a center location of around 56.6 degrees south latitude and 6.5 degrees west longitude. Image dimensions are 240 km by 350 km (149 miles by 218 miles). The smaller image inset (upper right edge) was obtained by SIR-C/X-SAR on October 6, 1994, and covers a portion of the same ice features that are shown in the large image. The inset image dimensions are 18 km by 50 km (11 miles by 31 miles). The ocean eddies have a clockwise (or cyclonic) rotation and are roughly 40 km to 60 km (25 miles to 37 miles) in diameter. The dark areas are new ice and the lighter green areas are small sea-ice floes that are swept along by surface currents; both of these areas are shown within the eddies and to the south of the eddies. First year seasonal ice, typically 0.5 meter to 0.8 meter (1.5 feet to 2.5 feet) thick, is shown in the darker green area in the lower right corner. The open ocean to the north

  7. Weather Radar Technology Development

    DTIC Science & Technology

    1990-08-15

    uelocitV WMs ) data processing systems such as NEXRAD to have a reliable technique for removing ambiguities due to velocity aliasing. Performance of many...intended for automated implementation on radar systems such as the NEXt generation weather RADar ( NEXRAD ) system. Several research areas were addressed...with Doppler radar will soon be realized with the deployment of the NEXRAD radar systems. Some of these large scale storms can have devastating wind

  8. Radar: Human Safety Net

    ERIC Educational Resources Information Center

    Ritz, John M.

    2016-01-01

    Radar is a technology that can be used to detect distant objects not visible to the human eye. A predecessor of radar, called the telemobiloscope, was first used to detect ships in the fog in 1904 off the German coast. Many scientists have worked on the development and refinement of radar (Hertz with electromagnetic waves; Popov with determining…

  9. A new approach to lightweight radar altimeters

    NASA Technical Reports Server (NTRS)

    Levanon, N.; Stremler, F. G.; Suomi, V. E.

    1974-01-01

    Test results and key principles are given for a radar altimeter designed for meteorological balloons. The instrument, which weighs 160 g and consumes 0.7 W, will fill a gap in meteorological sensing using balloons - an area where pressure altitude was formerly the prevailing reference. The instrument is basically a delay-lock radar utilizing a superregenerative RF stage. Long-term absolute accuracy of plus or minus 10 m and short-term stability of better than 2 m rms were measured at altitudes of 20 km.

  10. Venus: Global radar properties in a geological context

    NASA Technical Reports Server (NTRS)

    Garvin, J. B.

    1984-01-01

    The radar altimetry, roughness (RMS slopes), and reflectivity data acquired for Venus represent the only global radar information available for any of the planets. In addition, the Pioneer Venus radar instrument was able to sound the surface at normal incidence so that it was possible to accurately measure the small-scale surface slopes and reflectivity (dielectric and porosity properties) at the same time as the surface elevation. Analyses of the topography of Venus demonstrate that it differs in its distribution from the Moon, Mars, or the Earth. While the range of topography extends from -2.5 km below the reference level to 11.5 km above, most of Venus falls within 1 km of the mean elevation, this is in sharp contrast to the Earth. The narrow, unimodal nature of the distribution of topography on Venus evidently exerts control on the other radar-derived properties of the surface. When clustering analysis techniques are applied to the Venus radar data sets, the result demonstrates that topographic zones serve as the best criteria for distinguishing regions on Venus which have related radar properties. The individual radar data sets are investigated separately and in conjunction with topography.

  11. A radar image of Venus.

    NASA Technical Reports Server (NTRS)

    Goldstein, R. M.; Rumsey, H. C.

    1972-01-01

    Radar scans of Venus have yielded a brightness map of a large portion of the surface. The bright area in the south (alpha) and the twin such areas in the north (beta and delta) were first discovered by spectral analysis of radar echos. When range-gating is also applied, their shapes are revealed, and they are seen to be roundish and about 1000 km across. Although radar brightness can be the result of either intrinsic reflectivity or surface roughness, polarization studies show these features to be rough (to the scale of the wavelength, 12.5 cm). Dark, circular areas can also be seen, many with bright central spots. The dark areas are probably smooth. The blurring of the equatorial strip is an artifact of the range-Doppler geometry; all resolution disappears at the equator. Another artifact of the method is the 'ghost', in the south, of the images of beta and delta. Such ghosts appear only at the eastern and western extremes of the map.

  12. The Southern Argentine Agile Meteor Radar (SAAMER)

    NASA Astrophysics Data System (ADS)

    Janches, Diego

    2014-11-01

    The Southern Argentina Agile Meteor Radar (SAAMER) is a new generation system deployed in Rio Grande, Tierra del Fuego, Argentina (53 S) in May 2008. SAAMER transmits 10 times more power than regular meteor radars, and uses a newly developed transmitting array, which focuses power upward instead of the traditional single-antenna-all-sky configuration. The system is configured such that the transmitter array can also be utilized as a receiver. The new design greatly increases the sensitivity of the radar enabling the detection of large number of particles at low zenith angles. The more concentrated transmitted power enables additional meteor studies besides those typical of these systems based on the detection of specular reflections, such as routine detections of head echoes and non-specular trails, previously only possible with High Power and Large Aperture radars. In August 2010, SAAMER was upgraded to a system capable to determine meteoroid orbital parameters. This was achieved by adding two remote receiving stations approximately 10 km away from the main site in near perpendicular directions. The upgrade significantly expands the science that is achieved with this new radar enabling us to study the orbital properties of the interplanetary dust environment. Because of the unique geographical location, SAAMER allows for additional inter-hemispheric comparison with measurements from Canadian Meteor Orbit Radar, which is geographically conjugate. Initial surveys show, for example, that SAAMER observes a very strong contribution of the South Toroidal Sporadic meteor source, of which limited observational data is available. In addition, SAAMER offers similar unique capabilities for meteor showers and streams studies given the range of ecliptic latitudes that the system enables detailed study of showers at high southern latitudes (e.g July Phoenicids or Puppids complex). Finally, SAAMER is ideal for the deployment of complementary instrumentation in both, permanent

  13. The Comet Radar Explorer Mission

    NASA Astrophysics Data System (ADS)

    Asphaug, Erik; Belton, Mike; Bockelee-Morvan, Dominique; Chesley, Steve; Delbo, Marco; Farnham, Tony; Gim, Yonggyu; Grimm, Robert; Herique, Alain; Kofman, Wlodek; Oberst, Juergen; Orosei, Roberto; Piqueux, Sylvain; Plaut, Jeff; Robinson, Mark; Sava, Paul; Heggy, Essam; Kurth, William; Scheeres, Dan; Denevi, Brett; Turtle, Elizabeth; Weissman, Paul

    2014-11-01

    Missions to cometary nuclei have revealed major geological surprises: (1) Global scale layers - do these persist through to the interior? Are they a record of primary accretion? (2) Smooth regions - are they landslides originating on the surface? Are they cryovolcanic? (3) Pits - are they impact craters or sublimation pits, or rooted in the interior? Unambiguous answers to these and other questions can be obtained by high definition 3D radar reflection imaging (RRI) of internal structure. RRI can answer many of the great unknowns in planetary science: How do primitive bodies accrete? Are cometary nuclei mostly ice? What drives their spectacular activity and evolution? The Comet Radar Explorer (CORE) mission will image the detailed internal structure of the nucleus of 10P/Tempel 2. This ~16 x 8 x 7 km Jupiter Family Comet (JFC), or its parent body, originated in the outer planets region possibly millions of years before planet formation. CORE arrives post-perihelion and observes the comet’s waning activity from safe distance. Once the nucleus is largely dormant, the spacecraft enters a ~20-km dedicated Radar Mapping Orbit (RMO). The exacting design of the RRI experiment and the precise navigation of RMO will achieve a highly focused 3D radar reflection image of internal structure, to tens of meters resolution, and tomographic images of velocity and attenuation to hundreds of meters resolution, tied to the gravity model and shape. Visible imagers will produce maps of the surface morphology, albedo, color, texture, and photometric response, and images for navigation and shape determination. The cameras will also monitor the structure and dynamics of the coma, and its dusty jets, allowing their correlation in 3D with deep interior structures and surface features. Repeated global high-resolution thermal images will probe the near-surface layers heated by the Sun. Derived maps of thermal inertia will be correlated with the radar boundary response, and photometry and

  14. Radar ranging to Ganymede and Callisto

    NASA Astrophysics Data System (ADS)

    Harmon, J. K.; Ostro, S. J.; Chandler, J. F.; Hudson, R. S.

    1994-03-01

    Arecibo observations from 1992 February to March have yielded the first successful radar range measurements to the Galilean satellites. Round-up time delays were measured for Ganymede and Callisto with accuracies of 20 to 50 micrometer (3 to 7 km) and 90 micrometer (14 km), respectively. Both satellites showed round-trip delay residuals (relative to the E-3 ephemeris) of about a millisecond, most of which can be attributed to errors in the predicted along-track positions (orbital phases). Using a simple model that assumed that all of the ephemeris error was due to constant orbital phase and Jupiter range errors we estimate that Ganymede was leading its ephemeris by 122 +/- 4 km, Callisto was lagging its ephemeris by 307 +/- 14 km, and Jupiter was 11 +/- 4 km more distant than predicted by the PEP740 planetary ephemeris.

  15. Radar stage uncertainty

    USGS Publications Warehouse

    Fulford, J.M.; Davies, W.J.

    2005-01-01

    The U.S. Geological Survey is investigating the performance of radars used for stage (or water-level) measurement. This paper presents a comparison of estimated uncertainties and data for radar water-level measurements with float, bubbler, and wire weight water-level measurements. The radar sensor was also temperature-tested in a laboratory. The uncertainty estimates indicate that radar measurements are more accurate than uncorrected pressure sensors at higher water stages, but are less accurate than pressure sensors at low stages. Field data at two sites indicate that radar sensors may have a small negative bias. Comparison of field radar measurements with wire weight measurements found that the radar tends to measure slightly lower values as stage increases. Copyright ASCE 2005.

  16. 2. VIEW SOUTHWEST, prime search radar tower, height finder radar ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. VIEW SOUTHWEST, prime search radar tower, height finder radar towards, height finder radar towers, and radar tower (unknown function) - Fort Custer Military Reservation, P-67 Radar Station, .25 mile north of Dickman Road, east of Clark Road, Battle Creek, Calhoun County, MI

  17. Alpine radar conversion for LAWR

    NASA Astrophysics Data System (ADS)

    Savina, M.; Burlando, P.

    2012-04-01

    The Local Area Weather Radar (LAWR) is a ship-born weather radar system operating in X-band developed by the DHI Group to detect precipitation in urban areas. To date more than thirty units are installed in different settings around the world. A LAWR was also deployed in the Alps, at 3883 m a.s.l. on the Kl. Matterhorn (Valais, Switzerland). This was the highest LAWR of the world and it led to the development of an Alpine LAWR system that, besides featuring important technological improvements needed to withstand the severe Alpine conditions, required the development of a new Alpine Radar COnversion Model (ARCOM), which is the main focus of this contribution. The LAWR system is equipped with the original FURUNO fan-beam slotted antenna and the original logarithmic receiver, which limits the radar observations to the video signal (L) withour providing the reflectivity (Z). The beam is 0.95 deg wide and 20 deg high. It can detect precipitation to a max range of 60 km. In order to account for the limited availability of raw signal and information and the specific mountain set-up, the conversion model had to be developed differently from the state-of-the-art radar conversion technique used for this class of radars. In particular, the ARCOM is based on a model used to simulate a spatial dependent factor, hereafter called ACF, which is in turn function of parameters that take in account climatological conditions, also used in other conversion methods, but additionally accounting for local radar beam features and for orographic forcings such as the effective sampling power (sP), which is modelled by means of antenna pattern, geometric ground clutter and their interaction. The result is a conversion factor formulated to account for a range correction that is based on the increase of the sampling volume, partial beam blocking and local climatological conditions. The importance of the latter in this study is double with respect to the standard conversion technique for this

  18. Space Radar Image of Boston, Massachusetts

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This radar image of the area surrounding Boston, Mass., shows how a spaceborne radar system distinguishes between densely populated urban areas and nearby areas that are relatively unsettled. The bright white area at the right center of the image is downtown Boston. The wide river below and to the left of the city is the Charles River in Boston's Back Bay neighborhood. The dark green patch to the right of the Back Bay is Boston Common. A bridge across the north end of Back Bay connects the cities of Boston and Cambridge. The light green areas that dominate most of the image are the suburban communities surrounding Boston. The many ponds that dot the region appear as dark irregular spots. Many densely populated urban areas show up as red in the image due to the alignment of streets and buildings to the incoming radar beam. North is toward the upper left. The image was acquired on October 9, 1994, by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) as it flew aboard the space shuttle Endeavour. This area is centered at 42.4 degrees north latitude, 71.2 degrees west longitude. The area shown is approximately 37 km by 18 km (23 miles by 11 miles). Colors are assigned to different radar frequencies and polarizations as follows: red is L-band horizontally transmitted, horizontally received; green is L-band horizontally transmitted, vertically received; blue is C-band horizontally transmitted, vertically received. SIR-C/X-SAR, a cooperative mission of the German, Italian and United States space agencies, is part of NASA's Mission to Planet Earth program.

  19. Space Radar Image of Saline Valley, California

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This is a three-dimensional perspective view of Saline Valley, about 30 km (19 miles) east of the town of Independence, California created by combining two spaceborne radar images using a technique known as interferometry. Visualizations like this one are helpful to scientists because they clarify the relationships of the different types of surfaces detected by the radar and the shapes of the topographic features such as mountains and valleys. The view is looking southwest across Saline Valley. The high peaks in the background are the Inyo Mountains, which rise more than 3,000 meters (10,000 feet) above the valley floor. The dark blue patch near the center of the image is an area of sand dunes. The brighter patches to the left of the dunes are the dry, salty lake beds of Saline Valley. The brown and orange areas are deposits of boulders, gravel and sand known as alluvial fans. The image was constructed by overlaying a color composite radar image on top of a digital elevation map. The radar image was taken by the Spaceborne Imaging Radar-C/X-bandSynthetic Aperture Radar (SIR-C/X-SAR) on board the space shuttleEndeavour in October 1994. The digital elevation map was producedusing radar interferometry, a process in which radar data are acquired on different passes of the space shuttle. The two data passes are compared to obtain elevation information. The elevation data were derived from a 1,500-km-long (930-mile) digital topographic map processed at JPL. Radar image data are draped over the topography to provide the color with the following assignments: red is L-band vertically transmitted, vertically received; green is C-band vertically transmitted, vetically received; and blue is the ratio of C-band vertically transmitted, vertically received to L-band vertically transmitted, vertically received. This image is centered near 36.8 degrees north latitude and 117.7 degrees west longitude. No vertical exaggeration factor has been applied to the data. SIR-C/X-SAR, a joint

  20. Synthetic aperture radar interferometry of Okmok volcano, Alaska: radar observations

    USGS Publications Warehouse

    Lu, Zhong; Mann, Dörte; Freymueller, Jeffrey T.; Meyer, David

    2000-01-01

    ERS-1/ERS-2 synthetic aperture radar interferometry was used to study the 1997 eruption of Okmok volcano in Alaska. First, we derived an accurate digital elevation model (DEM) using a tandem ERS-1/ERS-2 image pair and the preexisting DEM. Second, by studying changes in interferometric coherence we found that the newly erupted lava lost radar coherence for 5-17 months after the eruption. This suggests changes in the surface backscattering characteristics and was probably related to cooling and compaction processes. Third, the atmospheric delay anomalies in the deformation interferograms were quantitatively assessed. Atmospheric delay anomalies in some of the interferograms were significant and consistently smaller than one to two fringes in magnitude. For this reason, repeat observations are important to confidently interpret small geophysical signals related to volcanic activities. Finally, using two-pass differential interferometry, we analyzed the preemptive inflation, coeruptive deflation, and posteruptive inflation and confirmed the observations using independent image pairs. We observed more than 140 cm of subsidence associated with the 1997 eruption. This subsidence occurred between 16 months before the eruption and 5 months after the eruption, was preceded by ∼18 cm of uplift between 1992 and 1995 centered in the same location, and was followed by ∼10 cm of uplift between September 1997 and 1998. The best fitting model suggests the magma reservoir resided at 2.7 km depth beneath the center of the caldera, which was ∼5 km from the eruptive vent. We estimated the volume of the erupted material to be 0.055 km3 and the average thickness of the erupted lava to be ∼7.4 m. Copyright 2000 by the American Geophysical Union.

  1. Space Radar Image of Pishan, China

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This radar image is centered near the small town of Pishan in northwest China, about 280 km (174 miles) southeast of the city of Kashgar along the ancient Silk Route in the Taklamakan desert of the Xinjiang Province. Geologists are using this radar image as a map to study past climate changes and tectonics of the area. The irregular lavender branching patterns in the center of the image are the remains of ancient alluvial fans, gravel deposits that have accumulated at the base of the mountains during times of wetter climate. The subtle striped pattern cutting across the ancient fans are caused by thrusting of the Kun Lun Mountains north. This motion is caused by the continuing plate-tectonic collision of India with Asia. Modern fans show up as large lavender triangles above the ancient fan deposits. Yellow areas on the modern fans are vegetated oases. The gridded pattern results from the alignment of poplar trees that have been planted as wind breaks. The reservoir at the top of the image is part of a sophisticated irrigation system that supplies water to the oases. This image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour in April 1994. This image is centered at 37.4 degrees north latitude, 78.3 degrees east longitude and shows an area approximately 50 km by 100 km (31 miles by 62 miles). The colors are assigned to different frequencies and polarizations of the radar as follows: Red is L-band horizontally transmitted, horizontally received; green is L-band horizontally transmitted, vertically received; and blue is C-band horizontally transmitted and vertically received. SIR-C/X-SAR, a joint mission of the German, Italian, and the United States space agencies, is part of NASA's Mission to Planet Earth.

  2. Space Radar Image of Reunion Island

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This radar image shows the volcanic island of Reunion, about 700 km (434 miles) east of Madagascar in the southwest Indian Ocean. The southern half of the island is dominated by the active volcano, Piton de la Fournaise. This is one of the world's most active volcanoes, with more than 100 eruptions in the last 300 years. The most recent activity occurred in the vicinity of Dolomieu Crater, shown in the lower center of the image within a horseshoe-shaped collapse zone. Recent lava flows appear in shades of red, purple and orange. Light green areas are heavily vegetated forest, while much of the purple area near the coast is farmland. The radar illumination is from the left side of the image and dramatically emphasizes the precipitous cliffs at the edges of the central canyons of the island. These canyons are remnants from the collapse of formerly active parts of the volcanoes that built the island. This image was acquired by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on October 5, 1994. The image is centered at 21.2 degrees south latitude, 55.6 degrees east longitude. The area shown is approximately 50 km by 80 km (31 miles by 50 miles). North is toward the upper right. Colors are assigned to different frequencies and polarizations of the radar as follows: red is L-band horizontally transmitted, vertically received; green is L-band horizontally transmitted, vertically received; and blue is C-band horizontally transmitted, vertically received. SIR-C/X-SAR, a joint mission of the German, Italian and United States space agencies, is part of NASA's Mission to Planet Earth.

  3. W-band ARM Cloud Radar (WACR) Handbook

    SciTech Connect

    Widener, KB; Johnson, K

    2005-01-05

    The W-band Atmospheric Radiation Measurement (ARM) Program Cloud Radar (WACR) systems are zenith pointing Doppler radars that probe the extent and composition of clouds at 95.04 GHz. The main purpose of this radar is to determine cloud boundaries (e.g., cloud bottoms and tops). This radar reports estimates for the first three spectra moments for each range gate up to 15 km. The 0th moment is reflectivity, the 1st moment is radial velocity, and the 2nd moment is spectral width. Also available are the raw spectra files. Unlike the millimeter wavelength cloud radar (MMCR), the WACR does not use pulse coding and operates in only copolarization and cross-polarization modes.

  4. Low-Altitude Wind Shear Detection With Doppler Radar

    DTIC Science & Technology

    1987-02-01

    feasibility of using the next generation weather radar ( NEXRAD ) sys- tem to detect low-altitude horizontal wind shear near airports is investi- gated. We...requires that NEXRAD radar coverage havd’> lowest scan of 60 m above the surface in the airport area (within 20 km of the,,airport); the strongest...Availability Codes * Avail ~id/or Di’.t Special LIST OF FIGURES Figure 1. FAA requirements of altitude limits of NEXRAD coverage and resolu- tion in

  5. A simulation study of the effects of land cover and crop type on sensing soil moisture with an orbital C-band radar

    NASA Technical Reports Server (NTRS)

    Dobson, M. C.; Ulaby, F. T.; Moezzi, S.; Roth, E.

    1983-01-01

    Simulated C-band radar imagery for a 124-km by 108-km test site in eastern Kansas is used to classify soil moisture. Simulated radar resolutions are 100 m by 100 m, 1 km by 1 km, and 3 km by 3 km, and each is processed using more than 23 independent samples. Moisture classification errors are examined as a function of land-cover distribution, field-size distribution, and local topographic relief for the full test site and also for subregions of cropland, urban areas, woodland, and pasture/rangeland. Results show that a radar resolution of 100 m by 100 m yields the most robust classification accuracies.

  6. Probabilistic forecasts based on radar rainfall uncertainty

    NASA Astrophysics Data System (ADS)

    Liguori, S.; Rico-Ramirez, M. A.

    2012-04-01

    gauges location, and then interpolated back onto the radar domain, in order to obtain probabilistic radar rainfall fields in real time. The deterministic nowcasting model integrated in the STEPS system [7-8] has been used for the purpose of propagating the uncertainty and assessing the benefit of implementing the radar ensemble generator for probabilistic rainfall forecasts and ultimately sewer flow predictions. For this purpose, events representative of different types of precipitation (i.e. stratiform/convective) and significant at the urban catchment scale (i.e. in terms of sewer overflow within the urban drainage system) have been selected. As high spatial/temporal resolution is required to the forecasts for their use in urban areas [9-11], the probabilistic nowcasts have been set up to be produced at 1 km resolution and 5 min intervals. The forecasting chain is completed by a hydrodynamic model of the urban drainage network. The aim of this work is to discuss the implementation of this probabilistic system, which takes into account the radar error to characterize the forecast uncertainty, with consequent potential benefits in the management of urban systems. It will also allow a comparison with previous findings related to the analysis of different approaches to uncertainty estimation and quantification in terms of rainfall [12] and flows at the urban scale [13]. Acknowledgements The authors would like to acknowledge the BADC, the UK Met Office and Dr. Alan Seed from the Australian Bureau of Meteorology for providing the radar data and the nowcasting model. The authors acknowledge the support from the Engineering and Physical Sciences Research Council (EPSRC) via grant EP/I012222/1.

  7. Unexpected characteristics of the 150 km echoes observed over Gadanki and their implications

    NASA Astrophysics Data System (ADS)

    Patra, A. K.; Pavan Chaitanya, P.

    2016-11-01

    Recent discovery of two distinct types of 150 km echoes, namely, type-A and type-B, and subsequent progress in the large-scale kinetic simulation of photoelectron-induced plasma waves have begun a new era in resolving the five decades long 150 km echoing riddle. In this paper, we present hitherto unrevealed three important and unexpected findings on the two distinct types of 150 km echoes based on Gadanki radar observations. Our observations show unexpected predominance of type-A echoes, strong seasonal dependence of both type-A and type-B echoes, and a surprising connection of the type-B echoes to the unusually deep solar minimum of 2008-2009. We discuss how these results provide important new clues in tethering the competing processes involved in the daytime 150 km echoes and have significance in the recently proposed photoelectron-induced plasma fluctuations as a potential mechanism for the 150 km echoes.

  8. 30. Perimeter acquisition radar building room #318, showing radar control. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    30. Perimeter acquisition radar building room #318, showing radar control. Console and line printers - Stanley R. Mickelsen Safeguard Complex, Perimeter Acquisition Radar Building, Limited Access Area, between Limited Access Patrol Road & Service Road A, Nekoma, Cavalier County, ND

  9. 3. VIEW NORTHWEST, height finder radar towers, and radar tower ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. VIEW NORTHWEST, height finder radar towers, and radar tower (unknown function) - Fort Custer Military Reservation, P-67 Radar Station, .25 mile north of Dickman Road, east of Clark Road, Battle Creek, Calhoun County, MI

  10. Planetary radar studies

    NASA Technical Reports Server (NTRS)

    Thompson, T. W.; Cutts, J. A.

    1981-01-01

    A catalog of lunar and radar anomalies was generated to provide a base for comparison with Venusian radar signatures. The relationships between lunar radar anomalies and regolith processes were investigated, and a consortium was formed to compare lunar and Venusian radar images of craters. Time was scheduled at the Arecibo Observatory to use the 430 MHz radar to obtain high resolution radar maps of six areas of the lunar suface. Data from 1978 observations of Mare Serenitas and Plato are being analyzed on a PDP 11/70 computer to construct the computer program library necessary for the eventual reduction of the May 1981 and subsequent data acquisitions. Papers accepted for publication are presented.

  11. Application of Near-Space Passive Radar for Homeland Security

    NASA Astrophysics Data System (ADS)

    Wang, Wenqin

    2007-03-01

    To protect the homeland from terrorist attacks employing explosive devices, revolutionary advances across a wide range of technologies are required. Inspired by recent advances in near-space (defined as the region between 20 km and 100 km), this paper proposes a new passive radar system using opportunistic transmitter as an illuminator and near-space platform as a receiver. This concept differs substantially from current radars. This system can be operated as a passive bistatic or multistatic radar and hence largely immune to jamming. By placing the receiver in near-space platforms, many functions that are currently performed with satellites or airplanes could be performed much more cheaply and with much greater operational utility. These advantages make near-space passive attractive for a variety of applications, many of which fit well with the needs of homeland security. This paper details the role of near-space passive radar as sensor system that can support homeland security applications. The strengths and weakness of near-space passive radar, compared to current spaceborne and airborne radars, are detailed. The signal models and processing algorithms for near-space passive radar are provided. It is shown that the use of cost effective near-space platforms can provide the solutions that were previously thought to be out of reach to remote sensing and government customers.

  12. Temporal and spatial resolution of HF ocean radars

    NASA Astrophysics Data System (ADS)

    Heron, Malcom L.; Atwater, Daniel P.

    2013-03-01

    The spatial and temporal resolutions of the two main types of HF radar are compared, with reference to the phasedarray and the crossed-loop direction-finding systems which make up the Australian Coastal Ocean radar Network. Both genres use a swept frequency "chirp" modulation to define the range of a pixel being observed but the method for determining the azimuth direction of the pixel is a strong point of differentiation. The phased-array systems produce independent maps of surface currents in about 1/7 of the time for the crossed-loop systems because of contrasting noise performance of the antennas. The use of beam-forming analysis in the phased-arrays is shown to give spatial resolutions, for vector currents, of about 10 km close to the shore, and 25 km at ranges of 150 km. The corresponding vector current spatial resolutions for the crossed-loop systems are 40 km and 60 km respectively.

  13. Historical sketch: Radar geology

    NASA Technical Reports Server (NTRS)

    Macdonald, H.

    1980-01-01

    A chronological assessment is given of the broad spectra of technology associated with radar geology. Particular attention is given to the most recent developments made in the areas of microwave Earth resources applications and geologic remote sensing from aircraft and satellite. The significance of space derived radar in geologic investigations is discussed and the scientific basis for exploiting the sensitivity of radar signals to various aspects of geologic terrain is given.

  14. Towards a 1km resolution global flood risk model

    NASA Astrophysics Data System (ADS)

    Bates, Paul; Neal, Jeff; Sampson, Chris; Smith, Andy

    2014-05-01

    Recent advances in computationally efficient numerical algorithms and new High Performance Computing architectures now make high (1-2km) resolution global hydrodynamic models a realistic proposition. However in many areas of the world the data sets and tools necessary to undertake such modelling do not currently exist. In particular, five major problems need to be resolved: (1) the best globally available terrain data (SRTM) was generated from X-band interferometric radar data which does not penetrate vegetation canopies and which has significant problems in determining ground elevations in urban areas; (2) a global river bathymetry data set does not currently exist; (3) most river channels globally are less than the smallest currently resolvable grid scale (1km) and therefore require a sub-grid treatment; (4) a means to estimate the magnitude of the T year flood at any point along the global river network does not currently exist; and (5) a large proportion of flood losses are generated by off-floodplain surface water flows which are not well represented in current hydrodynamic modelling systems. In this paper we propose solutions to each of these five issues as part of a concerted effort to develop a 1km (or better) resolution global flood hazard model. We describe the new numerical algorithms, computer architectures and computational resources used, and demonstrate solutions to the five previously intractable problems identified above. We conduct a validation study of the modelling against satellite imagery of major flooding on the Mississippi-Missouri confluence plain in the central USA before outlining a proof-of-concept regional study for SE Asia as a step towards a global scale model. For SE Asia we simulate flood hazard for ten different flood return periods over the entire Thailand, Cambodia, Vietnam, Malaysia and Laos region at 1km resolution and show that the modelling produces coherent, consistent and sensible simulations of extent and water depth.

  15. Space Radar Image of Oil Slicks

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is a radar image of an offshore drilling field about 150 km (93 miles) west of Bombay, India, in the Arabian Sea. The dark streaks are extensive oil slicks surrounding many of the drilling platforms, which appear as bright white spots. Radar images are useful for detecting and measuring the extent of oil seepages on the ocean surface, from both natural and industrial sources. The long, thin streaks extending from many of the platforms are spreading across the sea surface, pushed by local winds. The larger dark patches are dispersed slicks that were likely discharged earlier than the longer streaks, when the winds were probably from a different direction. The dispersed oil will eventually spread out over the more dense water and become a layer which is a single molecule thick. Many forms of oil, both from biological and from petroleum sources, smooth out the ocean surface, causing the area to appear dark in radar images. There are also two forms of ocean waves shown in this image. The dominant group of large waves (upper center) are called internal waves. These waves are formed below the ocean surface at the boundary between layers of warm and cold water and they appear in the radar image because of the way they change the ocean surface. Ocean swells, which are waves generated by winds, are shown throughout the image but are most distinct in the blue area adjacent to the internal waves. Identification of waves provide oceanographers with information about the smaller scale dynamic processes of the ocean. This image was acquired by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on October 9, 1994. The colors are assigned to different frequencies and polarizations of the radar as follows: Red is L-band vertically transmitted, vertically received; green is the average of L-band vertically transmitted, vertically received and C-band vertically transmitted, vertically received; blue is C

  16. Aircraft and satellite measurement of ocean wave directional spectra using scanning-beam microwave radars

    NASA Technical Reports Server (NTRS)

    Jackson, F. C.; Walton, W. T.; Baker, P. L.

    1982-01-01

    A microwave radar technique for remotely measuring the vector wave number spectrum of the ocean surface is described. The technique, which employs short-pulse, noncoherent radars in a conical scan mode near vertical incidence, is shown to be suitable for both aircraft and satellite application, the technique was validated at 10 km aircraft altitude, where we have found excellent agreement between buoy and radar-inferred absolute wave height spectra.

  17. The altitude of type 3 auroral irregularities - Radar interferometer observations and implications

    NASA Astrophysics Data System (ADS)

    Sahr, J. D.; Farley, D. T.; Swartz, W. E.; Providakes, J. F.

    1991-10-01

    Altitude measurements are presented of type 3 auroral irregularities, acquired in northern Scandinavia in March 1989 during the second E Region Rocket Radar Instability Study campaign, that provide conclusive arguments against the electrostatic ion cyclotron instability theory. Interferometric analyses of coherent radar observations with a portable radar interferometer show that type 3 events occur at typical electrojet altitudes (100-120 km), at which the ion collision frequency is greater than the ion gyrofrequency, and no cyclotron motion is possible.

  18. Radar illusion via metamaterials

    NASA Astrophysics Data System (ADS)

    Jiang, Wei Xiang; Cui, Tie Jun

    2011-02-01

    An optical illusion is an image of a real target perceived by the eye that is deceptive or misleading due to a physiological illusion or a specific visual trick. The recently developed metamaterials provide efficient approaches to generate a perfect optical illusion. However, all existing research on metamaterial illusions has been limited to theory and numerical simulations. Here, we propose the concept of a radar illusion, which can make the electromagnetic (EM) image of a target gathered by radar look like a different target, and we realize a radar illusion device experimentally to change the radar image of a metallic target into a dielectric target with predesigned size and material parameters. It is well known that the radar signatures of metallic and dielectric objects are significantly different. However, when a metallic target is enclosed by the proposed illusion device, its EM scattering characteristics will be identical to that of a predesigned dielectric object under the illumination of radar waves. Such an illusion device will confuse the radar, and hence the real EM properties of the metallic target cannot be perceived. We designed and fabricated the radar illusion device using artificial metamaterials in the microwave frequency, and good illusion performances are observed in the experimental results.

  19. Metamaterial for Radar Frequencies

    DTIC Science & Technology

    2012-09-01

    Circuit Board RAM Radar Absorbing Material RCS Radar Cross Section SNR Signal-to-Noise Ratio SNG Single-Negative SRR Split Ring Resonator...although some can be single-negative ( SNG ). DNG refers to material with simultaneous negative real parts of the permittivity r  and permeability

  20. Synchronization in multistatic radar

    NASA Astrophysics Data System (ADS)

    Jubrink, H. G.

    1993-08-01

    This report gives a summary of multistatic radar principles and synchronization methods. Different methods are described using direct and indirect synchronization. The report also presents a general review of synchronization methods for the future. Two LORAN C receivers have been analyzed for use as local reference oscillators in multistatic radar.

  1. The PROUST radar

    NASA Technical Reports Server (NTRS)

    Bertin, F.; Glass, M.; Ney, R.; Petitdidier, M.

    1986-01-01

    The Stratosphere-Troposphere (ST) radar called PROUST works at 935 MHz using the same klystron and antenna as the coherent-scatter radar. The use of this equipment for ST work has required some important modifications of the transmitting system and the development of receiving, data processing and acquisition (1984,1985) equipment. The modifications are discussed.

  2. Noncooperative rendezvous radar system

    NASA Technical Reports Server (NTRS)

    1974-01-01

    A fire control radar system was developed, assembled, and modified. The baseline system and modified angle tracking system are described along with the performance characteristics of the baseline and modified systems. Proposed changes to provide additional techniques for radar evaluation are presented along with flight test data.

  3. Polarization Radar Processing Technology

    DTIC Science & Technology

    1989-10-01

    Oi"C FILE ( J qII RADC-TR-89-144 In-House Report October 1989 AD-A215 242 POLARIZATION RADAR PROCESSING TECHNOLOGY Kenneth C. Stiefvater, Russell D...NO. NO. NO. ACCESSION NO. 62702F 4506 11 58 11. TITLE (Include Security Classification) POLARIZATION RADAR PROCESSING TECHNOLOGY 12. PERSONAL AUTHOR(S

  4. Determination of radar MTF

    SciTech Connect

    Chambers, D.

    1994-11-15

    The ultimate goal of the Current Meter Array (CMA) is to be able to compare the current patterns detected with the array with radar images of the water surface. The internal wave current patterns modulate the waves on the water surface giving a detectable modulation of the radar cross-section (RCS). The function relating the RCS modulations to the current patterns is the Modulation Transfer Function (MTF). By comparing radar images directly with co-located CMA measurements the MTF can be determined. In this talk radar images and CMA measurements from a recent experiment at Loch Linnhe, Scotland, will be used to make the first direct determination of MTF for an X and S band radar at low grazing angles. The technical problems associated with comparing radar images to CMA data will be explained and the solution method discussed. The results suggest the both current and strain rate contribute equally to the radar modulation for X band. For S band, the strain rate contributes more than the current. The magnitude of the MTF and the RCS modulations are consistent with previous estimates when the wind is blowing perpendicular to the radar look direction.

  5. Java Radar Analysis Tool

    NASA Technical Reports Server (NTRS)

    Zaczek, Mariusz P.

    2005-01-01

    Java Radar Analysis Tool (JRAT) is a computer program for analyzing two-dimensional (2D) scatter plots derived from radar returns showing pieces of the disintegrating Space Shuttle Columbia. JRAT can also be applied to similar plots representing radar returns showing aviation accidents, and to scatter plots in general. The 2D scatter plots include overhead map views and side altitude views. The superposition of points in these views makes searching difficult. JRAT enables three-dimensional (3D) viewing: by use of a mouse and keyboard, the user can rotate to any desired viewing angle. The 3D view can include overlaid trajectories and search footprints to enhance situational awareness in searching for pieces. JRAT also enables playback: time-tagged radar-return data can be displayed in time order and an animated 3D model can be moved through the scene to show the locations of the Columbia (or other vehicle) at the times of the corresponding radar events. The combination of overlays and playback enables the user to correlate a radar return with a position of the vehicle to determine whether the return is valid. JRAT can optionally filter single radar returns, enabling the user to selectively hide or highlight a desired radar return.

  6. Observability of NEIALs with the Sondrestrom and Poker Flat incoherent scatter radars

    NASA Astrophysics Data System (ADS)

    Michell, R. G.; Samara, M.

    2013-12-01

    We present coordinated optical and radar observations using the Poker Flat Incoherent Scatter Radar (PFISR) in Alaska and the Sondrestrom radar in Greenland. Several cases were examined where intense, similar-looking dynamic auroral structures were observed in the magnetic zenith. The presence or absence of Naturally Enhanced Ion Acoustic Lines (NEIALs) was investigated in both sets of radar data. In all cases, the aurora exhibited small-scale (∼0.1-1 km), dynamic features that were observed with both all-sky and narrow-field of view (19°) imagers. In all of the cases examined, the PFISR radar observed NEIALs while the Sondrestrom radar did not, despite similar auroral morphology. The main difference between the radars, namely the probing wave number, provides strong evidence for a limiting spatial scale of between 10 and 15 cm for the enhanced wave activity responsible for NEIALs. This has implications for constraining the models of NEIAL generation mechanisms.

  7. Tropospheric gravity waves observed by three closely-spaced ST radars

    NASA Technical Reports Server (NTRS)

    Carter, D. A.; Eriddle, A. C. AFGARELLO, R.ly stable thro; Eriddle, A. C. AFGARELLO, R.ly stable thro

    1985-01-01

    During a 6 week period in 1982, 3 ST (Stratosphere-Troposphere) radars measured horizontal and vertical wavelengths of small scale tropospheric gravity waves. These 50 MHz, vertically-directed radars were located in a trianglar network with approximately 5 km spacing on the southern coast of France at the mouth of the Rhone River during the ALPEX (Alpine Experiment) program.

  8. On the origin of 150-km echoes: Recent observational results and current understanding

    NASA Astrophysics Data System (ADS)

    Patra, Amit

    2012-07-01

    Discovered nearly 45 years ago, the so-called 150-km echoing phenomenon continues to be a puzzle. These are the coherent radar echoes coming from the height region of 140-180 km during daytime and are of special interest to the ionospheric scientists since they are very useful means for estimating the daytime electric fields, a crucial parameter for studying daytime electrodynamics and plasma physics, and can be observed by radar with moderate sensitivity. Although the 150-km echoes are being regularly used for studying low latitude electrodynamics, it is a bit awkward using them in the scientific work without knowing their origin. This paper is meant to present and discuss new results obtained from Gadanki (13.5o N, 79.2o E, mag. lat. 6.5o N), India to elucidate the underlying physical processes, not considered before. Two new findings, one obtained during the passage of a solar eclipse and another linked with the intermediate layer type descending properties of 150-km echoes, clearly indicate the role of electron density gradient in generating the irregularities responsible for the 150-km radar echoes, not envisioned before. Given the fact that Gadanki is located at magnetically low latitude, it is proposed that the descending echoing layers are produced by interchange instability on the gradient of daytime descending ion layer formed by meridional wind shear associated with tidal/gravity waves quite similar to that observed during nighttime. Comparative anatomy of daytime 150-km echoes and nighttime intermediate layer echoes will also be presented and discussed in an effort to have a deeper understanding on the underlying instability processes.

  9. Spaceborne weather radar

    NASA Technical Reports Server (NTRS)

    Meneghini, Robert; Kozu, Toshiaki

    1990-01-01

    The present work on the development status of spaceborne weather radar systems and services discusses radar instrument complementarities, the current forms of equations for the characterization of such aspects of weather radar performance as surface and mirror-image returns, polarimetry, and Doppler considerations, and such essential factors in spaceborne weather radar design as frequency selection, scanning modes, and the application of SAR to rain detection. Attention is then given to radar signal absorption by the various atmospheric gases, rain drop size distribution and wind velocity determinations, and the characteristics of clouds, as well as the range of available estimation methods for backscattering, single- and dual-wavelength attenuation, and polarimetric and climatological characteristics.

  10. Micropower impulse radar imaging

    SciTech Connect

    Hall, M.S.

    1995-11-01

    From designs developed at the Lawrence Livermore National Laboratory (LLNL) in radar and imaging technologies, there exists the potential for a variety of applications in both public and private sectors. Presently tests are being conducted for the detection of buried mines and the analysis of civil structures. These new systems use a patented ultra-wide band (impulse) radar technology known as Micropower Impulse Radar (GPR) imaging systems. LLNL has also developed signal processing software capable of producing 2-D and 3-D images of objects embedded in materials such as soil, wood and concrete. My assignment while at LLNL has focused on the testing of different radar configurations and applications, as well as assisting in the creation of computer algorithms which enable the radar to scan target areas of different geometeries.

  11. Intelligent radar data processing

    NASA Astrophysics Data System (ADS)

    Holzbaur, Ulrich D.

    The application of artificial intelligence principles to the processing of radar signals is considered theoretically. The main capabilities required are learning and adaptation in a changing environment, processing and modeling information (especially dynamics and uncertainty), and decision-making based on all available information (taking its reliability into account). For the application to combat-aircraft radar systems, the tasks include the combination of data from different types of sensors, reacting to electronic counter-countermeasures, evaluation of how much data should be acquired (energy and radiation management), control of the radar, tracking, and identification. Also discussed are related uses such as monitoring the avionics systems, supporting pilot decisions with respect to the radar system, and general applications in radar-system R&D.

  12. Manganese(II)-azido/thiocyanato complexes of naphthylazoimidazoles: X-ray structures of Mn(β-NaiEt) 2(X) 2 (β-NaiEt = 1-ethyl-2-(naphthyl-β-azo)imidazole; X=N3-, NCS -)

    NASA Astrophysics Data System (ADS)

    Das, D.; Chand, B. G.; Wu, J. S.; Lu, T.-H.; Sinha, C.

    2007-10-01

    Manganese(II)-naphthylazoimidazole complexes using N3- and NCS - as counter ions are characterized as Mn(β-NaiR) 2(X) 2(β-NaiEt = 1-alkyl-2-(naphthyl-β-azo)imidazole; X=N3-, NCS -). The ligands are unsymmetric N(imidazole), N(azo) chelating agents. The microanalytical, spectral (FT-IR, UV-vis), magnetic (bulk moment and EPR) and electrochemical data establish the structure and composition of the complexes. The single crystal X-ray diffraction studies of Mn(β-NaiEt) 2(N 3) 2 and Mn(β-NaiEt) 2(NCS) 2(β-NaiEt = 1-ethyl-2-(naphthyl-β-azo)imidazole) have confirmed the three dimensional structure of the complexes. Cyclic voltammetry exhibits high potential Mn(III)/Mn(II) couple along with azo reductions. The EPR spectra show usual pattern.

  13. High-Altitude Cassini Radar Imaging of Titan

    NASA Astrophysics Data System (ADS)

    West, R. D.; Stiles, B.; Anderson, Y.; Boehmer, R.; Callahan, P.; Gim, Y.; Hamilton, G.; Hensley, S.; Janssen, M.; Johnson, W. T.; Kelleher, K.; Lorenz, R.; Ostro, S.; Paganelli, F.; Shaffer, S.; Wye, L.; Zebker, H.

    2006-12-01

    The Cassini spacecraft is now about halfway through its primary Tour of the Saturn system. By the time of this meeting, the radar instrument will have collected seven synthetic aperture strips during close flyby's, with 13 more to come. These images have resolutions as fine as 300 m. We present here data acquired using another imaging mode, very high altitude synthetic aperture radar (SAR) imaging, which extends imaging radar coverage and increases coincidental coverage with other Cassini imaging instruments such as VIMS and ISS. We also discuss calibration of SAR images and other radar data from additional engineering observations. Here we examine the performance trade-offs, special processing issues, and science potential of the high- altitude image observations, and the latest results from the calibration data. The high-altitude data collections are distinct from the normal Titan radar images because the range is much larger (around 20,000 km vs 950 km to 5000 km for normal SAR passes). To increase the signal to noise ratio in these circumstances, the radar operates in the lowest bandwidth scatterometer mode while spacecraft pointing control is used to slowly pan the central beam across a small swath. These high altitude images incorporate 150-200 independent looks in order to let us discriminate features that may lie below the noise floor. So far, three high-altitude images have been acquired, during Titan flyby's T12, T13, and T15. In T12 imaging was attempted from 37000 km with an effective resolution around 5 km. In T13 the Huygens Probe landing site was imaged from 11000 km with effective resolution of 1 2 km. In T15 the Tsegehi area was imaged from 20000 km with effective resolution of 2 -3 km. Additional high altitude image segments are also planned during the T19 and T20 Titan flyby's. The calibration observations are conducted independently or coupled with a distant icy satellite observation. They consist of receive-only data in all four bandwidths

  14. Distribution of P2Y2 receptors in the guinea pig enteric nervous system and its coexistence with P2X2 and P2X3 receptors, neuropeptide Y, nitric oxide synthase and calretinin.

    PubMed

    Xiang, Zhenghua; Burnstock, Geoffrey

    2005-11-01

    The distribution of P2Y2 receptor-immunoreactive (ir) neurons and fibers and coexistence of P2Y2 with P2X2 and P2X3 receptors, neuropeptide Y (NPY), calretinin (CR), calbindin (CB) and nitric oxide synthase (NOS) was investigated with immunostaining methods. The results showed that P2Y2-ir neurons and fibers were distributed widely in myenteric and submucous plexuses of the guinea pig stomach corpus, jejunum, ileum and colon. The typical morphology of P2Y2-ir neurons was a long process with strong positive staining on the same side of the cell body. The P2Y2-ir neurons could be Dogiel type 1. About 40-60% P2X3-ir neurons were immunoreactive for P2Y2 in the myenteric plexus and all the P2X3-ir neurons expressed the P2Y2 receptor in the submucosal plexus; almost all the NPY-ir neurons and the majority of CR-ir neurons were also immunoreactive for P2Y2, especially in the myenteric plexus of the small intestine; no P2Y2-ir neurons were immunoreactive for P2X2 receptors, CB and NOS. It is shown for the first time that S type/Dogiel type 1 neurons with fast P2X and slow P2Y receptor-mediated depolarizations could be those neurons expressing both P2Y2-ir and P2X3-ir and that they are widely distributed in myenteric and submucosal plexuses of guinea pig gut.

  15. Mixed-Up Sex Chromosomes: Identification of Sex Chromosomes in the X1X1X2X2/X1X2Y System of the Legless Lizards of the Genus Lialis (Squamata: Gekkota: Pygopodidae).

    PubMed

    Rovatsos, Michail; Johnson Pokorná, Martina; Altmanová, Marie; Kratochvíl, Lukáš

    2016-01-01

    Geckos in general show extensive variability in sex determining systems, but only male heterogamety has been demonstrated in the members of their legless family Pygopodidae. In the pioneering study published more than 45 years ago, multiple sex chromosomes of the type X1X1X2X2/X1X2Y were described in Burton's legless lizard (Lialisburtonis) based on conventional cytogenetic techniques. We conducted cytogenetic analyses including comparative genomic hybridization and fluorescence in situ hybridization (FISH) with selected cytogenetic markers in this species and the previously cytogenetically unstudied Papua snake lizard (Lialis jicari) to better understand the nature of these sex chromosomes and their differentiation. Both species possess male heterogamety with an X1X1X2X2/X1X2Y sex chromosome system; however, the Y and one of the X chromosomes are not small chromosomes as previously reported in L. burtonis, but the largest macrochromosomal pair in the karyotype. The Y chromosomes in both species have large heterochromatic blocks with extensive accumulations of GATA and AC microsatellite motifs. FISH with telomeric probe revealed an exclusively terminal position of telomeric sequences in L. jicari (2n = 42 chromosomes in females), but extensive interstitial signals, potentially remnants of chromosomal fusions, in L.burtonis (2n = 34 in females). Our study shows that even largely differentiated and heteromorphic sex chromosomes might be misidentified by conventional cytogenetic analyses and that the application of more sensitive cytogenetic techniques for the identification of sex chromosomes is beneficial even in the classical examples of multiple sex chromosomes.

  16. Influences of the substituents on the M-M bonding in Cp4Al4 and Cp2M2X2 (M = B, Al, Ga; Cp = C5H5, X = halogen).

    PubMed

    Lu, Feifei; Li, Xiaoyan; Sun, Zheng; Zeng, Yanli; Meng, Lingpeng

    2015-08-21

    Although the geometries of CpAl4 (Cp* = C5Me5) and Cp4Al4 (Cp = C5H5) are similar, CpAl4 is more stable than Cp4Al4. CpAl2I2 is the first complex involving an Al(ii)-Al(ii) bond to be supported by Cp-type ligands. In this work, the stability of CpAl4 and Cp4Al4 (Cp = C5H5), the nature of M-M bonding in Cp2M2X2 (M = B, Al, and Ga), and the influences of the X atom on the M-M bonds have been analyzed and compared within the framework of the atoms in molecules (AIM) theory, electron localization function (ELF), energy decomposition analysis (EDA), and natural bond orbital (NBO) analysis. The calculated results show that CpAl4 is more stable than Cp4Al4 because of HH interactions between the methyl groups on the same and different Cp rings and not because of the Al-Al bonds. In Cp2M2X2, the B-B bond is stronger than the Al-Al and Ga-Ga bonds. The B-B bond is most consistent with covalent bonding, whereas the Al-Al and Ga-Ga bonds are more consistent with metallic bonding. The strengths of the B-B bond increase in the sequence X = F, Cl, Br, and I, whereas the Al-Al and Ga-Ga bonds decrease in the sequence X = F, Cl, Br, and I. The different change tendencies arise from the different M-M bonds and the orbital interactions between atoms X and M.

  17. Synthesis, crystal structure and characterization of new 12H hexagonal perovskite-related oxides Ba 6M2Na 2X2O 17 ( M=Ru, Nb, Ta, Sb; X=V, Cr, Mn, P, As)

    NASA Astrophysics Data System (ADS)

    Quarez, Eric; Abraham, Francis; Mentré, Olivier

    2003-11-01

    The new Ba 6Ru 2Na 2X2O 17 ( X=V, Mn) compounds have been prepared by electrosynthesis in molten NaOH and their crystal structures have been refined from single crystals X-ray diffraction, space group P6 3/ mmc, Z=2, for X=V: a =5.8506(1) Å, c =29.6241(4) Å, R1=4.76%, for X=Mn : a =5.8323(1) Å, c =29.5299(3) Å, R1=3.48%. The crystal structure is a 12H-type perovskite with a ( c' cchcc) 2 stacking sequence of [BaO 3] c, [BaO 3] h and [BaO 2] c' layers. The tridimensional edifice is formed by blocks of Ru 2O 9 dimers that share corners with NaO 6 octahedra. These blocks sandwich double sheets of X5+O 4 tetrahedra. Several isotypic Ba 6M5+2Na 2X5+2O 17 materials ( X=V, Cr, Mn, P, As) and ( M=Ru, Nb, Ta, Sb) have been prepared by solid state reaction and characterized by Rietveld analysis. The magnetic and electric properties have been investigated and show besides the Ru 5+2O 9 typical intradimer antiferromagnetic couplings, discrepancies of both χ and ρ versus T at 50 and 100 K for Ba 6Ru 2Na 2X2O 17 ( X=V, As). In this work, a review of the identified Ru-hexagonal perovskite materials is also reported in order to overview the wide variety of possibilities in the field of new compounds synthesis.

  18. Comparison of FPS-16 radar/jimsphere and NASA's 50-MHz radar wind profiler turbulence indicators

    NASA Technical Reports Server (NTRS)

    Susko, Michael

    1993-01-01

    Measurements of the wind and turbulent regions from the surface to 16 km by the FPS-11 radar/jimsphere system are reported with particular attention given to the use of these turbulence and wind assessments to validate the NASA 50-MHz radar wind profiler. Wind profile statistics were compared at 150-m wavelengths, a wavelength validated from 20 jimspheres, simultaneously tracked by FPS-16 and FPQ-14 radar, and the resulting analysis of auto spectra, cross-spectra, and coherence squared spectra of the wind profiles. Results demonstrate that the NASA prototype wind profiler is an excellent monitoring device illustrating the measurements of the winds within 1/2 hour of launch zero.

  19. Space Radar Image of Owens Valley, California

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This is a three-dimensional perspective view of Owens Valley, near the town of Bishop, California that was created by combining two spaceborne radar images using a technique known as interferometry. Visualizations like this one are helpful to scientists because they clarify the relationships of the different types of surfaces detected by the radar and the shapes of the topographic features such as mountains and valleys. The view is looking southeast along the eastern edge of Owens Valley. The White Mountains are in the center of the image, and the Inyo Mountains loom in the background. The high peaks of the White Mountains rise more than 3,000 meters (10,000 feet) above the valley floor. The runways of the Bishop airport are visible at the right edge of the image. The meandering course of the Owens River and its tributaries appear light blue on the valley floor. Blue areas in the image are smooth, yellow areas are rock outcrops, and brown areas near the mountains are deposits of boulders, gravel and sand known as alluvial fans. The image was constructed by overlaying a color composite radar image on top of a digital elevation map. The radar data were taken by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) on board the space shuttle Endeavour in October 1994. The digital elevation map was produced using radar interferometry, a process in which radar data are acquired on different passes of the space shuttle. The two data passes are compared to obtain elevation information. The elevation data were derived from a 1,500-km-long (930-mile) digital topographic map processed at JPL. Radar image data are draped over the topography to provide the color with the following assignments: red is L-band vertically transmitted, vertically received; green is C-band vertically transmitted, vertically received; and blue is the ratio of C-band vertically transmitted, vertically received to L-band vertically transmitted, vertically received. This image is

  20. 4. VIEW NORTHEAST, radar tower (unknown function), prime search radar ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. VIEW NORTHEAST, radar tower (unknown function), prime search radar tower, emergency power building, and height finder radar tower - Fort Custer Military Reservation, P-67 Radar Station, .25 mile north of Dickman Road, east of Clark Road, Battle Creek, Calhoun County, MI

  1. 5. VIEW EAST, height finder radar towers, radar tower (unknown ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. VIEW EAST, height finder radar towers, radar tower (unknown function), prime search radar tower, operations building, and central heating plant - Fort Custer Military Reservation, P-67 Radar Station, .25 mile north of Dickman Road, east of Clark Road, Battle Creek, Calhoun County, MI

  2. Experimental High Resolution (3 km) SMAP Soil Moisture Data Fields With Uncertainty Estimates

    NASA Astrophysics Data System (ADS)

    Das, N. N.

    2015-12-01

    NASA's Soil Moisture Active Passive (SMAP) mission was launched on January 31st, 2015. The objective of the mission is global mapping of surface soil moisture and landscape freeze/thaw state. SMAP utilizes an L-band radar and radiometer sharing a rotating 6-meter mesh reflector antenna. The SMAP spacecraft is in a 685-km Sun-synchronous near-polar orbit, and viewing the surface at a constant 40-degree incidence angle with a 1000-km swath width. Merging of the high-resolution active (radar) and coarse-resolution but high-sensitivity passive (radiometer) L-band observations enable an unprecedented combination of accuracy, resolution, coverage and revisit-time for soil moisture and freeze/thaw state retrievals. However, on July 7th, 2015, the SMAP radar encountered an anomaly and is currently inoperable. Efforts are being made to revive the SMAP radar. Due to the present status of the SMAP observatory, nearly ~2.5 months (from the end of In-Orbit-Check April 13th, 2015 to July 7th, 2015) of the SMAP Active Passive product will be available to public through the NASA DAAC at National Snow and Ice Data Center (NSIDC). The baseline L2_SM_AP product is retrieved soil moisture from the disaggregated/downscaled brightness temperature obtained by merging the coarse-resolution (~36 km) radiometer brightness temperature data and the high-resolution (~3 km) radar backscatter data. The baseline product is intermediate scale 9 km global soil moisture information. Experimentally, a much higher resolution global surface soil moisture data set is also produced at 3 km. This experimental product covering the 2.5 Spring/Summer months is the focus of this presentation. We specifically focus on the analysis of errors and reliability of this data set. The errors in disaggregated brightness temperatures and the retrived soil moisture estimates are discussed. In the presentation the accuracies of the SMAP L2-SM_AP soil moisture retrievals will be shown using summary comparisons with in

  3. Radar remote sensing in biology

    USGS Publications Warehouse

    Moore, Richard K.; Simonett, David S.

    1967-01-01

    The present status of research on discrimination of natural and cultivated vegetation using radar imaging systems is sketched. The value of multiple polarization radar in improved discrimination of vegetation types over monoscopic radars is also documented. Possible future use of multi-frequency, multi-polarization radar systems for all weather agricultural survey is noted.

  4. Spaceborne meteorological radar studies

    NASA Technical Reports Server (NTRS)

    Meneghini, R.

    1988-01-01

    Various radar designs and methods are studied for the estimation of rainfall parameters from space. An immediate goal is to support the development of the spaceborne radar that has been proposed for the Tropical Rain Measuring Mission (TRMM). The effort is divided into two activities: a cooperative airborne rain measuring experiment with the Radio Research Laboratory of Japan (RRL), and the modelling of spaceborne weather radars. An airborne rain measuring experiment was conducted at Wallops Flight Facility in 1985 to 1986 using the dual-wavelength radar/radiometer developed by RRL. The data are presently being used to test a number of methods that are relevant to spaceborne weather radars. An example is shown of path-averaged rain rates as estimated from three methods: the standard reflectivity rain rate method (Z-R), a dual-wavelength method, and a surface reference method. The results from the experiment shows for the first time the feasibility of using attenuation methods from space. The purposes of the modelling are twofold: to understand in a quantitative manner the relationships between a particular radar design and its capability for estimating precipitation parameters and to help devise and test new methods. The models are being used to study the impact of various TRMM radar designs on the accuracy of rain rate estimation as well as to test the performance of range-profiling algorithms, the mirror-image method, and some recently devised graphical methods for the estimation of the drop size distribution.

  5. Neutral Wind Observations below 200 km altitudes

    NASA Astrophysics Data System (ADS)

    Watanabe, S.; Abe, T.; Habu, H.; Kakinami, Y.; Larsen, M. F.; Pfaff, R. F., Jr.; Yamamoto, M.

    2015-12-01

    Neutral Wind Observations below 200 km altitudesS. Watanabe1, T. Abe2, H. Habu2, Y. Kakinami3, M. Larsen4, R. Pfaff5, M. Yamamoto6, M-Y. Yamamoto31Hokkaido University/Hokkaido Information University, 2JAXA/ISAS, 3Kochi University of Technology, 4Clemson University, 5NASA/Goddard Space Flight Center, 6Kyoto University, Neutral wind in the thermosphere is one of the key parameters to understand the ionosphere-thermosphere coupling process. JAXA/ISAS successfully launched sounding rockets from Uchinoura Space Center (USC) on September 2, 2007, January 12, 2012, and July 20, 2013, and NASA launched sounding rockets from Kwajalein on May 7, 2013 and from Wallops on July 4, 2013. The rockets installed Lithium and/or TMA canisters as well as instruments for plasma and electric and magnetic fields. The atomic Lithium gases were released at altitudes between 150 km and 300 km in the evening on September 2, 2007, at altitude of ~100 km in the morning on January 12, 2012, at altitude of ~120km in the midnight on July 20, 2013, at altitude between 150 km and 300 km in the evening on May 7, 2013 and at altitude of ~150 km in the noon on July 4, 2013. The Lithium atoms were scattering sunlight by resonance scattering with wavelength of 670nm. However, the Lithium atoms scattered moon light on July 20, 2013. The moon light scattering is the first time to use for thermospheric wind measurement in the midnight. The Lithium clouds/trails and TMA trails showed clearly the neutral wind shears and atmospheric waves at ~150 km altitude in the lower thermosphere for all local time.

  6. Radar applications overview

    NASA Astrophysics Data System (ADS)

    Greenspan, Marshall

    1996-06-01

    During the fifty years since its initial development as a means of providing early warning of airborne attacks against allied countries during World War II, radar systems have developed to the point of being highly mobile and versatile systems capable of supporting a wide variety of remote sensing applications. Instead of being tied to stationary land-based sites, radar systems have found their way into highly mobile land vehicles as well as into aircraft, missiles, and ships of all sizes. Of all these applications, however, the most exciting revolution has occurred in the airborne platform arena where advanced technology radars can be found in all shapes and sizes...ranging from the large AWACS and Joint STARS long range surveillance and targeting systems to small millimeter wave multi-spectral sensors on smart weapons that can detect and identify their targets through the use of highly sophisticated digital signal processing hardware and software. This paper presents an overview of these radar applications with the emphasis on modern airborne sensors that span the RF spectrum. It will identify and describe the factors that influence the parameters of low frequency and ultra wide band radars designed to penetrate ground and dense foliage environments and locate within them buried mines, enemy armor, and other concealed or camouflaged weapons of war. It will similarly examine the factors that lead to the development of airborne radar systems that support long range extended endurance airborne surveillance platforms designed to detect and precision-located both small high speed airborne threats as well as highly mobile time critical moving and stationary surface vehicles. The mission needs and associated radar design impacts will be contrasted with those of radar systems designed for high maneuverability rapid acquisition tactical strike warfare platforms, and shorter range cued air-to-surface weapons with integral smart radar sensors.

  7. Radar frequency radiation

    NASA Astrophysics Data System (ADS)

    Malowicki, E.

    1981-11-01

    A method is presented for the determination of radar frequency radiation power densities that the PAVE PAWS radar system could produce in its air and ground environment. The effort was prompted by the concern of the people in the vicinity of OTIS AFB MA and BEALE AFB CA about the possible radar frequency radiation hazard of the PAVE PAWS radar. The method is based on the following main assumptions that: (a) the total field can be computed as the vector summation of the individual fields due to each antenna element; (b) the individual field can be calculated using distances for which the field point is in the far field of the antenna element. An RFR computer program was coded for the RADC HE 6180 digital computer and exercised to calculate the radiation levels in the air and ground space for the present baseline and the possible Six DB and 10 DB growth systems of the PAVE PAWS radar system at OTIS AFB MA. The average radiation levels due to the surveillance fence were computed for three regions: in the air space in front of the radar, at the radar hazard fence at OTIS AFB MA and at representative ground points in the OTIS AFB vicinity. It was concluded that the radar frequency radiation of PAVE PAWS does not present a hazard to personnel provided there is no entry to the air hazard zone or to the area within the hazard fence. The method developed offers a cost effective way to determine radiation levels from a phased array radar especially in the near field and transition regions.

  8. The estimation of space debris distribution by Kharkiv incoherent scatter radar data

    NASA Astrophysics Data System (ADS)

    Cherniak, Iurii

    Currently in near space are a large number of artificial origin objects. Among them are operable spacecrafts and the so-called "space debris". The Kharkiv radar is a sole incoherent scatter instrument on the middle latitudes of European region. The radar located near Kharkiv, Ukraine (geographic coordinates: 49.6N, 36.3E, geomagnetic coordinates: 45.7N, 117.8E). This powerful radar facility operates with 100-m zenith parabolic antenna at 158 MHz with peak transmitted power 2.0 MW, and can registered scattering of electromagnetic waves from small volumes (about ten square centimeters at distance 500 km). During the ionosphere parameters measurement by incoherent scatter radar are received different radar signals, different by nature from the signal, incoherent scattered ionosphere plasma. The paper presents the results of data analysis of several measurements cycles. It was obtained the distribution characteristics of the radar reflections from objects on Earth orbit. There are two main peak reflections appearance intensity at distances 800 km and 1000 km. Two other peaks at the altitude of 600 km and 1400 km. It is from distance above 1700 km the number of reflections is insignificant. Based on the experimental data was constructed height-temporal distribution of reflection signals. The total analysis time was about 200 hours. The intensity of reflections and their peak distances not significantly changed during day. The average number of observed reflections per day was about 500.

  9. A simulation study of scene confusion factors in sensing soil moisture from orbital radar

    NASA Technical Reports Server (NTRS)

    Ulaby, F. T. (Principal Investigator); Dobson, M. C.; Moezzi, S.; Roth, F. T.

    1983-01-01

    Simulated C-band radar imagery for a 124-km by 108-km test site in eastern Kansas is used to classify soil moisture. Simulated radar resolutions are 100 m by 100 m, 1 km by 1km, and 3 km by 3 km. Distributions of actual near-surface soil moisture are established daily for a 23-day accounting period using a water budget model. Within the 23-day period, three orbital radar overpasses are simulated roughly corresponding to generally moist, wet, and dry soil moisture conditions. The radar simulations are performed by a target/sensor interaction model dependent upon a terrain model, land-use classification, and near-surface soil moisture distribution. The accuracy of soil-moisture classification is evaluated for each single-date radar observation and also for multi-date detection of relative soil moisture change. In general, the results for single-date moisture detection show that 70% to 90% of cropland can be correctly classified to within +/- 20% of the true percent of field capacity. For a given radar resolution, the expected classification accuracy is shown to be dependent upon both the general soil moisture condition and also the geographical distribution of land-use and topographic relief. An analysis of cropland, urban, pasture/rangeland, and woodland subregions within the test site indicates that multi-temporal detection of relative soil moisture change is least sensitive to classification error resulting from scene complexity and topographic effects.

  10. News from KM3NeT

    SciTech Connect

    Katz, Ulrich F.; Collaboration: KM3NeT Collaboration

    2014-11-18

    KM3NeT is a future research infrastructure in the Mediterranean Sea, hosting a multi-cubic-kilometre neutrino telescope and nodes for Earth and Sea sciences. In this report we shortly summarise the genesis of the KM3NeT project and present key elements of its technical design. The physics objectives of the KM3NeT neutrino telescope and some selected sensitivity estimates are discussed. Finally, some first results from prototype operations and the next steps towards implementation – in particular the first construction phase in 2014/15 – are described.

  11. Mapping wintering waterfowl distributions using weather surveillance radar

    USGS Publications Warehouse

    Buler, Jeffrey J.; Randall, Lori A.; Fleskes, Joseph P.; Barrow, Wylie C.; Bogart, Tianna; Kluver, Daria

    2012-01-01

    The current network of weather surveillance radars within the United States readily detects flying birds and has proven to be a useful remote-sensing tool for ornithological study. Radar reflectivity measures serve as an index to bird density and have been used to quantitatively map landbird distributions during migratory stopover by sampling birds aloft at the onset of nocturnal migratory flights. Our objective was to further develop and validate a similar approach for mapping wintering waterfowl distributions using weather surveillance radar observations at the onset of evening flights. We evaluated data from the Sacramento, CA radar (KDAX) during winters 1998–1999 and 1999–2000. We determined an optimal sampling time by evaluating the accuracy and precision of radar observations at different times during the onset of evening flight relative to observed diurnal distributions of radio-marked birds on the ground. The mean time of evening flight initiation occurred 23 min after sunset with the strongest correlations between reflectivity and waterfowl density on the ground occurring almost immediately after flight initiation. Radar measures became more spatially homogeneous as evening flight progressed because birds dispersed from their departure locations. Radars effectively detected birds to a mean maximum range of 83 km during the first 20 min of evening flight. Using a sun elevation angle of -5° (28 min after sunset) as our optimal sampling time, we validated our approach using KDAX data and additional data from the Beale Air Force Base, CA (KBBX) radar during winter 1998–1999. Bias-adjusted radar reflectivity of waterfowl aloft was positively related to the observed diurnal density of radio-marked waterfowl locations on the ground. Thus, weather radars provide accurate measures of relative wintering waterfowl density that can be used to comprehensively map their distributions over large spatial extents.

  12. Mapping wintering waterfowl distributions using weather surveillance radar.

    PubMed

    Buler, Jeffrey J; Randall, Lori A; Fleskes, Joseph P; Barrow, Wylie C; Bogart, Tianna; Kluver, Daria

    2012-01-01

    The current network of weather surveillance radars within the United States readily detects flying birds and has proven to be a useful remote-sensing tool for ornithological study. Radar reflectivity measures serve as an index to bird density and have been used to quantitatively map landbird distributions during migratory stopover by sampling birds aloft at the onset of nocturnal migratory flights. Our objective was to further develop and validate a similar approach for mapping wintering waterfowl distributions using weather surveillance radar observations at the onset of evening flights. We evaluated data from the Sacramento, CA radar (KDAX) during winters 1998-1999 and 1999-2000. We determined an optimal sampling time by evaluating the accuracy and precision of radar observations at different times during the onset of evening flight relative to observed diurnal distributions of radio-marked birds on the ground. The mean time of evening flight initiation occurred 23 min after sunset with the strongest correlations between reflectivity and waterfowl density on the ground occurring almost immediately after flight initiation. Radar measures became more spatially homogeneous as evening flight progressed because birds dispersed from their departure locations. Radars effectively detected birds to a mean maximum range of 83 km during the first 20 min of evening flight. Using a sun elevation angle of -5° (28 min after sunset) as our optimal sampling time, we validated our approach using KDAX data and additional data from the Beale Air Force Base, CA (KBBX) radar during winter 1998-1999. Bias-adjusted radar reflectivity of waterfowl aloft was positively related to the observed diurnal density of radio-marked waterfowl locations on the ground. Thus, weather radars provide accurate measures of relative wintering waterfowl density that can be used to comprehensively map their distributions over large spatial extents.

  13. Mapping Wintering Waterfowl Distributions Using Weather Surveillance Radar

    PubMed Central

    Buler, Jeffrey J.; Randall, Lori A.; Fleskes, Joseph P.; Barrow, Wylie C.; Bogart, Tianna; Kluver, Daria

    2012-01-01

    The current network of weather surveillance radars within the United States readily detects flying birds and has proven to be a useful remote-sensing tool for ornithological study. Radar reflectivity measures serve as an index to bird density and have been used to quantitatively map landbird distributions during migratory stopover by sampling birds aloft at the onset of nocturnal migratory flights. Our objective was to further develop and validate a similar approach for mapping wintering waterfowl distributions using weather surveillance radar observations at the onset of evening flights. We evaluated data from the Sacramento, CA radar (KDAX) during winters 1998–1999 and 1999–2000. We determined an optimal sampling time by evaluating the accuracy and precision of radar observations at different times during the onset of evening flight relative to observed diurnal distributions of radio-marked birds on the ground. The mean time of evening flight initiation occurred 23 min after sunset with the strongest correlations between reflectivity and waterfowl density on the ground occurring almost immediately after flight initiation. Radar measures became more spatially homogeneous as evening flight progressed because birds dispersed from their departure locations. Radars effectively detected birds to a mean maximum range of 83 km during the first 20 min of evening flight. Using a sun elevation angle of −5° (28 min after sunset) as our optimal sampling time, we validated our approach using KDAX data and additional data from the Beale Air Force Base, CA (KBBX) radar during winter 1998–1999. Bias-adjusted radar reflectivity of waterfowl aloft was positively related to the observed diurnal density of radio-marked waterfowl locations on the ground. Thus, weather radars provide accurate measures of relative wintering waterfowl density that can be used to comprehensively map their distributions over large spatial extents. PMID:22911816

  14. A microprogrammable radar controller

    NASA Technical Reports Server (NTRS)

    Law, D. C.

    1986-01-01

    The Wave Propagation Lab. has completed the design and construction of a microprogrammable radar controller for atmospheric wind profiling. Unlike some radar controllers using state machines or hardwired logic for radar timing, this design is a high speed programmable sequencer with signal processing resources. A block diagram of the device is shown. The device is a single 8 1/2 inch by 10 1/2 inch printed circuit board and consists of three main subsections: (1) the host computer interface; (2) the microprogram sequencer; and (3) the signal processing circuitry. Each of these subsections are described in detail.

  15. Radar investigation of asteroids

    NASA Technical Reports Server (NTRS)

    Ostro, S. J.

    1981-01-01

    Efforts were focused on: (1) acquisition of radar data at Arecibo; (2) examination of raw data; (3) reduction of the unmodulated data to background-free, calibrated spectra; (4) integration and coherent analyses of the phase-coded data; and (5) calculation of Doppler shifts and preliminary values for echo limb-to-limb bandwidths, radar cross sections, and circular polarization ratios. Asteroids observed to data have radar properties distinct from those of the rocky terrestrial planets and those of the icy Galilean satellites.

  16. Radar investigation of asteroids

    NASA Technical Reports Server (NTRS)

    Ostro, S. J.

    1981-01-01

    Software to support all stages of asteroid radar observation and data analysis is developed. First-order analysis of all data in hand is complete. Estimates of radar cross sections, circular polarization ratios, and limb-to-limb echo spectral bandwidths for asteroids 7 Iris, 16 Psyche, 97 Klotho, 1862 Apollo, and 1915 Quetzalcoatl are reported. Radar observations of two previously unobserved asteroids were conducted. An Aten asteroid, 2100 Ra-Shalom, with the smallest known semimajor axis (0.83) was detected. Preliminary data reduction indicates a circular polarization ratio comparable to those of Apollo, Quetzalcoatl, and Toro.

  17. Radar investigation of asteroids

    NASA Technical Reports Server (NTRS)

    Ostro, S. J.

    1984-01-01

    The initial radar observations of the mainbelt asteroids 9 Metis, 27 Euterpe, and 60 Echo are examined. For each target, data are taken simultaneously in the same sense of circular polarization as transmitted as well as in the opposite (OC) sense. Estimates of the radar cross sections provide estimates of the circular polarization ratio, and the normalized OC radar cross section. The circular polarization ratio, is comparable to values measured for other large S type asteroids and for a few much smaller, Earth approaching objects, most of the echo is due to single reflection backscattering from smooth surface elements.

  18. Radar investigation of asteroids

    NASA Astrophysics Data System (ADS)

    Ostro, S. J.

    1981-11-01

    Software to support all stages of asteroid radar observation and data analysis is developed. First-order analysis of all data in hand is complete. Estimates of radar cross sections, circular polarization ratios, and limb-to-limb echo spectral bandwidths for asteroids 7 Iris, 16 Psyche, 97 Klotho, 1862 Apollo, and 1915 Quetzalcoatl are reported. Radar observations of two previously unobserved asteroids were conducted. An Aten asteroid, 2100 Ra-Shalom, with the smallest known semimajor axis (0.83) was detected. Preliminary data reduction indicates a circular polarization ratio comparable to those of Apollo, Quetzalcoatl, and Toro.

  19. Radar Remote Sensing

    NASA Technical Reports Server (NTRS)

    Rosen, Paul A.

    2012-01-01

    This lecture was just a taste of radar remote sensing techniques and applications. Other important areas include Stereo radar grammetry. PolInSAR for volumetric structure mapping. Agricultural monitoring, soil moisture, ice-mapping, etc. The broad range of sensor types, frequencies of observation and availability of sensors have enabled radar sensors to make significant contributions in a wide area of earth and planetary remote sensing sciences. The range of applications, both qualitative and quantitative, continue to expand with each new generation of sensors.

  20. Airborne Radar Observations of Severe Hailstorms: Implications for Future Spaceborne Radar

    NASA Technical Reports Server (NTRS)

    Heymsfield, Gerald M.; Tian, Lin; Li, Lihua; McLinden, Matthew; Cervantes, Jaime I.

    2013-01-01

    A new dual-frequency (Ku and Ka band) nadir-pointing Doppler radar on the high-altitude NASA ER-2 aircraft, called the High-Altitude Imaging Wind and Rain Airborne Profiler (HIWRAP), has collected data over severe thunderstorms in Oklahoma and Kansas during the Midlatitude Continental Convective Clouds Experiment (MC3E). The overarching motivation for this study is to understand the behavior of the dualwavelength airborne radar measurements in a global variety of thunderstorms and how these may relate to future spaceborne-radar measurements. HIWRAP is operated at frequencies that are similar to those of the precipitation radar on the Tropical Rainfall Measuring Mission (Ku band) and the upcoming Global Precipitation Measurement mission satellite's dual-frequency (Ku and Ka bands) precipitation radar. The aircraft measurements of strong hailstorms have been combined with ground-based polarimetric measurements to obtain a better understanding of the response of the Ku- and Ka-band radar to the vertical distribution of the hydrometeors, including hail. Data from two flight lines on 24 May 2011 are presented. Doppler velocities were approx. 39m/s2at 10.7-km altitude from the first flight line early on 24 May, and the lower value of approx. 25m/s on a second flight line later in the day. Vertical motions estimated using a fall speed estimate for large graupel and hail suggested that the first storm had an updraft that possibly exceeded 60m/s for the more intense part of the storm. This large updraft speed along with reports of 5-cm hail at the surface, reflectivities reaching 70 dBZ at S band in the storm cores, and hail signals from polarimetric data provide a highly challenging situation for spaceborne-radar measurements in intense convective systems. The Ku- and Ka-band reflectivities rarely exceed approx. 47 and approx. 37 dBZ, respectively, in these storms.

  1. Radar investigation of asteroids and planetary satellites

    NASA Technical Reports Server (NTRS)

    Ostro, Steven J.

    1988-01-01

    The aim is to make radar reconnaissance of near-Earth asteroids, mainbelt ateroids, the Galilean satellites, the Martian satellites, and the largest Saturnian satellites, using the Arecibo 13-cm and the Goldstone 3.5-cm systems. Measurements of echo strength, polarization, and delay/Doppler distribution of echo power provide information about dimensions, spin vector, large-scale topography, cm-to-m-scale morphology, and surface bulk density. The observations also yield refined estimates of target orbital elements. Radar signatures were measured for 31 mainbelt asteroids and 16 near-Earth asteroids since this task began eight years ago. The dispersion in asteroid radar albedoes and circular polarization ratios is extreme, revealing huge differences in surface morphologies, bulk densities, and metal concentration. For the most part, correction between radar signature and VIS/IR class is not high. Many near-Earth asteroids have extremely irregular, nonconvex shapes, but some have polar silhouettes that appear only slightly noncircular. The signatures of 1627 Ivar, 1986 DA, and the approximately 180-km mainbelt asteroid 216 Kleopatra suggest bifurcated shapes. Observational milestones during 1987 and 1988 are noted.

  2. Studies on Radar Sensor Networks

    DTIC Science & Technology

    2007-08-08

    through-foliage target detection using UWB radar sensor network based on real-world data; 2. Foliage clutter modeling using UWB radars; 3. Outdoor UWB...channel modeling based on field data; 4. Multi-target detection using radar sensor networks (theoretical studies); 5. SVD-QR and graph theory for MIMO...Superimposed code based channel assignment in multi-radio multi-channel wireless mesh networks. 15. SUBJECT TERMS Radar Sensor Network, UWB Radar, Sense

  3. Preliminary radar systems analysis for Venus orbiter missions

    NASA Technical Reports Server (NTRS)

    Brandenburg, R. K.; Spadoni, D. J.

    1971-01-01

    A short, preliminary analysis is presented of the problems involved in mapping the surface of Venus with radar from an orbiting spacecraft. Two types of radar, the noncoherent sidelooking and the focused synthetic aperture systems, are sized to fulfill two assumed levels of Venus exploration. The two exploration levels, regional and local, assumed for this study are based on previous Astro Sciences work (Klopp 1969). The regional level is defined as 1 to 3 kilometer spatial and 0.5 to 1 km vertical resolution of 100 percent 0 of the planet's surface. The local level is defined as 100 to 200 meter spatial and 50-10 m vertical resolution of about 100 percent of the surfAce (based on the regional survey). A 10cm operating frequency was chosen for both radar systems in order to minimize the antenna size and maximize the apparent radar cross section of the surface.

  4. Status of KM3NeT

    NASA Astrophysics Data System (ADS)

    Riccobene, G.

    2016-07-01

    The recent observation of cosmic neutrinos by IceCube has pushed the quest towards the identification of cosmic sources of high-energy particles. The KM3NeT Collaboration is now ready to launch the massive construction of detection units to be installed in deep sea to build a km-cubic size neutrino telescope. The main elements of the detector, the status of the project and the expected perfomances are briefly reported.

  5. On Radar Rainfall, Catchment Runoff and the Response Scale

    NASA Astrophysics Data System (ADS)

    Morin, E.; Goodrich, D. C.; Gao, X.; Sorooshian, S.

    2001-12-01

    The general research hypothesis is that: "a rainfall event, extreme at a specific scale, has the potential to generate an extreme runoff event in a catchment, which characterized by this response scale". In the presented study, which is a first step in testing this hypothesis, we examine if catchments have a stable response scale in the above context. For that purpose, we compare maximum storm rainfall intensities at different time and space scales with runoff peak discharges in order to determine at what scale these two variables are best related to each other. Three types of rainfall variable are tested: 1) gage rainfall intensity, 2) radar rainfall intensity, and 3) radar reflectivity. Initial results are available for the Walnut Gulch Experimental Catchment, a 150-km2 semi-arid catchment, located in southern Arizona. The catchment is well equipped with dense networks of rainfall and runoff gages. Radar data are also available for the catchment from the Tucson NEXRAD system. Preliminary results indicate a response scale in the order of 6-km and 2-hours for the 150-km2 catchment and for the 126- and 94-km2 sub-catchments. The response scale of a 25-km2 sub-catchment is reduced to 1-km and 20-minutes. The three types of rainfall variable tested point to the same response scale. As mentioned, the above results are initial and based on a limited number of events. We are investigating this hypothesis on a larger number of events as well as additional catchments.

  6. Analysis of the Gran Desierto, Pinacte Region, Sonora, Mexico, via shuttle imaging radar

    NASA Technical Reports Server (NTRS)

    Greeley, R.; Christensen, P. R.; Mchone, J. F.; Asmerom, Y.; Zimbelman, J. R.

    1984-01-01

    The radar discriminability of geolian features and their geological setting as imaged by the SIR-A experiment is examined. The Gran Desierto and Pincate volcanio field of Sonora, Mexico was used to analyze the radar characteristics of the interplay of aeolian features and volcano terrain. The area in the Gran Desierto covers 4000 sq. km. and contains sand dunes of several forms. The Pincate volcanio field covers more than 2.000 sq. km. and consists primarily of basaltic lavas. Margins of the field, especially on the western and northern sides, include several maar and maar-like craters; thus obtaining information on their radar characteristics for comparison with impact craters.

  7. Space Radar Image of Star City, Russia

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This radar image shows the Star City cosmonaut training center, east of Moscow, Russia. Four American astronauts are training here for future long-duration flights aboard the Russian Mir space station. These joint flights are giving NASA and the Russian Space Agency experience necessary for the construction of the international Alpha space station, beginning in late 1997. This image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR), on its 62nd orbit on October 3, 1994. This Star City image is centered at 55.55 degrees north latitude and 38.0 degrees east longitude. The area shown is approximately 32 kilometers by 49 kilometers (20 miles by 30 miles). North is to the top in this image. The radar illumination is from the top of the image. The image was produced using three channels of SIR-C radar data: red indicates L-band (23 cm wavelength, horizontally transmitted and received); green indicates L-band (horizontally transmitted and vertically received); blue indicates C-band (6 cm wavelength, horizontally transmitted and vertically received). In general, dark pink areas are agricultural; pink and light blue areas are urban communities; black areas represent lakes and rivers; dark blue areas are cleared forest; and light green areas are forested. The prominent black runways just right of center are Shchelkovo Airfield, about 4 km long. The textured pale blue-green area east and southeast of Shchelkovo Airfield is forest. Just east of the runways is a thin railroad line running southeast; the Star City compound lies just east of the small bend in the rail line. Star City contains the living quarters and training facilities for Russian cosmonauts and their families. Moscow's inner loop road is visible at the lower left edge of the image. The Kremlin is just off the left edge, on the banks of the meandering Moskva River. The Klyazma River snakes to the southeast from the reservoir in the upper left (shown in bright red

  8. Laser Radar Animation

    NASA Video Gallery

    Laser and radar instruments aboard NASA aircraft provide measurements of the snow and ice surface and down to the bedrock under the ice. Lasers, with a shorter wavelength, measure the surface eleva...

  9. Multispectral imaging radar

    NASA Technical Reports Server (NTRS)

    Porcello, L. J.; Rendleman, R. A.

    1972-01-01

    A side-looking radar, installed in a C-46 aircraft, was modified to provide it with an initial multispectral imaging capability. The radar is capable of radiating at either of two wavelengths, these being approximately 3 cm and 30 cm, with either horizontal or vertical polarization on each wavelength. Both the horizontally- and vertically-polarized components of the reflected signal can be observed for each wavelength/polarization transmitter configuration. At present, two-wavelength observation of a terrain region can be accomplished within the same day, but not with truly simultaneous observation on both wavelengths. A multiplex circuit to permit this simultaneous observation has been designed. A brief description of the modified radar system and its operating parameters is presented. Emphasis is then placed on initial flight test data and preliminary interpretation. Some considerations pertinent to the calibration of such radars are presented in passing.

  10. Radar investigation of asteroids

    NASA Technical Reports Server (NTRS)

    Ostro, S. J.

    1983-01-01

    For 80 Sappho, 356 Liguria, 694 Ekard, and 2340 Hathor, data were taken simultaneously in the same sense of circular polarization as transmitted (SC) as well as in the opposite (OC) sense. Graphs show the average OC and SC radar echo power spectra soothed to a resolution of EFB Hz and plotted against Doppler frequency. Radar observations of the peculiar object 2201 Oljato reveal an unusual set of echo power spectra. The albedo and polarization ratio remain fairly constant but the bandwidths range from approximately 0.8 Hz to 1.4 Hz and the spectral shapes vary dramatically. Echo characteristics within any one date's approximately 2.5-hr observation period do not fluctuate very much. Laboratory measurements of the radar frequency electrical properties of particulate metal-plus-silicate mixtures can be combined with radar albedo estimates to constrain the bulk density and metal weight, fraction in a hypothetical asteroid regolith having the same particle size distribution as lab samples.

  11. MU Radar Head Echo Observations of the 2011 October Draconids

    NASA Astrophysics Data System (ADS)

    Kero, J.; Fujiwara, Y.; Abo, M.; Szasz, C.; Nakamura, T.

    2012-05-01

    13 meteor head echoes from the 2011 October Draconids were observed with the MU radar in Japan. Their weighted mean geocentric velocity was 20.6±0.4km/s and the radiant located at RA=263°.3±0°.6, dec=55°.8±0°.2, in good agreement with simulations.

  12. Radar Cross Section Measurements

    DTIC Science & Technology

    1986-09-30

    Radar 54 17. Measured Range Sidelobe Performance of Chirp Radar 56 18. Range and Cross Range Image of Target Dror.’ŕ Vehicle 57 19. Incoherent rms...the measured range resolution, 4.9 in, closely agrees with the theoretical performance for this weighting. The measured range sidelobe performance...Interval 4.89in. 2% kHz 300 kHz 310 kHz (b) Expanded Scale + 5 ft from Target Figure 17. Measured Range Sidelobe Performance of

  13. Downhole pulse radar

    DOEpatents

    Chang, Hsi-Tien

    1987-09-28

    A borehole logging tool generates a fast rise-time, short duration, high peak-power radar pulse having broad energy distribution between 30 MHz and 300 MHz through a directional transmitting and receiving antennas having barium titanate in the electromagnetically active region to reduce the wavelength to within an order of magnitude of the diameter of the antenna. Radar returns from geological discontinuities are sampled for transmission uphole. 7 figs.

  14. Downhole pulse radar

    DOEpatents

    Chang, Hsi-Tien

    1989-01-01

    A borehole logging tool generates a fast rise-time, short duration, high peak-power radar pulse having broad energy distribution between 30 MHz and 300 MHz through a directional transmitting and receiving antennas having barium titanate in the electromagnetically active region to reduce the wavelength to within an order of magnitude of the diameter of the antenna. Radar returns from geological discontinuities are sampled for transmission uphole.

  15. Airborne MIMO GMTI Radar

    DTIC Science & Technology

    2011-03-31

    applications [1], [2], [3], [4]. [5]. [6]. [7]. [8]. [9]. [10]. [11]. [12]. Conventional phased array radars form a single coherent transmit beam and...intentionally left blank. 1. INTRODUCTION Conventional phased - array radars form a single coherent transmit beam and measure the backscattered response... steering vector for a SI MO array with nr"/? receiver phase centers located at positions xm + y„. This is how the MIMO virtual array arises. The waveforms

  16. Radar image San Francisco Bay Area, California

    NASA Technical Reports Server (NTRS)

    2000-01-01

    preliminary nature of this image product. These artifacts will be removed after further data processing.

    This image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11,2000. SRTM uses the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. The mission is designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency (NIMA) of the U.S. Department of Defense (DoD), and the German and Italian Space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise, Washington, DC.

    Size: 38 km (24 miles) by 71 km (44 miles) Location: 37.7 deg. North lat., 122.2 deg. West lon. Orientation: North to the upper right Original Data Resolution: 30 meters (99 feet) Date Acquired: February 16, 2000

  17. Chromosomal distribution of two multigene families and the unusual occurrence of an X1X1X2X2/X1X2Y sex chromosome system in the dolphinfish (Coryphaenidae): an evolutionary perspective.

    PubMed

    Soares, R X; Bertollo, L A C; Cioffi, M B; Costa, G W W F; F Molina, W

    2014-04-03

    Dolphinfishes (Coryphaenidae) are pelagic predators distributed throughout all tropical and subtropical oceans and are very important for commercial, traditional, and sport fishing. This small family contains the Coryphaena hippurus and Coryphaena equiselis species whose chromosomal aspects remain unknown, despite recent advances in cytogenetic data assimilation for Perciformes. In this study, both species were cytogenetically analyzed using different staining techniques (C-, Ag-, and CMA3 banding) and fluorescence in situ hybridization, to detect 18S rDNA and 5S rDNA. C. hippurus females exhibit 2n = 48 chromosomes, with 2m+4sm+42a (NF = 54). In C. equiselis, where both sexes could be analyzed, females displayed 2n = 48 chromosomes (2m+6sm+40a) and males exhibited 2n = 47 chromosomes (3m+6sm+38a) (NF = 56), indicating the presence of X1X1X2X2/X1X2Y multiple sex chromosomes. Sex-chromosome systems are rare in Perciformes, with this study demonstrating the first occurrence in a marine pelagic species. It remains unknown as to whether this system extends to other populations; however, these data are important with respect to evolutionary, phylogenetic, and speciation issues, as well as for elucidating the genesis of this unique sex system.

  18. Acid-sensing ion channel 3 or P2X2/3 is involved in the pain-like behavior under a high bone turnover state in ovariectomized mice.

    PubMed

    Kanaya, Kumiko; Iba, Kousuke; Abe, Yasuhisa; Dohke, Takayuki; Okazaki, Shunichiro; Matsumura, Tadaki; Yamashita, Toshihiko

    2016-04-01

    We have recently demonstrated that pathological changes leading to increased bone resorption by osteoclast activation are related to the induction of pain-like behavior in ovariectomized (OVX) mice. In addition, bisphosphonate and the antagonist of transient receptor potential vanilloid type 1 (TRPV1), an acid-sensing nociceptor, improved the threshold value of pain-like behaviors accompanying an improvement in the acidic environment in the bone tissue based on osteoclast inactivation. The aim of this study was to evaluate the effect of (i) an inhibitor of vacuolar H(+) -ATPase, known as an proton pump, (ii) an antagonist of acid-sensing ion channel (ASIC) 3, as another acid-sensing nociceptor, and (iii) the P2X2/3 receptor, as an ATP-ligand nociceptor, on pain-like behavior in OVX mice. This inhibitor and antagonists were found to improve the threshold value of pain-like behavior in OVX mice. These results indicated that the skeletal pain accompanying osteoporosis is possibly associated with the acidic microenvironment and increased ATP level caused by osteoclast activation under a high bone turnover state.

  19. Yttrium complexes incorporating the chelating diamides [ArN(CH2)xNAr]2- (Ar = C6H3-2,6-iPr2, x= 2, 3) and their unusual reaction with phenylsilane.

    PubMed

    Avent, Anthony G; Cloke, F Geoffrey N; Elvidge, Benjamin R; Hitchcock, Peter B

    2004-04-07

    Novel yttrium chelating diamide complexes [(Y[ArN(CH(2))(x)NAr](Z)(THF)(n))(y)] (Z = I, CH(SiMe(3))(2), CH(2)Ph, H, N(SiMe(3))(2), OC(6)H(3)-2,6-(t)Bu(2)-4-Me; x = 2, 3; n = 1 or 2; y = 1 or 2) were made via salt metathesis of the potassium diamides (x = 3 (3), x = 2 (4)) and yttrium triiodide in THF (5,10), followed by salt metathesis with the appropriate potassium salt (6-9, 11-13, 15) and further reaction with molecular hydrogen (14). 6 and 11(Z = CH(SiMe(3))(2), x = 2, 3) underwent unprecedented exchange of yttrium for silicon on reaction with phenylsilane to yield (Si[ArN(CH(2))(x)NAr]PhH) (x = 2 (16), 3) and (Si[CH(SiMe(3))(2)]PhH(2)).

  20. New insights into the comprehension of the magnetic properties of dinuclear Mn(III) compounds with the general formula [{MnL(NN)}2(μ-O)(μ-n-RC6H4COO)2]X2.

    PubMed

    Escriche-Tur, Luis; Font-Bardia, Mercè; Albela, Belén; Corbella, Montserrat

    2016-07-19

    Five new dinuclear Mn(iii) compounds with benzoato derivative bridges [{Mn(bpy)L}2(μ-O)(μ-n-RC6H4COO)2]X2 (n-R = 3-MeO, 4-MeO and 4-tBu, X = NO3(-) and ClO4(-)) were synthesised and characterised. According to X-ray diffraction, the X anions tend to be coordinated to the Mn ions and may occupy the place of the monodentate ligand L. Two structural isomers that only differ in one of their monodentate ligands have been obtained with the 3-MeOC6H4COO(-) bridges. For all compounds, the Mn(iii) ions display elongated octahedra with a pronounced rhombic distortion. To quantify these distortions separately, the elongation and rhombicity parameters Δ and ρ have been defined. The magnetic study shows a good relationship between the distortion of the coordination polyhedra and the zero field splitting parameters (DMn and EMn). From the magnetic data of a powder sample, it is possible to determine the sign and magnitude of DMn for ferromagnetic systems or weak antiferromagnetic systems with DMn < 0. For this kind of dinuclear compound, the R group at the meta position, the rhombic distortion of the octahedra, and large torsion angles between the Jahn-Teller axes lead to ferromagnetic interactions.

  1. Report on the comparison of the scan strategies employed by the Patrick Air Force Base WSR-74C/McGill radar and the NWS Melbourne WSR-88D radar

    NASA Technical Reports Server (NTRS)

    Taylor, Gregory; Evans, Randolph; Manobianco, John; Schumann, Robin; Wheeler, Mark; Yersavich, Ann

    1994-01-01

    The objective of this investigation is to determine whether the current standard WSR-88D radar (NEXRAD) scan strategies permit the use of the Melbourne WSR-88D to perform the essential functions now performed by the Patrick Air Force Base (PAFB) WSR-74C/McGill radar for evaluating shuttle weather flight rules (FR) and launch commit criteria (LCC). To meet this objective, the investigation compared the beam coverage patterns of the WSR-74C/McGill radar located at PAFB and the WSR-88D radar located at the Melbourne National Weather Service (NWS) Office over the area of concern for weather FR and LCC evaluations. The analysis focused on beam coverage within four vertical 74 km radius cylinders (1 to 4 km above ground level (AGL), 4 to 8 km AGL, 8 to 12 km AGL, and 1 to 12 km AGL) centered on Kennedy Space Center (KSC) Launch Complex 39A. The PAFB WSR-74C/McGill radar is approximately 17 km north-northeast of the Melbourne WSR-88D radar. The beam coverage of the WSR-88D using VCP 11 located at the Melbourne NWS Office is comparable (difference in percent of the atmosphere sampled between the two radars is 10 percent or less) within the area of concern to the beam coverage of the WSR-74C/McGill radar located at PAFB. Both radars provide good beam coverage over much of the atmospheric region of concern. In addition, both radars provide poor beam coverage (coverage less than 50 percent) over limited regions near the radars due to the radars' cone of silence and gaps in coverage within the higher elevation scans. Based on scan strategy alone, the WSR-88D radar could be used to perform the essential functions now performed by the PAFB WSR-74C/McGill radar for evaluating shuttle weather FR and LCC. Other radar characteristics may, however, affect the decision as to which radar to use in a given case.

  2. Daytime vertical and zonal velocities from 150-km echoes: Their relevance to F-region dynamics

    NASA Astrophysics Data System (ADS)

    Chau, Jorge L.; Woodman, Ronald F.

    2004-09-01

    As it was suggested by Kudeki and Fawcett [1993], and later shown by Woodman and Villanueva [1995], vertical Doppler velocities of daytime 150-km echoes represent the vertical E × B drift velocities at F region altitudes. Recently a special experiment was conducted to compare not only the vertical but also the zonal velocities from 150-km echoes with those from an incoherent scatter radar (ISR) mode perpendicular to the magnetic field. The vertical velocity comparisons show that (1) there is a very good agreement between 150-km velocity and the mean F-region E × B drift, and (2) much better agreement is found with the extrapolated values from the ISR altitudinal profiles. On the other hand poor-to-good agreement is found between their zonal components. Our preliminary zonal velocity results, indicate that there is a poor agreement before noontime, while better agreement is found in the afternoon.

  3. 66. VIEW SHOWING HOLD FOR RADAR CABLES AT RADAR SITE, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    66. VIEW SHOWING HOLD FOR RADAR CABLES AT RADAR SITE, LOOKING NORTH Everett Weinreb, photographer, March 1988 - Mount Gleason Nike Missile Site, Angeles National Forest, South of Soledad Canyon, Sylmar, Los Angeles County, CA

  4. Antarctic meteor observations using the Davis MST and meteor radars

    NASA Astrophysics Data System (ADS)

    Holdsworth, David A.; Murphy, Damian J.; Reid, Iain M.; Morris, Ray J.

    2008-07-01

    This paper presents the meteor observations obtained using two radars installed at Davis (68.6°S, 78.0°E), Antarctica. The Davis MST radar was installed primarily for observation of polar mesosphere summer echoes, with additional transmit and receive antennas installed to allow all-sky interferometric meteor radar observations. The Davis meteor radar performs dedicated all-sky interferometric meteor radar observations. The annual count rate variation for both radars peaks in mid-summer and minimizes in early Spring. The height distribution shows significant annual variation, with minimum (maximum) peak heights and maximum (minimum) height widths in early Spring (mid-summer). Although the meteor radar count rate and height distribution variations are consistent with a similar frequency meteor radar operating at Andenes (69.3°N), the peak heights show a much larger variation than at Andenes, while the count rate maximum-to-minimum ratios show a much smaller variation. Investigation of the effects of the temporal sampling parameters suggests that these differences are consistent with the different temporal sampling strategies used by the Davis and Andenes meteor radars. The new radiant mapping procedure of [Jones, J., Jones, W., Meteor radiant activity mapping using single-station radar observations, Mon. Not. R. Astron. Soc., 367(3), 1050-1056, doi: 10.1111/j.1365-2966.2006.10025.x, 2006] is investigated. The technique is used to detect the Southern delta-Aquarid meteor shower, and a previously unknown weak shower. Meteoroid speeds obtained using the Fresnel transform are presented. The diurnal, annual, and height variation of meteoroid speeds are presented, with the results found to be consistent with those obtained using specular meteor radars. Meteoroid speed estimates for echoes identified as Southern delta-Aquarid and Sextantid meteor candidates show good agreement with the theoretical pre-atmospheric speeds of these showers (41 km s -1 and 32 km s -1

  5. Measurement of momentum flux using two meteor radars in Indonesia

    NASA Astrophysics Data System (ADS)

    Matsumoto, Naoki; Shinbori, Atsuki; Riggin, Dennis M.; Tsuda, Toshitaka

    2016-03-01

    Two nearly identical meteor radars were operated at Koto Tabang (0.20° S, 100.32° E), West Sumatra, and Biak (1.17° S, 136.10° E), West Papua, in Indonesia, separated by approximately 4000 km in longitude on the Equator. The zonal and meridional momentum flux, u'w' and v'w', where u, v, and w are the eastward, northward, and vertical wind velocity components, respectively, were estimated at 86 to 94 km altitudes using the meteor radar data by applying a method proposed by Hocking (2005). The observed u'w' at the two sites agreed reasonably well at 86, 90, and 94 km during the observation periods when the data acquisition rate was sufficiently large enough. Variations in v'w' were consistent between 86, 90, and 94 km altitudes at both sites. The climatological variation in the monthly averaged u'w' and v'w' was investigated using the long-term radar data at Koto Tabang from November 2002 to November 2013. The seasonal variations in u'w' and v'w' showed a repeatable semiannual and annual cycles, respectively. u'w' showed eastward values in February-April and July-September and v'w' was northward in June to August at 90-94 km, both of which were generally anti-phase with the mean zonal and meridional winds, having the same periodicity. Our results suggest the usefulness of the Hocking method.

  6. Ground validation of Dual Precipitation Radar (DPR) on GPM by rapid scan Phased Array weahter Radar (PAR)

    NASA Astrophysics Data System (ADS)

    Hirano, Y.; Mega, T.; Shimamura, S.; Wu, T.; Kikuchi, H.; Ushio, T.; Yoshikawa, E.; Chandra, C. V.

    2014-12-01

    The core observatory satellite of the Global Precipitation Measurement (GPM) mission was launched on February 27th 2014. The Dual-frequency Precipitation Radar (DPR) on the GPM core observatory is the succession of the TRMM Precipitation Radar (PR). The DPR consists of a Ku-band precipitation radar and a Ka-band precipitation radar. The DPR is expected to be more sensitive than the PR especially in the measurement of light rainfall and snowfall in high latitude regions. Because of the difference of spatial and temporal resolutions, Space Radar (SR) and conventional type of Ground Radar (GR) are hard to compare.The SR observes each point of earth in short time, for example one footprint is an observation in some microseconds. Rain-gauge measurements have accurate rainfall rate, but rain-gage observes small area and accumulated rainfall in some minutes. The conventional GR can cover a wide area, however, a volume scan requires several minutes. The Phased Array weather Radar (PAR) is developed by Osaka University, Toshiba, and NICT. The PAR is a weather-radar on X-band within 100m range sampling. High spatial and temporal resolution is achieved by the PAR with pulse compression and the digital beam-forming technique. The PAR transmits a wide beam and receives narrow beams by using digital beam forming. Then, the PAR observes many elevation angles from a single pulse. The time of each volume scan is 10-30 seconds in operation, typically 30 seconds. The study shows comparisons between the DPR and the PAR by more similar spatial and temporal resolution. The rainfall region of DPR is similar to the one of PAR. Correlation coefficient of both radar reflectivity suggests more than 0.8 in the 20km range of PAR. As a result, it is considered that DPR can observe with high accuracy. We present the case study which DPR overpassed the PAR observation region in detail.

  7. Radar - ANL Wind Profiler with RASS, Goldendale - Raw Data

    SciTech Connect

    Coleman, Tim

    2016-10-25

    **Winds.** A radar wind profiler measures the Doppler shift of electromagnetic energy scattered back from atmospheric turbulence and hydrometeors along 3-5 vertical and off-vertical point beam directions. Back-scattered signal strength and radial-component velocities are remotely sensed along all beam directions and are combined to derive the horizontal wind field over the radar. These data typically are sampled and averaged hourly and usually have 6-m and/or 100-m vertical resolutions up to 4 km for the 915 MHz and 8 km for the 449 MHz systems. **Temperature.** To measure atmospheric temperature, a radio acoustic sound system (RASS) is used in conjunction with the wind profile. These data typically are sampled and averaged for five minutes each hour and have a 60-m vertical resolution up to 1.5 km for the 915 MHz and 60-m up to 3.5k m for the 449 MHz.

  8. Radar - ESRL Wind Profiler with RASS, Wasco Airport - Raw Data

    SciTech Connect

    Coleman, Tim

    2016-10-25

    **Winds.** A radar wind profiler measures the Doppler shift of electromagnetic energy scattered back from atmospheric turbulence and hydrometeors along 3-5 vertical and off-vertical point beam directions. Back-scattered signal strength and radial-component velocities are remotely sensed along all beam directions and are combined to derive the horizontal wind field over the radar. These data typically are sampled and averaged hourly and usually have 6-m and/or 100-m vertical resolutions up to 4 km for the 915 MHz and 8 km for the 449 MHz systems. **Temperature.** To measure atmospheric temperature, a radio acoustic sound system (RASS) is used in conjunction with the wind profile. These data typically are sampled and averaged for five minutes each hour and have a 60-m vertical resolution up to 1.5 km for the 915 MHz and 60-m up to 3.5k m for the 449 MHz.

  9. Radar - ANL Wind Profiler with RASS, Walla Walla - Raw Data

    SciTech Connect

    Coleman, Tim

    2016-10-25

    **Winds.** A radar wind profiler measures the Doppler shift of electromagnetic energy scattered back from atmospheric turbulence and hydrometeors along 3-5 vertical and off-vertical point beam directions. Back-scattered signal strength and radial-component velocities are remotely sensed along all beam directions and are combined to derive the horizontal wind field over the radar. These data typically are sampled and averaged hourly and usually have 6-m and/or 100-m vertical resolutions up to 4 km for the 915 MHz and 8 km for the 449 MHz systems. **Temperature.** To measure atmospheric temperature, a radio acoustic sound system (RASS) is used in conjunction with the wind profile. These data typically are sampled and averaged for five minutes each hour and have a 60-m vertical resolution up to 1.5 km for the 915 MHz and 60-m up to 3.5k m for the 449 MHz.

  10. Radar - ARL Wind Profilerwith RASS, Boardman - Raw Data

    SciTech Connect

    Coleman, Tim

    2016-10-25

    **Winds.** A radar wind profiler measures the Doppler shift of electromagnetic energy scattered back from atmospheric turbulence and hydrometeors along 3-5 vertical and off-vertical point beam directions. Back-scattered signal strength and radial-component velocities are remotely sensed along all beam directions and are combined to derive the horizontal wind field over the radar. These data typically are sampled and averaged hourly and usually have 6-m and/or 100-m vertical resolutions up to 4 km for the 915 MHz and 8 km for the 449 MHz systems. **Temperature.** To measure atmospheric temperature, a radio acoustic sound system (RASS) is used in conjunction with the wind profile. These data typically are sampled and averaged for five minutes each hour and have a 60-m vertical resolution up to 1.5 km for the 915 MHz and 60-m up to 3.5k m for the 449 MHz.

  11. Radar - ESRL Wind Profiler with RASS, Troutdale - Raw Data

    SciTech Connect

    Coleman, Tim

    2016-10-25

    **Winds.** A radar wind profiler measures the Doppler shift of electromagnetic energy scattered back from atmospheric turbulence and hydrometeors along 3-5 vertical and off-vertical point beam directions. Back-scattered signal strength and radial-component velocities are remotely sensed along all beam directions and are combined to derive the horizontal wind field over the radar. These data typically are sampled and averaged hourly and usually have 6-m and/or 100-m vertical resolutions up to 4 km for the 915 MHz and 8 km for the 449 MHz systems. **Temperature.** To measure atmospheric temperature, a radio acoustic sound system (RASS) is used in conjunction with the wind profile. These data typically are sampled and averaged for five minutes each hour and have a 60-m vertical resolution up to 1.5 km for the 915 MHz and 60-m up to 3.5k m for the 449 MHz.

  12. Radar - ANL Wind Profiler with RASS, Yakima - Raw Data

    SciTech Connect

    Coleman, Tim

    2016-10-25

    **Winds.** A radar wind profiler measures the Doppler shift of electromagnetic energy scattered back from atmospheric turbulence and hydrometeors along 3-5 vertical and off-vertical point beam directions. Back-scattered signal strength and radial-component velocities are remotely sensed along all beam directions and are combined to derive the horizontal wind field over the radar. These data typically are sampled and averaged hourly and usually have 6-m and/or 100-m vertical resolutions up to 4 km for the 915 MHz and 8 km for the 449 MHz systems. **Temperature.** To measure atmospheric temperature, a radio acoustic sound system (RASS) is used in conjunction with the wind profile. These data typically are sampled and averaged for five minutes each hour and have a 60-m vertical resolution up to 1.5 km for the 915 MHz and 60-m up to 3.5k m for the 449 MHz.

  13. Radar - ESRL Wind Profiler with RASS, Condon - Raw Data

    SciTech Connect

    Coleman, Tim

    2016-10-25

    **Winds.** A radar wind profiler measures the Doppler shift of electromagnetic energy scattered back from atmospheric turbulence and hydrometeors along 3-5 vertical and off-vertical point beam directions. Back-scattered signal strength and radial-component velocities are remotely sensed along all beam directions and are combined to derive the horizontal wind field over the radar. These data typically are sampled and averaged hourly and usually have 6-m and/or 100-m vertical resolutions up to 4 km for the 915 MHz and 8 km for the 449 MHz systems. **Temperature.** To measure atmospheric temperature, a radio acoustic sound system (RASS) is used in conjunction with the wind profile. These data typically are sampled and averaged for five minutes each hour and have a 60-m vertical resolution up to 1.5 km for the 915 MHz and 60-m up to 3.5k m for the 449 MHz.

  14. Radar - ESRL Wind Profiler with RASS, Prineville - Raw Data

    SciTech Connect

    Coleman, Tim

    2016-10-25

    **Winds.** A radar wind profiler measures the Doppler shift of electromagnetic energy scattered back from atmospheric turbulence and hydrometeors along 3-5 vertical and off-vertical point beam directions. Back-scattered signal strength and radial-component velocities are remotely sensed along all beam directions and are combined to derive the horizontal wind field over the radar. These data typically are sampled and averaged hourly and usually have 6-m and/or 100-m vertical resolutions up to 4 km for the 915 MHz and 8 km for the 449 MHz systems. **Temperature.** To measure atmospheric temperature, a radio acoustic sound system (RASS) is used in conjunction with the wind profile. These data typically are sampled and averaged for five minutes each hour and have a 60-m vertical resolution up to 1.5 km for the 915 MHz and 60-m up to 3.5k m for the 449 MHz.

  15. Plasma cortisol and testosterone following 19-km and 42-km kayak races.

    PubMed

    Lutoslawska, G; Obminski, Z; Krogulski, A; Sendecki, W

    1991-12-01

    Plasma cortisol and testosterone levels were examined in five, elite, male kayakers before and after 19-km and 42-km kayak races. Both races resulted in significant elevation in plasma cortisol and observed increase is likely to depend on race duration, being much more pronounced after 42-km race compared to 19-km. It should be stressed that observed elevation in cortisol level after 42-km race was higher than reported previously after a marathon run. This finding is in line with reports on hormonal changes in response to arms exercise. Both contests caused a decrease in plasma testosterone level, but the difference between races was not significant. Testosterone/cortisol ratio dropped significantly immediately after the races and the observed decrease was more dominant after the 42-km distance. On the next day, 18 h after the races plasma cortisol, testosterone levels and T/C ratio returned to basal level indicating recuperation from post exercise changes.

  16. A barrier radar concept

    NASA Astrophysics Data System (ADS)

    Marshall, J.; Ball, C.; Weissman, I.

    A description is given of a low power, light-weight radar that can be quickly set up and operated on batteries for extended periods of time to detect airborne intruders. With low equipment and operating costs, it becomes practical to employ a multiplicity of such radars to provide an unbroken intrusion fence over the desired perimeter. Each radar establishes a single transmitted fan beam extending vertically from horizon to horizon. The beam is generated by a two-face array antenna built in an A-frame configuration and is shaped, through phasing of the array elements, to concentrate the transmitter power in a manner consistent with the expected operating altitude ceiling of the targets of interest. The angular width of this beam in the dimension transverse to the fan depends on the radar transmission frequency and the antenna aperture dimension, but is typically wide enough so that a target at the maximum altitude or range will require tens of seconds to pass through the beam. A large number of independent samples of radar data will thus be available to provide many opportunities for target detection.

  17. A comparison of Northern Hemisphere winds using SuperDARN meteor trail and MF radar wind measurements

    NASA Astrophysics Data System (ADS)

    Hussey, G. C.; Meek, C. E.; André, D.; Manson, A. H.; Sofko, G. J.; Hall, C. M.

    The main purpose of the Super Dual Auroral Radar Network (SuperDARN) is to use paired radars to deduce the F-region convection from Doppler measurements of backscatter seen at large ranges, typically beyond ~900 km. Nearer to each HF radar, the nearest ranges at ~165-400 km are dominated by meteor trail echoes. Once formed, the motion of these meteor trails is normally controlled by neutral winds in the 80-110 km altitude range. By combining the line-of-sight velocities from all 16 receiver beams (~52° in azimuth) of a given SuperDARN radar, it is possible to determine the full horizontal wind vector field over the meteor trail height range. Elevation angles are also measured using an interferometer mode and as such height information can, in principle, be obtained from the combined range and elevation angle data. A comparison with neutral wind measurements from a colocated (Saskatoon, Canada) MF wind radar indicates good agreement between the two radar systems at heights of ~95 km. Based on these detailed comparisons, a simple common method for determining two-dimensional winds for all SuperDARN radars, which have extensive longitudinal coverage, was developed. Comparisons with other systems used for dynamical studies of tides and planetary waves are desirable and prove to be essential to obtain a good SuperDARN neutral wind motion analysis. The MF radars at Saskatoon and Troms[do], Norway, are located near the western and eastern ends of the Northern Hemisphere network of six SuperDARN radars. Comparisons between the two types of radars for two seasonal intervals (September and December) show that the SuperDARN radars provide good longitudinal coverage of tides in support of the more detailed MF radar data. The two systems complement each other effectively.

  18. Radar Studies on Kamb Ice Stream

    NASA Astrophysics Data System (ADS)

    Pettersson, R.; Osterhouse, D. J.; Mulhausen, A.; Welch, B. C.; Strandli, C. W.; Jacobel, R. W.

    2006-12-01

    During the past two Antarctic field seasons we acquired approximately 1600 km of ground-based ice- penetrating radar data on the lower trunk of Kamb Ice Stream (KIS) as part of radar, GPS and modeling study with scientists at the University of California Santa Cruz examining the possibility of ice stream reactivation. We present here a summary of radar results from this work and preliminary interpretations. Our working hypothesis is that the reactivation of the stagnant KIS may be triggered by excess influx of basal water produced by increased basal strain heating when mass builds up in the upper reaches of the locked ice stream. Using radar data, we have quantified variations in the amplitude of radar reflections from the ice-bed interface to estimate different provenances of occurrence of basal water. The weakest-reflecting ice-bed interface is found at a "sticky spot" in the middle of the ice stream trunk where ice appears to have become grounded over a large bedrock bump. At the sticky spot, bore holes drilled by California Technical Institute in 2000 showed a dry bed. A more highly reflective bed is located to either side of the sticky spot in regions of faster flow of KIS including one location where bore holes showed water at the ice-bed interface. However, the brightest bed is located approximately 80~km upstream of the sticky spot, where ice velocities are still on the order of 120~m a-1. Here radar reflected power is up to 1.5 times higher than elsewhere in the trunk despite the ice being 40% deeper. From this pattern of bed reflectivity we hypothesize that conditions allowing for rapid flow still exist under most areas of KIS and that sticky spots, like the one studied here, have played a key role in the ice stream shut down. We have also produced a map of detailed bed topography and tracked internal reflection layers over the sticky spot. We are able to trace the evolution of folds in the radar internal stratigraphy in this region in both time and space

  19. 33. Perimeter acquisition radar building room #320, perimeter acquisition radar ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    33. Perimeter acquisition radar building room #320, perimeter acquisition radar operations center (PAROC), contains the tactical command and control group equipment required to control the par site. Showing spacetrack monitor console - Stanley R. Mickelsen Safeguard Complex, Perimeter Acquisition Radar Building, Limited Access Area, between Limited Access Patrol Road & Service Road A, Nekoma, Cavalier County, ND

  20. Coordinated Radar Resource Management for Networked Phased Array Radars

    DTIC Science & Technology

    2014-12-01

    Research and Development Canada Ottawa, Canada K1A 0Z4 Email: Peter.Moo@drdc-rddc.gc.ca Abstract A phased array radar has the ability to rapidly and...search and Development Canada (DRDC) Ottawa to analyse the performance of radar resource management techniques for naval radars operating in a littoral

  1. The new Adelaide medium frequency Doppler radar

    NASA Astrophysics Data System (ADS)

    Reid, I. M.; Vandepeer, B. G. W.; Dillon, S.; Fuller, B.

    1993-08-01

    The Buckland Park Aerial Array (35 deg S, 138 deg E) is situated about 40 km north of Adelaide on a flat coastal plain. It was designed by Basil Briggs and Graham Elford, and constructed between 1965 and 1968. The first results were published in the late 1960's. Some aspects of the history of the array are described in Briggs (1993). A new MF Doppler Radar utilizing the array has been developed. This paper describes some of the technical details of this new facility.

  2. Phase modulating the Urbana radar

    NASA Technical Reports Server (NTRS)

    Herrington, L. J., Jr.; Bowhill, S. A.

    1983-01-01

    The design and operation of a switched phase modulation system for the Urbana Radar System are discussed. The system is implemented and demonstrated using a simple procedure. The radar system and circuits are described and analyzed.

  3. Rovibrationally selected ion-molecule collision study using the molecular beam vacuum ultraviolet laser pulsed field ionization-photoion method: charge transfer reaction of N2(+)(X 2Σg+; v+ = 0-2; N+ = 0-9) + Ar.

    PubMed

    Chang, Yih Chung; Xu, Yuntao; Lu, Zhou; Xu, Hong; Ng, C Y

    2012-09-14

    We have developed an ion-molecule reaction apparatus for state-selected absolute total cross section measurements by implementing a high-resolution molecular beam vacuum ultraviolet (VUV) laser pulsed field ionization-photoion (PFI-PI) ion source to a double-quadrupole double-octopole ion-guide mass spectrometer. Using the total cross section measurement of the state-selected N(2)(+)(v(+), N(+)) + Ar charge transfer (CT) reaction as an example, we describe in detail the design of the VUV laser PFI-PI ion source used, which has made possible the preparation of reactant N(2)(+)(X (2)Σ(g)(+), v(+) = 0-2, N(+) = 0-9) PFI-PIs with high quantum state purity, high intensity, and high kinetic energy resolution. The PFI-PIs and prompt ions produced in the ion source are shown to have different kinetic energies, allowing the clean rejection of prompt ions from the PFI-PI beam by applying a retarding potential barrier upstream of the PFI-PI source. By optimizing the width and amplitude of the pulsed electric fields employed to the VUV-PFI-PI source, we show that the reactant N(2)(+) PFI-PI beam can be formed with a laboratory kinetic energy resolution of ΔE(lab) = ± 50 meV. As a result, the total cross section measurement can be conducted at center-of-mass kinetic energies (E(cm)'s) down to thermal energies. Absolute total rovibrationally selected cross sections σ(v(+) = 0-2, N(+) = 0-9) for the N(2)(+)(X (2)Σ(g)(+); v(+) = 0-2, N(+) = 0-9) + Ar CT reaction have been measured in the E(cm) range of 0.04-10.0 eV, revealing strong vibrational enhancements and E(cm)-dependencies of σ(v(+) = 0-2, N(+) = 0-9). The thermochemical threshold at E(cm) = 0.179 eV for the formation of Ar(+) from N(2)(+)(X; v(+) = 0, N(+)) + Ar was observed by the measured σ(v(+) = 0), confirming the narrow ΔE(cm) spread achieved in the present study. The σ(v(+) = 0-2; N(+)) values obtained here are compared with previous experimental and theoretical results. The theoretical predictions

  4. Coherent IR radar technology

    NASA Astrophysics Data System (ADS)

    Gschwendtner, A. B.; Harney, R. C.; Hull, R. J.

    Recent progress in the development of coherent IR radar equipment is reviewed, focusing on the Firepond laser radar installation and the more compact systems derived for it. The design and capabilities of Firepond as a long-range satellite-tracking device are outlined. The technological improvements necessary to make laser radar mobile are discussed: a lightweight, stable 5-10-W transmitter laser for both CW and pulsed operation, a 12-element HgCdTe detector array, an eccentric-pupil Ritchey-Chretien telescope, and a combination of near-field phase modification and anamorphic expansion to produce a fan beam of relatively uniform intensity. Sample images obtained with a prototype system are shown, and the applicability of the mobile system to range-resolved coherent DIAL measurement is found to be similar to that of a baseline DIAL system.

  5. Daytime zonal drifts in the ionospheric E and 150 km regions estimated using EAR observations

    NASA Astrophysics Data System (ADS)

    Peddapati, PavanChaitanya; Otsuka, Yuichi; Yamamoto, Mamoru; Yokoyama, Tatsuhiro; Patra, Amit

    2016-07-01

    The Equatorial Atmosphere Radar (EAR), located at Kototabang (0.2o S, 100.32o E, mag. lat. 10.36o S), Indonesia, is capable of detecting both E region and 150 km echoes during daytime. We have conducted multi-beam observations using the EAR during daytime covering all seasons to study seasonal variations of these echoes and their dynamics. Given the facts that drifts at the 150 km region are governed primarily by electric field, drifts at the E region are governed by both electric field and neutral wind, simultaneous observations of drifts in both E and 150 km regions would help understand their variations. In this paper we present local time and seasonal variations of zonal drifts in the E and 150 km regions estimated using multi-beam observations. Zonal drifts (positive eastward) in the E and 150 km regions are found to be in the range of -10 to -60 m/s and -40 to 80 m/s, respectively. In the E region, zonal drifts show height reversal and temporal variations having tidal signature and noticeable seasonal variations. Zonal drifts in the 150 km region also show noticeable height and seasonal variations. These results are compared with model drifts and evaluated in terms of electric field and neutral wind.

  6. Radar data smoothing filter study

    NASA Technical Reports Server (NTRS)

    White, J. V.

    1984-01-01

    The accuracy of the current Wallops Flight Facility (WFF) data smoothing techniques for a variety of radars and payloads is examined. Alternative data reduction techniques are given and recommendations are made for improving radar data processing at WFF. A data adaptive algorithm, based on Kalman filtering and smoothing techniques, is also developed for estimating payload trajectories above the atmosphere from noisy time varying radar data. This algorithm is tested and verified using radar tracking data from WFF.

  7. Systems and Methods for Radar Data Communication

    NASA Technical Reports Server (NTRS)

    Bunch, Brian (Inventor); Szeto, Roland (Inventor); Miller, Brad (Inventor)

    2013-01-01

    A radar information processing system is operable to process high bandwidth radar information received from a radar system into low bandwidth radar information that may be communicated to a low bandwidth connection coupled to an electronic flight bag (EFB). An exemplary embodiment receives radar information from a radar system, the radar information communicated from the radar system at a first bandwidth; processes the received radar information into processed radar information, the processed radar information configured for communication over a connection operable at a second bandwidth, the second bandwidth lower than the first bandwidth; and communicates the radar information from a radar system, the radar information communicated from the radar system at a first bandwidth.

  8. A new multiple sex chromosome system X1X1X2X2/X1Y1X2Y2 in Siluriformes: cytogenetic characterization of Bunocephalus coracoideus (Aspredinidae).

    PubMed

    Ferreira, Milena; Garcia, Caroline; Matoso, Daniele Aparecida; de Jesus, Isac Silva; Feldberg, Eliana

    2016-10-01

    We analyzed one Bunocephalus coracoideus population from the Negro River basin using cytogenetic techniques. The results showed a diploid number of 42 chromosomes in both sexes, with the karyotypic formula 4m + 14sm + 24a and fundamental number (FN) = 60 for females and the formula 5m + 14sm + 23a and FN = 61 for males, constituting an X1X1X2X2/X1Y1X2Y2 multiple sex chromosome system. The constitutive heterochromatin is distributed in the pericentromeric regions of most of the chromosomes, except for the sex chromosomes, of which the X1, X2, and Y1 chromosomes were euchromatic and the Y2 chromosome was partially heterochromatic. 18S rDNA mapping confirmed the presence of nucleolar organizer regions on the short arms of the fifth chromosomal pair for both sexes. The 5S rDNA is present in the terminal regions of the short arms on the 2nd, 10th, and 12th pairs and on the X2 chromosome of both sexes; however, we observed variations in the presence of these ribosomal cistrons on the Y1 chromosome, on which the cistrons are pericentromeric, and on the Y2 chromosome, on which these cistrons are present in the terminal portions of the short and long arms. Telomeric sequences are located in the terminal regions of all of the chromosomes, particularly conspicuous blocks on the 10th and 12th pairs and internal telomeric sequences in the centromeric regions of the 1st, 6th, and 9th pairs for both sexes. This work describes an new sex chromosomes system for the Siluriformes and increases our genetic knowledge of the Aspredinidae family.

  9. MODIS 3 km and 10 km aerosol optical depth for China: Evaluation and comparison

    NASA Astrophysics Data System (ADS)

    He, Qingqing; Zhang, Ming; Huang, Bo; Tong, Xuelian

    2017-03-01

    The recently released Moderate Resolution Imaging Spectrometer (MODIS) Collection 6 introduced a fine scale aerosol optical depth (AOD) distribution, the 3 km product, which is expected to perform well in analyzing aerosols and identifying local air pollution, especially in the severely polluted atmosphere of China. However, few detailed evaluations of regional variations have been conducted. In this paper, we evaluate MODIS 3 km and 10 km AOD products for China against ground-based measurements and compare their performance with respect to spatial and temporal variations. The ground validations indicate that the two products are generally correlated well to ground-based observations. Spatially, the 3 km product slightly outperform the 10 km product in well-developed areas of southern China. Temporally, both products perform worse during spring and summer. Atmospheric clouds and underlying surface are two key factors that influence the accuracy and number of retrievals for both products. The comparison analysis reveals the newly introduced AOD product clearly shows good relationships with the coarse resolution retrievals in spatial and temporal variation but significant differences regarding details. The 3 km AOD product provides better aerosol gradients, more retrievals in bare areas of western China and some spikes of diurnal variation in cloudy days. Seasonal comparisons show the 3 km AOD product is higher than the 10 km product in all seasons, especially during spring and summer. Although the 3 km product for China generally performs slightly worse than the 10 km product, the added information of the MODIS 3 km AOD product shows potential for studying local aerosol characterization, and may facilitate studies of air pollution.

  10. Comparison between S. T. radar and in situ balloon measurements

    NASA Technical Reports Server (NTRS)

    Dalaudier, F.; Barat, J.; Bertin, F.; Brun, E.; Crochet, M.; Cuq, F.

    1986-01-01

    A campaign for simultaneous in situ and remote observation of both troposphere and stratosphere took place near Aire-sur-l'Adour (in southeastern France) on May 4, 1984. The aim of this campaign was a better understanding of the physics of radar echoes. The backscattered signal obtained with a stratosphere-troposphere radar both at the vertical and 15 deg. off vertical is compared with the velocity and temperature measurements made in the same region (about 10 km north of the radar site) by balloon-borne ionic anenometers and temperature sensors. In situ measurements clearly indicate that the temperature fluctuations are not always consistent with the standard turbulent theory. Nevertheless, the assumptions generally made (isotropy and turbulent field in k) and the classical formulation so derived for radar reflectivity are able to reproduce the shape of the radar return power profiles in oblique directions. Another significant result is the confirmation of the role played by the atmospheric stratification in the vertical echo power. It is important to develop these simultaneous in situ and remote experiments for a better description of the dynamical and thermal structure of the atmosphere and for a better understanding of the mechanisms governing clear-air radar reflectivity.

  11. Spaceborne Imaging Radar Symposium

    NASA Technical Reports Server (NTRS)

    Elachi, C.

    1983-01-01

    An overview of the present state of the art in the different scientific and technological fields related to spaceborne imaging radars was presented. The data acquired with the SEASAT SAR (1978) and Shuttle Imaging Radar, SIR-A (1981) clearly demonstrated the important emphasis in the 80's is going to be on in-depth research investigations conducted with the more flexible and sophisticated SIR series instruments and on long term monitoring of geophysical phenomena conducted from free-flying platforms such as ERS-1 and RADARSAT.

  12. Microwave radar oceanographic investigations

    NASA Technical Reports Server (NTRS)

    Jackson, F. C.

    1988-01-01

    The Radar Ocean Wave Spectrometer (ROWS) technique was developed and demonstrated for measuring ocean wave directional spectra from air and space platforms. The measurement technique was well demonstrated with data collected in a number of flight experiments involving wave spectral comparisons with wave buoys and the Surface Contour Radar (SCR). Recent missions include the SIR-B underflight experiment (1984), FASINEX (1986), and LEWEX (1987). ROWS related activity is presently concentrating on using the aircraft instrument for wave-processes investigations and obtaining the necessary support (consensus) for a satellite instrument development program. Prospective platforms include EOS and the Canadian RADARSAT.

  13. Spaceborne laser radar.

    NASA Technical Reports Server (NTRS)

    Flom, T.

    1972-01-01

    Development of laser systems to acquire and track targets in applications such as the rendezvous and docking of two spacecraft. A scan technique is described whereby a narrow laser beam is simultaneously scanned with an equally narrow receiver field-of-view without the aid of mechanical gimbals. Equations are developed in order to examine the maximum acquisition and tracking rates, and the maximum target range for a scanning laser radar system. A recently built prototype of a small, lightweight, low-power-consuming scanning laser radar is described.

  14. Radar Investigations of Asteroids

    NASA Technical Reports Server (NTRS)

    Ostro, S. J.

    1984-01-01

    Radar investigations of asteroids, including observations during 1984 to 1985 of at least 8 potential targets and continued analyses of radar data obtained during 1980 to 1984 for 30 other asteroids is proposed. The primary scientific objectives include estimation of echo strength, polarization, spectral shape, spectral bandwidth, and Doppler shift. These measurements yield estimates of target size, shape, and spin vector; place constraints on topography, morphology, density, and composition of the planetary surface; yield refined estimates of target orbital parameters; and reveals the presence of asteroidal satellites.

  15. Shuttle radar topography mapper (SRTM)

    NASA Astrophysics Data System (ADS)

    Jordan, Rolando L.; Caro, Edward R.; Kim, Yunjin; Kobrick, Michael; Shen, Yuhsyen; Stuhr, Frederick V.; Werner, Marian U.

    1996-12-01

    The use of interferometric SAR (IFSAR) to measure elevation is one of the most powerful and promising capabilities of radar. A properly equipped spaceborne IFSAR system can produce a highly accurate global digital elevation map, including cloud-covered areas, in significantly less time and at significantly lower cost than with other systems. For accurate topography, the interferometric measurements must be performed simultaneously in physically sperate receive system, since measurements made at different times with the same system suffer significant decorrelation. The US/German/Italian spaceborne imaging radar C/X-band SAR (SIR-C/X-SAR), successfully flown twice in 1994 aboard the Space Shuttle Endeavor, offers a unique opportunity for global multifrequency elevation mapping by the year 2000. With appropriate augmentation, SIR-C/X-SAR is capable of producing an accurate elevation map covering 80 percent of the Earth's land surface in a single 10-day Shuttle flight. The existing US SIR-C SCANSAR mode provides a 225-km swath at C-band, which makes this coverage possible. Addition of a C-band receive antenna, extended from the Shuttle bay on a mast and operating in concert with the existing SIR-C antenna, produces an interferometric pair. Accuracy is enhanced by utilizing the SIR-C dual polarizations simultaneously to form separate SCANSAR beams. Due to the practical limitation of approximately 60 meters for the mast length, the longer SIR-C L-band wavelength does not produce useful elevation measurement accuracy. IFSAR measurements can also be obtained by the German/Italian X-SAR, simultaneously with SIR-C, by utilizing an added outboard antenna at X-band to produce a swath coverage of about 50 km. Accuracy can be enhanced at both frequencies by processing both ascending and descending data takes. It is estimated that the 90 percent linear absolute elevation error achievable is less that 16 meters for elevation postings of 30 meters. This will be the first use of

  16. SEASAT Synthetic Aperture Radar Data

    NASA Technical Reports Server (NTRS)

    Henderson, F. M.

    1981-01-01

    The potential of radar imagery from space altitudes is discussed and the advantages of radar over passive sensor systems are outlined. Specific reference is made to the SEASAT synthetic aperture radar. Possible applications include oil spill monitoring, snow and ice reconnaissance, mineral exploration, and monitoring phenomena in the urban environment.

  17. Side looking radar calibration study

    NASA Technical Reports Server (NTRS)

    Edwards, W. D.

    1975-01-01

    Calibration of an airborne sidelooking radar is accomplished by the use of a model that relates the radar parameters to the physical mapping situation. Topics discussed include: characteristics of the transmitters; the antennas; target absorption and reradiation; the receiver and map making or radar data processing; and the calibration process.

  18. Close-range radar rainfall estimation and error analysis

    NASA Astrophysics Data System (ADS)

    van de Beek, C. Z.; Leijnse, H.; Hazenberg, P.; Uijlenhoet, R.

    2016-08-01

    Quantitative precipitation estimation (QPE) using ground-based weather radar is affected by many sources of error. The most important of these are (1) radar calibration, (2) ground clutter, (3) wet-radome attenuation, (4) rain-induced attenuation, (5) vertical variability in rain drop size distribution (DSD), (6) non-uniform beam filling and (7) variations in DSD. This study presents an attempt to separate and quantify these sources of error in flat terrain very close to the radar (1-2 km), where (4), (5) and (6) only play a minor role. Other important errors exist, like beam blockage, WLAN interferences and hail contamination and are briefly mentioned, but not considered in the analysis. A 3-day rainfall event (25-27 August 2010) that produced more than 50 mm of precipitation in De Bilt, the Netherlands, is analyzed using radar, rain gauge and disdrometer data. Without any correction, it is found that the radar severely underestimates the total rain amount (by more than 50 %). The calibration of the radar receiver is operationally monitored by analyzing the received power from the sun. This turns out to cause a 1 dB underestimation. The operational clutter filter applied by KNMI is found to incorrectly identify precipitation as clutter, especially at near-zero Doppler velocities. An alternative simple clutter removal scheme using a clear sky clutter map improves the rainfall estimation slightly. To investigate the effect of wet-radome attenuation, stable returns from buildings close to the radar are analyzed. It is shown that this may have caused an underestimation of up to 4 dB. Finally, a disdrometer is used to derive event and intra-event specific Z-R relations due to variations in the observed DSDs. Such variations may result in errors when applying the operational Marshall-Palmer Z-R relation. Correcting for all of these effects has a large positive impact on the radar-derived precipitation estimates and yields a good match between radar QPE and gauge

  19. A CW radar for ranging with PN/PSK modulation

    NASA Astrophysics Data System (ADS)

    Knapp, W.; Waesserling, H. G.; Wigger, B.

    The design and performance of a compact CW spread-spectrum ranging radar with pseudonoise phase-shift-keying (PN/PSK) modulation are discussed. The operating principles of the SAW convolver employed for matched filtering (Grossl, 1985) are explained; the system configuration is illustrated with a block diagram; and performance data are summarized in a table. The radar provides range resolution 2 m out to a maximum range of 2.4 km. Operating parameters include code length 511 chirps, dynamic range 50 dB, pseudorandom-function repetition rate 31.9 MHz, processing time 16 microsec, and target recognition level above noise 38 dB.

  20. 2-D inner-shelf current observations from a single VHF WEllen RAdar (WERA) station

    USGS Publications Warehouse

    Voulgaris, G.; Kumar, N.; Gurgel, K.-W.; Warner, J.C.; List, J.H.

    2011-01-01

    The majority of High Frequency (HF) radars used worldwide operate at medium to high frequencies (8 to 30 MHz) providing spatial resolutions ranging from 3 to 1.5 km and ranges from 150 to 50 km. This paper presents results from the deployment of a single Very High Frequency (VHF, 48 MHz) WEllen RAdar (WERA) radar with spatial resolution of 150 m and range 10-15 km, used in the nearshore off Cape Hatteras, NC, USA. It consisted of a linear array of 12 antennas operating in beam forming mode. Radial velocities were estimated from radar backscatter for a variety of wind and nearshore wave conditions. A methodology similar to that used for converting acoustically derived beam velocities to an orthogonal system is presented for obtaining 2-D current fields from a single station. The accuracy of the VHF radar-derived radial velocities is examined using a new statistical technique that evaluates the system over the range of measured velocities. The VHF radar velocities showed a bias of 3 to 7 cm/s over the experimental period explainable by the differences in radar penetration and in-situ measurement height. The 2-D current field shows good agreement with the in-situ measurements. Deviations and inaccuracies are well explained by the geometric dilution analysis. ?? 2011 IEEE.

  1. The estimation of 550 km x 550 km mean gravity anomalies. [from free atmosphere gravimetry data

    NASA Technical Reports Server (NTRS)

    Williamson, M. R.; Gaposchkin, E. M.

    1975-01-01

    The calculation of 550 km X 550 km mean gravity anomalies from 1 degree X 1 degree mean free-air gravimetry data is discussed. The block estimate procedure developed by Kaula was used, and estimates for 1452 of the 1654 blocks were obtained.

  2. Wuhan Atmosphere Radio Exploration (WARE) radar: System design and online winds measurements

    NASA Astrophysics Data System (ADS)

    Zhengyu, Zhao; Chen, Zhou; Haiyin, Qing; Guobin, Yang; Yuannong, Zhang; Gang, Chen; Yaogai, Hu

    2013-05-01

    The basic configuration of the Wuhan MST (mesosphere-stratosphere-troposphere) radar, which was designed and constructed by the School of Electronic Information, Wuhan University, is preliminarily described in this paper. The Wuhan MST radar operates at very high frequency (VHF) band (53.8 MHz) by observing the real-time characteristics of turbulence and the wind field vector in the height range of 3.5-90 km (not including 25-60 km) with high temporal and height resolutions. This all-solid-state, all-coherent pulse Doppler radar is China's first independent development of an MST radar focusing on atmospheric observation. The subsystems of the Wuhan MST radar include an antenna system, a feeder line system, all-solid-state radar transmitters, digital receivers, a beam control system, a signal processing system, a data processing system, a product generation system, and a user terminal. Advanced radar technologies are used, including highly reliable all-solid-state transmitters, low-noise large dynamic range digital receivers, an active phased array, high-speed digital signal processing, and real-time graphic terminals. This paper describes the design and implementation of the radar. Preliminary online wind measurements and results of the comparison to simultaneous observations by a GPS rawinsonde are presented as well.

  3. The Eyjafjöll explosive volcanic eruption from a microwave weather radar perspective

    NASA Astrophysics Data System (ADS)

    Marzano, F. S.; Lamantea, M.; Montopoli, M.; di Fabio, S.; Picciotti, E.

    2011-09-01

    The sub-glacial Eyjafjöll explosive volcanic eruptions of April and May 2010 are analyzed and quantitatively interpreted by using ground-based weather radar data and the Volcanic Ash Radar Retrieval (VARR) technique. The Eyjafjöll eruptions have been continuously monitored by the Keflavík C-band weather radar, located at a distance of about 155 km from the volcano vent. Considering that the Eyjafjöll volcano is approximately 20 km from the Atlantic Ocean and that the northerly winds stretched the plume toward the mainland Europe, weather radars are the only means to provide an estimate of the total ejected tephra. The VARR methodology is summarized and applied to available radar time series to estimate the plume maximum height, ash particle category, ash volume, ash fallout and ash concentration every 5 min near the vent. Estimates of the discharge rate of eruption, based on the retrieved ash plume top height, are provided together with an evaluation of the total erupted mass and volume. Deposited ash at ground is also retrieved from radar data by empirically reconstructing the vertical profile of radar reflectivity and estimating the near-surface ash fallout. Radar-based retrieval results cannot be compared with ground measurements, due to the lack of the latter, but further demonstrate the unique contribution of these remote sensing products to the understating and modelling of explosive volcanic ash eruptions.

  4. The Eyjafjöll explosive volcanic eruption from a microwave weather radar perspective

    NASA Astrophysics Data System (ADS)

    Marzano, F. S.; Lamantea, M.; Montopoli, M.; di Fabio, S.; Picciotti, E.

    2011-04-01

    The sub-glacial Eyjafjöll explosive volcanic eruptions of April and May 2010 are analyzed and quantitatively interpreted by using ground-based weather radar data and volcanic ash radar retrieval (VARR) technique. The Eyjafjöll eruptions have been continuously monitored by the Keflavík C-band weather radar, located at a distance of about 155 km from the volcano vent. Considering that the Eyjafjöll volcano is approximately 20 km far from the Atlantic Ocean and that the northerly winds stretched the plume toward the mainland Europe, weather radars are the only means to provide an estimate of the total ejected tephra. The VARR methodology is summarized and applied to available radar time series to estimate the plume maximum height, ash particle category, ash volume, ash fallout and ash concentration every 5 min near the vent. Estimates of the discharge rate of eruption, based on the retrieved ash plume top height, are provided together with an evaluation of the total erupted mass and volume. Deposited ash at ground is also retrieved from radar data by empirically reconstructing the vertical profile of radar reflectivity and estimating the near-surface ash fallout. Radar-based retrieval results cannot be compared with ground measurements, due to the lack of the latter, but further demonstrate the unique contribution of these remote sensing products to the understating and modelling of explosive volcanic ash eruptions.

  5. Applying WebMining on KM system

    NASA Astrophysics Data System (ADS)

    Shimazu, Keiko; Ozaki, Tomonobu; Furukawa, Koichi

    KM (Knowledge Management) systems have recently been adopted within the realm of enterprise management. On the other hand, data mining technology is widely acknowledged within Information systems' R&D Divisions. Specially, acquisition of meaningful information from Web usage data has become one of the most exciting eras. In this paper, we employ a Web based KM system and propose a framework for applying Web Usage Mining technology to KM data. As it turns out, task duration varies according to different user operations such as referencing a table-of-contents page, down-loading a target file, and writing to a bulletin board. This in turn makes it possible to easily predict the purpose of the user's task. By taking these observations into account, we segmented access log data manually. These results were compared with results abstained by applying the constant interval method. Next, we obtained a segmentation rule of Web access logs by applying a machine-learning algorithm to manually segmented access logs as training data. Then, the newly obtained segmentation rule was compared with other known methods including the time interval method by evaluating their segmentation results in terms of recall and precision rates and it was shown that our rule attained the best results in both measures. Furthermore, the segmented data were fed to an association rule miner and the obtained association rules were utilized to modify the Web structure.

  6. Km3Net Italy - Seafloor network

    NASA Astrophysics Data System (ADS)

    Papaleo, Riccardo

    2016-04-01

    The KM3NeT European project aims to construct a large volume underwater neutrino telescope in the depths of the Mediterranean Sea. INFN and KM3NeT collaboration, thanks to a dedicated funding of 21.000.000 € (PON 2007-2013), are committed to build and deploy the Phase 1 of the telescope, composed of a network of detection units: 8 towers, equipped with single photomultiplier optical modules, and 24 strings, equipped with multi-photomultipliers optical modules. All the towers and strings are connected to the main electro optical cable by means of a network of junction boxes and electro optical interlink cables. Each junction box is an active node able to provide all the necessary power to the detection units and to guarantee the data transmission between the detector and the on-shore control station. The KM3NeT Italia project foresees the realization and the installation of the first part of the deep sea network, composed of three junction boxes, one for the towers and two for the strings. In July 2015, two junction boxes have been deployed and connected to the new cable termination frame installed during the same sea campaign. The third and last one will be installed in November 2015. The status of the deep sea network is presented together with technical details of the project.

  7. Spatial Correlation of Rain Drop Size Distribution from Polarimetric Radar and 2D-Video Disdrometers

    NASA Technical Reports Server (NTRS)

    Thurai, Merhala; Bringi, Viswanathan; Gatlin, Patrick N.; Wingo, Matt; Petersen, Walter Arthur; Carey, Lawrence D.

    2011-01-01

    Spatial correlations of two of the main rain drop-size distribution (DSD) parameters - namely the median-volume diameter (Do) and the normalized intercept parameter (Nw) - as well as rainfall rate (R) are determined from polarimetric radar measurements, with added information from 2D video disdrometer (2DVD) data. Two cases have been considered, (i) a widespread, long-duration rain event in Huntsville, Alabama, and (ii) an event with localized intense rain-cells within a convection line which occurred during the MC3E campaign. For the first case, data from a C-band polarimetric radar (ARMOR) were utilized, with two 2DVDs acting as ground-truth , both being located at the same site 15 km from the radar. The radar was operated in a special near-dwelling mode over the 2DVDs. In the second case, data from an S-band polarimetric radar (NPOL) data were utilized, with at least five 2DVDs located between 20 and 30 km from the radar. In both rain event cases, comparisons of Do, log10(Nw) and R were made between radar derived estimates and 2DVD-based measurements, and were found to be in good agreement, and in both cases, the radar data were subsequently used to determine the spatial correlations For the first case, the spatial decorrelation distance was found to be smallest for R (4.5 km), and largest fo Do (8.2 km). For log10(Nw) it was 7.2 km (Fig. 1). For the second case, the corresponding decorrelation distances were somewhat smaller but had a directional dependence. In Fig. 2, we show an example of Do comparisons between NPOL based estimates and 1-minute DSD based estimates from one of the five 2DVDs.

  8. The Southern Argentina Agile Meteor Radar (SAAMER): Platform for comprehensive meteor radar observations and studies

    NASA Astrophysics Data System (ADS)

    Janches, D.; Hormaechea, J.; Pifko, S.; Hocking, W.; Fritts, D.; Brunini, C.; Close, S.; Michell, R.; Samara, M.

    2014-07-01

    The Southern Argentina Agile Meteor Radar (SAAMER) is a new generation system deployed in Rio Grande, Tierra del Fuego, Argentina (53^oS) in May 2008 (Janches et al., 2013,2014). SAAMER transmits 10 times more power than regular meteor radars, and uses a newly developed transmitting array, which focuses power upward instead of the traditional single-antenna-all-sky configuration. The system is configured such that the transmitter array can also be utilized as a receiver. The new design greatly increases the sensitivity of the radar enabling the detection of large numbers of particles at low zenith angles. The more concentrated transmitted power enables additional meteor studies besides those typical of these systems based on the detection of specular reflections, such as routine detections of head echoes and non-specular trails, previously only possible with High Power and Large Aperture radars (Janches et al., 2014). In August 2010, SAAMER was upgraded to a system capable to determine meteoroid orbital parameters. This was achieved by adding two remote receiving stations approximately 10 km away from the main site in near perpendicular directions (Pifko et al., 2014). The upgrade significantly expands the science that is achieved with this new radar enabling us to study the orbital properties of the interplanetary dust environment. Because of the unique geographical location, the SAAMER allows for additional inter-hemispheric comparison with measurements from Canadian Meteor Orbit Radar, which is geographically conjugate. Initial surveys show, for example, that SAAMER observes a very strong contribution of the South Toroidal Sporadic meteor source (Pifko et al., 2014), of which limited observational data is available. In addition, SAAMER offers similar unique capabilities for meteor showers and streams studies given the range of ecliptic latitudes that the system enables to survey (Janches et al., 2013). It can effectively observe radiants from the ecliptic south

  9. Radar Scans of the Saturn Rings

    NASA Astrophysics Data System (ADS)

    West, Richard D.; Janssen, Michael A.; Cuzzi, Jeffrey N.; Anderson, Yanhua; Hamilton, Gary; Cassini Radar Team

    2016-10-01

    The Cassini mission is now heading into its last year of observations. Part of the mission plan includes orbits that bring the spacecraft close to Saturn's rings prior to deorbiting into Saturn's atmosphere. These orbits are providing a unique opportunity to obtain backscatter measurements and relatively high-resolution brightness temperature measurements from the rings. We plan to scan the rings with the radar central beam and obtain backscatter measurements as a function of radial distance with some variation of incidence angle. Active mode radar scans are planned for four of the final high inclination orbits that bring the spacecraft close to the rings. These radar observations will be designed to sweep the A through C rings with varying bandwidth chirps selected to optimize the tradeoff between radial resolution and measurement variance. Pulse compression will deliver radial resolutions varying from about 200 m to around 4 km depending on the bandwidth used. These measurements will provide a 1-D profile of backscatter obtained at 2.2 cm wavelength that will complement similar passive profiles obtained at optical, infrared, and microwave wavelengths. This presentation will summarize the detailed designs and tradeoffs made for these observations. Such measurements will further constrain and inform models of the composition and structure of the ring particle distributions. This work is supported by the NASA Cassini Program at JPL - CalTech.

  10. Bird radar validation in the field by time-referencing line-transect surveys.

    PubMed

    Dokter, Adriaan M; Baptist, Martin J; Ens, Bruno J; Krijgsveld, Karen L; van Loon, E Emiel

    2013-01-01

    Track-while-scan bird radars are widely used in ornithological studies, but often the precise detection capabilities of these systems are unknown. Quantification of radar performance is essential to avoid observational biases, which requires practical methods for validating a radar's detection capability in specific field settings. In this study a method to quantify the detection capability of a bird radar is presented, as well a demonstration of this method in a case study. By time-referencing line-transect surveys, visually identified birds were automatically linked to individual tracks using their transect crossing time. Detection probabilities were determined as the fraction of the total set of visual observations that could be linked to radar tracks. To avoid ambiguities in assigning radar tracks to visual observations, the observer's accuracy in determining a bird's transect crossing time was taken into account. The accuracy was determined by examining the effect of a time lag applied to the visual observations on the number of matches found with radar tracks. Effects of flight altitude, distance, surface substrate and species size on the detection probability by the radar were quantified in a marine intertidal study area. Detection probability varied strongly with all these factors, as well as species-specific flight behaviour. The effective detection range for single birds flying at low altitude for an X-band marine radar based system was estimated at ~1.5 km. Within this range the fraction of individual flying birds that were detected by the radar was 0.50 ± 0.06 with a detection bias towards higher flight altitudes, larger birds and high tide situations. Besides radar validation, which we consider essential when quantification of bird numbers is important, our method of linking radar tracks to ground-truthed field observations can facilitate species-specific studies using surveillance radars. The methodology may prove equally useful for optimising

  11. Multiparameter Radar and Aircraft Based Studies of Microphysical, Kinematic and Electrical Structure of Convective Clouds during CaPE

    DTIC Science & Technology

    1994-03-31

    Caylor 1991 ). distributions of p (0) from light rainfall (drizzle) and A conventional differential reflectivity ZDR radar , a "bright band ," the mean...above 8 km regions containing cloud water with low (-25 0 C ) at the time the 2-dB ZDR column concentrations of rain. began to fall back from the 5 km...et al. (1989) have reported single polarization radar observations of Lightning echoes were observed in thunderstorms lightning at UHF, S- band , and C

  12. Interception of LPI Radar Signals

    DTIC Science & Technology

    1991-11-01

    AD-A246 315!I! I!! II I’ IIi INTERCEPTION OF LPI RADAR SIGNALS (U) by Jim P.Y. Lee DEFENCE RESEARCH ESTABLISHMENT OTTAWA TECHNICAL NOTE 91-23 Canadd...November 1991Ottawa 92-041269’ 2 2 18 II.2t1111111I 111111! !_ 1+1 efrc nadonds INTERCEPTION OF LPI RADAR SIGNALS (U) by Jim P.Y. Lee Radar E"Sect&ion... radar may employ against current EW receivers. The general conclusion is that it is possible to design a LPI radar which is effective against current

  13. Aggregation and disaggregation of radar rainfall rates

    NASA Astrophysics Data System (ADS)

    Krebsbach, K.; Friederichs, P.

    2012-12-01

    Spatially distributed, high-resolution precipitation rates are key ingredients for modeling soil-vegetation processes, water and solute transports in mesoscale catchments, and for short-range weather prediction. The ultimate goal of our study is to develop a space-time, multilevel statistical model that merges rain radar measurements with other observations of precipitation. This is a challenging task since it aims at combining data sources with a variety of error structures, and temporal resolutions. E.g., in-situ measurements are quite accurate, but available only at sparse and irregularly distributed locations, whereas remote measurements cover complete areas but suffer from spatially and temporally inhomogeneous systematic errors. The first step towards such a space-time precipitation model is to develop a statistical model for precipitation based on radar measurements. Precipitation rates over a region of about 230× 230 km2 are provided by a composite of the two polarimetric X-band radars in Germany. The two radars are located in a distance of about 60 km in Bonn and Jülich, respectively. For the statistical model formulation we use a Gaussian Markov random field as underlying process. A Markov random field is a suitable model to account for spatial dependencies if the neighborhood can be reduced to a small region without losing information. This makes large data problems computationally feasible, since the neighborhood structure is given by a sparse precision matrix. Markov random fields are closely related to a graphical models. In processing the unadjusted radar rainfall rates, we follow D. Allcroft and C. Glasbey (2003)footnote{⪉bel{foot:1}David Allcroft and Chris Glasbey (2003). A latent Gaussian Markov Random Field model for spatiotemporal rainfall disaggregationJournal of the Royal Statistical Society: Series C (Applied Statistics), 52:487-498}. We start with a transformation of the precipitation rates to a truncated Gaussian distribution. The

  14. Synthetic Aperture Radar Interferometry

    NASA Technical Reports Server (NTRS)

    Rosen, P. A.; Hensley, S.; Joughin, I. R.; Li, F.; Madsen, S. N.; Rodriguez, E.; Goldstein, R. M.

    1998-01-01

    Synthetic aperture radar interferometry is an imaging technique for measuring the topography of a surface, its changes over time, and other changes in the detailed characteristics of the surface. This paper reviews the techniques of interferometry, systems and limitations, and applications in a rapidly growing area of science and engineering.

  15. Netted LPI RADARs

    DTIC Science & Technology

    2011-09-01

    Characteristics ALQ-172 B-52G/H Self- protection Track/search radar jamming, steerable jam beams , software programmable, phased array antenna ...bore sight: knowing the pattern of the antenna’s gain, two or more intercepts within the antenna main beam are sufficient to determine the...14 a. Low Level Antenna Sidelobes .............14 b. Antenna Scan Patterns ...................18 4. Carrier Frequency Selection

  16. Rain radar instrument definition

    NASA Astrophysics Data System (ADS)

    Vincent, Nicolas; Chenebault, J.; Suinot, Noel; Mancini, Paolo L.

    1996-12-01

    As a result of a pre-phase a study, founded by ESA, this paper presents the definition of a spaceborne Rain Radar, candidate instrument for earth explorer precipitation mission. Based upon the description of user requirements for such a dedicated mission, a mission analysis defines the most suitable space segment. At system level, a parametric analysis compares pros and cons of instrument concepts associated with rain rate retrieval algorithms in order to select the most performing one. Several trade-off analysis at subsystem level leads then to the definition of the proposed design. In particular, as pulse compression is implemented in order to increase the radar sensitivity, the selected method to achieve a pulse response with a side-lobe level below--60 dB is presented. Antenna is another critical rain radar subsystem and several designs are com pared: direct radiating array, single or dual reflector illuminated by single or dual feed arrays. At least, feasibility of centralized amplification using TWTA is compared with criticality of Tx/Rx modules for distributed amplification. Mass and power budgets of the designed instrument are summarized as well as standard deviations and bias of simulated rain rate retrieval profiles. The feasibility of a compliant rain radar instrument is therefore demonstrated.

  17. Frequency Diverse Array Radar

    DTIC Science & Technology

    2010-09-01

    the methods for electronic scanning of antenna systems. Techniques that have been studied in this connection include frequency variation, phase shift...an array antenna instantaneously into a desired direction where no mechanical mechanism is involved in the scanning process. Electronic scanning... methods including phase scanning, time delay scanning, and frequency scanning have been used in various radar applications; however new and cheaper

  18. Passive MIMO Radar Detection

    DTIC Science & Technology

    2013-09-01

    Hypothesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 3.3.3 Dependence on SNR...71 4.3.3 Dependence on SNR and DNR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 4.4 Interpretations...described as a passive radar network. The topology of such networks is described as bistatic, multistatic, or multiple-input multiple-output, depending on

  19. Passive bistatic radar analysis

    NASA Astrophysics Data System (ADS)

    O'Hagan, Daniel W.; Kuschel, H.; Schiller, Joachim

    2009-06-01

    Passive Bistatic Radar (PBR) research is at its zenith with several notable PBR systems currently operational, or available for deployment. Such PBRs include the Manastash Ridge Radar (MRR) developed for and by academia; Silent Sentry developed as a commercial concern by Lockheed Martin; and Homeland Alerter (HA100) also a commercial system developed by Thales. However at present, despite the existence of numerous PBR prototypes, take up of commercial passive radar technology remains slow. This is due in part to technology immaturity, in part to politics, and particularly due to the fact that monostatic radars perform so well. If PBRs are to enjoy longevity as a viable technology then it is imperative that they address certain niche application areas, with the aforementioned MRR being one prime example of this. The focus of this paper will be an analysis of a PBR system that utilised FM radio signals of opportunity to detect aircraft targets with an RCS generally not lower than 20 m2. The paper will demonstrate the theoretical detection coverage of an FM based PBR operating in a severe interference environment.

  20. Impulse radar studfinder

    DOEpatents

    McEwan, T.E.

    1995-10-10

    An impulse radar studfinder propagates electromagnetic pulses and detects reflected pulses from a fixed range. Unmodulated pulses, about 200 ps wide, are emitted. A large number of reflected pulses are sampled and averaged. Background reflections are subtracted. Reflections from wall studs or other hidden objects are detected and displayed using light emitting diodes. 9 figs.

  1. Impulse radar studfinder

    DOEpatents

    McEwan, Thomas E.

    1995-01-01

    An impulse radar studfinder propagates electromagnetic pulses and detects reflected pulses from a fixed range. Unmodulated pulses, about 200 ps wide, are emitted. A large number of reflected pulses are sampled and averaged. Background reflections are subtracted. Reflections from wall studs or other hidden objects are detected and displayed using light emitting diodes.

  2. A Next Generation Radar Altimeter: The Proposed SWOT Mission

    NASA Astrophysics Data System (ADS)

    Fu, L. L.

    2014-12-01

    Conventional nadir-looking radar altimeter is based on pulse-limited footprint approach. Near a coast the pulse limited footprint is contaminated by land within the much larger radar footprint, causing data quality to decay within 10 km from a coast. In the open ocean, the instrument noise limits the detection of dynamic ocean signals to wavelengths longer than 70 km. Using the technique of radar interferometry, the proposed Surface Water and Ocean Topography (SWOT) Mission would reduce instrument noise to resolve ocean signals to 15 km in wavelength over most of the open ocean without land contamination in the coastal zone. Sea surface height would be measured in two dimensions over a swath 120 km wide across the satellite's flight path. SWOT is under development as a joint mission of NASA and the French Space Agency, CNES, with contributions from the Canadian Space Agency and the UK Space Agency. The launch is baselined for 2020. An overview of the projected mission performance for oceanographic applications will be presented. SWOT would also measure the elevation of land surface water with hydrological applications.

  3. Mercury's Global Topography from Radar Ranging Data

    NASA Technical Reports Server (NTRS)

    Anderson, J. D.; Schubert, G.; Asmar, S. W.; Jurgens, R. F.; Lau, E. L.; Moore, W. B.; Slade, M. A., III; Standish, E. M., Jr.

    2001-01-01

    When Mercury's radius is expanded in Legendre functions to the second degree and order, the systematic error in radar ranging data is reduced substantially. Previously, data spanning an observing interval from 1966 to 1990 were used to infer an equatorial ellipticity (a - b)/a = (540 +/- 54) X 10(exp -6) and a center-of-figure minus center-of-mass offset of (640 +/- 78) m. The magnitude of this equatorial center of figure offset implies an excess crustal thickness of 12 km or less, comparable to the Moon's excess. By comparing the equatorial ellipticity with the Mariner 10 gravity field, and assuming Airy isostatic compensation, bounds on crustal thickness can be derived. Mercury's crustal thickness is in the range from 100 to 300 km. The Mercury radar ranging observing interval has been extended from 1966 to the present. In addition, improvements in data reduction techniques have resulted in a set of Mercury ranging data less affected by systematic error, in particular the biases introduced by local topographic variations. We use this new set of reduced ranging data to improve Mercury's global topography and center-of-figure minus center-of-mass offset. New results on crustal thickness are derived, and prospects for further improvement with Mercury Orbiter data are discussed.

  4. Radar ''Sail'' satellite concept and design

    NASA Astrophysics Data System (ADS)

    Aguttes, Jean.-Paul; Sombrin, Jacques; Conde, Eric; Chaubet, Michel; Sebbag, Isabelle; Bousquet, Pierre

    2000-05-01

    The RADAR SAIL concept is based on the use of a rectangular antenna lying in the dawn-dusk orbital plane with the length (along speed vector) smaller than the height. Such geometry makes it possible to place the solar cells on the back of the antenna, to use gravity gradient stabilisation, and (optionally) to implement multipath-free GPS interferometric measurement of the antenna deformation thus allowing structural relaxation. Less obviously, the geometry favours the RADAR design too, by allowing grating lobes and therefore a lower density of built-in electronic in the active antenna. The antenna can be thin and packed for launch inside a cylinder-shaped bus having pyrotechnic doors for the antenna deployment and bearing the rest of the payload and the service equipment. With respect to a standard design of high performance missions, cost savings come from the bus, whose functions (AOCS, power supply) are simplified, from the launch since the mass budget and the stowing configuration become compatible with medium size rockets (LLV2/3, DELTA-LITE, LM-4…), and from the active antenna built-in electronics. Moreover, long satellite life-time can be achieved (10 years instead of 5). The RADAR SAIL concept is all the more cost effective when the mission requires a large, high and short antenna, i.e. high resolution (<5 m), low frequency band (L or S or even P), high revisiting, multiple frequencies. Mission implementation and funding can be favored by the new capability to share the satellite between autonomous regional operators. Combined with ground DBF (digital beam forming) technique, the concept allows extremely simple and low cost missions providing a fixed wide swath (10 to 15 m resolution within 500 km to 1000 km swath) for systematic surveillance or monitoring.

  5. Western Eisila Regio, Venus - Radar properties of volcanic deposits

    NASA Technical Reports Server (NTRS)

    Campbell, Bruce A.; Campbell, Donald B.

    1990-01-01

    The 1988 Arecibo Observatory dual-polarization radar images are presented for Western Eisila Regio, Venus. The polarization information and Pioneer-Venus Orbiter reflectivity and altimetry data are analyzed for volcanic deposits on two 400-500 km radius constructs, Sif and Gula Montes. Many of the large effusive deposits studied appear to require superposed flows or multiple vents to explain the observed progression of roughness along their length. High Fresnel reflectivity material may be present along the summit region of Gula Mons and in an embayed tessera-like region to the N. Radar-dark units on the flanks of Sif Mons are inferred to be pyroclastic deposits, but radar-dark features near the summits of both edifices are more consistent with very smooth lava flows. Higher spatial resolution Magellan data will be useful in testing these predictions.

  6. Western Eisila Regio, Venus - Radar properties of volcanic deposits

    NASA Astrophysics Data System (ADS)

    Campbell, Bruce A.; Campbell, Donald B.

    1990-08-01

    The 1988 Arecibo Observatory dual-polarization radar images are presented for Western Eisila Regio, Venus. The polarization information and Pioneer-Venus Orbiter reflectivity and altimetry data are analyzed for volcanic deposits on two 400-500 km radius constructs, Sif and Gula Montes. Many of the large effusive deposits studied appear to require superposed flows or multiple vents to explain the observed progression of roughness along their length. High Fresnel reflectivity material may be present along the summit region of Gula Mons and in an embayed tessera-like region to the N. Radar-dark units on the flanks of Sif Mons are inferred to be pyroclastic deposits, but radar-dark features near the summits of both edifices are more consistent with very smooth lava flows. Higher spatial resolution Magellan data will be useful in testing these predictions.

  7. Chatanika radar measurements of the electrical properties of auroral arcs

    NASA Astrophysics Data System (ADS)

    Vondrak, R. R.

    Ionospheric parameters measured in the presence of auroral arcs by the incoherent scatter Chatanika radar are used to define properties of the arcs. The radar broadcasts at 3-5 MW with a range resolution of 4.5 km along the radar line-of-sight, and has yielded auroral measurements on the variation of electron density, Hall and Pederson conductivity, horizontal electric fields, electrojet currents, precipitating electron energy flux, and the Joule heating rate. Elevation-scan techniques have been utilized to study the latitude and altitude variation of the ionospheric plasma parameters, and fixed-position scans allow determination of ionization conditions, including the electric fields and the acceleration of precipitating auroral electrons. Arcs in the diffuse aurora have been found to be local conductivity enhancements, while discrete arcs correspond to the boundary plasma sheet and have an asymmetric electric field pattern reduced on the northward side.

  8. High-frequency radar observations of ocean surface currents.

    PubMed

    Paduan, Jeffrey D; Washburn, Libe

    2013-01-01

    This article reviews the discovery, development, and use of high-frequency (HF) radio wave backscatter in oceanography. HF radars, as the instruments are commonly called, remotely measure ocean surface currents by exploiting a Bragg resonant backscatter phenomenon. Electromagnetic waves in the HF band (3-30 MHz) have wavelengths that are commensurate with wind-driven gravity waves on the ocean surface; the ocean waves whose wavelengths are exactly half as long as those of the broadcast radio waves are responsible for the resonant backscatter. Networks of HF radar systems are capable of mapping surface currents hourly out to ranges approaching 200 km with a horizontal resolution of a few kilometers. Such information has many uses, including search and rescue support and oil-spill mitigation in real time and larval population connectivity assessment when viewed over many years. Today, HF radar networks form the backbone of many ocean observing systems, and the data are assimilated into ocean circulation models.

  9. Ultra-wideband noise radar based on optical waveform generation

    NASA Astrophysics Data System (ADS)

    Grodensky, Daniel; Kravitz, Daniel; Zadok, Avi

    2012-06-01

    A microwave-photonic, ultra-wideband (UWB) noise radar system is proposed and demonstrated. The system brings together photonic generation of UWB waveforms and fiber-optic distribution. The use of UWB noise provides high ranging resolution and better immunity to interception and jamming. Distribution over fibers allows for the separation the radar-operating personnel and equipment from the location of the front-end. The noise waveforms are generated using the amplified spontaneous emission that is associated with stimulated Brillouin scattering in a standard optical fiber, or with an erbium-doped fiber amplifier. Our experiments demonstrate a proof of concept for an integrated radar system, driven by optically generated UWB noise waveforms of more than 1 GHz bandwidth that are distributed over 10 km distance. The detection of concealed metallic object and the resolving of two targets with the anticipated ranging resolution are reported.

  10. High resolution measurements of aerial rainfall with X-band radars in New Zealand

    NASA Astrophysics Data System (ADS)

    Sutherland-Stacey, Luke; Shucksmith, Paul; Austin, Geoff

    2010-05-01

    The Atmospheric Physics Group runs a number of high resolution X-band mobile rain radars. The radars are unusual in that they operate at very high spatial and temporal resolution but short range (100m/20sec/20km) as compared with the C-band radars of the New Zealand Meteorological Service (2km/7min/240km). Portability was a key design criterion for the radars, which can either be towed by a personal four wheel drive vehicle or carted by a container truck. Past deployments include the slopes of an erupting volcano, the path of a tropical storm and overwintering in a mountain range. It is well known that sampling and representativeness problems associated with sparse gauge networks and C-band radars can result in high uncertainty in estimates of aerial rainfall. Some of this error is associated with poor sampling of the spatial and temporal scales which are important to precipitation processes. In the case of long range radar, the beam height increase with range also introduces uncertainty when trying to infer precipitation at the ground, even after reflectivity profile correction methods are applied. This paper describes a recently completed field campaign in a hydro power catchment in the North Island of New Zealand. The radar was deployed in a pasture on a farm overlooking the catchment which is about 15km x 10km in size. The catchment is about 150km from the nearest national C-band radar. A number of rain gauges, including high resolution drop counters, were deployed nearby. X-band and comparative C-band radar observations of particular events including orographically initiated convection, frontal systems and widespread rain types are presented. The convective events are characterised by short length scales and rapid evolution, but even the widespread rain has embedded structure. The observations indicate that the evolution time and spatial scales associated with many of the hydrometeors observed in this work precludes aerial estimates being made with sparse

  11. Earth-based Radar Observations of Mercury: Imaging Results with the Upgraded Arecibo Radar

    NASA Astrophysics Data System (ADS)

    Harmon, J.

    With the completion of the Arecibo upgrade in 1998 came the opportunity to do Mercury radar imaging of unprecedented quality. Among the early results with the upgraded S-band radar was the delay-Doppler imaging of the north polar ice features at 1.5-km resolution (Harmon et al., 2001). These images provided accurate mapping of the putative ice deposits within shaded crater floors as well as a precise determination of the pole position. They also produced the surprising discovery of ice features in small craters and at relatively low latitudes, which places important constraints on thermal models. We are also planning imaging observations of the south pole as it returns to view in 2004 and subsequent years. Besides polar studies, an important component of the Arecibo program is full-disk radar imaging around the entire planet, with a special emphasis on the hemisphere left unimaged by Mariner 10. For this purpose we are conducting a program of delay-Doppler observations using the long-code method (Harmon, 2002), which produces cleaner images than conventional delay-Doppler. Most striking are the depolarized images, which are found to be dominated by bright features associated with fresh crater ejecta. These images show some spectacular rayed craters in the Tycho class, as well as numerous bright, rayless features from smaller impacts. Also visible are some diffuse albedo features with no obvious impact association. Some of these high-albedo patches are found in smooth plains regions such as Tolstoy basin and Tir Planitia, which is the reverse of the mare-highland contrast seen in radar images of the Moon. In addition to the imaging results, we will briefly review the major findings from the pre-upgrade radar altimetry measurements.

  12. Twisted light transmission over 143 km

    NASA Astrophysics Data System (ADS)

    Krenn, Mario; Handsteiner, Johannes; Fink, Matthias; Fickler, Robert; Ursin, Rupert; Malik, Mehul; Zeilinger, Anton

    2016-11-01

    Spatial modes of light can potentially carry a vast amount of information, making them promising candidates for both classical and quantum communication. However, the distribution of such modes over large distances remains difficult. Intermodal coupling complicates their use with common fibers, whereas free-space transmission is thought to be strongly influenced by atmospheric turbulence. Here, we show the transmission of orbital angular momentum modes of light over a distance of 143 km between two Canary Islands, which is 50× greater than the maximum distance achieved previously. As a demonstration of the transmission quality, we use superpositions of these modes to encode a short message. At the receiver, an artificial neural network is used for distinguishing between the different twisted light superpositions. The algorithm is able to identify different mode superpositions with an accuracy of more than 80% up to the third mode order and decode the transmitted message with an error rate of 8.33%. Using our data, we estimate that the distribution of orbital angular momentum entanglement over more than 100 km of free space is feasible. Moreover, the quality of our free-space link can be further improved by the use of state-of-the-art adaptive optics systems.

  13. 45-km horizontal path optical link demonstration

    NASA Astrophysics Data System (ADS)

    Biswas, Abhijit; Wright, Malcolm W.; Sanii, Babak; Page, Norman A.

    2001-06-01

    Observations made during a mountain-top-to-mountain-top horizontal optical link demonstration are described. The optical link spans a range of 46 Km at an average altitude of 2 Km above sea level. A multibeam beacon comprised of eight laser beams emerging from four multimode fiber coupled lasers (780 nm) is launched through a 0.6 m diameter telescope located at the JPL Table Mountain Facility (TMF) in Wrightwood, California. The multibeam beacon is received at Strawberry Peak located in the San Bernardino Mountains of California. The NASA, JPL developed optical communications demonstrator (OCD) receives the beacon, senses the atmospheric turbulence induced motion and using an upgraded fine steering loop actively points a communications laser beam (852 nm, 400 Mbps on-off key modulated, PN7 pseudo random bit sequence) to TMF. The eight-beam beacon allowed a four-fold reduction in normalized irradiance or scintillation index. This in turn was sufficient to eliminate beacon fades sensed by the OCD and enable performance evaluation of the fine steering loop. The residual tracking error was determined to be +/- 1.1 to +/- 1.7 (mu) rad compared to a model prediction of +/- 3.4 (mu) rad. The best link performance observed showed average bit error rates (BER) of 1E-5 over long durations (30 seconds); however, instantaneous BERs of at least 0.8E-6 over durations of 2 ms were observed. The paper also discusses results pertaining to atmospheric effects, link analysis, and overall performance.

  14. Twisted light transmission over 143 km.

    PubMed

    Krenn, Mario; Handsteiner, Johannes; Fink, Matthias; Fickler, Robert; Ursin, Rupert; Malik, Mehul; Zeilinger, Anton

    2016-11-29

    Spatial modes of light can potentially carry a vast amount of information, making them promising candidates for both classical and quantum communication. However, the distribution of such modes over large distances remains difficult. Intermodal coupling complicates their use with common fibers, whereas free-space transmission is thought to be strongly influenced by atmospheric turbulence. Here, we show the transmission of orbital angular momentum modes of light over a distance of 143 km between two Canary Islands, which is 50× greater than the maximum distance achieved previously. As a demonstration of the transmission quality, we use superpositions of these modes to encode a short message. At the receiver, an artificial neural network is used for distinguishing between the different twisted light superpositions. The algorithm is able to identify different mode superpositions with an accuracy of more than 80% up to the third mode order and decode the transmitted message with an error rate of 8.33%. Using our data, we estimate that the distribution of orbital angular momentum entanglement over more than 100 km of free space is feasible. Moreover, the quality of our free-space link can be further improved by the use of state-of-the-art adaptive optics systems.

  15. An MSK Radar Waveform

    NASA Technical Reports Server (NTRS)

    Quirk, Kevin J.; Srinivasan, Meera

    2012-01-01

    The minimum-shift-keying (MSK) radar waveform is formed by periodically extending a waveform that separately modulates the in-phase and quadrature- phase components of the carrier with offset pulse-shaped pseudo noise (PN) sequences. To generate this waveform, a pair of periodic PN sequences is each passed through a pulse-shaping filter with a half sinusoid impulse response. These shaped PN waveforms are then offset by half a chip time and are separately modulated on the in-phase and quadrature phase components of an RF carrier. This new radar waveform allows an increase in radar resolution without the need for additional spectrum. In addition, it provides self-interference suppression and configurable peak sidelobes. Compared strictly on the basis of the expressions for delay resolution, main-lobe bandwidth, effective Doppler bandwidth, and peak ambiguity sidelobe, it appears that bi-phase coded (BPC) outperforms the new MSK waveform. However, a radar waveform must meet certain constraints imposed by the transmission and reception of the modulation, as well as criteria dictated by the observation. In particular, the phase discontinuity of the BPC waveform presents a significant impediment to the achievement of finer resolutions in radar measurements a limitation that is overcome by using the continuous phase MSK waveform. The phase continuity, and the lower fractional out-of-band power of MSK, increases the allowable bandwidth compared with BPC, resulting in a factor of two increase in the range resolution of the radar. The MSK waveform also has been demonstrated to have an ambiguity sidelobe structure very similar to BPC, where the sidelobe levels can be decreased by increasing the length of the m-sequence used in its generation. This ability to set the peak sidelobe level is advantageous as it allows the system to be configured to a variety of targets, including those with a larger dynamic range. Other conventionally used waveforms that possess an even greater

  16. Radar observations of Asteroids 64 Angelina and 69 Hesperia

    NASA Astrophysics Data System (ADS)

    Shepard, Michael K.; Harris, Alan W.; Taylor, Patrick A.; Clark, Beth Ellen; Ockert-Bell, Maureen; Nolan, Michael C.; Howell, Ellen S.; Magri, Christopher; Giorgini, Jon D.; Benner, Lance A. M.

    2011-10-01

    We report new radar observations of E-class Asteroid 64 Angelina and M-class Asteroid 69 Hesperia obtained with the Arecibo Observatory S-band radar (2480 MHz, 12.6 cm). Our measurements of Angelina's radar bandwidth are consistent with reported diameters and poles. We find Angelina's circular polarization ratio to be 0.8 ± 0.1, tied with 434 Hungaria for the highest value observed for main-belt asteroids and consistent with the high values observed for all E-class asteroids (Benner, L.A.M., Ostro, S.J., Magri, C., Nolan, M.C., Howell, E.S., Giorgini, J.D., Jurgens, R.F., Margot, J.L., Taylor, P.A., Busch, M.W., Shepard, M.K. [2008]. Icarus 198, 294-304; Shepard, M.K., Kressler, K.M., Clark, B.E., Ockert-Bell, M.E., Nolan, M.C., Howell, E.S., Magri, C., Giorgini, J.D., Benner, L.A.M., Ostro, S.J. [2008b]. Icarus 195, 220-225). Our radar observations of 69 Hesperia, combined with lightcurve-based shape models, lead to a diameter estimate, Deff = 110 ± 15 km, approximately 20% smaller than the reported IRAS value. We estimate Hesperia to have a radar albedo of σ=0.45±0.12, consistent with a high-metal content. We therefore add 69 Hesperia to the Mm-class (high metal M) (Shepard, M.K., Clark, B.E., Ockert-Bell, M., Nolan, M.C., Howell, E.S., Magri, C., Giorgini, J.D., Benner, L.A.M., Ostro, S.J., Harris, A.W., Warner, B.D., Stephens, R.D., Mueller, M. [2010]. Icarus 208, 221-237), bringing the total number of Mm-class objects to eight; this is 40% of all M-class asteroids observed by radar to date.

  17. A comparison of airborne and ground-based radar observations with rain gages during the CaPE experiment

    NASA Technical Reports Server (NTRS)

    Satake, Makoto; Short, David A.; Iguchi, Toshio

    1992-01-01

    The vicinity of KSC, where the primary ground truth site of the Tropical Rainfall Measuring Mission (TRMM) program is located, was the focal point of the Convection and Precipitation/Electrification (CaPE) experiment in Jul. and Aug. 1991. In addition to several specialized radars, local coverage was provided by the C-band (5 cm) radar at Patrick AFB. Point measurements of rain rate were provided by tipping bucket rain gage networks. Besides these ground-based activities, airborne radar measurements with X- and Ka-band nadir-looking radars on board an aircraft were also recorded. A unique combination data set of airborne radar observations with ground-based observations was obtained in the summer convective rain regime of central Florida. We present a comparison of these data intending a preliminary validation. A convective rain event was observed simultaneously by all three instrument types on the evening of 27 Jul. 1991. The high resolution aircraft radar was flown over convective cells with tops exceeding 10 km and observed reflectivities of 40 to 50 dBZ at 4 to 5 km altitude, while the low resolution surface radar observed 35 to 55 dBZ echoes and a rain gage indicated maximum surface rain rates exceeding 100 mm/hr. The height profile of reflectivity measured with the airborne radar show an attenuation of 6.5 dB/km (two way) for X-band, corresponding to a rainfall rate of 95 mm/hr.

  18. 94 GHz doppler wind radar satellite mission concept

    NASA Astrophysics Data System (ADS)

    Lin, Chung-Chi; Rommen, Björn; Buck, Christopher; Schüttemeyer, Dirk

    2015-10-01

    Extreme weather such as storms, hurricanes and typhoons, also called `high impact weather', is a high priority area of research for the atmospheric dynamics and meteorological science communities. 94 GHz Doppler wind radar satellite mission concepts have been elaborated, which use cloud and precipitation droplets/particles as tracers to measure 3-D wind fields. The so-called polarisation-diversity pulse-pair (PDPP) technique enables to derive line-of-sight wind speed with good accuracy (< 2-3 m/s) and large unambiguous dynamic range (e.g. 75 m/s). Two distinct system concepts have been elaborated: (1) a conically scanning radar concept with large coverage (> 800 km) and ˜50 km along-track sampling, and; (2) a stereo viewing concept with high sampling resolution (< 4 km) within an inclined cut through the atmosphere. The former concept is adequate for studying large-scale severe/extreme weather systems, whereas the latter would be more suitable for understanding of small-scale convective phenomena. For demonstrating the potential of the FDPP technique for deriving accurate Doppler observations, ground-based and airborne Doppler radar campaigns are in preparation. The Galileo 94 GHz radar, upgraded recently to include a FDPP capability, at Chilbolton in the UK, will be used for an extended ground-based campaign (6 months). For the airborne campaign, the dual-frequency (9.4 + 94 GHz) NAWX radar on board a Convair-580 aircraft of the National Science Council of Canada will be upgraded and flown. This paper describes the observation requirements, preliminary satellite mission concepts, associated wind retrieval aspects and the planned demonstration campaigns.

  19. Radar observations and shape model of asteroid 16 Psyche

    NASA Astrophysics Data System (ADS)

    Shepard, Michael K.; Richardson, James; Taylor, Patrick A.; Rodriguez-Ford, Linda A.; Conrad, Al; de Pater, Imke; Adamkovics, Mate; de Kleer, Katherine; Males, Jared R.; Morzinski, Katie M.; Close, Laird M.; Kaasalainen, Mikko; Viikinkoski, Matti; Timerson, Bradley; Reddy, Vishnu; Magri, Christopher; Nolan, Michael C.; Howell, Ellen S.; Benner, Lance A. M.; Giorgini, Jon D.; Warner, Brian D.; Harris, Alan W.

    2017-01-01

    Using the S-band radar at Arecibo Observatory, we observed 16 Psyche, the largest M-class asteroid in the main belt. We obtained 18 radar imaging and 6 continuous wave runs in November and December 2015, and combined these with 16 continuous wave runs from 2005 and 6 recent adaptive-optics (AO) images (Drummond et al., 2016) to generate a three-dimensional shape model of Psyche. Our model is consistent with a previously published AO image (Hanus et al., 2013) and three multi-chord occultations. Our shape model has dimensions 279 × 232 × 189 km (± 10%), Deff = 226 ± 23 km, and is 6% larger than, but within the uncertainties of, the most recently published size and shape model generated from the inversion of lightcurves (Hanus et al., 2013). Psyche is roughly ellipsoidal but displays a mass-deficit over a region spanning 90° of longitude. There is also evidence for two ∼50-70 km wide depressions near its south pole. Our size and published masses lead to an overall bulk density estimate of 4500 ± 1400 kgm-3. Psyche's mean radar albedo of 0.37 ± 0.09 is consistent with a near-surface regolith composed largely of iron-nickel and ∼40% porosity. Its radar reflectivity varies by a factor of 1.6 as the asteroid rotates, suggesting global variations in metal abundance or bulk density in the near surface. The variations in radar albedo appear to correlate with large and small-scale shape features. Our size and Psyche's published absolute magnitude lead to an optical albedo of pv = 0.15 ± 0.03, and there is evidence for albedo variegations that correlate with shape features.

  20. Asteroid 16 Psyche: Radar Observations and Shape Model

    NASA Astrophysics Data System (ADS)

    Shepard, Michael K.; Richardson, James E.; Taylor, Patrick A.; Rodriguez-Ford, Linda A.; Conrad, Al; de Pater, Imke; Adamkovics, Mate; de Kleer, Katherine R.; Males, Jared; Morzinski, Kathleen M.; Miller Close, Laird; Kaasalainen, Mikko; Viikinkoski, Matti; Timerson, Bradley; Reddy, Vishnu; Magri, Christopher; Nolan, Michael C.; Howell, Ellen S.; Warner, Brian D.; Harris, Alan W.

    2016-10-01

    We observed 16 Psyche, the largest M-class asteroid in the main belt, using the S-band radar at Arecibo Observatory. We obtained 18 radar imaging and 6 continuous wave runs in November and December 2015, and combined these with 16 continuous wave runs from 2005 and 6 recent adaptive-optics (AO) images to generate a three-dimensional shape model of Psyche. Our model is consistent with a previously published AO image [Hanus et al. Icarus 226, 1045-1057, 2013] and three multi-chord occultations. Our shape model has dimensions 279 x 232 x 189 km (±10%), Deff = 226 ± 23 km, and is 6% larger than, but within the uncertainties of, the most recently published size and shape model generated from the inversion of lightcurves [Hanus et al., 2013]. Psyche is roughly ellipsoidal but displays a mass-deficit over a region spanning 90° of longitude. There is also evidence for two ~50-70 km wide depressions near its south pole. Our size and published masses lead to an overall bulk density estimate of 4500 ± 1400 kg m-3. Psyche's mean radar albedo of 0.37 ± 0.09 is consistent with a near-surface regolith composed largely of iron-nickel and ~40% porosity. Its radar reflectivity varies by a factor of 1.6 as the asteroid rotates, suggesting global variations in metal abundance or bulk density in the near surface. The variations in radar albedo appear to correlate with large and small-scale shape features. Our size and Psyche's published absolute magnitude lead to an optical albedo of pv = 0.15 ± 0.03, and there is evidence for albedo variegations that correlate with shape features.

  1. Bird Radar Validation in the Field by Time-Referencing Line-Transect Surveys

    PubMed Central

    Dokter, Adriaan M.; Baptist, Martin J.; Ens, Bruno J.; Krijgsveld, Karen L.; van Loon, E. Emiel

    2013-01-01

    Track-while-scan bird radars are widely used in ornithological studies, but often the precise detection capabilities of these systems are unknown. Quantification of radar performance is essential to avoid observational biases, which requires practical methods for validating a radar’s detection capability in specific field settings. In this study a method to quantify the detection capability of a bird radar is presented, as well a demonstration of this method in a case study. By time-referencing line-transect surveys, visually identified birds were automatically linked to individual tracks using their transect crossing time. Detection probabilities were determined as the fraction of the total set of visual observations that could be linked to radar tracks. To avoid ambiguities in assigning radar tracks to visual observations, the observer’s accuracy in determining a bird’s transect crossing time was taken into account. The accuracy was determined by examining the effect of a time lag applied to the visual observations on the number of matches found with radar tracks. Effects of flight altitude, distance, surface substrate and species size on the detection probability by the radar were quantified in a marine intertidal study area. Detection probability varied strongly with all these factors, as well as species-specific flight behaviour. The effective detection range for single birds flying at low altitude for an X-band marine radar based system was estimated at ∼1.5 km. Within this range the fraction of individual flying birds that were detected by the radar was 0.50±0.06 with a detection bias towards higher flight altitudes, larger birds and high tide situations. Besides radar validation, which we consider essential when quantification of bird numbers is important, our method of linking radar tracks to ground-truthed field observations can facilitate species-specific studies using surveillance radars. The methodology may prove equally useful for optimising

  2. Simultaneous optical and radar observations of meteor head-echoes utilizing SAAMER

    NASA Astrophysics Data System (ADS)

    Michell, R. G.; Janches, D.; Samara, M.; Hormaechea, J. L.; Brunini, C.; Bibbo, I.

    2015-12-01

    We present simultaneous optical and radar observations of meteors observed with the Southern Argentine Agile MEteor Radar (SAAMER). Although such observations were performed in the past using High Power and Large Aperture radars, the focus here is on meteors that produced head echoes that can be detected by a significantly less sensitive but more accessible radar system. An observational campaign was conducted in August of 2011, where an optical imager was operated near the radar site in Rio Grande, Tierra del Fuego, Argentina. Six head echo events out of 150 total detections were identified where simultaneous optical meteors could also be clearly seen within the main radar beam. The location of the meteors derived from the radar interferometry agreed very well with the optical location, verifying the accuracy of the radar interferometry technique. The meteor speeds and origin directions calculated from the radar data were accurate-compared with the optics-for the 2 meteors that had radar signal-to-noise ratios above 2.5. The optical meteors that produced the head echoes had horizontal velocities in the range of 29-91 km/s. These comparisons with optical observations improve the accuracy of the radar detection and analysis techniques, such that, when applied over longer periods of time, will improve the statistics of southern hemisphere meteor observations. Mass estimates were derived using both the optical and radar data and the resulting masses agreed well with each other. All were within an order of magnitude and in most cases, the agreement was within a factor of two.

  3. X-Band local area weather radar--preliminary calibration results.

    PubMed

    Jensen, N E

    2002-01-01

    DHI has developed a cost-effective X-Band Local Area Weather Radar (LAWR) with a typical range (radius) of 60 km, 500 x 500 m areal resolution and 253 reflection levels. The development is performed in a co-operation with a number of European partners, including Danish Meteorological Institute. The specifications of the weather radar and preliminary results from the calibration are presented. Good calibration results have been obtained using high-resolution rain gauges.

  4. Radar Target Recognition Using Bispectrum Correlation

    DTIC Science & Technology

    2007-06-01

    21 2. Inverse Synthetic Aperture Radar ...................................................22 3. Range Profiles...characteristics need to be stored. 2. Inverse Synthetic Aperture Radar We often identify things based on pictures and Synthetic Aperture Radar (SAR) is an...By taking multiple discrete measurements while translating the radar , a larger effective aperture can be created. Inverse Synthetic Aperture Radar

  5. 51. View of upper radar scanner switch in radar scanner ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    51. View of upper radar scanner switch in radar scanner building 105 from upper catwalk level showing emanating waveguides from upper switch (upper one-fourth of photograph) and emanating waveguides from lower radar scanner switch in vertical runs. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  6. Radar cross-sectional study using noise radar

    NASA Astrophysics Data System (ADS)

    Freundorfer, A. P.; Siddiqui, J. Y.; Antar, Y. M. M.

    2015-05-01

    A noise radar system is proposed with capabilities to measure and acquire the radar cross-section (RCS) of targets. The proposed system can cover a noise bandwidth of near DC to 50 GHz. The noise radar RCS measurements were conducted for selective targets like spheres and carpenter squares with and without dielectric bodies for a noise band of 400MHz-5000MHz. The bandwidth of operation was limited by the multiplier and the antennae used.

  7. 41. Perimeter acquisition radar building radar element and coaxial display, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    41. Perimeter acquisition radar building radar element and coaxial display, with drawing of typical antenna section. Drawing, from left to right, shows element, aluminum ground plane, cable connectors and hardware, cable, and back-up ring. Grey area is the concrete wall - Stanley R. Mickelsen Safeguard Complex, Perimeter Acquisition Radar Building, Limited Access Area, between Limited Access Patrol Road & Service Road A, Nekoma, Cavalier County, ND

  8. Kuiper Belt Mapping Radar

    NASA Technical Reports Server (NTRS)

    Freeman, A.; Nilsen, E.

    2001-01-01

    Since their initial discovery in 1992, to date only a relatively small number of Kuiper Belt Objects (KBO's) have been discovered. Current detection techniques rely on frame-to-frame comparisons of images collected by optical telescopes such as Hubble, to detect KBO's as they move against the background stellar field. Another technique involving studies of KBO's through occultation of known stars has been proposed. Such techniques are serendipitous, not systematic, and may lead to an inadequate understanding of the size, range, and distribution of KBO's. In this paper, a future Kuiper Belt Mapping Radar is proposed as a solution to the problem of mapping the size distribution, extent, and range of KBO's. This approach can also be used to recover radar albedo and object rotation rates. Additional information is contained in the original extended abstract.

  9. RADAR Reveals Titan Topography

    NASA Technical Reports Server (NTRS)

    Kirk, R. L.; Callahan, P.; Seu, R.; Lorenz, R. D.; Paganelli, F.; Lopes, R.; Elachi, C.

    2005-01-01

    The Cassini Titan RADAR Mapper is a K(sub u)-band (13.78 GHz, lambda = 2.17 cm) linear polarized RADAR instrument capable of operating in synthetic aperture (SAR), scatterometer, altimeter and radiometer modes. During the first targeted flyby of Titan on 26 October, 2004 (referred to as Ta) observations were made in all modes. Evidence for topographic relief based on the Ta altimetry and SAR data are presented here. Additional SAR and altimetry observations are planned for the T3 encounter on 15 February, 2005, but have not been carried out at this writing. Results from the T3 encounter relevant to topography will be included in our presentation. Data obtained in the Ta encounter include a SAR image swath

  10. Floor-plan radar

    NASA Astrophysics Data System (ADS)

    Falconer, David G.; Ueberschaer, Ronald M.

    2000-07-01

    Urban-warfare specialists, law-enforcement officers, counter-drug agents, and counter-terrorism experts encounter operational situations where they must assault a target building and capture or rescue its occupants. To minimize potential casualties, the assault team needs a picture of the building's interior and a copy of its floor plan. With this need in mind, we constructed a scale model of a single- story house and imaged its interior using synthetic-aperture techniques. The interior and exterior walls nearest the radar set were imaged with good fidelity, but the distal ones appear poorly defined and surrounded by ghosts and artifacts. The latter defects are traceable to beam attenuation, wavefront distortion, multiple scattering, traveling waves, resonance phenomena, and other effects not accounted for in the traditional (noninteracting, isotropic point scatterer) model for radar imaging.

  11. Predicting km-scale shear zone formation

    NASA Astrophysics Data System (ADS)

    Gerbi, Christopher; Culshaw, Nicholas; Shulman, Deborah; Foley, Maura; Marsh, Jeffrey

    2015-04-01

    Because km-scale shear zones play a first-order role in lithospheric kinematics, accurate conceptual and numerical models of orogenic development require predicting when and where they form. Although a strain-based algorithm in the upper crust for weakening due to faulting appears to succeed (e.g., Koons et al., 2010, doi:10.1029/2009TC002463), a comparable general rule for the viscous crust remains unestablished. Here we consider two aspects of the geological argument for a similar algorithm in the viscous regime, namely (1) whether predicting km-scale shear zone development based on a single parameter (such as strain or shear heating) is reasonable; and (2) whether lithologic variability inherent in most orogenic systems precludes a simple predictive rule. A review of tectonically significant shear zones worldwide and more detailed investigations in the Central Gneiss belt of the Ontario segment of the Grenville Province reveals that most km-scale shear zones occur at lithological boundaries and involve mass transfer, but have fairly little else in common. As examples, the relatively flat-lying Twelve Mile Bay shear zone in the western Central Gneiss belt bounds the Parry Sound domain and is likely the product of both localized anatexis and later retrograde hydration with attendant metamorphism. Moderately dipping shear zones in granitoids of the Grenville Front Tectonic Zone apparently resulted from cooperation among several complementary microstructural processes, such as grain size reduction, enhanced diffusion, and a small degree of metamorphic reaction. Localization into shear zones requires the operation of some spatially restricted processes such as stress concentration, metamorphism/fluid access, textural evolution, and thermal perturbation. All of these could be due in part to strain, but not necessarily linearly related to strain. Stress concentrations, such as those that form at rheological boundaries, may be sufficient to nucleate high strain

  12. Magellan radar to reveal secrets of enshrouded Venus

    NASA Technical Reports Server (NTRS)

    Saunders, R. Stephen

    1990-01-01

    Imaging Venus with a synthetic aperture radar (SAR) with 70 percent global coverage at 1-km optical line-pair resolution to provide a detailed global characterization of the volcanic land-forms on Venus by an integration of image data with altimetry is discussed. The Magellan radar system uses navigation predictions to preset the radar data collection parameters. The data are collected in such a way as to preserve the Doppler signature of surface elements and later they are transmitted to the earth for processing into high-resolution radar images. To maintain high accuracy, a complex on-board filter algorithm allows the altitude control logic to respond only to a narrow range of expected photon intensity levels and only to signals that occur within a small predicted interval of time. Each mapping pass images a swath of the planet that varies in width from 20 to 25 km. Since the orbital plane of the spacecraft remains fixed in the inertial space, the slow rotation of Venus continually brings new areas into view of the spacecraft.

  13. Magellan radar to reveal secrets of enshrouded Venus

    NASA Astrophysics Data System (ADS)

    Saunders, R. Stephen

    1990-09-01

    Imaging Venus with a synthetic aperture radar (SAR) with 70 percent global coverage at 1-km optical line-pair resolution to provide a detailed global characterization of the volcanic land-forms on Venus by an integration of image data with altimetry is discussed. The Magellan radar system uses navigation predictions to preset the radar data collection parameters. The data are collected in such a way as to preserve the Doppler signature of surface elements and later they are transmitted to the earth for processing into high-resolution radar images. To maintain high accuracy, a complex on-board filter algorithm allows the altitude control logic to respond only to a narrow range of expected photon intensity levels and only to signals that occur within a small predicted interval of time. Each mapping pass images a swath of the planet that varies in width from 20 to 25 km. Since the orbital plane of the spacecraft remains fixed in the inertial space, the slow rotation of Venus continually brings new areas into view of the spacecraft.

  14. Spaceborne Radar Study

    DTIC Science & Technology

    1974-06-28

    If comm beam contact is lost, the instrumentation data are sent via the omnichannel transmitter on command of the ground station. There are six ways...comm’beam) at all times except when comm beam contact is lost. A two-way omnidirectional (backup) command link is provided for initial stabilization...via either the oomm beam or the omnichannel . Satellite instrumentation data are sent to the ground station following every radar signal transmission

  15. Shuttle imaging radar experiment

    USGS Publications Warehouse

    Elachi, C.; Brown, W.E.; Cimino, J.B.; Dixon, T.; Evans, D.L.; Ford, J.P.; Saunders, R.S.; Breed, C.; Masursky, H.; McCauley, J.F.; Schaber, G.; Dellwig, L.; England, A.; MacDonald, H.; Martin-Kaye, P.; Sabins, F.

    1982-01-01

    The shuttle imaging radar (SIR-A) acquired images of a variety of the earth's geologic areas covering about 10 million square kilometers. Structural and geomorphic features such as faults, folds, outcrops, and dunes are clearly visible in both tropical and arid regions. The combination of SIR-A and Seasat images provides additional information about the surface physical properties: topography and roughness. Ocean features were also observed, including large internal waves in the Andaman Sea. Copyright ?? 1982 AAAS.

  16. Weather Radar Studies.

    DTIC Science & Technology

    2014-09-26

    and Doppler weather radar data from the National Center for Atmospheric Research JAWS program and the National .Severe Storms Laboratory, are being...Atmospheric Research JAWS program and the National Severe Storms Laboratory, are being analyzed to develop low-altitude wind-shear detection algorithms...pictures, and dusted for fingerprints. The wind sensors, rain gauge, and antenna were destroyed but the DCP, solar panel, and other site components

  17. The Radar Roadmap

    DTIC Science & Technology

    2013-01-01

    LIMITATION OF ABSTRACT Same as Report ( SAR ) 18. NUMBER OF PAGES 25 19a. NAME OF RESPONSIBLE PERSON a. REPORT unclassified b. ABSTRACT unclassified c...ABSTRACT Same as Report ( SAR ) 18. NUMBER OF PAGES 25 19a. NAME OF RESPONSIBLE PERSON a. REPORT unclassified b. ABSTRACT unclassified c. THIS PAGE...object bistatic radars. The former allows high resolution without the use of pulse compression techniques and the latter promises cheaper systems by

  18. Imaging synthetic aperture radar

    DOEpatents

    Burns, Bryan L.; Cordaro, J. Thomas

    1997-01-01

    A linear-FM SAR imaging radar method and apparatus to produce a real-time image by first arranging the returned signals into a plurality of subaperture arrays, the columns of each subaperture array having samples of dechirped baseband pulses, and further including a processing of each subaperture array to obtain coarse-resolution in azimuth, then fine-resolution in range, and lastly, to combine the processed subapertures to obtain the final fine-resolution in azimuth. Greater efficiency is achieved because both the transmitted signal and a local oscillator signal mixed with the returned signal can be varied on a pulse-to-pulse basis as a function of radar motion. Moreover, a novel circuit can adjust the sampling location and the A/D sample rate of the combined dechirped baseband signal which greatly reduces processing time and hardware. The processing steps include implementing a window function, stabilizing either a central reference point and/or all other points of a subaperture with respect to doppler frequency and/or range as a function of radar motion, sorting and compressing the signals using a standard fourier transforms. The stabilization of each processing part is accomplished with vector multiplication using waveforms generated as a function of radar motion wherein these waveforms may be synthesized in integrated circuits. Stabilization of range migration as a function of doppler frequency by simple vector multiplication is a particularly useful feature of the invention; as is stabilization of azimuth migration by correcting for spatially varying phase errors prior to the application of an autofocus process.

  19. Goldstone solar system radar

    NASA Technical Reports Server (NTRS)

    Jurgens, Raymond F.

    1991-01-01

    Caltech/Jet Propulsion Laboratory (JPL) radar astronomers made use of the Very Large Array (VLA) at Socorro, NM, during February 1990, to receive radio echoes from the planet Venus. The transmitter was the 70 meter antenna at the Goldstone complex northwest of Barstow, CA. These observations contain new information about the roughness of Venus at cm to decimeter scales and are complementary to information being obtained by the Magellan spacecraft. Asteroid observations are also discussed.

  20. Cognitive Nonlinear Radar

    DTIC Science & Technology

    2013-01-01

    Devices and Method for Detecting Emplacement of Improvised Explosive Devices, U. S. Patent 7,680,599, Mar. 16, 2010. 11. Steele, D.; Rotondo, F.; Houck...Patent 7,987,068, Jul. 26, 2011. 9 14. Keller, W. Active Improvised Explosive Device (IED) Electronic Signature Detection , U. S. Patent...operate without interfering with each other. The CNR uses a narrowband, nonlinear radar target detection methodology. This methodology has the advantage

  1. Weather Radar Studies.

    DTIC Science & Technology

    1985-03-31

    National Center for Atmospheric Research JAWS program and the National Severe Storms Laboratory are being analyzed to develop low-altitude wind shear...public through low-altitude wind shear aviation weather products the National Technical Information Service, NEXR I turbulence., Springfield, VA 22161. 19...were analyzed preliminarily to determine wind shear characteristics in the Memphis area. Doppler weather radar data from the National Center for

  2. Mineral equilibria and the high radar reflectivity of Venus mountaintops

    NASA Technical Reports Server (NTRS)

    Klose, K. B.; Wood, J. A.; Hashimoto, A.

    1992-01-01

    The relationship between altitude and microwave emissivity in 10 highland regions of Venus is investigated on the basis of the Magellan data set. Highlands on Venus are found to display high radar reflectivity. The required change in surface electrical properties occurs abruptly at a 'critical altitude,' whose value varies from one highland area to another. Critical altitudes range from 4.75 km to 2.49 km. Differences in reflectivity are caused by differences in the surface mineral assemblage, which determines the dielectric constant of surface material. The mineral responsible for high radar reflectivity on mountaintops is pyrite, which occurs in weathered mineral assemblages at high altitudes. Conductive pyrite occurs dispersed in insulating materials, forming a loaded dielectric material.

  3. Radar clutter classification

    NASA Astrophysics Data System (ADS)

    Stehwien, Wolfgang

    1989-11-01

    The problem of classifying radar clutter as found on air traffic control radar systems is studied. An algorithm based on Bayes decision theory and the parametric maximum a posteriori probability classifier is developed to perform this classification automatically. This classifier employs a quadratic discriminant function and is optimum for feature vectors that are distributed according to the multivariate normal density. Separable clutter classes are most likely to arise from the analysis of the Doppler spectrum. Specifically, a feature set based on the complex reflection coefficients of the lattice prediction error filter is proposed. The classifier is tested using data recorded from L-band air traffic control radars. The Doppler spectra of these data are examined; the properties of the feature set computed using these data are studied in terms of both the marginal and multivariate statistics. Several strategies involving different numbers of features, class assignments, and data set pretesting according to Doppler frequency and signal to noise ratio were evaluated before settling on a workable algorithm. Final results are presented in terms of experimental misclassification rates and simulated and classified plane position indicator displays.

  4. Radar gun hazards

    SciTech Connect

    Not Available

    1991-12-20

    Radar guns - hand-held units used by the law to nail speeders - have been in use since the early '60s. Now they've been accused of causing cancer. Police officers in several states have so far filed eight suits against the manufacturer, claiming that they have contracted rare forms of cancer, such as of the eyelid and the testicle, from frequent proximity to the devices. Spurred by concerns expressed by police groups, researchers at the Rochester Institute of Technology are conducting what they believe to be the first research of its kind in the nation. Last month psychologist John Violanti, an expert in policy psychology and health, sent out a one-page survey to 6,000 active and retired police officers in New York State, asking them about their health and their use of radar guns. Violanti says melanoma, leukemia, and lymph node cancer may be linked to these as well as other electromagnetic devices. The Food and Drug Administration earlier this year issued a warning about radar guns, telling users not to operate them closer than 6 inches from the body. But this may not be a sufficient safeguard since the instruments can give off crisscrossing wave emissions within a police vehicle. The survey will be used to help determine if it would be safer to mount the guns, which are currently either hand-held or mounted on dashboards, outside troopers' cars.

  5. Nordic Snow Radar Experiment

    NASA Astrophysics Data System (ADS)

    Lemmetyinen, Juha; Kontu, Anna; Pulliainen, Jouni; Vehviläinen, Juho; Rautiainen, Kimmo; Wiesmann, Andreas; Mätzler, Christian; Werner, Charles; Rott, Helmut; Nagler, Thomas; Schneebeli, Martin; Proksch, Martin; Schüttemeyer, Dirk; Kern, Michael; Davidson, Malcolm W. J.

    2016-09-01

    The objective of the Nordic Snow Radar Experiment (NoSREx) campaign was to provide a continuous time series of active and passive microwave observations of snow cover at a representative location of the Arctic boreal forest area, covering a whole winter season. The activity was a part of Phase A studies for the ESA Earth Explorer 7 candidate mission CoReH2O (Cold Regions Hydrology High-resolution Observatory). The NoSREx campaign, conducted at the Finnish Meteorological Institute Arctic Research Centre (FMI-ARC) in Sodankylä, Finland, hosted a frequency scanning scatterometer operating at frequencies from X- to Ku-band. The radar observations were complemented by a microwave dual-polarization radiometer system operating from X- to W-bands. In situ measurements consisted of manual snow pit measurements at the main test site as well as extensive automated measurements on snow, ground and meteorological parameters. This study provides a summary of the obtained data, detailing measurement protocols for each microwave instrument and in situ reference data. A first analysis of the microwave signatures against snow parameters is given, also comparing observed radar backscattering and microwave emission to predictions of an active/passive forward model. All data, including the raw data observations, are available for research purposes through the European Space Agency and the Finnish Meteorological Institute. A consolidated dataset of observations, comprising the key microwave and in situ observations, is provided through the ESA campaign data portal to enable easy access to the data.

  6. Sensitivity of Radar Wave Propagation Power to the Marine Atmospheric Boundary Layer

    NASA Astrophysics Data System (ADS)

    Lentini, N.; Hackett, E. E.

    2014-12-01

    Radar is a remote sensor used for scientific, meteorological, and military applications. Radar waves are affected by the medium through which they propagate, impacting the accuracy of radar measurements. Thus, environmental effects should be understood and quantified. The marine atmospheric boundary layer (MABL) is highly dynamic and turbulent, and affects radar wave propagation. The ocean surface roughness impacts scattering behavior. These effects cause variability in constructive and destructive interference patterns due to reflection from the ocean surface, known as multipath. The atmospheric effects cause radar waves to attenuate and refract; this study focuses on the refractive effects. A high-fidelity, physics-based, parabolic wave equation simulation is used to model the radar propagation and accounts for effects of the rough ocean surface (wind seas and swell) as well as variable refractivity with height and range. We use a robust, variance based, sensitivity analysis method called the Extended Fourier Amplitude Sensitivity Test to quantify which environmental parameters have the most significant effect on the modeled radar wave propagation. In this sensitivity study, the environment is parameterized by 16 variables, 8 ocean surface and 8 atmospheric. Sensitivity analysis is performed for 3 radar frequencies (3, 9, and 15 GHz) and 2 polarizations (horizontal and vertical). Results indicate that radar wave propagation is more sensitive to atmospheric parameters than ocean surface parameters. The mixed layer has the most far-reaching effect over the entire model domain (a range of 60 km and altitudes up to 1 km), characterized by its height and refractivity gradient. The remaining important factors have a predominantly local effect in the region where they occur in the MABL atmospheric structure. At low altitudes, radar wave propagation power is most sensitive to the gradient and curvature of the vertical refractivity profile. This research provides insight

  7. Optical-network-connected multi-channel 96-GHz-band distributed radar system

    NASA Astrophysics Data System (ADS)

    Kanno, Atsushi; Kuri, Toshiaki; Kawanishi, Tetsuya

    2015-05-01

    The millimeter-wave (MMW) radar is a promising candidate for high-precision imaging because of its short wavelength and broad range of available bandwidths. In particular in the frequency range of 92-100 GHz, which is regulated for radiolocation, an atmospheric attenuation coefficient less than 1 dB/km limits the imaging range. Therefore, a combination of MMW radar and distributed antenna system directly connected to optical fiber networks can realize both high-precision imaging and large-area surveillance. In this paper, we demonstrate a multi-channel MMW frequency-modulated continuous-wave distributed radar system connected to an analog radio-over-fiber network.

  8. Polarisation Radar Studies of Precipitation: Implementation of the Technique and Data Interpretation

    DTIC Science & Technology

    1990-07-25

    radar echo q’i c ls reached only 5km (slightly above the freezing level), but during this time values of ZDR in Figure 2. A vertical scan on 20 June 1980...Chilbolton radar does not support this view. Values of ZDR of up to 9dB have been observed in the bright band and are thought to result from melting...Brandes E A (1979) Radar measurements of rainfall - a summary. Bull Am Met Soc, 60, 1048-1058 TABLE 1 P-P shapes B & C shapes Size Axial ZDR (dB) Axial ZDR

  9. High-resolution instrumentation radar

    NASA Astrophysics Data System (ADS)

    Dydbal, Robert B.; Hurlbut, Keith H.; Mori, Tsutomu T.

    1987-03-01

    An instrumentation radar that uses a chirp waveform to achieve high-range resolution is described. High-range-resolution instrumentation radars evaluate the target response to operational waveforms used in high-performance radars and/or obtain a display of the individual target scattering mechanisms to better understand the scattering process. This particular radar was efficiently constructed from a combination of commercially available components and in-house fabricated circuitry. This instrumentation radar operates at X-band and achieves a 4.9-in-range resolution. A key feature of the radar is the combination of amplitude weighting with a high degree of waveform fidelity to achieve a very good range sidelobe performance. This range sidelobe performance is important to avoid masking lower level target returns in the range sidelobes of higher target returns.

  10. Comparing Goldstone Solar System Radar Earth-based Observations of Mars with Orbital Datasets

    NASA Technical Reports Server (NTRS)

    Haldemann, A. F. C.; Larsen, K. W.; Jurgens, R. F.; Slade, M. A.

    2005-01-01

    The Goldstone Solar System Radar (GSSR) has collected a self-consistent set of delay-Doppler near-nadir radar echo data from Mars since 1988. Prior to the Mars Global Surveyor (MGS) Mars Orbiter Laser Altimeter (MOLA) global topography for Mars, these radar data provided local elevation information, along with radar scattering information with global coverage. Two kinds of GSSR Mars delay-Doppler data exist: low 5 km x 150 km resolution and, more recently, high (5 to 10 km) spatial resolution. Radar data, and non-imaging delay-Doppler data in particular, requires significant data processing to extract elevation, reflectivity and roughness of the reflecting surface. Interpretation of these parameters, while limited by the complexities of electromagnetic scattering, provide information directly relevant to geophysical and geomorphic analyses of Mars. In this presentation we want to demonstrate how to compare GSSR delay-Doppler data to other Mars datasets, including some idiosyncracies of the radar data. Additional information is included in the original extended abstract.

  11. Radar scattering properties of steep-sided domes on Venus

    NASA Technical Reports Server (NTRS)

    Ford, Peter G.

    1994-01-01

    More than 100 quasi-circular steep-sided volcanic domes, with diameters ranging from 6 to 60 km, have been observed on the surface of Venus by the Magellan radar mapper. Assuming that they have the shape of a solidified high-viscosity Newtonian fluid, their radar scattering properties can be studied in detail from Magellan images, since a typical radar swath resolves each dome into several tens of thousands of measurements of radar cross section at incidence angles varying fom 15 deg to 55 deg. Through examination of 20 domes in detail, it appears that many of those situated on lava plains scatter radar in a manner that is indistinguishable from that of the surrounding material, suggesting that either (1) they were formed of a relatively high-density high-viscosity material, e.g., andesite, rather than a lower-density one, e.g., rhyolite or dacite; or (2) that their surfaces share a common origin with those of their surroundings, e.g., through in situ weathering or aeolian deposition.

  12. Radar and satellite observations of the storm time cleft

    SciTech Connect

    Yeh, H.C.; Foster, J.C.; Holt, J.M.; Redus, R.H.; Rich, F.J.

    1990-08-01

    During the magnetic storm of February 8-9, 1986, the region of strong ion convection in the vicinity of the dayside cusp expanded equatorward into the field of view of the Millstone Hill radar at lower mid-latitudes. High-speed (>1.5 km/s) poleward ion flows were found at latitudes as low as 60 deg invariant latitude, at least 10 deg lower than the typical cleft/cusp position for moderately disturbed (Kp>4) magnetospheric conditions. The ion velocity pattern responded promptly to changes in the interplanetary magnetic field By direction. The large-scale two-dimensional convection pattern across the dayside was well resolved using radar azimuth scan data at Millstone Hill, thus enabling us to place the fine-scale radar/satellite observations of the storm time cusp and cleft in the context of the large-scale pattern. We present a detailed comparison of radar and DMSP F7 satellite observations in the prenoon sector during a period of Kp > 7, to examine the low-altitude signatures of various plasma regions in the vicinity of the cusp. The combination of particle precipitation, magnetic field perturbation, radar measurements of ion heating, and convection consistently suggests the unusual low-latitude position of cusp at 65 invariant latitude.

  13. A method for estimating the height of a mesospheric density level using meteor radar

    NASA Astrophysics Data System (ADS)

    Younger, J. P.; Reid, I. M.; Vincent, R. A.; Murphy, D. J.

    2015-07-01

    A new technique for determining the height of a constant density surface at altitudes of 78-85 km is presented. The first results are derived from a decade of observations by a meteor radar located at Davis Station in Antarctica and are compared with observations from the Microwave Limb Sounder instrument aboard the Aura satellite. The density of the neutral atmosphere in the mesosphere/lower thermosphere region around 70-110 km is an essential parameter for interpreting airglow-derived atmospheric temperatures, planning atmospheric entry maneuvers of returning spacecraft, and understanding the response of climate to different stimuli. This region is not well characterized, however, due to inaccessibility combined with a lack of consistent strong atmospheric radar scattering mechanisms. Recent advances in the analysis of detection records from high-performance meteor radars provide new opportunities to obtain atmospheric density estimates at high time resolutions in the MLT region using the durations and heights of faint radar echoes from meteor trails. Previous studies have indicated that the expected increase in underdense meteor radar echo decay times with decreasing altitude is reversed in the lower part of the meteor ablation region due to the neutralization of meteor plasma. The height at which the gradient of meteor echo decay times reverses is found to occur at a fixed atmospheric density. Thus, the gradient reversal height of meteor radar diffusion coefficient profiles can be used to infer the height of a constant density level, enabling the observation of mesospheric density variations using meteor radar.

  14. Coherent Doppler Laser Radar: Technology Development and Applications

    NASA Technical Reports Server (NTRS)

    Kavaya, Michael J.; Arnold, James E. (Technical Monitor)

    2000-01-01

    NASA's Marshall Space Flight Center has been investigating, developing, and applying coherent Doppler laser radar technology for over 30 years. These efforts have included the first wind measurement in 1967, the first airborne flights in 1972, the first airborne wind field mapping in 1981, and the first measurement of hurricane eyewall winds in 1998. A parallel effort at MSFC since 1982 has been the study, modeling and technology development for a space-based global wind measurement system. These endeavors to date have resulted in compact, robust, eyesafe lidars at 2 micron wavelength based on solid-state laser technology; in a factor of 6 volume reduction in near diffraction limited, space-qualifiable telescopes; in sophisticated airborne scanners with full platform motion subtraction; in local oscillator lasers capable of rapid tuning of 25 GHz for removal of relative laser radar to target velocities over a 25 km/s range; in performance prediction theory and simulations that have been validated experimentally; and in extensive field campaign experience. We have also begun efforts to dramatically improve the fundamental photon efficiency of the laser radar, to demonstrate advanced lower mass laser radar telescopes and scanners; to develop laser and laser radar system alignment maintenance technologies; and to greatly improve the electrical efficiency, cooling technique, and robustness of the pulsed laser. This coherent Doppler laser radar technology is suitable for high resolution, high accuracy wind mapping; for aerosol and cloud measurement; for Differential Absorption Lidar (DIAL) measurements of atmospheric and trace gases; for hard target range and velocity measurement; and for hard target vibration spectra measurement. It is also suitable for a number of aircraft operations applications such as clear air turbulence (CAT) detection; dangerous wind shear (microburst) detection; airspeed, angle of attack, and sideslip measurement; and fuel savings through

  15. A 449 MHz modular wind profiler radar system

    NASA Astrophysics Data System (ADS)

    Lindseth, Bradley James

    This thesis presents the design of a 449 MHz radar for wind profiling, with a focus on modularity, antenna sidelobe reduction, and solid-state transmitter design. It is one of the first wind profiler radars to use low-cost LDMOS power amplifiers combined with spaced antennas. The system is portable and designed for 2-3 month deployments. The transmitter power amplifier consists of multiple 1-kW peak power modules which feed 54 antenna elements arranged in a hexagonal array, scalable directly to 126 elements. The power amplifier is operated in pulsed mode with a 10% duty cycle at 63% drain efficiency. The antenna array is designed to have low sidelobes, confirmed by measurements. The radar was operated in Boulder, Colorado and Salt Lake City, Utah. Atmospheric wind vertical and horizontal components at altitudes between 200m and 4km were calculated from the collected atmospheric return signals. Sidelobe reduction of the antenna array pattern is explored to reduce the effects of ground or sea clutter. Simulations are performed for various shapes of compact clutter fences for the 915-MHz beam-steering Doppler radar and the 449-MHz spaced antenna interferometric radar. It is shown that minimal low-cost hardware modifications to existing compact ground planes of 915-MHz beam-steering radar allow for reduction of sidelobes of up to 5dB. The results obtained on a single beam-steering array are extended to the 449 MHz triple hexagonal array spaced antenna interferometric radar. Cross-correlation, transmit beamwidth, and sidelobe levels are evaluated for various clutter fence configurations and array spacings. The resulting sidelobes are as much as 10 dB below those without a clutter fence and can be incorporated into existing and future 915 and 449 MHz wind profiler systems with minimal hardware modifications.

  16. Studies of high latitude mesospheric turbulence by radar and rocket. II - Measurements of small scale turbulence

    NASA Technical Reports Server (NTRS)

    Blood, S. P.; Mitchell, J. D.; Croskey, C. L.; Raymund, T. D.; Thrane, E. V.; Blix, T. A.; Hoppe, U. P.; Fritts, D. C.; Schmidlin, F. J.

    1988-01-01

    Measurements of mesospheric small scale turbulence and associated larger scale wave structures were obtained from rocket probe flights during equinox in spring 1985. The measurements were verified by data from the mesosphere-stratosphere-troposphere radar at Poker Flat, Alaska. Electron density irregularities down to an altitude of about 62 km and fluctuations in positive ion density in the altitude region from 50 to 90 km were measured. Turbulence in the inertial subrange was observed at heights where the fluctuations generally were largest. Measurement of background electron density exhibited gradients relative to the monotonically increasing density profile, suggesting the presence of large amplitude wave motions transporting the plasma by mixing. The radar detected the occurrence of 1-3 km wavelike perturbations superimposed on a 7-km wave in the wind velocity field. It is suggested that the 1-3 km waves are more important in the transport of energy and momentum and in the production of turbulence in the lower mesosphere.

  17. Comparison of rain gauge and radar data as input to an urban rainfall-runoff model.

    PubMed

    Quirmbach, M; Schultz, G A

    2002-01-01

    This paper presents an application of radar data (DX-product of the German Weather Service) with a high resolution in space (1 degree x 1 km) and time (delta t = 5 minutes) in urban hydrology. The radar data and data of rain gauges with different locations in the test catchment were compared concerning their suitability as input into an urban rainfall-runoff model. In order to evaluate the accuracy of model simulation results, five evaluation criteria have been specified which are relevant for an efficient management of sewer systems and wastewater treatment plants. The results demonstrate that radar data should be used in urban hydrology if distances > 4 km between rain gauge and catchment exist and for catchments with a density of rain gauges smaller than 1 rain gauge per 16 km2.

  18. Radar-aeolian roughness project

    NASA Technical Reports Server (NTRS)

    Greeley, Ronald; Dobrovolskis, A.; Gaddis, L.; Iversen, J. D.; Lancaster, N.; Leach, Rodman N.; Rasnussen, K.; Saunders, S.; Vanzyl, J.; Wall, S.

    1991-01-01

    The objective is to establish an empirical relationship between measurements of radar, aeolian, and surface roughness on a variety of natural surfaces and to understand the underlying physical causes. This relationship will form the basis for developing a predictive equation to derive aeolian roughness from radar backscatter. Results are given from investigations carried out in 1989 on the principal elements of the project, with separate sections on field studies, radar data analysis, laboratory simulations, and development of theory for planetary applications.

  19. Radar studies of bird migration

    NASA Technical Reports Server (NTRS)

    Williams, T. C.; Williams, J. M.

    1974-01-01

    Observations of bird migration with NASA radars were made at Wallops Island, Va. Simultaneous observations were made at a number of radar sites in the North Atlantic Ocean in an effort to discover what happened to those birds that were observed leaving the coast of North America headed toward Bermuda, the Caribbean and South America. Transatlantic migration, utilizing observations from a large number of radars is discussed. Detailed studies of bird movements at Wallops Island are presented.

  20. Radar Studies of Aviation Hazards

    DTIC Science & Technology

    1994-05-31

    4. TITLE AND SURTITLE S. FUNDING NUMBERS RADAR STUDIES OF AVIATION HAZARDS F1 9628-93- C -0054 _____________ __PE63707F 6. AUTHOR(S) PR278 1...foilowing processing steps have been adopted: a. acquire single scan radar data, b. distinguish individual storms, c . eliminate spurious data for...occurred only with radar reflectivities above 40 dBZ at the -10° C level and cloud tops above the -200C level. Lightning occurred only when tops extended

  1. Radar Image, Hokkaido, Japan

    NASA Technical Reports Server (NTRS)

    2000-01-01

    The southeast part of the island of Hokkaido, Japan, is an area dominated by volcanoes and volcanic caldera. The active Usu Volcano is at the lower right edge of the circular Lake Toya-Ko and near the center of the image. The prominent cone above and to the left of the lake is Yotei Volcano with its summit crater. The city of Sapporo lies at the base of the mountains at the top of the image and the town of Yoichi -- the hometown of SRTM astronaut Mamoru Mohri -- is at the upper left edge. The bay of Uchiura-Wan takes up the lower center of the image. In this image, color represents elevation, from blue at the lowest elevations to white at the highest. The radar image has been overlaid to provide more details of the terrain. Due to a processing problem, an island in the center of this crater lake is missing and will be properly placed when further SRTM swaths are processed. The horizontal banding in this image is a processing artifact that will be removed when the navigation information collected by SRTM is fully calibrated. This image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency (NIMA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise, Washington, DC. Size: 100 by 150 kilometers

  2. Reconfigurable L-Band Radar

    NASA Technical Reports Server (NTRS)

    Rincon, Rafael F.

    2008-01-01

    The reconfigurable L-Band radar is an ongoing development at NASA/GSFC that exploits the capability inherently in phased array radar systems with a state-of-the-art data acquisition and real-time processor in order to enable multi-mode measurement techniques in a single radar architecture. The development leverages on the L-Band Imaging Scatterometer, a radar system designed for the development and testing of new radar techniques; and the custom-built DBSAR processor, a highly reconfigurable, high speed data acquisition and processing system. The radar modes currently implemented include scatterometer, synthetic aperture radar, and altimetry; and plans to add new modes such as radiometry and bi-static GNSS signals are being formulated. This development is aimed at enhancing the radar remote sensing capabilities for airborne and spaceborne applications in support of Earth Science and planetary exploration This paper describes the design of the radar and processor systems, explains the operational modes, and discusses preliminary measurements and future plans.

  3. Python-ARM Radar Toolkit

    SciTech Connect

    Jonathan Helmus, Scott Collis

    2013-03-17

    The Python-ARM Radar Toolkit (Py-ART) is a collection of radar quality control and retrieval codes which all work on two unifying Python objects: the PyRadar and PyGrid objects. By building ingests to several popular radar formats and then abstracting the interface Py-ART greatly simplifies data processing over several other available utilities. In addition Py-ART makes use of Numpy arrays as its primary storage mechanism enabling use of existing and extensive community software tools.

  4. First HF radar measurements of summer mesopause echoes at SURA

    NASA Astrophysics Data System (ADS)

    Karashtin, A. N.; Shlyugaev, Y. V.; Abramov, V. I.; Belov, I. F.; Berezin, I. V.; Bychkov, V. V.; Eryshev, E. B.; Komrakov, G. P.

    1997-07-01

    HF sounding of the mesosphere was first carried out at SURA in summer 1994 at frequencies in the range 8-9 MHz using one of the sub-arrays of the SURA heating facility. The observations had a range resolution of 3 km. Almost all measurements indicated the presence of strong radar returns from altitudes between 83 and 90 km with features very similar to VHF measurements of mesopause summer echoes at mid-latitudes and polar mesopause summer echoes. In contrast to VHF observations, HF mesopause echoes are almost always present.

  5. 45 Km Horizontal Path Optical Link Experiment

    NASA Technical Reports Server (NTRS)

    Biswas, A.; Ceniceros, J.; Novak, M.; Jeganathan, M.; Portillo, A.; Erickson, D.; Depew, J.; Sanii, B.; Lesh, J. R.

    2000-01-01

    Mountain-top to mountain-top optical link experiments have been initiated at JPL, in order to perform a systems level evaluation of optical communications. Progress made so far is reported. ne NASA, JPL developed optical communications demonstrator (OCD) is used to transmit a laser signal from Strawberry Peak (SP), located in the San Bernadino mountains of California. This laser beam is received by a 0.6 m aperture telescope at JPL's Table Mountain Facility (TMF), located in Wrightwood, California. The optical link is bi-directional with the TMF telescope transmitting a continuous 4-wave (cw) 780 run beacon and the OCD sending back a 840 nm, 100 - 500 Mbps pseudo noise (PN) modulated, laser beam. The optical link path is at an average altitude of 2 km above sea level, covers a range of 46.8 km and provides an atmospheric channel equivalent to approx. 4 air masses. Average received power measured at either end fall well within the uncertainties predicted by link analysis. The reduction in normalized intensity variance (sigma(sup 2, sub I)) for the 4-beam beacon, compared to each individual beam, at SP, was from approx. 0.68 to 0.22. With some allowance for intra-beam mis-alignment, this is consistent with incoherent averaging. The sigma(sup2, sub I) measured at TMF approx. 0.43 +/- 0.22 exceeded the expected aperture averaged value of less than 0.1, probably because of beam wander. The focused spot sizes of approx. 162 +/- 6 microns at the TMF Coude and approx. 64 +/- 3 microns on the OCD compare to the predicted size range of 52 - 172 microns and 57 - 93 microns, respectively. This is consistent with 4 - 5 arcsec of atmospheric "seeing". The preliminary evaluation of OCD's fine tracking indicates that the uncompensated tracking error is approx. 3.3 micro rad compared to approx. 1.7 micro rad observed in the laboratory. Fine tracking performance was intermittent, primarily due to beacon fades on the OCD tracking sensor. The best bit error rates observed while

  6. The Telescope Array RADAR (TARA) Project and the Search for the Radar Signature of Cosmic Ray Induced Extensive Air Showers

    NASA Astrophysics Data System (ADS)

    Prohira, Steven; TARA Collaboration; Telescope Array Collaboration

    2016-03-01

    The TARA (Telescope Array Radar) cosmic ray detector has been in operation since May 2013. It is the most ambitious effort to date to test an idea that originated in the 1940's: that ionization produced by cosmic ray extensive air showers should reflect electromagnetic radiation. The observation of this effect would open the possibility that remote-sensing radar technology could be used to detect and reconstruct extensive air showers, thus increasing the aperture available for the study of the highest-energy cosmic rays. TARA employs a bi-static radar configuration, consisting of a 25 kW, 5 MW ERP transmitter at 54.1 MHz broadcasting across the Telescope Array surface detector. 40 km distant, a set of log-periodic receiver antennas are read out by two independent data acquisition systems employing different techniques to select signals of the form expected for radar targets moving at close to the speed of light. In this talk, we describe the TARA detector and present the first quantitative limits on the radar cross-section of extensive air showers.

  7. 915-MHz Radar Wind Profiler (915RWP) Handbook

    SciTech Connect

    Coulter, R

    2005-01-01

    The 915 MHz radar wind profiler/radio acoustic sounding system (RWP/RASS) measures wind profiles and backscattered signal strength between (nominally) 0.1 km and 5 km and virtual temperature profiles between 0.1 km and 2.5 km. It operates by transmitting electromagnetic energy into the atmosphere and measuring the strength and frequency of backscattered energy. Virtual temperatures are recovered by transmitting an acoustic signal vertically and measuring the electromagnetic energy scattered from the acoustic wavefront. Because the propagation speed of the acoustic wave is proportional to the square root of the virtual temperature of the air, the virtual temperature can be recovered by measuring the Doppler shift of the scattered electromagnetic wave.

  8. Radar - 449MHz - North Bend, OR (OTH) - Raw Data

    SciTech Connect

    Coleman, Tim

    2016-10-25

    **Winds.** A radar wind profiler measures the Doppler shift of electromagnetic energy scattered back from atmospheric turbulence and hydrometeors along 3-5 vertical and off-vertical point beam directions. Back-scattered signal strength and radial-component velocities are remotely sensed along all beam directions and are combined to derive the horizontal wind field over the radar. These data typically are sampled and averaged hourly and usually have 6-m and/or 100-m vertical resolutions up to 4 km for the 915 MHz and 8 km for the 449 MHz systems. **Temperature.** To measure atmospheric temperature, a radio acoustic sound system (RASS) is used in conjunction with the wind profile. These data typically are sampled and averaged for five minutes each hour and have a 60-m vertical resolution up to 1.5 km for the 915 MHz and 60-m up to 3.5k m for the 449 MHz. **Spectra.** The daily raw spectra data are available. The files are labeled "header" and "data." These data files are generated by LapXM, binary encoded, and are specific to this application. These datasets contain the raw data from the radar, such as signal-to-noise, signal power, radial velocity, and spectra widths.

  9. Radar - 449MHz - Astoria, OR (AST) - Raw Data

    SciTech Connect

    Coleman, Tim

    2016-10-25

    **Winds.** A radar wind profiler measures the Doppler shift of electromagnetic energy scattered back from atmospheric turbulence and hydrometeors along 3-5 vertical and off-vertical point beam directions. Back-scattered signal strength and radial-component velocities are remotely sensed along all beam directions and are combined to derive the horizontal wind field over the radar. These data typically are sampled and averaged hourly and usually have 6-m and/or 100-m vertical resolutions up to 4 km for the 915 MHz and 8 km for the 449 MHz systems. **Temperature.** To measure atmospheric temperature, a radio acoustic sound system (RASS) is used in conjunction with the wind profile. These data typically are sampled and averaged for five minutes each hour and have a 60-m vertical resolution up to 1.5 km for the 915 MHz and 60-m up to 3.5k m for the 449 MHz. **Spectra.** The daily raw spectra data are available. The files are labeled "header" and "data." These data files are generated by LapXM, binary encoded, and are specific to this application. These datasets contain the raw data from the radar, such as signal-to-noise, signal power, radial velocity, and spectra widths.

  10. Radar - 449MHz - Forks, WA (FKS) - Raw Data

    SciTech Connect

    Coleman, Tim

    2016-10-25

    **Winds.** A radar wind profiler measures the Doppler shift of electromagnetic energy scattered back from atmospheric turbulence and hydrometeors along 3-5 vertical and off-vertical point beam directions. Back-scattered signal strength and radial-component velocities are remotely sensed along all beam directions and are combined to derive the horizontal wind field over the radar. These data typically are sampled and averaged hourly and usually have 6-m and/or 100-m vertical resolutions up to 4 km for the 915 MHz and 8 km for the 449 MHz systems. **Temperature.** To measure atmospheric temperature, a radio acoustic sound system (RASS) is used in conjunction with the wind profile. These data typically are sampled and averaged for five minutes each hour and have a 60-m vertical resolution up to 1.5 km for the 915 MHz and 60-m up to 3.5k m for the 449 MHz. **Spectra.** The daily raw spectra data are available. The files are labeled "header" and "data." These data files are generated by LapXM, binary encoded, and are specific to this application. These datasets contain the raw data from the radar, such as signal-to-noise, signal power, radial velocity, and spectra widths.

  11. Teleportation of entanglement over 143 km.

    PubMed

    Herbst, Thomas; Scheidl, Thomas; Fink, Matthias; Handsteiner, Johannes; Wittmann, Bernhard; Ursin, Rupert; Zeilinger, Anton

    2015-11-17

    As a direct consequence of the no-cloning theorem, the deterministic amplification as in classical communication is impossible for unknown quantum states. This calls for more advanced techniques in a future global quantum network, e.g., for cloud quantum computing. A unique solution is the teleportation of an entangled state, i.e., entanglement swapping, representing the central resource to relay entanglement between distant nodes. Together with entanglement purification and a quantum memory it constitutes a so-called quantum repeater. Since the aforementioned building blocks have been individually demonstrated in laboratory setups only, the applicability of the required technology in real-world scenarios remained to be proven. Here we present a free-space entanglement-swapping experiment between the Canary Islands of La Palma and Tenerife, verifying the presence of quantum entanglement between two previously independent photons separated by 143 km. We obtained an expectation value for the entanglement-witness operator, more than 6 SDs beyond the classical limit. By consecutive generation of the two required photon pairs and space-like separation of the relevant measurement events, we also showed the feasibility of the swapping protocol in a long-distance scenario, where the independence of the nodes is highly demanded. Because our results already allow for efficient implementation of entanglement purification, we anticipate our research to lay the ground for a fully fledged quantum repeater over a realistic high-loss and even turbulent quantum channel.

  12. Integration of WERA Ocean Radar into Tsunami Early Warning Systems

    NASA Astrophysics Data System (ADS)

    Dzvonkovskaya, Anna; Helzel, Thomas; Kniephoff, Matthias; Petersen, Leif; Weber, Bernd

    2016-04-01

    High-frequency (HF) ocean radars give a unique capability to deliver simultaneous wide area measurements of ocean surface current fields and sea state parameters far beyond the horizon. The WERA® ocean radar system is a shore-based remote sensing system to monitor ocean surface in near real-time and at all-weather conditions up to 300 km offshore. Tsunami induced surface currents cause increasing orbital velocities comparing to normal oceanographic situation and affect the measured radar spectra. The theoretical approach about tsunami influence on radar spectra showed that a tsunami wave train generates a specific unusual pattern in the HF radar spectra. While the tsunami wave is approaching the beach, the surface current pattern changes slightly in deep water and significantly in the shelf area as it was shown in theoretical considerations and later proved during the 2011 Japan tsunami. These observed tsunami signatures showed that the velocity of tsunami currents depended on a tsunami wave height and bathymetry. The HF ocean radar doesn't measure the approaching wave height of a tsunami; however, it can resolve the surface current velocity signature, which is generated when tsunami reaches the shelf edge. This strong change of the surface current can be detected by a phased-array WERA system in real-time; thus the WERA ocean radar is a valuable tool to support Tsunami Early Warning Systems (TEWS). Based on real tsunami measurements, requirements for the integration of ocean radar systems into TEWS are already defined. The requirements include a high range resolution, a narrow beam directivity of phased-array antennas and an accelerated data update mode to provide a possibility of offshore tsunami detection in real-time. The developed software package allows reconstructing an ocean surface current map of the area observed by HF radar based on the radar power spectrum processing. This fact gives an opportunity to issue an automated tsunami identification message

  13. Removing interfering clutter associated with radar pulses that an airborne radar receives from a radar transponder

    DOEpatents

    Ormesher, Richard C.; Axline, Robert M.

    2008-12-02

    Interfering clutter in radar pulses received by an airborne radar system from a radar transponder can be suppressed by developing a representation of the incoming echo-voltage time-series that permits the clutter associated with predetermined parts of the time-series to be estimated. These estimates can be used to estimate and suppress the clutter associated with other parts of the time-series.

  14. Temporal Stability of Soil Moisture and Radar Backscatter Observed by the Advanced Synthetic Aperture Radar (ASAR).

    PubMed

    Wagner, Wolfgang; Pathe, Carsten; Doubkova, Marcela; Sabel, Daniel; Bartsch, Annett; Hasenauer, Stefan; Blöschl, Günter; Scipal, Klaus; Martínez-Fernández, José; Löw, Alexander

    2008-02-21

    The high spatio-temporal variability of soil moisture is the result of atmosphericforcing and redistribution processes related to terrain, soil, and vegetation characteristics.Despite this high variability, many field studies have shown that in the temporal domainsoil moisture measured at specific locations is correlated to the mean soil moisture contentover an area. Since the measurements taken by Synthetic Aperture Radar (SAR)instruments are very sensitive to soil moisture it is hypothesized that the temporally stablesoil moisture patterns are reflected in the radar backscatter measurements. To verify this hypothesis 73 Wide Swath (WS) images have been acquired by the ENVISAT AdvancedSynthetic Aperture Radar (ASAR) over the REMEDHUS soil moisture network located inthe Duero basin, Spain. It is found that a time-invariant linear relationship is well suited forrelating local scale (pixel) and regional scale (50 km) backscatter. The observed linearmodel coefficients can be estimated by considering the scattering properties of the terrainand vegetation and the soil moisture scaling properties. For both linear model coefficients,the relative error between observed and modelled values is less than 5 % and thecoefficient of determination (R²) is 86 %. The results are of relevance for interpreting anddownscaling coarse resolution soil moisture data retrieved from active (METOP ASCAT)and passive (SMOS, AMSR-E) instruments.

  15. Planetary radar studies. [radar mapping of the Moon and radar signatures of lunar and Venus craters

    NASA Technical Reports Server (NTRS)

    Thompson, T. W.; Cutts, J. A.

    1981-01-01

    Progress made in studying the evolution of Venusian craters and the evolution of infrared and radar signatures of lunar crater interiors is reported. Comparison of radar images of craters on Venus and the Moon present evidence for a steady state Venus crater population. Successful observations at the Arecibo Observatory yielded good data on five nights when data for a mix of inner and limb areas were acquired. Lunar craters with radar bright ejects are discussed. An overview of infrared radar crater catalogs in the data base is included.

  16. Radar Sounding of Mars with MARSIS

    NASA Astrophysics Data System (ADS)

    Plaut, J. J.; Picardi, G.; Orosei, R.; Gurnett, D. A.

    2009-12-01

    MARSIS, the Mars Advanced Radar for Subsurface and Ionospheric Sounding, is a radar sounder that has been observing Mars from the Mars Express orbiter since June 2005. MARSIS works in the range of 1.3 to 5.5 MHz, and includes significant onboard data summing. MARSIS also operates in an Active Ionospheric Sounding mode down to 0.1 MHz to capture echoes from the topside of the ionosphere. MARSIS signals easily penetrate the polar layered deposits (PLD), usually to their basal contact with the substrate. The typically strong echo return from the lower interface of the PLD indicates that only minor attenuation of the radar signal is occurring within the PLD, implying a composition of nearly pure water ice. MARSIS data have been used to map the bed of the polar deposits to their maximum depth of over 3.5 km in the south. In the north, MARSIS delineates the extent of the “basal unit,” a sediment-laden icy layer that makes up more than a third of the total volume of the topographic cap. In both polar regions, the bed topography does not display a regional-scale deflection that might be expected from a flexural response to the PLD load, indicating a thick elastic lithosphere in these regions. Subsurface interfaces in the low latitudes of Mars are also being mapped by MARSIS, in the equatorial Medusae Fossae Formation. MARSIS has not detected any unambiguous evidence for sizable shallow aquifers. While it is possible that such features exist, the lack of detection more likely indicates that liquid water is not abundant in the shallow (< several km) subsurface of Mars. However, water ice is abundant in the polar regions, including a large area surrounding the polar layered deposits that is associated with the Dorsa Argentea Formation. In addition, analysis of the MARSIS surface echo strength suggests that a substantial fraction of the upper km of the subsurface of the northern plains may be ice-rich. In its ionospheric mode, MARSIS has characterized the complex structure

  17. Radar polarization studies of volcanic and impact cratered terrains on the Earth, Venus, and the Moon

    NASA Astrophysics Data System (ADS)

    Campbell, Bruce Allan

    The results of four research projects which utilized imaging radar polarization data for remote sensing of volcanic and impact cratered terrains on the Earth, Venus, and the Moon are presented. The first project is an analysis of airborne multi-polarization radar data. A technique is developed for decomposing the polarized radar echo into components attributed to quasi-specular, small-perturbation, and 'dihedral' mechanisms. The second and third projects analyze the geomorphology and radar polarization properties of deposits on two volcanoes, Sif and Gula Montes, in western Eistla Regio, Venus. These analyses utilize radar images collected at Arecibo Observatory in 1988 (spatial resolution 1 km). Changes in the radar brightness of lava flows with downslope distance from possible vents are inconsistent with trends observed for single terrestrial lava flow. This observation, coupled with evidence of multiple eruptive vents, suggests that most of the large flows in western Eistla Regio are formed by coalescence of numerous smaller flows. The third project also compares the radar polarization properties of volcanic deposits on Sif and Gula Montes to data for terrestrial lava flows and a smooth desert area. The fourth project presents a study of lunar crater rays using high-resolution (30 m) radar images collected at Haystack Observatory, and focuses on the bright ray in Mare Serenitatis and ray segments attributed to Tycho and Copernicus craters.

  18. Simulation of radar rainfall errors and their propagation into rainfall-runoff processes

    NASA Astrophysics Data System (ADS)

    Aghakouchak, A.; Habib, E.

    2008-05-01

    Radar rainfall data compared with rain gauge measurements provide higher spatial and temporal resolution. However, radar data obtained form reflectivity patterns are subject to various errors such as errors in Z-R relationship, vertical profile of reflectivity, spatial and temporal sampling, etc. Characterization of such uncertainties in radar data and their effects on hydrologic simulations (e.g., streamflow estimation) is a challenging issue. This study aims to analyze radar rainfall error characteristics empirically to gain information on prosperities of random error representativeness and its temporal and spatial dependency. To empirically analyze error characteristics, high resolution and accurate rain gauge measurements are required. The Goodwin Creek watershed located in the north part of Mississippi is selected for this study due to availability of a dense rain gauge network. A total of 30 rain gauge measurement stations within Goodwin Creak watershed and the NWS Level II radar reflectivity data obtained from the WSR-88dD Memphis radar station with temporal resolution of 5min and spatial resolution of 1 km2 are used in this study. Radar data and rain gauge measurements comparisons are used to estimate overall bias, and statistical characteristics and spatio-temporal dependency of radar rainfall error fields. This information is then used to simulate realizations of radar error patterns with multiple correlated variables using Monte Calro method and the Cholesky decomposition. The generated error fields are then imposed on radar rainfall fields to obtain statistical realizations of input rainfall fields. Each simulated realization is then fed as input to a distributed physically based hydrological model resulting in an ensemble of predicted runoff hydrographs. The study analyzes the propagation of radar errors on the simulation of different rainfall-runoff processes such as streamflow, soil moisture, infiltration, and over-land flooding.

  19. Analysis of spatial variability of extreme rainfall at radar subpixel scale using IDF curves

    NASA Astrophysics Data System (ADS)

    Peleg, Nadav; Marra, Francesco; Fatichi, Simone; Paschalis, Athanasios; Molnar, Peter; Burlando, Paolo

    2016-04-01

    Extreme rainfall is quantified in engineering practice using Intensity-Duration-Frequency curves (IDFs) that are traditionally derived from rain-gauges and, more recently, also from weather radars. These instruments measure rainfall at different spatial scales: rain-gauge samples rainfall at the point scale while weather radar averages precipitation over a relatively large area, generally around 1 km2. As such, a radar derived IDF curve is representative of the mean areal rainfall over a given radar pixel and neglects the within-pixel rainfall variability. In this study, we quantify subpixel variability of extreme rainfall by using a novel space-time rainfall generator (STREAP model) that downscales in space the rainfall within a given radar pixel. The study was conducted using a long radar data record (23 years) and a very dense rain-gauge network in the Eastern Mediterranean area. Radar-IDF curves, together with an ensemble of point-based IDF curves representing the radar subpixel extreme rainfall variability, were developed fitting GEV distributions to annual rainfall maxima. It was found that the mean areal extreme rainfall derived from the radar underestimate most of the extreme values computed for point locations within the radar pixel. The subpixel variability of extreme rainfall was found to increase with longer return periods and shorter durations. For the longer return periods, a considerable enhancement of extreme rainfall variability was found when stochastic (natural) climate variability was taken into account. Bounding the range of the subpixel extreme rainfall derived from radar-IDF can be of major importance for applications that require very local estimates of rainfall extremes.

  20. Broadview Radar Altimetry Toolbox

    NASA Astrophysics Data System (ADS)

    Mondéjar, Albert; Benveniste, Jérôme; Naeije, Marc; Escolà, Roger; Moyano, Gorka; Roca, Mònica; Terra-Homem, Miguel; Friaças, Ana; Martinho, Fernando; Schrama, Ernst; Ambrózio, Américo; Restano, Marco

    2016-07-01

    The universal altimetry toolbox, BRAT (Broadview Radar Altimetry Toolbox) which can read all previous and current altimetry missions' data, incorporates now the capability to read the upcoming Sentinel-3 L1 and L2 products. ESA endeavoured to develop and supply this capability to support the users of the future Sentinel-3 SAR Altimetry Mission. BRAT is a collection of tools and tutorial documents designed to facilitate the processing of radar altimetry data. This project started in 2005 from the joint efforts of ESA (European Space Agency) and CNES (Centre National d'Études Spatiales), and it is freely available at http://earth.esa.int/brat. The tools enable users to interact with the most common altimetry data formats. The BratGUI is the front-end for the powerful command line tools that are part of the BRAT suite. BRAT can also be used in conjunction with MATLAB/IDL (via reading routines) or in C/C++/Fortran via a programming API, allowing the user to obtain desired data, bypassing the data-formatting hassle. BRAT can be used simply to visualise data quickly, or to translate the data into other formats such as NetCDF, ASCII text files, KML (Google Earth) and raster images (JPEG, PNG, etc.). Several kinds of computations can be done within BRAT involving combinations of data fields that the user can save for posterior reuse or using the already embedded formulas that include the standard oceanographic altimetry formulas. The Radar Altimeter Tutorial, that contains a strong introduction to altimetry, shows its applications in different fields such as Oceanography, Cryosphere, Geodesy, Hydrology among others. Included are also "use cases", with step-by-step examples, on how to use the toolbox in the different contexts. The Sentinel-3 SAR Altimetry Toolbox shall benefit from the current BRAT version. While developing the toolbox we will revamp of the Graphical User Interface and provide, among other enhancements, support for reading the upcoming S3 datasets and

  1. Broadview Radar Altimetry Toolbox

    NASA Astrophysics Data System (ADS)

    Escolà, Roger; Garcia-Mondejar, Albert; Moyano, Gorka; Roca, Mònica; Terra-Homem, Miguel; Friaças, Ana; Martinho, Fernando; Schrama, Ernst; Naeije, Marc; Ambrozio, Americo; Restano, Marco; Benveniste, Jérôme

    2016-04-01

    The universal altimetry toolbox, BRAT (Broadview Radar Altimetry Toolbox) which can read all previous and current altimetry missions' data, incorporates now the capability to read the upcoming Sentinel-3 L1 and L2 products. ESA endeavoured to develop and supply this capability to support the users of the future Sentinel-3 SAR Altimetry Mission. BRAT is a collection of tools and tutorial documents designed to facilitate the processing of radar altimetry data. This project started in 2005 from the joint efforts of ESA (European Space Agency) and CNES (Centre National d'Etudes Spatiales), and it is freely available at http://earth.esa.int/brat. The tools enable users to interact with the most common altimetry data formats. The BratGUI is the front-end for the powerful command line tools that are part of the BRAT suite. BRAT can also be used in conjunction with MATLAB/IDL (via reading routines) or in C/C++/Fortran via a programming API, allowing the user to obtain desired data, bypassing the data-formatting hassle. BRAT can be used simply to visualise data quickly, or to translate the data into other formats such as NetCDF, ASCII text files, KML (Google Earth) and raster images (JPEG, PNG, etc.). Several kinds of computations can be done within BRAT involving combinations of data fields that the user can save for posterior reuse or using the already embedded formulas that include the standard oceanographic altimetry formulas. The Radar Altimeter Tutorial, that contains a strong introduction to altimetry, shows its applications in different fields such as Oceanography, Cryosphere, Geodesy, Hydrology among others. Included are also "use cases", with step-by-step examples, on how to use the toolbox in the different contexts. The Sentinel-3 SAR Altimetry Toolbox shall benefit from the current BRAT version. While developing the toolbox we will revamp of the Graphical User Interface and provide, among other enhancements, support for reading the upcoming S3 datasets and

  2. Peregrine 100-km Sounding Rocket Project

    NASA Technical Reports Server (NTRS)

    Zilliac, Gregory

    2012-01-01

    The Peregrine Sounding Rocket Program is a joint basic research program of NASA Ames Research Center, NASA Wallops, Stanford University, and the Space Propulsion Group, Inc. (SPG). The goal is to determine the applicability of this technology to a small launch system. The approach is to design, build, and fly a stable, efficient liquefying fuel hybrid rocket vehicle to an altitude of 100 km. The program was kicked off in October of 2006 and has seen considerable progress in the subsequent 18 months. This research group began studying liquifying hybrid rocket fuel technology more than a decade ago. The overall goal of the research was to gain a better understanding of the fundamental physics of the liquid layer entrainment process responsible for the large increase in regression rate observed in these fuels, and to demonstrate the effect of increased regression rate on hybrid rocket motor performance. At the time of this reporting, more than 400 motor tests were conducted with a variety of oxidizers (N2O, GOx, LOx) at ever increasing scales with thrust levels from 5 to over 15,000 pounds (22 N to over 66 kN) in order to move this technology from the laboratory to practical applications. The Peregrine program is the natural next step in this development. A number of small sounding rockets with diameters of 3, 4, and 6 in. (7.6, 10.2, and 15.2 cm) have been flown, but Peregrine at a diameter of 15 in. (38.1 cm) and 14,000-lb (62.3-kN) thrust is by far the largest system ever attempted and will be one of the largest hybrids ever flown. Successful Peregrine flights will set the stage for a wide range of applications of this technology.

  3. Interferometric radar measurements

    NASA Astrophysics Data System (ADS)

    Smith, Ronald A.; Shipman, Mark; Holder, E. J.; Williams, James K.

    2002-08-01

    The United States Army Space and Missile Defense Command (USASMDC) has interest in a technology demonstration that capitalizes on investment in fire control and smart interceptor technologies that have matured beyond basic research. The concept SWORD (Short range missile defense With Optimized Radar Distribution) consists of a novel approach utilizing a missile interceptor and interferometric fire control radar. A hit-to-kill, closed-loop, command guidance scheme is planned that takes advantage of extremely accurate target and interceptor state vectors derived via the fire control radar. The fire control system has the capability to detect, track, and classify multiple threats in a tactical regime as well as simultaneously provide command guidance updates to multiple missile interceptors. The missile interceptor offers a cost reduction potential as well as an enhancement to the kinematics range and lethality over existing SHORAD systems. Additionally, the Radio Frequency (RF) guidance scheme offers increased battlefield weather performance. The Air Defense (AD) community, responding to current threat capabilities and trends, has identified an urgent need to have a capability to counter proliferated, low cost threats with a low cost-per-kill weapon system. The SWORD system will offer a solution that meets this need. The SWORD critical technologies will be identified including a detailed description of each. Validated test results and basic principles of operation will be presented to prove the merit of past investments. The Deputy Assistant Secretary of the Army for Research and Technology (DAS(R&T) has a three- year Science and Technology Program to evaluate the errors and proposed mitigation techniques associated with target spectral dispersion and range gate straddle. Preliminary bench-top experiment results will be presented in this paper.

  4. Doppler radar flowmeter

    DOEpatents

    Petlevich, Walter J.; Sverdrup, Edward F.

    1978-01-01

    A Doppler radar flowmeter comprises a transceiver which produces an audio frequency output related to the Doppler shift in frequency between radio waves backscattered from particulate matter carried in a fluid and the radiated radio waves. A variable gain amplifier and low pass filter are provided for amplifying and filtering the transceiver output. A frequency counter having a variable triggering level is also provided to determine the magnitude of the Doppler shift. A calibration method is disclosed wherein the amplifier gain and frequency counter trigger level are adjusted to achieve plateaus in the output of the frequency counter and thereby allow calibration without the necessity of being able to visually observe the flow.

  5. Weather Radar Studies

    DTIC Science & Technology

    1988-03-31

    Reflectivity Core Recognition 68 IV-10 Middle-Level Precursor Recognition 69 IV-l I Early Microburst Hazard Declaration 70 IV-12 Example of Results from...Denver Test Bed 106 V-I Selected Product Types 14 V-2 Encoded Map Size (in ELMs ) for Terminal Map Data Set 119 V-3 Encoded Map Size (in ELMs ) for En...Route Data Sets 119 V-4 Encoded Map Size (in ELMs ) for Terminal Map Data Set 125 xiii WEATHER RADAR STUDIES 1. INTRODUCTION The principal areas of

  6. Propagation of radar rainfall uncertainty in urban flood simulations

    NASA Astrophysics Data System (ADS)

    Liguori, Sara; Rico-Ramirez, Miguel

    2013-04-01

    hydrodynamic sewer network model implemented in the Infoworks software was used to model the rainfall-runoff process in the urban area. The software calculates the flow through the sewer conduits of the urban model using rainfall as the primary input. The sewer network is covered by 25 radar pixels with a spatial resolution of 1 km2. The majority of the sewer system is combined, carrying both urban rainfall runoff as well as domestic and trade waste water [11]. The urban model was configured to receive the probabilistic radar rainfall fields. The results showed that the radar rainfall ensembles provide additional information about the uncertainty in the radar rainfall measurements that can be propagated in urban flood modelling. The peaks of the measured flow hydrographs are often bounded within the uncertainty area produced by using the radar rainfall ensembles. This is in fact one of the benefits of using radar rainfall ensembles in urban flood modelling. More work needs to be done in improving the urban models, but this is out of the scope of this research. The rainfall uncertainty cannot explain the whole uncertainty shown in the flow simulations, and additional sources of uncertainty will come from the structure of the urban models as well as the large number of parameters required by these models. Acknowledgements The authors would like to acknowledge the BADC, the UK Met Office and the UK Environment Agency for providing the various data sets. We also thank Yorkshire Water Services Ltd for providing the urban model. The authors acknowledge the support from the Engineering and Physical Sciences Research Council (EPSRC) via grant EP/I012222/1. References [1] Browning KA, 1978. Meteorological applications of radar. Reports on Progress in Physics 41 761 Doi: 10.1088/0034-4885/41/5/003 [2] Rico-Ramirez MA, Cluckie ID, Shepherd G, Pallot A, 2007. A high-resolution radar experiment on the island of Jersey. Meteorological Applications 14: 117-129. [3] Villarini G, Krajewski WF

  7. Radar Imaging and Feature Extraction

    DTIC Science & Technology

    2007-11-02

    aperture radar (ISAR) autofocus and imaging, synthetic aperture radar (SAR) autofocus and motion compensation, superresolution SAR image formation... superresolution image formation, and two parametric methods, MCRELAX (Motion Compensation RELAX) and MCCLEAN (Motion Compensation CLEAN), for simultaneous target...Direction Estimation) together with WRELAX) algorithm is proposed for the superresolution time delay estimation.

  8. Millimeter radar improves target identification

    NASA Astrophysics Data System (ADS)

    McAulay, Alastair D.

    2011-06-01

    Recently developed millimeter wave radar has advantages for target identification over conventional microwave radar which typically use lower frequencies. We describe the pertinent features involved in the construction of the new millimeter wave radar, the pseudo-optical cavity source and the quasi-optical duplexer. The long wavelength relative to light allows the radar beam to penetrate through most weather because the wavelength is larger than the particle size for dust, drizzle rain, fog. Further the mm wave beam passes through an atmospheric transmission window that provides a dip in attenuation. The higher frequency than conventional radar provides higher Doppler frequencies, for example, than X-band radar. We show by simulation that small characteristic vibrations and slow turns of an aircraft become visible so that the Doppler signature improves identification. The higher frequency also reduces beam width, which increases transmit and receive antenna gains. For the same power the transmit beam extends to farther range and the increase in receive antenna gain increases signal to noise ratio for improved detection and identification. The narrower beam can also reduce clutter and reject other noise more readily. We show by simulation that the radar can be used at lower elevations over the sea than conventional radar.

  9. Radar Control Optimal Resource Allocation

    DTIC Science & Technology

    2015-07-13

    Dartmouth, Nova Scotia, Canada by the McMaster University Intelligent PIXel (IPIX) X-band Polarimetric Coherent Radar during the OHGR - Dartmouth...Distribution is unlimited Wind Direction N Figure 7: Radar data collection site at OHGR, Nova Scotia. Source:[15] to having a significant wave height of 0.7 m

  10. High-resolution instrumentation radar

    NASA Astrophysics Data System (ADS)

    Dybdal, Robert B.; Hurlbut, Keith H.; Mori, Tsutomu T.

    1986-09-01

    The development of an instrumentation radar that uses a chirp waveform to achieve high range resolution is described. Such range resolution capability is required for two reasons: (1) to evaluate the response of targets to the operational waveforms used in high-performance radars; and (2) to obtain a means of separating the individual mechanisms that comprise the target scattering response to better understand the scattering process. This particular radar was efficiently constructed from a combination of commercially available components and in-house-fabricated circuitry. This instrumentation radar operates at X-band and achieves a 4.9-in. range resolution. A key feature of the radar is its ability to combine amplitude weighting with a high degree of waveform fidelity, with the result being very good range sidelobe performance.

  11. A radar image time series

    NASA Technical Reports Server (NTRS)

    Leberl, F.; Fuchs, H.; Ford, J. P.

    1981-01-01

    A set of ten side-looking radar images of a mining area in Arizona that were aquired over a period of 14 yr are studied to demonstrate the photogrammetric differential-rectification technique applied to radar images and to examine changes that occurred in the area over time. Five of the images are rectified by using ground control points and a digital height model taken from a map. Residual coordinate errors in ground control are reduced from several hundred meters in all cases to + or - 19 to 70 m. The contents of the radar images are compared with a Landsat image and with aerial photographs. Effects of radar system parameters on radar images are briefly reviewed.

  12. Shuttle Imaging Radar - Geologic applications

    NASA Technical Reports Server (NTRS)

    Macdonald, H.; Bridges, L.; Waite, W.; Kaupp, V.

    1982-01-01

    The Space Shuttle, on its second flight (November 12, 1981), carried the first science and applications payload which provided an early demonstration of Shuttle's research capabilities. One of the experiments, the Shuttle Imaging Radar-A (SIR-A), had as a prime objective to evaluate the capability of spaceborne imaging radars as a tool for geologic exploration. The results of the experiment will help determine the value of using the combination of space radar and Landsat imagery for improved geologic analysis and mapping. Preliminary analysis of the Shuttle radar imagery with Seasat and Landsat imagery from similar areas provides evidence that spaceborne radars can significantly complement Landsat interpretation, and vastly improve geologic reconnaissance mapping in those areas of the world that are relatively unmapped because of perpetual cloud cover.

  13. Low-brightness quantum radar

    NASA Astrophysics Data System (ADS)

    Lanzagorta, Marco

    2015-05-01

    One of the major scientific thrusts from recent years has been to try to harness quantum phenomena to dramatically increase the performance of a wide variety of classical information processing devices. These advances in quantum information science have had a considerable impact on the development of standoff sensors such as quantum radar. In this paper we analyze the theoretical performance of low-brightness quantum radar that uses entangled photon states. We use the detection error probability as a measure of sensing performance and the interception error probability as a measure of stealthiness. We compare the performance of quantum radar against a coherent light sensor (such as lidar) and classical radar. In particular, we restrict our analysis to the performance of low-brightness standoff sensors operating in a noisy environment. We show that, compared to the two classical standoff sensing devices, quantum radar is stealthier, more resilient to jamming, and more accurate for the detection of low reflectivity targets.

  14. Radar SLAM using visual features

    NASA Astrophysics Data System (ADS)

    Callmer, Jonas; Törnqvist, David; Gustafsson, Fredrik; Svensson, Henrik; Carlbom, Pelle

    2011-12-01

    A vessel navigating in a critical environment such as an archipelago requires very accurate movement estimates. Intentional or unintentional jamming makes GPS unreliable as the only source of information and an additional independent supporting navigation system should be used. In this paper, we suggest estimating the vessel movements using a sequence of radar images from the preexisting body-fixed radar. Island landmarks in the radar scans are tracked between multiple scans using visual features. This provides information not only about the position of the vessel but also of its course and velocity. We present here a navigation framework that requires no additional hardware than the already existing naval radar sensor. Experiments show that visual radar features can be used to accurately estimate the vessel trajectory over an extensive data set.

  15. Comparison of Beijing MST radar and radiosonde horizontal wind measurements

    NASA Astrophysics Data System (ADS)

    Tian, Yufang; Lü, Daren

    2017-01-01

    To determine the performance and data accuracy of the 50 MHz Beijing Mesosphere-Stratosphere-Troposphere (MST) radar, comparisons of radar measured horizontal winds in the height range 3-25 km with radiosonde observations were made during 2012. A total of 427 profiles and 15 210 data pairs were compared. There was very good agreement between the two types of measurement. Standard deviations of difference (mean difference) for wind direction, wind speed, zonal wind and meridional wind were 24.86° (0.77°), 3.37 (-0.44), 3.33 (-0.32) and 3.58 (-0.25) m s-1, respectively. The annual standard deviations of differences for wind speed were within 2.5-3 m s-1 at all heights apart from 10-15 km, the area of strong winds, where the values were 3-4 m s-1. The relatively larger differences were mainly due to wind field variations in height regions with larger wind speeds, stronger wind shear and the quasi-zero wind layer. A lower MST radar SNR and a lower percentage of data pairs compared will also result in larger inconsistencies. Importantly, this study found that differences between the MST radar and radiosonde observations did not simply increase when balloon drift resulted in an increase in the real-time distance between the two instruments, but also depended on spatiotemporal structures and their respective positions in the contemporary synoptic systems. In this sense, the MST radar was shown to be a unique observation facility for atmospheric dynamics studies, as well as an operational meteorological observation system with a high temporal and vertical resolution.

  16. Space Radar Image of Washington D.C.

    NASA Technical Reports Server (NTRS)

    1994-01-01

    The city of Washington, D.C., is shown is this space radar image. Images like these are useful tools for urban planners and managers, who use them to map and monitor land use patterns. Downtown Washington is the bright area between the Potomac (upper center to lower left) and Anacostia (middle right) rivers. The dark cross shape that is formed by the National Mall, Tidal Basin, the White House and Ellipse is seen in the center of the image. Arlington National Cemetery is the dark blue area on the Virginia (left) side of the Potomac River near the center of the image. The Pentagon is visible in bright white and red, south of the cemetery. Due to the alignment of the radar and the streets, the avenues that form the boundary between Washington and Maryland appear as bright red lines in the top, right and bottom parts of the image, parallel to the image borders. This image is centered at 38.85 degrees north latitude, 77.05 degrees west longitude. North is toward the upper right. The area shown is approximately 29 km by 26 km (18 miles by 16 miles). Colors are assigned to different frequencies and polarizations of the radar as follows: Red is the L-band horizontally transmitted, horizontally received; green is the L-band horizontally transmitted, vertically received; blue is the C-band horizontally transmitted, vertically received. The image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture (SIR-C/X-SAR) imaging radar when it flew aboard the space shuttle Endeavour on April 18, 1994. SIR-C/X-SAR, a joint mission of the German, Italian and United States space agencies, is part of NASA's Mission to Planet Earth program.

  17. Runoff Analysis Considering Orographical Features Using Dual Polarization Radar Rainfall

    NASA Astrophysics Data System (ADS)

    Noh, Hui-seong; Shin, Hyun-seok; Kang, Na-rae; Lee, Choong-Ke; Kim, Hung-soo

    2013-04-01

    Recently, the necessity for rainfall estimation and forecasting using the radar is being highlighted, due to the frequent occurrence of torrential rainfall resulting from abnormal changes of weather. Radar rainfall data represents temporal and spatial distributions properly and replace the existing rain gauge networks. It is also frequently applied in many hydrologic field researches. However, the radar rainfall data has an accuracy limitation since it estimates rainfall, by monitoring clouds and precipitation particles formed around the surface of the earth(1.5-3km above the surface) or the atmosphere. In a condition like Korea where nearly 70% of the land is covered by mountainous areas, there are lots of restrictions to use rainfall radar, because of the occurrence of beam blocking areas by topography. This study is aiming at analyzing runoff and examining the applicability of (R(Z), R(ZDR) and R(KDP)) provided by the Han River Flood Control Office(HRFCO) based on the basin elevation of Nakdong river watershed. For this purpose, the amount of radar rainfall of each rainfall event was estimated according to three sub-basins of Nakdong river watershed with the average basin elevation above 400m which are Namgang dam, Andong dam and Hapcheon dam and also another three sub-basins with the average basin elevation below 150m which are Waegwan, Changryeong and Goryeong. After runoff analysis using a distribution model, Vflo model, the results were reviewed and compared with the observed runoff. This study estimated the rainfall by using the radar-rainfall transform formulas, (R(Z), R(Z,ZDR) and R(Z,ZDR,KDP) for four stormwater events and compared the results with the point rainfall of the rain gauge. As the result, it was overestimated or underestimated, depending on rainfall events. Also, calculation indicates that the values from R(Z,ZDR) and R(Z,ZDR,KDP) relatively showed the most similar results. Moreover the runoff analysis using the estimated radar rainfall is

  18. KM3NeT: towards a km 3-scale neutrino telescope in the Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Distefano, C.; KM3NeT Consortium

    2009-05-01

    The observation of high energy neutrinos ( ≳1 TeV) from astrophysical sources would substantially improve our knowledge and understanding of the non-thermal processes in these sources, and would in particular pinpoint the accelerators of cosmic rays. Theoretical predictions indicate that km 3-scale detectors are needed to detect astrophysical neutrino fluxes. That is the reason why the three Mediterranean experiments, ANTARES, NEMO and NESTOR are working together on preparing KM3NeT, a large deep-sea neutrino telescope in the Mediterranean Sea which will survey a large part of the Galactic disc, including the Galactic Centre. It will complement the IceCube telescope currently under construction at the South Pole. Furthermore, the improved optical properties of sea water, compared to Antarctic ice, will allow for a better angular resolution and hence a better background rejection. The construction of this detector will require the solution of technological problems common to many deep submarine installations, and will help paving the way for other deep-sea research facilities. In this paper the major activities and the status of KM3NeT are presented.

  19. KM3NeT: towards a km3-scale neutrino telescope in the Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Km3NeT Consortium; Distefano, C.; KM3NeT Consortium

    2009-05-01

    The observation of high energy neutrinos (≳1 TeV) from astrophysical sources would substantially improve our knowledge and understanding of the non-thermal processes in these sources, and would in particular pinpoint the accelerators of cosmic rays. Theoretical predictions indicate that km3-scale detectors are needed to detect astrophysical neutrino fluxes. That is the reason why the three Mediterranean experiments, ANTARES, NEMO and NESTOR are working together on preparing KM3NeT, a large deep-sea neutrino telescope in the Mediterranean Sea which will survey a large part of the Galactic disc, including the Galactic Centre. It will complement the IceCube telescope currently under construction at the South Pole. Furthermore, the improved optical properties of sea water, compared to Antarctic ice, will allow for a better angular resolution and hence a better background rejection. The construction of this detector will require the solution of technological problems common to many deep submarine installations, and will help paving the way for other deep-sea research facilities. In this paper the major activities and the status of KM3NeT are presented.

  20. Land subsidence measured by satellite radar altimetry

    NASA Technical Reports Server (NTRS)

    Krabill, W. B.; Brooks, R. L.

    1981-01-01

    Radar altimeter measurements from the GEOS-3 and SEASAT satellites are being evaluated to assess their potential contribution to terrain mapping. The primary evaluation area is the San Joaquin Valley of southern California; 40,000/sq km of the Valley have been mapped at a contour interval of 10 m from the satellite altimeter measurements. The accuracy of the altimeter derived terrain elevations is being assessed by comparison with 1:24,000 and digitized 1:250,000 maps and by intercomparisons at the crossover altimeter intersections. Comparisons of the altimeter derived elevations with historical maps archived at the U.S. Geological Survey confirms the USGS 1926-1972 subsidence contours for this area. Preliminary results from a similar analysis in the Houston-Galveston area of subsidence also demonstrates a capability of measuring land subsidence by satellite altimetry.

  1. Ground-based radar reflectivity mosaic of mei-yu precipitation systems over the Yangtze River-Huaihe River basins

    NASA Astrophysics Data System (ADS)

    Luo, Yali; Qian, Weimiao; Gong, Yu; Wang, Hongyan; Zhang, Da-Lin

    2016-11-01

    The 3D radar reflectivity produced by a mosaic software system, with measurements from 29 operational weather radars in the Yangtze River-Huaihe River Basins (YRHRB) during the mei-yu season of 2007, is compared to coincident TRMM PR observations in order to evaluate the value of the ground-based radar reflectivity mosaic in characterizing the 3D structures of mei-yu precipitation. Results show reasonable agreement in the composite radar reflectivity between the two datasets, with a correlation coefficient of 0.8 and a mean bias of -1 dB. The radar mosaic data at constant altitudes are reasonably consistent with the TRMM PR observations in the height range of 2-5 km, revealing essentially the same spatial distribution of radar echo and nearly identical histograms of reflectivity. However, at altitudes above 5 km, the mosaic data overestimate reflectivity and have slower decreasing rates with height compared to the TRMM PR observations. The areas of convective and stratiform precipitation, based on the mosaic reflectivity distribution at 3-km altitude, are highly correlated with the corresponding regions in the TRMM products, with correlation coefficients of 0.92 and 0.97 and mean relative differences of -7.9% and -2.5%, respectively. Finally, the usefulness of the mosaic reflectivity at 3-km altitude at 6-min intervals is illustrated using a mesoscale convective system that occurred over the YRHRB.

  2. Theoretical and experimental study of EKB radar ground-scatter signals at nearby frequencies

    NASA Astrophysics Data System (ADS)

    Kutelev, Konstantin; Berngardt, Oleg; Grkovich, Konstantin; Mikhailov, Nikita

    SuperDARN radars have wide possibilities for diagnostics of different motions in the ionosphere. The radars allow studying small-, medium- and large-scale irregularities. The radars have good time resolution (about 1 minute for full scan) and wide territory coverage (azimuthal coverage - 50 degrees, maximal range — 3000 km). EKB radar is the first russian radar of SuperDARN kind, installed by ISTP SB RAS near Ekaterinburg. The radar started its operation in December 2012. Mostly SuperDARN radars are used to investigate irregular structure of the ionosphere. In the work we present original approach that allows diagnose regular ionosphere. The approach is based on sounding at three close frequencies and on analysis of ground-scattered signal properties. As theoretical analysis shows the use of three-frequency sounding technique allows one to estimate following characteristics of the model quasiparabolic F-layer in a middle point of path: its critical frequency, the height of its maximum and layer thickness. For this purpose we use known dependence of a minimal group path of signal on radar frequency. The key problem for the described technique is optimizing the frequency step between sounding signals. From the one side, the frequency step should be large enough. This is necessary for the difference in group delays be larger than radar range resolution (15-60km). From the other side, significant variation of frequency leads to a significant movement of path midpoint. This leads to signifficant errors in estimating ionospheric paramters due to theirs horizontal gradients. To solve this problem we perform a simulation of ground-scattered signal at EKB radar in different geophysical conditions. We use IRI-2007 as a model of the ionosphere. We simulate experiment at different levels of solar activity, in different seasons and daytime. By using geometrooptical ray tracing method we calculate a signal minimal group paths for a set of frequencies. According to these data

  3. Coupling Between Doppler Radar Signatures and Tornado Damage Tracks

    NASA Technical Reports Server (NTRS)

    Jedlovec, Gary J.; Molthan, Andrew L.; Carey, Lawrence; Carcione, Brian; Smith, Matthew; Schultz, Elise V.; Schultz, Christopher; Lafontaine, Frank

    2011-01-01

    On April 27, 2011, the southeastern United States was raked with several episodes of severe weather. Numerous tornadoes caused extensive damage, and tragically, the deaths of over 300 people. In Alabama alone, there were 61 confirmed tornados, 4 of them produced EF5 damage, and several were on the ground an hour or more with continuous damage tracks exceeding 80km. The use of Doppler radars covering the region provided reflectivity and velocity signatures that allowed forecasters to monitors the severe storms from beginning to end issuing hundreds of severe weather warnings throughout the day. Meteorologists from the the NWS performed extensive surveys to assess the intensity, duration, and ground track of tornadoes reported during the event. Survey activities included site visits to the affected locations, analysis of radar and satellite data, aerial surveys, and interviews with eyewitnesses. Satellite data from NASA's MODIS and ASTER instruments played a helpful role in determining the location of tornado damage paths and in the assessment. High resolution multispectral and temporal composites helped forecasters corroborate their damage assessments, determine starting and ending points for tornado touchdowns, and helped to provide forecasters with a better big-picture view of the damage region. The imagery also helped to separate damage from the April 27th tornados from severe weather that occurred earlier that month. In a post analysis of the outbreak, tornado damage path signatures observed in the NASA satellite data have been correlated to "debris ball" signatures in the NWS Doppler radars and a special ARMOR dual-polarization radar operated by the University of Alabama Huntsville during the event. The Doppler radar data indicates a circular enhanced reflectivity signal and rotational couplet in the radial velocity likely associated with the tornado that is spatially correlated with the damage tracks in the observed satellite data. An algorithm to detect and

  4. Determining titan's spin state from cassini radar images

    USGS Publications Warehouse

    Stiles, B.W.; Kirk, R.L.; Lorenz, R.D.; Hensley, S.; Lee, E.; Ostro, S.J.; Allison, M.D.; Callahan, P.S.; Gim, Y.; Iess, L.; Del Marmo, P.P.; Hamilton, G.; Johnson, W.T.K.; West, R.D.

    2008-01-01

    For some 19 areas of Titan's surface, the Cassini RADAR instrument has obtained synthetic aperture radar (SAR) images during two different flybys. The time interval between flybys varies from several weeks to two years. We have used the apparent misregistration (by 10-30 km) of features between separate flybys to construct a refined model of Titan's spin state, estimating six parameters: north pole right ascension and declination, spin rate, and these quantities' first time derivatives We determine a pole location with right ascension of 39.48 degrees and declination of 83.43 degrees corresponding to a 0.3 degree obliquity. We determine the spin rate to be 22.5781 deg day -1 or 0.001 deg day-1 faster than the synchronous spin rate. Our estimated corrections to the pole and spin rate exceed their corresponding standard errors by factors of 80 and 8, respectively. We also found that the rate of change in the pole right ascension is -30 deg century-1, ten times faster than right ascension rate of change for the orbit normal. The spin rate is increasing at a rate of 0.05 deg day -1 per century. We observed no significant change in pole declination over the period for which we have data. Applying our pole correction reduces the feature misregistration from tens of km to 3 km. Applying the spin rate and derivative corrections further reduces the misregistration to 1.2 km. ?? 2008. The American Astronomical Society. All rights reserved.

  5. Mars Express radar collects first surface data

    NASA Astrophysics Data System (ADS)

    2005-08-01

    subsurface probing, Marsis must operate between 300 km and 800 km from the Martian surface, while for ionospheric sounding, it has already provided satisfactory results from a distance of up to 3000 km. Radar vertical resolution is about 150m (in free space), while horizontal resolution, in the range of a few kilometres, depends on the spacecraft's altitude. The joint Italian and American Marsis team is also largely involved in the Sharad radar, a facility instrument provided by ASI for NASA’s Mars Reconnaissance Orbiter (MRO), due for launch in August. Marsis and Sharad are two radars designed to provide complementary information about the Martian subsurface. Marsis can penetrate to an average depth of 5km, while Sharad will concentrate on layers closer to the surface.

  6. Recent upgrade of the MU radar and optical observation in the MLT region over Shigaraki, Japan.

    NASA Astrophysics Data System (ADS)

    Nakamura, T.; Kawahara, T.; Tsutsumi, M.; Shiokawa, K.

    The MU radar meteor echo observation has been used to derive precise horizontal wind velocities in the MLT region 80 - 100 km Relative temperature fluctuation can also be derived using ambipolar diffusion coefficient measured by decay time constants of meteor echoes Coordinated optical observations such as all-sky imagers FPI airglow photometers sodium and rayleigh lidars have been carried out in order to study atmospheric waves and dynamics structures of the MLT region Recently a sodium temperature lidar which was operated in Syowa Antarctica was moved to Uji near Shigaraki about 30 km west and started temperature profiling of the MLT region in 2005 The temperature profiles observed with this lidar provides important information of N 2 Buoyancy frequency squared in discussing vertical wave propagation and instability The coordinated observations with the new sodium lidar the MU radar and the airglow imager of OMTI optical mesosphere thermosphere imagers were conducted in October November 2005 Variations of wind temperature and sodium density showed significant effect of atmospheric tides Characteristics and propagations of the waves observed in the airglow imager are discussed using the temperature and wind data from the lidar and the radar We also present the new MU radar capability of ultra-multi channel digital receivers 25 channels and GPS synchronized radar operation which enables multichannel-multistatic meteor radar observations The plan of new meteor observations to derive high resolution horizontal

  7. 47 CFR 80.273 - Radar standards.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Radar standards. 80.273 Section 80.273... MARITIME SERVICES Equipment Authorization for Compulsory Ships § 80.273 Radar standards. (a) Radar... with radar must comply with the following standards (all incorporated by reference, see § 80.7):...

  8. 47 CFR 80.273 - Radar standards.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Radar standards. 80.273 Section 80.273... MARITIME SERVICES Equipment Authorization for Compulsory Ships § 80.273 Radar standards. (a) Radar... with radar must comply with the following standards (all incorporated by reference, see § 80.7):...

  9. FIRE_CI2_ETL_RADAR

    Atmospheric Science Data Center

    2015-11-25

    FIRE_CI2_ETL_RADAR Project Title:  FIRE II CIRRUS Discipline:  ... Platform:  Ground Station Instrument:  Radar Spatial Coverage:  (37.06, -95.34) Spatial ... Search Guide Documents:  ETL_RADAR Guide Readme Files:  Readme ETL_RADAR (PS) ...

  10. 47 CFR 80.273 - Radar standards.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Radar standards. 80.273 Section 80.273... MARITIME SERVICES Equipment Authorization for Compulsory Ships § 80.273 Radar standards. (a) Radar... with radar must comply with the following standards (all incorporated by reference, see § 80.7):...

  11. RADAR OBSERVATION CONDITIONS OF POOR VISIBILITY,

    DTIC Science & Technology

    Ship navigational radar is an effective means for revealing above-water objects in conditions of poor visibility. A radar image of the surrounding...radar observation and with the competent operation of the set, radar is a reliable means of detection of encountered vessels in conditions of poor

  12. Radar, Insect Population Ecology, and Pest Management

    NASA Technical Reports Server (NTRS)

    Vaughn, C. R. (Editor); Wolf, W. (Editor); Klassen, W. (Editor)

    1979-01-01

    Discussions included: (1) the potential role of radar in insect ecology studies and pest management; (2) the potential role of radar in correlating atmospheric phenomena with insect movement; (3) the present and future radar systems; (4) program objectives required to adapt radar to insect ecology studies and pest management; and (5) the specific action items to achieve the objectives.

  13. Evaluation of meteorological airborne Doppler radar

    NASA Technical Reports Server (NTRS)

    Hildebrand, P. H.; Mueller, C. K.

    1984-01-01

    This paper will discuss the capabilities of airborne Doppler radar for atmospheric sciences research. The evaluation is based on airborne and ground based Doppler radar observations of convective storms. The capability of airborne Doppler radar to measure horizontal and vertical air motions is evaluated. Airborne Doppler radar is shown to be a viable tool for atmospheric sciences research.

  14. Large phased-array radars

    SciTech Connect

    Brookner, D.E.

    1988-12-15

    Large phased-array radars can play a very important part in arms control. They can be used to determine the number of RVs being deployed, the type of targeting of the RVs (the same or different targets), the shape of the deployed objects, and possibly the weight and yields of the deployed RVs. They can provide this information at night as well as during the day and during rain and cloud covered conditions. The radar can be on the ground, on a ship, in an airplane, or space-borne. Airborne and space-borne radars can provide high resolution map images of the ground for reconnaissance, of anti-ballistic missile (ABM) ground radar installations, missile launch sites, and tactical targets such as trucks and tanks. The large ground based radars can have microwave carrier frequencies or be at HF (high frequency). For a ground-based HF radar the signal is reflected off the ionosphere so as to provide over-the-horizon (OTH) viewing of targets. OTH radars can potentially be used to monitor stealth targets and missile traffic.

  15. SAR (Synthetic Aperture Radar). Earth observing system. Volume 2F: Instrument panel report

    NASA Technical Reports Server (NTRS)

    1987-01-01

    The scientific and engineering requirements for the Earth Observing System (EOS) imaging radar are provided. The radar is based on Shuttle Imaging Radar-C (SIR-C), and would include three frequencies: 1.25 GHz, 5.3 GHz, and 9.6 GHz; selectable polarizations for both transmit and receive channels; and selectable incidence angles from 15 to 55 deg. There would be three main viewing modes: a local high-resolution mode with typically 25 m resolution and 50 km swath width; a regional mapping mode with 100 m resolution and up to 200 km swath width; and a global mapping mode with typically 500 m resolution and up to 700 km swath width. The last mode allows global coverage in three days. The EOS SAR will be the first orbital imaging radar to provide multifrequency, multipolarization, multiple incidence angle observations of the entire Earth. Combined with Canadian and Japanese satellites, continuous radar observation capability will be possible. Major applications in the areas of glaciology, hydrology, vegetation science, oceanography, geology, and data and information systems are described.

  16. Output tube emission characteristics of operational radars

    NASA Astrophysics Data System (ADS)

    Matheson, R. J.; Smilley, J. D.; Falcon, G. D.; Lawrence, V. S.

    1982-01-01

    Measurement of the emission spectra and other characteristics of many radars operating in the government frequency bands is described. The emission spectra of 19 different types of radars, selected to show the different emission spectrum characteristics produced by a variety of radar output tube technologies are presented. The radars include examples of ground based search, airport surveillance, weather, and height finding radars operating in L band, S band, or C band. The RSMS, contained within a mobile van, is described, along with the measurement techniques used for obtaining radar emission characteristics. The emission limits imposed by the Radar Spectrum Engineering Criteria (RSEC) are displayed with each emission spectrum.

  17. San Gabriel Mountains, California, Radar image, color as height

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This topographic radar image shows the relationship of the urban area of Pasadena, California to the natural contours of the land. The image includes the alluvial plain on which Pasadena and the Jet Propulsion Laboratory sit, and the steep range of the San Gabriel Mountains. The mountain front and the arcuate valley running from upper left to the lower right are active fault zones, along which the mountains are rising. The chaparral-covered slopes above Pasadena are also a prime area for wildfires and mudslides. Hazards from earthquakes, floods and fires are intimately related to the topography in this area. Topographic data and other remote sensing images provide valuable information for assessing and mitigating the natural hazards for cities along the front of active mountain ranges.

    This image combines two types of data from the Shuttle Radar Topography Mission. The image brightness corresponds to the strength of the radar signal reflected from the ground, while colors show the elevation as measured by SRTM. Colors range from blue at the lowest elevations to white at the highest elevations. This image contains about 2300 meters (7500 feet) of total relief. White speckles on the face of some of the mountains are holes in the data caused by steep terrain. These will be filled using coverage from an intersecting pass.

    The Shuttle Radar Topography Mission (SRTM), launched on February 11,2000, uses the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. The mission is designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, an additional C-band imaging antenna and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency

  18. Los Angeles, California, Radar Image, Wrapped Color as Height

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This topographic radar image shows the relationships of the dense urban development of Los Angeles and the natural contours of the land. The image includes the Pacific Ocean on the left, the flat Los Angeles Basin across the center, and the steep ranges of the Santa Monica and Verdugo mountains along the top. The two dark strips near the coast at lower left are the runways of Los Angeles International Airport. Downtown Los Angeles is the bright yellow and pink area at lower center. Pasadena, including the Rose Bowl, are seen half way down the right edge of the image. The communities of Glendale and Burbank, including the Burbank Airport, are seen at the center of the top edge of the image. Hazards from earthquakes, floods and fires are intimately related to the topography in this area. Topographic data and other remote sensing images provide valuable information for assessing and mitigating the natural hazards for cities such as Leangles.

    This image combines two types of data from the Shuttle Radar Topography Mission. The image brightness corresponds to the strength of the radar signal reflected from the ground, while colors show the elevation as measured by SRTM. Each cycle of colors (from pink through blue back to pink) represents an equal amount of elevation difference (400 meters, or 1300 feet) similar to contour lines on a standard topographic map. This image contains about 2400 meters (8000 feet) of total relief.

    The Shuttle Radar Topography Mission (SRTM), launched on February 11,2000, uses the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. The mission is designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, an additional C-band imaging antenna and improved tracking and navigation devices. The mission is a cooperative project between

  19. 3D measurements in the polar mesosphere using coherent radar imaging

    NASA Astrophysics Data System (ADS)

    Zecha, M.; Sommer, S.; Rapp, M.; Stober, G.; Latteck, R.

    2012-12-01

    Radars provide the opportunity of continuous measurements in the interesting area of the polar mesosphere. Usually the spatial resolution of measurements by pulsed VHF radars is limited by the radar beam width, transmitting pulse length, and sampling time. Due to these technical restrictions the typical small-scale structures in the mesosphere often cannot be resolved. Furthermore the quality of the estimation of dynamic atmosphere parameters is reduced if the position and direction of scatter returns cannot determined exactly. Radar interferometry methods have been developed to reduce these limitations. The coherent radar imaging method gives a high resolving image of the scatter structure insight the radar beam volume. In recent years the VHF radar MAARSY was installed in Andenes/Norway (69°N). This new radar was designed to allow improved three-dimensional observations in the atmosphere. It consists of 433 Yagis and allows a minimum beam width of about 4 degree. The beam direction can be changed pulse-by-pulse freely in azimuth angle and practicable up to 40 degree in zenith angle. The pulse length can be varied from a couple of km down to 50 m. Up to 16 receiving channels of spaced antennas can be used. In this presentation we show the detection of the angles-of-arrival of radar echoes and the correction of the wind measurements. We demonstrate the improvement of measurement results by using coherent radar imaging. The differences to the results of conventional methods depend on the beam width, range resolution, antenna distances, and beam tilting. We show that the application of interferometry is necessary to improve considerably the quality of 3D-measurement results. Furthermore we demonstrate the synthesis of high resolved images to get a real 3D image of the mesosphere.

  20. The Clementine bistatic radar experiment.

    PubMed

    Nozette, S; Lichtenberg, C L; Spudis, P; Bonner, R; Ort, W; Malaret, E; Robinson, M; Shoemaker, E M

    1996-11-29

    During the Clementine 1 mission, a bistatic radar experiment measured the magnitude and polarization of the radar echo versus bistatic angle, beta, for selected lunar areas. Observations of the lunar south pole yield a same-sense polarization enhancement around beta = 0. Analysis shows that the observed enhancement is localized to the permanently shadowed regions of the lunar south pole. Radar observations of periodically solar-illuminated lunar surfaces, including the north pole, yielded no such enhancement. A probable explanation for these differences is the presence of low-loss volume scatterers, such as water ice, in the permanently shadowed region at the south pole.

  1. Gyroklystron-Powered WARLOC Radar

    NASA Astrophysics Data System (ADS)

    Danly, B. G.; Cheung, W. J.; Gregers-Hansen, V.; Linde, G.; Ngo, M.

    2003-12-01

    A high-power, coherent, W-band (94 GHz) millimeter-wave radar has been developed at the Naval Research Laboratory. This radar, named WARLOC, employs a 100 kW peak power, 10 kW average power gyro-klystron as the final power amplifier, an overmoded transmission line system, and a quasi-optical duplexer, together with a high gain antenna, four-channel receiver, and state-of-the-art signal processing. The gyro-amplifiers and the implementation in the WARLOC radar will be described.

  2. The Clementine Bistatic Radar Experiment

    NASA Technical Reports Server (NTRS)

    Nozette, S.; Lichtenberg, C. L.; Spudis, P.; Bonner, R.; Ort, W.; Malaret, E.; Robinson, M.; Shoemaker, E. M.

    1996-01-01

    During the Clementine 1 mission, a bistatic radar experiment measured the magnitude and polarization of the radar echo versus bistatic angle, beta, for selected lunar areas. Observations of the lunar south pole yield a same-sense polarization enhancement around beta = 0. Analysis shows that the observed enhancement is localized to the permanently shadowed regions of the lunar south pole. Radar observations of periodically solar-illuminated lunar surfaces, including the north pole, yielded no such enhancement. A probable explanation for these differences is the presence of low-loss volume scatterers, such as water ice, in the permanently shadowed region at the south pole.

  3. The Clementine bistatic radar experiment

    USGS Publications Warehouse

    Nozette, S.; Lichtenberg, C.L.; Spudis, P.; Bonner, R.; Ort, W.; Malaret, E.; Robinson, M.; Shoemaker, E.M.

    1996-01-01

    During the Clementine 1 mission, a bistatic radar experiment measured the magnitude and polarization of the radar echo versus bistatic angle, ??, for selected lunar areas. Observations of the lunar south pole yield a same- sense polarization enhancement around ?? = 0. Analysis shows that the observed enhancement is localized to the permanently shadowed regions of the lunar south pole. Radar observations of periodically solar-illuminated lunar surfaces, including the north pole, yielded no such enhancement. A probable explanation for these differences is the presence of low-loss volume scatterers, such as water ice, in the permanently shadowed region at the south pole.

  4. Radar investigation of asteroids

    NASA Technical Reports Server (NTRS)

    Ostro, S. J.

    1982-01-01

    The dual polarization CW radar system which permits simultaneous reception in the same rotational sense of circular polarization as transmitted (i.e., the "SC" sense) and in the opposite ("OC") sense, was used to observe five previously unobserved asteroids: 2 Pallas, 8 Flora, 22 Kalliope, 132 Aethra, and 471 Papagena. Echoes from Pallas and Flora were easily detected in the OC sense on each of several nights. Weighted mean echo power spectra also show marginally significant responses in the SC sense. An approximately 4.5 standard deviation signal was obtained for Aethra. The Doppler shift of the peak is about 10 Hz higher than that predicted from the a priori trial ephemeris. Calculations are performed to determine whether this frequency offset can be reconciled dynamically with optical positions reported for Aethra.

  5. Radar investigation of asteroids

    NASA Astrophysics Data System (ADS)

    Ostro, S. J.

    1981-07-01

    Radar investigations were conducted of selected minor planets, including: (1) observations during 1981-82 of 10 potential targets (2 Pallas, 8 Flora, 12 Victoria, 15 Eunomia, 19 Fortuna, 22 Kalliope, 132 Aethra, 219 Thusnelda, 433 Eros, and 2100 Ra-Shalom); and (2) continued analyses of observational data obtained during 1980-81 for 10 other asteroids (4 Vesta, 7 Iris, 16 Psyche, 75 Eurydike, 97 Klotho, 216 Kleopatra, 1685 Toro, 1862 Apollo, 1865 Cerberus, and 1915 Quetzalcoatl). Scientific objectives include estimation of echo strength, polarization, spectral shape, spectral bandwidth, and Doppler shift. These measurements: (1) yield estimates of target size, shape, and spin vector; (2) place constraints on topography, morphology, and composition of the planetary surface; (3) yield refined estimates of target orbital parameters; (4) reveal the presence of asteroidal satellites.

  6. Application of the staring-edge tracking in laser radar

    NASA Astrophysics Data System (ADS)

    He, Lianhe; Wu, Jian

    1997-04-01

    The extended target that the size is larger that the diameter of the light beam can be tracked in the laser tracking radar designed on the basic of the method and the algorithm of the staring edge tracking. A moving aluminium plate is tracked by a coherent CO2 laser tracking radar facility with transmitter power 5W and the divergent angle of the transmitter light beam less than 0.18 mrad at a n approximate range of 1 km. The error signals of the azimuth and the elevation are generated from the quad detector. This successful experiment results indicates that the question that the traditional tracking method of quad detector is vain to the extended target has been overcome and testifies that our theory of the staring edge tracking is correct. This tracking method has many advantages. For example, is we choose the tracking position at the top of the target, then the ground target is not easy to lose. So it can avoid tracking the ground. On the other hand, the range of the laser radar using this method is longer than the range of the radar using the point tracking, because the target using narrow light beam illumination is taken as an extended Lambertian target.

  7. Fluvial channels on Titan: Initial Cassini RADAR observations

    USGS Publications Warehouse

    Lorenz, R.D.; Lopes, R.M.; Paganelli, F.; Lunine, J.I.; Kirk, R.L.; Mitchell, K.L.; Soderblom, L.A.; Stofan, E.R.; Ori, G.; Myers, M.; Miyamoto, H.; Radebaugh, J.; Stiles, B.; Wall, S.D.; Wood, C.A.

    2008-01-01

    Cassini radar images show a variety of fluvial channels on Titan's surface, often several hundreds of kilometers in length. Some (predominantly at low- and mid-latitude) are radar-bright and braided, resembling desert washes where fines have been removed by energetic surface liquid flow, presumably from methane rainstorms. Others (predominantly at high latitudes) are radar-dark and meandering and drain into or connect polar lakes, suggesting slower-moving flow depositing fine-grained sediments. A third type, seen predominantly at mid- and high latitudes, have radar brightness patterns indicating topographic incision, with valley widths of up to 3 km across and depth of several hundred meters. These observations show that fluvial activity occurs at least occasionally at all latitudes, not only at the Huygens landing site, and can produce channels much larger in scale than those observed there. The areas in which channels are prominent so far amount to about 1% of Titan's surface, of which only a fraction is actually occupied by channels. The corresponding global sediment volume inferred is not enough to account for the extensive sand seas. Channels observed so far have a consistent large-scale flow pattern, tending to flow polewards and eastwards. ?? 2008.

  8. Mesocyclones in Central Europe as seen by radar

    NASA Astrophysics Data System (ADS)

    Wapler, Kathrin; Hengstebeck, Thomas; Groenemeijer, Pieter

    2016-02-01

    The occurrence and characteristics of mesocyclones in Central Europe as seen by radar are analysed. A three year analysis shows an annual and diurnal cycle with a wider maximum in the late afternoon/evening compared to the diurnal cycle of general thunderstorms. Analysis of F2 tornado events and over a hundred hail storms show the characteristics of the corresponding mesocyclones as seen by radar. For all of the six F2 tornadoes in the three-year period in Germany a corresponding mesocyclone could be detected in radar data. Furthermore the analysis reveals that about half of all hail storms in Germany are associated with a mesocyclone detected in radar data within 10 km and 10 min. Some mesocyclone attributes, e.g. depth and maximum shear, and of the associated convective cell, e.g. reflectivity related parameters VIL, VILD and echotop, have predictive skill for indicating the occurrence of hail. The mesocyclone detection algorithm may support the analysis and nowcasting of severe weather events and thus support the warning process.

  9. Searching for Cosmic Ray Radar Echos In TARA Data

    NASA Astrophysics Data System (ADS)

    Myers, Isaac

    2013-04-01

    The TARA (Telescope Array Radar) cosmic ray detector has been in operation for about a year and half. This bi-static CW radar detector was designed with the goal of detecting cosmic rays in coincidence with Telescope Array (TA). For the majority of its operation it has been in the TARA1.5 phase in which a 1.5 kW transmitter broadcasts from a single Yagi antenna across the TA surface detector array to our receiver station 50 km away. Our initial DAQ system has obtained millions of triggers utilizing a USRP2 PC controlled radio. During recent months, we have commissioned a 250 MHz sample rate detector with an intelligent self-triggering algorithm that can detect radar echo chirp signals below the noise. I will describe the stages of analysis used for comparing TARA radar triggers with TA data and present a synopsis of the analysis of the USRP2 data and preliminary results from the more advanced DAQ system.

  10. C-Band Radar Imagery, Dallas-Fort Worth, Texas

    NASA Technical Reports Server (NTRS)

    2000-01-01

    The Dallas-Fort Worth metropolitan area in Texas is shown on this image collected by the C-band radar of the Shuttle Radar Topography Mission (SRTM). On this radar image, smooth areas, such as lakes, roads and airport runways appear dark. Rougher features, such as buildings and trees, appear bright. Downtown Dallas is the bright area at the center of the image, alongside the dark linear floodway of the Trinity River. Dark linear runways of two airports are also seen: Love Field near downtown Dallas in the image center, and Dallas-Fort Worth International Airport in the upper left corner. The semi-circular terminal buildings of the international airport can also be seen in the area between the runways. Several large lakes, including Lake Ray Hubbard (upper right) and Joe Pool Lake (lower left) are also seen. Images like these, along with the SRTM topographic data, will be used by urban planners to study and monitor land use, and update maps and geographic information systems for the area. This image represents just 4 seconds of data collection time by the SRTM instrument. The overall diagonal linear pattern is a data processing artifact due to the quick turn-around browse nature of this image. These artifacts will be removed with further data processing.

    This radar image was obtained by the Shuttle Radar Topography Mission as part of its mission to map the Earth's topography. The image was acquired by just one of SRTM's two antennas, and consequently does not show topographic data but only the strength of the radar signal reflected from the ground. This signal, known as radar backscatter, provides insight into the nature of the surface, including its roughness, vegetation cover, and urbanization.

    This image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM uses the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR

  11. Studies on Radar and Non-radar Sensor Networks

    DTIC Science & Technology

    2006-06-15

    selection based on specific applications. References [1] Q . Liang, "Waveform Design and Diversity in Radar Sensor Networks: Theoretical Analysis and...Application to Automatic Target Recognition," submitted to IEEE Trans on Aerospace and Electronic Systems. [2] Q . Liang, "Waveform Design and Diversity in...Sensor Networks, June 2006, New York. [3] Q . Liang, "Radar Sensor Networks: Algorithms for Waveform Design and Diversity with Appli- cation to ATR with

  12. Historical aspects of radar atmospheric dynamics

    NASA Technical Reports Server (NTRS)

    Kato, Susumu

    1989-01-01

    A review of the history of radar techniques which have been applied to atmospheric observation is given. The author starts with ionosphere observation with the ionosonde, symbolizing as it does the earliest history of radar observation, and proceeds to later developments in radar observation such as the use of partial reflection, meteor, and incoherent scatter radars. Mesosphere stratosphere troposphere (MST) radars are discussed in terms of lower atmosphere observation.

  13. Elliptical storm cell modeling of digital radar data

    NASA Technical Reports Server (NTRS)

    Altman, F. J.

    1972-01-01

    A model for spatial distributions of reflectivity in storm cells was fitted to digital radar data. The data were taken with a modified WSR-57 weather radar with 2.6-km resolution. The data consisted of modified B-scan records on magnetic tape of storm cells tracked at 0 deg elevation for several hours. The MIT L-band radar with 0.8-km resolution produced cross-section data on several cells at 1/2 deg elevation intervals. The model developed uses ellipses for contours of constant effective-reflectivity factor Z with constant orientation and eccentricity within a horizontal cell cross section at a given time and elevation. The centers of the ellipses are assumed to be uniformly spaced on a straight line, with areas linearly related to log Z. All cross sections are similar at different heights (except for cell tops, bottoms, and splitting cells), especially for the highest reflectivities; wind shear causes some translation and rotation between levels. Goodness-of-fit measures and parameters of interest for 204 ellipses are considered.

  14. Size estimate of (99942) Apophis based on radar imaging

    NASA Astrophysics Data System (ADS)

    Brozovic, Marina; Benner, Lance; McMichael, Joseph; Pravec, Petr; Scheirich, Petr; Giorgini, Jon; Magri, Chris; Busch, Michael; Jao, Joseph; Lee, Clement; Nolan, Michael; Taylor, Patrick; Howell, Ellen; Slade, Martin

    2015-11-01

    (99942) Apophis is one of the most important near-Earth asteroids ever discovered. It will make a very close Earth approach on Friday, April 13, 2029 when it will pass within only a few Earth radii above Earth's surface. This will be the closest approach by something this large currently known. Apophis approached within 0.1 au in January of 2013, and we organized an extensive radar campaign at Goldstone and Arecibo between December 2012 and March 2013. Our primary objective was to obtain ranging measurements to improve the orbit, characterize its physical properties, and facilitate detection of the Yarkovsky effect leading to estimation of the mass and bulk density. We obtained frequency-only data, and 150 m and 75 m ranging data. The signal-to-noise ratios (SNRs) were strong enough so that coarsely resolved delay-Doppler images revealed aspects of Apophis’ shape. The visible extents varied from ~0.2 km to ~0.4 km and the bandwidths varied from 0.9 Hz to1.4 Hz. The object is clearly elongated, which is consistent with the large lightcurve amplitude of ~0.9 mag reported by Behrend et al. ( http://obswww.unige.ch/~behrend/r099942a.png) and Pravec et al. (Icarus 233, 48-60, 2014). The radar images suggest that Apophis could be a contact binary.Pravec et al. have estimated the shape and spin of Apophis from lightcurves that were collected at similar times as our radar data. The radar data were not strong enough for 3D shape modeling, but we used the Shape software (Hudson, Remote Sens. Rev. 8, 195-203, 1993 and Magri et al., Icarus 186, 152-177, 2007) to scale the convex lightcurve-derived shape model to fit the radar data. We find that the best χ2 value corresponds to the model that has 0.43×0.30×0.26 (±0.04, ±0.03, ±0.03) km for long, intermediate, and short axis, and a dynamically equivalent, equal volume ellipsoid of 0.31±0.03 km.

  15. Venus mountain-top mineralogy: Misconceptions about pyrite as the high radar-reflecting phase

    NASA Technical Reports Server (NTRS)

    Burns, Roger G.; Straub, Darcy W.

    1993-01-01

    Altitude-dependent, high radar-reflectivity surfaces on Venus are observed on most mountainous volcanic terranes above a planetary radius of about 6054 km. However, high radar-reflectivity areas also occur at lower altitudes in some impact craters and plain terranes. Pyrite (FeS2) is commonly believed to be responsible for the high radar reflectivities at high elevations on Venus, on account of large dielectric constants measured for sulfide-bearing rocks that were erroneously attributed to pyrite instead of pyrrhotite. Pentlandite-pyrrhotite assemblages may be responsible for high reflectivities associated with impact craters on the Venusian surface, by analogy with Fe-Ni sulfide deposits occurring in terrestrial astroblemes. Mixed-valence Fe(2+)-Fe(3+) silicates, including oxyhornblende, oxybiotite, and ilvaite, may contribute to high radar reflecting surfaces on mountain-tops of Venus.

  16. Fly eye radar or micro-radar sensor technology

    NASA Astrophysics Data System (ADS)

    Molchanov, Pavlo; Asmolova, Olga

    2014-05-01

    To compensate for its eye's inability to point its eye at a target, the fly's eye consists of multiple angularly spaced sensors giving the fly the wide-area visual coverage it needs to detect and avoid the threats around him. Based on a similar concept a revolutionary new micro-radar sensor technology is proposed for detecting and tracking ground and/or airborne low profile low altitude targets in harsh urban environments. Distributed along a border or around a protected object (military facility and buildings, camp, stadium) small size, low power unattended radar sensors can be used for target detection and tracking, threat warning, pre-shot sniper protection and provides effective support for homeland security. In addition it can provide 3D recognition and targets classification due to its use of five orders more pulses than any scanning radar to each space point, by using few points of view, diversity signals and intelligent processing. The application of an array of directional antennas eliminates the need for a mechanical scanning antenna or phase processor. It radically decreases radar size and increases bearing accuracy several folds. The proposed micro-radar sensors can be easy connected to one or several operators by point-to-point invisible protected communication. The directional antennas have higher gain, can be multi-frequency and connected to a multi-functional network. Fly eye micro-radars are inexpensive, can be expendable and will reduce cost of defense.

  17. Fine resolution topographic mapping of the Jovian moons: a Ka-band high resolution topographic mapping interferometric synthetic aperture radar

    NASA Technical Reports Server (NTRS)

    Madsen, Soren N.; Carsey, Frank D.; Turtle, Elizabeth P.

    2003-01-01

    The topographic data set obtained by MOLA has provided an unprecedented level of information about Mars' geologic features. The proposed flight of JIMO provides an opportunity to accomplish a similar mapping of and comparable scientific discovery for the Jovian moons through us of an interferometric imaging radar analogous to the Shuttle radar that recently generated a new topographic map of Earth. A Ka-band single pass across-track synthetic aperture radar (SAR) interferometer can provide very high resolution surface elevation maps. The concept would use two antennas mounted at the ends of a deployable boom (similar to the Shuttle Radar Topographic Mapper) extended orthogonal to the direction of flight. Assuming an orbit altitude of approximately 100 km and a ground velocity of approximately 1.5 km/sec, horizontal resolutions at the 10 meter level and vertical resolutions at the sub-meter level are possible.

  18. Fine Resolution Topographic Mapping of the Jovian Moons: A Ka-Band High Resolution Topographic Mapping Interferometric Synthetic Aperture Radar

    NASA Technical Reports Server (NTRS)

    Madsen, S. N.; Carsey, F. D.; Turtle, E. P.

    2003-01-01

    The topographic data set obtained by MOLA has provided an unprecedented level of information about Mars' geologic features. The proposed flight of JIMO provides an opportunity to accomplish a similar mapping of and comparable scientific discovery for the Jovian moons through use of an interferometric imaging radar analogous to the Shuttle radar that recently generated a new topographic map of Earth. A Ka-band single pass across-track synthetic aperture radar (SAR) interferometer can provide very high resolution surface elevation maps. The concept would use two antennas mounted at the ends of a deployable boom (similar to the Shuttle Radar Topographic Mapper) extended orthogonal to the direction of flight. Assuming an orbit altitude of approximately 100km and a ground velocity of approximately 1.5 km/sec, horizontal resolutions at the 10 meter level and vertical resolutions at the sub-meter level are possible.

  19. Space radar image of Sunbury, Pennsylvania

    NASA Technical Reports Server (NTRS)

    1995-01-01

    Scientists are using this radar image of the area surrounding Sunbury, Pennsylvania to study the geologic structure and land use patterns in the Appalachian Valley and Ridge province. This image was collected on October 6, 1994 by the Spaceborne Imaging Radar-C/ X-Band Synthetic Aperture Radar (SIR-C/X-SAR) on orbit 102 of the space shuttle Endeavour. The image is centered on latitude 40.85 degrees North latitude and 76.79 degrees West longitude. The area shown is approximately 30.5 km by 38 km.(19 miles by 24 miles). North is towards the upper right of the image. The Valley and Ridge province occurs in the north-central Appalachians, primarily in Pennsylvania, Maryland, and Virginia. It is an area of adjacent valleys and ridges that formed when the Appalachian mountain were created some 370 to 390 million years ago. During the continental collision that formed the Appalachians, the rocks in this area were pushed from the side and buckled much like a rug when pushed from one end. Subsequent erosion has produced the landscape we see in this image. The more resistant rocks, such as sandstone, form the tops of the ridges which appear as forested greenish areas on this image. The less resistant rocks, such as limestone, form the lower valleys which are cleared land and farm fields and are purple in this image. Smaller rivers and streams in the area flow along the valleys and in places cut across the ridges in 'water gaps.' In addition to defining the geography of this region, the Valley and Ridge province also provides this area with natural resources. The valleys provide fertile farmland and the folded mountains form natural traps for oil and gas accumulation; coal deposits are also found in the mountains. The colors in the image are assigned to different frequencies and polarizations of the SIR-C radar as follows: red is L-band horizontally transmitted, horizontally received; green is L-band horizontally transmitted, vertically received; blue is C-band horizontally

  20. Precipitation Estimation from the ARM Distributed Radar Network During the MC3E Campaign

    NASA Astrophysics Data System (ADS)

    Theisen, A. K.; Giangrande, S. E.; Collis, S. M.

    2012-12-01

    The DOE - NASA Midlatitude Continental Convective Cloud Experiment (MC3E) was the first demonstration of the Atmospheric Radiation Measurement (ARM) Climate Research Facility scanning precipitation radar platforms. A goal for the MC3E field campaign over the Southern Great Plains (SGP) facility was to demonstrate the capabilities of ARM polarimetric radar systems for providing unique insights into deep convective storm evolution and microphysics. One practical application of interest for climate studies and the forcing of cloud resolving models is improved Quantitative Precipitation Estimates (QPE) from ARM radar systems positioned at SGP. This study presents the results of ARM radar-based precipitation estimates during the 2-month MC3E campaign. Emphasis is on the usefulness of polarimetric C-band radar observations (CSAPR) for rainfall estimation to distances within 100 km of the Oklahoma SGP facility. Collocated ground disdrometer resources, precipitation profiling radars and nearby surface Oklahoma Mesonet gauge records are consulted to evaluate potential ARM radar-based rainfall products and optimal methods. Rainfall products are also evaluated against the regional NEXRAD-standard observations.

  1. Complementary code and digital filtering for detection of weak VHF radar signals from the mesoscale

    NASA Astrophysics Data System (ADS)

    Schmidt, G.; Ruster, R.; Czechowsky, P.

    1983-12-01

    The SOUSY-VHF-Radar operates at a frequency of 53.5 MHz in a valley in the Harz mountains, Germany, 90 km from Hanover. The radar controller, which is programmed by a 16-bit computer holds 1024 program steps in core and controls, via 8 channels, the whole radar system: in particular the master oscillator, the transmitter, the transmit-receive-switch, the receiver, the analog to digital converter, and the hardware adder. The high-sensitivity receiver has a dynamic range of 70 dB and a video bandwidth of 1 MHz. Phase coding schemes are applied, in particular for investigations at mesospheric heights, in order to carry out measurements with the maximum duty cycle and the maximum height resolution. The computer takes the data from the adder to store it in magnetic tape or disc. The radar controller is programmed by the computer using simple FORTRAN IV statements. After the program has been loaded and the computer has started the radar controller, it runs automatically, stopping at the program end. In case of errors or failures occurring during the radar operation, the radar controller is shut off caused either by a safety circuit or by a power failure circuit or by a parity check system.

  2. Talemzane - Algerian impact crater detected on SIR-A orbital imaging radar

    NASA Technical Reports Server (NTRS)

    Mchone, John F.; Greeley, Ronald

    1987-01-01

    In November, 1981, NASA's first Shuttle Imaging Radar mission (SIR-A) began producing maplike photographic strips of Earth scenes from orbital altitude. A Saharan radar image acquired over Algeria clearly delineates two sedimentary basins, Erg Occidental and Erg Oriental, separated by an elongated zone of exposed bedrock, the M'Zab Chebka. At the NE margin of the Chebka, rimrocks, slopes, and ejecta deposits of Talemzane meteorite impact crater appear as a distinct two km wide radar-bright ring. This unique circle of strong radar backscatter distinguishes the solitary impact structure from numerous dayas (similarly appearing karstic depressions) which characterize the region. The crater is prominent on radar, but is obscure on optically obtained satellite and aircraft images, as are partly buried fluvial drainage systems and fault-block traces developed in bedrocks of the Chebka. Radar detection of an annular drainage system indicates possible presence of a ring graben at the crater. Brightest radar signals on the image are cultural features at recently developed gas fields near Hassi er R'Mel.

  3. MODIS 3km Aerosol Product: Algorithm and Global Perspective

    NASA Technical Reports Server (NTRS)

    Remer, L. A.; Mattoo, S.; Levy, R. C.; Munchak, L.

    2013-01-01

    After more than a decade of producing a nominal 10 km aerosol product based on the dark target method, the MODIS aerosol team will be releasing a nominal 3 km product as part of their Collection 6 release. The new product differs from the original 10 km product only in the manner in which reflectance pixels are ingested, organized and selected by the aerosol algorithm. Overall, the 3 km product closely mirrors the 10 km product. However, the finer resolution product is able to retrieve over ocean closer to islands and coastlines, and is better able to resolve fine aerosol features such as smoke plumes over both ocean and land. In some situations, it provides retrievals over entire regions that the 10 km product barely samples. In situations traditionally difficult for the dark target algorithm, such as over bright or urban surfaces the 3 km product introduces isolated spikes of artificially high aerosol optical depth (AOD) that the 10 km algorithm avoids. Over land, globally, the 3 km product appears to be 0.01 to 0.02 higher than the 10 km product, while over ocean, the 3 km algorithm is retrieving a proportionally greater number of very low aerosol loading situations. Based on collocations with ground-based observations for only six months, expected errors associated with the 3 km land product are determined to be greater than for the 10 km product: 0.05 0.25 AOD. Over ocean, the suggestion is for expected errors to be the same as the 10 km product: 0.03 0.05 AOD. The advantage of the product is on the local scale, which will require continued evaluation not addressed here. Nevertheless, the new 3 km product is expected to provide important information complementary to existing satellite-derived products and become an important tool for the aerosol community.

  4. Goldstone/VLA Radar Observations of Near-Earth Asteroid 4179 Toutatis in 2012

    NASA Astrophysics Data System (ADS)

    Busch, Michael W.; Brozovic, M.; Benner, L.; Giorgini, J. D.; Takahashi, Y.; Scheeres, D. J.

    2013-10-01

    Near-Earth asteroid 4179 Toutatis is close to a 4:1 orbital resonance with Earth. It has been observed extensively with radar during close Earth flybys in 1992, 1996, 2000, 2004, 2008, and 2012. Previous radar observations have shown that Toutatis is bifurcated, ~4.5 km long, with an unusual non-principal-axis spin state. In December of 2012, Toutatis approached within 0.0463 AU (6.93 million km) of Earth, the last flyby within 0.2 AU until 2069. We conducted an extensive campaign of radar imaging and radar speckle tracking with Goldstone and with elements of the Very Large Array. The radar images were obtained on 16 days between December 4 and December 22 and include time on December 13 when the Chang’e 2 spacecraft flew by the asteroid. The radar images on December 12 and 13 had range resolution of 3.75 m/pixel and show a wealth of surface features, many previously unseen, including radar-bright spots that we interpret as decameter-scale boulders similar to those visible in the Chang’e 2 images. Both the 2012 radar images and the spacecraft images confirm the radar-based Toutatis shape model published by Hudson et al. 2003 (Icarus 161, 346-355) but also show where that model can be improved - particularly the big end of Toutatis, which was not imaged extensively by radar prior to 2012. During each orbit, Toutatis’ spin state changes by up to 0.1% of the asteroid’s total angular momentum due to gravitational tides from the Sun and Earth. We have constructed a model of Toutatis’ spin state in which we numerically integrate the tidal torques on the asteroid to match the orientation of Toutatis at each apparition. The tidal spin state changes and the non-principal-axis rotation allow us to estimate Toutatis’ moments of inertia independently of its shape. We will present the 2012 radar images and describe our current knowledge of the asteroid’s shape and spin state. The unprecedented resolution and orientation coverage of the 2012 radar data and Chang

  5. Multifrequency radar imaging of ash plumes: an experiment at Stromboli

    NASA Astrophysics Data System (ADS)

    Donnadieu, Franck; Freret-Lorgeril, Valentin; Delanoë, Julien; Vinson, Jean-Paul; Peyrin, Frédéric; Hervier, Claude; Caudoux, Christophe; Van Baelen, Joël; Latchimy, Thierry

    2016-04-01

    Volcanic ash emissions in the atmosphere are hazardous to aviation while ash fallout affects people and human activities and may cause damage to infrastructures and economic losses. In the framework of the French Government Laboratory of Excellence ClerVolc initiative, an experiment was carried out on Stromboli volcano (Italy), between 28 September and 4 October 2015. The aim was to retrieve various physical properties of the ash plumes, especially the mass loading parameters which are critical for the modelling of ash dispersal. We used a complementary set of cutting edge techniques recording in different bands of the electromagnetic spectrum. The innovative instrument setup consisted in three radars, hyperspectral thermal infrared and dual-band UV cameras, a mini DOAS-Flyspec and a multigas sensor. A drone equipped with differential GPS was flown near the ash plumes with several sensors including SO2, CO2 and particle counter. We mainly focus on radar measurements of over 200 ash plumes and present some preliminary comparisons at three frequencies. The BASTA Doppler radar at 95 GHz, originally designed for atmospheric studies, was deployed at about 2.2 km in slant distance from the eruptive craters. It was configured to observe volumes above one of the active craters with a spatio-temporal resolution of 12.5 m and 1 s. From the same location, a 1.2 GHz volcano Doppler radar (VOLDORAD) was recording the signature of ballistics and small lapilli at 0.15 s in 60 m-deep volumes. In addition, a commercial 24 GHz micro rain Doppler radar (MRR) simultaneously recorded activity from the Rochette station, at 400 to 650 m from the active craters with a sampling rate of 10 s and a resolution of 25 m. The latter was pointing almost perpendicularly to the other radar beams. Reflectivity factors were measured inside the ash plume above the source vent by the BASTA radar (3 mm wavelength) spanning -9 to +21 dBZ. Fallout could sometimes be tracked during several minutes within

  6. European coordination for coastal HF radar data in EMODnet Physics

    NASA Astrophysics Data System (ADS)

    Mader, Julien; Novellino, Antonio; Gorringe, Patrick; Griffa, Annalisa; Schulz-Stellenfleth, Johannes; Montero, Pedro; Montovani, Carlo; Ayensa, Garbi; Vila, Begoña; Rubio, Anna; Sagarminaga, Yolanda

    2015-04-01

    Historically, joint effort has been put on observing open ocean, organizing, homogenizing, sharing and reinforcing the impact of the acquired information based on one technology: ARGO with profilers Argo floats, EuroSites, ESONET-NoE, FixO3 for deep water platforms, Ferrybox for stations in ships of opportunities, and GROOM for the more recent gliders. This kind of networking creates synergies and makes easier the implementation of this source of data in the European Data exchange services like EMODnet, ROOSs portals, or any applied services in the Blue economy. One main targeted improvement in the second phase of EMODnet projects is the assembling of data along coastline. In that sense, further coordination is recommended between platform operators around a specific technology in order to make easier the implementation of the data in the platforms (4th EuroGOOS DATAMEQ WG). HF radar is today recognized internationally as a cost-effective solution to provide high spatial and temporal resolution current maps (depending on the instrument operation frequency, covering from a few kilometres offshore up to 200 km) that are needed for many applications for issues related to ocean surface drift or sea state characterization. Significant heterogeneity still exists in Europe concerning technological configurations, data processing, quality standards and data availability. This makes more difficult the development of a significant network for achieving the needed accessibility to HF Radar data for a pan European use. EuroGOOS took the initiative to lead and coordinate activities within the various observation platforms by establishing a number of Ocean Observing Task Teams such as HF-Radars. The purpose is to coordinate and join the technological, scientific and operational HF radar communities at European level. The goal of the group is on the harmonization of systems requirements, systems design, data quality, improvement and proof of the readiness and standardization of

  7. Ground Penetrating Radar, Barrow, Alaska

    DOE Data Explorer

    John Peterson

    2015-03-06

    This is 500 MHz Ground Penetrating Radar collected along the AB Line in Intensive Site 1 beginning in October 2012 and collected along L2 in Intensive Site 0 beginning in September 2011. Both continue to the present.

  8. NASA Radar Images Asteroid Toutatis

    NASA Video Gallery

    This 64-frame movie of asteroid Toutatis was generated from data by Goldstone's Solar System Radar on Dec. 12 and 13, 2012. In the movie clips, the rotation of the asteroid appears faster than it o...

  9. GPS-aided gravimetry at 30 km altitude from a balloon-borne platform

    NASA Technical Reports Server (NTRS)

    Lazarewicz, Andrew R.; Evans, Alan G.

    1989-01-01

    A balloon-borne experiment, flown at 30 km altitude over New Mexico, was used to test dynamic differential Global Positioning System (GPS) tracking in support of gravimetry at high-altitudes. The experiment package contained a gravimeter (Vibrating String Accelerometer), a full complement of inertial instruments, a TI-4100 GPS receiver and a radar transponder. The flight was supported by two GPS receivers on the ground near the flight path. From the 8 hour flight, about a forty minute period was selected for analysis. Differential GPS phase measurements were used to estimate changes in position over the sample time interval, or average velocity. In addition to average velocity, differential positions and numerical averages of acceleration were obtained in three components. Gravitational acceleration was estimated by correcting for accelerations due to translational motion, ignoring all rotational effects.

  10. Lower thermosphere (80-100 km) dynamics response to solar and geomagnetic activity: Overview

    NASA Technical Reports Server (NTRS)

    Kazimirovsky, E. S.

    1989-01-01

    The variations of solar and geomagnetic activity may affect the thermosphere circulation via plasma heating and electric fields, especially at high latitudes. The possibility exists that the energy involved in auroral and magnetic storms can produce significant changes of mesosphere and lower thermosphere wind systems. A study of global radar measurements of winds at 80 to 100 km region revealed the short term effects (correlation between wind field and geomagnetic storms) and long term variations over a solar cycle. It seems likely that the correlation results from a modification of planetary waves and tides propagated from below, thus altering the dynamical regime of the thermosphere. Sometimes the long term behavior points rather to a climatic variation with the internal atmospheric cause than to a direct solar control.

  11. Advanced Borehole Radar for Hydrogeology

    NASA Astrophysics Data System (ADS)

    Sato, M.

    2014-12-01

    Ground Penetrating Radar is a useful tool for monitoring the hydrogeological environment. We have developed GPR systems which can be applied to these purposes, and we will demonstrate examples borehole radar measurements. In order to have longer radar detection range, frequency lower than100MHz has been normally adopted in borehole radar. Typical subsurface fractures of our interests have a few mm aperture and radar resolution is much poorer than a few cm in this frequency range. We are proposing and demonstrating to use radar polarimetry to solve this problem. We have demonstrated that a full-polarimetry borehole radar can be used for characterization of subsurface fractures. Together with signal processing for antenna characteristic compensation to equalize the signal by a dipole antenna and slot antennas, we could demonstrate that polarimetric borehole radar can estimate the surface roughness of subsurface fractures, We believe the surface roughness is closely related to water permeability through the fractures. We then developed a directional borehole radar, which uses optical field sensor. A dipole antenna in a borehole has omni-directional radiation pattern, and we cannot get azimuthal information about the scatterers. We use multiple dipole antennas set around the borehole axis, and from the phase differences, we can estimate the 3-diemnational orientation of subsurface structures. We are using optical electric field sensor for receiver of borehole radar. This is a passive sensor and connected only with optical fibers and does not require any electric power supply to operate the receiver. It has two major advantages; the first one is that the receiver can be electrically isolated from other parts, and wave coupling to a logging cable is avoided. Then, secondary, it can operate for a long time, because it does not require battery installed inside the system. It makes it possible to set sensors in fixed positions to monitor the change of environmental

  12. The NASA Polarimetric Radar (NPOL)

    NASA Technical Reports Server (NTRS)

    Petersen, Walter A.; Wolff, David B.

    2013-01-01

    Characteristics of the NASA NPOL S-band dual-polarimetric radar are presented including its operating characteristics, field configuration, scanning capabilities and calibration approaches. Examples of precipitation science data collections conducted using various scan types, and associated products, are presented for different convective system types and previous field campaign deployments. Finally, the NASA NPOL radar location is depicted in its home base configuration within the greater Wallops Flight Facility precipitation research array supporting NASA Global Precipitation Measurement Mission ground validation.

  13. Radar Imaging and Target Identification

    DTIC Science & Technology

    2009-02-09

    Methods in Wave Propagation, Vaxjo, Swe- den. • February 19, 2008, "Radar Imaging", math colloquium, Brigham- Young University. • January 31, 2008...manuscript, namely "Radar detection using sparsely distributed 19 apertures in urban environments", Ling Wang, II- Young Son, Trond Varslot, C. Evren...Coinmun. COM- 20, pp. 774-780, 1972. [24] M. Tomlinson, "New automatic equalizer employing modulo arithmetic," Electron. Lett. 7, pp. 138-139, 1971

  14. Synthetic Aperture Radar Simulation Study

    DTIC Science & Technology

    1984-03-01

    multilook are discussed. A chapter is devoted to elevation and planimetric data bases. In addition, six- teen pictures of SAR images from Hughes Aircraft, as...scans. Figure 5.4-1 is a photograph ot two SAR displays. The tirst display is made up ot six subscans and has a multilook ot one. Note that tading is...dentfi by block number) * Synthetic Aperture Radar ( SAR ) Simulation Study Radar Simulation Data Bases 5/~t. 4th.- Computer Image Generation Display 20

  15. The use of radar and LANDSAT data for mineral and petroleum exploration in the Los Andes region, Venezuela

    NASA Technical Reports Server (NTRS)

    Vincent, R. K.

    1980-01-01

    A geological study of a 27,500 sq km area in the Los Andes region of northwestern Venezuela was performed which employed both X-band radar mosaics and computer processed Landsat images. The 3.12 cm wavelength radar data were collected with horizontal-horizontal polarization and 10 meter spatial resolution by an Aeroservices SAR system at an altitude of 12,000 meters. The radar images increased the number of observable suspected fractures by 27 percent over what could be mapped by LANDSAT alone, owing mostly to the cloud cover penetration capabilities of radar. The approximate eight fold greater spatial resolution of the radar images made possible the identification of shorter, narrower fractures than could be detected with LANDSAT data alone, resulting in the discovery of a low relief anticline that could not be observed in LANDSAT data. Exploration targets for petroleum, copper, and uranium were identified for further geophysical work.

  16. Representing radar QPE and QPF uncertainties using radar ensembles

    NASA Astrophysics Data System (ADS)

    Sempere-Torres, D.; Llort, X.; Roca, J.; Pegram, G.

    2009-09-01

    In the last years, new comprehension of the physics underlying the radar measurements as well as new technological advancements have allowed radar community to propose better algorithms and methodologies and significant advancements have been achieved in improving Quantitative Precipitation Estimates (QPE) and Quantitative Precipitation forecasting (QPF) by radar. Thus the study of the 2D uncertainties field associated to these estimates has become an important subject, specially to enhance the use of radar QPE and QPF in hydrological studies, as well as in providing a reference for satellite precipitations measurements. In this context the use of radar-based rainfall ensembles (i.e. equiprobable rainfall field scenarios generated to be compatible with the observations/forecasts and with the inferred structure of the uncertainties) has been seen as an extremely interesting tool to represent their associated uncertainties. The generation of such radar ensembles requires first the full characterization of the 3D field of associated uncertainties (2D spatial plus temporal), since rainfall estimates show an error structure highly correlated in space and time. A full methodology to deal with this kind of radar-based rainfall ensembles is presented. Given a rainfall event, the 2D uncertainty fields associated to the radar estimates are defined for every time step using a benchmark, or reference field, based on the best available estimate of the rainfall field. This benchmark is built using an advanced non parametric interpolation of a dense raingauge network able to use the spatial structure provided by the radar observations, and is confined to the region in which this combination could be taken as a reference measurement (Velasco-Forero et al. 2008, doi:10.1016/j.advwatres.2008.10.004). Then the spatial and temporal structures of these uncertainty fields are characterized and a methodology to generate consistent multiple realisations of them is used to generate the

  17. Hydrologic applications of weather radar

    NASA Astrophysics Data System (ADS)

    Seo, Dong-Jun; Habib, Emad; Andrieu, Hervé; Morin, Efrat

    2015-12-01

    By providing high-resolution quantitative precipitation information (QPI), weather radars have revolutionized hydrology in the last two decades. With the aid of GIS technology, radar-based quantitative precipitation estimates (QPE) have enabled routine high-resolution hydrologic modeling in many parts of the world. Given the ever-increasing need for higher-resolution hydrologic and water resources information for a wide range of applications, one may expect that the use of weather radar will only grow. Despite the tremendous progress, a number of significant scientific, technological and engineering challenges remain to realize its potential. New challenges are also emerging as new areas of applications are discovered, explored and pursued. The purpose of this special issue is to provide the readership with some of the latest advances, lessons learned, experiences gained, and science issues and challenges related to hydrologic applications of weather radar. The special issue features 20 contributions on various topics which reflect the increasing diversity as well as the areas of focus in radar hydrology today. The contributions may be grouped as follows: Radar QPE (Kwon et al.; Hall et al.; Chen and Chandrasekar; Seo and Krajewski; Sandford).

  18. Coded continuous wave meteor radar

    NASA Astrophysics Data System (ADS)

    Vierinen, Juha; Chau, Jorge L.; Pfeffer, Nico; Clahsen, Matthias; Stober, Gunter

    2016-03-01

    The concept of a coded continuous wave specular meteor radar (SMR) is described. The radar uses a continuously transmitted pseudorandom phase-modulated waveform, which has several advantages compared to conventional pulsed SMRs. The coding avoids range and Doppler aliasing, which are in some cases problematic with pulsed radars. Continuous transmissions maximize pulse compression gain, allowing operation at lower peak power than a pulsed system. With continuous coding, the temporal and spectral resolution are not dependent on the transmit waveform and they can be fairly flexibly changed after performing a measurement. The low signal-to-noise ratio before pulse compression, combined with independent pseudorandom transmit waveforms, allows multiple geographically separated transmitters to be used in the same frequency band simultaneously without significantly interfering with each other. Because the same frequency band can be used by multiple transmitters, the same interferometric receiver antennas can be used to receive multiple transmitters at the same time. The principles of the signal processing are discussed, in addition to discussion of several practical ways to increase computation speed, and how to optimally detect meteor echoes. Measurements from a campaign performed with a coded continuous wave SMR are shown and compared with two standard pulsed SMR measurements. The type of meteor radar described in this paper would be suited for use in a large-scale multi-static network of meteor radar transmitters and receivers. Such a system would be useful for increasing the number of meteor detections to obtain improved meteor radar data products.

  19. Pacific Barrier Radar III (PACBAR III)

    NASA Astrophysics Data System (ADS)

    Miller, C. D.; Sigler, J. D.

    1983-11-01

    The Pacific Barrier (PACBAR III) C-band radar is being installed at the Western Space and Missile Center to furnish Revolution 0 detection of foreign launches. Previously installed on a tracking ship, the upgraded system will also identify and target space objects, maintain a catalog, and cover maneuvers and decay of space objects. Nominal operation will comprise a search of a predesignated 15 deg azimuth with the capability of detecting a 6 sq m target in a 400 km orbit, track spacecraft in orbits up to 800 km altitude, have a range resolution of about 80 yd, provide realtime payload and rocket body discrimination, and transmit two-way digital message traffic between the Center and NORAD in Cheyenne Mt. Interlaced vertical and horizontal pulses will augment the search and acquisition capabilities, and the antenna will have a 140 deg plunge range. The transmitter will function at 5.4-5.65 GHz, 320 p/sec, with a peak power of 0.8 MW, and the system will have a nonambiguous range of 32,768 nmi.

  20. Arecibo radar imagery of Mars: The major volcanic provinces

    NASA Astrophysics Data System (ADS)

    Harmon, John K.; Nolan, Michael C.; Husmann, Diana I.; Campbell, Bruce A.

    2012-08-01

    We present Earth-based radar images of Mars obtained with the upgraded Arecibo S-band (λ = 12.6 cm) radar during the 2005-2012 oppositions. The imaging was done using the same long-code delay-Doppler technique as for the earlier (pre-upgrade) imaging but at a much higher resolution (˜3 km) and, for some regions, a more favorable sub-Earth latitude. This has enabled us to make a more detailed and complete mapping of depolarized radar reflectivity (a proxy for small-scale surface roughness) over the major volcanic provinces of Tharsis, Elysium, and Amazonis. We find that vast portions of these regions are covered by radar-bright lava flows exhibiting circular polarization ratios close to unity, a characteristic that is uncommon for terrestrial lavas and that is a likely indicator of multiple scattering from extremely blocky or otherwise highly disrupted flow surfaces. All of the major volcanoes have radar-bright features on their shields, although the brightness distribution on Olympus Mons is very patchy and the summit plateau of Pavonis Mons is entirely radar-dark. The older minor shields (paterae and tholi) are largely or entirely radar-dark, which is consistent with mantling by dust or pyroclastic material. Other prominent radar-dark features include: the "fan-shaped deposits", possibly glacial, associated with the three major Tharsis Montes shields; various units of the Medusae Fossae Formation; a region south and west of Biblis Patera where "Stealth" deposits appear to obscure Tharsis flows; and a number of "dark-halo craters" with radar-absorbing ejecta blankets deposited atop surrounding bright flows. Several major bright features in Tharsis are associated with off-shield lava flows; these include the Olympus Mons basal plains, volcanic fields east and south of Pavonis Mons, the Daedalia Planum flows south of Arsia Mons, and a broad expanse of flows extending east from the Tharsis Montes to Echus Chasma. The radar-bright lava plains in Elysium are

  1. Space Radar Image of West Texas - SAR scan

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This radar image of the Midland/Odessa region of West Texas, demonstrates an experimental technique, called ScanSAR, that allows scientists to rapidly image large areas of the Earth's surface. The large image covers an area 245 kilometers by 225 kilometers (152 miles by 139 miles). It was obtained by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) flying aboard the space shuttle Endeavour on October 5, 1994. The smaller inset image is a standard SIR-C image showing a portion of the same area, 100 kilometers by 57 kilometers (62 miles by 35 miles) and was taken during the first flight of SIR-C on April 14, 1994. The bright spots on the right side of the image are the cities of Odessa (left) and Midland (right), Texas. The Pecos River runs from the top center to the bottom center of the image. Along the left side of the image are, from top to bottom, parts of the Guadalupe, Davis and Santiago Mountains. North is toward the upper right. Unlike conventional radar imaging, in which a radar continuously illuminates a single ground swath as the space shuttle passes over the terrain, a Scansar radar illuminates several adjacent ground swaths almost simultaneously, by 'scanning' the radar beam across a large area in a rapid sequence. The adjacent swaths, typically about 50 km (31 miles) wide, are then merged during ground processing to produce a single large scene. Illumination for this L-band scene is from the top of the image. The beams were scanned from the top of the scene to the bottom, as the shuttle flew from left to right. This scene was acquired in about 30 seconds. A normal SIR-C image is acquired in about 13 seconds. The ScanSAR mode will likely be used on future radar sensors to construct regional and possibly global radar images and topographic maps. The ScanSAR processor is being designed for 1996 implementation at NASA's Alaska SAR Facility, located at the University of Alaska Fairbanks, and will produce digital images from the

  2. Radar scattering properties of pancakelike domes on Venus

    NASA Technical Reports Server (NTRS)

    Ford, P. G.; Pettengill, G. H.

    1992-01-01

    Magellan radar images have disclosed the presence of a large number of almost perfectly circular domes, presumably of volcanic origin, in many regions of Venus several with diameters of 30 km or more. Their high degree of symmetry has permitted measurements of their shape, as determined by the Magellan altimeter to be compared with models of dome production from the eruption of high-viscosity magmas. In this work, we examine in detail the radar images of domes in Rusalka Planitia (2.8 deg S, 150.9 deg E) and Tinatin Planitia (12.2 deg N, 7.5 deg E), selected for their circular symmetry and apparent absence of modification due to large-scale slumping or tectonic rifting.

  3. SEASAT radar altimeter measurements over the Florida Everglades

    NASA Technical Reports Server (NTRS)

    Brooks, R. L.; Norcross, G. A.

    1983-01-01

    The SEASAT satellite radar altimeter traversed the Florida Everglades on August 14, 1978. Analysis of the measurements disclosed that the altimeter pulses from 800 km above the Earth's surface penetrated the vegetation canopies to provide land and water surface elevations with accuracies better than + or - 50 cm. The altimeter waveforms required retracking over the specular Everglades surface. The altimeter-derived land elevations were correlated with large-scale topographic maps while the altimeter-derived water elevations were correlated with water gauge records of the U.S. Geological Survey. Examination of the altimeter waveforms also revealed reflections from the Everglades' surface occurring earlier than the surface reflections. These earlier surface reflections are interpreted to be from vegetation canopies, and may provide a measure of vegetation canopy heights. Future satellite radar altimeters could provide supplemental vertical control in relatively inaccessible swamp areas, could monitor water levels, and perhaps could monitor vegetation growth.

  4. Doppler radar observation of the evolution of a thunderstorm

    NASA Technical Reports Server (NTRS)

    Heymsfield, G. M.; Srivastava, R. C.

    1980-01-01

    Triple-Doppler radar observations of the evolution of the three-dimensional structure of a thunderstorm on May 19, 1978 are analyzed. Continuous data were taken over a long period of the non-severe storm's lifetime as it passed through the radar and the portable automated mesonet network. A fairly low cloud top of 10 km and high reflectivities were observed, and horizontal rotations developed in the middle troposphere, which never reached lower levels. The cyclonic and anticyclonic circulations at mid-levels intensified after the maximum cell height was reached, and a high reflectivity maximum lasted 15-20 min aloft, with the core descending to the surface because of rapid fallout from the largest precipitation particles. Due to the fairly small scale of the updrafts, future use of smaller grid spacings is considered a necessity.

  5. Satellite microwave radiances correlated with radar rain rates over land

    NASA Technical Reports Server (NTRS)

    Spencer, R. W.; Martin, D. W.; Hinton, B. B.; Weinman, J. A.

    1983-01-01

    The characteristics of upwelling microwave radiation from raindrops as measured by satellite sensors are examined. The scanning multichannel microwave radiometers on board the Nimbus 7 and Seasat satellites have the capability of quantifying the perpendicularly polarized antenna temperatures at 37, 21, 18, 10.7, and 6.6 GHz. The instruments scan the earth at a constant 50 deg angle to the surface with a footprint that varies from 20-70 km. Radar rainfall measurements have an accuracy of within 60 percent, whereas a series of test measurements using SMMR data in comparison with radar data for rainfall in the same areas showed that the microwave data depicted rainfall rates with less than 1.55 mm/h error. Details of the rainfall rate algorithms used to treat the satellite microwave data are provided, noting that the identification of rainfall rates is dependent on quantifying the amount the upwelling radiance is reduced due to rainfall.

  6. Radar Observations of Meteor Interactions in the Ionosphere

    NASA Astrophysics Data System (ADS)

    Mann, I.; Pellinen-Wannberg, A.; Tjulin, A.

    2011-12-01

    Solid particles entering the Earth's atmosphere produce meteors in the ionosphere, typically at 80 to 120 km altitude, but also beyond. The major process causing the meteor is the vaporization of the solid after heating by collision with the atmospheric particles; sputtering also occurs. A fraction of the material that is ablated from the entering objects re-condenses into meteoric smoke particles. Meteors are actively detected by backscattering of radar signals and they are observed, for instance, with the EISCAT (European Incoherent Scatter Scientific Association) radars. Meteor trail and headecho observations detect the ionisation that is associated with the meteor. They allow for studying the properties of the entering solid objects (dust and meteors) and the subsequent ionospheric interactions. We discuss the range of objects that can be detected with EISCAT and the capability of the measurements to find the formation of the meteoric smoke. We then consider the possibilities for measurements with the future EISCAT 3D.

  7. Remote monitoring of the earthquake cycle using satellite radar interferometry.

    PubMed

    Wright, Tim J

    2002-12-15

    The earthquake cycle is poorly understood. Earthquakes continue to occur on previously unrecognized faults. Earthquake prediction seems impossible. These remain the facts despite nearly 100 years of intensive study since the earthquake cycle was first conceptualized. Using data acquired from satellites in orbit 800 km above the Earth, a new technique, radar interferometry (InSAR), has the potential to solve these problems. For the first time, detailed maps of the warping of the Earth's surface during the earthquake cycle can be obtained with a spatial resolution of a few tens of metres and a precision of a few millimetres. InSAR does not need equipment on the ground or expensive field campaigns, so it can gather crucial data on earthquakes and the seismic cycle from some of the remotest areas of the planet. In this article, I review some of the remarkable observations of the earthquake cycle already made using radar interferometry and speculate on breakthroughs that are tantalizingly close.

  8. Radar image processing for rock-type discrimination

    NASA Technical Reports Server (NTRS)

    Blom, R. G.; Daily, M.

    1982-01-01

    Image processing and enhancement techniques for improving the geologic utility of digital satellite radar images are reviewed. Preprocessing techniques such as mean and variance correction on a range or azimuth line by line basis to provide uniformly illuminated swaths, median value filtering for four-look imagery to eliminate speckle, and geometric rectification using a priori elevation data. Examples are presented of application of preprocessing methods to Seasat and Landsat data, and Seasat SAR imagery was coregistered with Landsat imagery to form composite scenes. A polynomial was developed to distort the radar picture to fit the Landsat image of a 90 x 90 km sq grid, using Landsat color ratios with Seasat intensities. Subsequent linear discrimination analysis was employed to discriminate rock types from known areas. Seasat additions to the Landsat data improved rock identification by 7%.

  9. Development of wide band digital receiver for atmospheric radars using COTS board based SDR

    NASA Astrophysics Data System (ADS)

    Yasodha, Polisetti; Jayaraman, Achuthan; Thriveni, A.

    2016-07-01

    Digital receiver extracts the received echo signal information, and is a potential subsystem for atmospheric radar, also referred to as wind profiling radar (WPR), which provides the vertical profiles of 3-dimensional wind vector in the atmosphere. This paper presents the development of digital receiver using COTS board based Software Defined Radio technique, which can be used for atmospheric radars. The developmental work is being carried out at National Atmospheric Research Laboratory (NARL), Gadanki. The digital receiver consists of a commercially available software defined radio (SDR) board called as universal software radio peripheral B210 (USRP B210) and a personal computer. USRP B210 operates over a wider frequency range from 70 MHz to 6 GHz and hence can be used for variety of radars like Doppler weather radars operating in S/C bands, in addition to wind profiling radars operating in VHF, UHF and L bands. Due to the flexibility and re-configurability of SDR, where the component functionalities are implemented in software, it is easy to modify the software to receive the echoes and process them as per the requirement suitable for the type of the radar intended. Hence, USRP B210 board along with the computer forms a versatile digital receiver from 70 MHz to 6 GHz. It has an inbuilt direct conversion transceiver with two transmit and two receive channels, which can be operated in fully coherent 2x2 MIMO fashion and thus it can be used as a two channel receiver. Multiple USRP B210 boards can be synchronized using the pulse per second (PPS) input provided on the board, to configure multi-channel digital receiver system. RF gain of the transceiver can be varied from 0 to 70 dB. The board can be controlled from the computer via USB 3.0 interface through USRP hardware driver (UHD), which is an open source cross platform driver. The USRP B210 board is connected to the personal computer through USB 3.0. Reference (10 MHz) clock signal from the radar master oscillator

  10. Combination of radar and daily precipitation data to estimate meaningful sub-daily point precipitation extremes

    NASA Astrophysics Data System (ADS)

    Bárdossy, András; Pegram, Geoffrey

    2017-01-01

    Bethlehem from 1998 to 2003, whose scan at 1.5 km above ground [CAPPI] overlapped a dense (10 km spacing) set of 45 pluviometers recording in the same 6-year period. This valuable set of data was obtained from each of 37 selected radar pixels [1 km square in plan] which contained a pluviometer not masked out by the radar foot-print. The pluviometer data were also aggregated to daily totals, for the same purpose. The extremes obtained using disaggregation methods were compared to the observed extremes in a cross validation procedure. The unusual and novel goal was not to obtain the reproduction of the precipitation matching in space and time, but to obtain frequency distributions of the point extremes, which we found to be stable.

  11. Space Radar Image of Long Island Optical/Radar

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This pair of images of the Long Island, New York region is a comparison of an optical photograph (top) and a radar image (bottom), both taken in darkness in April 1994. The photograph at the top was taken by the Endeavour astronauts at about 3 a.m. Eastern time on April 20, 1994. The image at the bottom was acquired at about the same time four days earlier on April 16,1994 by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) system aboard the space shuttle Endeavour. Both images show an area approximately 100 kilometers by 40 kilometers (62 miles by 25 miles) that is centered at 40.7 degrees North latitude and 73.5 degrees West longitude. North is toward the upper right. The optical image is dominated by city lights, which are particularly bright in the densely developed urban areas of New York City located on the left half of the photo. The brightest white zones appear on the island of Manhattan in the left center, and Central Park can be seen as a darker area in the middle of Manhattan. To the northeast (right) of the city, suburban Long Island appears as a less densely illuminated area, with the brightest zones occurring along major transportation and development corridors. Since radar is an active sensing system that provides its own illumination, the radar image shows a great amount of surface detail, despite the night-time acquisition. The colors in the radar image were obtained using the following radar channels: red represents the L-band (horizontally transmitted and received); green represents the L-band (horizontally transmitted and vertically received); blue represents the C-band (horizontally transmitted and vertically received). In this image, the water surface - the Atlantic Ocean along the bottom edge and Long Island Sound shown at the top edge - appears red because small waves at the surface strongly reflect the horizontally transmitted and received L-band radar signal. Networks of highways and railroad lines are clearly

  12. Online clustering algorithms for radar emitter classification.

    PubMed

    Liu, Jun; Lee, Jim P Y; Senior; Li, Lingjie; Luo, Zhi-Quan; Wong, K Max

    2005-08-01

    Radar emitter classification is a special application of data clustering for classifying unknown radar emitters from received radar pulse samples. The main challenges of this task are the high dimensionality of radar pulse samples, small sample group size, and closely located radar pulse clusters. In this paper, two new online clustering algorithms are developed for radar emitter classification: One is model-based using the Minimum Description Length (MDL) criterion and the other is based on competitive learning. Computational complexity is analyzed for each algorithm and then compared. Simulation results show the superior performance of the model-based algorithm over competitive learning in terms of better classification accuracy, flexibility, and stability.

  13. Space Radar Image of Possible String of Impact Creaters

    NASA Technical Reports Server (NTRS)

    1994-01-01

    The impact of an asteroid or comet several hundred million years ago left scars in the landscape that are still visible in this spaceborne radar image of an area in the Sahara Desert of northern Chad. The concentric ring structure left of center is the Aorounga impact crater with a diameter of about 17 kilometers (10.5 miles). Scientists are using radar images to investigate the possibility that Aorounga formed as part of a multiple impact event. A proposed second crater, similar in size to the main structure, appears as a circular trough surrounding a central peak in the center of the image. A third structure, also about the same size, is seen as a dark, partial circular trough with a possible central structure in the right center of the image. The proposed crater 'chain' could have formed when a 1 km to 2 km (0.5 mile to 1 mile) diameter object broke apart before impact. The dark streaks are deposits of windblown sand that migrate along valleys cut by thousands of years of wind erosion. Radar imaging is a valuable tool for the study of desert regions because the radar waves can penetrate thin layers of dry sand to reveal details of geologic structure that are invisible to other sensors. The image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) on April 18 and 19, 1994, onboard the space shuttle Endeavour. The area shown is 45 kilometers by 61 kilometers (28 miles by 38 miles) and is centeredat 19.25 degrees north latitude, 19.25 degrees east longitude. North is toward the upper right. The colors are assigned to differentradar frequencies and polarizations as follows: red is L-band, horizontally transmitted and received; green is C-band, horizontallytransmitted and received; and blue is C-band, horizontally transmitted,vertically received. SIR-C/X-SAR, a joint mission of the German, Italian and United States space agencies, is part of NASA's Mission to Planet Earth program.

  14. Cloud radar deployment for Indian Monsoon observations: Preliminary Results

    NASA Astrophysics Data System (ADS)

    Chakravarty, K.; Kalapureddy, M.; Pa, M.; Deshpandy, S.; Das, S.; Pandithurai, G.; Prabhakaran, T.; Chandrasekar, C. V.; Goswami, B.

    2013-12-01

    Indian Institute of Tropical Meteorology (IITM)'s acquired Ka-band radar for the Study of the interaction between Cloud and Environment for formation of Precipitation. Main objective of it is to make simultaneous high resolution measurements on dynamical, cloud microphysical and precipitation parameters pertain to monsoon system probably at diverse locations. The goal is to understand the interplay between cloud processes and environment that not only allow understanding the fundamental cloud-environment interactions but also precipitation formation mechanisms and further to estimate cloud contribution to the re-distribution of energy and water in climate system. For this, Polarimetric weather Doppler Radar at higher frequencies (9.5 and 35 GHz) can be a potential tool to gain knowledge on this scientific as well as societal application oriented programme. IITM's Polarimetric scanning Ka-band (cloud) radar operations started recently during May 2013. Mobile Ka-band Scanning Polarimetric Doppler Radar (KaSPR) is a cloud radar operating at wavelength of 8.5 mm with average powers of 110 W. KaSPR incorporates a conduction cooled Extended Interaction Klystron Amplifier. It is having four foot diameter Ka-band cassegrain antenna. Liquid cooled air-sealed RF unit provides excellent temperature stability. Antenna on the top of RF unit is mounted on the Elevation over azimuth pedestal which is designed to rotate continuously in the azimuth axis and a full 180 degrees in the elevation axis (horizon to horizon) with a maximum velocity of 200/sec and maximum acceleration of 120/s2. KaSPR uses dual channel 16-bit digital receiver having dynamic range of more than 80 dB with bandwidths 10 MHz. Arbitrary waveform generator capable of generating any user-defined waveform of up to 16K samples in length. It is having sensitivity of the order -45 dBZ at 5 km. KaSPR has been providing high sensitivity versatile measurements of cloud and precipitation at tropical site (Manderdev, 18

  15. Characteristics of mesosphere echoes over Antarctica obtained using PANSY and MF radars

    NASA Astrophysics Data System (ADS)

    Tsutsumi, Masaki; Nakamura, Takuji; Sato, Toru; Nishimura, Koji; Sato, Kaoru; Tomikawa, Yoshihiro; Kohma, Masashi

    2016-07-01

    In the polar region characteristic radar echoes are observed from the mesosphere by using a VHF system. The nature of the echoes is distinctively different between summer and winter and those echoes are called Polar Mesosphere Summer Echoes (PMSEs) and Polar Mesosphere Winter Echoes (PMWEs), respectively. Since the PMSEs are usually very strong and can be easily measured with a small radar system, their nature is relatively well understood. On the other hand PMWEs are much weaker and they are still only poorly understood. The PANSY radar (47MHz) at Syowa station (69S) is the only large aperture atmospheric radar in the Antarctic, and can continuously survey the dynamics of the middle atmosphere with high time and height resolutions [Sato et al., 2014]. Nishiyama et al [2014] reported the first study of PMWEs using PANSY radar and showed a seasonal and local time dependence of these echoes. An MF radar system (2.4MHz) is co-located at Syowa, and has been operating for mesosphere and lower thermosphere observations. Although the MF radar has only a much poorer height resolution and is incapable of vertical wind measurement, it can almost continuously measure mesosphere day and night. In this study the nature of the mesosphere echoes, mainly PMWEs, are being studied using the two radars based on the observation made in 2015. These radars are operated using largely different radio frequencies and can provide complementary information with each other such as wind velocities and also echo scattering mechanisms. Horizontal wind velocities have been compared between the two radars with a great care mostly in the MF radar winds in order to avoid possible biases inherent in the correlation analysis technique employed for the MF radar wind measurement. A careful analysis has shown that the horizontal wind velocities agree well between the two systems with a high correlation coefficient around 0.8 throughout the height region of 65-85km. Aspect sensitivities estimated using

  16. All-digital radar architecture

    NASA Astrophysics Data System (ADS)

    Molchanov, Pavlo A.

    2014-10-01

    All digital radar architecture requires exclude mechanical scan system. The phase antenna array is necessarily large because the array elements must be co-located with very precise dimensions and will need high accuracy phase processing system for aggregate and distribute T/R modules data to/from antenna elements. Even phase array cannot provide wide field of view. New nature inspired all digital radar architecture proposed. The fly's eye consists of multiple angularly spaced sensors giving the fly simultaneously thee wide-area visual coverage it needs to detect and avoid the threats around him. Fly eye radar antenna array consist multiple directional antennas loose distributed along perimeter of ground vehicle or aircraft and coupled with receiving/transmitting front end modules connected by digital interface to central processor. Non-steering antenna array allows creating all-digital radar with extreme flexible architecture. Fly eye radar architecture provides wide possibility of digital modulation and different waveform generation. Simultaneous correlation and integration of thousands signals per second from each point of surveillance area allows not only detecting of low level signals ((low profile targets), but help to recognize and classify signals (targets) by using diversity signals, polarization modulation and intelligent processing. Proposed all digital radar architecture with distributed directional antenna array can provide a 3D space vector to the jammer by verification direction of arrival for signals sources and as result jam/spoof protection not only for radar systems, but for communication systems and any navigation constellation system, for both encrypted or unencrypted signals, for not limited number or close positioned jammers.

  17. Quantitative estimation of Tropical Rainfall Mapping Mission precipitation radar signals from ground-based polarimetric radar observations

    NASA Astrophysics Data System (ADS)

    Bolen, Steven M.; Chandrasekar, V.

    2003-06-01

    The Tropical Rainfall Mapping Mission (TRMM) is the first mission dedicated to measuring rainfall from space using radar. The precipitation radar (PR) is one of several instruments aboard the TRMM satellite that is operating in a nearly circular orbit with nominal altitude of 350 km, inclination of 35°, and period of 91.5 min. The PR is a single-frequency Ku-band instrument that is designed to yield information about the vertical storm structure so as to gain insight into the intensity and distribution of rainfall. Attenuation effects on PR measurements, however, can be significant and as high as 10-15 dB. This can seriously impair the accuracy of rain rate retrieval algorithms derived from PR signal returns. Quantitative estimation of PR attenuation is made along the PR beam via ground-based polarimetric observations to validate attenuation correction procedures used by the PR. The reflectivity (Zh) at horizontal polarization and specific differential phase (Kdp) are found along the beam from S-band ground radar measurements, and theoretical modeling is used to determine the expected specific attenuation (k) along the space-Earth path at Ku-band frequency from these measurements. A theoretical k-Kdp relationship is determined for rain when Kdp ≥ 0.5°/km, and a power law relationship, k = a Zhb, is determined for light rain and other types of hydrometers encountered along the path. After alignment and resolution volume matching is made between ground and PR measurements, the two-way path-integrated attenuation (PIA) is calculated along the PR propagation path by integrating the specific attenuation along the path. The PR reflectivity derived after removing the PIA is also compared against ground radar observations.

  18. Microphysical Model of the Venus clouds between 40km and 80km

    NASA Astrophysics Data System (ADS)

    McGouldrick, Kevin

    2013-10-01

    I am continuing to adapt the Community Aerosol and Radiation Model for Atmospheres (CARMA) to successfully simulate the multi-layered clouds of Venus. The present version of the one-dimensional model now includes a simple parameterization of the photochemicial production of sulfuric acid around altitudes of 62km, and its thermochemical destruction below cloud base. Photochemical production in the model is limited by the availability of water vapor and insolation. Upper cloud particles are introduced into the model via binary homogeneous nucleation, while the lower and middle cloud particles are created via activation of involatile cloud condensation nuclei. Growth by condensation and coagulation and coalescence are also treated. Mass loadings and particle sizes compare favorably with the in situ observations by the Pioneer Venus Large Probe Particle Size Spectrometer, and mixing ratios of volatiles compare favorably with remotely sensed observations of water vapor and sulfuric acid vapor. This work was supported by the NASA Planetary Atmospheres Program, grant number NNX11AD79G.

  19. Shigaraki middle and upper atmosphere radar meteor-head-echo database

    NASA Astrophysics Data System (ADS)

    Kero, J.; Nakamura, T.; Szasz, C.; Kastinen, D.; Watanabe, J.; Yamamoto, M.; Fujiwara, Y.; Abo, M.; Tanaka, Y.; Abe, S.

    2014-07-01

    Introduction: Mass infux from space into the terrestrial atmosphere is mainly caused by meteors. Meteors deliver various elements into the atmosphere and the meteoric dust particles are of great importance in the terrestrial atmosphere. For example, they act as nucleus for condensation and clouds and affect various atmospheric phenomena both in physical and chemical aspects. Thus, to investigate the meteor flux, orbits and their interactions in the upper atmosphere is very important but at the same time the method of investigation is limited, especially for precise measurements. High-power large-aperture (HPLA) radar observation is a recent technique to provide useful information on meteor infux and orbits, as well as interactions with the atmosphere. Since 2009 orbital data of about 120,000 meteors [2] have been collected using a novel head-echo analysis algorithm for the lower VHF band [1]. The data was collected using the middle and upper atmosphere radar (MU radar) of Kyoto University at Shigaraki (34.9N, 136.1S). The MU radar is a large atmospheric VHF radar with 46.5 MHz frequency, 1 MW output transmission power and 8330 m^2 aperture array antenna. An open database (MU radar meteor head echo database: MURMHED) for research and education is now being created. Database: The database currently holds 53 different parameters for each event and a number of associated time series consisting of range, height, radar cross section, signal to noise ratio, radial velocity and meteorid velocity. The database parameters are MJD, Year [UT], Month [UT], Day [UT], Hour [UT], Minute [UT], Second [UT], Duration [s], RA [deg], Dec [deg], Az [deg], Ze [deg], Az uncorr [deg], Ze uncorr [deg], Ze correction [deg], Obs initial vel [km/s], Geocentric vel [km/s], RCS [dBsm], SNR [dB], Start hgt [km], End hgt [km], Az of start point [deg], Ze of start point [deg], Az of end point [deg], Ze of end point [deg], Semimajor axis [au], Eccentricity, Perihelion dist [au], Lon of asc node [deg

  20. Studies based on global subsurface radar sounding of the Moon by SELENE (Kaguya) Lunar Radar Sounder (LRS): A summary

    NASA Astrophysics Data System (ADS)

    Kumamoto, A.; Yamaguchi, Y.; Yamaji, A.; Kobayashi, T.; Oshigami, S.; Ishiyama, K.; Nakamura, N.; Goto, Y.

    2015-12-01

    The Lunar Radar Sounder (LRS) onboard the SELENE (Kaguya) spacecraft has successfully performed radar sounder observations of the lunar subsurface structures and passive observations of natural radio and plasma waves from the lunar orbit. After the transfer of the spacecraft into the final lunar orbit and antenna deployment, the operation of LRS started on October 29, 2007. Through the operation until June 10, 2009, 130 million pulses worth of radar sounder data have been obtained [Ono et al., 2010]. Based on the datasets of the first lunar global subsurface radar sounding, Ono et al. [2009] revealed that there are distinct reflectors at a depth of several hundred meters in the nearside maria, which are inferred to be buried regolith layers covered by a basalt layer with a thickness of several hundred meters. Based on the further survey, Pommerol et al. [2010] pointed out the negative correlation of clear subsurface echoes with the maps of ilmenite, and suggested that dense ilmenite attenuates the radar pulse in the basaltic mare lava, and cause the absence of the clear subsurface echoes. That also suggests there are undetected subsurface reflectors especially below the young lava flow units with high ilmenite abundance. Kobayashi et al. [2012] applied synthetic aperture radar (SAR) processing to SELENE LRS data in order to obtain distinct radargram. Taking advantage of analyzing waveform data sent via high data rate telemetry from the Moon, we can perform advanced data analyses on the ground. We started providing the both SAR processed and waveform datasets via SELENE Data Archive (http://l2db.selene.darts.isas.jaxa.jp/index.html.en) since 2015. Oshigami et al. [2014] estimated volumes of basalt units in the ages of 2.7 Ga to 3.8 Ga in the nearside maria. The volume was derived from the depth of subsurface reflectors measured by LRS. The volumes of the geologic units were 103 to 104 km3. The average eruption rates were 10-5 to 10-3 km3 yr-1. The estimated volumes

  1. Tomographic Observation and Bedmapping of Glaciers in Western Greenland with IceBridge Sounding Radar

    NASA Technical Reports Server (NTRS)

    Wu, Xiaoqing; Paden, John; Jezek, Ken; Rignot, Eric; Gim, Young

    2013-01-01

    We produced the high resolution bedmaps of several glaciers in western Greenland from IceBridge Mission sounding radar data using tomographic sounding technique. The bedmaps cover 3 regions: Russell glaciers, Umanaq glaciers and Jakobshavn glaciers of western Greenland. The covered areas is about 20x40 km(sup 2) for Russell glaciers and 300x100 sq km, and 100x80 sq km for Jakobshavn glaciers. The ground resolution is 50 meters and the average ice thickness accuracy is 10 to 20 meters. There are some void areas within the swath of the tracks in the bedmaps where the ice thickness is not known. Tomographic observations of these void areas indicate that the surface and shallow sub-surface pockets, likely filled with water, are highly reflective and greatly weaken the radar signal and reduce the energy reaching and reflected from the ice sheet bottom.

  2. The SHARAD Sounding Radar Explores Mars (Invited)

    NASA Astrophysics Data System (ADS)

    Phillips, R. J.; Seu, R.; Campbell, B. A.; Plaut, J. J.; Holt, J. W.; Carter, L. M.; Putzig, N. E.; Smrekar, S. E.; Nunes, D. C.; Orosei, R.

    2009-12-01

    SHARAD (SHAllow RADar) is a sounding radar provided by the Italian Space Agency for the Mars Reconnaissance Orbiter mission. Its 20-MHz center frequency and 10-MHz bandwidth complement the lower frequency and narrower bandwidth of the MARSIS sounding radar. SHARAD is particularly useful for mapping the internal, fine-scale layering of the deposits in the polar regions of Mars. In the north, SHARAD paints a three-dimensional picture of the stratigraphy, previously mapped from visible images only in canyon exposures on the periphery of the cap. Regional differences in elevation across the cap are caused by a coarsely layered, variable thickness Basal Unit partially underlying a relatively constant thickness (~2-km) ice-rich layered unit. Of particular interest are the subsurface patterns of ice and dust layers, which are likely tied to the martian climate history over the last several million years and thus to time variations in the planet’s orbit and in its spin-axis obliquity and precession. In the layered deposits at both poles SHARAD has mapped angular unconformities, and at the northern cap SHARAD has unraveled the stratigraphic records of trough migration. The subsurface structures of the ice-rich layered deposits are on the whole different between the two poles, and this may reflect their age difference. The radars have also mapped subsurface reflections in other areas of Mars, including many locales in the northern lowlands. In southern Elysium Planitia, some have interpreted the geomorphology seen in imagery in terms of a frozen sea, but SHARAD shows that the electrical properties of the shallow subsurface material in this region are inconsistent with ice. Elsewhere, geological evidence points to the possibility of ice-rich deposits (such as lobate debris aprons) at mid-latitudes, relics of past glaciations driven by high obliquities. Here, SHARAD confirms the ice hypothesis based on the dielectric behavior of the subsurface material. A subsurface

  3. Development of an external interferometer for meteor wind observation attached to the MU radar

    NASA Astrophysics Data System (ADS)

    Nakamura, Takuji; Tsuda, Toshitaka; Tsutsumi, Masaki

    1997-05-01

    An external meteor detection system for the middle and upper atmosphere (MU) radar, Shigaraki, Japan, has been developed in order to monitor the wind velocities at 80-100 km. The characteristics of the MU radar system and the observations are closely inspected, and we design a three-channel interferometer system using three independent single antennas. The data-taking system was carefully designed, considering fast data rate, short interpulse period, wide data bits (19 bit), and fast sampling rate (1 million samples/s), and all the logics are assembled by programmable logic devices. This external interferometer was operated since March 1995 during the Doppler beam swinging observation by the MU radar, and the first results are presented. Meteor echo rate was around 2000/day, 1000 of which were usable for postprocessing, i.e., wind measurement. This echo rate is greater than that of the meteor radar system in Jakarta. Wind velocities were determined with time-height resolutions of 1 hour × 2 km, which showed reasonable agreement with the wind velocities determined from the turbulent echoes in the mesosphere. We present the capability of an external interferometry system attached to the mesosphere-stratosphere-troposphere/stratosphere-troposphere radar as a meteor wind observation system.

  4. Correcting for wind drift in high resolution radar rainfall products: a feasibility study

    NASA Astrophysics Data System (ADS)

    Sandford, Caroline

    2015-12-01

    Increasing demands from emergency responders for accurate flood prediction, particularly in cities, have motivated consistent increases in the resolution of urban drainage models. Such models are now primarily limited by the accuracy and resolution of the initialising rainfall field. Surface rainfall estimates from radar, traditionally derived at scales of order 1 km, are now requested at grid lengths of 100 m to drive improvements in the outputs of these models. Deriving radar precipitation products on grids at the sub-kilometre scale introduces new requirements for the processing of reflectivity measurements into surface rainfall rates. A major source of uncertainty is the physical distance between the radar measurement and the surface onto which precipitation falls. Whilst adjustments to account for inhomogeneity in the vertical reflectivity profile have been extensively investigated, the effects of horizontal displacement have not. This paper discusses the issue of wind drift, first by outlining the need for correction, and then by evaluating the corrections available for impact at the required scale. One correction is detailed and its sensitivity evaluated with respect to the assumptions necessary in its derivation. These sensitivities are verified by trials on the Met Office operational radar processing system, where errors on wind drift displacement estimates are shown to be of order 1 km or more. This is significantly greater than the grid length desired by hydrological users. The paper therefore concludes by suggesting further research necessary to ensure the accuracy of radar precipitation estimates at sub-kilometre resolution.

  5. Radar analyses of mesoscale meteorological phenomena during the AVE/VAS correlation field experiment

    NASA Technical Reports Server (NTRS)

    Huebner, G. L.

    1984-01-01

    Radar data were collected during the selected critical times of the field experiment and subsequently analyzed for specific items. The analyses of the radar data for the AVE/VAS experiment provided statistically significant values for each of the 10 Km by 10 Km grids within radar range. The resulting information for correlation with satellite data included the following derived items that were averaged for each grid area: (1) rainfall rate in mm/hr; (2) dBZ (reflectivity) values; (3) accumulated rainfall values per hour; (4) accumulated rainfall values for a 6-hour period; (5) vertically integrated liquid water content per square meter; and (6) vertical height of the radar axis at the midpoint of each grid. Additional products derived from radar data are being investigated. An example of one such product is the derivation of the errors in integrated rainfall with different sampling periods. This is of significance for correlation with satellite data in that normally a step-function type of rainfall rate is used to derive the total rainfall over a period.

  6. Doppler radar radial winds in HIRLAM. Part I: observation modelling and validation

    NASA Astrophysics Data System (ADS)

    Järvinen, H.; Salonen, K.; Lindskog, M.; Huuskonen, A.; Niemelä, S.; Eresmaa, R.

    2009-03-01

    An observation operator for Doppler radar radial wind measurements is developed further in this article, based on the earlier work and considerations of the measurement characteristic. The elementary observation operator treats radar observations as point measurements at pre-processed observation heights. Here, modelling of the radar pulse volume broadening in vertical and the radar pulse path bending due to refraction is included to improve the realism of the observation modelling. The operator is implemented into the High Resolution Limited Area Model (HIRLAM) limited area numerical weather prediction (NWP) system. A data set of circa 133000 radial wind measurements is passively monitored against the HIRLAM six-hourly background values in a 1-month experiment. No data assimilation experiments are performed at this stage. A new finding is that the improved modelling reduces the mean observation minus background (OmB) vector wind difference at ranges below 55 km, and the standard deviation of the radial wind OmB difference at ranges over 25 km. In conclusion, a more accurate and still computationally feasible observation operator is developed. The companion paper (Part II) considers optimal super-observation processing of Doppler radar radial winds for HIRLAM, with general applicability in NWP.

  7. Considerations for a Radar System to Detect an Ocean Underneath the Icy Shell of Europa

    NASA Technical Reports Server (NTRS)

    Markus, Thorsten; Gogineni, Prasad; Green, James; Cooper, John; Fung, Shing; Taylor, William; Benson, Robert; Reinisch, Bodo; Song, Paul

    2004-01-01

    The detection of an ocean underneath Europa is one of the primary objectives of the Jupiter Icy Moons Orbiter (JIMO) mission. An orbiting surface penetrating radar has the potential of providing that measurement thus yielding information regarding the possibility of life support on Europa. Radars in the MHz range have successfully monitored the kilometer-deep ice shelves of Greenland and Antarctica, including the detection of Lake Vostok (and others) below an ice sheet thickness of about 4 km. The performance of a radar system orbiting Europa will be subject to several potential complications and unknowns. Besides ionospheric dispersion and the actual depth of the ocean, which is estimated between 2 and 30 km, major unknowns affecting radar performance are the temperature profile, the amount of salt and other impurities within the ice crust as well as the surface roughness. These impurities can in part be produced at the highly irradiated surface by magnetospheric interactions and transported downward into the ice crust by geologic processes. The ionospheric interference must also be modeled from effects of these interactions on production of the thin neutral atmosphere and subsequent ionization of the neutrals. We investigated these uncertainties through radar simulations using different surface and ice characteristics over a frequency range from 10 to 50 MHz. The talk will present results from these simulations discussing potential limitations.

  8. A comparison of vertical velocity variance measurements from wind profiling radars and sonic anemometers

    NASA Astrophysics Data System (ADS)

    McCaffrey, Katherine; Bianco, Laura; Johnston, Paul; Wilczak, James M.

    2017-03-01

    Observations of turbulence in the planetary boundary layer are critical for developing and evaluating boundary layer parameterizations in mesoscale numerical weather prediction models. These observations, however, are expensive and rarely profile the entire boundary layer. Using optimized configurations for 449 and 915 MHz wind profiling radars during the eXperimental Planetary boundary layer Instrumentation Assessment (XPIA), improvements have been made to the historical methods of measuring vertical velocity variance through the time series of vertical velocity, as well as the Doppler spectral width. Using six heights of sonic anemometers mounted on a 300 m tower, correlations of up to R2 = 0. 74 are seen in measurements of the large-scale variances from the radar time series and R2 = 0. 79 in measurements of small-scale variance from radar spectral widths. The total variance, measured as the sum of the small and large scales, agrees well with sonic anemometers, with R2 = 0. 79. Correlation is higher in daytime convective boundary layers than nighttime stable conditions when turbulence levels are smaller. With the good agreement with the in situ measurements, highly resolved profiles up to 2 km can be accurately observed from the 449 MHz radar and 1 km from the 915 MHz radar. This optimized configuration will provide unique observations for the verification and improvement to boundary layer parameterizations in mesoscale models.

  9. How dual-polarization radar observations can be used to verify model representation of secondary ice

    NASA Astrophysics Data System (ADS)

    Sinclair, Victoria A.; Moisseev, Dmitri; Lerber, Annakaisa

    2016-09-01

    In this paper it is discussed how dual-polarization radar observations can be used to verify model representations of secondary ice production. An event where enhanced specific differential phase, Kdp, signatures in snow occur at the altitudes where temperatures lie in the range between -8 and -3°C is investigated. By combining radar and surface-based precipitation observations it is shown that these dual-polarization radar signatures are most likely caused by ice with concentrations exceeding those expected from primary ice parameterizations. It is also shown that the newly formed ice particles readily aggregate, which may explain why Kdp values seem to be capped at 0.2-0.3°/km for a C band radar. For the event of interest, multiple high-resolution (1 km) Weather Research and Forecasting (WRF) model simulations are conducted. When the default versions of the Morrison microphysics schemes were used, the simulated number concentration of frozen hydrometeors is much lower than observed and the simulated ice particle concentrations are comparable with values expected from primary ice parameterizations. Higher ice concentrations, which exceed values expected from primary ice parameterizations, were simulated when ad hoc thresholds for rain and cloud water mixing ratio in the Hallett-Mossop part of the Morrison scheme were removed. These results suggest that the parameterization of secondary ice production in operational weather prediction models needs to be revisited and that dual-polarization radar observations, in conjunction with ancillary observations, can be used to verify them.

  10. Assimilation of Dual-Polarimetric Radar Observations with WRF GSI

    NASA Technical Reports Server (NTRS)

    Li, Xuanli; Mecikalski, John; Fehnel, Traci; Zavodsky, Bradley; Srikishen, Jayanthi

    2014-01-01

    Dual-polarimetric (dual-pol) radar typically transmits both horizontally and vertically polarized radio wave pulses. From the two different reflected power returns, more accurate estimate of liquid and solid cloud and precipitation can be provided. The upgrade of the traditional NWS WSR-88D radar to include dual-pol capabilities will soon be completed for the entire NEXRAD network. Therefore, the use of dual-pol radar network will have a broad impact in both research and operational communities. The assimilation of dual-pol radar data is especially challenging as few guidelines have been provided by previous research. It is our goal to examine how to best use dual-pol radar data to improve forecast of severe storm and forecast initialization. In recent years, the Development Testbed Center (DTC) has released the community Gridpoint Statistical Interpolation (GSI) DA system for the Weather Research and Forecasting (WRF) model. The community GSI system runs in independently environment, yet works functionally equivalent to operational centers. With collaboration with the NASA Short-term Prediction Research and Transition (SPoRT) Center, this study explores regional assimilation of the dual-pol radar variables from the WSR-88D radars for real case storms. Our presentation will highlight our recent effort on incorporating the horizontal reflectivity (ZH), differential reflectivity (ZDR), specific differential phase (KDP), and radial velocity (VR) data for initializing convective storms, with a significant focus being on an improved representation of hydrometeor fields. In addition, discussion will be provided on the development of enhanced assimilation procedures in the GSI system with respect to dual-pol variables. Beyond the dual-pol variable assimilation procedure developing within a GSI framework, highresolution (=1 km) WRF model simulations and storm scale data assimilation experiments will be examined, emphasizing both model initialization and short-term forecast

  11. Radar Mosaic of Africa

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This is an image of equatorial Africa, centered on the equator at longitude 15degrees east. This image is a mosaic of almost 4,000 separate images obtained in 1996 by the L-band imaging radar onboard the Japanese Earth Resources Satellite. Using radar to penetrate the persistent clouds prevalent in tropical forests, the Japanese Earth Resources Satellite was able for the first time to image at high resolution this continental scale region during single flooding seasons. The area shown covers about 7.4 million square kilometers (2.8 million square miles) of land surface, spans more than 5,000 kilometers(3,100 miles) east and west and some 2,000 kilometers (1,240 miles) north and south. North is up in this image. At the full resolution of the mosaic (100 meters or 330 feet), this image is more than 500 megabytes in size, and was processed from imagery totaling more than 60 gigabytes.

    Central Africa was imaged twice in 1996, once between January and March, which is the major low-flood season in the Congo Basin, and once between October and November, which is the major high-flood season in the Congo Basin. The red color corresponds to the data from the low-flood season, the green to the high-flood season, and the blue to the 'texture' of the low-flood data. The forests appear green as a result, the flooded and palm forests, as well as urban areas, appear yellow, the ocean and lakes appear black, and savanna areas appear blue, black or green, depending on the savanna type, surface topography and other factors. The areas of the image that are black and white were mapped only between January and March 1996. In these areas, the black areas are savanna or open water, the gray are forests, and the white areas are flooded forests or urban areas. The Congo River dominates the middle of the image, where the nearby forests that are periodically flooded by the Congo and its tributaries stand out as yellow. The Nile River flows north from Lake Victoria in the middle right of

  12. Bistatic synthetic aperture radar

    NASA Astrophysics Data System (ADS)

    Yates, Gillian

    Synthetic aperture radar (SAR) allows all-weather, day and night, surface surveillance and has the ability to detect, classify and geolocate objects at long stand-off ranges. Bistatic SAR, where the transmitter and the receiver are on separate platforms, is seen as a potential means of countering the vulnerability of conventional monostatic SAR to electronic countermeasures, particularly directional jamming, and avoiding physical attack of the imaging platform. As the receiving platform can be totally passive, it does not advertise its position by RF emissions. The transmitter is not susceptible to jamming and can, for example, operate at long stand-off ranges to reduce its vulnerability to physical attack. This thesis examines some of the complications involved in producing high-resolution bistatic SAR imagery. The effect of bistatic operation on resolution is examined from a theoretical viewpoint and analytical expressions for resolution are developed. These expressions are verified by simulation work using a simple 'point by point' processor. This work is extended to look at using modern practical processing engines for bistatic geometries. Adaptations of the polar format algorithm and range migration algorithm are considered. The principal achievement of this work is a fully airborne demonstration of bistatic SAR. The route taken in reaching this is given, along with some results. The bistatic SAR imagery is analysed and compared to the monostatic imagery collected at the same time. Demonstrating high-resolution bistatic SAR imagery using two airborne platforms represents what I believe to be a European first and is likely to be the first time that this has been achieved outside the US (the UK has very little insight into US work on this topic). Bistatic target characteristics are examined through the use of simulations. This also compares bistatic imagery with monostatic and gives further insight into the utility of bistatic SAR.

  13. Comparison of wind measurements in the troposphere and mesosphere by VHF/MF radars and in-situ techniques

    NASA Astrophysics Data System (ADS)

    Engler, N.; Singer, W.; Latteck, R.; Strelnikov, B.

    2008-11-01

    Radar wind observations at frequencies between 1.98 and 53.5 MHz obtained at polar latitudes were compared to in-situ wind measurements by radiosondes at tropospheric altitudes and to winds from falling spheres at mesospheric altitudes. Comparisons are shown for several campaigns of radiosonde and falling sphere observations. The radar wind directions agree well to the radiosonde and falling sphere observations and are highly correlated. The winds estimated from radar measurements are less than the radiosonde data by about 15% for spaced antenna observations and by about 10% for the Doppler beam swinging experiment. At mesospheric altitudes the spaced antenna winds obtained from the wide-beam Andenes MF radar are underestimated in the order of 35% and winds from the narrow-beam Saura MF radar are underestimated by about 20% compared to falling sphere winds at altitudes between 70 and 80 km. Furthermore, the relation between wind measurements using narrow-beam and wide-beam antenna arrangements for the MF radars is discussed and VHF radar observations are compared to the wide-beam MF radar.

  14. High Resolution 3D Radar Imaging of Comet Interiors

    NASA Astrophysics Data System (ADS)

    Asphaug, E. I.; Gim, Y.; Belton, M.; Brophy, J.; Weissman, P. R.; Heggy, E.

    2012-12-01

    Knowing the interiors of comets and other primitive bodies is fundamental to our understanding of how planets formed. We have developed a Discovery-class mission formulation, Comet Radar Explorer (CORE), based on the use of previously flown planetary radar sounding techniques, with the goal of obtaining high resolution 3D images of the interior of a small primitive body. We focus on the Jupiter-Family Comets (JFCs) as these are among the most primitive bodies reachable by spacecraft. Scattered in from far beyond Neptune, they are ultimate targets of a cryogenic sample return mission according to the Decadal Survey. Other suitable targets include primitive NEOs, Main Belt Comets, and Jupiter Trojans. The approach is optimal for small icy bodies ~3-20 km diameter with spin periods faster than about 12 hours, since (a) navigation is relatively easy, (b) radar penetration is global for decameter wavelengths, and (c) repeated overlapping ground tracks are obtained. The science mission can be as short as ~1 month for a fast-rotating JFC. Bodies smaller than ~1 km can be globally imaged, but the navigation solutions are less accurate and the relative resolution is coarse. Larger comets are more interesting, but radar signal is unlikely to be reflected from depths greater than ~10 km. So, JFCs are excellent targets for a variety of reasons. We furthermore focus on the use of Solar Electric Propulsion (SEP) to rendezvous shortly after the comet's perihelion. This approach leaves us with ample power for science operations under dormant conditions beyond ~2-3 AU. This leads to a natural mission approach of distant observation, followed by closer inspection, terminated by a dedicated radar mapping orbit. Radar reflections are obtained from a polar orbit about the icy nucleus, which spins underneath. Echoes are obtained from a sounder operating at dual frequencies 5 and 15 MHz, with 1 and 10 MHz bandwidths respectively. The dense network of echoes is used to obtain global 3D

  15. Global digital topography mapping using a scanning radar altimeter

    NASA Technical Reports Server (NTRS)

    Elachi, C.; Im, K. E.; Li, F.; Rodriguez, E.

    1987-01-01

    The conceptual design of a Scanning Radar Altimeter system capable of collecting less than 300-m spatial and less than 3-m height resolution digital topography data for the entire globe, from an orbital platform, is presented. A 37-GHz frequency SRA system is used to achieve the requisite resolution while reducing antenna length in the along-track dimension. Near-global coverage in a short time period is obtained by scanning the antenna beam cross-track, in a swath of about 100 km. Attention is given to the algorithm that will be used to retrieve pixel height from the return waveform.

  16. Interferometric synthetic aperture radar studies of Alaska volcanoes

    USGS Publications Warehouse

    Lu, Zhiming; Wicks, C.; Power, J.; Dzurisin, D.; Thatcher, W.; Masterlark, Timothy

    2002-01-01

    Interferometric synthetic aperture radar (InSAR) imaging is a recently developed geodetic technique capable of measuring ground-surface deformation with centimeter to subcentimeter vertical precision and spatial resolution of tens-of-meter over a relatively large region (~104 km2). The spatial distribution of surface deformation data, derived from InSAR images, enables the construction of detailed mechanical models to enhance the study of magmatic and tectonic processes associated with volcanoes. This paper summarizes our recent InSAR studies of several Alaska volcanoes, which include Okmok, Akutan, Kiska, Augustine, Westdahl, and Peulik volcanoes.

  17. Technology: Photonics illuminates the future of radar

    NASA Astrophysics Data System (ADS)

    McKinney, Jason D.

    2014-03-01

    The first implementation of a fully photonics-based coherent radar system shows how photonic methods for radio-frequency signal generation and measurement may facilitate the development of software-defined radar systems. See Letter p.341

  18. Obstacle penetrating dynamic radar imaging system

    DOEpatents

    Romero, Carlos E.; Zumstein, James E.; Chang, John T.; Leach, Jr.. Richard R.

    2006-12-12

    An obstacle penetrating dynamic radar imaging system for the detection, tracking, and imaging of an individual, animal, or object comprising a multiplicity of low power ultra wideband radar units that produce a set of return radar signals from the individual, animal, or object, and a processing system for said set of return radar signals for detection, tracking, and imaging of the individual, animal, or object. The system provides a radar video system for detecting and tracking an individual, animal, or object by producing a set of return radar signals from the individual, animal, or object with a multiplicity of low power ultra wideband radar units, and processing said set of return radar signals for detecting and tracking of the individual, animal, or object.

  19. Meteorological radar facility. Part 1: System design

    NASA Technical Reports Server (NTRS)

    Brassaw, L. L., Jr.; Hamren, S. D.; Mullins, W. H.; Schweitzer, B. P.

    1976-01-01

    A compilation of information regarding systems design of space shuttles used in meteorological radar probes is presented. Necessary radar equipment is delineated, while space system elements, calibration techniques, antenna systems and other subsystems are reviewed.

  20. Extended target recognition in cognitive radar networks.

    PubMed

    Wei, Yimin; Meng, Huadong; Liu, Yimin; Wang, Xiqin

    2010-01-01

    We address the problem of adaptive waveform design for extended target recognition in cognitive radar networks. A closed-loop active target recognition radar system is extended to the case of a centralized cognitive radar network, in which a generalized likelihood ratio (GLR) based sequential hypothesis testing (SHT) framework is employed. Using Doppler velocities measured by multiple radars, the target aspect angle for each radar is calculated. The joint probability of each target hypothesis is then updated using observations from different radar line of sights (LOS). Based on these probabilities, a minimum correlation algorithm is proposed to adaptively design the transmit waveform for each radar in an amplitude fluctuation situation. Simulation results demonstrate performance improvements due to the cognitive radar network and adaptive waveform design. Our minimum correlation algorithm outperforms the eigen-waveform solution and other non-cognitive waveform design approaches.

  1. German Radar Observation Shuttle Experiment (ROSE)

    NASA Technical Reports Server (NTRS)

    Sleber, A. J.; Hartl, P.; Haydn, R.; Hildebrandt, G.; Konecny, G.; Muehlfeld, R.

    1984-01-01

    The success of radar sensors in several different application areas of interest depends on the knowledge of the backscatter of radar waves from the targets of interest, the variance of these interaction mechanisms with respect to changing measurement parameters, and the determination of the influence of he measuring systems on the results. The incidence-angle dependency of the radar cross section of different natural targets is derived. Problems involved by the combination of data gained with different sensors, e.g., MSS-, TM-, SPOTand SAR-images are analyzed. Radar cross-section values gained with ground-based radar spectrometers and spaceborne radar imaging, and non-imaging scatterometers and spaceborne radar images from the same areal target are correlated. The penetration of L-band radar waves into vegetated and nonvegetated surfaces is analyzed.

  2. Radar Observation of Insects - Mosquitoes

    NASA Technical Reports Server (NTRS)

    Frost, E.; Downing, J.

    1979-01-01

    Tests were conducted at several sites over the coastal lowlands of New Jersey and over a region of high plains and low mountains in Oklahoma. In one area, a salt marsh in New Jersey, extensive ground tests were combined with laboratory data on expected insect backscatter to arrive at an extremely convincing model of the insect origin of most Dot Angels. A great deal of insight was studied from radar on the buildup and dispersal of insect swarms, since radar can follow where other means of trapping and observation cannot. Data on large-scale behavior as a function of wind and topography are presented. Displayed techniques which show individual or small swarm motion within some larger cloud or mass, or which can show the overall motion over great distances were developed. The influence of wind and terrain on insect motion and dispersal is determined from radar data.

  3. Scanning ARM Cloud Radar Handbook

    SciTech Connect

    Widener, K; Bharadwaj, N; Johnson, K

    2012-06-18

    The scanning ARM cloud radar (SACR) is a polarimetric Doppler radar consisting of three different radar designs based on operating frequency. These are designated as follows: (1) X-band SACR (X-SACR); (2) Ka-band SACR (Ka-SACR); and (3) W-band SACR (W-SACR). There are two SACRs on a single pedestal at each site where SACRs are deployed. The selection of the operating frequencies at each deployed site is predominantly determined by atmospheric attenuation at the site. Because RF attenuation increases with atmospheric water vapor content, ARM's Tropical Western Pacific (TWP) sites use the X-/Ka-band frequency pair. The Southern Great Plains (SGP) and North Slope of Alaska (NSA) sites field the Ka-/W-band frequency pair. One ARM Mobile Facility (AMF1) has a Ka/W-SACR and the other (AMF2) has a X/Ka-SACR.

  4. Airborne Differential Doppler Weather Radar

    NASA Technical Reports Server (NTRS)

    Meneghini, R.; Bidwell, S.; Liao, L.; Rincon, R.; Heymsfield, G.; Hildebrand, Peter H. (Technical Monitor)

    2001-01-01

    The Precipitation Radar aboard the Tropical Rain Measuring Mission (TRMM) Satellite has shown the potential for spaceborne sensing of snow and rain by means of an incoherent pulsed radar operating at 13.8 GHz. The primary advantage of radar relative to passive instruments arises from the fact that the radar can image the 3-dimensional structure of storms. As a consequence, the radar data can be used to determine the vertical rain structure, rain type (convective/stratiform) effective storm height, and location of the melting layer. The radar, moreover, can be used to detect snow and improve the estimation of rain rate over land. To move toward spaceborne weather radars that can be deployed routinely as part of an instrument set consisting of passive and active sensors will require the development of less expensive, lighter-weight radars that consume less power. At the same time, the addition of a second frequency and an upgrade to Doppler capability are features that are needed to retrieve information on the characteristics of the drop size distribution, vertical air motion and storm dynamics. One approach to the problem is to use a single broad-band transmitter-receiver and antenna where two narrow-band frequencies are spaced apart by 5% to 10% of the center frequency. Use of Ka-band frequencies (26.5 GHz - 40 GHz) affords two advantages: adequate spatial resolution can be attained with a relatively small antenna and the differential reflectivity and mean Doppler signals are directly related to the median mass diameter of the snow and raindrop size distributions. The differential mean Doppler signal has the additional property that this quantity depends only on that part of the radial speed of the hydrometeors that is drop-size dependent. In principle, the mean and differential mean Doppler from a near-nadir viewing radar can be used to retrieve vertical air motion as well as the total mean radial velocity. In the paper, we present theoretical calculations for the

  5. High-frequency Doppler radar measurements of the Florida current in Summer 1983

    NASA Astrophysics Data System (ADS)

    Schott, F.; Leaman, K.; Samuels, G.; Frisch, A. S.; Fontino, I. Popa

    1985-01-01

    An oceanographic evaluation is carried out here of high-frequency (HF) Doppler radar measurements of surface currents made by the NOAA Wave Propagation Laboratory June 26 to August 4, 1983, at the western side of the Florida Straits in the area between Jupiter and West Palm Beach in the context of the Subtropical Atlantic Climate Studies. These current measurements are compared with direct current measurements made at various positions in the area covered by the radar, and investigated for their potential as transport indicator. Means and standard deviations of the downstream current component compared well with those from PEGASUS and subsurface moored current measurements carried out in the northern part of the radar current field up to 35 km distance from the coast, but there seemed to exist a bias in the southern part of the current field measured by the radar, causing significant northward mean shear about 20 km offshore. Low-frequency current fluctuations from the radar currents and near-surface moored currents were coherent for the downstream but not the small cross-stream component. Mean downstream components in a center strip of the radar current field, where data quality was found to be best, were compared with Florida Current transports as determined by cable and by moored current measurements, but transport fluctuations were small during the measurement period which fell into the summer maximum of the Florida Current. Coherence with cable transports was significant at the meander time scale of 5 days, but a longer period transport burst of 3×106 m3/s occurring during the time period was not identified in the surface current measurements. In summary, the HF radar as used in this application is useful to determine near-surface patterns of eddies and meanders but doubtful for derived quantities like energy fluxes and vorticity without additional calibration.

  6. Velocity profiles inside volcanic clouds from three-dimensional scanning microwave dual-polarization Doppler radars

    NASA Astrophysics Data System (ADS)

    Montopoli, Mario

    2016-07-01

    In this work, velocity profiles within a volcanic tephra cloud obtained by dual-polarization Doppler radar acquisitions with three-dimensional (3-D) mechanical scanning capability are analyzed. A method for segmenting the radar volumes into three velocity regimes: vertical updraft, vertical fallout, and horizontal wind advection within a volcanic tephra cloud using dual-polarization Doppler radar moments is proposed. The horizontal and vertical velocity components within the regimes are retrieved using a novel procedure that makes assumptions concerning the characteristics of the winds inside these regimes. The vertical velocities retrieved are combined with 1-D simulations to derive additional parameters including particle fallout, mass flux, and particle sizes. The explosive event occurred on 23 November 2013 at the Mount Etna volcano (Sicily, Italy), is considered a demonstrative case in which to analyze the radar Doppler signal inside the tephra column. The X-band radar (3 cm wavelength) in the Catania, Italy, airport observed the 3-D scenes of the Etna tephra cloud ~32 km from the volcano vent every 10 min. From the radar-derived vertical velocity profiles of updraft, particle fallout, and horizontal transportation, an exit velocity of 150 m/s, mass flux rate of 1.37 • 107 kg/s, particle fallout velocity of 18 m/s, and diameters of precipitating tephra particles equal to 0.8 cm are estimated on average. These numbers are shown to be consistent with theoretical 1-D simulations of plume dynamics and local reports at the ground, respectively. A thickness of 3 ± 0.36 km for the downwind ash cloud is also inferred by differentiating the radar-derived cloud top and the height of transition between the convective and buoyancy regions, the latter being inferred by the estimated vertical updraft velocity profile. The unique nature of the case study as well as the novelty of the segmentation and retrieval methods presented potentially give new insights into the

  7. A Wing Pod-based Millimeter Wave Cloud Radar on HIAPER

    NASA Astrophysics Data System (ADS)

    Vivekanandan, Jothiram; Tsai, Peisang; Ellis, Scott; Loew, Eric; Lee, Wen-Chau; Emmett, Joanthan

    2014-05-01

    One of the attractive features of a millimeter wave radar system is its ability to detect micron-sized particles that constitute clouds with lower than 0.1 g m-3 liquid or ice water content. Scanning or vertically-pointing ground-based millimeter wavelength radars are used to study stratocumulus (Vali et al. 1998; Kollias and Albrecht 2000) and fair-weather cumulus (Kollias et al. 2001). Airborne millimeter wavelength radars have been used for atmospheric remote sensing since the early 1990s (Pazmany et al. 1995). Airborne millimeter wavelength radar systems, such as the University of Wyoming King Air Cloud Radar (WCR) and the NASA ER-2 Cloud Radar System (CRS), have added mobility to observe clouds in remote regions and over oceans. Scientific requirements of millimeter wavelength radar are mainly driven by climate and cloud initiation studies. Survey results from the cloud radar user community indicated a common preference for a narrow beam W-band radar with polarimetric and Doppler capabilities for airborne remote sensing of clouds. For detecting small amounts of liquid and ice, it is desired to have -30 dBZ sensitivity at a 10 km range. Additional desired capabilities included a second wavelength and/or dual-Doppler winds. Modern radar technology offers various options (e.g., dual-polarization and dual-wavelength). Even though a basic fixed beam Doppler radar system with a sensitivity of -30 dBZ at 10 km is capable of satisfying cloud detection requirements, the above-mentioned additional options, namely dual-wavelength, and dual-polarization, significantly extend the measurement capabilities to further reduce any uncertainty in radar-based retrievals of cloud properties. This paper describes a novel, airborne pod-based millimeter wave radar, preliminary radar measurements and corresponding derived scientific products. Since some of the primary engineering requirements of this millimeter wave radar are that it should be deployable on an airborne platform

  8. Development and Performance of the Millimeter-wave Cloud Profiling Radar at 95 GHz

    NASA Astrophysics Data System (ADS)

    Takano, Toshiaki; Yamaguchi, Jun; Abe, Hideji; Futaba, Ken-Ichi; Yokote, Shin-Ichi; Kawamura, Youhei; Takamura, Tamio; Kumagai, Hiroshi; Ohno, Yuichi; Nakanishi, Yuji; Nakajima, Teruyuki

    We developed a cloud profiling radar, named FALCON-I, transmitting frequency-modulated continuous wave (FM-CW) at 95 GHz for high sensitivity and high spatial resolution ground-based observations. Millimeter wave at 95 GHz is used to realize high sensitivity to small cloud particles. An FM-CW type radar realizes similar sensitivity with much smaller output power to a pulse type radar. Two 1m-diameter parabolic antennas separated by 1.4m each other are used for transmitting and receiving the wave. The direction of the antennas is fixed at the zenith at this moment. The radar can observe clouds up to 20 km in height with a resolution of 9 m. Beam size of the antenna is as small as 0.2 degree of arc, which corresponds to 15 m at the range of 5 km. Observation results showed that the sensitivity of -34 dBZ is realized at 5 km in range, and good spatial resolutions.

  9. Radar operation in a hostile electromagnetic environment

    SciTech Connect

    Doerry, Armin Walter

    2014-03-01

    Radar ISR does not always involve cooperative or even friendly targets. An adversary has numerous techniques available to him to counter the effectiveness of a radar ISR sensor. These generally fall under the banner of jamming, spoofing, or otherwise interfering with the EM signals required by the radar sensor. Consequently mitigation techniques are prudent to retain efficacy of the radar sensor. We discuss in general terms a number of mitigation techniques.

  10. Goldstone solar system radar signal processing

    NASA Technical Reports Server (NTRS)

    Jurgens, R. F.; Satorius, E.; Sanchez, O.

    1992-01-01

    A performance analysis of the planetary radar data acquisition system is presented. These results extend previous computer simulation analysis and are facilitated by the development of a simple analytical model that predicts radar system performance over a wide range of operational parameters. The results of this study are useful to both the radar systems designer and the science investigator in establishing operational radar data acquisition parameters which result in the best systems performance for a given set of input conditions.

  11. Goldstone solar system radar signal processing

    NASA Technical Reports Server (NTRS)

    Jurgens, R.; Satorius, E.; Sanchez, O.

    1992-01-01

    A performance analysis of the planetary radar data acquisition system is presented. These results extend previous computer simulation analysis and are facilitated by the development of a simple analytical model that predicts radar system performance over a wide range of operational parameters. The results of this study are useful to both the radar system designer and the science investigator in establishing operational radar data acquisition parameters which result in the best systems performance for a given set of input conditions.

  12. An MSK Waveform for Radar Applications

    NASA Technical Reports Server (NTRS)

    Quirk, Kevin J.; Srinivasan, Meera

    2009-01-01

    We introduce a minimum shift keying (MSK) waveform developed for use in radar applications. This waveform is characterized in terms of its spectrum, autocorrelation, and ambiguity function, and is compared with the conventionally used bi-phase coded (BPC) radar signal. It is shown that the MSK waveform has several advantages when compared with the BPC waveform, and is a better candidate for deep-space radar imaging systems such as NASA's Goldstone Solar System Radar.

  13. SAR Ambiguity Study for the Cassini Radar

    NASA Technical Reports Server (NTRS)

    Hensley, Scott; Im, Eastwood; Johnson, William T. K.

    1993-01-01

    The Cassini Radar's synthetic aperture radar (SAR) ambiguity analysis is unique with respect to other spaceborne SAR ambiguity analyses owing to the non-orbiting spacecraft trajectory, asymmetric antenna pattern, and burst mode of data collection. By properly varying the pointing, burst mode timing, and radar parameters along the trajectory this study shows that the signal-to-ambiguity ratio of better than 15 dB can be achieved for all images obtained by the Cassini Radar.

  14. FMCW Radar Jamming Techniques and Analysis

    DTIC Science & Technology

    2013-09-01

    discussed. 14. SUBJECT TERMS FMCW Radar , LPI , Jamming, Electronic Warfare 15. NUMBER OF PAGES 103 16. PRICE CODE 17. SECURITY CLASSIFICATION...Among the many variations of LPI radar systems, Frequency-Modulated Continuous Wave ( FMCW ) radar has not only the ability to avoid detection, but... LPI radars and possible electronic protection (EP) mechanisms that may be implemented in the FMCW emitter. The research questions can be summarized

  15. 7 CFR 29.1035 - Mixed color (KM).

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Mixed color (KM). 29.1035 Section 29.1035 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 92) § 29.1035 Mixed color (KM). Distinctly different colors of the type mingled together....

  16. 7 CFR 29.1035 - Mixed color (KM).

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Mixed color (KM). 29.1035 Section 29.1035 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 92) § 29.1035 Mixed color (KM). Distinctly different colors of the type mingled together....

  17. 7 CFR 29.1035 - Mixed color (KM).

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Mixed color (KM). 29.1035 Section 29.1035 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 92) § 29.1035 Mixed color (KM). Distinctly different colors of the type mingled together....

  18. 7 CFR 29.1035 - Mixed color (KM).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Mixed color (KM). 29.1035 Section 29.1035 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 92) § 29.1035 Mixed color (KM). Distinctly different colors of the type mingled together....

  19. 7 CFR 29.1035 - Mixed color (KM).

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Mixed color (KM). 29.1035 Section 29.1035 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 92) § 29.1035 Mixed color (KM). Distinctly different colors of the type mingled together....

  20. Measured Changes in C-Band Radar Reflectivity of Clear Air Caused by Aircraft Wake Vortices

    NASA Technical Reports Server (NTRS)

    Mackenzie, Anne I.

    1997-01-01

    Wake vortices from a C-130 airplane were observed at the NASA Wallops Flight Facility with a ground-based, monostatic C-band radar and an antenna-mounted boresight video camera. The airplane wake was viewed from a distance of approximately 1 km, and radar scanning was adjusted to cross a pair of marker smoke trails generated by the C-130. For each airplane pass, changes in radar reflectivity were calculated by subtracting the signal magnitudes during an initial clutter scan from the signal magnitudes during vortex-plus-clutter scans. The results showed both increases and decreases in reflectivity on and near the smoke trails in a characteristic sinusoidal pattern of heightened reflectivity in the center and lessened reflectivity at the sides. Reflectivity changes in either direction varied from -131 to -102 dBm(exp -1); the vortex-plus-clutter to noise ratio varied from 20 to 41 dB. The radar recordings lasted 2.5 min each; evidence of wake vortices was found for up to 2 min after the passage of the airplane. Ground and aircraft clutter were eliminated as possible sources of the disturbance by noting the occurrence of vortex signatures at different positions relative to the ground and the airplane. This work supports the feasibility of vortex detection by radar, and it is recommended that future radar vortex detection be done with Doppler systems.