Inversion of parameters for semiarid regions by a neural network

NASA Technical Reports Server (NTRS)

Zurk, Lisa M.; Davis, Daniel; Njoku, Eni G.; Tsang, Leung; Hwang, Jenq-Neng

1992-01-01

Microwave brightness temperatures obtained from a passive radiative transfer model are inverted through use of a neural network. The model is applicable to semiarid regions and produces dual-polarized brightness temperatures for 6.6-, 10.7-, and 37-GHz frequencies. A range of temperatures is generated by varying three geophysical parameters over acceptable ranges: soil moisture, vegetation moisture, and soil temperature. A multilayered perceptron (MLP) neural network is trained with a subset of the generated temperatures, and the remaining temperatures are inverted using a backpropagation method. Several synthetic terrains are devised and inverted by the network under local constraints. All the inversions show good agreement with the original geophysical parameters, falling within 5 percent of the actual value of the parameter range.

The correlation of Skylab L-band brightness temperatures with antecedent precipitation

NASA Technical Reports Server (NTRS)

Mcfarland, M. J.

1975-01-01

The S194 L-band radiometer flown on the Skylab mission measured terrestrial radiation at the microwave wavelength of 21.4 cm. The terrain emissivity at this wavelength is strongly dependent on the soil moisture content, which can be inferred from antecedent precipitation. For the Skylab data acquisition pass from the Oklahoma panhandle to southeastern Texas on 11 June 1973, the S194 brightness temperatures are highly correlated with antecedent precipitation from the preceding eleven day period, but very little correlation was apparent for the preceding five day period. The correlation coefficient between the averaged antecedent precipitation index values and the corresponding S194 brightness temperatures between 230 K and 270 K, the region of apparent response to soil moisture in the data, was -0.97. The equation of the linear least squares line is given.

Sky brightness and twilight measurements at Jogyakarta city, Indonesia

NASA Astrophysics Data System (ADS)

Herdiwijaya, Dhani

2016-11-01

The sky brightness measurements were performed using a portable photometer. A pocket-sized and low-cost photometer has 20 degree area measurement, and spectral ranges between 320-720 nm with output directly in magnitudes per arc second square (mass) unit. The sky brightness with 3 seconds temporal resolutions was recorded at Jogyakarta city (110° 25’ E; 70° 52’ S; elevation 100 m) within 136 days in years from 2014 to 2016. The darkest night could reach 22.61 mpass only in several seconds, with mean value 18.8±0.7 mpass and temperature variation 23.1±1.2 C. The difference of mean sky brightness between before and after midnight was about -0.76 mpass or 2.0 times brighter. Moreover, the sky brightness and temperature fluctuations were more stable in after midnight than in before midnight. It is suggested that city light pollution affects those variations, and subsequently duration of twilight. By comparing twilight brightness for several places, we also suggest a 17° solar dip or about 66 minutes before sunrise for new time of Fajr prayer.

Ground temperature measurement by PRT-5 for maps experiment

NASA Technical Reports Server (NTRS)

Gupta, S. K.; Tiwari, S. N.

1978-01-01

A simple algorithm and computer program were developed for determining the actual surface temperature from the effective brightness temperature as measured remotely by a radiation thermometer called PRT-5. This procedure allows the computation of atmospheric correction to the effective brightness temperature without performing detailed radiative transfer calculations. Model radiative transfer calculations were performed to compute atmospheric corrections for several values of the surface and atmospheric parameters individually and in combination. Polynomial regressions were performed between the magnitudes or deviations of these parameters and the corresponding computed corrections to establish simple analytical relations between them. Analytical relations were also developed to represent combined correction for simultaneous variation of parameters in terms of their individual corrections.

Estimation of surface temperature in remote pollution measurement experiments

NASA Technical Reports Server (NTRS)

Gupta, S. K.; Tiwari, S. N.

1978-01-01

A simple algorithm has been developed for estimating the actual surface temperature by applying corrections to the effective brightness temperature measured by radiometers mounted on remote sensing platforms. Corrections to effective brightness temperature are computed using an accurate radiative transfer model for the 'basic atmosphere' and several modifications of this caused by deviations of the various atmospheric and surface parameters from their base model values. Model calculations are employed to establish simple analytical relations between the deviations of these parameters and the additional temperature corrections required to compensate for them. Effects of simultaneous variation of two parameters are also examined. Use of these analytical relations instead of detailed radiative transfer calculations for routine data analysis results in a severalfold reduction in computation costs.

Evaluating Uncertainties in Coronal Electron Temperature and Radial Speed Measurements Using a Simulation of the Bastille Day Eruption

NASA Astrophysics Data System (ADS)

Reginald, Nelson; St. Cyr, Orville; Davila, Joseph; Rastaetter, Lutz; Török, Tibor

2018-05-01

Obtaining reliable measurements of plasma parameters in the Sun's corona remains an important challenge for solar physics. We previously presented a method for producing maps of electron temperature and speed of the solar corona using K-corona brightness measurements made through four color filters in visible light, which were tested for their accuracies using models of a structured, yet steady corona. In this article we test the same technique using a coronal model of the Bastille Day (14 July 2000) coronal mass ejection, which also contains quiet areas and streamers. We use the coronal electron density, temperature, and flow speed contained in the model to determine two K-coronal brightness ratios at (410.3, 390.0 nm) and (423.3, 398.7 nm) along more than 4000 lines of sight. Now assuming that for real observations, the only information we have for each line of sight are these two K-coronal brightness ratios, we use a spherically symmetric model of the corona that contains no structures to interpret these two ratios for electron temperature and speed. We then compare the interpreted (or measured) values for each line of sight with the true values from the model at the plane of the sky for that same line of sight to determine the magnitude of the errors. We show that the measured values closely match the true values in quiet areas. However, in locations of coronal structures, the measured values are predictably underestimated or overestimated compared to the true values, but can nevertheless be used to determine the positions of the structures with respect to the plane of the sky, in front or behind. Based on our results, we propose that future white-light coronagraphs be equipped to image the corona using four color filters in order to routinely create coronal maps of electron density, temperature, and flow speed.

[The Performance Analysis for Lighting Sources in Highway Tunnel Based on Visual Function].

PubMed

Yang, Yong; Han, Wen-yuan; Yan, Ming; Jiang, Hai-feng; Zhu, Li-wei

2015-10-01

Under the condition of mesopic vision, the spectral luminous efficiency function is shown as a series of curves. Its peak wavelength and intensity are affected by light spectrum, background brightness and other aspects. The impact of light source to lighting visibility could not be carried out via a single optical parametric characterization. The reaction time of visual cognition is regard as evaluating indexes in this experiment. Under the condition of different speed and luminous environment, testing visual cognition based on vision function method. The light sources include high pressure sodium, electrodeless fluorescent lamp and white LED with three kinds of color temperature (the range of color temperature is from 1 958 to 5 537 K). The background brightness value is used for basic section of highway tunnel illumination and general outdoor illumination, its range is between 1 and 5 cd x m(-)2. All values are in the scope of mesopic vision. Test results show that: under the same condition of speed and luminance, the reaction time of visual cognition that corresponding to high color temperature of light source is shorter than it corresponding to low color temperature; the reaction time corresponding to visual target in high speed is shorter than it in low speed. At the end moment, however, the visual angle of target in observer's visual field that corresponding to low speed was larger than it corresponding to high speed. Based on MOVE model, calculating the equivalent luminance of human mesopic vision, which is on condition of different emission spectrum and background brightness that formed by test lighting sources. Compared with photopic vision result, the standard deviation (CV) of time-reaction curve corresponding to equivalent brightness of mesopic vision is smaller. Under the condition of mesopic vision, the discrepancy between equivalent brightness of different lighting source and photopic vision, that is one of the main reasons for causing the discrepancy of visual recognition. The emission spectrum peak of GaN chip is approximate to the wave length peak of efficiency function in photopic vision. The lighting visual effect of write LED in high color temperature is better than it in low color temperature and electrodeless fluorescent lamp. The lighting visual effect of high pressure sodium is weak. Because of its peak value is around the Na+ characteristic spectra.

Extreme Thunderstorms as Seen by Satellite

NASA Technical Reports Server (NTRS)

Cecil, Daniel J.

2014-01-01

Extreme events by their nature fall outside the bounds of routine experience. With imperfect or ambiguous measuring systems, it is appropriate to question whether an unusual measurement represents an extreme event or is the result of instrument errors or other sources of noise. About three weeks after the Tropical Rainfall Measuring Mission (TRMM) satellite began collecting data in Dec 1997, a thunderstorm was observed over northern Argentina with 85 GHz brightness temperatures below 50 K and 37 GHz brightness temperatures below 70 K (Zipser et al. 2006). These values are well below what had previously been observed from satellite sensors with lower resolution. The 37 GHz brightness temperatures are also well below those measured by TRMM for any other storm in the subsequent 16 years. Without corroborating evidence, it would be natural to suspect a problem with the instrument, or perhaps an irregularity with the platform during the first weeks of the satellite mission. But the TRMM satellite also carries a radar and a lightning sensor, both confirming the presence of an intense thunderstorm. The radar recorded 40+ dBZ (decibels relative to Z) reflectivity up to about 19 km altitude. More than 200 lightning flashes per minute were recorded. That same storm's 19 GHz brightness temperatures below 150 K would normally be interpreted as the result of a low-emissivity water surface (e.g., a lake, or flood waters) if not for the simultaneous measurements of such intense convection. This paper will examine records from TRMM and related satellite sensors including SSMI and AMSR-E to find the strongest signatures resulting from thunderstorms, and distinguishing those from sources of noise. The lowest brightness temperatures resulting from thunderstorms as seen by TRMM have been in Argentina in November and December. For SSMI sensors carried on five DMSP satellites examined so far, the lowest thunderstorm-related brightness temperatures have been from Argentina in November - December and from Minnesota in June-July. The Minnesota cases were associated with spotter reports of large hail, significant severe wind, and tornadoes. Those locations have the record holders for each satellite. This paper will show examples of cases with the lowest brightness temperatures, and map the locations of these and other storms with brightness temperatures nearly as low. Higher resolution data from the field program MC3E and possibly from IPHEX will be considered for context.

Titan's Surface Brightness Temperatures and H2 Mole Fraction from Cassini CIRS

NASA Technical Reports Server (NTRS)

Jennings, Donald E.; Flasar, F. M.; Kunde, V. G.; Samuelson, R. E.; Pearl, J. C.; Nixon, C. A.; Carlson, R. C.; Mamoutkine, A. A.; Brasunas, J. C.; Guandique, E.;

Geological applications of Nimbus radiation data in the Middle East

NASA Technical Reports Server (NTRS)

Allison, L. J.

1977-01-01

Large plateaus of Eocene limestone and exposed limestone escarpments, in Egypt and Saudi Arabia, respectively, were indicated by cool brightness temperatures recorded by the Nimbus-5 electrically scanning microwave radiometer (ESMR), over a 2-year period. Nubian sandstone, desert eolian sand, and igneous-metamorphic rock of the Pliocene, Miocene, Oligocene, and Cretaceous periods were differentiated from these limestone areas by warm T sub B values. These brightness temperature differences are a result of seasonal in-situ ground temperatures and differential emissivity of limestone and sand, sandstone and granite, whose dielectric constants are 6 to 8.9 and 2.9 and 4.2 to 5.3, respectively, at 19.35 GHz.

21-cm radiation: a new probe of variation in the fine-structure constant.

PubMed

Khatri, Rishi; Wandelt, Benjamin D

2007-03-16

We investigate the effect of variation in the value of the fine-structure constant (alpha) at high redshifts (recombination > z > 30) on the absorption of the cosmic microwave background (CMB) at 21 cm hyperfine transition of the neutral atomic hydrogen. We find that the 21 cm signal is very sensitive to the variations in alpha and it is so far the only probe of the fine-structure constant in this redshift range. A change in the value of alpha by 1% changes the mean brightness temperature decrement of the CMB due to 21 cm absorption by >5% over the redshift range z < 50. There is an effect of similar magnitude on the amplitude of the fluctuations in the brightness temperature. The redshift of maximum absorption also changes by approximately 5%.

The emissivities of liquid metals at their fusion temperatures

NASA Technical Reports Server (NTRS)

Bonnell, D. W.; Treverton, J. A.; Valerga, A. J.; Margrave, J. L.

1972-01-01

A survey of the literature through 1969 shows an almost total lack of experimental emissivity data for metals in the liquid state. The emissivities for several transition metals and various other metals and compounds in the liquid state at their fusion temperatures have been determined. The technique used involves electromagnetic levitation-induction heating of the materials in an inert atmosphere. The brightness temperature of the liquid phase of the material is measured as the material is heated through fusion. Given a reliable value of the fusion temperature, which is available for most pure substances, one may readily calculate an emissivity for the liquid phase at the fusion temperatures. Even in cases where melting points are poorly known, the brightness temperatures are unique parameters, independent of the temperature scale and measured for a chemically defined system at a fixed point. Better emissivities may be recalculated as better melting point data become available.

Calibration of Hurricane Imaging Radiometer C-Band Receivers

NASA Technical Reports Server (NTRS)

Biswas, Sayak K.; Cecil, Daniel J.; James, Mark W.

2017-01-01

The laboratory calibration of airborne Hurricane Imaging Radiometer's C-Band multi-frequency receivers is described here. The method used to obtain the values of receiver frontend loss, internal cold load brightness temperature and injected noise diode temperature is presented along with the expected RMS uncertainty in the final calibration.

Retrieval of surface temperature by remote sensing. [of earth surface using brightness temperature of air pollutants

NASA Technical Reports Server (NTRS)

Gupta, S. K.; Tiwari, S. N.

1976-01-01

A simple procedure and computer program were developed for retrieving the surface temperature from the measurement of upwelling infrared radiance in a single spectral region in the atmosphere. The program evaluates the total upwelling radiance at any altitude in the region of the CO fundamental band (2070-2220 1/cm) for several values of surface temperature. Actual surface temperature is inferred by interpolation of the measured upwelling radiance between the computed values of radiance for the same altitude. Sensitivity calculations were made to determine the effect of uncertainty in various surface, atmospheric and experimental parameters on the inferred value of surface temperature. It is found that the uncertainties in water vapor concentration and surface emittance are the most important factors affecting the accuracy of the inferred value of surface temperature.

Estimation of soil hydraulic properties with microwave techniques

NASA Technical Reports Server (NTRS)

Oneill, P. E.; Gurney, R. J.; Camillo, P. J.

1985-01-01

Useful quantitative information about soil properties may be obtained by calibrating energy and moisture balance models with remotely sensed data. A soil physics model solves heat and moisture flux equations in the soil profile and is driven by the surface energy balance. Model generated surface temperature and soil moisture and temperature profiles are then used in a microwave emission model to predict the soil brightness temperature. The model hydraulic parameters are varied until the predicted temperatures agree with the remotely sensed values. This method is used to estimate values for saturated hydraulic conductivity, saturated matrix potential, and a soil texture parameter. The conductivity agreed well with a value measured with an infiltration ring and the other parameters agreed with values in the literature.

Thermal inertia mapping of Mars from 60°S to 60°N

USGS Publications Warehouse

Palluconi, Frank Don; Kieffer, Hugh H.

1981-01-01

Twenty-micrometer brightness temperatures are used to derive the thermal inertia for 81% of the Martian surface between latitudes ±60°. These data were acquired by the two Viking Infrared Thermal Mappers in 1977 and 1978 following the two global dust storms of 1977. The spatial resolution used is 2° in latitude by 2° in longitude and the total range in derived inertia is . The distribution of thermal inertia is strongly bimodal with all values of thermal inertia less than  being associated with three disjoint bright regions mostly in the northern hemisphere. Sufficient dust is raised in global storms to provide fine material adequate to produce these low-inertia areas but the specific deposition mechanism has not been defined. At the low resolution used, no complete exposures of clean rock were found. There is some tendency for darker material to be associated with higher thermal inertia, although the trend is far from one to one. The distribution of high- and low-inertia areas is sufficiently nonrandom to produce a variation in whole-disk brightness temperature with central meridian longitude. This variation and the change in surface kinetic temperature associated with dust storms are factors in establishing the whole-disk brightness temperature at radio and infrared wavelengths and will be important for those who use Mars as a calibration source.

Photic effects on sustained performance

NASA Technical Reports Server (NTRS)

French, J.; Whitmore, J.; Hannon, P. J.; Brainard, G.; Schiflett, S.

1992-01-01

Research is described which evaluates manipulating environmental light intensity as a means to attenuate fatigue. A counter balanced, within-subjects design was used to compare nine male subjects exposed to dim (100 lux) and bright (3000 lux) light conditions. Oral temperature values were greater for the bright light group over the dim light condition. Melatonin levels were suppressed by bright light treatment. Also, the frequency of eye blink rate was less for subjects during bright over dim light exposure. Light exposure was without effect on subjective fatigue. However, irrespective of light condition, significant effects on confusion, fatigue, and vigor mood dimensions were found as a result of 30 hour sleep deprivation. The findings suggest that bright lights may be used to help sustain nocturnal activity otherwise susceptible to fatigue. Such findings may have implications for the lighting arrangements on space flights during the subjective night for astronauts.

Correlation studies of passive and active microwave data in the marginal ice zone

NASA Technical Reports Server (NTRS)

Comiso, J. C.

1991-01-01

The microwave radiative and backscatter characteristics of sea ice in an Arctic marginal ice zone have been studied using near-simultaneous passive and active synthetic aperture radar microwave data. Intermediate-resolution multichannel passive microwave data were registered and analyzed. Passive and active microwave data generally complement each other as the two sensors are especially sensitive to different physical properties of the sea ice. In the inner pack, undeformed first-year ice is observed to have low backscatter values but high brightness temperatures while multiyear ice has generally high backscatter values and low brightness temperatures. However, in the marginal ice zone, the signature and backscatter for multiyear ice are considerably different and closer to those of first-year ice. Some floes identified by photography as snow-covered thick ice have backscatter similar to that of new ice or open water while brash ice has backscatter similar to or higher than that of ridged ice.

Calculations of microwave brightness temperature of rough soil surfaces: Bare field

NASA Technical Reports Server (NTRS)

Mo, T.; Schmugge, T. J.; Wang, J. R.

1985-01-01

A model for simulating the brightness temperatures of soils with rough surfaces is developed. The surface emissivity of the soil media is obtained by the integration of the bistatic scattering coefficients for rough surfaces. The roughness of a soil surface is characterized by two parameters, the surface height standard deviation sigma and its horizontal correlation length l. The model calculations are compared to the measured angular variations of the polarized brightness temperatures at both 1.4 GHz and 5 GHz frequences. A nonlinear least-squares fitting method is used to obtain the values of delta and l that best characterize the surface roughness. The effect of shadowing is incorporated by introducing a function S(theta), which represents the probability that a point on a rough surface is not shadowed by other parts of the surface. The model results for the horizontal polarization are in excellent agreement with the data. However, for the vertical polarization, some discrepancies exist between the calculations and data, particularly at the 1.4 GHz frequency. Possible causes of the discrepancy are discussed.

S193 radiometer brightness temperature precision/accuracy for SL2 and SL3

NASA Technical Reports Server (NTRS)

Pounds, D. J.; Krishen, K.

1975-01-01

The precision and accuracy with which the S193 radiometer measured the brightness temperature of ground scenes is investigated. Estimates were derived from data collected during Skylab missions. Homogeneous ground sites were selected and S193 radiometer brightness temperature data analyzed. The precision was expressed as the standard deviation of the radiometer acquired brightness temperature. Precision was determined to be 2.40 K or better depending on mode and target temperature.

Arctic sea ice signatures: L-band brightness temperature sensitivity comparison using two radiation transfer models

NASA Astrophysics Data System (ADS)

Richter, Friedrich; Drusch, Matthias; Kaleschke, Lars; Maaß, Nina; Tian-Kunze, Xiangshan; Mecklenburg, Susanne

2018-03-01

Sea ice is a crucial component for short-, medium- and long-term numerical weather predictions. Most importantly, changes of sea ice coverage and areas covered by thin sea ice have a large impact on heat fluxes between the ocean and the atmosphere. L-band brightness temperatures from ESA's Earth Explorer SMOS (Soil Moisture and Ocean Salinity) have been proven to be a valuable tool to derive thin sea ice thickness. These retrieved estimates were already successfully assimilated in forecasting models to constrain the ice analysis, leading to more accurate initial conditions and subsequently more accurate forecasts. However, the brightness temperature measurements can potentially be assimilated directly in forecasting systems, reducing the data latency and providing a more consistent first guess. As a first step towards such a data assimilation system we studied the forward operator that translates geophysical parameters provided by a model into brightness temperatures. We use two different radiative transfer models to generate top of atmosphere brightness temperatures based on ORAP5 model output for the 2012/2013 winter season. The simulations are then compared against actual SMOS measurements. The results indicate that both models are able to capture the general variability of measured brightness temperatures over sea ice. The simulated brightness temperatures are dominated by sea ice coverage and thickness changes are most pronounced in the marginal ice zone where new sea ice is formed. There we observe the largest differences of more than 20 K over sea ice between simulated and observed brightness temperatures. We conclude that the assimilation of SMOS brightness temperatures yields high potential for forecasting models to correct for uncertainties in thin sea ice areas and suggest that information on sea ice fractional coverage from higher-frequency brightness temperatures should be used simultaneously.

Analysis of Saturn's Thermal Emission at 2.2-cm Wavelength: Spatial Distribution of Ammonia Vapor

NASA Technical Reports Server (NTRS)

Laraia, A. L.; Ingersoll, A. P.; Janssen, Michael A.; Gulkis, Samuel; Oyafuso, Fabiano A.; Allison, Michael D.

2013-01-01

This work focuses on determining the latitudinal structure of ammonia vapor in Saturn's cloud layer near 1.5 bars using the brightness temperature maps derived from the Cassini RADAR (Elachi et al., 2004) instrument, which works in a passive mode to measure thermal emission from Saturn at 2.2-cm wavelength. We perform an analysis of five brightness temperature maps that span epochs from 2005 to 2011, which are presented in a companion paper by Janssen et al. (2013a, this issue). The brightness temperature maps are representative of the spatial distribution of ammonia vapor, since ammonia gas is the only effective opacity source in Saturn's atmosphere at 2.2-cm wavelength. Relatively high brightness temperatures indicate relatively low ammonia relative humidity (RH), and vice versa. We compare the observed brightness temperatures to brightness temperatures computed using the Juno atmospheric microwave radiative transfer (JAMRT) program which includes both the means to calculate a tropospheric atmosphere model for Saturn and the means to carry out radiative transfer calculations at microwave frequencies. The reference atmosphere to which we compare has a 3x solar deep mixing ratio of ammonia (we use 1.352x10(exp -4) for the solar mixing ratio of ammonia vapor relative to H2; see Atreya, 2010) and is fully saturated above its cloud base. The maps are comprised of residual brightness temperatures-observed brightness temperature minus the model brightness temperature of the saturated atmosphere.

[Monitoring of brightness temperature fluctuation of water in SHF range].

PubMed

Ivanov, Yu D; Kozlov, A F; Galiullin, R A; Tatu, V Yu; Vesnin, S G; Ziborov, V S; Ivanova, N D; Pleshakova, T O

2017-01-01

The purpose of the research consisted in detection of fluctuation of brightness temperature (TSHF) of water in the area of the temperature Т = 42°С (that is critical for human) during its evaporation by SHF radiometry. Methods: Monitoring of the changes in brightness temperature of water in superhigh frequency (SHF) range (3.8-4.2 GHz) near the phase transition temperature of water Т = 42°С during its evaporation in the cone dielectric cell. The brightness temperature measurements were carried out using radiometer. Results: Fluctuation with maximum of brightness temperature was detected in 3.8-4.2 GHz frequency range near at the temperature of water Т = 42°С. It was characteristic for these TSHF fluctuations that brightness temperature rise time in this range of frequencies in ~4°С temperature range with 0.05-15°С/min gradient and a sharp decrease during 10 s connected with measuring vapor conditions. Then nonintensive fluctuation series was observed. At that, the environment temperature remained constant. Conclusion: The significant increasing in brightness temperature of water during its evaporation in SHF range near the temperature of Т ~42°С were detected. It was shown that for water, ТSHF pull with the amplitude DТSHF ~4°C are observed. At the same time, thermodynamic temperature virtually does not change. The observed effects can be used in the development of the systems for diadnostics of pathologies in human and analytical system.

Post-shock temperatures in minerals. [infrared detection of brightness temperature

NASA Technical Reports Server (NTRS)

Raikes, S. A.; Ahrens, T. J.

1978-01-01

Post-shock temperatures were measured in a wide variety of materials, including those of geophysical interest such as silicates by using an infrared detector to determine the brightness temperature of samples shocked to pressures in the range 5 to approximately 30 GPa. Measurements were made in the 4.5 to 5.75 micron and in the 7 to 14 micron wavelength ranges. Reproducible results, withe the temperatures in the two wavelength bands generally in excellent agreement, were obtained for aluminum-2024 (10.5 to 33 GPa; 125 to 260 C), stainless steel-304 (11.5 to 50 GPa; 80 to 350 C), crystalline quartz (5.0 to 21.5 GPa; 80 to 250 C) forsterite (7.5 to 28.0 GPa; approximately 30 to 160 C) and Bamble bronzite (6.0 to 26.0 GPa; approximately 30 to 225 C). Results are generally much higher at low pressures than the values calculated assuming a hydrodynamic rheology and isentropic release parallel to the Hugoniot but tend towards them at higher pressures.

The prediction of tropopause height from clusters of brightness temperatures and its application in the stratified regression temperature retrievals using microwave and infrared satellite measurements

NASA Technical Reports Server (NTRS)

Munteanu, M. J.; Piraino, P.; Jakubowicz, O.

1984-01-01

A total of 1575 radiosondes and the corresponding simulated brightness temperatures were used in an effort to derive a temperature retrieval based on the clusters of brightness temperatures. The 8 simulated channels, namely, 3 MSU and 5 IR of the TIROS-N satellite are used by the GLAS temperature retrieval method. The 3 MSU and 5 IR brightness temperatures were clustered into 17 cluster groups and a regression for the prediction of the tropopause height in mb was generated. The overall r.m.s. for the tropopause prediction is excellent, namely, around 16 mb for the summer and 23 mb for the winter. The correct cluster of brightness temperatures can be identified 98% of the time by the method of discriminatory classification if it is approximately a normal distribution or, in general, by the method of the nearest neighbor.

Landcover Based Optimal Deconvolution of PALS L-band Microwave Brightness Temperature

NASA Technical Reports Server (NTRS)

Limaye, Ashutosh S.; Crosson, William L.; Laymon, Charles A.; Njoku, Eni G.

2004-01-01

An optimal de-convolution (ODC) technique has been developed to estimate microwave brightness temperatures of agricultural fields using microwave radiometer observations. The technique is applied to airborne measurements taken by the Passive and Active L and S band (PALS) sensor in Iowa during Soil Moisture Experiments in 2002 (SMEX02). Agricultural fields in the study area were predominantly soybeans and corn. The brightness temperatures of corn and soybeans were observed to be significantly different because of large differences in vegetation biomass. PALS observations have significant over-sampling; observations were made about 100 m apart and the sensor footprint extends to about 400 m. Conventionally, observations of this type are averaged to produce smooth spatial data fields of brightness temperatures. However, the conventional approach is in contrast to reality in which the brightness temperatures are in fact strongly dependent on landcover, which is characterized by sharp boundaries. In this study, we mathematically de-convolve the observations into brightness temperature at the field scale (500-800m) using the sensor antenna response function. The result is more accurate spatial representation of field-scale brightness temperatures, which may in turn lead to more accurate soil moisture retrieval.

Red-emission phosphor's brightness deterioration by x-ray and brightness recovery phenomenon by heating.

PubMed

Nakamura, Masaaki; Chida, Koichi; Inaba, Yohei; Kobayashi, Ryota; Zuguchi, Masayuki

2017-06-26

There are no feasible real-time and direct skin dosimeters for interventional radiology. One would be available if there were x-ray phosphors that had no brightness change caused by x-ray irradiation, but the emission of the Y 2 O 3 :Eu, (Y, Gd, Eu)BO 3 , and YVO 4 :Eu phosphors investigated in our previous study was reduced by x-ray irradiation. We found that the brightness of those phosphors recovered, and the purpose of this study is to investigate their recovery phenomena. It is expected that more kinds of phosphors could be used in x-ray dosimeters if the brightness changes caused by x-rays are elucidated and prevented. Three kinds of phosphors-Y 2 O 3 :Eu, (Y, Gd, Eu)BO 3 , and YVO 4 :Eu-were irradiated by x-rays (2 Gy) to reduce their brightness. After the irradiation, brightness changes occurring at room temperature and at 80 °C were investigated. The irradiation reduced the brightness of all the phosphors by 5%-10%, but the brightness of each recovered immediately both at room temperature and at 80 °C. The recovery at 80 °C was faster than that at room temperature, and at both temperatures the recovered brightness remained at 95%-98% of the brightness before the x-ray irradiation. The brightness recovery phenomena of Y 2 O 3 :Eu, (Y, Gd, Eu)BO 3 , and YVO 4 :Eu phosphors occurring after brightness deterioration due to x-ray irradiation were found to be more significant at 80 °C than at room temperature. More kinds of phosphors could be used in x-ray scintillation dosimeters if the reasons for the brightness changes caused by x-rays were elucidated.

IRTM brightness temperature maps of the Martian south polar region during the polar night: The cold spots don't move

NASA Technical Reports Server (NTRS)

Paige, D. A.; Crisp, D.; Santee, M. L.; Richardson, M. I.

1993-01-01

A series of infrared thermal mapper (IRTM) south polar brightness temperature maps obtained by Viking Orbiter 2 during a 35-day period during the southern fall season in 1978 was examined. The maps show a number of phenomena that have been identified in previous studies, including day to day brightness temperature variations in individual low temperature regions and the tendency for IRTM 11-micron channel brightness temperatures to also decrease in regions where low 20-micron channel brightness temperatures are observed. The maps also show new phenomena, the most striking of which is a clear tendency for the low brightness temperature regions to occur at fixed geographic regions. During this season, the coldest low brightness temperatures appear to be concentrated in distinct regions, with spatial scales ranging from 50 to 300 km. There are approximately a dozen of these concentrations, with the largest centered near the location of the south residual polar cap. Other concentrations are located at Cavi Angusti and close to the craters Main, South, Lau, and Dana. Broader, less intense regions appear to be well correlated with the boundaries of the south polar layered deposits and the Mountains of Mitchell. No evidence for horizontal motion of any of these regions has been detected.

Microwave Brightness Temperatures of Tilted Convective Systems

NASA Technical Reports Server (NTRS)

Hong, Ye; Haferman, Jeffrey L.; Olson, William S.; Kummerow, Christian D.

1998-01-01

Aircraft and ground-based radar data from the Tropical Ocean and Global Atmosphere Coupled-Ocean Atmosphere Response Experiment (TOGA COARE) show that convective systems are not always vertical. Instead, many are tilted from vertical. Satellite passive microwave radiometers observe the atmosphere at a viewing angle. For example, the Special Sensor Microwave/Imager (SSM/I) on Defense Meteorological Satellite Program (DMSP) satellites and the Tropical Rainfall Measurement Mission (TRMM) Microwave Imager (TMI) on the TRMM satellite have an incident angle of about 50deg. Thus, the brightness temperature measured from one direction of tilt may be different than that viewed from the opposite direction due to the different optical depth. This paper presents the investigation of passive microwave brightness temperatures of tilted convective systems. To account for the effect of tilt, a 3-D backward Monte Carlo radiative transfer model has been applied to a simple tilted cloud model and a dynamically evolving cloud model to derive the brightness temperature. The radiative transfer results indicate that brightness temperature varies when the viewing angle changes because of the different optical depth. The tilt increases the displacements between high 19 GHz brightness temperature (Tb(sub 19)) due to liquid emission from lower level of cloud and the low 85 GHz brightness temperature (Tb(sub 85)) due to ice scattering from upper level of cloud. As the resolution degrades, the difference of brightness temperature due to the change of viewing angle decreases dramatically. The dislocation between Tb(sub 19) and Tb(sub 85), however, remains prominent.

Electrically-Active Convection and Tropical Cyclogenesis in the Atlantic and East Pacific

NASA Technical Reports Server (NTRS)

Leppert, Kenneth D., II; Petersen, Walter A.

2011-01-01

It has been hypothesized that deep, intense convective-scale hot towers may aid the process of tropical cyclogenesis and intensification through dynamic and thermodynamic feedbacks on the larger meso-to-synoptic scale circulation. In this study, we make use of NCEP Reanalysis data and Tropical Rainfall Measurement Mission (TRMM) lightning imaging sensor (LIS), precipitation radar (PR), and microwave imager (TMI) data to investigate the role that widespread and/or intense lightning-producing convection (i.e., electrically-hot towers) present in African easterly waves (AEWs) may play in tropical cyclogenesis over the Atlantic, Caribbean, and East Pacific regions. NCEP Reanalysis 700 hPa meridional winds for the months of June to November for the years 2001-2009 were analyzed for the domain of 5 deg. N-20 deg. N and 130 deg. W-20 deg. E in order to partition individual AEWs into northerly, southerly, trough, and ridge phases. Subsequently, information from National Hurricane Center (NHC) storm reports was used to divide the waves into developing and non-developing waves. In addition, information from the NHC reports was used to further divide the developing waves into those waves that spawned storms that only developed to tropical storm strength and those that spawned storms that reached hurricane strength. The developing waves were also divided by the region in which they developed. To assess the evolution of convection associated with the AEWs as they propagated across our analysis domain, the full 130 deg. W-20 deg. E domain was divided into five longitude bands, and waves were analyzed for each band. To help determine the gross nature of the smaller convective scale, composites were created of all developing and non-developing waves as a function of AEW wave phase over the full analysis domain and each longitude band by compositing TRMM PR, TMI, LIS, and IR brightness temperature data extracted from the NASA global-merged infrared brightness temperature dataset. Finally, similar composites were created using various NCEP variables to assess the nature of the larger scale environment and circulation. Results suggest a clear distinction between developing and non-developing waves as developing waves near their region of development in terms of the intensity of convection (indicated by lightning flash rate), coverage of cold cloudiness (indicated by the percentage of a 2.5 deg. by 2.5 deg. box covered by IR brightness temperatures less than 240 deg. K and 210 deg. K), and large-scale variables, such as midlevel moisture and upper-level upward motion. For example, waves that developed in the East Pacific longitude band (i.e., 130 deg. W 95 deg. W) were observed in that band to have a flash rate of 56.4 flashes per day, a coverage by brightness temperatures less than 240 deg. K equal to 15.9%, a coverage by brightness temperatures less than 210 deg. K equal to 2.2%, a 700-hPa specific humidity anomaly of 0.4 g per kilogram, and a 300-hPa omega value of -0.04 Pascals per second in the trough phase compared to the non-developing wave trough values of 22.1 flashes per day, a coverage by brightness temperatures less than 240 deg. K equal to 8.1%, a coverage by brightness temperatures less than 210 deg. K equal to 0.9%, a 700-hPa specific humidity anomaly of -0.3 g per kilogram, and a 300-hPa omega value of -0.01 Pascals per second. Further analysis is being conducted to determine if the aforementioned behavior is observed for developing waves farther from their region of development and to determine any significant differences between waves that spawned storms that reached tropical storm strength and those that spawned storms that reached hurricane strength.

Synthesizing SMOS Zero-Baselines with Aquarius Brightness Temperature Simulator

NASA Technical Reports Server (NTRS)

Colliander, A.; Dinnat, E.; Le Vine, D.; Kainulainen, J.

2012-01-01

SMOS [1] and Aquarius [2] are ESA and NASA missions, respectively, to make L-band measurements from the Low Earth Orbit. SMOS makes passive measurements whereas Aquarius measures both passive and active. SMOS was launched in November 2009 and Aquarius in June 2011.The scientific objectives of the missions are overlapping: both missions aim at mapping the global Sea Surface Salinity (SSS). Additionally, SMOS mission produces soil moisture product (however, Aquarius data will eventually be used for retrieving soil moisture too). The consistency of the brightness temperature observations made by the two instruments is essential for long-term studies of SSS and soil moisture. For resolving the consistency, the calibration of the instruments is the key. The basis of the SMOS brightness temperature level is the measurements performed with the so-called zero-baselines [3]; SMOS employs an interferometric measurement technique which forms a brightness temperature image from several baselines constructed by combination of multiple receivers in an array; zero-length baseline defines the overall brightness temperature level. The basis of the Aquarius brightness temperature level is resolved from the brightness temperature simulator combined with ancillary data such as antenna patterns and environmental models [4]. Consistency between the SMOS zero-baseline measurements and the simulator output would provide a robust basis for establishing the overall comparability of the missions.

A Methodology for Surface Soil Moisture and Vegetation Optical Depth Retrieval Using the Microwave Polarization Difference Index

NASA Technical Reports Server (NTRS)

Owe, Manfred; deJeu, Richard; Walker, Jeffrey; Zukor, Dorothy J. (Technical Monitor)

2001-01-01

A methodology for retrieving surface soil moisture and vegetation optical depth from satellite microwave radiometer data is presented. The procedure is tested with historical 6.6 GHz brightness temperature observations from the Scanning Multichannel Microwave Radiometer over several test sites in Illinois. Results using only nighttime data are presented at this time, due to the greater stability of nighttime surface temperature estimation. The methodology uses a radiative transfer model to solve for surface soil moisture and vegetation optical depth simultaneously using a non-linear iterative optimization procedure. It assumes known constant values for the scattering albedo and roughness. Surface temperature is derived by a procedure using high frequency vertically polarized brightness temperatures. The methodology does not require any field observations of soil moisture or canopy biophysical properties for calibration purposes and is totally independent of wavelength. Results compare well with field observations of soil moisture and satellite-derived vegetation index data from optical sensors.

[Retrieval of the Optical Thickness and Cloud Top Height of Cirrus Clouds Based on AIRS IR High Spectral Resolution Data].

PubMed

Cao, Ya-nan; Wei, He-li; Dai, Cong-ming; Zhang, Xue-hai

2015-05-01

A study was carried out to retrieve optical thickness and cloud top height of cirrus clouds from the Atmospheric Infrared Sounder (AIRS) high spectral resolution data in 1070~1135 cm-1 IR band using a Combined Atmospheric Radiative Transfer model (CART) by brightness temperature difference between model simulation and AIRS observation. The research is based on AIRS LIB high spectral infrared observation data combined with Moderate Resolution Imaging Spectroradiometer (MODIS) cloud product data. Brightness temperature spectra based, on the retrieved cirrus optical thickness and cloud top height were simulated and compared with brightness temperature spectra of AIRS observation in the 650~1150 cm-1 band. The cirrus optical thickness and cloud top height retrieved were compared with brightness temperature of AIRS for channel 760 (900.56 cm-1, 11. 1 µm) and cirrus reflectance of MODIS cloud product. And cloud top height retrieved was compared with cloud top height from MODIS. Results show that the brightness temperature spectra simulated were basically consistent with AIRS observation under the condition of retrieval in the 650~1150 cm-1 band. It means that CART can be used to simulate AIRS brightness temperature spectra. The retrieved cirrus parameters are consistent with brightness temperature of AIRS for channel 11. 1 µm with low brightness temperature corresponding to large cirrus optical thickness and high cloud top height. And the retrieved cirrus parameters are consistent with cirrus reflectance of MODIS cloud product with high cirrus reflectance corresponding to large cirrus optical thickness and high cloud top height. Correlation coefficient of brightness temperature between retrieved cloud top height and MODIS cloud top height was relatively high. They are mostly located in the range of 8. 5~11.5 km, and their probability distribution trend is approximately identical. CART model is feasible to retrieve cirrus properties, and the retrieval is reliable.

Thermal measurements of dark and bright surface features on Vesta as derived from Dawn/VIR

USGS Publications Warehouse

Tosi, Federico; Capria, Maria Teresa; De Sanctis, M.C.; Combe, J.-Ph.; Zambon, F.; Nathues, A.; Schröder, S.E.; Li, J.-Y.; Palomba, E.; Longobardo, A.; Blewett, D.T.; Denevi, B.W.; Palmer, E.; Capaccioni, F.; Ammannito, E.; Titus, Timothy N.; Mittlefehldt, D.W.; Sunshine, J.M.; Russell, C.T.; Raymond, C.A.; Dawn/VIR Team,

2014-01-01

Remote sensing data acquired during Dawn’s orbital mission at Vesta showed several local concentrations of high-albedo (bright) and low-albedo (dark) material units, in addition to spectrally distinct meteorite impact ejecta. The thermal behavior of such areas seen at local scale (1-10 km) is related to physical properties that can provide information about the origin of those materials. We use Dawn’s Visible and InfraRed (VIR) mapping spectrometer hyperspectral data to retrieve surface temperatures and emissivities, with high accuracy as long as temperatures are greater than 220 K. Some of the dark and bright features were observed multiple times by VIR in the various mission phases at variable spatial resolution, illumination and observation angles, local solar time, and heliocentric distance. This work presents the first temperature maps and spectral emissivities of several kilometer-scale dark and bright material units on Vesta. Results retrieved from the infrared data acquired by VIR show that bright regions generally correspond to regions with lower temperature, while dark regions correspond to areas with higher temperature. During maximum daily insolation and in the range of heliocentric distances explored by Dawn, i.e. 2.23-2.54 AU, the warmest dark unit found on Vesta rises to a temperature of 273 K, while bright units observed under comparable conditions do not exceed 266 K. Similarly, dark units appear to have higher emissivity on average compared to bright units. Dark-material units show a weak anticorrelation between temperature and albedo, whereas the relation is stronger for bright material units observed under the same conditions. Individual features may show either evanescent or distinct margins in the thermal images, as a consequence of the cohesion of the surface material. Finally, for the two categories of dark and bright materials, we were able to highlight the influence of heliocentric distance on surface temperatures, and estimate an average temperature rate change of 1% following a variation of 0.04 AU in the solar distance.

Lunar brightness temperature from Microwave Radiometers data of Chang'E-1 and Chang'E-2

NASA Astrophysics Data System (ADS)

Feng, J.-Q.; Su, Y.; Zheng, L.; Liu, J.-J.

2011-10-01

Both of the Chinese lunar orbiter, Chang'E-1 and Chang'E-2 carried Microwave Radiometers (MRM) to obtain the brightness temperature of the Moon. Based on the different characteristics of these two MRMs, modified algorithms of brightness temperature and specific ground calibration parameters were proposed, and the corresponding lunar global brightness temperature maps were made here. In order to analyze the data distributions of these maps, normalization method was applied on the data series. The second channel data with large deviations were rectified, and the reasons of deviations were analyzed in the end.

The Influence of Microphysical Cloud Parameterization on Microwave Brightness Temperatures

NASA Technical Reports Server (NTRS)

Skofronick-Jackson, Gail M.; Gasiewski, Albin J.; Wang, James R.; Zukor, Dorothy J. (Technical Monitor)

2000-01-01

The microphysical parameterization of clouds and rain-cells plays a central role in atmospheric forward radiative transfer models used in calculating passive microwave brightness temperatures. The absorption and scattering properties of a hydrometeor-laden atmosphere are governed by particle phase, size distribution, aggregate density., shape, and dielectric constant. This study identifies the sensitivity of brightness temperatures with respect to the microphysical cloud parameterization. Cloud parameterizations for wideband (6-410 GHz observations of baseline brightness temperatures were studied for four evolutionary stages of an oceanic convective storm using a five-phase hydrometeor model in a planar-stratified scattering-based radiative transfer model. Five other microphysical cloud parameterizations were compared to the baseline calculations to evaluate brightness temperature sensitivity to gross changes in the hydrometeor size distributions and the ice-air-water ratios in the frozen or partly frozen phase. The comparison shows that, enlarging the rain drop size or adding water to the partly Frozen hydrometeor mix warms brightness temperatures by up to .55 K at 6 GHz. The cooling signature caused by ice scattering intensifies with increasing ice concentrations and at higher frequencies. An additional comparison to measured Convection and Moisture LA Experiment (CAMEX 3) brightness temperatures shows that in general all but, two parameterizations produce calculated T(sub B)'s that fall within the observed clear-air minima and maxima. The exceptions are for parameterizations that, enhance the scattering characteristics of frozen hydrometeors.

Electrically-Active Convection and Tropical Cyclogenesis in the Atlantic and East Pacific

NASA Technical Reports Server (NTRS)

Leppert, Kenneth D., II; Petersen, Walter A.

2010-01-01

It has been hypothesized that deep, intense convective-scale "hot" towers may aid the process of tropical cyclogenesis and intensification through dynamic and thermodynamic feedbacks on the larger meso-to-synoptic scale circulation. In this study, we make use of NCEP Reanalysis data and Tropical Rainfall Measurement Mission (TRMM) lightning imaging sensor (LIS), precipitation radar (PR), and microwave imager (TMI) data to investigate the role that widespread and/or intense lightning-producing convection (i.e., "electrically-hot towers") present in African easterly waves (AEWs) may play in tropical cyclogenesis over the Atlantic, Caribbean, and East Pacific regions. NCEP Reanalysis 700 hPa meridional winds for the months of June to November for the years 2001-2009 were analyzed for the domain of 5degN-20degN and 130degW-20degE in order to partition individual AEWs into northerly, southerly, trough, and ridge phases. Subsequently, information from National Hurricane Center (NHC) storm reports was used to divide the waves into developing and non-developing waves and to further divide the developing waves into those waves that spawned storms that only developed to tropical storm strength and those that spawned storms that reached hurricane strength. The developing waves were also divided by the region in which they developed. To help determine the gross nature of the smaller convective scale, composites were created of all developing and non-developing waves as a function of AEW wave phase over the full analysis domain and over various smaller longitude bands by compositing TRMM PR, TMI, LIS, and IR brightness temperature data extracted from the NASA global-merged IR brightness temperature dataset. Finally, similar composites were created using various NCEP variables to assess the nature of the larger scale environment and circulation. Results suggest a clear distinction between developing and non-developing waves as developing waves near their region of development in terms of the intensity of convection (indicated by lightning flash rate), coverage of cold cloudiness (indicated by the percentage of a 2.5deg by 2.5deg box covered by IR brightness temperatures less than 210 K), and large-scale variables, such as midlevel moisture and upper-level upward motion. For example, waves that developed in the East Pacific longitude band (i.e., 130degW-95degW) were observed in that band to have a flash rate of 56.4 flashes/day, a coverage by brightness temperatures less than 210 K equal to 2.2%, a 700-hPa specific humidity anomaly of 0.4 g/kg, and a 300-hPa omega value of -0.04 Pascals/s in the trough phase compared to the non-developing wave trough values of 22.1 flashes/day, a coverage by brightness temperatures less than 210 K equal to 0.9%, a 700-hPa specific humidity anomaly of -0.3 g/kg, and a 300-hPa omega value of -0.01 Pascals/s.

[Influence of brightness value of supranasal point and apex nasi on dominant wavelength and excitation purity in complexion inspection of healthy adults].

PubMed

Zhu, Zhi-Rong; Zeng, Chang-Chun; Yang, Li; Liu, Han-Ping; Liu, Song-Hao

2011-12-01

In this study, to analyze the influence of the brightness value of the supranasal point and the apex nasi on their dominant wavelength and excitation purity according to the spectrocolorimetry data of the supranasal point and the apex nasi in healthy adults that were collected based on optical spectrum colorimetry. A total of 516 healthy adults were taken as the research subjects. The brightness, dominant wavelength and excitation purity values of the supranasal point and the apex nasi during the complexion inspection of subjects were calculated. This was based on the visible reflection spectrum, and the linear correlation/regression analysis between the brightness Y value and the dominant wavelength or excitation purity value. There was no correlation between the brightness Y value and the dominant wavelength of the normal supranasal point and the apex nasi; however, there was negative correlation between the brightness Y value and the excitation purity of the normal supranasal point and apex nasi. During the complexion inspection, the brightness Y value would not influence the dominant wavelength value, indicating that whiteness and/or blackness would not influence the normal individual complexion. However, the brightness Y value would influence the excitation purity of the supranasal point and the apex nasi, and the degree of saturation should be referred to as the brightness. This research provides a basic reference for diagnosing facial complexion in traditional Chinese medicine.

The seasonal variation in skin hydration, sebum, scaliness, brightness and elasticity in Korean females.

PubMed

Nam, G W; Baek, J H; Koh, J S; Hwang, J-K

2015-02-01

Age, gender, regional, and ethnic differences influence skin conditions. The purpose of this study was to observe the effects of environments, especially the air temperature, relative humidity, air pressure, duration of sunshine, and precipitation on skin, and the seasonal variation in skin hydration, sebum, scales, brightness, and elasticity in Korean females. The study included 89 Korean subjects, aged 29.7 ± 6.2 years. The five skin biophysical parameters (skin hydration, sebum, scales, brightness, and elasticity) were measured at six sites: forehead, under the eye, frontal cheek, crow's foot, lateral cheek, and inner forearm. Skin hydration was measured using the Corneometer® CM 825. Skin sebum was measured with Sebumeter® SM 815. Skin scaliness was measured with Visioscan® VC 98. Skin brightness (L* value) was measured by using Spectrophotometer. A suction chamber device, Cutometer® MPA 580, was used to measure the skin elasticity. The measurements were performed every month for 13 months, from April 2007 to April 2008. There were significantly seasonal variations in environmental factors. The air temperature was the lowest in January (-1.7°C), and the highest in August (26.5°C). The relative humidity was the lowest in February (46%), and the highest in July and August (75%). There was a negative correlation between skin scaliness and three environmental factors such as air temperature, relative humidity, and highest precipitation. There was a positive correlation between skin scaliness and two environmental factors such as air pressure and duration of sunshine. Elasticity was correlated with air temperature positively and with air pressure negatively. The correlations shown between the skin biophysical parameters and environmental factors demonstrate that the skin biophysical parameters are affected by environmental factors. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Exposure to bright light for several hours during the daytime lowers tympanic temperature.

PubMed

Aizawa, S; Tokura, H

1997-11-01

The present study investigates the effect on thympanic temperature of exposure to different light intensities for several hours during the daytime. Nine healthy young adult volunteers (two male, seven female) were exposed to bright light of 4000 lx or dim light of 100 lx during the daytime from 0930 to 1800 hours; the light condition was then kept at 100 lx for a further hour. Tympanic temperature was measured continuously at a neutral condition (28 degrees C, 60% relative humidity) from 1000 to 1800 hours. Urinary samples were collected from 1100 to 1900 hours every 2 h, and melatonin excretion rate was measured by enzyme immunoassay. Of nine subjects, six showed clearly lower tympanic temperatures in the bright compared with the dim condition from 1400 to 1800 hours. Average tympanic temperatures were significantly lower in the bright than in the dim condition from 1645 to 1800 hours. Melatonin excretion rate tended to be higher in the bright than in the dim condition. It was concluded that exposure to bright light of 4000 lx during the daytime for several hours could reduce tympanic temperature, compared with that measured in dim light of 100 lx.

Exposure to bright light for several hours during the daytime lowers tympanic temperature

NASA Astrophysics Data System (ADS)

Aizawa, Seika; Tokura, H.

The present study investigates the effect on thympanic temperature of exposure to different light intensities for several hours during the daytime. Nine healthy young adult volunteers (two male, seven female) were exposed to bright light of 4000 lx or dim light of 100 lx during the daytime from 0930 to 1800 hours; the light condition was then kept at 100 lx for a further hour. Tympanic temperature was measured continuously at a neutral condition (28° C, 60% relative humidity) from 1000 to 1800 hours. Urinary samples were collected from 1100 to 1900 hours every 2 h, and melatonin excretion rate was measured by enzyme immunoassay. Of nine subjects, six showed clearly lower tympanic temperatures in the bright compared with the dim condition from 1400 to 1800 hours. Average tympanic temperatures were significantly lower in the bright than in the dim condition from 1645 to 1800 hours. Melatonin excretion rate tended to be higher in the bright than in the dim condition. It was concluded that exposure to bright light of 4000 lx during the daytime for several hours could reduce tympanic temperature, compared with that measured in dim light of 100 lx.

Classification of sea ice types with single-band (33.6 GHz) airborne passive microwave imagery

NASA Astrophysics Data System (ADS)

Eppler, Duane T.; Farmer, L. Dennis; Lohanick, Alan W.; Hoover, Mervyn

1986-09-01

During March 1983 extensive high-quality airborne passive Ka band (33.6 GHz) microwave imagery and coincident high-resolution aerial photography were obtained of ice along a 378-km flight line in the Beaufort Sea. Analysis of these data suggests that four classes of winter surfaces can be distinguished solely on the basis of 33.6-GHz brightness temperature: open water, frazil, old ice, and young/first-year ice. New ice (excluding frazil) and nilas display brightness temperatures that overlap the range of temperatures characteristic of old ice and, to a lesser extent, young/first-year ice. Scenes in which a new ice or nilas are present in appreciable amounts are subject to substantial errors in classification if static measures of Ka band radiometric brightness temperature alone are considered. Textural characteristics of nilas and new ice, however, differ significantly from textural features characteristic of other ice types and probably can be used with brightness temperature data to classify ice type in high-resolution single-band microwave images. In any case, open water is radiometrically the coldest surface observed in any scene. Lack of overlap between brightness temperatures characteristic of other surfaces indicates that estimates of the areal extent of open water based on only 33.6-GHz brightness temperatures are accurate.

Foundations for statistical-physical precipitation retrieval from passive microwave satellite measurements. I - Brightness-temperature properties of a time-dependent cloud-radiation model

NASA Technical Reports Server (NTRS)

Smith, Eric A.; Mugnai, Alberto; Cooper, Harry J.; Tripoli, Gregory J.; Xiang, Xuwu

1992-01-01

The relationship between emerging microwave brightness temperatures (T(B)s) and vertically distributed mixtures of liquid and frozen hydrometeors was investigated, using a cloud-radiation model, in order to establish the framework for a hybrid statistical-physical rainfall retrieval algorithm. Although strong relationships were found between the T(B) values and various rain parameters, these correlations are misleading in that the T(B)s are largely controlled by fluctuations in the ice-particle mixing ratios, which in turn are highly correlated to fluctuations in liquid-particle mixing ratios. However, the empirically based T(B)-rain-rate (T(B)-RR) algorithms can still be used as tools for estimating precipitation if the hydrometeor profiles used for T(B)-RR algorithms are not specified in an ad hoc fashion.

If the Sun Were a Light Bulb.

ERIC Educational Resources Information Center

Adney, Kenneth J.

1991-01-01

An activity in which students compare the sun's brightness with that of a light bulb of known luminosity (in watts) to determine the luminosity of the sun is presented. As an extension, the luminosity value that the student obtains for the sun can also be used to estimate the sun's surface temperature. (KR)

Effect of soil texture on the microwave emission from soils

NASA Technical Reports Server (NTRS)

Schmugge, T. J.

1980-01-01

The intensity brightness temperature of the microwave emission from the soil is determined primarily by its dielectric properties. The large difference between the dielectric constant of water and that of dry soil produces a strong dependence of the soil's dielectric constant on its moisture content. This dependence is effected by the texture of the soil because the water molecules close to the particle surface are tightly bound and do not contribute significantly to the dielectric properties. Since this surface area is a function of the particle size distribution (soil texture), being larger for clay soils with small particles, and smaller for sandy soils with larger particles; the dielectric properties will depend on soil texture. Laboratory measurements of the dielectric constant for soils are summarized. The dependence of the microwave emission on texture is demonstrated by measurements of brightness temperature from an aircraft platform for a wide range of soil textures. It is concluded that the effect of soil texture differences on the observed values can be normalized by expressing the soil moisture values as a percent field capacity for the soil.

The Cold Land Processes Experiment (CLPX-1): Analysis and Modelling of LSOS Data (IOP3 Period)

NASA Technical Reports Server (NTRS)

Tedesco, Marco; Kim, Edward J.; Cline, Don; Graf, Tobias; Koike, Toshio; Hardy, Janet; Armstrong, Richard; Brodzik, Mary

2004-01-01

Microwave brightness temperatures at 18.7,36.5, and 89 GHz collected at the Local-Scale Observation Site (LSOS) of the NASA Cold-Land Processes Field Experiment in February, 2003 (third Intensive Observation Period) were simulated using a Dense Media Radiative Transfer model (DMRT), based on the Quasi Crystalline Approximation with Coherent Potential (QCA-CP). Inputs to the model were averaged from LSOS snow pit measurements, although different averages were used for the lower frequencies vs. the highest one, due to the different penetration depths and to the stratigraphy of the snowpack. Mean snow particle radius was computed as a best-fit parameter. Results show that the model was able to reproduce satisfactorily brightness temperatures measured by the University of Tokyo s Ground Based Microwave Radiometer system (CBMR-7). The values of the best-fit snow particle radii were found to fall within the range of values obtained by averaging the field-measured mean particle sizes for the three classes of Small, Medium and Large grain sizes measured at the LSOS site.

Effects of evening bright light exposure on melatonin, body temperature and sleep.

PubMed

Bunnell; Treiber; Phillips; Berger

1992-03-01

Five male subjects were exposed to a single 2-h period of bright (2500 lux) or dim (<100 lux) light prior to sleep on two consecutive nights. The two conditions were repeated the following week in opposite order. Bright light significantly suppressed salivary melatonin and raised rectal temperature 0.3 degrees C (which remained elevated during the first 1.5 h of sleep), without affecting tympanic temperature. Bright light also increased REM latency, NREM period length, EEG spectral power in low frequency, 0.75-8 Hz and sigma, 12-14 Hz (sleep spindle) bandwidths during the first hour of sleep, and power of all frequency bands (0.5-32 Hz) within the first NREMP. Potentiation of EEG slow wave activity (0.5-4.0 Hz) by bright light persisted through the end of the second NREMP. The enhanced low-frequency power and delayed REM sleep after bright light exposure could represent a circadian phase-shift and/or the effect of an elevated rectal temperature, possibly mediated by the suppression of melatonin.

The plasma filling factor of coronal bright points. II. Combined EIS and TRACE results

NASA Astrophysics Data System (ADS)

Dere, K. P.

2009-04-01

Aims: In a previous paper, the volumetric plasma filling factor of coronal bright points was determined from spectra obtained with the Extreme ultraviolet Imaging Spectrometer (EIS). The analysis of these data showed that the median plasma filling factor was 0.015. One interpretation of this result was that the small filling factor was consistent with a single coronal loop with a width of 1-2´´, somewhat below the apparent width. In this paper, higher spatial resolution observations with the Transition Region and Corona Explorer (TRACE) are used to test this interpretation. Methods: Rastered spectra of regions of the quiet Sun were recorded by the EIS during operations with the Hinode satellite. Many of these regions were simultaneously observed with TRACE. Calibrated intensities of Fe xii lines were obtained and images of the quiet corona were constructed from the EIS measurements. Emission measures were determined from the EIS spectra and geometrical widths of coronal bright points were obtained from the TRACE images. Electron densities were determined from density-sensitive line ratios measured with EIS. A comparison of the emission measure and bright point widths with the electron densities yielded the plasma filling factor. Results: The median electron density of coronal bright points is 3 × 109 cm-3 at a temperature of 1.6 × 106 K. The volumetric plasma filling factor of coronal bright points was found to vary from 3 × 10-3 to 0.3 with a median value of 0.04. Conclusions: The current set of EIS and TRACE coronal bright-point observations indicate the median value of their plasma filling factor is 0.04. This can be interpreted as evidence of a considerable subresolution structure in coronal bright points or as the result of a single completely filled plasma loop with widths on the order of 0.2-1.5´´ that has not been spatially resolved in these measurements.

The Seasat scanning multichannel microwave radiometer /SMMR/: Antenna pattern corrections - Development and implementation

NASA Technical Reports Server (NTRS)

Njoku, E. G.; Christensen, E. J.; Cofield, R. E.

1980-01-01

The antenna temperatures measured by the Seasat scanning multichannel microwave radiometer (SMMR) differ from the true brightness temperatures of the observed scene due to antenna pattern effects, principally from antenna sidelobe contributions and cross-polarization coupling. To provide accurate brightness temperatures convenient for geophysical parameter retrievals the antenna temperatures are processed through a series of stages, collectively known as the antenna pattern correction (APC) algorithm. A description of the development and implementation of the APC algorithm is given, along with an error analysis of the resulting brightness temperatures.

Evaluation and analysis of Seasat-A scanning multichannel Microwave Radiometer (SMMR) Antenna Pattern Correction (APC) algorithm

NASA Technical Reports Server (NTRS)

Kitzis, J. L.; Kitzis, S. N.

1979-01-01

The brightness temperature data produced by the SMMR final Antenna Pattern Correction (APC) algorithm is discussed. The algorithm consisted of: (1) a direct comparison of the outputs of the final and interim APC algorithms; and (2) an analysis of a possible relationship between observed cross track gradients in the interim brightness temperatures and the asymmetry in the antenna temperature data. Results indicate a bias between the brightness temperature produced by the final and interim APC algorithm.

Study of the model of calibrating differences of brightness temperature from geostationary satellite generated by time zone differences

NASA Astrophysics Data System (ADS)

Li, Weidong; Shan, Xinjian; Qu, Chunyan

2010-11-01

In comparison with polar-orbiting satellites, geostationary satellites have a higher time resolution and wider field of visions, which can cover eleven time zones (an image covers about one third of the Earth's surface). For a geostationary satellite panorama graph at a point of time, the brightness temperature of different zones is unable to represent the thermal radiation information of the surface at the same point of time because of the effect of different sun solar radiation. So it is necessary to calibrate brightness temperature of different zones with respect to the same point of time. A model of calibrating the differences of the brightness temperature of geostationary satellite generated by time zone differences is suggested in this study. A total of 16 curves of four positions in four different stages are given through sample statistics of brightness temperature of every 5 days synthetic data which are from four different time zones (time zones 4, 6, 8, and 9). The above four stages span January -March (winter), April-June (spring), July-September (summer), and October-December (autumn). Three kinds of correct situations and correct formulas based on curves changes are able to better eliminate brightness temperature rising or dropping caused by time zone differences.

Calculation of gyrosynchrotron radiation brightness temperature for outer bright loop of ICME

NASA Astrophysics Data System (ADS)

Sun, Weiying; Wu, Ji; Wang, C. B.; Wang, S.

:Solar polar orbit radio telescope (SPORT) is proposed to detect the high density plasma clouds of outer bright loop of ICMEs from solar orbit with large inclination. Of particular interest is following the propagation of the plasma clouds with remote sensor in radio wavelength band. Gyrosynchrotron emission is a main radio radiation mechanism of the plasma clouds and can provide information of interplanetary magnetic field. In this paper, we statistically analyze the electron density, electron temperature and magnetic field of background solar wind in time of quiet sun and ICMEs propagation. We also estimate the fluctuation range of the electron density, electron temperature and magnetic field of outer bright loop of ICMEs. Moreover, we calculate and analyze the emission brightness temperature and degree of polarization on the basis of the study of gyrosynchrotron emission, absorption and polarization characteristics as the optical depth is less than or equal to 1.

Tolerance of brightness and contrast adjustments on chronic apical abscess and apical granuloma interpretation

NASA Astrophysics Data System (ADS)

Purnamasari, L.; Iskandar, H. H. B.; Makes, B. N.

2017-08-01

In digitized radiography techniques, adjusting the image enhancement can improve the subjective image quality by optimizing the brightness and contrast for diagnostic needs. To determine the value range of image enhancement (brightness and contrast) on chronic apical abscess and apical granuloma interpretation. 30 periapical radiographs that diagnosed chronic apical abscess and 30 that diagnosed apical granuloma were adjusted by changing brightness and contrast values. The value range of brightness and contrast adjustment that can be tolerated in radiographic interpretations of chronic apical abscess and apical granuloma spans from -10 to +10. Brightness and contrast adjustments on digital radiographs do not affect the radiographic interpretation of chronic apical abscess and apical granuloma if conducted within the value range.

Probing the innermost regions of AGN jets and their magnetic fields with RadioAstron. II. Observations of 3C 273 at minimum activity

NASA Astrophysics Data System (ADS)

Bruni, G.; Gómez, J. L.; Casadio, C.; Lobanov, A.; Kovalev, Y. Y.; Sokolovsky, K. V.; Lisakov, M. M.; Bach, U.; Marscher, A.; Jorstad, S.; Anderson, J. M.; Krichbaum, T. P.; Savolainen, T.; Vega-García, L.; Fuentes, A.; Zensus, J. A.; Alberdi, A.; Lee, S.-S.; Lu, R.-S.; Pérez-Torres, M.; Ros, E.

2017-08-01

Context. RadioAstron is a 10 m orbiting radio telescope mounted on the Spektr-R satellite, launched in 2011, performing Space Very Long Baseline Interferometry (SVLBI) observations supported by a global ground array of radio telescopes. With an apogee of 350 000 km, it is offering for the first time the possibility to perform μas-resolution imaging in the cm-band. Aims: The RadioAstron active galactic nuclei (AGN) polarization Key Science Project (KSP) aims at exploiting the unprecedented angular resolution provided by RadioAstron to study jet launching/collimation and magnetic-field configuration in AGN jets. The targets of our KSP are some of the most powerful blazars in the sky. Methods: We present observations at 22 GHz of 3C 273, performed in 2014, designed to reach a maximum baseline of approximately nine Earth diameters. Reaching an angular resolution of 0.3 mas, we study a particularly low-activity state of the source, and estimate the nuclear region brightness temperature, comparing with the extreme one detected one year before during the RadioAstron early science period. We also make use of the VLBA-BU-BLAZAR survey data, at 43 GHz, to study the kinematics of the jet in a 1.5-yr time window. Results: We find that the nuclear brightness temperature is two orders of magnitude lower than the exceptionally high value detected in 2013 with RadioAstron at the same frequency (1.4 × 1013 K, source-frame), and even one order of magnitude lower than the equipartition value. The kinematics analysis at 43 GHz shows that a new component was ejected 2 months after the 2013 epoch, visible also in our 22 GHz map presented here. Consequently this was located upstream of the core during the brightness temperature peak. Fermi-LAT observations for the period 2010-2014 do not show any γ-ray flare in conjunction with the passage of the new component by the core at 43 GHz. Conclusions: These observations confirm that the previously detected extreme brightness temperature in 3C 273, exceeding the inverse Compton limit, is a short-lived phenomenon caused by a temporary departure from equipartition. Thus, the availability of interferometric baselines capable of providing μas angular resolution does not systematically imply measured brightness temperatures over the known physical limits for astrophysical sources. The reduced image (FITS file) is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/604/A111

Mercury: infrared evidence for nonsynchronous rotation.

PubMed

Soter, S L

1966-09-02

An infrared observation of the dark side of Mercury made by Pettit and Nicholson in 1923 led them to suggest that the planet rotates nonsynchronously. Their early measurements, if taken at face value, would imply a brightness temperature of about 180 degrees K for the dark side. The asymmetry of the infrared phase curve is further interpreted as suggesting direct rotation.

Heavy thunderstorms observed over land by the Nimbus 7 scanning multichannel microwave radiometer

NASA Technical Reports Server (NTRS)

Spencer, R. W.; Olson, W. S.; Martin, D. W.; Weinman, J. A.; Santek, D. A.; Wu, R.

1983-01-01

Brightness temperatures obtained through examination of microwave data from the Nimbus 7 satellite are noted to be much lower than those expected on the strength of radiation emanating from rain-producing clouds. Very cold brightness temperature cases all coincided with heavy thunderstorm rainfall, with the cold temperatures being attributable to scattering by a layer of ice hydrometeors in the upper parts of the storms. It is accordingly suggested that brightness temperatures observed by satellite microwave radiometers can sometimes distinguish heavy rain over land.

Characterization and Correction of Aquarius Long Term Calibration Drift Using On-Earth Brightness Temperature Refernces

NASA Technical Reports Server (NTRS)

Brown, Shannon; Misra, Sidharth

2013-01-01

The Aquarius/SAC-D mission was launched on June 10, 2011 from Vandenberg Air Force Base. Aquarius consists of an L-band radiometer and scatterometer intended to provide global maps of sea surface salinity. One of the main mission objectives is to provide monthly global salinity maps for climate studies of ocean circulation, surface evaporation and precipitation, air/sea interactions and other processes. Therefore, it is critical that any spatial or temporal systematic biases be characterized and corrected. One of the main mission requirements is to measure salinity with an accuracy of 0.2 psu on montly time scales which requires a brightness temperature stability of about 0.1K, which is a challenging requirement for the radiometer. A secondary use of the Aquarius data is for soil moisture applications, which requires brightness temperature stability at the warmer end of the brightness temperature dynamic range. Soon after launch, time variable drifts were observed in the Aquarius data compared to in-situ data from ARGO and models for the ocean surface salinity. These drifts could arise from a number of sources, including the various components of the retrieval algorithm, such as the correction for direct and reflected galactic emission, or from the instrument brightness temperature calibration. If arising from the brightness temperature calibration, they could have gain and offset components. It is critical that the nature of the drifts be understood before a suitable correction can be implemented. This paper describes the approach that was used to detect and characterize the components of the drift that were in the brightness temperature calibration using on-Earth reference targets that were independent of the ocean model.

Optical emission of directly contacted copper/sapphire interface under shock compression of megabar

NASA Astrophysics Data System (ADS)

Hao, G. Y.; Liu, F. S.; Zhang, D. Y.; Zhang, M. J.

2007-06-01

The shock-induced optical emission histories from copper/sapphire interface were measured under two different contact conditions, which simulated the typical situations of pyrometry experiments. Results showed that the "peak" feature of the radiation, previously interpreted as the appearance of so-called high-temperature layer, was nearly diminished by finely polishing and uniformly prepressing technique, and that it is possible to directly measure the equilibrium temperature of bulk metal/window interface. Study also demonstrated that the saturated value of the apparent temperature in nonideal contact situation is related to the color temperature of the shock-induced "bright spot" in sapphire window under megabar pressures.

The estimation of the propagation delay through the troposphere from microwave radiometer data. [very long base interferometry

NASA Technical Reports Server (NTRS)

Moran, J. M.; Rosen, B. R.

1980-01-01

The uncertainity in propagation delay estimates is due primarily to tropospheric water, the total amount and vertical distribution of which is variable. Because water vapor both delays and attenuates microwave signals, the propagation delay, or wet path length, can be estimated from the microwave brightness temperature near the 22.235 GHz transition of water vapor. The data from a total of 240 radiosonde launches taken simultaneously were analyzed. Estimates of brightness temperature at 19 and 22 GHz and wet path length were made from these data. The wet path length in the zenith direction could be estimated from the surface water vapor density to an accuracy of 5 cm for the summer data and 2 cm for winter data. Using the brightness temperatures, the wet path could be estimated to an accuracy of 0.3 cm. Two dual frequency radiometers were refurbished in order to test these techniques. These radiometers were capable of measuring the difference in the brightness temperature at 30 deg elevation angle and at the zenith to an accuracy of about 1 K. In August 1975, 45 radiosondes were launched over an 11 day period. Brightness temperature measurements were made simultaneously at 19 and 22 GHz with the radiometers. The rms error for the estimation of wet path length from surface meteorological parameters was 3.2 cm, and from the radiometer brightness temperatures, 1.5 cm.

Thin Sea-Ice Thickness as Inferred from Passive Microwave and In Situ Observations

NASA Technical Reports Server (NTRS)

Naoki, Kazuhiro; Ukita, Jinro; Nishio, Fumihiko; Nakayama, Masashige; Comiso, Josefino C.; Gasiewski, Al

2007-01-01

Since microwave radiometric signals from sea-ice strongly reflect physical conditions of a layer near the ice surface, a relationship of brightness temperature with thickness is possible especially during the early stages of ice growth. Sea ice is most saline during formation stage and as the salinity decreases with time while at the same time the thickness of the sea ice increases, a corresponding change in the dielectric properties and hence the brightness temperature may occur. This study examines the extent to which the relationships of thickness with brightness temperature (and with emissivity) hold for thin sea-ice, approximately less than 0.2 -0.3 m, using near concurrent measurements of sea-ice thickness in the Sea of Okhotsk from a ship and passive microwave brightness temperature data from an over-flying aircraft. The results show that the brightness temperature and emissivity increase with ice thickness for the frequency range of 10-37 GHz. The relationship is more pronounced at lower frequencies and at the horizontal polarization. We also established an empirical relationship between ice thickness and salinity in the layer near the ice surface from a field experiment, which qualitatively support the idea that changes in the near-surface brine characteristics contribute to the observed thickness-brightness temperature/emissivity relationship. Our results suggest that for thin ice, passive microwave radiometric signals contain, ice thickness information which can be utilized in polar process studies.

Polar Chromospheric Signatures of the Subdued Cycle 23/24 Solar Minimum

NASA Technical Reports Server (NTRS)

Gopalswamy, N.; Yashiro, S.; Makela, P.; Shibasaki, K.; Hathaway, D.

2010-01-01

Coronal holes appear brighter than the quiet Sun in microwave images, with a brightness enhancement of 500 to 2000 K. The brightness enhancement corresponds to the upper chromosphere, where the plasma temperature is about 10000 K. We constructed a microwave butterfly diagram using the synoptic images obtained by the Nobeyama radioheliograph (NoRH) showing the evolution of the polar and low latitude brightness temperature. While the polar brightness reveals the chromospheric conditions, the low latitude brightness is attributed to active regions in the corona. When we compared the microwave butterfly diagram with the magnetic butterfly diagram, we found a good correlation between the microwave brightness enhancement and the polar field strength. The microwave butterfly diagram covers part of solar cycle 22, whole of cycle 23, and part of cycle 24, thus enabling comparison between the cycle 23/24 and cycle 22/23 minima. The microwave brightness during the cycle 23/24 minimum was found to be lower than that during the cycle 22/23 minimum by approximately 250 K. The reduced brightness temperature is consistent with the reduced polar field strength during the cycle 23/24 minimum seen in the magnetic butterfly diagram. We suggest that the microwave brightness at the solar poles is a good indicator of the speed of the solar wind sampled by Ulysses at high latitudes.

Microphysical Retrievals Over Stratiform Rain Using Measurements from an Airborne Dual-Wavelength Radar-Radiometer

NASA Technical Reports Server (NTRS)

Meneghini, Robert; Kumagai, Hiroshi; Wang, James R.; Iguchi, Toshio; Kozu, Toshiaki

1997-01-01

The need to understand the complementarity of the radar and radiometer is important not only to the Tropical Rain Measuring Mission (TRMM) program but to a growing number of multi-instrumented airborne experiment that combine single or dual-frequency radars with multichannel radiometers. The method of analysis used in this study begins with the derivation of dual-wavelength radar equations for the estimation of a two-parameter drop size distribution (DSD). Defining a "storm model" as the set of parameters that characterize snow density, cloud water, water vapor, and features of the melting layer, then to each storm model there will usually correspond a set of range-profiled drop size distributions that are approximate solutions of the radar equations. To test these solutions, a radiative transfer model is used to compute the brightness temperatures for the radiometric frequencies of interest. A storm model or class of storm models is considered optimum if it provides the best reproduction of the radar and radiometer measurements. Tests of the method are made for stratiform rain using simulated storm models as well as measured airborne data. Preliminary results show that the best correspondence between the measured and estimated radar profiles usually can be obtained by using a moderate snow density (0.1-0.2 g/cu cm), the Maxwell-Garnett mixing formula for partially melted hydrometeors (water matrix with snow inclusions), and low to moderate values of the integrated cloud liquid water (less than 1 kg/sq m). The storm-model parameters that yield the best reproductions of the measured radar reflectivity factors also provide brightness temperatures at 10 GHz that agree well with the measurements. On the other hand, the correspondence between the measured and modeled values usually worsens in going to the higher frequency channels at 19 and 34 GHz. In searching for possible reasons for the discrepancies, It is found that changes in the DSD parameter Mu, the radar constants, or the path-integrated attenuation can affect the high frequency channels significantly. In particular, parameters that cause only modest increases in the median mass diameter of the snow, and which have a minor effect on the radar returns or the low frequency brightness temperature, can produce a strong cooling of the 34 GHz brightness temperature.

Satellite microwave and in situ observations of the Weddell Sea ice cover and its marginal ice zone

NASA Technical Reports Server (NTRS)

Comiso, J. C.; Sullivan, C. W.

1986-01-01

The radiative and physical characteristics of the Weddell Sea ice cover and its marginal ice zone are analyzed using multichannel satellite passive microwave data and ship and helicopter observations obtained during the 1983 Antarctic Marine Ecosystem Research. Winter and spring brightness temperatures are examined; spatial variability in the brightness temperatures of consolidated ice in winter and spring cyclic increases and decrease in brightness temperatures of consolidated ice with an amplitude of 50 K at 37 GHz and 20 K at 18 GHz are observed. The roles of variations in air temperature and surface characteristics in the variability of spring brightness temperatures are investigated. Ice concentrations are derived using the frequency and polarization techniques, and the data are compared with the helicopter and ship observations. Temporal changes in the ice margin structure and the mass balance of fresh water and of biological features of the marginal ice zone are studied.

Effect of morning bright light on body temperature, plasma cortisol and wrist motility measured during 24 hour of constant conditions.

PubMed

Foret, J; Aguirre, A; Touitou, Y; Clodoré, M; Benoit, O

1993-06-11

Using 24 h constant conditions, time course of body temperature, plasma cortisol and wrist motility was measured in response to a 3 day morning 2 h bright light pulse. This protocol demonstrated that a 2000 lux illumination was sufficient to elicit a shift of about 2 h of temperature minimum and cortisol peak. In reference session, actimetric recordings showed a circadian time course, closely in relation with core temperature. Bright light pulse resulted in a decrease of amplitude and a disappearance of circadian pattern of actimetry.

Energy and Emission Characteristics of a Short-Arc Xenon Flash Lamp Under "Saturated" Optical Brightness Conditions

NASA Astrophysics Data System (ADS)

Kamrukov, A. S.; Kireev, S. G.; Kozlov, N. P.; Shashkovskii, S. G.

2017-09-01

We present the results of a study of the electrical, energy, and spectral brightness characteristics of an experimental three-electrode high-pressure xenon flash lamp under conditions ensuring close to maximum possible spectral brightness for the xenon emission. We show that under saturated optical brightness conditions (brightness temperature in the visible region of the spectrum 30,000 K), emission of a pulsed discharge in xenon is quite different from the emission from an ideal blackbody: the maximum brightness temperatures are 24,000 K in the short-wavelength UV region and 19,000 K in the near IR range. The relative fraction of UV radiation in the emission spectrum of the lamp is >50%, which lets us consider such lamps as promising broadband sources of radiation with high spectral brightness for many important practical applications.

Evidence for Precursors of the Coronal Hole Jets in Solar Bright Points

NASA Astrophysics Data System (ADS)

Bagashvili, Salome R.; Shergelashvili, Bidzina M.; Japaridze, Darejan R.; Kukhianidze, Vasil; Poedts, Stefaan; Zaqarashvili, Teimuraz V.; Khodachenko, Maxim L.; De Causmaecker, Patrick

2018-03-01

A set of 23 observations of coronal jet events that occurred in coronal bright points has been analyzed. The focus was on the temporal evolution of the mean brightness before and during coronal jet events. In the absolute majority of the cases either single or recurrent coronal jets (CJs) were preceded by slight precursor disturbances observed in the mean intensity curves. The key conclusion is that we were able to detect quasi-periodical oscillations with characteristic periods from sub-minute up to 3–4 minute values in the bright point brightness that precedes the jets. Our basic claim is that along with the conventionally accepted scenario of bright-point evolution through new magnetic flux emergence and its reconnection with the initial structure of the bright point and the coronal hole, certain magnetohydrodynamic (MHD) oscillatory and wavelike motions can be excited and these can take an important place in the observed dynamics. These quasi-oscillatory phenomena might play the role of links between different epochs of the coronal jet ignition and evolution. They can be an indication of the MHD wave excitation processes due to the system entropy variations, density variations, or shear flows. It is very likely a sharp outflow velocity transverse gradients at the edges between the open and closed field line regions. We suppose that magnetic reconnections can be the source of MHD waves due to impulsive generation or rapid temperature variations, and shear flow driven nonmodel MHD wave evolution (self-heating and/or overreflection mechanisms).

Chromospheric Signatures of the Subdued Cycle 23/24 Solar Minimum in Microwaves

NASA Technical Reports Server (NTRS)

Yashiro, S.; Makela, P.; Shibasaki, K.; Hathaway, D.

2011-01-01

Coronal holes appear brighter than the quiet Sun in microwave images, with a brightness enhancement of 500 to 2000 K. The brightness enhancement corresponds to the upper chromosphere, where the plasma temperature is about 10000 K. We constructed a microwave butterfly diagram using the synoptic images obtained by the Nobeyama radio-heliograph (NoRH) showing the evolution of the polar and low latitude brightness temperature. While the polar brightness reveals the chromospheric conditions, the low latitude brightness is attributed to active regions in the corona. When we compared the microwave butterfly diagram with the magnetic butterfly diagram, we found a good correlation between the microwave brightness enhancement and the polar field strength. The microwave butterfly diagram covers part of solar cycle 22, whole of cycle 23, and part of cycle 24, thus enabling comparison between the cycle 23/24 and cycle 22/23 minima. The microwave brightness during the cycle 23/24 minimum was found to be lower than that during the cycle 22/23 minimum by approx.250 K. The reduced brightness temperature is consistent with the reduced polar field strength during the cycle 23/24 minimum seen in the magnetic butterfly diagram. We suggest that the microwave brightness at the solar poles is a good indicator of the speed of the solar wind sampled by Ulysses at high latitudes.

Tolerance limit value of brightness and contrast adjustment on digitized radiographs

NASA Astrophysics Data System (ADS)

Utami, S. N.; Kiswanjaya, B.; Syahraini, S. I.; Ustriyana, P.

2017-08-01

The aim of this study was to measure the tolerance limit value of brightness and contrast adjustment on digitized radiograph with apical periodontitis and early apical abscess. Brightness and contrast adjustment on 60 periapical radiograph with apical periodontitis and early apical abscess made by 2 observers. Reliabilities tested by Cohen’s Kappa Coefficient and significance tested by wilcoxon test. Tolerance limit value of brightness and contrast adjustment for apical periodontitis is -5 and +5, early apical abscess is -10 and +10, and both is -5 and +5. Brightness and contrast adjustment which not appropriate can alter the evaluation and differential diagnosis of periapical lesion.

Circadian rhythm adaptation to simulated night shift work: effect of nocturnal bright-light duration.

PubMed

Eastman, C I; Liu, L; Fogg, L F

1995-07-01

We compared bright-light durations of 6, 3 and 0 hours (i.e. dim light) during simulated night shifts for phase shifting the circadian rectal temperature rhythm to align with a 12-hour shift of the sleep schedule. After 10 baseline days there were 8 consecutive night-work, day-sleep days, with 8-hour sleep (dark) periods. The bright light (about 5,000 lux, around the baseline temperature minimum) was used during all 8 night shifts, and dim light was < 500 lux. This was a field study in which subjects (n = 46) went outside after the night shifts and slept at home. Substantial circadian adaptation (i.e. a large cumulative temperature rhythm phase shift) was produced in many subjects in the bright light groups, but not in the dim light group. Six and 3 hours of bright light were each significantly better than dim light for phase shifting the temperature rhythm, but there was no significant difference between 6 and 3 hours. Thus, durations > 3 hours are probably not necessary in similar shift-work situations. Larger temperature rhythm phase shifts were associated with better subjective daytime sleep, less subjective fatigue and better overall mood.

Characterization of Titan surface scenarios combining Cassini SAR images and radiometric data

NASA Astrophysics Data System (ADS)

Ventura, B.; Notarnicola, C.; Casarano, D.; Janssen, M.; Posa, F.; Cassini RADAR Science Team

2009-04-01

A great amount of data and images was provided by the radar on Cassini probe, thus opening and suggesting new scenarios about Titan's formation and evolution. An important result was the detection, among the peculiar and heterogeneous Titan's surface features, of lakes most likely constituted by liquid hydrocarbons, thus supporting the hypothesis of a methane cycle similar to water cycle on Earth.These areas, which resemble terrestrial lakes, seem to be sprinkled all over the high latitudes surrounding Titan's pole. The abundant methane in Titan's atmosphere combined with the low temperature, 94 K, lead scientists to interpret them as lakes of liquid methane or ethane. In this work, scattering models and a Bayesian inversion algorithm are applied in order to characterize lake and land surfaces. The possibility of combining the SAR data with radiometric ones on both lakes and neighboring land areas is also presented. Radar backscattering from lakes is described in terms of a double layer model, consisting of Bragg or facets scattering for the upper liquid layer and the Integral Equation Model (IEM) model for the lower solid surface. Furthermore, by means of a gravity-capillary wave model (Donelan-Pierson), the wave spectra of liquid hydrocarbons surfaces are introduced as a function of wind speed and direction. Theoretical radar backscattering coefficient values are compared with the experimental ones collected by the radar in order to estimate physical and morphological surface parameters, and to evaluate their compatibility with the expected constituents for Titan surfaces. This electromagnetic analysis is the starting point for a statistical inversion algorithm which allows determining limits on the parameters values, especially on the optical thickness and wind speed of the lakes. The physical surface parameters inferred by using the inversion algorithm are used as input for a forward radiative transfer model calculation to obtain simulated brightness temperatures. The radiometric model has been introduced to further verify the values ranges for the different parameters. In fact the same parameters derived from the radar data analysis have been used as input for the radiometric model. The comparison between the observed and computed brightness temperatures has been performed in order to address the consistency of the observations from the two instruments and to determine the coarse characteristics of the surface parameters. For both radar and radiometric data the soil medium is horizontally stratified into 2 layers. Each layer can be characterized by different absorption coefficients depending on the optical thickness, dielectric constant and physical temperature. In this algorithm, the starting point is the map of optical thickness derived from the SAR images. The simulated brightness temperature is calculated by applying the forward radiative transfer model to the optical thickness map with the same hypotheses assumed to derive it. The simulation is also carried out on the neighboring land areas by considering a double layer model including a contribution of volume scattering. Each layer is described in terms of dielectric constant values, albedo and roughness parameters with the hypothesis of water ice ammonia on layers of solid hydrocarbons and organic compounds like tholins. The analysis is applied to the areas detected on flybys 25 and 30. One important result arises from the analysis of the inverted optical thickness on deep lakes. In this case, found values of optical thickness can be considered limit values because, beyond these values, a complete attenuation can be considered. This limit value is important as it is stable even if the other parameters vary. Starting from this point, posing the condition of a complete attenuation of the second layer, i.e. fixing the value of the optical thickness, the algorithm can be used to estimate the wind speed. The retrieved values vary between 0.2 to 0.5 m/s. The first results also show a good agreement between the simulated data and the measured brightness temperature for both the liquid surface and the surrounding areas. In the last case, a good agreement is obtained only if the contribution from volume scattering is included in the model

Acute effects of bright light and caffeine on nighttime melatonin and temperature levels in women taking and not taking oral contraceptives

NASA Technical Reports Server (NTRS)

Wright, K. P. Jr; Myers, B. L.; Plenzler, S. C.; Drake, C. L.; Badia, P.; Czeisler, C. A. (Principal Investigator)

2000-01-01

Caffeine and bright light effects on nighttime melatonin and temperature levels in women were tested during the luteal phase of the menstrual cycle (n=30) or the pseudo luteal phase for oral contraceptive users (n=32). Participants were randomly assigned to receive either bright (5000 lux) or dim room light (<88 lux) between 20:00 and 08:00 h under a modified constant routine protocol. Half the subjects in each lighting condition were administered either caffeine (100 mg) or placebo in a double-blind manner at 20:00, 23:00, 02:00 and 05:00 h. Results showed that the combination of bright light and caffeine enhanced nighttime temperature levels to a greater extent than did either caffeine or bright light alone. Both of the latter groups had higher temperature levels relative to the dim light placebo condition and the two groups did not differ. Temperature levels in the bright light caffeine condition were maintained at near peak circadian levels the entire night in the luteal and pseudo luteal phase. Melatonin levels were reduced throughout the duration of bright light exposure for all women. Caffeine reduced the onset of melatonin levels for women in the luteal phase, but it had little effect on melatonin levels for oral contraceptive users. The results for women in the luteal phase of the menstrual cycle are consistent with our previous findings in men. The results also suggest that oral contraceptives may alter the effects of caffeine on nighttime melatonin levels.

Brightness and magnetic evolution of solar coronal bright points

NASA Astrophysics Data System (ADS)

Ugarte Urra, Ignacio

This thesis presents a study of the brightness and magnetic evolution of several Extreme ultraviolet (EUV) coronal bright points (hereafter BPs). The study was carried out using several instruments on board the Solar and Heliospheric Observatory, supported by the high resolution imaging from the Transition Region And Coronal Explorer. The results confirm that, down to 1" resolution, BPs are made of small loops with lengths of [approximate]6 Mm and cross-sections of ≈2 Mm. The loops are very dynamic, evolving in time scales as short as 1 - 2 minutes. This is reflected in a highly variable EUV response with fluctuations highly correlated in spectral lines at transition region temperatures, but not always at coronal temperatures. A wavelet analysis of the intensity variations reveals the existence of quasi-periodic oscillations with periods ranging 400--1000s, in the range of periods characteristic of the chromospheric network. The link between BPs and network bright points is discussed, as well as the interpretation of the oscillations in terms of global acoustic modes of closed magnetic structures. A comparison of the magnetic flux evolution of the magnetic polarities to the EUV flux changes is also presented. Throughout their lifetime, the intrinsic EUV emission of BPs is found to be dependent on the total magnetic flux of the polarities. In short time scales, co-spatial and co-temporal coronal images and magnetograms, reveal the signature of heating events that produce sudden EUV brightenings simultaneous to magnetic flux cancellations. This is interpreted in terms of magnetic reconnection events. Finally, a electron density study of six coronal bright points produces values of ≈1.6×10 9 cm -3 , closer to active region plasma than to quiet Sun. The analysis of a large coronal loop (half length of 72 Mm) introduces the discussion on the prospects of future plasma diagnostics of BPs with forthcoming solar missions.

Integration of SMAP and SMOS L-Band Observations

NASA Technical Reports Server (NTRS)

Bindlish, Rajat; Jackson, Thomas J.; Chan, Steven; Colliander, Andreas; Kerr, Yaan

2017-01-01

Soil Moisture Active Passive (SMAP) mission and the ESA Soil Moisture and Ocean Salinity (SMOS) missions provide brightness temperature and soil moisture estimates every 2-3 days. SMAP brightness temperature observations were compared with SMOS observations at 40 Degrees incidence angle. The brightness temperatures from the two missions are not consistent and have a bias of about 2.7K over land with respect to each other. SMAP and SMOS missions use different retrieval algorithms and ancillary datasets which result in further inconsistencies between the soil moisture products. The reprocessed constant-angle SMOS brightness temperatures were used in the SMAP soil moisture retrieval algorithm to develop a consistent multi-satellite product. The integrated product will have an increased global revisit frequency (1 day) and period of record that would be unattainable by either one of the satellites alone. Results from the development and validation of the integrated product will be presented.

Dark goggles and bright light improve circadian rhythm adaptation to night-shift work.

PubMed

Eastman, C I; Stewart, K T; Mahoney, M P; Liu, L; Fogg, L F

1994-09-01

We compared the contributions of bright light during the night shift and dark goggles during daylight for phase shifting the circadian rhythm of temperature to realign with a 12-hour shift of sleep. After 10 baseline days there were 8 night-work/day-sleep days. Temperature was continuously recorded from 50 subjects. There were four groups in a 2 x 2 design: light (bright, dim), goggles (yes, no). Subjects were exposed to bright light (about 5,000 lux) for 6 hours on the first 2 night shifts. Dim light was < 500 lux. Both bright light and goggles were significant factors for producing circadian rhythm phase shifts. The combination of bright light plus goggles was the most effective, whereas the combination of dim light and no goggles was the least effective. The temperature rhythm either phase advanced or phase delayed when it aligned with daytime sleep. However, when subjects did not have goggles only phase advances occurred. Goggles were necessary for producing phase delays. The most likely explanation is that daylight during the travel-home window after a night shift inhibits phase-delay shifts, and goggles can prevent this inhibition. Larger temperature-rhythm phase shifts were associated with better subjective daytime sleep, less subjective fatigue and better mood.

Estimating effective particle size of tropical deep convective clouds with a look-up table method using satellite measurements of brightness temperature differences

NASA Astrophysics Data System (ADS)

Hong, Gang; Minnis, Patrick; Doelling, David; Ayers, J. Kirk; Sun-Mack, Szedung

2012-03-01

A method for estimating effective ice particle radius Re at the tops of tropical deep convective clouds (DCC) is developed on the basis of precomputed look-up tables (LUTs) of brightness temperature differences (BTDs) between the 3.7 and 11.0 μm bands. A combination of discrete ordinates radiative transfer and correlated k distribution programs, which account for the multiple scattering and monochromatic molecular absorption in the atmosphere, is utilized to compute the LUTs as functions of solar zenith angle, satellite zenith angle, relative azimuth angle, Re, cloud top temperature (CTT), and cloud visible optical thickness τ. The LUT-estimated DCC Re agrees well with the cloud retrievals of the Moderate Resolution Imaging Spectroradiometer (MODIS) for the NASA Clouds and Earth's Radiant Energy System with a correlation coefficient of 0.988 and differences of less than 10%. The LUTs are applied to 1 year of measurements taken from MODIS aboard Aqua in 2007 to estimate DCC Re and are compared to a similar quantity from CloudSat over the region bounded by 140°E, 180°E, 0°N, and 20°N in the Western Pacific Warm Pool. The estimated DCC Re values are mainly concentrated in the range of 25-45 μm and decrease with CTT. Matching the LUT-estimated Re with ice cloud Re retrieved by CloudSat, it is found that the ice cloud τ values from DCC top to the vertical location where LUT-estimated Re is located at the CloudSat-retrieved Re profile are mostly less than 2.5 with a mean value of about 1.3. Changes in the DCC τ can result in differences of less than 10% for Re estimated from LUTs. The LUTs of 0.65 μm bidirectional reflectance distribution function (BRDF) are built as functions of viewing geometry and column amount of ozone above upper troposphere. The 0.65 μm BRDF can eliminate some noncore portions of the DCCs detected using only 11 μm brightness temperature thresholds, which result in a mean difference of only 0.6 μm for DCC Re estimated from BTD LUTs.

Assimilation of Global Radar Backscatter and Radiometer Brightness Temperature Observations to Improve Soil Moisture and Land Evaporation Estimates

NASA Technical Reports Server (NTRS)

Lievens, H.; Martens, B.; Verhoest, N. E. C.; Hahn, S.; Reichle, R. H.; Miralles, D. G.

2017-01-01

Active radar backscatter (s?) observations from the Advanced Scatterometer (ASCAT) and passive radiometer brightness temperature (TB) observations from the Soil Moisture Ocean Salinity (SMOS) mission are assimilated either individually or jointly into the Global Land Evaporation Amsterdam Model (GLEAM) to improve its simulations of soil moisture and land evaporation. To enable s? and TB assimilation, GLEAM is coupled to the Water Cloud Model and the L-band Microwave Emission from the Biosphere (L-MEB) model. The innovations, i.e. differences between observations and simulations, are mapped onto the model soil moisture states through an Ensemble Kalman Filter. The validation of surface (0-10 cm) soil moisture simulations over the period 2010-2014 against in situ measurements from the International Soil Moisture Network (ISMN) shows that assimilating s? or TB alone improves the average correlation of seasonal anomalies (Ran) from 0.514 to 0.547 and 0.548, respectively. The joint assimilation further improves Ran to 0.559. Associated enhancements in daily evaporative flux simulations by GLEAM are validated based on measurements from 22 FLUXNET stations. Again, the singular assimilation improves Ran from 0.502 to 0.536 and 0.533, respectively for s? and TB, whereas the best performance is observed for the joint assimilation (Ran = 0.546). These results demonstrate the complementary value of assimilating radar backscatter observations together with brightness temperatures for improving estimates of hydrological variables, as their joint assimilation outperforms the assimilation of each observation type separately.

Quantifying photometric observing conditions on Paranal using an IR camera

NASA Astrophysics Data System (ADS)

Kerber, Florian; Querel, Richard R.; Hanuschik, Reinhard

2014-08-01

A Low Humidity and Temperature Profiling (LHATPRO) microwave radiometer, manufactured by Radiometer Physics GmbH (RPG), is used to monitor sky conditions over ESO's Paranal observatory in support of VLT science operations. In addition to measuring precipitable water vapour (PWV) the instrument also contains an IR camera measuring sky brightness temperature at 10.5 μm. Due to its extended operating range down to -100 °C it is capable of detecting very cold and very thin, even sub-visual, cirrus clouds. We present a set of instrument flux calibration values as compared with a detrended fluctuation analysis (DFA) of the IR camera zenith-looking sky brightness data measured above Paranal taken over the past two years. We show that it is possible to quantify photometric observing conditions and that the method is highly sensitive to the presence of even very thin clouds but robust against variations of sky brightness caused by effects other than clouds such as variations of precipitable water vapour. Hence it can be used to determine photometric conditions for science operations. About 60 % of nights are free of clouds on Paranal. More work will be required to classify the clouds using this technique. For the future this approach might become part of VLT science operations for evaluating nightly sky conditions.

Optimum Image Formation for Spaceborne Microwave Radiometer Products.

PubMed

Long, David G; Brodzik, Mary J

2016-05-01

This paper considers some of the issues of radiometer brightness image formation and reconstruction for use in the NASA-sponsored Calibrated Passive Microwave Daily Equal-Area Scalable Earth Grid 2.0 Brightness Temperature Earth System Data Record project, which generates a multisensor multidecadal time series of high-resolution radiometer products designed to support climate studies. Two primary reconstruction algorithms are considered: the Backus-Gilbert approach and the radiometer form of the scatterometer image reconstruction (SIR) algorithm. These are compared with the conventional drop-in-the-bucket (DIB) gridded image formation approach. Tradeoff study results for the various algorithm options are presented to select optimum values for the grid resolution, the number of SIR iterations, and the BG gamma parameter. We find that although both approaches are effective in improving the spatial resolution of the surface brightness temperature estimates compared to DIB, SIR requires significantly less computation. The sensitivity of the reconstruction to the accuracy of the measurement spatial response function (MRF) is explored. The partial reconstruction of the methods can tolerate errors in the description of the sensor measurement response function, which simplifies the processing of historic sensor data for which the MRF is not known as well as modern sensors. Simulation tradeoff results are confirmed using actual data.

Extreme Magnetosphere-Ionosphere Coupling at the Plasmapause: a - In-A Bright SAR Arc

NASA Astrophysics Data System (ADS)

Baumgardner, J.; Wroten, J.; Semeter, J.; Mendillo, M.; Kozyra, J.

2007-05-01

Heat conduction from the ring current - plasmapause interaction region generates high electron temperature within the ionosphere that drive stable auroral red (SAR) arc emission at 6300 A. On the night of 29 October 1991, a SAR arc was observed using an all-sky imager and meridional imaging spectrograph at Millstone Hill. At xxxx UT, the SAR arc was south of Millstone at approximate L = 2 and reached emission levels of 13,000 rayleighs (R). Over two solar cycle of imaging observations have been made at Millstone Hill, and SAR arc brightness levels (excluding this event) averaged ~ 500 R. Simultaneous observations using the incoherent scatter radar (ISR), a DMSP satellite pass, the MSIS neutral atmosphere and SAR arc modeling using the Rees and Roble formalism succeeded in simulations of the observed emission. The reason for the unusual brightness was not the extreme temperatures achieved (and therefore heat conduction input), but the fact that the end of the plasmapause field line where the elevated Te values were measured did not occur in the ionospheric trough, but equatorward of it, thereby having far more ambient electrons to heat and subsequently collide with atomic oxygen. This unusual spatial geometry probably resulted from unusual convection patterns early in a superstorm scenario.

Availability of color calibration for consistent color display in medical images and optimization of reference brightness for clinical use

NASA Astrophysics Data System (ADS)

Iwai, Daiki; Suganami, Haruka; Hosoba, Minoru; Ohno, Kazuko; Emoto, Yutaka; Tabata, Yoshito; Matsui, Norihisa

2013-03-01

Color image consistency has not been accomplished yet except the Digital Imaging and Communication in Medicine (DICOM) Supplement 100 for implementing a color reproduction pipeline and device independent color spaces. Thus, most healthcare enterprises could not check monitor degradation routinely. To ensure color consistency in medical color imaging, monitor color calibration should be introduced. Using simple color calibration device . chromaticity of colors including typical color (Red, Green, Blue, Green and White) are measured as device independent profile connection space value called u'v' before and after calibration. In addition, clinical color images are displayed and visual differences are observed. In color calibration, monitor brightness level has to be set to quite lower value 80 cd/m2 according to sRGB standard. As Maximum brightness of most color monitors available currently for medical use have much higher brightness than 80 cd/m2, it is not seemed to be appropriate to use 80 cd/m2 level for calibration. Therefore, we propose that new brightness standard should be introduced while maintaining the color representation in clinical use. To evaluate effects of brightness to chromaticity experimentally, brightness level is changed in two monitors from 80 to 270cd/m2 and chromaticity value are compared with each brightness levels. As a result, there are no significant differences in chromaticity diagram when brightness levels are changed. In conclusion, chromaticity is close to theoretical value after color calibration. Moreover, chromaticity isn't moved when brightness is changed. The results indicate optimized reference brightness level for clinical use could be set at high brightness in current monitors .

Bright light and thermoregulatory responses to exercise.

PubMed

Atkinson, G; Barr, D; Chester, N; Drust, B; Gregson, W; Reilly, T; Waterhouse, J

2008-03-01

The thermoregulatory responses to morning exercise after exposure to different schedules of bright light were examined. At 07:00 h, six males ran on two occasions in an environmental chamber (temperature = 31.4 +/- 1.0 degrees C, humidity = 66 +/- 6 %) for 40 min at 60 % of maximal oxygen uptake. Participants were exposed to bright light (10,000 lux) either between 22:00 - 23:00 h (BT (low)) or 06:00 - 07:00 h (BT (high)). Otherwise, participants remained in dim light (< 50 lux). It was hypothesized that BT (low) attenuates core temperature during morning exercise via the phase-delaying properties of evening bright light and by avoiding bright light in the morning. Evening bright light in BT (low) suppressed (p = 0.037) the increase in melatonin compared to dim light (1.1 +/- 11.4 vs. 15.2 +/- 19.7 pg x ml (-1)) and delayed (p = 0.034) the core temperature minimum by 1.46 +/- 1.24 h. Core temperature was 0.20 +/- 0.17 degrees C lower in BT (low) compared to BT (high) during the hour before exercise (p = 0.036), with evidence (p = 0.075) that this difference was maintained during exercise. Conversely, mean skin temperature was 1.0 +/- 1.7 degrees C higher during the first 10 min of exercise in BT (low) than in BT (high) (p = 0.030). There was evidence that the increase in perceived exertion was attenuated in BT (low) (p = 0.056). A chronobiologically-based light schedule can lower core temperature before and during morning exercise in hot conditions.

The Peculiar Solar Minimum 23/24 Revealed by the Microwave Butterfly Diagram

NASA Technical Reports Server (NTRS)

Gopalswamy, Natchimuthuk; Yashiro, Seiji; Makela, Pertti; Shibasaki, Kiyoto; Hathaway, David

2010-01-01

The diminished polar magnetic field strength during the minimum between cycles 23 and 24 is also reflected in the thermal radio emission originating from the polar chromosphere. During solar minima, the polar corona has extended coronal holes containing intense unipolar flux. In microwave images, the coronal holes appear bright, with a brightness enhancement of 500 to 2000 K with respect to the quiet Sun. The brightness enhancement corresponds to the upper chromosphere, where the plasma temperature is approx.10000 K. We constructed a microwave butterfly diagram using the synoptic images obtained by the Nobeyama radioheliograph (NoRH) showing the evolution of the polar and low latitude brightness temperature. While the polar brightness reveals the chromospheric conditions, the low latitude brightness is attributed to active regions in the corona. When we compared the microwave butterfly diagram with the magnetic butterfly diagram, we found a good correlation between the microwave brightness enhancement and the polar field strength. The microwave butterfly diagram covers part of solar cycle 22, whole of cycle 23, and part of cycle 24, thus enabling comparison between the cycle 23/24 and cycle 22/23 minima. The microwave brightness during the cycle 23/24 minimum was found to be lower than that during the cycle 22/23 minimum by approx.250 K. The reduced brightness temperature is consistent with the reduced polar field strength during the cycle 23/24 minimum seen in the magnetic butterfly diagram. We suggest that the microwave brightness at the solar poles is a good indicator of the speed of the solar wind sampled by Ulysses at high latitudes..

Inferring Land Surface Model Parameters for the Assimilation of Satellite-Based L-Band Brightness Temperature Observations into a Soil Moisture Analysis System

NASA Technical Reports Server (NTRS)

Reichle, Rolf H.; De Lannoy, Gabrielle J. M.

2012-01-01

The Soil Moisture and Ocean Salinity (SMOS) satellite mission provides global measurements of L-band brightness temperatures at horizontal and vertical polarization and a variety of incidence angles that are sensitive to moisture and temperature conditions in the top few centimeters of the soil. These L-band observations can therefore be assimilated into a land surface model to obtain surface and root zone soil moisture estimates. As part of the observation operator, such an assimilation system requires a radiative transfer model (RTM) that converts geophysical fields (including soil moisture and soil temperature) into modeled L-band brightness temperatures. At the global scale, the RTM parameters and the climatological soil moisture conditions are still poorly known. Using look-up tables from the literature to estimate the RTM parameters usually results in modeled L-band brightness temperatures that are strongly biased against the SMOS observations, with biases varying regionally and seasonally. Such biases must be addressed within the land data assimilation system. In this presentation, the estimation of the RTM parameters is discussed for the NASA GEOS-5 land data assimilation system, which is based on the ensemble Kalman filter (EnKF) and the Catchment land surface model. In the GEOS-5 land data assimilation system, soil moisture and brightness temperature biases are addressed in three stages. First, the global soil properties and soil hydraulic parameters that are used in the Catchment model were revised to minimize the bias in the modeled soil moisture, as verified against available in situ soil moisture measurements. Second, key parameters of the "tau-omega" RTM were calibrated prior to data assimilation using an objective function that minimizes the climatological differences between the modeled L-band brightness temperatures and the corresponding SMOS observations. Calibrated parameters include soil roughness parameters, vegetation structure parameters, and the single scattering albedo. After this climatological calibration, the modeling system can provide L-band brightness temperatures with a global mean absolute bias of less than 10K against SMOS observations, across multiple incidence angles and for horizontal and vertical polarization. Third, seasonal and regional variations in the residual biases are addressed by estimating the vegetation optical depth through state augmentation during the assimilation of the L-band brightness temperatures. This strategy, tested here with SMOS data, is part of the baseline approach for the Level 4 Surface and Root Zone Soil Moisture data product from the planned Soil Moisture Active Passive (SMAP) satellite mission.

Brightness field distributions of microlens arrays using micro molding.

PubMed

Cheng, Hsin-Chung; Huang, Chiung-Fang; Lin, Yi; Shen, Yung-Kang

2010-12-20

This study describes the brightness field distributions of microlens arrays fabricated by micro injection molding (μIM) and micro injection-compression molding (μICM). The process for fabricating microlens arrays used room-temperature imprint lithography, photoresist reflow, electroforming, μIM, μICM, and optical properties measurement. Analytical results indicate that the brightness field distribution of the molded microlens arrays generated by μICM is better than those made using μIM. Our results further demonstrate that mold temperature is the most important processing parameter for brightness field distribution of molded microlens arrays made by μIM or μICM.

Anisotropy of thermal infrared remote sensing over urban areas : assessment from airborne data and modeling approach

NASA Astrophysics Data System (ADS)

Hénon, A.; Mestayer, P.; Lagouarde, J.-P.; Lee, J. H.

2009-09-01

Due to the morphological complexity of the urban canopy and to the variability in thermal properties of the building materials, the heterogeneity of the surface temperatures generates a strong directional anisotropy of thermal infrared remote sensing signal. Thermal infrared (TIR) data obtained with an airborne FLIR camera over Toulouse (France) city centre during the CAPITOUL experiment (feb. 2004 - feb. 2005) show brightness temperature anisotropies ranging from 3 °C by night to more than 10 °C by sunny days. These data have been analyzed in view of developing a simple approach to correct TIR satellite remote sensing from the canopy-generated anisotropy, and to further evaluate the sensible heat fluxes. The methodology is based on the identification of 6 different classes of surfaces: roofs, walls and grounds, sunlit or shaded, respectively. The thermo-radiative model SOLENE is used to simulate, with a 1 m resolution computational grid, the surface temperatures of an 18000 m² urban district, in the same meteorological conditions as during the observation. A pixel-by-pixel comparison with both hand-held temperature measurements and airborne camera images allows to assess the actual values of the radiative and thermal parameters of the scene elements. SOLENE is then used to simulate a generic street-canyon geometry, whose sizes average the morphological parameters of the actual streets in the district, for 18 different geographical orientations. The simulated temperatures are then integrated for different viewing positions, taking into account shadowing and masking, and directional temperatures are determined for the 6 surface classes. The class ratios in each viewing direction are derived from images of the district generated by using the POVRAY software, and used to weigh the temperatures of each class and to compute the resulting directional brightness temperature at the district scale for a given sun direction (time in the day). Simulated and measured anisotropies are finally compared for several flights over Toulouse in summer and winter. An inverse method is further proposed to obtain the surface temperatures from the directional brightness temperatures, which may be extended to deduce the sensible heat fluxes separately from the buildings and from the ground.

Effect of bright light at night on core temperature, subjective alertness and performance as a function of exposure time.

PubMed

Foret, J; Daurat, A; Tirilly, G

1998-01-01

This simulated night shift study measured the effects of moderate bright light (a 4-hour pulse starting at 2000 or 0400) during the exposure night and subsequent night (dim light). Eight young males remained confined with little physical activity to a laboratory in groups of 4. After a night of reference, they were active for 24 hours; then after a morning recovery sleep, they were active again for 16 hours. Continuously measured rectal temperature proved to be immediately sensitive to 4 hours of bright light, particularly when given at the end of the night. Self-assessed alertness and also performance on a task with a high requirement for short-term memory were improved by the exposure to bright light. During the subsequent night the subjects were exposed only to dim light. Core temperature, subjective alertness and performance continued to show a time course depending on the preceding bright light exposure. Probably because evening exposure to bright light and morning sleep both had a phase-delaying effect, the effects on the circadian pacemaker were more pronounced. Thus, for practical applications in long night shifts, bright light can be considered to improve mood and alertness immediately but the possibility of modifying the circadian "clock" during subsequent nights should be taken into consideration, in particular after exposure to bright light in the evening.

Self-deflection of a bright soliton in a separate bright-dark spatial soliton pair based on a higher-order space charge field

NASA Astrophysics Data System (ADS)

Liu, Jin-Song; Hao, Zhong-Hua

2003-10-01

The self-deflection of a bright solitary beam can be controlled by a dark solitary beam via a parametric coupling effect between the bright and dark solitary beams in a separate bright-dark spatial soliton pair supported by an unbiased series photorefractive crystal circuit. The spatial shift of the bright solitary beam centre as a function of the input intensity of the dark solitary beam (hat rho) is investigated by taking into account the higher-order space charge field in the dynamics of the bright solitary beam via both numerical and perturbation methods under steady-state conditions. The deflection amount (Deltas0), defined as the value of the spatial shift at the output surface of the crystal, is a monotonic and nonlinear function of hat rho. When hat rho is weak or strong enough, Deltas0 is, in fact, unchanged with hat rho, whereas Deltas0 increases or decreases monotonically with hat rho in a middle range of hat rho. The corresponding variation range (deltas) depends strongly on the value of the input intensity of the bright solitary beam (r). There are some peak and valley values in the curve of deltas versus r under some conditions. When hat rho increases, the bright solitary beam can scan toward both the direction same as and opposite to the crystal's c-axis. Whether the direction is the same as or opposite to the c-axis depends on the parameter values and configuration of the crystal circuit, as well as the value of r. Some potential applications are discussed.

35 GHz Measurements of CO2 Crystals for Simulating Observations of the Martian Polar Caps

NASA Technical Reports Server (NTRS)

Foster, J. L.; Chang, A. T. C.; Hall, D. K.; Tait, A. B.; Barton, J. S.

1998-01-01

In order to learn more about the Martian polar caps, it is important to compare and contrast the behavior of both frozen H2O and CO2 in different parts of the electromagnetic spectrum. Relatively little attention has been given, thus far, to observing the thermal microwave part of the spectrum. In this experiment, passive microwave radiation emanating from within a 33 cm snowpack was measured with a 35 GHz hand-held radiometer, and in addition to the natural snow measurements, the radiometer was used to measure the microwave emission and scattering from layers of manufactured CO2 (dry ice). A 1 m x 2 m plate of aluminum sheet metal was positioned beneath the natural snow so that microwave emissions from the underlying soil layers would be minimized. Compared to the natural snow crystals, results for the dry ice layers exhibit lower' microwave brightness temperatures for similar thicknesses, regardless of the incidence angle of the radiometer. For example, at 50 degree H (horizontal polarization) and with a covering of 21 cm of snow and 18 cm of dry ice, the brightness temperatures were 150 K and 76 K, respectively. When the snow depth was 33 cm, the brightness temperature was 144 K, and when the total thickness of the dry ice was 27 cm, the brightness temperature was 86 K. The lower brightness temperatures are due to a combination of the lower physical temperature and the larger crystal sizes of the commercial CO2 Crystals compared to the snow crystals. As the crystal size approaches the size of the microwave wavelength, it scatters microwave radiation more effectively, thus lowering the brightness temperature. The dry ice crystals in this experiment were about an order of magnitude larger than the snow crystals and three orders of magnitude larger than the CO2 Crystals produced in the cold stage of a scanning electron microscope. Spreading soil, approximately 2 mm in thickness, on the dry ice appeared to have no effect on the brightness temperatures.

High-resolution maps of Jupiter at five microns.

NASA Technical Reports Server (NTRS)

Keay, C. S. L.; Low, F. J.; Rieke, G. H.; Minton, R. B.

1973-01-01

The distribution of 5-micron radiation, emitted from a large number of discrete sources from Jupiter, was observed during the 1972 apparition. These sources are less bright than those observed by Westphal (1969). At least 50 discrete sources having brightness temperatures exceeding 227 K were revealed which were mainly located within three narrow-latitude bands. Strong correlation exists between the 5-micron brightness temperatures of Jovian features and their colors as recorded photographically.

Investigations of the emittance and brightness of ion beams from an electron beam ion source of the Dresden EBIS type.

PubMed

Silze, Alexandra; Ritter, Erik; Zschornack, Günter; Schwan, Andreas; Ullmann, Falk

2010-02-01

We have characterized ion beams extracted from the Dresden EBIS-A, a compact room-temperature electron beam ion source (EBIS) with a permanent magnet system for electron beam compression, using a pepper-pot emittance meter. The EBIS-A is the precursor to the Dresden EBIS-SC in which the permanent magnets have been replaced by superconducting solenoids for the use of the source in high-ion-current applications such as heavy-ion cancer therapy. Beam emittance and brightness values were calculated from data sets acquired for a variety of source parameters, in leaky as well as pulsed ion extraction mode. With box shaped pulses of C(4+) ions at an energy of 39 keV root mean square emittances of 1-4 mm mrad and a brightness of 10 nA mm(-2) mrad(-2) were achieved. The results meet the expectations for high quality ion beams generated by an electron beam ion source.

Starspots and Activity of the Flare Star GJ 1243

NASA Astrophysics Data System (ADS)

Savanov, I. S.; Dmitrienko, E. S.

2018-04-01

The photometric variability of the uniqueMdwarf flare star GJ 1243 (KIC 9726699) is investigated using the most complete set of observationalmaterial obtained with the Kepler Space Telescope. The analysis is based on 49 487 individual brightness measurements obtained during an interval of 1460 days (nearly four years). The periodicity of the brightness variations with the period P phot = 0.59261 ± 0.00060d is confirmed. The temperature inhomogeneities on the stellar surface reconstructed from the light curve are used to drive maps of these surface-temperature inhomogeneities (of the filling factor f). The resulting maps are used to determine the positions of active regions. Analysis of the surface-temperature maps for GJ 1243 led to the conclusion that the positions of spots on the stellar surface displayed appreciable evolution during the analyzed time interval. The maximum value for the lower limit on the differentialrotation parameter ΔΩ is 0.0022 rad/day. This more accurate estimate of ΔΩ is lower than the values presented earlier by Davenport et al. [1] (0.0058 and 0.0036 rad/day), due to the more accurate account of variations in the positions of the most active longitude in the current study. However, the differentialrotation estimate obtained in [1] using a method based on fitting the evolution of spots using twodimensional Gaussian functions essentially coincides with the new estimate presented here. The fractional area of the total spotted surface S of the star during the observing interval considered varied from 7 to 2%. The amplitude of the brightness variability of the star slowly decreased, varying in the range 1.6-0.5%. Overall, the position of GJ 1243 in spottedness-age, spottedness-rotation period, and spottedness-Rossby number diagrams agrees very well with the general character of the dependences displayed in earlier studies of M dwarfs.

Variations in West Antarctic Ice Front and Passive Microwave Brightness Temperature for 8 Years Duration in 2000s

NASA Astrophysics Data System (ADS)

Kim, J.; Yu, J.; Wang, L.; Liu, H.

2017-12-01

Changes in Antarctic ice sheet are caused by various reasons such as changes in Holocene climate, precipitation, and ocean temperature. Such issues of changes in ice sheet has been mainly focused on the Antarctic peninsula, and it is known that ice retreat of the area is caused by changes in atmospheric and ocean temperatures. For the case of West Antarctica, ice front change research is relatively rarely conducted except the Pine island glacier area. This study has monitored ice front changes of West Antarctica and compared the patterns with the changes in brightness temperature based on remote sensing techniques. We used 2000 Radarsat-1 and 2008 Rasarsat-2 SAR data to delineate coastlines of whole West Antarctica based on the locally thresholding adaptive algorithm. The delineated coast lines are analyzed to figure out ice front change patterns between the duration. The variations in brightness temperature for the same duration are calculated based on Defense Meteorological Satellite Program (DMSP)'s Special Sensor Microwave/Images-Special Sensor Microwave Imager/Sounder (SSM/I-SSMIS) passive microwave data. The results show ice front of West Antarctica shows advancing trend except the pine island glacier area. The brightness temperature had decreasing trend during the study period. It infers that changes in ice front and brightness temperature of West Antarctica have considerable relationships. It is expected that a long term monitoring of the relationship would contribute understanding ice dynamics of West Antarctica significantly.

Passive microwave studies of snowpack properties. [Walden and Steamboat Spring, Colorado

NASA Technical Reports Server (NTRS)

Hall, D. K.; Chang, A. T. C.; Foster, J. L.; Rango, A.; Schmugge, T.

1978-01-01

Microwave brightness temperatures were measured for the snowpacks at Walden and Steamboat Springs, Colorado during 1976 and 1977 aircraft experiments. Variations in measured brightness temperatures are attributed to snow grain and crystal sizes, liquid water content, and snowpack temperature. Results demonstrate that shorter wavelength radiation is scattered more strongly than longer wavelength radiation.

The effect of precipitation on measuring sea surface salinity from space

NASA Astrophysics Data System (ADS)

Jin, Xuchen; Pan, Delu; He, Xianqiang; Wang, Difeng; Zhu, Qiankun; Gong, Fang

2017-10-01

The sea surface salinity (SSS) can be measured from space by using L-band (1.4 GHz) microwave radiometers. The L-band has been chosen for its sensitivity of brightness temperature to the change of salinity. However, SSS remote sensing is still challenging due to the low sensitivity of brightness temperature to SSS variation: for the vertical polarization, the sensitivity is about 0.4 to 0.8 K/psu with different incident angles and sea surface temperature; for horizontal polarization, the sensitivity is about 0.2 to 0.6 K/psu. It means that we have to make radiometric measurements with accuracy better than 1K even for the best sensitivity of brightness temperature to SSS. Therefore, in order to retrieve SSS, the measured brightness temperature at the top of atmosphere (TOA) needs to be corrected for many sources of error. One main geophysical source of error comes from atmosphere. Currently, the atmospheric effect at L-band is usually corrected by absorption and emission model, which estimate the radiation absorbed and emitted by atmosphere. However, the radiation scattered by precipitation is neglected in absorption and emission models, which might be significant under heavy precipitation. In this paper, a vector radiative transfer model for coupled atmosphere and ocean systems with a rough surface is developed to simulate the brightness temperature at the TOA under different precipitations. The model is based on the adding-doubling method, which includes oceanic emission and reflection, atmospheric absorption and scattering. For the ocean system with a rough surface, an empirical emission model established by Gabarro and the isotropic Cox-Munk wave model considering shadowing effect are used to simulate the emission and reflection of sea surface. For the atmospheric attenuation, it is divided into two parts: For the rain layer, a Marshall-Palmer distribution is used and the scattering properties of the hydrometeors are calculated by Mie theory (the scattering hydrometeors are assumed to be spherical). For the other atmosphere layers, which are assumed to be clear sky, Liebe's millimeter wave propagation model (MPM93) is used to calculate the absorption coefficients of oxygen, water vapor, and cloud droplets. To simulate the change of brightness temperature caused by different rain rate (0-50 mm/h), we assume a 26-layer precipitation structure corresponding to NCEP FNL data. Our radiative transfer simulations showed that the brightness temperature at TOA can be influenced significantly by the heavy precipitation, the results indicate that the atmospheric attenuation of L-band at incidence angle of 42.5° should be a positive bias, and when rain rate rise up to 50 mm/h, the brightness temperature increases are close to 0.6 K and 0.8 K for horizontally and vertically polarized brightness temperature, respectively. Thus, in the case of heavy precipitation, the current absorption and emission model is not accurate enough to correct atmospheric effect, and a radiative transfer model which considers the effect of radiation scattering should be used.

Site testing in Colombia : Identification of the least-worst places for optical telescopes

NASA Astrophysics Data System (ADS)

Pinzón, G.

2017-07-01

With the aim of identifying a set of least-worst sites for astronomical observations in Colombia we used a novel algorithm for the computation of the number of clear nights over an extended region covering Colombia and the western part of Venezuela. This algorithm compares the brightness temperatures of five years of GOES images with reference temperature values obtained from long-term records of monthly temperatures at ground and at heights of 8, 9 and 10 kilometers. Our predictions were validated with cloud cover information from the log-books of the Observatorio Nacional de Llano del Hato in Venezuela. Short and sporadic expeditions to four of those sites were also done from 2013 to 2015 in order to conduct measurements in-situ of temperature and humidity along the night, seeing, sky brightness and atmospheric extinction using basic instrumentation. The final conclusions have been derived solely on the basis of the actually visited sites. It was found that at Cañón del río Nevado the Seeing during the nights was more stable with rms=0.59'' and then a suitable and extended region (of almost 30 km) for the location of optical telescopes aimed to enhance astronomy research and outreach in the country.

A study of cooling flows in poor clusters of galaxies

NASA Technical Reports Server (NTRS)

Kriss, Gerard A.; Dillingham, Stephen

1995-01-01

We observed three poor clusters with central dominant galaxies (AWM 4, MKW 4, and MKW 3's) using the Position Sensitive Proportional Counter on the ROSAT X-ray satellite. The images reveal smooth, symmetrical X-ray emission filling the cluster with a sharp peak on each central galaxy. The cluster surface brightness profiles can be decomposed using superposed King models for the central galaxy and the intracluster medium. The King model parameters for the cluster portions are consistent with previous observations of these clusters. The newly measured King model parameters for the central galaxies are typical of the X-ray surface brightness distributions of isolated elliptical galaxies. Spatially resolved temperature measurements in annular rings throughout the clusters show a nearly isothermal profile. Temperatures are consistent with previously measured values, but are much better determined. There is no significant drop in temperature noted in the innermost bins where cooling flows are likely to be present, nor is any excess absorption by cold gas required. All cold gas columns are consistent with galactic foreground absorption. We derive mass profiles for the clusters assuming both isothermal temperature profiles and cooling flow models with constant mass flow rates. Our results are consistent with previous Einstein IPC observations by Kriss, Cioffi, & Canizares, but extend the mass profiles out to 1 Mpc in these poor clusters.

Surface-induced brightness temperature variations and their effects on detecting thin cirrus clouds using IR emission channels in the 8-12 microns region

NASA Technical Reports Server (NTRS)

Gao, Bo-Cai; Wiscombe, W. J.

1994-01-01

A method for detecting cirrus clouds in terms of brightness temperature differences between narrowbands at 8, 11, and 12 microns has been proposed by Ackerman et al. In this method, the variation of emissivity with wavelength for different surface targets was not taken into consideration. Based on state-of-the-art laboratory measurements of reflectance spectra of terrestrial materials by Salisbury and D'Aria, it is found that the brightness temperature differences between the 8- and 11-microns bands for soils, rocks, and minerals, and dry vegetation can vary between approximately -8 and +8 K due solely to surface emissivity variations. The large brightness temperature differences are sufficient to cause false detection of cirrus clouds from remote sensing data acquired over certain surface targets using the 8-11-12-microns method directly. It is suggested that the 8-11-12-microns method should be improved to include the surface emissivity effects. In addition, it is recommended that in the future the variation of surface emissivity with wavelength should be taken into account in algorithms for retrieving surface temperatures and low-level atmospheric temperature and water vapor profiles.

A search for p-mode oscillations of Jupiter - Serendipitous observations of nonacoustic thermal wave structure

NASA Technical Reports Server (NTRS)

Deming, Drake; Mumma, Michael J.; Espenak, Fred; Jennings, Donald E.; Kostiuk, Theodor; Wiedemann, Gunter

1989-01-01

Frequencies for the p-mode oscillations of Jupiter have been determined, and infrared brightness temperature fluctuations are used to search for the modes. Measurements of the infrared intensity of the Jovian disk were obtained in a broad bandwidth using a 20-element linear array. No p-mode oscillations were observed at the 0.07-K level in the 8-13-micron brightness temperature. The results suggest that Jovian p modes are not likely to have observable amplitudes. A prominent nonacoustic wave-like structure in the 8-13-micron brightness temperature is found both at 20 deg N and at the equator.

Solar Prominence Modelling and Plasma Diagnostics at ALMA Wavelengths

NASA Astrophysics Data System (ADS)

Rodger, Andrew; Labrosse, Nicolas

2017-09-01

Our aim is to test potential solar prominence plasma diagnostics as obtained with the new solar capability of the Atacama Large Millimeter/submillimeter Array (ALMA). We investigate the thermal and plasma diagnostic potential of ALMA for solar prominences through the computation of brightness temperatures at ALMA wavelengths. The brightness temperature, for a chosen line of sight, is calculated using the densities of electrons, hydrogen, and helium obtained from a radiative transfer code under non-local thermodynamic equilibrium (non-LTE) conditions, as well as the input internal parameters of the prominence model in consideration. Two distinct sets of prominence models were used: isothermal-isobaric fine-structure threads, and large-scale structures with radially increasing temperature distributions representing the prominence-to-corona transition region. We compute brightness temperatures over the range of wavelengths in which ALMA is capable of observing (0.32 - 9.6 mm), however, we particularly focus on the bands available to solar observers in ALMA cycles 4 and 5, namely 2.6 - 3.6 mm (Band 3) and 1.1 - 1.4 mm (Band 6). We show how the computed brightness temperatures and optical thicknesses in our models vary with the plasma parameters (temperature and pressure) and the wavelength of observation. We then study how ALMA observables such as the ratio of brightness temperatures at two frequencies can be used to estimate the optical thickness and the emission measure for isothermal and non-isothermal prominences. From this study we conclude that for both sets of models, ALMA presents a strong thermal diagnostic capability, provided that the interpretation of observations is supported by the use of non-LTE simulation results.

Snow stratigraphic heterogeneity within ground-based passive microwave radiometer footprints: implications for emission modelling

NASA Astrophysics Data System (ADS)

Sandells, M.; Rutter, N.; Derksen, C.; Langlois, A.; Lemmetyinen, J.; Montpetit, B.; Pulliainen, J. T.; Royer, A.; Toose, P.

2012-12-01

Remote sensing of snow mass remains a challenging area of research. Scattering of electromagnetic radiation is sensitive to snow mass, but is also affected by contrasts in the dielectric properties of the snow. Although the argument that errors from simple algorithms average out at large scales has been used to justify current retrieval methods, it is not obvious why this should be the case. This hypothesis needs to be tested more rigorously. A ground-based field experiment was carried out to assess the impact of sub-footprint snow heterogeneity on microwave brightness temperature, in Churchill, Canada in winter in early 2010. Passive microwave measurements of snow were made using sled-mounted radiometers at 75cm intervals over a 5m transect. Measurements were made at horizontal and vertical polarizations at frequencies of 19 and 37 GHz. Snow beneath the radiometer footprints was subsequently excavated, creating a snow trench wall along the centrepoints of adjacent footprints. The trench wall was carefully smoothed and photographed with a near-infrared camera in order to determine the positions of stratigraphic snow layer boundaries. Three one-dimensional vertical profiles of snowpack properties (density and snow specific surface area) were taken at 75cm, 185cm and 355cm from the left hand side of the trench. These profile measurements were used to derive snow density and grain size for each of the layers identified from the NIR image. Microwave brightness temperatures for the 2-dimensional map of snow properties was simulated with the Helsinki University of Technology (HUT) model at 1cm intervals horizontally across the trench. Where each of five ice lenses was identified in the snow stratigraphy, a decrease in brightness temperature was simulated. However, the median brightness temperature simulated across the trench was substantially higher than the observations, of the order of tens of Kelvin, dependent on frequency and polarization. In order to understand and quantify possible sources of error in the simulations, a number of experiments were carried out to investigate the sensitivity of the brightness temperature to: 1) uncertainties in field observations, 2) representation of ice lenses, 3) model layering structure, and 4) near-infrared derived grain size representing snow grain size at microwave wavelengths. Field measurement error made little difference to the simulated brightness temperature, nor did the representation of ice lenses as crusts of high density snow. As the number of layers in the snow was reduced to 3, 2, or 1, the simulated brightness temperature increased slightly. However, scaling of snow grain size had a dramatic effect on the simulated brightness temperatures, reducing the median bias of the simulations to within measurement error for the statistically different brightness temperature distributions. This indicated that further investigation is required to define what is meant by the microwave grain size, and how this relates to the grain size that is used in the microwave emission model.

Suzaku observations of low surface brightness cluster Abell 1631

NASA Astrophysics Data System (ADS)

Babazaki, Yasunori; Mitsuishi, Ikuyuki; Ota, Naomi; Sasaki, Shin; Böhringer, Hans; Chon, Gayoung; Pratt, Gabriel W.; Matsumoto, Hironori

2018-04-01

We present analysis results for a nearby galaxy cluster Abell 1631 at z = 0.046 using the X-ray observatory Suzaku. This cluster is categorized as a low X-ray surface brightness cluster. To study the dynamical state of the cluster, we conduct four-pointed Suzaku observations and investigate physical properties of the Mpc-scale hot gas associated with the A 1631 cluster for the first time. Unlike relaxed clusters, the X-ray image shows no strong peak at the center and an irregular morphology. We perform spectral analysis and investigate the radial profiles of the gas temperature, density, and entropy out to approximately 1.5 Mpc in the east, north, west, and south directions by combining with the XMM-Newton data archive. The measured gas density in the central region is relatively low (a few ×10-4 cm-3) at the given temperature (˜2.9 keV) compared with X-ray-selected clusters. The entropy profile and value within the central region (r < 0.1 r200) are found to be flatter and higher (≳400 keV cm2). The observed bolometric luminosity is approximately three times lower than that expected from the luminosity-temperature relation in previous studies of relaxed clusters. These features are also observed in another low surface brightness cluster, Abell 76. The spatial distributions of galaxies and the hot gas appear to be different. The X-ray luminosity is relatively lower than that expected from the velocity dispersion. A post-merger scenario may explain the observed results.

Suzaku observations of low surface brightness cluster Abell 1631

NASA Astrophysics Data System (ADS)

Babazaki, Yasunori; Mitsuishi, Ikuyuki; Ota, Naomi; Sasaki, Shin; Böhringer, Hans; Chon, Gayoung; Pratt, Gabriel W.; Matsumoto, Hironori

2018-06-01

We present analysis results for a nearby galaxy cluster Abell 1631 at z = 0.046 using the X-ray observatory Suzaku. This cluster is categorized as a low X-ray surface brightness cluster. To study the dynamical state of the cluster, we conduct four-pointed Suzaku observations and investigate physical properties of the Mpc-scale hot gas associated with the A 1631 cluster for the first time. Unlike relaxed clusters, the X-ray image shows no strong peak at the center and an irregular morphology. We perform spectral analysis and investigate the radial profiles of the gas temperature, density, and entropy out to approximately 1.5 Mpc in the east, north, west, and south directions by combining with the XMM-Newton data archive. The measured gas density in the central region is relatively low (a few ×10-4 cm-3) at the given temperature (˜2.9 keV) compared with X-ray-selected clusters. The entropy profile and value within the central region (r < 0.1 r200) are found to be flatter and higher (≳400 keV cm2). The observed bolometric luminosity is approximately three times lower than that expected from the luminosity-temperature relation in previous studies of relaxed clusters. These features are also observed in another low surface brightness cluster, Abell 76. The spatial distributions of galaxies and the hot gas appear to be different. The X-ray luminosity is relatively lower than that expected from the velocity dispersion. A post-merger scenario may explain the observed results.

Skin Temperature Rhythms in Humans Respond to Changes in the Timing of Sleep and Light.

PubMed

Cuesta, Marc; Boudreau, Philippe; Cermakian, Nicolas; Boivin, Diane B

2017-06-01

Body temperature is known to vary with circadian phase and to be influenced by factors that can mask its circadian expression. We wanted to test whether skin temperature rhythms were sensitive to an abrupt shift of the sleep schedule and to the resetting effects of light. Nineteen healthy subjects spent 6 days in time isolation and underwent a simulated night-shift procedure. They were assigned to either a control group ( n = 10) or bright light group ( n = 9) and measurements were taken under a baseline day-oriented schedule and during the 4 th cycle of a night-oriented schedule. In the bright light group, participants were exposed to a 3-cycle 8-h exposure of ~6,500 lux at night, while the control group remained in dim light conditions (~3 lux). Skin temperature was recorded in 10 and 4 participants from the control and bright light groups, respectively. We found significant circadian rhythms of plasma melatonin, core body temperature (CBT), and skin temperature at baseline for both groups ( p < 0.001 for all). Rhythms of melatonin, CBT, and skin temperature following night shifts were significantly phase delayed by about 7 to 9 h ( p < 0.05) in response to bright light at night, whereas there was no shift in the control group. In addition, we found that at bedtime melatonin does not consistently increase before the increase in distal skin temperature and subsequent decrease in CBT, in contrast to what has been previously reported. The present study shows that, in constant posture conditions, skin temperature rhythms have an evoked component sensitive to abrupt changes in the timing of sleep. They also comprise an endogenous component that is sensitive to the resetting effects of bright light exposure. These results have applications for the determination of circadian phase, as skin temperature is less intrusive than rectal temperature recordings.

L band brightness temperature observations over a corn canopy during the entire growth cycle

USDA-ARS?s Scientific Manuscript database

During a field campaign covering the 2002 corn growing season, a dual polarized tower mounted L-band (1.4 GHz) radiometer (LRAD) provided brightness temperature (T¬B) measurements at preset intervals, incidence and azimuth angles. These radiometer measurements were supported by an extensive characte...

Comparison of Nimbus-7 SMMR and GOES-1 VISSR Atmospheric Liquid Water Content.

NASA Astrophysics Data System (ADS)

Lojou, Jean-Yves; Frouin, Robert; Bernard, René

1991-02-01

Vertically integrated atmospheric liquid water content derived from Nimbus-7 Scanning Multichannel Microwave Radiometer (SMMR) brightness temperatures and from GOES-1 Visible and Infrared Spin-Scan Radiometer (VISSR) radiances in the visible are compared over the Indian Ocean during MONEX (monsoon experiment). In the retrieval procedure, Wilheit and Chang' algorithm and Stephens' parameterization schemes are applied to the SMMR and VISSR data, respectively. The results indicate that in the 0-100 mg cm2 range of liquid water content considered, the correlation coefficient between the two types of estimates is 0.83 (0.81- 0.85 at the 99 percent confidence level). The Wilheit and Chang algorithm, however, yields values lower than those obtained with Stephens's schemes by 24.5 mg cm2 on the average, and occasionally the SMMR-based values are negative. Alternative algorithms are proposed for use with SMMR data, which eliminate the bias, augment the correlation coefficient, and reduce the rms difference. These algorithms include using the Witheit and Chang formula with modified coefficients (multilinear regression), the Wilheit and Chang formula with the same coefficients but different equivalent atmospheric temperatures for each channel (temperature bias adjustment), and a second-order polynomial in brightness temperatures at 18, 21, and 37 GHz (polynomial development). When applied to a dataset excluded from the regressionn dataset, the multilinear regression algorithm provides the best results, namely a 0.91 correlation coefficient, a 5.2 mg cm2 (residual) difference, and a 2.9 mg cm2 bias. Simply shifting the liquid water content predicted by the Wilheit and Chang algorithm does not yield as good comparison statistics, indicating that the occasional negative values are not due only to a bias. The more accurate SMMR-derived liquid water content allows one to better evaluate cloud transmittance in the solar spectrum, at least in the area and during the period analyzed. Combining this cloud transmittance with a clear sky model would provide ocean surface insulation estimates from SMMR data alone.

The functional correlation between rainfall rate and extinction coefficient for frequencies from 3 to 10 GHz

NASA Technical Reports Server (NTRS)

Jameson, A. R.

1990-01-01

The relationship between the rainfall rate (R) obtained from radiometric brightness temperatures and the extinction coefficient (k sub e) is investigated by computing the values of k sub e over a wide range of rainfall rates, for frequencies from 3 to 25 GHz. The results show that the strength of the relation between the R and the k sub e values exhibits considerable variation for frequencies at this range. Practical suggestions are made concerning the selection of particular frequencies for rain measurements to minimize the error in R determinations.

MWRRET Value-Added Product: The Retrieval of Liquid Water Path and Precipitable Water Vapor from Microwave Radiometer (MWR) Datasets

DOE Office of Scientific and Technical Information (OSTI.GOV)

KL Gaustad; DD Turner

2007-09-30

This report provides a short description of the Atmospheric Radiation Measurement (ARM) microwave radiometer (MWR) RETrievel (MWRRET) Value-Added Product (VAP) algorithm. This algorithm utilizes complimentary physical and statistical retrieval methods and applies brightness temperature offsets to reduce spurious liquid water path (LWP) bias in clear skies resulting in significantly improved precipitable water vapor (PWV) and LWP retrievals. We present a general overview of the technique, input parameters, output products, and describe data quality checks. A more complete discussion of the theory and results is given in Turner et al. (2007b).

Glacial Boundary Features Delineated Using Enhanced-resolution Passive-microwave Data to Determine Melt Season Variation of the Vatnajokull Ice Cap, Iceland

NASA Astrophysics Data System (ADS)

Marzillier, D. M.; Ramage, J. M.

2017-12-01

Temperate glaciers such as those seen in Iceland experience high annual mass flux, thereby responding to small scale changes in Earth's climate. Decadal changes in the glacial margins of Iceland's ice caps are observable in the Landsat record, however twice daily AMSR-E Calibrated Enhanced-Resolution Passive Microwave Daily EASE-Grid 2.0 Brightness Temperature (CETB) Earth System Data Record (ESDR) allow for observation on a daily temporal scale and a 3.125 km spatial scale, which can in turn be connected to patterns seen over longer periods of time. Passive microwave data allow for careful observation of melt onset and duration in Iceland's glacial regions by recording changes in emissivity of the ice surface, known as brightness temperature (TB), which is sensitive to fluctuations in the liquid water content of snow and ice seen during melting in glaciated regions. Enhanced resolution of this data set allows for a determination of a threshold that defines the melting season. The XPGR snowmelt algorithm originally presented by Abdalati and Steffen (1995) is used as a comparison with the diurnal amplitude variation (DAV) values on Iceland's Vatnajokull ice cap located at 64.4N, -16.8W. Ground-based air temperature data in this region, digital elevation models (DEMs), and river discharge dominated by glacial runoff are used to confirm the glacial response to changes in global climate. Results show that Iceland glaciers have a bimodal distribution of brightness temperature delineating when the snow/ice is melting and refreezing. Ground based temperatures have increased on a decadal trend. Clear glacial boundaries are visible on the passive microwave delineating strong features, and we are working to understand their variability and contribution to glacier evolution. The passive microwave data set allows connections to be made between observations seen on a daily scale and the long term glacier changes observed by the Landsat satellite record that integrates the overall glacier changes.

Environmental Effects on the Metallicities of Early-Type Galaxies

NASA Technical Reports Server (NTRS)

Jones, Christine; Oliversen, Ronald (Technical Monitor)

2004-01-01

We completed and published two papers in the Astrophysical Journal based on research from grant. In the first paper we analyzed nine X-ray-bright Virgo early-type galaxies observed by both ASCA and ROSAT. Through spatially resolved spectroscopy, we determined the radial temperature profiles and abundances of Mg, Si, and Fe for six galaxies. The temperature profiles are consistent with isothermal temperatures outside of cooler regions at the galaxies' centers. We present new evidence for iron abundance gradients in NGC 4472 and NGC 4649 and confirm the previous results on NGC 4636. Mg and Si abundance gradients on average are flatter than those of iron and correspond to an underabundance of α-process elements at high Fe values, while at low iron the element ratios favor enrichment by Type II supernovae (SNe). We explain the observed trend using the metallicity dependence of SN Ia metal production and present constraints on the available theoretical modeling for low-metallicity inhibition of SNe Ia. In the second paper We analyzed nine X-ray-bright Virgo early-type galaxies observed by both ASCA and ROSAT. Through spatially resolved spectroscopy, we determined the radial temperature profiles and abundances of Mg, Si, and Fe for six galaxies. The temperature profiles are consistent with isothermal temperatures outside of cooler regions at the galaxies' centers. We present new evidence for iron abundance gradients in NGC 4472 and NGC 4649 and confirm the previous results on NGC 4636. Mg and Si abundance gradients on average are flatter than those of iron and correspond to an underabundance of α-process elements at high Fe values, while at low iron the element ratios favor enrichment by Type I1 supernovae (SNe). We explain the observed trend using the metallicity dependence of SN Ia metal production and present constraints on the available theoretical modeling for low-metallicity inhibition of SNe Ia.

Microwave brightness temperature of a windblown sea

NASA Technical Reports Server (NTRS)

Hall, F. G.

1972-01-01

A mathematical model is developed for the apparent temperature of the sea at all microwave frequencies. The model is a numerical model in which both the clear water structure and white water are accounted for as a function of wind speed. The model produces results similar to Stogryn's model at 19.35 GHz for wind speeds less than 8 m/sec; it can use radiosonde data to calculate atmospheric effects and can incorporate an empirically determined antenna gain pattern. The corresponding computer program is of modular design and the logic of the main program is capable of treating a horizontally inhomogeneous surface or atmosphere. It is shown that a variation of microwave brightness temperature with zenith angle is necessary to produce the wind sensitivity of the horizontally polarized brightness temperature; the variation of sky temperature with frequency is sufficient to produce a frequency dependent wind sensitivity.

A Parallel, High-Fidelity Radar Model

DTIC Science & Technology

2010-09-01

THIS PAGE unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 . TCMB is the temperature due to the cosmic microwave background ...per unit area, per unit frequency. In the microwave regime, this is usually given the name brightness temperature, . There are various sources...which contribute to the brightness temperature. They include external sources outside of the earth’s atmosphere (e.g. cosmic or galactic noise

Intercalibration between HIRS/2 and HIRS/3 channel 12 based on physical considerations

NASA Astrophysics Data System (ADS)

Gierens, Klaus; Eleftheratos, Kostas; Sausen, Robert

2018-02-01

High-resolution Infrared Radiation Sounder (HIRS) brightness temperatures at channel 12 (T12) can be used to assess the water vapour content of the upper troposphere. The transition from HIRS/2 to HIRS/3 in 1999 involved a shift in the central wavelength of channel 12 from 6.7 to 6.5 µm, causing a discontinuity in the time series of T12. To understand the impact of this change in the measured brightness temperatures, we have performed radiative transfer calculations for channel 12 of HIRS/2 and HIRS/3 instruments, using a large set of radiosonde profiles of temperature and relative humidity from three different sites. Other possible changes within the instrument, apart from the changed spectral response function, have been assumed to be of minor importance, and in fact, it was necessary to assume as a working hypothesis that the spectral and radiometric calibration of the two instruments did not change during the relatively short period of their common operation. For each radiosonde profile we performed two radiative transfer calculations, one using the HIRS/2 channel response function of NOAA 14 and one using the HIRS/3 channel response function of NOAA 15, resulting in negative differences of T12 (denoted as ΔT12 := T12/15 - T12/14) ranging between -12 and -2 K. Inspection of individual profiles for large, medium and small values of ΔT12 pointed to the role of the mid-tropospheric humidity. This guided us to investigate the relation between ΔT12 and the channel 11 brightness temperatures which are typically used to detect signals from the mid-troposphere. This allowed us to construct a correction for the HIRS/3 T12, which leads to a pseudo-channel 12 brightness temperature as if a HIRS/2 instrument had measured it. By applying this correction we find an excellent agreement between the original HIRS/2 T12 and the HIRS/3 data inferred from the correction method with R = 0.986. Upper-tropospheric humidity (UTH) derived from the pseudo HIRS/2 T12 data compared well with that calculated from intersatellite-calibrated data, providing independent justification for using the two intercalibrated time series (HIRS/2 and HIRS/3) as a continuous HIRS time series for long-term UTH analyses.

Remote sensing of soil moisture content over bare fields at 1.4 GHz frequency

NASA Technical Reports Server (NTRS)

Wang, J. R.; Choudhury, B. J.

1980-01-01

A simple method of estimating moisture content (W) of a bare soil from the observed brightness temperature (T sub B) at 1.4 GHz is discussed. The method is based on a radiative transfer model calculation, which has been successfully used in the past to account for many observational results, with some modifications to take into account the effect of surface roughness. Besides the measured T sub B's, the three additional inputs required by the method are the effective soil thermodynamic temperature, the precise relation between W and the smooth field brightness temperature T sub B and a parameter specifying the surface roughness characteristics. The soil effective temperature can be readily measured and the procedures of estimating surface roughness parameter and obtaining the relation between W and smooth field brightness temperature are discussed in detail. Dual polarized radiometric measurements at an off-nadir incident angle are sufficient to estimate both surface roughness parameter and W, provided that the relation between W and smooth field brightness temperature at the same angle is known. The method of W estimate is demonstrated with two sets of experimental data, one from a controlled field experiment by a mobile tower and the other, from aircraft overflight. The results from both data sets are encouraging when the estimated W's are compared with the acquired ground truth of W's in the top 2 cm layer. An offset between the estimated and the measured W's exists in the results of the analyses, but that can be accounted for by the presently poor knowledge of the relationship between W and smooth field brightness temperature for various types of soils. An approach to quantify this relationship for different soils and thus improve the method of W estimate is suggested.

Spectral ratio method for measuring emissivity

USGS Publications Warehouse

Watson, K.

1992-01-01

The spectral ratio method is based on the concept that although the spectral radiances are very sensitive to small changes in temperature the ratios are not. Only an approximate estimate of temperature is required thus, for example, we can determine the emissivity ratio to an accuracy of 1% with a temperature estimate that is only accurate to 12.5 K. Selecting the maximum value of the channel brightness temperatures is an unbiased estimate. Laboratory and field spectral data are easily converted into spectral ratio plots. The ratio method is limited by system signal:noise and spectral band-width. The images can appear quite noisy because ratios enhance high frequencies and may require spatial filtering. Atmospheric effects tend to rescale the ratios and require using an atmospheric model or a calibration site. ?? 1992.

The effect of monomolecular surface films on the microwave brightness temperature of the sea surface

NASA Technical Reports Server (NTRS)

Alpers, W.; Blume, H.-J. C.; Garrett, W. D.; Huehnerfuss, H.

1982-01-01

It is pointed out that monomolecular surface films of biological origin are often encountered on the ocean surface, especially in coastal regions. The thicknesses of the monomolecular films are of the order of 3 x 10 to the -9th m. Huehnerfuss et al. (1978, 1981) have shown that monomolecular surface films damp surface waves quite strongly in the centimeter to decimeter wavelength regime. Other effects caused by films are related to the reduction of the gas exchange at the air-sea interface and the decrease of the wind stress. The present investigation is concerned with experiments which reveal an unexpectedly large response of the microwave brightness temperature to a monomolecular oleyl alcohol slick at 1.43 GHz. Brightness temperature is a function of the complex dielectric constant of thy upper layer of the ocean. During six overflights over an ocean area covered with an artificial monomolecular alcohol film, a large decrease of the brightness temperature at the L-band was measured, while at the S-band almost no decrease was observed.

Titan's surface from the Cassini RADAR radiometry data during SAR mode

USGS Publications Warehouse

Paganelli, F.; Janssen, M.A.; Lopes, R.M.; Stofan, E.; Wall, S.D.; Lorenz, R.D.; Lunine, J.I.; Kirk, R.L.; Roth, L.; Elachi, C.

2008-01-01

We present initial results on the calibration and interpretation of the high-resolution radiometry data acquired during the Synthetic Aperture Radar (SAR) mode (SAR-radiometry) of the Cassini Radar Mapper during its first five flybys of Saturn's moon Titan. We construct maps of the brightness temperature at the 2-cm wavelength coincident with SAR swath imaging. A preliminary radiometry calibration shows that brightness temperature in these maps varies from 64 to 89 K. Surface features and physical properties derived from the SAR-radiometry maps and SAR imaging are strongly correlated; in general, we find that surface features with high radar reflectivity are associated with radiometrically cold regions, while surface features with low radar reflectivity correlate with radiometrically warm regions. We examined scatterplots of the normalized radar cross-section ??0 versus brightness temperature, outlining signatures that characterize various terrains and surface features. The results indicate that volume scattering is important in many areas of Titan's surface, particularly Xanadu, while other areas exhibit complex brightness temperature variations consistent with variable slopes or surface material and compositional properties. ?? 2007.

The impact of morning light intensity and environmental temperature on body temperatures and alertness.

PubMed

Te Kulve, Marije; Schlangen, Luc J M; Schellen, Lisje; Frijns, Arjan J H; van Marken Lichtenbelt, Wouter D

2017-06-01

Indoor temperature and light exposure are known to affect body temperature, productivity and alertness of building occupants. However, not much is known about the interaction between light and temperature exposure and the relationship between morning light induced alertness and its effect on body temperature. Light intensity and room temperature during morning office hours were investigated under strictly controlled conditions. In a randomized crossover study, two white light conditions (4000K, either bright 1200lx or dim 5lx) under three different room temperatures (26, 29 and 32°C) were investigated. A lower room temperature increased the core body temperature (CBT) and lowered skin temperature and the distal-proximal temperature gradient (DPG). Moreover, a lower room temperature reduced the subjective sleepiness and reaction time on an auditory psychomotor vigilance task (PVT), irrespective of the light condition. Interestingly, the morning bright light exposure did affect thermophysiological parameters, i.e. it decreased plasma cortisol, CBT and proximal skin temperature and increased the DPG, irrespective of the room temperature. During the bright light session, subjective sleepiness decreased irrespective of the room temperature. However, the change in sleepiness due to the light exposure was not related to these physiological changes. Copyright © 2017 Elsevier Inc. All rights reserved.

Synthesis of SrAl2O4:Eu2+ phosphors co-doped with Dy3+, Tb3+, Si4+ and optimization of co-doping amount by response surface method

NASA Astrophysics Data System (ADS)

Wang, Huan; Liang, Xiaoping; Liu, Kai; Zhou, Qianqian; Chen, Peng; Wang, Jun; Li, Jianxin

2016-03-01

Dy3+ doped SrAl2O4:Eu2+ phosphors were synthesized by high temperature solid phase method in a weak reducing atmosphere (5% H2 + 95% N2). The relationship between the crushed granularity and the phosphors brightness was studied. The effect of co-doping amount of Dy3+, Tb3+ and Si4+ on the structure and properties of SrAl2O4:Eu2+ via response surface method was investigated. Photoluminescence measurement results showed that the initial afterglow brightness of 0.002 mol% Dy3+ doped SrAl2O4:Eu2+0.002 phosphors decreased after first increased within the sintering temperature range from 1150 to 1400 °C, which created the highest value of 12,101 mcd/m2 at 1300 °C. Numerous coarse particles in the powder ought to be crushed for the practical application, however, the brightness became lower accompanied by the decrease of the granularity. The luminescence property of SrAl2O4:Eu2+ sintered at 1200 °C improved by co-doping Dy3+-Tb3+-Si4+. The results of response surface method showed that the influence extent on the luminescence property was Dy3+ > Tb3+ > Si4+. When the co-doping amount in SrAl2O4:Eu2+0.002 phosphors of Dy3+, Tb3+ and Si4+ was 0.001 mol%, 0.0005 mol% and 0.002 mol%, respectively, the initial afterglow brightness of SrAl2O4 was up to the highest value of 12,231 mcd/m2, which was in good agreement on the predicted maximum value of 12,519 mcd/m2 with the optimum co-doping amount of 0.0015 mol% Dy3+, 0.0005 mol% Tb3+ and 0.0017 mol% Si4+. The brightness of co-doped phosphors not only increased by 56.79% than that of SrAl2O4:Eu2+0.002, Dy3+0.002 sintered at 1200 °C, but also was above that of 1300 °C. The emission spectra results showed that, compared with 0.001 mol% Dy3+ doped phosphor, the emission peak of 0.001 mol% Dy3+-0.001 mol% Tb3+ co-doped phosphor generated red shift and increased by 9.3% in emission intensity; 0.001 mol% Dy3+-0.004 mol% Si4+ and 0.001 mol% Dy3+-0.001 mol% Tb3+-0.004 mol% Si4+ co-doped SrAl2O4:Eu2+0.002 emission peak created blue shift and increased by 37.2% and 47.6% in emission intensity, respectively.

The radio structure of the peculiar narrow-line Seyfert 1 galaxy candidate J1100+4421

NASA Astrophysics Data System (ADS)

Gabányi, K. É.; Frey, S.; Paragi, Z.; Järvelä, E.; Morokuma, T.; An, T.; Tanaka, M.; Tar, I.

2018-01-01

Narrow-line Seyfert 1 galaxies (NLS1) are an intriguing subclass of active galactic nuclei. Their observed properties indicate low central black hole mass and high accretion rate. The extremely radio-loud NLS1 sources often show relativistic beaming and are usually regarded as younger counterparts of blazars. Recently, the object SDSS J110006.07+442144.3 was reported as a candidate NLS1 source. The characteristics of its dramatic optical flare indicated its jet-related origin. The spectral energy distribution of the object was similar to that of the γ-ray detected radio-loud NLS1, PMN J0948+0022. Our high-resolution European very long baseline interferometry network observations at 1.7 and 5 GHz revealed a compact core feature with a brightness temperature of ≳1010 K. Using the lowest brightness temperature value and assuming a moderate Lorentz factor of ∼9, the jet viewing angle is ≲26°. Archival Very Large Array data show a large-scale radio structure with a projected linear size of ∼150 kpc reminiscent of double-sided morphology.

Microwave emission measurements of sea surface roughness, soil moisture, and sea ice structure

NASA Technical Reports Server (NTRS)

Gloersen, P.; Wilheit, T. T.; Schmugge, T. J.

1972-01-01

In order to demonstrate the feasibility of the microwave radiometers to be carried aboard the Nimbus 5 and 6 satellites and proposed for one of the earth observatory satellites, remote measurements of microwave radiation at wavelengths ranging from 0.8 to 21 cm have been made of a variety of the earth's surfaces from the NASA CV-990 A/C. Brightness temperatures of sea water surfaces of varying roughness, of terrain with varying soil moisture, and of sea ice of varying structure were observed. In each case, around truth information was available for correlation with the microwave brightness temperature. The utility of passive microwave radiometry in determining ocean surface wind speeds, at least for values higher than 7 meters/second has been demonstrated. In addition, it was shown that radiometric signatures can be used to determine soil moisture in unvegetated terrain to within five percentage points by weight. Finally, it was demonstrated that first year thick, multi-year, and first year thin sea ice can be distinguished by observing their differing microwave emissivities at various wavelengths.

Comparison of measured brightness temperatures from SMOS with modelled ones from ORCHIDEE and H-TESSEL over the Iberian Peninsula

NASA Astrophysics Data System (ADS)

Barella-Ortiz, Anaïs; Polcher, Jan; de Rosnay, Patricia; Piles, Maria; Gelati, Emiliano

2017-01-01

L-band radiometry is considered to be one of the most suitable techniques to estimate surface soil moisture (SSM) by means of remote sensing. Brightness temperatures are key in this process, as they are the main input in the retrieval algorithm which yields SSM estimates. The work exposed compares brightness temperatures measured by the SMOS mission to two different sets of modelled ones, over the Iberian Peninsula from 2010 to 2012. The two modelled sets were estimated using a radiative transfer model and state variables from two land-surface models: (i) ORCHIDEE and (ii) H-TESSEL. The radiative transfer model used is the CMEM. Measured and modelled brightness temperatures show a good agreement in their temporal evolution, but their spatial structures are not consistent. An empirical orthogonal function analysis of the brightness temperature's error identifies a dominant structure over the south-west of the Iberian Peninsula which evolves during the year and is maximum in autumn and winter. Hypotheses concerning forcing-induced biases and assumptions made in the radiative transfer model are analysed to explain this inconsistency, but no candidate is found to be responsible for the weak spatial correlations at the moment. Further hypotheses are proposed and will be explored in a forthcoming paper. The analysis of spatial inconsistencies between modelled and measured TBs is important, as these can affect the estimation of geophysical variables and TB assimilation in operational models, as well as result in misleading validation studies.

LRO Diviner Nonlinear Response and Opposition Effect Corrections

NASA Astrophysics Data System (ADS)

Gyalay, S.; Aye, K. M.; Paige, D. A.

2016-12-01

Aboard the Lunar Reconnaissance Orbiter, the Diviner Lunar Radiometer Experiment measures thermal radiation to determine the brightness temperature of the lunar surface. As with the Mars Climate Sounder (upon which Diviner is based), we use pre-flight calibration data to correct for the nonlinear response in Diviner's detectors, which in-turn accounts for much of the detector non-uniformity within channels. Furthermore, channels 8 and 9 exhibit unexpectedly high brightness temperatures close to the equator around midday, with even higher brightness temperatures when observing lunar highlands as opposed to maria. Unexpectedly high brightness temperatures around midday at the equator is reminiscent of the opposition effect known to exist on the Moon at low phase angles in Visual to Near Infra-Red (VNIR) wavelengths. Diviner channel 2 data (which detects solar radiation reflected by the Moon) shows this opposition effect, which is more pronounced in the highlands than the maria. We interpret a correlation we observe between channel 2 detected radiance and channel 8 and 9 brightness temperature as due to incomplete blocking of reflected solar radiation. This leads us to an opposition effect correction for Diviner channels 8 and 9 dependent on Diviner's solar channel data. Whether this is a direct leak of VNIR light upon the detectors, or solar heating of blocking filters, which then radiate infrared radiation upon the detectors, is yet to be determined. We can use the nonlinearity and opposition effect corrections to recharacterize the spectral emissivity of the lunar regolith, which we can then compare to laboratory spectra.

High-brightness 1.3 μm InAs/GaAs quantum dot tapered laser with high temperature stability.

PubMed

Cao, Yulian; Ji, Haiming; Xu, Pengfei; Gu, Yongxian; Ma, Wenquan; Yang, Tao

2012-10-01

We demonstrate high-brightness 1.3 μm tapered lasers with high temperature stability by using p-doped InAs/GaAs quantum dots (QDs) as the active region. It is found that the beam quality factor M(2) for the devices is almost unchanged as the light power and temperature increase. The almost constant M(2) results from the p-doped QD active region.

ATM observations - X-ray results. [solar coronal structure from Skylab experiments

NASA Technical Reports Server (NTRS)

Vaiana, G. S.; Zombeck, M.; Krieger, A. S.; Timothy, A. F.

1976-01-01

Preliminary results of the solar X-ray observations from Skylab are reviewed which indicate a highly structured nature for the corona, with closed magnetic-loop structures over a wide range of size scales. A description of the S-054 experiments is provided, and values are given for the parameters - including size, density, and temperature - describing a variety of typical coronal features. The structure and evolution of active regions, coronal holes, and bright points are discussed.

Comparative analysis of multisensor satellite monitoring of Arctic sea-ice

USGS Publications Warehouse

Belchansky, G.I.; Mordvintsev, Ilia N.; Douglas, David C.

1999-01-01

This report represents comparative analysis of nearly coincident Russian OKEAN-01 polar orbiting satellite data, Special Sensor Microwave Imager (SSM/I) and Advanced Very High Resolution Radiometer (AVHRR) imagery. OKEAN-01 ice concentration algorithms utilize active and passive microwave measurements and a linear mixture model for measured values of the brightness temperature and the radar backscatter. SSM/I and AVHRR ice concentrations were computed with NASA Team algorithm and visible and thermal-infrared wavelength AVHRR data, accordingly

Combined Dust Detection Algorithm by Using MODIS Infrared Channels over East Asia

NASA Technical Reports Server (NTRS)

Park, Sang Seo; Kim, Jhoon; Lee, Jaehwa; Lee, Sukjo; Kim, Jeong Soo; Chang, Lim Seok; Ou, Steve

2014-01-01

A new dust detection algorithm is developed by combining the results of multiple dust detectionmethods using IR channels onboard the MODerate resolution Imaging Spectroradiometer (MODIS). Brightness Temperature Difference (BTD) between two wavelength channels has been used widely in previous dust detection methods. However, BTDmethods have limitations in identifying the offset values of the BTDto discriminate clear-sky areas. The current algorithm overcomes the disadvantages of previous dust detection methods by considering the Brightness Temperature Ratio (BTR) values of the dual wavelength channels with 30-day composite, the optical properties of the dust particles, the variability of surface properties, and the cloud contamination. Therefore, the current algorithm shows improvements in detecting the dust loaded region over land during daytime. Finally, the confidence index of the current dust algorithm is shown in 10 × 10 pixels of the MODIS observations. From January to June, 2006, the results of the current algorithm are within 64 to 81% of those found using the fine mode fraction (FMF) and aerosol index (AI) from the MODIS and Ozone Monitoring Instrument (OMI). The agreement between the results of the current algorithm and the OMI AI over the non-polluted land also ranges from 60 to 67% to avoid errors due to the anthropogenic aerosol. In addition, the developed algorithm shows statistically significant results at four AErosol RObotic NETwork (AERONET) sites in East Asia.

Laboratory study of the spectrum of highly ionized calcium in the 100-250 A range applied to solar flare diagnostics

NASA Technical Reports Server (NTRS)

Lippmann, S.; Finkenthal, M.; Huang, L. K.; Moos, H. W.; Stratton, B. C.; Yu, T. L.; Bhatia, A. K.

1987-01-01

Calcium was introduced into the TEXT tokamak, and its spectral emission was recorded in the 50-360 A range by an absolutely calibrated grazing incidence spectrometer. These observations of highly ionized species of calcium at known conditions of plasma electron temperature and density allow testing of line brightness ratio predictions based on theoretical values of temperature-dependent electron excitation rates. The confirmation of the expected ratios in Be I-like to O I-like calcium allows more confident use of these ratios as a density diagnostic of remote astrophysical sources such as solar flares.

T1 bright appendix sign to exclude acute appendicitis in pregnant women.

PubMed

Shin, Ilah; An, Chansik; Lim, Joon Seok; Kim, Myeong-Jin; Chung, Yong Eun

2017-08-01

To evaluate the diagnostic value of the T1 bright appendix sign for the diagnosis of acute appendicitis in pregnant women. This retrospective study included 125 pregnant women with suspected appendicitis who underwent magnetic resonance (MR) imaging. The T1 bright appendix sign was defined as a high intensity signal filling more than half length of the appendix on T1-weighted imaging. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the T1 bright appendix sign for normal appendix identification were calculated in all patients and in those with borderline-sized appendices (6-7 mm). The T1 bright appendix sign was seen in 51% of patients with normal appendices, but only in 4.5% of patients with acute appendicitis. The overall sensitivity, specificity, PPV, and NPV of the T1 bright appendix sign for normal appendix diagnosis were 44.9%, 95.5%, 97.6%, and 30.0%, respectively. All four patients with borderline sized appendix with appendicitis showed negative T1 bright appendix sign. The T1 bright appendix sign is a specific finding for the diagnosis of a normal appendix in pregnant women with suspected acute appendicitis. • Magnetic resonance imaging is increasingly used in emergency settings. • Acute appendicitis is the most common cause of acute abdomen. • Magnetic resonance imaging is widely used in pregnant population. • T1 bright appendix sign can be a specific sign representing normal appendix.

Results of soil moisture flights during April 1974

NASA Technical Reports Server (NTRS)

Schmugge, T. J.; Blanchard, B. J.; Burke, W. J.; Paris, J. F.; Swang, J. R.

1976-01-01

The results presented here are derived from measurements made during the April 5 and 6, 1974 flights of the NASA P-3A aircraft over the Phoenix, Arizona agricultural test site. The purpose of the mission was to study the use of microwave techniques for the remote sensing of soil moisture. These results include infrared (10-to 12 micrometers) 2.8-cm and 21-cm brightness temperatures for approximately 90 bare fields. These brightness temperatures are compared with surface measurements of the soil moisture made at the time of the overflights. These data indicate that the combination of the sum and difference of the vertically and the horizontally polarized brightness temperatures yield information on both the soil moisture and surface roughness conditions.

Emirates Mars Ultraviolet Spectrometer's (EMUS) Prediction of Oxygen OI 135.6 nm and CO 4PG Emissions in the Martian Atmosphere

NASA Astrophysics Data System (ADS)

Almatroushi, H. R.; Lootah, F. H.; Deighan, J.; Fillingim, M. O.; Jain, S.; Bougher, S. W.; England, S.; Schneider, N. M.

2017-12-01

This research focuses on developing empirical and theoretical models for OI 135.6 nm and CO 4PG band system FUV dayglow emissions in the Martian thermosphere as predicted to be seen from the Emirates Mars Ultraviolet Spectrometer (EMUS), one of the three scientific instruments aboard the Emirates Mars Mission (EMM) to be launched in 2020. These models will aid in simulating accurate disk radiances which will be utilized as an input to an EMUS instrument simulator. The developed zonally averaged empirical models are based on FUV data from the IUVS instrument onboard the MAVEN mission, while the theoretical models are based on a basic Chapman profile. The models calculate the brightness (B) of those emissions taking into consideration observation geometry parameters such as emission angle (EA), solar zenith angle (SZA) and planet distance from the sun (Ds). Specifically, the empirical models takes a general form of Bn=A*cos(SZA)n/cos(EA)m , where Bn is the normalized brightness value of an emission feature, and A, n, and m are positive constant values. The model form shows that the brightness has a positive correlation with EA and a negative correlation with SZA. A comparison of both models are explained in this research while examining full Mars and half Mars disk images generated using geometry code specially developed for the EMUS instrument. Sensitivity analyses have also been conducted for the theoretical modeling to observe the contributions of electron impact on atomic oxygen and CO2 to the brightness of OI 135.6nm, in addition to the effect of electron temperature on the CO2± dissociative recombination contribution to the CO 4PG band system.

Shock-heated NH3 in a Molecular Jet Associated with a High-Mass Young Star.

PubMed

Zhang; Hunter; Sridharan; Cesaroni

1999-12-20

We present the discovery of shock-excited NH3 in a well-collimated jet associated with the extremely young high-mass star IRAS 20126+4104. The NH3 (3, 3) and (4, 4) emission is dominated by three clumps along the SiO jet. At the end of the jet, there exists strong and broad (+/-10 km s-1) NH3 (3, 3) emission. With typical brightness temperatures greater than 500 K, the overall emission indicates a weakly inverted population and appears in an arc, consistent with the excitation by bow shocks. There are two bright spots in the NH3 (3, 3) emission with brightness temperatures of approximately 2000 K. The narrow line width (1.5 km s-1 FWHM), the small sizes (<0&farcs;3), and the unusually high brightness temperature of the features are indicative of maser emission. Our observations provide clear evidence that NH3 (3, 3) masers are excited in shock regions in molecular outflows.

Assimilation of SMOS brightness temperatures in the ECMWF EKF for the analysis of soil moisture

NASA Astrophysics Data System (ADS)

Munoz-Sabater, Joaquin

2012-07-01

Since November 2nd 2009, the European Centre for Medium-Range Weather Forecasts (ECMWF) has being monitoring, in Near Real Time (NRT), L-band brightness temperatures measured by the Soil Moisture and Ocean Salinity (SMOS) satellite mission of the European Space Agency (ESA). The main objective of the monitoring suite for SMOS data is to systematically monitor the difference between SMOS observed brightness temperatures and the corresponding model equivalent simulated by the Community Microwave Emission Model (CMEM), the so-called first guess departures. This is a crucial step, as first guess departures is the quantity used in the analysis. The ultimate goal is to investigate how the assimilation of SMOS brightness temperatures over land improves the weather forecast skill, through a more accurate initialization of the global soil moisture state. In this presentation, some significant results from the activities preparing for the assimilation of SMOS data are shown. Among these activities, an effective data thinning strategy, a practical approach to reduce noise from the observed brightness temperatures and a bias correction scheme are of special interest. Firstly, SMOS data needs to be significantly thinned as the data volume delivered for a single orbit is too large for the current operational capabilities in any Numerical Weather Prediction system. Different thinning strategies have been analysed and tested. The most suitable one is the assimilation of SMOS brightness temperatures which match the ECMWF T511 (~40 km) reduced Gaussian Grid. Secondly, SMOS observational noise is reduced significantly by averaging the data in angular bins. In addition, this methodology contributes to further thinning of the SMOS data before the analysis. Finally, a bias correction scheme based on a CDF matching is applied to the observations to ensure an unbiased dataset ready for assimilation in the ECMWF surface analysis system. The current ECMWF operational soil moisture analysis system is based on a point-wise Extended Kalman Filter (EKF). This system assimilates proxy surface observations, i.e., 2 m air temperature and relative humidity to analyse the soil moisture state. Recent developments have also made it possible to assimilate remote sensing data coming from active and passive instruments. In particular, the ECMWF EKF can also assimilate data from the Advanced Scatterometer (ASCAT) onboard METOP-A and, more recently, from SMOS brightness temperatures observations. The first preliminary assimilation results will be shown. The analysis fields will be evaluated through comparison to in-situ data from different regions.

Physical Retrievals of Over-Ocean Rain Rate from Multichannel Microwave Imagery. Part 1; Theoretical Characteristics of Normalized Polarization and Scattering Indices

NASA Technical Reports Server (NTRS)

Petty, G. W.

1994-01-01

Microwave rain rate retrieval algorithms have most often been formulated in terms of the raw brightness temperatures observed by one or more channels of a satellite radiometer. Taken individually, single-channel brightness temperatures generally represent a near-arbitrary combination of positive contributions due to liquid water emission and negative contributions due to scattering by ice and/or visibility of the radiometrically cold ocean surface. Unfortunately, for a given rain rate, emission by liquid water below the freezing level and scattering by ice particles above the freezing level are rather loosely coupled in both a physical and statistical sense. Furthermore, microwave brightness temperatures may vary significantly (approx. 30-70 K) in response to geophysical parameters other than liquid water and precipitation. Because of these complications, physical algorithms which attempt to directly invert observed brightness temperatures have typically relied on the iterative adjustment of detailed micro-physical profiles or cloud models, guided by explicit forward microwave radiative transfer calculations. In support of an effort to develop a significantly simpler and more efficient inversion-type rain rate algorithm, the physical information content of two linear transformations of single-frequency, dual-polarization brightness temperatures is studied: the normalized polarization difference P of Petty and Katsaros (1990, 1992), which is intended as a measure of footprint-averaged rain cloud transmittance for a given frequency; and a scattering index S (similar to the polarization corrected temperature of Spencer et al.,1989) which is sensitive almost exclusively to ice. A reverse Monte Carlo radiative transfer model is used to elucidate the qualitative response of these physically distinct single-frequency indices to idealized 3-dimensional rain clouds and to demonstrate their advantages over raw brightness temperatures both as stand-alone indices of precipitation activity and as primary variables in physical, multichannel rain rate retrieval schemes. As a byproduct of the present analysis, it is shown that conventional plane-parallel analyses of the well-known foot-print-filling problem for emission-based algorithms may in some cases give seriously misleading results.

Thermometric- and Acoustic-Based Beam Power Monitor for Ultra-Bright X-Rays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bentsen, Gregory; /Rochester U. /SLAC

2010-08-25

A design for an average beam power monitor for ultra-bright X-ray sources is proposed that makes simultaneous use of calorimetry and radiation acoustics. Radiation incident on a solid target will induce heating and ultrasonic vibrations, both of which may be measured to give a fairly precise value of the beam power. The monitor is intended for measuring ultra-bright Free-Electron Laser (FEL) X-ray beams, for which traditional monitoring technologies such as photo-diodes or scintillators are unsuitable. The monitor consists of a Boron Carbide (B{sub 4}C) target designed to absorb most of the incident beam's energy. Resistance temperature detectors (RTD) and piezoelectricmore » actuators are mounted on the outward faces of the target to measure the temperature changes and ultrasonic vibrations induced by the incident beam. The design was tested using an optical pulsed beam (780 nm, 120 and 360 Hz) from a Ti:sapphire oscillator at several energies between 0.8 and 2.6 mJ. The RTDs measured an increase in temperature of about 10 K over a period of several minutes. The piezoelectric sensors recorded ringing acoustic oscillations at 580 {+-} 40 kHz. Most importantly, the amplitude of the acoustic signals was observed to scale linearly with beam power up to 2 mJ of pulse energy. Above this pulse energy, the vibrational signals became nonlinear. Several causes for this nonlinearity are discussed, including amplifier saturation and piezoelectric saturation. Despite this nonlinearity, these measurements demonstrate the feasibility of such a beam power measurement device. The advantage of two distinct measurements (acoustic and thermometric) provides a useful method of calibration that is unavailable to current LCLS diagnostics tools.« less

Thermodynamics of the Coma Cluster Outskirts

NASA Astrophysics Data System (ADS)

Simionescu, A.; Werner, N.; Urban, O.; Allen, S. W.; Fabian, A. C.; Mantz, A.; Matsushita, K.; Nulsen, P. E. J.; Sanders, J. S.; Sasaki, T.; Sato, T.; Takei, Y.; Walker, S. A.

2013-09-01

We present results from a large mosaic of Suzaku observations of the Coma Cluster, the nearest and X-ray brightest hot (~8 keV), dynamically active, non-cool core system, focusing on the thermodynamic properties of the intracluster medium on large scales. For azimuths not aligned with an infalling subcluster toward the southwest, our measured temperature and X-ray brightness profiles exhibit broadly consistent radial trends, with the temperature decreasing from about 8.5 keV at the cluster center to about 2 keV at a radius of 2 Mpc, which is the edge of our detection limit. The southwest merger significantly boosts the surface brightness, allowing us to detect X-ray emission out to ~2.2 Mpc along this direction. Apart from the southwestern infalling subcluster, the surface brightness profiles show multiple edges around radii of 30-40 arcmin. The azimuthally averaged temperature profile, as well as the deprojected density and pressure profiles, all show a sharp drop consistent with an outwardly-propagating shock front located at 40 arcmin, corresponding to the outermost edge of the giant radio halo observed at 352 MHz with the Westerbork Synthesis Radio Telescope. The shock front may be powering this radio emission. A clear entropy excess inside of r 500 reflects the violent merging events linked with these morphological features. Beyond r 500, the entropy profiles of the Coma Cluster along the relatively relaxed directions are consistent with the power-law behavior expected from simple models of gravitational large-scale structure formation. The pressure is also in agreement at these radii with the expected values measured from Sunyaev-Zel'dovich data from the Planck satellite. However, due to the large uncertainties associated with the Coma Cluster measurements, we cannot yet exclude an entropy flattening in this system consistent with that seen in more relaxed cool core clusters.

The extreme blazar AO 0235+164 as seen by extensive ground and space radio observations

NASA Astrophysics Data System (ADS)

Kutkin, A. M.; Pashchenko, I. N.; Lisakov, M. M.; Voytsik, P. A.; Sokolovsky, K. V.; Kovalev, Y. Y.; Lobanov, A. P.; Ipatov, A. V.; Aller, M. F.; Aller, H. D.; Lahteenmaki, A.; Tornikoski, M.; Gurvits, L. I.

2018-04-01

Clues to the physical conditions in radio cores of blazars come from measurements of brightness temperatures as well as effects produced by intrinsic opacity. We study the properties of the ultra-compact blazar AO 0235+164 with RadioAstron ground-space radio interferometer, multifrequency VLBA, EVN, and single-dish radio observations. We employ visibility modelling and image stacking for deriving structure and kinematics of the source, and use Gaussian process regression to find the relative multiband time delays of the flares. The multifrequency core size and time lags support prevailing synchrotron self-absorption. The intrinsic brightness temperature of the core derived from ground-based very long baseline interferometry (VLBI) is close to the equipartition regime value. In the same time, there is evidence for ultra-compact features of the size of less than 10 μas in the source, which might be responsible for the extreme apparent brightness temperatures of up to 1014 K as measured by RadioAstron. In 2007-2016 the VLBI components in the source at 43 GHz are found predominantly in two directions, suggesting a bend of the outflow from southern to northern direction. The apparent opening angle of the jet seen in the stacked image at 43 GHz is two times wider than that at 15 GHz, indicating a collimation of the flow within the central 1.5 mas. We estimate the Lorentz factor Γ = 14, the Doppler factor δ = 21, and the viewing angle θ = 1.7° of the apparent jet base, derive the gradients of magnetic field strength and electron density in the outflow, and the distance between jet apex and the core at each frequency.

A MODEL FOR THE SOURCES OF THE SLOWLY VARYING COMPONENT OF MICROWAVE SOLAR RADIATION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Swarup, G.; Kakinuma, T.

1962-11-01

A comparison of the observations of the slowly varying component of the solar radio emission made with highresolution interferometers operating at wavelengths of 3.2, strong sources are higher at the longer wavelengths than at 3 cm. The same conclusion is derived from eclipse and statistical investigations, which indicate further that the spectrum of the flux density has a peak around 6 cm. The decrease in flux density with frequency cannot be explained simply by assuming a greater optical thickness for the extraordinary wave near 10 cm in the million-degree corona, as given by the magneto-ionic theory, since the observed degreemore » of polarization at 7.5 or 9.1 cm is much lower than that at 3.2 cm. It is suggested that radiation at the gyrofrequency and its harmonics emitted by the thermal electrons in the dense region over a sunspot group should be raken into account to explain the spectrum of the slowly varying component. This mechanism of resonance absorption requires the average strength of the magnetic field over the sunspot group to be about 800 gauss at a height of 2 x 10/sup 4/ km above the photosphere and 250 gauss at a height of 4 x 10/sup 4/ km. In order to explain the observed values of brightness temperature of 1/-4 x 10/sup 6/ deg K near 10 cm by the magneto-ionic theory, it is necessary to assume values of electron density of up to 20 or 40 times the normal. However, these high values of densities are not required by the gyro-theory, and values of five to ten times the normal are sufficient for explaining simultaneously the observations of brightness temperature, flux density, and polarization. This theory also explains the small size of the source in the range 3-10 cm. The radio emission is considered to originate thermally, which requires that the value of the electron temperature in the region of the inner solar corona above a large sunspot group is about 2-4 x 10 deg K. (auth)« less

Revised Correlation between Odin/OSIRIS PMC Properties and Coincident TIMED/SABER Mesospheric Temperatures

NASA Technical Reports Server (NTRS)

Feofilov, A. G.; Petelina, S V.; Kutepov, A. A.; Pesnell, W. D.; Goldberg, R. A.; Llewellyn, E. J.; Russell, J. M.

2006-01-01

The Optical Spectrograph and Infrared Imaging System (OSIRIS) instrument on board the Odin satellite detects Polar Mesospheric Clouds (PMCs) through the enhancement in the limb scattered solar radiance. The Sounding of the Atmosphere using the Broadband Emission Radiometry (SABER) instrument on board the TIMED satellite is a limb scanning infrared radiometer that measures temperature and vertical profiles and energetic parameters for minor constituents in the mesosphere and lower thermosphere. The combination of OSIRIS and SABER data has been previously used to statistically derive thermal conditions for PMC existence [Petelina et al., 2005]. In this work, we employ the simultaneous common volume measurements of PMCs by OSIRIS and temperature profiles measured by SABER for the Northern Hemisphere summers of 2002-2005 and corrected in the polar region by accounting for the vibrational-vibrational energy exchange among the CO2 isotopes [Kutepov et al., 2006]. For each of 20 coincidences identified within plus or minus 1 degree latitude, plus or minus 2 degrees longitude and less than 1 hour time the frost point temperatures were calculated using the corresponding SABER temperature profile and water vapor densities of 1,3, and 10 ppmv. We found that the PMC presence and brightness correlated only with the temperature threshold that corresponds to the frost point. The absolute value of the temperature below the frost point, however, didn't play a significant role in the intensity of PMC signal for the majority of selected coincidences. The presence of several bright clouds at temperatures above the frost point is obviously related to the limitation of the limb geometry when some near- or far-field PMCs located at higher (and warmer) altitudes appear to be at lower altitudes.

Revised Correlation between Odin/OSIRIS PMC Properties and Coincident TIMED/SABER Mesospheric Temperatures

NASA Technical Reports Server (NTRS)

Feofilov, A. G.; Petelina, S. V.; Kutepov, A. A.; Pesnell, W. D.; Goldberg, R. A.; Llewellyn, E. J.; Russell, J. M.

2006-01-01

The Optical Spectrograph and Infrared Imaging System (OSIRIS) instrument on board the Odin satellite detects Polar Mesospheric Clouds (PMCs) through the enhancement in the limb-scattered solar radiance. The Sounding of the Atmosphere using the Broadband Emission Radiometry (SABER) instrument on board the TIMED satellite is a limb scanning infrared radiometer that measures temperature and vertical profiles and energetic parameters for minor constituents in the mesosphere and lower thermosphere. The combination of OSIRIS and SABER data has been previously used to statistically derive thermal conditions for PMC existence [Petelina et al., 2005]. a, A.A. Kutepov, W.D. Pesnell, In this work, we employ the simultaneous common volume measurements of PMCs by OSIRIS and temperature profiles measured by SABER for the Northern Hemisphere summers of 2002-2005 and corrected in the polar region by accounting for the vibrational-vibrational energy exchange among the CO2 isotopes [Kutepov et al., 2006]. For each of 20 coincidences identified within plus or minus 1 degree latitude, plus or minus 2 degrees longitude and less than 1 hour time the frost point temperatures were calculated using the corresponding SABER temperature profile and water vapor densities of 1,3, and 10 ppmv. We found that the PMC presence and brightness correlated only with the temperature threshold that corresponds to the frost point. The absolute value of the temperature below the frost point, however, didn't play a significant role in the intensity of PMC signal for the majority of selected coincidences. The presence of several bright clouds at temperatures above the frost point is obviously related to the limitation of the limb geometry when some near- or far-field PMCs located at higher (and warmer) altitudes appear to be at lower altitudes.

Evaluation and Analysis of Seasat a Scanning Multichannel Microwave Radiometer (SMMR) Antenna Pattern Correction (APC) Algorithm

NASA Technical Reports Server (NTRS)

Kitzis, S. N.; Kitzis, J. L.

1979-01-01

The accuracy of the SEASAT-A SMMR antenna pattern correction (APC) algorithm was assessed. Interim APC brightness temperature measurements for the SMMR 6.6 GHz channels are compared with surface truth derived sea surface temperatures. Plots and associated statistics are presented for SEASAT-A SMMR data acquired for the Gulf of Alaska experiment. The cross-track gradients observed in the 6.6 GHz brightness temperature data are discussed.

Study of variability of permittivity and its mapping over lunar surface and subsurface using multisensors datasets

NASA Astrophysics Data System (ADS)

Calla, O. P. N.; Mathur, Shubhra; Gadri, Kishan Lal; Jangid, Monika

2016-12-01

In the present paper, permittivity maps of equatorial lunar surface are generated using brightness temperature (TB) data obtained from Microwave Radiometer (MRM) of Chang'e-1 and physical temperature (TP) data obtained from Diviner of Lunar Reconnaissance Orbiter (LRO). Here, permittivity mapping is not carried out above 60° latitudes towards the lunar poles due to large anomaly in the physical temperature obtained from the Diviner. Microwave frequencies, which are used to generate these maps are 3 GHz, 7.8 GHz, 19.35 GHz and 37 GHz. Permittivity values are simulated using TB values at these four frequencies. Here, weighted average of physical temperature obtained from Diviner are used to compute permittivity at each microwave frequencies. Longer wavelengths of microwave signals give information of more deeper layers of the lunar surface as compared to smaller wavelength. Initially, microwave emissivity is estimated using TB values from MRM and physical temperature (TP) from Diviner. From estimated emissivity the real part of permittivity (ε), is calculated using Fresnel equations. The permittivity maps of equatorial lunar surface is generated. The simulated permittivity values are normalized with respect to density for easy comparison of simulated permittivity values with the permittivity values of Apollo samples as well as with the permittivity values of Terrestrial Analogue of Lunar Soil (TALS) JSC-1A. Lower value of dielectric constant (ε‧) indicates that the corresponding lunar surface is smooth and doesn't have rough rocky terrain. Thus a future lunar astronaut can use these data to decide proper landing site for future lunar missions. The results of this paper will serve as input to future exploration of lunar surface.

Use of geostationary meteorological satellite images in convective rain estimation for flash-flood forecasting

NASA Astrophysics Data System (ADS)

Wardah, T.; Abu Bakar, S. H.; Bardossy, A.; Maznorizan, M.

2008-07-01

SummaryFrequent flash-floods causing immense devastation in the Klang River Basin of Malaysia necessitate an improvement in the real-time forecasting systems being used. The use of meteorological satellite images in estimating rainfall has become an attractive option for improving the performance of flood forecasting-and-warning systems. In this study, a rainfall estimation algorithm using the infrared (IR) information from the Geostationary Meteorological Satellite-5 (GMS-5) is developed for potential input in a flood forecasting system. Data from the records of GMS-5 IR images have been retrieved for selected convective cells to be trained with the radar rain rate in a back-propagation neural network. The selected data as inputs to the neural network, are five parameters having a significant correlation with the radar rain rate: namely, the cloud-top brightness-temperature of the pixel of interest, the mean and the standard deviation of the temperatures of the surrounding five by five pixels, the rate of temperature change, and the sobel operator that indicates the temperature gradient. In addition, three numerical weather prediction (NWP) products, namely the precipitable water content, relative humidity, and vertical wind, are also included as inputs. The algorithm is applied for the areal rainfall estimation in the upper Klang River Basin and compared with another technique that uses power-law regression between the cloud-top brightness-temperature and radar rain rate. Results from both techniques are validated against previously recorded Thiessen areal-averaged rainfall values with coefficient correlation values of 0.77 and 0.91 for the power-law regression and the artificial neural network (ANN) technique, respectively. An extra lead time of around 2 h is gained when the satellite-based ANN rainfall estimation is coupled with a rainfall-runoff model to forecast a flash-flood event in the upper Klang River Basin.

The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Implications for Spectral Line Intensity Mapping at Millimeter Wavelengths and CMB Spectral Distortions

NASA Astrophysics Data System (ADS)

Carilli, C. L.; Chluba, J.; Decarli, R.; Walter, F.; Aravena, M.; Wagg, J.; Popping, G.; Cortes, P.; Hodge, J.; Weiss, A.; Bertoldi, F.; Riechers, D.

2016-12-01

We present direct estimates of the mean sky brightness temperature in observing bands around 99 and 242 GHz due to line emission from distant galaxies. These values are calculated from the summed line emission observed in a blind, deep survey for spectral line emission from high redshift galaxies using ALMA (the ALMA spectral deep field observations “ASPECS” survey). In the 99 GHz band, the mean brightness will be dominated by rotational transitions of CO from intermediate and high redshift galaxies. In the 242 GHz band, the emission could be a combination of higher order CO lines, and possibly [C II] 158 μm line emission from very high redshift galaxies (z ˜ 6-7). The mean line surface brightness is a quantity that is relevant to measurements of spectral distortions of the cosmic microwave background, and as a potential tool for studying large-scale structures in the early universe using intensity mapping. While the cosmic volume and the number of detections are admittedly small, this pilot survey provides a direct measure of the mean line surface brightness, independent of conversion factors, excitation, or other galaxy formation model assumptions. The mean surface brightness in the 99 GHZ band is: T B = 0.94 ± 0.09 μK. In the 242 GHz band, the mean brightness is: T B = 0.55 ± 0.033 μK. These should be interpreted as lower limits on the average sky signal, since we only include lines detected individually in the blind survey, while in a low resolution intensity mapping experiment, there will also be the summed contribution from lower luminosity galaxies that cannot be detected individually in the current blind survey.

Extracting Galaxy Cluster Gas Inhomogeneity from X-Ray Surface Brightness: A Statistical Approach and Application to Abell 3667

NASA Astrophysics Data System (ADS)

Kawahara, Hajime; Reese, Erik D.; Kitayama, Tetsu; Sasaki, Shin; Suto, Yasushi

2008-11-01

Our previous analysis indicates that small-scale fluctuations in the intracluster medium (ICM) from cosmological hydrodynamic simulations follow the lognormal probability density function. In order to test the lognormal nature of the ICM directly against X-ray observations of galaxy clusters, we develop a method of extracting statistical information about the three-dimensional properties of the fluctuations from the two-dimensional X-ray surface brightness. We first create a set of synthetic clusters with lognormal fluctuations around their mean profile given by spherical isothermal β-models, later considering polytropic temperature profiles as well. Performing mock observations of these synthetic clusters, we find that the resulting X-ray surface brightness fluctuations also follow the lognormal distribution fairly well. Systematic analysis of the synthetic clusters provides an empirical relation between the three-dimensional density fluctuations and the two-dimensional X-ray surface brightness. We analyze Chandra observations of the galaxy cluster Abell 3667, and find that its X-ray surface brightness fluctuations follow the lognormal distribution. While the lognormal model was originally motivated by cosmological hydrodynamic simulations, this is the first observational confirmation of the lognormal signature in a real cluster. Finally we check the synthetic cluster results against clusters from cosmological hydrodynamic simulations. As a result of the complex structure exhibited by simulated clusters, the empirical relation between the two- and three-dimensional fluctuation properties calibrated with synthetic clusters when applied to simulated clusters shows large scatter. Nevertheless we are able to reproduce the true value of the fluctuation amplitude of simulated clusters within a factor of 2 from their two-dimensional X-ray surface brightness alone. Our current methodology combined with existing observational data is useful in describing and inferring the statistical properties of the three-dimensional inhomogeneity in galaxy clusters.

Understanding Climate Trends Using IR Brightness Temperature Spectra from AIRS, IASI and CrIS

NASA Astrophysics Data System (ADS)

Deslover, D. H.; Nikolla, E.; Knuteson, R. O.; Revercomb, H. E.; Tobin, D. C.

2016-12-01

NASA's Atmospheric Infrared Sounder (AIRS) provides a data record that extends from its 2002 launch to the present. The Infrared Atmospheric Sounding Interferometer (IASI) onboard Metop- (A launched in 2006, B in 2012), as well as the Joint Polar Satellite System (JPSS) Cross-track Infrared Sounder (CrIS) launched in 2011, complement this data record. Future infrared sounders with similar capabilities will augment these measurements into the near future. We have created a global data set from these infrared measurements, using the nadir-most observations for each of the aforementioned instruments. We can filter the data based upon spatial, diurnal and seasonal properties to discern trends for a given spectral channel and, therefore, a specific atmospheric layer. Subtle differences between spectral sampling among the three instruments can lead significant differences in the resultant probability distribution functions for similar spectral channels. We take advantage of the higher (0.25 cm-1) IASI spectral resolution to subsample the IASI spectra onto AIRS and CrIS spectral grids to better compare AIRS/IASI and CrIS/IASI trends in the brightness temperature anomalies. To better understand the dependance of trace gases on the measured brightness temperature spectral time-series, a companion study has utilized coincident vertical profiles of stratospheric carbon dioxide, water vapor and ozone concentration are used to infer a correlation with the CrIS brightness temperatures. The goal was to investigate the role of ozone heating and carbon dioxide cooling on the observed brightness temperature spectra. Results from that study will be presented alongside the climate trend analysis.

Microwave signatures of ice hydrometeors from ground-based observations above Summit, Greenland

DOE PAGES

Pettersen, Claire; Bennartz, Ralf; Kulie, Mark S.; ...

2016-04-15

Multi-instrument, ground-based measurements provide unique and comprehensive data sets of the atmosphere for a specific location over long periods of time and resulting data compliment past and existing global satellite observations. Our paper explores the effect of ice hydrometeors on ground-based, high-frequency passive microwave measurements and attempts to isolate an ice signature for summer seasons at Summit, Greenland, from 2010 to 2013. Furthermore, data from a combination of passive microwave, cloud radar, radiosonde, and ceilometer were examined to isolate the ice signature at microwave wavelengths. By limiting the study to a cloud liquid water path of 40 g m -2more » or less, the cloud radar can identify cases where the precipitation was dominated by ice. These cases were examined using liquid water and gas microwave absorption models, and brightness temperatures were calculated for the high-frequency microwave channels: 90, 150, and 225GHz. By comparing the measured brightness temperatures from the microwave radiometers and the calculated brightness temperature using only gas and liquid contributions, any residual brightness temperature difference is due to emission and scattering of microwave radiation from the ice hydrometeors in the column. The ice signature in the 90, 150, and 225 GHz channels for the Summit Station summer months was isolated. Then, this measured ice signature was compared to an equivalent brightness temperature difference calculated with a radiative transfer model including microwave single-scattering properties for several ice habits. Furthermore, initial model results compare well against the 4 years of summer season isolated ice signature in the high-frequency microwave channels.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pettersen, Claire; Bennartz, Ralf; Kulie, Mark S.

Multi-instrument, ground-based measurements provide unique and comprehensive data sets of the atmosphere for a specific location over long periods of time and resulting data compliment past and existing global satellite observations. Our paper explores the effect of ice hydrometeors on ground-based, high-frequency passive microwave measurements and attempts to isolate an ice signature for summer seasons at Summit, Greenland, from 2010 to 2013. Furthermore, data from a combination of passive microwave, cloud radar, radiosonde, and ceilometer were examined to isolate the ice signature at microwave wavelengths. By limiting the study to a cloud liquid water path of 40 g m -2more » or less, the cloud radar can identify cases where the precipitation was dominated by ice. These cases were examined using liquid water and gas microwave absorption models, and brightness temperatures were calculated for the high-frequency microwave channels: 90, 150, and 225GHz. By comparing the measured brightness temperatures from the microwave radiometers and the calculated brightness temperature using only gas and liquid contributions, any residual brightness temperature difference is due to emission and scattering of microwave radiation from the ice hydrometeors in the column. The ice signature in the 90, 150, and 225 GHz channels for the Summit Station summer months was isolated. Then, this measured ice signature was compared to an equivalent brightness temperature difference calculated with a radiative transfer model including microwave single-scattering properties for several ice habits. Furthermore, initial model results compare well against the 4 years of summer season isolated ice signature in the high-frequency microwave channels.« less

MWRRET Value-Added Product: The Retrieval of Liquid Water Path and Precipitable Water Vapor from Microwave Radiometer (MWR) Datasets May 2009

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gaustad, KL; Turner, DD

2009-05-30

This report provides a short description of the Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF) microwave radiometer (MWR) RETrievel (MWRRET) value-added product (VAP) algorithm. This algorithm utilizes a complementary physical retrieval method and applies brightness temperature offsets to reduce spurious liquid water path (LWP) bias in clear skies resulting in significantly improved precipitable water vapor (PWV) and LWP retrievals. We present a general overview of the technique, input parameters, output products, and describe data quality checks. A more complete discussion of the theory and results is given in Turner et al. (2007b).

MWRRET Value-Added Product: The Retrieval of Liquid Water Path and Precipitable Water Vapor from Microwave Radiometer (MWR) Data Sets (Revision 2)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gaustad, KL; Turner, DD; McFarlane, SA

2011-07-25

This report provides a short description of the Atmospheric Radiation Measurement (ARM) Climate Research Facility microwave radiometer (MWR) Retrieval (MWRRET) value-added product (VAP) algorithm. This algorithm utilizes a complementary physical retrieval method and applies brightness temperature offsets to reduce spurious liquid water path (LWP) bias in clear skies resulting in significantly improved precipitable water vapor (PWV) and LWP retrievals. We present a general overview of the technique, input parameters, output products, and describe data quality checks. A more complete discussion of the theory and results is given in Turner et al. (2007b).

Estimates of primary productivity over the Thar Desert based upon Nimbus-7 37 GHz data - 1979-1985

NASA Technical Reports Server (NTRS)

Choudhury, B. J.

1987-01-01

An empirical relationship has been determined between the difference of vertically and horizontally polarized brightness temperatures noted at the 37 GHz frequency of the Nimbus-7 SMMR and primary productivity over hot arid and semiarid regions of Africa and Australia. This empirical relationship is applied to estimate the primary productivity over the Thar Desert between 1979 and 1985, giving an average value of 0.271 kg/sq m per yr. The spatial variability of the productivity values is found to be quite significant, with a standard deviation about the mean of 0.08 kg/sq m per yr.

Tolerance of image enhancement brightness and contrast in lateral cephalometric digital radiography for Steiner analysis

NASA Astrophysics Data System (ADS)

Rianti, R. A.; Priaminiarti, M.; Syahraini, S. I.

2017-08-01

Image enhancement brightness and contrast can be adjusted on lateral cephalometric digital radiographs to improve image quality and anatomic landmarks for measurement by Steiner analysis. To determine the limit value for adjustments of image enhancement brightness and contrast in lateral cephalometric digital radiography for Steiner analysis. Image enhancement brightness and contrast were adjusted on 100 lateral cephalometric radiography in 10-point increments (-30, -20, -10, 0, +10, +20, +30). Steiner analysis measurements were then performed by two observers. Reliabilities were tested by the Interclass Correlation Coefficient (ICC) and significance tested by ANOVA or the Kruskal Wallis test. No significant differences were detected in lateral cephalometric analysis measurements following adjustment of the image enhancement brightness and contrast. The limit value of adjustments of the image enhancement brightness and contrast associated with incremental 10-point changes (-30, -20, -10, 0, +10, +20, +30) does not affect the results of Steiner analysis.

Effect of a single 3-hour exposure to bright light on core body temperature and sleep in humans.

PubMed

Dijk, D J; Cajochen, C; Borbély, A A

1991-01-02

Seven human subjects were exposed to bright light (BL, approx. 2500 lux) and dim light (DL, approx. 6 lux) during 3 h prior to nocturnal sleep, in a cross-over design. At the end of the BL exposure period core body temperature was significantly higher than at the end of the DL exposure period. The difference in core body temperature persisted during the first 4 h of sleep. The latency to sleep onset was increased after BL exposure. Rapid-eye movement sleep (REMS) and slow-wave sleep (SWS; stage 3 + 4 of non-REMS) were not significantly changed. Eight subjects were exposed to BL from 20.30 to 23.30 h while their eyes were covered or uncovered. During BL exposure with uncovered eyes, core body temperature decreased significantly less than during exposure with covered eyes. We conclude that bright light immediately affects core body temperature and that this effect is mediated via the eyes.

Evaluation of AIRS, MODIS, and HIRS 11 Micron Brightness Temperature Difference Changes from 2002 through 2006

NASA Technical Reports Server (NTRS)

Broberg, Steven E.; Aumann, Hartmut H.; Gregorich, David T.; Xiong, X.

2006-01-01

In an effort to validate the accuracy and stability of AIRS data at low scene temperatures (200-250 K range), we evaluated brightness temperatures at 11 microns with Aqua MODIS band 31 and HIRS/3 channel 8 for Antarctic granules between September 2002 and May 2006. We found excellent agreement with MODIS (at the 0.2 K level) over the full emperature range in data from early in the Aqua mission. However, in more recent data, starting in April 2005, we found a scene temperature dependence in MODIS-AIRS brightness temperature differences, with a discrepancy of 1- 1.5 K at 200 K. The comparison between AIRS and HIRS/3 (channel 8) on NOAA 16 for the same time period yields excellent agreement. The cause and time dependence of the disagreement with MODIS is under evaluation, but the change was coincident with a change in the MODIS production software from collection 4 to 5.

Monitoring of deep brain temperature in infants using multi-frequency microwave radiometry and thermal modelling.

PubMed

Han, J W; Van Leeuwen, G M; Mizushina, S; Van de Kamer, J B; Maruyama, K; Sugiura, T; Azzopardi, D V; Edwards, A D

2001-07-01

In this study we present a design for a multi-frequency microwave radiometer aimed at prolonged monitoring of deep brain temperature in newborn infants and suitable for use during hypothermic neural rescue therapy. We identify appropriate hardware to measure brightness temperature and evaluate the accuracy of the measurements. We describe a method to estimate the tissue temperature distribution from measured brightness temperatures which uses the results of numerical simulations of the tissue temperature as well as the propagation of the microwaves in a realistic detailed three-dimensional infant head model. The temperature retrieval method is then used to evaluate how the statistical fluctuations in the measured brightness temperatures limit the confidence interval for the estimated temperature: for an 18 degrees C temperature differential between cooled surface and deep brain we found a standard error in the estimated central brain temperature of 0.75 degrees C. Evaluation of the systematic errors arising from inaccuracies in model parameters showed that realistic deviations in tissue parameters have little impact compared to uncertainty in the thickness of the bolus between the receiving antenna and the infant's head or in the skull thickness. This highlights the need to pay particular attention to these latter parameters in future practical implementation of the technique.

Brightness temperature and attenuation statistics at 20.6 and 31.65 GHz

NASA Technical Reports Server (NTRS)

Westwater, Edgeworth R.; Falls, M. J.

1991-01-01

Attenuation and brightness temperature statistics at 20.6 and 31.65 GHz are analyzed for a year's worth of data. The data were collected in 1988 at Denver and Platteville, Colorado. The locations are separated by 49 km. Single-station statistics are derived for the entire year. Quality control procedures are discussed and examples of their application are given.

Real Time Monitoring of Flooding from Microwave Satellite Observations

NASA Technical Reports Server (NTRS)

Galantowicz, John F.; Frey, H. (Technical Monitor)

2001-01-01

In this report, we review the progress to date including results from data analyses and present a schedule of milestones for the remainder of the project. We discuss the processing of flood extent data and SSM/I brightness temperature data for the 1993 Midwest Flood. We present preliminary results from the derivation of open water fraction from brightness temperatures.

Inventory of File nam.t00z.goes24300.tm00.grib2

Science.gov Websites

of Records: 4 Number Level/Layer Parameter Forecast Valid Description 001 top of atmosphere SBT122 analysis Simulated Brightness Temperature for GOES 12, Channel 2 [K] 002 top of atmosphere SBT123 analysis Simulated Brightness Temperature for GOES 12, Channel 3 [K] 003 top of atmosphere SBT124 analysis Simulated

Inventory of File nam.t00z.goes21800.tm00.grib2

Science.gov Websites

of Records: 4 Number Level/Layer Parameter Forecast Valid Description 001 top of atmosphere SBT122 analysis Simulated Brightness Temperature for GOES 12, Channel 2 [K] 002 top of atmosphere SBT123 analysis Simulated Brightness Temperature for GOES 12, Channel 3 [K] 003 top of atmosphere SBT124 analysis Simulated

Inventory of File nam.t00z.goes22100.tm00.grib2

Science.gov Websites

of Records: 4 Number Level/Layer Parameter Forecast Valid Description 001 top of atmosphere SBT122 analysis Simulated Brightness Temperature for GOES 12, Channel 2 [K] 002 top of atmosphere SBT123 analysis Simulated Brightness Temperature for GOES 12, Channel 3 [K] 003 top of atmosphere SBT124 analysis Simulated

ACCELERATION OF COMPACT RADIO JETS ON SUB-PARSEC SCALES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Sang-Sung; Lobanov, Andrei P.; Krichbaum, Thomas P.

2016-08-01

Jets of compact radio sources are highly relativistic and Doppler boosted, making studies of their intrinsic properties difficult. Observed brightness temperatures can be used to study the intrinsic physical properties of relativistic jets, and constrain models of jet formation in the inner jet region. We aim to observationally test such inner jet models. The very long baseline interferometry (VLBI) cores of compact radio sources are optically thick at a given frequency. The distance of the core from the central engine is inversely proportional to the frequency. Under the equipartition condition between the magnetic field energy and particle energy densities, themore » absolute distance of the VLBI core can be predicted. We compiled the brightness temperatures of VLBI cores at various radio frequencies of 2, 8, 15, and 86 GHz. We derive the brightness temperature on sub-parsec scales in the rest frame of the compact radio sources. We find that the brightness temperature increases with increasing distance from the central engine, indicating that the intrinsic jet speed (the Lorentz factor) increases along the jet. This implies that the jets are accelerated in the (sub-)parsec regions from the central engine.« less

Titan's surface from Cassini RADAR SAR and high resolution radiometry data of the first five flybys

USGS Publications Warehouse

Paganelli, F.; Janssen, M.A.; Stiles, B.; West, R.; Lorenz, R.D.; Lunine, J.I.; Wall, S.D.; Callahan, P.; Lopes, R.M.; Stofan, E.; Kirk, R.L.; Johnson, W.T.K.; Roth, L.; Elachi, C.; ,

2007-01-01

The first five Titan flybys with Cassini's Synthetic Aperture RADAR (SAR) and radiometer are examined with emphasis on the calibration and interpretation of the high-resolution radiometry data acquired during the SAR mode (SAR-radiometry). Maps of the 2-cm wavelength brightness temperature are obtained coincident with the SAR swath imaging, with spatial resolution approaching 6 km. A preliminary calibration shows that brightness temperature in these maps varies from 64 to 89 K. Surface features and physical properties derived from the SAR-radiometry maps and SAR imaging are strongly correlated; in general, we find that surface features with high radar reflectivity are associated with radiometrically cold regions, while surface features with low radar reflectivity correlate with radiometrically warm regions. We examined scatterplots of the normalized radar cross-section ??0 versus brightness temperature, finding differing signatures that characterize various terrains and surface features. Implications for the physical and compositional properties of these features are discussed. The results indicate that volume scattering is important in many areas of Titan's surface, particularly Xanadu, while other areas exhibit complex brightness temperature variations consistent with variable slopes or surface material and compositional properties. ?? 2007 Elsevier Inc.

Nist Microwave Blackbody: The Design, Testing, and Verification of a Conical Brightness Temperature Source

NASA Astrophysics Data System (ADS)

Houtz, Derek Anderson

Microwave radiometers allow remote sensing of earth and atmospheric temperatures from space, anytime, anywhere, through clouds, and in the dark. Data from microwave radiometers are high-impact operational inputs to weather forecasts, and are used to provide a vast array of climate data products including land and sea surface temperatures, soil moisture, ocean salinity, cloud precipitation and moisture height profiles, and even wind speed and direction, to name a few. Space-borne microwave radiometers have a major weakness when it comes to long-term climate trends due to their lack of traceability. Because there is no standard, or absolute reference, for microwave brightness temperature, nationally or internationally, individual instruments must each rely on their own internal calibration source to set an absolute reference to the fundamental unit of Kelvin. This causes each subsequent instrument to have a calibration offset and there is no 'true' reference. The work introduced in this thesis addresses this vacancy by proposing and introducing a NIST microwave brightness temperature source that may act as the primary reference. The NIST standard will allow pre-launch calibration of radiometers across a broad range of remote sensing pertinent frequencies between 18 GHz and 220 GHz. The blackbody will be capable of reaching temperatures ranging between liquid nitrogen boiling at approximately 77 K and warm-target temperature of 350 K. The brightness temperature of the source has associated standard uncertainty ranging as a function of frequency between 0.084 K and 0.111 K. The standard can be transferred to the calibration source in the instrument, providing traceability of all subsequent measurements back to the primary standard. The development of the NIST standard source involved predicting and measuring its brightness temperature, and minimizing the associated uncertainty of this quantity. Uniform and constant physical temperature along with well characterized and maximized emissivity are fundamental to a well characterized blackbody. The chosen geometry is a microwave absorber coated copper cone. Electromagnetic and thermal simulations are introduced to optimize the design. Experimental verifications of the simulated quantities confirm the predicted performance of the blackbody.

Detection of secondary eclipses of WASP-10b and Qatar-1b in the Ks band and the correlation between Ks-band temperature and stellar activity.

NASA Astrophysics Data System (ADS)

Cruz, Patricia; Barrado, David; Lillo-Box, Jorge; Diaz, Marcos; López-Morales, Mercedes; Birkby, Jayne; Fortney, Jonathan J.; Hodgkin, Simon

2017-10-01

The Calar Alto Secondary Eclipse study was a program dedicated to observe secondary eclipses in the near-IR of two known close-orbiting exoplanets around K-dwarfs: WASP-10b and Qatar-1b. Such observations reveal hints on the orbital configuration of the system and on the thermal emission of the exoplanet, which allows the study of the brightness temperature of its atmosphere. The observations were performed at the Calar Alto Observatory (Spain). We used the OMEGA2000 instrument (Ks band) at the 3.5m telescope. The data was acquired with the telescope strongly defocused. The differential light curve was corrected from systematic effects using the Principal Component Analysis (PCA) technique. The final light curve was fitted using an occultation model to find the eclipse depth and a possible phase shift by performing a MCMC analysis. The observations have revealed a secondary eclipse of WASP-10b with depth of 0.137%, and a depth of 0.196% for Qatar-1b. The observed phase offset from expected mid-eclipse was of -0.0028 for WASP-10b, and of -0.0079 for Qatar-1b. These measured offsets led to a value for |ecosω| of 0.0044 for the WASP-10b system, leading to a derived eccentricity which was too small to be of any significance. For Qatar-1b, we have derived a |ecosω| of 0.0123, however, this last result needs to be confirmed with more data. The estimated Ks-band brightness temperatures are of 1647 K and 1885 K for WASP-10b and Qatar-1b, respectively. We also found an empirical correlation between the (R'HK) activity index of planet hosts and the Ks-band brightness temperature of exoplanets, considering a small number of systems.

Estimation and analysis of interannual variations in tropical oceanic rainfall using data from SSM/I

NASA Technical Reports Server (NTRS)

Berg, Wesley

1992-01-01

Rainfall over tropical ocean regions, particularly in the tropical Pacific, is estimated using Special Sensor Microwave/Imager (SSM/I) data. Instantaneous rainfall estimates are derived from brightness temperature values obtained from the satellite data using the Hughes D-Matrix algorithm. Comparisons with other satellite techniques are made to validate the SSM/I results for the tropical Pacific. The correlation coefficients are relatively high for the three data sets investigated, especially for the annual case.

A comparison of three regions of Puppis A

NASA Technical Reports Server (NTRS)

Fischbach, K. F.; Bateman, L. M.; Canizares, C. R.; Markert, T. H.; Saez, P. J.

1990-01-01

High resolution X-ray spectral observations of Puppis A were performed with the FPCS on the Einstein Observatory at three regions of the remnant: the shock front, the bright eastern knot, and the interior. Plasma diagnostics of lines from OVII and OVIII constrain the values of electron temperature, ionization timescale, and hydrogen column density. Results of the diagnostics for these three regions are compared. A nonequilibrium analysis of previously published fluxes of oxygen lines shows that the interior has not yet reached ionization equilibrium.

Titan Surface Temperatures as Measured by Cassini CIRS

NASA Technical Reports Server (NTRS)

Jennings, Donald E.; Flasar, F.M.; Kunde, V.G.; Nixon, C.A.; Romani, P.N.; Samuelson, R.E.; Coustenis, A.; Courtin, R.

2009-01-01

Thermal radiation from the surface of Titan reaches space through a spectral window of low opacity at 19-microns wavelength. This radiance gives a measure of the brightness temperature of the surface. Composite Infrared Spectrometer' (CIRS) observations from Cassini during its first four years at Saturn have permitted latitude mapping of zonally averaged surface temperatures. The measurements are corrected for atmospheric opacity using the dependence of radiance on emission angle. With the more complete latitude coverage and much larger dataset of CIRS we have improved upon the original results from Voyager IRIS. CIRS measures the equatorial surface brightness temperature to be 93.7+/-0.6 K, the same as the temperature measured at the Huygens landing site. The surface brightness temperature decreases by 2 K toward the south pole and by 3 K toward the north pole. The drop in surface temperature between equator and north pole implies a 50% decrease in methane saturation vapor pressure and relative humidity; this may help explain the large northern lakes. The H2 mole fraction is derived as a by-product of our analysis and agrees with previous results. Evidence of seasonal variation in surface and atmospheric temperatures is emerging from CIRS measurements over the Cassini mission.

Coronal bright points at 6cm wavelength

NASA Technical Reports Server (NTRS)

Fu, Qijun; Kundu, M. R.; Schmahl, E. J.

1988-01-01

Results are presented from observations of bright points at a wavelength of 6-cm using the VLA with a spatial resolution of 1.2 arcsec. During two hours of observations, 44 sources were detected with brightness temperatures between 2000 and 30,000 K. Of these sources, 27 are associated with weak dark He 10830 A features at distances less than 40 arcsecs. Consideration is given to variations in the source parameters and the relationship between ephemeral regions and bright points.

Snowpack monitoring in North America and Eurasia using passive microwave satellite data

NASA Technical Reports Server (NTRS)

Foster, J. L.; Rango, A.; Hall, D. K.; Chang, A. T. C.; Allison, L. J.; Diesen, B. C., III

1980-01-01

Areas of the Canadian high plains, the Montana and North Dakota high plains, and the steppes of central Russia have been studied in an effort to determine the utility of spaceborne microwave radiometers for monitoring snow depths in different geographic areas. Significant regression relationships between snow depth and microwave brightness temperatures were developed for each of these homogeneous areas. In each of the study areas investigated in this paper, Nimbus-6 (0.81 cm) ESMR data produced higher correlations than Nimbus-5 (1.55 cm) ESMR data in relating microwave brightness temperature to snow depth. It is difficult to extrapolate relationships between microwave brightness temperature and snow depth from one area to another because different geographic areas are likely to have different snowpack conditions.

New Observations of Subarcsecond Photospheric Bright Points

NASA Technical Reports Server (NTRS)

Berger, T. E.; Schrijver, C. J.; Shine, R. A.; Tarbell, T. D.; Title, A. M.; Scharmer, G.

1995-01-01

We have used an interference filter centered at 4305 A within the bandhead of the CH radical (the 'G band') and real-time image selection at the Swedish Vacuum Solar Telescope on La Palma to produce very high contrast images of subarcsecond photospheric bright points at all locations on the solar disk. During the 6 day period of 15-20 Sept. 1993 we observed active region NOAA 7581 from its appearance on the East limb to a near-disk-center position on 20 Sept. A total of 1804 bright points were selected for analysis from the disk center image using feature extraction image processing techniques. The measured FWHM distribution of the bright points in the image is lognormal with a modal value of 220 km (0.30 sec) and an average value of 250 km (0.35 sec). The smallest measured bright point diameter is 120 km (0.17 sec) and the largest is 600 km (O.69 sec). Approximately 60% of the measured bright points are circular (eccentricity approx. 1.0), the average eccentricity is 1.5, and the maximum eccentricity corresponding to filigree in the image is 6.5. The peak contrast of the measured bright points is normally distributed. The contrast distribution variance is much greater than the measurement accuracy, indicating a large spread in intrinsic bright-point contrast. When referenced to an averaged 'quiet-Sun' area in the image, the modal contrast is 29% and the maximum value is 75%; when referenced to an average intergranular lane brightness in the image, the distribution has a modal value of 61% and a maximum of 119%. The bin-averaged contrast of G-band bright points is constant across the entire measured size range. The measured area of the bright points, corrected for pixelation and selection effects, covers about 1.8% of the total image area. Large pores and micropores occupy an additional 2% of the image area, implying a total area fraction of magnetic proxy features in the image of 3.8%. We discuss the implications of this area fraction measurement in the context of previously published measurements which show that typical active region plage has a magnetic filling factor on the order of 10% or greater. The results suggest that in the active region analyzed here, less than 50% of the small-scale magnetic flux tubes are demarcated by visible proxies such as bright points or pores.

In-flight calibration/validation of the ENVISAT/MWR

NASA Astrophysics Data System (ADS)

Tran, N.; Obligis, E.; Eymard, L.

2003-04-01

Retrieval algorithms for wet tropospheric correction, integrated vapor and liquid water contents, atmospheric attenuations of backscattering coefficients in Ku and S band, have been developed using a database of geophysical parameters from global analyses from a meteorological model and corresponding simulated brightness temperatures and backscattering cross-sections by a radiative transfer model. Meteorological data correspond to 12 hours predictions from the European Center for Medium range Weather Forecasts (ECMWF) model. Relationships between satellite measurements and geophysical parameters are determined using a statistical method. The quality of the retrieval algorithms depends therefore on the representativity of the database, the accuracy of the radiative transfer model used for the simulations and finally on the quality of the inversion model. The database has been built using the latest version of the ECMWF forecast model, which has been operationally run since November 2000. The 60 levels in the model allow a complete description of the troposphere/stratosphere profiles and the horizontal resolution is now half of a degree. The radiative transfer model is the emissivity model developed at the Université Catholique de Louvain [Lemaire, 1998], coupled to an atmospheric model [Liebe et al, 1993] for gaseous absorption. For the inversion, we have replaced the classical log-linear regression with a neural networks inversion. For Envisat, the backscattering coefficient in Ku band is used in the different algorithms to take into account the surface roughness as it is done with the 18 GHz channel for the TOPEX algorithms or an additional term in wind speed for ERS2 algorithms. The in-flight calibration/validation of the Envisat radiometer has been performed with the tuning of 3 internal parameters (the transmission coefficient of the reflector, the sky horn feed transmission coefficient and the main antenna transmission coefficient). First an adjustment of the ERS2 brightness temperatures to the simulations for the 2000/2001 version of the ECMWF model has been applied. Then, Envisat brightness temperatures have been calibrated on these adjusted ERS2 values. The advantages of this calibration approach are that : i) such a method provides the relative discrepancy with respect to the simulation chain. The results, obtained simultaneously for several radiometers (we repeat the same analyze with TOPEX and JASON radiometers), can be used to detect significant calibration problems, more than 2 3 K). ii) the retrieval algorithms have been developed using the same meteorological model (2000/2001 version of the ECMWF model), and the same radiative transfer model than the calibration process, insuring the consistency between calibration and retrieval processing. Retrieval parameters are then optimized. iii) the calibration of the Envisat brightness temperatures over the 2000/2001 version of the ECMWF model, as well as the recommendation to use the same model as a reference to correct ERS2 brightness temperatures, allow the use of the same retrieval algorithms for the two missions, providing the continuity between the two. iv) by comparison with other calibration methods (such as systematic calibration of an instrument or products by using respectively the ones from previous mission), this method is more satisfactory since improvements in terms of technology, modelisation, retrieval processing are taken into account. For the validation of the brightness temperatures, we use either a direct comparison with measurements provided by other instruments in similar channel, or the monitoring over stable areas (coldest ocean points, stable continental areas). The validation of the wet tropospheric correction can be also provided by comparison with other radiometer products, but the only real validation rely on the comparison between in-situ measurements (performed by radiosonding) and retrieved products in coincidence.

Soil Moisture Active/Passive (SMAP) Forward Brightness Temperature Simulator

NASA Technical Reports Server (NTRS)

Peng, Jinzheng; Peipmeier, Jeffrey; Kim, Edward

2012-01-01

The SMAP is one of four first-tier missions recommended by the US National Research Council's Committee on Earth Science and Applications from Space (Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond, Space Studies Board, National Academies Press, 2007) [1]. It is to measure the global soil moisture and freeze/thaw from space. One of the spaceborne instruments is an L-band radiometer with a shared single feedhorn and parabolic mesh reflector. While the radiometer measures the emission over a footprint of interest, unwanted emissions are also received by the antenna through the antenna sidelobes from the cosmic background and other error sources such as the Sun, the Moon and the galaxy. Their effects need to be considered accurately, and the analysis of the overall performance of the radiometer requires end-to-end performance simulation from Earth emission to antenna brightness temperature, such as the global simulation of L-band brightness temperature simulation over land and sea [2]. To assist with the SMAP radiometer level 1B algorithm development, the SMAP forward brightness temperature simulator is developed by adapting the Aquarius simulator [2] with necessary modifications. This poster presents the current status of the SMAP forward brightness simulator s development including incorporating the land microwave emission model and its input datasets, and a simplified atmospheric radiative transfer model. The latest simulation results are also presented to demonstrate the ability of supporting the SMAP L1B algorithm development.

Crystal zoning in a large-volume ignimbrite: constraints on the thermal history of a supervolcano magma system

NASA Astrophysics Data System (ADS)

Matthews, N. E.; Pyle, D. M.; Wilson, C. J.

2009-12-01

Chemical zoning of crystals provides an important archive of information that allows for the reconstruction of complex thermal histories and changes in melt composition of the magma reservoir during crystallization. Here we investigate cathodoluminescence (CL) and Ti zonation in quartz crystals extracted from pumices from the Whakamaru and Rangitaiki ignimbrite units (part of the large-volume Whakamaru Group Ignimbrites), New Zealand, to reconstruct the thermal history of the parent magma chamber(s). CL intensity images are taken as a proxy for Ti content and temperature variation during crystal growth, and direct estimates of temperature are made using the TitaniQ geothermometer (Wark & Watson 2006 Cont. Min. Pet.) based on Ti concentration in quartz. These results are reviewed in comparison with temperatures from Fe-Ti oxide geothermometry. Quartz zoning is also compared to zonation in feldspars (using BSE imaging) from the same pumice clasts in order to establish the degree to which different crystal species record similar or contrasting magmatic histories. Quartz crystals in Whakamaru pumice display a variety of CL zoning patterns and resorption boundaries. Overgrowths typically appear to truncate CL growth zoning within the crystal core, indicating periods of resorption and subsequent re-growth - consistent with magma recharge causing a marked change in conditions (temperature and/or volatile saturation) and multi-stage crystallisation. Crystals typically display a dark (lower Ti) resorbed core, with an abrupt change to a CL-bright rim, although irregular textures and complex variations between crystals are observed. Core-to-rim profiles of Ti concentration in analysed quartz crystals show Ti variations within the range 50-225 ppm, corresponding to crystallisation temperatures of 733-935°C (assuming TiO2 activity in the melt of 0.6), with the lowest values recorded in the crystal core, increasing in a step-wise pattern towards the rim. These values are consistent with Fe-Ti oxide temperature data for the same pumice clasts which provide a temperature range of 660-933°C. It is inferred that the major steps in Ti content (and thus CL brightness) represent short-term temperature fluctuations due to magma chamber recharge and rejuvenation of a crystal mush, while rim temperatures are likely to record the magma temperature at the time of eruption.

Radio observations of a coronal mass ejection induced depletion in the outer solar corona

NASA Astrophysics Data System (ADS)

Ramesh, R.; Sastry, Ch. V.

2000-06-01

We report the first low frequency radio observations of a depletion that occurred in the outer solar corona in the aftermath of the CME event of 1986 June 5, with the large E-W one dimensional grating interferometer at the Gauribidanur radio observatory. We estimated the mass loss associated with the depletion and found that it agrees well with the value obtained through white light observations of the event. The radio brightness temperature at the location of the depletion was less by a factor of ~ 7 compared to the ambient. The angular extent over which the decrease in brightness took place was <= 3'. The electron density variation was found to be proportional to r-10. Since observations at different wavelength bands have different physical origins, the radio method might be useful in independently estimating the characteristics of CME induced coronal depletions.

Radio thermal sounding of natural environments

NASA Astrophysics Data System (ADS)

Gauss, Martin; Lomukhin, Yuriy

2017-11-01

At the moment, methods of sounding a status of soil, plant, forest and aquatic environments using radiometry and radar methods are intensively used. The main source of information using radar sounding is the back reflection ratio. The radiometric method is used for detection of the brightness temperature. In this paper, a communication between the back reflection ratio and the brightness temperature is described. This communication is proportional.

The Rapid Intensification of Typhoon Soudelor (2015) Explored through Next-Generation Satellite Observations

NASA Astrophysics Data System (ADS)

Munsell, E.; Braun, S. A.; Zhang, F.

2017-12-01

The dynamics that govern the intensification of tropical cyclones (TC) are dominated by rapidly evolving moist convective processes in the inner-core region. Remotely sensed satellite observations are typically available but in the past have lacked the necessary resolution to sufficiently examine TC intensification processes. However, as a result of the recent launch of next-generation high-resolution satellites (JMA's Himawari-8 and NOAA/NASA's GOES-16), the spatial and temporal frequency of remotely-sensed observations of TCs have increased significantly. This study utilizes brightness temperatures observed by the Advanced Himawari Imager to examine the structure of Typhoon Soudelor (2015) throughout its rapid intensification (RI) from a tropical storm to a super typhoon. Wavenumber decompositions are performed on brightness temperature fields that correspond to channels sensitive to upper-, mid-, and lower-level water vapor, and IR longwave radiation, to study wave features associated with the inner-core region. A scale-separation is also performed to assess the degree to which the intensification processes are dominated by phenomenon of various wavelengths. Higher-order wavenumbers reveal asymmetric features that propagate outwards from the storm on short time scales ( 1-2 h). The identification of these waves and their contribution to intensification is ongoing. A deterministic forecast of Typhoon Soudelor performed using a convection-permitting WRF simulation coupled to an Ensemble Kalman Filter that assimilates brightness temperatures, accurately captures the TCs RI event. The Community Radiative Transfer Model (CRTM) is used to produce simulated brightness temperature fields for the applicable channels. The model demonstrates the ability to reproduce the observed brightness temperatures in great detail, including smaller-scale features such as primary rainbands and the eye; however, a uniform warm bias is present. It is hypothesized that this likely results from inaccuracies in the heights and depths of the simulated upper-tropospheric clouds and is primarily related to deficiencies in the microphysics scheme. The sensitivity of various microphysics parameters is being explored to assess ways to improve the representation of the brightness temperatures within the CRTM.

Brightness and magnetic evolution of solar coronal bright points

NASA Astrophysics Data System (ADS)

Ugarte-Urra, I.

2004-12-01

This thesis presents a study of the brightness and magnetic evolution of several Extreme ultraviolet (EUV) coronal bright points (hereafter BPs). BPs are loop-like features of enhanced emission in the coronal EUV and X-ray images of the Sun, that are associated to the interaction of opposite photospheric magnetic polarities with magnetic fluxes of ≈1018 - 1019 Mx. The study was carried out using several instruments on board the Solar and Heliospheric Observatory (SOHO): the Extreme Ultraviolet Imager (EIT), the Coronal Diagnostic Spectrometer (CDS) and the Michelson Doppler Imager (MDI), supported by the high resolution imaging from the Transition Region And Coronal Explorer (TRACE). The results confirm that, down to 1'' (i.e. ~715 km) resolution, BPs are made of small loops with lengths of ~6 Mm and cross-sections of ~2 Mm. The loops are very dynamic, evolving in time scales as short as 1 - 2 minutes. This is reflected in a highly variable EUV response with fluctuations highly correlated in spectral lines at transition region temperatures (in the range 3.2x10^4 - 3.5x10^5 K), but not always at coronal temperatures. A wavelet analysis of the intensity variations reveals, for the first time, the existence of quasi-periodic oscillations with periods ranging 400 -- 1000 s, in the range of periods characteristic of the chromospheric network. The link between BPs and network bright points is discussed, as well as the interpretation of the oscillations in terms of global acoustic modes of closed magnetic structures. A comparison of the magnetic flux evolution of the magnetic polarities to the EUV flux changes is also presented. Throughout their lifetime, the intrinsic EUV emission of BPs is found to be dependent on the total magnetic flux of the polarities. In short time scales, co-spatial and co-temporal TRACE and MDI images, reveal the signature of heating events that produce sudden EUV brightenings simultaneous to magnetic flux cancellations. This is interpreted in terms of magnetic reconnection events. Finally, a electron density study of six coronal bright points produces values of ~1.6x109 cm-3, closer to active region plasma than to quiet Sun. The analysis of a large coronal loop (half length of 72 Mm) introduces the discussion on the prospects of future plasma diagnostics of BPs with forthcoming solar missions like Solar-B.

Utilizing Machine Learning to Downscale SMAP L3_SM_P Brightness Temperatures in Iowa for Agricultural Applications

NASA Astrophysics Data System (ADS)

Chakrabarti, S.; Judge, J.; Bindlish, R.; Bongiovanni, T.; Jackson, T. J.

2016-12-01

The NASA Soil Moisture Active Passive (SMAP) mission provides global observations of brightness temperatures (TB) at 36km. For these observations to be relevant to studies in agricultural regions, the TB values need to be downscaled to finer resolutions. In this study, a machine learning algorithm is introduced for downscaling of TB from 36km to 9km. The algorithm uses image segmentation to cluster the study region based on meteorological and land cover similarity, followed by a support vector machine based regression that computes the value of the disaggregated TB at all pixels. High resolution remote sensing products such as land surface temperature, normalized difference vegetation index, enhanced vegetation index, precipitation, soil texture, and land-cover were used for downscaling. The algorithm was implemented in Iowa, United States, during the growing season from April to July 2015 when the SMAP L3-SM_AP TB product at 9 km was available for comparison. In addition, the downscaled estimates from the algorithm are compared with 9km TB obtained by resampling SMAP L1B_TB product at 36km. It was found that the downscaled TB were very similar to the SMAP-L3_SM _AP TB product, even for vegetated areas with a mean difference ≤ 5K. However, the standard deviation of the downscaled was lower by 7K than that of the AP product. The probability density functions of the downscaled TB were similar to the SMAP- TB. The results indicate that these downscaling algorithms may be used for downscaling TB using complex non-linear correlations on a grid without using active microwave observations.

Interstellar Broadening of Images in the Gravitational Lens Pks 1830-211

NASA Technical Reports Server (NTRS)

Jones, D. L.; Preston, R. A.; Murphy, D. W.; Jauncey, D. L.; Reynolds, J. E.; Tzioumis, A. K.; King, E. A.; McCulloch, P. M.; Lovell, J. E. J.; Costa, M. E.

1996-01-01

The remarkably strong radio gravitational lens PKS 1830-211 consists of a one arcsecond diameter Einstein ring with two bright compact (milliarcsecond) components located on opposite sides of the ring. We have obtained 22 GHz VLBA data on this source to determine the intrinsic angular sizes of the compact components. Previous VLBI observations at lower frequencies indicate that the brightness temperatures of these components are significantly lower than 10(exp 10) K (Jauncey, et al. 1991), less than is typical for compact synchrotron radio sources and less than is implied by the short timescales of flux density variations. A possible explanation is that interstellar scattering is broadening the apparent angular size of the source and thereby reducing the observed brightness temperature. Our VLBA data support this hypothesis. At 22 GHz the measured brightness temperature is at least 10(exp 11) K, and the deconvolved 2 size of the core in the southwest compact component is proportional to upsilon(sup -2) between 1.7 and 22 GHz. VLBI observations at still higher frequencies should be unaffected by interstellar scattering.

Effect of Different Tree canopies on the Brightness Temperature of Snowpack

NASA Astrophysics Data System (ADS)

Mousavi, S.; De Roo, R. D.; Brucker, L.

2017-12-01

Snow stores the water we drink and is essential to grow food that we eat. But changes in snow quantities such as snow water equivalent (SWE) are underway and have serious consequences. So, effective management of the freshwater reservoir requires to monitor frequently (weekly or better) the spatial distribution of SWE and snowpack wetness. Both microwave radar and radiometer systems have long been considered as relevant remote sensing tools in retrieving globally snow physical parameters of interest thanks to their all-weather operation capability. However, their observations are sensitive to the presence of tree canopies, which in turns impacts SWE estimation. To address this long-lasting challenge, we parked a truck-mounted microwave radiometer system for an entire winter in a rare area where it exists different tree types in the different cardinal directions. We used dual-polarization microwave radiometers at three different frequencies (1.4, 19, and 37 GHz), mounted on a boom truck to observe continuously the snowpack surrounding the truck. Observations were recorded at different incidence angles. These measurements have been collected in Grand Mesa National Forest, Colorado as part of the NASA SnowEx 2016-17. In this presentation, the effect of Engelmann Spruce and Aspen trees on the measured brightness temperature of snow is discussed. It is shown that Engelmann Spruce trees increases the brightness temperature of the snowpack more than Aspen trees do. Moreover, the elevation angular dependence of the measured brightness temperatures of snowpack with and without tree canopies is investigated in the context of SWE retrievals. A time-lapse camera was monitoring a snow post installed in the sensors' field of view to characterize the brightness temperature change as snow depth evolved. Also, our study takes advantage of the snowpit measurements that were collected near the radiometers' field of view.

Correction of WindScat Scatterometric Measurements by Combining with AMSR Radiometric Data

NASA Technical Reports Server (NTRS)

Song, S.; Moore, R. K.

1996-01-01

The Seawinds scatterometer on the advanced Earth observing satellite-2 (ADEOS-2) will determine surface wind vectors by measuring the radar cross section. Multiple measurements will be made at different points in a wind-vector cell. When dense clouds and rain are present, the signal will be attenuated, thereby giving erroneous results for the wind. This report describes algorithms to use with the advanced mechanically scanned radiometer (AMSR) scanning radiometer on ADEOS-2 to correct for the attenuation. One can determine attenuation from a radiometer measurement based on the excess brightness temperature measured. This is the difference between the total measured brightness temperature and the contribution from surface emission. A major problem that the algorithm must address is determining the surface contribution. Two basic approaches were developed for this, one using the scattering coefficient measured along with the brightness temperature, and the other using the brightness temperature alone. For both methods, best results will occur if the wind from the preceding wind-vector cell can be used as an input to the algorithm. In the method based on the scattering coefficient, we need the wind direction from the preceding cell. In the method using brightness temperature alone, we need the wind speed from the preceding cell. If neither is available, the algorithm can work, but the corrections will be less accurate. Both correction methods require iterative solutions. Simulations show that the algorithms make significant improvements in the measured scattering coefficient and thus is the retrieved wind vector. For stratiform rains, the errors without correction can be quite large, so the correction makes a major improvement. For systems of separated convective cells, the initial error is smaller and the correction, although about the same percentage, has a smaller effect.

Validation of MODIS-derived bidirectional reflectivity retrieval algorithm in mid-infrared channel with field measurements.

PubMed

Tang, Bo-Hui; Wu, Hua-; Li, Zhao-Liang; Nerry, Françoise

2012-07-30

This work addressed the validation of the MODIS-derived bidirectional reflectivity retrieval algorithm in mid-infrared (MIR) channel, proposed by Tang and Li [Int. J. Remote Sens. 29, 4907 (2008)], with ground-measured data, which were collected from a field campaign that took place in June 2004 at the ONERA (Office National d'Etudes et de Recherches Aérospatiales) center of Fauga-Mauzac, on the PIRRENE (Programme Interdisciplinaire de Recherche sur la Radiométrie en Environnement Extérieur) experiment site [Opt. Express 15, 12464 (2007)]. The leaving-surface spectral radiances measured by a BOMEM (MR250 Series) Fourier transform interferometer were used to calculate the ground brightness temperatures with the combination of the inversion of the Planck function and the spectral response functions of MODIS channels 22 and 23, and then to estimate the ground brightness temperature without the contribution of the solar direct beam and the bidirectional reflectivity by using Tang and Li's proposed algorithm. On the other hand, the simultaneously measured atmospheric profiles were used to obtain the atmospheric parameters and then to calculate the ground brightness temperature without the contribution of the solar direct beam, based on the atmospheric radiative transfer equation in the MIR region. Comparison of those two kinds of brightness temperature obtained by two different methods indicated that the Root Mean Square Error (RMSE) between the brightness temperatures estimated respectively using Tang and Li's algorithm and the atmospheric radiative transfer equation is 1.94 K. In addition, comparison of the hemispherical-directional reflectances derived by Tang and Li's algorithm with those obtained from the field measurements showed that the RMSE is 0.011, which indicates that Tang and Li's algorithm is feasible to retrieve the bidirectional reflectivity in MIR channel from MODIS data.

Estimating the urban bias of surface shelter temperatures using upper-air and satellite data. Part 2: Estimation of the urban bias

NASA Technical Reports Server (NTRS)

Epperson, David L.; Davis, Jerry M.; Bloomfield, Peter; Karl, Thomas R.; Mcnab, Alan L.; Gallo, Kevin P.

1995-01-01

A methodology is presented for estimating the urban bias of surface shelter temperatures due to the effect of the urban heat island. Multiple regression techniques were used to predict surface shelter temperatures based on the time period 1986-89 using upper-air data from the European Centre for Medium-Range Weather Forecasts (ECMWF) to represent the background climate, site-specific data to represent the local landscape, and satellite-derived data -- the normalized difference vegetation index (NDVI) and the Defense Meteorological Satellite Program (DMSP) nighttime brightness data -- to represent the urban and rural landscape. Local NDVI and DMSP values were calculated for each station using the mean NDVI and DMSP values from a 3 km x 3 km area centered over the given station. Regional NDVI and DMSP values were calculated to represent a typical rural value for each station using the mean NDVI and DMSP values from a 1 deg x 1 deg latitude-longitude area in which the given station was located. Models for the United States were then developed for monthly maximum, mean, and minimum temperatures using data from over 1000 stations in the U.S. Cooperative (COOP) Network and for monthly mean temperatures with data from over 1150 stations in the Global Historical Climate Network (GHCN). Local biases, or the differences between the model predictions using the observed NDVI and DMSP values, and the predictions using the background regional values were calculated and compared with the results of other research. The local or urban bias of U.S. temperatures, as derived from all U.S. stations (urban and rural) used in the models, averaged near 0.40 C for monthly minimum temperatures, near 0.25 C for monthly mean temperatures, and near 0.10 C for monthly maximum temperatures. The biases of monthly minimum temperatures for individual stations ranged from near -1.1 C for rural stations to 2.4 C for stations from the largest urban areas. The results of this study indicate minimal problems for global application once global NDVI and DMSP data become available.

Control of dispersed-phase temperature in plasma flows by the spectral-brightness pyrometry method

NASA Astrophysics Data System (ADS)

Dolmatov, A. V.; Gulyaev, I. P.; Gulyaev, P. Yu; Iordan, V. I.

2016-02-01

In the present work, we propose a new method for measuring the distribution of temperature in the ensembles of condensed-phase particles in plasma spray flows. Interrelation between the spectral temperature of the particles and the distribution of camera brightness signal is revealed. The established inter-relation enables an in-situ calibration of measuring instruments using the objects under study. The spectral-brightness pyrometry method was approbated on a Plazer plasma-arc wire spraying facility at the Paton Institute of Electrical Welding (Ukrainian Academy of Sciences, Kiev) and on the Thermoplasma 50-1 powder spraying facility at the Institute of Theoretical and Applied Mechanics (Russian Academy of Sciences, Siberian Branch, Novosibirsk). The work was supported by the Russian Foundation for Basic Research (Grants Nos. 14-08-90428 and 15-48-00100).

Assessment of mesoscale convective systems using IR brightness temperature in the southwest of Iran

NASA Astrophysics Data System (ADS)

Rafati, Somayeh; Karimi, Mostafa

2017-07-01

In this research, the spatial and temporal distribution of Mesoscale Convective Systems was assessed in the southwest of Iran using Global merged satellite IR brightness temperature (acquired from Meteosat, GOES, and GMS geostationary satellites) and synoptic station data. Event days were selected using a set of storm reports and precipitation criteria. The following criteria are used to determine the days with occurrence of convective systems: (1) at least one station reported 6-h precipitation exceeding 10 mm and (2) at least three stations reported phenomena related to convection (thunderstorm, lightning, and shower). MCSs were detected based on brightness temperature, maximum areal extent, and duration thresholds (228 K, 10,000 km2, and 3 h, respectively). An MCS occurrence classification system is developed based on mean sea level, 850 and 500 hPa pressure patterns.

Laboratory measurement of the millimeter wave properties of liquid sulfuric acid (H2SO4). [study of microwave emission from Venus

NASA Technical Reports Server (NTRS)

Fahd, Antoine K.; Steffes, Paul G.

1991-01-01

The methodology and the results of laboratory measurements of the millimeter wave properties of liquid sulfuric acid are presented. Measurements conducted at 30-40 and 90-100 GHz are reported, using different concentrations of liquid H2SO4. The measured data are used to compute the expected opacity of H2SO4 condensates and their effects on the millimeter wave emission from Venus. The cloud condensate is found to have an effect on the emission from Venus. The calculated decrease in brightness temperature is well below the observed decrease in brightness temperature found by de Pater et al. (1991). It is suggested that other constituents such as gaseous H2SO4 also affect the observed variation in the brightness temperature.

SUPERMODEL ANALYSIS OF GALAXY CLUSTERS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fusco-Femiano, R.; Cavaliere, A.; Lapi, A.

2009-11-01

We present the analysis of the X-ray brightness and temperature profiles for six clusters belonging to both the Cool Core (CC) and Non Cool Core (NCC) classes, in terms of the Supermodel (SM) developed by Cavaliere et al. Based on the gravitational wells set by the dark matter (DM) halos, the SM straightforwardly expresses the equilibrium of the intracluster plasma (ICP) modulated by the entropy deposited at the boundary by standing shocks from gravitational accretion, and injected at the center by outgoing blast waves from mergers or from outbursts of active galactic nuclei. The cluster set analyzed here highlights notmore » only how simply the SM represents the main dichotomy CC versus NCC clusters in terms of a few ICP parameters governing the radial entropy run, but also how accurately it fits even complex brightness and temperature profiles. For CC clusters like A2199 and A2597, the SM with a low level of central entropy straightforwardly yields the characteristic peaked profile of the temperature marked by a decline toward the center, without requiring currently strong radiative cooling and high mass deposition rates. NCC clusters like A1656 require instead a central entropy floor of a substantial level, and some like A2256 and even more A644 feature structured temperature profiles that also call for a definite floor extension; in such conditions the SM accurately fits the observations, and suggests that in these clusters the ICP has been just remolded by a merger event, in the way of a remnant cool core. The SM also predicts that DM halos with high concentration should correlate with flatter entropy profiles and steeper brightness in the outskirts; this is indeed the case with A1689, for which from X-rays we find concentration values c approx 10, the hallmark of an early halo formation. Thus, we show the SM to constitute a fast tool not only to provide wide libraries of accurate fits to X-ray temperature and density profiles, but also to retrieve from the ICP archives specific information concerning the physical histories of DM and baryons in the inner and the outer cluster regions.« less

A NuSTAR census of coronal parameters in Seyfert galaxies

NASA Astrophysics Data System (ADS)

Tortosa, A.; Bianchi, S.; Marinucci, A.; Matt, G.; Petrucci, P. O.

2018-06-01

Context. We discuss the results of the hot corona parameters of active galactic nuclei (AGN) that have been recently measured with NuSTAR. The values taken from the literature of a sample of 19 bright Seyfert galaxies are analysed. Aims: The aim of this work is to look for correlations between coronal parameters, such as the photon index and cut-off energy (when a phenomenological model is adopted) or the optical depth and temperature (when a Comptonization model is used), and other parameters of the systems, such as the black hole mass or the Eddington ratio. Methods: We analysed the coronal parameters of the 19 unobscured, bright Seyfert galaxies that are present in the Swift/BAT 70-month catalogue and that have been observed by NuSTAR, alone or simultaneously with others X-ray observatories, such as Swift, Suzaku, or XMM-Newton. Results: We found an anti-correlation with a significance level >98% between the coronal optical depth and the coronal temperature of our sample. On the other hand, no correlation between the above parameters and the black hole mass, the accretion rate, and the intrinsic spectral slope of the sources is found.

Effect of terrestrial radiation on brightness temperature at lunar nearside: Based on theoretical calculation and data analysis

NASA Astrophysics Data System (ADS)

Wei, Guangfei; Li, Xiongyao; Wang, Shijie

2015-02-01

Terrestrial radiation is another possible source of heat in lunar thermal environment at its nearside besides the solar illumination. On the basis of Clouds and the Earth's Radiant Energy System (CERES) data products, the effect of terrestrial radiation on the brightness temperature (TBe) of the lunar nearside has been theoretically calculated. It shows that the mafic lunar mare with high TBe is more sensitive to terrestrial radiation than the feldspathic highland with low TBe value. According to the synchronous rotation of the Moon, we extract TBe on lunar nearside using the microwave radiometer data from the first Chinese lunar probe Chang'E-1 (CE-1). Consistently, the average TBe at Mare Serenitatis is about 1.2 K while the highland around the Geber crater (19.4°S, 13.9°E) is relatively small at ∼0.4 K. Our results indicate that there is no significant effect of terrestrial radiation on TBe at the lunar nearside. However, to extract TBe accurately, effects of heat flow, rock abundance and subsurface rock fragments which are more significant should be considered in the future work.

Morning twilight measured at Bandung and Jombang

NASA Astrophysics Data System (ADS)

Arumaningtyas, Eka Puspita; Raharto, Moedji; Herdiwijaya, Dhani

2012-06-01

Twilight divided into three categories namely, astronomical twilight, nautical twilight, and civil twilight. The three types of twilight can occur either in the evening or early morning. According to the U.S. Naval Observatory the three types distinguished by the depression (altitude of the sun below the horizon) for the evening or the morning twilight, -180, -120, and -60. Sky brightness measurements usually intended to determine the quality of the sky at some observation site or to determine the quality of the atmosphere by light pollution. Sky brightness data could be use for practical purposes such as to determine prayer times (Morning Prayer). This study describes the measurement of sky brightness using a light meter Sky Quality Meter. The measurements indicate the presence of different values and patterns in the twilight sky brightness. This variability highly determined by the weather conditions. Sky brightness shows a constant value shortly after the evening astronomical twilight and before morning astronomical twilight. Before the evening astronomical twilight and after morning astronomical twilight sky brightness showing continue changing.

A passive microwave technique for estimating rainfall and vertical structure information from space. Part 1: Algorithm description

NASA Technical Reports Server (NTRS)

Kummerow, Christian; Giglio, Louis

1994-01-01

This paper describes a multichannel physical approach for retrieving rainfall and vertical structure information from satellite-based passive microwave observations. The algorithm makes use of statistical inversion techniques based upon theoretically calculated relations between rainfall rates and brightness temperatures. Potential errors introduced into the theoretical calculations by the unknown vertical distribution of hydrometeors are overcome by explicity accounting for diverse hydrometeor profiles. This is accomplished by allowing for a number of different vertical distributions in the theoretical brightness temperature calculations and requiring consistency between the observed and calculated brightness temperatures. This paper will focus primarily on the theoretical aspects of the retrieval algorithm, which includes a procedure used to account for inhomogeneities of the rainfall within the satellite field of view as well as a detailed description of the algorithm as it is applied over both ocean and land surfaces. The residual error between observed and calculated brightness temperatures is found to be an important quantity in assessing the uniqueness of the solution. It is further found that the residual error is a meaningful quantity that can be used to derive expected accuracies from this retrieval technique. Examples comparing the retrieved results as well as the detailed analysis of the algorithm performance under various circumstances are the subject of a companion paper.

Behavior of Solar Cycles 23 and 24 Revealed by Microwave Observations

NASA Technical Reports Server (NTRS)

Gopalswamy, N.; Yashiro, S.; Maekelae, P.; Michalek, G.; Shibasaki, K.; Hathaway, D. H.

2012-01-01

Using magnetic and microwave butterfly diagrams, we compare the behavior of solar polar regions to show that (1) the polar magnetic field and the microwave brightness temperature during solar minimum substantially diminished during the cycle 23/24 minimum compared to the 22/23 minimum. (2) The polar microwave brightness temperature (Tb) seems to be a good proxy for the underlying magnetic field strength (B). The analysis indicates a relationship, B = 0.0067Tb - 70, where B is in G and Tb in K. (3) Both the brightness temperature and the magnetic field strength show north-south asymmetry most of the time except for a short period during the maximum phase. (4) The rush-to-the-pole phenomenon observed in the prominence eruption (PE) activity seems to be complete in the northern hemisphere as of 2012 March. (5) The decline of the microwave brightness temperature in the north polar region to the quiet-Sun levels and the sustained PE activity poleward of 60degN suggest that solar maximum conditions have arrived at the northern hemisphere. The southern hemisphere continues to exhibit conditions corresponding to the rise phase of solar cycle 24. Key words: Sun: chromosphere Sun: coronal mass ejections (CMEs) Sun: filaments, prominences Sun: photosphere Sun: radio radiation Sun: surface magnetism

Preliminary investigations on a new method of retaining the colour of shucked cockles ( Anadara Granosa), and the extension of shelflife by gamma irradiation and vacuum packing

NASA Astrophysics Data System (ADS)

Ng, Cher Siang; Low, Lai Kim; Chia, Lawrence H. L.

Live cockles were incubated in atmospheres containing different concentrations of carbon monoxide. Since CO combines more readily with myoglobin and haemoglobin than oxygen, the formation of in vivo deoxygenated haemoglobins and post mortem formation of methaemoglobin were retarded by the more stable carboxyhaemoglobin (HbCO). The bright red colour of the stable HbCO is retained during storage, giving the desired colour to the cockles. The colour of normal, chilled cockle meat deteriorated after 3 days ice storage while those treated with 50 and 100% CO retained the bright deep orange colour up to 10 days storage. Irradiation caused faster colour deterioration in both CO and non-CO treated samples. Vacuum packing influenced the colour of the cockles with irradiation and with CO treatments. In non-CO treated, irradiated samples, the effect of vacuum packing was not obvious. In CO treated, irradiated samples, vacuum packing retarded the deterioration of colour. Odour developments were influenced by irradiation, vacuum packing and storage temperature, and were not influenced by CO treatments. Irradiation suppressed the development of odour for the first 11 days storage (0°C) while vacuum packing depressed the odour by lowering its intensity instead. Odour development was slowed down by lowering the storage temperature. The odour of shucked cockles was rejected within one day at room temperature (26-28°C) while at 0°C the odour of the shucked cockles was still acceptable after 10 days. Suitable chemical indices for quality are K value and TVBN. Treatment with CO did not influence the K value development. Vacuum packing produced the highest K values after 19 days storage (0°C), while irradiated samples had higher K values than non-irradiated samples. The TVBN increased with storage and is an indicator of the odour development. The use of CO treatment extended the shelflife of the cockles based on appearance. A combination of CO treatment, vacuum packing, ice storage and irradiation extended the shelflife to beyond 18 days, based on odour, colour, and overall appearance.

A quantitative analysis of TIMS data obtained on the Learjet 23 at various altitudes

NASA Technical Reports Server (NTRS)

Jaggi, S.

1992-01-01

A series of Thermal Infrared Multispectral Scanner (TIMS) data acquisition flights were conducted on the NASA Learjet 23 at different altitudes over a test site. The objective was to monitor the performance of the TIMS (its estimation of the brightness temperatures of the ground scene) with increasing altitude. The results do not show any significant correlation between the brightness temperatures and the altitude. The analysis indicates that the estimation of the temperatures is a function of the accuracy of the atmospheric correction used for each altitude.

Enhancing user experience by using multi-sensor data fusion to predict phone's luminance

NASA Astrophysics Data System (ADS)

Marhoubi, Asmaa H.

2017-09-01

The movement of a phone in an environment with different brightness, makes the luminance prediction challenging. The ambient light sensor takes time to modify the brightness of the screen based on the environment it is placed in. This causes an unsatisfactory user experience and delays in adjustment of the screen brightness. In this research, a method is proposed for enhancing the prediction of luminance using accelerometer, gyroscope and speed measurement technique. The speed of the phone is identified using Sum-of-Sine parameters. The lux values are then fused with the accelerometer and gyroscope data to present more accurate luminance values for the ALS based on the movement of the phone. An investigation is made during the movement of the user in a standard lighting environment. This enhances the user experience and improves the screen brightness precision. The accuracy has given an R-Square value of up to 0.97.

Satellite-derived ice data sets no. 2: Arctic monthly average microwave brightness temperatures and sea ice concentrations, 1973-1976

NASA Technical Reports Server (NTRS)

Parkinson, C. L.; Comiso, J. C.; Zwally, H. J.

1987-01-01

A summary data set for four years (mid 70's) of Arctic sea ice conditions is available on magnetic tape. The data include monthly and yearly averaged Nimbus 5 electrically scanning microwave radiometer (ESMR) brightness temperatures, an ice concentration parameter derived from the brightness temperatures, monthly climatological surface air temperatures, and monthly climatological sea level pressures. All data matrices are applied to 293 by 293 grids that cover a polar stereographic map enclosing the 50 deg N latitude circle. The grid size varies from about 32 X 32 km at the poles to about 28 X 28 km at 50 deg N. The ice concentration parameter is calculated assuming that the field of view contains only open water and first-year ice with an ice emissivity of 0.92. To account for the presence of multiyear ice, a nomogram is provided relating the ice concentration parameter, the total ice concentration, and the fraction of the ice cover which is multiyear ice.

Organic Nanocrystals with Bright Red Persistent Room-Temperature Phosphorescence for Biological Applications.

PubMed

Fateminia, S M Ali; Mao, Zhu; Xu, Shidang; Yang, Zhiyong; Chi, Zhenguo; Liu, Bin

2017-09-25

Persistent room-temperature phosphorescence (RTP) in pure organic materials has attracted great attention because of their unique optical properties. The design of organic materials with bright red persistent RTP remains challenging. Herein, we report a new design strategy for realizing high brightness and long lifetime of red-emissive RTP molecules, which is based on introducing an alkoxy spacer between the hybrid units in the molecule. The spacer offers easy Br-H bond formation during crystallization, which also facilitates intermolecular electron coupling to favor persistent RTP. As the majority of RTP compounds have to be confined in a rigid environment to quench nonradiative relaxation pathways for bright phosphorescence emission, nanocrystallization is used to not only rigidify the molecules but also offer the desirable size and water-dispersity for biomedical applications. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Microwave Signatures of Melting/Refreezing Snow: Observations and Modeling Using Dense Medium Radiative Transfer Theory

NASA Technical Reports Server (NTRS)

Tedesco, Marco; Kim, Edward J.; England, Anthony; deRoo, Roger; Hardy, Janet

2005-01-01

Microwave brightness temperatures of snow covered terrains can be modeled by means of the Dense Radiative Transfer Medium Theory (DMRT). In a dense medium, such as snow, the assumption of independent scattering is no longer valid and the scattering of correlated scatterers must be considered. In the DMRT, this is done considering a pair distribution function of the particles position. In the electromagnetic model, the snowpack is simulated as a homogeneous layer having effective permittivity and albedo calculated through the DMRT. In order to account for clustering of snow crystals, a model of cohesive particles can be applied, where the cohesion between the particles is described by means of a dimensionless parameters called stickiness (z), representing a measure of the inversion of the attraction of the particles. The lower the z the higher the stickiness. In this study, microwave signatures of melting and refreezing cycles of seasonal snowpacks at high altitudes are studied by means of both experimental and modeling tools. Radiometric data were collected 24 hours per day by the University of Michigan Tower Mounted Radiometer System (TMRS). The brightness temperatures collected by means of the TMRS are simulated by means of a multi-layer electromagnetic model based on the dense medium theory with the inputs to the model derived from the data collected at the snow pits and from the meteorological station. The paper is structured as follows: in the first Section the temperature profiles recorded by the meteorological station and the snow pit data are presented and analyzed; in the second Section, the characteristics of the radiometric system used to collect the brightness temperatures are reported together with the temporal behavior of the recorded brightness temperatures; in the successive Section the multi-layer DMRT-based electromagnetic model is described; in the fourth Section the comparison between modeled and measured brightness temperatures is discussed. We dedicate the last Section to the conclusions and future works.

Submillimeter Observations of the Low-Metallicity Galaxy NGC 4214

NASA Astrophysics Data System (ADS)

Kiuchi, Gaku; Ohta, Kouji; Sawicki, Marcin; Allen, Michael

2004-12-01

Results of submillimeter (450 and 850 μm) observations of a nearby dwarf irregular galaxy NGC 4214 with SCUBA on JCMT are presented. We aimed at examining the far-infrared-to-submillimeter spectral energy distribution (SED) and properties of dust thermal emission in a low-metallicity environment by choosing NGC 4214, in which the gas metallicity (logO/H+12) is 8.34. We found that the SED is quite similar to those of the IRAS Bright Galaxies Sample (IBGS), which are local bright star-forming galaxies with metallicities comparable to the solar abundance. The dust temperature and emissivity index for NGC 4214 obtained by a fitting to the single temperature graybody model are Td=35+/-0.8 K and β=1.4+/-0.1, respectively, which are typical values for IBGS galaxies. Compiling the previous studies on similar nearby dwarf irregular galaxies, we found that NGC 1569 shows similar results to those of NGC 4214, while NGC 4449 and IC 10 SE show different SEDs and low emissivity indices. There seems to be a variety of SEDs among metal-poor dwarf irregular galaxies. We examined the dependence on the intensity of interstellar radiation field, as well as a two-temperature model, but the origin of the difference is not clear. Some mechanism(s) other than metallicity and the interstellar radiation field must be responsible for controlling dust emission properties.

New Observations of Subarcsecond Photospheric Bright Points

NASA Technical Reports Server (NTRS)

Berger, T. E.; Schrijver, C. J.; Shine, R. A.; Tarbell, T. D.; Title, A. M.; Scharmer, G.

1995-01-01

We have used an interference filter centered at 4305 A within the bandhead of the CH radical (the 'G band') and real-time image selection at the Swedish Vacuum Solar Telescope on La Palma to produce very high contrast images of subarcsecond photospheric bright points at all locations on the solar disk. During the 6 day period of 1993 September 15-20 we observed active region NOAA 7581 from its appearance on the East limb to a near-disk-center position on September 20. A total of 1804 bright points were selected for analysis from the disk center image using feature extraction image processing techniques. The measured Full Width at Half Maximum (FWHM) distribution of the bright points in the image is lognormal with a modal value of 220 km (0 sec .30) and an average value of 250 km (0 sec .35). The smallest measured bright point diameter is 120 km (0 sec .17) and the largest is 600 km (O sec .69). Approximately 60% of the measured bright points are circular (eccentricity approx. 1.0), the average eccentricity is 1.5, and the maximum eccentricity corresponding to filigree in the image is 6.5. The peak contrast of the measured bright points is normally distributed. The contrast distribution variance is much greater than the measurement accuracy, indicating a large spread in intrinsic bright-point contrast. When referenced to an averaged 'quiet-Sun' area in the image, the modal contrast is 29% and the maximum value is 75%; when referenced to an average intergranular lane brightness in the image, the distribution has a modal value of 61% and a maximum of 119%. The bin-averaged contrast of G-band bright points is constant across the entire measured size range. The measured area of the bright points, corrected for pixelation and selection effects, covers about 1.8% of the total image area. Large pores and micropores occupy an additional 2% of the image area, implying a total area fraction of magnetic proxy features in the image of 3.8%. We discuss the implications of this area fraction measurement in the context of previously published measurements which show that typical active region plage has a magnetic filling factor on the order of 10% or greater. The results suggest that in the active region analyzed here, less than 50% of the small-scale magnetic flux tubes are demarcated by visible proxies such as bright points or pores.

Inference of Ice Cloud Properties from High-spectral Resolution Infrared Observations. Appendix 4

NASA Technical Reports Server (NTRS)

Huang, Hung-Lung; Yang, Ping; Wei, Heli; Baum, Bryan A.; Hu, Yongxiang; Antonelli, Paolo; Ackerman, Steven A.

2005-01-01

The theoretical basis is explored for inferring the microphysical properties of ice crystal from high-spectral resolution infrared observations. A radiative transfer model is employed to simulate spectral radiances to address relevant issues. The extinction and absorption efficiencies of individual ice crystals, assumed as hexagonal columns for large particles and droxtals for small particles, are computed from a combination of the finite- difference time-domain (FDTD) technique and a composite method. The corresponding phase functions are computed from a combination of FDTD and an improved geometric optics method (IGOM). Bulk scattering properties are derived by averaging the single- scattering properties of individual particles for 30 particle size distributions developed from in situ measurements and for additional four analytical Gamma size distributions for small particles. The non-sphericity of ice crystals is shown to have a significant impact on the radiative signatures in the infrared (IR) spectrum; the spherical particle approximation for inferring ice cloud properties may result in an overest&ation of the optical thickness and an inaccurate retrieval of effective particle size. Furthermore, we show that the error associated with the use of the Henyey-Greenstein phase function can be as larger as 1 K in terms of brightness temperature for larger particle effective size at some strong scattering wavenumbers. For small particles, the difference between the two phase functions is much less, with brightness temperatures generally differing by less than 0.4 K. The simulations undertaken in this study show that the slope of the IR brightness temperature spectrum between 790-960/cm is sensitive to the effective particle size. Furthermore, a strong sensitivity of IR brightness temperature to cloud optical thickness is noted within the l050-1250/cm region. Based on this spectral feature, a technique is presented for the simultaneous retrieval of the visible optical thickness and effective particle size from high spectral resolution infrared data under ice cloudy con&tion. The error analysis shows that the uncertainty of the retrieved optical thickness and effective particle size has a small range of variation. The error for retrieving particle size in conjunction with an uncertainty of 5 K in cloud'temperature, or a surface temperature uncertainty of 2.5 K, is less than 15%. The corresponding e m r in the uncertainty of optical thickness is within 5-2096, depending on the value of cloud optical thickness. The applicability of the technique is demonstrated using the aircraft-based High- resolution Interferometer Sounder (HIS) data from the Subsonic Aircraft: Contrail and Cloud Effects Special Study (SUCCESS) in 1996 and the First ISCCP Regional Experiment - Arctic Clouds Experiment (FIRE-ACE) in 1998.

Precursor state of oxygen molecules on the Si(001) surface during the initial room-temperature adsorption

NASA Astrophysics Data System (ADS)

Hwang, Eunkyung; Chang, Yun Hee; Kim, Yong-Sung; Koo, Ja-Yong; Kim, Hanchul

2012-10-01

The initial adsorption of oxygen molecules on Si(001) is investigated at room temperature. The scanning tunneling microscopy images reveal a unique bright O2-induced feature. The very initial sticking coefficient of O2 below 0.04 Langmuir is measured to be ˜0.16. Upon thermal annealing at 250-600 °C, the bright O2-induced feature is destroyed, and the Si(001) surface is covered with dark depressions that seem to be oxidized structures with -Si-O-Si- bonds. This suggests that the observed bright O2-induced feature is an intermediate precursor state that may be either a silanone species or a molecular adsorption structure.

A statistical examination of Nimbus 7 SMMR data and remote sensing of sea surface temperature, liquid water content in the atmosphere and surfaces wind speed

NASA Technical Reports Server (NTRS)

Prabhakara, C.; Wang, I.; Chang, A. T. C.; Gloersen, P.

1982-01-01

Nimbus 7 Scanning Multichannel Microwave Radiometer (SMMR) brightness temperature measurements over the global oceans have been examined with the help of statistical and empirical techniques. Such analyses show that zonal averages of brightness temperature measured by SMMR, over the oceans, on a large scale are primarily influenced by the water vapor in the atmosphere. Liquid water in the clouds and rain, which has a much smaller spatial and temporal scale, contributes substantially to the variability of the SMMR measurements within the latitudinal zones. The surface wind not only increases the surface emissivity but through its interactions with the atmosphere produces correlations, in the SMMR brightness temperature data, that have significant meteorological implications. It is found that a simple meteorological model can explain the general characteristics of the SMMR data. With the help of this model methods to infer over the global oceans, the surface temperature, liquid water content in the atmosphere, and surface wind speed are developed. Monthly mean estimates of the sea surface temperature and surface winds are compared with the ship measurements. Estimates of liquid water content in the atmosphere are consistent with earlier satellite measurements.

RESOLVING THE BRIGHT HCN(1–0) EMISSION TOWARD THE SEYFERT 2 NUCLEUS OF M51: SHOCK ENHANCEMENT BY RADIO JETS AND WEAK MASING BY INFRARED PUMPING?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsushita, Satoki; Trung, Dinh-V-; Boone, Frédéric

2015-01-20

We present high angular resolution observations of the HCN(1-0) emission (at ∼1'' or ∼34 pc), together with CO J = 1-0, 2-1, and 3-2 observations, toward the Seyfert 2 nucleus of M51 (NGC 5194). The overall HCN(1-0) distribution and kinematics are very similar to that of the CO lines, which have been indicated as the jet-entrained molecular gas in our past observations. In addition, high HCN(1-0)/CO(1-0) brightness temperature ratio of about unity is observed along the jets, similar to that observed at the shocked molecular gas in our Galaxy. These results strongly indicate that both diffuse and dense gases are entrained bymore » the jets and outflowing from the active galactic nucleus. The channel map of HCN(1-0) at the systemic velocity shows a strong emission right at the nucleus, where no obvious emission has been detected in the CO lines. The HCN(1-0)/CO(1-0) brightness temperature ratio at this region reaches >2, a value that cannot be explained considering standard physical/chemical conditions. Based on our calculations, we suggest infrared pumping and possibly weak HCN masing, but still requiring an enhanced HCN abundance for the cause of this high ratio. This suggests the presence of a compact dense obscuring molecular gas in front of the nucleus of M51, which remains unresolved at our ∼1'' (∼34 pc) resolution, and consistent with the Seyfert 2 classification picture.« less

An atlas of upper tropospheric radiances observed in the 6 to 7-micrometer water vapor band using TOVS data from the NOAA weather satellites during 1979-1991

NASA Technical Reports Server (NTRS)

Chesters, Dennis; Sharma, OM

1992-01-01

This document is a pictorial atlas of the Earth's radiance emitted in the 6 to 7 micro-m water vapor band. At these wavelengths, the infrared brightness temperature corresponds to the layer-average temperature of the top few millimeters of water vapor in the atmosphere. At low altitudes, bright regions are dry slots in the upper troposphere. The satellite observations were obtained from NOAA's cloud and angle corrected measurements made by a series of polar orbiting TOVS (TIROS Operational Vertical Sounder) instruments flown from 1979 to 1991. TOVS 6.7 micro-m and 7.2 micro-m channels were converted to a single brightness temperature that simulates a high altitude channel near '6.5' micro-m. For climatological studies, the daily '6.5' micro-m overpass data were gridded to a cartesian projection with 5 by 5 degree horizontal resolution between 40 degrees N and 40 degrees S latitude. This atlas presents greyscale images of the '6.5' micro-m brightness fields for every day in every month for 13 years. The mean brightness for each of the 12 months for 13 years is presented to display interannual variability, and the annual cycle of 12 monthly means is summarized on a single page. Statistical summaries are presented from other investigations in progress.

Studying and Understanding the Jovian Aurora Based on Measurements from the Juno MWR Taken during Perijove 5

NASA Astrophysics Data System (ADS)

Bellotti, A.; Steffes, P. G.; Janssen, M. A.

2017-12-01

During Perijove 5 (March 27, 2017), an anomolous signal level was detected by the Juno Microwave Radiometer (MWR) at latitudes north of 50N. This anomaly presented itself in two distinct ways. At the three longest wavelength channels (11.55, 24, 50 cm), a decrease in brightness temperatures at latitudes between 50N-60N was measured. At the longest wavelength channel (50 cm) this decrease is followed by an increase in brightness temperature at higher latitudes. These anomalous brightness temperatures are examined and attributed to Juno MWR flying over and measuring effects from the Jovian aurora. Presented here are the basics of the radiative transfer model needed to properly understand, explain, and model this anomoly. This work was supported by NASA Contract NNM06AA75C from the Marshall Space Flight Center supporting the Juno Mission Science team, under Subcontract 699054X from the Southwest Research Institute.

Morning-evening differences in global and regional oceanic precipitation as observed by the SSM/I

NASA Technical Reports Server (NTRS)

Petty, Grant W.; Katsaros, Kristina B.

1992-01-01

For the present preliminary analysis of oceanic rainfall statistics, global oceanic SSM/I data were simply scanned for pixels which exhibited a 37 GHz polarization difference (vertically polarized brightness temperatures minus horizontally polarized brightness temperatures) of less than 15 K. Such a low polarization difference over the open ocean is a completely unambiguous indication of moderate to intense precipitation. Co-located brightness temperatures from all seven channels of the SSM/I were saved for each pixel so identified. Bad scans and geographically mislocated block of data were objectively identified and removed from the resulting data base. We collected global oceanic rainfall data for two time periods, each one month in length. The first period (20 July-19 August 1987) coincides with the peak of the Northern Hemisphere summer. The second period (13 January-12 February 1988) coincides with the Northern Hemisphere winter.

The high brightness temperature of B0529+483 revealed by RadioAstron and implications for interstellar scattering

NASA Astrophysics Data System (ADS)

Pilipenko, S. V.; Kovalev, Y. Y.; Andrianov, A. S.; Bach, U.; Buttaccio, S.; Cassaro, P.; Cimò, G.; Edwards, P. G.; Gawroński, M. P.; Gurvits, L. I.; Hovatta, T.; Jauncey, D. L.; Johnson, M. D.; Kovalev, Yu A.; Kutkin, A. M.; Lisakov, M. M.; Melnikov, A. E.; Orlati, A.; Rudnitskiy, A. G.; Sokolovsky, K. V.; Stanghellini, C.; de Vicente, P.; Voitsik, P. A.; Wolak, P.; Zhekanis, G. V.

2018-03-01

The high brightness temperatures, Tb ≳ 1013 K, detected in several active galactic nuclei by RadioAstron space VLBI observations challenge theoretical limits. Refractive scattering by the interstellar medium may affect such measurements. We quantify the scattering properties and the sub-mas scale source parameters for the quasar B0529+483. Using RadioAstron correlated flux density measurements at 1.7, 4.8, and 22 GHz on projected baselines up to 240 000 km we find two characteristic angular scales in the quasar core, about 100 and 10 μas. Some indications of scattering substructure are found. Very high brightness temperatures, Tb ≥ 1013 K, are estimated at 4.8 and 22 GHz even taking into account the refractive scattering. Our findings suggest a clear dominance of the particle energy density over the magnetic field energy density in the core of this quasar.

Determination of cloud liquid water content using the SSM/I

NASA Technical Reports Server (NTRS)

Alishouse, John C.; Snider, Jack B.; Westwater, Ed R.; Swift, Calvin T.; Ruf, Christopher S.

1990-01-01

As part of a calibration/validation effort for the special sensor microwave/imager (SSM/I), coincident observations of SSM/I brightness temperatures and surface-based observations of cloud liquid water were obtained. These observations were used to validate initial algorithms and to derive an improved algorithm. The initial algorithms were divided into latitudinal-, seasonal-, and surface-type zones. It was found that these initial algorithms, which were of the D-matrix type, did not yield sufficiently accurate results. The surface-based measurements of channels were investigated; however, the 85V channel was excluded because of excessive noise. It was found that there is no significant correlation between the SSM/I brightness temperatures and the surface-based cloud liquid water determination when the background surface is land or snow. A high correlation was found between brightness temperatures and ground-based measurements over the ocean.

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.

Validation of the Soil Moisture Active Passive (SMAP) satellite soil moisture retrieval in an Arctic tundra environment

NASA Astrophysics Data System (ADS)

Wrona, Elizabeth; Rowlandson, Tracy L.; Nambiar, Manoj; Berg, Aaron A.; Colliander, Andreas; Marsh, Philip

2017-05-01

This study examines the Soil Moisture Active Passive soil moisture product on the Equal Area Scalable Earth-2 (EASE-2) 36 km Global cylindrical and North Polar azimuthal grids relative to two in situ soil moisture monitoring networks that were installed in 2015 and 2016. Results indicate that there is no relationship between the Soil Moisture Active Passive (SMAP) Level-2 passive soil moisture product and the upscaled in situ measurements. Additionally, there is very low correlation between modeled brightness temperature using the Community Microwave Emission Model and the Level-1 C SMAP brightness temperature interpolated to the EASE-2 Global grid; however, there is a much stronger relationship to the brightness temperature measurements interpolated to the North Polar grid, suggesting that the soil moisture product could be improved with interpolation on the North Polar grid.

Preliminary infrared radiometry of the night side of mercury from mariner 10.

PubMed

Chase, S C; Miner, E D; Morrison, D; Münch, G; Neugebauer, G; Schroeder, M

1974-07-12

The infrared radiometer on Mariner 10 measured the thermal emission from the planet with a spatial resolution element as small as 40 kilometers in a broad wavelength band centered at 45 micrometers. The minimum brightness temperature (near local midnight) in these near-equatorial scans was 100 degrees K. Along the track observed, the temperature declined steadily from local sunset to near midnight, behaving as would be expected for a homogeneous, porous material with a thermal inertia of 0.0017 cal cm(-2) sec(-(1/2)) degrees K(-1), a value only slightly larger than that of the moon. From near midnight to dawn, however, the temperature fluctuated over a range of about 10 degrees K, implying the presence of regions having thermal inertia as high as 0.003 cal cm(-2) sec-(1/2) degrees K(-1).

Spectral emissivities and optical constants of electromagnetically levitated liquid metals as functions of temperature and wavelength

NASA Technical Reports Server (NTRS)

Krishnan, S.; Hauge, R. H.; Margrave, J. L.

1989-01-01

The development of a noncontact temperature measurement device utilizing rotating analyzer ellipsometry is described. The technique circumvents the necessity of spectral emissivity estimation by direct measurement concomittant with radiance brightness. Using this approach, the optical properties of electromagnetically levitated liquid metals Cu, Ag, Au, Ni, Pd, Pt, and Zr were measured in situ at four wavelengths and up to 600 K superheat in the liquid. The data suggest an increase in the emissivity of the liquid compared with the incandescent solid. The data also show moderate temperature dependence of the spectral emissivity. A few measurements of the optical properties of undercooled liquid metals were also conducted. The data for both solids and liquids show excellent agreement with available values in the literature for the spectral emissivities as well as the optical constants.

A map of the day-night contrast of the extrasolar planet HD 189733b.

PubMed

Knutson, Heather A; Charbonneau, David; Allen, Lori E; Fortney, Jonathan J; Agol, Eric; Cowan, Nicolas B; Showman, Adam P; Cooper, Curtis S; Megeath, S Thomas

2007-05-10

'Hot Jupiter' extrasolar planets are expected to be tidally locked because they are close (<0.05 astronomical units, where 1 au is the average Sun-Earth distance) to their parent stars, resulting in permanent daysides and nightsides. By observing systems where the planet and star periodically eclipse each other, several groups have been able to estimate the temperatures of the daysides of these planets. A key question is whether the atmosphere is able to transport the energy incident upon the dayside to the nightside, which will determine the temperature at different points on the planet's surface. Here we report observations of HD 189733, the closest of these eclipsing planetary systems, over half an orbital period, from which we can construct a 'map' of the distribution of temperatures. We detected the increase in brightness as the dayside of the planet rotated into view. We estimate a minimum brightness temperature of 973 +/- 33 K and a maximum brightness temperature of 1,212 +/- 11 K at a wavelength of 8 mum, indicating that energy from the irradiated dayside is efficiently redistributed throughout the atmosphere, in contrast to a recent claim for another hot Jupiter. Our data indicate that the peak hemisphere-integrated brightness occurs 16 +/- 6 degrees before opposition, corresponding to a hotspot shifted east of the substellar point. The secondary eclipse (when the planet moves behind the star) occurs 120 +/- 24 s later than predicted, which may indicate a slightly eccentric orbit.

How Different are SMOS Morning and Evening Observations?

NASA Astrophysics Data System (ADS)

Rowlandson, T. L.; Hornbuckle, B. K.

2010-12-01

The Soil Moisture Ocean Salinity (SMOS) satellite was launched by the European Space Agency in November, 2009, to make measurements of soil moisture at L-band in a 40 km x 40 km footprint, making passes over the north central region of the United States at 6am and 6pm approximately, with the intent of having passes at least every 3 days. No comparisons between 6am and 6pm have been made. The NASA Soil Moisture Active Passive (SMAP) intends to use only 6am data because of concerns of the quality of the data for 6pm passes. Brightness temperature outputs of the SMOS data were examined for both the 6am and 6pm passes to determine if changes in measurement exist for days when there is no rainfall. Changes in the brightness temperature can result from changes in internal water content of the crop, which we currently do not have the ability to accurately determine, presence of external water on the canopy, which in this study will be limited to dew, changes in canopy and soil temperature, and changes in soil moisture. The first step taken in this project was to investigating changes between the 6am and 6pm measurements that may result from the presence of dew on the canopy. Land and airborne L-band radiometers have shown that dew on a crop canopy provides a source of error in the measurements of surface soil moisture. The magnitude and sign of the error appears to be crop dependent. The empirical model of RH>90% has been used extensively to simulate dew duration. At the Iowa Validation site in Ames, Iowa, relative humidity was measured above the crop canopy, in both corn and soybeans, and within the crop canopy. Comparisons were made between the relative humidity measured above the canopy to that measured within the canopy at 3 locations within the field. These values were also compared to relative humidity measured at a standard weather station near the field site. These measurements were used to define a more appropriate relative humidity threshold for the central Midwest, specifically where agriculture is a dominant land use. It is important that relative humidity data utilized from a source outside of an agricultural field is representative of the conditions occurring within the crop canopy, which is generally higher. SMOS pixels were chosen for regions where > 75% of the land area was comprised of agriculture. Days were chosen where there was a satellite pass both at 6am and 6pm, on days when no rainfall occurred. As such, changes in soil moisture would be minimal. The brightness temperatures obtained were normalized using the polarization index, which uses both v-pol and h-pol outputs to remove the influence of changes in surface temperature on the brightness temperature. As such, changes in the brightness temperature can be attributed to changes in the water content of the crop canopy or the presence of dew. Identifying changes in the signal between morning and evening passes will aid in determining if the presence of dew on crop canopy is an important source of error in soil moisture measurements at L-band, and more importantly, if 6pm measurements appear to be viable for soil moisture retrieval.

Modelling of the L-band brightness temperatures measured with ELBARA III radiometer on Bubnow wetland

NASA Astrophysics Data System (ADS)

Gluba, Lukasz; Sagan, Joanna; Lukowski, Mateusz; Szlazak, Radoslaw; Usowicz, Boguslaw

2017-04-01

Microwave radiometry has become the main tool for investigating soil moisture (SM) with remote sensing methods. ESA - SMOS (Soil Moisture and Ocean Salinity) satellite operating at L-band provides global distribution of soil moisture. An integral part of SMOS mission are calibration and validation activities involving measurements with ELBARA III which is an L-band microwave passive radiometer. It is done in order to improve soil moisture retrievals - make them more time-effective and accurate. The instrument is located at Bubnow test-site, on the border of cultivated field, fallow, meadow and natural wetland being a part of Polesie National Park (Poland). We obtain both temporal and spatial dependences of brightness temperatures for varied types of land covers with the ELBARA III directed at different azimuths. Soil moisture is retrieved from brightness temperature using L-band Microwave Emission of the Biosphere (L-MEB) model, the same as currently used radiative transfer model for SMOS. Parametrization of L-MEB, as well as input values are still under debate. We discuss the results of SM retrievals basing on data obtained during first year of the radiometer's operation. We analyze temporal dependences of retrieved SM for one-parameter (SM), two-parameter (SM, τ - optical depth) and three-parameter (SM, τ, Hr - roughness parameter) retrievals, as well as spatial dependences for specific dates. Special case of Simplified Roughness Parametrization, combining the roughness parameter and optical depth, is considered. L-MEB processing is supported by the continuous measurements of soil moisture and temperature obtained from nearby agrometeorological station, as well as studies on the soil granulometric composition of the Bubnow test-site area. Furthermore, for better estimation of optical depth, the satellite-derived Normalized Difference Vegetation Index (NDVI) was employed, supported by measured in situ vegetation parameters (such as Leaf Area Index and Vegetation Water Content) obtained during the field campaigns. The values of NDVI around ELBARA III radiometer are provided by Sentinel-2 satellite with approximately 10 m spatial resolution and average 10 days of time interval within studied period of time. The work was partially funded under two ESA projects: 1) "ELBARA_PD (Penetration Depth)" No. 4000107897/13/NL/KML, funded by the Government of Poland through an ESA-PECS contract (Plan for European Cooperating States). 2) "Technical Support for the fabrication and deployment of the radiometer ELBARA-III in Bubnow, Poland" No. 4000113360/15/NL/FF/gp.

Implementation of an Ultra-Bright Thermographic Phosphor for Gas Turbine Engine Temperature Measurements

NASA Technical Reports Server (NTRS)

Eldridge, Jeffrey I.; Bencic, Timothy J.; Zhu, Dongming; Cuy, Michael D.; Wolfe, Douglas E.; Allison, Stephen W.; Beshears, David L.; Jenkins, Thomas P.; Heeg, Bauke; Howard, Robert P.;

Gain and Polarization Properties of a Large Radio Telescope from Calculation and Measurement: The John A. Galt Telescope

NASA Astrophysics Data System (ADS)

Du, X.; Landecker, T. L.; Robishaw, T.; Gray, A. D.; Douglas, K. A.; Wolleben, M.

2016-11-01

Measurement of the brightness temperature of extended radio emission demands knowledge of the gain (or aperture efficiency) of the telescope and measurement of the polarized component of the emission requires correction for the conversion of unpolarized emission from sky and ground to apparently polarized signal. Radiation properties of the John A. Galt Telescope at the Dominion Radio Astrophysical Observatory were studied through analysis and measurement in order to provide absolute calibration of a survey of polarized emission from the entire northern sky from 1280 to 1750 MHz, and to understand the polarization performance of the telescope. Electromagnetic simulation packages CST and GRASP-10 were used to compute complete radiation patterns of the telescope in all Stokes parameters, and thereby to establish gain and aperture efficiency. Aperture efficiency was also evaluated using geometrical optics and ray tracing analysis and was measured based on the known flux density of Cyg A. Measured aperture efficiency varied smoothly with frequency between values of 0.49 and 0.54; GRASP-10 yielded values 6.5% higher but with closely similar variation with frequency. Overall error across the frequency band is 3%, but values at any two frequencies are relatively correct to ˜1%. Dominant influences on aperture efficiency are the illumination taper of the feed radiation pattern and the shadowing of the reflector from the feed by the feed-support struts. A model of emission from the ground was developed based on measurements and on empirical data obtained from remote sensing of the Earth from satellite-borne telescopes. This model was convolved with the computed antenna response to estimate conversion of ground emission into spurious polarized signal. The computed spurious signal is comparable to measured values, but is not accurate enough to be used to correct observations. A simpler model, in which the ground is considered as an unpolarized emitter with a brightness temperature of ˜240 K, is shown to have useful accuracy when compared to measurements.

Using SMOS brightness temperature and derived surface-soil moisture to characterize surface conditions and validate land surface models.

NASA Astrophysics Data System (ADS)

Polcher, Jan; Barella-Ortiz, Anaïs; Piles, Maria; Gelati, Emiliano; de Rosnay, Patricia

2017-04-01

The SMOS satellite, operated by ESA, observes the surface in the L-band. On continental surface these observations are sensitive to moisture and in particular surface-soil moisture (SSM). In this presentation we will explore how the observations of this satellite can be exploited over the Iberian Peninsula by comparing its results with two land surface models : ORCHIDEE and HTESSEL. Measured and modelled brightness temperatures show a good agreement in their temporal evolution, but their spatial structures are not consistent. An empirical orthogonal function analysis of the brightness temperature's error identifies a dominant structure over the south-west of the Iberian Peninsula which evolves during the year and is maximum in autumn and winter. Hypotheses concerning forcing-induced biases and assumptions made in the radiative transfer model are analysed to explain this inconsistency, but no candidate is found to be responsible for the weak spatial correlations. The analysis of spatial inconsistencies between modelled and measured TBs is important, as these can affect the estimation of geophysical variables and TB assimilation in operational models, as well as result in misleading validation studies. When comparing the surface-soil moisture of the models with the product derived operationally by ESA from SMOS observations similar results are found. The spatial correlation over the IP between SMOS and ORCHIDEE SSM estimates is poor (ρ 0.3). A single value decomposition (SVD) analysis of rainfall and SSM shows that the co-varying patterns of these variables are in reasonable agreement between both products. Moreover the first three SVD soil moisture patterns explain over 80% of the SSM variance simulated by the model while the explained fraction is only 52% of the remotely sensed values. These results suggest that the rainfall-driven soil moisture variability may not account for the poor spatial correlation between SMOS and ORCHIDEE products. Other reasons have to be sought to explain the poor agreement in spatial patterns between satellite derived and modelled SSM. This presentation will hopefully contribute to the discussion of how SMOS and other observations can be used to prepare, carry-out and exploit a field campaign over the Iberian Peninsula which aims at improving our understanding of semi-arid land surface processes.

Analysis of Bright Harvest Remote Analysis for Residential Solar Installations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nangle, John; Simon, Joseph

Bright Harvest provides remote shading analysis and design products for residential PV system installers. The National Renewable Energy Laboratory (NREL) through the NREL Commercialization Assistance Program, completed comparative assessments between on-site measurements and remotely calculated values to validate the accuracy of Bright Harvest’s remote shading and power generation.

Physical retrieval of precipitation water contents from Special Sensor Microwave/Imager (SSM/I) data. Part 1: A cloud ensemble/radiative parameterization for sensor response (report version)

NASA Technical Reports Server (NTRS)

Olson, William S.; Raymond, William H.

1990-01-01

The physical retrieval of geophysical parameters based upon remotely sensed data requires a sensor response model which relates the upwelling radiances that the sensor observes to the parameters to be retrieved. In the retrieval of precipitation water contents from satellite passive microwave observations, the sensor response model has two basic components. First, a description of the radiative transfer of microwaves through a precipitating atmosphere must be considered, because it is necessary to establish the physical relationship between precipitation water content and upwelling microwave brightness temperature. Also the spatial response of the satellite microwave sensor (or antenna pattern) must be included in the description of sensor response, since precipitation and the associated brightness temperature field can vary over a typical microwave sensor resolution footprint. A 'population' of convective cells, as well as stratiform clouds, are simulated using a computationally-efficient multi-cylinder cloud model. Ensembles of clouds selected at random from the population, distributed over a 25 km x 25 km model domain, serve as the basis for radiative transfer calculations of upwelling brightness temperatures at the SSM/I frequencies. Sensor spatial response is treated explicitly by convolving the upwelling brightness temperature by the domain-integrated SSM/I antenna patterns. The sensor response model is utilized in precipitation water content retrievals.

Brightness temperature - obtaining the physical properties of a non-equipartition plasma

NASA Astrophysics Data System (ADS)

Nokhrina, E. E.

2017-06-01

The limit on the intrinsic brightness temperature, attributed to `Compton catastrophe', has been established being 1012 K. Somewhat lower limit of the order of 1011.5 K is implied if we assume that the radiating plasma is in equipartition with the magnetic field - the idea that explained why the observed cores of active galactic nuclei (AGNs) sustained the limit lower than the `Compton catastrophe'. Recent observations with unprecedented high resolution by the RadioAstron have revealed systematic exceed in the observed brightness temperature. We propose means of estimating the degree of the non-equipartition regime in AGN cores. Coupled with the core-shift measurements, the method allows us to independently estimate the magnetic field strength and the particle number density at the core. We show that the ratio of magnetic energy to radiating plasma energy is of the order of 10-5, which means the flow in the core is dominated by the particle energy. We show that the magnetic field obtained by the brightness temperature measurements may be underestimated. We propose for the relativistic jets with small viewing angles the non-uniform magnetohydrodynamic model and obtain the expression for the magnetic field amplitude about two orders higher than that for the uniform model. These magnetic field amplitudes are consistent with the limiting magnetic field suggested by the `magnetically arrested disc' model.

SMOS brightness temperature assimilation into the Community Land Model

NASA Astrophysics Data System (ADS)

Rains, Dominik; Han, Xujun; Lievens, Hans; Montzka, Carsten; Verhoest, Niko E. C.

2017-11-01

SMOS (Soil Moisture and Ocean Salinity mission) brightness temperatures at a single incident angle are assimilated into the Community Land Model (CLM) across Australia to improve soil moisture simulations. Therefore, the data assimilation system DasPy is coupled to the local ensemble transform Kalman filter (LETKF) as well as to the Community Microwave Emission Model (CMEM). Brightness temperature climatologies are precomputed to enable the assimilation of brightness temperature anomalies, making use of 6 years of SMOS data (2010-2015). Mean correlation R with in situ measurements increases moderately from 0.61 to 0.68 (11 %) for upper soil layers if the root zone is included in the updates. A reduced improvement of 5 % is achieved if the assimilation is restricted to the upper soil layers. Root-zone simulations improve by 7 % when updating both the top layers and root zone, and by 4 % when only updating the top layers. Mean increments and increment standard deviations are compared for the experiments. The long-term assimilation impact is analysed by looking at a set of quantiles computed for soil moisture at each grid cell. Within hydrological monitoring systems, extreme dry or wet conditions are often defined via their relative occurrence, adding great importance to assimilation-induced quantile changes. Although still being limited now, longer L-band radiometer time series will become available and make model output improved by assimilating such data that are more usable for extreme event statistics.

THE ALMA SPECTROSCOPIC SURVEY IN THE HUBBLE ULTRA DEEP FIELD: IMPLICATIONS FOR SPECTRAL LINE INTENSITY MAPPING AT MILLIMETER WAVELENGTHS AND CMB SPECTRAL DISTORTIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carilli, C. L.; Walter, F.; Chluba, J.

We present direct estimates of the mean sky brightness temperature in observing bands around 99 and 242 GHz due to line emission from distant galaxies. These values are calculated from the summed line emission observed in a blind, deep survey for spectral line emission from high redshift galaxies using ALMA (the ALMA spectral deep field observations “ASPECS” survey). In the 99 GHz band, the mean brightness will be dominated by rotational transitions of CO from intermediate and high redshift galaxies. In the 242 GHz band, the emission could be a combination of higher order CO lines, and possibly [C ii]more » 158 μ m line emission from very high redshift galaxies ( z  ∼ 6–7). The mean line surface brightness is a quantity that is relevant to measurements of spectral distortions of the cosmic microwave background, and as a potential tool for studying large-scale structures in the early universe using intensity mapping. While the cosmic volume and the number of detections are admittedly small, this pilot survey provides a direct measure of the mean line surface brightness, independent of conversion factors, excitation, or other galaxy formation model assumptions. The mean surface brightness in the 99 GHZ band is: T{sub B}  = 0.94 ± 0.09 μ K. In the 242 GHz band, the mean brightness is: T{sub B}  = 0.55 ± 0.033 μ K. These should be interpreted as lower limits on the average sky signal, since we only include lines detected individually in the blind survey, while in a low resolution intensity mapping experiment, there will also be the summed contribution from lower luminosity galaxies that cannot be detected individually in the current blind survey.« less

LOFAR observations of the quiet solar corona

NASA Astrophysics Data System (ADS)

Vocks, C.; Mann, G.; Breitling, F.; Bisi, M. M.; Dąbrowski, B.; Fallows, R.; Gallagher, P. T.; Krankowski, A.; Magdalenić, J.; Marqué, C.; Morosan, D.; Rucker, H.

2018-06-01

Context. The quiet solar corona emits meter-wave thermal bremsstrahlung. Coronal radio emission can only propagate above that radius, Rω, where the local plasma frequency equals the observing frequency. The radio interferometer LOw Frequency ARray (LOFAR) observes in its low band (10-90 MHz) solar radio emission originating from the middle and upper corona. Aims: We present the first solar aperture synthesis imaging observations in the low band of LOFAR in 12 frequencies each separated by 5 MHz. From each of these radio maps we infer Rω, and a scale height temperature, T. These results can be combined into coronal density and temperature profiles. Methods: We derived radial intensity profiles from the radio images. We focus on polar directions with simpler, radial magnetic field structure. Intensity profiles were modeled by ray-tracing simulations, following wave paths through the refractive solar corona, and including free-free emission and absorption. We fitted model profiles to observations with Rω and T as fitting parameters. Results: In the low corona, Rω < 1.5 solar radii, we find high scale height temperatures up to 2.2 × 106 K, much more than the brightness temperatures usually found there. But if all Rω values are combined into a density profile, this profile can be fitted by a hydrostatic model with the same temperature, thereby confirming this with two independent methods. The density profile deviates from the hydrostatic model above 1.5 solar radii, indicating the transition into the solar wind. Conclusions: These results demonstrate what information can be gleaned from solar low-frequency radio images. The scale height temperatures we find are not only higher than brightness temperatures, but also than temperatures derived from coronograph or extreme ultraviolet (EUV) data. Future observations will provide continuous frequency coverage. This continuous coverage eliminates the need for local hydrostatic density models in the data analysis and enables the analysis of more complex coronal structures such as those with closed magnetic fields.

Far infrared and submillimeter brightness temperatures of the giant planets

NASA Technical Reports Server (NTRS)

Hildebrand, R. H.; Loewenstein, R. F.; Harper, D. A.; Orton, G. S.; Keene, J.; Whitcomb, S. E.

1985-01-01

The brightness temperatures of Jupiter, Saturn, Uranus, and Neptune in the range 35 to 1000 micron. The effective temperatures derived from the measurements, supplemented by shorter wavelength Voyager data for Jupiter and Saturn, are 126.8 + or - 4.5 K, 93.4 + or - 3.3 K, 58.3 + or - 2.0 K, and 60.3 + or - 2.0 K, respectively. The implications of the measurements for bolometric output and for atmospheric structure and composition are discussed. The temperature spectrum of Jupiter shows a strong peak at approx. 350 microns followed by a deep valley at approx. 450 to 500 microns. Spectra derived from model atmospheres qualitatively reproduced these features but do not fit the data closely.

Determination of mean rainfall from the Special Sensor Microwave/Imager (SSM/I) using a mixed lognormal distribution

NASA Technical Reports Server (NTRS)

Berg, Wesley; Chase, Robert

1992-01-01

Global estimates of monthly, seasonal, and annual oceanic rainfall are computed for a period of one year using data from the Special Sensor Microwave/Imager (SSM/I). Instantaneous rainfall estimates are derived from brightness temperature values obtained from the satellite data using the Hughes D-matrix algorithm. The instantaneous rainfall estimates are stored in 1 deg square bins over the global oceans for each month. A mixed probability distribution combining a lognormal distribution describing the positive rainfall values and a spike at zero describing the observations indicating no rainfall is used to compute mean values. The resulting data for the period of interest are fitted to a lognormal distribution by using a maximum-likelihood. Mean values are computed for the mixed distribution and qualitative comparisons with published historical results as well as quantitative comparisons with corresponding in situ raingage data are performed.

THERMODYNAMICS OF THE COMA CLUSTER OUTSKIRTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simionescu, A.; Werner, N.; Urban, O.

2013-09-20

We present results from a large mosaic of Suzaku observations of the Coma Cluster, the nearest and X-ray brightest hot ({approx}8 keV), dynamically active, non-cool core system, focusing on the thermodynamic properties of the intracluster medium on large scales. For azimuths not aligned with an infalling subcluster toward the southwest, our measured temperature and X-ray brightness profiles exhibit broadly consistent radial trends, with the temperature decreasing from about 8.5 keV at the cluster center to about 2 keV at a radius of 2 Mpc, which is the edge of our detection limit. The southwest merger significantly boosts the surface brightness,more » allowing us to detect X-ray emission out to {approx}2.2 Mpc along this direction. Apart from the southwestern infalling subcluster, the surface brightness profiles show multiple edges around radii of 30-40 arcmin. The azimuthally averaged temperature profile, as well as the deprojected density and pressure profiles, all show a sharp drop consistent with an outwardly-propagating shock front located at 40 arcmin, corresponding to the outermost edge of the giant radio halo observed at 352 MHz with the Westerbork Synthesis Radio Telescope. The shock front may be powering this radio emission. A clear entropy excess inside of r{sub 500} reflects the violent merging events linked with these morphological features. Beyond r{sub 500}, the entropy profiles of the Coma Cluster along the relatively relaxed directions are consistent with the power-law behavior expected from simple models of gravitational large-scale structure formation. The pressure is also in agreement at these radii with the expected values measured from Sunyaev-Zel'dovich data from the Planck satellite. However, due to the large uncertainties associated with the Coma Cluster measurements, we cannot yet exclude an entropy flattening in this system consistent with that seen in more relaxed cool core clusters.« less

Retrieval of an ice water path over the ocean from ISMAR and MARSS millimeter and submillimeter brightness temperatures

NASA Astrophysics Data System (ADS)

Brath, Manfred; Fox, Stuart; Eriksson, Patrick; Chawn Harlow, R.; Burgdorf, Martin; Buehler, Stefan A.

2018-02-01

A neural-network-based retrieval method to determine the snow ice water path (SIWP), liquid water path (LWP), and integrated water vapor (IWV) from millimeter and submillimeter brightness temperatures, measured by using airborne radiometers (ISMAR and MARSS), is presented. The neural networks were trained by using atmospheric profiles from the ICON numerical weather prediction (NWP) model and by radiative transfer simulations using the Atmospheric Radiative Transfer Simulator (ARTS). The basic performance of the retrieval method was analyzed in terms of offset (bias) and the median fractional error (MFE), and the benefit of using submillimeter channels was studied in comparison to pure microwave retrievals. The retrieval is offset-free for SIWP > 0.01 kg m-2, LWP > 0.1 kg m-2, and IWV > 3 kg m-2. The MFE of SIWP decreases from 100 % at SIWP = 0.01 kg m-2 to 20 % at SIWP = 1 kg m-2 and the MFE of LWP from 100 % at LWP = 0.05 kg m-2 to 30 % at LWP = 1 kg m-2. The MFE of IWV for IWV > 3 kg m-2 is 5 to 8 %. The SIWP retrieval strongly benefits from submillimeter channels, which reduce the MFE by a factor of 2, compared to pure microwave retrievals. The IWV and the LWP retrievals also benefit from submillimeter channels, albeit to a lesser degree. The retrieval was applied to ISMAR and MARSS brightness temperatures from FAAM flight B897 on 18 March 2015 of a precipitating frontal system west of the coast of Iceland. Considering the given uncertainties, the retrieval is in reasonable agreement with the SIWP, LWP, and IWV values simulated by the ICON NWP model for that flight. A comparison of the retrieved IWV with IWV from 12 dropsonde measurements shows an offset of 0.5 kg m-2 and an RMS difference of 0.8 kg m-2, showing that the retrieval of IWV is highly effective even under cloudy conditions.

Surface-induced brightness temperature variations and their effects on detecting thin cirrus clouds using IR emission channels in the 8-12 micrometer region

NASA Technical Reports Server (NTRS)

Gao, Bo-Cai; Wiscombe, W. J.

1993-01-01

A method for detecting cirrus clouds in terms of brightness temperature differences between narrow bands at 8, 11, and 12 mu m has been proposed by Ackerman et al. (1990). In this method, the variation of emissivity with wavelength for different surface targets was not taken into consideration. Based on state-of-the-art laboratory measurements of reflectance spectra of terrestrial materials by Salisbury and D'Aria (1992), we have found that the brightness temperature differences between the 8 and 11 mu m bands for soils, rocks and minerals, and dry vegetation can vary between approximately -8 K and +8 K due solely to surface emissivity variations. We conclude that although the method of Ackerman et al. is useful for detecting cirrus clouds over areas covered by green vegetation, water, and ice, it is less effective for detecting cirrus clouds over areas covered by bare soils, rocks and minerals, and dry vegetation. In addition, we recommend that in future the variation of surface emissivity with wavelength should be taken into account in algorithms for retrieving surface temperatures and low-level atmospheric temperature and water vapor profiles.

Crop moisture estimation over the southern Great Plains with dual polarization 1.66 centimeter passive microwave data from Nimbus 7

NASA Technical Reports Server (NTRS)

Mcfarland, M. J.; Harder, P. H., II; Wilke, G. D.; Huebner, G. L., Jr.

1984-01-01

Moisture content of snow-free, unfrozen soil is inferred using passive microwave brightness temperatures from the scanning multichannel microwave radiometer (SMMR) on Nimbus-7. Investigation is restricted to the two polarizations of the 1.66 cm wavelength sensor. Passive microwave estimates of soil moisture are of two basic categories; those based upon soil emissivity and those based upon the polarization of soil emission. The two methods are compared and contrasted through the investigation of 54 potential functions of polarized brightness temperatures and, in some cases, ground-based temperature measurements. Of these indices, three are selected for the estimated emissivity, the difference between polarized brightness temperatures, and the normalized polarization difference. Each of these indices is about equally effective for monitoring soil moisture. Using an antecedent precipitation index (API) as ground control data, temporal and spatial analyses show that emissivity data consistently give slightly better soil moisture estimates than depolarization data. The difference, however, is not statistically significant. It is concluded that polarization data alone can provide estimates of soil moisture in areas where the emissivity cannot be inferred due to nonavailability of surface temperature data.

How much material do the radar-bright craters at the Mercurian poles contain?

NASA Astrophysics Data System (ADS)

Vilas, Faith; Cobian, Paul S.; Barlow, Nadine G.; Lederer, Susan M.

2005-12-01

The depth-to-diameter (d/D) ratios were determined for 12 craters located near the Mercurian north pole that were identified by Harmon et al. (2001, Icarus 149) as having strong depolarized radar echos. We find that the mean d/D value of these radar-bright craters is {2}/{3} the mean d/D value of the general population of non-radar-bright craters in the surrounding north polar region. Previous studies, however, show no difference between d/D values of Mercurian polar and equatorial crater populations, suggesting that no terrain softening which could modify crater structure exists at the Mercurian poles (Barlow et al., 1999, 194, Icarus 141). Thus, the change in d/D is governed by a change in crater depth, probably due to deposition of material inside the crater. The volume of infilling material, including volatiles, in the radar-bright craters is significantly greater than predicted by proposed mechanisms for the emplacement of either water ice or sulfur.

Relative spectral response corrected calibration inter-comparison of S-NPP VIIRS and Aqua MODIS thermal emissive bands

NASA Astrophysics Data System (ADS)

Efremova, Boryana; Wu, Aisheng; Xiong, Xiaoxiong

2014-09-01

The S-NPP Visible Infrared Imaging Radiometer Suite (VIIRS) instrument is built with strong heritage from EOS MODIS, and has very similar thermal emissive bands (TEB) calibration algorithm and on-board calibrating source - a V-grooved blackbody. The calibration of the two instruments can be assessed by comparing the brightness temperatures retrieved from VIIRS and Aqua MODIS simultaneous nadir observations (SNO) from their spectrally matched TEB. However, even though the VIIRS and MODIS bands are similar there are still relative spectral response (RSR) differences and thus some differences in the retrieved brightness temperatures are expected. The differences depend on both the type and the temperature of the observed scene, and contribute to the bias and the scatter of the comparison. In this paper we use S-NPP Cross-track Infrared Sounder (CrIS) data taken simultaneously with the VIIRS data to derive a correction for the slightly different spectral coverage of VIIRS and MODIS TEB bands. An attempt to correct for RSR differences is also made using MODTRAN models, computed with physical parameters appropriate for each scene, and compared to the value derived from actual CrIS spectra. After applying the CrIS-based correction for RSR differences we see an excellent agreement between the VIIRS and Aqua MODIS measurements in the studied band pairs M13-B23, M15-B31, and M16- B32. The agreement is better than the VIIRS uncertainty at cold scenes, and improves with increasing scene temperature up to about 290K.

Development of Yellow Sand Image Products Using Infrared Brightness Temperature Difference Method

NASA Astrophysics Data System (ADS)

Ha, J.; Kim, J.; Kwak, M.; Ha, K.

2007-12-01

A technique for detection of airborne yellow sand dust using meteorological satellite has been developed from various bands from ultraviolet to infrared channels. Among them, Infrared (IR) channels have an advantage of detecting aerosols over high reflecting surface as well as during nighttime. There had been suggestion of using brightness temperature difference (BTD) between 11 and 12¥ìm. We have found that the technique is highly depends on surface temperature, emissivity, and zenith angle, which results in changing the threshold of BTD. In order to overcome these problems, we have constructed the background brightness temperature threshold of BTD and then aerosol index (AI) has been determined from subtracting the background threshold from BTD of our interested scene. Along with this, we utilized high temporal coverage of geostationary satellite, MTSAT, to improve the reliability of the determined AI signal. The products have been evaluated by comparing the forecasted wind field with the movement fiend of AI. The statistical score test illustrates that this newly developed algorithm produces a promising result for detecting mineral dust by reducing the errors with respect to the current BTD method.

The effect of a change in sleep-wakefulness timing, bright light and physical exercise interventions on 24-hour patterns of performance, mood and body temperature.

PubMed

Iskra-Golec, I; Fafrowicz, M; Marek, T; Costa, G; Folkard, S; Foret, J; Kundi, M; Smith, L

2001-12-01

Experiments consisting of baseline, bright light and physical exercise studies were carried out to compare the effect of a 9-hour delay in sleep-wakefulness timing, and the effects of bright light and physical exercise interventions on 24-hour patterns of performance, mood and body temperature were examined. Each study comprised a 24-hour constant routine at the beginning followed by 3 night shifts and 24-hour constant routine at the end. Performance on tasks differing in cognitive load, mood and body temperature was measured during each constant routine and the interventions were applied during the night shifts. The 24-hour pattern of alertness and performance on the tasks with low cognitive load in post-treatment conditions followed the change in sleep-wakefulness timing while more cognitively loaded tasks tended to show a reverse trend when compared to pre-treatment conditions. There was a phase delay around 4 hours in circadian rhythms of body temperature in post-treatment conditions.

Summer season variability of the north residual cap of Mars as observed by the Mars Global Surveyor Thermal Emission Spectrometer (MGS-TES)

USGS Publications Warehouse

Calvin, W.M.; Titus, T.N.

2008-01-01

Previous observations have noted the change in albedo in a number of North Pole bright outliers and in the distribution of bright ice deposits between Mariner 9, Viking, and Mars Global Surveyor (MGS) data sets. Changes over the summer season as well as between regions at the same season (Ls) in different years have been observed. We used the bolometric albedo and brightness temperature channels of the Thermal Emission Spectrometer (TES) on the MGS spacecraft to monitor north polar residual ice cap variations between Mars years and within the summer season for three northern Martian summers between July 1999 and April 2003. Large-scale brightness variations are observed in four general areas: (1) the patchy outlying frost deposits from 90 to 270??E, 75 to 80??N; (2) the large "tail" below the Chasma Boreale and its associated plateau from 315 to 45??E, 80 to 85??N, that we call the "Boreale Tongue" and in Hyperboreae Undae; (3) the troughed terrain in the region from 0 to 120??E longitude (the lower right on a polar stereographic projection) we have called "Shackleton's Grooves" and (4) the unit mapped as residual ice in Olympia Planitia. We also note two areas which seem to persist as cool and bright throughout the summer and between Mars years. One is at the "source" of Chasma Boreale (???15??E, 85??N) dubbed "McMurdo", and the "Cool and Bright Anomaly (CABA)" noted by Kieffer and Titus 2001. TES Mapping of Mars' north seasonal cap. Icarus 154, 162-180] at ???330??E, 87??N called here "Vostok". Overall defrosting occurs early in the summer as the temperatures rise and then after the peak temperatures are reached (Ls???110) higher elevations and outlier bright deposits cold trap and re-accumulate new frost. Persistent bright areas are associated with either higher elevations or higher background albedos suggesting complex feedback mechanisms including cold-trapping of frost due to albedo and elevation effects, as well as influence of mesoscale atmospheric dynamics. ?? 2007 Elsevier Ltd. All rights reserved.

Radio and gamma-ray properties of extragalactic jets from the TANAMI sample

DOE PAGES

Böck, M.; Kadler, M.; Müller, C.; ...

2016-05-04

The TANAMI program has been observing parsec-scale radio jets of southern (declination south of - 30°) γ-ray bright AGN, simultaneously with Fermi/LAT monitoring of their γ-ray emission, via high-resolution radio imaging with Very Long Baseline Interferometry techniques. In this paper, we present the radio and γ-rayproperties of the TANAMI sources based on one year of contemporaneous TANAMI and Fermi/LAT data. A large fraction (72%) of the TANAMI sample can be associated with bright γ-ray sources for this time range. Association rates differ for different optical classes with all BL Lacs, 76% of quasars, and just 17% of galaxies detected bymore » the LAT. Upper limits were established on the γ-ray flux from TANAMI sources not detected by LAT. This analysis led to the identification of three new Fermi sources whose detection was later confirmed. The γ-ray and radio luminosities are related by L γ ∝ L r 0.89±0.04. The brightness temperatures of the radio cores increase with the average γ-ray luminosity and the presence of brightness temperatures above the inverse Compton limit implies strong Doppler boosting in those sources. The undetected sources have lower γ/radio luminosity ratios and lower contemporaneous brightness temperatures. Finally, unless the Fermi/LAT-undetected blazars are much γ-ray-fainter than the Fermi/LAT-detected sources, their γ-ray luminosity should not be significantly lower than the upper limits calculated here.« less

Is blue intensity ready to replace maximum latewood density as a strong temperature proxy? A tree-ring case study on Scots pine from northern Sweden

NASA Astrophysics Data System (ADS)

Björklund, J. A.; Gunnarson, B. E.; Seftigen, K.; Esper, J.; Linderholm, H. W.

2013-09-01

At high latitudes, where low temperatures mainly limit tree-growth, measurements of wood density (e.g. Maximum Latewood Density, MXD) using the X-Ray methodology provide a temperature proxy that is superior to that of TRW. Density measurements are however costly and time consuming and have lead to experimentation with optical flatbed scanners to produce Maximum Blue Intensity (BImax). BImax is an excellent proxy for density on annual scale but very limited in skill on centennial scale. Discolouration between samples is limiting BImax where specific brightnesses can have different densities. To overcome this, the new un-exploited parameter Δ blue intensity (ΔBI) was constructed by using the brightness in the earlywood (BIEW) as background, (BImax - BIEW = ΔBI). This parameter was tested on X-Ray material (MXD - earlywood density = ΔMXD) and showed great potential both as a quality control and as a booster of climate signals. Unfortunately since the relationship between grey scale and density is not linear, and between-sample brightness can differ tremendously for similar densities, ΔBI cannot fully match ΔMXD in skill as climate proxy on centennial scale. For ΔBI to stand alone, the range of brightness/density offset must be reduced. Further studies are needed to evaluate this possibility, and solutions might include heavier sample treatment (reflux with chemicals) or image-data treatment (digitally manipulating base-line levels of brightness).

Surface and Atmospheric Contributions to Passive Microwave Brightness Temperatures for Falling Snow Events

NASA Technical Reports Server (NTRS)

Skofronick-Jackson, Gail; Johnson, Benjamin T.

2011-01-01

Physically based passive microwave precipitation retrieval algorithms require a set of relationships between satellite -observed brightness temperatures (TBs) and the physical state of the underlying atmosphere and surface. These relationships are nonlinear, such that inversions are ill ]posed especially over variable land surfaces. In order to elucidate these relationships, this work presents a theoretical analysis using TB weighting functions to quantify the percentage influence of the TB resulting from absorption, emission, and/or reflection from the surface, as well as from frozen hydrometeors in clouds, from atmospheric water vapor, and from other contributors. The percentage analysis was also compared to Jacobians. The results are presented for frequencies from 10 to 874 GHz, for individual snow profiles, and for averages over three cloud-resolving model simulations of falling snow. The bulk structure (e.g., ice water path and cloud depth) of the underlying cloud scene was found to affect the resultant TB and percentages, producing different values for blizzard, lake effect, and synoptic snow events. The slant path at a 53 viewing angle increases the hydrometeor contributions relative to nadir viewing channels. Jacobians provide the magnitude and direction of change in the TB values due to a change in the underlying scene; however, the percentage analysis provides detailed information on how that change affected contributions to the TB from the surface, hydrometeors, and water vapor. The TB percentage information presented in this paper provides information about the relative contributions to the TB and supplies key pieces of information required to develop and improve precipitation retrievals over land surfaces.

The night sky brightness at McDonald Observatory

NASA Technical Reports Server (NTRS)

Kalinowski, J. K.; Roosen, R. G.; Brandt, J. C.

1975-01-01

Baseline observations of the night sky brightness in B and V are presented for McDonald Observatory. In agreement with earlier work by Elvey and Rudnick (1937) and Elvey (1943), significant night-to-night and same-night variations in sky brightness are found. Possible causes for these variations are discussed. The largest variation in sky brightness found during a single night is approximately a factor of two, a value which corresponds to a factor-of-four variation in airglow brightness. The data are used to comment on the accuracy of previously published surface photometry of M 81.

A satellite technique for quantitatively mapping rainfall rates over the oceans

NASA Technical Reports Server (NTRS)

Wilheit, T. T.; Roa, M. S. V.; Chang, T. C.; Rodgers, E. B.; Theon, J. S.

1975-01-01

A theoretical model for calculating microwave radiative transfer in raining atmospheres is developed. These calculations are compared with microwave brightness temperatures at a wavelength of 1.55 cm measured on the Nimbus-5 satellite and rain rates derived from WSR-57 meteorological radar measurements. A specially designed ground based verification experiment was also performed wherein upward viewing microwave brightness temperature measurements at wavelengths of 1.55 cm and 0.81 cm were compared with directly measured rain rates.

Evaluation and Analysis of SEASAT-A Scanning Multichannel Microwave Radiometer (SSMR) Antenna Pattern Correction (APC) Algorithm. Sub-task 4: Interim Mode T Sub B Versus Cross and Nominal Mode T Sub B

NASA Technical Reports Server (NTRS)

Kitzis, J. L.; Kitzis, S. N.

1979-01-01

The brightness temperature data produced by the SMMR Antenna Pattern Correction algorithm are evaluated. The evaluation consists of: (1) a direct comparison of the outputs of the interim, cross, and nominal APC modes; (2) a refinement of the previously determined cos beta estimates; and (3) a comparison of the world brightness temperature (T sub B) map with actual SMMR measurements.

Simple Forest Canopy Thermal Exitance Model

NASA Technical Reports Server (NTRS)

Smith J. A.; Goltz, S. M.

1999-01-01

We describe a model to calculate brightness temperature and surface energy balance for a forest canopy system. The model is an extension of an earlier vegetation only model by inclusion of a simple soil layer. The root mean square error in brightness temperature for a dense forest canopy was 2.5 C. Surface energy balance predictions were also in good agreement. The corresponding root mean square errors for net radiation, latent, and sensible heat were 38.9, 30.7, and 41.4 W/sq m respectively.

Satellite passive microwave rain rate measurement over croplands during spring, summer and fall

NASA Technical Reports Server (NTRS)

Spencer, R. W.

1984-01-01

Rain-rate algorithms for spring, summer and fall that have been developed from comparisons between the brightness temperatures measured by the Nimbus-7 Scanning Multichannel Microwave Radiometer (SMMR) and rain rates derived from operational WSR-57 radars over land are described. Data were utilized from a total of 25 SMMR passes and 234 radars, resulting in about 12,000 observations of about 1600 sq/km areas. Multiple correlation coefficients of 0.63, 0.80 and 0.75 are achieved for the spring, summer and fall algorithms, respectively. Most of this information is in the form of multifrequency contrast in brightness temperature, which is interpreted as a measurement of the degree to which the land-emitted radiation is attenuated by the rain systems. The SMMR 37-GHz channel has more information on rain rate than any other channel. By combining the lower frequency channels with the 37-GHz observations, variations in land and precipitation thermometric temperatures can be removed, leaving rain attenuation as the major effect on brightness temperature. Polarization screening at 37 GHz is found to be sufficient to screen out cases of wet ground, which is only important when the ground is relatively vegetation free. Heavy rain cases are found to be significant part of the algorithms' success, because of the strong microwve signatures (low-brightness temperatures) that result from the presence of precipitation-sized ice in the upper portions of heavily precipitating storms. If IR data are combined with the summer microwave data, an improved (0.85) correlation with radar rain rates is achieved.

Research of the relationships between light dispersion and contrast of the registered image at different background brightness

NASA Astrophysics Data System (ADS)

Stoyanov, Stiliyan; Mardirossian, Garo

2012-10-01

The light diffraction is for telescope apparatuses an especially important characteristic which has an influence on the record image contrast from the eye observer. The task of the investigation is to determine to what degree the coefficient of light diffraction influences the record image brightness. The object of the theoretical research are experimental results provided from a telescope system experiment in the process of observation of remote objects with different brightness of the background in the fixed light diffraction coefficients and permanent contrast of the background in respect to the object. The received values and the ratio of the image contrast to the light diffraction coefficient is shown in a graphic view. It's settled that with increasing of the value of background brightness in permanent background contrast in respect to the object, the image contrast sharply decrease. The relationship between the increase of the light diffraction coefficient and the decrease of the brightness of the project image from telescope apparatuses can be observed.

The treatment of early-morning awakening insomnia with 2 evenings of bright light.

PubMed

Lack, Leon; Wright, Helen; Kemp, Kristyn; Gibbon, Samantha

2005-05-01

To assess the effectiveness of brief bright-light therapy for the treatment of early-morning awakening insomnia. Twenty-four healthy adults with early-morning awakening insomnia were assigned to either the bright-light condition (2,500-lux white light) or the control (dim red light) condition. The circadian phase of rectal temperature and urinary melatonin rhythms were assessed with 26-hour constant routines before and after 2 evenings of light therapy. Sleep and daytime functioning were monitored using sleep diaries, activity monitors, and mood scales before light therapy and for 4 weeks during the follow-up period. While there were no significant circadian phase changes in the dim-light control group, the bright-light group had significant 2-hour phase delays of circadian temperature and melatonin rhythm. Compared to pretreatment measures, over the 4-week follow-up period, the bright-light group had a greater reduction of time awake after sleep onset, showed a trend toward waking later, and had a greater increase of total sleep time. Participants in the bright-light condition also tended to report greater reductions of negative daytime symptoms, including significantly fewer days of feeling depressed at the 4-week follow-up, as compared with the control group. Two evenings of bright-light exposure phase delayed the circadian rhythms of early-morning awakening insomniacs. It also improved diary and actigraphy sleep measures and improved some indexes of daytime functioning for up to 1 month after light exposure. The study suggests that a brief course of evening bright-light therapy can be an effective treatment for early-morning awakening insomniacs who have relatively phase advanced circadian rhythms.

Color reduction of sulfonated eucalyptus kraft lignin.

PubMed

Zhang, Hui; Bai, Youcan; Zhou, Wanpeng; Chen, Fangeng

2017-04-01

Several eucalyptus lignins named as HSL, SML and BSL were prepared by high temperature sulfonation, sulfomethylation, butane sultone sulfonation respectively. The color properties of samples were investigated. Under optimized conditions the sulfonic group (SO 3 H) content of HSL, SML and BSL reached 1.52, 1.60 and 1.58mmol/g, respectively. Samples were characterized by UV-vis spectroscopy, FTIR spectroscopy, 1 H NMR spectroscopy, GPC and brightness test, respectively. The results revealed that BSL performed a higher molecular weight and lighter color due to the phenolic hydroxyl blocking by 1,4-butane sultone (1,4-BS). The color reduction of sodium borohydride treated BSL (labeled as SBSL) was further enhanced and the brightness value was improved by 76.1% compared with the darkest HSL. SBSL process was much better than HSL and SML process. Hydroxyl blocking effect of 1,4-BS and reducibility of sodium borohydride played important roles in the color reduction of sulfonated eucalyptus kraft lignin. Copyright © 2017 Elsevier B.V. All rights reserved.

Influence of Forest-Canopy Morphology and Relief on Spectral Characteristics of Taiga Forests

NASA Astrophysics Data System (ADS)

Zhirin, V. M.; Knyazeva, S. V.; Eydlina, S. P.

2017-12-01

The article deals with the results of a statistical analysis reflecting tendencies (trends) of the relationship between spectral characteristics of taiga forests, indicators of the morphological structure of forest canopy and illumination of the territory. The study was carried out on the example of the model forest territory of the Priangarskiy taiga region of Eastern Siberia (Krasnoyarsk krai) using historical data (forest inventory 1992, Landsat 5 TM 16.06.1989) and the digital elevation model. This article describes a method for determining the quantitative indicator of morphological structure of forest canopy based on taxation data, and the authors propose to subdivide the morphological structure into high complexity, medium complexity, and relatively simple. As a result of the research, dependences of average values of spectral brightness in near and short-wave infrared channels of a Landsat 5 TM image for dark-coniferous, light-coniferous and deciduous forests from the degree of complexity of the forest-canopy structure are received. A high level of variance and maximum brightness average values are marked in green moss (hilocominosa) dark-coniferous and various-grass (larioherbosa) dark-coniferous forests and light-coniferous forests with a complex structure of canopy. The parvifoliate forests are characterized by high values of brightness in stands with a relatively simple structure of the canopy and by a small variance in brightness of any degree of the structure of the canopy complexity. The increase in brightness for the lit slopes in comparison with shaded ones in all stands with a difficult morphological canopy structure is revealed. However, the brightness values of the lit and shaded slopes do not differ for stands with a medium complexity of the structure. It is noted that, in addition to the indicator of the forest-canopy structure, the possible impact on increasing the variance of spectral brightness for the taxation plot has a variability of the slope ratio of "microslopes" inside the forest plot if it exceeds 60%.

Low-level water vapor fields from the VAS split-window channels at 11 and 12 microns

NASA Technical Reports Server (NTRS)

Chesters, D.; Uccellini, L. W.; Robinson, W.

1983-01-01

Originally, the VAS split window channels were designed to use the differential water vapor absorption between 11 and 12 microns to estimate sea surface temperature by correcting for the radiometric losses caused by atmospheric moisture. It is shown that it is possible to reverse the procedure in order to estimate the vertically integrated low level moisture content with the background surface (skin) temperature removed, even over the bright, complex background of the land. Because the lower troposphere's water vapor content is an important factor in convective instability, the derived fields are of considerable value to mesoscale meteorology. Moisture patterns are available as quantitative fields (centimeters of precipitable water) at full VAS resolution (as fine as 7 kilometers horizontal resolution every 15 minutes), and are readily converted to image format for false color movies. The technique, demonstrated with GOES-5, uses a sequence of split window radiances taken once every 3 hours from dawn to dusk over the Eastern and Central United States. The algorithm is calibrated with the morning radiosonde sites embedded within the first VAS radiance field; then, entire moisture fields are calculated at all five observation times. Cloud contamination is removed by rejecting any pixel having a radiance less than the atmospheric brightness determined at the radiosonde sites.

Multi-scale assimilation of remotely sensed snow observations for hydrologic estimation

NASA Astrophysics Data System (ADS)

Andreadis, K.; Lettenmaier, D.

2008-12-01

Data assimilation provides a framework for optimally merging model predictions and remote sensing observations of snow properties (snow cover extent, water equivalent, grain size, melt state), ideally overcoming limitations of both. A synthetic twin experiment is used to evaluate a data assimilation system that would ingest remotely sensed observations from passive microwave and visible wavelength sensors (brightness temperature and snow cover extent derived products, respectively) with the objective of estimating snow water equivalent. Two data assimilation techniques are used, the Ensemble Kalman filter and the Ensemble Multiscale Kalman filter (EnMKF). One of the challenges inherent in such a data assimilation system is the discrepancy in spatial scales between the different types of snow-related observations. The EnMKF represents the sample model error covariance with a tree that relates the system state variables at different locations and scales through a set of parent-child relationships. This provides an attractive framework to efficiently assimilate observations at different spatial scales. This study provides a first assessment of the feasibility of a system that would assimilate observations from multiple sensors (MODIS snow cover and AMSR-E brightness temperatures) and at different spatial scales for snow water equivalent estimation. The relative value of the different types of observations is examined. Additionally, the error characteristics of both model and observations are discussed.

Influence of hydrogenated oil as cocoa butter replacers in the development of sugar-free compound chocolates: Use of inulin as stabilizing agent.

PubMed

Rodriguez Furlán, Laura T; Baracco, Yanina; Lecot, Javier; Zaritzky, Noemi; Campderrós, Mercedes E

2017-02-15

The effect of the addition of inulin as a surfactant or stability agent on white compound chocolate sweetened with sucralose and Stevia was studied. Samples were stored at 7, 15 and 30°C during 100days and the influence of inulin on rheological properties, sensorial attributes, shelf-life, physical properties such as melting, crystallization and blooming were analyzed. The shelf-life of the compound chocolate with the incorporation of inulin was higher than the control sample without replacement. Compound chocolate with inulin at 10%w/w showed a dense matrix structure, reducing the size and number of fat crystals formed during storage; furthermore they presented higher values of brightness and WI. This chocolate also showed less fracturability and improved thermal properties. DSC studies revealed increased values of onset and peak temperatures and enthalpy of melting of the polymorphic form V, at higher storage temperatures, achieving greater stability against degradation processes. Copyright © 2016 Elsevier Ltd. All rights reserved.

Method and apparatus for free-space quantum key distribution in daylight

DOEpatents

Hughes, Richard J.; Buttler, William T.; Lamoreaux, Steve K.; Morgan, George L.; Nordholt, Jane E.; Peterson, C. Glen; Kwiat, Paul G.

2004-06-08

A quantum cryptography apparatus securely generates a key to be used for secure transmission between a sender and a receiver connected by an atmospheric transmission link. A first laser outputs a timing bright light pulse; other lasers output polarized optical data pulses after having been enabled by a random bit generator. Output optics transmit output light from the lasers that is received by receiving optics. A first beam splitter receives light from the receiving optics, where a received timing bright light pulse is directed to a delay circuit for establishing a timing window for receiving light from the lasers and where an optical data pulse from one of the lasers has a probability of being either transmitted by the beam splitter or reflected by the beam splitter. A first polarizer receives transmitted optical data pulses to output one data bit value and a second polarizer receives reflected optical data pulses to output a second data bit value. A computer receives pulses representing receipt of a timing bright timing pulse and the first and second data bit values, where receipt of the first and second data bit values is indexed by the bright timing pulse.

Ground truth data for test sites (SL-4). [thermal radiation brightness temperature and solar radiation measurments

NASA Technical Reports Server (NTRS)

1974-01-01

Field measurements performed simultaneous with Skylab overpass in order to provide comparative calibration and performance evaluation measurements for the EREP sensors are presented. Wavelength region covered include: solar radiation (400 to 1300 nanometer), and thermal radiation (8 to 14 micrometer). Measurements consisted of general conditions and near surface meteorology, atmospheric temperature and humidity vs altitude, the thermal brightness temperature, total and diffuse solar radiation, direct solar radiation (subsequently analyzed for optical depth/transmittance), and target reflectivity/radiance. The particular instruments used are discussed along with analyses performed. Detailed instrument operation, calibrations, techniques, and errors are given.

The 7.5- to 13.5-micron spectrum of Saturn

NASA Technical Reports Server (NTRS)

Gillett, F. C.; Forrest, W. J.

1974-01-01

A medium-resolution spectrum of Saturn in the 7.5-13.5 micron range is presented. The observed low brightness temperature between 9 and 11 microns of about 100-105 K rules out gaseous NH3 as the dominant absorber in this spectral range. Absorption features due to PH3 may be present around 10 microns and cloud particles could be an important source of opacity in this wavelength range. There are strong indications of a temperature inversion in the upper atmosphere, including high brightness temperature in the 7.7-micron CH4 band, and possible emission from C2H6 around 12 microns.

Imprint of non-linear effects on HI intensity mapping on large scales

DOE Office of Scientific and Technical Information (OSTI.GOV)

Umeh, Obinna, E-mail: umeobinna@gmail.com

Intensity mapping of the HI brightness temperature provides a unique way of tracing large-scale structures of the Universe up to the largest possible scales. This is achieved by using a low angular resolution radio telescopes to detect emission line from cosmic neutral Hydrogen in the post-reionization Universe. We use general relativistic perturbation theory techniques to derive for the first time the full expression for the HI brightness temperature up to third order in perturbation theory without making any plane-parallel approximation. We use this result and the renormalization prescription for biased tracers to study the impact of nonlinear effects on themore » power spectrum of HI brightness temperature both in real and redshift space. We show how mode coupling at nonlinear order due to nonlinear bias parameters and redshift space distortion terms modulate the power spectrum on large scales. The large scale modulation may be understood to be due to the effective bias parameter and effective shot noise.« less

Quantifying spatial and temporal variabilities of microwave brightness temperature over the U.S. Southern Great Plains

NASA Technical Reports Server (NTRS)

Choudhury, B. J.; Owe, M.; Ormsby, J. P.; Chang, A. T. C.; Wang, J. R.; Goward, S. N.; Golus, R. E.

1987-01-01

Spatial and temporal variabilities of microwave brightness temperature over the U.S. Southern Great Plains are quantified in terms of vegetation and soil wetness. The brightness temperatures (TB) are the daytime observations from April to October for five years (1979 to 1983) obtained by the Nimbus-7 Scanning Multichannel Microwave Radiometer at 6.6 GHz frequency, horizontal polarization. The spatial and temporal variabilities of vegetation are assessed using visible and near-infrared observations by the NOAA-7 Advanced Very High Resolution Radiometer (AVHRR), while an Antecedent Precipitation Index (API) model is used for soil wetness. The API model was able to account for more than 50 percent of the observed variability in TB, although linear correlations between TB and API were generally significant at the 1 percent level. The slope of the linear regression between TB and API is found to correlate linearly with an index for vegetation density derived from AVHRR data.

Possible stressors in a neonatal intensive care unit at a university hospital

PubMed Central

Jordão, Kamila Reis; Pinto, Lauriane de Assis Proença; Machado, Lucimer Rocha; Costa, Laetitia Braga Vasconcellos de Lima; Trajano, Eduardo Tavares Lima

2016-01-01

Objective To investigate possible stressors to which newborns are exposed in the neonatal intensive care unit. Methods The levels of continuous noise were checked by a decibel meter positioned near the ear of the newborn, brightness was observed by a light meter positioned in the incubator in front of the newborn's eyes, and temperature was checked through the incubator display. The evaluations were performed in three periods of the day, with ten measurements taken at one-minute intervals during each shift for the subsequent statistical analysis. Results All shifts showed noise above acceptable levels. Morning (p < 0.001), afternoon (p < 0.05) and night (p < 0.001) showed a significant increase compared to the control. The brightness significantly exceeded the normal range (p < 0.01) in the morning. We observed that only one of the incubators was within the normal temperature limits. Conclusion The noise, brightness and temperature intensities were not in accordance with regulatory standards and thus might be possible stressors to newborns. PMID:27626948

Imprint of non-linear effects on HI intensity mapping on large scales

NASA Astrophysics Data System (ADS)

Umeh, Obinna

2017-06-01

Intensity mapping of the HI brightness temperature provides a unique way of tracing large-scale structures of the Universe up to the largest possible scales. This is achieved by using a low angular resolution radio telescopes to detect emission line from cosmic neutral Hydrogen in the post-reionization Universe. We use general relativistic perturbation theory techniques to derive for the first time the full expression for the HI brightness temperature up to third order in perturbation theory without making any plane-parallel approximation. We use this result and the renormalization prescription for biased tracers to study the impact of nonlinear effects on the power spectrum of HI brightness temperature both in real and redshift space. We show how mode coupling at nonlinear order due to nonlinear bias parameters and redshift space distortion terms modulate the power spectrum on large scales. The large scale modulation may be understood to be due to the effective bias parameter and effective shot noise.

Application of Reflected Global Navigation Satellite System (GNSS-R) Signals in the Estimation of Sea Roughness Effects in Microwave Radiometry

NASA Technical Reports Server (NTRS)

Voo, Justin K.; Garrison, James L.; Yueh, Simon H.; Grant, Michael S.; Fore, Alexander G.; Haase, Jennifer S.; Clauss, Bryan

2010-01-01

In February-March 2009 NASA JPL conducted an airborne field campaign using the Passive Active L-band System (PALS) and the Ku-band Polarimetric Scatterometer (PolSCAT) collecting measurements of brightness temperature and near surface wind speeds. Flights were conducted over a region of expected high-speed winds in the Atlantic Ocean, for the purposes of algorithm development for salinity retrievals. Wind speeds encountered were in the range of 5 to 25 m/s during the two weeks deployment. The NASA-Langley GPS delay-mapping receiver (DMR) was also flown to collect GPS signals reflected from the ocean surface and generate post-correlation power vs. delay measurements. This data was used to estimate ocean surface roughness and a strong correlation with brightness temperature was found. Initial results suggest that reflected GPS signals, using small low-power instruments, will provide an additional source of data for correcting brightness temperature measurements for the purpose of sea surface salinity retrievals.

Detection of moisture and moisture related phenomena from Skylab. [correlation of brightness and antenna temperature with soil moisture for Texas and Kansas test sites

NASA Technical Reports Server (NTRS)

Eagleman, J. R.; Pogge, E. C.; Moore, R. K. (Principal Investigator); Hardy, N.; Lin, W.; League, L.

1974-01-01

The author has identified the following significant results. Skylab 2 data for June 5, 1973 (Texas site) relates favorably with previously calculated aircraft data when correlating brightness temperature to soil moisture. However, more detailed work is needed to determine the corrected surface temperature. In addition, correlations between the S194 antenna temperature and soil moisture have been obtained for five sets of Skylab data. The best correlations were obtained for the surface to one inch depth in four cases and for surface to two inches depth for the fifth case. Correlation coefficients for the surface to one inch depth were -0.98, -0.95, -0.90, -0.82, and -0.80.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Royer, Michael P.; Houser, Kevin W.

An experiment was conducted to examine the effect of tuning optical radiation on brightness perception for younger (18-25 years of age) and older (50 years of age or older) observers. Participants made forced-choice evaluations of the brightness of a full factorial of stimulus pairs selected from two groups of four metameric stimuli. The large-field stimuli were created by systematically varying either the red or the blue primary of an RGB LED mixture. The results indicate that light stimuli of equal illuminance and chromaticity do not appear equally bright to either younger or older subjects. The rank-order of brightness is notmore » predicted by any current model of human vision or theory of brightness perception including Scotopic to Photopic or Cirtopic to Photopic ratio theory, prime color theory, correlated color temperature, V(λ)-based photometry, color quality metrics, linear brightness models, or color appearance models. Age may affect brightness perception when short-wavelength primaries are used, especially those with a peak wavelength shorter than 450 nm. The results suggest further development of metrics to predict brightness perception is warranted, and that including age as a variable in predictive models may be valuable.« less

SMOS/SMAP Synergy for SMAP Level 2 Soil Moisture Algorithm Evaluation

NASA Technical Reports Server (NTRS)

Bindlish, Rajat; Jackson, Thomas J.; Zhao, Tianjie; Cosh, Michael; Chan, Steven; O'Neill, Peggy; Njoku, Eni; Colliander, Andreas; Kerr, Yann

2011-01-01

Soil Moisture Active Passive (SMAP) satellite has been proposed to provide global measurements of soil moisture and land freeze/thaw state at 10 km and 3 km resolutions, respectively. SMAP would also provide a radiometer-only soil moisture product at 40-km spatial resolution. This product and the supporting brightness temperature observations are common to both SMAP and European Space Agency's Soil Moisture and Ocean Salinity (SMOS) mission. As a result, there are opportunities for synergies between the two missions. These include exploiting the data for calibration and validation and establishing longer term L-band brightness temperature and derived soil moisture products. In this investigation we will be using SMOS brightness temperature, ancillary data, and soil moisture products to develop and evaluate a candidate SMAP L2 passive soil moisture retrieval algorithm. This work will begin with evaluations based on the SMOS product grids and ancillary data sets and transition to those that will be used by SMAP. An important step in this analysis is reprocessing the multiple incidence angle observations provided by SMOS to a global brightness temperature product that simulates the constant 40 degree incidence angle observations that SMAP will provide. The reprocessed brightness temperature data provide a basis for evaluating different SMAP algorithm alternatives. Several algorithms are being considered for the SMAP radiometer-only soil moisture retrieval. In this first phase, we utilized only the Single Channel Algorithm (SCA), which is based on the radiative transfer equation and uses the channel that is most sensitive to soil moisture (H-pol). Brightness temperature is corrected sequentially for the effects of temperature, vegetation, roughness (dynamic ancillary data sets) and soil texture (static ancillary data set). European Centre for Medium-Range Weather Forecasts (ECMWF) estimates of soil temperature for the top layer (as provided as part of the SMOS ancillary data) were used to correct for surface temperature effects and to derive microwave emissivity. ECMWF data were also used for precipitation forecasts, presence of snow, and frozen ground. Vegetation options are described below. One year of soil moisture observations from a set of four watersheds in the U.S. were used to evaluate four different retrieval methodologies: (1) SMOS soil moisture estimates (version 400), (2) SeA soil moisture estimates using the SMOS/SMAP data with SMOS estimated vegetation optical depth, which is part of the SMOS level 2 product, (3) SeA soil moisture estimates using the SMOS/SMAP data and the MODIS-based vegetation climatology data, and (4) SeA soil moisture estimates using the SMOS/SMAP data and actual MODIS observations. The use of SMOS real-world global microwave observations and the analyses described here will help in the development and selection of different land surface parameters and ancillary observations needed for the SMAP soil moisture algorithms. These investigations will greatly improve the quality and reliability of this SMAP product at launch.

Comet brightness parameters: Definition, determination, and correlations

NASA Technical Reports Server (NTRS)

Meisel, D. D.; Morris, C. S.

1976-01-01

The power-law definition of comet brightness is reviewed and possible systematic influences are discussed that can affect the derivation of m sub o and n values from visual magnitude estimates. A rationale for the Bobrovnikoff aperture correction method is given and it is demonstrated that the Beyer extrafocal method leads to large systematic effects which if uncorrected by an instrumental relationship result in values significantly higher than those derived according to the Bobrovnikoff guidelines. A series of visual brightness parameter sets are presented which have been reduced to the same photometric system. Recommendations are given to insure that future observations are reduced to the same system.

Approximating tasseled cap values to evaluate brightness, greenness, and wetness for the Advanced Land Imager (ALI)

USGS Publications Warehouse

Yamamoto, Kristina H.; Finn, Michael P.

2012-01-01

The Tasseled Cap transformation is a method of image band conversion to enhance spectral information. It primarily is used to detect vegetation using the derived brightness, greenness, and wetness bands. An approximation of Tasseled Cap values for the Advanced Land Imager was investigated and compared to the Landsat Thematic Mapper Tasseled Cap values. Despite sharing similar spectral, temporal, and spatial resolution, the two systems are not interchangeable with regard to Tasseled Cap matrices.

Evaluation and analysis of Seasat-A Scanning multichannel Microwave radiometer (SMMR) Antenna Pattern Correction (APC) algorithm. Sub-task 2: T sub B measured vs. T sub B calculated comparison results

NASA Technical Reports Server (NTRS)

Kitzis, J. L.; Kitzis, S. N.

1979-01-01

Interim Antenna Pattern Correction (APC) brightness temperature measurements for all ten SMMR channels are compared with calculated values generated from surface truth data. Plots and associated statistics are presented for the available points of coincidence between SMMR and surface truth measurements acquired for the Gulf of Alaska SEASAT Experiment. The most important conclusions of the study deal with the apparent existence of different instrument biases for each SMMR channel, and their variation across the scan.

Model Development for MODIS Thermal Band Electronic Crosstalk

NASA Technical Reports Server (NTRS)

Chang, Tiejun; Wu, Aisheng; Geng, Xu; Li, Yonghonh; Brinkman, Jake; Keller, Graziela; Xiong, Xiaoxiong

2016-01-01

MODerate-resolution Imaging Spectroradiometer (MODIS) has 36 bands. Among them, 16 thermal emissive bands covering a wavelength range from 3.8 to 14.4 m. After 16 years on-orbit operation, the electronic crosstalk of a few Terra MODIS thermal emissive bands developed substantial issues that cause biases in the EV brightness temperature measurements and surface feature contamination. The crosstalk effects on band 27 with center wavelength at 6.7 m and band 29 at 8.5 m increased significantly in recent years, affecting downstream products such as water vapor and cloud mask. The crosstalk effect is evident in the near-monthly scheduled lunar measurements, from which the crosstalk coefficients can be derived. The development of an alternative approach is very helpful for independent verification.In this work, a physical model was developed to assess the crosstalk impact on calibration as well as in Earth view brightness temperature retrieval. This model was applied to Terra MODIS band 29 empirically to correct the Earth brightness temperature measurements. In the model development, the detectors nonlinear response is considered. The impact of the electronic crosstalk is assessed in two steps. The first step consists of determining the impact on calibration using the on-board blackbody (BB). Due to the detectors nonlinear response and large background signal, both linear and nonlinear coefficients are affected by the crosstalk from sending bands. The second step is to calculate the effects on the Earth view brightness temperature retrieval. The effects include those from affected calibration coefficients and the contamination of Earth view measurements. This model links the measurement bias with crosstalk coefficients, detector non-linearity, and the ratio of Earth measurements between the sending and receiving bands. The correction of the electronic cross talk can be implemented empirically from the processed bias at different brightness temperature. The implementation can be done through two approaches. As routine calibration assessment for thermal infrared bands, the trending over select Earth scenes is processed for all the detectors in a band and the band averaged bias is derived at a certain time. In this case, the correction of an affected band can be made using the regression of the model with band averaged bias and then corrections of detector differences are applied. The second approach requires the trending for individual detectors and the bias for each detector is used for regression with the model. A test using the first approach was made for Terra MODIS band 29 with the biases derived from long-term trending of brightness temperature over ocean and Dome-C.

Preparation and Characterization of Chromium(III)-Activated Yttrium Aluminum Borate: A New Thermographic Phosphor for Optical Sensing and Imaging at Ambient Temperatures

PubMed Central

2010-01-01

A new thermographic phosphor based on chromium(III)-doped yttrium aluminum borate (YAB) is obtained as single crystals by high temperature flux growth and as a microcrystalline powder via solution combustion synthesis. The phosphor is excitable both in the blue (λmax 422 nm) and in the red part of the spectrum (λmax 600 nm) and shows bright NIR emission. The brightness of the phosphor is comparable to that of a well-known lamp phosphor Mn(IV)-doped magnesium fluorogermanate. At ambient temperatures, the Cr(III)-doped YAB shows high temperature dependence of the luminescence decay time, which approaches 1% per deg. The material shows no decrease in luminescence intensity at higher temperatures. The new phosphor is particularly promising for applications in temperature-compensated optical chemosensors (including those based on NIR-emitting indicators) and in pressure-sensitive paints. PMID:20473368

Image plane detector spectrophotometer - Application to O2 atmospheric band nightglow

NASA Technical Reports Server (NTRS)

Luo, Mingzhao; Yee, Jeng-Hwa; Hays, Paul B.

1988-01-01

A new variety of low resolution spectrometer is described. This device, an image plane detector spectrophotometer, has high sensitivity and modest resolution sufficient to determine the rotational temperature and brightness of molecular band emissions. It uses an interference filter as a dispersive element and a multichannel image plane detector as the photon collecting device. The data analysis technqiue used to recover the temperature of the emitter and the emission brightness is presented. The atmospheric band of molecular oxygen is used to illustrate the use of the device.

Radiation calibration for LWIR Hyperspectral Imager Spectrometer

NASA Astrophysics Data System (ADS)

Yang, Zhixiong; Yu, Chunchao; Zheng, Wei-jian; Lei, Zhenggang; Yan, Min; Yuan, Xiaochun; Zhang, Peizhong

2014-11-01

The radiometric calibration of LWIR Hyperspectral imager Spectrometer is presented. The lab has been developed to LWIR Interferometric Hyperspectral imager Spectrometer Prototype(CHIPED-I) to study Lab Radiation Calibration, Two-point linear calibration is carried out for the spectrometer by using blackbody respectively. Firstly, calibration measured relative intensity is converted to the absolute radiation lightness of the object. Then, radiation lightness of the object is is converted the brightness temperature spectrum by the method of brightness temperature. The result indicated †that this method of Radiation Calibration calibration was very good.

Skylab floating ice experiment

NASA Technical Reports Server (NTRS)

Campbell, W. J. (Principal Investigator); Ramseier, R. O.; Weaver, R. J.; Weeks, W. F.

1975-01-01

The author has identified the following significant results. Coupling of the aircraft data with the ground truth observations proved to be highly successful with interesting results being obtained with IR and SLAR passive microwave techniques, and standard photography. Of particular interest were the results of the PMIS system which operated at 10.69 GHz with both vertical and horizontal polarizations. This was the first time that dual polarized images were obtained from floating ice. In both sea and lake ice, it was possible to distinguish a wide variety of thin ice types because of their large differences in brightness temperatures. It was found that the higher brightness temperature was invariably obtained in the vertically polarized mode, and as the age of the ice increases the brightness temperature increases in both polarizations. Associated with this change in age, the difference in temperature was observed as the different polarizations decreased. It appears that the horizontally polarized data is the most sensitive to variations in ice type for both fresh water and sea ice. The study also showed the great amount of information on ice surface roughness and deformation patterns that can be obtained from X-band SLAR observations.

Investigations of dark, bright, combined dark-bright optical and other soliton solutions in the complex cubic nonlinear Schrödinger equation with δ-potential

NASA Astrophysics Data System (ADS)

Baskonus, Haci Mehmet; Sulaiman, Tukur Abdulkadir; Bulut, Hasan; Aktürk, Tolga

2018-03-01

In this study, using the extended sinh-Gordon equation expansion method, we construct the dark, bright, combined dark-bright optical, singular, combined singular solitons and singular periodic waves solutions to the complex cubic nonlinear Schrödinger equation with δ-potential. The conditions for the existence of the obtained solutions are given. To present the physical feature of the acquired result, the 2D and 3D graphs are plotted under the choice of suitable values of the parameters.

Can we settle with single-band radiometric temperature monitoring during hyperthermia treatment of chestwall recurrence of breast cancer using a dual-mode transceiving applicator?

PubMed

Jacobsen, Svein; Stauffer, Paul R

2007-02-21

The total thermal dose that can be delivered during hyperthermia treatments is frequently limited by temperature heterogeneities in the heated tissue volume. Reliable temperature information on the heated area is thus vital for the optimization of clinical dosimetry. Microwave radiometry has been proposed as an accurate, quick and painless temperature sensing technique for biological tissue. Advantages include the ability to sense volume-averaged temperatures from subsurface tissue non-invasively, rather than with a limited set of point measurements typical of implanted temperature probes. We present a procedure to estimate the maximum tissue temperature from a single radiometric brightness temperature which is based on a numerical simulation of 3D tissue temperature distributions induced by microwave heating at 915 MHz. The temperature retrieval scheme is evaluated against errors arising from unknown variations in thermal, electromagnetic and design model parameters. Whereas realistic deviations from base values of dielectric and thermal parameters have only marginal impact on performance, pronounced deviations in estimated maximum tissue temperature are observed for unanticipated variations of the temperature or thickness of the bolus compartment. The need to pay particular attention to these latter applicator construction parameters in future clinical implementation of the thermometric method is emphasized.

Can we settle with single-band radiometric temperature monitoring during hyperthermia treatment of chestwall recurrence of breast cancer using a dual-mode transceiving applicator?

NASA Astrophysics Data System (ADS)

Jacobsen, Svein; Stauffer, Paul R.

2007-02-01

The total thermal dose that can be delivered during hyperthermia treatments is frequently limited by temperature heterogeneities in the heated tissue volume. Reliable temperature information on the heated area is thus vital for the optimization of clinical dosimetry. Microwave radiometry has been proposed as an accurate, quick and painless temperature sensing technique for biological tissue. Advantages include the ability to sense volume-averaged temperatures from subsurface tissue non-invasively, rather than with a limited set of point measurements typical of implanted temperature probes. We present a procedure to estimate the maximum tissue temperature from a single radiometric brightness temperature which is based on a numerical simulation of 3D tissue temperature distributions induced by microwave heating at 915 MHz. The temperature retrieval scheme is evaluated against errors arising from unknown variations in thermal, electromagnetic and design model parameters. Whereas realistic deviations from base values of dielectric and thermal parameters have only marginal impact on performance, pronounced deviations in estimated maximum tissue temperature are observed for unanticipated variations of the temperature or thickness of the bolus compartment. The need to pay particular attention to these latter applicator construction parameters in future clinical implementation of the thermometric method is emphasized.

[Evaluation of eco-environmental quality based on artificial neural network and remote sensing techniques].

PubMed

Li, Hongyi; Shi, Zhou; Sha, Jinming; Cheng, Jieliang

2006-08-01

In the present study, vegetation, soil brightness, and moisture indices were extracted from Landsat ETM remote sensing image, heat indices were extracted from MODIS land surface temperature product, and climate index and other auxiliary geographical information were selected as the input of neural network. The remote sensing eco-environmental background value of standard interest region evaluated in situ was selected as the output of neural network, and the back propagation (BP) neural network prediction model containing three layers was designed. The network was trained, and the remote sensing eco-environmental background value of Fuzhou in China was predicted by using software MATLAB. The class mapping of remote sensing eco-environmental background values based on evaluation standard showed that the total classification accuracy was 87. 8%. The method with a scheme of prediction first and classification then could provide acceptable results in accord with the regional eco-environment types.

Measurement of the cosmic microwave background spectrum by the COBE FIRAS instrument

NASA Technical Reports Server (NTRS)

Mather, J. C.; Cheng, E. S.; Cottingham, D. A.; Eplee, R. E., Jr.; Fixsen, D. J.; Hewagama, T.; Isaacman, R. B.; Jensen, K. A.; Meyer, S. S.; Noerdlinger, P. D.

1994-01-01

The cosmic microwave background radiation (CMBR) has a blackbody spectrum within 3.4 x 10(exp -8) ergs/sq cm/s/sr cm over the frequency range from 2 to 20/cm (5-0.5 mm). These measurements, derived from the Far-Infrared Absolute Spectrophotomer (FIRAS) instrument on the Cosmic Background Explorer (COBE) satellite, imply stringent limits on energy release in the early universe after t approximately 1 year and redshift z approximately 3 x 10(exp 6). The deviations are less than 0.30% of the peak brightness, with an rms value of 0.01%, and the dimensionless cosmological distortion parameters are limited to the absolute value of y is less than 2.5 x 10(exp -5) and the absolute value of mu is less than 3.3 x 10(exp -4) (95% confidence level). The temperature of the CMBR is 2.726 +/- 0.010 K (95% confidence level systematic).

Exospheric temperatures deduced from 7320- to 7330-A /O/+//2P/ - O/+//2D// twilight observations

NASA Technical Reports Server (NTRS)

Yee, J. H.; Abreu, V. J.

1982-01-01

A technique developed to deduce exospheric temperatures from the 7320- to 7330-A emission measured by the visible airglow experiment on board the AE-E satellite is considered. An excess emission in the measured 7320- to 7330-A brightness is noticed as a result of the interaction between the spacecraft and the atmosphere. The observed brightnesses are corrected for this effect. The galactic background emission is also carefully subtracted. The deduced temperatures exhibit a positive correlation with solar activity. It varies from approximately 700 K in late 1976 to approximately 1700 K at the peak of this solar cycle. The presence of a nonthermal oxygen corona is considered inconclusive.

Forecasting Weather on Distant Worlds

NASA Technical Reports Server (NTRS)

2007-01-01

An artist's conception shows a gas-giant planet orbiting very close to its parent star, creating searingly hot conditions on the planet's surface. New research suggests that for three such planets lying from 50 to 150 light-years from Earth, strong winds thousands of miles per hour mix the atmosphere so that the temperature is relatively uniform from the permanently light side to the permanently dark side.

This illustration represents an infrared view of a planetary system, in which brightness indicates warmer temperatures. For example, the bright band around the equator of the planet denotes warmer temperatures on both the dark and sunlit sides. The planet's poles, shown in darker colors, would be cooler.

Radiative transfer in multilayered random medium with laminar structure - Green's function approach

NASA Technical Reports Server (NTRS)

Karam, M. A.; Fung, A. K.

1986-01-01

For a multilayered random medium with a laminar structure a Green's function approach is introduced to obtain the emitted intensity due to an arbitrary point source. It is then shown that the approach is applicable to both active and passive remote sensing. In active remote sensing, the computed radar backscattering cross section for the multilayered medium includes the effects of both volume multiple scattering and surface multiple scattering at the layer boundaries. In passive remote sensing, the brightness temperature is obtained for arbitrary temperature profiles in the layers. As an illustration the brightness temperature and reflectivity are calculated for a bounded layer and compared with results in the literature.

A Broadband Microwave Radiometer Technique at X-band for Rain and Drop Size Distribution Estimation

NASA Technical Reports Server (NTRS)

Meneghini, R.

2005-01-01

Radiometric brightess temperatures below about 12 GHz provide accurate estimates of path attenuation through precipitation and cloud water. Multiple brightness temperature measurements at X-band frequencies can be used to estimate rainfall rate and parameters of the drop size distribution once correction for cloud water attenuation is made. Employing a stratiform storm model, calculations of the brightness temperatures at 9.5, 10 and 12 GHz are used to simulate estimates of path-averaged median mass diameter, number concentration and rainfall rate. The results indicate that reasonably accurate estimates of rainfall rate and information on the drop size distribution can be derived over ocean under low to moderate wind speed conditions.

Simulating the impact of X-ray heating during the cosmic dawn

NASA Astrophysics Data System (ADS)

Ross, Hannah E.; Dixon, Keri L.; Iliev, Ilian T.; Mellema, Garrelt

2017-07-01

Upcoming observations of the 21-cm signal from the epoch of reionization will soon provide the first direct detection of this era. This signal is influenced by many astrophysical effects, including long-range X-ray heating of the intergalactic gas. During the preceding cosmic dawn era, the impact of this heating on the 21-cm signal is particularly prominent, especially before spin temperature saturation. We present the largest volume (349 Mpc comoving = 244 h-1Mpc) full numerical radiative transfer simulations to date of this epoch which include the effects of helium and multifrequency heating, both with and without X-ray sources. We show that X-ray sources contribute significantly to early heating of the neutral intergalactic medium and, hence, to the corresponding 21-cm signal. The inclusion of hard, energetic radiation yields an earlier, extended transition from absorption to emission compared to the stellar-only case. The presence of X-ray sources decreases the absolute value of the mean 21-cm differential brightness temperature. These hard sources also significantly increase the 21-cm fluctuations compared to the common assumption of temperature saturation. The 21-cm differential brightness temperature power spectrum is initially boosted on large scales, before decreasing on all scales. Compared to the case of the cold, unheated intergalactic medium, the signal has lower rms fluctuations and increased non-Gaussianity, as measured by the skewness and kurtosis of the 21-cm probability distribution functions. Images of the 21-cm signal with resolution around 11 arcmin still show fluctuations well above the expected noise for deep integrations with the SKA1-Low, indicating that direct imaging of the X-ray heating epoch could be feasible.

A Method for Obtaining High Frequency, Global, IR-Based Convective Cloud Tops for Studies of the TTL

NASA Technical Reports Server (NTRS)

Pfister, Leonhard; Ueyama, Rei; Jensen, Eric; Schoeberl, Mark

2017-01-01

Models of varying complexity that simulate water vapor and clouds in the Tropical Tropopause Layer (TTL) show that including convection directly is essential to properly simulating the water vapor and cloud distribution. In boreal winter, for example, simulations without convection yield a water vapor distribution that is too uniform with longitude, as well as minimal cloud distributions. Two things are important for convective simulations. First, it is important to get the convective cloud top potential temperature correctly, since unrealistically high values (reaching above the cold point tropopause too frequently) will cause excessive hydration of the stratosphere. Second, one must capture the time variation as well, since hydration by convection depends on the local relative humidity (temperature), which has substantial variation on synoptic time scales in the TTL. This paper describes a method for obtaining high frequency (3-hourly) global convective cloud top distributions which can be used in trajectory models. The method uses rainfall thresholds, standard IR brightness temperatures, meteorological temperature analyses, and physically realistic and documented corrections IR brightness temperature corrections to derive cloud top altitudes and potential temperatures. The cloud top altitudes compare well with combined CLOUDSAT and CALIPSO data, both in time-averaged overall vertical and horizontal distributions and in individual cases (correlations of .65-.7). An important finding is that there is significant uncertainty (nearly .5 km) in evaluating the statistical distribution of convective cloud tops even using lidar. Deep convection whose tops are in regions of high relative humidity (such as much of the TTL), will cause clouds to form above the actual convection. It is often difficult to distinguish these clouds from the actual convective cloud due to the uncertainties of evaluating ice water content from lidar measurements. Comparison with models show that calculated cloud top altitudes are generally higher than those calculated by global analyses (e.g., MERRA). Interannual variability in the distribution of convective cloud top altitudes is also investigated.

Surface temperatures and retention of H2O frost on Ganymede and Callisto

NASA Technical Reports Server (NTRS)

Squyres, S. W.

1980-01-01

Surface temperatures and ice evaporation rates are calculated for Ganymede and Callisto as functions of latitude, time of day, and albedo, according to a model that uses surface thermal properties determined by eclipse radiometry and albedos determined from photometrically decalibrated Voyager images. The difference in temperature between Ganymede and Callisto is not great enough to account for the lack of bright polar caps on Callisto, which seems instead to reflect a real deficiency in the amount of available water frost relative to Ganymede. The temperature difference between Ganymede's grooved and cratered terrains also cannot account for the high concentration of bright ray craters in the former, suggesting that an internal geologic process has enriched the grooved terrain in ice content relative to the cratered terrain.

Moon night sky brightness simulation for the Xinglong station

NASA Astrophysics Data System (ADS)

Yao, Song; Zhang, Hao-Tong; Yuan, Hai-Long; Zhao, Yong-Heng; Dong, Yi-Qiao; Bai, Zhong-Rui; Deng, Li-Cai; Lei, Ya-Juan

2013-10-01

Using a sky brightness monitor at the Xinglong station of National Astronomical Observatories, Chinese Academy of Sciences, we collected data from 22 dark clear nights and 90 moon nights. We first measured the sky brightness variation with time for dark nights and found a clear correlation between sky brightness and human activity. Then with a modified sky brightness model of moon nights and data from these nights, we derived the typical value for several important parameters in the model. With these results, we calculated the sky brightness distribution under a given moon condition for the Xinglong station. Furthermore, we simulated the sky brightness distribution of a moon night for a telescope with a 5° field of view (such as LAMOST). These simulations will be helpful for determining the limiting magnitude and exposure time, as well as planning the survey for LAMOST during moon nights.

Irradiation application for color removal and purification of green tea leaves extract

NASA Astrophysics Data System (ADS)

Jo, Cheorun; Son, Jun Ho; Lee, Hyun Ja; Byun, Myung Woo

2003-02-01

Gamma irradiation was introduced to develop a new processing method for brighter-colored green tea leaves extract without changes of physiological activities. Dried green tea leaves were purchased and extracted by 70% ethanol solution and irradiated at 0, 5, 10, and 20 kGy with gamma rays. Hunter color L-value increased and a- and b-value decreased by irradiation, resulting in bright yellow from dark brown. There was no difference in radical scavenging and tyrosinase inhibition effect by irradiation. The irradiation effect in the solution disappeared during storage for 3 weeks at room temperature but vitamin C addition was effective in reducing the color change. Results indicated that irradiation may be a good technology to remove undesirable color in green tea leaves extract.

Comparison Between AQUARIUS and SMOS brightness temperatures for Heterogeneous Land Areas

NASA Astrophysics Data System (ADS)

Benlloch, Amparo; Lopez-Baeza, Ernesto; Tenjo, Carolina; Navarro, Enrique

2016-07-01

Intercomparison between Aquarius and SMOS brightness temperatures (TBs) over land surfaces is more challenging than over oceans because land footprints are more heterogeneous. In this work we are comparing Aquarius and SMOS TBs under coherente conditions obtained both by considering similar areas, according to land uses and by stratifying by means of TVDI (Temperature Vegetation Dryness Index) that accounts for the dynamics of the vegetation instead of assuming static characteristics as in the previous approches. The area of study was chosen in central Spain where we could get a significant number of matches between both instruments. The study period corresponded to 2012-2014. SMOS level-3 data were obtained from the Centre Aval de Traitement des Données SMOS (CATDS) and Aquarius' from the Physical Oceanography Distributed Active Archive Center (PODAAC). Land uses were obtained from the Spanish SIOSE facility (Sistema de Informacion de Ocupacion del Suelo en España) that uses a scale of 1:25.000 and polygon geometrical structure layer. SIOSE is based on panchromatic and multispectral 2.5 m resolution SPOT-5 images together with Landsat-5 images and orthophotos from the Spanish Nacional Plan of Aerial Orthophotography (PNOA). TVDI values were obtained from MODIS operational products of land surface temperature and NDVI. SMOS ascending TBs were compared to inner-beam Aquarius descending half-orbit TBs coinciding over the study area at 06:00 h. The Aquarius inner beam has an incidence angle of 28,7º and SMOS data were considered for the 27,5º incidence angle. The SMOS products corresponded to version 2.6x (data before 31st Oct 2013) and version 2.7x (data after 1st Jan 2014). Intersections between both footprints were analysed under conditions of similar areas, land uses and TVDI values. For the latter (land uses/TVDI), a linear combination of SMOS land uses/TVDI was obtained to match the larger Aquarius footprint. A more physical approach is also under way including the Aquarius antenna pattern in the aggregation of the SMOS data.

Modelling CLPX IOP3 Radiometric Data by Means of the Dense Media Theory: Preliminary Results for the LSOS Test Site

NASA Technical Reports Server (NTRS)

Tedesco, Marco; Kim, Edward J.; Cline, Don; Graf, Tobias; Koike, Toshio; Armstrong, Richard; Brodzik, Mary Jo; Hardy, Janet

2003-01-01

The capabilities of the Dense Media Radiative Transfer model using the Quasi Crystalline Approximation with Coherent Potential (QCA-CP) to reproduce measured radiometric data were tested using the University of Tokyo Ground Based Microwave Radiometer (GBMR-7) during the third Intensive Observation Period (IOP3) of the NASA Cold-land Processes Field Experiment (CLPX). The data were collected at the Local-Scale Observation Site (LSOS), a 0.8-ha study site consisting of two open meadows separated by trees. Intensive measurements were also made of snow depth and temperature, density, and grain size profiles. A DMRT model is needed to describe radiative transfer in a medium such as snow because the assumption of independent scattering used in classical radiative transfer theory (CRT) is not valid. Validation of the DMRT approach requires a relationship between measured snow grain size and the DMRT approximation of snow grain radius as spherical particles with a mean radius of the log-normal particle-size distribution. This relationship is very important for a better understanding of snow modelling and for practical applications. DMRT simulations were compared with observations of microwave brightnesses at 18.7, 36.5 and 89-GHz (V and H polarizations) collected on February-1 9-25, 2003. Observation angles ranged from 30\\deg to 70\\deg. Model inputs included measured snow parameters except mean grain size. The average snow temperature, fractional volume and depth were held constant, together with the ice and soil permittivities. The minimum and maximum measured mean grain sizes were used to test the capabilities of the DMRT to reproduce the brightnesses as upper and lower limits. The sensitivity to the largest and smallest measured grain size in the three classes of minimum, medium and maximum observed grain sizes was also investigated. DMRT particle sizes yielding a best-fit to the experimental data for each date were computed. Results show that the measured brightnesses fall within the range of simulated brightnesses using the smallest and largest measured grain size values. The DMRT best-fit radii are comparable to the average radii for the medium observed grain sizes.

A Fast Infrared Radiative Transfer Model for Overlapping Clouds

NASA Technical Reports Server (NTRS)

Niu, Jianguo; Yang, Ping; Huang, Huang-Lung; Davies, James E.; Li, Jun; Baum, Bryan A.; Hu, Yong X.

2006-01-01

A fast infrared radiative transfer model (FIRTM2) appropriate for application to both single-layered and overlapping cloud situations is developed for simulating the outgoing infrared spectral radiance at the top of the atmosphere (TOA). In FIRTM2 a pre-computed library of cloud reflectance and transmittance values is employed to account for one or two cloud layers, whereas the background atmospheric optical thickness due to gaseous absorption can be computed from a clear-sky radiative transfer model. FIRTM2 is applicable to three atmospheric conditions: 1) clear-sky, 2) single-layered ice or water cloud, and 3) two simultaneous cloud layers in a column (e.g., ice cloud overlying water cloud). Moreover, FIRTM2 outputs the derivatives (i.e., Jacobians) of the TOA brightness temperature with respect to cloud optical thickness and effective particle size. Sensitivity analyses have been carried out to assess the performance of FIRTM2 for two spectral regions, namely the longwave (LW) band (587.3 - 1179.5/cm) and the short-to-medium wave (SMW) band (1180.1 - 2228.9/cm). The assessment is carried out in terms of brightness temperature differences (BTD) between FIRTM2 and the well-known discrete ordinates radiative transfer model (DISORT), henceforth referred to as BTD (F-D). The BTD (F-D) values for single-layered clouds are generally less than 0.8 K. For the case of two cloud layers (specifically ice cloud over water cloud), the BTD(F-D) values are also generally less than 0.8 K except for the SMW band for the case of a very high altitude (>15 km) cloud comprised of small ice particles. Note that for clear-sky atmospheres, FIRTM2 reduces to the clear-sky radiative transfer model that is incorporated into FIRTM2, and the errors in this case are essentially those of the clear-sky radiative transfer model.

Progress in extremely high brightness LED-based light sources

NASA Astrophysics Data System (ADS)

Hoelen, Christoph; Antonis, Piet; de Boer, Dick; Koole, Rolf; Kadijk, Simon; Li, Yun; Vanbroekhoven, Vincent; Van De Voorde, Patrick

2017-09-01

Although the maximum brightness of LEDs has been increasing continuously during the past decade, their luminance is still far from what is required for multiple applications that still rely on the high brightness of discharge lamps. In particular for high brightness applications with limited étendue, e.g. front projection, only very modest luminance values in the beam can be achieved with LEDs compared to systems based on discharge lamps or lasers. With dedicated architectures, phosphor-converted green LEDs for projection may achieve luminance values up to 200-300 Mnit. In this paper we report on the progress made in the development of light engines based on an elongated luminescent concentrator pumped by blue LEDs. This concept has recently been introduced to the market as ColorSpark High Lumen Density LED technology. These sources outperform the maximum brightness of LEDs by multiple factors. In LED front projection, green LEDs are the main limiting factor. With our green modules, we now have achieved peak luminance values of 2 Gnit, enabling LED-based projection systems with over 4000 ANSI lm. Extension of this concept to yellow and red light sources is presented. The light source efficiency has been increased considerably, reaching 45-60 lm/W for green under practical application conditions. The module architecture, beam shaping, and performance characteristics are reviewed, as well as system aspects. The performance increase, spectral range extensions, beam-shaping flexibility, and cost reductions realized with the new module architecture enable a breakthrough in LED-based projection systems and in a wide variety of other high brightness applications.

Analyzing Snowpack Metrics Over Large Spatial Extents Using Calibrated, Enhanced-Resolution Brightness Temperature Data and Long Short Term Memory Artificial Neural Networks

NASA Astrophysics Data System (ADS)

Norris, W.; J Q Farmer, C.

2017-12-01

Snow water equivalence (SWE) is a difficult metric to measure accurately over large spatial extents; snow-tell sites are too localized, and traditional remotely sensed brightness temperature data is at too coarse of a resolution to capture variation. The new Calibrated Enhanced-Resolution Brightness Temperature (CETB) data from the National Snow and Ice Data Center (NSIDC) offers remotely sensed brightness temperature data at an enhanced resolution of 3.125 km versus the original 25 km, which allows for large spatial extents to be analyzed with reduced uncertainty compared to the 25km product. While the 25km brightness temperature data has proved useful in past research — one group found decreasing trends in SWE outweighed increasing trends three to one in North America; other researchers used the data to incorporate winter conditions, like snow cover, into ecological zoning criterion — with the new 3.125 km data, it is possible to derive more accurate metrics for SWE, since we have far more spatial variability in measurements. Even with higher resolution data, using the 37 - 19 GHz frequencies to estimate SWE distorts the data during times of melt onset and accumulation onset. Past researchers employed statistical splines, while other successful attempts utilized non-parametric curve fitting to smooth out spikes distorting metrics. In this work, rather than using legacy curve fitting techniques, a Long Short Term Memory (LSTM) Artificial Neural Network (ANN) was trained to perform curve fitting on the data. LSTM ANN have shown great promise in modeling time series data, and with almost 40 years of data available — 14,235 days — there is plenty of training data for the ANN. LSTM's are ideal for this type of time series analysis because they allow important trends to persist for long periods of time, but ignore short term fluctuations; since LSTM's have poor mid- to short-term memory, they are ideal for smoothing out the large spikes generated in the melt and accumulation onset seasons, while still capturing the overall trends in the data.

Exploiting the synergy between SMAP and SMOS to improve brightness temperature simulations and soil moisture retrievals in arid regions

NASA Astrophysics Data System (ADS)

Ebrahimi, Mohsen; Alavipanah, Seyed Kazem; Hamzeh, Saeid; Amiraslani, Farshad; Neysani Samany, Najmeh; Wigneron, Jean-Pierre

2018-02-01

The objective of this study was to exploit the synergy between SMOS and SMAP based on vegetation optical depth (VOD) to improve brightness temperature (TB) simulations and land surface soil moisture (SM) retrievals in arid regions of the world. In the current operational algorithm of SMAP (level 2), vegetation water content (VWC) is considered as a proxy to compute VOD which is calculated by an empirical conversion function of NDVI. Avoiding the empirical estimation of VOD, the SMOS algorithm is used to retrieve simultaneously SM and VOD from TB observations. The present study attempted to improve SMAP TB simulations and SM retrievals by benefiting from the advantages of the SMOS (L-MEB) algorithm. This was achieved by using a synergy method based on replacing the default value of SMAP VOD with the retrieved value of VOD from the SMOS multi angular and bi-polarization observations of TB. The insitu SM measurements, used as reference SM in this study, were obtained from the International Soil Moisture Network (ISMN) over 180 stations located in arid regions of the world. Furthermore, four stations were randomly selected to analyze the temporal variations in VOD and SM. Results of the synergy method showed that the accuracy of the TB simulations and SM retrievals was respectively improved at 144 and 124 stations (out of a total of 180 stations) in terms of coefficient of determination (R2) and unbiased root mean squared error (UbRMSE). Analyzing the temporal variations in VOD showed that the SMOS VOD, conversely to the SMAP VOD, can better illustrate the presence of herbaceous plants and may be a better indicator of the seasonal changes in the vegetation density and biomass over the year.

Measuring protein dynamics in live cells: protocols and practical considerations for fluorescence fluctuation microscopy

PubMed Central

Youker, Robert T.; Teng, Haibing

2014-01-01

Abstract. Quantitative analysis of protein complex stoichiometries and mobilities are critical for elucidating the mechanisms that regulate cellular pathways. Fluorescence fluctuation spectroscopy (FFS) techniques can measure protein dynamics, such as diffusion coefficients and formation of complexes, with extraordinary precision and sensitivity. Complete calibration and characterization of the microscope instrument is necessary in order to avoid artifacts during data acquisition and to capitalize on the full capabilities of FFS techniques. We provide an overview of the theory behind FFS techniques, discuss calibration procedures, provide protocols, and give practical considerations for performing FFS experiments. One important parameter recovered from FFS measurements is the relative molecular brightness that can correlate with oligomerization. Three methods for measuring molecular brightness (fluorescence correlation spectroscopy, photon-counting histogram, and number and brightness analysis) recover similar values when measuring samples under ideal conditions in vitro. However, examples are given illustrating that these different methods used for calculating molecular brightness of fluorescent molecules in cells are not always equivalent. Methods relying on spot measurements are more prone to bleaching and movement artifacts that can lead to underestimation of brightness values. We advocate for the use of multiple FFS techniques to study molecular brightnesses to overcome and compliment limitations of individual techniques. PMID:25260867

Retrieval of Precipitation Profiles from Multiresolution, Multifrequency, Active and Passive Microwave Observations

NASA Technical Reports Server (NTRS)

Grecu, Mircea; Anagnostou, Emmanouil N.; Olson, William S.; Starr, David OC. (Technical Monitor)

2002-01-01

In this study, a technique for estimating vertical profiles of precipitation from multifrequency, multiresolution active and passive microwave observations is investigated using both simulated and airborne data. The technique is applicable to the Tropical Rainfall Measuring Mission (TRMM) satellite multi-frequency active and passive observations. These observations are characterized by various spatial and sampling resolutions. This makes the retrieval problem mathematically more difficult and ill-determined because the quality of information decreases with decreasing resolution. A model that, given reflectivity profiles and a small set of parameters (including the cloud water content, the intercept drop size distribution, and a variable describing the frozen hydrometeor properties), simulates high-resolution brightness temperatures is used. The high-resolution simulated brightness temperatures are convolved at the real sensor resolution. An optimal estimation procedure is used to minimize the differences between simulated and observed brightness temperatures. The retrieval technique is investigated using cloud model synthetic and airborne data from the Fourth Convection And Moisture Experiment. Simulated high-resolution brightness temperatures and reflectivities and airborne observation strong are convolved at the resolution of the TRMM instruments and retrievals are performed and analyzed relative to the reference data used in observations synthesis. An illustration of the possible use of the technique in satellite rainfall estimation is presented through an application to TRMM data. The study suggests improvements in combined active and passive retrievals even when the instruments resolutions are significantly different. Future work needs to better quantify the retrievals performance, especially in connection with satellite applications, and the uncertainty of the models used in retrieval.

Surface and Atmospheric Contributions to Passive Microwave Brightness Temperatures

NASA Technical Reports Server (NTRS)

Jackson, Gail Skofronick; Johnson, Benjamin T.

2010-01-01

Physically-based passive microwave precipitation retrieval algorithms require a set of relationships between satellite observed brightness temperatures (TB) and the physical state of the underlying atmosphere and surface. These relationships are typically non-linear, such that inversions are ill-posed especially over variable land surfaces. In order to better understand these relationships, this work presents a theoretical analysis using brightness temperature weighting functions to quantify the percentage of the TB resulting from absorption/emission/reflection from the surface, absorption/emission/scattering by liquid and frozen hydrometeors in the cloud, the emission from atmospheric water vapor, and other contributors. The results are presented for frequencies from 10 to 874 GHz and for several individual precipitation profiles as well as for three cloud resolving model simulations of falling snow. As expected, low frequency channels (<89 GHz) respond to liquid hydrometeors and the surface, while the higher frequency channels become increasingly sensitive to ice hydrometeors and the water vapor sounding channels react to water vapor in the atmosphere. Low emissivity surfaces (water and snow-covered land) permit energy downwelling from clouds to be reflected at the surface thereby increasing the percentage of the TB resulting from the hydrometeors. The slant path at a 53deg viewing angle increases the hydrometeor contributions relative to nadir viewing channels and show sensitivity to surface polarization effects. The TB percentage information presented in this paper answers questions about the relative contributions to the brightness temperatures and provides a key piece of information required to develop and improve precipitation retrievals over land surfaces.

The Chandra M10l Megasecond: Diffuse Emission

NASA Technical Reports Server (NTRS)

Kuntz, K. D.; Snowden, S. L.

2009-01-01

Because MIOl is nearly face-on, it provides an excellent laboratory in which to study the distribution of X-ray emitting gas in a typical late-type spiral galaxy. We obtained a Chandra observation with a cumulative exposure of roughly 1 Ms to study the diffuse X-ray emission in MlOl. The bulk of the X-ray emission is correlated with the star formation traced by the FUV emission. The global FUV/Xray correlation is non-linear (the X-ray surface brightness is roughly proportional to the square root of the FUV surface brightness) and the small-scale correlation is poor, probably due to the delay between the FUV emission and the X-ray production ill star-forming regions. The X-ray emission contains only minor contributions from unresolved stars (approximates less than 3%), unresolved X-ray point sources (approximates less than 4%), and individual supernova remnants (approximates 3%). The global spectrum of the diffuse emission can be reasonably well fitted with a three component thermal model, but the fitted temperatures are not unique; many distributions of emission measure can produce the same temperatures when observed with the current CCD energy resolution. The spectrum of the diffuse emission depends on the environment; regions with higher X-ray surface brightnesses have relatively stronger hard components, but there is no significant evidence that the temperatures of the emitting components increase with surface brightness.

A semiempirical model for interpreting microwave emission from semiarid land surfaces as seen from space

NASA Technical Reports Server (NTRS)

Kerr, Yann H.; Njoku, Eni G.

1990-01-01

A radiative-transfer model for simulating microwave brightness temperatures over land surfaces is described. The model takes into account sensor viewing conditions (spacecraft altitude, viewing angle, frequency, and polarization) and atmospheric parameters over a soil surface characterized by its moisture, roughness, and temperature and covered with a layer of vegetation characterized by its temperature, water content, single scattering albedo, structure, and percent coverage. In order to reduce the influence of atmospheric and surface temperature effects, the brightness temperatures are expressed as polarization ratios that depend primarily on the soil moisture and roughness, canopy water content, and percentage of cover. The sensitivity of the polarization ratio to these parameters is investigated. Simulation of the temporal evolution of the microwave signal over semiarid areas in the African Sahel is presented and compared to actual satellite data from the SMMR instrument on Nimbus-7.

The decay of coronal loops brightened by flares and transients

NASA Technical Reports Server (NTRS)

Krieger, A. S.

1978-01-01

Observations of X-ray emitting loops derived from Skylab S-054 photographs, and combined with temperature and brightness estimates from Solrad data, are used to determine brightness decay times resulting from various coronal energy loss mechanisms. Conductive losses are found to be more rapid than radiative losses. Attention is given to the role of geometrical inhibition of conduction as a possible mechanism of brightness decay. Soft X-ray observations are consistent with the continuation of the 'evaporation' driven by thermal conduction late into the decay phase of the event.

Harnessing AIA Diffraction Patterns to Determine Flare Footpoint Temperatures

NASA Astrophysics Data System (ADS)

Bain, H. M.; Schwartz, R. A.; Torre, G.; Krucker, S.; Raftery, C. L.

2014-12-01

In the "Standard Flare Model" energy from accelerated electrons is deposited at the footpoints of newly reconnected flare loops, heating the surrounding plasma. Understanding the relation between the multi-thermal nature of the footpoints and the energy flux from accelerated electrons is therefore fundamental to flare physics. Extreme ultraviolet (EUV) images of bright flare kernels, obtained from the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory, are often saturated despite the implementation of automatic exposure control. These kernels produce diffraction patterns often seen in AIA images during the most energetic flares. We implement an automated image reconstruction procedure, which utilizes diffraction pattern artifacts, to de-saturate AIA images and reconstruct the flare brightness in saturated pixels. Applying this technique to recover the footpoint brightness in each of the AIA EUV passbands, we investigate the footpoint temperature distribution. Using observations from the Ramaty High Energy Solar Spectroscopic Imager (RHESSI), we will characterize the footpoint accelerated electron distribution of the flare. By combining these techniques, we investigate the relation between the nonthermal electron energy flux and the temperature response of the flare footpoints.

Geological applications of Nimbus radiation data in Middle East

NASA Technical Reports Server (NTRS)

Allison, L. J.

1976-01-01

Plateaus of Eocene limestone and exposed limestone escarpments, in Egypt and Saudi Arabia respectively, were indicated by cool brightness temperatures T sub B (less than 240 to 265 K) by the Nimbus 5 electrically scanning microwave radiometer (ESMR) over a 2-year period. Nubian sandstone, desert eolian sand and igneous metamorphic rocks were differentiated from these limestone areas by warm T sub B values (more than 265 to 300 K). Cool T sub B values in the form of a V were found over broad areas of the Nile Valley and in the western desert of central Egypt. Similar cool T sub B values were shown over limestone-dolomitic hills of the interior Homocline and the Hadramawt plateau of Saudi Arabia. Nimbus 5 and 6 ESMR T sub B values selectively identified intermediate dense rock types (limestone versus sandstone/granite) in the Lake Nasser region whose thermal inertia ranged from 0.035 to 0.06 cal cm to minus 2 C sec 1/2 to minus one half.

The effects of large- and small-scale density structures on the radio from coronal streamers

NASA Astrophysics Data System (ADS)

Thejappa, G.; Kundu, M. R.

1994-01-01

The radio observations of the coronal streamers obtained using Clark Lake radioheliograph at 73.8, 50.0, and 38.5 MHz during a period of minimum activity in September 1986 are presented. Streamers appear to correlate with two prominent disk sources whose intensites fluctuated randomly. The variations in half-power diameter of the radio Sun are found to correspond with the variations in the white-light extents of the coronal streamers. It appears that the shape of the radio Sun is not a function of the phase of the solar cycle; instead it depends on the relative positions of the streamers in the corona. The observed peak brightness temperatures, TB, of the streamers are found to be very low, being approximately equal to 6 x 104 K. We compute the brightness temperature distribution along the equator by tracing the rays in the coronal plasma. The rays are deflected away by the streamers before reaching the critical density level, whereas they penetrate deeper into the coronal hole for small angles between the line of sight and the streamer axis. As a consequence, it is found that the streamers and coronal holes appear in the calculated equatorial brightness distribution as irregular brightness depressions and enhancements, respectively. The fine structures are found to disappear when the scattering due to small-scale density inhomogeneities is included in the ray-tracing calculations. The required relative level of density fluctuations, epsilon1 = (delta N)/N, is found to be greater than 12% to reduce the peak brightness temperature from 106 K to 6 x 104 K for all the three frequencies.

A brightness exceeding simulated Langmuir limit

NASA Astrophysics Data System (ADS)

Nakasuji, Mamoru

2013-08-01

When an excitation of the first lens determines a beam is parallel beam, a brightness that is 100 times higher than Langmuir limit is measured experimentally, where Langmuir limits are estimated using a simulated axial cathode current density which is simulated based on a measured emission current. The measured brightness is comparable to Langmuir limit, when the lens excitation is such that an image position is slightly shorter than a lens position. Previously measured values of brightness for cathode apical radii of curvature 20, 60, 120, 240, and 480 μm were 8.7, 5.3, 3.3, 2.4, and 3.9 times higher than their corresponding Langmuir limits, respectively, in this experiment, the lens excitation was such that the lens and the image positions were 180 mm and 400 mm, respectively. From these measured brightness for three different lens excitation conditions, it is concluded that the brightness depends on the first lens excitation. For the electron gun operated in a space charge limited condition, some of the electrons emitted from the cathode are returned to the cathode without having crossed a virtual cathode. Therefore, method that assumes a Langmuir limit defining method using a Maxwellian distribution of electron velocities may need to be revised. For the condition in which the values of the exceeding the Langmuir limit are measured, the simulated trajectories of electrons that are emitted from the cathode do not cross the optical axis at the crossover, thus the law of sines may not be valid for high brightness electron beam systems.

Structure and physical conditions in the Huygens region of the Orion nebula

NASA Astrophysics Data System (ADS)

O'Dell, C. R.; Ferland, G. J.; Peimbert, M.

2017-02-01

Hubble Space Telescope images, MUSE maps of emission lines, and an atlas of high velocity resolution emission-line spectra have been used to establish for the first time correlations of the electron temperature, electron density, radial velocity, turbulence, and orientation within the main ionization front of the nebula. From the study of the combined properties of multiple features, it is established that variations in the radial velocity are primarily caused by the photoevaporating ionization front being viewed at different angles. There is a progressive increase of the electron temperature and density with decreasing distance from the dominant ionizing star θ1 Ori C. The product of these characteristics (ne × Te) is the most relevant parameter in modelling a blister-type nebula like the Huygens region, where this quantity should vary with the surface brightness in Hα. Several lines of evidence indicate that small-scale structure and turbulence exist down to the level of our resolution of a few arcseconds. Although photoevaporative flow must contribute at some level to the well-known non-thermal broadening of the emission lines, comparison of quantitative predictions with the observed optical line widths indicates that it is not the major additive broadening component. Derivation of Te values for H+ from radio+optical and optical-only ionized hydrogen emission showed that this temperature is close to that derived from [N II] and that the transition from the well-known flat extinction curve which applies in the Huygens region to a more normal steep extinction curve occurs immediately outside of the Bright Bar feature of the nebula.

Detectors for the Atacama Cosmology Telescope

NASA Astrophysics Data System (ADS)

Marriage, Tobias Andrew

The Atacama Cosmology Telescope (ACT) will make measurements of the brightness temperature anisotropy in the Cosmic Microwave Background (CMB) on degree to arcminute angular scales. The ACT observing site is located 5200 m near the top of Cerro Toco in the Atacama Desert of northern Chile. This thesis presents research on the detectors which capture the image of the CMB formed at ACT's focal plane. In the first chapter, the primary brightness temperature fluctuations in the Cosmic Microwave Background are reviewed. In Chapter 2, a calculation shows how the CMB brightness is translated by ACT to an input power to the detectors. Chapter 3 describes the ACT detectors in detail and presents the response and sensitivity of the detectors to the input power computed in Chapter 2. Chapter 4 describes the detector fabrication at NASA Goddard Space Flight Center. Chapter 5 summarizes experiments which characterize the ACT detector performance.

Zones, spots, and planetary-scale waves beating in brown dwarf atmospheres.

PubMed

Apai, D; Karalidi, T; Marley, M S; Yang, H; Flateau, D; Metchev, S; Cowan, N B; Buenzli, E; Burgasser, A J; Radigan, J; Artigau, E; Lowrance, P

2017-08-18

Brown dwarfs are massive analogs of extrasolar giant planets and may host types of atmospheric circulation not seen in the solar system. We analyzed a long-term Spitzer Space Telescope infrared monitoring campaign of brown dwarfs to constrain cloud cover variations over a total of 192 rotations. The infrared brightness evolution is dominated by beat patterns caused by planetary-scale wave pairs and by a small number of bright spots. The beating waves have similar amplitudes but slightly different apparent periods because of differing velocities or directions. The power spectrum of intermediate-temperature brown dwarfs resembles that of Neptune, indicating the presence of zonal temperature and wind speed variations. Our findings explain three previously puzzling behaviors seen in brown dwarf brightness variations. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Continuous and line spectra of granules and intergranular lanes

NASA Astrophysics Data System (ADS)

Suemoto, Z.; Hiei, E.; Nakagomi, Y.

1990-05-01

Temperature and velocity structures above granules and intergranular lanes were studied on spectrograms covering Ca II H and K lines. In agreement with earlier results, it was confirmed more quantitatively that there appear two kinds of bright continua, one in the outer wings (granular continuum) and the other in the inner wings (temporarily called K0-continuum) of Ca II H and K lines, and that these two kinds of bright continua are located more or less in a complementary fashion. Further, it was found that the bright K0-continuum is well associated with higher central residual intensity of absorption lines. These facts suggest that, in the upper photosphere, there are high temperature regions in the intergranular lanes. Motions above granular regions are essentially upwards, whereas those of intergranular regions are predominantly downwards, and in the uppermost photosphere the motions become more random.

Low-temperature transonic cooling flows in galaxy clusters

NASA Technical Reports Server (NTRS)

Sulkanen, Martin E.; Burns, Jack O.; Norman, Michael L.

1989-01-01

Calculations are presented which demonstrate that cooling flow models with large sonic radii may be consistent with observed cluster gas properties. It is found that plausible cluster parameters and cooling flow mass accretion rates can produce sonic radii of 10-20 kpc for sonic point temperatures of 1-3 x 10 to the 6th K. The numerical calculations match these cooling flows to hydrostatic atmosphere solutions for the cluster gas beyond the cooling flow region. The cooling flows produce no appreciable 'holes' in the surface brightness toward the cluster center, and the model can be made to match the observed X-ray surface brightness of three clusters in which cooling flows had been believed to be absent. It is suggested that clusters with low velocity dispersion may be the natural location for such 'cool' cooling flows, and fits of these models to the X-ray surface brightness profiles for three clusters are presented.

NuSTAR spectral analysis of two bright Seyfert 1 galaxies: MCG +8-11-11 and NGC 6814

NASA Astrophysics Data System (ADS)

Tortosa, A.; Bianchi, S.; Marinucci, A.; Matt, G.; Middei, R.; Piconcelli, E.; Brenneman, L. W.; Cappi, M.; Dadina, M.; De Rosa, A.; Petrucci, P. O.; Ursini, F.; Walton, D. J.

2018-01-01

We report on the NuSTAR observations of two bright Seyfert 1 galaxies, namely MCG +8-11-11 (100 ks) and NGC 6814 (150 ks). The main goal of these observations was to investigate the Comptonization mechanisms acting in the innermost regions of an active galactic nucleus (AGN) which are believed to be responsible for the UV/X-ray emission. The spectroscopic analysis of the NuSTAR spectra of these two sources revealed that although they had different properties overall (black hole masses, luminosity and Eddington ratios), they had very similar coronal properties. Both presented a power-law spectrum with a high-energy cut-off at ∼150-200 keV, a relativistically broadened Fe K α line and the associated disc reflection component, plus a narrow iron line likely emitted in Compton thin and distant matter. The intrinsic continuum was well described by Comptonization models that show for MCG +8-11-11 a temperature of the coronal plasma of kTe ∼ 60 keV and an extrapolated optical depth τ = 1.8; for NGC 6814, the coronal temperature was kTe ∼ 45 keV with an extrapolated optical depth of τ = 2.5. We compare and discuss these values to some most common Comptonization models that aim at explaining the energy production and stability of coronae in AGNs.

Liquid water path retrieval using the lowest frequency channels of Fengyun-3C Microwave Radiation Imager (MWRI)

NASA Astrophysics Data System (ADS)

Tang, Fei; Zou, Xiaolei

2017-12-01

The Microwave Radiation Imager (MWRI) on board Chinese Fengyun-3 (FY-3) satellites provides measurements at 10.65, 18.7, 23.8, 36.5, and 89.0 GHz with both horizontal and vertical polarization channels. Brightness temperature measurements of those channels with their central frequencies higher than 19 GHz from satellite-based microwave imager radiometers had traditionally been used to retrieve cloud liquid water path (LWP) over ocean. The results show that the lowest frequency channels are the most appropriate for retrieving LWP when its values are large. Therefore, a modified LWP retrieval algorithm is developed for retrieving LWP of different magnitudes involving not only the high frequency channels but also the lowest frequency channels of FY-3 MWRI. The theoretical estimates of the LWP retrieval errors are between 0.11 and 0.06 mm for 10.65- and 18.7-GHz channels and between 0.02 and 0.04 mm for 36.5- and 89.0-GHz channels. It is also shown that the brightness temperature observations at 10.65 GHz can be utilized to better retrieve the LWP greater than 3 mm in the eyewall region of Super Typhoon Neoguri (2014). The spiral structure of clouds within and around Typhoon Neoguri can be well captured by combining the LWP retrievals from different frequency channels.

Study of the post-flare loops on 29 July 1973. II - Physical parameters in the X-ray loops

NASA Technical Reports Server (NTRS)

Petrasso, R. D.; Nolte, J. T.; Gerassimenko, M.; Krieger, A. S.; Krogstad, R.; Seguin, F. H.; Svestka, Z.

1979-01-01

We use the filter ratio method of analysis to determine spatially resolved values of plasma parameters in the X-ray emitting post-flare loop system which developed on 29 and 30 July 1973. We find that the loops were hotter and had higher plasma pressure at their tops than near their footpoints. The loop tops were at nearly the same temperature at different places 3 hr after the flare maximum and were also at nearly this same temperature 3 and 8 hr later. Variations in brightness transverse to the loops were due to variations in emission measure. We show by consideration of radiative losses alone that energy must have been added to the hottest part of the flare, at the tops of the loops, late in the decay phase of the flare.

Impedance spectroscopic and dielectric properties of nanosized Y2/3Cu3Ti4O12 ceramic

NASA Astrophysics Data System (ADS)

Sharma, Sunita; Yadav, Shiv Sundar; Singh, M. M.; Mandal, K. D.

2014-11-01

Yttrium Copper Titanate (Y2/3Cu3Ti4O12) nanoceramic is structurally analogous to CaCu3Ti4O12 (CCTO). X-ray diffraction (XRD) of Y2/3Cu3Ti4O12 (YCTO) shows the presence of all normal peaks of CCTO. SEM micrograph exhibits the presence of bimodal grains of size ranging from 1-2 μm. Bright field TEM image clearly displays nanocrystalline particle which is supported by presence of a few clear rings in the corresponding selected area electron diffraction (SAED) pattern. It exhibits a high value of dielectric constant (ɛ‧ = 8434) at room temperature and 100 Hz frequency with characteristic relaxation peaks. Impedance and modulus studies revealed the presence of temperature-dependent Maxwell-Wagner type of relaxation in the ceramic.

The brightness temperature of Venus and the absolute flux-density scale at 608 MHz.

NASA Technical Reports Server (NTRS)

Muhleman, D. O.; Berge, G. L.; Orton, G. S.

1973-01-01

The disk temperature of Venus was measured at 608 MHz near the inferior conjunction of 1972, and a value of 498 plus or minus 33 K was obtained using a nominal CKL flux-density scale. The result is consistent with earlier measurements, but has a much smaller uncertainty. Our theoretical model prediction is larger by a factor of 1.21 plus or minus 0.09. This discrepancy has been noticed previously for frequencies below 1400 MHz, but was generally disregarded because of the large observational uncertainties. No way could be found to change the model to produce agreement without causing a conflict with well-established properties of Venus. Thus it is suggested that the flux-density scale may require an upward revision, at least near this frequency, in excess of what has previously been considered likely.

Structure of the bulge of the galaxy NGC 4258

NASA Astrophysics Data System (ADS)

Matveyenko, L. I.; Demichev, V. A.

2017-09-01

The superfine structure of the bulge of the galaxy NGC 4258 has been investigated in H2O maser emission at the epochs on February 4, 2013, and November 29, 2013. The peak intensities of the spectral components reached F ≈ 5 Jy. The emission of the component at v = 476 km s-1 dominated at the beginning of this period; the second component at v = 487 km s-1 was observed at the end of the period. The structure is a chain of compact components up to 200 µas or 7mpc in extent. The velocity of the local standard of rest is v LSR = 482 km s-1. Two bright compact components with a separation between them Δ ρ ≈ 35 µas or 1.3 mpc and a pair of components spaced 13 µas apart, whose brightness reaches 30% of the peak value corresponding to a brightness temperature T b ≈ 1018 K, are located at the center. The sizes of the components are 2-3 µas. A splitting and a shift of the two pairs of components relative to each other by 8 µas or 0.3 mpc in the 45° direction are observed at the end of the period. The velocity gradient of the structure is dV/dρ = 224 km s-1 mas-1, suggesting a solid-body rotation with a period T ≈ 760 years. The compact components correspond to the tangential directions of the arm. Two parallel chains of components corresponding to the tangential directions of the walls of the bipolar outflow carrying away an excess angular momentum are ejected from the central part of the bulge, two sources. The outflow is oriented at an angle X ≈ 15° relative to the disk axis. The brightness of the outflow fragments does not exceed 1.5% of the peak value. The ejection of material from the central part in the northward direction at a level up to 0.2%, T b ≈ 1015 K, is observed at the epoch on February 4, 2013, at v = 478 km s-1. The core structure suggests a double system: parallel disks-vortices spaced 0.25 mpc apart.

Organic electroluminescent devices and method for improving energy efficiency and optical stability thereof

DOEpatents

Heller, Christian Maria

2004-04-27

An organic electroluminescent device ("OELD") has a controllable brightness, an improved energy efficiency, and stable optical output at low brightness. The OELD is activated with a series of voltage pulses, each of which has a maximum voltage value that corresponds to the maximum power efficiency when the OELD is activated. The frequency of the pulses, or the duty cycle, or both are chosen to provide the desired average brightness.

Passive microwave measurements of temperature and salinity in coastal zones

NASA Technical Reports Server (NTRS)

Blume, H.-J. C.; Kendall, B. M.

1982-01-01

Experimental methods and results from the maritime remote sensing (MARSEN) experiments using dual frequency microwave radiometer detecting systems on board aircraft are described. The radiometers were operated at 1.43 and 2.65 GHz and flown above U.S. Atlantic coastal areas, Chesapeake Bay, around Puerto Rico, and over the German Bight. The advanced switched radiometers used were configured to be independent of gain variations and errors originating from front-end losses and determined the absolute brightness temperatures to within a few tenths Kelvin. Corrections to the observed brightness temperature of the ocean are analytically defined, including accounts made for roughness, the cosmic background radiation, and the solar radio source. The coastal flight data for salinity gradients and surface temperatures were compared with sea truth measured from ships and found to be accurate to within 1 C and 1 pph.

A model for microwave emission from vegetation-covered fields

NASA Technical Reports Server (NTRS)

Mo, T.; Choudhury, B. J.; Schmugge, T. J.; Wang, J. R.; Jackson, T. J.

1982-01-01

The measured brightness temperatures over vegetation-covered fields are simulated by a radiative transfer model which treats the vegetation as a uniform canopy with a constant temperature, over a moist soil which emits polarized microwave radiation. The analytic formula for the microwave emission has four parameters: roughness height, polarization mixing factor, effective canopy optical thickness, and single scattering albedo. A good representation has been obtained with the model for both the horizontally and vertically polarized brightness temperatures at 1.4 and 5 GHz frequencies, over fields covered with grass, soybean and corn. A directly proportional relation is found between effective canopy optical thickness and the amount of water present in the vegetation canopy. The effective canopy single scattering albedo depends on vegetation type.

Infrared radiometry of Uranus and Neptune at 21 and 32 microns

NASA Technical Reports Server (NTRS)

Orton, Glenn S.; Baines, Kelvin H.; Bergstralh, Jay T.; Brown, Robert H.; Caldwell, John

1987-01-01

Mauna Kea's NASA IRTF has been used to obtain 21- and 32-cm radiometric measurements of Uranus and Neptune; brightness temperatures of 54.1 + or - 0.3 K for Uranus and 58.1 + or 0.3 K for Neptune were obtained by calibrating the 21-cm data against Alpha Boo. A calibration of the 32-cm data against Callisto and Ganymede yielded respective temperatures of 51.8 + or - 1.5 K and 55.6 + or - 1.2 K. The general decrease of brightness temperatures with wavelength from 20 to 30 microns is confirmed. The two planets are noted to appear as bodies sufficiently different to depart from the hypothesis of smooth planetary bulk property variation as a function of heliocentric distance.

Application of Fourier transforms for microwave radiometric inversions

NASA Technical Reports Server (NTRS)

Holmes, J. J.; Balanis, C. A.; Truman, W. M.

1975-01-01

Existing microwave radiometer technology now provides a suitable method for remote determination of the ocean surface's absolute brightness temperature. To extract the brightness temperature of the water from the antenna temperature, an unstable Fredholm integral equation of the first kind is solved. Fourier transform techniques are used to invert the integral after it is placed into a cross correlation form. Application and verification of the methods to a two-dimensional modeling of a laboratory wave tank system are included. The instability of the ill-posed Fredholm equation is examined and a restoration procedure is included which smooths the resulting oscillations. With the recent availability and advances of fast Fourier transform (FFT) techniques, the method presented becomes very attractive in the evaluation of large quantities of data.

The Barnes-Evans color-surface brightness relation: A preliminary theoretical interpretation

NASA Technical Reports Server (NTRS)

Shipman, H. L.

1980-01-01

Model atmosphere calculations are used to assess whether an empirically derived relation between V-R and surface brightness is independent of a variety of stellar paramters, including surface gravity. This relationship is used in a variety of applications, including the determination of the distances of Cepheid variables using a method based on the Beade-Wesselink method. It is concluded that the use of a main sequence relation between V-R color and surface brightness in determining radii of giant stars is subject to systematic errors that are smaller than 10% in the determination of a radius or distance for temperature cooler than 12,000 K. The error in white dwarf radii determined from a main sequence color surface brightness relation is roughly 10%.

Effects of electromagnetic radiation (bright light, extremely low-frequency magnetic fields, infrared radiation) on the circadian rhythm of melatonin synthesis, rectal temperature, and heart rate.

PubMed

Griefahn, Barbara; Künemund, Christa; Blaszkewicz, Meinolf; Lerchl, Alexander; Degen, Gisela H

2002-10-01

Electromagnetic spectra reduce melatonin production and delay the nadirs of rectal temperature and heart rate. Seven healthy men (16-22 yrs) completed 4 permuted sessions. The control session consisted of a 24-hours bedrest at < 30 lux, 18 degrees C, and < 50 dBA. In the experimental sessions, either light (1500 lux), magnetic field (16.7 Hz, 0.2 mT), or infrared radiation (65 degrees C) was applied from 5 pm to 1 am. Salivary melatonin level was determined hourly, rectal temperature and heart rate were continuously recorded. Melatonin synthesis was completely suppressed by light but resumed thereafter. The nadirs of rectal temperature and heart rate were delayed. The magnetic field had no effect. Infrared radiation elevated rectal temperature and heart rate. Only bright light affected the circadian rhythms of melatonin synthesis, rectal temperature, and heart rate, however, differently thus causing a dissociation, which might enhance the adverse effects of shiftwork in the long run.

Stellar populations of bulges in galaxies with a low surface-brightness disc

NASA Astrophysics Data System (ADS)

Morelli, L.; Corsini, E. M.; Pizzella, A.; Dalla Bontà, E.; Coccato, L.; Méndez-Abreu, J.

2015-03-01

The radial profiles of the Hβ, Mg, and Fe line-strength indices are presented for a sample of eight spiral galaxies with a low surface-brightness stellar disc and a bulge. The correlations between the central values of the line-strength indices and velocity dispersion are consistent to those known for early-type galaxies and bulges of high surface-brightness galaxies. The age, metallicity, and α/Fe enhancement of the stellar populations in the bulge-dominated region are obtained using stellar population models with variable element abundance ratios. Almost all the sample bulges are characterized by a young stellar population, on-going star formation, and a solar α/Fe enhancement. Their metallicity spans from high to sub-solar values. No significant gradient in age and α/Fe enhancement is measured, whereas only in a few cases a negative metallicity gradient is found. These properties suggest that a pure dissipative collapse is not able to explain formation of all the sample bulges and that other phenomena, like mergers or acquisition events, need to be invoked. Such a picture is also supported by the lack of a correlation between the central value and gradient of the metallicity in bulges with very low metallicity. The stellar populations of the bulges hosted by low surface-brightness discs share many properties with those of high surface-brightness galaxies. Therefore, they are likely to have common formation scenarios and evolution histories. A strong interplay between bulges and discs is ruled out by the fact that in spite of being hosted by discs with extremely different properties, the bulges of low and high surface-brightness discs are remarkably similar.

Global land-surface primary productivity based upon Nimbus-7 37 GHz data

NASA Technical Reports Server (NTRS)

Choudhury, B. J.

1988-01-01

Accumulation and renewal of organic matter as quantified through net primary productivity (NPP) is considered a very major function of the biosphere, and its estimation is crucial in understanding the carbon cycle. A physically-based model relating NPP to the difference of vertically and horizontally polarized brightness temperatures (Delta T) observed at 37 GHz frequency of the scanning multichannel microwave radiometer on board the Nimbus-7 satellite is used for fitting areally averaged values of NPP and Delta T for five biomes. The land-surface NPP within 80 deg N to 55 deg S is then calculated using the Delta T data and compared with other estimates.

Theoretical colours and isochrones for some Hubble Space Telescope colour systems

NASA Technical Reports Server (NTRS)

Edvardsson, B.; Bell, R. A.

1989-01-01

Synthetic spectra for effective temperatures of 4000-7250 K, logarithmic surface gravities typical of dwarfs and subgiants, and metallicities from solar values to 0.001 of the solar metallicity were used to derive a grid of synthetic surface brightness magnitudes for 21 of the Hubble Space Telescope Wide Field Camera (WFC) band passes. The absolute magnitudes of these 21 band passes are also obtained for a set of globular cluster isochrones with different helium abundances, metallicities, oxygen abundances, and ages. The usefulness and efficiency of different sets of broad and intermediate bandwidth WFC colors for determining ages and metallicities for globular clusters are evaluated.

Effectiveness of recycling light in ultra-bright short-arc discharge lamps.

PubMed

Malul, Asher; Nakar, Doron; Feuermann, Daniel; Gordon, Jeffrey M

2007-10-17

Recycling light back into a plasma lamp's radiant zone can enhance its radiance. Measurements are reported for the effectiveness, spectral properties and modified plasma radiance maps that result from light recycling with a specular hemispherical mirror in commercial 150 W ultrabright Xenon short-arc discharge lamps, motivated by projection, biomedical and high-temperature furnace applications. For certain spectral windows and plasma arc regions, radiance can be heightened by up to 70%. However, the overall light recycling efficiency is reduced to about half this value due to lamp geometry. The manner in which light-plasma interactions affect light recycling efficacy is also elucidated.

The Potential of Multicolor Photometry for Pulsating Subdwarf B Stars

NASA Astrophysics Data System (ADS)

Randall, S. K.; Fontaine, G.; Brassard, P.; Bergeron, P.

2005-12-01

We investigate the potential of multicolor photometry for partial mode identification in both long- and short-period variable subdwarf B stars. The technique presented is based on the fact that the frequency dependence of an oscillation's amplitude and phase bears the signature of the mode's degree index l, among other things. Unknown contributing factors can be eliminated through the evaluation of the amplitude ratios and phase differences arising from the brightness variation in different wavebands, theoretically enabling the inference of the degree index from observations in two or more bandpasses. Employing a designated model atmosphere code, we calculate the brightness variation expected across the visible disk during a pulsation cycle in terms of temperature, radius, and surface gravity perturbations to the emergent flux for representative EC 14026 and PG 1716 star models. Nonadiabatic effects are considered in detail and found to be significant from nonadiabatic pulsation calculations applied to our state-of-the-art models of subdwarf B stars. Our results indicate that the brightness variations observed in subdwarf B stars are caused primarily by changes in temperature and radius, with surface gravity perturbations playing a small role. For PG 1716 stars, temperature effects dominate in the limit of long periods with the result that the oscillatory amplitudes and phases lose their period dependence and nonadiabatic effects become unimportant. Outside this regime, however, their values are strongly influenced by both factors. We find that the phase shifts between brightness variations in different wavebands are generally small but may lie above the experimental detection threshold in certain cases. The prospect of mode discrimination seems much more promising on the basis of the corresponding amplitude ratios. While in EC 14026 stars the amplitude ratios predicted are very similar for modes with l=0, 1, or 2, they are well separated from those of modes with l=3, l=5, and l=4 or 6, each of which form a distinct group. For the case of the PG 1716 stars it should be possible to discriminate between modes with l=1, 2, 4, or 6 and those of degree indices l=3 and l=5. Identifying modes within a given group is challenging for both types of pulsator and requires multicolor photometry of extremely high quality. Nevertheless, we demonstrate that it is feasible using the example of the largest amplitude peak detected for the fast pulsator KPD 2109+4401 by Jeffery et al. Predicted color-amplitude ratios for a series of representative EC 14026 and PG 1716 stars are available upon request. Interested collaborators please contact S. K. Randall or G. Fontaine.

The First ALMA Observation of a Solar Plasmoid Ejection from an X-Ray Bright Point

NASA Astrophysics Data System (ADS)

Shimojo, M.; Hudson, H. S.; White, S. M.; Bastian, T.; Iwai, K.

2017-12-01

Eruptive phenomena are important features of energy releases events, such solar flares, and have the potential to improve our understanding of the dynamics of the solar atmosphere. The 304 A EUV line of helium, formed at around 10^5 K, is found to be a reliable tracer of such phenomena, but the determination of physical parameters from such observations is not straightforward. We have observed a plasmoid ejection from an X-ray bright point simultaneously with ALMA, SDO/AIA, and Hinode/XRT. This paper reports the physical parameters of the plasmoid obtained by combining the radio, EUV, and X-ray data. As a result, we conclude that the plasmoid can consist either of (approximately) isothermal ˜10^5 K plasma that is optically thin at 100 GHz, or a ˜10^4 K core with a hot envelope. The analysis demonstrates the value of the additional temperature and density constraints that ALMA provides, and future science observations with ALMA will be able to match the spatial resolution of space-borne and other high-resolution telescopes.

IMPACT OF SUPERNOVA AND COSMIC-RAY DRIVING ON THE SURFACE BRIGHTNESS OF THE GALACTIC HALO IN SOFT X-RAYS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peters, Thomas; Girichidis, Philipp; Gatto, Andrea

2015-11-10

The halo of the Milky Way contains a hot plasma with a surface brightness in soft X-rays of the order 10{sup −12} erg cm{sup −2} s{sup −1} deg{sup −2}. The origin of this gas is unclear, but so far numerical models of galactic star formation have failed to reproduce such a large surface brightness by several orders of magnitude. In this paper, we analyze simulations of the turbulent, magnetized, multi-phase interstellar medium including thermal feedback by supernova explosions as well as cosmic-ray feedback. We include a time-dependent chemical network, self-shielding by gas and dust, and self-gravity. Pure thermal feedback alonemore » is sufficient to produce the observed surface brightness, although it is very sensitive to the supernova rate. Cosmic rays suppress this sensitivity and reduce the surface brightness because they drive cooler outflows. Self-gravity has by far the largest effect because it accumulates the diffuse gas in the disk in dense clumps and filaments, so that supernovae exploding in voids can eject a large amount of hot gas into the halo. This can boost the surface brightness by several orders of magnitude. Although our simulations do not reach a steady state, all simulations produce surface brightness values of the same order of magnitude as the observations, with the exact value depending sensitively on the simulation parameters. We conclude that star formation feedback alone is sufficient to explain the origin of the hot halo gas, but measurements of the surface brightness alone do not provide useful diagnostics for the study of galactic star formation.« less

Geometrical evidence for dark matter: X-ray constraints on the mass of the elliptical galaxy NGC 720

NASA Astrophysics Data System (ADS)

Buote, David A.; Canizares, Claude R.

1994-05-01

We describe (1) a new test for dark matter and alternate theories of gravitation based on the relative geometries of the X-ray and optical surface brightness distributions and an assumed form for the potential, of the optical light, (2) a technique to measure the shapes of the total gravitating matter and dark matter of an ellipsoidal system which is insensitive to the precise value of the temperature of the gas and to modest temperature gradients, and (3) a new method to determine the ratio of dark mass to stellar mass that is dependent on the functional forms for the visible star, gas and dark matter distributions, but independent of the distance to the galaxy or the gas temperature. We apply these techniques to X-ray data from the ROSAT Position Sensitive Proportional Counter (PSPC) of the optically flattened elliptical galaxy NGC 720; the optical isophotes have ellipticity epsilon approximately 0.40 extending out to approximately 120 sec. The X-ray isophotes are significantly elongated, epsilon = 0.20-0.30 for semimajor axis a approximately 100 sec. The major axes of the optical and X-ray isophotes are misaligned by approximately 30 deg +/- 15 deg. Spectral analysis of the X-ray data reveals no evidence of temperature gradients or anisotropies and demonstrates that a single-temperature plasma (T approximately 0.6 keV) having subsolar heavy element abundances and a two-temperature model having solar abundances describe the spectrum equally well. Considering only the relative geometries of the X-ray and optical surface brightness distributions and an assumed functional form for the potential of the optical light, we conclude that matter distributed like the optical light cannot produce the observed ellipticities of the X-ray isophotes, independent of the gas pressure, the gas temperature, and the value of the stellar mass; this comparison assumes a state of quasi-hydrostatic equilibrium so that the three-dimensional surfaces of the gas emissivity trace the three-dimensional isopotential surfaces -- we discuss the viability of this assumption for NGC 720. Milgrom's Modification of Newtonian Dynamics (MOND) cannot dispel this manifestation of dark matter. Hence, geometrical considerations require, without mention of pressure or temperature, the presence of an extended, massive dark matter halo in NGC 720. Employing essentially the technique of Buote & Canizares (1992; Buote 1992) we use the shape of the X-ray surface brightness to constrain the shape of the total gravitating matter. The total matter is modeled as either an oblate or prolate spheriod of constant shape and orientation having either a Ferrers (rho approximately r-n) or Hernquist density. Assuming the X-ray gas is in hydrostatic equilibrium, we construct a model X-ray gas distribution for various temperature profiles. We determine the ellipticity of the total gravitating matter to be epsilon approximately 0.50-0.70. Using the single-temperature model we estimate a total mass approximately (0.41-1.4) x 1012 h80 solar mass interior to the ellipsoid of semimajor axis 43.6 h80 kpc. Ferrers densities as steep as r-3 do not fit the data, but the r-2 and Hernquist models yield excellent fits. We estimate the mass distributions of the stars and the gas and fit the dark matter directly. For a given gas equation of state and functional forms for the visible stars, gas, and dark matter, these models yield a distance-independent and temperature-independent measurement of the ratio of dark mass to stellar mass MDM/Mstars. We estimate a minimum MDM/Mstars greater than or equal to 4 which corresponds to a total mass slightly greater than that derived from the single-temperature models for distance D = 20h80 Mpc.

Geometrical evidence for dark matter: X-ray constraints on the mass of the elliptical galaxy NGC 720

NASA Technical Reports Server (NTRS)

Buote, David A.; Canizares, Claude R.

1994-01-01

We describe (1) a new test for dark matter and alternate theories of gravitation based on the relative geometries of the X-ray and optical surface brightness distributions and an assumed form for the potential, of the optical light, (2) a technique to measure the shapes of the total gravitating matter and dark matter of an ellipsoidal system which is insensitive to the precise value of the temperature of the gas and to modest temperature gradients, and (3) a new method to determine the ratio of dark mass to stellar mass that is dependent on the functional forms for the visible star, gas and dark matter distributions, but independent of the distance to the galaxy or the gas temperature. We apply these techniques to X-ray data from the ROSAT Position Sensitive Proportional Counter (PSPC) of the optically flattened elliptical galaxy NGC 720; the optical isophotes have ellipticity epsilon approximately 0.40 extending out to approximately 120 sec. The X-ray isophotes are significantly elongated, epsilon = 0.20-0.30 for semimajor axis a approximately 100 sec. The major axes of the optical and X-ray isophotes are misaligned by approximately 30 deg +/- 15 deg. Spectral analysis of the X-ray data reveals no evidence of temperature gradients or anisotropies and demonstrates that a single-temperature plasma (T approximately 0.6 keV) having subsolar heavy element abundances and a two-temperature model having solar abundances describe the spectrum equally well. Considering only the relative geometries of the X-ray and optical surface brightness distributions and an assumed functional form for the potential of the optical light, we conclude that matter distributed like the optical light cannot produce the observed ellipticities of the X-ray isophotes, independent of the gas pressure, the gas temperature, and the value of the stellar mass; this comparison assumes a state of quasi-hydrostatic equilibrium so that the three-dimensional surfaces of the gas emissivity trace the three-dimensional isopotential surfaces -- we discuss the viability of this assumption for NGC 720. Milgrom's Modification of Newtonian Dynamics (MOND) cannot dispel this manifestation of dark matter. Hence, geometrical considerations require, without mention of pressure or temperature, the presence of an extended, massive dark matter halo in NGC 720. Employing essentially the technique of Buote & Canizares (1992; Buote 1992) we use the shape of the X-ray surface brightness to constrain the shape of the total gravitating matter. The total matter is modeled as either an oblate or prolate spheriod of constant shape and orientation having either a Ferrers (rho approximately r(exp -n)) or Hernquist density. Assuming the X-ray gas is in hydrostatic equilibrium, we construct a model X-ray gas distribution for various temperature profiles. We determine the ellipticity of the total gravitating matter to be epsilon approximately 0.50-0.70. Using the single-temperature model we estimate a total mass approximately (0.41-1.4) x 10(exp 12) h(sub 80) solar mass interior to the ellipsoid of semimajor axis 43.6 h(sub 80) kpc. Ferrers densities as steep as r(exp -3) do not fit the data, but the r(exp -2) and Hernquist models yield excellent fits. We estimate the mass distributions of the stars and the gas and fit the dark matter directly. For a given gas equation of state and functional forms for the visible stars, gas, and dark matter, these models yield a distance-independent and temperature-independent measurement of the ratio of dark mass to stellar mass M(sub DM)/M(sub stars). We estimate a minimum M(sub DM)/M(sub stars) greater than or equal to 4 which corresponds to a total mass slightly greater than that derived from the single-temperature models for distance D = 20h(sub 80) Mpc.

Temperature profile determination in an absorbing plasma.

NASA Technical Reports Server (NTRS)

Usher, J. L.; Campbell, H. D.

1972-01-01

A new method has been developed to determine the temperature profile of an optically-non-thin plasma. The technique is essentially an extension of the brightness-emissivity method to the case of a cylindrically-symmetric plasma.

Meteorology and the physical activity of the elderly: the Nakanojo Study

NASA Astrophysics Data System (ADS)

Togo, Fumiharu; Watanabe, Eiji; Park, Hyuntae; Shephard, Roy J.; Aoyagi, Yukitoshi

2005-11-01

Seasonal changes in ambient temperature and day length are thought to modify habitual physical activity. However, relationships between such environmental factors and the daily physical activity of older populations remain unclear. The present study thus examined associations between meteorological variables and the number of steps taken per day by elderly Japanese. Continuous pedometer counts over a 450-day period were collected from 41 healthy subjects (age 71±4 years), none of whom engaged in any specific occupational activity or exercise programs. An electronic physical activity monitor was attached to a belt worn on the left side of the body throughout the day. Daily values for mean ambient temperature, duration of bright sunshine, mean wind speed, mean relative humidity, and precipitation were obtained from local meteorological stations. The day length was calculated from times of sunrise and sunset. Based on the entire group of 41 subjects (ensemble average), a subject’s step count per day decreased exponentially with increasing precipitation (r2=0.19, P<0.05). On days when precipitation was <1 mm, the step count increased with the mean ambient temperature over the range of 2 to 17°C, but decreased over the range 17 29°C. The daily step count also tended to increase with day length, but the regression coefficient of determination attributable to step count and mean ambient temperature (r2=0.32, P<0.05) exceeded that linking the step count and day length (r2=0.13, P<0.05). The influence of other meteorological factors was small (r2≤0.03) and of little practical significance. On days when precipitation is <1 mm, physical activity is associated more strongly with ambient temperature than with day length, duration of bright sunshine, wind speed, or relative humidity. Our findings have practical implications for health promotion efforts designed to increase the physical activity of elderly people consistently in the face of seasonal variations in environmental conditions.

Adjusting the tasseled cap brightness and greenness factors for atmospheric path radiance and absorption on a pixel by pixel basis

NASA Technical Reports Server (NTRS)

Jackson, R. D.; Slater, P. N.; Pinter, P. J. (Principal Investigator)

1982-01-01

A radiative transfer model was used to convert ground measured reflectances into the radiance at the top of the atmosphere, for several levels of atmospheric path radiance. The radiance in MSS7 (0.8 to 1.1 m) was multiplied by the transmission fraction for atmospheres having different levels of precipitable water. The radiance values were converted to simulated LANDSAT digital counts for four path radiance levels and four levels of precipitable water. These values were used to calculate the Kauth-Thomas brightness, greenness, yellowness, and nonsuch factors. Brightness was affected by surface conditions and path radiance. Greenness was affected by surface conditions, path radiance, and precipitable water. Yellowness was affected by path radiance and nonsuch by precipitable water, and both factors changed only slightly with surface conditions. Yellowness and nonsuch were used to adjust brightness and greenness to produce factors that were affected only by surface conditions such as soils and vegetation, and not by path radiance and precipitable water.

Microwave remote sensing of soil moisture content over bare and vegetated fields

NASA Technical Reports Server (NTRS)

Wang, J. R.; Shiue, J. C.; Mcmurtrey, J. E., III (Principal Investigator)

1980-01-01

The author has identified the following significant results. Ground truth of soil moisture content, and ambient air and soil temperatures were acquired concurrently with measurements of soil moisture in bare fields and fields covered with grass, corn, and soybeans obtained with 1.4 GHz and 5 GHz radiometers mounted on a truck. The biomass of the vegetation was sampled about once a week. The measured brightness temperatures over the bare fields were compared with those of radiative transfer model calculations using as inputs the acquired soil moisture and temperatures data with appropriate values of dielectric constants for soil-water mixtures. A good agreement was found between the calculated and measured results over 10 deg to 70 deg incident angles. The presence of vegetation reduced the sensitivity of soil moisture sensing. At 1.4 GHz the sensitivity reduction ranged from about 20% for 10 cm tall grassland cover to over 50 to 60% for the dense soybean field. At 5 GHz corresponding reduction in sensitivity ranged from approximately 70% to approximately 90%.

Microwave remote sensing of soil moisture content over bare and vegetated fields

NASA Technical Reports Server (NTRS)

Wang, J. R.; Shiue, J. C.; Mcmurtrey, J. E., III

1980-01-01

Remote measurements of soil moisture contents over bare fields and fields covered with orchard grass, corn, and soybean were made during October 1979 with 1.4 GHz and 5 GHz microwave radiometers mounted on a truck. Ground truth of soil moisture content, ambient air, and soil temperatures was acquired concurrently with the radiometric measurements. The biomass of the vegetation was sampled about once a week. The measured brightness temperatures over bare fields were compared with those of radiative transfer model calculations using as inputs the acquired soil moisture and temperature data with appropriate values of dielectric constants for soil-water mixtures. Good agreement was found between the calculated and the measured results over 10-70 deg incident angles. The presence of vegetation was found to reduce the sensitivity of soil moisture sensing. At 1.4 GHz the sensitivity reduction ranged from approximately 20% for 10-cm tall grassland to over 60% for the dense soybean field. At 5 GHz the corresponding reduction in sensitivity ranged from approximately 70 to approximately 90%.

Upgrade possibilities for continuous wave rf electron guns based on room-temperature very high frequency technology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sannibale, F.; Filippetto, D.; Johnson, M.

The past decade was characterized by an increasing scientific demand for extending towards higher repetition rates (MHz class and beyond) the performance of already operating lower repetition rate accelerator-based instruments such as x-ray free electron lasers (FELs) and ultrafast electron diffraction (UED) and microscopy (UEM) instruments. Such a need stimulated a worldwide spread of a vibrant R & D activity targeting the development of high-brightness electron sources capable of operating at these challenging rates. Among the different technologies pursued, rf guns based on room-temperature structures resonating in the very high frequency (VHF) range (30-300 MHz) and operating in continuous wavemore » successfully demonstrated in the past few years the targeted brightness and reliability. Nonetheless, recently proposed upgrades for x-ray FELs and the always brightness-frontier applications such as UED and UEM are now requiring a further step forward in terms of beam brightness in electron sources. Here, we present a few possible upgrade paths that would allow one to extend, in a relatively simple and cost-effective way, the performance of the present VHF technology to the required new goals.« less

Upgrade possibilities for continuous wave rf electron guns based on room-temperature very high frequency technology

DOE PAGES

Sannibale, F.; Filippetto, D.; Johnson, M.; ...

2017-11-27

The past decade was characterized by an increasing scientific demand for extending towards higher repetition rates (MHz class and beyond) the performance of already operating lower repetition rate accelerator-based instruments such as x-ray free electron lasers (FELs) and ultrafast electron diffraction (UED) and microscopy (UEM) instruments. Such a need stimulated a worldwide spread of a vibrant R & D activity targeting the development of high-brightness electron sources capable of operating at these challenging rates. Among the different technologies pursued, rf guns based on room-temperature structures resonating in the very high frequency (VHF) range (30-300 MHz) and operating in continuous wavemore » successfully demonstrated in the past few years the targeted brightness and reliability. Nonetheless, recently proposed upgrades for x-ray FELs and the always brightness-frontier applications such as UED and UEM are now requiring a further step forward in terms of beam brightness in electron sources. Here, we present a few possible upgrade paths that would allow one to extend, in a relatively simple and cost-effective way, the performance of the present VHF technology to the required new goals.« less

Temperature and color management of silicon solar cells for building integrated photovoltaic

NASA Astrophysics Data System (ADS)

Amara, Mohamed; Mandorlo, Fabien; Couderc, Romain; Gerenton, Félix; Lemiti, Mustapha

2018-01-01

Color management of integrated photovoltaics must meet two criteria of performance: provide maximum conversion efficiency and allow getting the chosen colors with an appropriate brightness, more particularly when using side by side solar cells of different colors. As the cooling conditions are not necessarily optimal, we need to take into account the influence of the heat transfer and temperature. In this article, we focus on the color space and brightness achieved by varying the antireflective properties of flat silicon solar cells. We demonstrate that taking into account the thermal effects allows freely choosing the color and adapting the brightness with a small impact on the conversion efficiency, except for dark blue solar cells. This behavior is especially true when heat exchange by convection is low. Our optical simulations show that the perceived color, for single layer ARC, is not varying with the position of the observer, whatever the chosen color. The use of a double layer ARC adds flexibility to tune the wanted color since the color space is greatly increased in the green and yellow directions. Last, choosing the accurate material allows both bright colors and high conversion efficiency at the same time.

Sensitivity of Support Vector Machine Predictions of Passive Microwave Brightness Temperature Over Snow-covered Terrain in High Mountain Asia

NASA Astrophysics Data System (ADS)

Ahmad, J. A.; Forman, B. A.

2017-12-01

High Mountain Asia (HMA) serves as a water supply source for over 1.3 billion people, primarily in south-east Asia. Most of this water originates as snow (or ice) that melts during the summer months and contributes to the run-off downstream. In spite of its critical role, there is still considerable uncertainty regarding the total amount of snow in HMA and its spatial and temporal variation. In this study, the NASA Land Information Systems (LIS) is used to model the hydrologic cycle over the Indus basin. In addition, the ability of support vector machines (SVM), a machine learning technique, to predict passive microwave brightness temperatures at a specific frequency and polarization as a function of LIS-derived land surface model output is explored in a sensitivity analysis. Multi-frequency, multi-polarization passive microwave brightness temperatures as measured by the Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E) over the Indus basin are used as training targets during the SVM training process. Normalized sensitivity coefficients (NSC) are then computed to assess the sensitivity of a well-trained SVM to each LIS-derived state variable. Preliminary results conform with the known first-order physics. For example, input states directly linked to physical temperature like snow temperature, air temperature, and vegetation temperature have positive NSC's whereas input states that increase volume scattering such as snow water equivalent or snow density yield negative NSC's. Air temperature exhibits the largest sensitivity coefficients due to its inherent, high-frequency variability. Adherence of this machine learning algorithm to the first-order physics bodes well for its potential use in LIS as the observation operator within a radiance data assimilation system aimed at improving regional- and continental-scale snow estimates.

Microwave Properties of Ice-Phase Hydrometeors for Radar and Radiometers: Sensitivity to Model Assumptions

NASA Technical Reports Server (NTRS)

Johnson, Benjamin T.; Petty, Grant W.; Skofronick-Jackson, Gail

2012-01-01

A simplied framework is presented for assessing the qualitative sensitivities of computed microwave properties, satellite brightness temperatures, and radar reflectivities to assumptions concerning the physical properties of ice-phase hydrometeors. Properties considered included the shape parameter of a gamma size distribution andthe melted-equivalent mass median diameter D0, the particle density, dielectric mixing formula, and the choice of complex index of refraction for ice. We examine these properties at selected radiometer frequencies of 18.7, 36.5, 89.0, and 150.0 GHz; and radar frequencies at 2.8, 13.4, 35.6, and 94.0 GHz consistent with existing and planned remote sensing instruments. Passive and active microwave observables of ice particles arefound to be extremely sensitive to the melted-equivalent mass median diameter D0 ofthe size distribution. Similar large sensitivities are found for variations in the ice vol-ume fraction whenever the geometric mass median diameter exceeds approximately 1/8th of the wavelength. At 94 GHz the two-way path integrated attenuation is potentially large for dense compact particles. The distribution parameter mu has a relatively weak effect on any observable: less than 1-2 K in brightness temperature and up to 2.7 dB difference in the effective radar reflectivity. Reversal of the roles of ice and air in the MaxwellGarnett dielectric mixing formula leads to a signicant change in both microwave brightness temperature (10 K) and radar reflectivity (2 dB). The choice of Warren (1984) or Warren and Brandt (2008) for the complex index of refraction of ice can produce a 3%-4% change in the brightness temperature depression.

The influence of thermal inertia on temperatures and frost stability on Triton

NASA Technical Reports Server (NTRS)

Spencer, John R.; Moore, Jeffrey M.

1992-01-01

It is presently argued, in view of (1) a thermal inertia model for the surface of Triton which (like previous ones) predicts a monotonic recession of permanent N2 deposits toward the poles and very little seasonal N2 frost in the southern hemisphere, and (2) new spectroscopic evidence for nonvolatile CO2 on Triton's bright southern hemisphere, that much of that bright southern material is not N2. Such bright southern hemisphere volatiles may allow the formation of seasonal frosts, thereby helping to explain the observed spectroscopic changes of Triton during the last decade.

Principles of computer processing of Landsat data for geologic applications

USGS Publications Warehouse

Taranik, James V.

1978-01-01

The main objectives of computer processing of Landsat data for geologic applications are to improve display of image data to the analyst or to facilitate evaluation of the multispectral characteristics of the data. Interpretations of the data are made from enhanced and classified data by an analyst trained in geology. Image enhancements involve adjustments of brightness values for individual picture elements. Image classification involves determination of the brightness values of picture elements for a particular cover type. Histograms are used to display the range and frequency of occurrence of brightness values. Landsat-1 and -2 data are preprocessed at Goddard Space Flight Center (GSFC) to adjust for the detector response of the multispectral scanner (MSS). Adjustments are applied to minimize the effects of striping, adjust for bad-data lines and line segments and lost individual pixel data. Because illumination conditions and landscape characteristics vary considerably and detector response changes with time, the radiometric adjustments applied at GSFC are seldom perfect and some detector striping remain in Landsat data. Rotation of the Earth under the satellite and movements of the satellite platform introduce geometric distortions in the data that must also be compensated for if image data are to be correctly displayed to the data analyst. Adjustments to Landsat data are made to compensate for variable solar illumination and for atmospheric effects. GeoMetric registration of Landsat data involves determination of the spatial location of a pixel in. the output image and the determination of a new value for the pixel. The general objective of image enhancement is to optimize display of the data to the analyst. Contrast enhancements are employed to expand the range of brightness values in Landsat data so that the data can be efficiently recorded in a manner desired by the analyst. Spatial frequency enhancements are designed to enhance boundaries between features which have subtle differences in brightness values. Ratioing tends to reduce the effects due to topography and it tends to emphasize changes in brightness values between two Landsat bands. Simulated natural color is produced for geologists so that the colors of materials on images appear similar to colors of actual materials in the field. Image classification of Landsat data involves both machine assisted delineation of multispectral patterns in four-dimensional spectral space and identification of machine delineated multispectral patterns that represent particular cover conditions. The geological information derived from an analysis of a multispectral classification is usually related to lithology.

Pioneer 10 observations of zodiacal light brightness near the ecliptic - Changes with heliocentric distance

NASA Technical Reports Server (NTRS)

Hanner, M. S.; Weinberg, J. L.; Beeson, D. E.; Sparrow, J. G.

1976-01-01

Sky maps made by the Pioneer 10 Imaging Photopolarimeter (IPP) at sun-spacecraft distances from 1 to 3 AU have been analyzed to derive the brightness of the zodiacal light near the ecliptic at elongations greater than 90 degrees. The change in zodiacal light brightness with heliocentric distance is compared with models of the spatial distribution of the dust. Use of background starlight brightnesses derived from IPP measurements beyond the asteroid belt, where the zodiacal light is not detected, and, especially, use of a corrected calibration lead to considerably lower values for zodiacal light than those reported by us previously.

Model development for MODIS thermal band electronic cross-talk

NASA Astrophysics Data System (ADS)

Chang, Tiejun; Wu, Aisheng; Geng, Xu; Li, Yonghong; Brinkmann, Jake; Keller, Graziela; Xiong, Xiaoxiong (Jack)

2016-10-01

MODerate-resolution Imaging Spectroradiometer (MODIS) has 36 bands. Among them, 16 thermal emissive bands covering a wavelength range from 3.8 to 14.4 μm. After 16 years on-orbit operation, the electronic crosstalk of a few Terra MODIS thermal emissive bands develop substantial issues which cause biases in the EV brightness temperature measurements and surface feature contamination. The crosstalk effects on band 27 with center wavelength at 6.7 μm and band 29 at 8.5 μm increased significantly in recent years, affecting downstream products such as water vapor and cloud mask. The crosstalk issue can be observed from nearly monthly scheduled lunar measurements, from which the crosstalk coefficients can be derived. Most of MODIS thermal bands are saturated at moon surface temperatures and the development of an alternative approach is very helpful for verification. In this work, a physical model was developed to assess the crosstalk impact on calibration as well as in Earth view brightness temperature retrieval. This model was applied to Terra MODIS band 29 empirically for correction of Earth brightness temperature measurements. In the model development, the detector nonlinear response is considered. The impacts of the electronic crosstalk are assessed in two steps. The first step consists of determining the impact on calibration using the on-board blackbody (BB). Due to the detector nonlinear response and large background signal, both linear and nonlinear coefficients are affected by the crosstalk from sending bands. The crosstalk impact on calibration coefficients was calculated. The second step is to calculate the effects on the Earth view brightness temperature retrieval. The effects include those from affected calibration coefficients and the contamination of Earth view measurements. This model links the measurement bias with crosstalk coefficients, detector nonlinearity, and the ratio of Earth measurements between the sending and receiving bands. The correction of the electronic crosstalk can be implemented empirically from the processed bias at different brightness temperature. The implementation can be done through two approaches. As routine calibration assessment for thermal infrared bands, the trending over select Earth scenes is processed for all the detectors in a band and the band averaged bias is derived for certain time. In this case, the correction of an affected band can be made using the regression of the model with band averaged bias and then corrections of detector differences are applied. The second approach requires the trending for individual detectors and the bias for each detector is used for regression with the model. A test using the first approach was made for Terra MODIS band 29 with the biases derived from long-term trending of sea surface temperature and Dome-C surface temperature.

Use of Radar Vegetation Index (RVI) in Passive Microwave Algorithms for Soil Moisture Estimates

NASA Astrophysics Data System (ADS)

Rowlandson, T. L.; Berg, A. A.

2013-12-01

The Soil Moisture Active Passive (SMAP) satellite will provide a unique opportunity for the estimation of soil moisture by having simultaneous radar and radiometer measurements available. As with the Soil Moisture and Ocean Salinity (SMOS) satellite, the soil moisture algorithms will need to account for the contribution of vegetation to the brightness temperature. Global maps of vegetation volumetric water content (VWC) are difficult to obtain, and the SMOS mission has opted to estimate the optical depth of standing vegetation by using a relationship between the VWC and the leaf area index (LAI). LAI is estimated from optical remote sensing or through soil-vegetation-atmosphere transfer modeling. During the growing season, the VWC of agricultural crops can increase rapidly, and if cloud cover exists during an optical acquisition, the estimation of LAI may be delayed, resulting in an underestimation of the VWC and overestimation of the soil moisture. Alternatively, the radar vegetation index (RVI) has shown strong correlation and linear relationship with VWC for rice and soybeans. Using the SMAP radar to produce RVI values that are coincident to brightness temperature measurements may eliminate the need for LAI estimates. The SMAP Validation Experiment 2012 (SMAPVEX12) was a cal/val campaign for the SMAP mission held in Manitoba, Canada, during a 6-week period in June and July, 2012. During this campaign, soil moisture measurements were obtained for 55 fields with varying soil texture and vegetation cover. Vegetation was sampled from each field weekly to determine the VWC. Soil moisture measurements were taken coincident to overpasses by an aircraft carrying the Passive and Active L-band System (PALS) instrumentation. The aircraft flew flight lines at both high and low altitudes. The low altitude flight lines provided a footprint size approximately equivalent to the size of the SMAPVEX12 field sites. Of the 55 field sites, the low altitude flight lines provided measurements for 15 fields. One field was planted in corn; three were pasture; six were soybeans; three were wheat; and two were winter wheat. The average RVI for each field was determined for each PALS overpass, with sampled radar data confined to the field dimensions. A linear interpolation was conducted between measured values of VWC to estimate a daily VWC value. A linear regression was conducted between the average VWC and the RVI, for each vegetation type. A positive linear relationship was found for all crops, with the exception of pasture. The correlation between the RVI and VWC was strong for corn and pasture, but moderate for soybeans and winter wheat; however, the correlation for corn was not significant. The developed models were utilized to provide a calculated VWC which was inputted into a modified version of the Land Parameter Retrieval Model (LPRM) to determine the error associated with using a calculated VWC from the RVI versus measured VWC data. The LPRM outputs for both scenarios were compared to the PALS radiometer measurements of brightness temperature.

Seasonal Changes in Titan's Surface Temperatures

NASA Technical Reports Server (NTRS)

Jennins, Donald E.; Cottini, V.; Nixon, C. A.; Flasar, F. M.; Kunde, V. G.; Samuelson, R. E.; Romani, P. N.; Hesman, B. E.; Carlson, R. C.; Gorius, N. J. P.;

VEGAS-SSS: A VST Programme to Study the Satellite Stellar Systems around Bright Early-type Galaxies

NASA Astrophysics Data System (ADS)

Cantiello, M.; Capaccioli, M.; Napolitano, N.; Grado, A.; Limatola, L.; Paolillo, M.; Iodice, E.; Romanowsky, A. J.; Forbes, D. A.; Raimondo, G.; Spavone, M.; La Barbera, F.; Puzia, T. H.; Schipani, P.

2015-03-01

The VEGAS-SSS programme is devoted to studying the properties of small stellar systems (SSSs) in and around bright galaxies, built on the VLT Survey Telescope early-type galaxy survey (VEGAS), an ongoing guaranteed time imaging survey distributed over many semesters (Principal Investigator: Capaccioli). On completion, the VEGAS survey will have collected detailed photometric information of ~ 100 bright early-type galaxies to study the properties of diffuse light (surface brightness, colours, surface brightness fluctuations, etc.) and the distribution of clustered light (compact ''small'' stellar systems) out to previously unreached projected galactocentric radii. VEGAS-SSS will define an accurate and homogeneous dataset that will have an important legacy value for studies of the evolution and transformation processes taking place in galaxies through the fossil information provided by SSSs.

Fall Colors, Temperature, and Day Length

ERIC Educational Resources Information Center

Burton, Stephen; Miller, Heather; Roossinck, Carrie

2007-01-01

Along with the bright hues of orange, red, and yellow, the season of fall represents significant changes, such as day length and temperature. These changes provide excellent opportunities for students to use science process skills to examine how abiotic factors such as weather and temperature impact organisms. In this article, the authors describe…

The Temperature and Distribution of Organic Molecules in the Inner Regions of T Tauri Disks

NASA Technical Reports Server (NTRS)

Mandell, Avi

2012-01-01

"High-resolution NIR spectroscopic observations of warm molecular gas emission from young circumstellar disks allow us to constrain the temperature and composition of material in the inner planet-forming region. By combining advanced data reduction algorithms with accurate modeling of the terrestrial atmospheric spectrum and a novel double-differencing data analysis technique, we have achieved very high-contrast measurements (S/N approx. 500-1000) of molecular emission at 3 microns. In disks around low-mass stars, we have achieved the first detections of emission from HCN and C2H2 at near-infrared wavelengths from several bright T Tauri stars using the CRIRES spectrograph on the Very Large Telescope and NIRSPEC spectrograph on the Keck Telescope. We spectrally resolve the line shape, showing that the emission has both a Keplerian and non-Keplerian component as observed previously for CO emission. We used a simplified single-temperature local thermal equilibrium (LTE) slab model with a Gaussian line profile to make line identifications and determine a best-fit temperature and initial abundance ratios, and we then compared these values with constraints derived from a detailed disk radiative transfer model assuming LTE excitation but utilizing a realistic temperature and density structure. Abundance ratios from both sets of models are consistent with each other and consistent with expected values from theoretical chemical models, and analysis of the line shapes suggests that the molecular emission originates from within a narrow region in the inner disk (R < 1 AU)."

Sky Brightness During Eclipses: A Compendium from the Literature

DTIC Science & Technology

1974-08-05

86 25. Absolute Values of Luminance of the Terrain and the Sky 88 26. Sky Brightness From Film No. 1 89 27. Sky Brightness From Film No. 2 89 28...these twilight equivalents when dust is present in the r.tmosphere are also difficult. Both involve the passage of light through long path lengths...purposes." Ilford-Selo, HP-3 isopan film with a sensitivity of 800 H & D was used. The measurement of the photographs was performed by means of a

[Study of Image Quality Comparison Based on the MTF Method Between Different Medical Rigid Endoscopes in an In Vitro Model].

PubMed

Wang, Yunlong; Ji, Jun; Jiang, Changsong; Huang, Zengyue

2015-04-01

This study was aimed to use the method of modulation transfer function (MTF) to compare image quality among three different Olympus medical rigid cystoscopes in an in vitro model. During the experimental processes, we firstly used three different types of cystoscopes (i. e. OLYMPUS cystourethroscopy with FOV of 12 degrees, OLYMPUS Germany A22003A and OLYMPUS A2013A) to collect raster images at different brightness with industrial camera and computer from the resolution target which is with different spatial frequency, and then we processed the collected images using MALAB software with the optical transfer function MTF to obtain the values of MTF at different brightness and different spatial frequency. We then did data mathematical statistics and compared imaging quality. The statistical data showed that all three MTF values were smaller than 1. MTF values with the spatial frequency gradually increasing would decrease approaching 0 at the same brightness. When the brightness enhanced in the same process at the same spatial frequency, MTF values showed a slowly increasing trend. The three endoscopes' MTF values were completely different. In some cases the MTF values had a large difference, and the maximum difference could reach 0.7. Conclusion can be derived from analysis of experimental data that three Olympus medical rigid cystoscopes have completely different imaging quality abilities. The No. 3 endoscope OLYMPUS A2013A has low resolution but high contrast. The No. 1 endoscope OLYMPUS cystourethroscopy with FOV of 12 degrees, on the contrary, had high resolution and lower contrast. The No. 2 endoscope OLYMPUS Germany A22003A had high contrast and high resolution, and its image quality was the best.

A New Bond Albedo for Performing Orbital Debris Brightness to Size Transformations

NASA Technical Reports Server (NTRS)

Mulrooney, Mark K.; Matney, Mark J.

2008-01-01

We have developed a technique for estimating the intrinsic size distribution of orbital debris objects via optical measurements alone. The process is predicated on the empirically observed power-law size distribution of debris (as indicated by radar RCS measurements) and the log-normal probability distribution of optical albedos as ascertained from phase (Lambertian) and range-corrected telescopic brightness measurements. Since the observed distribution of optical brightness is the product integral of the size distribution of the parent [debris] population with the albedo probability distribution, it is a straightforward matter to transform a given distribution of optical brightness back to a size distribution by the appropriate choice of a single albedo value. This is true because the integration of a powerlaw with a log-normal distribution (Fredholm Integral of the First Kind) yields a Gaussian-blurred power-law distribution with identical power-law exponent. Application of a single albedo to this distribution recovers a simple power-law [in size] which is linearly offset from the original distribution by a constant whose value depends on the choice of the albedo. Significantly, there exists a unique Bond albedo which, when applied to an observed brightness distribution, yields zero offset and therefore recovers the original size distribution. For physically realistic powerlaws of negative slope, the proper choice of albedo recovers the parent size distribution by compensating for the observational bias caused by the large number of small objects that appear anomalously large (bright) - and thereby skew the small population upward by rising above the detection threshold - and the lower number of large objects that appear anomalously small (dim). Based on this comprehensive analysis, a value of 0.13 should be applied to all orbital debris albedo-based brightness-to-size transformations regardless of data source. Its prima fascia genesis, derived and constructed from the current RCS to size conversion methodology (SiBAM Size-Based Estimation Model) and optical data reduction standards, assures consistency in application with the prior canonical value of 0.1. Herein we present the empirical and mathematical arguments for this approach and by example apply it to a comprehensive set of photometric data acquired via NASA's Liquid Mirror Telescopes during the 2000-2001 observing season.

Snowpack monitoring in North America and Eurasia using passive microwave satellite data

NASA Technical Reports Server (NTRS)

Foster, J. L.; Rango, A.; Hall, D. K.

1980-01-01

Areas of the Canadian high plains, the Montana and North Dakota high plains, and the steppes of central Russia were studied in an effort to determine the utility of spaceborne electrical scanning microwave radiometers (ESMR) for monitoring snow depths in different geographic areas. Significant regression relationships between snow depth and microwave brightness temperatures were developed for each of these homogeneous areas. In the areas investigated, Nimbus 6 (.081 cm) ESMR data produced higher correlations than Nimbus 5 (1.55 cm) ESMR data in relating microwave brightness temperature and snow depth from one area to another because different geographic areas are likely to have different snowpack conditions.

Modeling the non-grey-body thermal emission from the full moon

NASA Technical Reports Server (NTRS)

Vogler, Karl J.; Johnson, Paul E.; Shorthill, Richard W.

1991-01-01

The present series of thermophysical computer models for solid-surfaced planetary bodies whose surface roughness is modeled as paraboloidal craters of specified depth/diameter ratio attempts to characterize the nongrey-body brightness temperature spectra of the moon and of the Galilean satellites. This modeling, in which nondiffuse radiation properties and surface roughness are included for rigorous analysis of scattered and reemitted radiation within a crater, explains to first order the behavior of both limb-scans and disk-integrated IR brightness temperature spectra for the full moon. Only negative surface relief can explain lunar thermal emissions' deviation from smooth Lambert-surface expectations.

Satellite observations of a monsoon depression

NASA Technical Reports Server (NTRS)

Warner, C.

1984-01-01

The exploration of a monsoon depression over Burma and the Bay of Bengal is discussed. Aircraft and satellite data were examined, with an emphasis on the Microwave Sounding Unit (MSU) aboard TIROS-N and the Scanning Multichannel Microwave Radiometer (SMMR) aboard Nimbus-7. The structure of the monsoon depression was found to be dominated by cumulus convection. The only systematic large scale behavior discerned was a propagation of the depression westward, and diurnal migration of contours of brightness temperature. These contours in the middle troposphere showed a gradient toward the north with the patterns migrating northward at night. From SMMR and dropwindsonde data, water vapor contents were found to be near 65 mm, increasing to more than 70 mm in the northeast Bay of Bengal. Cloud water contents reached about three mm. Rainfall rates exceeding 5.7 mm/h occurred over a small part of the storm area, while mean rainfall rates in areas of order 20,000 sq km reached approximately 0.5 mm/h. Measured MSU brightness temperatures were reconciled very well with dropwindsonde data and with airborne in situ observations of clouds (by photography) and hydrometeors (by radar). Diffuse scattering was determined to be important in computing brightness temperature.

Remote sensing of the lightning heating effect duration with ground-based microwave radiometer

NASA Astrophysics Data System (ADS)

Jiang, Sulin; Pan, Yun; Lei, Lianfa; Ma, Lina; Li, Qing; Wang, Zhenhui

2018-06-01

Artificially triggered lightning events from May 26, 2017 to July 16, 2017 in Guangzhou Field Experiment Site for Lightning Research and Test (GFESL) were intentionally remotely sensed with a ground-based microwave radiometer for the first time in order to obtain the features of lightning heating effect. The microwave radiometer antenna was adjusted to point at a certain elevation angle towards the expected artificially triggered lightning discharging path. Eight of the 16 successfully artificially triggered lightning events were captured and the brightness temperature data at four frequencies in K and V bands were obtained. The results from data time series analysis show that artificially triggered lightning can make the radiometer generate brightness temperature pulses, and the amplitudes of these pulses are in the range of 2.0 K to 73.8 K. The brightness temperature pulses associated with 7 events can be used to estimate the duration of lightning heating effect through accounting the number of the pulses in the continuous pulse sequence and the sampling interval between four frequencies. The maximum duration of the lightning heating effect is 1.13 s, the minimum is 0.172 s, and the average is 0.63 s.

Aircraft microwave observations and simulations of deep convection from 18 to 183 GHz. II - Model results

NASA Technical Reports Server (NTRS)

Yeh, Hwa-Young M.; Prasad, N.; Mack, Robert A.; Adler, Robert F.

1990-01-01

In this June 29, 1986 case study, a radiative transfer model is used to simulate the aircraft multichannel microwave brightness temperatures presented in the Adler et al. (1990) paper and to study the convective storm structure. Ground-based radar data are used to derive hydrometeor profiles of the storm, based on which the microwave upwelling brightness temperatures are calculated. Various vertical hydrometeor phase profiles and the Marshall and Palmer (M-P, 1948) and Sekhon and Srivastava (S-S, 1970) ice particle size distributions are experimented in the model. The results are compared with the aircraft radiometric data. The comparison reveals that the M-P distribution well represents the ice particle size distribution, especially in the upper tropospheric portion of the cloud; the S-S distribution appears to better simulate the ice particle size at the lower portion of the cloud, which has a greater effect on the low-frequency microwave upwelling brightness temperatures; and that, in deep convective regions, significant supercooled liquid water (about 0.5 g/cu m) may be present up to the -30 C layer, while in less convective areas, frozen hydrometeors are predominant above -10 C level.

Absolute calibration of the OMEGA streaked optical pyrometer for temperature measurements of compressed materials

DOE PAGES

Gregor, M. C.; Boni, R.; Sorce, A.; ...

2016-11-29

Experiments in high-energy-density physics often use optical pyrometry to determine temperatures of dynamically compressed materials. In combination with simultaneous shock-velocity and optical-reflectivity measurements using velocity interferometry, these experiments provide accurate equation-of-state data at extreme pressures (P > 1 Mbar) and temperatures (T > 0.5 eV). This paper reports on the absolute calibration of the streaked optical pyrometer (SOP) at the Omega Laser Facility. The wavelength-dependent system response was determined by measuring the optical emission from a National Institute of Standards and Technology–traceable tungsten-filament lamp through various narrowband (40 nm-wide) filters. The integrated signal over the SOP’s ~250-nm operating range ismore » then related to that of a blackbody radiator using the calibrated response. We present a simple closed-form equation for the brightness temperature as a function of streak-camera signal derived from this calibration. As a result, error estimates indicate that brightness temperature can be inferred to a precision of <5%.« less

Absolute calibration of the OMEGA streaked optical pyrometer for temperature measurements of compressed materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gregor, M. C.; Boni, R.; Sorce, A.

Experiments in high-energy-density physics often use optical pyrometry to determine temperatures of dynamically compressed materials. In combination with simultaneous shock-velocity and optical-reflectivity measurements using velocity interferometry, these experiments provide accurate equation-of-state data at extreme pressures (P > 1 Mbar) and temperatures (T > 0.5 eV). This paper reports on the absolute calibration of the streaked optical pyrometer (SOP) at the Omega Laser Facility. The wavelength-dependent system response was determined by measuring the optical emission from a National Institute of Standards and Technology–traceable tungsten-filament lamp through various narrowband (40 nm-wide) filters. The integrated signal over the SOP’s ~250-nm operating range ismore » then related to that of a blackbody radiator using the calibrated response. We present a simple closed-form equation for the brightness temperature as a function of streak-camera signal derived from this calibration. As a result, error estimates indicate that brightness temperature can be inferred to a precision of <5%.« less

Assessing the influence of skin color and tooth shade value on perceived smile attractiveness.

PubMed

Sabherwal, Ruchika S; Gonzalez, Juan; Naini, Farhad B

2009-06-01

The authors conducted a study to determine whether variations in skin color would influence perceptions of smile attractiveness for a given tooth shade value. Using a photograph of a woman smiling, the authors altered skin color to consist of four tones (fair, fair/medium, medium/dark and dark) and altered tooth shade value (brightness) to range from 00 (brightest) to 05 (darkest). Two groups of judges (70 dentists, 70 laypeople) completed a questionnaire and rated the images for smile attractiveness. For most tooth shade values (00, 01, 03, 04, 05), multiple mixed linear regression showed that variation in skin color influenced respondents' perceptions of smile attractiveness (P < .001). For images corresponding to tooth shade values 01, 02, 03, 04 and 05, men provided lower ratings than did women (P < .05). Attractiveness ratings increased with the age of participants (P < .05). Dentists rated images higher than did laypeople (P < .05). Variation in skin color for most tooth shade values influenced dentists' and laypeople's perceived smile attractiveness. Dentists and laypeople did not perceive the brightest tooth shade to be the most attractive, and they did not perceive all skin colors to be equally attractive with bright white teeth. Respondents perceived dark skin with bright white teeth and fair skin with dark teeth as relatively unattractive.

Simultaneous Assimilation of AMSR-E Brightness Temperature and MODIS LST to Improve Soil Moisture with Dual Ensemble Kalman Smoother

NASA Astrophysics Data System (ADS)

Huang, Chunlin; Chen, Weijin; Wang, Weizhen; Gu, Juan

2017-04-01

Uncertainties in model parameters can easily cause systematic differences between model states and observations from ground or satellites, which significantly affect the accuracy of soil moisture estimation in data assimilation systems. In this paper, a novel soil moisture assimilation scheme is developed to simultaneously assimilate AMSR-E brightness temperature (TB) and MODIS Land Surface Temperature (LST), which can correct model bias by simultaneously updating model states and parameters with dual ensemble Kalman filter (DEnKS). The Common Land Model (CoLM) and a Q-h Radiative Transfer Model (RTM) are adopted as model operator and observation operator, respectively. The assimilation experiment is conducted in Naqu, Tibet Plateau, from May 31 to September 27, 2011. Compared with in-situ measurements, the accuracy of soil moisture estimation is tremendously improved in terms of a variety of scales. The updated soil temperature by assimilating MODIS LST as input of RTM can reduce the differences between the simulated and observed brightness temperatures to a certain degree, which helps to improve the estimation of soil moisture and model parameters. The updated parameters show large discrepancy with the default ones and the former effectively reduces the states bias of CoLM. Results demonstrate the potential of assimilating both microwave TB and MODIS LST to improve the estimation of soil moisture and related parameters. Furthermore, this study also indicates that the developed scheme is an effective soil moisture downscaling approach for coarse-scale microwave TB.

Fusion of Terra-MODIS and Landsat TM data for geothermal sites investigation in Jiangsu Province, China

NASA Astrophysics Data System (ADS)

Chen, Shengbo

2006-01-01

Geothermal resources are generally confined to areas of the Earth's crust where heat flow higher than in surrounding areas heats the water contained in permeable rocks (reservoirs) at depth. It is becoming one of attractive solutions for clean and sustainable energy future for the world. The geothermal fields commonly occurs at the boundaries of plates, and only occasionally in the middle of a plate. The study area, Jiangsu Province, as an example, located in the east of China, is a potential area of geothermal energy. In this study, Landsat thematic Mapper (TM) data were georeferenced to position spatially the geothermal energy in the study area. Multi-spectral infrared data of Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Terra platform were georeferenced to Landsat TM images. Based on the Wien Displacement Law, these infrared data indicate the surface emitted radiance under the same atmospheric condition, and stand for surface bright temperature respectively. Thus, different surface bright temperature data from Terra-MODIS band 20 or band 31 (R), together with Landsat TM band 4 (G) and band 3 (B) separately, were made up false color composite images (RGB) to generate the distribution maps of surface bright temperatures. Combing with geologic environment and geophysical anomalies, the potential area of geothermal energy with different geo-temperature were mapped respectively. Specially, one geothermal spot in Qinhu Lake Scenery Area in Taizhou city was validated by drilling, and its groundwater temperature is up to some 51°.

Milliarcsecond Imaging of the Radio Emission from the Quasar with the Most Massive Black Hole at Reionization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Ran; Wu, Xue-Bing; Jiang, Linhua

We report Very Long Baseline Array (VLBA) observations of the 1.5 GHz radio continuum emission of the z = 6.326 quasar SDSS J010013.02+280225.8 (hereafter J0100+2802). J0100+2802 is by far the most optically luminous and is a radio-quiet quasar with the most massive black hole known at z > 6. The VLBA observations have a synthesized beam size of 12.10 mas ×5.36 mas (FWHM), and detected the radio continuum emission from this object with a peak surface brightness of 64.6 ± 9.0 μ Jy beam{sup −1} and a total flux density of 88 ± 19 μ Jy. The position of themore » radio peak is consistent with that from SDSS in the optical and Chandra in the X-ray. The radio source is marginally resolved by the VLBA observations. A 2D Gaussian fit to the image constrains the source size to (7.1 ± 3.5) mas × (3.1 ± 1.7) mas. This corresponds to a physical scale of (40 ± 20) pc × (18 ± 10) pc. We estimate the intrinsic brightness temperature of the VLBA source to be T {sub B} = (1.6 ± 1.2) × 10{sup 7} K. This is significantly higher than the maximum value in normal star-forming galaxies, indicating an active galactic nucleus (AGN) origin for the radio continuum emission. However, it is also significantly lower than the brightness temperatures found in highest-redshift radio-loud quasars. J0100+2802 provides a unique example for studying the radio activity in optically luminous and radio-quiet AGNs in the early universe. Further observations at multiple radio frequencies will accurately measure the spectral index and address the dominant radiation mechanism of the radio emission.« less

Convective and stratiform rain: Multichannel microwave sensing over oceans

NASA Technical Reports Server (NTRS)

Prabhakara, C.; Nucciarone, J. J.; Dalu, G.

1993-01-01

Measurements made by the Special Sensor Microwave/Imager (SSM/I) radiometer over the oceans, at 19, 37, and 85 GHz in dual polarization, are used to develop a model to classify rain into light-stratiform, moderately convective, and heavy convective types in the mesoscale convective systems (MCS). It is observed that the bulk of the 19- and 37-GHz data are linearly correlated with respect to one another, and generally increase together in brightness as the mean rain rate in the field of view (FOV) of the radiometer increases. However, a significant fraction of the data from these channels departs from this linear relationship, reflecting the nonuniform rain that is convective vs. the relatively light stratiform rain. It is inferred from the SSM/I data, in a MCS, when the slope dT sub 3/dT sub 19 is greater than unity there are optically thin clouds which produce light uniform rain. On the other hand, when dT sub 3/dT sub 19 is close to unity, the rain cells have an open structure and correspond to the convective type of rain. The openings between the cells are apparently a result of the downdrafts and/or entrainment. Relatively low values of 85-GHz brightness temperatures that are present when dT sub 37/dT sub 19 is close to unity support these views and, in addition, leads us to conclude that when the convection is heavy this brightness temperature decreases due to scattering by hydrometeors. On the basis of this explanation of the SSM/I data, an empirical rain retrieval algorithm is developed. Radar backscatter observations over the Atlantic Ocean next to Florida are used to demonstrate the applicability of this method. Three monthly mean maps of rainfall over the oceans from 50 degrees N to 50 degrees S, are presented to illustrate the ability of this method to sense seasonal and interannual variations of rain.

Recombination Line versus Forbidden Line Abundances in Planetary Nebulae

NASA Astrophysics Data System (ADS)

Robertson-Tessi, Mark; Garnett, Donald R.

2005-04-01

Recombination lines (RLs) of C II, N II, and O II in planetary nebulae (PNs) have been found to give abundances that are much larger in some cases than abundances from collisionally excited forbidden lines (CELs). The origins of this abundance discrepancy are highly debated. We present new spectroscopic observations of O II and C II recombination lines for six planetary nebulae. With these data we compare the abundances derived from the optical recombination lines with those determined from collisionally excited lines. Combining our new data with published results on RLs in other PNs, we examine the discrepancy in abundances derived from RLs and CELs. We find that there is a wide range in the measured abundance discrepancy Δ(O+2)=logO+2(RL)-logO+2(CEL), ranging from approximately 0.1 dex (within the 1 σ measurement errors) up to 1.4 dex. This tends to rule out errors in the recombination coefficients as a source of the discrepancy. Most RLs yield similar abundances, with the notable exception of O II multiplet V15, known to arise primarily from dielectronic recombination, which gives abundances averaging 0.6 dex higher than other O II RLs. We compare Δ(O+2) against a variety of physical properties of the PNs to look for clues as to the mechanism responsible for the abundance discrepancy. The strongest correlations are found with the nebula diameter and the Balmer surface brightness; high surface brightness, compact PNs show small values of Δ(O+2), while large low surface brightness PNs show the largest discrepancies. An inverse correlation of Δ(O+2) with nebular density is also seen. A marginal correlation of Δ(O+2) is found with expansion velocity. No correlations are seen with electron temperature, He+2/He+, central star effective temperature and luminosity, stellar mass-loss rate, or nebular morphology. Similar results are found for carbon in comparing C II RL abundances with ultraviolet measurements of C III].

Characteristics of the Energetic Igniters Through Integrating B/Ti Nano-Multilayers on TaN Film Bridge

NASA Astrophysics Data System (ADS)

Yan, YiChao; Shi, Wei; Jiang, HongChuan; Cai, XianYao; Deng, XinWu; Xiong, Jie; Zhang, WanLi

2015-05-01

The energetic igniters through integrating B/Ti nano-multilayers on tantalum nitride (TaN) ignition bridge are designed and fabricated. The X-ray diffraction (XRD) and temperature coefficient of resistance (TCR) results show that nitrogen content has a great influence on the crystalline structure and TCR. TaN films under nitrogen ratio of 0.99 % exhibit a near-zero TCR value of approximately 10 ppm/°C. The scanning electron microscopy demonstrates that the layered structure of the B/Ti multilayer films is clearly visible with sharp and smooth interfaces. The electrical explosion characteristics employing a capacitor discharge firing set at the optimized charging voltage of 45 V reveal an excellent explosion performance by (B/Ti) n /TaN integration film bridge with small ignition delay time, high explosion temperature, much more bright flash of light, and much large quantities of the ejected product particles than TaN film bridge.

Colour analysis of the equine endometrium: comparison of spectrophotometry and computer-assisted analysis of photographs within the L*a*b* colour space system.

PubMed

Neuhauser, S; Handler, J

2013-09-01

The aims of this study were to compare two different methods of quantifying the colour of the luminal surface of the equine endometrium and to relate the results to histopathological evidence of inflammation and fibrosis. The mucosal surfaces of 17 equine uteri obtained from an abattoir were assessed using a spectrophotometer and by computer-assisted analysis of photographs. Values were converted into L(*)a(*)b(*) colour space. Although there was significant correlation between the two methods of quantification, variations in 'brightness', 'red' and 'yellow' values were noted. Within a given uterus, measurements using the spectrophotometer did not differ significantly. Using photographic analysis, brightness differed between horns, although no differences in chromaticity were found. Histopathological classification of changes within endometria corresponded to measured differences in colour. Extensive fibrosis was associated with increased brightness and decreased chromaticity using both methods. Inflammation correlated with reduced chromaticity, when measured by spectrophotometry, and with reduced brightness and yellow values, when assessed photographically. For this technique to gain wider acceptance as a diagnostic tool, e.g. for the endoscopic evaluation of uterine mucosae in vivo, standardised illumination techniques will be required so that colours can be compared and interpreted accurately. Copyright © 2013 Elsevier Ltd. All rights reserved.

Solar corona during the 1994 and 1999 eclipses

NASA Astrophysics Data System (ADS)

Badalyan, O. G.; Sýkora, J.

2008-06-01

The lower and middle layers of the corona are studied analyzing the ground-based observations carried out during the November 3, 1994 and August 11, 1999 total solar eclipses. While the 1994 eclipse took place nearby the solar activity minimum, the 1999 eclipse occurred closer to the solar cycle maximum. Structures, isolines of brightness and polarization, and topology of the magnetic field lines of force (calculated under a potential approximation) of these two coronae are mutually compared. It is confirmed that the brightness distribution in the corona corresponds to the hydrostatic distribution of density at the distances 1.2-1.8R⊙. Temperature 1.4 MK and density n0 = 3.3 × 108cm-3 are found for the equatorial coronal regions of the 1999 corona. Physical conditions in the polar coronal regions are investigated analyzing the brightness and polarization of the 1994 eclipse. We have found that the degree of polarization in polar plumes is about 10% higher than that in the inter-plumes space. Consideration of the brightness in plumes and in the adjacent background space allowed us to conclude that the temperatures there are close to 1 MK. The density in the individual plumes is near n0 = 2.7 × 108cm-3, while it decreases to about n0 = 2.0 × 108cm-3 in the inter-plumes space. It is pointed out that the simultaneous interpretation of the measured brightness and polarization struggles with some difficulties.

Subjective time runs faster under the influence of bright rather than dim light conditions during the forenoon.

PubMed

Morita, Takeshi; Fukui, Tomoe; Morofushi, Masayo; Tokura, Hiromi

2007-05-16

The study investigated if 6 h morning bright light exposure, compared with dim light exposure, could influence time sense (range: 5-15 s). Eight women served as participants. The participant entered a bioclimatic chamber at 10:00 h on the day before the test day, where an ambient temperature and relative humidity were controlled at 25 degrees C and 60%RH. She sat quietly in a sofa in 50 lx until 22:00 h, retired at 22:00 h and then slept in total darkness. She rose at 07:00 h the following morning and again sat quietly in a sofa till 13:00 h, either in bright (2500 lx) or dim light (50 lx), the order of light intensities between the two occasions being randomized. The time-estimation test was performed from 13:00 to 13:10 h in 200 lx. The participant estimated the time that had elapsed between two buzzers, ranging over 5-15 s, and inputting the estimate into a computer. The test was carried out separately upon each individual. Results showed that the participants estimated higher durations of the given time intervals after previous exposure to 6 h of bright rather than dim light. The finding is discussed in terms of different load errors (difference between the actual core temperature and its thermoregulatory set-point) following 6-h exposure to bright or dim light in the morning.

The Effect of maceration period on contents and color brightness of phycoerythrin from Gracilaria sp.

NASA Astrophysics Data System (ADS)

Lidiana, H.; Sulmartiwi, L.; Andriyono, S.

2018-04-01

Natural pigment from seaweed, is currently required by humans as one of active compounds that are usefull in the field of health, cosmetics and food. One of the pigments which potentially can be developed is red phycobilin pigment. The pigment can be obtained from Gracilaria sp. throught maceration method. This research aims to find out wheter there is influence from the long maceration time toward to the content and the phycoerytrin color brightness of Gracilaria sp. The reseach method used experimental experiment with complete randomized design (CRD) which was consisted of nine treatments of long time maceration period three replications. Data analysis was used the Analysis of Variance (ANOVA) and continued to Duncan’s Multiple Distance Test to. The result showed that treatments with the time of maceration for 30 hours was the best treatment on phycoerytrin content about 0.98 mg/g with the brightness value was 19.73 L*, reddish value was 7.23 a*, and yellowish value was 2.87 b* of Gracilaria sp.

Improved mapping of radio sources from VLBI data by least-square fit

NASA Technical Reports Server (NTRS)

Rodemich, E. R.

1985-01-01

A method is described for producing improved mapping of radio sources from Very Long Base Interferometry (VLBI) data. The method described is more direct than existing Fourier methods, is often more accurate, and runs at least as fast. The visibility data is modeled here, as in existing methods, as a function of the unknown brightness distribution and the unknown antenna gains and phases. These unknowns are chosen so that the resulting function values are as near as possible to the observed values. If researchers use the radio mapping source deviation to measure the closeness of this fit to the observed values, they are led to the problem of minimizing a certain function of all the unknown parameters. This minimization problem cannot be solved directly, but it can be attacked by iterative methods which we show converge automatically to the minimum with no user intervention. The resulting brightness distribution will furnish the best fit to the data among all brightness distributions of given resolution.

A Physical Model to Estimate Snowfall over Land using AMSU-B Observations

NASA Technical Reports Server (NTRS)

Kim, Min-Jeong; Weinman, J. A.; Olson, W. S.; Chang, D.-E.; Skofronick-Jackson, G.; Wang, J. R.

2008-01-01

In this study, we present an improved physical model to retrieve snowfall rate over land using brightness temperature observations from the National Oceanic and Atmospheric Administration's (NOAA) Advanced Microwave Sounder Unit-B (AMSU-B) at 89 GHz, 150 GHz, 183.3 +/- 1 GHz, 183.3 +/- 3 GHz, and 183.3 +/- 7 GHz. The retrieval model is applied to the New England blizzard of March 5, 2001 which deposited about 75 cm of snow over much of Vermont, New Hampshire, and northern New York. In this improved physical model, prior retrieval assumptions about snowflake shape, particle size distributions, environmental conditions, and optimization methodology have been updated. Here, single scattering parameters for snow particles are calculated with the Discrete-Dipole Approximation (DDA) method instead of assuming spherical shapes. Five different snow particle models (hexagonal columns, hexagonal plates, and three different kinds of aggregates) are considered. Snow particle size distributions are assumed to vary with air temperature and to follow aircraft measurements described by previous studies. Brightness temperatures at AMSU-B frequencies for the New England blizzard are calculated using these DDA calculated single scattering parameters and particle size distributions. The vertical profiles of pressure, temperature, relative humidity and hydrometeors are provided by MM5 model simulations. These profiles are treated as the a priori data base in the Bayesian retrieval algorithm. In algorithm applications to the blizzard data, calculated brightness temperatures associated with selected database profiles agree with AMSU-B observations to within about +/- 5 K at all five frequencies. Retrieved snowfall rates compare favorably with the near-concurrent National Weather Service (NWS) radar reflectivity measurements. The relationships between the NWS radar measured reflectivities Z(sub e) and retrieved snowfall rate R for a given snow particle model are derived by a histogram matching technique. All of these Z(sub e)-R relationships fall in the range of previously established Z(sub e)-R relationships for snowfall. This suggests that the current physical model developed in this study can reliably estimate the snowfall rate over land using the AMSU-B measured brightness temperatures.

Drilling of optical glass with electroplated diamond tools

NASA Astrophysics Data System (ADS)

Wang, A. J.; Luan, C. G.; Yu, A. B.

2010-10-01

K9 optical glass drilling experiments were carried out. Bright nickel electroplated diamond tools with small slots and under heat treatment in different temperature were fabricated. Scan electro microscope was applied to analyze the wear of electroplated diamond tool. The material removal rate and grinding ratio were calculated. Machining quality was observed. Bond coating hardness was measured. The experimental results show that coolant is needed for the drilling processes of optical glasses. Heat treatment temperature of diamond tool has influence on wearability of diamond tool and grinding ratio. There were two wear types of electroplated diamond tool, diamond grit wear and bond wear. With the machining processes, wear of diamond grits included fracture, blunt and pull-out, and electroplated bond was gradually worn out. High material removal rates could be obtained by using diamond tool with suitable slot numbers. Bright nickel coating bond presents smallest grains and has better mechanical properties. Bright nickel electroplated diamond tool with slot structure and heat treatment under 200°C was suitable for optical glass drilling.

Comparison and evaluation of the Chang'E microwave radiometer data based on theoretical computation of brightness temperatures at the Apollo 15 and 17 sites

NASA Astrophysics Data System (ADS)

Hu, Guo-Ping; Chan, Kwing L.; Zheng, Yong-Chun; Tsang, Kang T.; Xu, Ao-Ao

2017-09-01

There are significant differences (in the order of 3 to 20 K) between the lunar brightness temperatures (TBs) as measured by the microwave radiometers (MRM) onboard Chang'E (CE)-1 and -2. To determine which set is more accurate, we have carried out a dataset comparison using theoretical calculations of the TBs (four frequency channels) versus local time at the Apollo 15 and 17 landing sites, where the thermal parameters are well-constrained by the in-situ measurements. Based on these parameters, we sought to constrain fits between theory and observation, as uncertainties still exist in parameters involved in the microwave transfer computation. We found that: (i) CE-1/2 TBs have almost constant biases (negative, different for different channels) from the theoretical TBs. The averaged biases for each channel are smaller for CE-1; (ii) TBs of the high frequency channels (19.35/37 GHz) show a better fit with theory than the low frequency channels. The channel 4 (37 GHz) TBs from CE-1 are consistently shifted by about 1 K from the theoretical values. Adjustments in the order of 20 K are instead needed for the two CE-2 low frequency channels (3/7.8 GHz). Based on this comparison, we conclude that the CE-1 dataset to be more accurate than CE-2 one in terms of temperature accuracy (not spatial resolution). We also offer a possible explanation for the significant TB differences between CE-1 and CE-2, and propose a possible recalibration method as a starting point towards the realignment of the two datasets.

Optical Sky Brightness and Transparency during the Winter Season at Dome A Antarctica from the Gattini-All-Sky Camera

NASA Astrophysics Data System (ADS)

Yang, Yi; Moore, Anna M.; Krisciunas, Kevin; Wang, Lifan; Ashley, Michael C. B.; Fu, Jianning; Brown, Peter J.; Cui, Xiangqun; Feng, Long-Long; Gong, Xuefei; Hu, Zhongwen; Lawrence, Jon S.; Luong-Van, Daniel; Riddle, Reed L.; Shang, Zhaohui; Sims, Geoff; Storey, John W. V.; Suntzeff, Nicholas B.; Tothill, Nick; Travouillon, Tony; Yang, Huigen; Yang, Ji; Zhou, Xu; Zhu, Zhenxi

2017-07-01

The summit of the Antarctic plateau, Dome A, is proving to be an excellent site for optical, near-infrared, and terahertz astronomical observations. Gattini is a wide-field camera installed on the PLATO instrument module as part of the Chinese-led traverse to Dome A in 2009 January. We present here the measurements of sky brightness with the Gattini ultra-large field of view (90^\\circ × 90^\\circ ) in the photometric B-, V-, and R-bands; cloud cover statistics measured during the 2009 winter season; and an estimate of the sky transparency. A cumulative probability distribution indicates that the darkest 10% of the nights at Dome A have sky brightness of S B = 22.98, S V = 21.86, and S R = 21.68 mag arcsec-2. These values were obtained during the year 2009 with minimum aurora, and they are comparable to the faintest sky brightness at Maunakea and the best sites of northern Chile. Since every filter includes strong auroral lines that effectively contaminate the sky brightness measurements, for instruments working around the auroral lines, either with custom filters or with high spectral resolution instruments, these values could be easily obtained on a more routine basis. In addition, we present example light curves for bright targets to emphasize the unprecedented observational window function available from this ground-based site. These light curves will be published in a future paper.

Selection of embryogenic sugarcane callus by image analysis.

PubMed

Honda, H; Ito, T; Yamada, J; Hanai, T; Matsuoka, M; Kobayashi, T

1999-01-01

In the cultivation of plant calli on solid media, two kinds of calli such as compact and friable calli, which are a bright yellow and a whitish clump, respectively, are often obtained. Distinction of these calli is of much importance in the regeneration step. The image analysis system associated with a Charge Coupled Device (CCD) camera and microscopy were used to distinguish sugarcane calli. The original images from compact and friable calli were input to a computer via an image analysis board. At first, the brightnesses of trichromatic colors, red (R), green (G) and blue (B), of each pixels were extracted and the average brightness value for each color was calculated. From these values of the trichromatic colors, compact and friable calli could not be clearly distinguished. Next, the brightness of yellow, Br(Y), and white, Br(W), were defined using Br(R), Br(G) and Br(B), and the difference between Br(Y) and Br(W), Br(Y-W), which can be used to express the yellowish grade, was calculated. When Br(Y-W) was determined from all pixels of the original images of both calli, the compact calli were found to be clearly distinguished from the friable calli by the frequency distributions of Br(Y-W). Average brightness center value, Av(C(Y-W)), was calculated from the frequency distributions. It was found that the calli with less than 10 units of Av(C(Y-W)) was never regenerated and a proportional relationship between Av(C(Y-W)) and the regeneration frequency of the callus line was obtained.

Exposure to bright light biases effort-based decisions.

PubMed

Bijleveld, Erik; Knufinke, Melanie

2018-06-01

Secreted in the evening and the night, melatonin suppresses activity of the mesolimbic dopamine pathway, a brain pathway involved in reward processing. However, exposure to bright light diminishes-or even prevents-melatonin secretion. Thus, we hypothesized that reward processing, in the evening, is more pronounced in bright light (vs. dim light). Healthy human participants carried out three tasks that tapped into various aspects of reward processing (effort expenditure for rewards task [EEfRT]; two-armed bandit task [2ABT]; balloon analogue risk task [BART). Brightness was manipulated within-subjects (bright vs. dim light), in separate evening sessions. During the EEfRT, participants used reward-value information more strongly when they were exposed to bright light (vs. dim light). This finding supported our hypothesis. However, exposure to bright light did not significantly affect task behavior on the 2ABT and the BART. While future research is necessary (e.g., to zoom in on working mechanisms), these findings have potential implications for the design of physical work environments. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

A one-layer satellite surface energy balance for estimating evapotranspiration rates and crop water stress indexes.

PubMed

Barbagallo, Salvatore; Consoli, Simona; Russo, Alfonso

2009-01-01

Daily evapotranspiration fluxes over the semi-arid Catania Plain area (Eastern Sicily, Italy) were evaluated using remotely sensed data from Landsat Thematic Mapper TM5 images. A one-source parameterization of the surface sensible heat flux exchange using satellite surface temperature has been used. The transfer of sensible and latent heat is described by aerodynamic resistance and surface resistance. Required model inputs are brightness, temperature, fractional vegetation cover or leaf area index, albedo, crop height, roughness lengths, net radiation, air temperature, air humidity and wind speed. The aerodynamic resistance (r(ah)) is formulated on the basis of the Monin-Obukhov surface layer similarity theory and the surface resistance (r(s)) is evaluated from the energy balance equation. The instantaneous surface flux values were converted into evaporative fraction (EF) over the heterogeneous land surface to derive daily evapotranspiration values. Remote sensing-based assessments of crop water stress (CWSI) were also made in order to identify local irrigation requirements. Evapotranspiration data and crop coefficient values obtained from the approach were compared with: (i) data from the semi-empirical approach "K(c) reflectance-based", which integrates satellite data in the visible and NIR regions of the electromagnetic spectrum with ground-based measurements and (ii) surface energy flux measurements collected from a micrometeorological tower located in the experiment area. The expected variability associated with ET flux measurements suggests that the approach-derived surface fluxes were in acceptable agreement with the observations.

THE CHROMOSPHERIC SOLAR MILLIMETER-WAVE CAVITY ORIGINATES IN THE TEMPERATURE MINIMUM REGION

DOE Office of Scientific and Technical Information (OSTI.GOV)

De la Luz, Victor; Raulin, Jean-Pierre; Lara, Alejandro

2013-01-10

We present a detailed theoretical analysis of the local radio emission at the lower part of the solar atmosphere. To accomplish this, we have used a numerical code to simulate the emission and transport of high-frequency electromagnetic waves from 2 GHz up to 10 THz. As initial conditions, we used VALC, SEL05, and C7 solar chromospheric models. In this way, the generated synthetic spectra allow us to study the local emission and absorption processes with high resolution in both altitude and frequency. Associated with the temperature minimum predicted by these models, we found that the local optical depth at millimetermore » wavelengths remains constant, producing an optically thin layer that is surrounded by two layers of high local emission. We call this structure the Chromospheric Solar Millimeter-wave Cavity (CSMC). The temperature profile, which features temperature minimum layers and a subsequent temperature rise, produces the CSMC phenomenon. The CSMC shows the complexity of the relation between the theoretical temperature profile and the observed brightness temperature and may help us to understand the dispersion of the observed brightness temperature in the millimeter wavelength range.« less

Laser ion source for high brightness heavy ion beam

DOE PAGES

Okamura, M.

2016-09-01

A laser ion source is known as a high current high charge state heavy ion source. But, we place great emphasis on the capability to realize a high brightness ion source. A laser ion source has a pinpoint small volume where materials are ionized and can achieve quite uniform low temperature ion beam. Those features may enable us to realize very small emittance beams. Furthermore, a low charge state high brightness laser ion source was successfully commissioned in Brookhaven National Laboratory in 2014. Now most of all the solid based heavy ions are being provided from the laser ion sourcemore » for regular operation.« less

USSR Report, Electronics and Electrical Engineering.

DTIC Science & Technology

1985-04-30

References 15: 12 Russian, 3 Western. [147-6900] UDC: 621.316.933.6 WIDE-APERTURE ’ BLACK BOY ’ UHF NOISE EMITTER WITH 104 K BRIGHTNESS TEMPERATURE...Ferromagnetic Semiconductors (F. G. Bass, N. N. Nasonov; IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY RADIOFIZIKA, No 11, Nov 84) 19 A Wide-Aperture ’ Black ... Boy ’ UHF Noise Emitter with 10 K Brightness (S. V. Butakova; IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY RADIOFIZIKA, No 11, Nov 84) 19 BROADCASTING

Bright carbonate deposits as evidence of aqueous alteration on (1) Ceres

NASA Astrophysics Data System (ADS)

de Sanctis, M. C.; Raponi, A.; Ammannito, E.; Ciarniello, M.; Toplis, M. J.; McSween, H. Y.; Castillo-Rogez, J. C.; Ehlmann, B. L.; Carrozzo, F. G.; Marchi, S.; Tosi, F.; Zambon, F.; Capaccioni, F.; Capria, M. T.; Fonte, S.; Formisano, M.; Frigeri, A.; Giardino, M.; Longobardo, A.; Magni, G.; Palomba, E.; McFadden, L. A.; Pieters, C. M.; Jaumann, R.; Schenk, P.; Mugnuolo, R.; Raymond, C. A.; Russell, C. T.

2016-08-01

The typically dark surface of the dwarf planet Ceres is punctuated by areas of much higher albedo, most prominently in the Occator crater. These small bright areas have been tentatively interpreted as containing a large amount of hydrated magnesium sulfate, in contrast to the average surface, which is a mixture of low-albedo materials and magnesium phyllosilicates, ammoniated phyllosilicates and carbonates. Here we report high spatial and spectral resolution near-infrared observations of the bright areas in the Occator crater on Ceres. Spectra of these bright areas are consistent with a large amount of sodium carbonate, constituting the most concentrated known extraterrestrial occurrence of carbonate on kilometre-wide scales in the Solar System. The carbonates are mixed with a dark component and small amounts of phyllosilicates, as well as ammonium carbonate or ammonium chloride. Some of these compounds have also been detected in the plume of Saturn’s sixth-largest moon Enceladus. The compounds are endogenous and we propose that they are the solid residue of crystallization of brines and entrained altered solids that reached the surface from below. The heat source may have been transient (triggered by impact heating). Alternatively, internal temperatures may be above the eutectic temperature of subsurface brines, in which case fluids may exist at depth on Ceres today.

Effects of hue, saturation, and brightness on preference: a study on Goethe's color circle with RGB color space

NASA Astrophysics Data System (ADS)

Camgoz, Nilgun; Yener, Cengiz

2002-06-01

In order to investigate preference responses for foreground- background color relationships, 85 university undergraduates in Ankara, Turkey, viewed 6 background colors (red, yellow, green, cyan, blue, and magenta) on which color squares of differing hues, saturations, and brightnesses were presented. All the background colors had maximum brightness (100%) and maximum saturation (100%). Subjects were asked to show the color square they preferred on the presented background color viewed through a computer monitor. The experimental setup consisted of a computer monitor located in a windowless room, illuminated with cove lighting. The findings of the experiment show that the brightness 100%- saturation 100% range is significantly preferred the most (p-value < 0.03). Thus, color squares that are most saturated and brightest are preferred on backgrounds of most saturated and brightest colors. Regardless of the background colors viewed, the subjects preferred blue the most (p-value < 0.01). Findings of the study are also discussed with pertinent research on the field. Through this analysis, an understanding of foreground-background color relationships in terms of preference is sought.

Observing Flux Rope Formation During the Impulsive Phase of a Solar Eruption

NASA Astrophysics Data System (ADS)

Cheng, X.; Zhang, J.; Liu, Y.; Ding, M. D.

2011-05-01

Magnetic flux ropes are believed to be an important structural component of coronal mass ejections (CMEs). While there exists much observational evidence of flux ropes after the eruption, e.g., as seen in remote-sensing coronagraph images or in situ solar wind data, the direct observation of flux ropes during CME impulsive phase has been rare. In this Letter, we present an unambiguous observation of a flux rope still in the formation phase in the low corona. The CME of interest occurred above the east limb on 2010 November 3 with footpoints partially blocked. The flux rope was seen as a bright blob of hot plasma in the Atmospheric Imaging Assembly (AIA) 131 Å passband (peak temperature ~11 MK) rising from the core of the source active region, rapidly moving outward and stretching the surrounding background magnetic field upward. The stretched magnetic field seemed to curve-in behind the core, similar to the classical magnetic reconnection scenario in eruptive flares. On the other hand, the flux rope appeared as a dark cavity in the AIA 211 Å passband (2.0 MK) and 171 Å passband (0.6 MK) in these relatively cool temperature bands, a bright rim clearly enclosed the dark cavity. The bright rim likely represents the pileup of the surrounding coronal plasma compressed by the expanding flux rope. The composite structure seen in AIA multiple temperature bands is very similar to that in the corresponding coronagraph images, which consists of a bright leading edge and a dark cavity, commonly believed to be a flux rope.

In-situ Microwave Brightness Temperature Variability from Ground-based Radiometer Measurements at Dome C in Antarctica Induced by Wind-formed Features

NASA Technical Reports Server (NTRS)

Royer, A.; Picard, G.; Arnaud, L.; Brucker, L.; Fily, M..

2014-01-01

Space-borne microwave radiometers are among the most useful tools to study snow and to collect information on the Antarctic climate. They have several advantages over other remote sensing techniques: high sensitivity to snow properties of interest (temperature, grain size, density), subdaily coverage in the polar regions, and their observations are independent of cloud conditions and solar illumination. Thus, microwave radiometers are widely used to retrieve information over snow-covered regions. For the Antarctic Plateau, many studies presenting retrieval algorithms or numerical simulations have assumed, explicitly or not, that the subpixel-scale heterogeneity is negligible and that the retrieved properties were representative of whole pixels. In this presentation, we investigate the spatial variations of brightness temperature over arange of a few kilometers in the Dome C area (Antarctic Plateau).

Dust ion acoustic freak waves in a plasma with two temperature electrons featuring Tsallis distribution

NASA Astrophysics Data System (ADS)

Chahal, Balwinder Singh; Singh, Manpreet; Shalini; Saini, N. S.

2018-02-01

We present an investigation for the nonlinear dust ion acoustic wave modulation in a plasma composed of charged dust grains, two temperature (cold and hot) nonextensive electrons and ions. For this purpose, the multiscale reductive perturbation technique is used to obtain a nonlinear Schrödinger equation. The critical wave number, which indicates where the modulational instability sets in, has been determined precisely for various regimes. The influence of plasma background nonextensivity on the growth rate of modulational instability is discussed. The modulated wavepackets in the form of either bright or dark type envelope solitons may exist. Formation of rogue waves from bright envelope solitons is also discussed. The investigation indicates that the structural characteristics of these envelope excitations (width, amplitude) are significantly affected by nonextensivity, dust concentration, cold electron-ion density ratio and temperature ratio.

Percentage Contributions from Atmospheric and Surface Features to Computed Brightness Temperatures

NASA Technical Reports Server (NTRS)

Jackson, Gail Skofronick

2006-01-01

Over the past few years, there has become an increasing interest in the use of millimeter-wave (mm-wave) and sub-millimeter-wave (submm-wave) radiometer observations to investigate the properties of ice particles in clouds. Passive radiometric channels respond to both the integrated particle mass throughout the volume and field of view, and to the amount, location, and size distribution of the frozen (and liquid) particles with the sensitivity varying for different frequencies and hydrometeor types. One methodology used since the 1960's to discern the relationship between the physical state observed and the brightness temperature (TB) is through the temperature weighting function profile. In this research, the temperature weighting function concept is exploited to analyze the sensitivity of various characteristics of the cloud profile, such as relative humidity, ice water path, liquid water path, and surface emissivity. In our numerical analysis, we compute the contribution (in Kelvin) from each of these cloud and surface characteristics, so that the sum of these various parts equals the computed TB. Furthermore, the percentage contribution from each of these characteristics is assessed. There is some intermingling/contamination of the contributions from various components due to the integrated nature of passive observations and the absorption and scattering between the vertical layers, but all in all the knowledge gained is useful. This investigation probes the sensitivity over several cloud classifications, such as cirrus, blizzards, light snow, anvil clouds, and heavy rain. The focus is on mm-wave and submm-wave frequencies, however discussions of the effects of cloud variations to frequencies as low as 10 GHz and up to 874 GHz will also be presented. The results show that nearly 60% of the TB value at 89 GHz comes from the earth's surface for even the heaviest blizzard snow rates. On the other hand, a significant percentage of the TB value comes from the snow in the cloud for 166, and 183 plus or minus 7 GHz for the heavy and medium snow rates. For submm-wave channels, there is no contribution from the surface because these channels cannot probe through clouds, nor normal water vapor amounts in clear air regions. This work is extremely valuable in physically-based retrieval algorithm development research.

A case study on large-scale dynamical influence on bright band using cloud radar during the Indian summer monsoon

NASA Astrophysics Data System (ADS)

Jha, Ambuj K.; Kalapureddy, M. C. R.; Devisetty, Hari Krishna; Deshpande, Sachin M.; Pandithurai, G.

2018-02-01

The present study is a first of its kind attempt in exploring the physical features (e.g., height, width, intensity, duration) of tropical Indian bright band using a Ka-band cloud radar under the influence of large-scale cyclonic circulation and attempts to explain the abrupt changes in bright band features, viz., rise in the bright band height by 430 m and deepening of the bright band by about 300 m observed at around 14:00 UTC on Sep 14, 2016, synoptically as well as locally. The study extends the utility of cloud radar to understand how the bright band features are associated with light precipitation, ranging from 0 to 1.5 mm/h. Our analysis of the precipitation event of Sep 14-15, 2016 shows that the bright band above (below) 3.7 km, thickness less (more) than 300 m can potentially lead to light drizzle of 0-0.25 mm/h (drizzle/light rain) at the surface. It is also seen that the cloud radar may be suitable for bright band study within light drizzle limits than under higher rain conditions. Further, the study illustrates that the bright band features can be determined using the polarimetric capability of the cloud radar. It is shown that an LDR value of - 22 dB can be associated with the top height of bright band in the Ka-band observations which is useful in the extraction of the bright band top height and its width. This study is useful for understanding the bright band phenomenon and could be potentially useful in establishing the bright band-surface rain relationship through the perspective of a cloud radar, which would be helpful to enhance the cloud radar-based quantitative estimates of precipitation.

Passive Microwave Observation of Soil Water Infiltration

NASA Technical Reports Server (NTRS)

Jackson, Thomas J.; Schmugge, Thomas J.; Rawls, Walter J.; ONeill, Peggy E.; Parlange, Marc B.

1997-01-01

Infiltration is a time varying process of water entry into soil. Experiments were conducted here using truck based microwave radiometers to observe small plots during and following sprinkler irrigation. Experiments were conducted on a sandy loam soil in 1994 and a silt loam in 1995. Sandy loam soils typically have higher infiltration capabilities than clays. For the sandy loam the observed brightness temperature (TB) quickly reached a nominally constant value during irrigation. When the irrigation was stopped the TB began to increase as drainage took place. The irrigation rates in 1995 with the silt loam soil exceeded the saturated conductivity of the soil. During irrigation the TB values exhibited a pattern that suggests the occurrence of coherent reflection, a rarely observed phenomena under natural conditions. These results suggested the existence of a sharp dielectric boundary (wet over dry soil) that was increasing in depth with time.

Characterization of undulator radiation at the photon factory

NASA Astrophysics Data System (ADS)

Maezawa, Hideki; Suzuki, Yoshio; Kitamura, Hideo; Sasaki, Taizo

1986-05-01

Spectra of undulator radiation of the Photon Factory undulator, model PMU-2, were measured in a scale of absolute brightness in the soft X-ray region for various values of the K-parameter from 0.72 to 1.66. A significant reduction of the peak brightness was observed, whereas we also observed a relatively sharp edge at the high energy side of the first harmonic. The results show that the peak brightness and the band width are highly dependent on the beam parameters and the geometry of spectral observation.

An equivalent method of mixed dielectric constant in passive microwave/millimeter radiometric measurement

NASA Astrophysics Data System (ADS)

Su, Jinlong; Tian, Yan; Hu, Fei; Gui, Liangqi; Cheng, Yayun; Peng, Xiaohui

2017-10-01

Dielectric constant is an important role to describe the properties of matter. This paper proposes This paper proposes the concept of mixed dielectric constant(MDC) in passive microwave radiometric measurement. In addition, a MDC inversion method is come up, Ratio of Angle-Polarization Difference(RAPD) is utilized in this method. The MDC of several materials are investigated using RAPD. Brightness temperatures(TBs) which calculated by MDC and original dielectric constant are compared. Random errors are added to the simulation to test the robustness of the algorithm. Keywords: Passive detection, microwave/millimeter, radiometric measurement, ratio of angle-polarization difference (RAPD), mixed dielectric constant (MDC), brightness temperatures, remote sensing, target recognition.

Evaluation of sorghum flour functionality and quality characteristics of gluten-free bread and cake as influenced by ozone treatment.

PubMed

Marston, Kathryn; Khouryieh, Hanna; Aramouni, Fadi

2015-12-01

Commercially milled food-grade sorghum flour was subjected to ozone at the rate of 0.06 L/min for 15, 30, and 45 min. The pH of ozone-treated flour decreased as exposure time increased. The L* (lightness) values of sorghum flour significantly increased (p < 0.05), while the b* (yellowness) values significantly decreased as ozone exposure time increased. Peak viscosity significantly increased as time of ozonation increased from 0 to 45 min. Results showed that gluten-free cake volume significantly increased as ozonation time increased. Additionally, longer ozonation exposure times increased cells per slice area, lightness, and slice brightness values in gluten-free cakes while reducing crumb firmness. Despite improving lightness and slice brightness values, ozonation did not significantly increase the specific volume of gluten-free batter-based bread. While ozonation improved the volume and texture in cakes, it did not have the same positive effects on gluten-free bread. Bread made from ozonated sorghum flour had an open ragged structure with equivalent volume to the control flour. In both applications, the increased brightness and lightness values due to ozone exposure is recommended to increase the acceptability of sorghum products. © The Author(s) 2014.

Xenon gas field ion source from a single-atom tip

NASA Astrophysics Data System (ADS)

Lai, Wei-Chiao; Lin, Chun-Yueh; Chang, Wei-Tse; Li, Po-Chang; Fu, Tsu-Yi; Chang, Chia-Seng; Tsong, T. T.; Hwang, Ing-Shouh

2017-06-01

Focused ion beam (FIB) systems have become powerful diagnostic and modification tools for nanoscience and nanotechnology. Gas field ion sources (GFISs) built from atomic-size emitters offer the highest brightness among all ion sources and thus can improve the spatial resolution of FIB systems. Here we show that the Ir/W(111) single-atom tip (SAT) can emit high-brightness Xe+ ion beams with a high current stability. The ion emission current versus extraction voltage was analyzed from 150 K up to 309 K. The optimal emitter temperature for maximum Xe+ ion emission was ˜150 K and the reduced brightness at the Xe gas pressure of 1 × 10-4 torr is two to three orders of magnitude higher than that of a Ga liquid metal ion source, and four to five orders of magnitude higher than that of a Xe inductively coupled plasma ion source. Most surprisingly, the SAT emitter remained stable even when operated at 309 K. Even though the ion current decreased with increasing temperature, the current at room temperature (RT) could still reach over 1 pA when the gas pressure was higher than 1 × 10-3 torr, indicating the feasibility of RT-Xe-GFIS for application to FIB systems. The operation temperature of Xe-SAT-GFIS is considerably higher than the cryogenic temperature required for the helium ion microscope (HIM), which offers great technical advantages because only simple or no cooling schemes can be adopted. Thus, Xe-GFIS-FIB would be easy to implement and may become a powerful tool for nanoscale milling and secondary ion mass spectroscopy.

Detecting the brightness temperature from Landsat-8 thermal infra red scanner preceding the Rinjani strombolian eruption 2015

NASA Astrophysics Data System (ADS)

Suwarsono, Hidayat, Suprapto, Totok; Prasasti, Indah; Parwati, Rokhis Khomarudin, M.

2017-07-01

At the end of October to early November 2015, Rinjani Volcano that is located in Lombok Island was erupted and has catapulted the ash, pyroclastic and lava flow. The dispersion of this volcanic ash in the atmosphere has been disrupting flights and the three closest airports to be closed for a while. The existence of Rinjani Volcano geographically plays an important role in the survival of life on the island of Lombok, because large areas of land on the island are a part of the Rinjani Volcano landscape. Based on the experience of violent eruptions that have occurred in the 13th century ago, the monitoring of the volcanism activity of this volcano needs to be done intensively and continuously. This is something important to do an early detection efforts of the volcanic eruption. These efforts need to be done as a preparedness effort in order to minimize adverse impacts that may occur as a result of this eruption. This research tries to detect the volcanic eruption precursor based on changes in temperature conditions of the crater and the surrounding area. We use the medium resolution satellite data, Thermal Infra Red Scanner (TIRS), on board Landsat-8, to monitor the brightness temperature as a representative of surface temperature of the volcanic region. The results showed that the brightness temperature derived from Landsat-8 TIRS is very usefull to predict the strombolian eruption which will occur in the near future. The use of multitemporal image data is important to understand the dynamics of volcanism activity over time.

Color constancy using bright-neutral pixels

NASA Astrophysics Data System (ADS)

Wang, Yanfang; Luo, Yupin

2014-03-01

An effective illuminant-estimation approach for color constancy is proposed. Bright and near-neutral pixels are selected to jointly represent the illuminant color and utilized for illuminant estimation. To assess the representing capability of pixels, bright-neutral strength (BNS) is proposed by combining pixel chroma and brightness. Accordingly, a certain percentage of pixels with the largest BNS is selected to be the representative set. For every input image, a proper percentage value is determined via an iterative strategy by seeking the optimal color-corrected image. To compare various color-corrected images of an input image, image color-cast degree (ICCD) is devised using means and standard deviations of RGB channels. Experimental evaluation on standard real-world datasets validates the effectiveness of the proposed approach.

Use of the variable gain settings on SPOT

USGS Publications Warehouse

Chavez, P.S.

1989-01-01

Often the brightness or digital number (DN) range of satellite image data is less than optimal and uses only a portion of the available values (0 to 255) because the range of reflectance values is small. Most imaging systems have been designed with only two gain settings, normal and high. The SPOT High Resolution Visible (HRV) imaging system has the capability to collect image data using one of eight different gain settings. With the proper procedure this allows the brightness or reflectance resolution, which is directly related to the range of DN values recorded, to be optimized for any given site as compared to using a single set of gain settings everywhere. -from Author

Radio Thermal Emission from Pluto and Charon during the New Horizons Encounter

NASA Astrophysics Data System (ADS)

Bird, Michael; Linscott, Ivan; Hinson, David; Tyler, G. L.; Strobel, Darrell F.; New Horizons Science Team

2017-10-01

As part of the New Horizons Radio-Science Experiment REX, radio thermal emission from Pluto and Charon (wavelength: 4.2 cm) was observed during the encounter on 14 July 2015. The primary REX measurement, a determination of the atmospheric height profile from the surface up to about 100 km, was conducted during an uplink radio occultation at both ingress and egress (Hinson et al., Icarus 290, 96-111, 2017). During the interval between ingress and egress, when the Earth and the REX uplink signals were occulted by the Pluto disk, the spacecraft antenna continued to point toward Earth and thus scanned diametrically across the Pluto nightside. The average diameter of the HGA 3 dB beam was ≈1100 km at the surface during this opportunity, thereby providing crudely resolved measurements of the radio brightness temperature across Pluto. The best resolution for the REX radiometry observations occurred shortly after closest approach, when the HGA was scanned twice across Pluto. These observations will be reported elsewhere (Linscott et al., Icarus, submitted, 2017). In addition to the resolved observations, full disk brightness temperature measurements of both bodies were performed during the approach (dayside) and departure (nightside) phases of the encounter. We present the results of these observations and provide a preliminary interpretation of the measured brightness temperatures.

'Electrically-Hot' Convection and Tropical Cyclone Development in the Eastern Atlantic

NASA Technical Reports Server (NTRS)

Leppert, Kenneth, II; Petersen, Walter A.; Williams, Earle

2008-01-01

The depth and intensity of convective-scale "hot" towers in intensifying tropical disturbances has been hypothesized to play a role in tropical cyclogenesis via dynamic and thermodynamic feedbacks on the larger meso-to-synoptic scale circulation. In this investigation we investigate the role that widespread and/or intense lightning-producing convection (i.e., "electrically-hot towers") resident in African Easterly Waves (AEW) may play in tropical cyclogenesis over the eastern Atlantic Ocean. NCEP reanalysis data for the months of July to November for the years 2004, 2006, and 2007 are analyzed for the domain of 5 N - 15 N and 500W - 300 E. Specifically, NCEP data for individual AEWs are partitioned into northerly, southerly, trough, and ridge phases using the 700 hPa meridional winds. Subsequently, information from National Hurricane Center storm reports were divided up into developing and non-developing waves (i.e. tropical cyclogenesis). Finally, composites were created of developing and non-developing waves using the NCEP variables, but with the inclusion of lightning flash count and infrared brightness temperature information. The Zeus and World Wide Lightning Location Network lightning data were used for the lightning information, and the IR brightness temperature data was extracted from the NASA global-merged infrared brightness temperature dataset.

Estimation of wind speeds inside Super Typhoon Nepartak from AMSR2 low-frequency brightness temperatures

NASA Astrophysics Data System (ADS)

Zhang, Lei; Yin, Xiaobin; Shi, Hanqing; Wang, Zhenzhan; Xu, Qing

2018-04-01

Accurate estimations of typhoon-level winds are highly desired over the western Pacific Ocean. A wind speed retrieval algorithm is used to retrieve the wind speeds within Super Typhoon Nepartak (2016) using 6.9- and 10.7-GHz brightness temperatures from the Japanese Advanced Microwave Scanning Radiometer 2 (AMSR2) sensor on board the Global Change Observation Mission-Water 1 (GCOM-W1) satellite. The results show that the retrieved wind speeds clearly represent the intensification process of Super Typhoon Nepartak. A good agreement is found between the retrieved wind speeds and the Soil Moisture Active Passive wind speed product. The mean bias is 0.51 m/s, and the root-mean-square difference is 1.93 m/s between them. The retrieved maximum wind speeds are 59.6 m/s at 04:45 UTC on July 6 and 71.3 m/s at 16:58 UTC on July 6. The two results demonstrate good agreement with the results reported by the China Meteorological Administration and the Joint Typhoon Warning Center. In addition, Feng-Yun 2G (FY-2G) satellite infrared images, Feng-Yun 3C (FY-3C) microwave atmospheric sounder data, and AMSR2 brightness temperature images are also used to describe the development and structure of Super Typhoon Nepartak.

Data Quality Assessment of FY-3C MWRI Microwave Imager from CMA, ECMWF and the Met Office

NASA Astrophysics Data System (ADS)

Lu, Q.; WU, S.; Dou, F.; Sun, F.; Lawrence, H.; Geer, A.; English, S.; Newman, S.; Bell, W.; Bormann, N.; Carminati, F.

2017-12-01

MWRI is a conical-scanning microwave imager following on from the heritage of similar instruments such as SSMI/S and AMSR-2, with ten channels at frequencies between 10.65 GHz and 89 GHz. MWRI is flown on the China Meteorological Administration's (CMA's) Feng-Yun-3 (FY-3) satellite series, including on FY-3C and the upcoming FY-3D, scheduled for launch in September 2017. Here we present an evaluation of the data from MWRI on the FY-3C satellite launched in 2013. At CMA, the MWRI instrumental parameters and statistics between observation and simulation from RTTOV and CRTM radiative transfer modeling were monitored to characterise instrumental uncertainty from calibration and assess the data quality. The data were also assessed using model-equivalent brightness temperatures from the ECMWF and Met Office short-range forecasts. The forecasts were first transformed into brightness temperature space using the RTTOV radiative transfer code. By analysing observed minus model background ("O-B") brightness temperature departures we were able to investigate the instrument and geophysical state dependence of biases. We show examples of how biases can impact the data quality, related to ascending/descending node differences and radio frequency interference. We discuss the prospects of assimilation of MWRI data at NWP centres.

Microwave emission characteristics of sea ice

NASA Technical Reports Server (NTRS)

Edgerton, A. T.; Poe, G.

1972-01-01

A general classification is presented for sea ice brightness temperatures with categories of high and low emission, corresponding to young and weathered sea ice, respectively. A sea ice emission model was developed which allows variations of ice salinity and temperature in directions perpendicular to the ice surface.

Simultaneous Luminescence Pressure and Temperature Mapping

NASA Technical Reports Server (NTRS)

Buck, Gregory M. (Inventor)

1998-01-01

A simultaneous luminescence pressure and temperature mapping system is developed including improved dye application techniques for surface temperature and pressure measurements from 5 torr to 1000 torr with possible upgrade to from 0.5 torr to several atmospheres with improved camera resolution. Adsorbed perylene dye on slip-cast silica is pressure (oxygen) sensitive and reusable to relatively high temperatures (-150 C). Adsorbed luminescence has an approximately linear color shift with temperature, which can be used for independent temperature mapping and brightness pressure calibration with temperature.

Simultaneous Luminescence Pressure and Temperature Mapping System

NASA Technical Reports Server (NTRS)

Buck, Gregory M. (Inventor)

1995-01-01

A simultaneous luminescence pressure and temperature mapping system is developed including improved dye application techniques for surface temperature and pressure measurements from 5 torr to 1000 torr with possible upgrade to from 0.5 torr to several atmospheres with improved camera resolution. Adsorbed perylene dye on slip-cast silica is pressure (oxygen) sensitive and reusable to relatively high temperatures (approximately 150 C). Adsorbed luminescence has an approximately linear color shift with temperature, which can be used for independent temperature mapping and brightness pressure calibration with temperature.

OH as an Alternate Tracer for Molecular Gas: Excitation Temperatures of the OH 18 cm Main Lines in W5

NASA Astrophysics Data System (ADS)

Engelke, Philip D.; Allen, Ronald J.

2018-05-01

We present excitation temperatures T ex for the OH 18 cm main lines at 1665 and 1667 MHz measured directly in front of the W5 star-forming region, using observations from the Green Bank Telescope and the Very Large Array. We find unequivocally that T ex at 1665 MHz is greater than T ex at 1667 MHz. Our method exploits variations in the continuum emission from W5, and the fact that the continuum brightness temperatures T C in this nebula are close to the excitation temperatures of the OH lines in the foreground gas. The result is that an OH line can appear in emission in one location and in absorption in a neighboring location, and the value of T C where the profiles switch from emission to absorption indicates T ex. Absolute measurements of T ex for the main lines were subject to greater uncertainty because of unknown effects of geometry of the OH features. We also employed the traditional “expected profile” method for comparison with our “continuum background” method and found that the continuum background method provided more precise results and was the one to definitively show the T ex difference. Our best estimate values are {T}ex}65=6.0+/- 0.5 K, {T}ex}67=5.1+/- 0.2 K, and {T}ex}65-{T}ex}67=0.9+/- 0.5 K. The T ex values we have measured for the ISM in front of W5 are similar to those found in the quiescent ISM, indicating that proximity to massive star-forming regions does not generally result in widespread anomalous excitation of OH emission.

Performance and Results from a Space Borne, Uncooled Microbolometer Array Spectral Radiometric Imager

NASA Technical Reports Server (NTRS)

Spinhirne, James M; Scott, V. Stan; Lancaster, Redgie S.; Manizade, Kathrine; Palm, Steven P.

2000-01-01

The Infrared Spectral Imaging Radiometer experiment was flown on a space shuttle mission as a shuttle hitchhiker experiment in August of 1997. The goals of the experiment were to test uncooled array detectors for infrared spectral imaging from space and to apply for the first time retrieval from space of brightness temperatures of cloud, land and sea along with direct laser measurements of cloud top height. The instrument operates in 3 narrow and one broad spectral band, all between 7 and 13 microns in either stare or time-delay and integration mode. The nominal spatial resolution was 1/4 kilometer. Using onboard calibrations along with periodic views of deep space, radiometric calibration of imagery was carried out and performance analyzed. The noise equivalent temperature difference and absolute accuracy reported here varied with operating mode, spectral band and scene temperature but were within requirements. This paper provides a description of the instrument, its operating modes, the method of brightness temperature retrieval, the method of spectral registration and results from the flight.

Comparison of Local Scale Measured and Modeled Brightness Temperatures and Snow Parameters from the CLPX 2003 by Means of a Dense Medium Radiative Transfer Theory Model

NASA Technical Reports Server (NTRS)

Tedescol, Marco; Kim, Edward J.; Cline, Don; Graf, Tobias; Koike, Toshio; Armstrong, Richard; Brodzik, Mary J.; Hardy, Janet

2004-01-01

Microwave remote sensing offers distinct advantages for observing the cryosphere. Solar illumination is not required, and spatial and temporal coverage are excellent from polar-orbiting satellites. Passive microwave measurements are sensitive to the two most useful physical quantities for many hydrological applications: physical temperature and water content/state. Sensitivity to the latter is a direct result of the microwave sensitivity to the dielectric properties of natural media, including snow, ice, soil (frozen or thawed), and vegetation. These considerations are factors motivating the development of future cryospheric satellite remote sensing missions, continuing and improving on a 26-year microwave measurement legacy. Perhaps the biggest issues regarding the use of such satellite measurements involve how to relate parameter values at spatial scales as small as a hectare to observations with sensor footprints that may be up to 25 x 25 km. The NASA Cold-land Processes Field Experiment (CLPX) generated a dataset designed to enhance understanding of such scaling issues. CLPX observations were made in February (dry snow) and March (wet snow), 2003 in Colorado, USA, at scales ranging from plot scale to 25 x 25 km satellite footprints. Of interest here are passive microwave observations from ground-based, airborne, and satellite sensors, as well as meteorological and snowpack measurements that will enable studies of the effects of spatial heterogeneity of surface conditions on the observations. Prior to performing such scaling studies, an evaluation of snowpack forward modelling at the plot scale (least heterogeneous scale) is in order. This is the focus of this paper. Many forward models of snow signatures (brightness temperatures) have been developed over the years. It is now recognized that a dense medium radiative transfer (DMRT) treatment represents a high degree of physical fidelity for snow modeling, yet dense medium models are particularly sensitive to snowpack structural parameters such as grain size, density, and depth---parameters that may vary substantially within a snowpack. Microwave radiometric data and snow pit measurements collected at the Local-Scale Observation Site (LSOS) during the third Intensive Observation Period (IOP3) of the CLPX have been used to test the capabilities of a DMRT model using the Quasi Crystalline Approximation with Coherent Potential (QCA-CP). The radiometric measurements were made by the University of Tokyo s Ground Based Microwave Radiometer-7 (GBMR-7) system. We evaluate the degree to which a DMRT-based model can accurately reproduce the GBMR-7 brightness temperatures at different frequencies and incidence angles.

On the Response of the Special Sensor Microwave/Imager to the Marine Environment: Implications for Atmospheric Parameter Retrievals. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Petty, Grant W.

1990-01-01

A reasonably rigorous basis for understanding and extracting the physical information content of Special Sensor Microwave/Imager (SSM/I) satellite images of the marine environment is provided. To this end, a comprehensive algebraic parameterization is developed for the response of the SSM/I to a set of nine atmospheric and ocean surface parameters. The brightness temperature model includes a closed-form approximation to microwave radiative transfer in a non-scattering atmosphere and fitted models for surface emission and scattering based on geometric optics calculations for the roughened sea surface. The combined model is empirically tuned using suitable sets of SSM/I data and coincident surface observations. The brightness temperature model is then used to examine the sensitivity of the SSM/I to realistic variations in the scene being observed and to evaluate the theoretical maximum precision of global SSM/I retrievals of integrated water vapor, integrated cloud liquid water, and surface wind speed. A general minimum-variance method for optimally retrieving geophysical parameters from multichannel brightness temperature measurements is outlined, and several global statistical constraints of the type required by this method are computed. Finally, a unified set of efficient statistical and semi-physical algorithms is presented for obtaining fields of surface wind speed, integrated water vapor, cloud liquid water, and precipitation from SSM/I brightness temperature data. Features include: a semi-physical method for retrieving integrated cloud liquid water at 15 km resolution and with rms errors as small as approximately 0.02 kg/sq m; a 3-channel statistical algorithm for integrated water vapor which was constructed so as to have improved linear response to water vapor and reduced sensitivity to precipitation; and two complementary indices of precipitation activity (based on 37 GHz attenuation and 85 GHz scattering, respectively), each of which are relatively insensitive to variations in other environmental parameters.

Passive Microwave Remote Sensing of Colorado Watersheds Using Calibrated, Enhanced-Resolution Brightness Temperatures (CETB) from AMSR-E and SSM/I for Estimation of Snowmelt Timing

NASA Astrophysics Data System (ADS)

Johnson, M.; Ramage, J. M.; Troy, T. J.; Brodzik, M. J.

2017-12-01

Understanding the timing of snowmelt is critical for water resources management in snow-dominated watersheds. Passive microwave remote sensing has been used to estimate melt-refreeze events through brightness temperature satellite observations taken with sensors like the Special Sensor Microwave Imager (SSM/I) and the Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E). Previous studies were limited to lower resolution ( 25 km) datasets, making it difficult to quantify the snowpack in heterogeneous, high-relief areas. This study investigates the use of newly available passive microwave calibrated, enhanced-resolution brightness temperatures (CETB) produced at the National Snow and Ice Data Center to estimate melt timing at much higher spatial resolution ( 3-6 km). CETB datasets generated from SSM/I and AMSR-E records will be used to examine three mountainous basins in Colorado. The CETB datasets retain twice-daily (day/night) observations of brightness temperatures. Therefore, we employ the diurnal amplitude variation (DAV) method to detect melt onset and melt occurrences to determine if algorithms developed for legacy data are valid with the improved CETB dataset. We compare melt variability with nearby stream discharge records to determine an optimum melt onset algorithm using the newly reprocessed data. This study investigates the effectiveness of the CETB product for several locations in Colorado (North Park, Rabbit Ears, Fraser) that were the sites of previous ground/airborne surveys during the NASA Cold Land Processes Field Experiment (CLPX 2002-2003). In summary, this work lays the foundation for the utilization of higher resolution reprocessed CETB data for snow evolution more broadly in a range of environments. Consequently, the new processing methods and improved spatial resolution will enable hydrologists to better analyze trends in snow-dominated mountainous watersheds for more effective water resources management.

Mapping Solid and Liquid Meltwater Retention on the Greenland and Antarctic Ice Sheets from Space

NASA Astrophysics Data System (ADS)

Miller, J.; Bringer, A.; Jezek, K. C.; Johnson, J. T.; Scambos, T.; Forster, R. R.; Long, D. G.

2017-12-01

We use satellite and airborne microwave radiometry to explore the potential for mapping both solid (infiltration ice) and liquid (firn aquifers) meltwater retention on ice sheets. Meltwater retention in firn is currently poorly understood, especially on an ice sheet-scale, however, critical to understanding the ultimate fate of liquid meltwater produced at the surface of ice sheets. Is it contributing to sea level? Or, is it being buffered prior to escaping into the ocean? We previously developed a simple satellite retrieval technique to map firn aquifers on the Greenland ice sheet using distinct L-band brightness temperature signatures that decrease on timescales of months following surface freeze-up, however, similar L-band brightness temperature signatures that decrease on timescales ranging from weeks to days are also present throughout the percolation facies of both the Greenland and Antarctic ice sheets. We hypothesize this characteristic family of temporal signatures represents meltwater retention within firn, where slowly decreasing signatures are characteristic of meltwater retention within perennial firn aquifers, and rapidly decreasing signatures are characteristic of meltwater retention as superimposed ice. Decreasing signatures on timescales between likely represent a continuum of firn characteristics, such as transient firn aquifers, perched firn aquifers, ice layers, ice pipes and lenses, and iced firn. To investigate these temporal signatures, we use L-band (1.4 GHz) brightness temperature observations collected over the Greenland and Antarctic ice sheets by the interferometric MIRAS instrument aboard ESA's Soil Moisture and Ocean Salinity (SMOS) satellite, and the radiometer aboard NASA's Soil Moisture Active Passive (SMAP) satellite. We will also investigate spectral signatures using multi-frequency L-band brightness temperature data (0.5-2 GHz) to be collected over several firn aquifer areas on the Greenland ice sheet by the Ohio State University developed Ultra-Wideband Software-Defined Microwave Radiometer (UWBRAD) as part of our airborne field campaign to be conducted in September 2017.

Enchanced methods of hydrophilized CdSe quantum dots synthesis

NASA Astrophysics Data System (ADS)

Potapkin, D. V.; Zharkova, I. S.; Goryacheva, I. Y.

2015-03-01

Quantum dots are bright and stable fluorescence signal sources, but for most of applications they need an additional hydrophilization step. Unfortunately, most of existing approaches lead to QD's fluorescence quenching, so there is a need for additional enhancing of hydrophilized QD's brightness like UV irradiation, which can be used both on water insoluble QD's with oleic acid ligands (in toluene) and on hydrophilized QD's covered with UV-stable polymer (in aqueous solution). For synthesis of bright water-soluble fluorescent labels CdSe/CdS/ZnS colloidal quantum dots were covered with PAMAM dendrimer and irradiated with UV lamp in quartz cuvettes for 3 hours at the room temperature and then compared with control sample.

Ultra-bright emission from hexagonal boron nitride defects as a new platform for bio-imaging and bio-labelling

NASA Astrophysics Data System (ADS)

Elbadawi, Christopher; Tran, Trong Toan; Shimoni, Olga; Totonjian, Daniel; Lobo, Charlene J.; Grosso, Gabriele; Moon, Hyowan; Englund, Dirk R.; Ford, Michael J.; Aharonovich, Igor; Toth, Milos

2016-12-01

Bio-imaging requires robust ultra-bright probes without causing any toxicity to the cellular environment, maintain their stability and are chemically inert. In this work we present hexagonal boron nitride (hBN) nanoflakes which exhibit narrowband ultra-bright single photon emitters1. The emitters are optically stable at room temperature and under ambient environment. hBN has also been noted to be noncytotoxic and seen significant advances in functionalization with biomolecules2,3. We further demonstrate two methods of engineering this new range of extremely robust multicolour emitters across the visible and near infrared spectral ranges for large scale sensing and biolabeling applications.

Kinematics of Parsec-scale Jets of Gamma-Ray Blazars at 43 GHz within the VLBA-BU-BLAZAR Program

NASA Astrophysics Data System (ADS)

Jorstad, Svetlana G.; Marscher, Alan P.; Morozova, Daria A.; Troitsky, Ivan S.; Agudo, Iván; Casadio, Carolina; Foord, Adi; Gómez, José L.; MacDonald, Nicholas R.; Molina, Sol N.; Lähteenmäki, Anne; Tammi, Joni; Tornikoski, Merja

2017-09-01

We analyze the parsec-scale jet kinematics from 2007 June to 2013 January of a sample of γ-ray bright blazars monitored roughly monthly with the Very Long Baseline Array at 43 GHz. In a total of 1929 images, we measure apparent speeds of 252 emission knots in 21 quasars, 12 BL Lacertae objects (BLLacs), and 3 radio galaxies, ranging from 0.02c to 78c; 21% of the knots are quasi-stationary. Approximately one-third of the moving knots execute non-ballistic motions, with the quasars exhibiting acceleration along the jet within 5 pc (projected) of the core, and knots in BLLacs tending to decelerate near the core. Using the apparent speeds of the components and the timescales of variability from their light curves, we derive the physical parameters of 120 superluminal knots, including variability Doppler factors, Lorentz factors, and viewing angles. We estimate the half-opening angle of each jet based on the projected opening angle and scatter of intrinsic viewing angles of knots. We determine characteristic values of the physical parameters for each jet and active galactic nucleus class based on the range of values obtained for individual features. We calculate the intrinsic brightness temperatures of the cores, {T}{{b},{int}}{core}, at all epochs, finding that the radio galaxies usually maintain equipartition conditions in the cores, while ˜30% of {T}{{b},{int}}{core} measurements in the quasars and BLLacs deviate from equipartition values by a factor >10. This probably occurs during transient events connected with active states. In the Appendix, we briefly describe the behavior of each blazar during the period analyzed.

Integral field spectroscopy of selected areas of the Bright bar and Orion-S cloud in the Orion nebula

NASA Astrophysics Data System (ADS)

Mesa-Delgado, A.; Núñez-Díaz, M.; Esteban, C.; López-Martín, L.; García-Rojas, J.

2011-10-01

We present integral field spectroscopy of two selected zones in the Orion nebula obtained with the Potsdam Multi-Aperture Spectrophotometer, covering the optical spectral range from 3500 to 7200 Å and with a spatial resolution of 1 arcsec. The observed zones are located on the prominent Bright bar and on the brightest area at the north-east of the Orion south cloud, both containing remarkable ionization fronts. We obtain maps of emission-line fluxes and ratios, electron density and temperatures, and chemical abundances. We study the ionization structure and morphology of both fields, whose ionization fronts show different inclination angles with respect to the plane of the sky. We find that the maps of electron density, O+/H+ and O/H ratios show a rather similar structure. We interpret this as produced by the strong dependence on density of the [O II] lines used to derive the O+ abundance, and that our nominal values of electron density - derived from the [S II] line ratio - may be slightly higher than the appropriate value for the O+ zone. We measure the faint recombination lines of O II in the field at the north-east of the Orion south cloud, allowing us to explore the so-called abundance discrepancy problem. We find a rather constant abundance discrepancy across the field and a mean value similar to that determined in other areas of the Orion nebula, indicating that the particular physical conditions of this ionization front do not contribute to this discrepancy. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC).

Fluorescence properties of 6-aryl-2‧-deoxy-furanouridine and -pyrrolocytidine and their derivatives

NASA Astrophysics Data System (ADS)

Ro, Jong Jin; Go, Gui Han; Wilhelmsson, L. Marcus; Hyean Kim, Byeang

2018-01-01

2‧-deoxyfuranouridine derivatives presenting various aryl groups have been synthesized through Cu(I)-catalyzed intramolecular cyclizations. Moreover, corresponding pyrrolo-dC derivatives have been synthesized and both families of compounds thoroughly characterized using UV/vis and fluorescence spectroscopy as well as time-dependent density functional theory calculations. The photophysical characterization, show that our newly synthesized derivatives of the important pyrrolo-dC family have high fluorescence quantum yields (QYs) and brightness values. Pyrrolo-dC derivative, 3a, shows an environment sensitive QY of up to >60% and brightness of almost 3000, in low polarity solvents and excitation and emission maxima between 365-381 nm and 479-510 nm, respectively, in solvents of different polarities. Two other derivatives, 3b and 3c, show high QYs and brightness values of up to 3300 that are fairly insensitive to their microenvironment. These promising photophysical features suggest future applicability as fluorescent nucleobase analogs.

Color and temperature of the crater lakes at Kelimutu volcano through time

NASA Astrophysics Data System (ADS)

Murphy, Sam; Wright, Robert; Rouwet, Dmitri

2018-01-01

We investigated the color and temperature of three volcanic crater lakes that co-exist at Kelimutu volcano (Indonesia) using 30 years of Landsat data. These satellite data were obtained through Google Earth Engine. Time series of surface reflectance (visible wavelengths) and brightness temperature above background (thermal infrared wavelengths) were calculated. Color was defined in the RGB (red-green-blue) and HSV (hue-saturation-value) color spaces, and we introduce a visualization concept called "hue stretch" to consistently represent hue through time. These parameters display long-term trends, seasonal cycles and short duration bursts of activity at the lakes. We demonstrate that the color of the lakes are related over a period of months to years and discovered a previously unreported but significant episode around 1997, which included large agglomerations of floating elemental sulfur. Globally speaking, these techniques could reveal trends at any of the 100 crater lakes on active volcanoes. Furthermore, they could apply to any target whose color changes through time (e.g., forests, crops, and non-volcanic water bodies). We have open-sourced the code necessary to perform these analyses.

The Atacama Cosmology Telescope: Beam Measurements and the Microwave Brightness Temperatures of Uranus and Saturn

NASA Technical Reports Server (NTRS)

Hasselfield, Matthew; Moodley, Kavilan; Bond, J. Richard; Das, Sudeep; Devlin, Mark J.; Dunkley, Joanna; Dunner, Rolando; Fowler, Joseph W.; Gallardo, Patricio; Gralla, Megan B.;

A multisensor analysis of Nimbus-5 data recorded on 22 January 1973. [measurement of rainfall rates for east coast of the United States

NASA Technical Reports Server (NTRS)

Allison, L. J.; Rodgers, E. B.; Wilheit, T. T.; Wexler, R.

1975-01-01

The Nimbus 5 meteorological satellite has a full complement of radiation sensors. Data from these sensors were analyzed and intercompared for orbits 569 and 570. The electrically-scanning microwave radiometer (19.35-GHz region) delineated rain areas over the ocean off the U.S. east coast, in good agreement with radar imagery, and permitted the estimation of rainfall rates in this region. Residual ground water, from abnormal rainfall in the lower Mississippi Valley, was indicated under clear sky conditions by soil brightness temperature values in the Nimbus 5 electrically scanning microwave radiometer and U.S. Air Force Data Acquisition and Processing Program infrared data. The temperature-humidity infrared radiometer (6.7 micron and 11 micron) showed the height and spatial configuration of frontal clouds along the east coast and outlined the confluence of a polar jet stream with a broad subtropical jet stream along the U.S. Gulf Coast. Temperature profiles from three vertical temperature sounders are found to be in good agreement with related radiosonde ascents along orbit 569 from the subtropics to the Arctic Circle.

Prediction of the thermal imaging minimum resolvable (circle) temperature difference with neural network application.

PubMed

Fang, Yi-Chin; Wu, Bo-Wen

2008-12-01

Thermal imaging is an important technology in both national defense and the private sector. An advantage of thermal imaging is its ability to be deployed while fully engaged in duties, not limited by weather or the brightness of indoor or outdoor conditions. However, in an outdoor environment, many factors, including atmospheric decay, target shape, great distance, fog, temperature out of range and diffraction limits can lead to bad image formation, which directly affects the accuracy of object recognition. The visual characteristics of the human eye mean that it has a much better capacity for picture recognition under normal conditions than artificial intelligence does. However, conditions of interference significantly reduce this capacity for picture recognition for instance, fatigue impairs human eyesight. Hence, psychological and physiological factors can affect the result when the human eye is adopted to measure MRTD (minimum resolvable temperature difference) and MRCTD (minimum resolvable circle temperature difference). This study explores thermal imaging recognition, and presents a method for effectively choosing the characteristic values and processing the images fully. Neural network technology is successfully applied to recognize thermal imaging and predict MRTD and MRCTD (Appendix A), exceeding thermal imaging recognition under fatigue and the limits of the human eye.

Passive microwave mapping of ice thickness. Final Report. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Apinis, J. J.; Peake, W. H.

1976-01-01

Basic calculations are presented for evaluating the feasibility of a scanning microwave radiometer system for mapping the thickness of lake ice. An analytical model for the apparent brightness temperature as a function of ice thickness has been developed, and elaborated to include such variables as galactic and atmospheric noise, aspect angle, polarization, temperature gradient in the ice, the presence of transition layers such as snow, slush, and water, increased loss due to air inclusions in the ice layer, and the presence of multiple ice thicknesses within the antenna footprint. It was found that brightness temperature measurements at six or seven frequencies in the range of 0.4 to 0.7 GHz were required to obtain unambiquous thickness estimates. A number of data processing methods were examined. The effects of antenna beamwidth, scanning rate, receiver bandwidth, noise figure, and integration time were studied.

Application and sensitivity investigation of Fourier transforms for microwave radiometric inversions

NASA Technical Reports Server (NTRS)

Holmes, J. J.; Balanis, C. A.

1974-01-01

Existing microwave radiometer technology now provides a suitable method for remote determination of the ocean surface's absolute brightness temperature. To extract the brightness temperature of the water from the antenna temperature equation, an unstable Fredholm integral equation of the first kind was solved. Fast Fourier Transform techniques were used to invert the integral after it is placed into a cross-correlation form. Application and verification of the methods to a two-dimensional modeling of a laboratory wave tank system were included. The instability of the Fredholm equation was then demonstrated and a restoration procedure was included which smooths the resulting oscillations. With the recent availability and advances of Fast Fourier Transform techniques, the method presented becomes very attractive in the evaluation of large quantities of data. Actual radiometric measurements of sea water are inverted using the restoration method, incorporating the advantages of the Fast Fourier Transform algorithm for computations.

Identification and Classification of Transient Signatures in Over-Land SSM/I Imagery

NASA Technical Reports Server (NTRS)

Petty, Grant W.; Conner, Mark D.

1994-01-01

Two distinct yet related factors make it difficult to reliably detect precipitation over land with passive microwave techniques, such as those developed during recent years for the Special Sensor Microwave/Imager (SSM/I). The first factor is the general lack of contrast between radiances from the strongly emitting land background and that from a non-scattering atmosphere. Indeed. for certain common combinations of surface emissivity and temperature (both surface and atmospheric), significant changes in atmospheric opacity due to liquid water may have a negligible effect on satellite observed brightness temperatures. and whatever minor change occurs may be of either positive or negative sign. For this reason it is generally necessary for some degree of volume scattering by precipitation-size ice particles to be present in order to reduce the brightness temperature of the atmosphere relative to the warm background. by which process the precipitation may be observed.

PIG (partially ionized globule) anatomy - Density and temperature structure of the bright-rimmed globule IC 1396E

NASA Technical Reports Server (NTRS)

Serabyn, E.; Guesten, R.; Mundy, L.

1993-01-01

The density and temperature structure of the bright-rimmed cometary globule IC 1396E is estimated, and the possibility that recent internal star formation was triggered by the ionization front in its southern surface is assessed. On the basis of NH3 data, gas temperatures in the globule are found to increase outward from the center, from a minimum of 17 K in its tail to a maximum of 26 K on the surface most directly facing the stars ionizing IC 1396. On the basis of a microturbulent radiative transfer code to model the radial dependence of the CS line intensities, and also the intensities of the optically thin 2-1 and 5-4 lines toward the cloud center, a radial density dependence of r exp -1.55 to r exp -1.75 is found.

The use of stereoscopic satellite observation in the determination of the emissivity of cirrus

NASA Astrophysics Data System (ADS)

Szejwach, G.; Sletten, T. N.; Hasler, A. F.

The feasibility of determining cirrus ``emissivity'' from combined stereoscopic and infrared satellite observations in conjunction with radiosounding data is investigated for a particular case study. Simultaneous visible images obtained during SESAME-1979 from two geosynchronous GOES meteorological satellites were processed on the NASA/Goddard interactive system (AOIPS) and were used to determine the stereo cloud top height ZC as described by Hasler [1]. Iso-contours of radiances were outlined on the corresponding infrared image. Total brightness temperature TB and ground surface brightness temperature TS were inferred from the radiances. The special SESAME network of radiosoundings was used to determine the cloud top temperature TCLD at the level defined by ZC. The ``effective cirrus emissivity'' NE where N is the fractional cirrus cloudiness and E is the emissivity in a GOES infrared picture element of about 10 km × 10 km is then computed from TB, TS and TCLD.

Cloud top structure of Venus revealed by Subaru/COMICS mid-infrared images

NASA Astrophysics Data System (ADS)

Sato, T. M.; Sagawa, H.; Kouyama, T.; Mitsuyama, K.; Satoh, T.; Ohtsuki, S.; Ueno, M.; Kasaba, Y.; Nakamura, M.; Imamura, T.

2014-11-01

We have investigated the cloud top structure of Venus by analyzing ground-based images taken at the mid-infrared wavelengths of 8.66 μm and 11.34 μm. Venus at a solar phase angle of ∼90°, with the morning terminator in view, was observed by the Cooled Mid-Infrared Camera and Spectrometer (COMICS), mounted on the 8.2-m Subaru Telescope, during the period October 25-29, 2007. The disk-averaged brightness temperatures for the observation period are ∼230 K and ∼238 K at 8.66 μm and 11.34 μm, respectively. The obtained images with good signal-to-noise ratio and with high spatial resolution (∼200 km at the sub-observer point) provide several important findings. First, we present observational evidence, for the first time, of the possibility that the westward rotation of the polar features (the hot polar spots and the surrounding cold collars) is synchronized between the northern and southern hemispheres. Second, after high-pass filtering, the images reveal that streaks and mottled and patchy patterns are distributed over the entire disk, with typical amplitudes of ∼0.5 K, and vary from day to day. The detected features, some of which are similar to those seen in past UV images, result from inhomogeneities of both the temperature and the cloud top altitude. Third, the equatorial center-to-limb variations of brightness temperatures have a systematic day-night asymmetry, except those on October 25, that the dayside brightness temperatures are higher than the nightside brightness temperatures by 0-4 K under the same viewing geometry. Such asymmetry would be caused by the propagation of the migrating semidiurnal tide. Finally, by applying the lapse rates deduced from previous studies, we demonstrate that the equatorial center-to-limb curves in the two spectral channels give access to two parameters: the cloud scale height H and the cloud top altitude zc. The acceptable models for data on October 25 are obtained at H = 2.4-4.3 km and zc = 66-69 km; this supports previous results determined from spacecraft observations.

Statistical Analysis of the Correlation between Microwave Emission Anomalies and Seismic Activity Based on AMSR-E Satellite Data

NASA Astrophysics Data System (ADS)

qin, kai; Wu, Lixin; De Santis, Angelo; Zhang, Bin

2016-04-01

Pre-seismic thermal IR anomalies and ionosphere disturbances have been widely reported by using the Earth observation system (EOS). To investigate the possible physical mechanisms, a series of detecting experiments on rock loaded to fracturing were conducted. Some experiments studies have demonstrated that microwave radiation energy will increase under the loaded rock in specific frequency and the feature of radiation property can reflect the deformation process of rock fracture. This experimental result indicates the possibility that microwaves are emitted before earthquakes. Such microwaves signals are recently found to be detectable before some earthquake cases from the brightness temperature data obtained by the microwave-radiometer Advanced Microwave-Scanning Radiometer for the EOS (AMSR-E) aboard the satellite Aqua. This suggested that AMSR-E with vertical- and horizontal-polarization capability for six frequency bands (6.925, 10.65, 18.7, 23.8, 36.5, and 89.0 GHz) would be feasible to detect an earthquake which is associated with rock crash or plate slip. However, the statistical analysis of the correlation between satellite-observed microwave emission anomalies and seismic activity are firstly required. Here, we focus on the Kamchatka peninsula to carry out a statistical study, considering its high seismicity activity and the dense orbits covering of AMSR-E in high latitudes. 8-years (2003-2010) AMSR-E microwave brightness temperature data were used to reveal the spatio-temporal association between microwave emission anomalies and 17 earthquake events (M>5). Firstly, obvious spatial difference of microwave brightness temperatures between the seismic zone at the eastern side and the non-seismic zone the western side within the Kamchatka peninsula are found. Secondly, using both vertical- and horizontal-polarization to extract the temporal association, it is found that abnormal changes of microwave brightness temperatures appear generally 2 months before the M>6 earthquakes. Since the microwave emissions observed by AMSR-E are affected by various factors (e.g., emission of the earth's surface and emission, absorption and scattering of the atmosphere), further study together with the surface temperature, soil moisture and atmospheric water vapor will remove the weather and climate influences.

Effects of the Antenna Aperture on Remote Sensing of Sea Surface Salinity at L-Band

NASA Technical Reports Server (NTRS)

Dinnat, Emmanuel P.; LeVine, David M.

2006-01-01

Remote sensing of sea surface salinity with sufficient accuracy to meet the needs of global oceanography is a challenging task. The global variability of the salinity signal in the open ocean is only a few Kelvin even at L-band and an accuracy on the order of 0.1K is desired to study the influence of salinity on ocean circulation and energy exchange with the atmosphere. On the other hand, resolution is not an issue for understanding the dynamics of the open ocean where scales of hundreds of km are not uncommon. This permits remote sensing with large antenna footprints and spatial averaging to reduce noise. However, antennas with large footprints introduce other problems. For example, the angle of incidence and hence the brightness temperature varies over the footprint. Similarly, the polarization of brightness temperature relative to the antenna ports changes. Studies have been conducted using antenna patterns representative of the antenna that will be flown on the Aquarius mission to examine these effects. Aquarius is a pushbroom style radiometer with three beams looking across track away from the sun. The beams are at incidences angles (at the spacecraft) of about 26.5, 34 and 40 degrees each with a half-power beam width of about 5.8 degrees. It is shown that the measured brightness temperature is biased relative to the value at boresight because of changes across the field of view. The bias can be as much as 4K and positive or negative depending on polarization. Polarization mixing because of the variations of the local plane of incidence across the footprint also occur and can result in biased polarimetric measurements. A bias in the third Stokes parameter of as much as 0.4K is possible. Such effects may affect algorithms that use the third Stokes parameter to correct for Faraday rotation. Another issue associated with the antenna is sun glint. This is an issue determined by surface roughness and antenna sidelobes. Examples will be given for the random component (glint) for the case of the Aquarius antenna beams. Fortunately, the Aquarius beams mostly look to the dark side of the day-night termination, but during some portions of the year they will see sun-lighted ocean. In this case, glint could be an issue for the inner-most beam.

Tropical Pacific sea surface salinity variability derived from SMOS data: Comparison with in-situ observations.

NASA Astrophysics Data System (ADS)

Ballabrera, Joaquim; Hoareau, Nina; Umbert, Marta; Martínez, Justino; Turiel, Antonio

2013-04-01

Prediction of El Niño/Southern Oscillation (ENSO), and its relation with global climate anomalies, continues to be an important research effort in short-term climate forecasting. This task has become even more challenging as researchers are becoming more and more convinced that there is not a single archetypical El Niño (or La Niña) pattern, but several. During some events (called now Standard or East Pacific), the largest temperature anomalies are located at the eastern part of the Pacific. However, during some of the most recent events, the largest anomalies are restricted to the central part of the Pacific Ocean, and are now called Central Pacific or Modoki (a Japanese word for "almost") events. Although the role of salinity in operational ENSO forecasting was initially neglected (in contrast with temperature, sea level, or surface winds), recent studies have shown that salinity does play a role in the preconditioning of ENSO. Moreover, some researchers suggest that sea surface salinity might play a role (through the modulation of the western Pacific barrier layer) to favor the Standard or the Modoki nature of each event. Sea Surface Salinity maps are being operationally generated from microwave (L-band, 1.4 Ghz) brightness temperature maps. The L-band frequency was chosen because is the optimal one for ocean salinity measurements. However, after three years of satellite data, it has been found that noise in brightness temperatures (due to natural and artificial sources) is larger than expected. Moreover, the retrieval of SSS information requires special care because of the low sensitivity of the brightness temperature to SSS: from 0.2-0.8 K per salinity unit. Despite of all these facts, current accuracy of SS maps ranges from 0.2-0.4, depending on the processing level and the region being considered. We present here our study about the salinity variability in the tropical Pacific Ocean from the 9-day, 0.25 bins salinity maps derived from the SMOS reprocessing campaign released to the SMOS user community on March 2011. During the period under study, the equatorial Pacific has been in a quasi-continuous La Niña state. During the cold phases of ENSO, positive anomalies of SSS are expected with the largest anomalous values in the western warm-fresh pool. The anomalies derived from the SMOS data do indeed display a positive anomaly. The persistence of the feature, its geographical pattern, the time modulation of the anomaly amplitude indicate, and its resemblance with in situ observations indicate this novel observation technology is currently able to capture seasonal and interannual signatures of climate interest.

MARSTHERM: A Web-based System Providing Thermophysical Analysis Tools for Mars Research

NASA Astrophysics Data System (ADS)

Putzig, N. E.; Barratt, E. M.; Mellon, M. T.; Michaels, T. I.

2013-12-01

We introduce MARSTHERM, a web-based system that will allow researchers access to a standard numerical thermal model of the Martian near-surface and atmosphere. In addition, the system will provide tools for the derivation, mapping, and analysis of apparent thermal inertia from temperature observations by the Mars Global Surveyor Thermal Emission Spectrometer (TES) and the Mars Odyssey Thermal Emission Imaging System (THEMIS). Adjustable parameters for the thermal model include thermal inertia, albedo, surface pressure, surface emissivity, atmospheric dust opacity, latitude, surface slope angle and azimuth, season (solar longitude), and time steps for calculations and output. The model computes diurnal surface and brightness temperatures for either a single day or a full Mars year. Output options include text files and plots of seasonal and diurnal surface, brightness, and atmospheric temperatures. The tools for the derivation and mapping of apparent thermal inertia from spacecraft data are project-based, wherein the user provides an area of interest (AOI) by specifying latitude and longitude ranges. The system will then extract results within the AOI from prior global mapping of elevation (from the Mars Orbiter Laser Altimeter, for calculating surface pressure), TES annual albedo, and TES seasonal and annual-mean 2AM and 2PM apparent thermal inertia (Putzig and Mellon, 2007, Icarus 191, 68-94). In addition, a history of TES dust opacity within the AOI is computed. For each project, users may then provide a list of THEMIS images to process for apparent thermal inertia, optionally overriding the TES-derived dust opacity with a fixed value. Output from the THEMIS derivation process includes thumbnail and context images, GeoTIFF raster data, and HDF5 files containing arrays of input and output data (radiance, brightness temperature, apparent thermal inertia, elevation, quality flag, latitude, and longitude) and ancillary information. As a demonstration of capabilities, we will present results from a thermophysical study of Gale Crater (Barratt and Putzig, 2013, EPSC abstract 613), for which TES and THEMIS mapping has been carried out during system development. Public access to the MARSTHERM system will be provided in conjunction with the 2013 AGU Fall Meeting and will feature the numerical thermal model and thermal-inertia derivation algorithm developed by Mellon et al. (2000, Icarus 148, 437-455) as modified by Putzig and Mellon (2007, Icarus 191, 68-94). Updates to the thermal model and derivation algorithm that include a more sophisticated representation of the atmosphere and a layered subsurface are presently in development, and these will be incorporated into the system when they are available. Other planned enhancements include tools for modeling temperatures from horizontal mixtures of materials and slope facets, for comparing heterogeneity modeling results to TES and THEMIS results, and for mosaicking THEMIS images.

Double Bright Band Observations with High-Resolution Vertically Pointing Radar, Lidar, and Profiles

NASA Technical Reports Server (NTRS)

Emory, Amber E.; Demoz, Belay; Vermeesch, Kevin; Hicks, Michael

2014-01-01

On 11 May 2010, an elevated temperature inversion associated with an approaching warm front produced two melting layers simultaneously, which resulted in two distinct bright bands as viewed from the ER-2 Doppler radar system, a vertically pointing, coherent X band radar located in Greenbelt, MD. Due to the high temporal resolution of this radar system, an increase in altitude of the melting layer of approximately 1.2 km in the time span of 4 min was captured. The double bright band feature remained evident for approximately 17 min, until the lower atmosphere warmed enough to dissipate the lower melting layer. This case shows the relatively rapid evolution of freezing levels in response to an advancing warm front over a 2 h time period and the descent of an elevated warm air mass with time. Although observations of double bright bands are somewhat rare, the ability to identify this phenomenon is important for rainfall estimation from spaceborne sensors because algorithms employing the restriction of a radar bright band to a constant height, especially when sampling across frontal systems, will limit the ability to accurately estimate rainfall.

Network based sky Brightness Monitor

NASA Astrophysics Data System (ADS)

McKenna, Dan; Pulvermacher, R.; Davis, D. R.

2009-01-01

We have developed and are currently testing an autonomous 2 channel photometer designed to measure the night sky brightness in the visual wavelengths over a multi-year campaign. The photometer uses a robust silicon sensor filtered with Hoya CM500 glass. The Sky brightness is measured every minute at two elevation angles typically zenith and 20 degrees to monitor brightness and transparency. The Sky Brightness monitor consists of two units, the remote photometer and a network interface. Currently these devices use 2.4 Ghz transceivers with a free space range of 100 meters. The remote unit is battery powered with day time recharging using a solar panel. Data received by the network interface transmits data via standard POP Email protocol. A second version is under development for radio sensitive areas using an optical fiber for data transmission. We will present the current comparison with the National Park Service sky monitoring camera. We will also discuss the calibration methods used for standardization and temperature compensation. This system is expected to be deployed in the next year and be operated by the International Dark Sky Association SKYMONITOR project.

A Coronal Hole Jet Observed with Hinode and the Solar Dynamics Observatory

NASA Technical Reports Server (NTRS)

Young, Peter H.; Muglach, Karin

2014-01-01

A small blowout jet was observed at the boundary of the south coronal hole on 2011 February 8 at around 21:00 UT. Images from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO) revealed an expanding loop rising from one footpoint of a compact, bipolar bright point. Magnetograms from the Helioseismic Magnetic Imager (HMI) on board SDO showed that the jet was triggered by the cancelation of a parasitic positive polarity feature near the negative pole of the bright point. The jet emission was present for 25 mins and it extended 30 Mm from the bright point. Spectra from the EUV Imaging Spectrometer on board Hinode yielded a temperature and density of 1.6 MK and 0.9-1.7 × 10( exp 8) cu cm for the ejected plasma. Line-of-sight velocities reached up to 250 km/s. The density of the bright point was 7.6 × 10(exp 8) cu cm, and the peak of the bright point's emission measure occurred at 1.3 MK, with no plasma above 3 MK.

Double bright band observations with high-resolution vertically pointing radar, lidar, and profilers

NASA Astrophysics Data System (ADS)

Emory, Amber E.; Demoz, Belay; Vermeesch, Kevin; Hicks, Micheal

2014-07-01

On 11 May 2010, an elevated temperature inversion associated with an approaching warm front produced two melting layers simultaneously, which resulted in two distinct bright bands as viewed from the ER-2 Doppler radar system, a vertically pointing, coherent X band radar located in Greenbelt, MD. Due to the high temporal resolution of this radar system, an increase in altitude of the melting layer of approximately 1.2 km in the time span of 4 min was captured. The double bright band feature remained evident for approximately 17 min, until the lower atmosphere warmed enough to dissipate the lower melting layer. This case shows the relatively rapid evolution of freezing levels in response to an advancing warm front over a 2 h time period and the descent of an elevated warm air mass with time. Although observations of double bright bands are somewhat rare, the ability to identify this phenomenon is important for rainfall estimation from spaceborne sensors because algorithms employing the restriction of a radar bright band to a constant height, especially when sampling across frontal systems, will limit the ability to accurately estimate rainfall.

Substituting the polarizer mechanism with a polarization camera - an experiment to confirm its capability

NASA Astrophysics Data System (ADS)

Reginald, Nelson Leslie; Gopalswamy, Natchimuthuk; Guhathakurta, Madhulika; Yashiro, Seiji

2016-05-01

Experiments that require polarized brightness measurements, traditionally have done so by taking three successive images through a polarizer that is rotated through three well-defined angles. With the advent of the polarization camera, the polarized brightness can be measured from a single image. This also eliminates the need for a polarizer and the associated rotator mechanisms and can contribute towards less weight, size, less power requirements, and importantly higher temporal resolution. We intend to demonstrate the capabilities of the polarization camera by conducting a field experiment in conjunction with the total solar eclipse of 21 August 2017 using the Imaging Spectrograph of Coronal Electrons (ISCORE) instrument (Reginald et. al., solar physics, 2009, 260, 347-361). In this instrumental concept four K-coronal images of the corona through four filters centered at 385.0, 398.7, 410.0, 423.3 nm with a bandpass of 4 nm are expected to allow us to determine the coronal electron temperature and electron speed all around the corona. In order to determine the K-coronal brightness through each filter, we would have to take three images by rotating a polarizer through three angles for each of the filters, and it is not feasible owing to the short durations of total solar eclipses. Therefore, in the past we have assumed the total brightness (F + K) measured by each of the four filters to represent K-coronal brightness, which is true in low solar corona. However, with the advent of the polarization camera we can now measure the Stokes Polarization Parameters on a pixel by pixel basis for every image taken by the polarization camera. This allows us to independently quantify the total brightness (K+F) and polarized brightness (K). Also in addition to the four filter images that allow us to measure the electron temperature and electron speed, taking an additional image without a filter will give us enough information to determine the electron density. This instrumental concept was first tried in conjunction with the total solar eclipse of 9 March 2016 in Maba, Indonesia, but was unfortunately clouded out.

Retrieving Land Surface Temperature from Hyperspectral Thermal Infrared Data Using a Multi-Channel Method

PubMed Central

Zhong, Xinke; Huo, Xing; Ren, Chao; Labed, Jelila; Li, Zhao-Liang

2016-01-01

Land Surface Temperature (LST) is a key parameter in climate systems. The methods for retrieving LST from hyperspectral thermal infrared data either require accurate atmospheric profile data or require thousands of continuous channels. We aim to retrieve LST for natural land surfaces from hyperspectral thermal infrared data using an adapted multi-channel method taking Land Surface Emissivity (LSE) properly into consideration. In the adapted method, LST can be retrieved by a linear function of 36 brightness temperatures at Top of Atmosphere (TOA) using channels where LSE has high values. We evaluated the adapted method using simulation data at nadir and satellite data near nadir. The Root Mean Square Error (RMSE) of the LST retrieved from the simulation data is 0.90 K. Compared with an LST product from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) on Meteosat, the error in the LST retrieved from the Infared Atmospheric Sounding Interferometer (IASI) is approximately 1.6 K. The adapted method can be used for the near-real-time production of an LST product and to provide the physical method to simultaneously retrieve atmospheric profiles, LST, and LSE with a first-guess LST value. The limitations of the adapted method are that it requires the minimum LSE in the spectral interval of 800–950 cm−1 larger than 0.95 and it has not been extended for off-nadir measurements. PMID:27187408

Venus: estimates of the surface temperature and pressure from radio and radar measurements.

PubMed

Wood, A T; Wattson, R B; Pollack, J B

1968-10-04

The radio brightness temperature and radar cross section spectra of Venus are in much better accord with surface boundary conditions deduced from a combination of the Mariner V results and the radar radius than those obtained by the Venera 4 space probe. The average surface temperature and pressure are approximately 750 degrees K and 90 atmospheres.

Ultrahigh 6D-brightness electron beams for the light sources of the next generation

NASA Astrophysics Data System (ADS)

Habib, Fahim; Manahan, Grace G.; Scherkl, Paul; Heinemann, Thomas; Sheng, Z. M.; Bruhwiler, D. L.; Cary, J. R.; Rosenzweig, J. B.; Hidding, Bernhard

2017-10-01

The plasma photocathode mechanism (aka Trojan Horse) enables a path towards electron beams with nm-level normalized emittance and kA range peak currents, hence ultrahigh 5D-brightness. This ultrahigh 5D-brightness beams hold great prospects to realize laboratory scale free-electron-lasers. However, the GV/m-accelerating gradient in plasma accelerators leads to substantial energy chirp and spread. The large energy spread is a major show-stopper towards key application such as the free-electron-laser. Here we present a novel method for energy chirp compensation which takes advantage of tailored beam loading due to a second ``escort'' bunch released via plasma photocathode. The escort bunch reverses the accelerating field locally at the trapping position of the ultrahigh 5D-brightness beam. This induces a counter-clockwise rotation within the longitudinal phase space and allows to compensate the chirp completely. Analytical scaling predicts energy spread values below 0.01 percentage level. Ultrahigh 5D-brightness combined with minimized energy spread opens a path towards witness beams with unprecedented ultrahigh 6D-brightness.

Coherence imaging for ion temperature and flow measurements in a low-temperature helicon plasma source

NASA Astrophysics Data System (ADS)

Lester, R.; Zhai, Y.; Corr, C.; Howard, J.

2016-02-01

This paper describes a coherence imaging system designed for spectroscopic Doppler measurements of ion light in a low-temperature (T e   <  10 eV) helicon-produced argon plasma. Observation of the very small Doppler broadening of the Ar II 488 nm emission line requires very high spectral resolution, or equivalently, very large interferometric optical path delay (comparable with the coherence length of the emission line). For these polarization interferometers, this can only be achieved using large thicknesses (100 mm) of birefringent crystal. This poses special design challenges including the application of field-widening techniques and the development of passive thermal stabilization of the optical phase offset. We discuss the measurement principles and the optical design of these systems and present measurements of the line-integrated emissivity, and ion flow and ion temperatures along with tomographic reconstructions of the local values, for a cylindrical low temperature helicon discharge in a linear magnetized device with downstream magnetic mirror. Key results reveal a hollow edge-peaked temperature profile (central temperature  ∼0.1 eV) and sheared rigid-body rotational flows and axial flows which are comparable with the ion thermal speed. The emission line brightness, ion temperature and azimuthal ion flows are all found to increase with increased mirror magnetic field strength.

Structural changes in the hot Algol OGLE-LMC-DPV-097 and its disc related to its long cycle

NASA Astrophysics Data System (ADS)

Garcés L, J.; Mennickent, R. E.; Djurašević, G.; Poleski, R.; Soszyński, I.

2018-06-01

Double Periodic Variables (DPVs) are hot Algols showing a long photometric cycle of uncertain origin. We report the discovery of changes in the orbital light curve of OGLE-LMC-DPV-097 which depend on the phase of its long photometric cycle. During the ascending branch of the long cycle the brightness at the first quadrature is larger than during the second quadrature, during the maximum of the long cycle the brightness is basically the same at both quadratures, during the descending branch the brightness at the second quadrature is larger than during the first quadrature, and during the minimum of the long cycle the secondary minimum disappears. We model the light curve at different phases of the long cycle and find that the data are consistent with changes in the properties of the accretion disc and two disc spots. The disc's size and temperature change with the long-cycle period. We find a smaller and hotter disc at minimum, and larger and cooler disc at maximum. The spot temperatures, locations, and angular sizes also show variability during the long cycle.

Ultrabright continuously tunable terahertz-wave generation at room temperature

PubMed Central

Hayashi, Shin'ichiro; Nawata, Kouji; Taira, Takunori; Shikata, Jun-ichi; Kawase, Kodo; Minamide, Hiroaki

2014-01-01

The hottest frequency region in terms of research currently lies in the ‘frequency gap' region between microwaves and infrared: terahertz waves. Although new methods for generating terahertz radiation have been developed, most sources cannot generate high-brightness terahertz beams. Here we demonstrate the generation of ultrabright terahertz waves (brightness ~0.2 GW/sr·cm2, brightness temperature of ~1018 K, peak power of >50 kW) using parametric wavelength conversion in a nonlinear crystal; this is brighter than many specialized sources such as far-infrared free-electron lasers (~1016 K, ~2 kW). We revealed novel parametric wavelength conversion using stimulated Raman scattering in LiNbO3 without stimulated Brillouin scattering using recently-developed microchip laser. Furthermore, nonlinear up-conversion techniques allow the intense terahertz waves to be visualized and their frequency determined. These results are very promising for extending applied research into the terahertz region, and we expect that this source will open up new research fields such as nonlinear optics in the terahertz region. PMID:24898269

Ultrabright continuously tunable terahertz-wave generation at room temperature.

PubMed

Hayashi, Shin'ichiro; Nawata, Kouji; Taira, Takunori; Shikata, Jun-ichi; Kawase, Kodo; Minamide, Hiroaki

2014-06-05

The hottest frequency region in terms of research currently lies in the 'frequency gap' region between microwaves and infrared: terahertz waves. Although new methods for generating terahertz radiation have been developed, most sources cannot generate high-brightness terahertz beams. Here we demonstrate the generation of ultrabright terahertz waves (brightness ~0.2 GW/sr·cm(2), brightness temperature of ~10(18) K, peak power of >50 kW) using parametric wavelength conversion in a nonlinear crystal; this is brighter than many specialized sources such as far-infrared free-electron lasers (~10(16) K, ~2 kW). We revealed novel parametric wavelength conversion using stimulated Raman scattering in LiNbO3 without stimulated Brillouin scattering using recently-developed microchip laser. Furthermore, nonlinear up-conversion techniques allow the intense terahertz waves to be visualized and their frequency determined. These results are very promising for extending applied research into the terahertz region, and we expect that this source will open up new research fields such as nonlinear optics in the terahertz region.

Through thick and thin: quantitative classification of photometric observing conditions on Paranal

NASA Astrophysics Data System (ADS)

Kerber, Florian; Querel, Richard R.; Neureiter, Bianca; Hanuschik, Reinhard

2016-07-01

A Low Humidity and Temperature Profiling (LHATPRO) microwave radiometer is used to monitor sky conditions over ESO's Paranal observatory. It provides measurements of precipitable water vapour (PWV) at 183 GHz, which are being used in Service Mode for scheduling observations that can take advantage of favourable conditions for infrared (IR) observations. The instrument also contains an IR camera measuring sky brightness temperature at 10.5 μm. It is capable of detecting cold and thin, even sub-visual, cirrus clouds. We present a diagnostic diagram that, based on a sophisticated time series analysis of these IR sky brightness data, allows for the automatic and quantitative classification of photometric observing conditions over Paranal. The method is highly sensitive to the presence of even very thin clouds but robust against other causes of sky brightness variations. The diagram has been validated across the complete range of conditions that occur over Paranal and we find that the automated process provides correct classification at the 95% level. We plan to develop our method into an operational tool for routine use in support of ESO Science Operations.

Forward-Looking Infrared Cameras for Micrometeorological Applications within Vineyards

PubMed Central

Katurji, Marwan; Zawar-Reza, Peyman

2016-01-01

We apply the principles of atmospheric surface layer dynamics within a vineyard canopy to demonstrate the use of forward-looking infrared cameras measuring surface brightness temperature (spectrum bandwidth of 7.5 to 14 μm) at a relatively high temporal rate of 10 s. The temporal surface brightness signal over a few hours of the stable nighttime boundary layer, intermittently interrupted by periods of turbulent heat flux surges, was shown to be related to the observed meteorological measurements by an in situ eddy-covariance system, and reflected the above-canopy wind variability. The infrared raster images were collected and the resultant self-organized spatial cluster provided the meteorological context when compared to in situ data. The spatial brightness temperature pattern was explained in terms of the presence or absence of nighttime cloud cover and down-welling of long-wave radiation and the canopy turbulent heat flux. Time sequential thermography as demonstrated in this research provides positive evidence behind the application of thermal infrared cameras in the domain of micrometeorology, and to enhance our spatial understanding of turbulent eddy interactions with the surface. PMID:27649208

Bibliography of Ice Properties and Forecasting Related to Transportation in Ice-Covered Waters.

DTIC Science & Technology

1980-09-01

bulk modulus mobility exponent m were calculated from the strain and a shear mode that obeys a Maxwell model. A rate sensitivity of flow stress. The...were conducted with a mobile microwave A study of airborne microwave brightness tempera- laboratory containing a number of microwave radi. ture...highest brightness temperatures, averaging -3.0"C a mobile platform has been a goal of researchers and and -0.5"C, respectively. organizations, such

Bifurcation structure of localized states in the Lugiato-Lefever equation with anomalous dispersion

NASA Astrophysics Data System (ADS)

Parra-Rivas, P.; Gomila, D.; Gelens, L.; Knobloch, E.

2018-04-01

The origin, stability, and bifurcation structure of different types of bright localized structures described by the Lugiato-Lefever equation are studied. This mean field model describes the nonlinear dynamics of light circulating in fiber cavities and microresonators. In the case of anomalous group velocity dispersion and low values of the intracavity phase detuning these bright states are organized in a homoclinic snaking bifurcation structure. We describe how this bifurcation structure is destroyed when the detuning is increased across a critical value, and determine how a bifurcation structure known as foliated snaking emerges.

Intercomparison of the LASCO-C2, SECCHI-COR1, SECCHI-COR2, and Mk4 Coronagraphs

NASA Technical Reports Server (NTRS)

Frazin, Richard A.; Vasquez, Alberto M.; Thompson, William T.; Hewett, Russell J.; Lamy, Philippe; Llebaria, Antoine; Vourlidas, Angelos; Burkepile, Joan

2012-01-01

In order to assess the reliability and consistency of white-light coronagraph measurements, we report on quantitative comparisons between polarized brightness [pB] and total brightness [B] images taken by the following white-light coronagraphs: LASCO-C2 on SOHO, SECCHI-COR1 and -COR2 on STEREO, and the ground-based MLSO-Mk4. The data for this comparison were taken on 16 April 2007, when both STEREO spacecraft were within 3.1 deg. of Earth’s heliographic longitude, affording essentially the same view of the Sun for all of the instruments. Due to the difficulties of estimating stray-light backgrounds in COR1 and COR2, only Mk4 and C2 produce reliable coronal-hole values (but not at overlapping heights), and these cannot be validated without rocket flights or ground-based eclipse measurements. Generally, the agreement between all of the instruments’ pB values is within the uncertainties in bright streamer structures, implying that measurements of bright CMEs also should be trustworthy. Dominant sources of uncertainty and stray light are discussed, as is the design of future coronagraphs from the perspective of the experiences with these instruments.

Measurement of brightness temperature of two-dimensional electron gas in channel of a high electron mobility transistor at ultralow dissipation power

NASA Astrophysics Data System (ADS)

Korolev, A. M.; Shulga, V. M.; Turutanov, O. G.; Shnyrkov, V. I.

2016-07-01

A technically simple and physically clear method is suggested for direct measurement of the brightness temperature of two-dimensional electron gas (2DEG) in the channel of a high electron mobility transistor (HEMT). The usage of the method was demonstrated with the pseudomorphic HEMT as a specimen. The optimal HEMT dc regime, from the point of view of the "back action" problem, was found to belong to the unsaturated area of the static characteristics possibly corresponding to the ballistic electron transport mode. The proposed method is believed to be a convenient tool to explore the ballistic transport, electron diffusion, 2DEG properties and other electrophysical processes in heterostructures.

Preliminary results of radiometric measurements of clear air and cloud brightness (antenna) temperatures at 37GHz

NASA Astrophysics Data System (ADS)

Arakelyan, A. K.; Hambaryan, A. K.; Arakelyan, A. A.

2012-05-01

In this paper the results of polarization measurements of clear air and clouds brightness temperatures at 37GHz are presented. The results were obtained during the measurements carried out in Armenia from the measuring complex built under the framework of ISTC Projects A-872 and A-1524. The measurements were carried out at vertical and horizontal polarizations, under various angles of sensing by Ka-band combined scatterometric-radiometric system (ArtAr-37) developed and built by ECOSERV Remote Observation Centre Co.Ltd. under the framework of the above Projects. In the paper structural and operational features of the utilized system and the whole measuring complex will be considered and discussed as well.

The SEASAT altimeter wet tropospheric range correction revisited

NASA Technical Reports Server (NTRS)

Tapley, D. B.; Lundberg, J. B.; Born, G. H.

1984-01-01

An expanded set of radiosonde observations was used to calculate the wet tropospheric range correction for the brightness temperature measurements of the SEASAT scanning multichannel microwave radiometer (SMMR). The accuracy of the conventional algorithm for wet tropospheric range correction was evaluated. On the basis of the expanded observational data set, the algorithm was found to have a bias of about 1.0 cm, and a standard deviation 2.8 cm. In order to improve the algorithm, the exact linear, quadratic and logarithmic relationships between brightness temperatures and range corrections were determined. Various combinations of measurement parameters were used to reduce the standard deviation between SEASAT SMMR and radiosonde observations to about 2.1 cm. The performance of various range correction formulas is compared in a table.

Diurnal Variations of Titan's Surface Temperatures From Cassini -CIRS Observations

NASA Astrophysics Data System (ADS)

Cottini, Valeria; Nixon, Conor; Jennings, Don; Anderson, Carrie; Samuelson, Robert; Irwin, Patrick; Flasar, F. Michael

The Cassini Composite Infrared Spectrometer (CIRS) observations of Saturn's largest moon, Titan, are providing us with the ability to detect the surface temperature of the planet by studying its outgoing radiance through a spectral window in the thermal infrared at 19 m (530 cm-1) characterized by low opacity. Since the first acquisitions of CIRS Titan data the in-strument has gathered a large amount of spectra covering a wide range of latitudes, longitudes and local times. We retrieve the surface temperature and the atmospheric temperature pro-file by modeling proper zonally averaged spectra of nadir observations with radiative transfer computations. Our forward model uses the correlated-k approximation for spectral opacity to calculate the emitted radiance, including contributions from collision induced pairs of CH4, N2 and H2, haze, and gaseous emission lines (Irwin et al. 2008). The retrieval method uses a non-linear least-squares optimal estimation technique to iteratively adjust the model parameters to achieve a spectral fit (Rodgers 2000). We show an accurate selection of the wide amount of data available in terms of footprint diameter on the planet and observational conditions, together with the retrieved results. Our results represent formal retrievals of surface brightness temperatures from the Cassini CIRS dataset using a full radiative transfer treatment, and we compare to the earlier findings of Jennings et al. (2009). The application of our methodology over wide areas has increased the planet coverage and accuracy of our knowledge of Titan's surface brightness temperature. In particular we had the chance to look for diurnal variations in surface temperature around the equator: a trend with slowly increasing temperature toward the late afternoon reveals that diurnal temperature changes are present on Titan surface. References: Irwin, P.G.J., et al.: "The NEMESIS planetary atmosphere radiative transfer and retrieval tool" (2008). JQSRT, Vol. 109, pp. 1136-1150, 2008. Rodgers, C. D.: "Inverse Methods For Atmospheric Sounding: Theory and Practice". World Scientific, Singapore, 2000. Jennings, D.E., et al.: "Titan's Surface Brightness Temperatures." Ap. J. L., Vol. 691, pp. L103-L105, 2009.

Automated Adaptive Brightness in Wireless Capsule Endoscopy Using Image Segmentation and Sigmoid Function.

PubMed

Shrestha, Ravi; Mohammed, Shahed K; Hasan, Md Mehedi; Zhang, Xuechao; Wahid, Khan A

2016-08-01

Wireless capsule endoscopy (WCE) plays an important role in the diagnosis of gastrointestinal (GI) diseases by capturing images of human small intestine. Accurate diagnosis of endoscopic images depends heavily on the quality of captured images. Along with image and frame rate, brightness of the image is an important parameter that influences the image quality which leads to the design of an efficient illumination system. Such design involves the choice and placement of proper light source and its ability to illuminate GI surface with proper brightness. Light emitting diodes (LEDs) are normally used as sources where modulated pulses are used to control LED's brightness. In practice, instances like under- and over-illumination are very common in WCE, where the former provides dark images and the later provides bright images with high power consumption. In this paper, we propose a low-power and efficient illumination system that is based on an automated brightness algorithm. The scheme is adaptive in nature, i.e., the brightness level is controlled automatically in real-time while the images are being captured. The captured images are segmented into four equal regions and the brightness level of each region is calculated. Then an adaptive sigmoid function is used to find the optimized brightness level and accordingly a new value of duty cycle of the modulated pulse is generated to capture future images. The algorithm is fully implemented in a capsule prototype and tested with endoscopic images. Commercial capsules like Pillcam and Mirocam were also used in the experiment. The results show that the proposed algorithm works well in controlling the brightness level accordingly to the environmental condition, and as a result, good quality images are captured with an average of 40% brightness level that saves power consumption of the capsule.

Stellar model chromospheres. III - Arcturus /K2 III/

NASA Technical Reports Server (NTRS)

Ayres, T. R.; Linsky, J. L.

1975-01-01

Models are constructed for the upper photosphere and chromosphere of Arcturus based on the H, K, and IR triplet lines of Ca II and the h and k lines of Mg II. The chromosphere model is derived from complete redistribution solutions for a five-level Ca II ion and a two-level Mg II ion. A photospheric model is derived from the Ca II wings using first the 'traditional' complete-redistribution limit and then the more realistic partial-redistribution approximation. The temperature and mass column densities for the temperature-minimum region and the chromosphere-transition region boundary are computed, and the pressure in the transition region and corona are estimated. It is found that the ratio of minimum temperature to effective temperature is approximately 0.77 for Arcturus, Procyon, and the sun, and that mass tends to increase at the temperature minimum with decreasing gravity. The pressure is found to be about 1 percent of the solar value, and the surface brightness of the Arcturus transition region and coronal spectrum is estimated to be much less than for the sun. The partial-redistribution calculation for the Ca II K line indicates that the emission width is at least partially determined by damping rather than Doppler broadening, suggesting a reexamination of previous explanations for the Wilson-Bappu effect.

A multi-sensor analysis of Nimbus 5 data on 22 January 1973. [meteorological parameters

NASA Technical Reports Server (NTRS)

Allison, L. J.; Rodgers, E. B.; Wilheit, T. T.; Wexler, R.

1973-01-01

The Nimbus 5 meteorological satellite carried aloft a full complement of radiation sensors, the data from which were analyzed and intercompared during orbits 569-570 on 22 January 1973. The electrically scanning microwave radiometer (ESMR) which sensed passive microwave radiation in the 19.35 GHz region, delineated rain areas over the ocean off the U.S. east coast, in good agreement with WSR-57 and FPS-77 radar imagery and permitted the estimation of rainfall rates in this region. Residual ground water in the lower Mississippi Valley, which resulted from abnormal rainfall in previous months, was indicated under clear sky conditions by soil brightness temperature values in the Nimbus 5 ESMR and U.S. Air Force Data Acquisition and Processing Program (DAPP) IR data. The temperature-humidity infrared radiometer showed the height and spatial configuration of frontal clouds along the east coast and outlined the confluence of a polar jet stream with a broad sub-tropical jet stream along the U.S. Gulf Coast. Temperature profiles from three vertical temperature sounders, the infrared temperature profile radiometer (ITPR), the Nimbus E microwave spectrometer (NEMS) and the selective chopper radiometer (SCR) were found to be in good agreement with related radiosonde ascents along orbit 569 from the sub-tropics to the Arctic Circle.

Propagation of waves in a bounded random layer with laminar structure

NASA Technical Reports Server (NTRS)

Karam, M. A.; Fung, A. K.

1985-01-01

A closed form solution has been developed to obtain the intensity propagating in a bounded layer with laminar structure. Then, the brightness temperature due to an arbitrary temperature profile has been derived. Results are specialized to a half space to compare with those reported in the literature.

SMOS sea surface salinity maps of the Arctic Ocean

NASA Astrophysics Data System (ADS)

Gabarro, Carolina; Olmedo, Estrella; Turiel, Antonio; Ballabrera-Poy, Joaquim; Martinez, Justino; Portabella, Marcos

2016-04-01

Salinity and temperature gradients drive the thermohaline circulation of the oceans, and play a key role in the ocean-atmosphere coupling. The strong and direct interactions between the ocean and the cryosphere (primarily through sea ice and ice shelves) is also a key ingredient of the thermohaline circulation. The ESA's Soil Moisture and Ocean Salinity (SMOS) mission, launched in 2009, has the objective measuring soil moisture over the continents and sea surface salinity over the oceans. Although the mission was originally conceived for hydrological and oceanographic studies [1], SMOS is also making inroads in the cryospheric monitoring. SMOS carries an innovative L-band (1.4 GHz, or 21-cm wavelength), passive interferometric radiometer (the so-called MIRAS) that measures the electromagnetic radiation emitted by the Earth's surface, at about 50 km spatial resolution wide swath (1200-km), and with a 3-day revisit time at the equator, but a more frequent one at the poles. Although the SMOS radiometer operating frequency offers almost the maximum sensitivity of the brightness temperature (TB) to sea surface salinity (SSS) variations, this is rather low, , i.e.,: 90% of ocean SSS values span a range of brightness temperatures of only 5K at L-band. This sensitivity is particularly low in cold waters. This implies that the SSS retrieval requires high radiometric performance. Since the SMOS launch, SSS Level 3 maps have been distributed by several expert laboratories including the Barcelona Expert Centre (BEC). However, since the TB sensitivity to SSS decreases with decreasing sea surface temperature (SST), large retrieval errors had been reported when retrieving salinity values at latitudes above 50⁰N. Two new processing algorithms, recently developed at BEC, have led to a considerable improvement of the SMOS data, allowing for the first time to derive SSS maps in cold waters. The first one is to empirically characterize and correct the systematic biases with six years of SMOS data acquisitions. The second is the modification of the filtering criterion to account for the statistical distributions of SSS at each ocean grid point. This allows retrieving a value of SSS which is less affected by outliers originated from RFI and other effects. We will provide an assessment of the quality of these new SSS products in the Arctic, as well as illustrate the potential of these maps to monitor the main river discharges to the Arctic Ocean. [1] Font, J.; Camps, A.; Borges, A.; Martín-Neira, M.; Boutin, J.; Reul, N.; Kerr, Y.; Hahne, A. & Mecklenburg, S. SMOS: The Challenging Sea Surface Salinity Measurement From Space Proceedings of the IEEE, 2010, 98, 649 -665

Titan's Surface Temperatures Maps from Cassini - CIRS Observations

NASA Astrophysics Data System (ADS)

Cottini, Valeria; Nixon, C. A.; Jennings, D. E.; Anderson, C. M.; Samuelson, R. E.; Irwin, P. G. J.; Flasar, F. M.

2009-09-01

The Cassini Composite Infrared Spectrometer (CIRS) observations of Saturn's largest moon, Titan, are providing us with the ability to detect the surface temperature of the planet by studying its outgoing radiance through a spectral window in the thermal infrared at 19 μm (530 cm-1) characterized by low opacity. Since the first acquisitions of CIRS Titan data the instrument has gathered a large amount of spectra covering a wide range of latitudes, longitudes and local times. We retrieve the surface temperature and the atmospheric temperature profile by modeling proper zonally averaged spectra of nadir observations with radiative transfer computations. Our forward model uses the correlated-k approximation for spectral opacity to calculate the emitted radiance, including contributions from collision induced pairs of CH4, N2 and H2, haze, and gaseous emission lines (Irwin et al. 2008). The retrieval method uses a non-linear least-squares optimal estimation technique to iteratively adjust the model parameters to achieve a spectral fit (Rodgers 2000). We show an accurate selection of the wide amount of data available in terms of footprint diameter on the planet and observational conditions, together with the retrieved results. Our results represent formal retrievals of surface brightness temperatures from the Cassini CIRS dataset using a full radiative transfer treatment, and we compare to the earlier findings of Jennings et al. (2009). In future, application of our methodology over wide areas should greatly increase the planet coverage and accuracy of our knowledge of Titan's surface brightness temperature. References: Irwin, P.G.J., et al.: "The NEMESIS planetary atmosphere radiative transfer and retrieval tool" (2008). JQSRT, Vol. 109, pp. 1136-1150, 2008. Rodgers, C. D.: "Inverse Methods For Atmospheric Sounding: Theory and Practice". World Scientific, Singapore, 2000. Jennings, D.E., et al.: "Titan's Surface Brightness Temperatures." Ap. J. L., Vol. 691, pp. L103-L105, 2009.

In-depth Analysis of Land Surface Emissivity using Microwave Polarization Difference Index to Improve Satellite QPE

NASA Astrophysics Data System (ADS)

Zheng, Y.; Kirstetter, P. E.; Hong, Y.; Wen, Y.; Turk, J.; Gourley, J. J.

2015-12-01

One of primary uncertainties in satellite overland quantitative precipitation estimates (QPE) from passive sensors such as radiometers is the impact on the brightness temperatures by the surface land emissivity. The complexity of surface land emissivity is linked to its temporal variations (diurnal and seasonal) and spatial variations (subsurface vertical profiles of soil moisture, vegetation structure and surface temperature) translating into sub-pixel heterogeneity within the satellite field of view (FOV). To better extract the useful signal from hydrometeors, surface land emissivity needs to be determined and filtered from the satellite-measured brightness temperatures. Based on the dielectric properties of surface land cover constitutes, Microwave Polarization Differential index (MPDI) is expected to carry the composite effect of surface land properties on land surface emissivity, with a higher MPDI indicating a lower emissivity. This study analyses the dependence of MPDI to soil moisture, vegetation and surface skin temperature over 9 different land surface types. Such analysis is performed using the normalized difference vegetation index (NDVI) from MODIS, the near surface air temperature from the RAP model and ante-precedent precipitation accumulation from the Multi-Radar Multi-Sensor as surrogates for the vegetation, surface skin temperature and shallow layer soil moisture, respectively. This paper provides 1) evaluations of brightness temperature-based MPDI from the TRMM and GPM Microwave Imagers in both raining and non-raining conditions to test the dependence of MPDI to precipitation; 2) comparisons of MPDI categorized into instantly before, during and immediately after selected precipitation events to examine the impact of modest-to-heavy precipitation on the spatial pattern of MPDI; 3) inspections of relationship between MPDI versus rain fraction and rain rate within the satellite sensors FOV to investigate the behaviors of MPDI in varying precipitation conditions; 4) analysis of discrepancies of MPDI over 10.65, 19.35, 37 and 85.8 GHz to identify the sensitivity of MPDS to microwave wavelengths.

Optically dark excitonic states mediated exciton and biexciton valley dynamics in monolayer WSe₂.

PubMed

Zhang, Minghua; Fu, Jiyong; Dias, A C; Qu, Fanyao

2018-05-18

We present a theory to address the photoluminescence (PL) intensity and valley polarization (VP) dynamics in monolayer WSe$_2$, under the impact of excitonic dark states of both excitons and biexcitons. We find that the PL intensity of all excitonic channels including intravalley exciton (X$_{\\rm b}$), intravalley biexciton (XX$_{\\rm k,k}$) and intervalley biexciton (XX$_{\\rm k,k^\\prime}$) in particular for the {XX$_{\\rm k,k}$} PL is enhanced by laser excitation fluence. In addition, our results indicate the anomalous temperature dependence of PL, i.e., increasing with temperature, as a result of favored phonon assisted dark-to-bright scatterings at high temperatures. Moreover, we observe that the PL is almost immune to intervalley scatterings, which trigger the exchange of excitonic states between the two valleys. As far as the valley polarization is concerned, we find that the VP of X$_{\\rm b}$ shrinks as temperature increases, exhibiting opposite temperature response to PL, while the intravalley XX$_{\\rm k,k}$ VP is found almost independent of temperature. In contrast to both X$_{\\rm b}$ and XX$_{\\rm k,k}$, the intervalley XX$_{\\rm k,k^\\prime}$ VP identically vanishes, because of equal populations of excitons in the $K$ and $K^\\prime$ valleys bounded to form intervalley biexcitons. Notably, it is found that the X$_{\\rm b}$ VP much more strongly depends on bright-dark scattering than that of {XX$_{\\rm k,k}$}, making dark state act as a robust reservoir for valley polarization against intervalley scatterings for X$_{\\rm b}$ at strong bright-dark scatterings, but not for XX$_{\\rm k,k}$. Dark excitonic states enabled enhancement of VP benefits quantum technology for information processing based on the valley degree of freedom in valleytronic devices. Furthermore, the VP has strong dependence on intervalley scattering but maintains essentially constant with excitation fluence. Finally, the time evolution of PL and VP, depending on temperature and excitation fluence, is discussed. © 2018 IOP Publishing Ltd.

HILIS - A HIGH INTENSITY LIGHT SYSTEM FOR ALGAE FOOD PRODUCTION,

DTIC Science & Technology

ALGAE, PRODUCTION CONTROL), (*FOOD, FEASIBILITY STUDIES), CHLORELLA , CALORIMETRY, NUTRITION, MODEL TESTS, ILLUMINATION, BRIGHTNESS, TEMPERATURE CONTROL, HEAT TRANSFER, SPECTRUM SIGNATURES, TEST METHODS, TEST EQUIPMENT.

Simulation of the lunar surface emission and inversion of the lunar regolith thickness using fusion of optical and microwave remote sensing data

NASA Astrophysics Data System (ADS)

Jin, Y.-Q.

begin table htbp begin center begin tabular p 442pt hline A correspondence of the lunar regolith layer thickness to the lunar digital elevation mapping DEM is presented to construct the global distribution of lunar regolith layer thickness Based on some measurements the physical temperature distribution over the lunar surface is proposed Albedo of the lunar nearside at the wavelengths 0 42 0 65 0 75 0 95 mu m from the telescopic observation is employed to construct the spatial distribution of the FeO TiO 2 on the lunar regolith layer A statistic relationship between the DEM and FeO TiO 2 content of the lunar nearside is then extended to construction of FeO TiO 2 content of the lunar farside Thus the dielectric permittivity of global lunar regolith layer can be determined par Based on all theses conditions brightness temperature of the lunar regolith layer in passive microwave remote sensing which is planned for China s Chang-E lunar project is numerically simulated by a parallel layer model using the fluctuation dissipation theorem par Furthermore taking these simulations as observations an inversion method of the lunar regolith layer thickness is developed by using three- or two-channels brightness temperatures When the FeO TiO 2 content is low and the four channels brightness temperatures in Chang-E project are well distinguishable the regolith layer thickness and physical temperature of the underlying lunar rocky media can be inverted by the three-channels approach When the FeO TiO 2 content is so high that the

The thermal infrared radiance properties of dust aerosol over ocean

NASA Astrophysics Data System (ADS)

Hao, Zengzhou; Pan, Delu; Tu, Qianguang; Gong, Fang; Chen, Jianyu

2015-10-01

Asian dust storms, which can long-range transport to ocean, often occur on spring. The present of Asian dust aerosols over ocean makes some difficult for other studies, such as cloud detection, and also take some advantage for ocean, such as take nutrition into the ocean by dry or wet deposition. Therefore, it is important to study the dust aerosol and retrieve the properties of dust from satellite observations that is mainly from the thermal infrared radiance. In this paper, the thermal infrared radiance properties of dust aerosol over ocean are analyzed from MODIS and MTSAT2 observations and Streamer model simulations. By analyzing some line samples and a series of dust aerosol region, it shows that the dust aerosol brightness temperature at 12μm (BT12) is always greater than BT11 and BT8.5, and BT8.5 is general greater than BT11. The brightness temperature different between 11μm and 12μm (BTD11-12) increases with the dust intensity. And the BTD11-12 will become positive when the atmospheric relative humidity is greater than 70%. The BTD11-12 increases gradually with the surface temperature while the effect on BTD11-12 of dust layer temperature is not evident. Those are caused by the transmission of the dust aerosol is different at the two thermal infrared channels. During daytime, dust infrared brightness temperature at mid-infrared bands should reduce the visual radiance, which takes about 25K or less. In general, BT3.7 is greater than BT11 for dust aerosol. Those results are helpful to monitor or retrieve dust aerosol physical properties over ocean from satellite.

Use of quantitative analysis of sonographic brightness for detection of early healing of tendon injury in horses.

PubMed

Micklethwaite, L; Wood, A K; Sehgal, C M; Polansky, M; Dowling, B A; Dart, A J; Rose, R J; Hodgson, D R

2001-08-01

To determine whether quantitative analysis of sonographic brightness could be used to detect healing of an induced injury of the superficial digital flexor tendon in horses and whether rate of healing was influenced by equine recombinant growth hormone. 8 clinically normal Standardbreds. A localized injury was created in the left and right superficial digital flexor tendons of each horse by injection of 2,000 units of collagenase. After injury, 4 horses received equine recombinant growth hormone, a possible promoter of tendon healing. Sonographic images (7.5 MHz) of the flexor tendons and ligaments of the metacarpal region were recorded on videotape prior to injury and weekly for 7 weeks after injury. Images were digitized, and sonographic brightness of tendons and ligaments was calculated. Collagenase-induced injury was sonographically similar to naturally occurring injury. After injury, sonographic brightness of the tendon decreased; after 3 weeks, brightness progressively increased, although by 7 weeks brightness had not returned to preinjury value. Equine recombinant growth hormone had no significant effect on the rate of tendon healing, as evaluated sonographically or at necropsy. As healing developed, alterations in sonographic brightness of injured tendons coincided with real changes in tendon structure. Quantitative sonographic brightness could be used to accurately monitor healing of equine tendon and ligament injuries and investigate the efficacy of various treatment regimens.

Three-Dimensional Structure and Evolution of Extreme-Ultraviolet Bright Points Observed by STEREO/SECCHI/EUVI

NASA Technical Reports Server (NTRS)

Kwon, Ryun Young; Chae, Jongchul; Davila, Joseph M.; Zhang, Jie; Moon, Yong-Jae; Poomvises, Watanachak; Jones, Shaela I.

2012-01-01

We unveil the three-dimensional structure of quiet-Sun EUV bright points and their temporal evolution by applying a triangulation method to time series of images taken by SECCHI/EUVI on board the STEREO twin spacecraft. For this study we examine the heights and lengths as the components of the three-dimensional structure of EUV bright points and their temporal evolutions. Among them we present three bright points which show three distinct changes in the height and length: decreasing, increasing, and steady. We show that the three distinct changes are consistent with the motions (converging, diverging, and shearing, respectively) of their photospheric magnetic flux concentrations. Both growth and shrinkage of the magnetic fluxes occur during their lifetimes and they are dominant in the initial and later phases, respectively. They are all multi-temperature loop systems which have hot loops (approx. 10(exp 6.2) K) overlying cooler ones (approx 10(exp 6.0) K) with cool legs (approx 10(exp 4.9) K) during their whole evolutionary histories. Our results imply that the multi-thermal loop system is a general character of EUV bright points. We conclude that EUV bright points are flaring loops formed by magnetic reconnection and their geometry may represent the reconnected magnetic field lines rather than the separator field lines.

Effects of dim or bright-light exposure during the daytime on human gastrointestinal activity.

PubMed

Sone, Yoshiaki; Hyun, Ki-Ja; Nishimura, Shinya; Lee, Young-Ah; Tokura, Hiromi

2003-01-01

On the basis of our previous findings that bright-light exposure during the daytime has profound influence on physiological parameters such as melatonin secretion and tympanic temperature in humans, we proposed the hypothesis that bright vs. dim light-exposure during the daytime has a different influence on the activity of the digestive system via the endocrine and/or autonomic nervous system. To examine this hypothesis, we conducted a series of counterbalanced experiments in which subjects stayed the daytime (7:00 to 15:00h) under either a dim (80 lux) or bright (5,000 lux) light condition. We measured gastrointestinal activity using a breath hydrogen (indicative of carbohydrate malabsorption) and an electrogastrography (EGG, indicative of gastric myoelectric activity) test. The results showed the postprandial breath hydrogen excretion during the following nighttime period after daytime exposure to the dim-light condition was significantly higher than under the bright-light condition (p < 0.05). In addition, the spectrum total power of the EGG recorded after taking the evening meal was significantly lower for the dim than bright-light condition (p < 0.05). These results support our hypothesis and indicate that dim-light exposure during the daytime suppresses the digestion of the evening meal, resulting in malabsorption of dietary carbohydrates in it.

On the Long-Term Stability of Microwave Radiometers Using Noise Diodes for Calibration

NASA Technical Reports Server (NTRS)

Brown, Shannon T.; Desai, Shailen; Lu, Wenwen; Tanner, Alan B.

2007-01-01

Results are presented from the long-term monitoring and calibration of the National Aeronautics and Space Administration Jason Microwave Radiometer (JMR) on the Jason-1 ocean altimetry satellite and the ground-based Advanced Water Vapor Radiometers (AWVRs) developed for the Cassini Gravity Wave Experiment. Both radiometers retrieve the wet tropospheric path delay (PD) of the atmosphere and use internal noise diodes (NDs) for gain calibration. The JMR is the first radiometer to be flown in space that uses NDs for calibration. External calibration techniques are used to derive a time series of ND brightness for both instruments that is greater than four years. For the JMR, an optimal estimator is used to find the set of calibration coefficients that minimize the root-mean-square difference between the JMR brightness temperatures and the on-Earth hot and cold references. For the AWVR, continuous tip curves are used to derive the ND brightness. For the JMR and AWVR, both of which contain three redundant NDs per channel, it was observed that some NDs were very stable, whereas others experienced jumps and drifts in their effective brightness. Over the four-year time period, the ND stability ranged from 0.2% to 3% among the diodes for both instruments. The presented recalibration methodology demonstrates that long-term calibration stability can be achieved with frequent recalibration of the diodes using external calibration techniques. The JMR PD drift compared to ground truth over the four years since the launch was reduced from 3.9 to - 0.01 mm/year with the recalibrated ND time series. The JMR brightness temperature calibration stability is estimated to be 0.25 K over ten days.

Phase-shifting human circadian rhythms: influence of sleep timing, social contact and light exposure

NASA Technical Reports Server (NTRS)

Duffy, J. F.; Kronauer, R. E.; Czeisler, C. A.

1996-01-01

1. Both the timing of behavioural events (activity, sleep and social interactions) and the environmental light-dark cycle have been reported to contribute to entrainment of human circadian rhythms to the 24 h day. Yet, the relative contribution of those putative behavioural synchronizers to that of light exposure remains unclear. 2. To investigate this, we inverted the schedule of rest, sedentary activity and social contact of thirty-two young men either with or without exposure to bright light. 3. On this inverted schedule, the endogenous component of the core temperature rhythm of subjects who were exposed to bright light showed a significant phase shift, demonstrating that they were adapting to the new schedule. In contrast, the core temperature rhythm of subjects who were not exposed to bright light moved on average 0.2 h later per day and after 10 days had not significantly adapted to the new schedule. 4. The direction of phase shift in the groups exposed to bright light was dependent on the time of bright light exposure, while control subjects drifted to a later hour regardless of the timing of their schedule of sleep timing, social contact and meals. 5. These results support the concept that the light-dark cycle is the most important synchronizer of the human circadian system. They suggest that inversion of the sleep-wake, rest-activity and social contact cycles provides relatively minimal drive for resetting the human circadian pacemaker. 6. These data indicate that interventions designed to phase shift human circadian rhythms for adjustment to time zone changes or altered work schedules should focus on properly timed light exposure.

Bright triplet excitons in caesium lead halide perovskites

NASA Astrophysics Data System (ADS)

Becker, Michael A.; Vaxenburg, Roman; Nedelcu, Georgian; Sercel, Peter C.; Shabaev, Andrew; Mehl, Michael J.; Michopoulos, John G.; Lambrakos, Samuel G.; Bernstein, Noam; Lyons, John L.; Stöferle, Thilo; Mahrt, Rainer F.; Kovalenko, Maksym V.; Norris, David J.; Rainò, Gabriele; Efros, Alexander L.

2018-01-01

Nanostructured semiconductors emit light from electronic states known as excitons. For organic materials, Hund’s rules state that the lowest-energy exciton is a poorly emitting triplet state. For inorganic semiconductors, similar rules predict an analogue of this triplet state known as the ‘dark exciton’. Because dark excitons release photons slowly, hindering emission from inorganic nanostructures, materials that disobey these rules have been sought. However, despite considerable experimental and theoretical efforts, no inorganic semiconductors have been identified in which the lowest exciton is bright. Here we show that the lowest exciton in caesium lead halide perovskites (CsPbX3, with X = Cl, Br or I) involves a highly emissive triplet state. We first use an effective-mass model and group theory to demonstrate the possibility of such a state existing, which can occur when the strong spin-orbit coupling in the conduction band of a perovskite is combined with the Rashba effect. We then apply our model to CsPbX3 nanocrystals, and measure size- and composition-dependent fluorescence at the single-nanocrystal level. The bright triplet character of the lowest exciton explains the anomalous photon-emission rates of these materials, which emit about 20 and 1,000 times faster than any other semiconductor nanocrystal at room and cryogenic temperatures, respectively. The existence of this bright triplet exciton is further confirmed by analysis of the fine structure in low-temperature fluorescence spectra. For semiconductor nanocrystals, which are already used in lighting, lasers and displays, these excitons could lead to materials with brighter emission. More generally, our results provide criteria for identifying other semiconductors that exhibit bright excitons, with potential implications for optoelectronic devices.

Microwave Brightness Temperature and Its Relation to Atmospheric General Circulation Features

DTIC Science & Technology

1989-05-17

absolute temperature. Molecules may absorb electromagnetic radiation and transition to a higher energy level, or emit radiation and transition to a lower...Walker, 1970). In the microwave region, thermal emission is the only 10 source of radiation and is dependent on the absolute temperature of the...substance as determined by the Planck function. The relationship between absolute temperature and radiation emitted is given by Planck’s Law for a

Polyethers containing 4-(carbazol-2-yl)-7-arylbenzo[c]-1,2,5-thiadiazole chromophores as solution processed materials for hole transporting layers of OLEDs

NASA Astrophysics Data System (ADS)

Krucaite, G.; Tavgeniene, D.; Xie, Z.; Lin, X.; Zhang, B.; Grigalevicius, S.

2018-02-01

Two polyethers containing electroactive pendent 4-(carbazol-2-yl)-7-arylbenzo[c]-1,2,5-thiadiazole moieties have been synthesized by the multi-step synthetic route. Full characterization of their structures is presented. The polymers represent derivatives of very high thermal stability with initial thermal degradation temperatures of 425 °C and 431 °C. Glass transition temperatures of the amorphous materials were also very high and reached values of 154 °C and 163 °C. The electron photoemission spectra of thin layers of the polymers showed ionization potentials of 5.84 eV and 5.93 eV. Hole-transporting properties of the polymeric materials were tested in the structures of organic light emitting diodes with Alq3 as the green emitter and electron transporting material. An electroluminescent device containing hole-transporting layer (HTL) of the polymer with electroactive 4-carbazolyl-7-phenylbenzo[c]-1,2,5-thiadiazole moieties exhibited turn on voltage of 6.2 V, maximum photometric efficiency of 2.5 cd/A and maximum brightness exceeding 300 cd/m2. The device containing HTL of the polymer with 4-carbazolyl-7-(1-naphtyl)benzo[c]-1,2,5-thiadiazole moieties demonstrated turn on voltage of 5.2 V, maximum photometric efficiency of 1.6 cd/A and maximum brightness exceeding 1500 cd/m2. The efficiencies were about 30-90% higher than that of the device containing widely used hole transporting layers of poly(9-vinylcarbazole).

Classification methods for monitoring Arctic sea ice using OKEAN passive/active two-channel microwave data

USGS Publications Warehouse

Belchansky, Gennady I.; Douglas, David C.

2000-01-01

This paper presents methods for classifying Arctic sea ice using both passive and active (2-channel) microwave imagery acquired by the Russian OKEAN 01 polar-orbiting satellite series. Methods and results are compared to sea ice classifications derived from nearly coincident Special Sensor Microwave Imager (SSM/I) and Advanced Very High Resolution Radiometer (AVHRR) image data of the Barents, Kara, and Laptev Seas. The Russian OKEAN 01 satellite data were collected over weekly intervals during October 1995 through December 1997. Methods are presented for calibrating, georeferencing and classifying the raw active radar and passive microwave OKEAN 01 data, and for correcting the OKEAN 01 microwave radiometer calibration wedge based on concurrent 37 GHz horizontal polarization SSM/I brightness temperature data. Sea ice type and ice concentration algorithms utilized OKEAN's two-channel radar and passive microwave data in a linear mixture model based on the measured values of brightness temperature and radar backscatter, together with a priori knowledge about the scattering parameters and natural emissivities of basic sea ice types. OKEAN 01 data and algorithms tended to classify lower concentrations of young or first-year sea ice when concentrations were less than 60%, and to produce higher concentrations of multi-year sea ice when concentrations were greater than 40%, when compared to estimates produced from SSM/I data. Overall, total sea ice concentration maps derived independently from OKEAN 01, SSM/I, and AVHRR satellite imagery were all highly correlated, with uniform biases, and mean differences in total ice concentration of less than four percent (sd<15%).

Optical sensing in laser machining

NASA Astrophysics Data System (ADS)

Smurov, Igor; Doubenskaia, Maria

2009-05-01

Optical monitoring of temperature evolution and temperature distribution in laser machining provides important information to optimise and to control technological process under study. The multi-wavelength pyrometer is used to measure brightness temperature under the pulsed action of Nd:YAG laser on stainless steel substrates. Specially developed "notch" filters (10-6 transparency at 1.06 μm wavelength) are applied to avoid the influence of laser radiation on temperature measurements. The true temperature is restored based on the method of multi-colour pyrometry. Temperature monitoring of the thin-walled gilded kovar boxes is applied to detect deviation of the welding seam from its optimum position. The pyrometers are used to control CO2-laser welding of steel and Ti plates: misalignment of the welded plates, variation of the welding geometry, internal defects, deviation of the laser beam trajectory from the junction, etc. The temperature profiles along and across the welding axis are measured by the 2D pyrometer. When using multi-component powder blends in laser cladding, for example metal matrix composite with ceramic reinforcement, one needs to control temperature of the melt to avoid thermal decomposition of certain compounds (as WC) and to assure melting of the base metal (as Co). Infra-red camera FLIR Phoenix RDAS provides detailed information on distribution of brightness temperature in laser cladding zone. CCD-camera based diagnostic system is used to measure particles-in-flight velocity and size distribution.

Effect of bright light on EEG activities and subjective sleepiness to mental task during nocturnal sleep deprivation.

PubMed

Yokoi, Mari; Aoki, Ken; Shimomura, Yoshihiro; Iwanaga, Koichi; Katsuura, Tetsuo; Shiomura, Yoshihiro

2003-11-01

The purpose of this study was to investigate the effect of the exposure to bright light on EEG activity and subjective sleepiness at rest and at the mental task during nocturnal sleep deprivation. Eight male subjects lay awake in semi-supine in a reclining seat from 21:00 to 04:30 under the bright (BL; >2500 lux) or the dim (DL; <150 lux) light conditions. During the sleep deprivation, the mental task (Stroop color-word conflict test: CWT) was performed each 15 min in one hour. EEG, subjective sleepiness, rectal and mean skin temperatures and urinary melatonin concentrations were measured. The subjective sleepiness increased with time of sleep deprivation during both rest and CWT under the DL condition. The exposure to bright light delayed for 2 hours the increase in subjective sleepiness at rest and suppressed the increase in that during CWT. The bright light exposure also delayed the increase in the theta and alpha wave activities in EEG at rest. In contrast, the effect of the bright light exposure on the theta and alpha wave activities disappeared by CWT. Additionally, under the BL condition, the entire theta activity during CWT throughout nocturnal sleep deprivation increased significantly from that in a rest condition. Our results suggest that the exposure to bright light throughout nocturnal sleep deprivation influences the subjective sleepiness during the mental task and the EEG activity, as well as the subjective sleepiness at rest. However, the effect of the bright light exposure on the EEG activity at the mental task diminishes throughout nocturnal sleep deprivation.

Bilinearization of the generalized coupled nonlinear Schrödinger equation with variable coefficients and gain and dark-bright pair soliton solutions.

PubMed

Chakraborty, Sushmita; Nandy, Sudipta; Barthakur, Abhijit

2015-02-01

We investigate coupled nonlinear Schrödinger equations (NLSEs) with variable coefficients and gain. The coupled NLSE is a model equation for optical soliton propagation and their interaction in a multimode fiber medium or in a fiber array. By using Hirota's bilinear method, we obtain the bright-bright, dark-bright combinations of a one-soliton solution (1SS) and two-soliton solutions (2SS) for an n-coupled NLSE with variable coefficients and gain. Crucial properties of two-soliton (dark-bright pair) interactions, such as elastic and inelastic interactions and the dynamics of soliton bound states, are studied using asymptotic analysis and graphical analysis. We show that a bright 2-soliton, in addition to elastic interactions, also exhibits multiple inelastic interactions. A dark 2-soliton, on the other hand, exhibits only elastic interactions. We also observe a breatherlike structure of a bright 2-soliton, a feature that become prominent with gain and disappears as the amplitude acquires a minimum value, and after that the solitons remain parallel. The dark 2-soliton, however, remains parallel irrespective of the gain. The results found by us might be useful for applications in soliton control, a fiber amplifier, all optical switching, and optical computing.

Characteristics of the Energetic Igniters Through Integrating B/Ti Nano-Multilayers on TaN Film Bridge.

PubMed

Yan, YiChao; Shi, Wei; Jiang, HongChuan; Cai, XianYao; Deng, XinWu; Xiong, Jie; Zhang, WanLi

2015-12-01

The energetic igniters through integrating B/Ti nano-multilayers on tantalum nitride (TaN) ignition bridge are designed and fabricated. The X-ray diffraction (XRD) and temperature coefficient of resistance (TCR) results show that nitrogen content has a great influence on the crystalline structure and TCR. TaN films under nitrogen ratio of 0.99 % exhibit a near-zero TCR value of approximately 10 ppm/°C. The scanning electron microscopy demonstrates that the layered structure of the B/Ti multilayer films is clearly visible with sharp and smooth interfaces. The electrical explosion characteristics employing a capacitor discharge firing set at the optimized charging voltage of 45 V reveal an excellent explosion performance by (B/Ti) n /TaN integration film bridge with small ignition delay time, high explosion temperature, much more bright flash of light, and much large quantities of the ejected product particles than TaN film bridge.

Energy balance in solar and stellar chromospheres

NASA Technical Reports Server (NTRS)

Avrett, E. H.

1981-01-01

Net radiative cooling rates for quiet and active regions of the solar chromosphere and for two stellar chromospheres are calculated from corresponding atmospheric models. Models of chromospheric temperature and microvelocity distributions are derived from observed spectra of a dark point within a cell, the average sun and a very bright network element on the quiet sun, a solar plage and flare, and the stars Alpha Boo and Lambda And. Net radiative cooling rates due to the transitions of various atoms and ions are then calculated from the models as a function of depth. Large values of the net radiative cooling rate are found at the base of the chromosphere-corona transition region which are due primarily to Lyman alpha emission, and a temperature plateau is obtained in the transition region itself. In the chromospheric regions, the calculated cooling rate is equal to the mechanical energy input as a function of height and thus provides a direct constraint on theories of chromospheric heating.

MSU Antenna Pattern Data

NASA Technical Reports Server (NTRS)

Mo, Tsan; Kleespies, Thomas J.; Green, J. Philip

2000-01-01

The Microwave Sounding Unit (MSU) antenna pattern data for nine MSU Flight Models (FMs) have been successfully rescued from 22-year old 7-track and 9-track magnetic tapes and cartridges. These antenna pattern data were unpacked into user-friendly ASCII format, and are potentially useful for making antenna pattern corrections to MSU antenna temperatures in retrieving the true brightness temperatures. We also properly interpreted the contents of the data and show how to convert the measured antenna signal amplitude in volts into relative antenna power in dB with proper normalization. It is found that the data are of high quality with a 60-dB drop in the co-polarized antenna patterns from the central peak value to its side-lobe regions at scan angles beyond 30 deg. The unpacked antenna pattern data produced in this study provide a useful database for data users to correct the antenna side-lobe contribution to MSU measurements. All of the data are available to the scientific community on a single CD-ROM.

Joint Assimilation of SMOS Brightness Temperature and GRACE Terrestrial Water Storage Observations for Improved Soil Moisture Estimation

NASA Technical Reports Server (NTRS)

Girotto, Manuela; Reichle, Rolf H.; De Lannoy, Gabrielle J. M.; Rodell, Matthew

2017-01-01

Observations from recent soil moisture missions (e.g. SMOS) have been used in innovative data assimilation studies to provide global high spatial (i.e. 40 km) and temporal resolution (i.e. 3-days) soil moisture profile estimates from microwave brightness temperature observations. In contrast with microwave-based satellite missions that are only sensitive to near-surface soil moisture (0 - 5 cm), the Gravity Recovery and Climate Experiment (GRACE) mission provides accurate measurements of the entire vertically integrated terrestrial water storage column but, it is characterized by low spatial (i.e. 150,000 km2) and temporal (i.e. monthly) resolutions. Data assimilation studies have shown that GRACE-TWS primarily affects (in absolute terms) deeper moisture storages (i.e., groundwater). This work hypothesizes that unprecedented soil water profile accuracy can be obtained through the joint assimilation of GRACE terrestrial water storage and SMOS brightness temperature observations. A particular challenge of the joint assimilation is the use of the two different types of measurements that are relevant for hydrologic processes representing different temporal and spatial scales. The performance of the joint assimilation strongly depends on the chosen assimilation methods, measurement and model error spatial structures. The optimization of the assimilation technique constitutes a fundamental step toward a multi-variate multi-resolution integrative assimilation system aiming to improve our understanding of the global terrestrial water cycle.

Joint assimilation of SMOS brightness temperature and GRACE terrestrial water storage observations for improved soil moisture estimation

NASA Astrophysics Data System (ADS)

Girotto, M.; Reichle, R. H.; De Lannoy, G.; Rodell, M.

2017-12-01

Observations from recent soil moisture missions (e.g. SMOS) have been used in innovative data assimilation studies to provide global high spatial (i.e. 40 km) and temporal resolution (i.e. 3-days) soil moisture profile estimates from microwave brightness temperature observations. In contrast with microwave-based satellite missions that are only sensitive to near-surface soil moisture (0-5 cm), the Gravity Recovery and Climate Experiment (GRACE) mission provides accurate measurements of the entire vertically integrated terrestrial water storage column but, it is characterized by low spatial (i.e. 150,000 km2) and temporal (i.e. monthly) resolutions. Data assimilation studies have shown that GRACE-TWS primarily affects (in absolute terms) deeper moisture storages (i.e., groundwater). This work hypothesizes that unprecedented soil water profile accuracy can be obtained through the joint assimilation of GRACE terrestrial water storage and SMOS brightness temperature observations. A particular challenge of the joint assimilation is the use of the two different types of measurements that are relevant for hydrologic processes representing different temporal and spatial scales. The performance of the joint assimilation strongly depends on the chosen assimilation methods, measurement and model error spatial structures. The optimization of the assimilation technique constitutes a fundamental step toward a multi-variate multi-resolution integrative assimilation system aiming to improve our understanding of the global terrestrial water cycle.

Surface Temperature Measurements from a Stator Vane Doublet in a Turbine Engine Afterburner Flame using Ultra-Bright Cr-Doped GdAlO3 Thermographic Phosphor

NASA Technical Reports Server (NTRS)

Eldridge, Jeffrey I.; Jenkins, Thomas P.; Allison, Stephen W.; Wolfe, Douglas E.; Howard, Robert P.

2013-01-01

Luminescence-based surface temperature measurements from an ultra-bright Cr-doped GdAlO3 perovskite (GAP:Cr) coating were successfully conducted on an air-film-cooled stator vane doublet exposed to the afterburner flame of a J85 test engine at University of Tennessee Space Institute (UTSI). The objective of the testing at UTSI was to demonstrate that reliable thermal barrier coating (TBC) surface temperatures based on luminescence decay of a thermographic phosphor could be obtained from the surface of an actual engine component in an aggressive afterburner flame environment and to address the challenges of a highly radiant background and high velocity gases. A high-pressure turbine vane doublet from a Honeywell TECH7000 turbine engine was coated with a standard electron-beam physical vapor deposited (EB-PVD) 200-m-thick TBC composed of yttria-stabilized zirconia (YSZ) onto which a 25-m-thick GAP:Cr thermographic phosphor layer was deposited by EB-PVD. The ultra-bright broadband luminescence from the GAP:Cr thermographic phosphor is shown to offer the advantage of over an order-of-magnitude greater emission intensity compared to rare-earth-doped phosphors in the engine test environment. This higher emission intensity was shown to be very desirable for overcoming the necessarily restricted probe light collection solid angle and for achieving high signal-to-background levels. Luminescence-decay-based surface temperature measurements varied from 500 to over 1000C depending on engine operating conditions and level of air film cooling.

VEGAS-SSS: A VST Early-Type GAlaxy Survey: Analysis of Small Stellar System

NASA Astrophysics Data System (ADS)

Cantiello, M.

VEGAS-SSS is a program devoted to study the properties of small stellar systems (SSSs) around bright galaxies, built on the VEGAS survey. At completion, the survey will have collected detailed photometric information of ˜ 100 bright early-type galaxies to study the properties of diffuse light (surface brightness, colours, SBF, etc.) and the clustered light (compact stellar systems) out to previously unreached projected galactocentric radii. VEGAS-SSS will define an accurate and homogeneous dataset that will have an important legacy value for studies of the evolution and transformation processes taking place in galaxies through the fossil information provided by SSSs.

The near-infrared properties of compact binary systems

NASA Astrophysics Data System (ADS)

Froning, Cynthia Suzanne

I present H- and K-band light curves of the dwarf nova cataclysmic variable (CV), IP Peg, and the novalike CV, RW Tri, and an H-band light curve of the novalike CV, SW Sex. All three systems showed contributions from the late-type secondary star and the accretion disk, including a primary eclipse of the accretion disk by the secondary star and a secondary eclipse of the star by the disk. The ellipsoidal variations of the secondary star in IP Peg were modeled and subtracted from the data. The subtracted light curves show a pronounced double-hump variation, resembling those seen in the dwarf novae WZ Sge and AL Com. The primary eclipse was modeled using maximum entropy disk mapping techniques. The accretion disk has a flat intensity distribution and a low brightness temperature (Tbr ~= 3000-4000 K). Superimposed on the face of the disk is the bright spot, where the mass accretion stream impacts the disk; the position of the bright spot is different from the range of positions seen at visible wavelengths. The near-infrared accretion disk flux is dominated by optically thin emission. The eclipse depth is too shallow to be caused by a fully opaque accretion disk. The NIR light curves in RW Tri show a deep primary eclipse of the accretion disk, ellipsoidal variations from the secondary star, a secondary eclipse, and strong flickering in the disk flux. The depth of the secondary eclipse indicates that the accretion disk is opaque. The light curve also has a hump extending from φ = 0.1-0.9 which was successfully modeled as flux from the inner face of the secondary star when heated by a ~0.2 L Lsolar source. The radial brightness temperature profile of the outer disk is consistent with models of a disk in steady-state for a mass transfer rate of M~=5×10- 10 Msolaryr- 1 . At small disk radii, however, the brightness temperature profile is flatter than the steady-state model. The H-band light curve of SW Sex is dominated by emission from the accretion disk. As in RW Tri, the light curve has a hump outside of primary eclipse which was modeled as flux from the secondary star when irradiated by a 0.2-0.3 Lsolar source. The light curve has a dip at φ = 0.5 which is consistent with an eclipse of the irradiated face of the secondary star by an opaque accretion disk. The accretion disk has a brightness temperature profile much flatter than the theoretical profile of a steady- state disk. The disk is asymmetric, with the front of the disk (the side facing the secondary star at mid-eclipse) hotter than the back. The bright spot, which appears in visible disk maps of SW Sex, is not seen in the NIR light curve. I also present H-band light curves of the X-ray binary system, A0620-00, and NIR spectra of two X-ray binaries, CI Cam, and the relativistic jet source, SS 433. (Abstract shortened by UMI.)

The 60 GHz radiometric local vertical sensor experiment

NASA Technical Reports Server (NTRS)

Grauling, C. H., Jr.

1973-01-01

The experiment concept involves the use of millimeter wave radiation the atmospheric oxygen to provide vertical sensing information to a satellite-borne radiometer. The radiance profile studies require the calculation of ray brightness temperature as a function of tangential altitude and atmosphere model, and the computer program developed for this purpose is discussed. Detailed calculations have been made for a total of 12 atmosphere models, including some showing severe warning conditions. The experiment system analysis investigates the effect of various design choices on system behavior. Calculated temperature profiles are presented for a wide variety of frequencies, bandwidths, and atmosphere models. System performance is determined by the convolution of the brightness temperature and an assumed antenna pattern. A compensation scheme to account for different plateau temperatures is developed and demonstrated. The millimeter wave components developed for the local vertical sensor are discussed, with emphasis on the antenna, low noise mixer, and solid state local oscillator. It was concluded that a viable sensing technique exists, useful over a wide range of altitude with an accuracy generally on the order of 0.01 degree or better.

Tropical cyclone warm core analyses with FY-3 microwave temperature sounder data

NASA Astrophysics Data System (ADS)

Liu, Zhe; Bai, Jie; Zhang, Wenjun; Yan, Jun; Zhou, Zhuhua

2014-05-01

Space-borne microwave instruments are well suited to analyze Tropical Cyclone (TC) warm core structure, because certain wavelengths of microwave energy are able to penetrate the cirrus above TC. With the vector discrete-ordinate microwave radiative transfer model, the basic atmospheric parameters of Hurricane BOB are used to simulate the upwelling brightness temperatures on each channel of the Microwave Temperature Sounder (MWTS) onboard FY-3A/3B observation. Based on the simulation, the characteristic of 1109 super typhoon "Muifa" warm core structure is analyzed with the MWTS channel 3. Through the radiative and hydrostatic equation, TC warm core brightness temperature anomalies are related to surface pressure anomalies. In order to correct the radiation attenuation caused by MWTS scan geometric features, and improve the capability in capturing the relatively complete warm core radiation, a proposed algorithm is devised to correct the bias from receiving warm core microwave radiation, shows similar time-variant tendency with "Muifa" minimal sea level pressure as described by TC best track data. As the next generation of FY-3 satellite will be launched in 2012, this method will be further verified

A survey of eight hot Jupiters in secondary eclipse using WIRCam at CFHT

NASA Astrophysics Data System (ADS)

Martioli, Eder; Colón, Knicole D.; Angerhausen, Daniel; Stassun, Keivan G.; Rodriguez, Joseph E.; Zhou, George; Gaudi, B. Scott; Pepper, Joshua; Beatty, Thomas G.; Tata, Ramarao; James, David J.; Eastman, Jason D.; Wilson, Paul Anthony; Bayliss, Daniel; Stevens, Daniel J.

2018-03-01

We present near-infrared high-precision photometry for eight transiting hot Jupiters observed during their predicted secondary eclipses. Our observations were carried out using the staring mode of the WIRCam instrument on the Canada-France-Hawaii Telescope (CFHT). We present the observing strategies and data reduction methods which delivered time series photometry with statistical photometric precision as low as 0.11 per cent. We performed a Bayesian analysis to model the eclipse parameters and systematics simultaneously. The measured planet-to-star flux ratios allowed us to constrain the thermal emission from the day side of these hot Jupiters, as we derived the planet brightness temperatures. Our results combined with previously observed eclipses reveal an excess in the brightness temperatures relative to the blackbody prediction for the equilibrium temperatures of the planets for a wide range of heat redistribution factors. We find a trend that this excess appears to be larger for planets with lower equilibrium temperatures. This may imply some additional sources of radiation, such as reflected light from the host star and/or thermal emission from residual internal heat from the formation of the planet.

Studies of snowpack properties by passive microwave radiometry

NASA Technical Reports Server (NTRS)

Chang, A. T. C.; Hall, D. K.; Foster, J. L.; Rango, A.; Schmugge, T. J.

1978-01-01

Research involving the microwave characteristics of snow was undertaken in order to expand the information content currently available from remote sensing, namely the measurement of snowcovered area. Microwave radiation emitted from beneath the snow surface can be sensed and thus permits information on internal snowpack properties to be inferred. The intensity of radiation received is a function of the average temperature and emissivity of the snow layers and is commonly referred to as the brightness temperature (T sub b). The T sub b varies with snow grain and crystal sizes, liquid water content and snowpack temperature. The T sub b of the 0.8 cm wavelength channel was found to decrease moreso with increasing snow depth than the 1.4 cm channel. More scattering of the shorter wavelength radiation occurs thus resulting in a lower T sub b for shorter wavelengths in a dry snowpack. The longer 21.0 cm wavelength was used to assess the condition of the underlying ground. Ultimately it may be possible to estimate snow volume over large areas using calibrated brightness temperatures and consequently improve snowmelt runoff predictions.