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Sample records for absolute cavity radiometer

  1. Calibration of a Solar Absolute Cavity Radiometer with Traceability to the World Radiometric Reference

    SciTech Connect

    Reda, I.

    1996-01-01

    This report describes the present method of establishing traceability of absolute cavity radiometers to the World Radiometric Reference (WRR) through the process employed in the International Pyrheliometer Comparisons (IPC). This method derives the WRR reduction factor for each of the participating cavity radiometers. An alternative method is proposed, described, and evaluated as a way to reduce the uncertainty in the comparison process. The two methods are compared using a sample of data from the recent IPC-VIII conducted from September 25th to October 13th, 1995 at the World Radiation Center in Davos, Switzerland. A description of absolute cavity radiometers is also included, using a PMO-6 as an example of active cavity radiometers, and a HF as an example of passive cavity radiometers.

  2. Low-cost solar array project: Four absolute cavity radiometer (pyrheliometer) intercomparisons at New River, Arizona: Radiometer standards

    NASA Technical Reports Server (NTRS)

    Estey, R. S.; Seaman, C. H.

    1981-01-01

    Four detailed intercomparisons were made for a number of models of cavity-type self-calibrating radiometers (pyrheliometers). Each intercomparison consisted of simultaneous readings of pyrheliometers at 30-second intervals in runs of 10 minutes, with at least 15 runs per intercomparison. Twenty-seven instruments were in at least one intercomparison, and five were in all four. Summarized results and all raw data are provided from the intercomparisons.

  3. Transient conduction-radiation analysis of an absolute active cavity radiometer using finite elements

    NASA Technical Reports Server (NTRS)

    Mahan, J. R.; Kowsary, F.; Tira, N.; Gardiner, B. D.

    1987-01-01

    A NASA-developed finite element-based model of a generic active cavity radiometer (ACR) has been developed in order to study the dependence on operating temperature of the closed-loop and open-loop transient response of the instrument. Transient conduction within the sensing element is explored, and the transient temperature distribution resulting from the application of a time-varying radiative boundary condition is calculated. The results verify the prediction that operation of an ACR at cryogenic temperatures results in large gains in frequency response.

  4. Results of Second Outdoor Comparison Between Absolute Cavity Pyrgeometer (ACP) and Infrared Integrating Sphere (IRIS) Radiometer at PMOD (Presentation)

    SciTech Connect

    Reda, I.; Grobner, J.; Wacker, S.

    2014-01-01

    The Absolute Cavity Pyrgeometer (ACP) and InfraRed Integrating Sphere radiometer (IRIS) are developed to establish a world reference for calibrating pyrgeometers with traceability to SI units. The two radiometers are un-windowed with negligible spectral dependence, and traceable to SI units through the temperature scale (ITS-90). The second outdoor comparison between the two designs was held from September 30 to October 11, 2013 at the Physikalisch-Metorologisches Observatorium Davos (PMOD). The difference between the irradiance measured by ACP and that of the IRIS was within 1 W/m2 (3 IRISs: PMOD + Australia + Germany). From the first and second comparisons, a difference of 4-6 W/m2 was observed between the irradiance measured by ACP&IRIS and that of the interim World Infrared Standard Group (WISG). This presentation includes results from the first and second comparison in an effort to establish the world reference for pyrgeometer calibrations, a key deliverable for the World Meteorological Organization (WMO), and the DOE-ASR.

  5. Characterization of the DARA solar absolute radiometer

    NASA Astrophysics Data System (ADS)

    Finsterle, W.; Suter, M.; Fehlmann, A.; Kopp, G.

    2011-12-01

    The Davos Absolute Radiometer (DARA) prototype is an Electrical Substitution Radiometer (ESR) which has been developed as a successor of the PMO6 type on future space missions and ground based TSI measurements. The DARA implements an improved thermal design of the cavity detector and heat sink assembly to minimize air-vacuum differences and to maximize thermal symmetry of measuring and compensating cavity. The DARA also employs an inverted viewing geometry to reduce internal stray light. We will report on the characterization and calibration experiments which were carried out at PMOD/WRC and LASP (TRF).

  6. Results of First Outdoor Comparison Between Absolute Cavity Pyrgeometer (ACP) and Infrared Integrating Sphere (IRIS) Radiometer at PMOD (Presentation)

    SciTech Connect

    Reda, I.; Grobner, J.; Wacker, S.; Stoffel, T.

    2013-03-01

    The ACP and IRIS are developed to establish a world reference for calibrating pyrgeometers with traceability to SI units. The two radiometers are unwindowed with negligible spectral dependence, and traceable to SI units through the temperature scale (ITS-90). The first outdoor comparison between the two designs was held from January 28 to February 8, 2013 at the Physikalisch-Metorologisches Observatorium Davos (PMOD). The difference between the irradiance measured by ACP and that of IRIS was within 1 W/m2. A difference of 5 W/m2 was observed between the irradiance measured by ACP&IRIS and that of the interim World Infrared Standard Group (WISG).

  7. Absolute Radiometer for Reproducing the Solar Irradiance Unit

    NASA Astrophysics Data System (ADS)

    Sapritskii, V. I.; Pavlovich, M. N.

    1989-01-01

    A high-precision absolute radiometer with a thermally stabilized cavity as receiving element has been designed for use in solar irradiance measurements. The State Special Standard of the Solar Irradiance Unit has been built on the basis of the developed absolute radiometer. The Standard also includes the sun tracking system and the system for automatic thermal stabilization and information processing, comprising a built-in microcalculator which calculates the irradiance according to the input program. During metrological certification of the Standard, main error sources have been analysed and the non-excluded systematic and accidental errors of the irradiance-unit realization have been determined. The total error of the Standard does not exceed 0.3%. Beginning in 1984 the Standard has been taking part in a comparison with the Å 212 pyrheliometer and other Soviet and foreign standards. In 1986 it took part in the international comparison of absolute radiometers and standard pyrheliometers of socialist countries. The results of the comparisons proved the high metrological quality of this Standard based on an absolute radiometer.

  8. A cavity radiometer for Earth albedo measurement, phase 1

    NASA Technical Reports Server (NTRS)

    1987-01-01

    Radiometric measurements of the directional albedo of the Earth requires a detector with a flat response from 0.2 to 50 microns, a response time of about 2 seconds, a sensitivity of the order of 0.02 mw/sq cm, and a measurement uncertainty of less than 5 percent. Absolute cavity radiometers easily meet the spectral response and accuracy requirements for Earth albedo measurements, but the radiometers available today lack the necessary sensitivity and response time. The specific innovations addressed were the development of a very low thermal mass cavity and printed/deposited thermocouple sensing elements which were incorporated into the radiometer design to produce a sensitive, fast response, absolute radiometer. The cavity is applicable to the measurement of the reflected and radiated fluxes from the Earth surface and lower atmosphere from low Earth orbit satellites. The effort consisted of requirements and thermal analysis; design, construction, and test of prototype elements of the black cavity and sensor elements to show proof-of-concept. The results obtained indicate that a black body cavity sensor that has inherently a flat response from 0.2 to 50 microns can be produced which has a sensitivity of at least 0.02 mw/sq cm per micro volt ouput and with a time constant of less than two seconds. Additional work is required to develop the required thermopile.

  9. Mid-infrared absolute spectral responsivity scale based on an absolute cryogenic radiometer and an optical parametric oscillator laser

    NASA Astrophysics Data System (ADS)

    Zhao, Kun; Shi, Xueshun; Chen, Haidong; Liu, Yulong; Liu, Changming; Chen, Kunfeng; Li, Ligong; Gan, Haiyong; Ma, Chong

    2016-06-01

    We are reporting on a laser-based absolute spectral responsivity scale in the mid-infrared spectral range. By using a mid-infrared tunable optical parametric oscillator as the laser source, the absolute responsivity scale has been established by calibrating thin-film thermopile detectors against an absolute cryogenic radiometer. The thin-film thermopile detectors can be then used as transfer standard detectors. The extended uncertainty of the absolute spectral responsivity measurement has been analyzed to be 0.58%–0.68% (k  =  2).

  10. Mid-infrared absolute spectral responsivity scale based on an absolute cryogenic radiometer and an optical parametric oscillator laser

    NASA Astrophysics Data System (ADS)

    Zhao, Kun; Shi, Xueshun; Chen, Haidong; Liu, Yulong; Liu, Changming; Chen, Kunfeng; Li, Ligong; Gan, Haiyong; Ma, Chong

    2016-06-01

    We are reporting on a laser-based absolute spectral responsivity scale in the mid-infrared spectral range. By using a mid-infrared tunable optical parametric oscillator as the laser source, the absolute responsivity scale has been established by calibrating thin-film thermopile detectors against an absolute cryogenic radiometer. The thin-film thermopile detectors can be then used as transfer standard detectors. The extended uncertainty of the absolute spectral responsivity measurement has been analyzed to be 0.58%-0.68% (k  =  2).

  11. Intercomparison of the LBIR Absolute Cryogenic Radiometers to the NIST Optical Power Measurement Standard

    PubMed Central

    Fedchak, James A.; Carter, Adriaan C.; Datla, Raju

    2006-01-01

    The Low Background Infrared calibration (LBIR) facility at the National Institute of Standards and Technology (NIST) presently maintains four absolute cryogenic radiometers (ACRs) which serve as standard reference detectors for infrared calibrations performed by the facility. The primary standard for optical power measurements at NIST-Gaithersburg has been the High Accuracy Cryogenic Radiometer (HACR). Recently, an improved radiometer, the Primary Optical Watt Radiometer (POWR), has replaced the HACR as the primary standard. In this paper, we present the results of comparisons between the radiometric powers measured by the four ACRs presently maintained by the LBIR facility to that measured by the HACR and POWR. This was done by using a Si photodiode light-trapping detector as a secondary transfer standard to compare the primary national standards to the ACRs maintained by the LBIR facility. The technique used to compare an ACR to the trap detector is described in detail. The absolute optical power measurements are found to be within 0.1 % of the primary standard for all the ACRs examined in this study. PMID:27274936

  12. Absolute intensity calibration of the 32-channel heterodyne radiometer on experimental advanced superconducting tokamak

    SciTech Connect

    Liu, X.; Zhao, H. L.; Liu, Y. Li, E. Z.; Han, X.; Ti, A.; Hu, L. Q.; Zhang, X. D.; Domier, C. W.; Luhmann, N. C.

    2014-09-15

    This paper presents the results of the in situ absolute intensity calibration for the 32-channel heterodyne radiometer on the experimental advanced superconducting tokamak. The hot/cold load method is adopted, and the coherent averaging technique is employed to improve the signal to noise ratio. Measured spectra and electron temperature profiles are compared with those from an independent calibrated Michelson interferometer, and there is a relatively good agreement between the results from the two different systems.

  13. Cryogenic absolute radiometers as laboratory irradiance standards, remote sensing detectors, and pyroheliometers

    NASA Technical Reports Server (NTRS)

    Foukal, Peter V.; Hoyt, C.; Kochling, H.; Miller, P.

    1990-01-01

    The dramatic improvement in heat diffusivity of pure Cu at liquid-He temperatures makes possible very important advances in the absolute accuracy, reproducibility, sensitivity, and time constant of cryogenic electrical substitution radiometers (ESRs), relative to conventional ESRs. The design and characterization of a table-top cryogenic ESR now available for detector calibration work to the 0.01-percent level of absolute accuracy under laser illumination is discussed. A sensitive cryogenic ESR recently delivered to the NIST for radiometric calibrations of black bodies is also described, along with the design and testing of a very fast cryogenic ESR developed for NASA remote-sensing studies of the earth's radiation budget.

  14. Infrared Cavity Radiometer Reflectometry in Support of Total Solar Irradiance Instruments

    NASA Astrophysics Data System (ADS)

    Hanssen, L. M.; Zeng, J.; Wilthan, B.; Morrill, J. S.; Kopp, G.

    2011-12-01

    A key component required to achieve a high degree of accuracy in satellite solar irradiance measurements using cavity radiometers, is the characterization of the cavity spectral absorptance over the broad spectral range of the Solar output. This includes the infrared region up to at least 10 μm. In order to accurately measure high levels of absorptance of cavities, NIST has developed a laser and integrating sphere based facility (the Complete Hemispherical Infrared Laser-based Reflectometer (CHILR)). The system is used for both radiometer and blackbody cavity characterization. We report the results of reflectance (1 - absorptance) measurements of radiometer cavities designed for two solar irradiance measurement instruments: 1) the Active Cavity Radiometer Irradiance Monitor (ACRIM) and 2) the Total Irradiance Monitor (TIM) instrument on the SORCE and TSIS missions. The measurements were made using the NIST CHILR instrument as well as the Infrared Reference Integrating Sphere (IRIS) for relative spectral reflectance. The IRIS was used to obtain relative spectral reflectance for the TIM cones. The IRIS was also used to obtain the spectral reflectance of other surfaces in the ACRIM instrument that also interact with the incident irradiance and potentially affect the cavity performance. These reflectance results are used to validate previously estimated performance parameters of the two instruments.

  15. In-flight shortwave calibrations of the active cavity radiometers using tungsten lamps

    NASA Technical Reports Server (NTRS)

    Thomas, Susan; Lee, Robert B.; Gibson, Michael A.; Wilson, Robert S.; Bolden, William C.

    1992-01-01

    The Earth Radiation Budget Experiment (ERBE) active cavity radiometers are used to measure the incoming solar, reflected shortwave solar, and emitted longwave radiations from the Earth and atmosphere. The radiometers are located on the NASA's Earth Radiation Budget Satellite (ERBS) and the NOAA-9 and NOAA-10 spacecraft platforms. Two of the radiometers, one wide field of view (WFOV) and one medium field of view (MFOV), measure the total radiation in the spectral region of 0.2 to 50 microns and the other two radiometers (WFOV and MFOV) measure the shortwave radiation in the spectral region of 0.2 to 5.0 microns. For the in-flight calibrations, tungsten lamp and the sun are used as calibration sources for shortwave radiometers. Descriptions of the tungsten lamp and solar calibration procedures and mechanisms are presented. The tungsten lamp calibration measurements are compared with the measurements of solar calibration for ERBS and NOAA-9 instruments.

  16. Double-cavity radiometer for high-flux density solar radiation measurements.

    PubMed

    Parretta, A; Antonini, A; Armani, M; Nenna, G; Flaminio, G; Pellegrino, M

    2007-04-20

    A radiometric method has been developed, suitable for both total power and flux density profile measurement of concentrated solar radiation. The high-flux density radiation is collected by a first optical cavity, integrated, and driven to a second optical cavity, where, attenuated, it is measured by a conventional radiometer operating under a stationary irradiation regime. The attenuation factor is regulated by properly selecting the aperture areas in the two cavities. The radiometer has been calibrated by a pulsed solar simulator at concentration levels of hundreds of suns. An optical model and a ray-tracing study have also been developed and validated, by which the potentialities of the radiometer have been largely explored.

  17. PREMOS Absolute Radiometer Calibration and Implications to on-orbit Measurements of the Total Solar Irradiance

    NASA Astrophysics Data System (ADS)

    Fehlmann, A.; Kopp, G.; Schmutz, W. K.; Winkler, R.; Finsterle, W.; Fox, N.

    2011-12-01

    On orbit measurements starting in the late 1970's, have revealed the 11 year cycle of the Total Solar Irradiance (TSI). However, the absolute results from individual experiments differ although all instrument teams claim to measure an absolute value. Especially the data from the TIM/SORCE experiment confused the community as it measures 0.3 % lower than the other instruments, e.g. VIRGO/SOHO by PMOD/WRC, which clearly exceeds the uncertainty stated for the absolute characterization of the experiments. The PREMOS package on the PICARD platform launched in June 2010 is the latest space experiment by PMOD/WRC measuring the TSI. We have put great effort in the calibration and characterization of this instrument in order to resolve the inter-instrument differences. We performed calibrations at the National Physical Laboratory (NPL) in London and the Laboratory for Atmospheric and Space Physics (LASP) in Boulder against national SI standards for radiant power using a laser beam with a diameter being smaller than the aperture of the instrument. These measurements together with the World Radiometric Reference (WRR) calibration in Davos allowed to compare the WRR and the SI radiant power scale. We found that the WRR lies 0.18 % above the SI radiant power scale which explains a part of the VIRGO-TIM difference. The Total solar irradiance Radiometer Facility (TRF) at the LASP allows to generate a beam that over fills the apertures of our instruments, giving the presently best available representation of solar irradiance in a laboratory. These irradiance calibrations revealed a stray light contribution between 0.09 and 0.3 % to the measurements which had been underestimated in the characterization of our instruments. Using the irradiance calibrations, we found that the WRR lies 0.32 % above the TRF scale which in turn explains the full VIRGO-TIM difference. The first light PREMOS measurements in space confirmed our findings. If we use the WRR calibration, PREMOS yields a TSI

  18. ACRIM III Radiometer Cavity Reflectance at a Variety of Wavelengths across the Solar Spectrum

    NASA Astrophysics Data System (ADS)

    Lorentz, S. R.; Morrill, J. S.; Hanssen, L. M.; Zeng, J.

    2010-12-01

    We will present measurements of the reflected power from a spare ACRIM III radiometer cavity at a variety of wavelengths across the solar spectrum in order to generate a correction factor for the ACRIM III Total Solar Irradiance (TSI) measurements. These measurements are being performed as part of the NRL support of the ACRIMSAT Mission Extension. The cavity reflectance will be measured using a laser and integrating sphere technique at several wavelengths from the visible to the infra-red (IR). The visible wavelengths will be 457 nm, 488 nm, 532 nm, and 633 nm. The measurements at the IR wavelengths will include measurements at between 1 µm and 5 µm and between 9 µm and 11 µm. The results will include measurements where the laser has been rastered across the cavity entrance to produce a reflectance map. Uncertainty goals for the measurements are < 25 ppm in the visible and < 50 ppm in the IR.

  19. Optimum cavity length and absolute cavity detuning in acousto-optically mode-locked argon-ion lasers

    NASA Astrophysics Data System (ADS)

    Ruddock, I. S.; Illingworth, R.

    1987-09-01

    Acousto-optic mode-locking in an argon-ion laser was investigated in detail. Measurement of the discharge current is shown to be an accurate means of locating the optimum cavity length which depends strongly on level of excitation. The absolute cavity mismatch between the optimum length and that corresponding to c/4 vRF was determined by direct measurement and by using a cw dye laser as an active interferometer.

  20. The absolute radiometric calibration of the advanced very high resolution radiometer

    NASA Technical Reports Server (NTRS)

    Slater, P. N.; Teillet, P. M.; Mao, Y.

    1987-01-01

    The early results of an absolute radiometric calibration of the NOAA-9 AVHRR sensor indicate significant degradations in the response of bands 1 and 2 compared to prelaunch values. The results are currently in the process of being verified and it may be that refinements of the methodology will be in order as additional data sets are analyzed. The LANDSAT TM calibration used in this approach is known to be very precise and the Herman radiative transfer code, supplemented by the 5-S code for gaseous transmission, is reliable as well. The extent to which other steps in the analysis procedure give rise to uncertainties in the results is currently under investigation. Particular attention is being given to the geometric matching of the AVHRR and TM imagery, as well as to the spectral redistribution procedure. By taking advantage of a reasonably precise calibration of TM imagery acquired on the same day as the AVHRR data at White Sands, a promising approach to the in-orbit calibration of AVHRR sensors is being developed. Current efforts involve primarily the examination of additional test cases and the investigation of possible simplifications in the procedure through judicious use of atmospheric models.

  1. The absolute radiometric calibration of the advanced very high resolution radiometer

    NASA Astrophysics Data System (ADS)

    Slater, P. N.; Teillet, P. M.; Mao, Y.

    1987-09-01

    The early results of an absolute radiometric calibration of the NOAA-9 AVHRR sensor indicate significant degradations in the response of bands 1 and 2 compared to prelaunch values. The results are currently in the process of being verified and it may be that refinements of the methodology will be in order as additional data sets are analyzed. The LANDSAT TM calibration used in this approach is known to be very precise and the Herman radiative transfer code, supplemented by the 5-S code for gaseous transmission, is reliable as well. The extent to which other steps in the analysis procedure give rise to uncertainties in the results is currently under investigation. Particular attention is being given to the geometric matching of the AVHRR and TM imagery, as well as to the spectral redistribution procedure. By taking advantage of a reasonably precise calibration of TM imagery acquired on the same day as the AVHRR data at White Sands, a promising approach to the in-orbit calibration of AVHRR sensors is being developed. Current efforts involve primarily the examination of additional test cases and the investigation of possible simplifications in the procedure through judicious use of atmospheric models.

  2. Introducing an Absolute Cavity Pyrgeometer (ACP) for Improving the Atmospheric Longwave Irradiance Measurement (Poster)

    SciTech Connect

    Reda, I.; Stoffel, T.

    2012-03-01

    Advancing climate change research requires accurate and traceable measurement of the atmospheric longwave irradiance. Current measurement capabilities are limited to an estimated uncertainty of larger than +/- 4 W/m2 using the interim World Infrared Standard Group (WISG). WISG is traceable to the Systeme international d'unites (SI) through blackbody calibrations. An Absolute Cavity Pyrgeometer (ACP) is being developed to measure absolute outdoor longwave irradiance with traceability to SI using the temperature scale (ITS-90) and the sky as the reference source, instead of a blackbody. The ACP was designed by NREL and optically characterized by the National Institute of Standards and Technology (NIST). Under clear-sky and stable conditions, the responsivity of the ACP is determined by lowering the temperature of the cavity and calculating the rate of change of the thermopile output voltage versus the changing net irradiance. The absolute atmospheric longwave irradiance is then calculated with an uncertainty of +/- 3.96 W/m2 with traceability to SI. The measured irradiance by the ACP was compared with the irradiance measured by two pyrgeometers calibrated by the World Radiation Center with traceability to the WISG.

  3. Introducing an Absolute Cavity Pyrgeometer for Improving the Atmospheric Longwave Irradiance Measurement (Presentation)

    SciTech Connect

    Reda, I.; Hansen, L.; Zeng, J.

    2012-08-01

    Advancing climate change research requires accurate and traceable measurement of the atmospheric longwave irradiance. Current measurement capabilities are limited to an estimated uncertainty of larger than +/- 4 W/m2 using the interim World Infrared Standard Group (WISG). WISG is traceable to the Systeme international d'unites (SI) through blackbody calibrations. An Absolute Cavity Pyrgeometer (ACP) is being developed to measure absolute outdoor longwave irradiance with traceability to SI using the temperature scale (ITS-90) and the sky as the reference source, instead of a blackbody. The ACP was designed by NREL and optically characterized by the National Institute of Standards and Technology (NIST). Under clear-sky and stable conditions, the responsivity of the ACP is determined by lowering the temperature of the cavity and calculating the rate of change of the thermopile output voltage versus the changing net irradiance. The absolute atmospheric longwave irradiance is then calculated with an uncertainty of +/- 3.96 W/m2 with traceability to SI. The measured irradiance by the ACP was compared with the irradiance measured by two pyrgeometers calibrated by the World Radiation Center with traceability to the WISG. A total of 408 readings was collected over three different clear nights. The calculated irradiance measured by the ACP was 1.5 W/m2 lower than that measured by the two pyrgeometers that are traceable to WISG. Further development and characterization of the ACP might contribute to the effort of improving the uncertainty and traceability of WISG to SI.

  4. Validation of 1985-1997 Active Cavity Radiometer Spacecraft Measurements of Total Solar Irradiance Variability

    NASA Technical Reports Server (NTRS)

    Lee, Robert B., III; Wilson, Robert S.

    1998-01-01

    Since 1978, long-term variations in the total solar irradiance (solar constant) have been monitored using spacecraft radiometers, at the 0.01% precision level. The irradiance measurements were performed from the Earth Radiation Budget Satellite [ERBS], Nimbus-7, Solar Maximum Mission [SMM], Upper Atmosphere Research Satellite [UARS], European Retrievable Carrier (EURECA), Solar and Heliospheric Observatory [SOHO], and the Space Shuttle Atmospheric Laboratory for Applications and Science [ATLAS] spacecraft platforms. Radiometer responses can drift or shift at precision levels of a few hundreds of a percent. In-flight calibration sources are not available to detect radiometer response changes at radiometric accuracy or precision levels near the 0.01% (0.1 W/sq m) level. Inconsistent trends among the sets were used to identify possible instrumental drifts or shifts which may be incorrectly interpreted as solar irradiance changes while consistent trends among the different measurement sets were used to detect long-term irradiance variability components. In this paper, 1991-1998 corresponding ERBS, UARS, SOHO, and ATLAS irradiance measurements are inter-compared with each other as well as with the ERBS empirical irradiance fit. The empirical irradiance fit is based upon 10.7-cm solar radio flux (F10) and photometric sunspot index (PSI), indices of solar magnetic activity. Analyses of recent data sets identified no long-term shifts and drifts in the ERBS, SOHO, or UARS data sets. The typical value of the total solar irradiance is approximately 1365 Watts per meter squared (W/sq m).

  5. Absolute molecular transition frequencies measured by three cavity-enhanced spectroscopy techniques

    NASA Astrophysics Data System (ADS)

    Cygan, A.; Wójtewicz, S.; Kowzan, G.; Zaborowski, M.; Wcisło, P.; Nawrocki, J.; Krehlik, P.; Śliwczyński, Ł.; Lipiński, M.; Masłowski, P.; Ciuryło, R.; Lisak, D.

    2016-06-01

    Absolute frequencies of unperturbed 12C16O transitions from the near-infrared (3-0) band were measured with uncertainties five-fold lower than previously available data. The frequency axis of spectra was linked to the primary frequency standard. Three different cavity enhanced absorption and dispersion spectroscopic methods and various approaches to data analysis were used to estimate potential systematic instrumental errors. Except for a well established frequency-stabilized cavity ring-down spectroscopy, we applied the cavity mode-width spectroscopy and the one-dimensional cavity mode-dispersion spectroscopy for measurement of absorption and dispersion spectra, respectively. We demonstrated the highest quality of the dispersion line shape measured in optical spectroscopy so far. We obtained line positions of the Doppler-broadened R24 and R28 transitions with relative uncertainties at the level of 10-10. The pressure shifting coefficients were measured and the influence of the line asymmetry on unperturbed line positions was analyzed. Our dispersion spectra are the first demonstration of molecular spectroscopy with both axes of the spectra directly linked to the primary frequency standard, which is particularly desirable for the future reference-grade measurements of molecular spectra.

  6. 1999-2003 Shortwave Characterizations of Earth Radiation Budget Satellite (ERBS)/Earth Radiation Budget Experiment (ERBE) Broadband Active Cavity Radiometer Sensors

    NASA Technical Reports Server (NTRS)

    Lee, Robert B., III; Smith, George L.; Wong, Takmeng

    2008-01-01

    From October 1984 through May 2005, the NASA Earth Radiation Budget Satellite (ERBS/ )/Earth Radiation Budget Experiment (ERBE)ERBE nonscanning active cavity radiometers (ACR) were used to monitor long-term changes in the earth radiation budget components of the incoming total solar irradiance (TSI), earth-reflected TSI, and earth-emitted outgoing longwave radiation (OLR). From September1984 through September 1999, using on-board calibration systems, the ERBS/ERBE ACR sensor response changes, in gains and offsets, were determined from on-orbit calibration sources and from direct observations of the incoming TSI through calibration solar ports at measurement precision levels approaching 0.5 W/sq m , at satellite altitudes. On October 6, 1999, the onboard radiometer calibration system elevation drive failed. Thereafter, special spacecraft maneuvers were performed to observe cold space and the sun in order to define the post-September 1999 geometry of the radiometer measurements, and to determine the October 1999-September 2003 ERBS sensor response changes. Analyses of these special solar and cold space observations indicate that the radiometers were pointing approximately 16 degrees away from the spacecraft nadir and on the anti-solar side of the spacecraft. The special observations indicated that the radiometers responses were stable at precision levels approaching 0.5 W/sq m . In this paper, the measurement geometry determinations and the determinations of the radiometers gain and offset are presented, which will permit the accurate processing of the October 1999 through September 2003 ERBE data products at satellite and top-of-the-atmosphere altitudes.

  7. Validation of Spacecraft Active Cavity Radiometer Total Solar Irradiance (TSI) Long Term Measurement Trends Using Proxy TSI Least Squares Analyses

    NASA Technical Reports Server (NTRS)

    Lee, Robert Benjamin, III; Wilson, Robert S.

    2003-01-01

    Long-term, incoming total solar irradiance (TSI) measurement trends were validated using proxy TSI values, derived from indices of solar magnetic activity. Spacecraft active cavity radiometers (ACR) are being used to measure longterm TSI variability, which may trigger global climate changes. The TSI, typically referred to as the solar constant, was normalized to the mean earth-sun distance. Studies of spacecraft TSI data sets confirmed the existence of a 0.1 %, long-term TSI variability component within a 10-year period. The 0.1% TSI variability component is clearly present in the spacecraft data sets from the 1984-2004 time frame. Typically, three overlapping spacecraft data sets were used to validate long-term TSI variability trends. However, during the years of 1978-1984, 1989-1991, and 1993-1996, three overlapping spacecraft data sets were not available in order to validate TSI trends. The TSI was found to vary with indices of solar magnetic activity associated with recent 10-year sunspot cycles. Proxy TSI values were derived from least squares analyses of the measured TSI variability with the solar indices of 10.7-cm solar fluxes, and with limb-darked sunspot fluxes. The resulting proxy TSI values were compared to the spacecraft ACR measurements of TSI variability to detect ACR instrument degradation, which may be interpreted as TSI variability. Analyses of ACR measurements and TSI proxies are presented primarily for the 1984-2004, Earth Radiation Budget Experiment (ERBE) ACR solar monitor data set. Differences in proxy and spacecraft measurement data sets suggest the existence of another TSI variability component with an amplitude greater than or equal to 0.5 Wm-2 (0.04%), and with a cycle of 20 years or more.

  8. Relative Accuracy of 1-Minute and Daily Total Solar Radiation Data for 12 Global and 4 Direct Beam Solar Radiometers: Preprint

    SciTech Connect

    Myers, D. R.; Wilcox, S. M.

    2009-03-01

    This report evaluates the relative performance of 12 global and four direct beam solar radiometers deployed at a single site over a 12-month period. Test radiometer irradiances were compared with a reference irradiance consisting of either an absolute cavity radiometer (during calibrations) or a low uncertainty thermopile pyrheliometer (during the evaluation period) for pyrheliometers; and for pyranometers a reference global irradiance computed from the reference pyrheliometer and diffuse irradiance from a shaded pyranometer.

  9. Absolute measurements of total peroxy nitrate mixing ratios by thermal dissociation blue diode laser cavity ring-down spectroscopy.

    PubMed

    Paul, Dipayan; Osthoff, Hans D

    2010-08-01

    Peroxycarboxylic nitric anhydrides (PANs) have long been recognized as important trace gas constituents of the troposphere. Here, we describe a blue diode laser thermal dissociation cavity ring-down spectrometer for rapid and absolute measurements of total peroxyacyl nitrate (SigmaPAN) abundances at ambient concentration levels. The PANs are thermally dissociated and detected as NO2, whose mixing ratios are quantified by optical absorption at 405 nm relative to a reference channel kept at ambient temperature. The effective NO2 absorption cross-section at the diode laser emission wavelength was measured to be 6.1 x 10(-19) cm2 molecule(-1), in excellent agreement with a prediction based on a projection of a high-resolution literature absorption spectrum onto the laser line width. The performance, i.e., accuracy and precision of measurement and matrix effects, of the new 405 nm thermal dissociation cavity ring-down spectrometer was evaluated and compared to that of a 532 nm thermal dissociation cavity ring-down spectrometer using laboratory-generated air samples. The new 405 nm spectrometer was considerably more sensitive and compact than the previously constructed version. The key advantage of laser thermal dissociation cavity ring-down spectroscopy is that the measurement can be considered absolute and does not need to rely on external calibration.

  10. Characterization of an Ellipsoidal Radiometer

    PubMed Central

    Murthy, Annageri V.; Wetterlund, Ingrid; DeWitt, David P.

    2003-01-01

    An ellipsoidal radiometer has been characterized using a 25 mm variable-temperature blackbody as a radiant source. This radiometer is intended for separating radiation from convection effects in fire test methods. The characterization included angular response, responsivity, and purge-gas flow effect studies. The angular response measurements showed that the reflection from the radiometer cavity was higher on one of the cavity halves relative to the other half. Further development work may be necessary to improve the angular response. The responsivity measured with reference to a transfer-standard electrical-substitution radiometer showed dependence on the distance of the radiometer from the blackbody cavity. The purge-gas had the effect of reducing the signal output nearly linearly with flow rate. PMID:27413598

  11. Absolute distance measurement by multi-heterodyne interferometry using a frequency comb and a cavity-stabilized tunable laser.

    PubMed

    Wu, Hanzhong; Zhang, Fumin; Liu, Tingyang; Balling, Petr; Qu, Xinghua

    2016-05-20

    In this paper, we develop a multi-heterodyne system capable of absolute distance measurement using a frequency comb and a tunable diode laser locked to a Fabry-Perot cavity. In a series of subsequent measurements, numerous beat components can be obtained by downconverting the optical frequency into the RF region with multi-heterodyne interferometry. The distances can be measured via the mode phases with a series of synthetic wavelengths. The comparison with the reference interferometer shows an agreement within 1.5 μm for the averages of five measurements and 2.5 μm for the single measurement, which is at the 10-8 relative precision level. PMID:27411152

  12. Research on temperature measurement technology for graphite-cone-absorption-cavity absolute calorimeter

    NASA Astrophysics Data System (ADS)

    Wei, Ji Feng; Lu, Fei; Sun, Li Qun; Zhang, Kai; Hu, Xiao Yang; Zhou, Shan; Xu, De

    2015-02-01

    The nonlinear effect of materials and sensors in high-energy laser calorimeters is especially obvious—due to the steep temperature gradients of their absorbers. Significant measurement errors occur when traditional integral temperature sensors and methods are utilized. In an effort to remedy this, a method is proposed in this paper in which an absorption cavity is divided into many parts and multiple discrete thermocouple sensors are used to measure the temperature rise of the absorbers. The temperature distribution in the absorbers is theoretically analyzed, numerically simulated, and verified through experimentation. Energy measurement results are compared according to the temperature distribution for different layouts of thermocouples. A high-accuracy calorimeter is developed by setting and optimizing thermocouple layout, as well as correcting various elements such as the specific heat of graphite and responsivity of thermocouples. The calorimeter employing this measurement method is calibrated against a standard energy meter, resulting in correction coefficient of 1.027 and relative standard deviation of the correction coefficient of only 0.8%. Theoretical analysis, numerical simulation, and experimental verification all prove that the proposed method successfully improves measurement accuracy.

  13. Research on temperature measurement technology for graphite-cone-absorption-cavity absolute calorimeter.

    PubMed

    Wei, Ji Feng; Lu, Fei; Sun, Li Qun; Zhang, Kai; Hu, Xiao Yang; Zhou, Shan; Xu, De

    2015-02-01

    The nonlinear effect of materials and sensors in high-energy laser calorimeters is especially obvious-due to the steep temperature gradients of their absorbers. Significant measurement errors occur when traditional integral temperature sensors and methods are utilized. In an effort to remedy this, a method is proposed in this paper in which an absorption cavity is divided into many parts and multiple discrete thermocouple sensors are used to measure the temperature rise of the absorbers. The temperature distribution in the absorbers is theoretically analyzed, numerically simulated, and verified through experimentation. Energy measurement results are compared according to the temperature distribution for different layouts of thermocouples. A high-accuracy calorimeter is developed by setting and optimizing thermocouple layout, as well as correcting various elements such as the specific heat of graphite and responsivity of thermocouples. The calorimeter employing this measurement method is calibrated against a standard energy meter, resulting in correction coefficient of 1.027 and relative standard deviation of the correction coefficient of only 0.8%. Theoretical analysis, numerical simulation, and experimental verification all prove that the proposed method successfully improves measurement accuracy. PMID:25725875

  14. Absolute cavity pyrgeometer

    DOEpatents

    Reda, Ibrahim

    2013-10-29

    Implementations of the present disclosure involve an apparatus and method to measure the long-wave irradiance of the atmosphere or long-wave source. The apparatus may involve a thermopile, a concentrator and temperature controller. The incoming long-wave irradiance may be reflected from the concentrator to a thermopile receiver located at the bottom of the concentrator to receive the reflected long-wave irradiance. In addition, the thermopile may be thermally connected to a temperature controller to control the device temperature. Through use of the apparatus, the long-wave irradiance of the atmosphere may be calculated from several measurements provided by the apparatus. In addition, the apparatus may provide an international standard of pyrgeometers' calibration that is traceable back to the International System of Units (SI) rather than to a blackbody atmospheric simulator.

  15. The BAMM IIA Radiometer

    NASA Astrophysics Data System (ADS)

    Pohlman, R. T.

    1984-01-01

    The Balloon Altitude Mosaic Measurement (BAMM) IIA Radiometer is designed to make mosaic measurements in either of two modes of operation: the stare or demonstration mode and the radiometer mode. In the stare mode, background suppression and target detection can be demonstrated; in the radiometer mode the incoming energy is chopped to allow absolute measurements to be made. The Noise Equivalent Radiance (NER) in each available spectral band is less than 2.5E-8 W/cm2-sr in the stare mode and less than 1.25E-7 W/cm2-sr in the radiometer mode. The Radiometer is physically divided into two units: the Radiometer Unit and the Support Electronics Unit. The Radiometer Unit contains the optical, detection, and preprocessor sections of the instrument. Ten narrow-band spectral filters in the 2.59 to 5.1 micrometer region are mounted on a wheel and are selectable from the ground. Three telescopes on a turret allow the selection of 50, 200, or 800 meter detector footprints (at the nadir from the 100,000 ft. flight altitude). The focal plane module uses the Grumman-developed Z-dimension technology with 16 x 64 HgCdTe detectors. Included on the module are hybrid CMOS chips containing the signal conditioning circuitry for sample and hold operations, bandpass filtering, and 32:1 signal multiplexing. The second unit, the Support Electronics, supplies control signals, bias voltages, and clock signals. The output lines from the focal plane are converted to digital signals, multiplexed, and formatted for PCM trans-mission to the ground in this unit.

  16. PHOCUS radiometer

    NASA Astrophysics Data System (ADS)

    Nyström, O.; Murtagh, D.; Belitsky, V.

    2012-06-01

    PHOCUS - Particles, Hydrogen and Oxygen Chemistry in the Upper Summer Mesosphere is a Swedish sounding rocket experiment, launched in July 2011, with the main goal of investigating the upper atmosphere in the altitude range 50-110 km. This paper describes the SondRad instrument in the PHOCUS payload, a radiometer comprising two frequency channels (183 GHz and 557 GHz) aimed at exploring the water vapour concentration distribution in connection with the appearance of noctilucent (night shining) clouds. The design of the radiometer system has been done in a collaboration between Omnisys Instruments AB and the Group for Advanced Receiver Development (GARD) at Chalmers University of Technology where Omnisys was responsible for the overall design, implementation, and verification of the radiometers and backend, whereas GARD was responsible for the radiometer optics and calibration systems. The SondRad instrument covers the water absorption lines at 183 GHz and 557 GHz. The 183 GHz channel is a side-looking radiometer, while the 557 GHz radiometer is placed along the rocket axis looking in the forward direction. Both channels employ sub-harmonically pumped Schottky mixers and Fast Fourier Transform Spectrometers (FFTS) backends with 67 kHz resolution. The radiometers include novel calibration systems specifically adjusted for use with each frequency channel. The 183 GHz channel employs a continuous wave CW pilot signal calibrating the entire receiving chain, while the intermediate frequency chain (the IF-chain) of the 557 GHz channel is calibrated by injecting a signal from a reference noise source through a directional coupler. The instrument collected complete spectra for both the 183 GHz and the 557 GHz with 300 Hz data rate for the 183 GHz channel and 10 Hz data rate for the 557 GHz channel for about 60 s reaching the apogee of the flight trajectory and 100 s after that. With lossless data compression using variable resolution over the spectrum, the data set was

  17. PHOCUS radiometer

    NASA Astrophysics Data System (ADS)

    Nyström, O.; Murtagh, D.; Belitsky, V.

    2012-01-01

    PHOCUS - Particles, Hydrogen and Oxygen Chemistry in the Upper Summer Mesosphere is a Swedish sounding rocket experiment, launched in July 2011, with the main goal of investigating the upper atmosphere in the altitude range 50-110 km. This paper describes the SondRad instrument in the PHOCUS payload, the radiometer comprising two frequency channels, 183 GHz and 557 GHz, aimed at exploring the water vapour concentration distribution in connection with the appearance of noctilucent (night shining) clouds. The design of the radiometer system has been done in a collaboration between Omnisys Instruments AB and the Group for Advanced Receiver Development (GARD) at Chalmers University of Technology where Omnisys was responsible for the overall design, implementation, and verification of the radiometers and backend whereas GARD was responsible for the radiometer optics and calibration systems. The SondRad instrument covers the water absorption lines at 183 GHz and 557 GHz. The 183 GHz channel is a side-looking radiometer while the 557 GHz radiometer is placed along the rocket axis looking in the forward direction. Both channels employ sub-harmonically pumped Schottky mixers and FFT spectrometer backends with 67 kHz resolution. The radiometers include novel calibration systems specifically adjusted for use with each frequency channel. The 183 GHz channel employs a CW-pilot signal calibrating the entire receiving chain while the IF-chain of the 557 GHz channel is calibrated by injecting a signal from a reference noise source through a directional coupler. The instrument collected complete spectra for both the 183 GHz and the 557 GHz with 300 Hz data rate for the 183 GHz channel and 10 Hz data rate for the 557 GHz channel for about 60 s reaching the apogee of the flight trajectory and 100 s after that. With lossless data compression using variable resolution over the spectrum, the data set was reduced to 2 × 12 MByte. The first results indicate that the instrument has

  18. Cavities

    MedlinePlus

    ... The tooth may hurt even without stimulation (spontaneous toothache). If irreversible damage to the pulp occurs and ... To detect cavities early, a dentist inquires about pain, examines the teeth, probes the teeth with dental instruments, and may take x-rays. People should ...

  19. Absolute radiometry and the solar constant

    NASA Technical Reports Server (NTRS)

    Willson, R. C.

    1974-01-01

    A series of active cavity radiometers (ACRs) are described which have been developed as standard detectors for the accurate measurement of irradiance in absolute units. It is noted that the ACR is an electrical substitution calorimeter, is designed for automatic remote operation in any environment, and can make irradiance measurements in the range from low-level IR fluxes up to 30 solar constants with small absolute uncertainty. The instrument operates in a differential mode by chopping the radiant flux to be measured at a slow rate, and irradiance is determined from two electrical power measurements together with the instrumental constant. Results are reported for measurements of the solar constant with two types of ACRs. The more accurate measurement yielded a value of 136.6 plus or minus 0.7 mW/sq cm (1.958 plus or minus 0.010 cal/sq cm per min).

  20. Development of UHF radiometer

    NASA Technical Reports Server (NTRS)

    Kendall, B. M.; Blume, H. J. C.; Cross, A. E.

    1985-01-01

    A wideband multifrequency UHF radiometer was initially developed to operate in the 500 to 710 MHz frequency range for the remote measurement of ocean water salinity. However, radio-frequency interference required a reconfiguration to operate in the single-frequency radio astronomy band of 608 to 614 MHz. Details of the radiometer development and testing are described. Flight testing over variable terrain provided a performance comparison of the UHF radiometer with an L-band radiometer for remote sensing of geophysical parameters. Although theoretically more sensitive, the UHF radiometer was found to be less desirable in practice than the L-band radiometer.

  1. Radiometer Calibration and Characterization

    1994-12-31

    The Radiometer Calibration and Characterization (RCC) software is a data acquisition and data archival system for performing Broadband Outdoor Radiometer Calibrations (BORCAL). RCC provides a unique method of calibrating solar radiometers using techniques that reduce measurement uncertainty and better characterize a radiometer’s response profile. The RCC software automatically monitors and controls many of the components that contribute to uncertainty in an instrument’s responsivity.

  2. Easy Absolute Values? Absolutely

    ERIC Educational Resources Information Center

    Taylor, Sharon E.; Mittag, Kathleen Cage

    2015-01-01

    The authors teach a problem-solving course for preservice middle-grades education majors that includes concepts dealing with absolute-value computations, equations, and inequalities. Many of these students like mathematics and plan to teach it, so they are adept at symbolic manipulations. Getting them to think differently about a concept that they…

  3. Optomechanics for absolute rotation detection

    NASA Astrophysics Data System (ADS)

    Davuluri, Sankar

    2016-07-01

    In this article, we present an application of optomechanical cavity for the absolute rotation detection. The optomechanical cavity is arranged in a Michelson interferometer in such a way that the classical centrifugal force due to rotation changes the length of the optomechanical cavity. The change in the cavity length induces a shift in the frequency of the cavity mode. The phase shift corresponding to the frequency shift in the cavity mode is measured at the interferometer output to estimate the angular velocity of absolute rotation. We derived an analytic expression to estimate the minimum detectable rotation rate in our scheme for a given optomechanical cavity. Temperature dependence of the rotation detection sensitivity is studied.

  4. Radiometer on a Chip

    NASA Technical Reports Server (NTRS)

    Chattopadhyay, Goutam; Gill, John J.; Mehdi, Imran; Lee, Choonsup; Schlecht, Erich T.; Skalare, Anders; Ward, John S.; Siegel, Peter H.; Thomas, Bertrand C.

    2009-01-01

    The radiometer on a chip (ROC) integrates whole wafers together to p rovide a robust, extremely powerful way of making submillimeter rece ivers that provide vertically integrated functionality. By integratin g at the wafer level, customizing the interconnects, and planarizing the transmission media, it is possible to create a lightweight asse mbly performing the function of several pieces in a more conventiona l radiometer.

  5. Six mechanisms used on the SSM/1 radiometer

    NASA Technical Reports Server (NTRS)

    Ludwig, H. R.

    1985-01-01

    Future USAF Block 5D Defense Meteorological Satellites will carry a scanning microwave radiometer sensor (SSM/1). SSM/1 senses the emission of microwave energy and returns to earth data used to determine weather conditions, such as rainfall rates, soil moisture, and oceanic wind speed. The overall design of the SSM/1 radiometer was largely influenced by the mechanisms. The radiometer was designed to be stowed in a cavity on the existing spacecraft. The deployment of the sensor is complex due to the constraint of this cavity and the need for precision in the deployment. The radiometer will continuously rotate, instead of oscillate, creating the need for a bearing and power transfer assembly and a momentum compensation device. The six mechanisms developed for this program are described.

  6. Calibration of electron cyclotron emission radiometer for KSTAR.

    PubMed

    Kogi, Y; Jeong, S H; Lee, K D; Akaki, K; Mase, A; Kuwahara, D; Yoshinaga, T; Nagayama, Y; Kwon, M; Kawahata, K

    2010-10-01

    We developed and installed an electron cyclotron emission radiometer for taking measurements of Korea Superconducting Tokamak Advanced Research (KSTAR) plasma. In order to precisely measure the absolute value of electron temperatures, a calibration measurement of the whole radiometer system was performed, which confirmed that the radiometer has an acceptably linear output signal for changes in input temperature. It was also found that the output power level predicted by a theoretical calculation agrees with that obtained by the calibration measurement. We also showed that the system displays acceptable noise-temperature performance around 0.23 eV.

  7. Aquarius L-Band Radiometers Calibration Using Cold Sky Observations

    NASA Technical Reports Server (NTRS)

    Dinnat, Emmanuel P.; Le Vine, David M.; Piepmeier, Jeffrey R.; Brown, Shannon T.; Hong, Liang

    2015-01-01

    An important element in the calibration plan for the Aquarius radiometers is to look at the cold sky. This involves rotating the satellite 180 degrees from its nominal Earth viewing configuration to point the main beams at the celestial sky. At L-band, the cold sky provides a stable, well-characterized scene to be used as a calibration reference. This paper describes the cold sky calibration for Aquarius and how it is used as part of the absolute calibration. Cold sky observations helped establish the radiometer bias, by correcting for an error in the spillover lobe of the antenna pattern, and monitor the long-term radiometer drift.

  8. Solar-Collector Radiometer

    NASA Technical Reports Server (NTRS)

    Kendall, J. M., Jr

    1984-01-01

    Water-cooled Kendall radiometer measures output of solar energy concentrators. Unit measures irradiance up to 30,000 solar constants with 1 percent accuracy and responds to wavelengths from ultraviolet to far infrared.

  9. The Boundary Layer Radiometer

    NASA Astrophysics Data System (ADS)

    Irshad, Ranah; Bowles, N. E.; Calcutt, S. B.; Hurley, J.

    2010-10-01

    The Boundary Layer Radiometer is a small, low mass (<1kg) radiometer with only a single moving part - a scan/calibration mirror. The instrument consists of a three mirror telescope system incorporating an intermediate focus for use with miniature infrared and visible filters. It also has an integrated low power blackbody calibration target to provide long-term calibration stability The instrument may be used as an upward looking boundary layer radiometer for both the terrestrial and Martian atmospheres with appropriate filters for the mid-infrared carbon dioxide band, as well as a visible channel for the detection of aerosol components such as dust. The scan mirror may be used to step through different positions from the local horizon to the zenith, allowing the vertical temperature profile of the atmosphere to be retrieved. The radiometer uses miniature infrared filter assemblies developed for previous space-based instruments by Oxford, Cardiff and Reading Universities. The intermediate focus allows for the use of upstream blocking filters and baffles, which not only simplifies the design of the filters and focal plane assembly, but also reduces the risk of problems due to stray light. Combined with the calibration target this means it has significant advantages over previous generations of small radiometers.

  10. Hurricane Imaging Radiometer

    NASA Technical Reports Server (NTRS)

    Cecil, Daniel J.; James, Mark W.; Roberts, J. Brent; Bisawas, Sayak K.; Jones, W. Linwood; Johnson, James; Farrar, Spencer; Sahawneh, Saleem; Ruf, Christopher S.; Morris, Mary; Black, Peter G.

    2014-01-01

    The Hurricane Imaging Radiometer (HIRAD) is a synthetic thinned array passive microwave radiometer designed to allow retrieval of surface wind speed in hurricanes, up through category five intensity. The retrieval technology follows the Stepped Frequency Microwave Radiometer (SFMR), which measures surface wind speed in hurricanes along a narrow strip beneath the aircraft. HIRAD has flown in the NASA Genesis and Rapid Intensification Processes (GRIP) experiement in 2010 on a WB-57 aircraft, and on a Global Hawk unmanned aircraft system (UAS) in 2012 and 2013 as part of NASA's Hurricane and Severe Storms Sentinel (HS3) program. The GRIP program included flights over Hurricanes Earl and Karl (2010). The 2012 HS3 deployment did not include any hurricane flights for the UAS carrying HIRAD. Hurricane flights are expected for HIRAD in 2013 during HS3. This presentation will describe the HIRAD instrument, its results from the 2010 hurricane flights, and hopefully results from hurricane flights in August and September 2013.

  11. The conical scan radiometer

    NASA Astrophysics Data System (ADS)

    Prosch, T.; Hennings, D.

    1982-07-01

    A satellite-borne conical scan radiometer (CSR) is proposed, offering multiangular and multispectral measurements of Earth radiation fields, including the total radiances, which are not available from conventional radiometers. Advantages of the CSR for meteorological studies are discussed. In comparison to conventional cross track scanning instruments, the CSR is unique with respect to the selected picture element size which is kept constant by means of a specially shaped detector matrix at all scan angles. The conical scan mode offers the chance to improve angular sampling. Angular sampling gaps of previous satellite-borne radiometers can be interpolated and complemented by CSR data. Radiances are measured through 10 radiometric channels which are selected to study cloudiness, water vapor, ozone, surface albedo, ground and mean stratospheric temperature, and aerosols.

  12. Aquarius Radiometer Status

    NASA Technical Reports Server (NTRS)

    Le Vine, D. M.; Piepmeier, J. R.; Dinnat, E. P.; de Matthaeis, P.; Utku, C.; Abraham, S.; Lagerloef, G.S.E.; Meissner, T.; Wentz, F.

    2014-01-01

    Aquarius was launched on June 10, 2011 as part of the Aquarius/SAC-D observatory and the instrument has been operating continuously since being turned on in August of the same year. The initial map of sea surface salinity was released one month later (September) and the quality of the retrieval has continuously improved since then. The Aquarius radiometers include several special features such as measurement of the third Stokes parameter, fast sampling, and careful thermal control, and a combined passive/active instrument. Aquarius is working well and in addition to helping measure salinity, the radiometer special features are generating new results.

  13. Absolute CH radical concentrations in rich low-pressure methane-oxygen-argon flames via cavity ringdown spectroscopy of the A transition

    SciTech Connect

    John W. Thomas, Jr; Andrew McIlroy

    1999-11-22

    We measure cavity ringdown spectra of the A{sup 2}{Delta}-X{sup 2}II transition of the methylidyne (CH) radical in a series of rich low-pressure methane-oxygen-argon flames and demonstrate that the technique is sensitive, quantitative, and straightforward in its implementation and interpretation. As a line-of-sight technique, it complements imaging techniques, such as planar laser-induced fluorescence. Our results generally agree with chemical kinetic models for methane oxidation that have appeared in the literature, but suggest some refinements are necessary. Additional examination of the CH + O{sub 2} reaction rate as a function of temperature is advised. Our results are consistent with those of Derzy et al. using the C{sup 2}{Sigma}{sup +}-X{sup 2}II transition for stoichiometric, low-pressure flames which include nitrogen. Our results for rich flames, as with earlier experiments for singlet methylene, suggest that flame chemical kinetic models need to be adjusted to account for flame chemistry for stoichiometries richer than {phi} = 1.5.

  14. Microwave Radiometer (MWR) Handbook

    SciTech Connect

    Morris, VR

    2006-08-01

    The Microwave Radiometer (MWR) provides time-series measurements of column-integrated amounts of water vapor and liquid water. The instrument itself is essentially a sensitive microwave receiver. That is, it is tuned to measure the microwave emissions of the vapor and liquid water molecules in the atmosphere at specific frequencies.

  15. Stable radiometal antibody immunoconjugates

    DOEpatents

    Mease, Ronnie C.; Srivastava, Suresh C.; Gestin, Jean-Francois

    1994-01-01

    The present invention relates to new rigid chelating structures, to methods for preparing these materials, and to their use in preparing radiometal labeled immunoconjugates. These new chelates include cyclohexyl EDTA monohydride, the trans forms of cyclohexyl DTPA and TTHA, and derivatives of these cyclohexyl polyaminocarboxylate materials.

  16. Stable radiometal antibody immunoconjugates

    DOEpatents

    Mease, R.C.; Srivastava, S.C.; Gestin, J.F.

    1994-08-02

    The present invention relates to new rigid chelating structures, to methods for preparing these materials, and to their use in preparing radiometal labeled immunoconjugates. These new chelates include cyclohexyl EDTA monohydride, the trans forms of cyclohexyl DTPA and TTHA, and derivatives of these cyclohexyl polyaminocarboxylate materials. No Drawings

  17. Ten Thousand Solar Constants Radiometer

    NASA Technical Reports Server (NTRS)

    Kendall, J. M., Sr.

    1985-01-01

    "Radiometer for Accurate (+ or - 1%) Measurement of Solar Irradiances Equal to 10,000 Solar Constants," gives additional information on radiometer described elsewhere. Self-calibrating, water-cooled, thermopile radiometer measures irradiance produced in solar image formed by parabolic reflector or by multiple-mirror solar installation.

  18. Design, calibration, and characterization of a field radiometer using light-emitting diodes as detectors.

    PubMed

    Czapla-Myers, Jeffrey S; Thome, Kurtis J; Biggar, Stuart F

    2008-12-20

    The Remote Sensing Group at the University of Arizona has developed multispectral ground-viewing radiometers that use light-emitting diodes as detectors. This work describes the optical design, electrical design, and laboratory calibration of a three-channel radiometer that operates in the visible and near-infrared region of the spectrum. The optical and electrical design of the radiometer is introduced, and then the calibration and characterization of the radiometer are described. Laboratory measurements include the spectral responsivity for each channel of the radiometer, the temperature dependence of the total responsivity for each channel, system linearity, field of view, and finally, the absolute radiometric calibration. A solar-radiation-based calibration is used to determine the absolute responsivity.

  19. Loss-compensated radiometer

    SciTech Connect

    Lobo, P.C.

    1984-05-01

    A new radiometer concept is described and evaluated. Automatic dynamic electrical compensation is achieved by a high-gain feedback amplifier and low thermal inertia solar and compensating electrical sensors. With sufficiently high gain, compensation can increase accuracy to limits determined by amplifier drift. Equations governing instrument response are derived and analyzed. Initial measurements on a preliminary prototype confirm the validity of the concept which should yield a very accurate instrument with ''self calibrating'' features.

  20. Hurricane Imaging Radiometer

    NASA Technical Reports Server (NTRS)

    Cecil, Daniel J.; Biswas, Sayak K.; James, Mark W.; Roberts, J. Brent; Jones, W. Linwood; Johnson, James; Farrar, Spencer; Sahawneh, Saleem; Ruf, Christopher S.; Morris, Mary; Black, Peter G.

    2014-01-01

    The Hurricane Imaging Radiometer (HIRAD) is a synthetic thinned array passive microwave radiometer designed to allow retrieval of surface wind speed in hurricanes, up through category five intensity. The retrieval technology follows the Stepped Frequency Microwave Radiometer (SFMR), which measures surface wind speed in hurricanes along a narrow strip beneath the aircraft. HIRAD maps wind speeds in a swath below the aircraft, about 50-60 km wide when flown in the lower stratosphere. HIRAD has flown in the NASA Genesis and Rapid Intensification Processes (GRIP) experiment in 2010 on a WB-57 aircraft, and on a Global Hawk unmanned aircraft system (UAS) in 2012 and 2013 as part of NASA's Hurricane and Severe Storms Sentinel (HS3) program. The GRIP program included flights over Hurricanes Earl and Karl (2010). The 2012 HS3 deployment did not include any hurricane flights for the UAS carrying HIRAD. The 2013 HS3 flights included one flight over the predecessor to TS Gabrielle, and one flight over Hurricane Ingrid. This presentation will describe the HIRAD instrument, its results from the 2010 and 2013 flights, and potential future developments.

  1. High resolution spectroscopy of silane with an external-cavity quantum cascade laser: Absolute line strengths of the ν3 fundamental band at 4.6 μm

    NASA Astrophysics Data System (ADS)

    van Helden, J. H.; Lopatik, D.; Nave, A.; Lang, N.; Davies, P. B.; Röpcke, J.

    2015-01-01

    The introduction of room temperature continuous wave external-cavity quantum cascade lasers (EC-QCLs) with narrow linewidths has greatly facilitated high resolution spectroscopy over wide spectral ranges in the mid-infrared (MIR) region. Using the wide tuning range of an EC-QCL we have measured the absolute line strengths of many P-branch transitions of the stretching dyad of the ν3 fundamental band of 28SiH4 between 2096 and 2178 cm-1. Furthermore, the high spectral resolution available has enabled us to resolve and measure representative examples of the tetrahedral splittings associated with each component of the P-branch. The positions of these components are in excellent agreement with spherical top data system (STDS) predictions and theoretical transitions from the TDS spectroscopic database for spherical top molecules. These are the first measurements of these line strengths of 28SiH4 and are an example of the applicability of high-powered, widely tunable EC-QCLs to high resolution spectroscopy.

  2. Absolute calibration of remote sensing instruments

    NASA Astrophysics Data System (ADS)

    Biggar, S. F.; Bruegge, C. J.; Capron, B. A.; Castle, K. R.; Dinguirard, M. C.; Holm, R. G.; Lingg, L. J.; Mao, Y.; Palmer, J. M.; Phillips, A. L.

    1985-12-01

    Source-based and detector-based methods for the absolute radiometric calibration of a broadband field radiometer are described. Using such a radiometer, calibrated by both methods, the calibration of the integrating sphere used in the preflight calibration of the Thematic Mapper was redetermined. The results are presented. The in-flight calibration of space remote sensing instruments is discussed. A method which uses the results of ground-based reflectance and atmospheric measurements as input to a radiative transfer code to predict the radiance at the instrument is described. A calibrated, helicopter-mounted radiometer is used to determine the radiance levels at intermediate altitudes to check the code predictions. Results of such measurements for the calibration of the Thematic Mapper on Landsat 5 and an analysis that shows the value of such measurements are described.

  3. Absolute Summ

    NASA Astrophysics Data System (ADS)

    Phillips, Alfred, Jr.

    Summ means the entirety of the multiverse. It seems clear, from the inflation theories of A. Guth and others, that the creation of many universes is plausible. We argue that Absolute cosmological ideas, not unlike those of I. Newton, may be consistent with dynamic multiverse creations. As suggested in W. Heisenberg's uncertainty principle, and with the Anthropic Principle defended by S. Hawking, et al., human consciousness, buttressed by findings of neuroscience, may have to be considered in our models. Predictability, as A. Einstein realized with Invariants and General Relativity, may be required for new ideas to be part of physics. We present here a two postulate model geared to an Absolute Summ. The seedbed of this work is part of Akhnaton's philosophy (see S. Freud, Moses and Monotheism). Most important, however, is that the structure of human consciousness, manifest in Kenya's Rift Valley 200,000 years ago as Homo sapiens, who were the culmination of the six million year co-creation process of Hominins and Nature in Africa, allows us to do the physics that we do. .

  4. Wideband Agile Digital Microwave Radiometer

    NASA Technical Reports Server (NTRS)

    Gaier, Todd C.; Brown, Shannon T.; Ruf, Christopher; Gross, Steven

    2012-01-01

    The objectives of this work were to take the initial steps needed to develop a field programmable gate array (FPGA)- based wideband digital radiometer backend (>500 MHz bandwidth) that will enable passive microwave observations with minimal performance degradation in a radiofrequency-interference (RFI)-rich environment. As manmade RF emissions increase over time and fill more of the microwave spectrum, microwave radiometer science applications will be increasingly impacted in a negative way, and the current generation of spaceborne microwave radiometers that use broadband analog back ends will become severely compromised or unusable over an increasing fraction of time on orbit. There is a need to develop a digital radiometer back end that, for each observation period, uses digital signal processing (DSP) algorithms to identify the maximum amount of RFI-free spectrum across the radiometer band to preserve bandwidth to minimize radiometer noise (which is inversely related to the bandwidth). Ultimately, the objective is to incorporate all processing necessary in the back end to take contaminated input spectra and produce a single output value free of manmade signals to minimize data rates for spaceborne radiometer missions. But, to meet these objectives, several intermediate processing algorithms had to be developed, and their performance characterized relative to typical brightness temperature accuracy re quirements for current and future microwave radiometer missions, including those for measuring salinity, soil moisture, and snow pack.

  5. Analytical and Experimental Characterization of a Linear-Array Thermopile Scanning Radiometer for Geo-Synchronous Earth Radiation Budget Applications

    NASA Technical Reports Server (NTRS)

    Sorensen, Ira J.

    1998-01-01

    The Thermal Radiation Group, a laboratory in the department of Mechanical Engineering at Virginia Polytechnic Institute and State University, is currently working towards the development of a new technology for cavity-based radiometers. The radiometer consists of a 256-element linear-array thermopile detector mounted on the wall of a mirrored wedgeshaped cavity. The objective of this research is to provide analytical and experimental characterization of the proposed radiometer. A dynamic end-to-end opto-electrothermal model is developed to simulate the performance of the radiometer. Experimental results for prototype thermopile detectors are included. Also presented is the concept of the discrete Green's function to characterize the optical scattering of radiant energy in the cavity, along with a data-processing algorithm to correct for the scattering. Finally, a parametric study of the sensitivity of the discrete Green's function to uncertainties in the surface properties of the cavity is presented.

  6. Radiant Temperature Nulling Radiometer

    NASA Technical Reports Server (NTRS)

    Ryan, Robert (Inventor)

    2003-01-01

    A self-calibrating nulling radiometer for non-contact temperature measurement of an object, such as a body of water, employs a black body source as a temperature reference, an optomechanical mechanism, e.g., a chopper, to switch back and forth between measuring the temperature of the black body source and that of a test source, and an infrared detection technique. The radiometer functions by measuring radiance of both the test and the reference black body sources; adjusting the temperature of the reference black body so that its radiance is equivalent to the test source; and, measuring the temperature of the reference black body at this point using a precision contact-type temperature sensor, to determine the radiative temperature of the test source. The radiation from both sources is detected by an infrared detector that converts the detected radiation to an electrical signal that is fed with a chopper reference signal to an error signal generator, such as a synchronous detector, that creates a precision rectified signal that is approximately proportional to the difference between the temperature of the reference black body and that of the test infrared source. This error signal is then used in a feedback loop to adjust the reference black body temperature until it equals that of the test source, at which point the error signal is nulled to zero. The chopper mechanism operates at one or more Hertz allowing minimization of l/f noise. It also provides pure chopping between the black body and the test source and allows continuous measurements.

  7. In-flight absolute radiometric calibration of the thematic mapper

    NASA Technical Reports Server (NTRS)

    Castle, K. R.; Holm, R. G.; Kastner, C. J.; Palmer, J. M.; Slater, P. N.; Dinguirard, M.; Ezra, C. E.; Jackson, R. D.; Savage, R. K.

    1983-01-01

    The TM multispectral scanner system was calibrated in an absolute manner before launch. To determine the temporal changes of the absolute radiometric calibration of the entire system, spectroradiometric measurements of the ground and the atmosphere were made simultaneously with TM collections over White Sands, New Mexico. By entering the measured values in an atmospheric radiative transfer program, the radiance levels of the in four of the spectral bands of the TM were determined. Tables show values for the reflectance of snow at White Sands measured by a modular 8 channel radiometer, and values for exoatmospheric irradiance within the TM passbands, calculated for the Earth-Sun distance using a solar radiometer.

  8. Radiometers Optimize Local Weather Prediction

    NASA Technical Reports Server (NTRS)

    2010-01-01

    Radiometrics Corporation, headquartered in Boulder, Colorado, engaged in Small Business Innovation Research (SBIR) agreements with Glenn Research Center that resulted in a pencil-beam radiometer designed to detect supercooled liquid along flight paths -- a prime indicator of dangerous icing conditions. The company has brought to market a modular radiometer that resulted from the SBIR work. Radiometrics' radiometers are used around the world as key tools for detecting icing conditions near airports and for the prediction of weather conditions like fog and convective storms, which are known to produce hail, strong winds, flash floods, and tornadoes. They are also employed for oceanographic research and soil moisture studies.

  9. Characterization and calibration of 8-channel E-band heterodyne radiometer system for SST-1 tokamak

    SciTech Connect

    Siju, Varsha; Kumar, Dharmendra; Shukla, Praveena; Pathak, S. K.

    2014-05-15

    An 8-channel E-band heterodyne radiometer system (74–86 GHz) is designed, characterized, and calibrated to measure the radial electron temperature profile by measuring Electron Cyclotron Emission spectrum at SST-1 Tokamak. The developed radiometer has a noise equivalent temperature of 1 eV and sensitivity of 5 × 10{sup 9} V/W. In order to precisely measure the absolute value of electron temperature, a calibration measurement of the radiometer system is performed using hot-cold Dicke switch method, which confirms the system linearity.

  10. COBE differential microwave radiometers - Calibration techniques

    NASA Technical Reports Server (NTRS)

    Bennett, C. L.; Smoot, G. F.; Janssen, M.; Gulkis, S.; Kogut, A.; Hinshaw, G.; Backus, C.; Hauser, M. G.; Mather, J. C.; Rokke, L.

    1992-01-01

    The COBE spacecraft was launched November 18, 1989 UT carrying three scientific instruments into earth orbit for studies of cosmology. One of these instruments, the Differential Microwave Radiometer (DMR), is designed to measure the large-angular-scale temperature anisotropy of the cosmic microwave background radiation at three frequencies (31.5, 53, and 90 GHz). This paper presents three methods used to calibrate the DMR. First, the signal difference between beam-filling hot and cold targets observed on the ground provides a primary calibration that is transferred to space by noise sources internal to the instrument. Second, the moon is used in flight as an external calibration source. Third, the signal arising from the Doppler effect due to the earth's motion around the barycenter of the solar system is used as an external calibration source. Preliminary analysis of the external source calibration techniques confirms the accuracy of the currently more precise ground-based calibration. Assuming the noise source behavior did not change from the ground-based calibration to flight, a 0.1-0.4 percent relative and 0.7-2.5 percent absolute calibration uncertainty is derived, depending on radiometer channel.

  11. HELIOS dual swept frequency radiometer

    NASA Technical Reports Server (NTRS)

    White, J. R.

    1975-01-01

    The HELIOS dual swept frequency radiometer, used in conjunction with a dipole antenna, was designed to measure electromagnetic radiation in space. An engineering prototype was fabricated and tested on the HELIOS spacecraft. Two prototypes and two flight units were fabricated and three of the four units were integrated into the HELIOS spacecraft. Two sets of ground support equipment were provided for checkout of the radiometer.

  12. GPM Plans for Radiometer Intercalibration

    NASA Technical Reports Server (NTRS)

    Stocker, Erich Franz; Stout, John; Chou, Joyce

    2011-01-01

    The international Global Precipitation Measurement (GPM) mission led by NASA and JAXA is planned as a multi-radiometer constellation mission. A key mission component is the ability to intercalibrate the Tb from the partner constellation radiometers and create inter-calibrated, mission consistent Tc. One of the enabling strategies for this approach is the launching of a joint NASA/JAXA core satellite which contains a JAXA/NICT provided dual precipitation radar and a NASA provided Microwave Imaging passive radiometer. The observations from these instruments on the core satellite provide the opportunity to develop a transfer reference standard that can then be applied across the partner provided constellation radiometers that enables the creation of mission consistent brightness temperatures. The other aspect of the strategy is the development of a community consensus intercalibration algorithm that will be applied to the Tb observations from partner radiometers and create the best calibrated Tc. Also described is the development of the framework in which the inter-calibration is included in the final algorithm. A part of the latter effort has been the development of a generic, logical structure which can be applied across radiometer types and which guarantees the user community that key information for using Tc properly is recorded. Key

  13. Informal Preliminary Report on Comparisons of Prototype SPN-1 Radiometer to PARSL Measurements

    SciTech Connect

    Long, Charles N.

    2014-06-17

    The prototype SPN-1 has been taking measurements for several months collocated with our PNNL Atmospheric Remote Sensing Laboratory (PARSL) solar tracker mounted instruments at the Pacific Northwest National Laboratory (PNNL) located in Richland, Washington, USA. The PARSL radiometers used in the following comparisons consist of an Eppley Normal Incident Pyrheliometer (NIP) and a shaded Eppley model 8-48 “Black and White” pyrgeometer (B&W) to measure the direct and diffuse shortwave irradiance (SW), respectively. These instruments were calibrated in mid-September by comparison to an absolute cavity radiometer directly traceable to the world standard group in Davos, Switzerland. The NIP calibration was determined by direct comparison, while the B&W was calibrated using the shade/unshade technique. All PARSL data prior to mid-September have been reprocessed using the new calibration factors. The PARSL data are logged as 1-minute averages from 1-second samples. Data used in this report span the time period from June 22 through December 1, 2006. All data have been processed through the QCRad code (Long and Shi, 2006), which itself is a more elaborately developed methodology along the lines of that applied by the Baseline Surface Radiation Network (BSRN) Archive (Long and Dutton, 2004), for quality control. The SPN-1 data are the standard total and diffuse SW values obtained from the analog data port of the instrument. The comparisons use only times when both the PARSL and SPN-1 data passed all QC testing. The data were further processed and analyzed by application of the SW Flux Analysis methodology (Long and Ackerman, 2000; Long and Gaustad, 2004, Long et al., 2006) to detect periods of clear skies, calculate continuous estimates of clear-sky SW irradiance and the effect of clouds on the downwelling SW, and estimate fractional sky cover.

  14. Radiometer for accurate (+ or - 1%) measurement of solar irradiance equal to 10,000 solar constants

    NASA Technical Reports Server (NTRS)

    Kendall, J. M., Sr.

    1981-01-01

    The 10,000 solar constant radiometer was developed for the accurate (+ or - 1%) measurement of the irradiance produced in the image formed by a parabolic reflector or by a multiple mirror solar installation. This radiometer is water cooled, weighs about 1 kg, and is 5 cm (2 in.) in diameter by 10 cm (4 in.) long. A sting is provided for mounting the radiometer in the solar installation capable of measuring irradiances as high as 20,000 solar constants, the instrument is self calibrating. Its accuracy depends on the accurate determination of the cavity aperture, and absorptivity of the cavity, and accurate electrical measurements. The spectral response is flat over the entire spectrum from far UV to far IR. The radiometer responds to a measurement within 99.7% of the final value within 8 s. During a measurement of the 10,000 solar constant irradiance, the temperature rise of the water is about 20 C. The radiometer has perfect cosine response up to 60 deg off the radiometer axis.

  15. Radiometer Testbed Development for SWOT

    NASA Technical Reports Server (NTRS)

    Kangaslahti, Pekka; Brown, Shannon; Gaier, Todd; Dawson, Douglas; Harding, Dennis; Fu, Lee-Lueng; Esteban-Fernandez, Daniel

    2010-01-01

    Conventional altimeters include nadir looking colocated 18-37 GHz microwave radiometer to measure wet tropospheric path delay. These have reduced accuracy in coastal zone (within 50 km from land) and do not provide wet path delay over land. The addition of high frequency channels to Jason-class radiometer will improve retrievals in coastal regions and enable retrievals over land. High-frequency window channels, 90, 130 and 166 GHz are optimum for improving performance in coastal region and channels on 183 GHz water vapor line are ideal for over-land retrievals.

  16. Compact Radiometers Expand Climate Knowledge

    NASA Technical Reports Server (NTRS)

    2010-01-01

    To gain a better understanding of Earth's water, energy, and carbon cycles, NASA plans to embark on the Soil Moisture Active and Passive mission in 2015. To prepare, Goddard Space Flight Center provided Small Business Innovation Research (SBIR) funding to ProSensing Inc., of Amherst, Massachusetts, to develop a compact ultrastable radiometer for sea surface salinity and soil moisture mapping. ProSensing incorporated small, low-cost, high-performance elements into just a few circuit boards and now offers two lightweight radiometers commercially. Government research agencies, university research groups, and large corporations around the world are using the devices for mapping soil moisture, ocean salinity, and wind speed.

  17. TOPEX microwave radiometer system calibration - Refining the SMMR heritage

    NASA Astrophysics Data System (ADS)

    Ruf, Christopher S.; Janssen, Michael A.; Keihm, Stephen J.

    A modified version of the Scanning multichannel Microwave Radiometer (SMMR) will be used for wet tropospheric path-delay corrections to the TOPEX/POSEIDON radar altimeter measurements. A number of the sources of calibration problems encountered by SMMR onboard the Seasat and Nimbus-7 platforms have been identified, and appropriate corrections have been attempted. Calibration hardware corrections include a more representative modeling of the microwave losses and reflections, and a reduction in the thermal gradients expected across this hardware through the use of radomes and sun shades and the choice of pertinent orbit parameters. Antenna calibration corrections include a postlaunch fine tuning of the antenna pattern correction algorithm to accommodate small errors in the prelaunch antenna pattern measurements. This is accomplished by overpasses of ground-based, upward-looking water vapor radiometers. An absolute calibration accuracy of 1.0 K or less is anticipated.

  18. Calibration of IR test chambers with the missile defense transfer radiometer

    NASA Astrophysics Data System (ADS)

    Kaplan, Simon G.; Woods, Solomon I.; Carter, Adriaan C.; Jung, Timothy M.

    2013-05-01

    The Missile Defense Transfer Radiometer (MDXR) is designed to calibrate infrared collimated and flood sources over the fW/cm2 to W/cm2 power range from 3 μm to 28μ m in wavelength. The MDXR operates in three different modes: as a filter radiometer, a Fourier-transform spectrometer (FTS)-based spectroradiometer, and as an absolute cryogenic radiometer (ACR). Since 2010, the MDXR has made measurements of the collimated infrared irradiance at the output port of seven different infrared test chambers at several facilities. We present a selection of results from these calibration efforts compared to signal predictions from the respective chamber models for the three different MDXR calibration modes. We also compare the results to previous measurements made of the same chambers with a legacy transfer radiometer, the NIST BXR. In general, the results are found to agree within their combined uncertainties, with the MDXR having 30 % lower uncertainty and greater spectral coverage.

  19. Absolute Temperature Monitoring Using RF Radiometry in the MRI Scanner.

    PubMed

    El-Sharkawy, Abdel-Monem M; Sotiriadis, Paul P; Bottomley, Paul A; Atalar, Ergin

    2006-11-01

    Temperature detection using microwave radiometry has proven value for noninvasively measuring the absolute temperature of tissues inside the body. However, current clinical radiometers operate in the gigahertz range, which limits their depth of penetration. We have designed and built a noninvasive radiometer which operates at radio frequencies (64 MHz) with ∼100-kHz bandwidth, using an external RF loop coil as a thermal detector. The core of the radiometer is an accurate impedance measurement and automatic matching circuit of 0.05 Ω accuracy to compensate for any load variations. The radiometer permits temperature measurements with accuracy of ±0.1°K, over a tested physiological range of 28° C-40° C in saline phantoms whose electric properties match those of tissue. Because 1.5 T magnetic resonance imaging (MRI) scanners also operate at 64 MHz, we demonstrate the feasibility of integrating our radiometer with an MRI scanner to monitor RF power deposition and temperature dosimetry, obtaining coarse, spatially resolved, absolute thermal maps in the physiological range. We conclude that RF radiometry offers promise as a direct, noninvasive method of monitoring tissue heating during MRI studies and thereby providing an independent means of verifying patient-safe operation. Other potential applications include titration of hyper- and hypo-therapies. PMID:18026562

  20. Foil radiometer accessory improves measurements

    NASA Technical Reports Server (NTRS)

    Schumacher, P. E.

    1967-01-01

    The responsiveness of a foil radiometer is increased and its time constant is simultaneously decreased by isolating the foil in a controlled environment. Using an optical system, it is coupled to the media to be measured, and the resulting concentration of energy permits the thermocouple junction temperature to respond quickly.

  1. Advanced very high resolution radiometer

    NASA Technical Reports Server (NTRS)

    1976-01-01

    The advanced very high resolution radiometer development program is considered. The program covered the design, construction, and test of a breadboard model, engineering model, protoflight model, mechanical structural model, and a life test model. Special bench test and calibration equipment was also developed for use on the program.

  2. Teaching Absolute Value Meaningfully

    ERIC Educational Resources Information Center

    Wade, Angela

    2012-01-01

    What is the meaning of absolute value? And why do teachers teach students how to solve absolute value equations? Absolute value is a concept introduced in first-year algebra and then reinforced in later courses. Various authors have suggested instructional methods for teaching absolute value to high school students (Wei 2005; Stallings-Roberts…

  3. Lens transmission measurement for an absolute radiation thermometer

    SciTech Connect

    Hao, X.; Yuan, Z.; Lu, X.

    2013-09-11

    The lens transmission for the National Institute of Metrology of China absolute radiation thermometer is measured by a hybrid method. The results of the lens transmission measurements are 99.002% and 86.792% for filter radiometers with center wavelengths 633 nm and 900 nm, respectively. These results, after correcting for diffraction factors and the size-of-source effect when the lens is incorporated within the radiometer, can be used for measurement of thermodynamic temperature. The expanded uncertainty of the lens transmission measurement system has been evaluated. It is 1.3×10{sup −3} at 633 nm and 900 nm, respectively.

  4. Space shuttle cavity assessment test program

    NASA Technical Reports Server (NTRS)

    Scheps, P. B.

    1976-01-01

    In order to obtain basic radiation properties of the radiator/payload bay door cavity, three tests were conducted on a full-size structural simulator of the cavity. There were three tests conducted: (1) CATA used for determination of exchange factors, absorbed solar flux, and door covering influences, (2) quartz lamp array calibrated to provide IR flux distribution on CATA, and (3) retest with radiometer array for background flux measurement.

  5. Imaging radiometers employing linear thermoelectric arrays

    NASA Astrophysics Data System (ADS)

    McManus, Timothy J.; Mickelson, Steve

    1999-07-01

    Infrared Solutions, Inc. has developed a family of radiometers which employ silicon microstructure uncooled linear thermoelectric arrays, prepared by Honeywell Technology Center. Included in the family is a handheld imaging radiometer for predictive and preventive maintenance having a frame time of 1.4 sec, a linescanner radiometer for monitoring of industrial web process, an imaging radiometer for monitoring stationary industrial processes such as a die casting, and a linescanner radiometer for monitoring the temperature distribution of railcar wheels on trains moving at speeds up to 80 mph.

  6. Digital simulation of dynamic processes in radiometer systems. [microwave radiometers

    NASA Technical Reports Server (NTRS)

    Stanley, W. D.

    1980-01-01

    The development and application of several computer programs for simulating different classes of microwave radiometers are described. The programs are dynamic in nature, and they may be used to determine the instantaneous behavior of system variables as a function of time. Some of the programs employ random variable models in the simulations so that the statistical nature of the results may be investigated. The programs have been developed to utilize either the Continuous System Modeling Program or the Advanced Continuous System Language. The validity of most of the programs was investigated using statistical tests, and the results show excellent correlation with theoretical predictions. The programs are currently being used in the investigation of new design techniques for microwave radiometers.

  7. A Hand Held Ratioing Radiometer for remote radiance measurements

    NASA Technical Reports Server (NTRS)

    Daubner, L.; Davies, J.; Cumming, C.; Goetz, A.

    1982-01-01

    The small, lightweight Hand Held Ratioing Radiometer (HHRR) measures the ratio of spectral reflectance in any of 25 pairs of narrow bands in the 400 to 2500 nanometer spectral region. Two parallel optical trains view the scene through separate filters mounted in two filter wheels each containing five filters. Absolute reflectance of the scene can also be measured. HHRR is particularly useful for ground truth studies for the interpretation of imagery from Landsat, the thematic mappers and the forthcoming SPOT satellite. Its small size and simplicity of operation make it useful to geologists, botanists, oceanographers and many other geotechnologists.

  8. BESST: A Miniature, Modular Radiometer

    NASA Technical Reports Server (NTRS)

    Warden, Robert; Good, William; Baldwin-Stevens, Erik

    2010-01-01

    A new radiometer assembly has been developed that incorporates modular design principles in order to provide flexibility and versatility. The assembly, shown in Figure 1, is made up of six modules plus a central cubical frame. A small thermal imaging detector is used to determine the temperature of remote objects. To improve the accuracy of the temperature reading, frequent calibration is required. The detector must view known temperature targets before viewing the remote object. Calibration is achieved by using a motorized fold mirror to select the desired scene the detector views. The motor steps the fold mirror through several positions, which allows the detector to view the calibration targets or the remote object. The details, features, and benefits of the radiometer are described in this paper.

  9. Cloud Top Scanning radiometer (CTS)

    NASA Technical Reports Server (NTRS)

    1978-01-01

    A scanning radiometer to be used for measuring cloud radiances in each of three spectral regions is described. Significant features incorporated in the Cloud Top Scanner design are: (1) flexibility and growth potential through use of easily replaceable modular detectors and filters; (2) full aperture, multilevel inflight calibration; (3) inherent channel registration through employment of a single shared field stop; and (4) radiometric sensitivity margin in a compact optical design through use of Honeywell developed (Hg,Cd)Te detectors and preamplifiers.

  10. Calibration Methodology for the Lightweight Rainfall Radiometer STAR Aircraft Sensor

    NASA Technical Reports Server (NTRS)

    Principe, Caleb; Ruf, Christopher; Krebs, Carolyn A. (Technical Monitor)

    2002-01-01

    A proposed methodology for the in-flight calibration of a Synthetic Thinned Aperture Radiometer (STAR) airborne sensor with the potential application to a space flight version. The application of the spaceflight version of this instrument will address several pressing issues related to the Global Precipitation Measurement Mission (GPM). The X-Band Lightweight Rainfall Radiometer using STAR technology (LRR-X) is an aircraft sensor that is jointly developed by the NASA Goddard Space Flight Center and the University of Michigan. This paper will describe the theory of calibration as well as the hardware design specifications used by the method. The on-board hardware uses individual uncorrelated warm loads on each receiver as well as to a single noise diode providing a correlated noise source to each receiver. A procedure for maintaining onboard calibration with an optimum running average using correlated bursts of thermal noise interleaved with scene data will be exercised during the maiden flight of the LRR-X instrument during the spring of 2003. The final component of calibration of a synthetic aperture radiometer is the image reconstruction algorithm that uses the measured correlations to produce the temperature brightness (TB) images. An overview of system-level testing, both on the ground and in-flight, will be presented to validate the absolute accuracy of the image reconstruction algorithm.

  11. Absolute radiometric calibration of advanced remote sensing systems

    NASA Technical Reports Server (NTRS)

    Slater, P. N.

    1982-01-01

    The distinction between the uses of relative and absolute spectroradiometric calibration of remote sensing systems is discussed. The advantages of detector-based absolute calibration are described, and the categories of relative and absolute system calibrations are listed. The limitations and problems associated with three common methods used for the absolute calibration of remote sensing systems are addressed. Two methods are proposed for the in-flight absolute calibration of advanced multispectral linear array systems. One makes use of a sun-illuminated panel in front of the sensor, the radiance of which is monitored by a spectrally flat pyroelectric radiometer. The other uses a large, uniform, high-radiance reference ground surface. The ground and atmospheric measurements required as input to a radiative transfer program to predict the radiance level at the entrance pupil of the orbital sensor are discussed, and the ground instrumentation is described.

  12. Eosinophil count - absolute

    MedlinePlus

    Eosinophils; Absolute eosinophil count ... the white blood cell count to give the absolute eosinophil count. ... than 500 cells per microliter (cells/mcL). Normal value ranges may vary slightly among different laboratories. Talk ...

  13. A 16-channel heterodyne electron cyclotron emission radiometer on J-TEXT

    SciTech Connect

    Yang, Z. J.; Zhuang, G.; Xiao, J. S.; Wang, Z. J.; Phillips, P. E.; Huang, H.; Rowan, W. L.

    2012-10-15

    To study equilibrium temporal dynamics and the mechanisms of magnetohydrodynamic instabilities, a 16-channel heterodyne electron cyclotron emission (ECE) radiometer has been developed to view the J-TEXT tokamak from the low field side. The ECE radiometer detects second-harmonic extraordinary mode in the frequency band of 94-125 GHz which corresponds to resonances from 1.8 T to 2.2 T. This ECE system consists of an ECE transmission line, a radio frequency unit, and two 8-channel intermediate frequency units. An in situ blackbody calibration source is applied for system calibration by comparison of hot and cold sources in order to provide an absolute temperature measurement.

  14. GPM Intercalibrated Radiometer Brightness Temperatures

    NASA Astrophysics Data System (ADS)

    Stocker, Erich Franz; Chou, Joyce

    2013-04-01

    One of the keys to consistent precipitation retrieval from passive microwave radiometer measurements (whether imagers or sounders) is accurate, long-term consistent brightness temperature retrievals. This becomes doubly important when there measurements are taken from radiometers on multiple platforms, from multiple agencies, with many different purposes. The Global Precipitation Measurement (GPM) mission addresses this issue directly with the production of intercalibrated brightness temperatures from all the partner satellites contributing to the GPM mission. These intercalibrated brightness temperatures are given the product designation: 1C within GPM. This paper will describe the GPM approach to intercalibration 1C products. The intercalibration and creation of the products uses a 5-step methodology: comparison of the partner standard products (either Tb or Ta) with the GPM reference standard; determination of adjustments that should be made to each product to create consistent brightness temperatures; re-orbitization of all orbits (in non-realtime) to be in the standard GPM south-south orbit; application of the adjustments to the partner provide 1B(or 1A) products; production of 1C products in HDF5 using a "standard" logical format for any radiometer regardless of its 1B format. This paper describes each of these steps and provides the background for them. It discusses in some detail the current 1C logical format and why this format facilitates use by downstream product algorithms and end-users. Most importantly it provides the analysis approach established by the GPM inter-calibration working group in establishing the adjustments to be made at the 1C level. Finally, using DMSP F16-18, it provides examples of the 1C products and discusses the adjustments that are made.

  15. Millimeter-Wave Radiometer Imager

    NASA Technical Reports Server (NTRS)

    Wilson, W. J.; Howard, R. J.; Ibbott, A. C.; Parks, G. S.; Ricketts, W. B.

    1988-01-01

    A 3-mm radiometer system with mechanically scanned antenna built for use on small aircraft or helicopter to produce near-real-time moderate-resolution images of ground. Main advantage of passive imaging sensor able to provide information through clouds, smoke, and dust when visual and infrared (IR) systems unusable. Used also for variety of remote-sensing applications such as measurements of surface moisture, snow cover, vegetation type and extent, mineral type and extent, surface temperature, and thermal inertia. Possible to map fires and volcanic lava flows through obscuring clouds and smoke.

  16. Irradiance Calibration Using a Cryogenic Radiometer and a Broadband Light Source

    NASA Astrophysics Data System (ADS)

    Morrill, J. S.; McMullin, D.; Floyd, L. E.; Lorentz, S. R.; Korendyke, C. M.

    2009-12-01

    Total solar irradiance measurements have been made from space based instruments for the past several decades. Due to a variety of reasons which range from instrumental degradation to differences in optical design, the data from these sources have proved difficult to overlap and place on an absolute scale. Some previous calibration efforts have used the sun as a source while operating the instrument in a large vacuum chamber. More recent efforts to provide ground based, pre-flight intercomparisons between flight radiometers and recently developed high power cryogenic radiometers using lasers. We are currently developing a calibration facility at The Naval Research Laboratory which uses a high power cryogenic radiometer with a broadband light source with near solar illumination. The system uses a very low scattered light vacuum calibration tank used to perform the stray light tests of the LASCO and SECCHI coronagraphs on the SOHO and STEREO missions. This presentation will address the status of our system, recent measurements, and future plans.

  17. Absolute nuclear material assay

    DOEpatents

    Prasad, Manoj K.; Snyderman, Neal J.; Rowland, Mark S.

    2012-05-15

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  18. Absolute nuclear material assay

    DOEpatents

    Prasad, Manoj K.; Snyderman, Neal J.; Rowland, Mark S.

    2010-07-13

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  19. Thermal infrared radiometer calibration and experimental measurements

    NASA Astrophysics Data System (ADS)

    Wei, JiAn; Wang, Difeng; Gong, Fang; Yan, Bai; He, Xianqiang

    2015-08-01

    Thermal infrared radiometers play a vital role in obtaining information in field measurements and also in verifying information from remote sensing satellite sensor data. However, the calibration precision of the thermal infrared radiometers directly affects the accuracy of the remote sensing data analysis and application. It is therefore necessary to ensure that the calibration of thermal infrared radiometers is of sufficient and reliable precision. In this paper, the theory of a six-band thermal infrared radiometer (CE 312-2 ASTER) calibration method was introduced, with the calibration being conducted by using a blackbody source in the laboratory. The sources of error during the calibration procedure were analyzed, and the results of the calibration were provided. Then, laboratory experiments using the radiometer were described. The measurements of the surface temperature of a water sample that was contained in a thermostatic water bath, performed by using the radiometer, were compared to the water sample's temperature controlled by another device. These experiments were used to evaluate the calibration precision of the CE 312-2 ASTER radiometer, by means of assessing the measurement accuracy of the experiments. The results demonstrated that the calibration coefficients of the CE 312-2 ASTER thermal infrared radiometer displayed a very good performance, with highly accurate measurements, and could be used to detect phenomena related to a thermal infrared target.

  20. Measuring the instrument function of radiometers

    SciTech Connect

    Winston, R.; Littlejohn, R.G.

    1997-12-31

    The instrument function is a function of position and angle, the knowledge of which allows one to compute the response of a radiometer to an incident wave field in any state of coherence. The instrument function of a given radiometer need not be calculated; instead, it may be measured by calibration with incident plane waves.

  1. Portable Radiometer Identifies Minerals in the Field

    NASA Technical Reports Server (NTRS)

    Goetz, A. F. H.; Machida, R. A.

    1982-01-01

    Hand-held optical instrument aids in identifying minerals in field. Can be used in exploration for minerals on foot or by aircraft. The radiometer is especially suitable for identifying clay and carbonate minerals. Radiometer measures reflectances of mineral at two wavelengths, computes ratio of reflectances, and displays ratio to user.

  2. Radiometer Design Analysis Based Upon Measurement Uncertainty

    NASA Technical Reports Server (NTRS)

    Racette, Paul E.; Lang, Roger H.

    2004-01-01

    This paper introduces a method for predicting the performance of a radiometer design based on calculating the measurement uncertainty. The variety in radiometer designs and the demand for improved radiometric measurements justify the need for a more general and comprehensive method to assess system performance. Radiometric resolution, or sensitivity, is a figure of merit that has been commonly used to characterize the performance of a radiometer. However when evaluating the performance of a calibration design for a radiometer, the use of radiometric resolution has limited application. These limitations are overcome by considering instead the measurement uncertainty. A method for calculating measurement uncertainty for a generic radiometer design including its calibration algorithm is presented. The result is a generalized technique by which system calibration architectures and design parameters can be studied to optimize instrument performance for given requirements and constraints. Example applications demonstrate the utility of using measurement uncertainty as a figure of merit.

  3. The Radiometer Atmospheric Cubesat Experiment

    NASA Astrophysics Data System (ADS)

    Lim, B.; Bryk, M.; Clark, J.; Donahue, K.; Ellyin, R.; Misra, S.; Romero-Wolf, A.; Statham, S.; Steinkraus, J.; Lightsey, E. G.; Fear, A.; Francis, P.; Kjellberg, H.; McDonald, K.

    2014-12-01

    The Jet Propulsion Laboratory (JPL) has been developing the Radiometer Atmospheric CubeSat Experiment (RACE) since 2012, which consists of a water vapor radiometer integrated on a 3U CubeSat platform. RACE will measure 2 channels of the 183 GHz water vapor line, and will be used to validate new low noise amplifier (LNA) technology and a novel amplifier based internal calibration subsystem. The 3U spacecraft is provided by the University of Texas at Austin's Satellite Design Laboratory. RACE will advance the technology readiness level (TRL) of the 183 GHz receiver subsystem from TRL 4 to TRL 6 and a CubeSat 183 GHz radiometer system from TRL 4 to TRL 7. Measurements at 183 GHz are used to retrieve integrated products and vertical profiles of water vapor. Current full scale satellite missions that can utilize the technology include AMSU, ATMS, SSMIS and Megha-Tropiques. The LNAs are designed at JPL, based on a 35 nm indium phosphide (InP) high-electron-mobility transistors (HEMT) technology developed by Northrop Grumman. The resulting single chip LNAs require only 25 mW of power. Current pre-launch instrument performance specifications include an RF gain of over 30 dB and a room noise figure of < 9.5 dB. The noise figure is dominated by the insertion loss of the Dicke switch which at these frequencies are > 5dB. If a coupler based calibration system is shown to be sufficient, future receiver systems will have noise figures < 4 dB. The gain and noise figure variation over temperature is approximately 0.55 dB/K. The NEDT of the system is < 1K, and on orbit performance is expected to improve due to the thermal environment. The current system is configured for direct detection to reduce power consumption by eliminating the need for a local oscillator. A 2012 NASA CubeSat Launch Initiative (CSLI) selection, RACE is manifested for launch on the Orbital 3 (Orb-3) mission scheduled for October 2014. RACE will be deployed from the International Space Station (ISS) by NanoRacks.

  4. A Microwave Radiometer for Internal Body Temperature Measurement

    NASA Astrophysics Data System (ADS)

    Scheeler, Robert Patterson

    This thesis presents the analysis and design of a microwave radiometer for internal body temperature measurements. There is currently no available method for non-invasive temperature measurement inside the human body. However, knowledge of both relative and absolute temperature variations over time is important to a number of medical applications. The research presented in this thesis details a proof-of-concept near-field microwave radiometer demonstrating relative thermometry of a multi-layer phantom. There are a number of technical challenges addressed in this thesis for radiometric determination of sub-degree temperature variations in the human body. A theoretical approach is developed for determining sensing depth from known complex layered tissues, which is defined as a figure of merit, and is shown to be dependent on frequency, electrical properties of the tissues, and the near-field probe. In order to obtain depth resolution, multiple frequency operation can be used, so multi-frequency probes are designed and demonstrated in this work. The choice of frequencies is determined not only by the tissue material properties, but also by the ever increasing radio interference in the environment. In this work, quiet bands allocated to radio astronomy are investigated. The radiometer and probe need to be compact to be wearable, and several advancements are made towards a fully wearable device: multi-frequency low-profile probes are designed and fabricated on a flexible substrate and the process of on-chip integration is demonstrated by a GaAs MMIC cold noise source for radiometer calibration. The implemented proof-of-concept device consists of two radiometers at 1.4 GHz and 2.7 GHz, designed with commercial inexpensive devices that can enable sufficient sensitivity. The device is tested on a phantom with two water layers whose temperatures are varied in a controlled manner, and focused on the human body temperature range. Measured results are discussed qualitatively

  5. Infrared transfer radiometer for broadband and spectral calibration of space chambers

    NASA Astrophysics Data System (ADS)

    Jung, Timothy M.; Carter, Adriaan C.; Woods, Solomon I.; Kaplan, Simon G.; Datla, Raju U.

    2010-04-01

    The Low-Background Infrared (LBIR) facility at NIST has recently completed construction of an infrared transfer radiometer with an integrated cryogenic Fourier transform spectrometer (Cryo-FTS). This mobile system can be deployed to customer sites for broadband and spectral calibrations of space chambers and low-background HWIL testbeds. The Missile Defense Transfer Radiometer (MDXR) has many of the capabilities of a complete IR calibration facility and will replace our existing filter-based transfer radiometer (BXR) as the NIST standard detector deployed to MDA facilities. The MDXR features numerous improvements over the BXR, including: a cryogenic Fourier transform spectrometer, an on-board absolute cryogenic radiometer (ACR), an internal blackbody reference, and an integrated collimator. The Cryo-FTS can be used to measure high resolution spectra from 4 to 20 micrometers, using a Si:As blocked-impurity-band (BIB) detector. The on-board ACR can be used for self-calibration of the MDXR BIB as well as for absolute measurements of infrared sources. A set of filter wheels and a rotating polarizer within the MDXR allow for filter-based and polarization-sensitive measurements. The optical design of the MDXR makes both radiance and irradiance measurements possible and enables calibration of both divergent and collimated sources. Details of the various MDXR components will be presented as well as initial testing data on their performance.

  6. Distributed-switch Dicke radiometers

    NASA Technical Reports Server (NTRS)

    Levis, C. A. (Inventor)

    1979-01-01

    A radiometer on an orbiting spacecraft is described which derives high spatial resolution information from terrestrial and atmospheric regions. The N elements or subapertures on the spacecraft transduce electromagnetic energy into electric signals. Many or all of the elements are simultaneously illuminated by electromagnetic energy radiated from the same region. Identical, parallel processing channels are responsive to the N elements. Each of the channels includes a variable gain amplifier responsive to the signal transduced by its corresponding array elements. The gain of each amplifier is controlled as a function of the output difference when the channel is connected periodically to each of a pair of Dicke noise sources, such as resistors maintained at predetermined temperatures.

  7. Null-balancing microwave radiometer

    NASA Technical Reports Server (NTRS)

    Hardy, W. N.; Love, A. W.; Jones, A. C.

    1977-01-01

    Device performs absolute temperature measurements over range of 0 to 300 degrees Kelvin. Stability of device approaches 0.1 degrees Kelvin. Potential uses include detecting oil slicks on water and determining cloud water content and water vapor content of atmosphere.

  8. Design of a differential radiometer for atmospheric radiative flux measurements

    SciTech Connect

    LaDelfe, P.C.; Weber, P.G.; Rodriguez, C.W.

    1994-11-01

    The Hemispherical Optimized NEt Radiometer (HONER) is an instrument under development at the Los Alamos National Laboratory for deployment on an unmanned aerospace vehicle as part of the Atmospheric Radiation Measurements (ARM/UAV) program. HONER is a differential radiometer which will measure the difference between the total upwelling and downwelling fluxes and is intended to provide a means of measuring the atmospheric radiative flux divergence. Unlike existing instruments which measure the upwelling and downwelling fluxes separately, HONER will achieve an optical difference by chopping the two fluxes alternately onto a common pyroelectric detector. HONER will provide data resolved into two spectral bands; one covering the solar dominated region from less than 0.4 micrometer to approximately 4.5 micrometers and the other covering the region from approximately 4.5 micrometers to greater than 50 micrometers, dominated by thermal radiation. The means of separating the spectral regions guarantees seamless summation to calculate the total flux. The fields-of-view are near-hemispherical, upward and downward. The instrument can be converted, in flight, from the differential mode to absolute mode, measuring the upwelling and downwelling fluxes separately and simultaneously. The instrument also features continuous calibration from on-board sources. We will describe the design and operation of the sensor head and the on-board reference sources as well as the means of deployment.

  9. Comparative Analysis of Radiometer Systems Using Non-Stationary Processes

    NASA Technical Reports Server (NTRS)

    Racette, Paul; Lang, Roger; Krebs, Carolyn A. (Technical Monitor)

    2002-01-01

    Radiometers require periodic calibration to correct for instabilities in the receiver response. Various calibration techniques exist that minimize the effect of instabilities in the receivers. The optimal technique depends upon many parameters. Some parameters are constrained by the particular application and others can be chosen in the system design. For example, the measurement uncertainty may be reduced to the limits of the resolution of the measurement (sensitivity) if periodic absolute calibration can be performed with sufficient frequency. However if the period between calibrations is long, a reference-differencing technique, i.e. Dicke-type design, can yield better performance. The measurement uncertainty not only depends upon the detection scheme but also on the number of pixels between calibrations, the integration time per pixel, integration time per calibration reference measurement, calibration reference temperature, and the brightness temperature of what is being measured. The best scheme for reducing the measurement uncertainty also depends, in large part, on the stability of the receiver electronics. In this presentation a framework for evaluating calibration schemes for a wide range of system architectures is presented. Two methods for treating receiver non-stationarity are compared with radiometer measurements.

  10. Absolute biological needs.

    PubMed

    McLeod, Stephen

    2014-07-01

    Absolute needs (as against instrumental needs) are independent of the ends, goals and purposes of personal agents. Against the view that the only needs are instrumental needs, David Wiggins and Garrett Thomson have defended absolute needs on the grounds that the verb 'need' has instrumental and absolute senses. While remaining neutral about it, this article does not adopt that approach. Instead, it suggests that there are absolute biological needs. The absolute nature of these needs is defended by appeal to: their objectivity (as against mind-dependence); the universality of the phenomenon of needing across the plant and animal kingdoms; the impossibility that biological needs depend wholly upon the exercise of the abilities characteristic of personal agency; the contention that the possession of biological needs is prior to the possession of the abilities characteristic of personal agency. Finally, three philosophical usages of 'normative' are distinguished. On two of these, to describe a phenomenon or claim as 'normative' is to describe it as value-dependent. A description of a phenomenon or claim as 'normative' in the third sense does not entail such value-dependency, though it leaves open the possibility that value depends upon the phenomenon or upon the truth of the claim. It is argued that while survival needs (or claims about them) may well be normative in this third sense, they are normative in neither of the first two. Thus, the idea of absolute need is not inherently normative in either of the first two senses. PMID:23586876

  11. Absolute biological needs.

    PubMed

    McLeod, Stephen

    2014-07-01

    Absolute needs (as against instrumental needs) are independent of the ends, goals and purposes of personal agents. Against the view that the only needs are instrumental needs, David Wiggins and Garrett Thomson have defended absolute needs on the grounds that the verb 'need' has instrumental and absolute senses. While remaining neutral about it, this article does not adopt that approach. Instead, it suggests that there are absolute biological needs. The absolute nature of these needs is defended by appeal to: their objectivity (as against mind-dependence); the universality of the phenomenon of needing across the plant and animal kingdoms; the impossibility that biological needs depend wholly upon the exercise of the abilities characteristic of personal agency; the contention that the possession of biological needs is prior to the possession of the abilities characteristic of personal agency. Finally, three philosophical usages of 'normative' are distinguished. On two of these, to describe a phenomenon or claim as 'normative' is to describe it as value-dependent. A description of a phenomenon or claim as 'normative' in the third sense does not entail such value-dependency, though it leaves open the possibility that value depends upon the phenomenon or upon the truth of the claim. It is argued that while survival needs (or claims about them) may well be normative in this third sense, they are normative in neither of the first two. Thus, the idea of absolute need is not inherently normative in either of the first two senses.

  12. Scientific support of the Apollo infrared scanning radiometer experiment

    NASA Technical Reports Server (NTRS)

    Mendell, W. W.

    1976-01-01

    The Infrared Scanning Radiometer (ISR) was designed to map the thermal emission of the lunar surface from the service module of the orbiting Apollo 17 spacecraft. Lunar surface nighttime temperatures, which are extremely difficult to map from earth based telescopes were measured. The ISR transmitted approximately 90 hours of lunar data spread over 5 days in lunar orbit. Approximately 10 to the 8th power independent lunar temperature measurements were made with an absolute accuracy of 2K. Spatial resolution at nadir was approximately 2.2 km (depending on orbital altitude), exceeding that of earth based measurements by at least an order of magnitude. Preliminary studies of the data reveal the highest population of thermal anomalies (or hot spots) in Oceanus Procellarum. Very few anomalies exist on the far side of the moon as was predicted from the association of anomalies with mare on the near side. A number of negative anomalies (or cold spots) have also been found.

  13. Microwave Radiometer-High Frequency (MWRHF) Handbook

    SciTech Connect

    Caddedu, MP

    2011-03-17

    The 90/150-GHz Vapor Radiometer provides time-series measurements of brightness temperatures from two channels centered at 90 and 150 GHz. These two channels are sensitive to the presence of liquid water and precipitable water vapor.

  14. Galileo Photopolarimeter/Radiometer experiment

    NASA Technical Reports Server (NTRS)

    Russell, E. E.; Brown, F. G.; Chandos, R. A.; Fincher, W. C.; Kubel, L. F.; Lacis, A. A.; Travis, L. D.

    1992-01-01

    The Photopolarimeter/Radiometer (PPR) is a remote sensing instrument on the Galileo Orbiter designed to measure the degree of linear polarization and the intensity of reflected sunlight in ten spectral channels between 410 and 945 nm to determine the physical properties of Jovian clouds and aerosols, and to characterize the texture and microstructure of satellite surfaces. The PPR also measures thermal radiation in five spectral bands between 15 and 100 microns to sense the upper tropospheric temperature structure. Two additional channels which measure spectrally integrated solar and solar plus thermal radiation are used to determine the planetary radiation budget components. The PPR photopolarimetric measurements utilize previously flown technology for high-precision polarimetry using a calcite Wollaston prism and two silicon photodiodes to enable simultaneous detection of the two orthogonal polarization components. The PPR radiometry measurements are made with a lithium tantalate pyroelectric detector utilizing a unique arrangement of radiometric stops and a scene/space chopper blade to enable a warm instrument to sense accurately the much colder scene temperatures.

  15. Design of a geostationary microwave precipitation radiometer

    NASA Astrophysics Data System (ADS)

    Wilson, William J.; Eldred, Daniel B.

    1993-11-01

    The Geostationary Microwave Precipitation Radiometer will be a passive microwave radiometer system to be flown on the NASA Geostationary Earth Observatory. This instrument will provide microwave images for meteorology. It will measure radiation from the Earth and its atmosphere in seven frequency bands from 37 to 220 GHz. The instrument will have a 4 m Cassegrain antenna which will be mechanically scanned to provide images of the Earth in approximately equals 2 hours.

  16. The development of a stepped frequency microwave radiometer and its application to remote sensing of the Earth

    NASA Technical Reports Server (NTRS)

    Harrington, R. F.

    1980-01-01

    The design, development, application, and capabilities of a variable frequency microwave radiometer are described. This radiometer demonstrated the versatility, accuracy, and stability required to provide contributions to the geophysical understanding of ocean and ice processes. A closed-loop feedback method was used, whereby noise pulses were added to the received electromagnetic radiation to achieve a null balance in a Dicke switched radiometer. Stability was achieved through the use of a constant temperature enclosure around the low loss microwave front end. The Dicke reference temperature was maintained to an absolute accuracy of 0.1 K using a closed-loop proportional temperature controller. A microprocessor based digital controller operates the radiometer and records the data on computer compatible tapes. This radiometer exhibits an absolute accuracy of better than 0.5 K when the sensitivity is 0.1 K. The sensitivity varies between 0.0125 K and 1.25 K depending upon the bandwidth and integration time selected by the digital controller. Remote sensing experiments were conducted from an aircraft platform and the first radiometeric mapping of an ocean polar front; exploratory experiments to measure the thickness of lake ice; first discrimination between first year and multiyear ice below 10 GHz; and the first known measurements of frequency sensitive characteristics of sea ice.

  17. Using High-Resolution Hand-Held Radiometers To Measure In-Situ Thermal Resistance

    NASA Astrophysics Data System (ADS)

    Burch, Douglas M.; Krintz, Donald F.

    1984-03-01

    A field study was carried out to investigate the accuracy of using high-resolution radiometers to determine the in situ thermal resistance of building components having conventional residential construction. Two different types of radiometers were used to determine the thermal resistances of the walls of six test buildings located at the National Bureau of Standards. These radiometer thermal resistance measurements were compared to reference thermal resistance values determined from steady-state series resistance predictions, time-averaged heat-flow-sensor measurements, and guarded-hot-box measurements. When measurements were carried out 5 hours after sunset when the outdoor temperature was relatively steady and the heating plant was operated in a typical cyclic fashion, the following results were obtained: for lightweight wood-frame cavity walls, the radiometer procedures were found to distinguish wall thermal resistance 4.4 h.ft2- °F/Btu (0.77 m2•K/W) systematically higher than corresponding reference values. Such a discrimination will per-mit insulated and uninsulated walls to be distinguished. However, in the case of walls having large heat capacity (e.g., masonry and log), thermal storage effects produced large time lags between the outdoor diurnal temperature variation and the heat-flow response at the inside surface. This phenomenon caused radiometer thermal resistances to deviate substantially from corresponding reference values. This study recommends that the ANSI/ASHRAE Standard 101-1981 be modified requiring the heating plant to be operated in a typical cyclic fashion instead of being turned off prior to and during radiometer measurements.

  18. The absolute path command

    2012-05-11

    The ap command traveres all symlinks in a given file, directory, or executable name to identify the final absolute path. It can print just the final path, each intermediate link along with the symlink chan, and the permissions and ownership of each directory component in the final path. It has functionality similar to "which", except that it shows the final path instead of the first path. It is also similar to "pwd", but it canmore » provide the absolute path to a relative directory from the current working directory.« less

  19. The absolute path command

    SciTech Connect

    Moody, A.

    2012-05-11

    The ap command traveres all symlinks in a given file, directory, or executable name to identify the final absolute path. It can print just the final path, each intermediate link along with the symlink chan, and the permissions and ownership of each directory component in the final path. It has functionality similar to "which", except that it shows the final path instead of the first path. It is also similar to "pwd", but it can provide the absolute path to a relative directory from the current working directory.

  20. Narrow Angle Wide Spectral Range Radiometer Design FEANICS/REEFS Radiometer Design Report

    NASA Technical Reports Server (NTRS)

    Camperchioli, William

    2005-01-01

    A critical measurement for the Radiative Enhancement Effects on Flame Spread (REEFS) microgravity combustion experiment is the net radiative flux emitted from the gases and from the solid fuel bed. These quantities are measured using a set of narrow angle, wide spectral range radiometers. The radiometers are required to have an angular field of view of 1.2 degrees and measure over the spectral range of 0.6 to 30 microns, which presents a challenging design effort. This report details the design of this radiometer system including field of view, radiometer response, radiometric calculations, temperature effects, error sources, baffling and amplifiers. This report presents some radiometer specific data but does not present any REEFS experiment data.

  1. Cavity magnomechanics

    PubMed Central

    Zhang, Xufeng; Zou, Chang-Ling; Jiang, Liang; Tang, Hong X.

    2016-01-01

    A dielectric body couples with electromagnetic fields through radiation pressure and electrostrictive forces, which mediate phonon-photon coupling in cavity optomechanics. In a magnetic medium, according to the Korteweg-Helmholtz formula, which describes the electromagnetic force density acting on a medium, magneostrictive forces should arise and lead to phonon-magnon interaction. We report such a coupled phonon-magnon system based on ferrimagnetic spheres, which we term as cavity magnomechanics, by analogy to cavity optomechanics. Coherent phonon-magnon interactions, including electromagnetically induced transparency and absorption, are demonstrated. Because of the strong hybridization of magnon and microwave photon modes and their high tunability, our platform exhibits new features including parametric amplification of magnons and phonons, triple-resonant photon-magnon-phonon coupling, and phonon lasing. Our work demonstrates the fundamental principle of cavity magnomechanics and its application as a new information transduction platform based on coherent coupling between photons, phonons, and magnons. PMID:27034983

  2. Cavity magnomechanics.

    PubMed

    Zhang, Xufeng; Zou, Chang-Ling; Jiang, Liang; Tang, Hong X

    2016-03-01

    A dielectric body couples with electromagnetic fields through radiation pressure and electrostrictive forces, which mediate phonon-photon coupling in cavity optomechanics. In a magnetic medium, according to the Korteweg-Helmholtz formula, which describes the electromagnetic force density acting on a medium, magneostrictive forces should arise and lead to phonon-magnon interaction. We report such a coupled phonon-magnon system based on ferrimagnetic spheres, which we term as cavity magnomechanics, by analogy to cavity optomechanics. Coherent phonon-magnon interactions, including electromagnetically induced transparency and absorption, are demonstrated. Because of the strong hybridization of magnon and microwave photon modes and their high tunability, our platform exhibits new features including parametric amplification of magnons and phonons, triple-resonant photon-magnon-phonon coupling, and phonon lasing. Our work demonstrates the fundamental principle of cavity magnomechanics and its application as a new information transduction platform based on coherent coupling between photons, phonons, and magnons. PMID:27034983

  3. Novel Cyclotron-Based Radiometal Production

    SciTech Connect

    DeGrado, Timothy R.

    2013-10-31

    Accomplishments: (1) Construction of prototype solution target for radiometal production; (2) Testing of prototype target for production of following isotopes: a. Zr-89. Investigation of Zr-89 production from Y-89 nitrate solution. i. Defined problems of gas evolution and salt precipitation. ii. Solved problem of precipitation by addition of nitric acid. iii. Solved gas evolution problem with addition of backpressure regulator and constant degassing of target during irradiations. iv. Investigated effects of Y-89 nitrate concentration and beam current. v. Published abstracts at SNM and ISRS meetings; (3) Design of 2nd generation radiometal solution target. a. Included reflux chamber and smaller target volume to conserve precious target materials. b. Included aluminum for prototype and tantalum for working model. c. Included greater varicosities for improved heat transfer; and, (4) Construction of 2nd generation radiometal solution target started.

  4. Microwave radiometer for subsurface temperature measurement

    NASA Technical Reports Server (NTRS)

    Porter, R. A.; Bechis, K. P.

    1976-01-01

    A UHF radiometer, operating at a frequency of 800 MHz, was modified to provide an integral, three frequency voltage standing wave ratio (VSWR) circuit in the radio frequency (RF) head. The VSWR circuit provides readings of power transmission at the antenna-material interface with an accuracy of plus or minus 5 percent. The power transmission readings are numerically equal to the emissivity of the material under observation. Knowledge of material emissivity is useful in the interpretation of subsurface apparent temperatures obtained on phantom models of biological tissue. The emissivities of phantom models consisting of lean beefsteak were found to lie in the range 0.623 to 0.779, depending on moisture content. Radiometric measurements performed on instrumented phantoms showed that the radiometer was capable of sensing small temperature changes occurring at depths of at least 19 to 30 mm. This is consistent with previously generated data which showed that the radiometer could sense temperatures at a depth of 38 mm.

  5. Achieving Climate Change Absolute Accuracy in Orbit

    NASA Technical Reports Server (NTRS)

    Wielicki, Bruce A.; Young, D. F.; Mlynczak, M. G.; Thome, K. J; Leroy, S.; Corliss, J.; Anderson, J. G.; Ao, C. O.; Bantges, R.; Best, F.; Bowman, K.; Brindley, H.; Butler, J. J.; Collins, W.; Dykema, J. A.; Doelling, D. R.; Feldman, D. R.; Fox, N.; Huang, X.; Holz, R.; Huang, Y.; Jennings, D.; Jin, Z.; Johnson, D. G.; Jucks, K.; Kato, S.; Kratz, D. P.; Liu, X.; Lukashin, C.; Mannucci, A. J.; Phojanamongkolkij, N.; Roithmayr, C. M.; Sandford, S.; Taylor, P. C.; Xiong, X.

    2013-01-01

    The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission will provide a calibration laboratory in orbit for the purpose of accurately measuring and attributing climate change. CLARREO measurements establish new climate change benchmarks with high absolute radiometric accuracy and high statistical confidence across a wide range of essential climate variables. CLARREO's inherently high absolute accuracy will be verified and traceable on orbit to Système Internationale (SI) units. The benchmarks established by CLARREO will be critical for assessing changes in the Earth system and climate model predictive capabilities for decades into the future as society works to meet the challenge of optimizing strategies for mitigating and adapting to climate change. The CLARREO benchmarks are derived from measurements of the Earth's thermal infrared spectrum (5-50 micron), the spectrum of solar radiation reflected by the Earth and its atmosphere (320-2300 nm), and radio occultation refractivity from which accurate temperature profiles are derived. The mission has the ability to provide new spectral fingerprints of climate change, as well as to provide the first orbiting radiometer with accuracy sufficient to serve as the reference transfer standard for other space sensors, in essence serving as a "NIST [National Institute of Standards and Technology] in orbit." CLARREO will greatly improve the accuracy and relevance of a wide range of space-borne instruments for decadal climate change. Finally, CLARREO has developed new metrics and methods for determining the accuracy requirements of climate observations for a wide range of climate variables and uncertainty sources. These methods should be useful for improving our understanding of observing requirements for most climate change observations.

  6. Three Averaging Techniques for Reduction of Antenna Temperature Variance Measured by a Dicke Mode, C-Band Radiometer

    NASA Technical Reports Server (NTRS)

    Mackenzie, Anne I.; Lawrence, Roland W.

    2000-01-01

    As new radiometer technologies provide the possibility of greatly improved spatial resolution, their performance must also be evaluated in terms of expected sensitivity and absolute accuracy. As aperture size increases, the sensitivity of a Dicke mode radiometer can be maintained or improved by application of any or all of three digital averaging techniques: antenna data averaging with a greater than 50% antenna duty cycle, reference data averaging, and gain averaging. An experimental, noise-injection, benchtop radiometer at C-band showed a 68.5% reduction in Delta-T after all three averaging methods had been applied simultaneously. For any one antenna integration time, the optimum 34.8% reduction in Delta-T was realized by using an 83.3% antenna/reference duty cycle.

  7. Low-cost microprocessor controlled shadowband radiometer

    NASA Astrophysics Data System (ADS)

    Michalsky, J. J.; Lebaron, B. A.; Harrison, L. C.

    1985-06-01

    This paper describes the second phase in the development of a low-cost microprocessor-controlled rotating shadowband radiometer at PNL. The initial work, to develop a solar photometer, resulted in a mechanical design that is adopted for the solar radiometer with only minor changes. The goals of this effort are: (1) to improve the data acquisition system; and (2) to derive corrections for the silicon cell-based pyranometer that would allow measurements of total horizontal, diffuse horizontal, and direct normal solar radiation approaching first-class instrumentation accuracy at a fraction of the cost. Significant progress on temperature, cosine and spectral corrections is achieved.

  8. Salinity surveys using an airborne microwave radiometer

    NASA Technical Reports Server (NTRS)

    Paris, J. F.; Droppleman, J. D.; Evans, D. E.

    1972-01-01

    The Barnes PRT-5 infrared radiometer and L-band channel of the multifrequency microwave radiometer are used to survey the distribution of surface water temperature and salinity. These remote sensors were flown repetitively in November 1971 over the outflow of the Mississippi River into the Gulf of Mexico. Data reduction parameters were determined through the use of flight data obtained over a known water area. With these parameters, the measured infrared and microwave radiances were analyzed in terms of the surface temperature and salinity.

  9. The Hurricane Imaging Radiometer: Present and Future

    NASA Technical Reports Server (NTRS)

    Miller, Timothy L.; James, M. W.; Roberts, J. B.; Biswas, S. K.; Cecil, D.; Jones, W. L.; Johnson, J.; Farrar, S.; Sahawneh, S.; Ruf, C. S.; Morris, M.; Uhlhorn, E. W.; Black, P. G.

    2013-01-01

    The Hurricane Imaging Radiometer (HIRAD) is an airborne passive microwave radiometer designed to provide high resolution, wide swath imagery of surface wind speed in tropical cyclones from a low profile planar antenna with no mechanical scanning. Wind speed and rain rate images from HIRAD's first field campaign (GRIP, 2010) are presented here followed, by a discussion on the performance of the newly installed thermal control system during the 2012 HS3 campaign. The paper ends with a discussion on the next generation dual polarization HIRAD antenna (already designed) for a future system capable of measuring wind direction as well as wind speed.

  10. Development of a new radiometer for the thermodynamic measurement of high temperature fixed points

    SciTech Connect

    Dury, M. R.; Goodman, T. M.; Lowe, D. H.; Machin, G.; Woolliams, E. R.

    2013-09-11

    The National Physical Laboratory (NPL) has developed a new radiometer to measure the thermodynamic melting point temperatures of high temperature fixed points with ultra-low uncertainties. In comparison with the NPL's Absolute Radiation Thermometer (ART), the 'THermodynamic Optical Radiometer' (THOR) is more portable and compact, with a much lower size-of-source effect and improved performance in other parameters such as temperature sensitivity. It has been designed for calibration as a whole instrument via the radiance method, removing the need to calibrate the individual subcomponents, as required by ART, and thereby reducing uncertainties. In addition, the calibration approach has been improved through a new integrating sphere that has been designed to have greater uniformity.

  11. Design and first plasma measurements of the ITER-ECE prototype radiometer

    NASA Astrophysics Data System (ADS)

    Austin, M. E.; Brookman, M. W.; Rowan, W. L.; Danani, S.; Bryerton, E. W.; Dougherty, P.

    2016-11-01

    On ITER, second harmonic optically thick electron cyclotron emission (ECE) in the range of 220-340 GHz will supply the electron temperature (Te). To investigate the requirements and capabilities prescribed for the ITER system, a prototype radiometer covering this frequency range has been developed by Virginia Diodes, Inc. The first plasma measurements with this instrument have been carried out on the DIII-D tokamak, with lab bench tests and measurements of third through fifth harmonic ECE from high Te plasmas. At DIII-D the instrument shares the transmission line of the Michelson interferometer and can simultaneously acquire data. Comparison of the ECE radiation temperature from the absolutely calibrated Michelson and the prototype receiver shows that the ITER radiometer provides accurate measurements of the millimeter radiation across the instrument band.

  12. Calibration of a helium-cooled infrared spatial radiometer and grating spectrometer

    NASA Technical Reports Server (NTRS)

    Jacobsen, Larry; Sargent, Steve; Wyatt, Clair L.; Steed, Allan J.

    1992-01-01

    Methods used by the Space Dynamics Laboratory of Utah State University (SDL/USU) to calibrate infrared sensors are described, using the Infrared Background Signature Survey (IBSS) spatial radiometer and grating spectrometer as examples. A calibration equation and a radiometric model are given for each sensor to describe their responsivity in terms of individual radiometric parameters. The calibration equation terms include dark offset, linearity, absolute responsivity, and measurement uncertainty, and the radiometric model domains include spatial, spectral, and temporal domains. A portable calibration facility, designed and fabricated by SDL/USU, provided collimated, extended, diffuse scatter, and Jones sources in a single cryogenic dewar. This multi-function calibrator allowed calibration personnel to complete a full calibration of the IBSS infrared radiometer and spectrometer in two 15-day periods. A calibration data system was developed to control and monitor the calibration facility, and to record and analyze sensor data.

  13. Calibrating ground-based microwave radiometers: Uncertainty and drifts

    NASA Astrophysics Data System (ADS)

    Küchler, N.; Turner, D. D.; Löhnert, U.; Crewell, S.

    2016-04-01

    The quality of microwave radiometer (MWR) calibrations, including both the absolute radiometric accuracy and the spectral consistency, determines the accuracy of geophysical retrievals. The Microwave Radiometer Calibration Experiment (MiRaCalE) was conducted to evaluate the performance of MWR calibration techniques, especially of the so-called Tipping Curve Calibrations (TCC) and Liquid Nitrogen Calibrations (LN2cal), by repeatedly calibrating a fourth-generation Humidity and Temperature Profiler (HATPRO-G4) that measures downwelling radiance between 20 GHz and 60 GHz. MiRaCalE revealed two major points to improve MWR calibrations: (i) the necessary repetition frequency for MWR calibration techniques to correct drifts, which ensures stable long-term measurements; and (ii) the spectral consistency of control measurements of a well known reference is useful to estimate calibration accuracy. Besides, we determined the accuracy of the HATPRO's liquid nitrogen-cooled blackbody's temperature. TCCs and LN2cals were found to agree within 0.5 K when observing the liquid nitrogen-cooled blackbody with a physical temperature of 77 K. This agreement of two different calibration techniques suggests that the brightness temperature of the LN2 cooled blackbody is accurate within at least 0.5 K, which is a significant reduction of the uncertainties that have been assumed to vary between 0.6 K and 1.5 K when calibrating the HATPRO-G4. The error propagation of both techniques was found to behave almost linearly, leading to maximum uncertainties of 0.7 K when observing a scene that is associated with a brightness temperature of 15 K.

  14. An investigation of radiometer design using digital processing techniques

    NASA Technical Reports Server (NTRS)

    Lawrence, R. W.

    1981-01-01

    The use of digital signal processing techniques in Dicke switching radiometer design was investigated. The general approach was to develop an analytical model of the existing analog radiometer and identify factors which adversly affect its performance. A digital processor was then proposed to verify the feasibility of using digital techniques to minimize these adverse effects and improve the radiometer performance. Analysis and preliminary test results comparing the digital and analog processing approaches in radiometers design were analyzed.

  15. The absolute radiometric calibration of the advanced very high resolution radiometer

    NASA Technical Reports Server (NTRS)

    Slater, P. N.; Teillet, P. M.; Ding, Y.

    1989-01-01

    The measurement conditions are described for an intensive field campaign at White Sands Missile Range for the calibration of the AVHRRs on NOAA-9, NOAA-10 and NOAA-11, LANDSAT-4 TM and SPOT. Three different methods for calibration of AVHRRs by reference to a ground surface site are reported, and results from these methods are compared. Significant degradations in NOAA-9 and NOAA-10 AVHRR responsivities occurred since prelaunch calibrations were completed. As of February 1988, degradations in NOAA-9 AVHRR responsivities were on the order of 37 percent in channel and 41 percent in channel 2, and for the NOAA-10 AVHRR these degradations were 42 and 59 percent in channels 1 and 2, respectively.

  16. Calibration of ground-based microwave radiometers - Accuracy assessment and recommendations for network users

    NASA Astrophysics Data System (ADS)

    Pospichal, Bernhard; Küchler, Nils; Löhnert, Ulrich; Crewell, Susanne; Czekala, Harald; Güldner, Jürgen

    2016-04-01

    Ground-based microwave radiometers (MWR) are becoming widely used in atmospheric remote sensing and start to be routinely operated by national weather services and other institutions. However, common standards for calibration of these radiometers and a detailed knowledge about the error characteristics is needed, in order to assimilate the data into models. Intercomparisons of calibrations by different MWRs have rarely been done. Therefore, two calibration experiments in Lindenberg (2014) and Meckenheim (2015) were performed in the frame of TOPROF (Cost action ES1303) in order to assess uncertainties and differences between various instruments. In addition, a series of experiments were taken in Oklahoma in autumn 2014. The focus lay on the performance of the two main instrument types, which are currently used operationally. These are the MP-Profiler series by Radiometrics Corporation as well as the HATPRO series by Radiometer Physics GmbH (RPG). Both instrument types are operating in two frequency bands, one along the 22 GHz water vapour line, the other one at the lower wing of the 60 GHz oxygen absorption complex. The goal was to establish protocols for providing quality controlled (QC) MWR data and their uncertainties. To this end, standardized calibration procedures for MWR were developed and recommendations for radiometer users were compiled. We focus here mainly on data types, integration times and optimal settings for calibration intervals, both for absolute (liquid nitrogen, tipping curve) as well as relative (hot load, noise diode) calibrations. Besides the recommendations for ground-based MWR operators, we will present methods to determine the accuracy of the calibration as well as means for automatic data quality control. In addition, some results from the intercomparison of different radiometers will be discussed.

  17. Heat capacity mapping radiometer for AEM spacecraft

    NASA Technical Reports Server (NTRS)

    Sonnek, G. E.

    1977-01-01

    The operation, maintenance, and integration of the applications explorer mission heat capacity mapping radiometer is illustrated in block diagrams and detail schematics of circuit functions. Data format and logic timing diagrams are included along with radiometric and electronic calibration data. Mechanical and electrical configuration is presented to provide interface details for integration of the HCMR instrument to AEM spacecraft.

  18. LARSPEC spectroradiometer-multiband radiometer data formats

    NASA Technical Reports Server (NTRS)

    Biehl, L. L.

    1982-01-01

    The data base software system, LARSPEC, is discussed and the data base format for agronomic, meteorological, spectroradiometer, and multiband radiometer data is described. In addition, the contents and formats of each record of data and the wavelength tables are listed and the codes used for some of the parameters are described.

  19. Balloon-borne radiometer profiler: Field observations

    SciTech Connect

    Shaw, W.J.; Whiteman, C.D.; Anderson, G.A.; Alzheimer, J.M.; Hubbe, J.M.; Scott, K.A.

    1995-03-01

    This project involves the development of the capability of making routine soundings of broadband radiative fluxes and radiative flux divergences to heights of 1500m AGL. Described in this document are radiometers carried on a stabilized platform in a harness inserted in the tetherline of a tethered balloon meteriological sounding system. Field test results are given.

  20. Accounting For Nonlinearity In A Microwave Radiometer

    NASA Technical Reports Server (NTRS)

    Stelzried, Charles T.

    1991-01-01

    Simple mathematical technique found to account adequately for nonlinear component of response of microwave radiometer. Five prescribed temperatures measured to obtain quadratic calibration curve. Temperature assumed to vary quadratically with reading. Concept not limited to radiometric application; applicable to other measuring systems in which relationships between quantities to be determined and readings of instruments differ slightly from linearity.

  1. Scanning and focusing mechanisms of METEOSAT radiometer

    NASA Technical Reports Server (NTRS)

    Jouan, J.

    1977-01-01

    Two mechanisms, both of screw-jack type are described. The scanning mechanism, an oil lubricated and sealed unit drives and accurately positions the telescope of the METEOSAT radiometer. The dry lubricated focusing mechanism is used to adjust the focus of this telescope. The METEOSAT program is nearly completed, and the first flight model will be launched at the end of the year.

  2. The microwave radiometer spacecraft: A design study

    NASA Technical Reports Server (NTRS)

    Wright, R. L. (Editor)

    1981-01-01

    A large passive microwave radiometer spacecraft with near all weather capability of monitoring soil moisture for global crop forecasting was designed. The design, emphasizing large space structures technology, characterized the mission hardware at the conceptual level in sufficient detail to identify enabling and pacing technologies. Mission and spacecraft requirements, design and structural concepts, electromagnetic concepts, and control concepts are addressed.

  3. Application of Uncooled Monolithic Thermoelectric Linear Arrays to Imaging Radiometers

    NASA Astrophysics Data System (ADS)

    Kruse, Paul W.

    Introduction Identification of Incipient Failure of Railcar Wheels Technical Description of the Model IR 1000 Imaging Radiometer Performance of the Model IR 1000 Imaging Radiometer Initial Application Summary Imaging Radiometer for Predictive and Preventive Maintenance Description Operation Specifications Summary References INDEX CONTENTS OF VOLUMES IN THIS SERIES

  4. Microfluidic radiolabeling of biomolecules with PET radiometals

    PubMed Central

    Zeng, Dexing; Desai, Amit V.; Ranganathan, David; Wheeler, Tobias D.; Kenis, Paul J. A.; Reichert, David E.

    2012-01-01

    Introduction A robust, versatile and compact microreactor has been designed, fabricated and tested for the labeling of bifunctional chelate conjugated biomolecules (BFC-BM) with PET radiometals. Methods The developed microreactor was used to radiolabel a chelate, either 1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) or 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA) that had been conjugated to cyclo(Arg-Gly-Asp-DPhe-Lys) peptide, with both 64Cu and 68Ga respectively. The microreactor radiolabeling conditions were optimized by varying temperature, concentration and residence time. Results Direct comparisons between the microreactor approach and conventional methods showed improved labeling yields and increased reproducibility with the microreactor under identical labeling conditions, due to enhanced mass and heat transfer at the microscale. More importantly, over 90% radiolabeling yields (incorporation of radiometal) were achieved with a 1:1 stoichiometry of bifunctional chelate biomolecule conjugate (BFC-BM) to radiometal in the microreactor, which potentially obviates extensive chromatographic purification that is typically required to remove the large excess of unlabeled biomolecule in radioligands prepared using conventional methods. Moreover, higher yields for radiolabeling of DOTA-functionalized BSA protein (Bovine Serum Albumin) were observed with 64Cu/68Ga using the microreactor, which demonstrates the ability to label both small and large molecules. Conclusions A robust, reliable, compact microreactor capable of chelating radiometals with common chelates has been developed and validated. Based on our radiolabeling results, the reported microfluidic approach overall outperforms conventional radiosynthetic methods, and is a promising technology for the radiometal labeling of commonly utilized BFC-BM in aqueous solutions. PMID:23078875

  5. Wideband filter radiometers for blackbody temperature measurements

    NASA Astrophysics Data System (ADS)

    Boivin, L. P.; Bamber, C.; Gaertner, A. A.; Gerson, R. K.; Woods, D. J.; Woolliams, E. R.

    2010-10-01

    The use of high-temperature blackbody (HTBB) radiators to realize primary spectral irradiance scales requires that the operating temperature of the HTBB be accurately determined. We have developed five filter radiometers (FRs) to measure the temperature of the National Research Council of Canada's HTBB. The FRs are designed to minimize sensitivity to ambient temperature fluctuations. They incorporate air-spaced colored glass filters and a Si photodiode detector that are housed in a cell whose temperature is controlled to ±0.1°C by means of annular thermoelectric elements at the front and rear of the cell. These wideband filter radiometers operate in four different wavelength bands. The spectral responsivity measurements were performed in an underfill geometry for a power-mode calibration that is traceable to NRC's cryogenic radiometer. The spectral temperature sensitivity of each of these FRs has been measured. The apertures for these FRs were cold-formed by swaging machine-cut apertures onto precision dowel pins. A description of the filter radiometer design, fabrication and testing, together with a detailed uncertainty analysis, is presented. We derive the equations that relate the spectral irradiance measured by the FRs to the spectral radiance and temperature of the HTBB, and deal specifically with the change of index of refraction over the path of the radiation from the interior of the HTBB to the FRs. We believe these equations are more accurate than recently published derivations. Our measurements of the operating temperature of our HTBB working at temperatures near 2500 K, 2700 K and 2900 K, together with measurements using a pyrometer, show agreement between the five filter radiometers and with the pyrometer to within the estimated uncertainties.

  6. Mobile Microwave Radiometer Observations: Spatial Characteristics of Supercooled Cloud Water and Cloud Seeding Implications.

    NASA Astrophysics Data System (ADS)

    Huggins, Arlen W.

    1995-02-01

    Previous studies of the spatial distribution of supercooled liquid water in winter storms over mountainous terrain were performed primarily with instrumented aircraft and to a lesser extent with scans from a stationary microwave radiometer. The present work describes a new technique of mobile radiometer operation that was successfully used during numerous winter storms that occurred over the Wasatch Plateau of central Utah to determine the integrated depth of cloud liquid water relative to horizontal position on the mountain barrier. The technique had the advantage of being able to measure total liquid from the terrain upward, without the usual terrain avoidance problems that research aircraft face in cloudy conditions. The radiometer also collected data during several storms in which a research aircraft could not be operated because of severe turbulence and icing conditions.Repeated radiometer transects of specific regions of the plateau showed significant variability in liquid water depth over 30 60-min time periods, but also revealed that the profile of orographically generated cloud liquid was consistent, regardless of the absolute quantities. Radiometer liquid depth generally increased across the windward slope of the plateau to a peak near the western edge of the plateau top and then decreased across the relatively flat top of the plateau. These observations were consistent with regions where maximum and minimum vertical velocities were expected, and with depiction of cloud liquid by accretional ice particle growth across the mountain barrier. A comparison of data from the mobile radiometer and a stationary radiometer verified the general decrease in liquid depth from the windward slope to the top of the plateau and also showed that many liquid water regions were transient mesoscale features that moved across the plateau.Implications of the results, relative to the seeding of orographic clouds, were that seeding aerosols released from valley-based generators

  7. ABSOLUTE POLARIMETRY AT RHIC.

    SciTech Connect

    OKADA; BRAVAR, A.; BUNCE, G.; GILL, R.; HUANG, H.; MAKDISI, Y.; NASS, A.; WOOD, J.; ZELENSKI, Z.; ET AL.

    2007-09-10

    Precise and absolute beam polarization measurements are critical for the RHIC spin physics program. Because all experimental spin-dependent results are normalized by beam polarization, the normalization uncertainty contributes directly to final physics uncertainties. We aimed to perform the beam polarization measurement to an accuracy Of {Delta}P{sub beam}/P{sub beam} < 5%. The absolute polarimeter consists of Polarized Atomic Hydrogen Gas Jet Target and left-right pairs of silicon strip detectors and was installed in the RHIC-ring in 2004. This system features proton-proton elastic scattering in the Coulomb nuclear interference (CNI) region. Precise measurements of the analyzing power A{sub N} of this process has allowed us to achieve {Delta}P{sub beam}/P{sub beam} = 4.2% in 2005 for the first long spin-physics run. In this report, we describe the entire set up and performance of the system. The procedure of beam polarization measurement and analysis results from 2004-2005 are described. Physics topics of AN in the CNI region (four-momentum transfer squared 0.001 < -t < 0.032 (GeV/c){sup 2}) are also discussed. We point out the current issues and expected optimum accuracy in 2006 and the future.

  8. Absolute Equilibrium Entropy

    NASA Technical Reports Server (NTRS)

    Shebalin, John V.

    1997-01-01

    The entropy associated with absolute equilibrium ensemble theories of ideal, homogeneous, fluid and magneto-fluid turbulence is discussed and the three-dimensional fluid case is examined in detail. A sigma-function is defined, whose minimum value with respect to global parameters is the entropy. A comparison is made between the use of global functions sigma and phase functions H (associated with the development of various H-theorems of ideal turbulence). It is shown that the two approaches are complimentary though conceptually different: H-theorems show that an isolated system tends to equilibrium while sigma-functions allow the demonstration that entropy never decreases when two previously isolated systems are combined. This provides a more complete picture of entropy in the statistical mechanics of ideal fluids.

  9. Climate Absolute Radiance and Refractivity Observatory (CLARREO)

    NASA Technical Reports Server (NTRS)

    Leckey, John P.

    2015-01-01

    The Climate Absolute Radiance and Refractivity Observatory (CLARREO) is a mission, led and developed by NASA, that will measure a variety of climate variables with an unprecedented accuracy to quantify and attribute climate change. CLARREO consists of three separate instruments: an infrared (IR) spectrometer, a reflected solar (RS) spectrometer, and a radio occultation (RO) instrument. The mission will contain orbiting radiometers with sufficient accuracy, including on orbit verification, to calibrate other space-based instrumentation, increasing their respective accuracy by as much as an order of magnitude. The IR spectrometer is a Fourier Transform spectrometer (FTS) working in the 5 to 50 microns wavelength region with a goal of 0.1 K (k = 3) accuracy. The FTS will achieve this accuracy using phase change cells to verify thermistor accuracy and heated halos to verify blackbody emissivity, both on orbit. The RS spectrometer will measure the reflectance of the atmosphere in the 0.32 to 2.3 microns wavelength region with an accuracy of 0.3% (k = 2). The status of the instrumentation packages and potential mission options will be presented.

  10. Monolithic microwave integrated circuit water vapor radiometer

    NASA Technical Reports Server (NTRS)

    Sukamto, L. M.; Cooley, T. W.; Janssen, M. A.; Parks, G. S.

    1991-01-01

    A proof of concept Monolithic Microwave Integrated Circuit (MMIC) Water Vapor Radiometer (WVR) is under development at the Jet Propulsion Laboratory (JPL). WVR's are used to remotely sense water vapor and cloud liquid water in the atmosphere and are valuable for meteorological applications as well as for determination of signal path delays due to water vapor in the atmosphere. The high cost and large size of existing WVR instruments motivate the development of miniature MMIC WVR's, which have great potential for low cost mass production. The miniaturization of WVR components allows large scale deployment of WVR's for Earth environment and meteorological applications. Small WVR's can also result in improved thermal stability, resulting in improved calibration stability. Described here is the design and fabrication of a 31.4 GHz MMIC radiometer as one channel of a thermally stable WVR as a means of assessing MMIC technology feasibility.

  11. Nulling Infrared Radiometer for Measuring Temperature

    NASA Technical Reports Server (NTRS)

    Ryan, Robert

    2003-01-01

    A nulling, self-calibrating infrared radiometer is being developed for use in noncontact measurement of temperature in any of a variety of industrial and scientific applications. This instrument is expected to be especially well-suited to measurement of ambient or near-ambient temperature and, even more specifically, for measuring the surface temperature of a natural body of water. Although this radiometer would utilize the long-wavelength infrared (LWIR) portion of the spectrum (wavelengths of 8 to 12 m), its basic principle of operation could also be applied to other spectral bands (corresponding to other temperature ranges) in which the atmosphere is transparent and in which design requirements for sensitivity and temperature-measurement accuracy could be satisfied.

  12. Galileo Net Flux Radiometer Report 1997

    NASA Technical Reports Server (NTRS)

    Tomasko, Martin G.

    1997-01-01

    On 7 December 1995, the Galileo probe entered Jupiter's atmosphere. The Net Flux Radiometer (NFR) on board the probe, measured upward and downward fluxes in the visible and infrared. At the University of Arizona, we have analyzed the data from the two visible-light channels, as well as the solar contributions to the thermal channels. The results are being prepared for submission to JGR in early September.

  13. Analysis of radiometer calibration effects with TOUCHSTONE

    NASA Technical Reports Server (NTRS)

    Stanley, William D.

    1990-01-01

    The microwave circuit analysis program TOUCHSTONE is used to study two effects of importance in radiometer calibration. The two effects are impedance mismatches at the antenna-air and cold load-air interfaces and dissipatives losses, which radiate thermal noise into the system. The results predicted by TOUCHSTONE are shown to be in very close agreement with earlier results obtained by purely analytical methods. The techniques used in establishing the circuit models and in processing the resulting data are described in detail.

  14. Requirements for an Advanced Ocean Radiometer

    NASA Technical Reports Server (NTRS)

    Meister, Gerhard; McClain, Charles R.; Ahmad, Ziauddin; Bailey, Sean W.; Barnes, Robert A.; Brown, Steven; Eplee, Robert E.; Franz, Bryan; Holmes, Alan; Monosmith, W. Bryan; Patt, Frederick S.; Stumpf, Richard P.; Turpie, Kevin R.; Werdell, P. Jeremy

    2011-01-01

    This document suggests requirements for an advanced ocean radiometer, such as e.g. the ACE (Aerosol/Cloud/Ecosystem) ocean radiometer. The ACE ocean biology mission objectives have been defined in the ACE Ocean Biology white paper. The general requirements presented therein were chosen as the basis for the requirements provided in this document, which have been transformed into specific, testable requirements. The overall accuracy goal for the advanced ocean radiometer is that the total radiometric uncertainties are 0.5% or smaller for all bands. Specific mission requirements of SeaWiFS, MODIS, and VIIRS were often used as a model for the requirements presented here, which are in most cases more demanding than the heritage requirements. Experience with on-orbit performance and calibration (from SeaWiFS and MODIS) and prelaunch testing (from SeaWiFS, MODIS, and VIIRS) were important considerations when formulating the requirements. This document describes requirements in terms of the science data products, with a focus on qualities that can be verified by prelaunch radiometric characterization. It is expected that a more comprehensive requirements document will be developed during mission formulation

  15. Multifrequency microwave radiometer measurements of soil moisture

    NASA Technical Reports Server (NTRS)

    Njoku, E. G.; Oneill, P. E.

    1982-01-01

    Ground-based microwave radiometer experiments are carried out to investigate the effects of moisture, temperature, and roughness on microwave emission from bare soils. The measurements are made at frequencies of 0.6-0.9, 1.4, and 10.7 GHz using van-mounted radiometers to observe prepared soil sites in Kern County, CA. Brightness temperature variations of approximately 15 K at 1.4 GHz and 25 K at 10.7 GHz are observed as a result of diurnal changes in the soil temperature. Increasing the soil moisture content from 2% to 15% by volume is found to result in brightness temperature decreases of approximately 70 K at 0.775 and 1.4 GHz and 40 K at 10.7 GHz, depending, to a lesser extent, on polarization and viewing angle. The results attest the significance of soil temperature in deriving soil moisture from microwave radiometer measurements. Comparisons of the microwave measurements with theoretical predictions using smooth surface models give reasonable agreement and support previous results of this nature obtained with other soil types.

  16. Advanced Microwave Radiometer (AMR) for SWOT mission

    NASA Astrophysics Data System (ADS)

    Chae, C. S.

    2015-12-01

    The objective of the SWOT (Surface Water & Ocean Topography) satellite mission is to measure wide-swath, high resolution ocean topography and terrestrial surface waters. Since main payload radar will use interferometric SAR technology, conventional microwave radiometer system which has single nadir look antenna beam (i.e., OSTM/Jason-2 AMR) is not ideally applicable for the mission for wet tropospheric delay correction. Therefore, SWOT AMR incorporates two antenna beams along cross track direction. In addition to the cross track design of the AMR radiometer, wet tropospheric error requirement is expressed in space frequency domain (in the sense of cy/km), in other words, power spectral density (PSD). Thus, instrument error allocation and design are being done in PSD which are not conventional approaches for microwave radiometer requirement allocation and design. A few of novel analyses include: 1. The effects of antenna beam size to PSD error and land/ocean contamination, 2. Receiver error allocation and the contributions of radiometric count averaging, NEDT, Gain variation, etc. 3. Effect of thermal design in the frequency domain. In the presentation, detailed AMR design and analyses results will be discussed.

  17. The MASCOT Radiometer MARA for the Hayabusa 2 Mission

    NASA Astrophysics Data System (ADS)

    Grott, M.; Knollenberg, J.; Borgs, B.; Hänschke, F.; Kessler, E.; Helbert, J.; Maturilli, A.; Müller, N.

    2016-08-01

    The MASCOT radiometer MARA is a multi-spectral instrument which measures net radiative flux in six wavelength bands. MARA uses thermopile sensors as sensing elements, and the net flux between the instrument and the surface in the 18° field of view is determined by evaluating the thermoelectric potential between the sensors' absorbing surface and the thermopile's cold-junction. MARA houses 4 bandpass channels in the spectral range of 5.5-7, 8-9.5, 9.5-11.5, and 13.5-15.5 μm, as well as one long-pass channel, which is sensitive in the >3 μm range. In addition, one channel is similar to that used by the Hayabusa 2 orbiter thermal mapper, which uses a wavelength range of 8-12 μm. The primary science objective of the MARA instrument it the determination of the target asteroid's surface brightness temperature, from which surface thermal inertia can be derived. In addition, the spectral bandpass channels will be used to estimate the spectral slope of the surface in the thermal infrared wavelength range. The instrument has been calibrated using a cavity blackbody, and the temperature uncertainty is 1 K in the long pass channel for target temperatures of >173 K. Measurement uncertainty in the spectral bandpasses is 1 K for target temperatures above 273 K.

  18. Toward more accurate loss tangent measurements in reentrant cavities

    SciTech Connect

    Moyer, R. D.

    1980-05-01

    Karpova has described an absolute method for measurement of dielectric properties of a solid in a coaxial reentrant cavity. His cavity resonance equation yields very accurate results for dielectric constants. However, he presented only approximate expressions for the loss tangent. This report presents more exact expressions for that quantity and summarizes some experimental results.

  19. Absolute neutrino mass measurements

    SciTech Connect

    Wolf, Joachim

    2011-10-06

    The neutrino mass plays an important role in particle physics, astrophysics and cosmology. In recent years the detection of neutrino flavour oscillations proved that neutrinos carry mass. However, oscillation experiments are only sensitive to the mass-squared difference of the mass eigenvalues. In contrast to cosmological observations and neutrino-less double beta decay (0v2{beta}) searches, single {beta}-decay experiments provide a direct, model-independent way to determine the absolute neutrino mass by measuring the energy spectrum of decay electrons at the endpoint region with high accuracy.Currently the best kinematic upper limits on the neutrino mass of 2.2eV have been set by two experiments in Mainz and Troitsk, using tritium as beta emitter. The next generation tritium {beta}-experiment KATRIN is currently under construction in Karlsruhe/Germany by an international collaboration. KATRIN intends to improve the sensitivity by one order of magnitude to 0.2eV. The investigation of a second isotope ({sup 137}Rh) is being pursued by the international MARE collaboration using micro-calorimeters to measure the beta spectrum. The technology needed to reach 0.2eV sensitivity is still in the R and D phase. This paper reviews the present status of neutrino-mass measurements with cosmological data, 0v2{beta} decay and single {beta}-decay.

  20. The Absolute Radiometric Calibration of Space - Sensors.

    NASA Astrophysics Data System (ADS)

    Holm, Ronald Gene

    1987-09-01

    The need for absolute radiometric calibration of space-based sensors will continue to increase as new generations of space sensors are developed. A reflectance -based in-flight calibration procedure is used to determine the radiance reaching the entrance pupil of the sensor. This procedure uses ground-based measurements coupled with a radiative transfer code to characterize the effects the atmosphere has on the signal reaching the sensor. The computed radiance is compared to the digital count output of the sensor associated with the image of a test site. This provides an update to the preflight calibration of the system and a check on the on-board internal calibrator. This calibration procedure was used to perform a series of five calibrations of the Landsat-5 Thematic Mapper (TM). For the 12 measurements made in TM bands 1-3, the RMS variation from the mean as a percentage of the mean is (+OR-) 1.9%, and for measurements in the IR, TM bands 4,5, and 7, the value is (+OR-) 3.4%. The RMS variation for all 23 measurements is (+OR-) 2.8%. The absolute calibration techniques were put to another test with a series of three calibration of the SPOT-1 High Resolution Visible, (HRV), sensors. The ratio, HRV-2/HRV-1, of absolute calibration coefficients compared very well with ratios of histogrammed data obtained when the cameras simultaneously imaged the same ground site. Bands PA, B1 and B3 agreed to within 3%, while band B2 showed a 7% difference. The procedure for performing a satellite calibration was then used to demonstrate how a calibrated satellite sensor can be used to quantitatively evaluate surface reflectance over a wide range of surface features. Predicted reflectance factors were compared to values obtained from aircraft -based radiometer data. This procedure was applied on four dates with two different surface conditions per date. A strong correlation, R('2) = .996, was shown between reflectance values determined from satellite imagery and low-flying aircraft

  1. Cavity magnomechanics

    NASA Astrophysics Data System (ADS)

    Zou, Chang-Ling; Zhang, Xufeng; Jiang, Liang; Tang, Hong

    2016-05-01

    Recently, cavity magnonics has attracted much attention for potential applications of coherent information transduction and hybrid quantum devices. The magnon is a collective spin wave excitation in ferromagnetic material. It is magnetically tunability, with long coherence time and non-reciprocical interaction with electro-magnetic fields. We report the coherent coupling between magnon, microwave photon and phonon. First, we demonstrate strong coupling and ultrastrong coupling between the magnon in YIG sphere and microwave photon in three-dimensional cavity. Then, based on the hybridized magnon-photon modes, we observe the triply resonant magnon-mcirowave photon-phonon coupling, where the ultrahigh-Q mechanical vibration of YIG sphere is dispersively coupled with the magnon via magnetostrictive interaction. We observe interesting phenomena, including electromagnetically induced transparency/absorption and parametric amplification. In particular, benefit from the large tunability of the magnon, we demonstrate a tunable microwave amplifier with gain as high as 30 dB. The single crystal YIG also has excellent optical properties, and thus provide a unique platform bridging MHz, GHz and THz information carriers. Finally, we present the latest progress towards coherent magnon to optical photon conversion.

  2. Preliminary development of digital signal processing in microwave radiometers

    NASA Technical Reports Server (NTRS)

    Stanley, W. D.

    1980-01-01

    Topics covered involve a number of closely related tasks including: the development of several control loop and dynamic noise model computer programs for simulating microwave radiometer measurements; computer modeling of an existing stepped frequency radiometer in an effort to determine its optimum operational characteristics; investigation of the classical second order analog control loop to determine its ability to reduce the estimation error in a microwave radiometer; investigation of several digital signal processing unit designs; initiation of efforts to develop required hardware and software for implementation of the digital signal processing unit; and investigation of the general characteristics and peculiarities of digital processing noiselike microwave radiometer signals.

  3. Ultra Stable Microwave Radiometers for Future Sea Surface Salinity Missions

    NASA Technical Reports Server (NTRS)

    Wilson, William J.; Tanner, Alan B.; Pellerano, Fernando A.; Horgan, Kevin A.

    2005-01-01

    The NASA Earth Science System Pathfinder (ESSP) mission Aquarius will measure global sea surface salinity with 100-km spatial resolution every 8 days with an average monthly salinity accuracy of 0.2 psu (parts per thousand). This requires an L-band low-noise radiometer with the long-term calibration stability of less than 0.1 K over 8 days. This three-year research program on ultra stable radiometers has addressed the radiometer requirements and configuration necessary to achieve this objective for Aquarius and future ocean salinity missions. The system configuration and component performance have been evaluated with radiometer testbeds at both JPL and GSFC. The research has addressed several areas including component characterization as a function of temperature, a procedure for the measurement and correction for radiometer system non-linearity, noise diode calibration versus temperature, low noise amplifier performance over voltage, and temperature control requirements to achieve the required stability. A breadboard radiometer, utilizing microstrip-based technologies, has been built to demonstrate this long-term stability. This report also presents the results of the radiometer test program, a detailed radiometer noise model, and details of the operational switching sequence optimization that can be used to achieve the low noise and stability requirements. Many of the results of this research have been incorporated into the Aquarius radiometer design and will allow this instrument to achieve its goals.

  4. PV-MCT working standard radiometer

    NASA Astrophysics Data System (ADS)

    Eppeldauer, George P.; Podobedov, V. B.

    2012-06-01

    Sensitive infrared working-standard detectors with large active area are needed to extend the signal dynamic range of the National Institute of Standards and Technology (NIST) pyroelectric transfer-standards used for infrared spectral power responsivity calibrations. Increased sensitivity is especially important for irradiance mode responsivity measurements. The noise equivalent power (NEP) of the NIST used pyroelectric transfer-standards is about 8 nW/Hz1/2, equal to a D*= 5.5 x 107 cm Hz1/2/W. A large-area photovoltaic HgCdTe (PV-MCT) detector was custom made for the 2.5 μm to 11 μm wavelength range using a 4-stage thermoelectric cooler. At least an order of magnitude lower NEP was expected than that of the pyroelectric transfer-standards to measure irradiance. The large detector area was produced with multiple p-n junctions. The periodical, multiple-junction structure produced a spatial non-uniformity in the detector response. The PV-MCT radiometer was characterized for spatial non-uniformity of response using different incident beam sizes to evaluate the uncertainty component caused by the spatial non-uniformity. The output voltage noise and also the current and voltage responsivities were evaluated at different signal gains and frequencies. The output voltage noise was decreased and the voltage responsivity was increased to lower the NEP of the radiometer. The uncertainty of the spectral power responsivity measurements was evaluated. It is recommended to use a bootstrap type trans-impedance amplifier along with a cold field-of-view limiter to improve the NEP of the PV-MCT radiometer.

  5. Resolution Enhancement of Spaceborne Radiometer Images

    NASA Technical Reports Server (NTRS)

    Krim, Hamid

    2001-01-01

    Our progress over the last year has been along several dimensions: 1. Exploration and understanding of Earth Observatory System (EOS) mission with available data from NASA. 2. Comprehensive review of state of the art techniques and uncovering of limitations to be investigated (e.g. computational, algorithmic ...). and 3. Preliminary development of resolution enhancement algorithms. With the advent of well-collaborated satellite microwave radiometers, it is now possible to obtain long time series of geophysical parameters that are important for studying the global hydrologic cycle and earth radiation budget. Over the world's ocean, these radiometers simultaneously measure profiles of air temperature and the three phases of atmospheric water (vapor, liquid, and ice). In addition, surface parameters such as the near surface wind speed, the sea surface temperature, and the sea ice type and concentration can be retrieved. The special sensor microwaves imager SSM/I has wide application in atmospheric remote sensing over the ocean and provide essential inputs to numerical weather-prediction models. SSM/I data has also been used for land and ice studies, including snow cover classification measurements of soil and plant moisture contents, atmospheric moisture over land, land surface temperature and mapping polar ice. The brightness temperature observed by SSM/I is function of the effective brightness temperature of the earth's surface and the emission scattering and attenuation of the atmosphere. Advanced Microwave Scanning Radiometer (AMSR) is a new instrument that will measure the earth radiation over the spectral range from 7 to 90 GHz. Over the world's ocean, it will be possible to retrieve the four important geographical parameters SST, wind speed, vertically integrated water vapor, vertically integrated cloud liquid water L.

  6. Absolute Identification by Relative Judgment

    ERIC Educational Resources Information Center

    Stewart, Neil; Brown, Gordon D. A.; Chater, Nick

    2005-01-01

    In unidimensional absolute identification tasks, participants identify stimuli that vary along a single dimension. Performance is surprisingly poor compared with discrimination of the same stimuli. Existing models assume that identification is achieved using long-term representations of absolute magnitudes. The authors propose an alternative…

  7. Be Resolute about Absolute Value

    ERIC Educational Resources Information Center

    Kidd, Margaret L.

    2007-01-01

    This article explores how conceptualization of absolute value can start long before it is introduced. The manner in which absolute value is introduced to students in middle school has far-reaching consequences for their future mathematical understanding. It begins to lay the foundation for students' understanding of algebra, which can change…

  8. RF Reference Switch for Spaceflight Radiometer Calibration

    NASA Technical Reports Server (NTRS)

    Knuble, Joseph

    2013-01-01

    The goal of this technology is to provide improved calibration and measurement sensitivity to the Soil Moisture Active Passive Mission (SMAP) radiometer. While RF switches have been used in the past to calibrate microwave radiometers, the switch used on SMAP employs several techniques uniquely tailored to the instrument requirements and passive remote-sensing in general to improve radiometer performance. Measurement error and sensitivity are improved by employing techniques to reduce thermal gradients within the device, reduce insertion loss during antenna observations, increase insertion loss temporal stability, and increase rejection of radar and RFI (radio-frequency interference) signals during calibration. The two legs of the single-pole double-throw reference switch employ three PIN diodes per leg in a parallel-shunt configuration to minimize insertion loss and increase stability while exceeding rejection requirements at 1,413 MHz. The high-speed packaged diodes are selected to minimize junction capacitance and resistance while ensuring the parallel devices have very similar I-V curves. Switch rejection is improved by adding high-impedance quarter-wave tapers before and after the diodes, along with replacing the ground via of one diode per leg with an open circuit stub. Errors due to thermal gradients in the switch are reduced by embedding the 50-ohm reference load within the switch, along with using a 0.25-in. (approximately equal to 0.6-cm) aluminum prebacked substrate. Previous spaceflight microwave radiometers did not embed the reference load and thermocouple directly within the calibration switch. In doing so, the SMAP switch reduces error caused by thermal gradients between the load and switch. Thermal issues are further reduced by moving the custom, highspeed regulated driver circuit to a physically separate PWB (printed wiring board). Regarding RF performance, previous spaceflight reference switches have not employed high-impedance tapers to improve

  9. The Millimeter-Wave Imaging Radiometer (MIR)

    NASA Technical Reports Server (NTRS)

    Gasiewski, A. J.; Jackson, D. M.; Adler, R. F.; Dod, L. R.; Shiue, J. C.

    1991-01-01

    The Millimeter-Wave Imaging Radiometer (MIR) is a new instrument being designed for studies of airborne passive microwave retrieval of tropospheric water vapor, clouds, and precipitation parameters. The MIR is a total-power cross-track scanning radiometer for use on either the NASA ER-2 (high-altitude) or DC-8 (medium altitude) aircraft. The current design includes millimeter-wave (MMW) channels at 90, 166, 183 +/- 1,3,7, and 220 GHz. An upgrade for the addition of submillimeter-wave (SMMW) channels at 325 +/- 1,3,7 and 340 GHz is planned. The nadiral spatial resolution is approximately 700 meters at mid-altitude when operated aboard the NASA ER-2. The MIR consists of a scanhead and data acquisition system, designed for installation in the ER-2 superpod nose cone. The scanhead will house the receivers (feedhorns, mixers, local oscillators, and preamplifiers), a scanning mirror, hot and cold calibration loads, and temperature sensors. Particular attention is being given to the characterization of the hot and cold calibration loads through both laboratory bistatic scattering measurements and analytical modeling. Other aspects of the MIR and the data acquisition system are briefly discussed, and diagrams of the location of the MIR in the ER-2 superpod nosecone and of the data acquisition system are presented.

  10. ERBE and CERES broadband scanning radiometers

    NASA Technical Reports Server (NTRS)

    Weaver, William L.; Cooper, John E.

    1990-01-01

    Broadband scanning radiometers have been used extensively on earth-orbiting satellites to measure the Earth's outgoing radiation. The resulting estimates of longwave and shortwave fluxes have played an important role in helping to understand the Earth's radiant energy balance or budget. The Clouds and the Earth Radiant Energy System (CERES) experiment is expected to include instruments with three broadband scanning radiometers. The design of the CERES instrument will draw heavily from the flight-proven Earth Radiation Budget Experiment (ERBE) scanner instrument technology and will benefit from the several years of ERBE experience in mission operations and data processing. The discussion starts with a description of the scientific objectives of ERBE and CERES. The design and operational characteristics of the ERBE and CERES instrument are compared and the two ground-based data processing systems are compared. Finally, aspects of the CERES data processing which might be performed in near real-time aboard a spacecraft platform are discussed, and the types of algorithms and input data requirements for the onboard processing system are identified.

  11. Microfluidic Radiometal Labeling Systems for Biomolecules

    SciTech Connect

    Reichert, D E; Kenis, P J. A.

    2011-12-29

    In a typical labeling procedure with radiometals, such as Cu-64 and Ga-68; a very large (~ 100-fold) excess of the non-radioactive reactant (precursor) is used to promote rapid and efficient incorporation of the radioisotope into the PET imaging agent. In order to achieve high specific activities, careful control of reaction conditions and extensive chromatographic purifications are required in order to separate the labeled compounds from the cold precursors. Here we propose a microfluidic approach to overcome these problems, and achieve high specific activities in a more convenient, semi-automated fashion and faster time frame. Microfluidic reactors, consisting of a network of micron-sized channels (typical dimensions in the range 10 - 300¼m), filters, separation columns, electrodes and reaction loops/chambers etched onto a solid substrate, are now emerging as an extremely useful technology for the intensification and miniaturization of chemical processes. The ability to manipulate, process and analyze reagent concentrations and reaction interfaces in both space and time within the channel network of a microreactor provides the fine level of reaction control that is desirable in PET radiochemistry practice. These factors can bring radiometal labeling, specifically the preparation of radio-labeled biomolecules such as antibodies, much closer to their theoretical maximum specific activities.

  12. Conceptual radiometer design studies for Earth observations from low Earth orbit

    NASA Technical Reports Server (NTRS)

    Harrington, Richard F.

    1994-01-01

    A conceptual radiometer design study was performed to determine the optimum design approach for spaceborne radiometers in low Earth orbit. Radiometric system configurations which included total power radiometers, unbalanced Dicke radiometers, and balanced Dicke, or as known as noise injection, radiometers were studied. Radiometer receiver configurations which were analyzed included the direct detection radiometer receiver, the double sideband homodyne radiometer receiver, and the single sideband heterodyne radiometer receiver. Radiometer system performance was also studied. This included radiometric sensitivity analysis of the three different radiometer system configurations studied. Both external and internal calibration techniques were analyzed. An accuracy analysis with and without mismatch losses was performed. It was determined that the balanced Dicke radiometer system configuration with direct detection receivers and external calibrations was optimum where frequent calibration such as once per minute were not feasible.

  13. Monochromator-Based Absolute Calibration of a Standard Radiation Thermometer

    NASA Astrophysics Data System (ADS)

    Mantilla, J. M.; Hernanz, M. L.; Campos, J.; Martín, M. J.; Pons, A.; del Campo, D.

    2014-04-01

    Centro Español de Metrología (CEM) is disseminating the International Temperature Scale (ITS-90), at high temperatures, by using the fixed points of Ag and Cu and a standard radiation thermometer. However, the future mise-en-pratique for the definition of the kelvin ( MeP-K) will include the dissemination of the kelvin by primary methods and by indirect approximations capable of exceptionally low uncertainties or increased reliability. Primary radiometry is, at present, able to achieve uncertainties competitive with the ITS-90 above the silver point with one of the possible techniques the calibration for radiance responsivity of an imaging radiometer (radiance method). In order to carry out this calibration, IO-CSIC (Spanish Designated Institute for luminous intensity and luminous flux) has collaborated with CEM, allowing traceability to its cryogenic radiometer. A monochromator integrating sphere-based spectral comparator facility has been used to calibrate one of the CEM standard radiation thermometers. The absolute calibrated standard radiation thermometer has been used to determine the temperatures of the fixed points of Cu, Co-C, Pt-C, and Re-C. The results obtained are 1357.80 K, 1597.10 K, 2011.66 K, and 2747.64 K, respectively, with uncertainties ranging from 0.4 K to 1.1 K.

  14. The DC-8 Submillimeter-Wave Cloud Ice Radiometer

    NASA Technical Reports Server (NTRS)

    Walter, Steven J.; Batelaan, Paul; Siegel, Peter; Evans, K. Franklin; Evans, Aaron; Balachandra, Balu; Gannon, Jade; Guldalian, John; Raz, Guy; Shea, James

    2000-01-01

    An airborne radiometer is being developed to demonstrate the capability of radiometry at submillimeter-wavelengths to characterize cirrus clouds. At these wavelengths, cirrus clouds scatter upwelling radiation from water vapor in the lower troposphere. Radiometric measurements made at multiple widely spaced frequencies permit flux variations caused by changes in scattering due to crystal size to be distinguished from changes in cloud ice content. Measurements at dual polarizations can also be used to constrain the mean crystal shape. An airborne radiometer measuring the upwelling submillimeter-wave flux should then able to retrieve both bulk and microphysical cloud properties. The radiometer is being designed to make measurements at four frequencies (183 GHz, 325 GHz, 448 GHz, and 643 GHz) with dual-polarization capability at 643 GHz. The instrument is being developed for flight on NASA's DC-8 and will scan cross-track through an aircraft window. Measurements with this radiometer in combination with independent ground-based and airborne measurements will validate the submillimeter-wave radiometer retrieval techniques. The goal of this effort is to develop a technique to enable spaceborne characterization of cirrus, which will meet a key climate measurement need. The development of an airborne radiometer to validate cirrus retrieval techniques is a critical step toward development of spaced-based radiometers to investigate and monitor cirrus on a global scale. The radiometer development is a cooperative effort of the University of Colorado, Colorado State University, Swales Aerospace, and Jet Propulsion Laboratory and is funded by the NASA Instrument Incubator Program.

  15. Non-Scanning Radiometer Results for Earth Radiation Budget Investigations

    NASA Technical Reports Server (NTRS)

    Smith, G. Louis; Green, Richard N.; Lee, Robert B., III; Bess, T. Dale; Rutan, David

    1992-01-01

    The Earth Radiation Budget Experiment (ERBE) included non-scanning radiometers (Luther, 1986) flown aboard a dedicated mission of Earth Radiation Budget Satellite, and the NOAA-9 and -10 operational meteorological spacecraft (Barkstrom and Smith, 1986). The radiometers first began providing Earth radiation budget data in November 1984 and have remained operational, providing a record of nearly 8 years of data to date for researchers. Although they do not produce measurements with the resolution given by the scanning radiometers, the results from the non-scanning radiometers are extremely useful for climate research involving long-term radiation data sets. This paper discusses the non-scanning radiometers, their stability, the method of analyzing the data, and brief scientific results from the data.

  16. Large Antenna Multifrequency Microwave Radiometer (LAMMR) system design

    NASA Technical Reports Server (NTRS)

    King, J. L.

    1980-01-01

    The large Antenna Multifrequency Microwave Radiometer (LAMMR) is a high resolution 4 meter aperture scanning radiometer system designed to determine sea surface temperature and wind speed, atmospheric water vapor and liquid water, precipitation, and various sea ice parameters by interpreting brightness temperature images from low Earth orbiting satellites. The LAMMR with dual linear horizontal and vertical polarization radiometer channels from 1.4 to 91 GHZ can provide multidiscipline data with resolutions from 105 to 7 km. The LAMMR baseline radiometer system uses total power radiometers to achieve delta T's in the 0.5 to 1.7 K range and system calibration accuracies in the 1 to 2 deg range. A cold sky horn/ambient load two point calibration technique is used in this baseline concept and the second detector output uses an integrated and dump circuit to sample the scanning cross-tract resolution cells.

  17. MCM Polarimetric Radiometers for Planar Arrays

    NASA Technical Reports Server (NTRS)

    Kangaslahti, Pekka; Dawson, Douglas; Gaier, Todd

    2007-01-01

    A polarimetric radiometer that operates at a frequency of 40 GHz has been designed and built as a prototype of multiple identical units that could be arranged in a planar array for scientific measurements. Such an array is planned for use in studying the cosmic microwave background (CMB). All of the subsystems and components of this polarimetric radiometer are integrated into a single multi-chip module (MCM) of substantially planar geometry. In comparison with traditional designs of polarimetric radiometers, the MCM design is expected to greatly reduce the cost per unit in an array of many such units. The design of the unit is dictated partly by a requirement, in the planned CMB application, to measure the Stokes parameters I, Q, and U of the CMB radiation with high sensitivity. (A complete definition of the Stokes parameters would exceed the scope of this article. In necessarily oversimplified terms, I is a measure of total intensity of radiation, while Q and U are measures of the relationships between the horizontally and vertically polarized components of radiation.) Because the sensitivity of a single polarimeter cannot be increased significantly, the only way to satisfy the high-sensitivity requirement is to make a large array of polarimeters that operate in parallel. The MCM includes contact pins that can be plugged into receptacles on a standard printed-circuit board (PCB). All of the required microwave functionality is implemented within the MCM; any required supporting non-microwave ("back-end") electronic functionality, including the provision of DC bias and control signals, can be implemented by standard PCB techniques. On the way from a microwave antenna to the MCM, the incoming microwave signal passes through an orthomode transducer (OMT), which splits the radiation into an h + i(nu) beam and an h - i(nu) beam (where, using complex-number notation, h denotes the horizontal component, nu denotes the vertical component, and +/-i denotes a +/-90deg phase

  18. Singular perturbation of absolute stability.

    NASA Technical Reports Server (NTRS)

    Siljak, D. D.

    1972-01-01

    It was previously shown (author, 1969) that the regions of absolute stability in the parameter space can be determined when the parameters appear on the right-hand side of the system equations, i.e., the regular case. Here, the effect on absolute stability of a small parameter attached to higher derivatives in the equations (the singular case) is studied. The Lur'e-Postnikov class of nonlinear systems is considered.

  19. Solid-state spectral transmissometer and radiometer

    NASA Technical Reports Server (NTRS)

    Carder, K. L.; Steward, R. G.; Payne, P. R.

    1985-01-01

    An in situ instrument designed to measure the spectral attenuation coefficient of seawater and the ocean remote-sensing reflectance from 400 to 750 nm is in the test and development stage. It employs a 256 channel, charge-coupled type of linear array measuring the spectral intensities diffracted by a grating. Examples of the types of data delivered by this instrument have been simulated using a breadboard laboratory instrument and an above-water, solid-state radiometer. Algorithms developed using data from these instruments provide measures of chlorophyll a plus phaeophytin a concentrations from less than 0.1 to 77.0 mg/cu m, gelbstoff spectral absorption coefficients, and detrital spectral backscattering coefficients for waters of the west Florida shelf.

  20. Ozone height profiles using laser heterodyne radiometer

    NASA Technical Reports Server (NTRS)

    Jain, S. L.

    1994-01-01

    The monitoring of vertical profiles of ozone and related minor constituents in the atmosphere are of great significance to understanding the complex interaction between atmospheric dynamics, chemistry and radiation budget. An ultra high spectral resolution tunable CO2 laser heterodyne radiometer has been designed, developed and set up at the National Physical Laboratory, New Delhi to obtain vertical profiles of various minor constituents the characteristic absorption lines in 9 to 11 micron spectral range. Due to its high spectral resolution the lines can be resolved completely and data obtained are inverted to get vertical profiles using an inversion technique developed by the author. In the present communication the salient features of the laser heterodyne system and the results obtained are discussed in detail.

  1. Radiometals as payloads for radioimmunotherapy for lymphoma.

    PubMed

    DeNardo, Gerald L; Kennel, Stephen J; Siegel, Jeffry A; Denardo, Sally J

    2004-10-01

    Because of their remarkable effectiveness in radioimmunotherapy (RIT), 2 anti-CD20 monoclonal antibody (MAb) drugs, one labeled with indium 111 for imaging or yttrium 90 for therapy, and another labeled with iodine I 131 for imaging and therapy, have been approved for use in patients with non-Hodgkin's lymphoma (NHL). Successful RIT for lymphomas is due in large part to the rapid and efficient binding of the targeted MAb to lymphoma cells. Carcinomas are more difficult to access, necessitating novel strategies matched with radionuclides with specific physical properties. Because there are many radionuclides from which to choose, a systematic approach is required to select those preferred for a specific application. Thus far, radionuclides with g emissions for imaging and particulate emissions for therapy have been investigated. Radionuclides of iodine were the first to be used for RIT. Many conventionally radioiodinated MAbs are degraded after endocytosis by target cells, releasing radioiodinated peptides and amino acids. In contrast, radiometals have been shown to have residualizing properties, advantageous when the MAb is localized in malignant tissue. b-emitting lanthanides like those of 90Y, lutetium 177, etc. have attractive combinations of biologic, physical, radiochemical, production, economic, and radiation safety characteristics. Other radiometals, such as copper-67 and copper-64, are also of interest. a-emitters, including actinium-225 and bismuth-213, have been used for therapy in selected applications. Evidence for the impact of the radionuclide is provided by data from the randomized pivotal phase III trial of 90Y ibritumomab tiuxetan (Zevalin) in patients with NHL; responses were about 2 times greater in the 90Y ibritumomab tiuxetan arm than in the rituximab arm. It is clear that RIT has emerged as a safe and efficient method for treatment of NHL, especially in specific settings. PMID:15498149

  2. Dual frequency optical cavity

    DOEpatents

    George, E.V.; Schipper, J.F.

    Method and apparatus for generating two distinct laser frequencies in an optical cavity, using a T configuration laser cavity and means for intermittently increasing or decreasing the index of refraction n of an associated transmission medium in one arm of the optical cavity to enhance laser action in one arm or the second arm of the cavity.

  3. Dual frequency optical cavity

    DOEpatents

    George, E. Victor; Schipper, John F.

    1985-01-01

    Method and apparatus for generating two distinct laser frequencies in an optical cavity, using a "T" configuration laser cavity and means for intermittently increasing or decreasing the index of refraction n of an associated transmission medium in one arm of the optical cavity to enhance laser action in one arm or the second arm of the cavity.

  4. The Hurricane Imaging Radiometer (HIRAD): Instrument Status and Performance Predictions

    NASA Technical Reports Server (NTRS)

    Ruf, Christopher; Bailey, M. C.; Gross, Steven; Hood, Robbie; James, Mark; Johnson, James; Jones, Linwood; Miller, Timothy; Uhlhorn, Eric

    2009-01-01

    The Hurricane Imaging Radiometer (HIRAD) is an innovative radiometer which offers new and unique remotely sensed observations of both extreme oceanic wind events and strong precipitation. It is based on the airborne Stepped Frequency Microwave Radiometer (SFMR) [Uhlhorn and Black, 2004]. The HIRAD instrument advances beyond the current nadir viewing SFMR to an equivalent wide-swath SFMR imager using passive microwave synthetic thinned aperture radiometer (STAR) technology [Ruf et al., 1988]. This sensor operates over 4-7 GHz, where the required tropical cyclone remote sensing physics has been validated by both SFMR and WindSat radiometer [Bettenhausen et al., 2006; Brown et al., 2006]. HIRAD incorporates a new and unique array antenna design along with several technologies successfully demonstrated by the Lightweight Rain Radiometer instrument [Ruf et al., 2002; Ruf and Principe, 2003]. HIRAD will be a compact, lightweight, low-power instrument with no moving parts that will produce wide-swath imagery of ocean winds and rain in hurricane conditions. Accurate observations of surface ocean vector winds (OVW) with high spatial and temporal resolution are required for understanding and predicting tropical cyclones. The Hurricane Imaging Radiometer (HIRAD) is an innovative architecture which offers new and unique remotely sensed observations of both extreme oceanic wind events and strong precipitation. It is based on the airborne Stepped Frequency Microwave Radiometer (SFMR), which is a proven remote sensing technique for observing tropical cyclone (TC) ocean surface wind speeds and rain rates. The proposed HIRAD instrument advances beyond the current nadir viewing SFMR to an equivalent wide-swath SFMR imager using passive microwave synthetic thinned aperture radiometer (STAR) technology combined with a a unique array antenna design. The overarching design concept of HIRAD is to combine the multi-frequency C-band observing strategy of the SFMR with STAR technology to

  5. Measuring Earth Radiation Imbalance from a Massive Constellation of Flux Radiometers

    NASA Astrophysics Data System (ADS)

    Wiscombe, W. J.; Chiu, J.; Ardanuy, P. E.; Barker, H.; Han, S.; Lorentz, S. R.; Schwartz, S. E.; Trenberth, K. E.

    2012-12-01

    The most important climate variable that is not now measured from space with sufficient accuracy (not even one significant digit on any time scale) is Earth Radiation Imbalance (ERI), a subject of much discussion lately in relation to the "global warming hiatus". The greatest temporal challenges for ERI measurements are very long (decadal) and very short (diurnal) time scales. The decadal challenge is mainly one of calibration and continuity, whereas the diurnal challenge is mainly one of temporal coverage. ERI measurements must meet both challenges. We discuss here a massive constellation of flux radiometers in Low Earth Orbit that is capable of meeting both challenges. At least 30-40 satellites are required for diurnal coverage, an order of magnitude more than in any previous Earth science mission. This same diurnal coverage would make possible, for the first time, the use of ERI measurements in data assimilation, as well as providing a much more temporally resolved dataset for tuning and evaluating climate models. Although a large number of instruments on many satellites might seem to pose a gargantuan calibration challenge, actually, the more satellites, the better the intercalibration: satellites can not only follow each other closely in the same orbit plane, viewing exactly the same scene a few minutes apart, but they can engage in a spider web of crossovers in the polar regions, allowing many further such intercalibrations. Furthermore, keystone satellites can roll over to obtain an absolute calibration from the Sun and deep space, which can then be transferred to the other satellites. Simulations of ERI from such a constellation will be shown, along with the tradeoffs necessary to create an optimal configuration and to mitigate the problems experienced by previous generations of Earth radiation budget radiometers. A tentative instrument design will also be described.Constellation of flux radiometers for measuring Earth Radiation Imbalance

  6. Infrared radiometer for measuring thermophysical properties of wind tunnel models

    NASA Technical Reports Server (NTRS)

    Corwin, R. R.; Moorman, S. L.; Becker, E. C.

    1978-01-01

    An infrared radiometer is described which was developed to measure temperature rises of wind tunnel models undergoing transient heating over a temperature range of -17.8 C to 260 C. This radiometer interfaces directly with a system which measures the effective thermophysical property square root of rho ck. It has an output temperature fluctuation of 0.26 C at low temperatures and 0.07 C at high temperatures, and the output frequency response of the radiometer is from dc to 400 hertz.

  7. Aerosol physical properties in the stratosphere (APPS) radiometer design

    NASA Technical Reports Server (NTRS)

    Gray, C. R.; Woodin, E. A.; Anderson, T. J.; Magee, R. J.; Karthas, G. W.

    1977-01-01

    The measurement concepts and radiometer design developed to obtain earth-limb spectral radiance measurements for the Aerosol Physical Properties in the Stratosphere (APPS) measurement program are presented. The measurements made by a radiometer of this design can be inverted to yield vertical profiles of Rayleigh scatterers, ozone, nitrogen dioxide, aerosol extinction, and aerosol physical properties, including a Junge size-distribution parameter, and a real and imaginary index of refraction. The radiometer design provides the capacity for remote sensing of stratospheric constituents from space on platforms such as the space shuttle and satellites, and therefore provides for global measurements on a daily basis.

  8. Absolute flux scale for radioastronomy

    SciTech Connect

    Ivanov, V.P.; Stankevich, K.S.

    1986-07-01

    The authors propose and provide support for a new absolute flux scale for radio astronomy, which is not encumbered with the inadequacies of the previous scales. In constructing it the method of relative spectra was used (a powerful tool for choosing reference spectra). A review is given of previous flux scales. The authors compare the AIS scale with the scale they propose. Both scales are based on absolute measurements by the ''artificial moon'' method, and they are practically coincident in the range from 0.96 to 6 GHz. At frequencies above 6 GHz, 0.96 GHz, the AIS scale is overestimated because of incorrect extrapolation of the spectra of the primary and secondary standards. The major results which have emerged from this review of absolute scales in radio astronomy are summarized.

  9. Two-Dimensional Synthetic-Aperture Radiometer

    NASA Technical Reports Server (NTRS)

    LeVine, David M.

    2010-01-01

    A two-dimensional synthetic-aperture radiometer, now undergoing development, serves as a test bed for demonstrating the potential of aperture synthesis for remote sensing of the Earth, particularly for measuring spatial distributions of soil moisture and ocean-surface salinity. The goal is to use the technology for remote sensing aboard a spacecraft in orbit, but the basic principles of design and operation are applicable to remote sensing from aboard an aircraft, and the prototype of the system under development is designed for operation aboard an aircraft. In aperture synthesis, one utilizes several small antennas in combination with a signal processing in order to obtain resolution that otherwise would require the use of an antenna with a larger aperture (and, hence, potentially more difficult to deploy in space). The principle upon which this system is based is similar to that of Earth-rotation aperture synthesis employed in radio astronomy. In this technology the coherent products (correlations) of signals from pairs of antennas are obtained at different antenna-pair spacings (baselines). The correlation for each baseline yields a sample point in a Fourier transform of the brightness-temperature map of the scene. An image of the scene itself is then reconstructed by inverting the sampled transform. The predecessor of the present two-dimensional synthetic-aperture radiometer is a one-dimensional one, named the Electrically Scanned Thinned Array Radiometer (ESTAR). Operating in the L band, the ESTAR employs aperture synthesis in the cross-track dimension only, while using a conventional antenna for resolution in the along-track dimension. The two-dimensional instrument also operates in the L band to be precise, at a frequency of 1.413 GHz in the frequency band restricted for passive use (no transmission) only. The L band was chosen because (1) the L band represents the long-wavelength end of the remote- sensing spectrum, where the problem of achieving adequate

  10. Reflectance of Antarctic surfaces from multispectral radiometers: The correction of atmospheric effects

    SciTech Connect

    Zibordi, G. ); Maracci, G. )

    1993-01-01

    Monitoring reflectance of polar icecaps has relevance in climate studies. In fact, climate changes produce variations in the morphology of ice and snow covers, which are detectable as surface reflectance change. Surface reflectance can be retrieved from remotely sensed data. However, absolute values independent of atmospheric turbidity and surface altitude can only be obtained after removing masking effects of the atmosphere. An atmospheric correction model, accounting for surface and sensor altitudes above sea level, is described and validated through data detected over Antarctic surfaces with a Barnes Modular Multispectral Radiometer having bands overlapping those of the Landsat Thematic Mapper. The model is also applied in a sensitivity analysis to investigate error induced in reflectance obtained from satellite data by indeterminacy in optical parameters of atmospheric constituents. Results show that indeterminacy in the atmospheric water vapor optical thickness is the main source of nonaccuracy in the retrieval of surface reflectance from data remotely sensed over Antarctic regions.

  11. Blackbody Cavity for Calibrations at 200 to 273 K

    NASA Technical Reports Server (NTRS)

    Howell, Dane; Ryan, Robert; Ryan, Jim; Henderson, Doug; Clayton, Larry

    2007-01-01

    A laboratory blackbody cavity has been designed and built for calibrating infrared radiometers used to measure radiant temperatures in the range from about 200 to about 273 K. In this below-room-temperature range, scattering of background infrared radiation from room-temperature surfaces could, potentially, contribute significantly to the spectral radiance of the blackbody cavity, thereby contributing a significant error to the radiant temperature used as the calibration value. The present blackbody cavity is of an established type in which multiple reflections from a combination of conical and cylindrical black-coated walls are exploited to obtain an effective emissivity greater than the emissivity value of the coating material on a flat exposed surface.

  12. Zone radiometer measurements on a model rocket exhaust plume

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Radiometer for analytical prediction of rocket plume-to-booster thermal radiation and convective heating is described. Applications for engine combustion analysis, incineration, and pollution control by high temperature processing are discussed. Illustrations of equipment are included.

  13. Use of cold radiometers in several thermal/vacuum tests

    NASA Astrophysics Data System (ADS)

    DiPirro, Michael; Tuttle, J.; Canavan, Edgar R.; Shirron, Peter John

    2012-06-01

    A low cost low temperature broadband radiometer has been developed for use with low temperature tests as a diagnostic tool for measuring stray thermal radiation and remote measurement of material properties. So far these radiometers have been used in three large thermal/vacuum tests for the James Webb Space Telescope (JWST) Project. In the first two tests the radiometers measured stray radiation in a test of part of the JWST sunshield, and in the third test the radiometers were used to measure the reflectivity and specularity of black ChemglazeTM Z307 painted aluminum walls on a 25 K cooled shroud. This paper will present the results of the reflectivity/specularity tests.

  14. Submillimeter-Wave Radiometer Technology for Earth Remote Sensing Applications

    NASA Technical Reports Server (NTRS)

    Siegel, P.

    2000-01-01

    Recent innovations in ultra-high frequency, semiconductor device/component technology have enabled both traditional and new applications for space-borne millimeter- and submillimeter-wave heterodyne radiometer instruments.

  15. Relativistic Absolutism in Moral Education.

    ERIC Educational Resources Information Center

    Vogt, W. Paul

    1982-01-01

    Discusses Emile Durkheim's "Moral Education: A Study in the Theory and Application of the Sociology of Education," which holds that morally healthy societies may vary in culture and organization but must possess absolute rules of moral behavior. Compares this moral theory with current theory and practice of American educators. (MJL)

  16. Absolute transition probabilities of phosphorus.

    NASA Technical Reports Server (NTRS)

    Miller, M. H.; Roig, R. A.; Bengtson, R. D.

    1971-01-01

    Use of a gas-driven shock tube to measure the absolute strengths of 21 P I lines and 126 P II lines (from 3300 to 6900 A). Accuracy for prominent, isolated neutral and ionic lines is estimated to be 28 to 40% and 18 to 30%, respectively. The data and the corresponding theoretical predictions are examined for conformity with the sum rules.-

  17. Multifilter Rotating Shadowband Radiometer (MFRSR) Handbook

    SciTech Connect

    Hodges, GB; Michalsky, JJ

    2011-02-07

    The visible Multifilter Rotating Shadowband Radiometer (MFRSR) is a passive instrument that measures global and diffuse components of solar irradiance at six narrowband channels and one open, or broadband, channel (Harrison et al. 1994). Direct irradiance is not a primary measurement, but is calculated using the diffuse and global measurements. To collect one data record, the MFRSR takes measurements at four different shadowband positions. The first measurement is taken with the shadowband in the nadir (home) position. The next three measurements are, in order, the first side-band, sun-blocked, and second side-band. The side-band measurements are used to correct for the portion of the sky obscured by the shadowband. The nominal wavelengths of the narrowband channels are 415, 500, 615, 673, 870, and 940 nm. From such measurements, one may infer the atmosphere's aerosol optical depth at each wavelength. In turn, these optical depths may be used to derive information about the column abundances of ozone and water vapor (Michalsky et al. 1995), as well as aerosol (Harrison and Michalsky 1994) and other atmospheric constituents.

  18. A low-noise beta-radiometer

    SciTech Connect

    Antonenko, G.I.; Savina, V.I.

    1995-12-01

    The two-channel detector for a low-noise (down to 0.06 sec{sup -1}) beta-radiometer for measuring the mass concentration of {sup 90}Sr in the environment after the chemical extraction of strontium by the oxalate-nitrate method was certified at the D.I. Mendeleev Institute of Metrology (certificate No. 137/93). A detector unit using two end-window self-quenching counters with thin input windows (8 {mu}m thick and 60 mm in diameter) operating as a Geiger-Mueller counter and filled with a mixture of 90% helium (atomic gas) and 10% ethanol (organic molecules) can measure the beta-activity of two substrates concurrently. It is often used to detect the beta-radiation of {sup 90}Sr. This isotope produces particles with energies ranging from 180 to 1000 keV, and the detection efficiency is 50% at a level of 0.1 Bq after measuring for 20 min with an uncertainty of 25%.

  19. Global irradiance calibration of multifilter UV radiometers

    NASA Astrophysics Data System (ADS)

    Piedehierro, A. A.; Cancillo, M. L.; Serrano, A.; Antón, M.; Vilaplana, J. M.

    2016-01-01

    It is well known that the amount of ultraviolet solar radiation (UV) reaching the Earth's surface is governed by stratospheric ozone, which has exhibited notable variations since the late 1970s. A thorough monitoring of UV radiation requires long-term series of accurate measurements worldwide, and to keep track of its evolution, it is essential to use high-quality instrumentation with an excellent long-term performance capable of detecting low UV signal. There are several UV monitoring networks worldwide based on multifilter UV radiometers; however, there is no general agreement about the most suitable methodology for the global irradiance calibration of these instruments. This paper aims to compare several calibration methods and to analyze their behavior for different ranges of solar zenith angle (SZA). Four methods are studied: the two currently most frequently used methods referred to in the literature and two new methods that reduce systematic errors in calibrated data at large solar zenith angles. The results evidence that proposed new methods show a clear improvement compared to the classic approaches at high SZA, especially for channels 305 and 320 nm. These two channels are of great interest for calculating the total ozone column and other products such as dose rates of biological interest in the UV range (e.g., the erythemal dose).

  20. A segmented mirror antenna for radiometers

    NASA Technical Reports Server (NTRS)

    Lee, S. W.; Houshmand, B.; Zimmerman, M.; Acosta, R.

    1989-01-01

    An antenna is designed for the radiometer application of the planned NASA Earth Science Geostationary Platforms in the 1990's. The antenna consists of two parts: a regular parabolic dish of 5 meters in diameter which converts the radiation from feeds into a collimated beam, and a movable mirror that redirects the beam to a prescribed scan direction. The mirror is composed of 28 segmented planar conducting plates, mostly one square meter in size. The secondary pattern of the antenna was analyzed based on a physical optics analysis. For frequencies between 50 and 230 GHz, and for a scan range of + or -8 deg (270 beamwidths scan at 230 GHz), the worst calculated beam efficiency is 95 percent. To cover such a wide frequency and scan range, each of the 28 plates is individually controlled for a tilting less than 4 deg, and for a sliding less than 0.5 cm. The sliding is done at discrete steps. At 230 GHz, a step size of 2 mil is sufficient. The plate positions must be reset for each frequency and for each scan direction. Once the position is set, the frequency bandwidth of the antenna is very narrow.

  1. AVHRR/1-FM Advanced Very High Resolution Radiometer

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The advanced very high resolution radiometer is discussed. The program covers design, construction, and test of a breadboard model, engineering model, protoflight model, mechanical/structural model, and a life test model. Special bench test and calibration equipment was developed for use on the program. The flight model program objectives were to fabricate, assemble and test four of the advanced very high resolution radiometers along with a bench cooler and collimator.

  2. Radiometal complexes: characterization and relevant in vitro studies.

    PubMed

    Jurisson, S; Cutler, C; Smith, S V

    2008-09-01

    Radiometals are, and will continue to be, very important to diagnostic and therapeutic nuclear medicine applications as they predominantly possess the most suitable nuclear properties for these types of applications. This article attempts to give the reader an overview of key aspects that need to be considered in the design and synthesis of a radiopharmaceutical using the commonly known and employed radionuclides, such as technetium, rhenium, the lanthanides and copper. While it is important to understand each radiometal ion has its own specific coordination chemistry requirements, there are several issues that are critical to all radiometal ions for their incorporation into a radiopharmaceutical. 1) The route of production and the presence of long lived contaminating radionuclides and or of naturally occurring metal ions that will interfere with the efficient and optimum radiolabelling of their ligand of choice as well as the final specific activity of the product; 2) the significant differences between the chemistry at the macroscopic (mM and higher concentrations) and radiotracer levels (uM and lower concentrations for the high specific activity radionuclides); 3) the rate of complexation and of dissociation of the radiometal ion vs the competing reaction of radiometal hydrolysis; 4) natural biological pathway of the radio-metal ion and therefore the design of the appropriate and relevant in vitro tests to assess the stability of the radiometal complex. These are a selection of critical factors that need to be considered in the design of a successful radiopharmaceutical, whether it is used for imaging or therapy. However, one should consider tailoring their investigations to suit the radiometal under investigation, and to be mindful where the technology is to be applied (e.g. imaging organs or disease). PMID:18480740

  3. Construction of UV-A radiometer for irradiance measurements

    NASA Astrophysics Data System (ADS)

    Alves, L. C.; Coelho, C. T.; Corrêa, J. S. P. M.; Menegotto, T.; da Silva, T. F.; de Souza, M. A.; da Silva, E. M.; de Lima, M. S.; de Alvarenga, A. P. D.

    2016-07-01

    This work presents preliminary results aiming on providing Inmetro with a radiometric transfer standard in the UV-A spectral range. A broadband UV radiometer head was constructed using an UV photodiode, a commercially available UV-A optical filter and a precision aperture. These components have been characterized in the calibration and measurement facilities available at Inmetro. The preliminary characterization of the assembled UV broadband radiometer was carried out and the results are presented and discussed in this text.

  4. The Cloud Absorption Radiometer HDF Data User's Guide

    NASA Technical Reports Server (NTRS)

    Li, Jason Y.; Arnold, G. Thomas; Meyer, Howard G.; Tsay, Si-Chee; King, Michael D.

    1997-01-01

    The purpose of this document is to describe the Cloud Absorption Radiometer (CAR) Instrument, methods used in the CAR Hierarchical Data Format (HDF) data processing, the structure and format of the CAR HDF data files, and methods for accessing the data. Examples of CAR applications and their results are also presented. The CAR instrument is a multiwavelength scanning radiometer that measures the angular distributions of scattered radiation.

  5. Visible and infrared imaging radiometers for ocean observations

    NASA Technical Reports Server (NTRS)

    Barnes, W. L.

    1977-01-01

    The current status of visible and infrared sensors designed for the remote monitoring of the oceans is reviewed. Emphasis is placed on multichannel scanning radiometers that are either operational or under development. Present design practices and parameter constraints are discussed. Airborne sensor systems examined include the ocean color scanner and the ocean temperature scanner. The costal zone color scanner and advanced very high resolution radiometer are reviewed with emphasis on design specifications. Recent technological advances and their impact on sensor design are examined.

  6. Moral absolutism and ectopic pregnancy.

    PubMed

    Kaczor, C

    2001-02-01

    If one accepts a version of absolutism that excludes the intentional killing of any innocent human person from conception to natural death, ectopic pregnancy poses vexing difficulties. Given that the embryonic life almost certainly will die anyway, how can one retain one's moral principle and yet adequately respond to a situation that gravely threatens the life of the mother and her future fertility? The four options of treatment most often discussed in the literature are non-intervention, salpingectomy (removal of tube with embryo), salpingostomy (removal of embryo alone), and use of methotrexate (MXT). In this essay, I review these four options and introduce a fifth (the milking technique). In order to assess these options in terms of the absolutism mentioned, it will also be necessary to discuss various accounts of the intention/foresight distinction. I conclude that salpingectomy, salpingostomy, and the milking technique are compatible with absolutist presuppositions, but not the use of methotrexate.

  7. Moral absolutism and ectopic pregnancy.

    PubMed

    Kaczor, C

    2001-02-01

    If one accepts a version of absolutism that excludes the intentional killing of any innocent human person from conception to natural death, ectopic pregnancy poses vexing difficulties. Given that the embryonic life almost certainly will die anyway, how can one retain one's moral principle and yet adequately respond to a situation that gravely threatens the life of the mother and her future fertility? The four options of treatment most often discussed in the literature are non-intervention, salpingectomy (removal of tube with embryo), salpingostomy (removal of embryo alone), and use of methotrexate (MXT). In this essay, I review these four options and introduce a fifth (the milking technique). In order to assess these options in terms of the absolutism mentioned, it will also be necessary to discuss various accounts of the intention/foresight distinction. I conclude that salpingectomy, salpingostomy, and the milking technique are compatible with absolutist presuppositions, but not the use of methotrexate. PMID:11262641

  8. The Absolute Spectrum Polarimeter (ASP)

    NASA Technical Reports Server (NTRS)

    Kogut, A. J.

    2010-01-01

    The Absolute Spectrum Polarimeter (ASP) is an Explorer-class mission to map the absolute intensity and linear polarization of the cosmic microwave background and diffuse astrophysical foregrounds over the full sky from 30 GHz to 5 THz. The principal science goal is the detection and characterization of linear polarization from an inflationary epoch in the early universe, with tensor-to-scalar ratio r much greater than 1O(raised to the power of { -3}) and Compton distortion y < 10 (raised to the power of{-6}). We describe the ASP instrument and mission architecture needed to detect the signature of an inflationary epoch in the early universe using only 4 semiconductor bolometers.

  9. Classification images predict absolute efficiency.

    PubMed

    Murray, Richard F; Bennett, Patrick J; Sekuler, Allison B

    2005-02-24

    How well do classification images characterize human observers' strategies in perceptual tasks? We show mathematically that from the classification image of a noisy linear observer, it is possible to recover the observer's absolute efficiency. If we could similarly predict human observers' performance from their classification images, this would suggest that the linear model that underlies use of the classification image method is adequate over the small range of stimuli typically encountered in a classification image experiment, and that a classification image captures most important aspects of human observers' performance over this range. In a contrast discrimination task and in a shape discrimination task, we found that observers' absolute efficiencies were generally well predicted by their classification images, although consistently slightly (approximately 13%) higher than predicted. We consider whether a number of plausible nonlinearities can account for the slight under prediction, and of these we find that only a form of phase uncertainty can account for the discrepancy.

  10. Absolute calibration of optical flats

    DOEpatents

    Sommargren, Gary E.

    2005-04-05

    The invention uses the phase shifting diffraction interferometer (PSDI) to provide a true point-by-point measurement of absolute flatness over the surface of optical flats. Beams exiting the fiber optics in a PSDI have perfect spherical wavefronts. The measurement beam is reflected from the optical flat and passed through an auxiliary optic to then be combined with the reference beam on a CCD. The combined beams include phase errors due to both the optic under test and the auxiliary optic. Standard phase extraction algorithms are used to calculate this combined phase error. The optical flat is then removed from the system and the measurement fiber is moved to recombine the two beams. The newly combined beams include only the phase errors due to the auxiliary optic. When the second phase measurement is subtracted from the first phase measurement, the absolute phase error of the optical flat is obtained.

  11. Radiometric Measurement Comparisons Using Transfer Radiometers in Support of the Calibration of NASA's Earth Observing System (EOS) Sensors

    NASA Technical Reports Server (NTRS)

    Butler, James J.; Johnson, B. Carol; Brown, Steven W.; Yoon, Howard W.; Barnes, Robert A.; Markham, Brian L.; Biggar, Stuart F.; Zalewski, Edward F.; Spyak, Paul R.; Cooper, John W.; Sakuma, Fumihiro

    1999-01-01

    EOS satellite instruments operating in the visible through the shortwave infrared wavelength regions (from 0.4 micrometers to 2.5 micrometers) are calibrated prior to flight for radiance response using integrating spheres at a number of instrument builder facilities. The traceability of the radiance produced by these spheres with respect to international standards is the responsibility of the instrument builder, and different calibration techniques are employed by those builders. The National Aeronautics and Space Administration's (NASA's) Earth Observing System (EOS) Project Science Office, realizing the importance of preflight calibration and cross-calibration, has sponsored a number of radiometric measurement comparisons, the main purpose of which is to validate the radiometric scale assigned to the integrating spheres by the instrument builders. This paper describes the radiometric measurement comparisons, the use of stable transfer radiometers to perform the measurements, and the measurement approaches and protocols used to validate integrating sphere radiances. Stable transfer radiometers from the National Institute of Standards and Technology, the University of Arizona Optical Sciences Center Remote Sensing Group, NASA's Goddard Space Flight Center, and the National Research Laboratory of Metrology in Japan, have participated in these comparisons. The approaches used in the comparisons include the measurement of multiple integrating sphere lamp levels, repeat measurements of select lamp levels, the use of the stable radiometers as external sphere monitors, and the rapid reporting of measurement results. Results from several comparisons are presented. The absolute radiometric calibration standard uncertainties required by the EOS satellite instruments are typically in the +/- 3% to +/- 5% range. Preliminary results reported during eleven radiometric measurement comparisons held between February 1995 and May 1998 have shown the radiance of integrating spheres

  12. RESONANT CAVITY EXCITATION SYSTEM

    DOEpatents

    Baker, W.R.; Kerns, Q.A.; Riedel, J.

    1959-01-13

    An apparatus is presented for exciting a cavity resonator with a minimum of difficulty and, more specifically describes a sub-exciter and an amplifier type pre-exciter for the high-frequency cxcitation of large cavities. Instead of applying full voltage to the main oscillator, a sub-excitation voltage is initially used to establish a base level of oscillation in the cavity. A portion of the cavity encrgy is coupled to the input of the pre-exciter where it is amplified and fed back into the cavity when the pre-exciter is energized. After the voltage in the cavity resonator has reached maximum value under excitation by the pre-exciter, full voltage is applied to the oscillator and the pre-exciter is tunned off. The cavity is then excited to the maximum high voltage value of radio frequency by the oscillator.

  13. Cavity turnover and equilibrium cavity densities in a cottonwood bottomland

    USGS Publications Warehouse

    Sedgwick, James A.; Knopf, Fritz L.

    1992-01-01

    A fundamental factor regulating the numbers of secondary cavity nesting (SCN) birds is the number of extant cavities available for nesting. The number of available cavities may be thought of as being in an approximate equilibrium maintained by a very rough balance between recruitment and loss of cavities. Based on estimates of cavity recruitment and loss, we ascertained equilibrium cavity densities in a mature plains cottonwood (Populus sargentii) bottomland along the South Platte River in northeastern Colorado. Annual cavity recruitment, derived from density estimates of primary cavity nesting (PCN) birds and cavity excavation rates, was estimated to be 71-86 new cavities excavated/100 ha. Of 180 active cavities of 11 species of cavity-nesting birds found in 1985 and 1986, 83 were no longer usable by 1990, giving an average instantaneous rate of cavity loss of r = -0.230. From these values of cavity recruitment and cavity loss, equilibrium cavity density along the South Platte is 238-289 cavities/100 ha. This range of equilibrium cavity density is only slightly above the minimum of 205 cavities/100 ha required by SCN's and suggests that cavity availability may be limiting SCN densities along the South Platte River. We submit that snag management alone does not adequately address SCN habitat needs, and that cavity management, expressed in terms of cavity turnover and cavity densities, may be more useful.

  14. Feasibility of detecting aircraft wake vortices using passive microwave radiometers

    NASA Technical Reports Server (NTRS)

    Harrington, Richard F.

    1993-01-01

    The feasibility of detecting the cold core of the wake vortex from the wingtips of an aircraft using a passive microwave radiometer was investigated. It was determined that there is a possibility that a cold core whose physical temperature drop is 10 C or greater and which has a diameter of 5 m or greater can be detected by a microwave radiometer. The radiometer would be a noise injection balanced Dicke radiometer operating at a center frequency of 60 GHz. It would require a noise figure of 5 dB, a predetection bandwidth of 6 GHz, and an integration time of 2 seconds resulting in a radiometric sensitivity of 0.018 K. However, three additional studies are required. The first would determine what are the fluctuations in the radiometric antenna temperature due to short-term fluctuations in atmospheric pressure, temperature, and relative humidity. Second, what is the effect of the pressure and temperature drop within the cold core of the wake vortex on its opacity. The third area concerns the possibility of developing a 60 GHz radiometer with a radio metric sensitivity an order of magnitude improvement over the existing state of the art.

  15. APHID: A Wideband, Multichannel Radiometer for Phase Delay Correction

    NASA Astrophysics Data System (ADS)

    Staguhn, J.; Harris, A. I.; Munday, L. G.; Woody, D. P.

    Atmospheric phase fluctuations of mm and sub-mm signals are predominantly caused by line of sight fluctuations in the amount of water vapor. Measurements of the line emission from tropospheric water vapor can be used to track and correct these fluctuations. We present model calculations which led to the design of a multichannel water vapor radiometer for phase correction of millimeter arrays. Our particular emphasis is on designing a phase correction scheme for mid-latitude sites (BIMA, OVRO), and for high-altitude sites. The instrument being implemented at OVRO and BIMA is a cooled double-sideband heterodyne receiver centered on the 22.2GHz water vapor line with a 0.5 - 4.0GHz IF. The back end is a 16 channel analog lag correlator similar to the WASP spectrometer (Harris et al 1998). We present two applications for the multichannel radiometer. A line fit to the observed spectra is expected to provide sufficient accuracy for mm phase correction with the 22 GHZ line. The radiometer can also be used for the determination of the vertical water vapor distribution from the observed line shape. We discuss how this information can be used to improve the accuracy of water vapor radiometers which have too few channels to observe the line shape, and for phase correction schemes which are based on a 183 GHz water line radiometer.

  16. Comparison of precipitable water observations in the near tropics by GPS, microwave radiometer and radiosondes.

    SciTech Connect

    Liou, Y. A.; Teng, Y. T.; VanHove, T.; Liljegren, J. C.; Environmental Research; National Central Univ.; UCAR

    2001-01-01

    The sensing of precipitable water (PW) using the Global Positioning System (GPS) in the near Tropics is investigated. GPS data acquired from the Central Weather Bureau's Taipei weather station in Banchao (Taipei), Taiwan, and each of nine International GPS Service (IGS) stations were utilized to determine independently the PW at the Taipei site from 18 to 24 March 1998. Baselines between Taipei and the other nine stations range from 676 to 3009 km. The PW determined from GPS observations for the nine baseline cases are compared with measurements by a dual-channel water vapor radiometer (WVR) and radiosondes at the Taipei site. Although previous results from other locations show that the variability in the rms difference between GPS- and WVR-observed PW ranges from 1 to 2 mm, a variability of 2.2 mm is found. The increase is consistent with scaling of the variability with the total water vapor burden (PW). In addition, accurate absolute PW estimates from GPS data for baseline lengths between 1500 and 3000 km were obtained. Previously, 500 and 2000 km have been recommended in the literature as the minimum baseline length needed for accurate absolute PW estimation. An exception occurs when GPS data acquired in Guam, one of the nine IGS stations, were utilized. This result is a possible further indication that the rms difference between GPS- and WVR-measured PW is dependent on the total water vapor burden, because both Taipei and Guam are located in more humid regions than the other stations.

  17. Absolute Thermal SST Measurements over the Deepwater Horizon Oil Spill

    NASA Astrophysics Data System (ADS)

    Good, W. S.; Warden, R.; Kaptchen, P. F.; Finch, T.; Emery, W. J.

    2010-12-01

    Climate monitoring and natural disaster rapid assessment require baseline measurements that can be tracked over time to distinguish anthropogenic versus natural changes to the Earth system. Disasters like the Deepwater Horizon Oil Spill require constant monitoring to assess the potential environmental and economic impacts. Absolute calibration and validation of Earth-observing sensors is needed to allow for comparison of temporally separated data sets and provide accurate information to policy makers. The Ball Experimental Sea Surface Temperature (BESST) radiometer was designed and built by Ball Aerospace to provide a well calibrated measure of sea surface temperature (SST) from an unmanned aerial system (UAS). Currently, emissive skin SST observed by satellite infrared radiometers is validated by shipborne instruments that are expensive to deploy and can only take a few data samples along the ship track to overlap within a single satellite pixel. Implementation on a UAS will allow BESST to map the full footprint of a satellite pixel and perform averaging to remove any local variability due to the difference in footprint size of the instruments. It also enables the capability to study this sub-pixel variability to determine if smaller scale effects need to be accounted for in models to improve forecasting of ocean events. In addition to satellite sensor validation, BESST can distinguish meter scale variations in SST which could be used to remotely monitor and assess thermal pollution in rivers and coastal areas as well as study diurnal and seasonal changes to bodies of water that impact the ocean ecosystem. BESST was recently deployed on a conventional Twin Otter airplane for measurements over the Gulf of Mexico to access the thermal properties of the ocean surface being affected by the oil spill. Results of these measurements will be presented along with ancillary sensor data used to eliminate false signals including UV and Synthetic Aperture Radar (SAR

  18. The AFGL absolute gravity program

    NASA Technical Reports Server (NTRS)

    Hammond, J. A.; Iliff, R. L.

    1978-01-01

    A brief discussion of the AFGL's (Air Force Geophysics Laboratory) program in absolute gravity is presented. Support of outside work and in-house studies relating to gravity instrumentation are discussed. A description of the current transportable system is included and the latest results are presented. These results show good agreement with measurements at the AFGL site by an Italian system. The accuracy obtained by the transportable apparatus is better than 0.1 microns sq sec 10 microgal and agreement with previous measurements is within the combined uncertainties of the measurements.

  19. Familial Aggregation of Absolute Pitch

    PubMed Central

    Baharloo, Siamak; Service, Susan K.; Risch, Neil; Gitschier, Jane; Freimer, Nelson B.

    2000-01-01

    Absolute pitch (AP) is a behavioral trait that is defined as the ability to identify the pitch of tones in the absence of a reference pitch. AP is an ideal phenotype for investigation of gene and environment interactions in the development of complex human behaviors. Individuals who score exceptionally well on formalized auditory tests of pitch perception are designated as “AP-1.” As described in this report, auditory testing of siblings of AP-1 probands and of a control sample indicates that AP-1 aggregates in families. The implications of this finding for the mapping of loci for AP-1 predisposition are discussed. PMID:10924408

  20. Absolute brightness temperature measurements at 3.5-mm wavelength. [of sun, Venus, Jupiter and Saturn

    NASA Technical Reports Server (NTRS)

    Ulich, B. L.; Rhodes, P. J.; Davis, J. H.; Hollis, J. M.

    1980-01-01

    Careful observations have been made at 86.1 GHz to derive the absolute brightness temperatures of the sun (7914 + or - 192 K), Venus (357.5 + or - 13.1 K), Jupiter (179.4 + or - 4.7 K), and Saturn (153.4 + or - 4.8 K) with a standard error of about three percent. This is a significant improvement in accuracy over previous results at millimeter wavelengths. A stable transmitter and novel superheterodyne receiver were constructed and used to determine the effective collecting area of the Millimeter Wave Observatory (MWO) 4.9-m antenna relative to a previously calibrated standard gain horn. The thermal scale was set by calibrating the radiometer with carefully constructed and tested hot and cold loads. The brightness temperatures may be used to establish an absolute calibration scale and to determine the antenna aperture and beam efficiencies of other radio telescopes at 3.5-mm wavelength.

  1. A Liquid-Helium-Cooled Absolute Reference Cold Load forLong-Wavelength Radiometric Calibration

    SciTech Connect

    Bensadoun, M.; Witebsky, C.; Smoot, George F.; De Amici,Giovanni; Kogut, A.; Levin, S.

    1990-05-01

    We describe a large (78-cm) diameter liquid-helium-cooled black-body absolute reference cold load for the calibration of microwave radiometers. The load provides an absolute calibration near the liquid helium (LHe) boiling point, accurate to better than 30 mK for wavelengths from 2.5 to 25 cm (12-1.2 GHz). The emission (from non-LHe temperature parts of the cold load) and reflection are small and well determined. Total corrections to the LHe boiling point temperature are {le} 50 mK over the operating range. This cold load has been used at several wavelengths at the South Pole and at the White Mountain Research Station. In operation, the average LHe loss rate was {le} 4.4 l/hr. Design considerations, radiometric and thermal performance and operational aspects are discussed. A comparison with other LHe-cooled reference loads including the predecessor of this cold load is given.

  2. Progress in Low-Power Digital Microwave Radiometer Technologies

    NASA Technical Reports Server (NTRS)

    Piepmeier, Jeffrey R.; Kim, Edward J.

    2004-01-01

    Three component technologies were combined into a digital correlation microwave radiometer. The radiometer comprises a dual-channel X-band superheterodyne receiver, low-power high-speed cross-correlator (HSCC), three-level ADCs, and a correlated noise source (CNS). The HSCC dissipates 10 mW and operates at 500 MHz clock speed. The ADCs are implemented using ECL components and dissipate more power than desired. Thus, a low-power ADC development is underway. The new ADCs arc predicted to dissipated less than 200 mW and operate at 1 GSps with 1.5 GHz of input bandwidth. The CNS provides different input correlation values for calibration of the radiometer. The correlation channel had a null offset of 0.0008. Test results indicate that the correlation channel can be calibrated with 0.09% error in gain.

  3. Design and calibration of field deployable ground-viewing radiometers.

    PubMed

    Anderson, Nikolaus; Czapla-Myers, Jeffrey; Leisso, Nathan; Biggar, Stuart; Burkhart, Charles; Kingston, Rob; Thome, Kurtis

    2013-01-10

    Three improved ground-viewing radiometers were built to support the Radiometric Calibration Test Site (RadCaTS) developed by the Remote Sensing Group (RSG) at the University of Arizona. Improved over previous light-emitting diode based versions, these filter-based radiometers employ seven silicon detectors and one InGaAs detector covering a wavelength range of 400-1550 nm. They are temperature controlled and designed for greater stability and lower noise. The radiometer systems show signal-to-noise ratios of greater than 1000 for all eight channels at typical field calibration signal levels. Predeployment laboratory radiance calibrations using a 1 m spherical integrating source compare well with in situ field calibrations using the solar radiation based calibration method; all bands are within ±2.7% for the case tested.

  4. Electromagnetic SCRF Cavity Tuner

    SciTech Connect

    Kashikhin, V.; Borissov, E.; Foster, G.W.; Makulski, A.; Pischalnikov, Y.; Khabiboulline, T.; /Fermilab

    2009-05-01

    A novel prototype of SCRF cavity tuner is being designed and tested at Fermilab. This is a superconducting C-type iron dominated magnet having a 10 mm gap, axial symmetry, and a 1 Tesla field. Inside the gap is mounted a superconducting coil capable of moving {+-} 1 mm and producing a longitudinal force up to {+-} 1.5 kN. The static force applied to the RF cavity flanges provides a long-term cavity geometry tuning to a nominal frequency. The same coil powered by fast AC current pulse delivers mechanical perturbation for fast cavity tuning. This fast mechanical perturbation could be used to compensate a dynamic RF cavity detuning caused by cavity Lorentz forces and microphonics. A special configuration of magnet system was designed and tested.

  5. Cavity enhanced terahertz modulation

    SciTech Connect

    Born, N.; Scheller, M.; Moloney, J. V.; Koch, M.

    2014-03-10

    We present a versatile concept for all optical terahertz (THz) amplitude modulators based on a Fabry-Pérot semiconductor cavity design. Employing the high reflectivity of two parallel meta-surfaces allows for trapping selected THz photons within the cavity and thus only a weak optical modulation of the semiconductor absorbance is required to significantly damp the field within the cavity. The optical switching yields to modulation depths of more than 90% with insertion efficiencies of 80%.

  6. Experimental characterization of edge force on the Crookes radiometer

    SciTech Connect

    Ventura, Austin L.; Ketsdever, Andrew D.; Gimelshein, Natalia E.; Gimelshein, Sergey F.

    2014-12-09

    The contribution of edge force on the Crookes radiometer is experimentally investigated with three vane geometries. This work examines increasing the force per unit weight of a radiometer vane for applications such as near-space propulsion by increasing the vane’s perimeter while decreasing the total surface area of the vane by means of machined holes in the vanes. Experimental results are given for three vane geometries. These results indicate that although force to vane weight ratios can be improved, the maximum force is achieved by a vane geometry that contains no hole features.

  7. Maser radiometer for cosmic background radiation anisotropy measurements

    NASA Astrophysics Data System (ADS)

    Fixsen, D. J.; Wilkinson, D. T.

    1982-06-01

    A maser amplifier was incorporated into a low noise radiometer designed to measure large-scale anisotropy in the 3 deg K microwave background radiation. To minimize emission by atmospheric water vapor and oxygen, the radiometer is flown in a small balloon to an altitude to 25 km. Three successful flights were made - two from Palestine, Texas and one from Sao Jose dos Campos, Brazil. Good sky coverage is important to the experiment. Data from the northern hemisphere flights has been edited and calibrated.

  8. Remote monitoring of soil moisture using airborne microwave radiometers

    NASA Technical Reports Server (NTRS)

    Kroll, C. L.

    1973-01-01

    The current status of microwave radiometry is provided. The fundamentals of the microwave radiometer are reviewed with particular reference to airborne operations, and the interpretative procedures normally used for the modeling of the apparent temperature are presented. Airborne microwave radiometer measurements were made over selected flight lines in Chickasha, Oklahoma and Weslaco, Texas. Extensive ground measurements of soil moisture were made in support of the aircraft mission over the two locations. In addition, laboratory determination of the complex permittivities of soil samples taken from the flight lines were made with varying moisture contents. The data were analyzed to determine the degree of correlation between measured apparent temperatures and soil moisture content.

  9. Active radiometer for self-calibrated furnace temperature measurements

    DOEpatents

    Woskov, Paul P.; Cohn, Daniel R.; Titus, Charles H.; Wittle, J. Kenneth; Surma, Jeffrey E.

    1996-01-01

    Radiometer with a probe beam superimposed on its field-of-view for furnace temperature measurements. The radiometer includes a heterodyne millimeter/submillimeter-wave receiver including a millimeter/submillimeter-wave source for probing. The receiver is adapted to receive radiation from a surface whose temperature is to be measured. The radiation includes a surface emission portion and a surface reflection portion which includes the probe beam energy reflected from the surface. The surface emission portion is related to the surface temperature and the surface reflection portion is related to the emissivity of the surface. The simultaneous measurement of surface emissivity serves as a real time calibration of the temperature measurement.

  10. ESTAR - A synthetic aperture microwave radiometer for measuring soil moisture

    NASA Technical Reports Server (NTRS)

    Le Vine, D. M.; Griffis, A.; Swift, C. T.; Jackson, T. J.

    1992-01-01

    The measurement of soil moisture from space requires putting relatively large microwave antennas in orbit. Aperture synthesis, an interferometric technique for reducing the antenna aperture needed in space, offers the potential for a practical means of meeting these requirements. An aircraft prototype, electronically steered thinned array L-band radiometer (ESTAR), has been built to develop this concept and to demonstrate its suitability for the measurement of soil moisture. Recent flights over the Walnut Gulch Watershed in Arizona show good agreement with ground truth and with measurements with the Pushbroom Microwave Radiometer (PBMR).

  11. Maser radiometer for cosmic background radiation anisotropy measurements

    NASA Technical Reports Server (NTRS)

    Fixsen, D. J.; Wilkinson, D. T.

    1982-01-01

    A maser amplifier was incorporated into a low noise radiometer designed to measure large-scale anisotropy in the 3 deg K microwave background radiation. To minimize emission by atmospheric water vapor and oxygen, the radiometer is flown in a small balloon to an altitude to 25 km. Three successful flights were made - two from Palestine, Texas and one from Sao Jose dos Campos, Brazil. Good sky coverage is important to the experiment. Data from the northern hemisphere flights has been edited and calibrated.

  12. Interpreting measurements obtained with the cloud absorption radiometer

    NASA Technical Reports Server (NTRS)

    1988-01-01

    The software developed for the analysis of data from the Cloud Absorption Radiometer (CAR) is discussed. The CAR is a multichannel radiometer designed to measure the radiation field in the middle of an optically thick cloud (the diffusion domain). It can also measure the surface albedo and escape function. The instrument currently flies on a C-131A aircraft operated by the University of Washington. Most of this data was collected during the First International satellite cloud climatology project Regional Experiment (FIRE) Marine Stratocumulus Intensive Field Observation program off San Diego during July 1987. Earlier flights of the CAR have also been studied.

  13. Characterization of cavity wakes

    NASA Astrophysics Data System (ADS)

    Kidd, James A.

    Scope and Method of Study. This research focused on flow over deep cavities at subsonic speeds with emphasis on the wake downstream of the cavity. Cavity wake behaviors have not been studied in detail and are a major concern for air vehicles with cavities and in particular for optical sensor systems installed in cavities. Other key behaviors for sensor survival and performance are cavity resonance and turbulence scales in the shear layer. A wind tunnel test apparatus was developed to explore cavity and wake characteristics. It consisted of a test section insert for the OSU Indraft Wind Tunnel with an additional contraction cone for significantly increased speed. The test section included a variable depth cavity in a boundary layer splitter plate/fairing assembly, a Y-Z traverse and pitot rake with in-situ pressure transducers for high frequency response. Flows were measured over clean cavities with length to depth (L/D) ratios of 4 to 1/2 and on cavities with a porous fence for resonance suppression. Measurements were taken in streamwise and cross-stream sections to three cavity lengths downstream of the cavity trailing edge. Flow visualization using laser sheet and smoke injection was also used. Findings and Conclusions. The high speed insert demonstrated a significant new capability for the OSU wind tunnel, reaching speeds of 0.35 Mach (390 feet/second) in a 14"x14" test section. Inlet room flow was found to be quite unsteady and recommendations are made for improved flow and quantitative visualization. Key findings for cavity wake flow include its highly three dimensional nature with asymmetric peaks in cross section with boundary layer thicknesses and integral length scales several times that of a normal flat plate turbulent boundary layer (TBL). Turbulent intensities (TI) of 35% to 55% of freestream speeds were measured for the clean configuration. Fence configuration TI's were 20% to 35% of free stream and, in both configurations, TI's decayed to

  14. Optically measuring interior cavities

    DOEpatents

    Stone, Gary Franklin

    2008-12-21

    A method of measuring the three-dimensional volume or perimeter shape of an interior cavity includes the steps of collecting a first optical slice of data that represents a partial volume or perimeter shape of the interior cavity, collecting additional optical slices of data that represents a partial volume or perimeter shape of the interior cavity, and combining the first optical slice of data and the additional optical slices of data to calculate of the three-dimensional volume or perimeter shape of the interior cavity.

  15. Optically measuring interior cavities

    DOEpatents

    Stone, Gary Franklin

    2009-11-03

    A method of measuring the three-dimensional volume or perimeter shape of an interior cavity includes the steps of collecting a first optical slice of data that represents a partial volume or perimeter shape of the interior cavity, collecting additional optical slices of data that represents a partial volume or perimeter shape of the interior cavity, and combining the first optical slice of data and the additional optical slices of data to calculate of the three-dimensional volume or perimeter shape of the interior cavity.

  16. The study of the nonlinear correction of the FMCW absolute distance measurement using frequency-sampling and precision analysis

    NASA Astrophysics Data System (ADS)

    Lu, Cheng; Gan, Yu; Chen, Fengdong; Liu, Bingguo; Zhuang, Zhitao; Xu, Xinke; Liu, Guodong

    2014-12-01

    This article uses the external cavity laser to realize FMCW high precision absolute distance measurement, as the external cavity laser owns the advantage of large tuning range of frequency. Firstly, aim at the problem of nonlinear tuning of the external cavity laser, a study of method of frequency-sampling has been shown. Secondly, in this article the mathematical model of the absolute dis tance measurement system has been established, and the sources of the errors of the FMCW absolute distance measurement has been analyzed, and the accuracy model has been established. Finally, a ball which is put at a distance about 3 meters is measured, and the random error is 0.3479μm, the standard uncertainty of measurement system is 0.3479μm+3.141Rppm.

  17. Cloud Absorption Radiometer Autonomous Navigation System - CANS

    NASA Technical Reports Server (NTRS)

    Kahle, Duncan; Gatebe, Charles; McCune, Bill; Hellwig, Dustan

    2013-01-01

    CAR (cloud absorption radiometer) acquires spatial reference data from host aircraft navigation systems. This poses various problems during CAR data reduction, including navigation data format, accuracy of position data, accuracy of airframe inertial data, and navigation data rate. Incorporating its own navigation system, which included GPS (Global Positioning System), roll axis inertia and rates, and three axis acceleration, CANS expedites data reduction and increases the accuracy of the CAR end data product. CANS provides a self-contained navigation system for the CAR, using inertial reference and GPS positional information. The intent of the software application was to correct the sensor with respect to aircraft roll in real time based upon inputs from a precision navigation sensor. In addition, the navigation information (including GPS position), attitude data, and sensor position details are all streamed to a remote system for recording and later analysis. CANS comprises a commercially available inertial navigation system with integral GPS capability (Attitude Heading Reference System AHRS) integrated into the CAR support structure and data system. The unit is attached to the bottom of the tripod support structure. The related GPS antenna is located on the P-3 radome immediately above the CAR. The AHRS unit provides a RS-232 data stream containing global position and inertial attitude and velocity data to the CAR, which is recorded concurrently with the CAR data. This independence from aircraft navigation input provides for position and inertial state data that accounts for very small changes in aircraft attitude and position, sensed at the CAR location as opposed to aircraft state sensors typically installed close to the aircraft center of gravity. More accurate positional data enables quicker CAR data reduction with better resolution. The CANS software operates in two modes: initialization/calibration and operational. In the initialization/calibration mode

  18. Observations of water vapor by ground-based microwave radiometers and Raman lidar

    NASA Technical Reports Server (NTRS)

    Han, Yong; Snider, J. B.; Westwater, E. R.; Melfi, S. H.; Ferrare, R. A.

    1994-01-01

    In November to December 1991, a substantial number of remote sensors and in situ instruments were operated together in Coffeyville, Kansas, during the climate experiment First ISCCP Regional Experiment Phase 2 (FIRE 2). Includede in the suite of instruments were (1) the NOAA Environmental Technology Laboratory (ETL) three-channel microwave radiometer, (2) the NASA GSFC Raman lidar, (3) ETL radio acoustic sounding system (RASS), and (4) frequent, research-quality radiosondes. The Raman lidar operated only at night and the focus of this portion of the experiment concentrated on clear conditions. The lidar data, together with frequent radiosondes and measurements of temperature profiles (every 15 min) by RASS allowed profiles of temperature and absolute humidity to be estimated every minute. We compared 20 min measurements of brightness temperature (T(sub b) with calculations of T(sub b) that were based on the Liebe and Layton (1987) and Liebe et al. (1993) microwave propagation models, as well as the Waters (1976) model. The comparisons showed the best agreement at 20.6 GHz with the Waters model, with the Liebe et al. (1993) model being best at 31.65 GHz. The results at 90 GHz gave about equal success with the Liebe and Layton (1987) and Liebe et al. (1993) models. Comparisons of precipitable water vapor derived independently from the two instruments also showed excellent agreement, even for averages as short as 2 min. The rms difference between Raman and radiometric determinations of precipitable water vapor was 0.03 cm which is roughly 2%. The experiments clearly demonstrate the potential of simultaneous operation of radiometers and Raman lidars for fundamental physical studies of water vapor.

  19. Observations of water vapor by ground-based microwave radiometers and Raman lidar

    SciTech Connect

    Han, Y.; Snider, J.B.; Westwater, E.R.; Melfi, S.H.; Ferrare, R.A.

    1994-09-20

    In November to December 1991, a substantial number of remote sensors and in situ instruments were operated together in Coffeyville, Kansas, during the climate experiment FIRE II. Included in the suite of instruments were (1) the NOAA Environmental Technology Laboratory (ETL) three-channel microwave radiometer, (2) the NASA GSFC Raman lidar, (3) ETL radio acoustic sounding system (RASS), and (4) frequent, research-quality radiosondes. The Raman lidar operated only at night and the focus of this portion of the experiment concentrated on clear conditions. The lidar data, together with frequent radiosondes and measurements of temperature profiles (every 15 min) by RASS allowed profiles of temperature and absolute humidity to be estimated every minute. The authors compared 2-min measurements of brightness temperature (T{sub b}) with calculations of T{sub b} that were based on the Liebe and Layton, and Liebe et al. microwave propagation models, as well as the Waters model. The comparisons showed the best agreement at 20.6 GHz with the Waters model, with the Liebe et al. model being best at 31.65 GHz. The results at 90 GHz gave about equal success with the Liebe and Layton, and Liebe et al. models. Comparisons of precipitable water vapor derived independently from the two instruments also showed excellent agreement, even for averages as short as 2 min. The rms difference between Raman and radiometric determinations of precipitable water vapor was 0.03 cm which is roughly 2%. The experiments clearly demonstrate the potentisdal of simultaneous operation of radiometers and Raman lidars for fundamental physical studies of water vapor. 31 refs., 5 figs., 5 tabs.

  20. Cosmology with negative absolute temperatures

    NASA Astrophysics Data System (ADS)

    Vieira, J. P. P.; Byrnes, Christian T.; Lewis, Antony

    2016-08-01

    Negative absolute temperatures (NAT) are an exotic thermodynamical consequence of quantum physics which has been known since the 1950's (having been achieved in the lab on a number of occasions). Recently, the work of Braun et al. [1] has rekindled interest in negative temperatures and hinted at a possibility of using NAT systems in the lab as dark energy analogues. This paper goes one step further, looking into the cosmological consequences of the existence of a NAT component in the Universe. NAT-dominated expanding Universes experience a borderline phantom expansion (w < ‑1) with no Big Rip, and their contracting counterparts are forced to bounce after the energy density becomes sufficiently large. Both scenarios might be used to solve horizon and flatness problems analogously to standard inflation and bouncing cosmologies. We discuss the difficulties in obtaining and ending a NAT-dominated epoch, and possible ways of obtaining density perturbations with an acceptable spectrum.

  1. Apparatus for absolute pressure measurement

    NASA Technical Reports Server (NTRS)

    Hecht, R. (Inventor)

    1969-01-01

    An absolute pressure sensor (e.g., the diaphragm of a capacitance manometer) was subjected to a superimposed potential to effectively reduce the mechanical stiffness of the sensor. This substantially increases the sensitivity of the sensor and is particularly useful in vacuum gauges. An oscillating component of the superimposed potential induced vibrations of the sensor. The phase of these vibrations with respect to that of the oscillating component was monitored, and served to initiate an automatic adjustment of the static component of the superimposed potential, so as to bring the sensor into resonance at the frequency of the oscillating component. This establishes a selected sensitivity for the sensor, since a definite relationship exists between resonant frequency and sensitivity.

  2. Cosmology with negative absolute temperatures

    NASA Astrophysics Data System (ADS)

    Vieira, J. P. P.; Byrnes, Christian T.; Lewis, Antony

    2016-08-01

    Negative absolute temperatures (NAT) are an exotic thermodynamical consequence of quantum physics which has been known since the 1950's (having been achieved in the lab on a number of occasions). Recently, the work of Braun et al. [1] has rekindled interest in negative temperatures and hinted at a possibility of using NAT systems in the lab as dark energy analogues. This paper goes one step further, looking into the cosmological consequences of the existence of a NAT component in the Universe. NAT-dominated expanding Universes experience a borderline phantom expansion (w < -1) with no Big Rip, and their contracting counterparts are forced to bounce after the energy density becomes sufficiently large. Both scenarios might be used to solve horizon and flatness problems analogously to standard inflation and bouncing cosmologies. We discuss the difficulties in obtaining and ending a NAT-dominated epoch, and possible ways of obtaining density perturbations with an acceptable spectrum.

  3. Absolute flatness testing of skip-flat interferometry by matrix analysis in polar coordinates.

    PubMed

    Han, Zhi-Gang; Yin, Lu; Chen, Lei; Zhu, Ri-Hong

    2016-03-20

    A new method utilizing matrix analysis in polar coordinates has been presented for absolute testing of skip-flat interferometry. The retrieval of the absolute profile mainly includes three steps: (1) transform the wavefront maps of the two cavity measurements into data in polar coordinates; (2) retrieve the profile of the reflective flat in polar coordinates by matrix analysis; and (3) transform the profile of the reflective flat back into data in Cartesian coordinates and retrieve the profile of the sample. Simulation of synthetic surface data has been provided, showing the capability of the approach to achieve an accuracy of the order of 0.01 nm RMS. The absolute profile can be retrieved by a set of closed mathematical formulas without polynomial fitting of wavefront maps or the iterative evaluation of an error function, making the new method more efficient for absolute testing.

  4. The absolute radiometric calibration of space-based sensors

    NASA Astrophysics Data System (ADS)

    Holm, Ronald Gene

    A reflectance based inflight calibration procedure is used to determine the radiance reaching the entrance pupil of a sensor. This procedure uses ground based measurements coupled with a radiative transfer code to characterize the effects the atmosphere has on the signal reaching the sensor. The computed radiance is compared to the digital count output of the sensor associated with the image of a test site. This provides an update to the preflight calibration of the system and a check on the on-board internal calibrator. This calibration procedure was used to perform a series of 5 calibrations of the LANDSAT-5 Thematic Mapper. The absolute calibration techniques were put to another test with a series of 3 calibration of the SPOT-1 High Resolution Visible sensors. The procedure for performing a satellite calibration was then used to demonstrate how a calibrated satellite sensor can be used to quantitatively evaluate surface reflectance over a wide range of surface features. Predicted reflectance factors were compared to values obtained from aircraft based radiometer data. A strong correlation was shown between reflectance values determined from satellite imagery and low flying aircraft data.

  5. Liquid laser cavities

    NASA Technical Reports Server (NTRS)

    Bjorklund, S.; Filipescu, N.; Kellermeyer, G. L.; Mc Avoy, N.

    1969-01-01

    Liquid laser cavities have plenum chambers at the ends of the capillary cell which are terminated in transparent optical flats. By use of these cavities, several new europium chelates and a terbium chelate can provide laser action in solution at room temperature.

  6. A 94/183 GHz multichannel radiometer for Convair flights

    NASA Technical Reports Server (NTRS)

    Gagliano, J. A.; Stratigos, J. A.; Forsythe, R. E.; Schuchardt, J. M.

    1979-01-01

    A multichannel 94/183 GHz radiometer was designed, built, and installed on the NASA Convair 990 research aircraft to take data for hurricane penetration flights, SEASAT-A underflights for measuring rain and water vapor, and Nimbus-G underflights for new sea ice signatures and sea surface temperature data (94 GHz only). The radiometer utilized IF frequencies of 1, 5, and 8.75 GHz about the peak of the atmospheric water vapor absorption line, centered at 183.3 GHz, to gather data needed to determine the shape of the water molecule line. Another portion of the radiometer operated at 94 GHz and obtained data on the sea brightness temperature, sea ice signatures, and on areas of rain near the ocean surface. The radiometer used a multiple lens antenna/temperature calibration technique using 3 lenses and corrugated feed horns at 94 GHz and 183 GHz. Alignment of the feed beams at 94 GHz and 183 GHz was accomplished using a 45 deg oriented reflecting surface which permitted simultaneous viewing of the feeds on alternate cycles of the chopping intervals.

  7. Global measurements of air pollution from satellites. [employing radiometer techniques

    NASA Technical Reports Server (NTRS)

    Acton, L. L.; Bartle, E. R.; Griggs, M.; Hall, G. D.; Hesketh, W. D.; Ludwig, C. B.; Malkmus, W.; Reichle, H.

    1974-01-01

    The conceptual design of an FOV nadir radiometer was examined for its applicability to monitoring the radiation process in the atmosphere as it relates to aerosol behavior. The instrument employs a gas filter correlation technique and is suitable for transportation onboard satellite.

  8. High Frequency PIN-Diode Switches for Radiometer Applications

    NASA Technical Reports Server (NTRS)

    Montes, Oliver; Dawson, Douglas E.; Kangaslahti, Pekka; Reising, Steven C.

    2011-01-01

    Internally calibrated radiometers are needed for ocean topography and other missions. Typically internal calibration is achieved with Dicke switching as one of the techniques. We have developed high frequency single-pole double-throw (SPDT) switches in the form of monolithic microwave integrated circuits (MMIC) that can be easily integrated into Dicke switched radiometers that utilize microstrip technology. In particular, the switches we developed can be used for a radiometer such as the one proposed for the Surface Water and Ocean Topography (SWOT) Satellite Mission whose three channels at 92, 130, and 166 GHz would allow for wet-tropospheric path delay correction near coastal zones and over land. This feat is not possible with the current Jason-class radiometers due to their lower frequency signal measurement and thus lower resolution. The MMIC chips were fabricated at NGST using their InP PIN diode process and measured at JPL using high frequency test equipment. Measurement and simulation results will be presented.

  9. Microwave Radiometer – 3 Channel (MWR3C) Handbook

    SciTech Connect

    Cadeddu, MP

    2012-05-04

    The microwave radiometer 3-channel (MWR3C) provides time-series measurements of brightness temperatures from three channels centered at 23.834, 30, and 89 GHz. These three channels are sensitive to the presence of liquid water and precipitable water vapor.

  10. Inflatable Antenna Microwave Radiometer for Soil Moisture Measurement

    NASA Technical Reports Server (NTRS)

    Bailey, M. C.; Kendall, Bruce M.; Schroeder, Lyle C.; Harrington, Richard F.

    1993-01-01

    Microwave measurements of soil moisture are not being obtained at the required spatial Earth resolution with current technology. Recently, new novel designs for lightweight reflector systems have been developed using deployable inflatable antenna structures which could enable lightweight real-aperture radiometers. In consideration of this, a study was conducted at the NASA Langley Research Center (LaRC) to determine the feasibility of developing a microwave radiometer system using inflatable reflector antenna technology to obtain high spatial resolution radiometric measurements of soil moisture from low Earth orbit and which could be used with a small and cost effective launch vehicle. The required high resolution with reasonable swath width coupled with the L-band measurement frequency for soil moisture dictated the use of a large (30 meter class) real aperture antenna in conjunction with a pushbroom antenna beam configuration and noise-injection type radiometer designs at 1.4 and 4.3 GHz to produce a 370 kilometer cross-track swath with a 10 kilometer resolution that could be packaged for launch with a Titan 2 class vehicle. This study includes design of the inflatable structure, control analysis, structural and thermal analysis, antenna and feed design, radiometer design, payload packaging, orbital analysis, and electromagnetic losses in the thin membrane inflatable materials.

  11. Topographic Signatures in Aquarius Radiometer/Scatterometer Response: Initial Results

    NASA Technical Reports Server (NTRS)

    Utku, C.; LeVine, D. M.

    2012-01-01

    The effect of topography on remote sensing at L-band is examined using the co-located Aquarius radiometer and scatterometer observations over land. A correlation with slope standard deviation is demonstrated for both the radiometer and scatterometer at topographic scales. Although the goal of Aquarius is remote sensing of sea surface salinity, the radiometer and scatterometer are on continuously and collect data for remote sensing research over land. Research is reported here using the data over land to determine if topography could have impact on the passive remote sensing at L-band. In this study, we report observations from two study regions: North Africa between 15 deg and 30 deg Northern latitudes and Australia less the Tasmania Island. Common to these two regions are the semi-arid climate and low population density; both favorable conditions to isolate the effect of topography from other sources of scatter and emission such as vegetation and urban areas. Over these study regions, topographic scale slopes within each Aquarius pixel are computed and their standard deviations are compared with Aquarius scatterometer and radiometer observations over a 36 day period between days 275 and 311 of 2011.

  12. Radiometer calibration procedure and beacon attenuation estimation reference level

    NASA Technical Reports Server (NTRS)

    Crane, Robert K.

    1994-01-01

    The primary objectives are to compare radiometer attenuation with beacon attenuation and to compare sky temperature estimates with calculations using simultaneous meteorological data. Secondary objectives are: (1) noise diode and reference load measurements and (2) to adjust for outside temperature and component temperature changes.

  13. Wind compensation by radiometer arrays in high altitude propulsion

    NASA Astrophysics Data System (ADS)

    Gimelshein, Natalia; Gimelshein, Sergey; Ketsdever, Andrew; Young, Marcus

    2012-11-01

    Numerical analysis has been conducted to assess the feasibility of using radiometer arrays mounted on a near-space vehicle, for wind disturbance compensation. The results indicate the possibility of using radiometric force for that purpose for altitudes of 80 km and smaller, and head winds up to 30 m/s.

  14. Characterisation of optical filters for broadband UVA radiometer

    NASA Astrophysics Data System (ADS)

    Alves, Luciana C.; Coelho, Carla T.; Corrêa, Jaqueline S. P. M.; Menegotto, Thiago; Ferreira da Silva, Thiago; Aparecida de Souza, Muriel; Melo da Silva, Elisama; Simões de Lima, Maurício; Dornelles de Alvarenga, Ana Paula

    2016-07-01

    Optical filters were characterized in order to know its suitability for use in broadband UVA radiometer head for spectral irradiance measurements. The spectral transmittance, the angular dependence and the spatial uniformity of the spectral transmittance of the UVA optical filters were investigated. The temperature dependence of the transmittance was also studied.

  15. A horizontal vane radiometer: Experiment, theory, and simulation

    NASA Astrophysics Data System (ADS)

    Wolfe, David; Larraza, Andres; Garcia, Alejandro

    2016-03-01

    The existence of two motive forces on a Crookes radiometer has complicated the investigation of either force independently. The thermal creep shear force in particular has been subject to differing interpretations of the direction in which it acts and its order of magnitude. In this article, we provide a horizontal vane radiometer design which isolates the thermal creep shear force. The horizontal vane radiometer is explored through experiment, kinetic theory, and the Direct Simulation Monte Carlo (DSMC) method. The qualitative agreement between the three methods of investigation is good except for a dependence of the force on the width of the vane even when the temperature gradient is narrower than the vane which is present in the DSMC method results but not in the theory. The experimental results qualitatively resemble the theory in this regard. The quantitative agreement between the three methods of investigation is better than an order of magnitude in the cases examined. The theory is closer to the experimental values for narrow vanes and the simulations are closer to the experimental values for the wide vanes. We find that the thermal creep force acts from the hot side to the cold side of the vane. We also find the peak in the radiometer's angular speed as a function of pressure is explained as much by the behavior of the drag force as by the behavior of the thermal creep force.

  16. A New Way to Demonstrate the Radiometer as a Heat Engine

    ERIC Educational Resources Information Center

    Hladkouski, V. I.; Pinchuk, A. I.

    2015-01-01

    While the radiometer is readily available as a toy, A. E. Woodruff notes that it is also a very useful tool to help us understand how to resolve certain scientific problems. Many physicists think they know how the radiometer works, but only a few actually understand it. Here we present a demonstration that shows that a radiometer can be thought of…

  17. CAVITY EXCITATION CIRCUIT

    DOEpatents

    Franck, J.V.

    1959-10-20

    An electronic oscillator is described for energizing a resonant cavity and to a system for stabilizing the operatin g frequency of the oscillator at the particular frequency necessary to establish a particular preferred field configuration or mode in the cavity, in this instance a linear accelerator. A freely rnnning oscillator has an output coupled to a resonant cavity wherein a field may be built up at any one of several adjacent frequencies. A pickup loop in the cavity is suitably shielded and positioned in the cavity so that only energy at the panticular desired frequency is fed back to stabilize the oscillator. A phase and gain control is in cluded in the feedback line.

  18. Passivated niobium cavities

    SciTech Connect

    Myneni, Ganapati Rao; Hjorvarsson, Bjorgvin; Ciovati, Gianluigi

    2006-12-19

    A niobium cavity exhibiting high quality factors at high gradients is provided by treating a niobium cavity through a process comprising: 1) removing surface oxides by plasma etching or a similar process; 2) removing hydrogen or other gases absorbed in the bulk niobium by high temperature treatment of the cavity under ultra high vacuum to achieve hydrogen outgassing; and 3) assuring the long term chemical stability of the niobium cavity by applying a passivating layer of a superconducting material having a superconducting transition temperature higher than niobium thereby reducing losses from electron (cooper pair) scattering in the near surface region of the interior of the niobium cavity. According to a preferred embodiment, the passivating layer comprises niobium nitride (NbN) applied by reactive sputtering.

  19. The advanced microwave precipitation radiometer: A new aircraft radiometer for passive precipitation remote sensing

    NASA Technical Reports Server (NTRS)

    Hood, Robbie E.; Spencer, Roy W.; James, Mark W.

    1991-01-01

    Past studies of passive microwave measurements of precipitating systems have yielded broad empirical relationships between hydrometeors and microwave transmission. In general, these relationships fall into two categories of passive microwave precipitation retrievals rely upon the observed effect of liquid precipitation to increase the brightness temperature of a radiometrically cold background such as an ocean surface. A scattering-based method is based upon the effect that frozen hydrometeors tend to decrease the brightness temperature of a radiometrically warm background such as land. One step toward developing quantitative brightness temperature-rain rate relationships is the recent construction of a new aircraft instrument sponsored by National Aeronautics and Space Administration/Marshall Space Flight Center (NASA/MSFC). This instrument is the Advanced Microwave Precipitation Radiometer (AMPR) designed and built by Georgia Tech Research Institute to fly aboard high altitude research aircraft such as the NASA ER-2. The AMPR and its accompanying data acquisition system are mounted in the Q-bay compartment of the NASA ER-2.

  20. [Research on absolute calibration of sun channel of sun photometer using laser raster scanning method].

    PubMed

    Xu, Wen-Bin; Li, Jian-Jun; Zheng, Xiao-Bing

    2013-01-01

    In the present paper, a new calibration method of absolute spectral irradiance responsivity of sun channel of sun photometer was developed. A tunable laser was used as source and a standard tranfer detector, calibrated against cryogenic absolute radiometer, was used to measure laser beam power. By raster scanning of a single collimated laser beam to generate the uniform irradiance field at the plane of effective aperture stop of sun photometer, the absolute irradiance responsivity of center wavelength of the 870 nm unpolarized sun channels of sun photometer was obtained accurately. The relative spectral irradiance responsivity of corresponding channel was obtained by using lamp-monochromator system and then used to acquire the absolute spectral irradiance responsivity in the laboratory. On the basis of the above results, the top-of-the-atmosphere responsive constant V0 was obtained by integration with extraterrestrial solar spectral irradiance data. Comparing the calibration result with that from GSFC, NASA in 2009, the difference is only 3.75%. In the last, the uncertainties of calibration were evaluated and reached to 2.06%. The principle feasibility of the new method was validated.

  1. Columnar water vapor retrievals from multifilter rotating shadowband radiometer data

    SciTech Connect

    Alexandrov, Mikhail; Schmid, Beat; Turner, David D.; Cairns, Brian; Oinas, Valdar; Lacis, Andrew A.; Gutman, S.; Westwater, Ed R.; Smirnov, A.; Eilers, J.

    2009-01-26

    The Multi-Filter Rotating Shadowband Radiometer (MFRSR) measures direct and diffuse irradiances in the visible and near IR spectral range. In addition to characteristics of atmospheric aerosols, MFRSR data also allow retrieval of precipitable water vapor (PWV) column amounts, which are determined from the direct normal irradiances in the 940 nm spectral channel. The HITRAN 2004 spectral database was used in our retrievals to model the water vapor absorption. We present a detailed error analysis describing the influence of uncertainties in instrument calibration and spectral response, as well as those in available spectral databases, on the retrieval results. The results of our PWV retrievals from the Southern Great Plains (SGP) site operated by the DOE Atmospheric Radiation Measurement (ARM) Program were compared with correlative standard measurements by Microwave Radiometers (MWRs) and a Global Positioning System (GPS) water vapor sensor, as well as with retrievals from other solar radiometers (AERONET’s CIMEL, AATS-6). Some of these data are routinely available at the SGP’s Central Facility, however, we also used measurements from a wider array of instrumentation deployed at this site during the Water Vapor Intensive Observation Period (WVIOP2000) in September – October 2000. The WVIOP data show better agreement between different solar radiometers or between different microwave radiometers (both groups showing relative biases within 4%) than between these two groups of instruments, with MWRs values being consistently higher (up to 14%) than those from solar instruments. We also demonstrate the feasibility of using MFRSR network data for creation of 2D datasets comparable with the MODIS satellite water vapor product.

  2. Design and Development of the SMAP Microwave Radiometer Electronics

    NASA Technical Reports Server (NTRS)

    Piepmeier, Jeffrey R.; Medeiros, James J.; Horgan, Kevin A.; Brambora, Clifford K.; Estep, Robert H.

    2014-01-01

    The SMAP microwave radiometer will measure land surface brightness temperature at L-band (1413 MHz) in the presence of radio frequency interference (RFI) for soil moisture remote sensing. The radiometer design was driven by the requirements to incorporate internal calibration, to operate synchronously with the SMAP radar, and to mitigate the deleterious effects of RFI. The system design includes a highly linear super-heterodyne microwave receiver with internal reference loads and noise sources for calibration and an innovative digital signal processor and detection system. The front-end comprises a coaxial cable-based feed network, with a pair of diplexers and a coupled noise source, and radiometer front-end (RFE) box. Internal calibration is provided by reference switches and a common noise source inside the RFE. The RF back-end (RBE) downconverts the 1413 MHz channel to an intermediate frequency (IF) of 120 MHz. The IF signals are then sampled and quantized by high-speed analog-to-digital converters in the radiometer digital electronics (RDE) box. The RBE local oscillator and RDE sampling clocks are phase-locked to a common reference to ensure coherency between the signals. The RDE performs additional filtering, sub-band channelization, cross-correlation for measuring third and fourth Stokes parameters, and detection and integration of the first four raw moments of the signals. These data are packetized and sent to the ground for calibration and further processing. Here we discuss the novel features of the radiometer hardware particularly those influenced by the need to mitigate RFI.

  3. On-Orbit Absolute Radiance Standard for Future IR Remote Sensing Instruments

    NASA Astrophysics Data System (ADS)

    Best, F. A.; Adler, D. P.; Pettersen, C.; Revercomb, H. E.; Gero, P. J.; Taylor, J. K.; Knuteson, R. O.; Perepezko, J. H.

    2010-12-01

    Future NASA infrared remote sensing missions, including the climate benchmark CLARREO mission will require better absolute measurement accuracy than now available, and will most certainly rely on the emerging capability to fly SI traceable standards that provide irrefutable absolute measurement accuracy. As an example, instrumentation designed to measure spectrally resolved infrared radiances with an absolute brightness temperature error of better than 0.1 K will require high-emissivity (>0.999) calibration blackbodies with emissivity uncertainty of better than 0.06%, and absolute temperature uncertainties of better than 0.045K (3 sigma). Key elements of an On-Orbit Absolute Radiance Standard (OARS) meeting these stringent requirements have been demonstrated in the laboratory at the University of Wisconsin and are undergoing Technology Readiness Level (TRL) advancement under the NASA Instrument Incubator Program (IIP). We present the new technologies that underlie the OARS and the results of laboratory testing that demonstrate the required accuracy is being met. The underlying technologies include on-orbit absolute temperature calibration using the transient melt signatures of small quantities (<1g) of reference materials (gallium, water, and mercury) imbedded in the blackbody cavity; and on-orbit cavity spectral emissivity measurement using a heated halo. For these emissivity measurements, a carefully baffled heated cylinder is placed in front of a blackbody in the infrared spectrometer system, and the combined radiance of the blackbody and Heated Halo reflection is observed. Knowledge of key temperatures and the viewing geometry allow the blackbody cavity spectral emissivity to be calculated. This work will culminate with an integrated subsystem that can provide on-orbit end-to-end radiometric accuracy validation for infrared remote sensing instruments.

  4. Absolute configuration of isovouacapenol C

    PubMed Central

    Fun, Hoong-Kun; Yodsaoue, Orapun; Karalai, Chatchanok; Chantrapromma, Suchada

    2010-01-01

    The title compound, C27H34O5 {systematic name: (4aR,5R,6R,6aS,7R,11aS,11bR)-4a,6-dihy­droxy-4,4,7,11b-tetra­methyl-1,2,3,4,4a,5,6,6a,7,11,11a,11b-dodeca­hydro­phenanthro[3,2-b]furan-5-yl benzoate}, is a cassane furan­oditerpene, which was isolated from the roots of Caesalpinia pulcherrima. The three cyclo­hexane rings are trans fused: two of these are in chair conformations with the third in a twisted half-chair conformation, whereas the furan ring is almost planar (r.m.s. deviation = 0.003 Å). An intra­molecular C—H⋯O inter­action generates an S(6) ring. The absolute configurations of the stereogenic centres at positions 4a, 5, 6, 6a, 7, 11a and 11b are R, R, R, S, R, S and R, respectively. In the crystal, mol­ecules are linked into infinite chains along [010] by O—H⋯O hydrogen bonds. C⋯O [3.306 (2)–3.347 (2) Å] short contacts and C—H⋯π inter­actions also occur. PMID:21588364

  5. Frequency-domain analysis of absolute gravimeters

    NASA Astrophysics Data System (ADS)

    Svitlov, S.

    2012-12-01

    An absolute gravimeter is analysed as a linear time-invariant system in the frequency domain. Frequency responses of absolute gravimeters are derived analytically based on the propagation of the complex exponential signal through their linear measurement functions. Depending on the model of motion and the number of time-distance coordinates, an absolute gravimeter is considered as a second-order (three-level scheme) or third-order (multiple-level scheme) low-pass filter. It is shown that the behaviour of an atom absolute gravimeter in the frequency domain corresponds to that of the three-level corner-cube absolute gravimeter. Theoretical results are applied for evaluation of random and systematic measurement errors and optimization of an experiment. The developed theory agrees with known results of an absolute gravimeter analysis in the time and frequency domains and can be used for measurement uncertainty analyses, building of vibration-isolation systems and synthesis of digital filtering algorithms.

  6. Evaluation of Radiometers Deployed at the National Renewable Energy Laboratory's Solar Radiation Research Laboratory

    SciTech Connect

    Habte, A.; Wilcox, S.; Stoffel, T.

    2014-02-01

    This study analyzes the performance of various commercially available radiometers used for measuring global horizontal irradiances and direct normal irradiances. These include pyranometers, pyrheliometers, rotating shadowband radiometers, and a pyranometer with fixed internal shading and are all deployed at the National Renewable Energy Laboratory's Solar Radiation Research Laboratory. Data from 32 global horizontal irradiance and 19 direct normal irradiance radiometers are presented. The radiometers in this study were deployed for one year (from April 1, 2011, through March 31, 2012) and compared to measurements from radiometers with the lowest values of estimated measurement uncertainties for producing reference global horizontal irradiances and direct normal irradiances.

  7. Soil Moisture Active Passive (SMAP) L-Band Microwave Radiometer Post-Launch Calibration

    NASA Technical Reports Server (NTRS)

    Peng, Jinzheng; Piepmeier, Jeffrey R.; Misra, Sidharth; Dinnat, Emmanuel P.; Hudson, Derek; Le Vine, David M.; De Amici, Giovanni; Mohammed, Priscilla N.; Yueh, Simon H.; Meissner, Thomas

    2016-01-01

    The SMAP microwave radiometer is a fully-polarimetric L-band radiometer flown on the SMAP satellite in a 6 AM/ 6 PM sun-synchronous orbit at 685 km altitude. Since April, 2015, the radiometer is under calibration and validation to assess the quality of the radiometer L1B data product. Calibration methods including the SMAP L1B TA2TB (from Antenna Temperature (TA) to the Earth's surface Brightness Temperature (TB)) algorithm and TA forward models are outlined, and validation approaches to calibration stability/quality are described in this paper including future work. Results show that the current radiometer L1B data satisfies its requirements.

  8. The Correlation Radiometer - A New Application in MM-Wave Total Power Radiometry

    NASA Technical Reports Server (NTRS)

    Gaier, Todd; Tanner, Alan; Kangaslahti, Pekka; Lim, Boon

    2013-01-01

    We describe the design and performance of a 180 GHz correlation radiometer suitable for remote sensing. The radiometer provides continuous comparisons between a the observed signal and a reference load to provide stable radiometric baselines. The radiometer was assembled and tested using parts from the GeoSTAR-II instrument and is fully compatible with operation in a synthetic aperture radiometer or as a standalone technology for use in microwave sounding and imaging. This new radiometer was tested over several days easily demonstrating the required 6 hour stability requirement for observations of mean brightness temperature for a geostationary instrument.

  9. Hydroforming of elliptical cavities

    DOE PAGES

    Singer, W.; Singer, X.; Jelezov, I.; Kneisel, Peter

    2015-02-27

    Activities of the past several years in developing the technique of forming seamless (weldless) cavity cells by hydroforming are summarized. An overview of the technique developed at DESY for the fabrication of single cells and multicells of the TESLA cavity shape is given and the major rf results are presented. The forming is performed by expanding a seamless tube with internal water pressure while simultaneously swaging it axially. Prior to the expansion the tube is necked at the iris area and at the ends. Tube radii and axial displacements are computer controlled during the forming process in accordance with resultsmore » of finite element method simulations for necking and expansion using the experimentally obtained strain-stress relationship of tube material. In cooperation with industry different methods of niobium seamless tube production have been explored. The most appropriate and successful method is a combination of spinning or deep drawing with flow forming. Several single-cell niobium cavities of the 1.3 GHz TESLA shape were produced by hydroforming. They reached accelerating gradients Eacc up to 35 MV/m after buffered chemical polishing (BCP) and up to 42 MV/m after electropolishing (EP). More recent work concentrated on fabrication and testing of multicell and nine-cell cavities. Several seamless two- and three-cell units were explored. Accelerating gradients Eacc of 30–35 MV/m were measured after BCP and Eacc up to 40 MV/m were reached after EP. Nine-cell niobium cavities combining three three-cell units were completed at the company E. Zanon. These cavities reached accelerating gradients of Eacc = 30–35 MV/m. One cavity is successfully integrated in an XFEL cryomodule and is used in the operation of the FLASH linear accelerator at DESY. Additionally the fabrication of bimetallic single-cell and multicell NbCu cavities by hydroforming was successfully developed. Several NbCu clad single-cell and double-cell cavities of the TESLA shape have

  10. Tuned optical cavity magnetometer

    SciTech Connect

    Okandan, Murat; Schwindt, Peter

    2010-11-02

    An atomic magnetometer is disclosed which utilizes an optical cavity formed from a grating and a mirror, with a vapor cell containing an alkali metal vapor located inside the optical cavity. Lasers are used to magnetically polarize the alkali metal vapor and to probe the vapor and generate a diffracted laser beam which can be used to sense a magnetic field. Electrostatic actuators can be used in the magnetometer for positioning of the mirror, or for modulation thereof. Another optical cavity can also be formed from the mirror and a second grating for sensing, adjusting, or stabilizing the position of the mirror.

  11. Hydroforming of elliptical cavities

    SciTech Connect

    Singer, W.; Singer, X.; Jelezov, I.; Kneisel, Peter

    2015-02-27

    Activities of the past several years in developing the technique of forming seamless (weldless) cavity cells by hydroforming are summarized. An overview of the technique developed at DESY for the fabrication of single cells and multicells of the TESLA cavity shape is given and the major rf results are presented. The forming is performed by expanding a seamless tube with internal water pressure while simultaneously swaging it axially. Prior to the expansion the tube is necked at the iris area and at the ends. Tube radii and axial displacements are computer controlled during the forming process in accordance with results of finite element method simulations for necking and expansion using the experimentally obtained strain-stress relationship of tube material. In cooperation with industry different methods of niobium seamless tube production have been explored. The most appropriate and successful method is a combination of spinning or deep drawing with flow forming. Several single-cell niobium cavities of the 1.3 GHz TESLA shape were produced by hydroforming. They reached accelerating gradients Eacc up to 35 MV/m after buffered chemical polishing (BCP) and up to 42 MV/m after electropolishing (EP). More recent work concentrated on fabrication and testing of multicell and nine-cell cavities. Several seamless two- and three-cell units were explored. Accelerating gradients Eacc of 30–35 MV/m were measured after BCP and Eacc up to 40 MV/m were reached after EP. Nine-cell niobium cavities combining three three-cell units were completed at the company E. Zanon. These cavities reached accelerating gradients of Eacc = 30–35 MV/m. One cavity is successfully integrated in an XFEL cryomodule and is used in the operation of the FLASH linear accelerator at DESY. Additionally the fabrication of bimetallic single-cell and multicell NbCu cavities by hydroforming was successfully developed. Several NbCu clad single-cell and double

  12. Absolute measurements of the electronic transition moments of seven band systems of the C2 molecule. Ph.D. Thesis - York Univ., Toronto

    NASA Technical Reports Server (NTRS)

    Cooper, D. M.

    1979-01-01

    Electronic transition moments of seven C2 singlet and triplet band systems in the 0.2-1.2 micron spectral region were measured. The measurements were made in emission behind incident shock waves in C2H2-argon mixtures. Narrow bandpass radiometers were used to obtain absolute measurements of shock-excited C2 radiation from which absolute electronic transition moments are derived by a synthetic spectrum analysis. New results are reported for the Ballik-Ramsay, Phillips, Swan, Deslandres-d'Azambuja, Fox-Herzberg, Mulliken, and Freymark systems.

  13. Precipitation from the GPM Microwave Imager and Constellation Radiometers

    NASA Astrophysics Data System (ADS)

    Kummerow, Christian; Randel, David; Kirstetter, Pierre-Emmanuel; Kulie, Mark; Wang, Nai-Yu

    2014-05-01

    Satellite precipitation retrievals from microwave sensors are fundamentally underconstrained requiring either implicit or explicit a-priori information to constrain solutions. The radiometer algorithm designed for the GPM core and constellation satellites makes this a-priori information explicit in the form of a database of possible rain structures from the GPM core satellite and a Bayesian retrieval scheme. The a-priori database will eventually come from the GPM core satellite's combined radar/radiometer retrieval algorithm. That product is physically constrained to ensure radiometric consistency between the radars and radiometers and is thus ideally suited to create the a-priori databases for all radiometers in the GPM constellation. Until a robust product exists, however, the a-priori databases are being generated from the combination of existing sources over land and oceans. Over oceans, the Day-1 GPM radiometer algorithm uses the TRMM PR/TMI physically derived hydrometer profiles that are available from the tropics through sea surface temperatures of approximately 285K. For colder sea surface temperatures, the existing profiles are used with lower hydrometeor layers removed to correspond to colder conditions. While not ideal, the results appear to be reasonable placeholders until the full GPM database can be constructed. It is more difficult to construct physically consistent profiles over land due to ambiguities in surface emissivities as well as details of the ice scattering that dominates brightness temperature signatures over land. Over land, the a-priori databases have therefore been constructed by matching satellite overpasses to surface radar data derived from the WSR-88 network over the continental United States through the National Mosaic and Multi-Sensor QPE (NMQ) initiative. Databases are generated as a function of land type (4 categories of increasing vegetation cover as well as 4 categories of increasing snow depth), land surface temperature and

  14. CIRCULAR CAVITY SLOT ANTENNA

    DOEpatents

    Kerley, P.L.

    1959-01-01

    A small-size antenna having a doughnut-shaped field pattern and which can act both as an antenna and a resonant circuit is described. The antenna is of the slotted type and comprises a resonant cavity with a center hole. A circular slot is provided in one wall of the cavity concentric with the hole and a radio frequency source is connected across the slot. The pattern and loading of the antenna are adjusted by varying the position and shape of a center element slidably disposed within the hole and projecting from the slotted side of the resonant cavity. The disclosed structure may also be used to propagate the oscillator signal down a transniission line by replacing the center element with one leg of the transmission line in a spaced relation from the walls of the cavity.

  15. Absolute flux density calibrations: Receiver saturation effects

    NASA Technical Reports Server (NTRS)

    Freiley, A. J.; Ohlson, J. E.; Seidel, B. L.

    1978-01-01

    The effect of receiver saturation was examined for a total power radiometer which uses an ambient load for calibration. Extension to other calibration schemes is indicated. The analysis shows that a monotonic receiver saturation characteristic could cause either positive or negative measurement errors, with polarity depending upon operating conditions. A realistic model of the receiver was made by using a linear-cubic voltage transfer characteristic. The evaluation of measurement error for this model provided a means for correcting radio source measurements.

  16. Skylab program: Earth resources experiment package. Sensor performance evaluation. Volume 6: (S194) L-band radiometer

    NASA Technical Reports Server (NTRS)

    Kenney, G. P.

    1975-01-01

    Analysis of the Skylab S194 L-band radiometer experiment data provided significant results pertaining to the actual realized performance during flight. Analysis of preflight test data provided a baseline from which to compare the experiment flight performance, although many radiometric data performance capabilities could only be demonstrated in the flight environment. The final results establish the overall hardware performance of the S194 system from which prospective users of the flight data can refer for various scientific applications. Instrument performance is presented in the areas of housekeeping and internal calibration parameters, antenna system integrity, dynamic range, linearity, precision, resolution, and absolute accuracy. Supplementary evaluations were included for an error analysis of system calibration stability. Results of the evaluation show that the instrument performance was generally as expected. Conclusions are drawn from the final evaluation results, and recommendations for improving the effectiveness of a future program are offered.

  17. Evaluation of the Delta-T SPN1 radiometer for the measurement of solar irradiance components

    NASA Astrophysics Data System (ADS)

    Estelles, Victor; Serrano, David; Segura, Sara; Wood, John; Webb, Nick; Utrillas, Maria Pilar

    2016-04-01

    In this study we analyse the performance of an SPN1 radiometer built by Delta-T Devices Ltd. to retrieve global solar irradiance at ground and its components (diffuse, direct) in comparison with measurements from two Kipp&Zonen CMP21 radiometers and a Kipp&Zonen CHP1 pirheliometer, mounted on an active Solys-2 suntracker at the Burjassot site (Valencia, Spain) using data acquired every minute during years 2013 - 2015. The measurement site is close to sea level (60 m a.s.l.), near the Mediterranean coast (10 km) and within the metropolitan area of Valencia City (over 1.500.000 inhabitants). The SPN1 is an inexpensive and versatile instrument for the measurement of the three components of the solar radiation without any mobile part and without any need to azimuthally align the instrument to track the sun (http://www.delta-t.co.uk). The three components of the solar radiation are estimated from a combination of measurements performed by 7 different miniature thermopiles. The SPN1 pyranometer measures the irradiance between 400 and 2700 nm, and the nominal uncertainty for the individual readings is about 8% ± 10 W/m2 (5% for the daily averages). The pyranometer Kipp&Zonen CMP21 model is a secondary standard for the measurement of broadband solar global irradiance in horizontal planes. Two ventilated CMP21 are used for the measurement of the global and diffuse irradiances. The expected total daily uncertainty of the radiometer is estimated to be 2%. The pirheliometer Kipp&Zonen CHP1 is designed for the measurement of the direct irradiance. The principles are similar to the CMP21 pyranometer. The results of the comparison show that the global irradiance from the SPN1 compares very well with the CMP21, with absolute RMSD and MBD differences below the combined uncertainties (15 W/m2 and -5.4 W/m2, respectively; relative RMSD of 3.1%). Both datasets are very well correlated, with a correlation coefficient higher than 0.997 and a slope and intercept very close to 1 and 0

  18. Phased Array Radiometer Calibration Using a Radiated Noise Source

    NASA Technical Reports Server (NTRS)

    Srinivasan, Karthik; Limaye, Ashutoch S.; Laymon, Charles A.; Meyer, Paul J.

    2010-01-01

    Electronic beam steering capability of phased array antenna systems offer significant advantages when used in real aperture imaging radiometers. The sensitivity of such systems is limited by the ability to accurately calibrate variations in the antenna circuit characteristics. Passive antenna systems, which require mechanical rotation to scan the beam, have stable characteristics and the noise figure of the antenna can be characterized with knowledge of its physical temperature [1],[2]. Phased array antenna systems provide the ability to electronically steer the beam in any desired direction. Such antennas make use of active components (amplifiers, phase shifters) to provide electronic scanning capability while maintaining a low antenna noise figure. The gain fluctuations in the active components can be significant, resulting in substantial calibration difficulties [3]. In this paper, we introduce two novel calibration techniques that provide an end-to-end calibration of a real-aperture, phased array radiometer system. Empirical data will be shown to illustrate the performance of both methods.

  19. Thermoelectric temperature control system for the pushbroom microwave radiometer (PBMR)

    NASA Technical Reports Server (NTRS)

    Dillon-Townes, L. A.; Averill, R. D.

    1984-01-01

    A closed loop thermoelectric temperature control system is developed for stabilizing sensitive RF integrated circuits within a microwave radiometer to an accuracy of + or - 0.1 C over a range of ambient conditions from -20 C to +45 C. The dual mode (heating and cooling) control concept utilizes partial thermal isolation of the RF units from an instrument deck which is thermally controlled by thermoelectric coolers and thin film heaters. The temperature control concept is simulated with a thermal analyzer program (MITAS) which consists of 37 nodes and 61 conductors. A full scale thermal mockup is tested in the laboratory at temperatures of 0 C, 21 C, and 45 C to confirm the validity of the control concept. A flight radiometer and temperature control system is successfully flight tested on the NASA Skyvan aircraft.

  20. Narrow Field of View Zenith Radiometer (NFOV) Handbook

    SciTech Connect

    Chiu, C; Marshak, A; Hodges, G; Barnard, JC; Schmelzer, J

    2008-11-01

    The two-channel narrow field-of-view radiometer (NFOV2) is a ground-based radiometer that looks straight up and measures radiance directly above the instrument at wavelengths of 673 and 870 nm. The field-of-view of the instrument is 1.2 degrees, and the sampling time resolution is one second. Measurements of the NFOV2 have been used to retrieve optical properties for overhead clouds that range from patchy to overcast. With a one-second sampling rate of the NFOV2, faster than almost any other ARM Climate Research Facility (ACRF) instrument, we are able, for the first time, to capture changes in cloud optical properties at the natural time scale of cloud evolution.

  1. Solar-Reflectance-Based Calibration of Spectral Radiometers

    NASA Technical Reports Server (NTRS)

    Cattrall, Christopher; Carder, Kendall L.; Thome, Kurtis J.; Gordon, Howard R.

    2001-01-01

    A method by which to calibrate a spectral radiometer using the sun as the illumination source is discussed. Solar-based calibrations eliminate several uncertainties associated with applying a lamp-based calibration to field measurements. The procedure requires only a calibrated reflectance panel, relatively low aerosol optical depth, and measurements of atmospheric transmittance. Further, a solar-reflectance-based calibration (SRBC), by eliminating the need for extraterrestrial irradiance spectra, reduces calibration uncertainty to approximately 2.2% across the solar-reflective spectrum, significantly reducing uncertainty in measurements used to deduce the optical properties of a system illuminated by the sun (e.g., sky radiance). The procedure is very suitable for on-site calibration of long-term field instruments, thereby reducing the logistics and costs associated with transporting a radiometer to a calibration facility.

  2. The pushbroom microwave radiometer and aircraft measurement of soil moisture

    NASA Technical Reports Server (NTRS)

    Harrington, R. F.; Lawrence, R. W.; Levine, J. S.; Delnore, V. E.

    1985-01-01

    Soil moisture has been identified as a controlling parameter in the occurrence of atmospheric variations and crop vigor. Evapotranspiration rates impact local temperature, precipitation and motion fields of the atmosphere. The multiple beam pushbroom microwave radiometer (MBPMR) is a candidate for moisture monitoring on the Earth Observation System. A prototype MBPMR has been devised for airborne technology evaluations of pushbroom scanning capabilities. The instrument scans at 1.4 GHz with a Diche radiometer. Test flights on a NASA aircraft with the antenna mounted on the bottom of the fuselage have generated soil moisture data over crop areas for which ground truth data were gathered. Large antennas deployed from the Orbiter could collect sufficient data for mapping the global soil moisture in 6 days.

  3. Rotating shadowband radiometer development and analysis of spectral shortwave data

    SciTech Connect

    Michalsky, J.; Harrison, L.; Min, Q.

    1996-04-01

    Our goals in the Atmospheric Radiation Measurement (ARM) Program are improved measurements of spectral shortwave radiation and improved techniques for the retrieval of climatologically sensitive parameters. The multifilter rotating shadowband radiometer (MFRSR) that was developed during the first years of the ARM program has become a workhorse at the Southern Great Plains (SGP) Cloud and Radiation Testbed (CART) site, and it is widely deployed in other climate programs. We have spent most of our effort this year developing techniques to retrieve column aerosol, water vapor, and ozone from direct beam spectral measurements of the MFRSR. Additionally, we have had some success in calculating shortwave surface diffuse spectral irradiance. Using the surface albedo and the global irradiance, we have calculated cloud optical depths. From cloud optical depth and liquid water measured with the microwave radiometer, we have calculated effective liquid cloud particle radii. The rest of the text will provide some detail regarding each of these efforts.

  4. Active radiometer for self-calibrated furnace temperature measurements

    DOEpatents

    Woskov, P.P.; Cohn, D.R.; Titus, C.H.; Wittle, J.K.; Surma, J.E.

    1996-11-12

    A radiometer is described with a probe beam superimposed on its field-of-view for furnace temperature measurements. The radiometer includes a heterodyne millimeter/submillimeter-wave receiver including a millimeter/submillimeter-wave source for probing. The receiver is adapted to receive radiation from a surface whose temperature is to be measured. The radiation includes a surface emission portion and a surface reflection portion which includes the probe beam energy reflected from the surface. The surface emission portion is related to the surface temperature and the surface reflection portion is related to the emissivity of the surface. The simultaneous measurement of surface emissivity serves as a real time calibration of the temperature measurement. 5 figs.

  5. G-Band Vapor Radiometer Profiler (GVRP) Handbook

    SciTech Connect

    Caddeau, MP

    2010-06-23

    The G-Band Vapor Radiometer Profiler (GVRP) provides time-series measurements of brightness temperatures from 15 channels between 170 and 183.310 GHz. Atmospheric emission in this spectral region is primarily due to water vapor, with some influence from liquid water. Channels between 170.0 and 176.0 GHz are particularly sensitive to the presence of liquid water. The sensitivity to water vapor of the 183.31-GHz line is approximately 30 times higher than at the frequencies of the two-channel microwave radiometer (MWR) for a precipitable water vapor (PWV) amount of less than 2.5 mm. Measurements from the GVRP instrument are therefore especially useful during low-humidity conditions (PWV < 5 mm). In addition to integrated water vapor and liquid water, the GVRP can provide low-resolution vertical profiles of water vapor in very dry conditions.

  6. A Ruggedized MMW Radiometer Sensor For Surveillance Applications

    NASA Astrophysics Data System (ADS)

    Roeder, Robert S.; Wilt, Robert E.; Day, W. Baldwin

    1984-12-01

    A small millimeter wave (MMW) radiometer sensor has been developed that is adaptable to a wide variety of applications including low-altitude remote sensing for passive surveillance and target detection, navigation aid for aircraft, remote sensing from space platforms and precision terminal guidance and munitions. The radiometer is an environmentally hardened, 35 GHz total-power, periodically calibrated receiver with a measurement range of 0 to 500K and a sensitivity of less than 2K for an output bandwidth of 300 Hz. The basic unit without power supply and antenna has a volume of 20 cubic inches, weighs 1.6 lbs, and requires 7 watts dc power. This paper presents a brief overview of the fundamentals of microwave and MMW radiometry and a description of the advanced sensor, including laboratory test results on several units. Examples of airborne radiometric images are described.

  7. Quantitative Analysis of Spectral Impacts on Silicon Photodiode Radiometers: Preprint

    SciTech Connect

    Myers, D. R.

    2011-04-01

    Inexpensive broadband pyranometers with silicon photodiode detectors have a non-uniform spectral response over the spectral range of 300-1100 nm. The response region includes only about 70% to 75% of the total energy in the terrestrial solar spectral distribution from 300 nm to 4000 nm. The solar spectrum constantly changes with solar position and atmospheric conditions. Relative spectral distributions of diffuse hemispherical irradiance sky radiation and total global hemispherical irradiance are drastically different. This analysis convolves a typical photodiode response with SMARTS 2.9.5 spectral model spectra for different sites and atmospheric conditions. Differences in solar component spectra lead to differences on the order of 2% in global hemispherical and 5% or more in diffuse hemispherical irradiances from silicon radiometers. The result is that errors of more than 7% can occur in the computation of direct normal irradiance from global hemispherical irradiance and diffuse hemispherical irradiance using these radiometers.

  8. A combined radar-radiometer with variable polarization

    NASA Technical Reports Server (NTRS)

    Martin, D. P.

    1972-01-01

    An instrument is described that provides both radar and radiometer data at the same time. The antenna and receiver are time shared for the two sensor functions. The antenna polarization can be electronically scanned at rates up to 5000 changes for both the transmit and receive signal paths. This equipment is to investigate target signatures for remote sensing applications. The function of the equipment is described and the results for observations of asphalt, grass, and gravel surfaces are presented.

  9. ARM Multi-Filter Rotating Shadowband Radiometer (MFRSR): irradiances

    DOE Data Explorer

    Hodges, Gary

    1993-07-04

    The multifilter rotating shadowband radiometer (MFRSR) takes spectral measurements of direct normal, diffuse horizontal and total horizontal solar irradiances. These measurements are at nominal wavelengths of 415, 500, 615, 673, 870, and 940 nm. The measurements are made at a user-specified time interval, usually about one minute or less. The sampling rate for the Atmospheric Radiation Measurement (ARM) Climate Research Facility MFRSRs is 20 seconds. From such measurements, one may infer the atmosphere's optical depth at the wavelengths mentioned above. In turn, these optical depths may be used to derive information about the column abundances of ozone and water vapor (Michalsky et al. 1995), as well as aerosol (Michalsky et al. 1994) and other atmospheric constituents. A silicon detector is also part of the MFRSR. This detector provides a measure of the broadband direct normal, diffuse horizontal and total horizontal solar irradiances. A MFRSR head that is mounted to look vertically downward can measure upwelling spectral irradiances. In the ARM system, this instrument is called a multifilter radiometer (MFR). At the Southern Great Plains (SGP) there are two MFRs; one mounted at the 10-m height and the other at 25 m. At the North Slope of Alaska (NSA) sites, the MFRs are mounted at 10 m. MFRSR heads are also used to measure normal incidence radiation by mounting on a solar tracking device. These are referred to as normal incidence multi-filter radiometers (NIMFRs) and are located at the SGP and NSA sites. Another specialized use for the MFRSR is the narrow field of view (NFOV) instrument located at SGP. The NFOV is a ground-based radiometer (MFRSR head) that looks straight up.

  10. Multifrequency Aperture-Synthesizing Microwave Radiometer System (MFASMR). Volume 1

    NASA Technical Reports Server (NTRS)

    Wiley, C. A.; Chang, M. U.

    1981-01-01

    Background material and a systems analysis of a multifrequency aperture - synthesizing microwave radiometer system is presented. It was found that the system does not exhibit high performance because much of the available thermal power is not used in the construction of the image and because the image that can be formed has a resolution of only ten lines. An analysis of image reconstruction is given. The system is compared with conventional aperture synthesis systems.

  11. Ozone profiles above Kiruna from two ground-based radiometers

    NASA Astrophysics Data System (ADS)

    Ryan, Niall J.; Walker, Kaley A.; Raffalski, Uwe; Kivi, Rigel; Gross, Jochen; Manney, Gloria L.

    2016-09-01

    This paper presents new atmospheric ozone concentration profiles retrieved from measurements made with two ground-based millimetre-wave radiometers in Kiruna, Sweden. The instruments are the Kiruna Microwave Radiometer (KIMRA) and the Millimeter wave Radiometer 2 (MIRA 2). The ozone concentration profiles are retrieved using an optimal estimation inversion technique, and they cover an altitude range of ˜ 16-54 km, with an altitude resolution of, at best, 8 km. The KIMRA and MIRA 2 measurements are compared to each other, to measurements from balloon-borne ozonesonde measurements at Sodankylä, Finland, and to measurements made by the Microwave Limb Sounder (MLS) aboard the Aura satellite. KIMRA has a correlation of 0.82, but shows a low bias, with respect to the ozonesonde data, and MIRA 2 shows a smaller magnitude low bias and a 0.98 correlation coefficient. Both radiometers are in general agreement with each other and with MLS data, showing high correlation coefficients, but there are differences between measurements that are not explained by random errors. An oscillatory bias with a peak of approximately ±1 ppmv is identified in the KIMRA ozone profiles over an altitude range of ˜ 18-35 km, and is believed to be due to baseline wave features that are present in the spectra. A time series analysis of KIMRA ozone for winters 2008-2013 shows the existence of a local wintertime minimum in the ozone profile above Kiruna. The measurements have been ongoing at Kiruna since 2002 and late 2012 for KIMRA and MIRA 2, respectively.

  12. Electromagnetic design of a microwave radiometer antenna system

    NASA Technical Reports Server (NTRS)

    Agrawal, P. K.; Cockrell, C. R.

    1981-01-01

    A preliminary electromagnetic (EM) design of a radiometric antenna system was developed for the microwave radiometer spacecraft mission. The antenna system consists of a large spherical reflector and an array of feed horns along a concentric circular arc in front of the reflector. The reflector antenna was sized to simultaneously produce 200 contiguous 1 km diameter footprints with an overall beam efficiency of 90 percent, and the feed horns and feed horn array were designed to monitor the radiation from the footprints.

  13. Scanning mechanism study for multi-frequency microwave radiometers

    NASA Technical Reports Server (NTRS)

    Shin, I.

    1976-01-01

    Scanning mode for a microwave radiometer having large aperture antenna is determined from scientific needs by engineering tradeoffs. Two configurations of the scan drive mechanism with an integral momentum compensation are formulated for 1.OM and 1.4M diameter antennas. As the formulation is based on currently available components, it is possible to design and fabricate the formulated mechanism without new hardware development. A preliminary specification for major components of formulated drives is also included in the report.

  14. Color coded data obtained by JPL's Shuttle Multispectral Infrared radiometer

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Color coded data obtained from Baja California, Mexico to Texas by JPL's Shuttle Multispectral Infrared radiometer is pictured. The map shows where data was obtained on the 19th orbit of the mission. Yellow and green areas represent water. The first brown segment at left is Baja California, and the second begins at the coast of mainland Mexico and extends into Texas. The dark brown strips at the right are clouds.

  15. Characterization of spectral irradiance system based on a filter radiometer

    NASA Astrophysics Data System (ADS)

    Lima, M. S.; Silva, T. F.; Duarte, I.; Correa, J. S.; Viana, D.; Sousa, W. A.; Almeida, G. B.; Couceiro, I. B.

    2016-07-01

    The spectral irradiance scale has been realized recently. It is based on a filter radiometer that was mounted and characterized. The optical system was assembled and the procedures of the methodology were defined, including the mounting of FEL lamp jig, alignment of the optical system, calibration of the instruments and optical devices used on the experimental system. The main uncertainty components were evaluated and the preliminary uncertainty budget of the spectral irradiance system is presented.

  16. The DC-8 Submillimeter-Wave Cloud Ice Radiometer

    NASA Technical Reports Server (NTRS)

    Walter, Steven; Batelaan, Paul; Siegel, Peter; Evans, K. Franklin; Evans, Aaron; Balachandra, Balu; Gannon, Jade; Guldalian, John; Raz, Guy; Shea, James; Smith, Christopher; Thomassen, John

    2000-01-01

    Submillimeter-wave cloud ice radiometry is an innovative technique for determining the amount of ice present in cirrus clouds, measuring median crystal size, and constraining crystal shape. The radiometer described in this poster is being developed to acquire data to validate radiometric retrievals of cloud ice at submillimeter wavelengths. The goal of this effort is to develop a technique to enable spaceborne characterization of cirrus, meeting key climate modeling and NASA measurement needs.

  17. Analysis of Anechoic Chamber Testing of the Hurricane Imaging Radiometer

    NASA Technical Reports Server (NTRS)

    Fenigstein, David; Ruf, Chris; James, Mark; Simmons, David; Miller, Timothy; Buckley, Courtney

    2010-01-01

    The Hurricane Imaging Radiometer System (HIRAD) is a new airborne passive microwave remote sensor developed to observe hurricanes. HIRAD incorporates synthetic thinned array radiometry technology, which use Fourier synthesis to reconstruct images from an array of correlated antenna elements. The HIRAD system response to a point emitter has been measured in an anechoic chamber. With this data, a Fourier inversion image reconstruction algorithm has been developed. Performance analysis of the apparatus is presented, along with an overview of the image reconstruction algorithm

  18. Adaptive neuro-fuzzy inference system for temperature and humidity profile retrieval from microwave radiometer observations

    NASA Astrophysics Data System (ADS)

    Ramesh, K.; Kesarkar, A. P.; Bhate, J.; Venkat Ratnam, M.; Jayaraman, A.

    2015-01-01

    The retrieval of accurate profiles of temperature and water vapour is important for the study of atmospheric convection. Recent development in computational techniques motivated us to use adaptive techniques in the retrieval algorithms. In this work, we have used an adaptive neuro-fuzzy inference system (ANFIS) to retrieve profiles of temperature and humidity up to 10 km over the tropical station Gadanki (13.5° N, 79.2° E), India. ANFIS is trained by using observations of temperature and humidity measurements by co-located Meisei GPS radiosonde (henceforth referred to as radiosonde) and microwave brightness temperatures observed by radiometrics multichannel microwave radiometer MP3000 (MWR). ANFIS is trained by considering these observations during rainy and non-rainy days (ANFIS(RD + NRD)) and during non-rainy days only (ANFIS(NRD)). The comparison of ANFIS(RD + NRD) and ANFIS(NRD) profiles with independent radiosonde observations and profiles retrieved using multivariate linear regression (MVLR: RD + NRD and NRD) and artificial neural network (ANN) indicated that the errors in the ANFIS(RD + NRD) are less compared to other retrieval methods. The Pearson product movement correlation coefficient (r) between retrieved and observed profiles is more than 92% for temperature profiles for all techniques and more than 99% for the ANFIS(RD + NRD) technique Therefore this new techniques is relatively better for the retrieval of temperature profiles. The comparison of bias, mean absolute error (MAE), RMSE and symmetric mean absolute percentage error (SMAPE) of retrieved temperature and relative humidity (RH) profiles using ANN and ANFIS also indicated that profiles retrieved using ANFIS(RD + NRD) are significantly better compared to the ANN technique. The analysis of profiles concludes that retrieved profiles using ANFIS techniques have improved the temperature retrievals substantially; however, the retrieval of RH by all techniques considered in this paper (ANN, MVLR and

  19. Absolute Income, Relative Income, and Happiness

    ERIC Educational Resources Information Center

    Ball, Richard; Chernova, Kateryna

    2008-01-01

    This paper uses data from the World Values Survey to investigate how an individual's self-reported happiness is related to (i) the level of her income in absolute terms, and (ii) the level of her income relative to other people in her country. The main findings are that (i) both absolute and relative income are positively and significantly…

  20. Investigating Absolute Value: A Real World Application

    ERIC Educational Resources Information Center

    Kidd, Margaret; Pagni, David

    2009-01-01

    Making connections between various representations is important in mathematics. In this article, the authors discuss the numeric, algebraic, and graphical representations of sums of absolute values of linear functions. The initial explanations are accessible to all students who have experience graphing and who understand that absolute value simply…

  1. Preschoolers' Success at Coding Absolute Size Values.

    ERIC Educational Resources Information Center

    Russell, James

    1980-01-01

    Forty-five 2-year-old and forty-five 3-year-old children coded relative and absolute sizes using 1.5-inch, 6-inch, and 18-inch cardboard squares. Results indicate that absolute coding is possible for children of this age. (Author/RH)

  2. Introducing the Mean Absolute Deviation "Effect" Size

    ERIC Educational Resources Information Center

    Gorard, Stephen

    2015-01-01

    This paper revisits the use of effect sizes in the analysis of experimental and similar results, and reminds readers of the relative advantages of the mean absolute deviation as a measure of variation, as opposed to the more complex standard deviation. The mean absolute deviation is easier to use and understand, and more tolerant of extreme…

  3. Monolithically integrated absolute frequency comb laser system

    DOEpatents

    Wanke, Michael C.

    2016-07-12

    Rather than down-convert optical frequencies, a QCL laser system directly generates a THz frequency comb in a compact monolithically integrated chip that can be locked to an absolute frequency without the need of a frequency-comb synthesizer. The monolithic, absolute frequency comb can provide a THz frequency reference and tool for high-resolution broad band spectroscopy.

  4. Estimating the absolute wealth of households

    PubMed Central

    Gerkey, Drew; Hadley, Craig

    2015-01-01

    Abstract Objective To estimate the absolute wealth of households using data from demographic and health surveys. Methods We developed a new metric, the absolute wealth estimate, based on the rank of each surveyed household according to its material assets and the assumed shape of the distribution of wealth among surveyed households. Using data from 156 demographic and health surveys in 66 countries, we calculated absolute wealth estimates for households. We validated the method by comparing the proportion of households defined as poor using our estimates with published World Bank poverty headcounts. We also compared the accuracy of absolute versus relative wealth estimates for the prediction of anthropometric measures. Findings The median absolute wealth estimates of 1 403 186 households were 2056 international dollars per capita (interquartile range: 723–6103). The proportion of poor households based on absolute wealth estimates were strongly correlated with World Bank estimates of populations living on less than 2.00 United States dollars per capita per day (R2 = 0.84). Absolute wealth estimates were better predictors of anthropometric measures than relative wealth indexes. Conclusion Absolute wealth estimates provide new opportunities for comparative research to assess the effects of economic resources on health and human capital, as well as the long-term health consequences of economic change and inequality. PMID:26170506

  5. Absolute optical metrology : nanometers to kilometers

    NASA Technical Reports Server (NTRS)

    Dubovitsky, Serge; Lay, O. P.; Peters, R. D.; Liebe, C. C.

    2005-01-01

    We provide and overview of the developments in the field of high-accuracy absolute optical metrology with emphasis on space-based applications. Specific work on the Modulation Sideband Technology for Absolute Ranging (MSTAR) sensor is described along with novel applications of the sensor.

  6. Radiometer system to map the cosmic background radiation.

    PubMed

    Gorenstein, M V; Muller, R A; Smoot, G F; Tyson, J A

    1978-04-01

    We have developed a 33-GHz airborne radiometer system to map large angular scale variations in the temperature of the 3 K cosmic background radiation. A ferrite circulator switches a room-temperature mixer between two antennas pointing 60 degrees apart in the sky. In 40 min of observing, the radiometer can measure the anisotropy of the microwave background with an accuracy of +/-1 mK rms, or about 1 part in 3000 of 3 K. The apparatus is flown in a U-2 jet to 20 km altitude where 33-GHz thermal microwave emission from the atmosphere is at a low level. A second radiometer, tuned to 54 GHz near oxygen emission lines, monitors spurious signals from residual atmospheric radiation. The antennas, which have an extremely low side-lobe response of less than -65 dB past 60 degrees , reject anisotropic radiation from the earth's surface. Periodic interchange of the antenna positions and reversal of the aircraft's flight direction cancel equipment-based imbalances. The system has been operated successfully in U-2 aircraft flown from NASA-Ames at Moffett Field, CA.

  7. A millimeter-wave radiometer for detecting microbursts

    NASA Technical Reports Server (NTRS)

    Mcmillan, Robert

    1992-01-01

    This paper describes a millimeter-wave radiometer for the detection of wind shear from airborne platforms or at airport terminals. This proposed instrument will operate near the group of atmospheric oxygen absorptions centered near 60 GHz, which it will use to sense temperature from a distance. The instrument will use two channels to provide two different temperature measurements, providing the basis for solution of two equations in two unknowns, which are range to the wind shear plume and its temperature. A third channel will measure ambient atmospheric temperature. Depending on the temperature difference between the wind-shear plume and ambient, the standard deviation of range measurement accuracy is expected to be about 1 km at 5 km range, while the temperature measurement standard deviation will be about one-fourth the temperature difference between plume and ambient at this range. The instrument is expected to perform usefully at ranges up to 10 km, giving adequate warning of the presence of wind shear even for high performance jet aircraft. Other atmospheric hazards which might be detected by this radiometer include aircraft wakes and vortices, clear-air turbulence, and wind rotors, although the latter two phenomena would be detected by an airborne version of the instrument. A separate radiometer channel will be provided in the proposed instrument to detect aircraft wakes and vortices based on perturbation of the spectrum of microscopic atmospheric temperature fluctuations caused by the passage of large aircraft.

  8. Source analysis of spaceborne microwave radiometer interference over land

    NASA Astrophysics Data System (ADS)

    Guan, Li; Zhang, Sibo

    2016-03-01

    Satellite microwave thermal emissions mixed with signals from active sensors are referred to as radiofrequency interference (RFI). Based on Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) observations from June 1 to 16, 2011, RFI over Europe was identified and analyzed using the modified principal component analysis algorithm in this paper. The X band AMSR-E measurements in England and Italy are mostly affected by the stable, persistent, active microwave transmitters on the surface, while the RFI source of other European countries is the interference of the reflected geostationary TV satellite downlink signals to the measurements of spaceborne microwave radiometers. The locations and intensities of the RFI induced by the geostationary TV and communication satellites changed with time within the observed period. The observations of spaceborne microwave radiometers in ascending portions of orbits are usually interfered with over European land, while no RFI was detected in descending passes. The RFI locations and intensities from the reflection of downlink radiation are highly dependent upon the relative geometry between the geostationary satellite and the measuring passive sensor. Only these fields of view of a spaceborne instrument whose scan azimuths are close to the azimuth relative to the geostationary satellite are likely to be affected by RFI.

  9. Correcting airborne scanning infrared radiometer measurements for atmospheric effects

    NASA Technical Reports Server (NTRS)

    Boudreau, R. D.

    1972-01-01

    Two techniques were developed for determining atmospheric corrections from observations made by a scanning radiometer. Both techniques depend on knowing the radiometer's limb function. The limb function for an RS-18 scanning radiometer is derived from calculations made with a radiation model and used to demonstrate the techniques. One technique requires observations made over an isothermal water surface within the area being remotely sensed. The other technique does not depend on an isothermal water surface but requires a boat measurement of radiometric sea surface temperature within the area being remotely sensed. The radiation model used to derive the limb function does not account for the effects of atmospheric particulates on the correction. It is hypothesized that the effect of particulates on the limb function derived in this study is negligible, and therefore the technique essentially obtains the total correction. The techniques developed can be used over land provided that a section of isothermal land exists within the experiment area or that a radiometric measurement of surface temperature is made at the surface.

  10. Radiometer system to map the cosmic background radiation

    NASA Technical Reports Server (NTRS)

    Gorenstein, M. V.; Muller, R. A.; Smoot, G. F.; Tyson, J. A.

    1978-01-01

    A 33-GHz airborne radiometer system has been developed to map large angular scale variations in the temperature of the 3 K cosmic background radiation. A ferrite circulator switches a room-temperature mixer between two antennas pointing 60 deg apart in the sky. In 40 min of observing, the radiometer can measure the anisotropy of the microwave background with an accuracy of plus or minus 1 mK rms, or about 1 part in 3000 of 3 K. The apparatus is flown in a U-2 jet to 20 km altitude where 33-GHz thermal microwave emission from the atmosphere is at a low level. A second radiometer, tuned to 54 GHz near oxygen emission lines, monitors spurious signals from residual atmospheric radiation. The antennas, which have an extremely low side-lobe response of less than -65 dB past 60 deg, reject anisotropic radiation from the earth's surface. Periodic interchange of the antenna positions and reversal of the aircraft's flight direction cancel equipment-based imbalances. The system has been operated successfully in U-2 aircraft flown from NASA-Ames at Moffett Field, Calif.

  11. High performance S-band horn antennas for radiometer use

    NASA Technical Reports Server (NTRS)

    Caldecott, R.; Mentzer, C. A.; Peters, L.; Toth, J.

    1973-01-01

    Horn antennas of four types: pyramidal corrugated, conical corrugated, pyramidal dual mode and conical dual mode, have been constructed and evaluated for use as S-band radiometer antennas. Each of the structures is described and radiation patterns and impedance and resistive loss measurements including a layer of foreign material on a thin radome, are presented. A precision method for determining reflection losses is described using a multiprobe reflectometer technique. The same technique is also applied to the measurement of resistive losses by closing the ends of the antennas with short circuit plates and determining the losses from an accurate measurement of the reflection coefficient. The radiation patterns were recorded with the aid of a real-time digital computer. The stored patterns were then processed to yield gain and beam efficiency. It was concluded that it is possible to design a highly efficient antenna for radiometer use and to measure its parameters precisely. However, it was found that it is necessary to modify the conventional definition of beamwidth somewhat if this term is to be meaningful for radiometer applications.

  12. Thin foil planar radiometers: application for designing contactless ? sensors

    NASA Astrophysics Data System (ADS)

    Gaviot, E.; Godts, P.; Guths, S.; Leclercq, D.

    1996-04-01

    This paper is devoted to describing a new sensor allowing one to measure the net radiant flux exchanged by the wall surface it is mounted on. The device is constructed by mounting a thermopile-type radiometer on a larger thin metallic foil support. When the emissivity of the paint covering the support is the same as that of the wall surface on which the sensor is applied, a direct reading (positive or negative emf) of the radiant flux (absorbed or emitted) by the wall surface is given, whatever the convective losses. The calibration is carried out in a simple and useful apparatus designed to produce a prescribed total radiant exchange between two metallic plates at different temperatures and is estimated to be accurate to within two per cent. Simplicity and ruggedness make the radiometer appropriate for direct measurement of heat exchanged between surfaces heated up to 500 K. Notable applications include use as a traditional total hemispheric radiometer and a contactless temperature difference sensor.

  13. Hydrometeor Profiles Derived from Airborne Radar and Wideband Radiometer Observations

    NASA Technical Reports Server (NTRS)

    Skofronick-Jackson, G. M.; Wang, J. R.; Heymsfield, G.; Hood, R.; Arnold, James E. (Technical Monitor)

    2000-01-01

    A rich dataset was obtained with observations from the MIR (Millimeter-wave Imaging Radiometer, 89, 150, 183.3$\\pm$1, 183.3$\\pm$3,183.3$\\pm$7, and 220 apprx.GHz), the AMPR (Advanced Microwave Precipitation Radiometer, 10.7, 19.35, 37, and 85 approx. GHz), and the EDOP (ER-2 Doppler Radar, 9.6 approx. GHz) on board the ER-2 aircraft during the CAMEX-3/TEFLUN-B (Convection and Moisture Experiment/Texas and Florida Underflights) TRMM (Tropical Rainfall Measuring Mission) field campaign. Measurements over the ocean from these three instruments on 26 August 1998 were used in our iterative retrieval algorithm to estimate hydrometeor drop size profiles, The algorithm attempts to minimize the difference between the observations and forward radiometer and radar calculations based on the estimated profile. The high frequency MIR observations provide detailed information about the high altitude ice microphysics, while the AMPR is mostly used to define liquid hydrometeor characteristics. The EDOP provides an initial estimate of the profile and as a consistency check throughout the iterative cycle. The retrieval algorithm, specific results for convective and anvil cases, and general implications of this work will be presented.

  14. Remote sensing of soil moisture with microwave radiometers

    NASA Technical Reports Server (NTRS)

    Schmugge, T.; Wilheit, T.; Webster, W., Jr.; Gloerson, P.

    1976-01-01

    Results are presented that were derived from measurements made by microwave radiometers during the March 1972 and February 1973 flights of National Aeronautics and Space Administration (NASA) Convair-9900 aircraft over agricultural test sites in the southwestern part of United States. The purpose of the missions was to study the use of microwave radiometers for the remote sensing of soil moisture. The microwave radiometers covered the 0.8- to 21-cm wavelength range. The results show a good linear correlation between the observed microwave brightness temperature and moisture content of the 0- to 1-cm layer of the soil. The results at the largest wavelength (21 cm) show the greatest sensitivity to soil moisture variations and indicate the possibility of sensing these variations through a vegetative canopy. The effect of soil texture on the emission from the soil was also studied and it was found that this effect can be compensated for by expressing soil moisture as a percent of field capacity for the soil. The results were compared with calculations based on a radiative transfer model for layered dielectrics and the agreement is very good at the longer wavelengths. At the shorter wavelengths, surface roughness effects are larger and the agreement becomes poorer.

  15. Absolute instability of the Gaussian wake profile

    NASA Technical Reports Server (NTRS)

    Hultgren, Lennart S.; Aggarwal, Arun K.

    1987-01-01

    Linear parallel-flow stability theory has been used to investigate the effect of viscosity on the local absolute instability of a family of wake profiles with a Gaussian velocity distribution. The type of local instability, i.e., convective or absolute, is determined by the location of a branch-point singularity with zero group velocity of the complex dispersion relation for the instability waves. The effects of viscosity were found to be weak for values of the wake Reynolds number, based on the center-line velocity defect and the wake half-width, larger than about 400. Absolute instability occurs only for sufficiently large values of the center-line wake defect. The critical value of this parameter increases with decreasing wake Reynolds number, thereby indicating a shrinking region of absolute instability with decreasing wake Reynolds number. If backflow is not allowed, absolute instability does not occur for wake Reynolds numbers smaller than about 38.

  16. Total solar irradiance as measured by the SOVAP radiometer onboard PICARD

    NASA Astrophysics Data System (ADS)

    Meftah, Mustapha; Chevalier, André; Conscience, Christian; Nevens, Stijn

    2016-09-01

    From the SOlar VAriability PICARD (SOVAP) space-based radiometer, we obtained a new time series of the total solar irradiance (TSI) during Solar Cycle 24. Based on SOVAP data, we obtained that the TSI input at the top of the Earth's atmosphere at a distance of one astronomical unit from the Sun is 1361.8 ± 2.4 W m-2 (1σ) representative of the 2008 solar minimum period. From 2010 to 2014, the amplitude of the changes has been of the order of ± 0.1%, corresponding to a range of about 2.7 W m-2. To determine the TSI from SOVAP, we present here an improved instrument equation. A parameter was integrated from a theoretical analysis that highlighted the thermo-electrical non-equivalence of the radiometric cavity. From this approach, we obtained values that are lower than those previously provided with the same type of instrument. The results in this paper supersede the previous SOVAP analysis and provide the best SOVAP-based TSI-value estimate and its temporal variation.

  17. The multi-filter rotating shadowband radiometer (MFRSR) - precision infrared radiometer (PIR) platform in Fairbanks: Scientific objectives

    SciTech Connect

    Stamnes, K.; Leontieva, E.

    1996-04-01

    The multi-filter rotating shadowband radiometer (MFRSR) and precision infrared radiometer (PIR) have been employed at the Geophysical Institute in Fairbanks to check their performance under arctic conditions. Drawing on the experience of the previous measurements in the Arctic, the PIR was equipped with a ventilator to prevent frost and moisture build-up. We adopted the Solar Infrared Observing Sytem (SIROS) concept from the Southern Great Plains Cloud and Radiation Testbed (CART) to allow implementation of the same data processing software for a set of radiation and meteorological instruments. To validate the level of performance of the whole SIROS prior to its incorporation into the North Slope of Alaska (NSA) Cloud and Radiation Testbed Site instrumental suite for flux radiatin measurements, the comparison between measurements and model predictions will be undertaken to assess the MFRSR-PIR Arctic data quality.

  18. Ring resonant cavities for spectroscopy

    DOEpatents

    Zare, Richard N.; Martin, Juergen; Paldus, Barbara A.; Xie, Jinchun

    1999-01-01

    Ring-shaped resonant cavities for spectroscopy allow a reduction in optical feedback to the light source, and provide information on the interaction of both s- and p-polarized light with samples. A laser light source is locked to a single cavity mode. An intracavity acousto-optic modulator may be used to couple light into the cavity. The cavity geometry is particularly useful for Cavity Ring-Down Spectroscopy (CRDS).

  19. Ring resonant cavities for spectroscopy

    DOEpatents

    Zare, R.N.; Martin, J.; Paldus, B.A.; Xie, J.

    1999-06-15

    Ring-shaped resonant cavities for spectroscopy allow a reduction in optical feedback to the light source, and provide information on the interaction of both s- and p-polarized light with samples. A laser light source is locked to a single cavity mode. An intracavity acousto-optic modulator may be used to couple light into the cavity. The cavity geometry is particularly useful for Cavity Ring-Down Spectroscopy (CRDS). 6 figs.

  20. An Overview of the Hurricane Imaging Radiometer (HIRAD)

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Accurate observations of ocean surface vector winds (OSVW) with high spatial and temporal resolution are critically important to improve both our understanding and predictability of tropical cyclones. As the successful NASA QuikSCAT satellite continues to age beyond its planned life span, many members of the tropical cyclone research and operational community recognize the need to develop new observational technologies and strategies to meet the essential need for OSVW information. This concern has been expressed in both the "Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond" developed by the National Research Council Committee on Earth Science and Applications from Space and the "Interagency Strategic Research Plan for Tropical Cyclone The Way Ahead" developed by the Joint Action Group for Tropical Cyclone Research (JAG-TCR) sponsored by the Office of the Federal Coordinator for Meteorology. One innovative technology development which offers the potential for new, unique remotely sensed observations of tropical cyclone OSVW and precipitation is the Hurricane Imaging Radiometer (HIRAD). This new instrument is passive microwave synthetic thinned aperture radiometer under development at the NASA Marshall Space Flight Center that will operate at the C-Band frequencies of 4, 5, 6, and 7 GHz. These frequencies have been successfully demonstrated by the NOAA nadir-staring Stepped Frequency Microwave Radiometer (SFMR) as useful for monitoring tropical cyclone ocean surface wind speeds and rain rates from low altitude reconnaissance aircraft. The HIRAD design incorporates a unique antenna design as well as several technologies that have been successfully demonstrated by the University of Michigan Lightweight Rain Radiometer sponsored by NASA Earth Science Technology Office Instrument Incubator Program. HIRAD will be a compact, lightweight, low-power instrument with no moving parts that will produce imagery of ocean wind surface

  1. Fabrication of capacitive absolute pressure sensor using Si-Au eutectic bonding in SOI wafer

    NASA Astrophysics Data System (ADS)

    Ryeol Lee, Kang; Kim, Kunnyun; Park, Hyo-Derk; Kim, Yong Kook; Choi, Seung-Woo; Choi, Woo-Beom

    2006-04-01

    A capacitive absolute pressure sensor was fabricated using a large deflected diaphragm with a sealed vacuum cavity formed by removing handling silicon wafer and oxide layers from a SOI wafer after eutectic bonding of a silicon wafer to the SOI wafer. The deflected displacements of the diaphragm formed by the vacuum cavity in the fabricated sensor were similar to simulation results. Initial capacitance values were about 2.18pF and 3.65pF under normal atmosphere, where the thicknesses of the diaphragm used to fabricate the vacuum cavity were 20 µm and 30 µm, respectively. Also, it was confirmed that the differences of capacitance value from 1000hPa to 5hPa were about 2.57pF and 5.35pF, respectively.

  2. Metasurface external cavity laser

    NASA Astrophysics Data System (ADS)

    Xu, Luyao; Curwen, Christopher A.; Hon, Philip W. C.; Chen, Qi-Sheng; Itoh, Tatsuo; Williams, Benjamin S.

    2015-11-01

    A vertical-external-cavity surface-emitting-laser is demonstrated in the terahertz range, which is based upon an amplifying metasurface reflector composed of a sub-wavelength array of antenna-coupled quantum-cascade sub-cavities. Lasing is possible when the metasurface reflector is placed into a low-loss external cavity such that the external cavity—not the sub-cavities—determines the beam properties. A near-Gaussian beam of 4.3° × 5.1° divergence is observed and an output power level >5 mW is achieved. The polarized response of the metasurface allows the use of a wire-grid polarizer as an output coupler that is continuously tunable.

  3. Video Toroid Cavity Imager

    DOEpatents

    Gerald, II, Rex E.; Sanchez, Jairo; Rathke, Jerome W.

    2004-08-10

    A video toroid cavity imager for in situ measurement of electrochemical properties of an electrolytic material sample includes a cylindrical toroid cavity resonator containing the sample and employs NMR and video imaging for providing high-resolution spectral and visual information of molecular characteristics of the sample on a real-time basis. A large magnetic field is applied to the sample under controlled temperature and pressure conditions to simultaneously provide NMR spectroscopy and video imaging capabilities for investigating electrochemical transformations of materials or the evolution of long-range molecular aggregation during cooling of hydrocarbon melts. The video toroid cavity imager includes a miniature commercial video camera with an adjustable lens, a modified compression coin cell imager with a fiat circular principal detector element, and a sample mounted on a transparent circular glass disk, and provides NMR information as well as a video image of a sample, such as a polymer film, with micrometer resolution.

  4. Multicolor cavity soliton.

    PubMed

    Luo, Rui; Liang, Hanxiao; Lin, Qiang

    2016-07-25

    We show a new class of complex solitary wave that exists in a nonlinear optical cavity with appropriate dispersion characteristics. The cavity soliton consists of multiple soliton-like spectro-temporal components that exhibit distinctive colors but coincide in time and share a common phase, formed together via strong inter-soliton four-wave mixing and Cherenkov radiation. The multicolor cavity soliton shows intriguing spectral locking characteristics and remarkable capability of spectrum management to tailor soliton frequencies, which would be very useful for versatile generation and manipulation of multi-octave spanning phase-locked Kerr frequency combs, with great potential for applications in frequency metrology, optical frequency synthesis, and spectroscopy. PMID:27464131

  5. Metasurface external cavity laser

    SciTech Connect

    Xu, Luyao Curwen, Christopher A.; Williams, Benjamin S.; Hon, Philip W. C.; Itoh, Tatsuo; Chen, Qi-Sheng

    2015-11-30

    A vertical-external-cavity surface-emitting-laser is demonstrated in the terahertz range, which is based upon an amplifying metasurface reflector composed of a sub-wavelength array of antenna-coupled quantum-cascade sub-cavities. Lasing is possible when the metasurface reflector is placed into a low-loss external cavity such that the external cavity—not the sub-cavities—determines the beam properties. A near-Gaussian beam of 4.3° × 5.1° divergence is observed and an output power level >5 mW is achieved. The polarized response of the metasurface allows the use of a wire-grid polarizer as an output coupler that is continuously tunable.

  6. Single-Pole Double-Throw MMIC Switches for a Microwave Radiometer

    NASA Technical Reports Server (NTRS)

    Montes, Oliver; Dawson, Douglas E.; Kangaslahti, Pekka P.

    2012-01-01

    In order to reduce the effect of gain and noise instabilities in the RF chain of a microwave radiometer, a Dicke radiometer topology is often used, as in the case of the proposed surface water and ocean topography (SWOT) radiometer instrument. For this topology, a single-pole double-throw (SPDT) microwave switch is needed, which must have low insertion loss at the radiometer channel frequencies to minimize the overall receiver noise figure. Total power radiometers are limited in accuracy due to the continuous variation in gain of the receiver. High-frequency SPDT switches were developed in the form of monolithic microwave integrated circuits (MMICs) using 75 micron indium phosphide (InP) PIN-diode technology. These switches can be easily integrated into Dicke switched radiometers that utilize microstrip technology.

  7. Re-analysis of the long-term changes of the NIMBUS-7 radiometer and behaviour of total solar irradiance during solar cycle 21

    NASA Astrophysics Data System (ADS)

    Frohlich, C.

    2004-12-01

    Only one radiometer - called Hickey-Frieden (HF) - is within the ERB package on NIMBUS-7 for the measurement of total solar irradiance (TSI) and thus changes due to exposure to solar radiation cannot be directly determined by comparison with a less exposed radiometer on the same spacecraft. The geometry and optical property of the cavity of HF is, however, very similar to the PMO6-type radiometers, it is essentially a copy of it with increased size. For the PMO6V on VIRGO/SOHO two main effects have been identified, a rapid early increase and a slow decrease, normally termed degradation, which can be modelled with a hyperbolic function taking the actual dose into account (Fröhlich, 2003). The corrections used by Fröhlich and Lean (1998) for the composite were based on early results from VIRGO and used simple exponential functions. With the recent results from VIRGO a re-analysis of the long-term behaviour of HF is necessary. The results are not only important for solar radiometry from space, but also to improve the reliability of TSI before the start of ACRIM-I in early 1980. The latter will allow to better quantify the behaviour of solar cycle 21 and to compare it with the two recent ones which differ in several aspects. C. Fröhlich. Long-term behaviour of space radiometers. Metrologia, 40:60--65, 2003. C. Fröhlich and J. Lean. The sun's total irradiance: Cycles and trends in the past two decades and associated climate change uncertainties. Geophys. Res. Lett., 25:4377--4380, 1998.

  8. Microwave radiometer and scatterometer design for the aquarius sea surface Salinity Mission

    NASA Technical Reports Server (NTRS)

    Wilson, William J.; Yueh, Simon H.; Pellerano, Fernando

    2004-01-01

    The measurement of sea surface salinity with L-band microwave radiometers is a very challenging task. Since the L-band brightness temperature variations associated with salinity changes are small, it is necessary to have a very sensitive and stable radiometer. In addition, the corrections for the ocean surface roughness require real time scatterometer measurements. The designs of the Aquarius radiometer and scatterometer are described in this paper.

  9. Absolute magnitudes of trans-neptunian objects

    NASA Astrophysics Data System (ADS)

    Duffard, R.; Alvarez-candal, A.; Pinilla-Alonso, N.; Ortiz, J. L.; Morales, N.; Santos-Sanz, P.; Thirouin, A.

    2015-10-01

    Accurate measurements of diameters of trans- Neptunian objects are extremely complicated to obtain. Radiomatric techniques applied to thermal measurements can provide good results, but precise absolute magnitudes are needed to constrain diameters and albedos. Our objective is to measure accurate absolute magnitudes for a sample of trans- Neptunian objects, many of which have been observed, and modelled, by the "TNOs are cool" team, one of Herschel Space Observatory key projects grantes with ~ 400 hours of observing time. We observed 56 objects in filters V and R, if possible. These data, along with data available in the literature, was used to obtain phase curves and to measure absolute magnitudes by assuming a linear trend of the phase curves and considering magnitude variability due to rotational light-curve. In total we obtained 234 new magnitudes for the 56 objects, 6 of them with no reported previous measurements. Including the data from the literature we report a total of 109 absolute magnitudes.

  10. A New Gimmick for Assigning Absolute Configuration.

    ERIC Educational Resources Information Center

    Ayorinde, F. O.

    1983-01-01

    A five-step procedure is provided to help students in making the assignment absolute configuration less bothersome. Examples for both single (2-butanol) and multi-chiral carbon (3-chloro-2-butanol) molecules are included. (JN)

  11. The Simplicity Argument and Absolute Morality

    ERIC Educational Resources Information Center

    Mijuskovic, Ben

    1975-01-01

    In this paper the author has maintained that there is a similarity of thought to be found in the writings of Cudworth, Emerson, and Husserl in his investigation of an absolute system of morality. (Author/RK)

  12. Design and development of a multibeam 1.4 GHz pushbroom microwave radiometer

    NASA Technical Reports Server (NTRS)

    Lawrence, R. W.; Bailey, M. C.; Harrington, R. F.; Hearn, C. P.; Wells, J. G.; Stanley, W. D.

    1986-01-01

    The design and operation of a multiple beam, digital signal processing radiometer are discussed. The discussion includes a brief description of each major subsystem and an overall explanation of the hardware requirements and operation. A series of flight tests was conducted in which sea-truth sites, as well as an existing radiometer were used to verify the Pushbroom Radiometer performance. The results of these tests indicate that the Pushbroom Radiometer did meet the sensitivity design goal of 1.0 kelvin, and exceeded the accuracy requirement of 2.0 kelvin. Additional performance characteristics and test results are also presented.

  13. Ground registration of data from an airborne Multifrequency Microwave Radiometer (MfMR). [Colby, Kansas

    NASA Technical Reports Server (NTRS)

    Richter, J. C. (Principal Investigator)

    1981-01-01

    The agricultural soil moisture experiment was conducted near Colby, Kansas, in July and August 1978. A portion of the data collected was taken with a five band microwave radiometer. A method of locating the radiometer footprints with respect to a ground based coordinate system is documented. The procedure requires that the airplane's flight parameters along with aerial photography be acquired simultaneously with the radiometer data. The software which documented reads in data from the precision radiation thermometer (PRT Model 5) and attaches the scene temperature to the corresponding multifrequency microwave radiometer data. Listings of the programs used in the registration process are included.

  14. Comparison of Profiling Microwave Radiometer, Aircraft, and Radiosonde Measurements From the Alliance Icing Research Study (AIRS)

    NASA Technical Reports Server (NTRS)

    Reehorst, Andrew L.

    2001-01-01

    Measurements from a profiling microwave radiometer are compared to measurements from a research aircraft and radiosondes. Data compared is temperature, water vapor, and liquid water profiles. Data was gathered at the Alliance Icing Research Study (AIRS) at Mirabel Airport outside Montreal, Canada during December 1999 and January 2000. All radiometer measurements were found to lose accuracy when the radome was wet. When the radome was not wetted, the radiometer was seen to indicate an inverted distribution of liquid water within a cloud. When the radiometer measurements were made at 15 deg. instead of the standard zenith, the measurements were less accurate.

  15. Integrating a Microwave Radiometer into Radar Hardware for Simultaneous Data Collection Between the Instruments

    NASA Technical Reports Server (NTRS)

    McLinden, Matthew; Piepmeier, Jeffrey

    2013-01-01

    The conventional method for integrating a radiometer into radar hardware is to share the RF front end between the instruments, and to have separate IF receivers that take data at separate times. Alternatively, the radar and radiometer could share the antenna through the use of a diplexer, but have completely independent receivers. This novel method shares the radar's RF electronics and digital receiver with the radiometer, while allowing for simultaneous operation of the radar and radiometer. Radars and radiometers, while often having near-identical RF receivers, generally have substantially different IF and baseband receivers. Operation of the two instruments simultaneously is difficult, since airborne radars will pulse at a rate of hundreds of microseconds. Radiometer integration time is typically 10s or 100s of milliseconds. The bandwidth of radar may be 1 to 25 MHz, while a radiometer will have an RF bandwidth of up to a GHz. As such, the conventional method of integrating radar and radiometer hardware is to share the highfrequency RF receiver, but to have separate IF subsystems and digitizers. To avoid corruption of the radiometer data, the radar is turned off during the radiometer dwell time. This method utilizes a modern radar digital receiver to allow simultaneous operation of a radiometer and radar with a shared RF front end and digital receiver. The radiometer signal is coupled out after the first down-conversion stage. From there, the radar transmit frequencies are heavily filtered, and the bands outside the transmit filter are amplified and passed to a detector diode. This diode produces a DC output proportional to the input power. For a conventional radiometer, this level would be digitized. By taking this DC output and mixing it with a system oscillator at 10 MHz, the signal can instead be digitized by a second channel on the radar digital receiver (which typically do not accept DC inputs), and can be down-converted to a DC level again digitally. This

  16. Discrete cavity solitons.

    PubMed

    Peschel, U; Egorov, O; Lederer, F

    2004-08-15

    We derive evolution equations describing light propagation in an array of coupled-waveguide resonators and predict the existence of discrete cavity solitons. We identify stable, unstable, and oscillating solitons by varying the coupling strength between the anticontinuous and the continuous limit. PMID:15357356

  17. Melatonin and Oral Cavity

    PubMed Central

    Cengiz, Murat İnanç; Cengiz, Seda; Wang, Hom-Lay

    2012-01-01

    While initially the oral cavity was considered to be mainly a source of various bacteria, their toxins and antigens, recent studies showed that it may also be a location of oxidative stress and periodontal inflammation. Accordingly, this paper focuses on the involvement of melatonin in oxidative stress diseases of oral cavity as well as on potential therapeutic implications of melatonin in dental disorders. Melatonin has immunomodulatory and antioxidant activities, stimulates the proliferation of collagen and osseous tissue, and acts as a protector against cellular degeneration associated with aging and toxin exposure. Arising out of its antioxidant actions, melatonin protects against inflammatory processes and cellular damage caused by the toxic derivates of oxygen. As a result of these actions, melatonin may be useful as a coadjuvant in the treatment of certain conditions of the oral cavity. However, the most important effect of melatonin seems to result from its potent antioxidant, immunomodulatory, protective, and anticancer properties. Thus, melatonin could be used therapeutically for instance, locally, in the oral cavity damage of mechanical, bacterial, fungal, or viral origin, in postsurgical wounds caused by tooth extractions and other oral surgeries. Additionally, it can help bone formation in various autoimmunological disorders such as Sjorgen syndrome, in periodontal diseases, in toxic effects of dental materials, in dental implants, and in oral cancers. PMID:22792106

  18. Advanced Passive Microwave Radiometer Technology for GPM Mission

    NASA Technical Reports Server (NTRS)

    Smith, Eric A.; Im, Eastwood; Kummerow, Christian; Principe, Caleb; Ruf, Christoper; Wilheit, Thomas; Starr, David (Technical Monitor)

    2002-01-01

    An interferometer-type passive microwave radiometer based on MMIC receiver technology and a thinned array antenna design is being developed under the Instrument Incubator Program (TIP) on a project entitled the Lightweight Rainfall Radiometer (LRR). The prototype single channel aircraft instrument will be ready for first testing in 2nd quarter 2003, for deployment on the NASA DC-8 aircraft and in a ground configuration manner; this version measures at 10.7 GHz in a crosstrack imaging mode. The design for a two (2) frequency preliminary space flight model at 19 and 35 GHz (also in crosstrack imaging mode) has also been completed, in which the design features would enable it to fly in a bore-sighted configuration with a new dual-frequency space radar (DPR) under development at the Communications Research Laboratory (CRL) in Tokyo, Japan. The DPR will be flown as one of two primary instruments on the Global Precipitation Measurement (GPM) mission's core satellite in the 2007 time frame. The dual frequency space flight design of the ERR matches the APR frequencies and will be proposed as an ancillary instrument on the GPM core satellite to advance space-based precipitation measurement by enabling better microphysical characterization and coincident volume data gathering for exercising combined algorithm techniques which make use of both radar backscatter and radiometer attenuation information to constrain rainrate solutions within a physical algorithm context. This talk will discuss the design features, performance capabilities, applications plans, and conical/polarametric imaging possibilities for the LRR, as well as a brief summary of the project status and schedule.

  19. Blackbody Cavity for Calibrations at 200 to 273 K

    NASA Technical Reports Server (NTRS)

    Howell, Dane; Ryan, Robert; Ryan, Jim; Henderson, Doug; Clayton, Larry

    2004-01-01

    A laboratory blackbody cavity has been designed and built for calibrating infrared radiometers used to measure radiant temperatures in the range from about 200 to about 273 K. In this below-room-temperature range, scattering of background infrared radiation from room-temperature surfaces could, potentially, contribute significantly to the spectral radiance of the blackbody cavity, thereby contributing a significant error to the radiant temperature used as the calibration value. The present blackbody cavity is of an established type in which multiple reflections from a combination of conical and cylindrical black-coated walls are exploited to obtain an effective emissivity greater than the emissivity value of the coating material on a flat exposed surface. The coating material in this case is a flat black paint that has an emissivity of approximately of 0.91 in the thermal spectral range and was selected over other, higher-emissivity materials because of its ability to withstand thermal cycling. We found many black coatings cracked and flaked after thermal cycling due to differences in the coefficient of expansion differences. On the basis of theoretical calculations, the effective emissivity is expected to approach 0.999. The cylindrical/conical shell enclosing the cavity is machined from copper, which is chosen for its high thermal conductivity. In use, the shell is oriented vertically, open end facing up, and inserted in a Dewar flask filled with isopropyl alcohol/dry-ice slush. A flange at the open end of the shell is supported by a thermally insulating ring on the lip of the Dewar flask. The slush cools the shell (and thus the black-body cavity) to the desired temperature. Typically, the slush starts at a temperature of about 194 K. The slush is stirred and warmed by bubbling dry air or nitrogen through it, thereby gradually increasing the temperature through the aforementioned calibration range during an interval of several hours. The temperature of the slush

  20. Multichannel infrared fiber optic radiometer for controlled microwave heating

    NASA Astrophysics Data System (ADS)

    Drizlikh, S.; Zur, Albert; Katzir, Abraham

    1990-07-01

    An infrared fiberoptic multichannel radiometer was used for monitoring and controlling the temperature of samples in a microwave heating system. The temperature of water samples was maintained at about 40 °C, with a standard deviation of +/- 0.2°C and a maximum deviation of +/- 0.5°C. The temperature was monitored on the same time at several points on the surface and inside the sample. This novel controlled system is reliable and precise. Such system would be very useful for medical applications such as hypothermia and hyperthermi a.

  1. Compositional Ground Truth of Diviner Lunar Radiometer Observations

    NASA Technical Reports Server (NTRS)

    Greenhagen, B. T.; Thomas, I. R.; Bowles, N. E.; Allen, C. C.; Donaldson Hanna, K. L.; Foote, E. J.; Paige, D. A.

    2012-01-01

    The Moon affords us a unique opportunity to "ground truth" thermal infrared (i.e. 3 to 25 micron) observations of an airless body. The Moon is the most accessable member of the most abundant class of solar system bodies, which includes Mercury, astroids, and icy satellites. The Apollo samples returned from the Moon are the only extraterrestrial samples with known spatial context. And the Diviner Lunar Radiometer (Diviner) is the first instrument to globally map the spectral thermal emission of an airless body. Here we compare Diviner observations of Apollo sites to compositional and spectral measurements of Apollo lunar soil samples in simulated lunar environment (SLE).

  2. Landsat-simulating radiometer for agricultural remote sensing

    NASA Technical Reports Server (NTRS)

    Lemme, G. D.; Westin, F. C.

    1979-01-01

    The reliability of a Landsat-simulating ground-based spectral radiometer for use in agricultural remote sensing was investigated. Significant correlation coefficients in all wavebands except Band 7 were found to exist between Landsat computer compatible tape (CCT) and ground-based radiometric data from several corn fields. No significant correlations were found within data from small grain fields. Combined data from several common agricultural crops yielded significant correlation coefficients in the wavebands most commonly employed in agricultural remote sensing. It was also found that sun angle within certain limits of a given day had minimal effect on ground-based radiometric measurements taken from a fallow and barley field.

  3. Aquarius Radiometer Performance: Early On-Orbit Calibration and Results

    NASA Technical Reports Server (NTRS)

    Piepmeier, Jeffrey R.; LeVine, David M.; Yueh, Simon H.; Wentz, Frank; Ruf, Christopher

    2012-01-01

    The Aquarius/SAC-D observatory was launched into a 657-km altitude, 6-PM ascending node, sun-synchronous polar orbit from Vandenberg, California, USA on June 10, 2011. The Aquarius instrument was commissioned two months after launch and began operating in mission mode August 25. The Aquarius radiometer meets all engineering requirements, exhibited initial calibration biases within expected error bars, and continues to operate well. A review of the instrument design, discussion of early on-orbit performance and calibration assessment, and investigation of an on-going calibration drift are summarized in this abstract.

  4. COBE Differential Microwave Radiometer (DMR) data processing techniques

    NASA Technical Reports Server (NTRS)

    Jackson, P. D.; Smoot, G. F.; Bennett, C. L.; Aymon, J.; Backus, C.; Deamici, G.; Hinshaw, G.; Keegstra, P. B.; Kogut, A.; Lineweaver, C.

    1992-01-01

    The purpose of the Differential Microwave Radiometer (DMR) experiment on the Cosmic Background Explorer (COBE) satellite is to make whole-sky maps, at frequencies of 31.5, 53, and 90 GHz, of any departures of the Cosmic Microwave Background (CMB) from its mean value of 2.735 K. An elaborate software system is necessary to calibrate and invert the differential measurements, so as to make sky maps free from large scale systematic errors to levels less than a millionth of the CMB.

  5. First results from the large probe infrared radiometer experiment.

    PubMed

    Boese, R W; Pollack, J B; Silvaggio, P M

    1979-02-23

    During the descent to the surface of Venus, the large probe infrared radiometer measured the net thermal radiative flux in several spectral bandpasses. Preliminary analysis has permitted us to estimate (i) the infrared extinction coefficient profile attributable to aerosols, with respect to their visible profile, in the upper atmosphere of Venus and (ii) the water vapor mixing ratio below the clouds. An indication of the composition of a multicomponent cloud is seen in the data from the spectral bandpass from 6 to 7 micrometers.

  6. Conversion of sunflower multiband radiometer polarization measurements to polarization parameters

    NASA Technical Reports Server (NTRS)

    Biehl, Larry L.

    1995-01-01

    The data processing analysis and conversion of polarization measurements to polarization parameters from the Sunflower multiband radiometer is presented in this final report. Included is: (1) the actual data analysis; (2) the comparison of the averaging techniques and the percent polarization derived from the original and averaged I, Q, U parameters; (3) the polarizer angles used in conversion; (4) the Matlab files; (5) the relative ground size, field of view location, and view zenith angles, and (6) the summary of all the sky data for all dates.

  7. A new broadband square law detector. [microwave radiometers

    NASA Technical Reports Server (NTRS)

    Reid, M. S.; Gardner, R. A.; Stelzried, C. T.

    1975-01-01

    A broadband constant law detector was developed for precision power measurements, radio metric measurements, and other applications. It has a wide dynamic range and an accurate square law response. Other desirable characteristics, which are all included in a single compact unit, are: (1) high-level dc output with immunity to ground loop problems; (2) fast response times; (3) ability to insert known time constants; and (4) good thermal stability. The detector and its performance are described in detail. The detector can be operated in a programmable system with a ten-fold increase in accuracy. The use and performance of the detector in a noise-adding radiometer system is also discussed.

  8. Controller for the Electronically Scanned Thinned Array Radiometer (ESTAR) instrument

    NASA Technical Reports Server (NTRS)

    Zomberg, Brian G.; Chren, William A., Jr.

    1994-01-01

    A prototype controller for the ESTAR (electronically scanned thinned array radiometer) instrument has been designed and tested. It manages the operation of the digital data subsystem (DDS) and its communication with the Small Explorer data system (SEDS). Among the data processing tasks that it coordinates are FEM data acquisition, noise removal, phase alignment and correlation. Its control functions include instrument calibration and testing of two critical subsystems, the output data formatter and Walsh function generator. It is implemented in a Xilinx XC3064PC84-100 field programmable gate array (FPGA) and has a maximum clocking frequency of 10 MHz.

  9. Four band differential radiometer for monitoring LNG vapors

    NASA Technical Reports Server (NTRS)

    Simmonds, J. J.

    1981-01-01

    The development by JPL of a four band differential radiometer (FBDR) which is capable of providing a fast rate of response, accurate measurements of methane, ethane, and propane concentrations on the periphery of a dispersing LNG cloud. The FBDR is a small, low power, lightweight, portable instrument system that uses differential absorption of near infrared radiation by the LNG cloud as a technique for the determination of concentration of the three gases as the LNG cloud passes the instrument position. Instrument design and data analysis approaches are described. The data obtained from the FBDR prototype instrument system deployed in an instrument array during two 40 cubic meter spill tests are discussed.

  10. Altimeter and radiometer for a Venus orbiter mission

    NASA Technical Reports Server (NTRS)

    Bryan, J. W.; Richter, K. R.

    1971-01-01

    The concept, constraints, and capabilities of a radar altimeter type contour mapper for a Venus orbiter mission are presented. The system was developed for the proposed planetary explorer universal bus concept. A system with a height precision of 30meters over a surface area of 7200 square kilometers is achieved. Using this system and the orbit proposed in the orbiting bus concept, the northern hemisphere of Venus is mapped in one Venus day. The radar receiver system, is used in a radiometer mode to obtain a map of the diurnal and logitudinal variations of the Venus surface temperature with a resolution of 3.0 degrees Kelvin.

  11. A Novel Miniature Wide-band Radiometer for Space Applications

    NASA Astrophysics Data System (ADS)

    Sykulska-Lawrence, Hanna

    2016-10-01

    Design, development and testing of a novel miniaturised infrared radiometer is described. The instrument opens up new possibilities in planetary science of deployment on smaller platforms – such as unmanned aerial vehicles and microprobes – to enable study of a planet's radiation balance, as well as terrestrial volcano plumes and trace gases in planetary atmospheres, using low-cost long-term observations. Thus a key enabling development is that of miniaturised, low-power and well-calibrated instrumentation.The paper reports advances in miniature technology to perform high accuracy visible / IR remote sensing measurements. The infrared radiometer is akin to those widely used for remote sensing for earth and space applications, which are currently either large instruments on orbiting platforms or medium-sized payloads on balloons. We use MEMS microfabrication techniques to shrink a conventional design, while combining the calibration benefits of large (>1kg) type radiometers with the flexibility and portability of a <10g device. The instrument measures broadband (0.2 to 100um) upward and downward radiation fluxes, with built-in calibration capability, incorporating traceability to temperature standards such as ITS-90.The miniature instrument described here was derived from a concept developed for a European Space Agency study, Dalomis (Proc. of 'i-SAIRAS 2005', Munich, 2005), which involved dropping multiple probes into the atmosphere of Venus from a balloon to sample numerous parts of the complex weather systems on the planet. Data from such an in-situ instrument would complement information from a satellite remote sensing instrument or balloon radiosonde. Moreover, the addition of an internal calibration standard facilitates comparisons between datasets.One of the main challenges for a reduced size device is calibration. We use an in-situ method whereby a blackbody source is integrated within the device and a micromirror switches the input to the detector

  12. Microwave Radiometer/Scatterometer and Altimeter - Skylab Experiment S193

    NASA Technical Reports Server (NTRS)

    1970-01-01

    This 1970 photograph shows Skylab's Microwave Radiometer/Scatterometer and Altimeter, one of the major components for an Earth Resources Experiment Package (EREP). It was designed to study varying ocean surface, soil erosion, sea and lake ice, snow cover, seasonal vegetational changes, flooding, rainfall and soil types. The overall purpose of the EREP was to test the use of sensors that operated in the visible, infrared, and microwave portions of the electromagnetic spectrum to monitor and study Earth resources. The Marshall Space Flight Center had program management responsibility for the development of Skylab hardware and experiments.

  13. Application of microwave radiometers for wetlands and estuaries monitoring

    SciTech Connect

    Shutko, A.; Haldin, A.; Novichikhin, E.

    1997-06-01

    This paper presents the examples of experimental data obtained with airborne microwave radiometers used for monitoring of wetlands and estuaries located in coastal environments. The international team of researchers has successfully worked in Russia, Ukraine and USA. The data presented relate to a period of time between 1990 and 1995. They have been collected in Odessa Region, Black Sea coast, Ukraine, in Regions of Pittsville and Winfield, Maryland, USA, and in Region of St. Marks, Florida, USA. The parameters discussed are a soil moisture, depth to a shallow water table, vegetation index, salinity of water surface.

  14. COBE DMR results and implications. [Differential Microwave Radiometer

    NASA Technical Reports Server (NTRS)

    Smoot, George F.

    1992-01-01

    This lecture presents early results obtained from the first six months of measurements of the Cosmic Microwave Background (CMB) by Differential Microwave Radiometers (DMR) aboard COBE and discusses significant cosmological implications. The DMR maps show the dipole anisotropy and some galactic emission but otherwise a spatially smooth early universe. The measurements are sufficiently precise that we must pay careful attention to potential systematic errors. Maps of galactic and local emission such as those produced by the FIRAS and DIRBE instruments will be needed to identify foregrounds from extragalactic emission and thus to interpret the results in terms of events in the early universe. The current DMR results are significant for Cosmology.

  15. Electrically scanning microwave radiometers. [for satellite-borne remote sensing

    NASA Technical Reports Server (NTRS)

    Mix, R. F.

    1974-01-01

    The electrically scanning microwave radiometer (ESMR) developed for and currently used onboard the Nimbus 5 meteorological satellite is described, along with the ESMR developed for the Nimbus F satellite. They serve for synoptic mapping of microwave emissions from the earth's surface, the instrument on Nimbus 5 measuring these emissions at a wavelength of 1.55 cm (19.35 GHz) and the instrument on Nimbus F, at a wavelength of 0.81 cm (37 GHz). Radiative transfer characteristics measured at these wavelengths are sufficiently different from IR measurements to permit derivation and interpretation of unique meteorological, geomorphological, and oceanographic data.

  16. Diagnosis Of A Pressure-Modulator-Radiometer Cell

    NASA Technical Reports Server (NTRS)

    May, Randy D.; Mccleese, Daniel J.; Rider, David M.; Schofield, John T.; Webster, Christopher

    1990-01-01

    Spectral response of pressure-modulator-radiometer cell measured with help of lead-salt tunable diode laser. Laser chosen because of narrow bandwidths {2 x 10 to negative 4th power (cm) to negative 1st power} and relatively high powers (up to 1 mW continuous) of such lasers and because available for wavelengths from 3 to 30 micrometers. Direct measurement of spectral response enables formulation of more-precise atmospheric-transmission functions, enabling extraction of better information from readings taken with instrument.

  17. Broadband cavity electromagnetically induced transparency

    SciTech Connect

    Wei Xiaogang; Wang Yanhua; Zhang Jiepeng; Zhu Yifu

    2011-10-15

    Cavity electromagnetically induced transparency (EIT) is created in a three-level atomic system confined in a cavity and coupled to a free-space control laser and is manifested as a narrow transmission peak of a probe laser coupled into the cavity mode and tuned to the two-photon Raman resonance with the control laser. Cavity EIT can be observed with a control laser detuned from the atomic transition frequency in a range limited by the vacuum Rabi splitting of two cavity-atom normal modes. This leads to the broadband cavity EIT obtained in the coupled-cavity-atom system with a free-space, broadband control laser. We report an experimental observation of broadband cavity EIT in cold Rb atoms with a frequency-modulated control laser and discuss its application in multichannel and multifrequency light memory.

  18. Hollow waveguide cavity ringdown spectroscopy

    NASA Technical Reports Server (NTRS)

    Dreyer, Chris (Inventor); Mungas, Greg S. (Inventor)

    2012-01-01

    Laser light is confined in a hollow waveguide between two highly reflective mirrors. This waveguide cavity is used to conduct Cavity Ringdown Absorption Spectroscopy of loss mechanisms in the cavity including absorption or scattering by gases, liquid, solids, and/or optical elements.

  19. Jasminum flexile flower absolute from India--a detailed comparison with three other jasmine absolutes.

    PubMed

    Braun, Norbert A; Kohlenberg, Birgit; Sim, Sherina; Meier, Manfred; Hammerschmidt, Franz-Josef

    2009-09-01

    Jasminum flexile flower absolute from the south of India and the corresponding vacuum headspace (VHS) sample of the absolute were analyzed using GC and GC-MS. Three other commercially available Indian jasmine absolutes from the species: J. sambac, J. officinale subsp. grandiflorum, and J. auriculatum and the respective VHS samples were used for comparison purposes. One hundred and twenty-one compounds were characterized in J. flexile flower absolute, with methyl linolate, benzyl salicylate, benzyl benzoate, (2E,6E)-farnesol, and benzyl acetate as the main constituents. A detailed olfactory evaluation was also performed.

  20. Infrared fibers for radiometer thermometry in hypothermia and hyperthermia treatment

    SciTech Connect

    Katzir, A.; Bowman, H.F.; Asfour, Y.; Zur, A.; Valeri, C.R.

    1989-06-01

    Hypothermia is a condition which results from prolonged exposure to a cold environment. Rapid and efficient heating is needed to rewarm the patient from 32-35 degrees C to normal body temperature. Hyperthermia in cancer treatment involves heating malignant tumors to 42.5-43.0 degrees C for an extended period (e.g., 30 min) in an attempt to obtain remission. Microwave or radio frequency heating is often used for rewarming in hypothermia or for temperature elevation in hyperthermia treatment. One severe problem with such heating is the accurate measurement and control of temperature in the presence of a strong electromagnetic field. For this purpose, we have developed a fiberoptic radiometer system which is based on a nonmetallic, infrared fiber probe, which can operate either in contact or noncontact mode. In preliminary investigations, the radiometer worked well in a strong microwave or radiofrequency field, with an accuracy of +/- 0.5 degrees C. This fiberoptic thermometer was used to control the surface temperature of objects within +/- 2 degrees C.

  1. Infrared Fiber Radiometer For Thermometry In Electromagnetic Induced Therapeutic Healing

    NASA Astrophysics Data System (ADS)

    Katzir, A.; Bowman, F.; Asfour, Y.; Zur, A.; Valeri, C. R.

    1988-06-01

    Hypothermia is a condition which results from prolonged exposure to a cold environment. Rapid and efficient heating is needed to rewarm the patient from 32-35°C to normal body temperature. Hyperthermia in cancer treatment involves heating malignant tumors to 42.5-43.0°C for an extended period (e.g. 30 min.) in an attempt to obtain remission. Microwave or radio frequency heating is often used for rewarming in hypothermia or for temperature elevation in hyperthermia treatment. One severe problem with such heating is the accurate measurement and control of temperature in the presence of a strong electro-magnetic field. For this purpose we have developed a fiberoptic radiometer system which is based on a non-metallic, infrared fiber probe, which can operate either in contact or in non-contact modes. In preliminary investigations the radiometer worked well in a strong microwave or radiofrequency field, with an accuracy of ±0.5°C.

  2. Fact Checking LIGO's Radiometer Code with Simulated LIGO Data.

    NASA Astrophysics Data System (ADS)

    Thrush, Samantha Elaine

    2015-01-01

    Gravitational waves are predicted by various models, ranging from cosmological sources to astrophysical objects. One example of an astrophysical source is a neutron star in a binary system. The strongest example of this is from Scorpios X-1. A key set of instruments that are used to search for gravitational waves are the LIGO detectors. As the signal strength is expected to be small relative to the background noise from a single LIGO detector, data from two detectors are cross-correlated to increase sensitivity to any potential gravitational waves. In order to test the effectiveness of the cross-correlation 'radiometer' code in detecting point sources similar to Scorpius X-1, the code was modified to have the capability to add multiple simulated pulsar signals. To validate the changes to the radiometer code, two trials were run. The first trial compared results from simulated data read in through previously existing means with simulated data read in through the modified code. The second trial read in realistic LIGO data through the traditional means and explored the effects of adding simulated data via the modified code. Once the modified code has completed its vetting, it will be used to ascertain how well injected signals can be recovered when they fall on the border between frequency bins. After running multiple trials with different frequency shifts, the amount of attenuation found for each bin shift agrees with theory, and it was found that the bin shifting does have the ability to completely attenuate signals at higher frequencies.

  3. ECE RADIOMETER UPGRADE ON THE DIII-D TOKAMAK

    SciTech Connect

    AUSTIN, ME; LOHR, J

    2002-08-01

    OAK A271 ECE RADIOMETER UPGRADE ON THE DIII-D TOKAMAK. The electron cyclotron emission (ECE) heterodyne radiometer diagnostic on DIII-D has been upgraded with the addition of eight channels for a total of 40. The new, higher frequency channels allow measurements of electron temperature into the magnetic axis in discharges at maximum field, 2.15 T. The complete set now extends over the full usable range of second harmonic emission frequencies at 2.0 T covering radii from the outer edge inward to the location of third harmonic overlap on the high field side. Full coverage permits the measurement of heat pulses and magnetohydrodynamic (MHD) fluctuations on both sides of the magnetic axis. In addition, the symmetric measurements are used to fix the location of the magnetic axis in tokamak magnetic equilibrium reconstructions. Also, the new higher frequency channels have been used to determine central T{sub e} with good time resolution in low field, high density discharges using third harmonic ECE in the optically gray and optically thick regimes.

  4. First national intercomparison of solar ultraviolet radiometers in Italy

    NASA Astrophysics Data System (ADS)

    Diémoz, H.; Siani, A. M.; Casale, G. R.; di Sarra, A.; Serpillo, B.; Petkov, B.; Scaglione, S.; Bonino, A.; Facta, S.; Fedele, F.; Grifoni, D.; Verdi, L.; Zipoli, G.

    2011-05-01

    A blind intercomparison of ground-based ultraviolet (UV) instruments has been organized for the first time in Italy. The campaign was coordinated by the Environmental Protection Agency of Aosta Valley (ARPA Valle d'Aosta) and took place in Saint-Christophe (45.8° N, 7.4° E, 570 m a.s.l.), in the Alpine region, from 8 to 23 June 2010. It involved 8 institutions, 10 broadband radiometers, 2 filter radiometers and 2 spectroradiometers. Synchronized measurements of downward global solar UV irradiance at the ground were collected and the raw series were then individually processed by the respective operators on the basis of their own procedures and calibration data. The comparison was performed in terms of global solar UV Index and integrated UV-A irradiance against a well-calibrated double monochromator spectroradiometer as reference. An improved algorithm for comparing broadband data and spectra has been developed. For some instruments, we found average deviations ranging from -16 % up to 20 % relative to the reference and diurnal variations as large as 15 % even in clear days. Remarkable deviations also arose from instruments recently in operation and never involved in field intercomparison.

  5. First national intercomparison of solar ultraviolet radiometers in Italy

    NASA Astrophysics Data System (ADS)

    Diémoz, H.; Siani, A. M.; Casale, G. R.; di Sarra, A.; Serpillo, B.; Petkov, B.; Scaglione, S.; Bonino, A.; Facta, S.; Fedele, F.; Grifoni, D.; Verdi, L.; Zipoli, G.

    2011-08-01

    A blind intercomparison of ground-based ultraviolet (UV) instruments has been organized for the first time in Italy. The campaign was coordinated by the Environmental Protection Agency of Aosta Valley (ARPA Valle d'Aosta) and took place in Saint-Christophe (45.8° N, 7.4° E, 570 m a.s.l.), in the Alpine region, from 8 to 23 June 2010. It involved 8 institutions, 10 broadband radiometers, 2 filter radiometers and 2 spectroradiometers. Synchronized measurements of downward global solar UV irradiance at the ground were collected and the raw series were then individually processed by the respective operators on the base of their own procedures and calibration data. A radiative transfer model was successfully applied as an interpretative tool. The input parameters and output results are described in detail. The comparison was performed in terms of global solar UV Index and integrated UV-A irradiance against a well-calibrated double monochromator spectroradiometer as reference. An improved algorithm for comparing broadband data and spectra has been developed and is discussed in detail. For some instruments, we found average deviations ranging from -16 % up to 20 % relative to the reference and diurnal variations as large as 15 % even in clear days. Remarkable deviations were found for the instruments calibrated in the manufacturers' facilities and never involved in field intercomparison. Finally, some recommendations to the UV operators based on the campaign results are proposed.

  6. SIMBAD: a field radiometer for satellite ocean-color validation.

    PubMed

    Deschamps, Pierre-Yves; Fougnie, Bertrand; Frouin, Robert; Lecomte, Pierre; Verwaerde, Christian

    2004-07-10

    A hand-held radiometer, called SIMBAD, has been designed and built specifically for evaluating satellite-derived ocean color. It provides information on the basic ocean-color variables, namely aerosol optical thickness and marine reflectance, in five spectral bands centered at 443, 490, 560, 670, and 870 nm. Aerosol optical thickness is obtained by viewing the Sun disk and measuring the direct atmospheric transmittance. Marine reflectance is obtained by viewing the ocean surface and measuring the upwelling radiance through a vertical polarizer in a geometry that minimizes glitter and reflected sky radiation, i.e., at 45 degrees from nadir (near the Brewster angle) and at 135 degrees in azimuth from the Sun's principal plane. Relative inaccuracy on marine reflectance, established theoretically, is approximately 6% at 443 and 490 nm, 8% at 560 nm, and 23% at 670 nm for case 1 waters containing 0.1 mg m(-3) of chlorophyll a. Measurements by SIMBAD and other instruments during the Second Aerosol Characterization Experiment, the Aerosols-99 Experiment, and the California Cooperative Oceanic Fisheries Investigations cruises agree within uncertainties. The radiometer is compact, light, and easy to operate at sea. The measurement protocol is simple, allowing en route measurements from ships of opportunity (research vessels and merchant ships) traveling the world's oceans.

  7. Modeling the frequency response of microwave radiometers with QUCS

    NASA Astrophysics Data System (ADS)

    Zonca, A.; Roucaries, B.; Williams, B.; Rubin, I.; D'Arcangelo, O.; Meinhold, P.; Lubin, P.; Franceschet, C.; Jahn, S.; Mennella, A.; Bersanelli, M.

    2010-12-01

    Characterization of the frequency response of coherent radiometric receivers is a key element in estimating the flux of astrophysical emissions, since the measured signal depends on the convolution of the source spectral emission with the instrument band shape. Laboratory Radio Frequency (RF) measurements of the instrument bandpass often require complex test setups and are subject to a number of systematic effects driven by thermal issues and impedance matching, particularly if cryogenic operation is involved. In this paper we present an approach to modeling radiometers bandpasses by integrating simulations and RF measurements of individual components. This method is based on QUCS (Quasi Universal Circuit Simulator), an open-source circuit simulator, which gives the flexibility of choosing among the available devices, implementing new analytical software models or using measured S-parameters. Therefore an independent estimate of the instrument bandpass is achieved using standard individual component measurements and validated analytical simulations. In order to automate the process of preparing input data, running simulations and exporting results we developed the Python package python-qucs and released it under GNU Public License. We discuss, as working cases, bandpass response modeling of the COFE and Planck Low Frequency Instrument (LFI) radiometers and compare results obtained with QUCS and with a commercial circuit simulator software. The main purpose of bandpass modeling in COFE is to optimize component matching, while in LFI they represent the best estimation of frequency response, since end-to-end measurements were strongly affected by systematic effects.

  8. SIMBAD: A Field Radiometer for Satellite Ocean-Color Validation

    NASA Astrophysics Data System (ADS)

    Deschamps, Pierre-Yves; Fougnie, Bertrand; Frouin, Robert; Lecomte, Pierre; Verwaerde, Christian

    2004-07-01

    A hand-held radiometer, called SIMBAD, has been designed and built specifically for evaluating satellite-derived ocean color. It provides information on the basic ocean-color variables, namely aerosol optical thickness and marine reflectance, in five spectral bands centered at 443, 490, 560, 670, and 870 nm. Aerosol optical thickness is obtained by viewing the Sun disk and measuring the direct atmospheric transmittance. Marine reflectance is obtained by viewing the ocean surface and measuring the upwelling radiance through a vertical polarizer in a geometry that minimizes glitter and reflected sky radiation, i.e., at 45° from nadir (near the Brewster angle) and at 135° in azimuth from the Sun's principal plane. Relative inaccuracy on marine reflectance, established theoretically, is approximately 6% at 443 and 490 nm, 8% at 560 nm, and 23% at 670 nm for case 1 waters containing 0.1 mg m^-3 of chlorophyll a. Measurements by SIMBAD and other instruments during the Second Aerosol Characterization Experiment, the Aerosols-99 Experiment, and the California Cooperative Oceanic Fisheries Investigations cruises agree within uncertainties. The radiometer is compact, light, and easy to operate at sea. The measurement protocol is simple, allowing en route measurements from ships of opportunity (research vessels and merchant ships) traveling the world's oceans.

  9. SIMBAD: a field radiometer for satellite ocean-color validation.

    PubMed

    Deschamps, Pierre-Yves; Fougnie, Bertrand; Frouin, Robert; Lecomte, Pierre; Verwaerde, Christian

    2004-07-10

    A hand-held radiometer, called SIMBAD, has been designed and built specifically for evaluating satellite-derived ocean color. It provides information on the basic ocean-color variables, namely aerosol optical thickness and marine reflectance, in five spectral bands centered at 443, 490, 560, 670, and 870 nm. Aerosol optical thickness is obtained by viewing the Sun disk and measuring the direct atmospheric transmittance. Marine reflectance is obtained by viewing the ocean surface and measuring the upwelling radiance through a vertical polarizer in a geometry that minimizes glitter and reflected sky radiation, i.e., at 45 degrees from nadir (near the Brewster angle) and at 135 degrees in azimuth from the Sun's principal plane. Relative inaccuracy on marine reflectance, established theoretically, is approximately 6% at 443 and 490 nm, 8% at 560 nm, and 23% at 670 nm for case 1 waters containing 0.1 mg m(-3) of chlorophyll a. Measurements by SIMBAD and other instruments during the Second Aerosol Characterization Experiment, the Aerosols-99 Experiment, and the California Cooperative Oceanic Fisheries Investigations cruises agree within uncertainties. The radiometer is compact, light, and easy to operate at sea. The measurement protocol is simple, allowing en route measurements from ships of opportunity (research vessels and merchant ships) traveling the world's oceans. PMID:15285097

  10. Calibration and Image Reconstruction for the Hurricane Imaging Radiometer (HIRAD)

    NASA Technical Reports Server (NTRS)

    Ruf, Christopher; Roberts, J. Brent; Biswas, Sayak; James, Mark W.; Miller, Timothy

    2012-01-01

    The Hurricane Imaging Radiometer (HIRAD) is a new airborne passive microwave synthetic aperture radiometer designed to provide wide swath images of ocean surface wind speed under heavy precipitation and, in particular, in tropical cyclones. It operates at 4, 5, 6 and 6.6 GHz and uses interferometric signal processing to synthesize a pushbroom imager in software from a low profile planar antenna with no mechanical scanning. HIRAD participated in NASA s Genesis and Rapid Intensification Processes (GRIP) mission during Fall 2010 as its first science field campaign. HIRAD produced images of upwelling brightness temperature over a aprox 70 km swath width with approx 3 km spatial resolution. From this, ocean surface wind speed and column averaged atmospheric liquid water content can be retrieved across the swath. The calibration and image reconstruction algorithms that were used to verify HIRAD functional performance during and immediately after GRIP were only preliminary and used a number of simplifying assumptions and approximations about the instrument design and performance. The development and performance of a more detailed and complete set of algorithms are reported here.

  11. Surface and atmosphere parameter maps from earth-orbiting radiometers

    NASA Technical Reports Server (NTRS)

    Gloersen, P.

    1976-01-01

    Earlier studies have shown that an earth-orbiting electrically scanned microwave radiometer (ESMR) is capable of inferring the extent, concentration, and age of sea ice; the extent, concentration, and thickness of lake ice; rainfall rates over oceans; surface wind speeds over open water; particle size distribution in the deep snow cover of continental ice sheets; and soil moisture content in unvegetated fields. Most other features of the surface of the earth and its atmosphere require multispectral imaging techniques to unscramble the combined contributions of the atmosphere and the surface. Multispectral extraction of surface parameters is analyzed on the basis of a pertinent equation in terms of the observed brightness temperature, the emissivity of the surface which depends on wavelength and various parameters, the sensible temperature of the surface, and the total atmospheric opacity which is also wavelength dependent. Implementation of the multispectral technique is examined. Properties of the surface of the earth and its atmosphere to be determined from a scanning multichannel microwave radiometer are tabulated.

  12. L-Band Radiometer Measurements of Conifer Forests

    NASA Technical Reports Server (NTRS)

    Lang, R.; LeVine, D.; Chauhan, N.; deMatthaeis, P.; Bidwell, S.; Haken, M.

    2000-01-01

    Airborne radiometer measurements have been made at L-band over conifer forests in Virginia to study radiometric response to biomass and soil moisture. The horizontally polarized synthetic aperture radiometer, ESTAR, has been deployed abroad a NASA-P3 aircraft which is based at the Goddard Space Flight Center's Wallops Flight Facility. The instrument has been mounted in the bomb bay of the P-3 and images data in the cross track direction. Aircraft and surface measurements were made in July, August and November of 1999 over relatively homogeneous conifer stands of varying biomass. The surface measurements included soil moisture measurements in several stands. The soil moisture was low during the July flight and highest in November after heavy rains had occurred. The microwave images clearly distinguished between the different forest stands. Stand age, obtained from International Paper Corporation which owns the stands, showed a strong correlation between brightness temperature and stand age. This agrees with previous simulation studies of conifer forests which show that the brightness temperature increases with increasing stand biomass. Research is continuing to seek a quantitative correlation between the observed brightness temperature of the stands and their biomass and surface soil moisture.

  13. Design and fabrication of the Infrared Spectral Imaging Radiometer (ISIR)

    NASA Astrophysics Data System (ADS)

    Hoffman, James W.; Grush, Ronald C.

    1997-09-01

    The design and fabrication of the infrared spectral imaging radiometer (ISIR) is presented. The ISIR was designed in 1994 to provide calibrated images in four thermal wavelength bands without cryogenic cooling by utilizing the new, uncooled microbolometer detector technology. The complete system was fabricated at Space Instruments, Inc. (SI) in 1995 and 1996 and delivered to NASA Goddard Space Flight Center (GSFC) for flight on the space shuttle in 1997. Photographs of the flight hardware are shown. The ISIR operates in a pushbroom fashion and utilizes real time, digital time delay and integration (TDI) to improve the signal to noise ratio. From a nominal shuttle altitude of 140 nmi, the nadir pixel subtends 240 by 240 meters on the ground. The size of the radiometer is minimized by the elimination of mechanical scan mechanisms and a space radiator. The ISIR instrument utilizes a through-the- optics calibration system to periodically obtain a two-point calibration for each pixel in the detector array. A blackbody with both heating and cooling capability is used to obtain accurate calibration data for both terrestrial and cloudtop measurements. The timeline logic, TDI integration, mechanism control, calibration, and data formatting are performed in the onboard digital processor which utilizes two microprocessors and seven programmable logic devices. The output data is recorded on two, 8 mm tape recorders.

  14. Characterization of the Earth Radiation Budget Experiment radiometers

    NASA Technical Reports Server (NTRS)

    Lee, R. B., III; Barkstrom, B. R.

    1991-01-01

    The Earth Radiation Budget Experiment (ERBE) scanning radiometers were used to measure the earth's radiation fields during the period November 1984 through February 1990. The ERBE radiometric packages were placed into orbit aboard the Earth Radiation Budget Satellite (ERBS) and the NOAA-9 and NOAA-10 spacecraft platforms. In each radiometric package, thermistor bolometers were used as detection elements for the broadband total (0,2 - 50,0 microns), shortwave (0,2 - 5,0 microns), and longwave (5,0 - 50,0 microns) spectral regions. Flight calibration facilities were built into each of the spacecraft radiometric packages. The flight facilities consisted of black bodies, tungsten lamps, and silicon photodiodes. The black bodies and tungsten lamps were found to be reliable at precision levels approaching 0,5 percent over a five-year period. The photodiodes were found to degrade more than 2 percent during the first year in orbit. In this paper, the flight calibration systems for the ERBE scanning radiometers are described along with the resultant measurements.

  15. Preliminary submillimeter spectroscopic measurements using a submillimeter heterodyne radiometer

    NASA Technical Reports Server (NTRS)

    Safren, H. G.; Stabnow, W. R.; Bufton, J. L.; Peruso, C. J.; Rossey, C. E.; Walker, H. E.

    1982-01-01

    A submillimeter heterodyne radiometer uses a submillimeter laser, pumped by a CO2 laser, as a local oscillator and a room temperature Schottky barrier diode as the first IF mixer. The radiometer can resolve spectral lines in the submillimeter region of the spectrum (arising from pure rotational molecular transitions) to within 0.3 MHz, using acousto-optic spectrum analyzer which measures the power spectrum by simultaneously sampling 0.3 MHz wide channels over a 100 MHz bandwidth spanning the line. Preliminary observations of eight spectral lines of H2O2, CO, NH3 and H2O, all lying in the 434-524 micrometer wavelength range are described. All eight lines were observed using two local oscillator frequencies obtained by operating the submillimeter laser with either methyl fluoride (CH3F) or formic acid (HCOOH) as the lasing gas. Sample calculations of line parameters from the observed data show good agreement with established values. One development goal is the size and weight reduction of the package to make it suitable for balloon or shuttle experiments to detect trace gases in the upper atmosphere.

  16. Digital Cavity Resonance Monitor, alternative method of measuring cavity microphonics

    SciTech Connect

    Tomasz Plawski; G. Davis; Hai Dong; J. Hovater; John Musson; Thomas Powers

    2005-09-20

    As is well known, mechanical vibration or microphonics in a cryomodule causes the cavity resonance frequency to change at the vibration frequency. One way to measure the cavity microphonics is to drive the cavity with a Phase Locked Loop. Measurement of the instantaneous frequency or PLL error signal provides information about the cavity microphonic frequencies. Although the PLL error signal is available directly, precision frequency measurements require additional instrumentation, a Cavity Resonance Monitor (CRM). The analog version of such a device has been successfully used for several cavity tests [1]. In this paper we present a prototype of a Digital Cavity Resonance Monitor designed and built in the last year. The hardware of this instrument consists of an RF downconverter, digital quadrature demodulator and digital processor motherboard (Altera FPGA). The motherboard processes received data and computes frequency changes with a resolution of 0.2 Hz, with a 3 kHz output bandwidth.

  17. Universal Cosmic Absolute and Modern Science

    NASA Astrophysics Data System (ADS)

    Kostro, Ludwik

    The official Sciences, especially all natural sciences, respect in their researches the principle of methodic naturalism i.e. they consider all phenomena as entirely natural and therefore in their scientific explanations they do never adduce or cite supernatural entities and forces. The purpose of this paper is to show that Modern Science has its own self-existent, self-acting, and self-sufficient Natural All-in Being or Omni-Being i.e. the entire Nature as a Whole that justifies the scientific methodic naturalism. Since this Natural All-in Being is one and only It should be considered as the own scientifically justified Natural Absolute of Science and should be called, in my opinion, the Universal Cosmic Absolute of Modern Science. It will be also shown that the Universal Cosmic Absolute is ontologically enormously stratified and is in its ultimate i.e. in its most fundamental stratum trans-reistic and trans-personal. It means that in its basic stratum. It is neither a Thing or a Person although It contains in Itself all things and persons with all other sentient and conscious individuals as well, On the turn of the 20th century the Science has begun to look for a theory of everything, for a final theory, for a master theory. In my opinion the natural Universal Cosmic Absolute will constitute in such a theory the radical all penetrating Ultimate Basic Reality and will substitute step by step the traditional supernatural personal Absolute.

  18. Cavity enhanced atomic magnetometry

    PubMed Central

    Crepaz, Herbert; Ley, Li Yuan; Dumke, Rainer

    2015-01-01

    Atom sensing based on Faraday rotation is an indispensable method for precision measurements, universally suitable for both hot and cold atomic systems. Here we demonstrate an all-optical magnetometer where the optical cell for Faraday rotation spectroscopy is augmented with a low finesse cavity. Unlike in previous experiments, where specifically designed multipass cells had been employed, our scheme allows to use conventional, spherical vapour cells. Spherical shaped cells have the advantage that they can be effectively coated inside with a spin relaxation suppressing layer providing long spin coherence times without addition of a buffer gas. Cavity enhancement shows in an increase in optical polarization rotation and sensitivity compared to single-pass configurations. PMID:26481853

  19. Access cavity preparation.

    PubMed

    Adams, N; Tomson, P L

    2014-03-01

    Each stage of root canal treatment should be carried out to the highest possible standard. The access cavity is arguably the most important technical stage, as subsequent preparation of the root canal(s) can be severely comprised if this is not well executed. Inadequate access can lead to canals being left untreated, poorly disinfected, difficult to shape and obturate, and may ultimately lead to the failure of the treatment. This paper highlights common features in root canal anatomy and outlines basic principles for locating root canals and producing a good access cavity. It also explores each phase of the preparation in detail and offers suggestions of instruments that have been specifically designed to overcome potential difficulties in the process. Good access design and preparation will result in an operative environment which will facilitate cleaning, shaping and obturation of the root canal system in order to maximise success.

  20. CAVITY CONTROL ALGORITHM

    SciTech Connect

    Tomasz Plawski, J. Hovater

    2010-09-01

    A digital low level radio frequency (RF) system typically incorporates either a heterodyne or direct sampling technique, followed by fast ADCs, then an FPGA, and finally a transmitting DAC. This universal platform opens up the possibilities for a variety of control algorithm implementations. The foremost concern for an RF control system is cavity field stability, and to meet the required quality of regulation, the chosen control system needs to have sufficient feedback gain. In this paper we will investigate the effectiveness of the regulation for three basic control system algorithms: I&Q (In-phase and Quadrature), Amplitude & Phase and digital SEL (Self Exciting Loop) along with the example of the Jefferson Lab 12 GeV cavity field control system.

  1. Dielectric cavity relativistic magnetron

    NASA Astrophysics Data System (ADS)

    Hashemi, S. M. A.

    2010-02-01

    An alteration in the structure of the A6 relativistic magnetron is proposed, which introduces an extra degree of freedom to its design and enhances many of its quality factors. This modification involves the partial filling of the cavities of the device with a low-loss dielectric material. The operation of a dielectric-filled A6 is simulated; the results indicate single-mode operation at the desired π mode and a substantially cleaner rf spectrum.

  2. What Are Oral Cavity and Oropharyngeal Cancers?

    MedlinePlus

    ... about oral cavity and oropharyngeal cancers? What are oral cavity and oropharyngeal cancers? Cancer starts when cells in ... the parts of the mouth and throat. The oral cavity (mouth) and oropharynx (throat) The oral cavity includes ...

  3. Technique for Radiometer and Antenna Array Calibration with a Radiated Noise Diode

    NASA Technical Reports Server (NTRS)

    Srinivasan, Karthik; Limaye, Ashutosh; Laymon, Charles; Meyer, Paul

    2009-01-01

    This paper presents a new technique to calibrate a microwave radiometer and antenna array system. This calibration technique uses a radiated noise source in addition to two calibration sources internal to the radiometer. The method accurately calibrates antenna arrays with embedded active devices (such as amplifiers) which are used extensively in active phased array antennas.

  4. Quantum theory allows for absolute maximal contextuality

    NASA Astrophysics Data System (ADS)

    Amaral, Barbara; Cunha, Marcelo Terra; Cabello, Adán

    2015-12-01

    Contextuality is a fundamental feature of quantum theory and a necessary resource for quantum computation and communication. It is therefore important to investigate how large contextuality can be in quantum theory. Linear contextuality witnesses can be expressed as a sum S of n probabilities, and the independence number α and the Tsirelson-like number ϑ of the corresponding exclusivity graph are, respectively, the maximum of S for noncontextual theories and for the theory under consideration. A theory allows for absolute maximal contextuality if it has scenarios in which ϑ /α approaches n . Here we show that quantum theory allows for absolute maximal contextuality despite what is suggested by the examination of the quantum violations of Bell and noncontextuality inequalities considered in the past. Our proof is not constructive and does not single out explicit scenarios. Nevertheless, we identify scenarios in which quantum theory allows for almost-absolute-maximal contextuality.

  5. Absolute calibration in vivo measurement systems

    SciTech Connect

    Kruchten, D.A.; Hickman, D.P.

    1991-02-01

    Lawrence Livermore National Laboratory (LLNL) is currently investigating a new method for obtaining absolute calibration factors for radiation measurement systems used to measure internally deposited radionuclides in vivo. Absolute calibration of in vivo measurement systems will eliminate the need to generate a series of human surrogate structures (i.e., phantoms) for calibrating in vivo measurement systems. The absolute calibration of in vivo measurement systems utilizes magnetic resonance imaging (MRI) to define physiological structure, size, and composition. The MRI image provides a digitized representation of the physiological structure, which allows for any mathematical distribution of radionuclides within the body. Using Monte Carlo transport codes, the emission spectrum from the body is predicted. The in vivo measurement equipment is calibrated using the Monte Carlo code and adjusting for the intrinsic properties of the detection system. The calibration factors are verified using measurements of existing phantoms and previously obtained measurements of human volunteers. 8 refs.

  6. Stimulus probability effects in absolute identification.

    PubMed

    Kent, Christopher; Lamberts, Koen

    2016-05-01

    This study investigated the effect of stimulus presentation probability on accuracy and response times in an absolute identification task. Three schedules of presentation were used to investigate the interaction between presentation probability and stimulus position within the set. Data from individual participants indicated strong effects of presentation probability on both proportion correct and response times. The effects were moderated by the ubiquitous stimulus position effect. The accuracy and response time data were predicted by an exemplar-based model of perceptual cognition (Kent & Lamberts, 2005). The bow in discriminability was also attenuated when presentation probability for middle items was relatively high, an effect that will constrain future model development. The study provides evidence for item-specific learning in absolute identification. Implications for other theories of absolute identification are discussed. (PsycINFO Database Record

  7. Quantitative standards for absolute linguistic universals.

    PubMed

    Piantadosi, Steven T; Gibson, Edward

    2014-01-01

    Absolute linguistic universals are often justified by cross-linguistic analysis: If all observed languages exhibit a property, the property is taken to be a likely universal, perhaps specified in the cognitive or linguistic systems of language learners and users. In many cases, these patterns are then taken to motivate linguistic theory. Here, we show that cross-linguistic analysis will very rarely be able to statistically justify absolute, inviolable patterns in language. We formalize two statistical methods--frequentist and Bayesian--and show that in both it is possible to find strict linguistic universals, but that the numbers of independent languages necessary to do so is generally unachievable. This suggests that methods other than typological statistics are necessary to establish absolute properties of human language, and thus that many of the purported universals in linguistics have not received sufficient empirical justification.

  8. Absolute photoacoustic thermometry in deep tissue.

    PubMed

    Yao, Junjie; Ke, Haixin; Tai, Stephen; Zhou, Yong; Wang, Lihong V

    2013-12-15

    Photoacoustic thermography is a promising tool for temperature measurement in deep tissue. Here we propose an absolute temperature measurement method based on the dual temperature dependences of the Grüneisen parameter and the speed of sound in tissue. By taking ratiometric measurements at two adjacent temperatures, we can eliminate the factors that are temperature irrelevant but difficult to correct for in deep tissue. To validate our method, absolute temperatures of blood-filled tubes embedded ~9 mm deep in chicken tissue were measured in a biologically relevant range from 28°C to 46°C. The temperature measurement accuracy was ~0.6°C. The results suggest that our method can be potentially used for absolute temperature monitoring in deep tissue during thermotherapy.

  9. Molecular iodine absolute frequencies. Final report

    SciTech Connect

    Sansonetti, C.J.

    1990-06-25

    Fifty specified lines of {sup 127}I{sub 2} were studied by Doppler-free frequency modulation spectroscopy. For each line the classification of the molecular transition was determined, hyperfine components were identified, and one well-resolved component was selected for precise determination of its absolute frequency. In 3 cases, a nearby alternate line was selected for measurement because no well-resolved component was found for the specified line. Absolute frequency determinations were made with an estimated uncertainty of 1.1 MHz by locking a dye laser to the selected hyperfine component and measuring its wave number with a high-precision Fabry-Perot wavemeter. For each line results of the absolute measurement, the line classification, and a Doppler-free spectrum are given.

  10. Crab Cavities for Linear Colliders

    SciTech Connect

    Burt, G.; Ambattu, P.; Carter, R.; Dexter, A.; Tahir, I.; Beard, C.; Dykes, M.; Goudket, P.; Kalinin, A.; Ma, L.; McIntosh, P.; Shulte, D.; Jones, Roger M.; Bellantoni, L.; Chase, B.; Church, M.; Khabouline, T.; Latina, A.; Adolphsen, C.; Li, Z.; Seryi, Andrei; /SLAC

    2011-11-08

    Crab cavities have been proposed for a wide number of accelerators and interest in crab cavities has recently increased after the successful operation of a pair of crab cavities in KEK-B. In particular crab cavities are required for both the ILC and CLIC linear colliders for bunch alignment. Consideration of bunch structure and size constraints favour a 3.9 GHz superconducting, multi-cell cavity as the solution for ILC, whilst bunch structure and beam-loading considerations suggest an X-band copper travelling wave structure for CLIC. These two cavity solutions are very different in design but share complex design issues. Phase stabilisation, beam loading, wakefields and mode damping are fundamental issues for these crab cavities. Requirements and potential design solutions will be discussed for both colliders.

  11. RF Cavity Characterization with VORPAL

    SciTech Connect

    C. Nieter, C. Roark, P. Stoltz, C.D. Zhou, F. Marhauser

    2011-03-01

    When designing a radio frequency (RF) accelerating cavity structure various figures of merit are considered before coming to a final cavity design. These figures of merit include specific field and geometry based quantities such as the ratio of the shunt impedance to the quality factor (R/Q) or the normalized peak fields in the cavity. Other important measures of cavity performance include the peak surface fields as well as possible multipacting resonances in the cavity. High fidelity simulations of these structures can provide a good estimate of these important quantities before any cavity prototypes are built. We will present VORPAL simulations of a simple pillbox structure where these quantities can be calculated analytically and compare them to the results from the VORPAL simulations. We will then use VORPAL to calculate these figures of merit and potential multipacting resonances for two cavity designs under development at Jefferson National Lab for Project X.

  12. Absolute Stability And Hyperstability In Hilbert Space

    NASA Technical Reports Server (NTRS)

    Wen, John Ting-Yung

    1989-01-01

    Theorems on stabilities of feedback control systems proved. Paper presents recent developments regarding theorems of absolute stability and hyperstability of feedforward-and-feedback control system. Theorems applied in analysis of nonlinear, adaptive, and robust control. Extended to provide sufficient conditions for stability in system including nonlinear feedback subsystem and linear time-invariant (LTI) feedforward subsystem, state space of which is Hilbert space, and input and output spaces having finite numbers of dimensions. (In case of absolute stability, feedback subsystem memoryless and possibly time varying. For hyperstability, feedback system dynamical system.)

  13. Thermal analysis of radiometer containers for the 122m hoop column antenna concept

    NASA Technical Reports Server (NTRS)

    Dillon-Townes, L. A.

    1986-01-01

    A thermal analysis was conducted for the 122 Meter Hoop Column Antenna (HCA) Radiometer electronic package containers. The HCA radiometer containers were modeled using the computer aided graphics program, ANVIL 4000, and thermally simulated using two thermal programs, TRASYS and MITAS. The results of the analysis provided relationships between the absorptance-emittance ratio and the average surface temperature of the orbiting radiometer containers. These relationships can be used to specify the surface properties, absorptance and reflectance, of the radiometer containers. This is an initial effort in determining the passive thermal protection needs for the 122 m HCA radiometer containers. Several recommendations are provided which expand this effort so specific passive and active thermal protection systems can be defined and designed.

  14. Semiconductor millimeter and centimeter wave radiometer for the study of the radiation of an underlying surface

    NASA Technical Reports Server (NTRS)

    Bordonskiy, G. S.; Zazinov, A. N.; Kirsanov, Y. A.; Kravchenko, M. K.; Khapin, Y. B.; Sharapov, A. N.; Etkin, V. S.

    1979-01-01

    A theoretical and experimental investigation of a superheterodyne radiometer system with input frequency converter and intermediate frequency modulation is presented. Conditions are found, at which the temperature sensitivity of the device does not deteriorate. A sensitivity function to external parameters (temperature, heterodyne power) of a radiometer system with intermediate frequency modulation and a Schottky diode frequency converter is presented and calculated. Use of a frequency converter at the second harmonic of the heterodyne permitted simplication of the radiometer design and the use of a semiconductor heterodyne. A 3 cm range intermediate frequency amplifier permitted the use of centimeter wave radiometer signals. Fluctuation sensitivity of radiometers with a 1 sec time constant is 0.3 K at 3.4 mm and 0.06 K at 3 cm.

  15. Dual transmission grating based imaging radiometer for tokamak edge and divertor plasmas

    SciTech Connect

    Kumar, Deepak; Clayton, Daniel J.; Parman, Matthew; Stutman, Dan; Tritz, Kevin; Finkenthal, Michael

    2012-10-15

    The designs of single transmission grating based extreme ultraviolet (XUV) and vacuum ultraviolet (VUV) imaging spectrometers can be adapted to build an imaging radiometer for simultaneous measurement of both spectral ranges. This paper describes the design of such an imaging radiometer with dual transmission gratings. The radiometer will have an XUV coverage of 20-200 A with a {approx}10 A resolution and a VUV coverage of 200-2000 A with a {approx}50 A resolution. The radiometer is designed to have a spatial view of 16 Degree-Sign , with a 0.33 Degree-Sign resolution and a time resolution of {approx}10 ms. The applications for such a radiometer include spatially resolved impurity monitoring and electron temperature measurements in the tokamak edge and the divertor. As a proof of principle, the single grating instruments were used to diagnose a low temperature reflex discharge and the relevant data is also included in this paper.

  16. A 94/183 GHz aircraft radiometer system for Project Storm Fury

    NASA Technical Reports Server (NTRS)

    Gagliano, J. A.; Stratigos, J. A.; Forsythe, R. E.; Schuchardt, J. M.; Welch, J. M.; Gallentine, D. O.

    1980-01-01

    A radiometer design suitable for use in NASA's WB-57F aircraft to collect data from severe storm regions was developed. The design recommended was a 94/183 GHz scanning radiometer with 3 IF channels on either side of the 183.3 GHz water vapor line and a single IF channel for a low loss atmospheric window channel at 94 GHz. The development and construction of the 94/183 GHz scanning radiometer known as the Advanced Microwave Moisture Sounder (AMMS) is presented. The radiometer scans the scene below the aircraft over an angle of + or - 45 degrees with the beamwidth of the scene viewed of approximately 2 degrees at 94 GHz and 1 degree at 183 GHz. The AMMS data collection system consists of a microcomputer used to store the radiometer data on the flight cartridge recorder, operate the stepper motor driven scanner, and collect housekeeping data such as thermistor temperature readings and aircraft time code.

  17. A hot wire radiant energy source for mapping the field of view of a radiometer

    NASA Technical Reports Server (NTRS)

    Edwards, S. F.; Stewart, W. F.; Vann, D. S.

    1977-01-01

    The design and performance of a calibration device that allows the measurement of a radiometer's field of view are described. The heart of the device is a heated 0.0254-mm (0.001-inch) diameter filament that provides a variable, isothermal line source of radiant energy against a cold background. By moving this discrete line source across the field of view of a radiometer, the radiometer's spatial response can be completely mapped. The use of a platinum filament provides a durable radiation source whose temperature is stable and repeatable to 10 K over the range of 600 to 1200 K. By varying the energy emitted by the filament, the field of view of radiometers with different sensitivities (or multiple channel radiometers) can be totally mapped.

  18. Saturns Thermal Emission at 2.2-cm Wavelength as Imaged by the Cassini RADAR Radiometer

    NASA Technical Reports Server (NTRS)

    Janssen, M. A.; Ingersoll, A. P.; Allison, M. D.; Gulkis, S.; Laraia, A. L.; Baines, K. H.; Edgington, S. G.; Anderson, Y. Z.; Kelleher, K.; Oyafuso, F. A.

    2013-01-01

    We present well-calibrated, high-resolution maps of Saturn's thermal emission at 2.2-cm wavelength obtained by the Cassini RADAR radiometer through the Prime and Equinox Cassini missions, a period covering approximately 6 years. The absolute brightness temperature calibration of 2% achieved is more than twice better than for all previous microwave observations reported for Saturn, and the spatial resolution and sensitivity achieved each represent nearly an order of magnitude improvement. The brightness temperature of Saturn in the microwave region depends on the distribution of ammonia, which our radiative transfer modeling shows is the only significant source of absorption in Saturn's atmosphere at 2.2-cm wavelength. At this wavelength the thermal emission comes from just below and within the ammonia cloud-forming region, and yields information about atmospheric circulations and ammonia cloud-forming processes. The maps are presented as residuals compared to a fully saturated model atmosphere in hydrostatic equilibrium. Bright regions in these maps are readily interpreted as due to depletion of ammonia vapor in, and, for very bright regions, below the ammonia saturation region. Features seen include the following: a narrow equatorial band near full saturation surrounded by bands out to about 10deg planetographic latitude that demonstrate highly variable ammonia depletion in longitude; narrow bands of depletion at -35deg latitude; occasional large oval features with depleted ammonia around -45deg latitude; and the 2010-2011 storm, with extensive saturated and depleted areas as it stretched halfway around the planet in the northern hemisphere. Comparison of the maps over time indicates a high degree of stability outside a few latitudes that contain active regions.

  19. A microbolometer-based far infrared radiometer to study thin ice clouds in the Arctic

    NASA Astrophysics Data System (ADS)

    Libois, Quentin; Proulx, Christian; Ivanescu, Liviu; Coursol, Laurence; Pelletier, Ludovick S.; Bouzid, Yacine; Barbero, Francesco; Girard, Éric; Blanchet, Jean-Pierre

    2016-04-01

    A far infrared radiometer (FIRR) dedicated to measuring radiation emitted by clear and cloudy atmospheres was developed in the framework of the Thin Ice Clouds in Far InfraRed Experiment (TICFIRE) technology demonstration satellite project. The FIRR detector is an array of 80 × 60 uncooled microbolometers coated with gold black to enhance the absorptivity and responsivity. A filter wheel is used to select atmospheric radiation in nine spectral bands ranging from 8 to 50 µm. Calibrated radiances are obtained using two well-calibrated blackbodies. Images are acquired at a frame rate of 120 Hz, and temporally averaged to reduce electronic noise. A complete measurement sequence takes about 120 s. With a field of view of 6°, the FIRR is not intended to be an imager. Hence spatial average is computed over 193 illuminated pixels to increase the signal-to-noise ratio and consequently the detector resolution. This results in an improvement by a factor of 5 compared to individual pixel measurements. Another threefold increase in resolution is obtained using 193 non-illuminated pixels to remove correlated electronic noise, leading an overall resolution of approximately 0.015 W m-2 sr-1. Laboratory measurements performed on well-known targets suggest an absolute accuracy close to 0.02 W m-2 sr-1, which ensures atmospheric radiance is retrieved with an accuracy better than 1 %. Preliminary in situ experiments performed from the ground in winter and in summer on clear and cloudy atmospheres are compared to radiative transfer simulations. They point out the FIRR ability to detect clouds and changes in relative humidity of a few percent in various atmospheric conditions, paving the way for the development of new algorithms dedicated to ice cloud characterization and water vapor retrieval.

  20. Characterization of downwelling radiance measured from a ground-based microwave radiometer using numerical weather prediction model data

    NASA Astrophysics Data System (ADS)

    Ahn, M.-H.; Won, H. Y.; Han, D.; Kim, Y.-H.; Ha, J.-C.

    2016-01-01

    The ground-based microwave sounding radiometers installed at nine weather stations of Korea Meteorological Administration alongside with the wind profilers have been operating for more than 4 years. Here we apply a process to assess the characteristics of the observation data by comparing the measured brightness temperature (Tb) with reference data. For the current study, the reference data are prepared by the radiative transfer simulation with the temperature and humidity profiles from the numerical weather prediction model instead of the conventional radiosonde data. Based on the 3 years of data, from 2010 to 2012, we were able to characterize the effects of the absolute calibration on the quality of the measured Tb. We also showed that when clouds are present the comparison with the model has a high variability due to presence of cloud liquid water therefore making cloudy data not suitable for assessment of the radiometer's performance. Finally we showed that differences between modeled and measured brightness temperatures are unlikely due to a shift in the selection of the center frequency but more likely due to spectroscopy issues in the wings of the 60 GHz absorption band. With a proper consideration of data affected by these two effects, it is shown that there is an excellent agreement between the measured and simulated Tb. The regression coefficients are better than 0.97 along with the bias value of better than 1.0 K except for the 52.28 GHz channel which shows a rather large bias and variability of -2.6 and 1.8 K, respectively.

  1. Optical reflectance of pyrheliometer absorption cavities: progress toward SI-traceable measurements of solar irradiance.

    PubMed

    Patrick, Heather J; Germer, Thomas A; Zarobila, Clarence J; Cooksey, Catherine C; Yoon, Howard W

    2016-08-10

    We have accurately determined the absorptance of three pyrheliometer cavities at 532 nm by measuring the residual reflectance using an angle-resolved bidirectional reflectometer. Measurements were performed at a normal incidence as a function of the viewing angle and position on the cavity cone. By numerically integrating the measured angle-resolved scatter over both the direction and position and accounting for an obstructed view of the cavity, we determined that the effective cavity reflectance was between 8×10-4 and 9×10-4. Thus, the absorptance of the three cavities ranged from 0.99909±0.00014 to 0.99922±0.00012 (k=2 combined expanded uncertainties). These measurements, when extended over the spectral range of operation of the pyrheliometer, are required to establish SI traceability for absolute solar irradiance measurements. PMID:27534478

  2. The Odin satellite. II. Radiometer data processing and calibration

    NASA Astrophysics Data System (ADS)

    Olberg, M.; Frisk, U.; Lecacheux, A.; Olofsson, A. O. H.; Baron, P.; Bergman, P.; Florin, G.; Hjalmarson, Å..; Larsson, B.; Murtagh, D.; Olofsson, G.; Pagani, L.; Sandqvist, Aa.; Teyssier, D.; Torchinsky, S. A.; Volk, K.

    2003-05-01

    The radiometer on-board the Odin satellite comprises four different sub-mm receivers covering the 486-581 GHz frequency range and one fixed frequency 119 GHz receiver. Two auto-correlators and one acousto-optical spectrometer serve as backends. This article gives an overview over the processing of the data delivered by these instruments and discusses calibration issues. Odin is a Swedish-led satellite project funded jointly by the Swedish National Space Board (SNSB), the Canadian Space Agency (CSA), the National Technology Agency of Finland (Tekes) and the Centre National d'Études Spatiales (CNES, France). Odin is operated by the Swedish Space Corporation (SSC), the project's prime industrial contractor.

  3. COBE Differential Microwave Radiometers - Instrument design and implementation

    NASA Technical Reports Server (NTRS)

    Smoot, G.; Bennett, Charles; Weber, R.; Maruschak, John; Ratliff, Roger; Janssen, M.

    1990-01-01

    Differential Microwave Radiometers (DMRs) at frequencies of 31.5, 53, and 90 GHz have been designed and built to map the large angular scale variations in the brightness temperature of the cosmic microwave background radiation. The instrument is being flown aboard NASA's Cosmic Background Explorer (COBE) satellite, launched on November 18, 1989. Each receiver input is switched between two antennas pointing 60 deg apart on the sky. The satellite is in near-polar orbit with the orbital plane precessing at 1 deg per day, causing the beams to scan the entire sky in 6 months. In 1 year of observation, the instruments are capable of mapping the sky to an rms sensitivity of 0.1 mK per 7 deg field of view. The mission and the instrument have been carefully designed to minimize the need for systematic corrections to the data.

  4. Atmospheric moisture measurements - A microwave radiometer-radiosonde comparison

    NASA Technical Reports Server (NTRS)

    England, Martin N.; Schmidlin, F. J.; Johansson, Jan M.

    1993-01-01

    Measurements of the thermal emission of the sky at three frequencies (20.7, 22.2, and 31.4 GHz) with the NASA/Goddard Space Flight Center Crustal Dynamics Project MW Water Vapor Radiometer are reported. These measurements are compared with brightness temperatures inferred from measurements from VAISALA radiosonde packages launched every 3 hr during the experiment period. An error analysis for the radiosonde-inferred brightness temperatures is performed under the assumption of reasonable random uncertainties for the pressure, temperature, and humidity measurements and propagation of these uncertainties through the analysis algorithm. For the assumed uncertainties, the dominant contribution to the total uncertainty comes from the temperature measurement (66-88 percent), whereas the relative humidity measurement contributes only 2-8 percent, except in the vicinity of the water vapor line, where the contribution is 10-20 percent.

  5. Preliminary analysis of shuttle multispectral radiometer data for Southern Egypt

    USGS Publications Warehouse

    Rowan, L.C.; Goetz, A.F.H.; Kingston, M.J.

    1983-01-01

    The Shuttle Multispectral Infrared Radiometer (SMIRR) is a spectroradiometer covering the region from 0.5 to 2.5 ??m in 10 channels that acquired data from spots 100 m in diameter along the subspacecraft ground track. It was flown aboard the second flight of the space shuttle Columbia, November 12-14, 1981. Data collected during orbit 16 over southern Egypt show that carbonate rocks, kaolinite, and possibly montmorillonite can be identified by their SMIRR spectral signatures and limited knowledge of the lithologic units present. Detailed analysis of SMIRR data for this area indicates that calcite, kaolinite, and montmorillonite rocks give rise to absorption features that result in characteristic 10 channel spectra. ?? 1983.

  6. Combined Radar and Radiometer Analysis of Precipitation Over Land

    NASA Astrophysics Data System (ADS)

    Hammerschmidt, B.; Kummerow, C.

    2007-12-01

    above correlations) as well as improved understanding of the relationship between ice water aloft and surface rainfall in different meteorological regimes. To further explore the relation between radar derived IWP and radiometer signals, ice water paths were examined with a combination of both radar and radiometer observations. Specifically, different ice density and ice particle number concentrations were examined on the radar inferred ice water path. Stratiform precipitation showed good agreement with both radar and radiometer observations when relatively low density ice (e.g.. snow) particles were assumed. For convective pixels with significant ice scattering, significantly denser ice particles were generally required. Moreover, liquid water above the freezing level had to be added in over 50% of the profiles before a solution that was consistent with both radar and radiometer observations could be constructed. These results appear consistent with current cloud physics understanding.

  7. Mission definition for a large-aperture microwave radiometer spacecraft

    NASA Technical Reports Server (NTRS)

    Keafer, L. S., Jr.

    1981-01-01

    An Earth-observation measurements mission is defined for a large-aperture microwave radiometer spacecraft. This mission is defined without regard to any particular spacecraft design concept. Space data application needs, the measurement selection rationale, and broad spacecraft design requirements and constraints are described. The effects of orbital parameters and image quality requirements on the spacecraft and mission performance are discussed. Over the land the primary measurand is soil moisture; over the coastal zones and the oceans important measurands are salinity, surface temperature, surface winds, oil spill dimensions and ice boundaries; and specific measurement requirements have been selected for each. Near-all-weather operation and good spatial resolution are assured by operating at low microwave frequencies using an extremely large aperture antenna in a low-Earth-orbit contiguous mapping mode.

  8. Sensor Calibration and Ocean Products for TRMM Microwave Radiometer

    NASA Technical Reports Server (NTRS)

    Wentz, Frank J.; Lawrence, Richard J. (Technical Monitor)

    2003-01-01

    During the three years of finding, we have carefully corrected for two sensor/platform problems, developed a physically based retrieval algorithm to calculate SST, wind speed, water vapor, cloud liquid water and rain rates, validated these variables, and demonstrated that satellite microwave radiometers can provide very accurate SST retrievals through clouds. Prior to this, there was doubt by some scientists that the technique of microwave SST retrieval from satellites is a viable option. We think we have put these concerns to rest, and look forward to making microwave SSTs a standard component of the Earth science data sets. Our TMI SSTs were featured on several network news broadcasts and were reported in Science magazine. Additionally, we have developed a SST algorithm for VIRS to facilitate IR/MW inter-comparisons and completed research into diurnal cycles and air-sea interactions.

  9. Sensor Calibration and Ocean Products for TRMM Microwave Radiometer

    NASA Technical Reports Server (NTRS)

    Lawrence, Richard J. (Technical Monitor); Wentz, Frank J.

    2003-01-01

    During the three years of fundin& we have carefully corrected for two sensor/platform problems, developed a physically based retrieval algorithm to calculate SST, wind speed, water vapor, cloud liquid water and rain rates, validated these variables, and demonstrated that satellite microwave radiometers can provide very accurate SST retrievals through clouds. Prior to this, there was doubt by some scientists that the technique of microwave SST retrieval from satellites is a viable option. We think we have put these concerns to rest, and look forward to making microwave SSTs a standard component of the Earth science data sets. Our TMI SSTs were featured on several network news broadcasts and were reported in Science magazine. Additionally, we have developed a SST algorithm for VIRS to facilitate IR/MW inter-comparisons and completed research into diurnal cycles and air-sea interactions.

  10. The application of composite materials to spaceborne radiometer instrument design

    NASA Astrophysics Data System (ADS)

    Hookman, Robert A.; Zurmehly, George E.

    1990-10-01

    The stability and coregistration requirements for future radiometric instrument designs spawn the need for a totally integrated instrument structure and thermal control scheme. To meet the requirements of the future Geostationary meteorological missions an Ultra Stable Instrument Structure (USIS) will be needed. An instrument structure of lightweight construction is described that takes advantage of composite materials that combine high stiffness, low density along with low Coefficient of Thermal Expansion (CTE). In addition, this paper will outline the mission objectives, the operating environment and stability requirements needed for future spaceborne radiometer structures. A conceptual design of a composite instrument structure along with its thermal control system will be outlined, and various design trade-offs will be presented.

  11. Absolute Points for Multiple Assignment Problems

    ERIC Educational Resources Information Center

    Adlakha, V.; Kowalski, K.

    2006-01-01

    An algorithm is presented to solve multiple assignment problems in which a cost is incurred only when an assignment is made at a given cell. The proposed method recursively searches for single/group absolute points to identify cells that must be loaded in any optimal solution. Unlike other methods, the first solution is the optimal solution. The…

  12. Absolute partial photoionization cross sections of ozone.

    SciTech Connect

    Berkowitz, J.; Chemistry

    2008-04-01

    Despite the current concerns about ozone, absolute partial photoionization cross sections for this molecule in the vacuum ultraviolet (valence) region have been unavailable. By eclectic re-evaluation of old/new data and plausible assumptions, such cross sections have been assembled to fill this void.

  13. Stimulus Probability Effects in Absolute Identification

    ERIC Educational Resources Information Center

    Kent, Christopher; Lamberts, Koen

    2016-01-01

    This study investigated the effect of stimulus presentation probability on accuracy and response times in an absolute identification task. Three schedules of presentation were used to investigate the interaction between presentation probability and stimulus position within the set. Data from individual participants indicated strong effects of…

  14. Teaching Absolute Value Inequalities to Mature Students

    ERIC Educational Resources Information Center

    Sierpinska, Anna; Bobos, Georgeana; Pruncut, Andreea

    2011-01-01

    This paper gives an account of a teaching experiment on absolute value inequalities, whose aim was to identify characteristics of an approach that would realize the potential of the topic to develop theoretical thinking in students enrolled in prerequisite mathematics courses at a large, urban North American university. The potential is…

  15. Solving Absolute Value Equations Algebraically and Geometrically

    ERIC Educational Resources Information Center

    Shiyuan, Wei

    2005-01-01

    The way in which students can improve their comprehension by understanding the geometrical meaning of algebraic equations or solving algebraic equation geometrically is described. Students can experiment with the conditions of the absolute value equation presented, for an interesting way to form an overall understanding of the concept.

  16. Increasing Capacity: Practice Effects in Absolute Identification

    ERIC Educational Resources Information Center

    Dodds, Pennie; Donkin, Christopher; Brown, Scott D.; Heathcote, Andrew

    2011-01-01

    In most of the long history of the study of absolute identification--since Miller's (1956) seminal article--a severe limit on performance has been observed, and this limit has resisted improvement even by extensive practice. In a startling result, Rouder, Morey, Cowan, and Pfaltz (2004) found substantially improved performance with practice in the…

  17. Absolute Radiometric Calibration Of The Thematic Mapper

    NASA Astrophysics Data System (ADS)

    Slater, P. N.; Biggar, S. F.; Holm, R. G.; Jackson, R. D.; Mao, Y.; Moran, M. S.; Palmer, J. M.; Yuan, B.

    1986-11-01

    The results are presented of five in-flight absolute radiometric calibrations, made in the period July 1984 to November 1985, at White Sands, New Mexico, of the solar reflective bands of the Landsat-5 Thematic Mapper (TM) . The 23 bandcalibrations made on the five dates show a ± 2.8% RMS variation from the mean as a percentage of the mean.

  18. On Relative and Absolute Conviction in Mathematics

    ERIC Educational Resources Information Center

    Weber, Keith; Mejia-Ramos, Juan Pablo

    2015-01-01

    Conviction is a central construct in mathematics education research on justification and proof. In this paper, we claim that it is important to distinguish between absolute conviction and relative conviction. We argue that researchers in mathematics education frequently have not done so and this has lead to researchers making unwarranted claims…

  19. Sensitivity of Spacebased Microwave Radiometer Observations to Ocean Surface Evaporation

    NASA Technical Reports Server (NTRS)

    Liu, Timothy W.; Li, Li

    2000-01-01

    Ocean surface evaporation and the latent heat it carries are the major components of the hydrologic and thermal forcing on the global oceans. However, there is practically no direct in situ measurements. Evaporation estimated from bulk parameterization methods depends on the quality and distribution of volunteer-ship reports which are far less than satisfactory. The only way to monitor evaporation with sufficient temporal and spatial resolutions to study global environment changes is by spaceborne sensors. The estimation of seasonal-to-interannual variation of ocean evaporation, using spacebased measurements of wind speed, sea surface temperature (SST), and integrated water vapor, through bulk parameterization method,s was achieved with reasonable success over most of the global ocean, in the past decade. Because all the three geophysical parameters can be retrieved from the radiance at the frequencies measured by the Scanning Multichannel Microwave Radiometer (SMMR) on Nimbus-7, the feasibility of retrieving evaporation directly from the measured radiance was suggested and demonstrated using coincident brightness temperatures observed by SMMR and latent heat flux computed from ship data, in the monthly time scale. However, the operational microwave radiometers that followed SMMR, the Special Sensor Microwave/Imager (SSM/I), lack the low frequency channels which are sensitive to SST. This low frequency channels are again included in the microwave imager (TMI) of the recently launched Tropical Rain Measuring Mission (TRMM). The radiance at the frequencies observed by both TMI and SSM/I were simulated through an atmospheric radiative transfer model using ocean surface parameters and atmospheric temperature and humidity profiles produced by the reanalysis of the European Center for Medium Range Weather Forecast (ECMWF). From the same ECMWF data set, coincident evaporation is computed using a surface layer turbulent transfer model. The sensitivity of the radiance to

  20. Superconducting cavities and modulated RF

    SciTech Connect

    Farkas, Z.D.

    1981-02-01

    If a cavity has an infinite Q/sub o/, 81.5% of the energy contained in a pulse incident upon the cavity is transferred into the cavity by the end of the pulse if the cavity Q/sub e/ is chosen so that the cavity time constant is 0.796 pulse width (T/sub a/). As Q/sug o/ decreases, the energy in the cavity at the end of the pulse decreases very slowly as long as T/sub a/ is much less than the unloaded cavity time constant, T/sub co/. SC cavities with very high Q/sub o/ enable one to obtain very high gradients with a low power cw source. At high gradients, however, one often does not attain the high Q/sub o/ predicted by theory. Therefore, if one is inteerested in attaining maximum energy in the cavity, as is the case for RF processing and diagnostics, for a given available source energy there is no point in keeping the power on for longer than 0.1 T/sub co/ because the energy expended after 0.1 T/sub co/ is wasted. Therefore, to attain high fields at moderate Q/sub o/, pulsed operation is indicated. This note derives the fields and energy stored and dissipated in the cavity when Q/sub e/ is optimized for a given T/sub a/. It shows how to use this data to measure Q/sub o/ of an SC cavity as a function of field level, how to process the cavity with high RF fields, how to operate SC cavities in the pulsed mode to obtain higher efficiencies and gradients. Experimental results are also reported.

  1. Cavity optomechanical magnetometer.

    PubMed

    Forstner, S; Prams, S; Knittel, J; van Ooijen, E D; Swaim, J D; Harris, G I; Szorkovszky, A; Bowen, W P; Rubinsztein-Dunlop, H

    2012-03-23

    A cavity optomechanical magnetometer is demonstrated. The magnetic-field-induced expansion of a magnetostrictive material is resonantly transduced onto the physical structure of a highly compliant optical microresonator and read out optically with ultrahigh sensitivity. A peak magnetic field sensitivity of 400  nT  Hz(-1/2) is achieved, with theoretical modeling predicting the possibility of sensitivities below 1  pT  Hz(-1/2). This chip-based magnetometer combines high sensitivity and large dynamic range with small size and room temperature operation.

  2. Scanning micro-resonator direct-comb absolute spectroscopy

    PubMed Central

    Gambetta, Alessio; Cassinerio, Marco; Gatti, Davide; Laporta, Paolo; Galzerano, Gianluca

    2016-01-01

    Direct optical Frequency Comb Spectroscopy (DFCS) is proving to be a fundamental tool in many areas of science and technology thanks to its unique performance in terms of ultra-broadband, high-speed detection and frequency accuracy, allowing for high-fidelity mapping of atomic and molecular energy structure. Here we present a novel DFCS approach based on a scanning Fabry-Pérot micro-cavity resonator (SMART) providing a simple, compact and accurate method to resolve the mode structure of an optical frequency comb. The SMART approach, while drastically reducing system complexity, allows for a straightforward absolute calibration of the optical-frequency axis with an ultimate resolution limited by the micro-resonator resonance linewidth and can be used in any spectral region from UV to THz. We present an application to high-precision spectroscopy of acetylene at 1.54 μm, demonstrating performances comparable or even better than current state-of-the-art DFCS systems in terms of sensitivity, optical bandwidth and frequency-resolution. PMID:27752132

  3. Combined Use of Absolute and Differential Seismic Arrival Time Data to Improve Absolute Event Location

    NASA Astrophysics Data System (ADS)

    Myers, S.; Johannesson, G.

    2012-12-01

    Arrival time measurements based on waveform cross correlation are becoming more common as advanced signal processing methods are applied to seismic data archives and real-time data streams. Waveform correlation can precisely measure the time difference between the arrival of two phases, and differential time data can be used to constrain relative location of events. Absolute locations are needed for many applications, which generally requires the use of absolute time data. Current methods for measuring absolute time data are approximately two orders of magnitude less precise than differential time measurements. To exploit the strengths of both absolute and differential time data, we extend our multiple-event location method Bayesloc, which previously used absolute time data only, to include the use of differential time measurements that are based on waveform cross correlation. Fundamentally, Bayesloc is a formulation of the joint probability over all parameters comprising the multiple event location system. The Markov-Chain Monte Carlo method is used to sample from the joint probability distribution given arrival data sets. The differential time component of Bayesloc includes scaling a stochastic estimate of differential time measurement precision based the waveform correlation coefficient for each datum. For a regional-distance synthetic data set with absolute and differential time measurement error of 0.25 seconds and 0.01 second, respectively, epicenter location accuracy is improved from and average of 1.05 km when solely absolute time data are used to 0.28 km when absolute and differential time data are used jointly (73% improvement). The improvement in absolute location accuracy is the result of conditionally limiting absolute location probability regions based on the precise relative position with respect to neighboring events. Bayesloc estimates of data precision are found to be accurate for the synthetic test, with absolute and differential time measurement

  4. Applications of cavity optomechanics

    SciTech Connect

    Metcalfe, Michael

    2014-09-15

    Cavity-optomechanics” aims to study the quantum properties of mechanical systems. A common strategy implemented in order to achieve this goal couples a high finesse photonic cavity to a high quality factor mechanical resonator. Then, using feedback forces such as radiation pressure, one can cool the mechanical mode of interest into the quantum ground state and create non-classical states of mechanical motion. On the path towards achieving these goals, many near-term applications of this field have emerged. After briefly introducing optomechanical systems and describing the current state-of-the-art experimental results, this article summarizes some of the more exciting practical applications such as ultra-sensitive, high bandwidth accelerometers and force sensors, low phase noise x-band integrated microwave oscillators and optical signal processing such as optical delay-lines, wavelength converters, and tunable optical filters. In this rapidly evolving field, new applications are emerging at a fast pace, but this article concentrates on the aforementioned lab-based applications as these are the most promising avenues for near-term real-world applications. New basic science applications are also becoming apparent such as the generation of squeezed light, testing gravitational theories and for providing a link between disparate quantum systems.

  5. Multicolor cavity metrology.

    PubMed

    Izumi, Kiwamu; Arai, Koji; Barr, Bryan; Betzwieser, Joseph; Brooks, Aidan; Dahl, Katrin; Doravari, Suresh; Driggers, Jennifer C; Korth, W Zach; Miao, Haixing; Rollins, Jameson; Vass, Stephen; Yeaton-Massey, David; Adhikari, Rana X

    2012-10-01

    Long-baseline laser interferometers used for gravitational-wave detection have proven to be very complicated to control. In order to have sufficient sensitivity to astrophysical gravitational waves, a set of multiple coupled optical cavities comprising the interferometer must be brought into resonance with the laser field. A set of multi-input, multi-output servos then lock these cavities into place via feedback control. This procedure, known as lock acquisition, has proven to be a vexing problem and has reduced greatly the reliability and duty factor of the past generation of laser interferometers. In this article, we describe a technique for bringing the interferometer from an uncontrolled state into resonance by using harmonically related external fields to provide a deterministic hierarchical control. This technique reduces the effect of the external seismic disturbances by 4 orders of magnitude and promises to greatly enhance the stability and reliability of the current generation of gravitational-wave detectors. The possibility for using multicolor techniques to overcome current quantum and thermal noise limits is also discussed. PMID:23201656

  6. Application of Monte Carlo techniques to transient thermal modeling of cavity radiometers having diffuse-specular surfaces

    NASA Technical Reports Server (NTRS)

    Mahan, J. R.; Eskin, L. D.

    1981-01-01

    A viable alternative to the net exchange method of radiative analysis which is equally applicable to diffuse and diffuse-specular enclosures is presented. It is particularly more advantageous to use than the net exchange method in the case of a transient thermal analysis involving conduction and storage of energy as well as radiative exchange. A new quantity, called the distribution factor is defined which replaces the angle factor and the configuration factor. Once obtained, the array of distribution factors for an ensemble of surface elements which define an enclosure permits the instantaneous net radiative heat fluxes to all of the surfaces to be computed directly in terms of the known surface temperatures at that instant. The formulation of the thermal model is described, as is the determination of distribution factors by application of a Monte Carlo analysis. The results show that when fewer than 10,000 packets are emitted, an unsatisfactory approximation for the distribution factors is obtained, but that 10,000 packets is sufficient.

  7. Extremely Large Cusp Diamagnetic Cavities

    NASA Astrophysics Data System (ADS)

    Chen, J.; Fritz, T. A.

    2002-05-01

    Extremely large diamagnetic cavities with a size of as large as 6 Re have been observed in the dayside high-altitude cusp regions. Some of the diamagnetic cavities were independent of the IMF directions, which is unexpected by the current MHD (or ISM) models, suggesting that the cusp diamagnetic cavities are different from the magnetospheric sash, which provides a challenge to the existing MHD (or ISM) models. Associated with these cavities are ions with energies from 40 keV up to 8 MeV. The charge state distribution of these cusp cavity ions was indicative of their seed populations being a mixture of the ionospheric and the solar wind particles. The intensities of the cusp cavity energetic ions were observed to increase by as large as four orders of the magnitudes. During high solar wind pressure period on April 21, 1999, the POLAR spacecraft observed lower ion flux in the dayside high-latitude magnetosheath than that in the neighbouring cusp cavities. These observations indicate that the dayside high-altitude cusp diamagnetic cavity is a key region for transferring the solar wind energy, mass, and momentum into the Earth's magnetosphere. These energetic particles in the cusp diamagnetic cavity together with the cusp's connectivity have significant global impacts on the geospace environment research and will be shedding light on the long-standing unsolved fundamental issue about the origins of the energetic particles in the ring current and in upstream ion events.

  8. Extremely large cusp diamagnetic cavities

    NASA Astrophysics Data System (ADS)

    Chen, J.; Fritz, T.; Siscoe, G.

    Extremely large diamagnetic cavities with a size of as large as 6 Re have been observed in the dayside high-altitude cusp regions. These diamagnetic cavities are always there day by day. Some of the diamagnetic cavities have been observed in the morningside during intervals when the IMF By component was positive (duskward), suggesting that the cusp diamagnetic cavities are different from the magnetospheric sash predicted by MHD simulations. Associated with these cavities are ions with energies from 40 keV up to 8 MeV. The charge state distribution of these cusp cavity ions was indicative of their seed populations being a mixture of the ionospheric and the solar wind particles. The intensities of the cusp cavity energetic ions were observed to increase by as large as four orders of the magnitudes. These observations indicate that the dayside high-altitude cusp diamagnetic cavity is a key region for transferring the solar wind energy, mass, and momentum into the Earth's magnetosphere. These energetic particles in the cusp diamagnetic cavity together with the cusp's connectivity to the entire magnetopause may have significant global impacts on the geospace environment. They will possibly be shedding light on the long-standing unsolved fundamental issue about the origins of the energetic particles in the ring current and in the regions upstream of the subsolar magnetopause where energetic ion events frequently are observed.

  9. Nanofriction in Cavity Quantum Electrodynamics.

    PubMed

    Fogarty, T; Cormick, C; Landa, H; Stojanović, Vladimir M; Demler, E; Morigi, Giovanna

    2015-12-01

    The dynamics of cold trapped ions in a high-finesse resonator results from the interplay between the long-range Coulomb repulsion and the cavity-induced interactions. The latter are due to multiple scatterings of laser photons inside the cavity and become relevant when the laser pump is sufficiently strong to overcome photon decay. We study the stationary states of ions coupled with a mode of a standing-wave cavity as a function of the cavity and laser parameters, when the typical length scales of the two self-organizing processes, Coulomb crystallization and photon-mediated interactions, are incommensurate. The dynamics are frustrated and in specific limiting cases can be cast in terms of the Frenkel-Kontorova model, which reproduces features of friction in one dimension. We numerically recover the sliding and pinned phases. For strong cavity nonlinearities, they are in general separated by bistable regions where superlubric and stick-slip dynamics coexist. The cavity, moreover, acts as a thermal reservoir and can cool the chain vibrations to temperatures controlled by the cavity parameters and by the ions' phase. These features are imprinted in the radiation emitted by the cavity, which is readily measurable in state-of-the-art setups of cavity quantum electrodynamics. PMID:26684118

  10. Cavity coalescence in superplastic deformation

    SciTech Connect

    Stowell, M.J.; Livesey, D.W.; Ridley, N.

    1984-01-01

    An analysis of the probability distribution function of particles randomly dispersed in a solid has been applied to cavitation during superplastic deformation and a method of predicting cavity coalescence developed. Cavity size distribution data were obtained from two microduplex nickel-silver alloys deformed superplastically to various extents at elevated temperature, and compared to theoretical predictions. Excellent agreement occurred for small void sizes but the model underestimated the number of voids in the largest size groups. It is argued that the discrepancy results from a combination of effects due to non-random cavity distributions and to enhanced growth rates and incomplete spheroidization of the largest cavities.

  11. Nanofriction in Cavity Quantum Electrodynamics.

    PubMed

    Fogarty, T; Cormick, C; Landa, H; Stojanović, Vladimir M; Demler, E; Morigi, Giovanna

    2015-12-01

    The dynamics of cold trapped ions in a high-finesse resonator results from the interplay between the long-range Coulomb repulsion and the cavity-induced interactions. The latter are due to multiple scatterings of laser photons inside the cavity and become relevant when the laser pump is sufficiently strong to overcome photon decay. We study the stationary states of ions coupled with a mode of a standing-wave cavity as a function of the cavity and laser parameters, when the typical length scales of the two self-organizing processes, Coulomb crystallization and photon-mediated interactions, are incommensurate. The dynamics are frustrated and in specific limiting cases can be cast in terms of the Frenkel-Kontorova model, which reproduces features of friction in one dimension. We numerically recover the sliding and pinned phases. For strong cavity nonlinearities, they are in general separated by bistable regions where superlubric and stick-slip dynamics coexist. The cavity, moreover, acts as a thermal reservoir and can cool the chain vibrations to temperatures controlled by the cavity parameters and by the ions' phase. These features are imprinted in the radiation emitted by the cavity, which is readily measurable in state-of-the-art setups of cavity quantum electrodynamics.

  12. Nanofriction in Cavity Quantum Electrodynamics

    NASA Astrophysics Data System (ADS)

    Fogarty, T.; Cormick, C.; Landa, H.; Stojanović, Vladimir M.; Demler, E.; Morigi, Giovanna

    2015-12-01

    The dynamics of cold trapped ions in a high-finesse resonator results from the interplay between the long-range Coulomb repulsion and the cavity-induced interactions. The latter are due to multiple scatterings of laser photons inside the cavity and become relevant when the laser pump is sufficiently strong to overcome photon decay. We study the stationary states of ions coupled with a mode of a standing-wave cavity as a function of the cavity and laser parameters, when the typical length scales of the two self-organizing processes, Coulomb crystallization and photon-mediated interactions, are incommensurate. The dynamics are frustrated and in specific limiting cases can be cast in terms of the Frenkel-Kontorova model, which reproduces features of friction in one dimension. We numerically recover the sliding and pinned phases. For strong cavity nonlinearities, they are in general separated by bistable regions where superlubric and stick-slip dynamics coexist. The cavity, moreover, acts as a thermal reservoir and can cool the chain vibrations to temperatures controlled by the cavity parameters and by the ions' phase. These features are imprinted in the radiation emitted by the cavity, which is readily measurable in state-of-the-art setups of cavity quantum electrodynamics.

  13. Ultrahigh enhancement in absolute and relative rotation sensing using fast and slow light

    SciTech Connect

    Shahriar, M. S.; Pati, G. S.; Tripathi, R.; Gopal, V.; Messall, M.; Salit, K.

    2007-05-15

    We describe a resonator-based optical gyroscope whose sensitivity for measuring absolute rotation is enhanced via use of the anomalous dispersion characteristic of superluminal light propagation. The enhancement is given by the inverse of the group index, saturating to a bound determined by the group velocity dispersion. We also show how the offsetting effect of the concomitant broadening of the resonator linewidth may be circumvented by using an active cavity. For realistic conditions, the enhancement factor is as high as 10{sup 6}. We also show how normal dispersion used for slow light can enhance relative rotation sensing in a specially designed Sagnac interferometer, with the enhancement given by the slowing factor.

  14. An SSM/I radiometer simulator for studies of microwave emission from soil. [Special Sensor Microwave/Imager

    NASA Technical Reports Server (NTRS)

    Galantowicz, J. F.; England, A. W.

    1992-01-01

    A ground-based simulator of the defense meterological satellite program special sensor microwave/imager (DMSP SSM/I) is described, and its integration with micrometeorological instrumentation for an investigation of microwave emission from moist and frozen soils is discussed. The simulator consists of three single polarization radiometers which are capable of both Dicke radiometer and total power radiometer modes of operation. The radiometers are designed for untended operation through a local computer and a daily telephone link to a laboratory. The functional characteristics of the radiometers are described, together with their field deployment configuration and an example of performance parameters.

  15. Absolute Calibration of Optical Satellite Sensors Using Libya 4 Pseudo Invariant Calibration Site

    NASA Technical Reports Server (NTRS)

    Mishra, Nischal; Helder, Dennis; Angal, Amit; Choi, Jason; Xiong, Xiaoxiong

    2014-01-01

    The objective of this paper is to report the improvements in an empirical absolute calibration model developed at South Dakota State University using Libya 4 (+28.55 deg, +23.39 deg) pseudo invariant calibration site (PICS). The approach was based on use of the Terra MODIS as the radiometer to develop an absolute calibration model for the spectral channels covered by this instrument from visible to shortwave infrared. Earth Observing One (EO-1) Hyperion, with a spectral resolution of 10 nm, was used to extend the model to cover visible and near-infrared regions. A simple Bidirectional Reflectance Distribution function (BRDF) model was generated using Terra Moderate Resolution Imaging Spectroradiometer (MODIS) observations over Libya 4 and the resulting model was validated with nadir data acquired from satellite sensors such as Aqua MODIS and Landsat 7 (L7) Enhanced Thematic Mapper (ETM+). The improvements in the absolute calibration model to account for the BRDF due to off-nadir measurements and annual variations in the atmosphere are summarized. BRDF models due to off-nadir viewing angles have been derived using the measurements from EO-1 Hyperion. In addition to L7 ETM+, measurements from other sensors such as Aqua MODIS, UK-2 Disaster Monitoring Constellation (DMC), ENVISAT Medium Resolution Imaging Spectrometer (MERIS) and Operational Land Imager (OLI) onboard Landsat 8 (L8), which was launched in February 2013, were employed to validate the model. These satellite sensors differ in terms of the width of their spectral bandpasses, overpass time, off-nadir-viewing capabilities, spatial resolution and temporal revisit time, etc. The results demonstrate that the proposed empirical calibration model has accuracy of the order of 3% with an uncertainty of about 2% for the sensors used in the study.

  16. The Impact of Different Absolute Solar Irradiance Values on Current Climate Model Simulations

    NASA Technical Reports Server (NTRS)

    Rind, David H.; Lean, Judith L.; Jonas, Jeffrey

    2014-01-01

    Simulations of the preindustrial and doubled CO2 climates are made with the GISS Global Climate Middle Atmosphere Model 3 using two different estimates of the absolute solar irradiance value: a higher value measured by solar radiometers in the 1990s and a lower value measured recently by the Solar Radiation and Climate Experiment. Each of the model simulations is adjusted to achieve global energy balance; without this adjustment the difference in irradiance produces a global temperature change of 0.48C, comparable to the cooling estimated for the Maunder Minimum. The results indicate that by altering cloud cover the model properly compensates for the different absolute solar irradiance values on a global level when simulating both preindustrial and doubled CO2 climates. On a regional level, the preindustrial climate simulations and the patterns of change with doubled CO2 concentrations are again remarkably similar, but there are some differences. Using a higher absolute solar irradiance value and the requisite cloud cover affects the model's depictions of high-latitude surface air temperature, sea level pressure, and stratospheric ozone, as well as tropical precipitation. In the climate change experiments it leads to an underestimation of North Atlantic warming, reduced precipitation in the tropical western Pacific, and smaller total ozone growth at high northern latitudes. Although significant, these differences are typically modest compared with the magnitude of the regional changes expected for doubled greenhouse gas concentrations. Nevertheless, the model simulations demonstrate that achieving the highest possible fidelity when simulating regional climate change requires that climate models use as input the most accurate (lower) solar irradiance value.

  17. Continuous Time Series of Water Vapor Profiles from a Combination of Raman Lidar and Microwave Radiometer

    NASA Astrophysics Data System (ADS)

    Foth, Andreas; Baars, Holger; Di Girolamo, Paolo; Pospichal, Bernhard

    2016-06-01

    In this paper, we present a method to retrieve continuous water vapor profiles from a combination of a Raman lidar and a microwave radiometer. The integrated water vapor from the microwave radiometer is used to calibrate the Raman lidar operationally resulting in small biases compared to radiosondes. The height limitations for Raman lidars (cloud base and daylight contamination) can be well compensated by the application of a two-step algorithm combining the Raman lidars mass mixing ratio and the microwave radiometers brightness temperatures.

  18. An absolute measure for a key currency

    NASA Astrophysics Data System (ADS)

    Oya, Shunsuke; Aihara, Kazuyuki; Hirata, Yoshito

    It is generally considered that the US dollar and the euro are the key currencies in the world and in Europe, respectively. However, there is no absolute general measure for a key currency. Here, we investigate the 24-hour periodicity of foreign exchange markets using a recurrence plot, and define an absolute measure for a key currency based on the strength of the periodicity. Moreover, we analyze the time evolution of this measure. The results show that the credibility of the US dollar has not decreased significantly since the Lehman shock, when the Lehman Brothers bankrupted and influenced the economic markets, and has increased even relatively better than that of the euro and that of the Japanese yen.

  19. Probing absolute spin polarization at the nanoscale.

    PubMed

    Eltschka, Matthias; Jäck, Berthold; Assig, Maximilian; Kondrashov, Oleg V; Skvortsov, Mikhail A; Etzkorn, Markus; Ast, Christian R; Kern, Klaus

    2014-12-10

    Probing absolute values of spin polarization at the nanoscale offers insight into the fundamental mechanisms of spin-dependent transport. Employing the Zeeman splitting in superconducting tips (Meservey-Tedrow-Fulde effect), we introduce a novel spin-polarized scanning tunneling microscopy that combines the probing capability of the absolute values of spin polarization with precise control at the atomic scale. We utilize our novel approach to measure the locally resolved spin polarization of magnetic Co nanoislands on Cu(111). We find that the spin polarization is enhanced by 65% when increasing the width of the tunnel barrier by only 2.3 Å due to the different decay of the electron orbitals into vacuum. PMID:25423049

  20. From Hubble's NGSL to Absolute Fluxes

    NASA Technical Reports Server (NTRS)

    Heap, Sara R.; Lindler, Don

    2012-01-01

    Hubble's Next Generation Spectral Library (NGSL) consists of R-l000 spectra of 374 stars of assorted temperature, gravity, and metallicity. Each spectrum covers the wavelength range, 0.18-1.00 microns. The library can be viewed and/or downloaded from the website, http://archive.stsci.edu/prepds/stisngsll. Stars in the NGSL are now being used as absolute flux standards at ground-based observatories. However, the uncertainty in the absolute flux is about 2%, which does not meet the requirements of dark-energy surveys. We are therefore developing an observing procedure that should yield fluxes with uncertainties less than 1 % and will take part in an HST proposal to observe up to 15 stars using this new procedure.

  1. Impact of Winko on absolute discharges.

    PubMed

    Balachandra, Krishna; Swaminath, Sam; Litman, Larry C

    2004-01-01

    In Canada, case laws have had a significant impact on the way mentally ill offenders are managed, both in the criminal justice system and in the forensic mental health system. The Supreme Court of Canada's decision with respect to Winko has set a major precedent in the application of the test of significant risk to the safety of the public in making dispositions by the Ontario Review Board and granting absolute discharges to the mentally ill offenders in the forensic health system. Our study examines the impact of the Supreme Court of Canada's decision before and after Winko. The results show that the numbers of absolute discharges have increased post-Winko, which was statistically significant, but there could be other factors influencing this increase.

  2. Asteroid absolute magnitudes and slope parameters

    NASA Technical Reports Server (NTRS)

    Tedesco, Edward F.

    1991-01-01

    A new listing of absolute magnitudes (H) and slope parameters (G) has been created and published in the Minor Planet Circulars; this same listing will appear in the 1992 Ephemerides of Minor Planets. Unlike previous listings, the values of the current list were derived from fits of data at the V band. All observations were reduced in the same fashion using, where appropriate, a single basis default value of 0.15 for the slope parameter. Distances and phase angles were computed for each observation. The data for 113 asteroids was of sufficiently high quality to permit derivation of their H and G. These improved absolute magnitudes and slope parameters will be used to deduce the most reliable bias-corrected asteroid size-frequency distribution yet made.

  3. Absolute-magnitude distributions of supernovae

    SciTech Connect

    Richardson, Dean; Wright, John; Jenkins III, Robert L.; Maddox, Larry

    2014-05-01

    The absolute-magnitude distributions of seven supernova (SN) types are presented. The data used here were primarily taken from the Asiago Supernova Catalogue, but were supplemented with additional data. We accounted for both foreground and host-galaxy extinction. A bootstrap method is used to correct the samples for Malmquist bias. Separately, we generate volume-limited samples, restricted to events within 100 Mpc. We find that the superluminous events (M{sub B} < –21) make up only about 0.1% of all SNe in the bias-corrected sample. The subluminous events (M{sub B} > –15) make up about 3%. The normal Ia distribution was the brightest with a mean absolute blue magnitude of –19.25. The IIP distribution was the dimmest at –16.75.

  4. Absolute and relative dosimetry for ELIMED

    SciTech Connect

    Cirrone, G. A. P.; Schillaci, F.; Scuderi, V.; Cuttone, G.; Candiano, G.; Musumarra, A.; Pisciotta, P.; Romano, F.; Carpinelli, M.; Presti, D. Lo; Raffaele, L.; Tramontana, A.; Cirio, R.; Sacchi, R.; Monaco, V.; Marchetto, F.; Giordanengo, S.

    2013-07-26

    The definition of detectors, methods and procedures for the absolute and relative dosimetry of laser-driven proton beams is a crucial step toward the clinical use of this new kind of beams. Hence, one of the ELIMED task, will be the definition of procedures aiming to obtain an absolute dose measure at the end of the transport beamline with an accuracy as close as possible to the one required for clinical applications (i.e. of the order of 5% or less). Relative dosimetry procedures must be established, as well: they are necessary in order to determine and verify the beam dose distributions and to monitor the beam fluence and the energetic spectra during irradiations. Radiochromic films, CR39, Faraday Cup, Secondary Emission Monitor (SEM) and transmission ionization chamber will be considered, designed and studied in order to perform a fully dosimetric characterization of the ELIMED proton beam.

  5. Absolute photoionization cross sections of atomic oxygen

    NASA Technical Reports Server (NTRS)

    Samson, J. A. R.; Pareek, P. N.

    1985-01-01

    The absolute values of photoionization cross sections of atomic oxygen were measured from the ionization threshold to 120 A. An auto-ionizing resonance belonging to the 2S2P4(4P)3P(3Do, 3So) transition was observed at 479.43 A and another line at 389.97 A. The experimental data is in excellent agreement with rigorous close-coupling calculations that include electron correlations in both the initial and final states.

  6. Absolute photoionization cross sections of atomic oxygen

    NASA Technical Reports Server (NTRS)

    Samson, J. A. R.; Pareek, P. N.

    1982-01-01

    The absolute values of photoionization cross sections of atomic oxygen were measured from the ionization threshold to 120 A. An auto-ionizing resonance belonging to the 2S2P4(4P)3P(3Do, 3So) transition was observed at 479.43 A and another line at 389.97 A. The experimental data is in excellent agreement with rigorous close-coupling calculations that include electron correlations in both the initial and final states.

  7. Relative errors can cue absolute visuomotor mappings.

    PubMed

    van Dam, Loes C J; Ernst, Marc O

    2015-12-01

    When repeatedly switching between two visuomotor mappings, e.g. in a reaching or pointing task, adaptation tends to speed up over time. That is, when the error in the feedback corresponds to a mapping switch, fast adaptation occurs. Yet, what is learned, the relative error or the absolute mappings? When switching between mappings, errors with a size corresponding to the relative difference between the mappings will occur more often than other large errors. Thus, we could learn to correct more for errors with this familiar size (Error Learning). On the other hand, it has been shown that the human visuomotor system can store several absolute visuomotor mappings (Mapping Learning) and can use associated contextual cues to retrieve them. Thus, when contextual information is present, no error feedback is needed to switch between mappings. Using a rapid pointing task, we investigated how these two types of learning may each contribute when repeatedly switching between mappings in the absence of task-irrelevant contextual cues. After training, we examined how participants changed their behaviour when a single error probe indicated either the often-experienced error (Error Learning) or one of the previously experienced absolute mappings (Mapping Learning). Results were consistent with Mapping Learning despite the relative nature of the error information in the feedback. This shows that errors in the feedback can have a double role in visuomotor behaviour: they drive the general adaptation process by making corrections possible on subsequent movements, as well as serve as contextual cues that can signal a learned absolute mapping. PMID:26280315

  8. The absolute spectrophotometric catalog by Anita Cochran

    NASA Astrophysics Data System (ADS)

    Burnashev, V. I.; Burnasheva, B. A.; Ruban, E. V.; Hagen-Torn, E. I.

    2014-06-01

    The absolute spectrophotometric catalog by Anita Cochran is presented in a machine-readable form. The catalog systematizes observations acquired at the McDonald Observatory in 1977-1978. The data are compared with other sources, in particular, the calculated broadband stellar magnitudes are compared with photometric observations by other authors, to show that the observational data given in the catalog are reliable and suitable for a variety of applications. Observations of variable stars of different types make Cochran's catalog especially valuable.

  9. Absolute magnitudes and kinematics of barium stars.

    NASA Astrophysics Data System (ADS)

    Gomez, A. E.; Luri, X.; Grenier, S.; Prevot, L.; Mennessier, M. O.; Figueras, F.; Torra, J.

    1997-03-01

    The absolute magnitude of barium stars has been obtained from kinematical data using a new algorithm based on the maximum-likelihood principle. The method allows to separate a sample into groups characterized by different mean absolute magnitudes, kinematics and z-scale heights. It also takes into account, simultaneously, the censorship in the sample and the errors on the observables. The method has been applied to a sample of 318 barium stars. Four groups have been detected. Three of them show a kinematical behaviour corresponding to disk population stars. The fourth group contains stars with halo kinematics. The luminosities of the disk population groups spread a large range. The intrinsically brightest one (M_v_=-1.5mag, σ_M_=0.5mag) seems to be an inhomogeneous group containing barium binaries as well as AGB single stars. The most numerous group (about 150 stars) has a mean absolute magnitude corresponding to stars in the red giant branch (M_v_=0.9mag, σ_M_=0.8mag). The third group contains barium dwarfs, the obtained mean absolute magnitude is characteristic of stars on the main sequence or on the subgiant branch (M_v_=3.3mag, σ_M_=0.5mag). The obtained mean luminosities as well as the kinematical results are compatible with an evolutionary link between barium dwarfs and classical barium giants. The highly luminous group is not linked with these last two groups. More high-resolution spectroscopic data will be necessary in order to better discriminate between barium and non-barium stars.

  10. Chemical composition of French mimosa absolute oil.

    PubMed

    Perriot, Rodolphe; Breme, Katharina; Meierhenrich, Uwe J; Carenini, Elise; Ferrando, Georges; Baldovini, Nicolas

    2010-02-10

    Since decades mimosa (Acacia dealbata) absolute oil has been used in the flavor and perfume industry. Today, it finds an application in over 80 perfumes, and its worldwide industrial production is estimated five tons per year. Here we report on the chemical composition of French mimosa absolute oil. Straight-chain analogues from C6 to C26 with different functional groups (hydrocarbons, esters, aldehydes, diethyl acetals, alcohols, and ketones) were identified in the volatile fraction. Most of them are long-chain molecules: (Z)-heptadec-8-ene, heptadecane, nonadecane, and palmitic acid are the most abundant, and constituents such as 2-phenethyl alcohol, methyl anisate, and ethyl palmitate are present in smaller amounts. The heavier constituents were mainly triterpenoids such as lupenone and lupeol, which were identified as two of the main components. (Z)-Heptadec-8-ene, lupenone, and lupeol were quantified by GC-MS in SIM mode using external standards and represents 6%, 20%, and 7.8% (w/w) of the absolute oil. Moreover, odorant compounds were extracted by SPME and analyzed by GC-sniffing leading to the perception of 57 odorant zones, of which 37 compounds were identified by their odorant description, mass spectrum, retention index, and injection of the reference compound. PMID:20070087

  11. Measurement of absolute gravity acceleration in Firenze

    NASA Astrophysics Data System (ADS)

    de Angelis, M.; Greco, F.; Pistorio, A.; Poli, N.; Prevedelli, M.; Saccorotti, G.; Sorrentino, F.; Tino, G. M.

    2011-01-01

    This paper reports the results from the accurate measurement of the acceleration of gravity g taken at two separate premises in the Polo Scientifico of the University of Firenze (Italy). In these laboratories, two separate experiments aiming at measuring the Newtonian constant and testing the Newtonian law at short distances are in progress. Both experiments require an independent knowledge on the local value of g. The only available datum, pertaining to the italian zero-order gravity network, was taken more than 20 years ago at a distance of more than 60 km from the study site. Gravity measurements were conducted using an FG5 absolute gravimeter, and accompanied by seismic recordings for evaluating the noise condition at the site. The absolute accelerations of gravity at the two laboratories are (980 492 160.6 ± 4.0) μGal and (980 492 048.3 ± 3.0) μGal for the European Laboratory for Non-Linear Spectroscopy (LENS) and Dipartimento di Fisica e Astronomia, respectively. Other than for the two referenced experiments, the data here presented will serve as a benchmark for any future study requiring an accurate knowledge of the absolute value of the acceleration of gravity in the study region.

  12. A Methodology for Absolute Isotope Composition Measurement

    NASA Astrophysics Data System (ADS)

    Shen, J. J.; Lee, D.; Liang, W.

    2007-12-01

    Double spike technique was a well defined method for isotope composition measurement by TIMS of samples which have natural mass fractionation effect, but it is still a problem to define the isotope composition for double spike itself. In this study, we modified the old double spike technique and found that we could use the modified technique to solve the ¡§true¡¨ isotope composition of double spike itself. According the true isotope composition of double spike, we can measure the absolute isotope composition if the sample has natural fractionation effect. A new vector analytical method has been developed in order to obtain the true isotopic composition of a 42Ca-48Ca double spike, and this is achieved by using two different sample-spike mixtures combined with the double spike and the natural Ca data. Because the natural sample, the two mixtures, and the spike should all lie on a single mixing line, we are able to constrain the true isotopic composition of our double spike using this new approach. This method not only can be used in Ca system but also in Ti, Cr, Fe, Ni, Zn, Mo, Ba and Pb systems. The absolute double spike isotopic ratio is important, which can save a lot of time to check different reference standards. Especially for Pb, radiogenic isotope system, the decay systems embodied in three of four naturally occurring isotopes induce difficult to obtain true isotopic ratios for absolute dating.

  13. Chemical composition of French mimosa absolute oil.

    PubMed

    Perriot, Rodolphe; Breme, Katharina; Meierhenrich, Uwe J; Carenini, Elise; Ferrando, Georges; Baldovini, Nicolas

    2010-02-10

    Since decades mimosa (Acacia dealbata) absolute oil has been used in the flavor and perfume industry. Today, it finds an application in over 80 perfumes, and its worldwide industrial production is estimated five tons per year. Here we report on the chemical composition of French mimosa absolute oil. Straight-chain analogues from C6 to C26 with different functional groups (hydrocarbons, esters, aldehydes, diethyl acetals, alcohols, and ketones) were identified in the volatile fraction. Most of them are long-chain molecules: (Z)-heptadec-8-ene, heptadecane, nonadecane, and palmitic acid are the most abundant, and constituents such as 2-phenethyl alcohol, methyl anisate, and ethyl palmitate are present in smaller amounts. The heavier constituents were mainly triterpenoids such as lupenone and lupeol, which were identified as two of the main components. (Z)-Heptadec-8-ene, lupenone, and lupeol were quantified by GC-MS in SIM mode using external standards and represents 6%, 20%, and 7.8% (w/w) of the absolute oil. Moreover, odorant compounds were extracted by SPME and analyzed by GC-sniffing leading to the perception of 57 odorant zones, of which 37 compounds were identified by their odorant description, mass spectrum, retention index, and injection of the reference compound.

  14. The Carina Project: Absolute and Relative Calibrations

    NASA Astrophysics Data System (ADS)

    Corsi, C. E.; Bono, G.; Walker, A. R.; Brocato, E.; Buonanno, R.; Caputo, F.; Castellani, M.; Castellani, V.; Dall'Ora, M.; Marconi, M.; Monelli, M.; Nonino, M.; Pulone, L.; Ripepi, V.; Smith, H. A.

    We discuss the reduction strategy adopted to perform the relative and the absolute calibration of the Wide Field Imager (WFI) available at the 2.2m ESO/MPI telescope and of the Mosaic Camera (MC) available at the 4m CTIO Blanco telescope. To properly constrain the occurrence of deceptive systematic errors in the relative calibration we observed with each chip the same set of stars. Current photometry seems to suggest that the WFI shows a positional effect when moving from the top to the bottom of individual chips. Preliminary results based on an independent data set collected with the MC suggest that this camera is only marginally affected by the same problem. To perform the absolute calibration we observed with each chip the same set of standard stars. The sample covers a wide color range and the accuracy both in the B and in the V-band appears to be of the order of a few hundredths of magnitude. Finally, we briefly outline the observing strategy to improve both relative and absolute calibrations of mosaic CCD cameras.

  15. Aerosol Remote Sensing Applications for Airborne Multiangle, Multispectral Shortwave Radiometers

    NASA Astrophysics Data System (ADS)

    von Bismarck, Jonas; Ruhtz, Thomas; Starace, Marco; Hollstein, André; Preusker, René; Fischer, Jürgen

    2010-05-01

    Aerosol particles have an important impact on the surface net radiation budget by direct scattering and absorption (direct aerosol effect) of solar radiation, and also by influencing cloud formation processes (semi-direct and indirect aerosol effects). To study the former, a number of multispectral sky- and sunphotometers have been developed at the Institute for Space Sciences of the Free University of Berlin in the past two decades. The latest operational developments were the multispectral aureole- and sunphotometer FUBISS-ASA2, the zenith radiometer FUBISS-ZENITH, and the nadir polarimeter AMSSP-EM, all designed for a flexible use on moving platforms like aircraft or ships. Currently the multiangle, multispectral radiometer URMS/AMSSP (Universal Radiation Measurement System/ Airborne Multispectral Sunphotometer and Polarimeter) is under construction for a Wing-Pod of the high altitude research aircraft HALO operated by DLR. The system is expected to have its first mission on HALO in 2011. The algorithms for the retrieval of aerosol and trace gas properties from the recorded multidirectional, multispectral radiation measurements allow more than deriving standard products, as for instance the aerosol optical depth and the Angstrom exponent. The radiation measured in the solar aureole contains information about the aerosol phasefunction and therefore allows conclusions about the particle type. Furthermore, airborne instrument operation allows vertically resolved measurements. An inversion algorithm, based on radiative transfer simulations and additionally including measured vertical zenith-radiance profiles, allows conclusions about the aerosol single scattering albedo and the relative soot fraction in aerosol layers. Ozone column retrieval is performed evaluating measurements from pixels in the Chappuis absorption band. A retrieval algorithm to derive the water-vapor column from the sunphotometer measurements is currently under development. Of the various airborne

  16. Accessory oral cavity

    PubMed Central

    Gnaneswaran, Manica Ramamoorthy; Varadarajan, Usha; Srinivasan, Ramesh; Kamatchi, Sangeetha

    2012-01-01

    This is a rare case report of a patient around 11 years with the complaint of extra mouth who reported to the hospital for removal of that extra mouth. On examination there was accessory oral cavity with small upper and lower lips, seven teeth and saliva was drooling out. Under general anesthesia crevicular incision from 32 to 43 was put and labial gingiva with alveolar mucosa was reflected completely and bone exposed to lower border of mandible. There were seven teeth resembling lower permanent anterior teeth in the accessory mouth, which was excised with the accessory lips. 41 extracted and osteotomy carried out extending the incision from the extracted site and osteotomy carried out. Dermoid cyst both below and above the mylohyoid muscle and rudimentary tongue found and excised and the specimen sent for histopathological examination. The wound was closed and uneventful healing noted to the satisfaction of the patient. This is a rare and interesting case which has been documented. PMID:23833508

  17. A scanning cavity microscope.

    PubMed

    Mader, Matthias; Reichel, Jakob; Hänsch, Theodor W; Hunger, David

    2015-01-01

    Imaging the optical properties of individual nanosystems beyond fluorescence can provide a wealth of information. However, the minute signals for absorption and dispersion are challenging to observe, and only specialized techniques requiring sophisticated noise rejection are available. Here we use signal enhancement in a high-finesse scanning optical microcavity to demonstrate ultra-sensitive imaging. Harnessing multiple interactions of probe light with a sample within an optical resonator, we achieve a 1,700-fold signal enhancement compared with diffraction-limited microscopy. We demonstrate quantitative imaging of the extinction cross-section of gold nanoparticles with a sensitivity less than 1 nm(2); we show a method to improve the spatial resolution potentially below the diffraction limit by using higher order cavity modes, and we present measurements of the birefringence and extinction contrast of gold nanorods. The demonstrated simultaneous enhancement of absorptive and dispersive signals promises intriguing potential for optical studies of nanomaterials, molecules and biological nanosystems. PMID:26105690

  18. Calibration chain design based on integrating sphere transfer radiometer for SI-traceable on-orbit spectral radiometric calibration and its uncertainty analysis

    NASA Astrophysics Data System (ADS)

    Zhao, Wei-Ning; Fang, Wei; Sun, Li-Wei; Cui, Li-Hong; Wang, Yu-Peng

    2016-09-01

    In order to satisfy the requirement of SI-traceable on-orbit absolute radiation calibration transfer with high accuracy for satellite remote sensors, a transfer chain consisting of a fiber coupling monochromator (FBM) and an integrating sphere transfer radiometer (ISTR) was designed in this paper. Depending on the Sun, this chain based on detectors provides precise spectral radiometric calibration and measurement to spectrometers in the reflective solar band (RSB) covering 300-2500 nm with a spectral bandwidth of 0.5-6 nm. It shortens the traditional chain based on lamp source and reduces the calibration uncertainty from 5% to 0.5% by using the cryogenic radiometer in space as a radiometric benchmark and trap detectors as secondary standard. This paper also gives a detailed uncertainty budget with reasonable distribution of each impact factor, including the weak spectral signal measurement with uncertainty of 0.28%. According to the peculiar design and comprehensive uncertainty analysis, it illustrates that the spectral radiance measurement uncertainty of the ISTR system can reach to 0.48%. The result satisfies the requirements of SI-traceable on-orbit calibration and has wider significance for expanding the application of the remote sensing data with high-quality. Project supported by the National Natural Science Foundation of China (Grant No. 41474161) and the National High-Technology Program of China (Grant No. 2015AA123703).

  19. Calibration chain design based on integrating sphere transfer radiometer for SI-traceable on-orbit spectral radiometric calibration and its uncertainty analysis

    NASA Astrophysics Data System (ADS)

    Zhao, Wei-Ning; Fang, Wei; Sun, Li-Wei; Cui, Li-Hong; Wang, Yu-Peng

    2016-09-01

    In order to satisfy the requirement of SI-traceable on-orbit absolute radiation calibration transfer with high accuracy for satellite remote sensors, a transfer chain consisting of a fiber coupling monochromator (FBM) and an integrating sphere transfer radiometer (ISTR) was designed in this paper. Depending on the Sun, this chain based on detectors provides precise spectral radiometric calibration and measurement to spectrometers in the reflective solar band (RSB) covering 300–2500 nm with a spectral bandwidth of 0.5–6 nm. It shortens the traditional chain based on lamp source and reduces the calibration uncertainty from 5% to 0.5% by using the cryogenic radiometer in space as a radiometric benchmark and trap detectors as secondary standard. This paper also gives a detailed uncertainty budget with reasonable distribution of each impact factor, including the weak spectral signal measurement with uncertainty of 0.28%. According to the peculiar design and comprehensive uncertainty analysis, it illustrates that the spectral radiance measurement uncertainty of the ISTR system can reach to 0.48%. The result satisfies the requirements of SI-traceable on-orbit calibration and has wider significance for expanding the application of the remote sensing data with high-quality. Project supported by the National Natural Science Foundation of China (Grant No. 41474161) and the National High-Technology Program of China (Grant No. 2015AA123703).

  20. Limits of Precipitation Detection from Microwave Radiometers and Sounders

    NASA Astrophysics Data System (ADS)

    Munchak, S. J.; Skofronick-Jackson, G.; Johnson, B. T.

    2012-04-01

    The Global Precipitation Measurement (GPM) mission will unify and draw from numerous microwave conical scanning imaging radiometers and cross-track sounders, many of which already in operation, to provide near real-time precipitation estimates worldwide at 3-hour intervals. Some of these instruments were designed for primary purposes unrelated to precipitation remote sensing. Therefore it is worthwhile to evaluate the strengths and weaknesses of each set of channels with respect to precipitation detection to fully understand their role in the GPM constellation. The GPM radiometer algorithm will use an observationally-based Bayesian retrieval with common databases of precipitation profiles for all sensors. Since these databases are still under development and will not be truly complete until the GPM core satellite has completed at least one year of dual-frequency radar observations, a screening method based upon retrieval of non-precipitation parameters related to the surface and atmospheric state is used in this study. A cost function representing the departure of modeled radiances from their observed values plus the departure of surface and atmospheric parameters from the TELSEM emissivity atlas and MERRA reanalysis is used as an indicator of precipitation. Using this method, two datasets are used to evaluate precipitation detection: One year of matched AMSR-E and AMSU-B/MHS overpasses with CloudSat used as validation globally; and SSMIS overpasses over the United States using the National Mosaic and QPE (NMQ) as validation. The Heidke Skill Score (HSS) is used as a metric to evaluate detection skill over different surfaces, seasons, and across different sensors. Non-frozen oceans give the highest HSS for all sensors, followed by bare land and coasts, then snow-covered land and sea ice. Negligible skill is present over ice sheets. Sounders tend to have higher skill than imagers over complex surfaces (coast, snow, and sea ice), whereas imagers have higher skill

  1. Cloud thermodynamic phase detection with polarimetrically sensitive passive sky radiometers

    NASA Astrophysics Data System (ADS)

    Knobelspiesse, K.; van Diedenhoven, B.; Marshak, A.; Dunagan, S.; Holben, B.; Slutsker, I.

    2014-12-01

    The primary goal of this project has been to investigate if ground-based visible and near-infrared passive radiometers that have polarization sensitivity can determine the thermodynamic phase of overlying clouds, i.e. if they are comprised of liquid droplets or ice particles. While this knowledge is important by itself for our understanding of the global climate, it can also help improve cloud property retrieval algorithms that use total (unpolarized) radiance to determine Cloud Optical Depth (COD). This is a potentially unexploited capability of some instruments in the NASA Aerosol Robotic Network (AERONET), which, if practical, could expand the products of that global instrument network at minimal additional cost. We performed simulations that found, for zenith observations, cloud thermodynamic phase is often expressed in the sign of the Q component of the Stokes polarization vector. We chose our reference frame as the plane containing solar and observation vectors, so the sign of Q indicates the polarization direction, parallel (positive) or perpendicular (negative) to that plane. Since the quantity of polarization is inversely proportional to COD, optically thin clouds are most likely to create a signal greater than instrument noise. Besides COD and instrument accuracy, other important factors for the determination of cloud thermodynamic phase are the solar and observation geometry (scattering angles between 40 and 60° are best), and the properties of ice particles (pristine particles may have halos or other features that make them difficult to distinguish from water droplets at specific scattering angles, while extreme ice crystal aspect ratios polarize more than compact particles). We tested the conclusions of our simulations using data from polarimetrically sensitive versions of the Cimel 318 sun photometer/radiometer that comprise AERONET. Most algorithms that exploit Cimel polarized observations use the Degree of Linear Polarization (DoLP), not the

  2. Quench studies of ILC cavities

    SciTech Connect

    Eremeev, Grigory; Geng, Rongli; Palczewski, Ari; Dai, Jin

    2011-07-01

    Quench limits accelerating gradient in SRF cavities to a gradient lower than theoretically expected for superconducting niobium. Identification of the quenching site with thermometry and OST, optical inspection, and replica of the culprit is an ongoing effort at Jefferson Lab aimed at better understanding of this limiting phenomenon. In this contribution we present our finding with several SRF cavities that were limited by quench.

  3. Trislot-cavity microstrip antenna

    NASA Technical Reports Server (NTRS)

    Ellis, H., Jr.

    1981-01-01

    Flush-mountable assembly composed of disk radiator sandwiched between planes of metal-clad dielectric board has greater bandwidths and beamwidths than simple disk antenna. Conducting planes connect so that disk is enclosed in cavity with Y-shaped slot in top plane. Cavity is excited by microwave energy from disk and radiates from trislot aperature.

  4. Low-level water vapor fields from the VISSR atmospheric sounder (VAS) split window channels at 11 and 12 microns. [visible infrared spin scan radiometer

    NASA Technical Reports Server (NTRS)

    Chesters, D.; Uccellini, L.; Robinson, W.

    1982-01-01

    A series of high-resolution water vapor fields were derived from the 11 and 12 micron channels of the VISSR Atmospheric Sounder (VAS) on GOES-5. The low-level tropospheric moisture content was separated from the surface and atmospheric radiances by using the differential adsorption across the 'split window' along with the average air temperature from imbedded radiosondes. Fields of precipitable water are presented in a time sequence of five false color images taken over the United States at 3-hour intervals. Vivid subsynoptic and mesoscale patterns evolve at 15 km horizontal resolution over the 12-hour observing period. Convective cloud formations develop from several areas of enhanced low-level water vapor, especially where the vertical water vapor gradient relatively strong. Independent verification at radiosonde sites indicates fairly good absolute accuracy, and the spatial and temporal continuity of the water vapor features indicates very good relative accuracy. Residual errors are dominated by radiometer noise and unresolved clouds.

  5. The Aquarius Ocean Salinity Mission High Stability L-band Radiometer

    NASA Technical Reports Server (NTRS)

    Pellerano, Fernando A.; Piepmeier, Jeffrey; Triesky, Michael; Horgan, Kevin; Forgione, Joshua; Caldwell, James; Wilson, William J.; Yueh, Simon; Spencer, Michael; McWatters, Dalia; Freedman, Adam

    2006-01-01

    The NASA Earth Science System Pathfinder (ESSP) mission Aquarius, will measure global ocean surface salinity with approx.120 km spatial resolution every 7-days with an average monthly salinity accuracy of 0.2 psu (parts per thousand). This requires an L-band low-noise radiometer with the long-term calibration stability of less than or equal to 0.15 K over 7 days. The instrument utilizes a push-broom configuration which makes it impractical to use a traditional warm load and cold plate in front of the feedhorns. Therefore, to achieve the necessary performance Aquarius utilizes a Dicke radiometer with noise injection to perform a warm - hot calibration. The radiometer sequence between antenna, Dicke load, and noise diode has been optimized to maximize antenna observations and therefore minimize NEDT. This is possible due the ability to thermally control the radiometer electronics and front-end components to 0.1 Crms over 7 days.

  6. L-Band Radiometer Experiment in the SMOS Test Site Upper Danube

    NASA Astrophysics Data System (ADS)

    Schlenz, Florian; Gebhardt, Timo; Loew, Alexander; Marzahn, Philip; Mauser, Wolfram

    2010-12-01

    In the frame of calibration and validation activities for ESA's soil moisture and ocean salinity mission, SMOS, the University of Munich operates a ground based L-band radiometer (ELBARA II) at 1.4 GHz to test and validate the radiative transfer model L-MEB also used in the SMOS Level 2 processor. The radiometer is situated on a test site near Puch, about 30 km west of Munich in the Upper Danube watershed in southern Germany in a temperate agricultural area. It is mounted on a scaffolding that allows to rotate the antenna which enables it to look at 2 different fields with grass and winter rape as land use respectively. In addition to the radiometer, a variety of complementary sensors are installed measuring all important meteorological and hydrological parameters. First datasets of the radiometer experiment are presented.

  7. Analysis of Shuttle Multispecral Infrared Radiometer measurements of the western Saudi Arabian shield.

    USGS Publications Warehouse

    Rowan, L.C.; Goetz, A.F.H.; Abbott, E.

    1987-01-01

    During the November 12-14, 1981 mission of the space shuttle Columbia, the Shuttle Multispectral Infrared Radiometer (SMIRR) recorded radiances in 10 channels along a 100m wide groundtrack across the western Saudi Arabian shield.-from Authors

  8. A sea ice concentration estimation algorithm utilizing radiometer and SAR data

    NASA Astrophysics Data System (ADS)

    Karvonen, J.

    2014-04-01

    We have studied the possibility of combining the high-resolution SAR segmentation and ice concentration estimated by radiometer brightness temperatures. Here we present an algorithm for mapping a radiometer-based concentration value for each SAR segment. The concentrations are estimated by a MLP neural network which has the AMSR-2 radiometer polarization ratios and gradient ratios of four radiometer channels as its inputs. The results have been compared numerically to the gridded FMI ice chart concentrations and high-resolution AMSR-2 ASI algorithm concentrations provided by University of Hamburg and also visually to the AMSR-2 bootstrap algorithm concentrations, which are given in much coarser resolution. The results when compared to FMI ice charts were very promising.

  9. First Results of the Galileo Photopolarimeter/Radiometer on Jupiter and the Galilean Satellites

    NASA Technical Reports Server (NTRS)

    Orton, G. S.; Spencer, J. R.; Travis, L. D.; Martin, T. Z.; Tamppari, L. K.

    1996-01-01

    Photopolarimetric-Radiometer (PPR) 200-km resolution maps of daytime temperatures on Ganymede show the expected anticorrelation with albedo, but morning temperatures are about 10K warmer than expected.

  10. Effect of vegetation on soil moisture sensing observed from orbiting microwave radiometers

    NASA Technical Reports Server (NTRS)

    Wang, J. R.

    1985-01-01

    The microwave radiometric measurements made by the Skylab 1.4 GHz radiometer and by the 6.6 GHz and 10.7 GHz channels of the Nimbus-7 Scanning Multichannel Microwave Radiometer were analyzed to study the large-area soil moisture variations of land surfaces. Two regions in Texas, one with sparse and the other with dense vegetation covers, were selected for the study. The results gave a confirmation of the vegetation effect observed by ground-level microwave radiometers. Based on the statistics of the satellite data, it was possible to estimate surface soil moisture in about five different levels from dry to wet conditions with a 1.4 GHz radiometer, provided that the biomass of the vegetation cover could be independently measured. At frequencies greater than about 6.6 GHz, the radiometric measurements showed little sensitivity to moisture variation for vegetation-covered soils. The effects of polarization in microwave emission were studied also.

  11. Evaluating Solar Resource Data Obtained from Multiple Radiometers Deployed at the National Renewable Energy Laboratory: Preprint

    SciTech Connect

    Habte, A.; Sengupta, M.; Andreas, A.; Wilcox, S.; Stoffel, T.

    2014-09-01

    Solar radiation resource measurements from radiometers are used to predict and evaluate the performance of photovoltaic and concentrating solar power systems, validate satellite-based models for estimating solar resources, and advance research in solar forecasting and climate change. This study analyzes the performance of various commercially available radiometers used for measuring global horizontal irradiances (GHI) and direct normal irradiances (DNI). These include pyranometers, pyrheliometers, rotating shadowband irradiometers, and a pyranometer with a shading ring deployed at the National Renewable Energy Laboratory's Solar Radiation Research Laboratory (SRRL). The radiometers in this study were deployed for one year (from April 1, 2011, through March 31, 2012) and compared to measurements from radiometers with the lowest values of estimated measurement uncertainties for producing reference GHI and DNI.

  12. Mineral identification from orbit: Initial results from the shuttle multispectral infrared radiometer

    USGS Publications Warehouse

    Goetz, A.F.H.; Rowan, L.C.; Kingston, M.J.

    1982-01-01

    A shuttle-borne radiometer containing ten channels in the reflective infrared has demonstrated that direct identification of carbonates and hydroxyl-bearing minerals is possible by remote measurement from Earth orbit. Copyright ?? 1982 AAAS.

  13. Next-Generation Thermal Infrared Multi-Body Radiometer Experiment (TIMBRE)

    NASA Astrophysics Data System (ADS)

    Kenyon, M.; Mariani, G.; Johnson, B.; Brageot, E.; Hayne, P.

    2016-10-01

    We have developed an instrument concept called TIMBRE which belongs to the important class of instruments called thermal imaging radiometers (TIRs). TIMBRE is the next-generation TIR with unparalleled performance compared to the state-of-the-art.

  14. Radiometric characterization of the NASA GSFC radiometric calibration facility primary transfer radiometer

    NASA Astrophysics Data System (ADS)

    Cooper, John W.; Brown, Steven W.; Abel, Peter; Marketon, John E.; Butler, James J.

    2004-11-01

    As part of an effort to reduce uncertainties in the radiometric calibrations of integrating sphere sources and standard lamp irradiance sources, the Goddard Space Flight Center (GSFC) Radiometric Calibration Facility (RCF) primary radiometer was characterized at the NIST facility for Spectral Irradiance and Radiance Calibrations with Uniform Sources (SIRCUS). Specifically, the radiometer's slit spectral function was measured and the magnitude of out-of-band stray light was determined. The characterization also revealed significant contributions of spectral stray light due to fluorescence of the radiometer's input sphere. The RCF examined the effects of stray light and sphere fluorescence in the radiometer on source radiance calibrations along with approaches to reduce those sources of measurement error.

  15. Geosynchronous Microwave Atmospheric Sounding Radiometer (MASR) feasibility studies. Volume 1: Management summary

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The mission of the microwave atmospheric sounding radiometer (MASR) is to collect data to aid in the observation and prediction of severe storms. The geosynchronous orbit allows the continuous atmospheric measurement needed to resolve mesoscale dynamics. The instrument may operate in conjunction with this document, Volume 1 - Management, which summarizes the highlights of final reports on both the radiometer instrument and antenna studies. The radiometer instrument summary includes a synopsis of Volume 2 - Radiometer Receiver Feasibility, including design, recommended configuration, performance estimates, and weight and power estimates. The summary of the antenna study includes a synopsis of Volume 3 - Antenna Feasibility, including preliminary design tradeoffs, performance of selected design, and details of the mechanical/thermal design.

  16. Monochromatic radio frequency accelerating cavity

    DOEpatents

    Giordano, S.

    1984-02-09

    A radio frequency resonant cavity having a fundamental resonant frequency and characterized by being free of spurious modes. A plurality of spaced electrically conductive bars are arranged in a generally cylindrical array within the cavity to define a chamber between the bars and an outer solid cylindrically shaped wall of the cavity. A first and second plurality of mode perturbing rods are mounted in two groups at determined random locations to extend radially and axially into the cavity thereby to perturb spurious modes and cause their fields to extend through passageways between the bars and into the chamber. At least one body of lossy material is disposed within the chamber to damp all spurious modes that do extend into the chamber thereby enabling the cavity to operate free of undesired spurious modes.

  17. Monochromatic radio frequency accelerating cavity

    DOEpatents

    Giordano, Salvatore

    1985-01-01

    A radio frequency resonant cavity having a fundamental resonant frequency and characterized by being free of spurious modes. A plurality of spaced electrically conductive bars are arranged in a generally cylindrical array within the cavity to define a chamber between the bars and an outer solid cylindrically shaped wall of the cavity. A first and second plurality of mode perturbing rods are mounted in two groups at determined random locations to extend radially and axially into the cavity thereby to perturb spurious modes and cause their fields to extend through passageways between the bars and into the chamber. At least one body of lossy material is disposed within the chamber to damp all spurious modes that do extend into the chamber thereby enabling the cavity to operate free of undesired spurious modes.

  18. Mechanical Properties of Niobium Cavities

    SciTech Connect

    Ciovati, Gianluigi; Dhakal, Pashupati; Matalevich, Joseph R.; Myneni, Ganapati Rao

    2015-09-01

    The mechanical stability of bulk Nb cavity is an important aspect to be considered in relation to cavity material, geometry and treatments. Mechanical properties of Nb are typically obtained from uniaxial tensile tests of small samples. In this contribution we report the results of measurements of the resonant frequency and local strain along the contour of single-cell cavities made of ingot and fine-grain Nb of different purity subjected to increasing uniform differential pressure, up to 6 atm. Measurements have been done on cavities subjected to different heat treatments. Good agreement between finite element analysis simulations and experimental data in the elastic regime was obtained with a single set of values of Young’s modulus and Poisson’s ratio. The experimental results indicate that the yield strength of medium-purity ingot Nb cavities is higher than that of fine-grain, high-purity Nb.

  19. Instrumentation and First Results of the Reflected Solar Demonstration System for the Climate Absolute Radiance and Refractivity Observatory

    NASA Technical Reports Server (NTRS)

    McCorkel, Joel; Thome, Kurtis; Hair, Jason; McAndrew, Brendan; Jennings, Don; Rabin, Douglas; Daw, Adrian; Lundsford, Allen

    2012-01-01

    The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission key goals include enabling observation of high accuracy long-term climate change trends, use of these observations to test and improve climate forecasts, and calibration of operational and research sensors. The spaceborne instrument suites include a reflected solar spectroradiometer, emitted infrared spectroradiometer, and radio occultation receivers. The requirement for the RS instrument is that derived reflectance must be traceable to Sl standards with an absolute uncertainty of <0.3% and the error budget that achieves this requirement is described in previo1L5 work. This work describes the Solar/Lunar Absolute Reflectance Imaging Spectroradiometer (SOLARIS), a calibration demonstration system for RS instrument, and presents initial calibration and characterization methods and results. SOLARIS is an Offner spectrometer with two separate focal planes each with its own entrance aperture and grating covering spectral ranges of 320-640, 600-2300 nm over a full field-of-view of 10 degrees with 0.27 milliradian sampling. Results from laboratory measurements including use of integrating spheres, transfer radiometers and spectral standards combined with field-based solar and lunar acquisitions are presented. These results will be used to assess the accuracy and repeatability of the radiometric and spectral characteristics of SOLARIS, which will be presented against the sensor-level requirements addressed in the CLARREO RS instrument error budget.

  20. A comparison of absolute calibrations of a radiation thermometer based on a monochromator and a tunable source

    SciTech Connect

    Keawprasert, T.; Anhalt, K.; Taubert, D. R.; Sperling, A.; Schuster, M.; Nevas, S.

    2013-09-11

    An LP3 radiation thermometer was absolutely calibrated at a newly developed monochromator-based set-up and the TUneable Lasers in Photometry (TULIP) facility of PTB in the wavelength range from 400 nm to 1100 nm. At both facilities, the spectral radiation of the respective sources irradiates an integrating sphere, thus generating uniform radiance across its precision aperture. The spectral irradiance of the integrating sphere is determined via an effective area of a precision aperture and a Si trap detector, traceable to the primary cryogenic radiometer of PTB. Due to the limited output power from the monochromator, the absolute calibration was performed with the measurement uncertainty of 0.17 % (k= 1), while the respective uncertainty at the TULIP facility is 0.14 %. Calibration results obtained by the two facilities were compared in terms of spectral radiance responsivity, effective wavelength and integral responsivity. It was found that the measurement results in integral responsivity at the both facilities are in agreement within the expanded uncertainty (k= 2). To verify the calibration accuracy, the absolutely calibrated radiation thermometer was used to measure the thermodynamic freezing temperatures of the PTB gold fixed-point blackbody.

  1. A comparison of absolute calibrations of a radiation thermometer based on a monochromator and a tunable source

    NASA Astrophysics Data System (ADS)

    Keawprasert, T.; Anhalt, K.; Taubert, D. R.; Sperling, A.; Schuster, M.; Nevas, S.

    2013-09-01

    An LP3 radiation thermometer was absolutely calibrated at a newly developed monochromator-based set-up and the TUneable Lasers in Photometry (TULIP) facility of PTB in the wavelength range from 400 nm to 1100 nm. At both facilities, the spectral radiation of the respective sources irradiates an integrating sphere, thus generating uniform radiance across its precision aperture. The spectral irradiance of the integrating sphere is determined via an effective area of a precision aperture and a Si trap detector, traceable to the primary cryogenic radiometer of PTB. Due to the limited output power from the monochromator, the absolute calibration was performed with the measurement uncertainty of 0.17 % (k = 1), while the respective uncertainty at the TULIP facility is 0.14 %. Calibration results obtained by the two facilities were compared in terms of spectral radiance responsivity, effective wavelength and integral responsivity. It was found that the measurement results in integral responsivity at the both facilities are in agreement within the expanded uncertainty (k = 2). To verify the calibration accuracy, the absolutely calibrated radiation thermometer was used to measure the thermodynamic freezing temperatures of the PTB gold fixed-point blackbody.

  2. Advanced Microwave Precipitation Radiometer (AMPR) for remote observation of precipitation

    NASA Technical Reports Server (NTRS)

    Galliano, J. A.; Platt, R. H.

    1990-01-01

    The design, development, and tests of the Advanced Microwave Precipitation Radiometer (AMPR) operating in the 10 to 85 GHz range specifically for precipitation retrieval and mesoscale storm system studies from a high altitude aircraft platform (i.e., ER-2) are described. The primary goals of AMPR are the exploitation of the scattering signal of precipitation at frequencies near 10, 19, 37, and 85 GHz together to unambiguously retrieve precipitation and storm structure and intensity information in support of proposed and planned space sensors in geostationary and low earth orbit, as well as storm-related field experiments. The development of AMPR will have an important impact on the interpretation of microwave radiances for rain retrievals over both land and ocean for the following reasons: (1) A scanning instrument, such as AMPR, will allow the unambiguous detection and analysis of features in two dimensional space, allowing an improved interpretation of signals in terms of cloud features, and microphysical and radiative processes; (2) AMPR will offer more accurate comparisons with ground-based radar data by feature matching since the navigation of the ER-2 platform can be expected to drift 3 to 4 km per hour of flight time; and (3) AMPR will allow underflights of the SSM/I satellite instrument with enough spatial coverage at the same frequencies to make meaningful comparisons of the data for precipitation studies.

  3. Next-generation pushbroom filter radiometers for remote sensing

    NASA Astrophysics Data System (ADS)

    Tarde, Richard W.; Dittman, Michael G.; Kvaran, Geir E.

    2012-09-01

    Individual focal plane size, yield, and quality continue to improve, as does the technology required to combine these into large tiled formats. As a result, next-generation pushbroom imagers are replacing traditional scanning technologies in remote sensing applications. Pushbroom architecture has inherently better radiometric sensitivity and significantly reduced payload mass, power, and volume than previous generation scanning technologies. However, the architecture creates challenges achieving the required radiometric accuracy performance. Achieving good radiometric accuracy, including image spectral and spatial uniformity, requires creative optical design, high quality focal planes and filters, careful consideration of on-board calibration sources, and state-of-the-art ground test facilities. Ball Aerospace built the Landsat Data Continuity Mission (LDCM) next-generation Operational Landsat Imager (OLI) payload. Scheduled to launch in 2013, OLI provides imagery consistent with the historical Landsat spectral, spatial, radiometric, and geometric data record and completes the generational technology upgrade from the Enhanced Thematic Mapper (ETM+) whiskbroom technology to modern pushbroom technology afforded by advanced focal planes. We explain how Ball's capabilities allowed producing the innovative next-generational OLI pushbroom filter radiometer that meets challenging radiometric accuracy or calibration requirements. OLI will improve the multi-decadal land surface observation dataset dating back to the 1972 launch of ERTS-1 or Landsat 1.

  4. Retrieval of Atmospheric Temperature from Airborne Microwave Radiometer Observations

    NASA Astrophysics Data System (ADS)

    Xu, Jian; Schreier, Franz; Kenntner, Mareike; Fix, Andreas; Trautmann, Thomas

    2015-06-01

    Atmospheric temperature is a key geophysical parameter associated with fields such as meteorology, climatology, or photochemistry. There exist several techniques to measure temperature profiles. In the case of microwave remote sensing, the vertical temperature profile can be estimated from thermal emission lines of molecular oxygen. The MTP (Microwave Temperature Profiler) instrument is an airborne radiometer developed at the Jet Propulsion Laboratory (JPL), United States. The instrument passively measures natural thermal emission from oxygen lines at 3 frequencies and at a selection of 10 viewing angles (from near zenith to near nadir). MTP has participated in hundreds of flights, including on DLR’s Falcon and HALO aircrafts. These flights have provided data of the vertical temperature distribution from the troposphere to the lower stratosphere with a good temporal and spatial resolution. In this work, we present temperature retrievals based on the Tikhonov-type regularized nonlinear least squares fitting method. In particular, Jacobians (i.e. temperature derivatives) are evaluated by means of automatic differentiation. The retrieval performance from the MTP measurements is analyzed by using synthetic data. Besides, the vertical sensitivity of the temperature retrieval is studied by weighting functions characterizing the sensitivity of the transmission at different frequencies with respect to changes of altitude levels.

  5. Wiener filtering of the COBE Differential Microwave Radiometer data

    NASA Technical Reports Server (NTRS)

    Bunn, Emory F.; Fisher, Karl B.; Hoffman, Yehuda; Lahav, Ofer; Silk, Joseph; Zaroubi, Saleem

    1994-01-01

    We derive an optimal linear filter to suppress the noise from the cosmic background explorer satellite (COBE) Differential Microwave Radiometer (DMR) sky maps for a given power spectrum. We then apply the filter to the first-year DMR data, after removing pixels within 20 deg of the Galactic plane from the data. We are able to identify particular hot and cold spots in the filtered maps at a level 2 to 3 times the noise level. We use the formalism of constrained realizations of Gaussian random fields to assess the uncertainty in the filtered sky maps. In addition to improving the signal-to-noise ratio of the map as a whole, these techniques allow us to recover some information about the cosmic microwave background anisotropy in the missing Galactic plane region. From these maps we are able to determine which hot and cold spots in the data are statistically significant, and which may have been produced by noise. In addition, the filtered maps can be used for comparison with other experiments on similar angular scales.

  6. Pushbroom microwave radiometer results from HAPEX-MOBILHY

    SciTech Connect

    Nichols, W.E. ); Cuenca, R.H. . Dept. of Bioresource Engineering); Schmugge, T.J. . Agricultural Research Service); Wang, J.R. )

    1993-11-01

    The NASA C-130 remote sensing aircraft was in Toulouse, France from 25 May through 4 July 1986, for participation in the HAPEX-MOBILHY program. Spectral and radiometric data were collected by C-130-borne sensors in the visible, infrared, and microwave wavelengths. This data provided information on the spatial and temporal variations of surface parameters such as vegetation indices, surface temperature, and surface soil moisture. The Pushbroom Microwave Radiometer (PBMR) was used to collect passive microwave brightness temperature data. This four-beam sensor operates at the 21-cm wavelength, providing cross-track coverage approximately 1.2 times the aircraft altitude. Observed brightness temperatures for the period were high, ranging from above 230 K to about 290 K. Brightness temperature images appeared to correspond well to spatial and temporal soil moisture variation. When results from wetter soil conditions encountered in another experiment were included, the regression improved dramatically. Based on similar research with the PBMR and an understanding of the ground data collection program, this result was examined to produce recommendations for improvements to future passive microwave research and data collection programs. Examples of surface soil moisture maps generated with PBMR data are presented which appear to be representative of the actual soil moisture conditions.

  7. Daily quality assurance software for a satellite radiometer system

    NASA Technical Reports Server (NTRS)

    Keegstra, P. B.; Smoot, G. F.; Bennett, C. L.; Aymon, J.; Backus, C.; Deamici, G.; Hinshaw, G.; Jackson, P. D.; Kogut, A.; Lineweaver, C.

    1992-01-01

    Six Differential Microwave Radiometers (DMR) on COBE (Cosmic Background Explorer) measure the large-angular-scale isotropy of the cosmic microwave background (CMB) at 31.5, 53, and 90 GHz. Quality assurance software analyzes the daily telemetry from the spacecraft to ensure that the instrument is operating correctly and that the data are not corrupted. Quality assurance for DMR poses challenging requirements. The data are differential, so a single bad point can affect a large region of the sky, yet the CMB isotropy requires lengthy integration times (greater than 1 year) to limit potential CMB anisotropies. Celestial sources (with the exception of the moon) are not, in general, visible in the raw differential data. A 'quicklook' software system was developed that, in addition to basic plotting and limit-checking, implements a collection of data tests as well as long-term trending. Some of the key capabilities include the following: (1) stability analysis showing how well the data RMS averages down with increased data; (2) a Fourier analysis and autocorrelation routine to plot the power spectrum and confirm the presence of the 3 mK 'cosmic' dipole signal; (3) binning of the data against basic spacecraft quantities such as orbit angle; (4) long-term trending; and (5) dipole fits to confirm the spacecraft attitude azimuth angle.

  8. Time series inversion of spectra from ground-based radiometers

    NASA Astrophysics Data System (ADS)

    Christensen, O. M.; Eriksson, P.

    2013-07-01

    Retrieving time series of atmospheric constituents from ground-based spectrometers often requires different temporal averaging depending on the altitude region in focus. This can lead to several datasets existing for one instrument, which complicates validation and comparisons between instruments. This paper puts forth a possible solution by incorporating the temporal domain into the maximum a posteriori (MAP) retrieval algorithm. The state vector is increased to include measurements spanning a time period, and the temporal correlations between the true atmospheric states are explicitly specified in the a priori uncertainty matrix. This allows the MAP method to effectively select the best temporal smoothing for each altitude, removing the need for several datasets to cover different altitudes. The method is compared to traditional averaging of spectra using a simulated retrieval of water vapour in the mesosphere. The simulations show that the method offers a significant advantage compared to the traditional method, extending the sensitivity an additional 10 km upwards without reducing the temporal resolution at lower altitudes. The method is also tested on the Onsala Space Observatory (OSO) water vapour microwave radiometer confirming the advantages found in the simulation. Additionally, it is shown how the method can interpolate data in time and provide diagnostic values to evaluate the interpolated data.

  9. Time series inversion of spectra from ground-based radiometers

    NASA Astrophysics Data System (ADS)

    Christensen, O. M.; Eriksson, P.

    2013-02-01

    Retrieving time series of atmospheric constituents from ground-based spectrometers often requires different temporal averaging depending on the altitude region in focus. This can lead to several datasets existing for one instrument which complicates validation and comparisons between instruments. This paper puts forth a possible solution by incorporating the temporal domain into the maximum a posteriori (MAP) retrieval algorithm. The state vector is increased to include measurements spanning a time period, and the temporal correlations between the true atmospheric states are explicitly specified in the a priori uncertainty matrix. This allows the MAP method to effectively select the best temporal smoothing for each altitude, removing the need for several datasets to cover different altitudes. The method is compared to traditional averaging of spectra using a simulated retrieval of water vapour in the mesosphere. The simulations show that the method offers a significant advantage compared to the traditional method, extending the sensitivity an additional 10 km upwards without reducing the temporal resolution at lower altitudes. The method is also tested on the OSO water vapour microwave radiometer confirming the advantages found in the simulation. Additionally, it is shown how the method can interpolate data in time and provide diagnostic values to evaluate the interpolated data.

  10. Planar electrical-substitution carbon nanotube cryogenic radiometer

    NASA Astrophysics Data System (ADS)

    Tomlin, N. A.; White, M.; Vayshenker, I.; Woods, S. I.; Lehman, J. H.

    2015-04-01

    We have developed a fully-lithographic electrical-substitution planar bolometric-radiometer (PBR) that employs multiwall vertically-aligned carbon nanotubes (VACNT) as the absorber and thermistor, micro-machined Si as the weak thermal link and thin-film Mo as the electrical heater. The near-unity absorption of the VACNT over a broad wavelength range permits a planar geometry, compatible with lithographic fabrication. We present performance results on a PBR with an absorption of 0.999 35 at 1550 nm, a thermal conductance of 456 µW K-1 at 4 K and a time constant (1/e) of 7.7 ms. A single measurement of approximately 100 µW optical power at 1550 nm achieved in less than 100 s yields an expanded uncertainty of 0.14% (k = 2). We also observe an elevated superconducting transition temperature of 3.884 K for the Mo heater, which opens the possibility of future devices incorporating more sensitive thermistors and superconducting thin-film wiring. Contribution of an agency of the US government; not subject to copyright

  11. Advanced Very High Resolution Radiometer Normalized Difference Vegetation Index Composites

    USGS Publications Warehouse

    ,

    2005-01-01

    The Advanced Very High Resolution Radiometer (AVHRR) is a broad-band scanner with four to six bands, depending on the model. The AVHRR senses in the visible, near-, middle-, and thermal- infrared portions of the electromagnetic spectrum. This sensor is carried on a series of National Oceanic and Atmospheric Administration (NOAA) Polar Orbiting Environmental Satellites (POES), beginning with the Television InfraRed Observation Satellite (TIROS-N) in 1978. Since 1989, the United States Geological Survey (USGS) Center for Earth Resources Observation and Science (EROS) has been mapping the vegetation condition of the United States and Alaska using satellite information from the AVHRR sensor. The vegetation condition composites, more commonly called greenness maps, are produced every week using the latest information on the growth and condition of the vegetation. One of the most important aspects of USGS greenness mapping is the historical archive of information dating back to 1989. This historical stretch of information has allowed the USGS to determine a 'normal' vegetation condition. As a result, it is possible to compare the current week's vegetation condition with normal vegetation conditions. An above normal condition could indicate wetter or warmer than normal conditions, while a below normal condition could indicate colder or dryer than normal conditions. The interpretation of departure from normal will depend on the season and geography of a region.

  12. Cloud optical parameters as derived from the multispectral cloud radiometer

    NASA Technical Reports Server (NTRS)

    Nakajima, Teruyuki; King, Michael D.

    1990-01-01

    Simultaneous measurements of the liquid water content and particle size have assumed an important role in cloud physics as they help elucidate the mechanism of cloud particle formation and the mechanism of air mass-mixing in stratus clouds. Such measurements can reveal the modification of cloud air masses by anthropogenic aerosol particles (Coakley et al. 1987, Durkee 1989). Studies of the climatic impact of these modification processes on cloud microphysics seems to be urgent for understanding mechanisms of climate change. General Circulation Model (GCM) simulations can be improved by introducing a parameterization of cloud optical properties in terms of integrated liquid water content (liquid water path) and particle size (Slingo 1989). Motivated by the above mentioned circumstances, remote sensing techniques were developed for simultaneously retrieving the cloud optical thickness and effective particle radius, from which the liquid water path can be inferred. Statistical features of the cloud optical thickness (or liquid water path) and effective particle size for marine stratocumulus clouds are presented. These results were obtained during 4 days (7, 10, 13, and 16 July 1987) of observations with the Multispectral Cloud Radiometer (ER-2) and the Thematic Mapper (LANDSAT-5) during the First ISCCP Regional Experiment (FIRE).

  13. Automated test-site radiometer for vicarious calibration

    NASA Astrophysics Data System (ADS)

    Li, Xin; Yin, Ya-peng; Liu, En-chao; Zhang, Yan-na; Xun, Li-na; Wei, Wei; Zhang, Zhi-peng; Qiu, Gang-gang; Zhang, Quan; Zheng, Xiao-bing

    2014-11-01

    In order to realize unmanned vicarious calibration, Automated Test-site Radiometer (ATR) was developed for surface reflectance measurements. ATR samples the spectrum from 400nm-1600 nm with 8 interference filters coupled with silicon and InGaAs detectors. The field of view each channel is 10 ° with parallel optical axis. One SWIR channel lies in the center and the other seven VNIR channels are on the circle of 4.8cm diameters which guarantee each channel to view nearly the same section of ground. The optical head as a whole is temperature controlled utilizing a TE cooler for greater stability and lower noise. ATR is powered by a solar panel and transmit its data through a BDS (China's BeiDou Navigation Satellite System) terminator for long-term measurements without personnel in site. ATR deployed in Dunhuang test site with ground field about 30-cm-diameter area for multi-spectral reflectance measurements. Other instruments at the site include a Cimel sunphotometer and a diffuser-to-globe irradiance meter for atmosphere observations. The methodology for band-averaged reflectance retrieval and hyperspectral reflectance fitting process are described. Then the hyperspectral reflectance and atmospheric parameters are put into 6s code to predict TOA radiance which compare with MODIS radiance.

  14. Global spectral UV-radiometer with automatic shadow band.

    PubMed

    Rosales, Alejandro; Pedroni, Jorge V; Tocho, Jorge O

    2006-01-01

    A solar radiometer (GUV-511 C, Biospherical Instruments Inc., San Diego, CA) with four UV channels has been operating at Trelew (43.2 degrees S, 65.3 degrees W), Argentina, since the austral spring of 1997. The instrument provides global (direct + diffuse) irradiance on the horizontal plane year-round, with a 1 min period. On 1 January 1999, an automatic shadow band was added to calculate diffuse and direct radiation. The period of the measurements was increased to 2 min to keep the same signal to noise (S:N) ratio. Once the direct radiation values were available for the 305 nm and 320 nm spectral bands, the total ozone value was calculated and results were compared with data provided by the U.S. National Aeronautics and Space Administration for the Total Ozone Mapping Spectrometer (TOMS) on the Earth Probe satellite. Results show a root-mean-square (RMS) deviation within 4% compared with that of TOMS, so the quality of results is considered to be quite good. The importance of regular calibration to maintain long-term accuracy is stressed.

  15. Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Overview

    USGS Publications Warehouse

    ,

    2008-01-01

    The National Aeronautics and Space Administration (NASA) launched Terra, the Earth Observing System's (EOS) flagship satellite platform on December 18, 1999. The polar-orbiting Terra contains five remote sensing instruments, which enable the scientific study and analyses of global terrestrial processes and manifestations of global change. One of the five instruments is the multispectral Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), which is built in Japan by a consortium of government, industry, and research groups. It has three spectral bands in the visible near-infrared region (VNIR), six bands in the shortwave infrared region (SWIR), and five bands in the thermal infrared region (TIR), with 15-, 30-, and 90-meter ground resolutions, respectively. This combination of wide spectral coverage and high spatial resolution allows ASTER to discriminate among a wide variety of surface materials. The VNIR subsystem also has a backward-viewing telescope for high-resolution (15-meter) stereoscopic observation in the along-track direction, which facilitates the generation of digital elevation models (DEM).

  16. Modeling and Analysis of the Hurricane Imaging Radiometer (HIRAD)

    NASA Technical Reports Server (NTRS)

    Mauro, Stephanie

    2013-01-01

    The Hurricane Imaging Radiometer (HIRad) is a payload carried by an unmanned aerial vehicle (UAV) at altitudes up to 60,000 ft with the purpose of measuring ocean surface wind speeds and near ocean surface rain rates in hurricanes. The payload includes several components that must maintain steady temperatures throughout the flight. Minimizing the temperature drift of these components allows for accurate data collection and conclusions to be drawn concerning the behavior of hurricanes. HIRad has flown on several different UAVs over the past two years during the fall hurricane season. Based on the data from the 2011 flight, a Thermal Desktop model was created to simulate the payload and reproduce the temperatures. Using this model, recommendations were made to reduce the temperature drift through the use of heaters controlled by resistance temperature detector (RTD) sensors. The suggestions made were implemented for the 2012 hurricane season and further data was collected. The implementation of the heaters reduced the temperature drift for a portion of the flight, but after a period of time, the temperatures rose. With this new flight data, the thermal model was updated and correlated. Detailed analysis was conducted to determine a more effective way to reduce the temperature drift. The final recommendations made were to adjust the set temperatures of the heaters for 2013 flights and implement hardware changes for flights beyond 2013.

  17. Advanced very high resolution radiometer, Mod 2 engineering report

    NASA Technical Reports Server (NTRS)

    1980-01-01

    The Advanced High Resolution Radiometer, Mod 2 (AVHRR/2) is a modification of the original AVHRR (AVHRR/1) to expand the number of channels from four to five and provide additional sensing in the infrared region. A comparison of the spectral regions employed in the two instruments is given. Three of the channels are the same on both instruments. The difference in instruments is in the long wave IR region where a single channel was replaced by two channels. The modification from AVHRR/1 to AVHRR/2 was done with a minimum of changes. The areas of change are highlighted and the modifications by module are summarized. It is seen that the primary changes are in the relay optics and in the cooler. In this development program only two models are involved. The first model, the Optical Test Model was constructed and tested to prove the performance and structural integrity of the optical system and the modified cooler. The second model constructed is the Protoflight. Only the areas of the AVHRR/2 which were modified from the AVHRR/1 design are discussed.

  18. Infrared heterodyne radiometer for airborne atmospheric transmittance measurements

    NASA Technical Reports Server (NTRS)

    Wolczok, J. M.; Lange, R. A.; Dinardo, A. J.

    1980-01-01

    An infrared heterodyne radiometer (IHR) was used to measure atmospheric transmittance at selected hydrogen fluoride (2.7 micrometer) and deuterium fluoride (3.8 micrometer) laser transitions. The IHR was installed aboard a KC-135 aircraft for an airborne atmospheric measurements program that used the sun as a backlighting source for the transmission measurements. The critical components are: a wideband indium antimonide (1nSb) photomixer, a CW HF/DF laser L0, a radiometric processor, and a 1900 K blackbody reference source. The measured heterodyne receiver sensitivity (NEP) is 1.3 x 10 to the -19th power W/Hz, which yields a calculated IHR temperature resolution accuracy of delta I sub S/-3 sub S = 0.005 for a source temperature of 1000 K and a total transmittance of 0.5. Measured atmospheric transmittance at several wavelengths and aircraft altitudes from 9.14 km (30,000 ft) to 13.72 km (45,000 ft) were obtained during the measurements program and have been compared with values predicted by the AFGL Atmospheric Line Parameter Compilation.

  19. Thermal Modeling and Analysis of the Hurricane Imaging Radiometer (HIRad)

    NASA Technical Reports Server (NTRS)

    Mauro, Stephanie

    2013-01-01

    The Hurricane Imaging Radiometer (HIRad) is a payload carried by an unmanned aerial vehicle (UAV) at altitudes up to 60,000 ft with the purpose of measuring ocean surface wind speeds and near ocean surface rain rates in hurricanes. The payload includes several components that must maintain steady temperatures throughout the flight. Minimizing the temperature drift of these components allows for accurate data collection and conclusions to be drawn concerning the behavior of hurricanes. HIRad has flown on several different UAVs over the past two years during the fall hurricane season. Based on the data from the 2011 flight, a Thermal Desktop model was created to simulate the payload and reproduce the temperatures. Using this model, recommendations were made to reduce the temperature drift through the use of heaters controlled by resistance temperature detector (RTD) sensors. The suggestions made were implemented for the 2012 hurricane season and further data was collected. The implementation of the heaters reduced the temperature drift for a portion of the flight, but after a period of time, the temperatures rose. With this new flight data, the thermal model was updated and correlated. Detailed analysis was conducted to determine a more effective way to reduce the temperature drift. The final recommendations made were to adjust the set temperatures of the heaters for 2013 flights and implement hardware changes for flights beyond 2013.

  20. Regolith Formation Rates and Evolution from the Diviner Lunar Radiometer

    NASA Astrophysics Data System (ADS)

    Hayne, P. O.; Ghent, R. R.; Bandfield, J. L.; Vasavada, A. R.; Williams, J. P.; Siegler, M. A.; Lucey, P. G.; Greenhagen, B. T.; Elder, C. M.; Paige, D. A.

    2015-12-01

    Fragmentation and overturn of lunar surface materials produces a layer of regolith, which increases in thickness through time. Experiments on the lunar surface during the Apollo era, combined with remote sensing, found that the upper 10's of cm of regolith exhibit a rapid increase in density and thermal conductivity with depth. This is interpreted to be the signature of impact gardening, which operates most rapidly in the uppermost layers. Gravity data from the GRAIL mission showed that impacts have also extensively fractured the deeper crust. The breakdown and mixing of crustal materials is therefore a central process to lunar evolution and must be understood in order to interpret compositional information from remote sensing and sample analysis. Recently, thermal infrared data from the Lunar Reconnaissance Orbiter (LRO) Diviner radiometer were used to provide the first remote observational constraints on the rate of ejecta breakdown around craters < 1 Ga (Ghent et al., 2014). Here, we use nighttime regolith temperatures derived from Diviner data to constrain regolith thermal inertia, thickness, and spatial variability. Applied to models, these new data help improve understanding of regolith formation on a variety of geologic units. We will also discuss several anomalous features that merit further investigation. Reference: Ghent, R. R., Hayne, P. O., Bandfield, J. L., Campbell, B. A., Allen, C. C., Carter, L. M., & Paige, D. A. (2014). Constraints on the recent rate of lunar ejecta breakdown and implications for crater ages. Geology, 42(12), 1059-1062.