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Sample records for microwave water radiometer

  1. An airborne microwave radiometer and measurements of cloud liquid water

    Institute of Scientific and Technical Information of China (English)

    LEI Hengchi; JIN Dezhen; WEI Chong; SHEN Zhilai

    2003-01-01

    A single-channel (9.5 mm) airborne microwave radiometer with one antenna is developed. The retrieval methods and primary observation results of cloud liquid water and super-cooled cloud liquid water are discussed. The aircraft experiments show that the cloud liquid water and super-cooled liquid water can be sensitively monitored at some level of accuracy by the radiometer. The results of cloud liquid water content are reasonable and correspond well with the surface radar echo intensity. The design of the airborne radiometer and its retrieval methods are feasible, giving it application value.

  2. Microwave Radiometer (MWR) Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Morris, VR

    2006-08-01

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

  3. Microwave Radiometer Profiler

    Data.gov (United States)

    Oak Ridge National Laboratory — The microwave radiometer profiler (MWRP) provides vertical profiles of temperature, humidity, and cloud liquid water content as a function of height or pressure at...

  4. Continuous Time Series of Water Vapor Profiles from a Combination of Raman Lidar and Microwave Radiometer

    Directory of Open Access Journals (Sweden)

    Foth Andreas

    2016-01-01

    Full Text Available In this paper, we present a method to retrieve continuous water vapor profiles from a combination of a Raman lidar and a microwave radiometer. The integrated water vapor from the microwave radiometer is used to calibrate the Raman lidar operationally resulting in small biases compared to radiosondes. The height limitations for Raman lidars (cloud base and daylight contamination can be well compensated by the application of a two–step algorithm combining the Raman lidars mass mixing ratio and the microwave radiometers brightness temperatures.

  5. Atmospheric water distribution in cyclones as seen with Scanning Multichannel Microwave Radiometers (SMMR)

    Science.gov (United States)

    Katsaros, K. B.; Mcmurdie, L. A.

    1983-01-01

    Passive microwave measurements are used to study the distribution of atmospheric water in midlatitude cyclones. The integrated water vapor, integrated liquid water, and rainfall rate are deduced from the brightness temperatures at microwave frequencies measured by the Scanning Multichannel Microwave Radiometer (SMRR) flown on both the Seasat and Nimbus 7 satellites. The practical application of locating fronts by the cyclone moisture pattern over oceans is shown, and the relationship between the quantity of coastal rainfall and atmospheric water content is explored.

  6. Microwave Radiometer - high frequency

    Data.gov (United States)

    Oak Ridge National Laboratory — The Microwave Radiometer-High Frequency (MWRHF) provides time-series measurements of brightness temperatures from two channels centered at 90 and 150 GHz. These two...

  7. Retrieval of water, ammonia and dynamics using microwave spectra: With application to Juno Microwave Radiometer

    Science.gov (United States)

    Li, Cheng; Ingersoll, Andrew P.; Janssen, Michael A.

    2016-10-01

    The Juno Microwave Radiometer (MWR) is designed to measure the thermal emission of Jupiter's atmosphere from the cloud tops at about 1 bar pressure to as deep as hundreds of bars pressure, with unprecedented accuracy and spatial resolution. Unlike infrared spectroscopy, microwave observations of giant planetary atmospheres are difficult to interpret due to the absence of spectral features and broad weighting functions. The observed quantity is an intricate consequence of thermodynamic and dynamic processes. To unravel the mystery, we introduce two scalar parameters (stretching and cooling) that describe the alteration of the atmospheric thermal and compositional structure by dynamics. Using the above parameters, we are able to fit the Galileo Probe results as well as model the spectral differences between hot spots, zones and belts in Jupiter's atmosphere observed by VLA (de Pater et al., 2016). Finally, we make use of the state-of-the-art retrieval method - Markov Chain Monte Carlo - to determine the joint probability distribution of all parameters of interest. This approach fully calibrates error, assesses covariance between parameters, and explores the widest possible types of atmospheric conditions as opposed to traditional trial-and-error method. We apply this method to simulated Juno/MWR observations. We show that the water abundance is constrained to +3.1/-1.5 times solar for a normal situation and is constrained to an upper limit for an extreme situation.

  8. Microwave Radiometer Networks for Measurement of the Spatio-Temporal Variability of Water Vapor

    Science.gov (United States)

    Reising, S. C.; Iturbide-Sanchez, F.; Padmanabhan, S.

    2006-12-01

    Tropospheric water vapor plays a key role in the prediction of convective storm initiation, precipitation and extreme weather events. Conventionally, water vapor profiles are derived from dewpoint and temperature measurements using instrumented weather balloons, including radiosondes. These balloons take approximately one hour to measure from surface to tropopause, and transmitter-sensor packages cannot be reused. Such in-situ measurements provide profiles with very high vertical resolution but with severe limitations in temporal and spatial coverage. Raman lidars use active optical techniques to provide comparable vertical resolution and measurement accuracy to radiosondes. However, these lidars are bulky and expensive, and their operation is limited to clear-sky conditions due to the high optical opacity of clouds. Microwave radiometers provide path-integrated water vapor and liquid water with high temporal resolution during nearly all weather conditions. If multiple frequencies are measured near the water vapor resonance, coarse vertical profiles can be obtained using statistical inversion. Motivated by the need for improved temporal and spatial resolutions, a network of elevation and azimuth scanning radiometers is being developed to provide coordinated volumetric measurements of tropospheric water vapor. To realize this network, two Miniaturized Water Vapor profiling Radiometers (MVWR) have been designed and fabricated at Colorado State University. MWVR is small, light-weight, consumes little power and is highly stable. To reduce the mass, volume, cost and power consumption as compared to traditional waveguide techniques, MWVR was designed based on monolithic microwave integrated-circuit technology developed for the wireless communication and defense industries. It was designed for network operation, in which each radiometer will perform a complete volumetric scan within a few minutes, and overlapping scans from multiple sensors will be combined

  9. Measurements of integrated water vapor and cloud liquid water from microwave radiometers at the DOE ARM Cloud and Radiation Testbed in the U.S. Southern Great Plains

    Energy Technology Data Exchange (ETDEWEB)

    Liljegren, J.C. [Pacific Northwest Lab., Richland, WA (United States); Lesht, B.M.

    1996-06-01

    The operation and calibration of the ARM microwave radiometers is summarized. Measured radiometric brightness temperatures are compared with calculations based on the model using co-located radiosondes. Comparisons of perceptible water vapor retrieved from the radiometer with integrated soundings and co-located GPS retrievals are presented. The three water vapor sensing systems are shown to agree to within about 1 mm.

  10. Validation of stratospheric water vapour measurements from the airborne microwave radiometer AMSOS

    Directory of Open Access Journals (Sweden)

    S. C. Müller

    2008-01-01

    Full Text Available We present the validation of a water vapour dataset obtained by the Airborne Microwave Stratospheric Observing System AMSOS, a passive microwave radiometer operating at 183 GHz. Vertical profiles are retrieved from spectra by an optimal estimation method. The useful vertical range lies in the upper troposphere up to the mesosphere with an altitude resolution of 8 to 16 km and a horizontal resolution of about 57 km. Flight campaigns were performed once a year from 1998 to 2006 measuring the latitudinal distribution of water vapour from the tropics to the polar regions. The obtained profiles show clearly the main features of stratospheric water vapour in all latitudinal regions. Data are validated against a set of instruments comprising satellite, ground-based, airborne remote sensing and in-situ instruments. It appears that AMSOS profiles have a dry bias of 3–20%, when compared to satellite experiments. A good agreement with a difference of 3.3% was found between AMSOS and in-situ hygrosondes FISH and FLASH and an excellent matching of the lidar measurements from the DIAL instrument in the short overlap region in the upper troposphere.

  11. Atmospheric water distribution in a midlatitude cyclone observed by the Seasat Scanning Multichannel Microwave Radiometer

    Science.gov (United States)

    Mcmurdie, L. A.; Katsaros, K. B.

    1985-01-01

    Patterns in the horizontal distribution of integrated water vapor, integrated liquid water and rainfall rate derived from the Seasat Scanning Multichannel Microwave Radiometer (SMMR) during a September 10-12, 1978 North Pacific cyclone are studied. These patterns are compared with surface analyses, ship reports, radiosonde data, and GOES-West infrared satellite imagery. The SMMR data give a unique view of the large mesoscale structure of a midlatitude cyclone. The water vapor distribution is found to have characteristic patterns related to the location of the surface fronts throughout the development of the cyclone. An example is given to illustrate that SMMR data could significantly improve frontal analysis over data-sparse oceanic regions. The distribution of integrated liquid water agrees qualitatively well with corresponding cloud patterns in satellite imagery and appears to provide a means to distinguish where liquid water clouds exist under a cirrus shield. Ship reports of rainfall intensity agree qualitatively very well with SMMR-derived rainrates. Areas of mesoscale rainfall, on the order of 50 km x 50 km or greater are detected using SMMR derived rainrates.

  12. Microwave Radiometer Systems, Design and Analysis

    DEFF Research Database (Denmark)

    Skou, Niels; Vine, David Le

    Two important microwave remote sensors are the radar and the radiometer. There have been a number of books written on various aspects of radar, but there have been only a few written on microwave radiometers, especially on subjects of how to design and build radiometer systems. This book, which...

  13. Microwave Radiometer Systems, Design and Analysis

    DEFF Research Database (Denmark)

    Skou, Niels; Vine, David Le

    Two important microwave remote sensors are the radar and the radiometer. There have been a number of books written on various aspects of radar, but there have been only a few written on microwave radiometers, especially on subjects of how to design and build radiometer systems. This book, which...

  14. Dual Microwave Radiometer Experiment Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Marchand, Roger [Univ. of Washington, Seattle, WA (United States)

    2017-09-01

    Passive microwave radiometers (MWRs) are the most commonly used and accurate instruments the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Research Facility has to retrieve cloud liquid water path (LWP). The MWR measurements (microwave radiances or brightness temperatures) are often used to derive LWP using climatological constraints, but are frequently also combined with measurements from radar and other instruments for cloud microphysical retrievals. Nominally this latter approach improves the retrieval of LWP and other cloud microphysical quantities (such as effective radius or number concentration), but this also means that when MWR data are poor, other cloud microphysical quantities are also negatively affected. Unfortunately, current MWR data is often contaminated by water on the MWR radome. This water makes a substantial contribution to the measured radiance and typically results in retrievals of cloud liquid water and column water vapor that are biased high. While it is obvious when the contamination by standing water is large (and retrieval biases are large), much of the time it is difficult to know with confidence that there is no contamination. At present there is no attempt to estimate or correct for this source of error, and identification of problems is largely left to users. Typically users are advised to simply throw out all data when the MWR “wet-window” resistance-based sensor indicates water is present, but this sensor is adjusted by hand and is known to be temperamental. In order to address this problem, a pair of ARM microwave radiometers was deployed to the University of Washington (UW) in Seattle, Washington, USA. The radiometers were operated such that one radiometer was scanned under a cover that (nominally) prevents this radiometer radome from gathering water and permits measurements away from zenith; while the other radiometer is operated normally – open or uncovered - with the radome exposed to the sky

  15. A new airborne Ka-band double-antenna microwave radiometer for cloud liquid water content measurement

    Science.gov (United States)

    Sun, Jian; Zhao, Kai; Jiang, Tao; Gu, Lingjia

    2013-09-01

    A new type upward-looking airborne double-antenna microwave radiometer (ADAMR) system intended for detecting atmospheric cloud liquid water content (LWC) is developed in this paper. The frequency of this radiometer is 31.65 GHz. For the antenna elevation angle, one is 30°and the other is 90°. In order to detect the signals with low effective noise temperature (antenna ports respectively, the technique can elevate the small input noise signal power to the detectable range of the square-law detector and thus realize the weak signal detection. Moreover, in order to eliminate the impacts of the system gain fluctuations and obtain a higher sensitivity, an auto-gain compensation method based on the analog-to-digital converter, microcontroller and host computer software techniques is also proposed. Compared with the traditional radiometers, the radiometer topology is greatly simplified and the gain fluctuations can be readily realtime compensated using the compensation method. The laboratory test results show that radiometric sensitivity is better than 0.2 K for 300ms integration time and the instrument is conforming to specifications. Finally, the flight observation experiment results are presented to prove that the designed instrument is able to detect small changes of noise signal in a wide effective range of noise temperature (10-350K) and is a powerful tool for LWC measurement.

  16. Microwave Radiometer for Aviation Safety Project

    Data.gov (United States)

    National Aeronautics and Space Administration — SBIR Phase I Project proposes a new passive microwave airborne sensor for in flight icing hazard detection, Microwave Radiometer for Aviation Safety. A feasibility...

  17. Microwave Radiometer Linearity Measured by Simple Means

    DEFF Research Database (Denmark)

    Skou, Niels

    2002-01-01

    Modern spaceborne radiometer systems feature an almost perfect on-board calibration, hence the primary calibration task to be carried out before launch is a check of radiometer linearity. This paper describes two ways of measuring linearity of microwave radiometers only requiring relatively simple...

  18. Microwave Radiometry and Radiometers for Ocean Applications

    DEFF Research Database (Denmark)

    Skou, Niels

    2008-01-01

    The microwave radiometer system measures, within its bandwidth, the naturally emitted radiation – the brightness temperature – of substances within its antenna’s field of view. Thus a radiometer is really a sensitive and calibrated microwave receiver. The radiometer can be a basic total power...... aperture radiometer technique, both yielding imaging capability without scanning. Typical applications of microwave radiometry concerning oceans are: sea salinity, sea surface temperature, wind speed and direction, sea ice detection and classification. However, in an attempt to measure properties...

  19. Retrieval of Vertical Profiles of Liquid Water and Ice Content in Mixed Clouds from Doppler Radar and Microwave Radiometer Measurements.

    Science.gov (United States)

    Sauvageot, Henri

    1996-01-01

    A new method to retrieve vertical profiles of liquid water content Mw(z), ice water content Mi(z), and ice particle size distribution Ni(D, z), (where D is the ice particle size and z the vertical coordinate) in mixed nonprecipitating clouds using the observations of a zenith-viewing Doppler radar and of a microwave radiometer is proposed. In this method, the profile of the vertical air velocity deduced from Doppler radar measurements is used to describe the rate of production by the updrafts of water. vapor in excess of saturation with respect to ice. Using a Zi Mi power-law relation with an unknown linear parameter (let i, be this parameter) and initially assuming that Zw is negligible with respect to Zi, (where Zw and Zi are the radar reflectivity factors of liquid water and ice particles respectively), the measured radar reflectivity factor profile Zm ( Zi) is inverted to estimate Ni(D, z). From Ni(D, z), the profile of the rate of water vapor that can be consumed by pure deposition on ice particles is calculated. The difference between the rate of production of the exam water vapor and the rate of deposited water vapor is an expression of the rate of liquid water generation at each level. By writing that the integral of the liquid water along the profile has to be equal to the total liquid water deduced from the microwave radiometer measurement, an estimation of the i parameter is obtained. From i, an estimation of the profiles Mw(z), Mi(z), Zw(z), Zi(z) (=Zm Zw), and Ni(D, z) is calculated. If Zw is effectively negligible with respect to Zi, the computation of the retrieved profiles is ended. If not, Zi(z) is corrected and a new estimation of the profiles is computed. The results of the numerical simulation of the algorithm are presented.

  20. Advanced Microwave Radiometer (AMR) for SWOT mission

    Science.gov (United States)

    Chae, C. S.

    2015-12-01

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

  1. Microwave Radiometry and Radiometers for Ocean Applications

    DEFF Research Database (Denmark)

    Skou, Niels

    2008-01-01

    aperture radiometer technique, both yielding imaging capability without scanning. Typical applications of microwave radiometry concerning oceans are: sea salinity, sea surface temperature, wind speed and direction, sea ice detection and classification. However, in an attempt to measure properties...

  2. Validation of middle atmospheric campaign-based water vapour measured by the ground-based microwave radiometer MIAWARA-C

    Directory of Open Access Journals (Sweden)

    B. Tschanz

    2013-02-01

    Full Text Available Middle atmospheric water vapour can be used as a tracer for dynamical processes. It is mainly measured by satellite instruments and ground-based microwave radiometers. Ground-based instruments capable of measuring middle atmospheric water vapour are sparse but valuable as they complement satellite measurements, are relatively easy to maintain and have a long lifetime. MIAWARA-C is a ground-based microwave radiometer for middle atmospheric water vapour designed for use on measurement campaigns for both atmospheric case studies and instrument intercomparisons. MIAWARA-C's retrieval version 1.1 (v1.1 is set up in a way to provide a consistent data set even if the instrument is operated from different locations on a campaign basis. The sensitive altitude range for v1.1 extends from 4 hPa (37 km to 0.017 hPa (75 km. MIAWARA-C measures two polarisations of the incident radiation in separate receiver channels and can therefore provide two independent measurements of the same air mass. The standard deviation of the difference between the profiles obtained from the two polarisations is in excellent agreement with the estimated random error of v1.1. In this paper, the quality of v1.1 data is assessed during two measurement campaigns: (1 five months of measurements in the Arctic (Sodankylä, 67.37° N/26.63° E and (2 nine months of measurements at mid-latitudes (Zimmerwald, 46.88° N/7.46° E. For both campaigns MIAWARA-C's profiles are compared to measurements from the satellite experiments Aura MLS and MIPAS. In addition, comparisons to ACE-FTS and SOFIE are presented for the Arctic and to the ground-based radiometer MIAWARA for the mid-latitudinal campaign. In general all intercomparisons show high correlation coefficients, above 0.5 at altitudes above 45 km, confirming the ability of MIAWARA-C to monitor temporal variations on the order of days. The biases are generally below 10% and within the estimated systematic uncertainty of MIAWARA-C. No

  3. Microwave Radiometer – 3 Channel (MWR3C) Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Cadeddu, MP

    2012-05-04

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

  4. A Scanning Microwave Radar and Radiometer

    DEFF Research Database (Denmark)

    Skou, Niels

    1995-01-01

    The Scanning Microwave Radar and Radiometer (SMRR) is a line scanner featuring a combined radar and radiometer system operating around 35 and 94 GHz. The layout of the SMRR is shown. The 2 offset antenna parabolas scan in synchronism, the receiver antenna has the highest gain in order to ensure...... that footprints are identical for the radar and the radiometer. The instrument will be flown in a pod under a Gulfstream G3 normally cruising with 240 m/sec at 12500 m, and will thus be able to sense clouds and precipitation from above...

  5. Comparison of CloudSat Cloud Liquid Water Paths in Arctic Summer Using Ground-Based Microwave Radiometer

    Institute of Scientific and Technical Information of China (English)

    LIU Shuang; Georg Heygster; ZHANG Suping

    2010-01-01

    Arctic clouds strongly influence the regional radiation balance,temperature,melting of sea ice,and freezing of sea water.Despite their importance,there is a lack of systematic and reliable observations of Arctic clouds.The CloudSat satellite launched in 2006 with a 94 GHz Cloud Profiling Radar(CPR)may contribute to close this gap.Here we compare one of the key parameters,the cloud liquid water path(LWP)retrieved from CloudSat observations and from microwave radiometer(MWR)data taken during the ASCOS(Arctic Summer Cloud Ocean Study)cruise of the research vessel Oden from August to September 2008.Over the 45 days of the ASCOS cruise,collocations closer than 3 h and 100 km were found in only 9 d,and collocations closer than 1 h and 30 km in only 2 d.The poor correlations in the scatter plots of the two LWP retrievals can be explained by the patchiness of the cloud cover in these two days(August 5th and September 7th),as confirmed by coincident MODIS(Moderate-resolution Imaging Spectroradiometer)images.The averages of Oden-observed LWP values are systematically higher(40-70 g m-2)than the corresponding CloudSat observations(0-50 g m-2).These are cases of generally low LWP with presumably small droplets,and may be explained by the little sensitivity of the CPR to small droplets or by the surface clutter.

  6. Current status of the global change observation mission - water SHIZUKU (GCOM-W) and the advanced microwave scanning radiometer 2 (AMSR2) (Conference Presentation)

    Science.gov (United States)

    Maeda, Takashi; Kachi, Misako; Kasahara, Marehito

    2016-10-01

    Japan Aerospace Exploration Agency (JAXA) launched the Global Change Observation Mission - Water (GCOM-W) or "SHIZUKU" in 18 May 2012 (JST) from JAXA's Tanegashima Space Center. The GCOM-W satellite joins to NASA's A-train orbit since June 2012, and its observation is ongoing. The GCOM-W satellite carries the Advanced Microwave Scanning Radiometer 2 (AMSR2). The AMSR2 is a multi-frequency, total-power microwave radiometer system with dual polarization channels for all frequency bands, and successor microwave radiometer to the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) loaded on the NASA's Aqua satellite. The AMSR-E kept observation in the slower rotation speed (2 rotations per minute) for cross-calibration with AMSR2 since December 2012, its operation ended in December 2015. The AMSR2 is designed almost similarly as the AMSR-E. The AMSR2 has a conical scanning system with large-size offset parabolic antenna, a feed horn cluster to realize multi-frequency observation, and an external calibration system with two temperature standards. However, some important improvements are made. For example, the main reflector size of the AMSR2 is expanded to 2.0 m to observe the Earth's surface in higher spatial resolution, and 7.3-GHz channel is newly added to detect radio frequency interferences at 6.9 GHz. In this paper, we present a recent topic for the AMSR2 (i.e., RFI detection performances) and the current operation status of the AMSR2.

  7. Null-balancing microwave radiometer

    Science.gov (United States)

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

    1977-01-01

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

  8. Research on water ice content in Cabeus crater using the data from the microwave radiometer onboard Chang’e-1 satellite

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The existence, formation and content of water ice in the lunar permanently shaded region is one of the important questions for the current Moon study. On October 9, 2009, the LCROSS mission spacecraft impacted the Moon, and the initial result verified the existence of water on the Moon. But the study on formation and content of water ice is still under debate. The existence of water ice can change the dielectric constants of the lunar regolith, and a microwave radiometer is most sensitive to the dielectric parameters. Based on this, in this paper, the radiation transfer model is improved according to the simulation results in high frequency. Then the mixture dielectric constant models, including Odelevsky model, Wagner and landau-Lifshitz model, Clau-sius model, Gruggeman-Hanai model, etc., are analyzed and compared. The analyzing results indicate that the biggest difference occurs between Lichtenecker model and the improved Dobson model. The values estimated by refractive model are the second biggest in all the models. And the results from Odelevsky model, strong fluctuation model, Wagner and Landau –Lifshitz model, Clausius model and Bruggeman-Hanai model are very near to each other. Thereafter, the relation between volume water ice content and microwave brightness temperature is constructed with Odelevsky mixing dielectric model and the improved radiative transfer simulation, and the volume water ice content in Cabeus crater is retrieved with the data from microwave radiometer onboard Chang’e-1 satellite. The results present that the improved radiative transfer model is proper for the brightness temperature simulation of the one infinite regolith layer in high frequency. The brightness temperature in Cabeus crater is 69.93 K (37 GHz), and the corresponding volume water ice content is about 2.8%.

  9. Remote sensing techniques to measure dew: the detection of canopy water with an L-band passive microwave radiometer and a spectral reflectance sensor

    Science.gov (United States)

    De Jeu, Richard A. M.; Heusinkveld, Bert G.; Vugts, Hans; Holmes, Thomas R. H.; Owe, Manfred

    2004-10-01

    A technique to quantify the amount of dew on grassland with an L-band (1.4 GHz) passive microwave radiometer has been presented. The horizontal polarized brightness temperature is sensitive to dew and morning dew can increase the temperature up to 5 K. This is in contrary to recent published results, where they expect that dew does not have any effect on L band (1.4 GHz) observations. By using both the horizontal and vertical polarized brightness temperature in combination with measured soil moisture conditions we were able to estimate the amount of dew. The results compared well with another remote sensing technique to measure dew using a spectral reflectance sensor. In addition, a simple comparison study was done to study the sensitivity of the microwave emission on dew events and changes in internal water. This study showed that the microwave emission at L band is more sensitive to changes in dew than to changes in internal vegetation water content when the soil is wet. When the soil is dry, the microwave emission is more sensitive to internal vegetation water.

  10. Wide-Band Airborne Microwave and Millimeter-Wave Radiometers to Provide High-Resolution Wet-Tropospheric Path Delay Corrections for Coastal and Inland Water Altimetry

    Science.gov (United States)

    Reising, Steven C.; Kangaslahti, Pekka; Brown, Shannon T.; Tanner, Alan B.; Padmanabhan, Sharmila; Parashare, Chaitali; Montes, Oliver; Dawson, Douglas E.; Gaier, Todd C.; Khayatian, Behrouz; Bosch-Lluis, Xavier; Nelson, Scott P.; Johnson, Thaddeus; Hadel, Victoria; Gilliam, Kyle L.; Razavi, Behzad

    2013-04-01

    Current satellite ocean altimeters include nadir-viewing, co-located 18-34 GHz microwave radiometers to measure wet-tropospheric path delay. Due to the area of the surface instantaneous fields of view (IFOV) at these frequencies, the accuracy of wet path retrievals is substantially degraded near coastlines, and retrievals are not provided over land. Retrievals are flagged as not useful about 40 km from the world's coastlines. A viable approach to improve their capability is to add wide-band millimeter-wave window channels at 90 to 170 GHz, yielding finer spatial resolution for a fixed antenna size. In addition, NASA's Surface Water and Ocean Topography (SWOT) mission in formulation (Phase A) is planned for launch in late 2020. The primary objectives of SWOT are to characterize ocean sub-mesoscale processes on 10-km and larger scales in the global oceans, and to measure the global water storage in inland surface water bodies and the flow rate of rivers. Therefore, an important new science objective of SWOT is to transition satellite radar altimetry into the coastal zone. The addition of millimeter-wave channels near 90, 130 and 166 GHz to current Jason-class radiometers is expected to improve retrievals of wet-tropospheric delay in coastal areas and to enhance the potential for over-land retrievals. The Ocean Surface Topography Science Team Meeting recommended in 2012 to add these millimeter-wave channels to the Jason Continuity of Service (CS) mission. To reduce the risks associated with wet-tropospheric path delay correction over coastal areas and fresh water bodies, we are developing an airborne radiometer with 18.7, 23.8 and 34.0 GHz microwave channels, as well as millimeter-wave window channels at 90, 130 and 166 GHz, and temperature sounding above 118 as well as water vapor sounding below 183 GHz for validation of wet-path delay. For nadir-viewing space-borne radiometers with no moving parts, two-point internal calibration sources are necessary, and the

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

    Science.gov (United States)

    Reehorst, Andrew L.

    2001-01-01

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

  12. Microwave integrated circuit radiometer front-ends for the Push Broom Microwave Radiometer

    Science.gov (United States)

    Harrington, R. F.; Hearn, C. P.

    1982-01-01

    Microwave integrated circuit front-ends for the L-band, S-band and C-band stepped frequency null-balanced noise-injection Dicke-switched radiometer to be installed in the NASA Langley airborne prototype Push Broom Microwave Radiometer (PBMR) are described. These front-ends were developed for the fixed frequency of 1.413 GHz and the variable frequencies of 1.8-2.8 GHz and 3.8-5.8 GHz. Measurements of the noise temperature of these units were made at 55.8 C, and the results of these tests are given. While the overall performance was reasonable, improvements need to be made in circuit losses and noise temperatures, which in the case of the C-band were from 1000 to 1850 K instead of the 500 K specified. Further development of the prototypes is underway to improve performance and extend the frequency range.

  13. Microwave radiometer observations of soil moisture in HAPEX-SAHEL

    Science.gov (United States)

    Schmugge, Thomas J.; Chanzy, Andre; Kerr, Yann H.; van Oevelen, Peter

    1995-01-01

    Water stored in the soil serves as the reservoir for the evapotranspiration process, thus the interest in trying to map its spatial and temporal variations in experiments studying the soil- plant-atmosphere interactions at the GCM grid scale. During the 8 week intensive observation period (IOP) of HAPEX-Sahel (Hydrologic Atmospheric Pilot Experiment in the Sahel), this was done with two airborne microwave radiometer systems. The five frequency (5 to 90 GHz) PORTOS radiometer on the French ARAT aircraft and the single frequency (1.42 GHz) multibeam pushbroom microwave radiometer (PBMR) on the NASA C-130 were used. These aircraft measurements were supported by ground based observations at the central sites and, because of several rains during the IOP, covered a good range of soil wetness conditions that existed. The PBMR and the 5.05 GHz PORTOS channel in H polarization show a large dynamic range of TB on each day and between different days in response to variations in rainfall and drying conditions ranging from low TBs of 210 to 220 K for the wettest conditions to values of 280 to 290 K for the driest.

  14. A Microwave Radiometer for Internal Body Temperature Measurement

    Science.gov (United States)

    Scheeler, Robert Patterson

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

  15. Validation of middle-atmospheric campaign-based water vapour measured by the ground-based microwave radiometer MIAWARA-C

    Directory of Open Access Journals (Sweden)

    B. Tschanz

    2013-07-01

    Full Text Available Middle atmospheric water vapour can be used as a tracer for dynamical processes. It is mainly measured by satellite instruments and ground-based microwave radiometers. Ground-based instruments capable of measuring middle-atmospheric water vapour are sparse but valuable as they complement satellite measurements, are relatively easy to maintain and have a long lifetime. MIAWARA-C is a ground-based microwave radiometer for middle-atmospheric water vapour designed for use on measurement campaigns for both atmospheric case studies and instrument intercomparisons. MIAWARA-C's retrieval version 1.1 (v1.1 is set up in a such way as to provide a consistent data set even if the instrument is operated from different locations on a campaign basis. The sensitive altitude range for v1.1 extends from 4 hPa (37 km to 0.017 hPa (75 km. For v1.1 the estimated systematic error is approximately 10% for all altitudes. At lower altitudes it is dominated by uncertainties in the calibration, with altitude the influence of spectroscopic and temperature uncertainties increases. The estimated random error increases with altitude from 5 to 25%. MIAWARA-C measures two polarisations of the incident radiation in separate receiver channels, and can therefore provide two measurements of the same air mass with independent instrumental noise. The standard deviation of the difference between the profiles obtained from the two polarisations is in excellent agreement with the estimated random measurement error of v1.1. In this paper, the quality of v1.1 data is assessed for measurements obtained at two different locations: (1 a total of 25 months of measurements in the Arctic (Sodankylä, 67.37° N, 26.63° E and (2 nine months of measurements at mid-latitudes (Zimmerwald, 46.88° N, 7.46° E. For both locations MIAWARA-C's profiles are compared to measurements from the satellite experiments Aura MLS and MIPAS. In addition, comparisons to ACE-FTS and SOFIE are presented for the

  16. Multibeam 1.4-GHz Pushbroom Microwave Radiometer

    Science.gov (United States)

    Lawrence, Roland W.; Bailey, Marion C.; Harrington, Richard F.; Hearn, Chase P.; Wells, John G., Jr.; Stanley, William L.

    1990-01-01

    Airborne prototype of multiple-beam pushbroom microwave radiometer (PBMR) developed to advance radiometric technology necessary for remote sensing of geophysical parameters. Instrument used in several joint Langley Research Center/United States Department of Agriculture soil-moisture flight experiments in Virginia, Texas, and California. Data from experiments used to modify, develop, and verify algorithms used to predict soil moisture from remote-sensing measurements. Image data useful in study of effects of characters of beams on radiometer imaging data.

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

    Science.gov (United States)

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

    1992-01-01

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

  18. Source analysis of spaceborne microwave radiometer interference over land

    Institute of Scientific and Technical Information of China (English)

    Li GUAN; Sibo ZHANG

    2016-01-01

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

  19. Source analysis of spaceborne microwave radiometer interference over land

    Science.gov (United States)

    Guan, Li; Zhang, Sibo

    2016-03-01

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

  20. Comparison of time series of integrated water vapor measured using radiosonde, GPS and microwave radiometer at the CNR-IMAA Atmospheric Observatory

    Science.gov (United States)

    Amato, Franceso; Rosoldi, Marco; Madonna, Fabio

    2015-04-01

    . radiosondes (processed using GRUAN processing algorithm); 4. a microwave radiometer (data processed using a retrieval based on a neural network). F. Amato, M. Rosoldi, and F. Madonna Consiglio Nazionale delle Ricerche, Istituto di Metodologie per l'Analisi Ambientale (CNR-IMAA), Tito Scalo, Potenza, Italy Information about the amount and spatial distribution of atmospheric water vapor is essential to improve our knowledge of weather forecasting and climate change. Water vapor is highly variable in space and time depending on the complex interplay of several phenomena like convection, precipitation, turbulence, etc. It remains one of the most poorly characterized meteorological parameters. Remarkable progress in using of Global Navigation Satellite Systems (GNSS), in particular GPS, for the monitoring of atmospheric water vapor has been achieved during the last decades. Various studies have demonstrated that GPS could provide accurate water vapor estimates for the study of the atmosphere. Different GPS data processing provided within the scientific community made use of various tropospheric models that primarily differs for the assumptions on the vertical refractivity profiles and the mapping of the vertical delay with elevation angles. This works compares several models based on the use of surface meteorological data. In order to calculate the Integrated Water Vapour (IWV), an algorithm for calculating the zenith tropospheric delay was implemented. It is based upon different mapping functions (Niell, Saastamoinen, Chao and Herring Mapping Functions). Observations are performed at the Istituto di Metodologie per l'Analisi Ambientale (IMAA) GPS station located in Tito Scalo, Potenza (40.60N, 15.72E), from July to December 2014, in the framework of OSCAR project (Observation System for Climate Application at Regional scale). The retrieved values of the IWV using the GPS are systematically compared with the other estimation of IWV collected at CIAO (CNR-IMAA Atmospheric

  1. Underlying Surface Remote Sensing by the Microwave Radiometer with High Measurement Rate

    Directory of Open Access Journals (Sweden)

    Ubaichin Anton

    2016-01-01

    Full Text Available The paper describes a new approach to microwave radiometer design. The approach implies simultaneous using both modified zero measurement method and multi-receiver technique. Simultaneous using increases the operating characteristics of airborne microwave radiometers for aircrafts with self-contained power supply. The block diagram of the onboard Earth remote sensing microwave radiometric system is presented. The block diagram and operating timing diagrams of the designed radiometer are shown. An original technique to design a fiducial noise source for transfer characteristics is discussed. The advantages of the designed radiometer in comparison with the state of the art zero-type microwave radiometer are described.

  2. The Atmospheric Radiation Measurement (ARM program network of microwave radiometers: instrumentation, data, and retrievals

    Directory of Open Access Journals (Sweden)

    M. P. Cadeddu

    2013-04-01

    Full Text Available The Climate Research Facility of the US Department of Energy's Atmospheric Radiation Measurement (ARM Program operates a network of ground-based microwave radiometers. Data and retrievals from these instruments have been available to the scientific community for almost 20 yr. In the past five years the network has been expanded to include a total of 22 microwave radiometers deployed in various locations around the world. The new instruments cover a frequency range between 22 and 197 GHz and are consistently and automatically calibrated. The latest addition to the network is a new generation of three-channel radiometers currently in the early stage of deployment at all ARM sites. The network has been specifically designed to achieve increased accuracy in the retrieval of precipitable water vapor (PWV and cloud liquid water path (LWP with the long-term goal of providing the scientific community with reliable, calibrated radiometric data and retrievals of important geophysical quantities with well-characterized uncertainties. The radiometers provide high-quality, continuous datasets that can be utilized in a wealth of applications and scientific studies. This paper presents an overview of the microwave instrumentation, calibration procedures, data, and retrievals that are available for download from the ARM data archive.

  3. Design and Development of the SMAP Microwave Radiometer Electronics

    Science.gov (United States)

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

    2014-01-01

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

  4. Diurnal Difference Vegetation Water Content (ddVWC) of Advance Microwave Scanning Radiometer-Earth Observing System (AMSR-E) for assessment of crop water stress at regional level

    Science.gov (United States)

    Chakraborty, A.; Sesha Sai, M. V. R.

    2014-11-01

    Advance Microwave Scanning Radiometer - Earth Observing System (AMSR-E) derived Vegetation Water Content (VWC) at predawn (01:30 LST, descending pass) and afternoon (13:30 LST; ascending pass) were used to assess crop water stress condition over the selected meteorological subdivisions of India. The temporal profile of Normalized Difference Vegetation Index (NDVI) was used to study the progression of crop growth. The Diurnal Difference Vegetation Water Content (ddVWC) was found to be sensitive to rainfall patterns (wet/dry spell) particularly in moderate to full crop cover condition (NDVI > 0.4). The ddVWC was found to be significantly (p = 0.05) correlated with the rainfall over the rainfed regions. The ddVWC was further characterized to represent different categories of crop water stress considering irrigated flooded rice crop as a benchmark. Inter year comparative analysis of temporal variations of the ddVWC revealed its capability to differentiate normal (2005) and sub-normal years (2008 and 2009) in term of intensity and persistence of crop water stress. Spatio-temporal patterns of ddVWC could capture regional progression of crop water stress at high temporal resolution in near real time.

  5. Estimating atmospheric temperature profile by an airborne microwave radiometer

    Science.gov (United States)

    Zhang, Jun; Xu, Jian; Kenntner, Mareike; Schreier, Franz; Doicu, Adrian

    2017-04-01

    As the rising atmospheric issues such as climate change, air pollution, and ozone depletion have extracted extensive attraction worldwide, observing and modeling of atmospheric quantities becomes critical to our understanding of the environment. This work focuses on the performance of an airborne passive microwave radiometer called MTP (Microwave Temperature Profiler). We aim to obtain vertically distributed atmospheric temperature from intensities measured by the instrument in terms of three frequencies and ten viewing angles. A retrieval program TIRAMISU (Temperature InveRsion Algorithm for MIcrowave SoUnding) has been utilized for processing the MTP data. To solve this severely ill-posed inverse problem, an analysis of different ways of constructing the penalty term onto the Tikhonov-type objective function is conducted. This numerical analysis can help us to better understand pros and cons of these regularization methods and to investigate the measurement capabilities of MTP.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-01-26

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

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

    Science.gov (United States)

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

    1984-06-01

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

  8. Limits of Precipitation Detection from Microwave Radiometers and Sounders

    Science.gov (United States)

    Munchak, S. J.; Skofronick-Jackson, G.; Johnson, B. T.

    2012-04-01

    The Global Precipitation Measurement (GPM) mission will unify and draw from numerous microwave conical scanning imaging radiometers and cross-track sounders, many of which already in operation, to provide near real-time precipitation estimates worldwide at 3-hour intervals. Some of these instruments were designed for primary purposes unrelated to precipitation remote sensing. Therefore it is worthwhile to evaluate the strengths and weaknesses of each set of channels with respect to precipitation detection to fully understand their role in the GPM constellation. The GPM radiometer algorithm will use an observationally-based Bayesian retrieval with common databases of precipitation profiles for all sensors. Since these databases are still under development and will not be truly complete until the GPM core satellite has completed at least one year of dual-frequency radar observations, a screening method based upon retrieval of non-precipitation parameters related to the surface and atmospheric state is used in this study. A cost function representing the departure of modeled radiances from their observed values plus the departure of surface and atmospheric parameters from the TELSEM emissivity atlas and MERRA reanalysis is used as an indicator of precipitation. Using this method, two datasets are used to evaluate precipitation detection: One year of matched AMSR-E and AMSU-B/MHS overpasses with CloudSat used as validation globally; and SSMIS overpasses over the United States using the National Mosaic and QPE (NMQ) as validation. The Heidke Skill Score (HSS) is used as a metric to evaluate detection skill over different surfaces, seasons, and across different sensors. Non-frozen oceans give the highest HSS for all sensors, followed by bare land and coasts, then snow-covered land and sea ice. Negligible skill is present over ice sheets. Sounders tend to have higher skill than imagers over complex surfaces (coast, snow, and sea ice), whereas imagers have higher skill

  9. A One-Dimensional Synthetic-Aperture Microwave Radiometer

    Science.gov (United States)

    Doiron, Terence; Piepmeier, Jeffrey

    2010-01-01

    A proposed one-dimensional synthetic- aperture microwave radiometer could serve as an alternative to either the two-dimensional synthetic-aperture radiometer described in the immediately preceding article or to a prior one-dimensional one, denoted the Electrically Scanned Thinned Array Radiometer (ESTAR), mentioned in that article. The proposed radiometer would operate in a pushbroom imaging mode, utilizing (1) interferometric cross-track scanning to obtain cross-track resolution and (2) the focusing property of a reflector for along-track resolution. The most novel aspect of the proposed system would be the antenna (see figure), which would include a cylindrical reflector of offset parabolic cross section. The reflector could be made of a lightweight, flexible material amenable to stowage and deployment. Other than a stowage/deployment mechanism, the antenna would not include moving parts, and cross-track scanning would not entail mechanical rotation of the antenna. During operation, the focal line, parallel to the cylindrical axis, would be oriented in the cross-track direction, so that placement of receiving/radiating elements at the focal line would afford the desired along-track resolution. The elements would be microwave feed horns sparsely arrayed along the focal line. The feed horns would be oriented with their short and long cross-sectional dimensions parallel and perpendicular, respectively, to the cylindrical axis to obtain fan-shaped beams having their broad and narrow cross-sectional dimensions parallel and perpendicular, respectively, to the cylindrical axis. The interference among the beams would be controlled in the same manner as in the ESTAR to obtain along-cylindrical- axis (cross-track) resolution and cross-track scanning.

  10. Airborne Demonstration of Microwave and Wide-Band Millimeter-Wave Radiometers to Provide High-Resolution Wet-Tropospheric Path Delay Corrections for Coastal and Inland Water Altimetry

    Science.gov (United States)

    Reising, Steven; Kangaslahti, Pekka; Tanner, Alan; Padmanabhan, Sharmila; Montes, Oliver; Parashare, Chaitali; Bosch-Lluis, Xavier; Hadel, Victoria; Johnson, Thaddeus; Brown, Shannon; Khayatian, Behrouz; Dawson, Douglas; Gaier, Todd; Razavi, Behzad

    2014-05-01

    Current satellite ocean altimeters include nadir-viewing, co-located 18-34 GHz microwave radiometers to measure wet-tropospheric path delay. Due to the size of the surface instantaneous fields of view (IFOV) at these frequencies, the accuracy of wet path retrievals is substantially degraded near coastlines, and retrievals are not provided over land. Retrievals are flagged as not useful within approximately 40 km of the world's coastlines. A viable approach to improve their capability is to add wide-band high-frequency millimeter-wave window channels in the 90-180 GHz band, thereby achieving finer spatial resolution for a limited antenna size. In this context, the upcoming NASA/CNES/CSA Surface Water and Ocean Topography (SWOT) mission is in formulation and planned for launch in late 2020. The primary objectives of SWOT are to characterize ocean mesoscale and sub-mesoscale processes on 10-km and larger scales in the global oceans and provide measurements of the global water storage in inland surface water bodies and the flow rate of rivers. Therefore, an important new science objective of SWOT is to transition satellite altimetry from the open ocean into the coastal zone and over inland water. The addition of 90-180 GHz millimeter-wave window-channel radiometers to current Jason-class 18-34 GHz radiometers is expected to improve retrievals of wet-tropospheric delay in coastal areas and to enhance the potential for over-land retrievals. In 2012 the Ocean Surface Topography Science Team Meeting recommended to add high-frequency millimeter-wave radiometers to the Jason Continuity of Service (CS) mission. To reduce the risks of wet-tropospheric path delay measurement over coastal areas and inland water bodies, we have designed, developed and fabricated a new airborne radiometer, combining three high-frequency millimeter-wave window channels at 90, 130 and 168 GHz, along with Jason-series microwave channels at 18.7, 23.8 and 34.0 GHz, and validation channels sounding

  11. COBE Differential Microwave Radiometers - Instrument design and implementation

    Science.gov (United States)

    Smoot, G.; Bennett, Charles; Weber, R.; Maruschak, John; Ratliff, Roger; Janssen, M.

    1990-01-01

    Differential Microwave Radiometers (DMRs) at frequencies of 31.5, 53, and 90 GHz have been designed and built to map the large angular scale variations in the brightness temperature of the cosmic microwave background radiation. The instrument is being flown aboard NASA's Cosmic Background Explorer (COBE) satellite, launched on November 18, 1989. Each receiver input is switched between two antennas pointing 60 deg apart on the sky. The satellite is in near-polar orbit with the orbital plane precessing at 1 deg per day, causing the beams to scan the entire sky in 6 months. In 1 year of observation, the instruments are capable of mapping the sky to an rms sensitivity of 0.1 mK per 7 deg field of view. The mission and the instrument have been carefully designed to minimize the need for systematic corrections to the data.

  12. GHRSST Level 2P Global Subskin Sea Surface Temperature from the Advanced Microwave Scanning Radiometer 2 on the GCOM-W satellite (GDS version 2)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Advanced Microwave Scanning Radiometer 2 (AMSR2) was launched on 18 May 2012, onboard the Global Change Observation Mission - Water (GCOM-W) satellite developed...

  13. Island based radar and microwave radiometer measurements of stratus cloud parameters during the Atlantic Stratocumulus Transition Experiment (ASTEX)

    Energy Technology Data Exchange (ETDEWEB)

    Frisch, A.S. [Colorado State Univ., Fort Collins, CO (United States); Fairall, C.W.; Snider, J.B. [NOAA Environmental Technology Lab., Boulder, CO (United States); Lenshow, D.H.; Mayer, S.D. [National Center for Atmospheric Research, Boulder, CO (United States)

    1996-04-01

    During the Atlantic Stratocumulus Transition Experiment (ASTEX) in June 1992, simultaneous measurements were made with a vertically pointing cloud sensing radar and a microwave radiometer. The radar measurements are used to estimate stratus cloud drizzle and turbulence parameters. In addition, with the microwave radiometer measurements of reflectivity, we estimated the profiles of cloud liquid water and effective radius. We used radar data for computation of vertical profiles of various drizzle parameters such as droplet concentration, modal radius, and spread. A sample of these results is shown in Figure 1. In addition, in non-drizzle clouds, with the radar and radiometer we can estimate the verticle profiles of stratus cloud parameters such as liquid water concentration and effective radius. This is accomplished by assuming a droplet distribution with droplet number concentration and width constant with height.

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

    Science.gov (United States)

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

    2016-04-01

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

  15. Simultaneous Estimation of Geophysical Parameters with Microwave Radiometer Data based on Accelerated Simulated Annealing: SA

    Directory of Open Access Journals (Sweden)

    Kohei Arai

    2012-07-01

    Full Text Available Method for geophysical parameter estimations with microwave radiometer data based on Simulated Annealing: SA is proposed. Geophysical parameters which are estimated with microwave radiometer data are closely related each other. Therefore simultaneous estimation makes constraints in accordance with the relations. On the other hand, SA requires huge computer resources for convergence. In order to accelerate convergence process, oscillated decreasing function is proposed for cool down function. Experimental results show that remarkable improvements are observed for geophysical parameter estimations.

  16. Network operability of ground-based microwave radiometers: Calibration and standardization efforts

    Science.gov (United States)

    Pospichal, Bernhard; Löhnert, Ulrich; Küchler, Nils; Czekala, Harald

    2017-04-01

    Ground-based microwave radiometers (MWR) are already widely used by national weather services and research institutions all around the world. Most of the instruments operate continuously and are beginning to be implemented into data assimilation for atmospheric models. Especially their potential for continuously observing boundary-layer temperature profiles as well as integrated water vapor and cloud liquid water path makes them valuable for improving short-term weather forecasts. However until now, most MWR have been operated as stand-alone instruments. In order to benefit from a network of these instruments, standardization of calibration, operation and data format is necessary. In the frame of TOPROF (COST Action ES1303) several efforts have been undertaken, such as uncertainty and bias assessment, or calibration intercomparison campaigns. The goal was to establish protocols for providing quality controlled (QC) MWR data and their uncertainties. To this end, standardized calibration procedures for MWR have been developed and recommendations for radiometer users compiled. Based on the results of the TOPROF campaigns, a new, high-accuracy liquid-nitrogen calibration load has been introduced for MWR manufactured by Radiometer Physics GmbH (RPG). The new load improves the accuracy of the measurements considerably and will lead to even more reliable atmospheric observations. Next to the recommendations for set-up, calibration and operation of ground-based MWR within a future network, we will present homogenized methods to determine the accuracy of a running calibration as well as means for automatic data quality control. This sets the stage for the planned microwave calibration center at JOYCE (Jülich Observatory for Cloud Evolution), which will be shortly introduced.

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

    Science.gov (United States)

    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.

  18. An RFI Detection Algorithm for Microwave Radiometers Using Sparse Component Analysis

    Science.gov (United States)

    Mohammed-Tano, Priscilla N.; Korde-Patel, Asmita; Gholian, Armen; Piepmeier, Jeffrey R.; Schoenwald, Adam; Bradley, Damon

    2017-01-01

    Radio Frequency Interference (RFI) is a threat to passive microwave measurements and if undetected, can corrupt science retrievals. The sparse component analysis (SCA) for blind source separation has been investigated to detect RFI in microwave radiometer data. Various techniques using SCA have been simulated to determine detection performance with continuous wave (CW) RFI.

  19. Evaluating the quality of ground-based microwave radiometer measurements and retrievals using detrended fluctuation and spectral analysis methods

    CERN Document Server

    Ivanova, K; Shirer, H N; Ackerman, T P; Liljegren, J C; Ausloos, M

    2001-01-01

    Time series both of microwave radiometer brightness temperature measurements at 23.8 and 31.4 GHz and of retrievals of water vapor and liquid water path from these brightness temperatures are evaluated using the detrended fluctuation analysis method. As quantified by the parameter $\\alpha$, this method (i) enables identification of the time scales over which noise dominates the time series and (ii) characterizes the temporal range of correlations in the time series. The more common spectral analysis method is also used to assess the data and its results are compared with those from detrended fluctuation analysis method. The assumption that measurements should have certain scaling properties allows the quality of the measurements to be characterized. The additional assumption that the scaling properties of the measurements of an atmospheric quantity are preserved in a useful retrieval provides a means for evaluating the retrieval itself. Applying these two assumptions to microwave radiometer measurements and r...

  20. Low Power Silicon Germanium Electronics for Microwave Radiometers

    Science.gov (United States)

    Doiron, Terence A.; Krebs, Carolyn (Technical Monitor)

    2001-01-01

    Space-based radiometric observations of key hydrological parameters (e.g., soil moisture) at the spatial and temporal scales required in the post-2002 era face significant technological challenges. These measurements are based on relatively low frequency thermal microwave emission (at 1.4 GHz for soil moisture and salinity, 10 GHz and up for precipitation, and 19 and 37 GHz for snow). The long wavelengths at these frequencies coupled with the high spatial and radiometric resolutions required by the various global hydrology communities necessitate the use of very large apertures (e.g., greater than 20 m at 1.4 GHz) and highly integrated stable RF electronics on orbit. Radio-interferometric techniques such as Synthetic Thinned Array Radiometry (STAR), using silicon germanium (SiGe) low power radio frequency integrated circuits (RFIC), is one of the most promising technologies to enable very large non-rotating apertures in space. STAR instruments are composed of arrays of small antenna/receiving elements that are arranged so that the collecting area is smaller than an equivalent real aperture system, allowing very high packing densities for launch. A 20 meter aperture at L-band, for example, will require greater than 1000 of these receiving elements. SiGe RFIC's reduce power consumption enough to make an array like this possible in the power-limited environment of space flight. An overview of the state-of-the-art will be given, and current work in the area of SiGe radiometer development for soil moisture remote sensing will be discussed.

  1. On the Long-Term Stability of Microwave Radiometers Using Noise Diodes for Calibration

    Science.gov (United States)

    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.

  2. Modeling of Polar Precipitation with CloudSat, AIRS and High Frequency Microwave Radiometers

    Science.gov (United States)

    Turk, F. J.; Park, K.; Wang, N.; Haddad, Z. S.

    2009-12-01

    While measuring and monitoring precipitation in polar regions is difficult, recent studies have shown that microwave radiances measured by operational high-frequency sounders, such as the Advanced Microwave Sounding Unit (AMSU) and the Microwave Humidity Sounder (MHS), are sensitive to falling snow, though the frozen surface makes it very difficult to retrieve snowfall rates from these radiometric measurements. Since the microwave sounding channels are sensitive to the variable surface emissivity, the crucial step was to classify these data according to fractional ice coverage (derived from AMSR-E) and use principal component analyses to further separate the variations due to the radiometric signatures of the precipitation from that of the surface. These results quantify the correlation between the higher principal components of the microwave radiances and the CloudSat radar reflectivity profile. Further radiative transfer modeling of the polar atmosphere is done using the AIRS temperature and moisture profiles to specify the background atmosphere. We relate the simulated microwave radiances to the near-surface precipitation itself, by considering several hydrometeor habit and size distributions and super-cooled cloud liquid fractions, performing reflectivity-to-snow-content retrievals from the CloudSat radar profiles of ice and liquid water content.. With this methodology, one can simulate polar precipitation observations systematically utilizing these time/space matched measurements from the CloudSat radar and polar-orbiting high-frequency radiometers such as MHS or the SSMIS. In turn, this will help evaluate the realism of numerical models and their microphysical assumptions, particularly as the latter appear to have significant difficulties representing Arctic clouds accurately.

  3. 1D-Var temperature retrievals from microwave radiometer and convective scale model

    Directory of Open Access Journals (Sweden)

    Pauline Martinet

    2015-12-01

    Full Text Available This paper studies the potential of ground-based microwave radiometers (MWR for providing accurate temperature retrievals by combining convective scale numerical models and brightness temperatures (BTs. A one-dimensional variational (1D-Var retrieval technique has been tested to optimally combine MWR and 3-h forecasts from the French convective scale model AROME. A microwave profiler HATPRO (Humidity and Temperature PROfiler was operated during 6 months at the meteorological station of Bordeaux (Météo France. MWR BTs were monitored against simulations from the Atmospheric Radiative Transfer Simulator 2 radiative transfer model. An overall good agreement was found between observations and simulations for opaque V-band channels but large errors were observed for channels the most affected by liquid water and water vapour emissions (51.26 and 52.28 GHz. 1D-Var temperature retrievals are performed in clear-sky and cloudy conditions using a screening procedure based on cloud base height retrieval from ceilometer observations, infrared radiometer temperature and liquid water path derived from the MWR observations. The 1D-Var retrievals were found to improve the AROME forecasts up to 2 km with a maximum gain of approximately 50 % in root-mean-square-errors (RMSE below 500 m. They were also found to outperform neural network retrievals. A static bias correction was proposed to account for systematic instrumental errors. This correction was found to have a negligible impact on the 1D-Var retrievals. The use of low elevation angles improves the retrievals up to 12 % in RMSE in cloudy-sky in the first layers. The present implementation achieved a RMSE with respect to radiosondes within 1 K in clear-sky and 1.3 K in cloudy-sky conditions for temperature.

  4. Short-term Prediction and Detection of Dynamic Atmospheric Effects by Microwave Radiometer

    Directory of Open Access Journals (Sweden)

    P. Dvorak

    2012-12-01

    Full Text Available Specific utilization of a microwave radiometer for online monitoring, detection and, especially, prediction of particular dynamic atmospheric effects such as precipitation and cloudiness is proposed in the paper. The ground-based microwave radiometer and meteorological stations were incorporated into the measurement campaign in order to observe actual brightness temperature changes. The characteristics of atmospheric parameters recorded over a period of 14 months were evaluated and new applications for rain forecasting and cloud detection, based on signal variance, were proposed and validated.

  5. Retrievals on Tropical small scale humidity variability from multi-channel microwave radiometer

    Science.gov (United States)

    Zhang, Jianhao; Zuidema, Paquita; Turner, David

    2016-04-01

    Small-scale atmospheric humidity structure is important to many atmospheric process studies. In the Tropics especially, convection is sensitive to small variations in humidity. High temporal-resolution humidity profiles and spatially-resolved humidity fields are valuable for understanding the relationship of convection to tropical humidity, such as at convectively-induced cold pools and as part of the shallow-to-deep cloud transition. Radiosondes can provide high resolution vertical profiles of temperature and humidity, but are relatively infrequent. Microwave radiometers (MWR) are able to profile and scan autonomously and output measurements frequently (~1 Hz). To date, few assessments of microwave humidity profiling in the Tropics have been undertaken. Löhnert et al. (2009) provide one evaluation for Darwin, Australia. We build on this using four months of data from the equatorial Indian Ocean, at Gan Island, collected from University of Miami's (UM) multi-channel radiometer during the Dynamics of Madden-Julian Oscillation (DYNAMO) field campaign. Liquid Water Path (LWP) and Water Vapor Path (WVP) are physically retrieved using the MWR RETrieval (MWRRET) algorithm (Turner et al., 2007b), and humidity profiles in the tropics are retrieved using the Integrated Profiling Technique (Löhnert et al., 2004). Tropical temperature variability is weak and a climatological temperature profile is assumed, with humidity information drawn from five channels between 22 to 30 GHz. Scanning measurements were coordinated with the scanning pattern of NCAR's S-Pol-Ka radar. An analysis of the humidity information content gathered from both the profiling and scanning measurements will be presented.

  6. Geosynchronous Microwave Atmospheric Sounding Radiometer (MASR) feasibility studies. Volume 1: Management summary

    Science.gov (United States)

    1978-01-01

    The mission of the microwave atmospheric sounding radiometer (MASR) is to collect data to aid in the observation and prediction of severe storms. The geosynchronous orbit allows the continuous atmospheric measurement needed to resolve mesoscale dynamics. The instrument may operate in conjunction with this document, Volume 1 - Management, which summarizes the highlights of final reports on both the radiometer instrument and antenna studies. The radiometer instrument summary includes a synopsis of Volume 2 - Radiometer Receiver Feasibility, including design, recommended configuration, performance estimates, and weight and power estimates. The summary of the antenna study includes a synopsis of Volume 3 - Antenna Feasibility, including preliminary design tradeoffs, performance of selected design, and details of the mechanical/thermal design.

  7. An optimal estimation algorithm to derive Ice and Ocean parameters from AMSR Microwave radiometer observations

    DEFF Research Database (Denmark)

    Pedersen, Leif Toudal; Tonboe, Rasmus T.; Høyer, Jacob

    Global multispectral microwave radiometer measurements have been available for several decades. However, most current sea ice concentration algorithms still only takes advantage of a very limited subset of the available channels. Here we present a method that allows utilization of all available...

  8. Evaluation of brightness temperature from a forward model of ground-based microwave radiometer

    Indian Academy of Sciences (India)

    S Rambabu; J S Pillai; A Agarwal; G Pandithurai

    2014-06-01

    Ground-based microwave radiometers are getting great attention in recent years due to their capability to profile the temperature and humidity at high temporal and vertical resolution in the lower troposphere. The process of retrieving these parameters from the measurements of radiometric brightness temperature () includes the inversion algorithm, which uses the background information from a forward model. In the present study, an algorithm development and evaluation of this forward model for a ground-based microwave radiometer, being developed by Society for Applied Microwave Electronics Engineering and Research (SAMEER) of India, is presented. Initially, the analysis of absorption coefficient and weighting function at different frequencies was made to select the channels. Further the range of variation of for these selected channels for the year 2011, over the two stations Mumbai and Delhi is discussed. Finally the comparison between forward-model simulated s and radiometer measured s at Mahabaleshwar (73.66°E and 17.93°N) is done to evaluate the model. There is good agreement between model simulations and radiometer observations, which suggests that these forward model simulations can be used as background for inversion models for retrieving the temperature and humidity profiles.

  9. Retrievals of atmospheric parameters from radiances obtained by the Juno Microwave Radiometer

    Science.gov (United States)

    Li, C.; Ingersoll, A. P.; Janssen, M. A.

    2016-12-01

    The Juno microwave radiometer (MWR) makes a north-south scan of Jupiter on every perijove pass of the spacecraft (Fig. 1). The planet is observed in six channels, at wavelengths ranging from 1.3 cm to 50 cm, the peaks of whose weighting functions range from 0.6 bars to 30 bars, respectively. Within 25 degrees of the equator each latitude band 1 degree wide is observed at 5-10 different emission angles. Intermediate processing involves conversion of electrical signals into radiances, subtraction of the side lobe contributions, and deconvolution to achieve maximum spatial resolution. After that, one wants to convert the radiances into physical parameters of the atmosphere, all as functions of latitude. The two main goals of the MWR are (1) to determine the global water and ammonia abundances and (2) to document the latitude variations of water, ammonia, and temperature in the subcloud regions, in effect, to observe the deep Jovian weather. Prior probability is based on the Galileo probe results at 6 degrees north latitude, VLA maps at wavelengths shorter than 7 cm, and moist adiabats calculated from assumed deep abundances of water and ammonia. A complication is that ammonia dominates the microwave opacity, and water is detectable mainly through its effect on the temperature profile and the slope of the moist adiabat. MCMC analysis of synthetic data suggests that the radiances and limb-darkening parameters contain at most 4 pieces of information about the atmosphere at each latitude. Choosing the right parameters is the heart of the effort, and we will report on testing the choices using synthetic and real data. If we have preliminary results concerning objectives (1) and (2) above, we will share them.

  10. Modeling the frequency response of microwave radiometers with QUCS

    Science.gov (United States)

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

    2010-12-01

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

  11. Modeling the frequency response of microwave radiometers with QUCS

    Energy Technology Data Exchange (ETDEWEB)

    Zonca, A; Williams, B; Rubin, I; Meinhold, P; Lubin, P [Department of Physics, University of California, Santa Barbara, Santa Barbara, CA 93106 (United States); Roucaries, B [Universite Paris-Est, Laboratoire Central des Ponts et Chaussees, 75732 Paris (France); D' Arcangelo, O [IFP-CNR, via Cozzi 53, 20125 Milano (Italy); Franceschet, C; Mennella, A; Bersanelli, M [Dipartimento di Fisica, Universita degli Studi di Milano, Via Celoria 16, 20133 Milano (Italy); Jahn, S, E-mail: zonca@deepspace.ucsb.edu [Infineon Technologies AG, Am Campeon 1-12, 85579 Neubiberg, Munich (Germany)

    2010-12-15

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

  12. Development of Breakthrough Technology for Spaceflight Microwave Radiometers? RFI Noise Detection and Mitigation Based on the HHT2 Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Microwave active/passive radiometer is the premier instrument for remote sensing of Earth. However, it carries the price of non-linear response by its horn-receiver...

  13. Modeling the frequency response of microwave radiometers with QUCS

    CERN Document Server

    Zonca, Andrea; Williams, Brian; Rubin, Ishai; D'Arcangelo, Ocleto; Meinhold, Peter; Lubin, Philip; Franceschet, Cristian; Yahn, Stefan; Mennella, Aniello; Bersanelli, Marco

    2010-01-01

    Characterization of the frequency response of coherent radiometric receivers is a key element in estimating the flux of astrophysical emissions, since the measured signal depends on the convolution of the source spectral emission with the instrument band shape. Laboratory Radio Frequency (RF) measurements of the instrument bandpass often require complex test setups and are subject to a number of systematic effects driven by thermal issues and impedance matching, particularly if cryogenic operation is involved. In this paper we present an approach to modeling radiometers bandpasses by integrating simulations and RF measurements of individual components. This method is based on QUCS (Quasi Universal Circuit Simulator), an open-source circuit simulator, which gives the flexibility of choosing among the available devices, implementing new analytical software models or using measured S-parameters. Therefore an independent estimate of the instrument bandpass is achieved using standard individual component measureme...

  14. Modeling the Potential Effects of Virga on the Microwave Emission from the Jovian Atmosphere in Support of the Juno Microwave Radiometer (MWR)

    Science.gov (United States)

    Bellotti, Amadeo; Steffes, Paul

    2016-10-01

    The Juno Microwave Radiometer (MWR) has six channels ranging from 1.36-50 cm, and has the ability to peer deep into the Jovian atmosphere. With the potential to probe as deep as 1000 bars, the Juno MWR will probe well beneath the water clouds. To support necessary cloud depletion, precipitation will likely occur at some time and location over the Jovian disk. A model for potential precipitation effects has been developed and the resulting effects have been analyzed. The studies show a potential for identifying precipitation below the aqueous ammonia cloud using the MWR onboard the Juno spacecraft.

  15. Weight estimates and packaging techniques for the microwave radiometer spacecraft. [shuttle compatible design

    Science.gov (United States)

    Jensen, J. K.; Wright, R. L.

    1981-01-01

    Estimates of total spacecraft weight and packaging options were made for three conceptual designs of a microwave radiometer spacecraft. Erectable structures were found to be slightly lighter than deployable structures but could be packaged in one-tenth the volume. The tension rim concept, an unconventional design approach, was found to be the lightest and transportable to orbit in the least number of shuttle flights.

  16. Results from the pushbroom microwave radiometer flights over the Konza Prairie in 1985

    Science.gov (United States)

    Schmugge, T. J.; Wang, J. R.; Lawrence, R. W.

    1987-01-01

    Four flights were conducted by the NASA C-130 aircraft sensor platform bearing the 'pushbroom' microwave radiometer (PBMR) over the Konza Prairie in central Kansas in 1985, in order to monitor soil surface variations. When the brightness temperature maps thus obtained were analyzed, a striking difference was noted between burned and unburned watersheds; the latter had a very high emissivity despite having saturated soils, while the former had low values that increased with the gradual drying of the soils. The lack of sensitivity for the unburned watershed is tentatively attributed to the build-up of a thatch layer by the decaying vegetation, which serves as a good microwave absorber when wet.

  17. Microwave Radiometers from 0.6 to 22 GHz for Juno, A Polar Orbiter Around Jupiter

    Science.gov (United States)

    Pingree, P.; Janssen, M.; Oswald, J.; Brown, S.; Chen, J.; Hurst, K.; Kitiyakara, A.; Maiwald, F.; Smith, S.

    2008-01-01

    A compact instrument called the MWR (MicroWave Radiometer) is under development at JPL for Juno, the next NASA New Frontiers mission, scheduled to launch in 2011. It's purpose is to measure the thermal emission from Jupiter's atmosphere at six selected frequencies from 0.6 to 22 GHz, operating in direct detection mode, in order to quantify the distributions and abundances of water and ammonia in Jupiter's atmosphere. The goal is to understand the previously unobserved dynamics of the sub-cloud atmosphere, and to discriminate among models for planetary formation in our solar system. As part of a deep space mission aboard a solar-powered spacecraft, MWR is designed to be compact, lightweight, and low power. The receivers and control electronics are protected by a radiation-shielding enclosure on the Juno spacecraft that would provide a benign and stable operating temperature environment. All antennas and RF transmission lines outside the vault must withstand low temperatures and the harsh radiation environment surrounding Jupiter. This paper describes the concept of the MWR instrument and presents results of one breadboard receiver channel.

  18. The Passive Microwave Neural Network Precipitation Retrieval (PNPR) for AMSU/MHS and ATMS cross-track scanning radiometers

    Science.gov (United States)

    Sano', Paolo; Casella, Daniele; Panegrossi, Giulia; Cinzia Marra, Anna; Dietrich, Stefano

    2016-04-01

    another when an observed precipitation system extends over two or more types of surfaces. As input data, the PNPR algorithm incorporates the TBs from selected channels, and various additional TBs-derived variables. Ancillary geographical/geophysical inputs (i.e., latitude, terrain height, surface type, season) are also considered during the training phase. The PNPR algorithm outputs consist of both the surface precipitation rate (along with the information on precipitation phase: liquid, mixed, solid) and a pixel-based quality index. We will illustrate the main features of the PNPR algorithm and will show results of a verification study over Europe and Africa. The study is based on the available ground-based radar and/or rain gauge network observations over the European area. In addition, results of the comparison with rainfall products available from the NASA/JAXA Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) (over the African area) and Global Precipitation Measurement (GPM) Dual frequency Precipitation Radar (DPR) will be shown. The analysis is built upon a two-years coincidence dataset of AMSU/MHS and ATMS observations with PR (2013-2014) and DPR (2014-2015). The PNPR is developed within the EUMETSAT H/SAF program (Satellite Application Facility for Operational Hydrology and Water Management), where it is used operationally towards the full exploitation of all microwave radiometers available in the GPM era. The algorithm will be tailored to the future European Microwave Sounder (MWS) onboard the MetOp-Second Generation (MetOp-SG) satellites.

  19. Mesospheric CO above Troll station, Antarctica observed by a ground based microwave radiometer

    Directory of Open Access Journals (Sweden)

    C. Straub

    2013-06-01

    Full Text Available This paper presents mesospheric carbon monoxide (CO data acquired by the ground-based microwave radiometer of the British Antarctic Survey (BAS radiometer stationed at Troll station in Antarctica (72° S, 2.5° E, 1270 m a.s.l.. The dataset covers the period from February 2008 to January 2010, however, due to very low CO concentrations below approximately 80 km altitude in summer, profiles are only presented during the Antarctic winter. CO is measured for approximately 2 h each day and profiles are retrieved approximately every half hour. The retrieved profiles, covering the pressure range from 1 to 0.01 hPa (approximately 48 to 80 km, are compared to measurements from Microwave Limb Sounder on the Aura satellite (Aura/MLS and Whole Atmosphere Community Climate Model with Specified Dynamics (SD-WACCM. This intercomparison reveals a low bias of 0.5 to 1 ppmv at 0.1 hPa (approximately 64 km and 2.5 to 3.5 ppmv at 0.01 hPa (approximately 80 km of the BAS microwave radiometer compared to both reference datasets. One explanation for this low bias could be the known high bias of MLS which is on the same order of magnitude. The ground based radiometer shows high and significant correlation (coefficients higher than 0.9/0.7 compared to MLS/SD-WACCM at all altitudes compared with both reference datasets. The dataset can be accessed under http://dx.doi.org/10/mhq.

  20. Assessment of forecast indices over Sriharikota using ground-based microwave radiometer

    Science.gov (United States)

    Pushpa Saroja, R.; Rajasekhar, M.; Papa Rao, G.; Rajeevan, M.; Bharathi, G.

    2016-05-01

    Continuous measurements of vertical profiles of thermodynamic variables are important for severe weather nowcasting & forecasting over a region instead of radiosonde observations which are available once or twice daily. Microwave Radiometer (MWR) provides high quality of thermodynamic (temperature, water vapor, and cloud liquid) soundings up to an altitude of 10 Kms in the clear and cloudy weather conditions except during heavy rainfall. Retrievals of MWR profiles are based on the intensity of the atmospheric radiation at selected frequencies (22-30 GHz) & (51-59 GHz) with high temporal and vertical resolution in the troposphere. The MWR used in the present study is TP/WVP-3166A, measures the intensity of radiation at 8 water vapor channels and 14 oxygen channels which is installed at Sriharikota in June. In this paper we analyzed the thermodynamic indices derived from MWR profiles during severe convective thunderstorms for Sriharikota region. MWR derived thermodynamic profiles are compared with radiosonde observations during rainy & non rainy days. MWR temperature profiles and vapor density profiles are well correlated with the observations with a cold bias of 1.5°C & 2.5°C and with a dry bias of 0.37 g/m3 & 0.04 g/m3respectively. For this we considered 10 thunderstorm cases from June to November 2014 analysed with indices K index, MDPI, CAPE, Windex, KO index, L index, S index, Showalter index, Total totals index, Vertical totals along with integrated liquid water and vapour density. MDPI, CAP index, Windex, Kindex, Lindex and convective temperature were best performed indices two hours prior to thunderstorm over SHAR region.

  1. Topographic Effects on the Surface Emissivity of a Mountainous Area Observed by a Spaceborne Microwave Radiometer

    Directory of Open Access Journals (Sweden)

    Frank S. Marzano

    2008-03-01

    Full Text Available A simulation study to understand the influence of topography on the surfaceemissivity observed by a satellite microwave radiometer is carried out. We analyze theeffects due to changes in observation angle, including the rotation of the polarization plane.A mountainous area in the Alps (Northern Italy is considered and the information on therelief extracted from a digital elevation model is exploited. The numerical simulation refersto a radiometric image, acquired by a conically-scanning radiometer similar to AMSR-E,i.e., flying at 705 km of altitude with an observation angle of 55°. To single out the impacton surface emissivity, scattering of the radiation due to the atmosphere or neighboringelevated surfaces is not considered. C and X bands, for which atmospheric effects arenegligible, and Ka band are analyzed. The results indicate that the changes in the localobservation angle tend to lower the apparent emissivity of a radiometric pixel with respectto the corresponding flat surface characteristics. The effect of the rotation of thepolarization plane enlarges (vertical polarization, or attenuates (horizontal polarizationthis decrease. By doing some simplifying assumptions for the radiometer antenna, theconclusion is that the microwave emissivity at vertical polarization is underestimated,whilst the opposite occurs for horizontal polarization, except for Ka band, for which bothunder- and overprediction may occur. A quantification of the differences with respect to aflat soil and an approximate evaluation of their impact on soil moisture retrieval areyielded.

  2. Microwave Radiometer for Spectral Observations of Mesospheric Carbon Monoxide at 115 GHz Over Kharkiv, Ukraine

    Science.gov (United States)

    Piddyachiy, Valeriy; Shulga, Valerii; Myshenko, Valeriy; Korolev, Alexey; Antyufeyev, Oleksandr; Shulga, Dmytro; Forkman, Peter

    2016-11-01

    We present the results of the development of high sensitivity microwave radiometer designed for observation of the atmospheric carbon monoxide (CO) emission lines at 115 GHz. The receiver of this radiometer has the double-sideband noise temperature of 250 K at a temperature of 10°C. To date, this is the best noise performance for uncooled Schottky diode mixer receiver systems. The designed radiometer was tested during the 2014-2015 period at observations of the carbon monoxide emission lines over Kharkiv, Ukraine (50° N, 36.3° E). These tests have shown the reliability of the receiver system, which allows us in the future to use designed radiometer for continuous monitoring of carbon monoxide. The first observations of the atmospheric carbon monoxide spectral lines over Kharkiv have confirmed seasonal changes in the CO abundance and gave us reasons to assume the spread of the influence of the polar vortex on the state of the atmosphere up to the latitude of 50° N where our measurement system is located.

  3. Microwave Radiometer for Spectral Observations of Mesospheric Carbon Monoxide at 115 GHz Over Kharkiv, Ukraine

    Science.gov (United States)

    Piddyachiy, Valeriy; Shulga, Valerii; Myshenko, Valeriy; Korolev, Alexey; Antyufeyev, Oleksandr; Shulga, Dmytro; Forkman, Peter

    2017-03-01

    We present the results of the development of high sensitivity microwave radiometer designed for observation of the atmospheric carbon monoxide (CO) emission lines at 115 GHz. The receiver of this radiometer has the double-sideband noise temperature of 250 K at a temperature of 10°C. To date, this is the best noise performance for uncooled Schottky diode mixer receiver systems. The designed radiometer was tested during the 2014-2015 period at observations of the carbon monoxide emission lines over Kharkiv, Ukraine (50° N, 36.3° E). These tests have shown the reliability of the receiver system, which allows us in the future to use designed radiometer for continuous monitoring of carbon monoxide. The first observations of the atmospheric carbon monoxide spectral lines over Kharkiv have confirmed seasonal changes in the CO abundance and gave us reasons to assume the spread of the influence of the polar vortex on the state of the atmosphere up to the latitude of 50° N where our measurement system is located.

  4. Two-Look Polarimetric (2LP) Microwave Radiometers for Ocean Vector Wind Retrieval

    Science.gov (United States)

    Wentz, F. J.; Hilburn, K. A.; Meissner, T.; Brown, S. E.

    2014-12-01

    This talk discusses the future utilization of two-look polarimetric (2LP) microwave radiometers for measuring the ocean surface wind vector. Potentially, these 2LP satellite radiometers offer two advantages over conventional scatterometers: unambiguous wind vector retrievals and low-cost. One concept for a 2LP radiometer is being developed by JPL and is called the Compact Ocean Wind Vector Radiometer (COWVR). A space demonstration of COWVR is planned for 2016 timeframe. To explore the potential of 2LP radiometers, we use the 11 years of WindSat observations as a testbed. We only use that portion of the WindSat swath that has both fore and aft observations. WindSat provides fully polarimetric observations (all four Stokes parameters) at 11, 19, and 37 GHz. This represents 12 independent channels for each of the two azimuth directions. A wind vector retrieval algorithm is developed to fully utilize this wide assortment of information. Since this analysis is based on actual observations, it provides a realistic picture of what to expect from future 2LP radiometers. To our knowledge, this is the first time that the combination of WindSat's fore and aft observations has been fully utilized for wind vector retrievals. In our talk we compare the 2LP wind vector retrieval performance with that of single-look polarimetric radiometers (i.e., WindSat standard product) and scatterometers. We provide basic statistics from a triple collocation between winds from WindSat, QuikScat, and NDBC/PMEL ocean moored buoys. The statistics include the standard deviation of the first ranked ambiguity direction, skill rate, and number of ambiguities. All available data from the common period of operation between WindSat and QuikScat (2003-2009) are used. We characterize the wind direction accuracy as a function of wind speed, and show how 2LP retrievals are able to extend the wind vector accuracy to lower wind speeds than previously considered possible for radiometers.

  5. Mesospheric CO above Troll station, Antarctica observed by a ground based microwave radiometer

    Directory of Open Access Journals (Sweden)

    C. Straub

    2013-01-01

    Full Text Available This paper presents mesospheric carbon monoxide (CO data acquired by the ground-based microwave radiometer of the British Antarctic Survey (BAS radiometer stationed at Troll station in Antarctica (72° S, 2.5° E, 1270 a.m.s.l.. The data set covers the period from February 2008 to January 2010, however, due to very low CO concentrations below approximately 80 km altitude in summer, profiles can only be retrieved during Antarctic winter. CO is measured for approximately 2 h each day and profiles are retrieved approximately every half hour. The retrieved profiles, covering the pressure range from 1 to 0.01 hPa (approximately 48 to 80 km, are compared to measurements from Aura/MLS and SD-WACCM. This intercomparison reveals a low bias of 0.5 to 1 ppmv at 0.1 hPa (approximately 64 km and 2.5 to 3.5 ppmv at 0.01 hPa (approximately 80 km of the BAS microwave radiometer compared to both reference datasets. One explanation for this low bias could be the known high bias of MLS which is in the same order of magnitude. The ground based radiometer shows high and significant correlation (coefficients higher than 0.9/0.65 compared to MLS/SD-WACCM at all altitudes compared with both reference datasets. doi:10.5285/DE3E2092-406D-47A9-9205-3971A8DFB4A9

  6. Investigation of a Real-time Processing System for the NASA Multifrequency Microwave Radiometer

    Science.gov (United States)

    1976-01-01

    A study was conducted to investigate the data reduction and processing requirements for the multifrequency microwave radiometer system (MFMR). The objectives were to develop and evaluate algorithms and processing techniques which might provide for dedicated real time or near real time data processing and to develop a configuration design and processor recommendation to accomplish the data reduction. An analysis of the required data reduction and calibration equations was included along with the identification of sources of error which may be present in the (MFMR) data. The definition and evaluation of the significance of effects introduced by aircraft perturbation was given.

  7. Bayesian Estimation of Precipitation from Satellite Passive Microwave Observations Using Combined Radar-Radiometer Retrievals

    Science.gov (United States)

    Grecu, Mircea; Olson, William S.

    2006-01-01

    Precipitation estimation from satellite passive microwave radiometer observations is a problem that does not have a unique solution that is insensitive to errors in the input data. Traditionally, to make this problem well posed, a priori information derived from physical models or independent, high-quality observations is incorporated into the solution. In the present study, a database of precipitation profiles and associated brightness temperatures is constructed to serve as a priori information in a passive microwave radiometer algorithm. The precipitation profiles are derived from a Tropical Rainfall Measuring Mission (TRMM) combined radar radiometer algorithm, and the brightness temperatures are TRMM Microwave Imager (TMI) observed. Because the observed brightness temperatures are consistent with those derived from a radiative transfer model embedded in the combined algorithm, the precipitation brightness temperature database is considered to be physically consistent. The database examined here is derived from the analysis of a month-long record of TRMM data that yields more than a million profiles of precipitation and associated brightness temperatures. These profiles are clustered into a tractable number of classes based on the local sea surface temperature, a radiometer-based estimate of the echo-top height (the height beyond which the reflectivity drops below 17 dBZ), and brightness temperature principal components. For each class, the mean precipitation profile, brightness temperature principal components, and probability of occurrence are determined. The precipitation brightness temperature database supports a radiometer-only algorithm that incorporates a Bayesian estimation methodology. In the Bayesian framework, precipitation estimates are weighted averages of the mean precipitation values corresponding to the classes in the database, with the weights being determined according to the similarity between the observed brightness temperature principal

  8. Correlations between Nimbus-7 Scanning Multichannel Microwave Radiometer data and an antecedent precipitation index

    Science.gov (United States)

    Wilke, G. D.; Mcfarland, M. J.

    1986-01-01

    Passive microwave brightness temperatures from the Nimbus-7 Scanning Multichannel Microwave Radiometer (SMMR) can be used to infer the soil moisture content over agricultural areas such as the southern Great Plains of the United States. A linear regression analysis between three transforms of the five dual polarized SMMR wavelengths of 0.81, 1.36, 1.66, 2.80 and 4.54 cm and an antecedent precipitation index representing the precipitation history showed correlation coefficients greater than 0.90 for pixel aggregates of 25-50 km. The use of surface air temperatures to approximate the temperature of the emitting layer was not required to obtain high correlation coefficients between the transforms and the antecedent precipitation index.

  9. A preliminary assessment of the sea surface wind speed production of HY-2 scanning microwave radiometer

    Institute of Scientific and Technical Information of China (English)

    HUANG Xiaoqi; ZHU Jianhua; LIN Mingsen; ZHAO Yili; WANG He; CHEN Chuntao; PENG Hailong; ZHANG Youguang

    2014-01-01

    A scanning microwave radiometer (RM) was launched on August 16, 2011, on board HY-2 satellite. The six-month long global sea surface wind speeds observed by the HY-2 scanning microwave radiometer are preliminarily validated using in-situ measurements and WindSat observations, respectively, from January to June 2012. The wind speed root-mean-square (RMS) difference of the comparisons with in-situ data is 1.89 m/s for the measurements of NDBC and 1.72 m/s for the recent four-month data measured by PY30-1 oil platform, respectively. On a global scale, the wind speeds of HY-2 RM are compared with the sea surface wind speeds derived from WindSat, the RMS difference of 1.85 m/s for HY-2 RM collocated observations data set is calculated in the same period as above. With analyzing the global map of a mean difference between HY-2 RM and WindSat, it appears that the bias of the sea surface wind speed is obviously higher in the inshore regions. In the open sea, there is a relatively higher positive bias in the mid-latitude regions due to the overestimation of wind speed observations, while the wind speeds are underestimated in the Southern Ocean by HY-2 RM relative to WindSat observations.

  10. Microwave Radiometers for Fire Detection in Trains: Theory and Feasibility Study †

    Science.gov (United States)

    Alimenti, Federico; Roselli, Luca; Bonafoni, Stefania

    2016-01-01

    This paper introduces the theory of fire detection in moving vehicles by microwave radiometers. The system analysis is discussed and a feasibility study is illustrated on the basis of two implementation hypotheses. The basic idea is to have a fixed radiometer and to look inside the glass windows of the wagon when it passes in front of the instrument antenna. The proposed sensor uses a three-pixel multi-beam configuration that allows an image to be formed by the movement of the train itself. Each pixel is constituted by a direct amplification microwave receiver operating at 31.4 GHz. At this frequency, the antenna can be a 34 cm offset parabolic dish, whereas a 1 K brightness temperature resolution is achievable with an overall system noise figure of 6 dB, an observation bandwidth of 2 GHz and an integration time of 1 ms. The effect of the detector noise is also investigated and several implementation hypotheses are discussed. The presented study is important since it could be applied to the automatic fire alarm in trains and moving vehicles with dielectric wall/windows. PMID:27322280

  11. Microwave Radiometers for Fire Detection in Trains: Theory and Feasibility Study

    Directory of Open Access Journals (Sweden)

    Federico Alimenti

    2016-06-01

    Full Text Available This paper introduces the theory of fire detection in moving vehicles by microwave radiometers. The system analysis is discussed and a feasibility study is illustrated on the basis of two implementation hypotheses. The basic idea is to have a fixed radiometer and to look inside the glass windows of the wagon when it passes in front of the instrument antenna. The proposed sensor uses a three-pixel multi-beam configuration that allows an image to be formed by the movement of the train itself. Each pixel is constituted by a direct amplification microwave receiver operating at 31.4 GHz. At this frequency, the antenna can be a 34 cm offset parabolic dish, whereas a 1 K brightness temperature resolution is achievable with an overall system noise figure of 6 dB, an observation bandwidth of 2 GHz and an integration time of 1 ms. The effect of the detector noise is also investigated and several implementation hypotheses are discussed. The presented study is important since it could be applied to the automatic fire alarm in trains and moving vehicles with dielectric wall/windows.

  12. Validation of stratospheric temperature profiles from a ground-based microwave radiometer with other techniques

    Science.gov (United States)

    Navas, Francisco; Kämpfer, Niklaus; Haefele, Alexander; Keckhut, Philippe; Hauchecorne, Alain

    2016-04-01

    Vertical profiles of atmospheric temperature trends has become recognized as an important indicator of climate change, because different climate forcing mechanisms exhibit distinct vertical warming and cooling patterns. For example, the cooling of the stratosphere is an indicator for climate change as it provides evidence of natural and anthropogenic climate forcing just like surface warming. Despite its importance, our understanding of the observed stratospheric temperature trend and our ability to test simulations of the stratospheric response to emissions of greenhouse gases and ozone depleting substances remains limited. One of the main reason is because stratospheric long-term datasets are sparse and obtained trends differ from one another. Different techniques allow to measure stratospheric temperature profiles as radiosonde, lidar or satellite. The main advantage of microwave radiometers against these other instruments is a high temporal resolution with a reasonable good spatial resolution. Moreover, the measurement at a fixed location allows to observe local atmospheric dynamics over a long time period, which is crucial for climate research. This study presents an evaluation of the stratospheric temperature profiles from a newly ground-based microwave temperature radiometer (TEMPERA) which has been built and designed at the University of Bern. The measurements from TEMPERA are compared with the ones from other different techniques such as in-situ (radiosondes), active remote sensing (lidar) and passive remote sensing on board of Aura satellite (MLS) measurements. In addition a statistical analysis of the stratospheric temperature obtained from TEMPERA measurements during four years of data has been performed. This analysis evidenced the capability of TEMPERA radiometer to monitor the temperature in the stratosphere for a long-term. The detection of some singular sudden stratospheric warming (SSW) during the analyzed period shows the necessity of these

  13. Status of VESAS: a fully-electronic microwave imaging radiometer system

    Science.gov (United States)

    Schreiber, Eric; Peichl, Markus; Suess, Helmut

    2010-04-01

    Present applications of microwave remote sensing systems cover a large variety. One utilisation of the frequency range from 1 - 300 GHz is the domain of security and reconnaissance. Examples are the observation of critical infrastructures or the performance of security checks on people in order to detect concealed weapons or explosives, both being frequent threats in our world of growing international terrorism. The imaging capability of concealed objects is one of the main advantages of microwave remote sensing, because of the penetration performance of electromagnetic waves through dielectric materials in this frequency domain. The main physical effects used in passive microwave sensing rely on the naturally generated thermal radiation and the physical properties of matter, the latter being surface characteristics, chemical and physical composition, and the temperature of the material. As a consequence it is possible to discriminate objects having different material characteristics like ceramic weapons or plastic explosives with respect to the human body. Considering the use of microwave imaging with respect to people scanning systems in airports, railway stations, or stadiums, it is advantageous that passively operating devices generate no exposure on the scanned objects like actively operating devices do. For frequently used security gateways it is additionally important to have a high through-put rate in order to minimize the queue time. Consequently fast imaging systems are necessary. In this regard the conceptual idea of a fully-electronic microwave imaging radiometer system is introduced. The two-dimensional scanning mechanism is divided into a frequency scan in one direction and the method of aperture synthesis in the other. The overall goal here is to design a low-cost, fully-electronic imaging system with a frame rate of around one second at Ka band. This frequency domain around a center frequency of 37 GHz offers a well-balanced compromise between the

  14. Exploring the Turbulent Urban Boundary by Use of Lidars and Microwave Radiometers

    Science.gov (United States)

    Arend, Mark; Valerio, Ivan; Neufeld, Stephen; Bishir, Raymond; Wu, Younghu; Moshary, Fred; Melecio-Vazquez, David; Gonzalez, Jorge

    2016-06-01

    A Doppler lidar has been developed using fiber optic based technologies and advanced signal processing techniques. Although this system has been operated in a scanning mode in the past, for this application, the system is operated in a vertically pointing mode and delivers a time series of vertical velocity profiles. By cooperating the Doppler lidar with other instruments, including a back scatter lidar, and a microwave radiometer, models of atmospheric stability can be tested, opening up an exciting path for researchers, applied scientists and engineers to discover unique phenomena related to fundamental atmospheric science processes. A consistent set of retrievals between each of these instruments emphasizes the utility for such a network of instruments to better characterize the turbulent atmospheric urban boundary layers which is expected to offer a useful capability for assessing and improving models that are in great need of such ground truth.

  15. A new algorithm for microwave radiometer remote sensing of sea surface salinity and temperature

    Institute of Scientific and Technical Information of China (English)

    YIN; Xiaobin; LIU; Yuguang; WANG; Zhenzhan

    2006-01-01

    The microwave radiation of the sea surface, which is denoted by the sea surface brightness temperature, is not only related with sea surface salinity (SSS) and temperature (SST), but also influenced by sea surface wind. The errors of wind detected by satellite sensor have significant influences on the accuracy of SSS and SST retrieval. The effects of sea surface wind on sea surface brightness temperature, i.e. △Th,v, and the relations among △Th,v, wind speed, sea surface temperature, sea surface salinity and incidence angle of observation are investigated. Based on the investigations, a new algorithm depending on the design of a single radiometer with double polarizations and multi-incidence angles is proposed. The algorithm excludes the influence of sea surface wind on SSS and SST retrieval, and provides a new method for remote sensing of SSS and SST.

  16. Nimbus-7 scanning multichannel microwave radiometer /SMMR/ in-orbit performance appraisal

    Science.gov (United States)

    Gloersen, P.; Cavalieri, D. J.; Gatlin, J. A.

    1981-01-01

    Calibration and processing techniques enacted during first year of operation of the Nimbus-7 scanning multichannel microwave radiometer (SMMR) are described. It was found that in-orbit calibration was necessary, as was fine-tuning of the geophysical parameter retrieval parameters to account for anomalies such as lower-than-expected polarization differences in ocean radiances. Phase shifts in the scan angles were corrected in order to avoid polarization mixing. Calibration constants to eliminate cross-talk and phase shift effects were established for radiation reflected from the earth, then averaged over data from 300 orbits to fit points on a sine curve to better than 0.2 K accuracy. An iterative approach was determined to be necessary due to signal anomalies caused by antenna dish oscillations. Global ocean and atmosphere parameters used to construct a radiation model of ten latitude bands are presented for use in radiation transfer equations.

  17. Microwave radiometer to retrieve temperature profiles from the surface to the stratopause

    Directory of Open Access Journals (Sweden)

    O. Stähli

    2013-09-01

    Full Text Available TEMPERA (TEMPERature RAdiometer is a new ground-based radiometer which measures in a frequency range from 51–57 GHz radiation emitted by the atmosphere. With this instrument it is possible to measure temperature profiles from ground to about 50 km. This is the first ground-based instrument with the capability to retrieve temperature profiles simultaneously for the troposphere and stratosphere. The measurement is done with a filterbank in combination with a digital fast Fourier transform spectrometer. A hot load and a noise diode are used as stable calibration sources. The optics consist of an off-axis parabolic mirror to collect the sky radiation. Due to the Zeeman effect on the emission lines used, the maximum height for the temperature retrieval is about 50 km. The effect is apparent in the measured spectra. The performance of TEMPERA is validated by comparison with nearby radiosonde and satellite data from the Microwave Limb Sounder on the Aura satellite. In this paper we present the design and measurement method of the instrument followed by a description of the retrieval method, together with a validation of TEMPERA data over its first year, 2012.

  18. Water Vapour Radiometers for the Australia Telescope Compact Array

    CERN Document Server

    Indermuehle, Balthasar T; Crofts, Jonathan

    2012-01-01

    We have developed Water Vapour Radiometers (WVRs) for the Australia Telescope Compact Array (ATCA) that are capable of determining path fluctuations by virtue of measuring small temperature fluctuations in the atmosphere using the 22.2 GHz water vapour line for each of the six antennae. By measuring the line of sight variations of the water vapour, the induced path excess and thus the phase delay can be estimated and corrections can then be applied during data reduction. This reduces decorrelation of the source signal. We demonstrate how this recovers the telescope's efficiency and image quality as well as how this improves the telescope's ability to use longer baselines at higher frequencies, thereby resulting in higher spatial resolution. A description of the WVR hardware design, their calibration and water vapour retrieval mechanism is given.

  19. Detection of the Zeeman effect in atmospheric O2 using a ground-based microwave radiometer

    Science.gov (United States)

    Navas-Guzmán, Francisco; Kämpfer, Niklaus; Murk, Axel; Larsson, Richard; Buehler, Stefan A.; Eriksson, Patrick

    2015-04-01

    In this work we study the Zeeman effect on stratospheric O2 using ground-based microwave radiometer measurements. The Zeeman effect is a phenomenon which occurs when an external magnetic field interacts with a molecule or an atom of total electron spin different from zero. Such an interaction will split an original energy level into several sub-levels [1]. In the atmosphere, oxygen is an abundant molecule which in its ground electronic state has a permanent magnetic dipole moment coming from two parallel electron spins. The interaction of the magnetic dipole moment with the Earth magnetic field leads to a Zeeman splitting of the O2 rotational transitions which polarizes the emission spectra. A special campaign was carried out in order to measure this effect in the oxygen emission line centered at 53.07 GHz in Bern (Switzerland). The measurements were possible using a Fast Fourier Transform (FFT) spectrometer with 1 GHz of band width to measure the whole oxygen emission line centered at 53.07 GHz and a narrow spectrometer (4 MHz) to measure the center of the line with a very high resolution (1 kHz). Both a fixed and a rotating mirror were incorporated to the TEMPERA (TEMPERature RAdiometer) radiometer in order to be able to measure under different observational angles. This new configuration allowed us to change the angle between the observational path and the Earth magnetic field direction. The measured spectra showed a clear polarized signature when the observational angles were changed evidencing the Zeeman effect in the oxygen molecule. In addition, simulations carried out with the Atmospheric Radiative Transfer Simulator (ARTS) [2] allowed us to verify the microwave measurements showing a very good agreement between model and measurements. The incorporation of this effect to the forward model will allow to extend the temperature retrievals beyond 50 km. This improvement in the forward model will be very useful for the assimilation of brightness temperatures in

  20. Microwave Properties of Ice-Phase Hydrometeors for Radar and Radiometers: Sensitivity to Model Assumptions

    Science.gov (United States)

    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.

  1. Characterization of downwelling radiance measured from a ground-based microwave radiometer using numerical weather prediction model data

    Science.gov (United States)

    Ahn, M.-H.; Won, H. Y.; Han, D.; Kim, Y.-H.; Ha, J.-C.

    2016-01-01

    The ground-based microwave sounding radiometers installed at nine weather stations of Korea Meteorological Administration alongside with the wind profilers have been operating for more than 4 years. Here we apply a process to assess the characteristics of the observation data by comparing the measured brightness temperature (Tb) with reference data. For the current study, the reference data are prepared by the radiative transfer simulation with the temperature and humidity profiles from the numerical weather prediction model instead of the conventional radiosonde data. Based on the 3 years of data, from 2010 to 2012, we were able to characterize the effects of the absolute calibration on the quality of the measured Tb. We also showed that when clouds are present the comparison with the model has a high variability due to presence of cloud liquid water therefore making cloudy data not suitable for assessment of the radiometer's performance. Finally we showed that differences between modeled and measured brightness temperatures are unlikely due to a shift in the selection of the center frequency but more likely due to spectroscopy issues in the wings of the 60 GHz absorption band. With a proper consideration of data affected by these two effects, it is shown that there is an excellent agreement between the measured and simulated Tb. The regression coefficients are better than 0.97 along with the bias value of better than 1.0 K except for the 52.28 GHz channel which shows a rather large bias and variability of -2.6 and 1.8 K, respectively.

  2. Quantitative Characterisation of Sky Conditions on Paranal with the Microwave Radiometer LHATPRO – Five Years and Learning

    Science.gov (United States)

    Kerber, Florian; Querel, R.; Neureiter, B.; Hanuschik, R.

    2017-09-01

    "A Low Humidity and Temperature Profiling (LHATPRO) microwave radiometer, optimized for measuring small amounts of atmospheric precipitable water vapour (PWV), has now been in use for more than five years to monitor sky conditions over ESO's Paranal observatory (median PWV 2.5 mm). We'll summarise the performance characteristics of the unit and the current applications of its data in scheduling observations in Service Mode to take advantage of favourable conditions for infrared observations. We'll elaborate on our improved understanding of PWV over Paranal, including an analysis of PWV homogeneity addressing an important calibration issue. In addition we'll describe how the capabilities of the LHATPRO can be used in the future to further strengthen science operations and calibration by also offering line-of-sight support for individual VLT observations. Using its IR data we developed a method for an automated classification of photometric observing conditions in a quantitative way, supporting high precision photometry. Its highly precise PWV measurements enable new low PWV science during episodes of extremely low water vapour that result in a strongly increased transmission also outside the standard atmospheric windows. A goal for the future is to combine various diagnostics measurements (altitude resolved profiles) by LHATPRO and other instruments and sophisticated atmospheric modeling to better characterize relevant properties of the atmosphere and to thus enable more precise, local short-term forecasting for optimised science operations."

  3. Novel Low-Impact Integration of a Microwave Radiometer into Cloud Radar System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The radiometer channel will have significant filtering to reduce the contamination of the radar signal into the radiometer channels.The successful isolation between...

  4. The Capability of Microwave Radiometers In Retrieving Soil Moisture Profiles Using A Neural Networks

    Science.gov (United States)

    Macelloni, G.; Paloscia, S.; Santi, E.; Tedesco, M.

    Hydrological models require the knowledge of land surface parameters like soil mois- ture and snow properties with a large spatial distribution and high temporal frequency. Whilst conventional methods are unable to satisfy the constraints of space and time estimation of these parameters, the use of remote sensing data represents a real im- provement. In particular the potential of data collected by microwave radiometers at low frequencies to extract soil moisture has been clearly demonstrated in several pa- pers. However, the penetration power into the soil depends on frequency and, whereas L-band is able to estimate the moisture of a relatively thick soil layer, higher frequen- cies are only sensitive to the moisture of soil layer closer to the surface. This remark leads to the hypothesis that multifrequency observations could be able to retrieve a soil moisture profile. In several experiments carried out both on agricultural fields and on samples of soil in a tank, by using the IROE multifrequency microwave radiometers, the effect of moisture and surface roughness on different frequencies was studied. From this experiments the capability of L-band in measuring the moisture of a soil layer of several centimeters, in the order of the wavelength, was confirmed, as well the sensitivity to the moisture of the first centimeters layer at C- and X-bands, and the one of the very first layer of smooth soil at Ka-band. Using an electromagnetic model (Integral Equation Model, IEM) the brightness temperatures as a function of the in- cidence angle were computed at 1.4, 6, 10, and 37 GHz for different soil moisture profiles and different surface roughness. A particular consideration was dedicated to the latter parameter, since, especially at Ka band, surface roughness strongly affects the emission and masks the effect of moisture. Different soil moisture profiles have been tested: increasing and decreasing with depth and also constant for sandy and sandy-loam soils. After this

  5. Rock infromation of the moon revealed by multi-channel microwave radiometer data

    Science.gov (United States)

    Hu, Guo-Ping; Zheng, Yong-Chun; Chan, Kwing Lam; Xu, Ao-Ao; This work is supported by Science and Technology Development Fund in Macao SAR 048/2012/A2 and 039/2013/A2, and the NSFC program (41490633). The CE data was supported by the Key Laboratory of Lunar and Deep Space Exploration (2013DP173157), National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, China.

    2016-10-01

    Rock abundance on lunar surface is an important consideration for understanding the physical properties of the Moon. With the deeper penetration power of the microwave, data from Chang'E (CE) multichannel (3.0-, 7.8-, 19.35-, and 37-GHz) microwave radiometer (MRM) are used to constrain the rock distribution on the Moon. The contrasting thermo-physical properties between rocks and regolith fines cause multiple brightness temperature (TB) to be present within the field of view of CE microwave data. But these variations could be easily masked by the more significant effect of ilmenite on TB, especially in the mare regions which are rich in ilmenite.To highlight the rock effect in TB, the diurnal TB difference, which has the effect of enlarging the TB difference caused by the rock abundance and reducing the absolute error of the CE microwave data, is considered here. The rock information in TB data is distinguished from the ilmenite effect by comparing the diurnal TB difference with a statistical TB model of the mare regions which are relatively low in rock abundance. The employed statistical TB model is a polynomial fitting formula between the selected CE TB data from mare regions and the corresponding TiO2 content data from Clementine UVVIS data. The correlation coefficients of the polynomial fit between TB and TiO2 content are 0.94 at lunar daytime and 0.84 at lunar nighttime, respectively. This polynomial fit forms an approximated relationship between the TiO2 content and TB when rock abundance is zero, with a standard error determined from the regression procedure.Based on the TiO2 map retrieved from Clementine UVVIS data, the TB map that is deflated to a lower TiO2 content shows a distribution trend similar to the rock abundance map retrieved by LRO data, except for the mare regions at the nearside of the Moon. The bigger diurnal TB difference in the mare regions could be either caused by the rich ilmenite rocks or the smaller rocks which cannot be recognized by

  6. Correlation function analysis of the COBE differential microwave radiometer sky maps

    Energy Technology Data Exchange (ETDEWEB)

    Lineweaver, Charles Howe [Univ. of California, Berkeley, CA (United States). Space Sciences Lab.

    1994-08-01

    The Differential Microwave Radiometer (DMR) aboard the COBE satellite has detected anisotropies in the cosmic microwave background (CMB) radiation. A two-point correlation function analysis which helped lead to this discovery is presented in detail. The results of a correlation function analysis of the two year DMR data set is presented. The first and second year data sets are compared and found to be reasonably consistent. The positive correlation for separation angles less than ~20° is robust to Galactic latitude cuts and is very stable from year to year. The Galactic latitude cut independence of the correlation function is strong evidence that the signal is not Galactic in origin. The statistical significance of the structure seen in the correlation function of the first, second and two year maps is respectively > 9σ, > 10σ and > 18σ above the noise. The noise in the DMR sky maps is correlated at a low level. The structure of the pixel temperature covariance matrix is given. The noise covariance matrix of a DMR sky map is diagonal to an accuracy of better than 1%. For a given sky pixel, the dominant noise covariance occurs with the ring of pixels at an angular separation of 60° due to the 60° separation of the DMR horns. The mean covariance of 60° is 0.45%$+0.18\\atop{-0.14}$ of the mean variance. The noise properties of the DMR maps are thus well approximated by the noise properties of maps made by a single-beam experiment. Previously published DMR results are not significantly affected by correlated noise.

  7. Push broom microwave radiometer observations of surface soil moisture in Monsoon '90

    Science.gov (United States)

    Schmugge, T.; Jackson, T. J.; Kustas, W. P.; Roberts, R.; Parry, R.; Goodrich, D. C.; Amer, S. A.; Weltz, M. A.

    1994-05-01

    The push broom microwave radiometer (PBMR) was flown on six flights of the NASA C-130 to map the surface soil moisture over the U.S. Department of Agriculture's Agricultural Research Service Walnut Gulch experimental watershed in southeastern Arizona. The PBMR operates at a wavelength of 21 cm and has four horizontally polarized beams which cover a swath of 1.2 times the aircraft altitude. By flying a series of parallel flight lines it was possible to map the microwave brightness temperature (TB), and thus the soil moisture, over a large area. In this case the area was approximately 8 by 20 km. The moisture conditions ranged from very dry, 15%, after a heavy rain. The rain amounts ranged from less than 10 mm to more than 50 mm over the area mapped with the PBMR. With the PBMR we were able to observe the spatial variations of the rain amounts and the temporal variation as the soil dried. The TB values were registered to a Universal Transverse Mercator grid so that they could be compared to the rain gage readings and to the ground measurements of soil moisture in the 0- to 5-cm layer. The decreases in TB were well correlated with the rainfall amounts, R2 = 0.9, and the comparison of Tg with soil moisture was also good with an R2 of about 0.8. For the latter, there was some dependence of the relation on location, which may be due to soil or vegetation variations over the area mapped. The application of these data to runoff forecasts and flux estimates will be discussed.

  8. Statistics and topology of the COBE differential microwave radiometer first-year sky maps

    Science.gov (United States)

    Smoot, G. F.; Tenorio, L.; Banday, A. J.; Kogut, A.; Wright, E. L.; Hinshaw, G.; Bennett, C. L.

    1994-01-01

    We use statistical and topological quantities to test the Cosmic Background Explorer (COBE) Differential Microwave Radiometer (DMR) first-year sky maps against the hypothesis that the observed temperature fluctuations reflect Gaussian initial density perturbations with random phases. Recent papers discuss specific quantities as discriminators between Gaussian and non-Gaussian behavior, but the treatment of instrumental noise on the data is largely ignored. The presence of noise in the data biases many statistical quantities in a manner dependent on both the noise properties and the unknown cosmic microwave background temperature field. Appropriate weighting schemes can minimize this effect, but it cannot be completely eliminated. Analytic expressions are presented for these biases, and Monte Carlo simulations are used to assess the best strategy for determining cosmologically interesting information from noisy data. The genus is a robust discriminator that can be used to estimate the power-law quadrupole-normalized amplitude, Q(sub rms-PS), independently of the two-point correlation function. The genus of the DMR data is consistent with Gaussian initial fluctuations with Q(sub rms-PS) = (15.7 +/- 2.2) - (6.6 +/- 0.3)(n - 1) micro-K, where n is the power-law index. Fitting the rms temperature variations at various smoothing angles gives Q(sub rms-PS) = 13.2 +/- 2.5 micro-K and n = 1.7(sup (+0.3) sub (-0.6)). While consistent with Gaussian fluctuations, the first year data are only sufficient to rule out strongly non-Gaussian distributions of fluctuations.

  9. Microwave radiometer to retrieve temperature profiles from the surface to the stratopause

    Directory of Open Access Journals (Sweden)

    O. Stähli

    2013-03-01

    Full Text Available TEMPERA is a new ground-based radiometer which measures in a frequency range from 51–57 GHz radiation emitted by the atmosphere. The instrument operates thermally stabilized inside a lab. With this instrument it is possible to measure temperature profiles from ground to about 50 km. This is the first ground-based instrument with the capability to retrieve temperature profiles simultaneously for the troposphere and stratosphere. The measurement is done with a filterbank in combination with a digital Fast-Fourier-Transform spectrometer. A hot load and a noise diode are used as stable calibration sources. The optics consist of an off-axis parabolic mirror to collect the sky radiation. Due to the Zeeman effect on the emission lines used, the maximum height for the temperature retrieval is about 50 km. The effect is apparent in the measured spectra. The performance of TEMPERA is validated by comparison with nearby radiosonde and satellite data from the Microwave Limb Sounder on the Aura satellite. In this paper we present the design and measurement method of the instrument followed by a description of the retrieval method, together with a validation of TEMPERA data over its first year, 2012.

  10. Data Fusion Between Microwave and Thermal Infrared Radiometer Data and Its Application to Skin Sea Surface Temperature, Wind Speed and Salinity Retrievals

    Directory of Open Access Journals (Sweden)

    Kohei Arai

    2013-03-01

    Full Text Available Method for data fusion between Microwave Scanning Radiometer: MSR and Thermal Infrared Radiometer: TIR derived skin sea surface temperature: SSST, wind speed: WS and salinity is proposed. SSST can be estimated with MSR and TIR radiometer data. Although the contribution ocean depth to MSR and TIR radiometer data are different each other, SSST estimation can be refined through comparisons between MSR and TIR derived SSST. Also WS and salinity can be estimated with MSR data under the condition of the refined SSST. Simulation study results support the idea of the proposed data fusion method.

  11. Chang'E Microwave Radiometer Data Calibration with LRO Diviner Data and Machine Learning

    Science.gov (United States)

    Tsang, Ken; Hu, Guo-Ping; Zheng, Yong-Chun; This work is supported by BNU-HKBU United International College Research Grant R201626, Zhuhai Premier Discipline Enhancement Grant code: R1050, and Science and Technology Development Fund in Macao SAR 039/2013/A2

    2016-10-01

    Following usual practice in microwave remote sensing, raw data from multi-channel microwave radiometers (MR) onboard the Chinese Chang'E lunar obiters (CE1 & CE2) were acquired as observed antenna voltages, which were then calibrated and converted to brightness temperatures (TB) by a two-point calibration procedure. While the CE cold calibration antenna is supposed to point to the deep space and taking data for the cold reference point in the two-point calibration scheme, in reality, it picked up undesirable thermal microwave radiation from the lunar surface. Thus the "cold" reference point is not exactly the 2.7K cosmic background assumed and this affects the quality of the calibration.In this work, the small but puzzling differences between the two sets of Level 2C MR data released for CE1 & 2 are attributed to the difference in orbital altitudes between CE1 & 2. This leads to the different degrees of contamination to the cold antenna on CE1 & 2 by thermal radiations from the lunar surface, which showed up as persistent lower night-time TB values in the Level 2C CE2 dataset.We proposed a machine learning approach applied directly to pre-Level 2C data in the voltages to TB convertion process. Since all the antenna voltage data as well as the high temperature referencing point in the calibration procedure are directly measurable, optimized regression algorithms have been employed to determine the effective low temperature referencing points and obtain a single set of statistical consistent TB by combining raw data from CE1 & 2, due to the fact that seasonal variations are less than resolution of the CE MR data from low to medium latitudes.Finally, the Lunar Reconnaissance Orbiter (LRO) Diviner IR data are used as constraints on the boundary condition of the top layer regolith temperature to obtain a consistent sub-surface temperature profile, from which the measured CE MR data can be computed through multi-layer radiation transfer model. This step removes most of

  12. Spectroscopy underlying microwave remote sensing of atmospheric water vapor

    Science.gov (United States)

    Tretyakov, M. Yu.

    2016-10-01

    The paper presents a spectroscopist's view on the problem of recovery of the atmosphere humidity profile using modern microwave radiometers. Fundamental equations, including the description of their limitations, related to modeling of atmospheric water vapor absorption are given. A review of all reported to date experimental studies aimed at obtaining corresponding numerical parameters is presented. Best estimates of these parameters related to the Voigt (Lorentz, Gross, Van Vleck - Weisskopf and other equivalent) profile based modeling of the 22- and 183-GHz water vapor diagnostic lines and to non-resonance absorption as well as corresponding uncertainties are made on the basis of their comparative analysis.

  13. Passive Microwave Soil Moisture Retrieval through Combined Radar/Radiometer Ground Based Simulator with Special Reference to Dielectric Schemes

    Science.gov (United States)

    Srivastava, Prashant K., ,, Dr.; O'Neill, Peggy, ,, Dr.

    2014-05-01

    Soil moisture is an important element for weather and climate prediction, hydrological sciences, and applications. Hence, measurements of this hydrologic variable are required to improve our understanding of hydrological processes, ecosystem functions, and the linkages between the Earth's water, energy, and carbon cycles (Srivastava et al. 2013). The retrieval of soil moisture depends not only on parameterizations in the retrieval algorithm but also on the soil dielectric mixing models used (Behari 2005). Although a number of soil dielectric mixing models have been developed, testing these models for soil moisture retrieval has still not been fully explored, especially with SMAP-like simulators. The main objective of this work focuses on testing different dielectric models for soil moisture retrieval using the Combined Radar/Radiometer (ComRAD) ground-based L-band simulator developed jointly by NASA/GSFC and George Washington University (O'Neill et al., 2006). The ComRAD system was deployed during a field experiment in 2012 in order to provide long active/passive measurements of two crops under controlled conditions during an entire growing season. L-band passive data were acquired at a look angle of 40 degree from nadir at both horizontal & vertical polarization. Currently, there are many dielectric models available for soil moisture retrieval; however, four dielectric models (Mironov, Dobson, Wang & Schmugge and Hallikainen) were tested here and found to be promising for soil moisture retrieval (some with higher performances). All the above-mentioned dielectric models were integrated with Single Channel Algorithms using H (SCA-H) and V (SCA-V) polarizations for the soil moisture retrievals. All the ground-based observations were collected from test site-United States Department of Agriculture (USDA) OPE3, located a few miles away from NASA GSFC. Ground truth data were collected using a theta probe and in situ sensors which were then used for validation. Analysis

  14. A Novel Sensor Based on a Single-Pixel Microwave Radiometer for Warm Object Counting: Concept Validation and IoT Perspectives

    Directory of Open Access Journals (Sweden)

    Federico Alimenti

    2017-06-01

    Full Text Available Controlled measurements by a low-cost single-pixel microwave radiometer operating at 12.65 GHz were carried out to assess the detection and counting capability for targets warmer than the surroundings. The adopted reference test targets were pre-warmed water and oil; and a hand, both naked and wearing a glove. The results showed the reliability of microwave radiometry for counting operations under controlled conditions, and its effectiveness at detecting even warm targets masked by unheated dielectric layers. An electromagnetic model describing the scenario sensed by the radiometer antenna is proposed, and comparison with the experimental observations shows a good agreement. The measurements prove that reliable counting is enabled by an antenna temperature increment, for each target sample added, of around 1 K. Starting from this value, an analysis of the antenna filling factor was performed to provide an instrument useful for evaluating real applicability in many practical situations. This study also allows the direct people counting problem to be addressed, providing preliminary operational indications, reference numbers and experimental validation.

  15. A Novel Sensor Based on a Single-Pixel Microwave Radiometer for Warm Object Counting: Concept Validation and IoT Perspectives.

    Science.gov (United States)

    Alimenti, Federico; Bonafoni, Stefania; Roselli, Luca

    2017-06-14

    Controlled measurements by a low-cost single-pixel microwave radiometer operating at 12.65 GHz were carried out to assess the detection and counting capability for targets warmer than the surroundings. The adopted reference test targets were pre-warmed water and oil; and a hand, both naked and wearing a glove. The results showed the reliability of microwave radiometry for counting operations under controlled conditions, and its effectiveness at detecting even warm targets masked by unheated dielectric layers. An electromagnetic model describing the scenario sensed by the radiometer antenna is proposed, and comparison with the experimental observations shows a good agreement. The measurements prove that reliable counting is enabled by an antenna temperature increment, for each target sample added, of around 1 K. Starting from this value, an analysis of the antenna filling factor was performed to provide an instrument useful for evaluating real applicability in many practical situations. This study also allows the direct people counting problem to be addressed, providing preliminary operational indications, reference numbers and experimental validation.

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

    Science.gov (United States)

    McLinden, Matthew; Piepmeier, Jeffrey

    2013-01-01

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

  17. Soil Moisture Active Passive (SMAP) Microwave Radiometer Radio-Frequency Interference (RFI) Mitigation: Initial On-Orbit Results

    Science.gov (United States)

    Mohammed, Priscilla N.; Piepmeier, Jeffrey R.; Johnson, Joel T.; Aksoy, Mustafa; Bringer, Alexandra

    2015-01-01

    The Soil Moisture Active Passive (SMAP) mission, launched in January 2015, provides global measurements of soil moisture using a microwave radiometer. SMAPs radiometer passband lies within the passive frequency allocation. However, both unauthorized in-band transmitters as well as out-of-band emissions from transmitters operating at frequencies adjacent to this allocated spectrum have been documented as sources of radio frequency interference (RFI) to the L-band radiometers on SMOS and Aquarius. The spectral environment consists of high RFI levels as well as significant occurrences of low level RFI equivalent to 0.1 to 10 K. The SMAP ground processor reports the antenna temperature both before and after RFI mitigation is applied. The difference between these quantities represents the detected RFI level. The presentation will review the SMAP RFI detection and mitigation procedure and discuss early on-orbit RFI measurements from the SMAP radiometer. Assessments of global RFI properties and source types will be provided, as well as the implications of these results for SMAP soil moisture measurements.

  18. Forecast indices from ground-based microwave radiometer for operational meteorology

    Science.gov (United States)

    Cimini, D.; Nelson, M.; Güldner, J.; Ware, R.

    2014-07-01

    Today, commercial microwave radiometers profilers (MWRP) are robust and unattended instruments providing real time accurate atmospheric observations at ~ 1 min temporal resolution under nearly all-weather conditions. Common commercial units operate in the 20-60 GHz frequency range and are able to retrieve profiles of temperature, vapour density, and relative humidity. Temperature and humidity profiles retrieved from MWRP data are used here to feed tools developed for processing radiosonde observations to obtain values of forecast indices (FI) commonly used in operational meteorology. The FI considered here include K index, Total Totals, KO index, Showalter index, T1 Gust, Fog Threat, Lifted Index, S Index (STT), Jefferson Index, MDPI, Thompson Index, TQ Index, and CAPE. Values of FI computed from radiosonde and MWRP-retrieved temperature and humidity profiles are compared in order to quantitatively demonstrate the level of agreement and the value of continuous FI updates. This analysis is repeated for two sites at midlatitude, the first one located at low altitude in Central Europe (Lindenberg, Germany), while the second one located at high altitude in North America (Whistler, Canada). It is demonstrated that FI computed from MWRP well correlate with those computed from radiosondes, with the additional advantage of nearly continuous update. The accuracy of MWRP-derived FI is tested against radiosondes, taken as a reference, showing different performances depending upon index and environmental situation. Overall, FI computed from MWRP retrievals agree well with radiosonde values, with correlation coefficients usually above 0.8 (with few exceptions). We conclude that MWRP retrievals can be used to produce meaningful FI, with the advantage (with respect to radiosondes) of nearly continuous update.

  19. Forecast indices from a ground-based microwave radiometer for operational meteorology

    Science.gov (United States)

    Cimini, D.; Nelson, M.; Güldner, J.; Ware, R.

    2015-01-01

    Today, commercial microwave radiometer profilers (MWRPs) are robust and unattended instruments providing real-time, accurate atmospheric observations at ~ 1 min temporal resolution under nearly all weather conditions. Common commercial units operate in the 20-60 GHz frequency range and are able to retrieve profiles of temperature, vapour density, and relative humidity. Temperature and humidity profiles retrieved from MWRP data are used here to feed tools developed for processing radiosonde observations to obtain values of forecast indices (FIs) commonly used in operational meteorology. The FIs considered here include K index, total totals, KO index, Showalter index, T1 gust, fog threat, lifted index, S index (STT), Jefferson index, microburst day potential index (MDPI), Thompson index, TQ index, and CAPE (convective available potential energy). Values of FIs computed from radiosonde and MWRP-retrieved temperature and humidity profiles are compared in order to quantitatively demonstrate the level of agreement and the value of continuous FI updates. This analysis is repeated for two sites at midlatitude, the first one located at low altitude in central Europe (Lindenberg, Germany) and the second one located at high altitude in North America (Whistler, Canada). It is demonstrated that FIs computed from MWRPs well correlate with those computed from radiosondes, with the additional advantage of nearly continuous updates. The accuracy of MWRP-derived FIs is tested against radiosondes, taken as a reference, showing different performances depending upon index and environmental situation. Overall, FIs computed from MWRP retrievals agree well with radiosonde values, with correlation coefficients usually above 0.8 (with few exceptions). We conclude that MWRP retrievals can be used to produce meaningful FIs, with the advantage (with respect to radiosondes) of nearly continuous updates.

  20. Forecast indices from ground-based microwave radiometer for operational meteorology

    Directory of Open Access Journals (Sweden)

    D. Cimini

    2014-07-01

    Full Text Available Today, commercial microwave radiometers profilers (MWRP are robust and unattended instruments providing real time accurate atmospheric observations at ~ 1 min temporal resolution under nearly all-weather conditions. Common commercial units operate in the 20–60 GHz frequency range and are able to retrieve profiles of temperature, vapour density, and relative humidity. Temperature and humidity profiles retrieved from MWRP data are used here to feed tools developed for processing radiosonde observations to obtain values of forecast indices (FI commonly used in operational meteorology. The FI considered here include K index, Total Totals, KO index, Showalter index, T1 Gust, Fog Threat, Lifted Index, S Index (STT, Jefferson Index, MDPI, Thompson Index, TQ Index, and CAPE. Values of FI computed from radiosonde and MWRP-retrieved temperature and humidity profiles are compared in order to quantitatively demonstrate the level of agreement and the value of continuous FI updates. This analysis is repeated for two sites at midlatitude, the first one located at low altitude in Central Europe (Lindenberg, Germany, while the second one located at high altitude in North America (Whistler, Canada. It is demonstrated that FI computed from MWRP well correlate with those computed from radiosondes, with the additional advantage of nearly continuous update. The accuracy of MWRP-derived FI is tested against radiosondes, taken as a reference, showing different performances depending upon index and environmental situation. Overall, FI computed from MWRP retrievals agree well with radiosonde values, with correlation coefficients usually above 0.8 (with few exceptions. We conclude that MWRP retrievals can be used to produce meaningful FI, with the advantage (with respect to radiosondes of nearly continuous update.

  1. RTTOV-gb - adapting the fast radiative transfer model RTTOV for the assimilation of ground-based microwave radiometer observations

    Science.gov (United States)

    De Angelis, Francesco; Cimini, Domenico; Hocking, James; Martinet, Pauline; Kneifel, Stefan

    2016-08-01

    Ground-based microwave radiometers (MWRs) offer a new capability to provide continuous observations of the atmospheric thermodynamic state in the planetary boundary layer. Thus, they are potential candidates to supplement radiosonde network and satellite data to improve numerical weather prediction (NWP) models through a variational assimilation of their data. However in order to assimilate MWR observations, a fast radiative transfer model is required and such a model is not currently available. This is necessary for going from the model state vector space to the observation space at every observation point. The fast radiative transfer model RTTOV is well accepted in the NWP community, though it was developed to simulate satellite observations only. In this work, the RTTOV code has been modified to allow for simulations of ground-based upward-looking microwave sensors. In addition, the tangent linear, adjoint, and K-modules of RTTOV have been adapted to provide Jacobians (i.e., the sensitivity of observations to the atmospheric thermodynamical state) for ground-based geometry. These modules are necessary for the fast minimization of the cost function in a variational assimilation scheme. The proposed ground-based version of RTTOV, called RTTOV-gb, has been validated against accurate and less time-efficient line-by-line radiative transfer models. In the frequency range commonly used for temperature and humidity profiling (22-60 GHz), root-mean-square brightness temperature differences are smaller than typical MWR uncertainties (˜ 0.5 K) at all channels used in this analysis. Brightness temperatures (TBs) computed with RTTOV-gb from radiosonde profiles have been compared with nearly simultaneous and co-located ground-based MWR observations. Differences between simulated and measured TBs are below 0.5 K for all channels except for the water vapor band, where most of the uncertainty comes from instrumental errors. The Jacobians calculated with the K-module of RTTOV

  2. MIAWARA-C, a new ground based water vapor radiometer for measurement campaigns

    Directory of Open Access Journals (Sweden)

    C. Straub

    2010-09-01

    Full Text Available In this paper a new 22 GHz water vapor spectro-radiometer which has been specifically designed for profile measurement campaigns of the middle atmosphere is presented. The instrument is of a compact design and has a simple set up procedure. It can be operated as a standalone instrument as it maintains its own weather station and a calibration scheme that does not rely on other instruments or the use of liquid nitrogen. The optical system of MIAWARA-C combines a choked gaussian horn antenna with a parabolic mirror which reduces the size of the instrument in comparison with currently existing radiometers. For the data acquisition a correlation receiver is used together with a digital cross correlating spectrometer. The complete backend section, including the computer, is located in the same housing as the instrument. The receiver section is temperature stabilized to minimize gain fluctuations. Calibration of the instrument is achieved through a balancing scheme with the sky used as the cold load and the tropospheric properties are determined by performing regular tipping curves. Since MIAWARA-C is used in measurement campaigns it is important to be able to determine the elevation pointing in a simple manner as this is a crucial parameter in the calibration process. Here we present two different methods; scanning the sky and the Sun. Finally, we report on the first spectra and retrieved water vapor profiles acquired during the Lapbiat campaign at the Finnish Meteorological Institute Arctic Research Centre in Sodankylä, Finland. The performance of MIAWARA-C is validated here by comparison of the presented profiles against the equivalent profiles from the Microwave Limb Sounder on the EOS/Aura satellite.

  3. An optimal estimation algorithm to derive Ice and Ocean parameters from AMSR Microwave radiometer observations

    DEFF Research Database (Denmark)

    Pedersen, Leif Toudal; Tonboe, Rasmus T.; Høyer, Jacob

    to the ESA CCI round robin reference dataset to verify improvements. A prescribed co-variance matrix both for the a priori set of parameters and for the suite of AMSR brightness temperatures are used in addition to constrain the retrieval. These matrices are derived from an analysis of the ESA CCI round...... robin reference dataset. Over open water the reference data is a co-location of satellite SST, ERA Interim re-analysis data and observed brightness temperatures. Over ice the reference data is a co-location of ERA Interim re-analysis data, and observed AMSR microwave brightness temperatures. Due...

  4. Design and Evaluation of a Medical Microwave Radiometer for Observing Temperature Gradients Subcutaneously in the Human Body

    OpenAIRE

    2012-01-01

    Papers 1,3,4 and 5 of this thesis are not available in Munin: 1. Ø. Klemetsen, Y. Birkelund, and S. K. Jacobsen: 'Design of medical radiometer front-end for improved performance', Progress In Electromagnetics Research B (2011) Vol. 27, 289–306. Available at http://www.jpier.org/PIERB/pier.php?paper=10101204 3. Øystein Klemetsen and Svein Jacobsen: 'Improved Radiometric Performance Attained by an Elliptical Microwave Antenna With Suction', IEEE transactions on biomedical engineering (2012)59(1...

  5. The design of an in-water optical radiometer

    Digital Repository Service at National Institute of Oceanography (India)

    Desa, E.S.; Desa, B.A.E.; DeSa, E.J.

    and downwelling spectral irradiance over an effective dynamic range greater than six decades and with a spectral resolution of 2nm. The emergence of a new generation of radiometers is now practically possible with the advent of scientific grade CCD (charged couple...

  6. Some features observed by the L-band push broom microwave radiometer over the Konza Prairie during 1985-1989

    Science.gov (United States)

    Wang, J. R.

    1995-12-01

    Airborne L-band radiometric measurements were conducted over the Konza Prairie near Manhattan, Kansas, in the summers of 1985, 1987, 1988, and 1989 to study the relationship among surface microwave emission, soil moisture, and vegetation cover. The annual surface treatments that were applied to the watersheds in the experimental area appeared to show a significant impact on the surface microwave emission. A watershed that was burned every year showed a better sensitivity to soil moisture variation than those burned less frequently. This feature persisted even though the radiometric measurements were made over those watersheds that were burned in the same year. It was concluded that the burning process might not completely remove a thatch layer of efficient microwave absorption, which was developed through years of accumulation of senescent vegetation. Results from the analysis of these radiometric data sets also suggest the need of an adequate estimation of vegetation biomass in order to obtain a reliable retrieval of surface soil moisture from L-band radiometric measurements. On the basis of the data acquired from the 1987 and 1989 field campaigns, the push broom microwave radiometer (PBMR) measurements are likely to give errors of the order of ±0.065 g/cm3 in surface soil moisture estimation if there are no measurements of vegetation biomass. Measurements of vegetation biomass to an accuracy of ±0.46 kg/m2 improve the corresponding PBMR estimation of surface soil moisture to an accuracy of ±0.032 g/cm3.

  7. Comparison of stratospheric temperature profiles from a ground-based microwave radiometer with lidar, radiosonde and satellite data

    Science.gov (United States)

    Navas-Guzmán, Francisco; Kämpfer, Niklaus; Haefele, Alexander; Keckhut, Philippe; Hauchecorne, Alain

    2015-04-01

    The importance of the knowledge of the temperature structure in the atmosphere has been widely recognized. Temperature is a key parameter for dynamical, chemical and radiative processes in the atmosphere. The cooling of the stratosphere is an indicator for climate change as it provides evidence of natural and anthropogenic climate forcing just like surface warming ( [1] and references therein). However, our understanding of the observed stratospheric temperature trend and our ability to test simulations of the stratospheric response to emissions of greenhouse gases and ozone depleting substances remains limited. Stratospheric long-term datasets are sparse and obtained trends differ from one another [1]. Therefore it is important that in the future such datasets are generated. Different techniques allow to measure stratospheric temperature profiles as radiosonde, lidar or satellite. The main advantage of microwave radiometers against these other instruments is a high temporal resolution with a reasonable good spatial resolution. Moreover, the measurement at a fixed location allows to observe local atmospheric dynamics over a long time period, which is crucial for climate research. TEMPERA (TEMPERature RAdiometer) is a newly developed ground-based microwave radiometer designed, built and operated at the University of Bern. The instrument and the retrieval of temperature profiles has been described in detail in [2]. TEMPERA is measuring a pressure broadened oxygen line at 53.1 GHz in order to determine stratospheric temperature profiles. The retrieved profiles of TEMPERA cover an altitude range of approximately 20 to 45 km with a vertical resolution in the order of 15 km. The lower limit is given by the instrumental baseline and the bandwidth of the measured spectrum. The upper limit is given by the fact that above 50 km the oxygen lines are splitted by the Zeeman effect in the terrestrial magnetic field. In this study we present a comparison of stratospheric

  8. Correction of Tropospheric Refraction Errors with a Microwave Radiometer%对流层大气折射误差的微波辐射计修正

    Institute of Scientific and Technical Information of China (English)

    李江漫; 韩恒敏; 林乐科; 郭立新; 赵振维; 舒婷婷

    2012-01-01

    The requirements of tracking and positioning with radars and satellite orbit tracking and determination on correction of atmospheric refraction error are higher and higher nowadays. Traditional atmospheric refraction error correction methods are costly and have poor realtime performance. This paper proposes a method of inversion computation of atmospheric refraction ratio from brightness temperature measured by a dual channel microwave radiometer sensitive to water vapor and liquid water content. The result is compared with the result of sounding rockets. The mean bias and root mean square of inversion error of different heights are calculated. The results show that the refractive index profile retrieved by a radiometer is close to the real value and this verifies feasibility of the method. A new calibration method for microwave radiometer and a method for correction of refraction error of horizontally non-homogeneous atmosphere are also presented.%目前,雷达的目标跟踪定位、卫星的测控定轨等对大气折射误差高精度修正的要求越来越高.针对传统大气折射误差修正方法的成本高、实时性差等问题,研究利用对水汽和液态水含量敏感的双通道微波辐射计测得的辐射亮温来反演大气折射率的方法.对微波辐射计的反演结果和探空数据的结果进行比较,计算不同海拔高度上反演的平均偏差和均方差,发现利用微波辐射计反演得到的折射率剖面与探空值吻合较好,验证了此方法的可行性.同时介绍了微波辐射计新的定标方法和微波辐射计对于水平不均匀大气的折射误差修正方法.

  9. RTTOV-gb - Adapting the fast radiative transfer model RTTOV for the assimilation of ground-based microwave radiometer observations

    Science.gov (United States)

    De Angelis, Francesco; Cimini, Domenico; Hocking, James; Martinet, Pauline; Kneifel, Stefan

    2016-04-01

    The Planetary Boundary Layer (PBL) is the single most important under-sampled part of the atmosphere. According to the WMO Statement Of Guidance For Global Numerical Weather Prediction (NWP), temperature and humidity profiles (in cloudy areas) are among the four critical atmospheric variables not adequately measured in the PBL. Ground-based microwave radiometers (MWR) provide temperature and humidity profiles in both clear- and cloudy-sky conditions with high temporal resolution and low-to-moderate vertical resolution, with information mostly residing in the PBL. Ground-based MWR offer to bridge this observational gap by providing continuous temperature and humidity information in the PBL. The MWR data assimilation into NWP models may be particularly important in nowcasting and severe weather initiation. The assimilation of thermodynamic profiles retrieved from MWR data has been recently experimented, but a way to possibly increase the impact is to directly assimilate measured radiances instead of retrieved profiles. The assimilation of observed radiances in a variational scheme requires the following tools: (i) a fast radiative transfer (RT) model to compute the simulated radiances at MWR channels from the NWP model fields (ii) the partial derivatives (Jacobians) of the fast radiative transfer model with respect to control variables to optimize the distances of the atmospheric state from both the first guess and the observations. Such a RT model is available from the EUMETSAT NWPSAF (Numerical Weather Prediction Satellite Application Facility) and well accepted in the NWP community: RTTOV. This model was developed for nadir-viewing passive visible, infrared, and microwave satellite radiometers, spectrometers and interferometers. It has been modified to handle ground-based microwave radiometer observations. This version of RTTOV, called RTTOV-gb, provides the tools needed to exploit ground-based upward looking MWR brightness temperatures into NWP variational data

  10. Radiometer Testbed Development for SWOT

    Science.gov (United States)

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

    2010-01-01

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

  11. Artificial neural network approach for estimation of surface specific humidity and air temperature using Multifrequency Scanning Microwave Radiometer

    Indian Academy of Sciences (India)

    Randhir Singh; B G Vasudevan; P K Pal; P C Joshi

    2004-03-01

    Microwave sensor MSMR (Multifrequency Scanning Microwave Radiometer) data onboard Oceansat-1 was used for retrieval of monthly averages of near surface specific humidity (a) and air temperature (a) by means of Artificial Neural Network (ANN). The MSMR measures the microwave radiances in 8 channels at frequencies of 6.6, 10.7, 18 and 21 GHz for both vertical and horizontal polarizations. The artificial neural networks (ANN) technique is employed to find the transfer function relating the input MSMR observed brightness temperatures and output (a and a) parameters. Input data consist of nearly 28 months (June 1999 — September 2001) of monthly averages of MSMR observed brightness temperature and surface marine observations of a and a from Comprehensive Ocean- Atmosphere Data Set (COADS). The performance of the algorithm is assessed with independent surface marine observations. The results indicate that the combination of MSMR observed brightness temperatures as input parameters provides reasonable estimates of monthly averaged surface parameters. The global root mean square (rms) differences are 1.0°C and 1.1 g kg−1 for air temperature and surface specific humidity respectively.

  12. Tunable Water-based Microwave Metasurface

    DEFF Research Database (Denmark)

    Kapitanova, Polina; Odit, Mikhail; Dobrykh, Dmitry

    2017-01-01

    A water-based dynamically tunable microwave metasurface is developed and experimentally investigated. A simple approach to tune the metasurface properties by changing the shape of water-based unit cells by gravitation force is proposed. The transmission spectra of the metasurface for linear...... angle. The proposed approach can be used to design cheap metasurfaces for electromagnetic wave control in the microwave frequency range....

  13. Radiant Temperature Nulling Radiometer

    Science.gov (United States)

    2002-01-01

    A nulling, self-calibrating infrared radiometer is being developed for use in noncontact measurement of temperature in any of a variety of industrial and scientific applications. This instrument is expected to be especially well-suited to measurement of ambient or near-ambient temperature and, even more specifically, for measuring the surface temperature of a natural body of water. Although this radiometer would utilize the long-wavelength infrared (LWIR) portion of the spectrum (wavelengths of 8 to 12 m), its basic principle of operation could also be applied to other spectral bands (corresponding to other temperature ranges) in which the atmosphere is transparent and in which design requirements for sensitivity and temperature-measurement accuracy could be satisfied. The underlying principle of nulling and self-calibration is the same as that of a typical microwave radiometer, but because of differences between the characteristics of signals in the infrared and microwave spectral regions, the principle must be implemented in a different way. A detailed description of the instrument including an infrared photodetector equipped with focusing input optics [e.g., lens(es) and/or mirrors] and an input LWIR band-pass filter is presented.

  14. A General Analysis of the Impact of Digitization in Microwave Correlation Radiometers

    Directory of Open Access Journals (Sweden)

    Hyuk Park

    2011-06-01

    Full Text Available This study provides a general framework to analyze the effects on correlation radiometers of a generic quantization scheme and sampling process. It reviews, unifies and expands several previous works that focused on these effects separately. In addition, it provides a general theoretical background that allows analyzing any digitization scheme including any number of quantization levels, irregular quantization steps, gain compression, clipping, jitter and skew effects of the sampling period.

  15. Spectral irradiance measurement and actinic radiometer calibration for UV water disinfection

    Science.gov (United States)

    Sperfeld, Peter; Barton, Bettina; Pape, Sven; Towara, Anna-Lena; Eggers, Jutta; Hopfenmüller, Gabriel

    2014-12-01

    In a joint project, sglux and PTB investigated and developed methods and equipment to measure the spectral and weighted irradiance of high-efficiency UV-C emitters used in water disinfection plants. A calibration facility was set up to calibrate the microbicidal irradiance responsivity of actinic radiometers with respect to the weighted spectral irradiance of specially selected low-pressure mercury and medium-pressure mercury UV lamps. To verify the calibration method and to perform on-site tests, spectral measurements were carried out directly at water disinfection plants in operation. The weighted microbicidal irradiance of the plants was calculated and compared to the measurements of various actinic radiometers.

  16. Botswana water and surface energy balance research program. Part 2: Large scale moisture and passive microwaves

    Science.gov (United States)

    Vandegriend, A. A.; Owe, M.; Chang, A. T. C.

    1992-01-01

    The Botswana water and surface energy balance research program was developed to study and evaluate the integrated use of multispectral satellite remote sensing for monitoring the hydrological status of the Earth's surface. The research program consisted of two major, mutually related components: a surface energy balance modeling component, built around an extensive field campaign; and a passive microwave research component which consisted of a retrospective study of large scale moisture conditions and Nimbus scanning multichannel microwave radiometer microwave signatures. The integrated approach of both components are explained in general and activities performed within the passive microwave research component are summarized. The microwave theory is discussed taking into account: soil dielectric constant, emissivity, soil roughness effects, vegetation effects, optical depth, single scattering albedo, and wavelength effects. The study site is described. The soil moisture data and its processing are considered. The relation between observed large scale soil moisture and normalized brightness temperatures is discussed. Vegetation characteristics and inverse modeling of soil emissivity is considered.

  17. Emissivity measurements in thin metallized membrane reflectors used for microwave radiometer sensors

    Science.gov (United States)

    Schroeder, Lyle C.; Cravey, Robin L.; Scherner, Michael J.; Hearn, Chase P.; Blume, Hans-Juergen C.

    1995-01-01

    This paper is concerned with electromagnetic losses in metallized films used for inflatable reflectors. An inflatable membrane is made of tough elastic material such as Kapton, and it is not electromagnetically reflective by design. A film of conducting metal is added to the membrane to enhance its reflective properties. Since the impetus for use of inflatables for spacecraft is the light weight and compact packaging, it is important that the metal film be as thin as possible. However, if the material is not conductive or thick enough, the radiation due to the emissivity of the reflector could be a significant part of the radiation gathered by the radiometer. The emissivity would be of little consequence to a radar or solar collector; but for a radiometer whose signal is composed of thermal radiation, this contribution could be severe. Bulk properties of the metal film cannot be used to predict its loss. For this reason, a program of analysis and measurement was undertaken to determine the emissivities of a number of candidate metallized film reflectors. This paper describes the three types of measurements which were performed on the metallized thin films: (1) a network analyzer system with an L-band waveguide; (2) an S-band radiometer; and (3) a network analyzer system with a C-band antenna free-space transmission system.

  18. Electronic Correlated Noise Calibration Standard for Interferometric and Polarimetric Microwave Radiometers Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A new type of calibration standard is proposed which produces a pair of microwave noise signals to aid in the characterization and calibration of correlating...

  19. Electronic Correlated Noise Calibration Standard for Interferometric and Polarimetric Microwave Radiometers Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A new type of calibration standard is proposed which produces a pair of microwave noise signals to aid in the characterization and calibration of correlating...

  20. Sentinel-3 MWR Microwave Radiometer – Our contribution to the success of the Copernicus programme

    Directory of Open Access Journals (Sweden)

    M.A. Palacios

    2014-06-01

    Full Text Available The MWR builds, together with the SRAL altimeter, the S3 topography mission. The MWR, developed by EADS CASA Espacio as prime contractor, provides information for tropospheric path correction of SRAL measurements. MWR data can also be used for determining surface emissivity and soil moisture over land, surface energy budget investigations and ice characterization. The MWR instrument is a Noise Injection Radiometer (NIR, working at two frequencies (23.8/36.5 GHz, embarking a dual frequency horn antenna pointing to the cold sky for embedded autonomous calibration.

  1. Thermal behavior of regolith at cold traps on the moon's south pole: Revealed by Chang'E-2 microwave radiometer data

    Science.gov (United States)

    Wei, Guangfei; Li, Xiongyao; Wang, Shijie

    2016-03-01

    The long-term stability of water ice at cold traps depends on subsurface temperature and regolith thermophysical properties. Based on Chang'E-2 microwave radiometer data, we have inverted attenuation coefficient, thermal gradient and instantaneous temperature profiles at permanently shaded craters (Cabeus, Haworth and Shoemaker) on the Moon's south pole. The nonuniformity of the inverted attenuation coefficient within the craters reflects the inhomogeneous thermophysical properties of regolith. In addition, thermal gradient decreased significantly from the crater walls to the bottoms, which may be caused by scattered sunlight, internal heat flux and earthshine effect. Considering continuous supplement of water ice (with volumetric fraction 0-10%) at cold traps, it changes subsurface thermophysical properties but has little effect on thermal gradient. We also assumed that abundant ice (10%) mixed with regolith, the inversion results showed that the maximum difference of diurnal temperatures between "wet" and dry regolith were no more than 0.5 K. That is, the effect of water ice on subsurface thermal behavior can be neglected.

  2. Evaluation of Data from the Multi-frequency Scanning Microwave Radiometer (MSMR) and Its Potential for Soil Moisture Retrieval

    Science.gov (United States)

    Wen, J.; Jackson, T. J.; Bindlish, R.; Su, Z. B.

    2003-12-01

    The Multi-frequency Scanning Microwave Radiometer (MSMR) aboard the India Space Research Organization - Oceansat-1 (IRS-P4) platform measured land surface brightness temperature at low frequencies and provided an opportunity for exploring large-scale soil moisture retrieval during its two years period of observation. Several data issues had to be addressed before using the data. These included geolocation errors, data calibration and anthropogenic Radio-frequency Interference (RFI). Calibration was evaluated by comparisons to the Tropical Rainfall Measuring Mission/Microwave Imager (TRMM/TMI) measured brightness temperatures. A negative bias of 3.4 and 3.6 K were observed for the 10.6 GHz horizontal and vertical polarization bands respectively, negative differences of 14.0 and 10.1 K were found between the MSMR 6.6 GHz and TMI 10.6 GHz horizontal and vertical polarizations over land surface. These results suggested that additional calibration of the MSMR data was required. Comparisons between the MSMR measured brightness temperature and ground measured volumetric soil moisture collected during two field campaigns indicated that the lower frequency and horizontal polarization had higher sensitivity to the ground soil moisture. Using a previously developed soil emission model, multi-temporal soil moisture was retrieved for the continental United States. Comparisons between the MSMR based soil moisture and ground measured volumetric soil moisture indicated an uncertain error of 3.8 percent in the estimated soil moisture. This data may provide a valuable extension to the SMMR and AMSR instruments since it covers a portion of the time between the two missions. Keywords: passive microwave, brightness temperature, soil moisture, satellite remote sensing.

  3. Determination of Cloud Ice Water Content and Geometrical Thickness Using Microwave and Infrared Radiometric Measurements.

    Science.gov (United States)

    Wu, Man-Li C.

    1987-08-01

    Cloud ice water content and cloud geometrical thickness have been determined using a combination of near-infrared, thermal infrared and thermal microwave radiometric measurements. The radiometric measurements are from a Multispectral Cloud Radiometer, which has seven channels ranging from visible to thermal infrared, and an Advanced Microwave Moisture Sounder, which has four channels ranging from 90 to 183 GHz. Studies indicate that the microwave brightness temperatures depend not only on the amount of ice water content but also on the vertical distribution of ice water content. Studies also show that the low brightness temperature at 92 GHz for large ice water content is due to cloud reflection which reflects most of the irradiance incident at the cloud base downward. Therefore the 92 GHz channel detects a low brightness temperature at the cloud top.

  4. GHRSST Level 2P Regional Subskin Sea Surface Temperature from the Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E) on the NASA Aqua satellite for the Atlantic Ocean (GDS version 1)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Advanced Microwave Scanning Radiometer (AMSR-E) was launched on 4 May 2002, aboard NASA's Aqua spacecraft. The National Space Development Agency of Japan (NASDA)...

  5. GHRSST Level 2P Gridded Global Subskin Sea Surface Temperature from the Advanced Scanning Microwave Radiometer - Earth Observing System (AMSR-E) on the NASA Aqua Satellite (GDS version 1)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Advanced Microwave Scanning Radiometer (AMSR-E) was launched on 4 May 2002, aboard NASA's Aqua spacecraft. The National Space Development Agency of Japan (NASDA)...

  6. GHRSST Level 2P Global Subskin Sea Surface Temperature from the Advanced Scanning Microwave Radiometer - Earth Observing System (AMSR-E) on the NASA Aqua Satellite (GDS versions 1 and 2)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Advanced Microwave Scanning Radiometer (AMSR-E) was launched on 4 May 2002, aboard NASA's Aqua spacecraft. The National Space Development Agency of Japan (NASDA)...

  7. First middle-atmospheric zonal wind profile measurements with a new ground-based microwave Doppler-spectro-radiometer

    Directory of Open Access Journals (Sweden)

    R. Rüfenacht

    2012-11-01

    Full Text Available We report on the wind radiometer WIRA, a new ground-based microwave Doppler-spectro-radiometer specifically designed for the measurement of middle-atmospheric horizontal wind by observing ozone emission spectra at 142.17504 GHz. Currently, wind speeds in five levels between 30 and 79 km can be retrieved which makes WIRA the first instrument able to continuously measure horizontal wind in this altitude range. For an integration time of one day the measurement error on each level lies at around 25 m s−1. With a planned upgrade this value is expected to be reduced by a factor of 2 in the near future. On the altitude levels where our measurement can be compared to wind data from the European Centre for Medium-Range Weather Forecasts (ECMWF very good agreement in the long-term statistics as well as in short time structures with a duration of a few days has been found.

    WIRA uses a passive double sideband heterodyne receiver together with a digital Fourier transform spectrometer for the data acquisition. A big advantage of the radiometric approach is that such instruments can also operate under adverse weather conditions and thus provide a continuous time series for the given location. The optics enables the instrument to scan a wide range of azimuth angles including the directions east, west, north, and south for zonal and meridional wind measurements. The design of the radiometer is fairly compact and its calibration does not rely on liquid nitrogen which makes it transportable and suitable for campaign use. WIRA is conceived in a way that it can be operated remotely and does hardly require any maintenance.

    In the present paper, a description of the instrument is given, and the techniques used for the wind retrieval based on the determination of the Doppler shift of the measured atmospheric ozone emission spectra are outlined. Their reliability was tested using Monte Carlo simulations. Finally, a time series of 11

  8. 全极化微波辐射计数字化引入误差分析%The Error Analysis of Digital Technology in Polarimetric Microwave Radiometer

    Institute of Scientific and Technical Information of China (English)

    陆浩; 王振占

    2013-01-01

    全极化微波辐射计是一种用于海洋表面风场测量的新型被动微波遥感器。数字相关器是全极化辐射计的核心部件。数字相关器的应用相对于模拟相关辐射计具有可配置、集成度高和易于控制的特点。同时,数字化技术会给辐射计带来量化误差和相位抖动误差。具体的误差分析验证了全极化微波辐射计中数字化的可行性。文中详细分析了定量误差,并根据实际工程应用说明了多比特数字化带来的误差可以在系统整体误差中忽略。%Polarimetric microwave radiometer is a new passive microwave remote sensor used to measure ocean surface wind field .Digital correlator is the core component of polarimetric radiometer .Compared to analog correlator ,the digital correlator ra-diometer has the configurable ,highly integrated and easy-to-control features/At the same time ,digital technology will bring ra-diometer quantization error and phase jitter .Detailed error analysis is the way to verify the feasibility of digital technology in fully polarimetric microwave radiometer .The quantitative error is analyzed .According to practical application ,the error caused by multi-bit digital technology can be ignored in the overall system .

  9. In-situ Microwave Brightness Temperature Variability from Ground-based Radiometer Measurements at Dome C in Antarctica Induced by Wind-formed Features

    Science.gov (United States)

    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).

  10. Microwave and Millimeter-Wave Radiometric Studies of Temperature, Water Vapor and Clouds

    Energy Technology Data Exchange (ETDEWEB)

    Westwater, Edgeworth

    2011-05-06

    The importance of accurate measurements of column amounts of water vapor and cloud liquid has been well documented by scientists within the Atmospheric Radiation Measurement (ARM) Program. At the North Slope of Alaska (NSA), both microwave radiometers (MWR) and the MWRProfiler (MWRP), been used operationally by ARM for passive retrievals of the quantities: Precipitable Water Vapor (PWV) and Liquid Water Path (LWP). However, it has been convincingly shown that these instruments are inadequate to measure low amounts of PWV and LWP. In the case of water vapor, this is especially important during the Arctic winter, when PWV is frequently less than 2 mm. For low amounts of LWP (< 50 g/m{sup 2}), the MWR and MWRP retrievals have an accuracy that is also not acceptable. To address some of these needs, in March-April 2004, NOAA and ARM conducted the NSA Arctic Winter Radiometric Experiment - Water Vapor Intensive Operational Period at the ARM NSA/Adjacent Arctic Ocean (NSA/AAO) site. After this experiment, the radiometer group at NOAA moved to the Center for Environmental Technology (CET) of the Department of Electrical and Computer Engineering of the University of Colorado at Boulder. During this 2004 experiment, a total of 220 radiosondes were launched, and radiometric data from 22.235 to 380 GHz were obtained. Primary instruments included the ARM MWR and MWRP, a Global Positioning System (GPS), as well as the CET Ground-based Scanning Radiometer (GSR). We have analyzed data from these instruments to answer several questions of importance to ARM, including: (a) techniques for improved water vapor measurements; (b) improved calibration techniques during cloudy conditions; (c) the spectral response of radiometers to a variety of conditions: clear, liquid, ice, and mixed phase clouds; and (d) forward modeling of microwave and millimeter wave brightness temperatures from 22 to 380 GHz. Many of these results have been published in the open literature. During the third year of

  11. Combining Satellite Microwave Radiometer and Radar Observations to Estimate Atmospheric Latent Heating Profiles

    Science.gov (United States)

    Grecu, Mircea; Olson, William S.; Shie, Chung-Lin; L'Ecuyer, Tristan S.; Tao, Wei-Kuo

    2009-01-01

    In this study, satellite passive microwave sensor observations from the TRMM Microwave Imager (TMI) are utilized to make estimates of latent + eddy sensible heating rates (Q1-QR) in regions of precipitation. The TMI heating algorithm (TRAIN) is calibrated, or "trained" using relatively accurate estimates of heating based upon spaceborne Precipitation Radar (PR) observations collocated with the TMI observations over a one-month period. The heating estimation technique is based upon a previously described Bayesian methodology, but with improvements in supporting cloud-resolving model simulations, an adjustment of precipitation echo tops to compensate for model biases, and a separate scaling of convective and stratiform heating components that leads to an approximate balance between estimated vertically-integrated condensation and surface precipitation. Estimates of Q1-QR from TMI compare favorably with the PR training estimates and show only modest sensitivity to the cloud-resolving model simulations of heating used to construct the training data. Moreover, the net condensation in the corresponding annual mean satellite latent heating profile is within a few percent of the annual mean surface precipitation rate over the tropical and subtropical oceans where the algorithm is applied. Comparisons of Q1 produced by combining TMI Q1-QR with independently derived estimates of QR show reasonable agreement with rawinsonde-based analyses of Q1 from two field campaigns, although the satellite estimates exhibit heating profile structure with sharper and more intense heating peaks than the rawinsonde estimates. 2

  12. A Bayesian Retrieval of Greenland Ice Sheet Internal Temperature from Ultra-wideband Software-defined Microwave Radiometer (UWBRAD) Measurements

    Science.gov (United States)

    Duan, Y.; Durand, M. T.; Jezek, K. C.; Yardim, C.; Bringer, A.; Aksoy, M.; Johnson, J.

    2015-12-01

    The ultra-wideband software-defined microwave radiometer (UWBRAD) is designed to provide ice sheet internal temperature product via measuring low frequency microwave emission. Twelve channels ranging from 0.5 to 2.0 GHz are covered by the instrument. A Bayesian framework was designed to retrieve the ice sheet internal temperature from UWBRAD brightness temperature (Tb) measurements for the Greenland air-borne demonstration scheduled for summer 2016. Several parameters would affect the ice sheet physical temperature. And the effective surface temperature, geothermal heat flux and the variance of upper layer ice density were treated as unknown random variables within the retrieval framework. Synthetic brightness temperature were calculated by the snow radiation transfer models as a function of ice temperature, ice density, and an estimate of snow grain size in the upper layers. A incoherent model-the Microwave Emission Model of Layered Snowpacks (MEMLS) and a coherent model were used respectively to estimate the influence of coherent effect. The inputs of the radiation transfer model were generated from a 1-D heat-flow equation developed by Robin and a exponential fit of ice density variation from Borehole measurement. The simulated Tb was corrupted with white noise and served as UWBRAD observation in retrieval. A look-up table was developed between the parameters and the corresponding Tb. In the Bayesian retrieval process, each parameter was defined with its possible range and set to be uniformly distributed. The Markov Chain Monte Carlo (MCMC) approach was applied to make the unknown parameters randomly walk in the parameter space. Experiment results were examined for science goals on three levels: estimation of the 10-m firn temperature, the average temperature integrated with depth, and the entire temperature profile. The 10-m temperature was estimated to within 0.77 K, with a bias of 0.6 K, across the 47 locations on the ice sheet; the 10-m "synthetic true

  13. A millimeter and sub-millimeter wave frequency selective surface beamsplitter for geostationary orbit microwave radiometers

    Institute of Scientific and Technical Information of China (English)

    Cui Guang-Bin; Zhao Hai-Bo; Zhang Yong-Fang; Miao Jun-Gang

    2012-01-01

    We report the design of three frequency selective surface (FSS) filters used on the FengYun-4 (FY-4) microwave satellite,which separate five-frequency bands in the frequency range of 50-429 GHz with the insertion loss less than 0.4 dB,and separation between adjacent channels more than 20 dB for either TE or TM incidence.Firstly,we briefly introduce the disadvantages of two types of FSS filter: waveguide-array FSS and printed FSS,which are commonly employed in the millimeter and sub-millimeter wave band.In order to meet the insertion loss requirement and specified spectral transmission response,we adopt a filter composed of two closely spaced freestanding metal plates,which contains an array of resonant ring slot elements.Computer simulation technology (CST) is used to optimize the structural dimensions of the resonant unit and interlayer separation.Numerical results show that these FSS filters exhibit transmission loss of less than 0.4 dB and separation between adjacent channels of more than 20 dB.Simulated transmission coefficients are in close agreement with the required specification,and even exceed the performance specifications.

  14. PHOCUS radiometer

    Directory of Open Access Journals (Sweden)

    O. Nyström

    2012-01-01

    Full Text Available PHOCUS – Particles, Hydrogen and Oxygen Chemistry in the Upper Summer Mesosphere is a Swedish sounding rocket experiment, launched in July 2011, with the main goal of investigating the upper atmosphere in the altitude range 50–110 km. This paper describes the SondRad instrument in the PHOCUS payload, the radiometer comprising two frequency channels, 183 GHz and 557 GHz, aimed at exploring the water vapour concentration distribution in connection with the appearance of noctilucent (night shining clouds. The design of the radiometer system has been done in a collaboration between Omnisys Instruments AB and the Group for Advanced Receiver Development (GARD at Chalmers University of Technology where Omnisys was responsible for the overall design, implementation, and verification of the radiometers and backend whereas GARD was responsible for the radiometer optics and calibration systems.

    The SondRad instrument covers the water absorption lines at 183 GHz and 557 GHz. The 183 GHz channel is a side-looking radiometer while the 557 GHz radiometer is placed along the rocket axis looking in the forward direction. Both channels employ sub-harmonically pumped Schottky mixers and FFT spectrometer backends with 67 kHz resolution.

    The radiometers include novel calibration systems specifically adjusted for use with each frequency channel. The 183 GHz channel employs a CW-pilot signal calibrating the entire receiving chain while the IF-chain of the 557 GHz channel is calibrated by injecting a signal from a reference noise source through a directional coupler.

    The instrument collected complete spectra for both the 183 GHz and the 557 GHz with 300 Hz data rate for the 183 GHz channel and 10 Hz data rate for the 557 GHz channel for about 60 s reaching the apogee of the flight trajectory and 100 s after that. With lossless data compression using variable resolution over the spectrum, the data set was reduced to 2 × 12 MByte.

  15. PHOCUS radiometer

    Directory of Open Access Journals (Sweden)

    O. Nyström

    2012-06-01

    Full Text Available PHOCUS – Particles, Hydrogen and Oxygen Chemistry in the Upper Summer Mesosphere is a Swedish sounding rocket experiment, launched in July 2011, with the main goal of investigating the upper atmosphere in the altitude range 50–110 km. This paper describes the SondRad instrument in the PHOCUS payload, a radiometer comprising two frequency channels (183 GHz and 557 GHz aimed at exploring the water vapour concentration distribution in connection with the appearance of noctilucent (night shining clouds. The design of the radiometer system has been done in a collaboration between Omnisys Instruments AB and the Group for Advanced Receiver Development (GARD at Chalmers University of Technology where Omnisys was responsible for the overall design, implementation, and verification of the radiometers and backend, whereas GARD was responsible for the radiometer optics and calibration systems.

    The SondRad instrument covers the water absorption lines at 183 GHz and 557 GHz. The 183 GHz channel is a side-looking radiometer, while the 557 GHz radiometer is placed along the rocket axis looking in the forward direction. Both channels employ sub-harmonically pumped Schottky mixers and Fast Fourier Transform Spectrometers (FFTS backends with 67 kHz resolution.

    The radiometers include novel calibration systems specifically adjusted for use with each frequency channel. The 183 GHz channel employs a continuous wave CW pilot signal calibrating the entire receiving chain, while the intermediate frequency chain (the IF-chain of the 557 GHz channel is calibrated by injecting a signal from a reference noise source through a directional coupler.

    The instrument collected complete spectra for both the 183 GHz and the 557 GHz with 300 Hz data rate for the 183 GHz channel and 10 Hz data rate for the 557 GHz channel for about 60 s reaching the apogee of the flight trajectory and 100 s after that. With lossless data compression using variable

  16. Performance test of the synergetic use of simulated lidar and microwave radiometer observations for mixing-layer height detection

    Science.gov (United States)

    Saeed, Umar; Rocadenbosch, Francesc; Crewell, Susanne

    2015-10-01

    There are several instruments and methods to retrieve the atmospheric Mixing Layer Height (MLH). However, none of these instruments or methods can measure the development of the MLH under all atmospheric conditions. For example, aerosol signatures measured by backscatter lidars can be used to determine the MLH but this approach is reasonable only when the atmosphere is well-mixed. Microwave Radiometer (MWR) derived profiles have low vertical resolution and cannot resolve fine structures in the boundary layer, especially, at higher altitudes. Here we propose a method which combines data from a ground-based lidar and a MWR, in simulated as well as real measurements scenarios, to overcome these limitations. The method works by fitting an erf-like transition model function to the section of range-corrected lidar backscatter signal. The section of the lidar backscatter signal for fitting the model function is obtained by incorporating the MWR estimates of MLH along with their uncertainties. The fitting is achieved by using an extended Kalman filter (EKF). The proposed approach, by exploiting the synergy between the two instruments, enables to detect MLH with original vertical and temporal resolutions. Test cases combining simulated data for a co-located lidar-ceilometer and a MWR are presented. The simulated data is obtained from the Dutch Atmospheric Large Eddy Simulation (DALES) model for boundary layer studies. Doppler wind lidar along with radiosondes (whenever available) data is used to assess the quality of the synergetic MLH estimates. Data from the HD(CP)2 Observational Prototype Experiment (HOPE) campaign at Jülich, Germany is used to test the proposed method.

  17. Validation of brightness and physical temperature from two scanning microwave radiometers in the 60 GHz O2 band using radiosonde measurements

    Science.gov (United States)

    Navas-Guzmán, Francisco; Kämpfer, Niklaus; Haefele, Alexander

    2016-09-01

    In this paper, we address the assessment of the tropospheric performance of a new temperature radiometer (TEMPERA) at 60 GHz. With this goal, an intercomparison campaign was carried out at the aerological station of MeteoSwiss in Payerne (Switzerland). The brightness temperature and the tropospheric temperature were assessed by means of a comparison with simultaneous and collocated radiosondes that are launched twice a day at this station. In addition, the TEMPERA performances are compared with the ones from a commercial microwave radiometer (HATPRO), which has some different instrumental characteristics and uses a different inversion algorithm. Brightness temperatures from both radiometers were compared with the ones simulated using a radiative transfer model and atmospheric profiles from radiosondes. A total of 532 cases were analyzed under all weather conditions and evidenced larger brightness temperature deviations between the two radiometers and the radiosondes for the most transparent channels. Two different retrievals for the TEMPERA radiometer were implemented in order to evaluate the effect of the different channels on the temperature retrievals. The comparison with radiosondes evidenced better results very similar to the ones from HATPRO, when the eight more opaque channels were used. The study shows the good performance of TEMPERA to retrieve temperature profiles in the troposphere. The inversion method of TEMPERA is based on the optimal estimation method. The main advantage of this algorithm is that there is no necessity for radiosonde information to achieve good results in contrast to conventional methods as neural networks or lineal regression. Finally, an assessment of the effect of instrumental characteristics as the filter response and the antenna pattern on the brightness temperature showed that they can have an important impact on the most transparent channels.

  18. Can liquid water profiles be retrieved from passive microwave zenith observations?

    Science.gov (United States)

    Crewell, Susanne; Ebell, Kerstin; Löhnert, Ulrich; Turner, D. D.

    2009-03-01

    The ability to determine the cloud boundaries and vertical distribution of cloud liquid water for single-layer liquid clouds using zenith-pointing microwave radiometers is investigated. Simulations are used to demonstrate that there is little skill in determining either cloud base or cloud thickness, especially when the cloud thickness is less than 500 m. It is also shown that the different distributions of liquid water content within a cloud with known cloud boundaries results in a maximum change in the brightness temperature of less than 1 K at the surface from 20 to 150 GHz, which is on the order of the instrument noise level. Furthermore, it is demonstrated using the averaging kernel that the number of degrees of freedom for signal (i.e., independent pieces of information) is approximately 1, which implies there is no information on vertical distribution of liquid water in the microwave observations.

  19. Applying the Water Vapor Radiometer to Verify the Precipitable Water Vapor Measured by GPS

    Directory of Open Access Journals (Sweden)

    Ta-Kang Yeh

    2014-01-01

    Full Text Available Taiwan is located at the land-sea interface in a subtropical region. Because the climate is warm and moist year round, there is a large and highly variable amount of water vapor in the atmosphere. In this study, we calculated the Zenith Wet Delay (ZWD of the troposphere using the ground-based Global Positioning System (GPS. The ZWD measured by two Water Vapor Radiometers (WVRs was then used to verify the ZWD that had been calculated using GPS. We also analyzed the correlation between the ZWD and the precipitation data of these two types of station. Moreover, we used the observational data from 14 GPS and rainfall stations to evaluate three cases. The offset between the GPS-ZWD and the WVR-ZWD ranged from 1.31 to 2.57 cm. The correlation coefficient ranged from 0.89 to 0.93. The results calculated from GPS and those measured using the WVR were very similar. Moreover, when there was no rain, light rain, moderate rain, or heavy rain, the flatland station ZWD was 0.31, 0.36, 0.38, or 0.40 m, respectively. The mountain station ZWD exhibited the same trend. Therefore, these results have demonstrated that the potential and strength of precipitation in a region can be estimated according to its ZWD values. Now that the precision of GPS-ZWD has been confirmed, this method can eventually be expanded to the more than 400 GPS stations in Taiwan and its surrounding islands. The near real-time ZWD data with improved spatial and temporal resolution can be provided to the city and countryside weather-forecasting system that is currently under development. Such an exchange would fundamentally improve the resources used to generate weather forecasts.

  20. Water, Hydrogen Bonding and the Microwave Background

    Directory of Open Access Journals (Sweden)

    Robitaille P.-M.

    2009-04-01

    Full Text Available n this work, the properties of the water are briefly revisited. Though liquid water has a fleeting structure, it displays an astonishingly stable network of hydrogen bonds. Thus, even as a liquid, water possesses a local lattice with short range order. The presence of hydroxyl (O-H and hydrogen (H....OH2 bonds within water, indicate that it can simultaneously maintain two separate energy systems. These can be viewed as two very different temperatures. The analysis presented uses results from vibrational spec- troscopy, extracting the force constant for the hydrogen bonded dimer. By idealizing this species as a simple diatomic structure, it is shown that hydrogen bonds within wa- ter should be able to produce thermal spectra in the far infrared and microwave regions of the electromagnetic spectrum. This simple analysis reveals that the oceans have a physical mechanism at their disposal, which is capable of generating the microwave background.

  1. Comparison of Relative Humidity obtained from SAPHIR on board Megha-Tropiques and Ground based Microwave Radiometer Profiler over an equatorial station

    Science.gov (United States)

    Renju, Ramachandran Pillai; Uma, K. N.; Krishna Moorthy, K.; Mathew, Nizy; Raju C, Suresh

    A comparison has been made between the SAPHIR on board Megha-Tropiques (MT) derived Relative Humidity (RH (%)) with that derived from a ground based multi-frequency Microwave Radiometer Profiler (MRP) observations over an equatorial station Thiruvananthapuram (8.5(°) N and 76.9(°) E) for a one year period. As a first step, the validation of MRP has been made against the radiosonde for two years (2010 and 2011) during the Indian monsoon period July-September. This analysis shows a wet bias below 6 km and dry bias above. The comparison between the MRP and the MT derived RH has been made at five different altitudinal levels (0.75, 2.25, 4.0, 6.25 and 9.2 km range) strictly under clear sky condition. The regression analysis between the two reveals very good correlation (>0.8) in the altitudinal layer of 2.25 to 6.25 km. The differences between the two observations had also been explained interms of percentage of occurrence between MT and the MRP at each altitudinal layer. About 70-80% of the time, the difference in the RH is found to below 10% at first three layer. The RMSE of 2% is observed at almost all the height layers. The differences have been attributed to the different measurement and retrieval techniques involved in the ground based and satellite based measurements. Since MRP frequecy channels are not sensitive to small water vapor variabilities above 6 km, large differences are observed. Radiative Transfer computation for the channels of both MRP and SAPHIR will be carried out to understand the variabilities.

  2. Ice hydrometeor profile retrieval algorithm for high frequency microwave radiometers: application to the CoSSIR instrument during TC4

    Directory of Open Access Journals (Sweden)

    K. F. Evans

    2012-04-01

    Full Text Available A Bayesian algorithm to retrieve profiles of cloud ice water content (IWC, ice particle size (Dme, and relative humidity from millimeter-wave/submillimeter-wave radiometers is presented. The first part of the algorithm prepares an a priori file with cumulative distribution functions (CDFs and empirical orthogonal functions (EOFs of profiles of temperature, relative humidity, three ice particle parameters (IWC, Dme, distribution width, and two liquid cloud parameters. The a priori CDFs and EOFs are derived from CloudSat radar reflectivity profiles and associated ECMWF temperature and relative humidity profiles combined with three cloud microphysical probability distributions obtained from in situ cloud probes. The second part of the algorithm uses the CDF/EOF file to perform a Bayesian retrieval with a hybrid technique that uses Monte Carlo integration (MCI or, when too few MCI cases match the observations, uses optimization to maximize the posterior probability function. The very computationally intensive Markov chain Monte Carlo (MCMC method also may be chosen as a solution method. The radiative transfer model assumes mixtures of several shapes of randomly oriented ice particles, and here random aggregates of hexagonal plates, spheres, and dendrites are used for tropical convection. A new physical model of stochastic dendritic snowflake aggregation is developed. The retrieval algorithm is applied to data from the Compact Scanning Submillimeter-wave Imaging Radiometer (CoSSIR flown on the ER-2 aircraft during the Tropical Composition, Cloud and Climate Coupling (TC4 experiment in 2007. Example retrievals with error bars are shown for nadir profiles of IWC, Dme, and relative humidity, and nadir and conical scan swath retrievals of ice water path and average Dme. The ice cloud retrievals are evaluated by retrieving integrated 94 GHz backscattering from CoSSIR for comparison

  3. Ice hydrometeor profile retrieval algorithm for high frequency microwave radiometers: application to the CoSSIR instrument during TC4

    Science.gov (United States)

    Evans, K. F.; Wang, J. R.; O'C Starr, D.; Heymsfield, G.; Li, L.; Tian, L.; Lawson, R. P.; Heymsfield, A. J.; Bansemer, A.

    2012-04-01

    A Bayesian algorithm to retrieve profiles of cloud ice water content (IWC), ice particle size (Dme), and relative humidity from millimeter-wave/submillimeter-wave radiometers is presented. The first part of the algorithm prepares an a priori file with cumulative distribution functions (CDFs) and empirical orthogonal functions (EOFs) of profiles of temperature, relative humidity, three ice particle parameters (IWC, Dme, distribution width), and two liquid cloud parameters. The a priori CDFs and EOFs are derived from CloudSat radar reflectivity profiles and associated ECMWF temperature and relative humidity profiles combined with three cloud microphysical probability distributions obtained from in situ cloud probes. The second part of the algorithm uses the CDF/EOF file to perform a Bayesian retrieval with a hybrid technique that uses Monte Carlo integration (MCI) or, when too few MCI cases match the observations, uses optimization to maximize the posterior probability function. The very computationally intensive Markov chain Monte Carlo (MCMC) method also may be chosen as a solution method. The radiative transfer model assumes mixtures of several shapes of randomly oriented ice particles, and here random aggregates of hexagonal plates, spheres, and dendrites are used for tropical convection. A new physical model of stochastic dendritic snowflake aggregation is developed. The retrieval algorithm is applied to data from the Compact Scanning Submillimeter-wave Imaging Radiometer (CoSSIR) flown on the ER-2 aircraft during the Tropical Composition, Cloud and Climate Coupling (TC4) experiment in 2007. Example retrievals with error bars are shown for nadir profiles of IWC, Dme, and relative humidity, and nadir and conical scan swath retrievals of ice water path and average Dme. The ice cloud retrievals are evaluated by retrieving integrated 94 GHz backscattering from CoSSIR for comparison with the Cloud Radar System (CRS) flown on the same aircraft. The rms difference in

  4. Column Water Vapour using a PFR Radiometer at a High-Alpine Site

    Science.gov (United States)

    Nyeki, S.; Vuilleumier, L.; Heimo, A.; Kämpfer, N.; Mätzler, C.; Vernez, A.; Viatte, P.

    2003-04-01

    The Swiss Atmospheric Radiation Monitoring program (CHARM) integrates a number of solar and atmospheric radiation monitoring tasks within the Swiss contribution to GAW (Global Atmosphere Watch) of the WMO. Columnar water vapor (CWV) is derived from sun photometers at four locations within the CHARM network. A four-year dataset of CWV measured at the Jungfraujoch high-alpine research station (3580 m asl, Switzerland) using a Precision Filter Radiometer (PFR) is reported. Observations indicated that CWV above station altitude varied between 1 and 4 (+/- 1) kg.m-2 in winter and summer, respectively, confirming an earlier 12-month study in 1999.

  5. Identification of atmospheric fronts over the ocean with microwave measurements of water vapor and rain

    Science.gov (United States)

    Katsaros, Kristina B.; Bhatti, Iftekhar; Mcmurdie, Lynn A.; Patty, Grant W.

    1989-01-01

    This paper describes some basic research techniques and algorithms developed to diagnose fronts in cyclonic storms over the ocean with data from satellite-borne microwave radiometers. Methods are developed for flagging strong gradients in integrated atmospheric water vapor and the presence of rain by using data from the SSMR on board the polar orbiting Seasat and Nimbus-7 satellites. Examination of 65 frontal systems showed that the water vapor gradient flag correctly identified 86 percent of the fronts, while the precipitation flagged 91 percent. The two types of flags emphasize different portions of the cyclone and are therefore complementary. Ultimately, these techniques are intended for operational use with data from the Special Sensor Microwave Imager which was launched in June 1987 on a satellite in the Defense Meteorological Satellite Program (DMSP).

  6. Microwave Powered Gravitationally Independent Medical Grade Water Generation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — An innovative microwave system is proposed for the continuous production of medical grade water. This system will utilize direct absorption of microwave radiation to...

  7. A microwave satellite water vapour column retrieval for polar winter conditions

    Science.gov (United States)

    Perro, Christopher; Lesins, Glen; Duck, Thomas J.; Cadeddu, Maria

    2016-05-01

    A new microwave satellite water vapour retrieval for the polar winter atmosphere is presented. The retrieval builds on the work of Miao et al. (2001) and Melsheimer and Heygster (2008), employing auxiliary information for atmospheric conditions and numerical optimization. It was tested using simulated and actual measurements from the Microwave Humidity Sounder (MHS) satellite instruments. Ground truth was provided by the G-band vapour radiometer (GVR) at Barrow, Alaska. For water vapour columns less than 6 kg m-2, comparisons between the retrieval and GVR result in a root mean square (RMS) deviation of 0.39 kg m-2 and a systematic bias of 0.08 kg m-2. These results are compared with RMS deviations and biases at Barrow for the retrieval of Melsheimer and Heygster (2008), the AIRS and MIRS satellite data products, and the ERA-Interim, NCEP, JRA-55, and ASR reanalyses. When applied to MHS measurements, the new retrieval produces a smaller RMS deviation and bias than for the earlier retrieval and satellite data products. The RMS deviations for the new retrieval were comparable to those for the ERA-Interim, JRA-55, and ASR reanalyses; however, the MHS retrievals have much finer horizontal resolution (15 km at nadir) and reveal more structure. The new retrieval can be used to obtain pan-Arctic maps of water vapour columns of unprecedented quality. It may also be applied to measurements from the Special Sensor Microwave/Temperature 2 (SSM/T2), Advanced Microwave Sounding Unit B (AMSU-B), Special Sensor Microwave Imager/Sounder (SSMIS), Advanced Technology Microwave Sounder (ATMS), and Chinese MicroWave Humidity Sounder (MWHS) instruments.

  8. TEMPEST-D MM-Wave Radiometer

    Science.gov (United States)

    Padmanabhan, S.; Gaier, T.; Reising, S. C.; Lim, B.; Stachnik, R. A.; Jarnot, R.; Berg, W. K.; Kummerow, C. D.; Chandrasekar, V.

    2016-12-01

    The TEMPEST-D radiometer is a five-frequency millimeter-wave radiometer at 89, 165, 176, 180, and 182 GHz. The direct-detection architecture of the radiometer reduces its power consumption and eliminates the need for a local oscillator, reducing complexity. The Instrument includes a blackbody calibrator and a scanning reflector, which enable precision calibration and cross-track scanning. The MMIC-based millimeter-wave radiometers take advantage of the technology developed under extensive investment by the NASA Earth Science Technology Office (ESTO). The five-frequency millimeter-wave radiometer is built by Jet Propulsion Laboratory (JPL), which has produced a number of state-of-the-art spaceborne microwave radiometers, such as the Microwave Limb Sounder (MLS), Advanced Microwave Radiometer (AMR) for Jason-2/OSTM, Jason-3, and the Juno Microwave Radiometer (MWR). The TEMPEST-D Instrument design is based on a 165 to 182 GHz radiometer design inherited from RACE and an 89 GHz receiver developed under the ESTO ACT-08 and IIP-10 programs at Colorado State University (CSU) and JPL. The TEMPEST reflector scan and calibration methodology is adapted from the Advanced Technology Microwave Sounder (ATMS) and has been validated on the Global Hawk unmanned aerial vehicle (UAV) using the High Altitude MMIC Sounding radiometer (HAMSR) instrument. This presentation will focus on the design, development and performance of the TEMPEST-D radiometer instrument. The flow-down of the TEMPEST-D mission objectives to instrument level requirements will also be discussed.

  9. Observations of middle atmospheric H2O and O3 during the 2010 major sudden stratospheric warming by a network of microwave radiometers

    Directory of Open Access Journals (Sweden)

    N. Kämpfer

    2012-08-01

    Full Text Available In this study, we present middle atmospheric water vapor (H2O and ozone (O3 measurements obtained by ground-based microwave radiometers at three European locations in Bern (47° N, Onsala (57° N and Sodankylä (67° N during Northern winter 2009/2010. In January 2010, a major sudden stratospheric warming (SSW occurred in the Northern Hemisphere whose signatures are evident in the ground-based observations of H2O and O3. The observed anomalies in H2O and O3 are mostly explained by the relative location of the polar vortex with respect to the measurement locations. The SSW started on 26 January 2010 and was most pronounced by the end of January. The zonal mean temperature in the middle stratosphere (10 hPa increased by approximately 25 Kelvin within a few days. The stratospheric vortex weakened during the SSW and shifted towards Europe. In the mesosphere, the vortex broke down, which lead to large scale mixing of polar and midlatitudinal air. After the warming, the polar vortex in the stratosphere split into two weaker vortices and in the mesosphere, a new, pole-centered vortex formed with maximum wind speed of 70 m s−1 at approximately 40° N. The shift of the stratospheric vortex towards Europe was observed in Bern as an increase in stratospheric H2O and a decrease in O3. The breakdown of the mesospheric vortex during the SSW was observed at Onsala and Sodankylä as a sudden increase in mesospheric H2O. The following large-scale descent inside the newly formed mesospheric vortex was well captured by the H2O observations in Sodankylä. In order to combine the H2O observations from the three different locations, we applied the trajectory mapping technique on our H2O observations to derive synoptic scale maps of the H2O distribution. Based on our observations and the 3-D wind field, this method allows determining the approximate development of the stratospheric and mesospheric polar vortex and demonstrates the potential of a network of ground

  10. Estimation of Areal Soil Water Content through Microwave Remote Sensing

    NARCIS (Netherlands)

    Oevelen, van P.J.

    2000-01-01

    In this thesis the use of microwave remote sensing to estimate soil water content is investigated. A general framework is described which is applicable to both passive and active microwave remote sensing of soil water content. The various steps necessary to estimate areal soil water content are disc

  11. Application of Microwave Radiometer Data in the Fog Forecasting and Early Warning%微波辐射计资料在大雾预报预警中的应用

    Institute of Scientific and Technical Information of China (English)

    赵金霞; 范苏丹; 朱晓晶

    2015-01-01

    利用MP-3000A微波辐射计对2011—2013年天津大雾的观测资料,选取16次大雾典型个例,分析大雾发生、维持及消散时微波辐射计观测数据。分析表明:大雾从形成到消散过程中水汽密度、相对湿度和位温均有不同变化;大雾发生前近地层大气中的相对湿度、水汽密度一般会稳定增加,大雾发生时两者会有爆发性增加的现象。大雾维持阶段在近地层多伴有逆温层,辐射雾逆温层明显;大雾期间雾层高度有稳定型也有波动型,雾层高度下降时大雾会迅速加强。大雾消散时近地层大湿区减小抬升,水汽密度迅速减小。%MP- 3000A is a new atmospheric sounding instrument, which can be obtained continuously from the ground to the height of 10 km of high-resolution digital temperature, relative humidity, The water vapor density profile. Select fog occurs, upkeep and dissipate microwave radiometer observations, Analysis found that process from the formation of fog to dissipate, The evolution of the fog of water vapor density, relative humidity and potential temperature are different variations; Front fog occurs near surface atmospheric relative humidity, water vapor density is generally a steady increase, Fog occurs when They will increase explosively. There is inversion layer in near surface layer, radiation fog obvious, maintenance phase in the fog. Fog layer of highly there are stable and fluctuating in during fog, Fog will quickly strengthen the fog layer height when dropped. When the fog dissipates a large wet area near surface layer reduction and uplift,The water vapor density decreases rapidly. Therefore, the microwave radiometer water vapor density, liquid water content and potential temperature studies, will help improve the generation and dissipation of fog forecasting and early warning.

  12. Assessing Scale Effects on Snow Water Equivalent Retrievals Using Airborne and Spaceborne Passive Microwave Data

    Science.gov (United States)

    Derksen, C.; Walker, A.; Goodison, B.

    2003-12-01

    The Climate Research Branch (CRB) of the Meteorological Service of Canada (MSC) has a long-standing research program focused on the development of methods to retrieve snow cover information from passive microwave satellite data for Canadian regions. Algorithms that derive snow water equivalent (SWE) have been developed by CRB and are used to operationally generate SWE information over landscape regions including prairie, boreal forest, and taiga. New multi-scale research datasets were acquired in Saskatchewan, Canada during February 2003 to quantify the impact of spatially heterogeneous land cover and snowpack properties on passive microwave SWE retrievals. MSC microwave radiometers (6.9, 19, 37, and 85 GHz) were flown on the National Research Council (NRC) Twin Otter aircraft at two flying heights along a grid of flight lines, covering a 25 by 25 km study area centered on the Old Jack Pine Boreal Ecosystem Research and Monitoring Site (BERMS). Spaceborne Special Sensor Microwave/Imager (SSM/I) and Advanced Microwave Scanning Radiometer (AMSR-E) brightness temperatures were also acquired for this region. SWE was derived for all passive microwave datasets using the CRB land cover sensitive algorithm suite. An intensive, coincident ground sampling program characterized in situ snow depth, density, water equivalent and pack structure using a land cover based sampling scheme to isolate the variability in snow cover parameters within and between forest stands and land cover types, and within a single spaceborne passive microwave grid cell. The passive microwave data sets that are the focus of this investigation cover a range of spatial resolutions from 100-150 m for the airborne data to 10 km (AMSR-E) and 25 km (SSM/I) for the satellite data, providing the opportunity to investigate and compare microwave emission characteristics, SWE retrievals and land cover effects at different spatial scales. Initial analysis shows that the small footprint airborne passive microwave

  13. Retrieval of columnar water vapor using multispectral radiometer measurements over northern China

    Science.gov (United States)

    Liu, Chaoshun; Li, Yun; Gao, Wei; Shi, Runhe; Bai, Kaixu

    2011-01-01

    Water vapor is an important component in hydrological processes that basically involve all types of seasons, including dry (e.g., drought) or wet (e.g., hurricane or monsoon). This study retrieved columnar water vapor (CWV) with the 939.3 nm band of a multifilter rotating shadowband radiometer (MFRSR) using the modified Langley technique. Such an investigation was in concert with the use of the atmospheric transmission model MODTRAN for determining the instrument coefficients required for CWV estimation. Results of the retrieval of CWV by MFRSR from September 23, 2004 to June 20, 2005 at the XiangHe site are presented and analyzed in this paper. To improve the credibility, the MFRSR results were compared with those obtained from the AErosol RObotic NETwork CIMEL sun-photometer measurements, co-located at the XiangHe site, and the moderate resolution imaging spectroradiometer (MODIS) near-infrared total precipitable water product (MOD05), respectively. These comparisons show good agreement in terms of correlation coefficients, slopes, and offsets, revealing that the accuracy of CWV estimation using the MFRSR instrument is reliable and suitable for extended studies in northern China.

  14. Modeling of tropospheric integrated water vapor content using GPS, radiosonde, radiometer, rain gauge, and surface meteorological data in a tropical region (French Polynesia)

    Science.gov (United States)

    Serafini, Jonathan; Barriot, Jean-Pierre; Hopuare, Marania; Sichoix, Lydie; Fadil, Abdelali

    2012-11-01

    The integrated precipitable water vapor (IPW) is characterized by strong spatial and temporal variability, especially over tropical regions where the troposhere is not purely in hydrostatic equilibrium (convection). As an evidence, the survey of water vapor distibution as permanently as possible is an important issue and should serve as inputs for tropical climate modelling. In this paper, we present an estimation of the IPV from ground­ ba,.sed GPS receivers, which we compare to radiosondes and microwave radiometer. The data used here were collected in the vicinity of French Polynesia University site, during eight years from 2001 to 2008. In addition, we also include the IPW calculated using Era-Interim reanalyses (ECMWF). The main purpose of this paper is to highlight precision, qualities and limitations of each method available on the Island of Tahiti. During wet periods, the radiosondes vertical profiles of water vapor show an efficient mixing of water vapor between the the boundary layer (below trade winds inversion at Tahiti) and the free troposphere. Thus the rainy event detection allows to better constrain the validity range of a model of the vertical distribution of water vapor, which is based on a pseudo-adiabatic saturated evolution of the temperature.

  15. Solar-Collector Radiometer

    Science.gov (United States)

    Kendall, J. M., Jr

    1984-01-01

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

  16. Solutions Network Formulation Report. Visible/Infrared Imager/Radiometer Suite and Advanced Microwave Scanning Radiometer Data Products for National Drought Monitor Decision Support

    Science.gov (United States)

    Estep, Leland

    2007-01-01

    Drought effects are either direct or indirect depending on location, population, and regional economic vitality. Common direct effects of drought are reduced crop, rangeland, and forest productivity; increased fire hazard; reduced water levels; increased livestock and wildlife mortality rates; and damage to wildlife and fish habitat. Indirect impacts follow on the heels of direct impacts. For example, a reduction in crop, rangeland, and forest productivity may result in reduced income for farmers and agribusiness, increased prices for food and timber, unemployment, reduced tax revenues, increased crime, foreclosures on bank loans to farmers and businesses, migration, and disaster relief programs. In the United States alone, drought is estimated to result in annual losses of between $6 - 8 billion. Recent sustained drought in the United States has made decision-makers aware of the impacts of climate change on society and environment. The eight major droughts that occurred in the United States between 1980 and 1999 accounted for the largest percentage of weather-related monetary losses. Monitoring drought and its impact that occurs at a variety of scales is an important government activity -- not only nationally but internationally as well. The NDMC (National Drought Mitigation Center) and the USDA (U.S. Department of Agriculture) RMA (Risk Management Agency) have partnered together to develop a DM-DSS (Drought Monitoring Decision Support System). This monitoring system will be an interactive portal that will provide users the ability to visualize and assess drought at all levels. This candidate solution incorporates atmospherically corrected VIIRS data products, such as NDVI (Normalized Difference Vegetation Index) and Ocean SST (sea surface temperature), and AMSR-E soil moisture data products into two NDMC vegetation indices -- VegDRI (Vegetation Drought Response Index) and VegOUT (Vegetation Outlook) -- which are then input into the DM-DSS.

  17. Application of a coupled microwave, energy and water transfer model to relate passive microwave emission from bare soils to near-surface water content and evaporation

    Directory of Open Access Journals (Sweden)

    L. P. Simmonds

    1999-01-01

    Full Text Available The paper examines the stability of the relation between microwave emission from the soil and the average near-surface water content in the case of relatively smooth, bare soils, and then considers the extent to which microwave radiometry can be used to estimate the effective surface resistance to vapour transfer, which is also related to the near-surface water status. The analysis is based on the use of a model (MICRO-SWEAT which couples a microwave radiative transfer model with a SVAT scheme that describes the exchanges of water vapour, energy and sensible heat at the land surface. Verification of MICRO-SWEAT showed good agreement (about 3K RMSE between predicted L band (1.4 GHz brightness temperature over soils with contrasting texture during a multi-day drydown, and those measured using a truck-mounted radiometer. There was good agreement between the measured and predicted relations between the average water content of the upper 2 cm of the soil profile and the brightness temperature normalised with respect to the radiometric surface temperature. Some of the scatter in this relationship was attributable to diurnal variation in the magnitude of near-surface gradients in temperature and water content, and could be accounted for by using the physically-based simulation model. The influence of soil texture on this relationship was well-simulated using MICRO-SWEAT. The paper concludes by demonstrating how MICRO-SWEAT can be used to establish a relationship between the normalised brightness temperature and the surface resistance for use in the prediction of evaporation using the Penman-Montheith equation.

  18. An upward looking airborne millimeter wave radiometer for atmospheric water vapor sounding and rain detection

    Science.gov (United States)

    Gagliano, J. A.; Platt, R. H.

    1985-01-01

    A 90/180 GHz multichannel radiometer is currently under development for NASA's 1985 Hurricane Mission onboard the Convair 990 research aircraft. The radiometer will be a fixed beam instrument with dual corrugated horns and a common lens antenna designed to operate simultaneously at 90 and 180 GHz. The all solid state front-end will contain three double side band data channels at 90 + or - 3 GHz, 180 + or - 3 GHz, and 180 + or - 7 GHz. The airborne radiometer will mount in a window port on the CV-990 and will maintain a fixed beam view approximately 14 degrees off zenith. The radiometer design is a Dicke chopper arrangement selected to achieve maximum absolute temperature accuracy and minimum brightness temperature sensitivity. Analog outputs of the three data channels will be calibrated dc voltages representing the observed radiometric brightness temperatures over the selected integration time.

  19. Microwave emissivity of fresh water ice--Lake ice and Antarctic ice pack--Radiative transfer simulations versus satellite radiances

    CERN Document Server

    Mills, Peter

    2012-01-01

    Microwave emissivity models of sea ice are poorly validated empirically. Typical validation studies involve using averaged or stereotyped profiles of ice parameters against averaged radiance measurements. Measurement sites are rarely matched and even less often point-by-point. Because of saline content, complex permittivity of sea ice is highly variable and difficult to predict. Therefore, to check the validity of a typical, plane-parallel, radiative-transfer-based ice emissivity model, we apply it to fresh water ice instead of salt-water ice. Radiance simulations for lake ice are compared with measurements over Lake Superior from the Advanced Microwave Scanning Radiometer on EOS (AMSR-E). AMSR-E measurements are also collected over Antarctic icepack. For each pixel, a thermodynamic model is driven by four years of European Center for Medium Range Weather Forecasts (ECMWF) reanalysis data and the resulting temperature profiles used to drive the emissivity model. The results suggest that the relatively simple ...

  20. Comparison and evaluation of the Chang'E microwave radiometer data based on theoretical computation of brightness temperatures at the Apollo 15 and 17 sites

    Science.gov (United States)

    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.

  1. Inversions of subsurface temperature and thermal diffusivity on the Moon based on high frequency of Chang'E-1 microwave radiometer data

    Science.gov (United States)

    Wei, Guangfei; Li, Xiongyao; Wang, Shijie

    2016-09-01

    Thermal behavior of regolith reflects its thermophysical properties directly on the Moon. In this study, we employed the Fourier temperature model and inverted mean subsurface temperature and thermal diffusivity from high frequency of Chang'E-1 microwave radiometer data. The result showed that the mafic lunar mare endured higher thermal regime than that of feldspathic highland in a lunar cycle. As expected, the highland diffusivity with mean value 2.5 × 10-4 cm2/s is greater than the mean value 0.3 × 10-4 cm2/s of lunar mare. It indicated that the highland material responded more quickly than that of lunar mare to the changes of surface temperature in a diurnal day. In addition, thermal anomalous regions and hot/cold spots were also identified by diffusivity. For the thermal anomalous regions, Mare Tranquillitatis for example, with more contents of (FeO+TiO2), agglutinate and high maturity index corresponded to greater diffusivity (∼1.0 × 10-4 cm2/s) and is more sensitive to the variations of temperature than the neighboring Mare Serenitatis (∼0.3 × 10-4 cm2/s). Thus, inversion and comparison of regolith thermophysical properties can reveal more information of geological evolution on the Moon.

  2. Quality assessment of ground-based microwave measurements of chlorine monoxide, ozone, and nitrogen dioxide from the NDSC radiometer at the plateau de bure

    Energy Technology Data Exchange (ETDEWEB)

    Ricaud, P.; Noe, J. de la [Observatoire Aquitain des Sciences de l' Univers (OASU), Lab. d' Astrodynamique, d' Astrophysique et d' Aeronomie de Bordeaux, Floirac (France); Baron, P. [Noveltis, Toulouse (France)

    2004-07-01

    A ground-based microwave radiometer dedicated to chlorine monoxide (ClO) measurements around 278 GHz has been in operation from December 1993-June 1996 at the Plateau de Bure, France (45 N, 5.9 E, 2500 m altitude). It belongs to the international network for the detection of stratospheric change. A detailed study of both measurements and retrieval schemes has been undertaken. Although dedicated to the measurements of ClO, simultaneous profiles of O{sub 3}, ClO and NO{sub 2}, together with information about the instrumental baseline, have been retrieved using the optimal estimation method. The vertical profiles have been compared with other ground-based microwave data, satellite-borne data and model results. Data quality shows: 1) the weak sensitivity of the instrument that obliges to make time averages over several hours; 2) the site location where measurements of good opacities are possible for only a few days per year; 3) the baseline undulation affecting all the spectra, an issue common to all the microwave instruments; 4) the slow drift of some components affecting frequencies by 3-4 MHz within a couple of months. Nevertheless, when temporally averaging data over a few days, ClO temporal variations (diurnal and over several weeks in winter 1995) from 35-50 km are consistent with model results and satellite data, particularly at the peak altitude around 40 km, although temporal coincidences are infrequent in winter 1995. In addition to ClO, it is possible to obtain O{sub 3} information from 30-60 km whilst the instrument is not optimized at all for this molecule. Retrievals of O{sub 3} are reasonable when compared with model and another ground-based data set, although the lowermost layers are affected by the contamination of baseline remnants. Monthly-averaged diurnal variations of NO{sub 2} are detected at 40 km and appear in agreement with photochemical model results and satellite zonally-averaged data, although the amplitude is weaker than the other data sets

  3. Quality assessment of ground-based microwave measurements of chlorine monoxide, ozone, and nitrogen dioxide from the NDSC radiometer at the Plateau de Bure

    Directory of Open Access Journals (Sweden)

    P. Ricaud

    2004-06-01

    Full Text Available A ground-based microwave radiometer dedicated to chlorine monoxide (ClO measurements around 278GHz has been in operation from December 1993-June 1996 at the Plateau de Bure, France (45° N, 5.9° E, 2500m altitude. It belongs to the international Network for the Detection of Stratospheric Change. A detailed study of both measurements and retrieval schemes has been undertaken. Although dedicated to the measurements of ClO, simultaneous profiles of O3, ClO and NO2, together with information about the instrumental baseline, have been retrieved using the optimal estimation method. The vertical profiles have been compared with other ground-based microwave data, satellite-borne data and model results. Data quality shows: 1 the weak sensitivity of the instrument that obliges to make time averages over several hours; 2 the site location where measurements of good opacities are possible for only a few days per year; 3 the baseline undulation affecting all the spectra, an issue common to all the microwave instruments; 4 the slow drift of some components affecting frequencies by 3-4MHz within a couple of months. Nevertheless, when temporally averaging data over a few days, ClO temporal variations (diurnal and over several weeks in winter 1995 from 35-50km are consistent with model results and satellite data, particularly at the peak altitude around 40km, although temporal coincidences are infrequent in winter 1995. In addition to ClO, it is possible to obtain O3 information from 30-60km whilst the instrument is not optimized at all for this molecule. Retrievals of O3 are reasonable when compared with model and another ground-based data set, although the lowermost layers are affected by the contamination of baseline remnants. Monthly-averaged diurnal variations of NO2 are detected at 40km and appear in agreement with photochemical model results and satellite zonally-averaged data, although the amplitude

  4. Mathematical models for Enterococcus faecalis recovery after microwave water disinfection.

    Science.gov (United States)

    Benjamin, Earl; Reznik, Aron; Benjamin, Ellis; Pramanik, Saroj K; Sowers, Louise; Williams, Arthur L

    2009-12-01

    Microwave water disinfection is a rapid purification technique which can give billions of people access to clean drinking water. However, better understanding of bacterial recovery after microwave heating over time is necessary to determine parameters such as delayed bacterial growth rates and maximum bacterial yields. Mathematical models for Enterococcus faecalis recovery after microwave treatment in optimum growth conditions were developed for times up to 5 minutes using an optical absorbance method. Microwave times below 3 minutes (2,450 MHz, 130W) showed that bacterial recovery maintained a time-dependent sigmoidal form which included a maximum value. At microwave times greater than three minutes, bacterial recovery, with a time-dependent exponential form, significantly decreased and did not reach the maximum value within the interval of observance (0-8 hours). No bacterial growth was found after 6 minutes of microwave treatment. The prepared mathematical models were produced by transforming the given variables to the logistic or exponential functions. We found that time-dependent maximum growth rates and lag times could be approximated with second order polynomial functions. The determined models can be used as a template to illustrate bacterial survival during water purification using microwave irradiation, in both commercial and industrial processes.

  5. Comparing the Accuracy of AMSRE, AMSR2, SSMI and SSMIS Satellite Radiometer Ice Concentration Products with One-Meter Resolution Visible Imagery in the Arctic

    Science.gov (United States)

    Peterson, E. R.; Stanton, T. P.

    2016-12-01

    Determining ice concentration in the Arctic is necessary to track significant changes in sea ice edge extent. Sea ice concentrations are also needed to interpret data collected by in-situ instruments like buoys, as the amount of ice versus water in a given area determines local solar heating. Ice concentration products are now routinely derived from satellite radiometers including the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E), the Advanced Microwave Scanning Radiometer 2 (AMSR2), the Special Sensor Microwave Imager (SSMI), and the Special Sensor Microwave Imager/Sounder (SSMIS). While these radiometers are viewed as reliable to monitor long-term changes in sea ice extent, their accuracy should be analyzed, and compared to determine which radiometer performs best over smaller features such as melt ponds, and how seasonal conditions affect accuracy. Knowledge of the accuracy of radiometers at high resolution can help future researchers determine which radiometer to use, and be aware of radiometer shortcomings in different ice conditions. This will be especially useful when interpreting data from in-situ instruments which deal with small scale measurements. In order to compare these passive microwave radiometers, selected high spatial resolution one-meter resolution Medea images, archived at the Unites States Geological Survey, are used for ground truth comparison. Sea ice concentrations are derived from these images in an interactive process, although estimates are not perfect ground truth due to exposure of images, shadowing and cloud cover. 68 images are retrieved from the USGS website and compared with 9 useable, collocated SSMI, 33 SSMIS, 36 AMSRE, and 14 AMSR2 ice concentrations in the Arctic Ocean. We analyze and compare the accuracy of radiometer instrumentation in differing ice conditions.

  6. Hurricane Imaging Radiometer

    Science.gov (United States)

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

    2014-01-01

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

  7. Microwave Extraction of Lunar Water for Rocket Fuel

    Science.gov (United States)

    Ethridge, Edwin C.; Donahue, Benjamin; Kaukler, William

    2008-01-01

    Nearly 50% of the lunar surface is oxygen, present as oxides in silicate rocks and soil. Methods for reduction of these oxides could liberate the oxygen. Remote sensing has provided evidence of significant quantities of hydrogen possibly indicating hundreds of millions of metric tons, MT, of water at the lunar poles. If the presence of lunar water is verified, water is likely to be the first in situ resource exploited for human exploration and for LOX-H2 rocket fuel. In-Situ lunar resources offer unique advantages for space operations. Each unit of product produced on the lunar surface represents 6 units that need not to be launched into LEO. Previous studies have indicated the economic advantage of LOX for space tugs from LEO to GEO. Use of lunar derived LOX in a reusable lunar lander would greatly reduce the LEO mass required for a given payload to the moon. And Lunar LOX transported to L2 has unique advantages for a Mars mission. Several methods exist for extraction of oxygen from the soil. But, extraction of lunar water has several significant advantages. Microwave heating of lunar permafrost has additional important advantages for water extraction. Microwaves penetrate and heat from within not just at the surface and excavation is not required. Proof of concept experiments using a moon in a bottle concept have demonstrated that microwave processing of cryogenic lunar permafrost simulant in a vacuum rapidly and efficiently extracts water by sublimation. A prototype lunar water extraction rover was built and tested for heating of simulant. Microwave power was very efficiently delivered into a simulated lunar soil. Microwave dielectric properties (complex electric permittivity and magnetic permeability) of lunar regolith simulant, JSC-1A, were measured down to cryogenic temperatures and above room temperature. The microwave penetration has been correlated with the measured dielectric properties. Since the microwave penetration depth is a function of temperature

  8. Cross-correlation between the 170 GHz survey map and the COBE differential microwave radiometer first-year maps

    Science.gov (United States)

    Ganga, Ken; Cheng, ED; Meyer, Stephan; Page, Lyman

    1993-01-01

    This letter describes results of a cross-correlation between the 170 GHz partial-sky survey, made with a 3.8 deg beam balloon-borne instrument, and the COBE DMR 'Fit Technique' reduced galaxy all-sky map with a beam of 7 deg. The strong correlation between the data sets implies that the observed structure is consistent with thermal variations in a 2.7 K emitter. A chi-square analysis applied to the correlation function rules out the assumption that there is no structure in either of the two maps. A second test shows that if the DMR map has structure but the 170 GHz map does not, the probability of obtaining the observed correlation is small. Further analyses support the assumption that both maps have structure and that the 170 GHz-DMR cross-correlation is consistent with the analogous DMR correlation function. Maps containing various combinations of noise and Harrison-Zel'dovich power spectra are simulated and correlated to reinforce the result. The correlation provides compelling evidence that both instruments have observed fluctuations consistent with anisotropies in the cosmic microwave background.

  9. Deriving Sea Surface Salinity and Density Variations from Satellite and Aircraft Microwave Radiometer Measurements: Application to Coastal Plumes Using STARRS

    Science.gov (United States)

    2007-11-01

    vertical shear of the geostrophic velocity dVI /dz time and position, and aircraft attitude, respectively. For typ- prove to be acceptable, density...algorithm with corrections for the effects of the intervening water va- dD/dx=(OD) ( + (OD ((S 5 por obtained from estimates of precipitable water vapor

  10. Microwave assisted synthesis of 6-Substituted aminopurine analogs in water

    OpenAIRE

    Qu, Guirong; Han,Suhui; Zhang,Zhiguang; Geng,Mingwei; Xue, Feng

    2006-01-01

    Microwave assisted amination of 6-chloropurine derivatives with various amines in water resulted in a "green chemistry" protocol for the preparation of 6-substituted aminopurine analogs in very good yields. Using a simply modified microwave oven with the refluxing apparatus, the amination of the 6-chloro in the purine structure occurred smoothly. 19 known and 16 unknown 6-substituted aminopurine analogs were prepared through nucleophilic aromatic substitution with simple filtration or column ...

  11. Microwave-Based Water Decontamination System

    Science.gov (United States)

    Arndt, G. Dickey (Inventor); Byerly, Diane (Inventor); Sognier, Marguerite (Inventor); Dusl, John (Inventor)

    2016-01-01

    A system for decontaminating a medium. The system can include a medium having one or more contaminants disposed therein. The contaminants can be or include bacteria, fungi, parasites, viruses, and combinations thereof. A microwave energy radiation device can be positioned proximate the medium. The microwave energy radiation device can be adapted to generate a signal having a frequency from about 10 GHz to about 100 GHz. The signal can be adapted to kill one or more of the contaminants disposed within the medium while increasing a temperature of the medium by less than about 10 C.

  12. The conical scan radiometer

    Science.gov (United States)

    Prosch, T.; Hennings, D.

    1982-07-01

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

  13. DMSP SSMT/2 - Atmospheric Water Vapor Profiler

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The SSM/T-2 sensor is a five channel, total power microwave radiometer with three channels situated symmetrically about the 183.31 GHz water vapor resonance line and...

  14. Data Fusion of SST from HY-2A Satellite Radiometer in China Sea and its Adjacent Waters

    Science.gov (United States)

    Li, Xiaohui; Yang, Jingsong; Zheng, Gang; Han, Guoqi; Ren, Lin; Wang, Juan

    2016-08-01

    This paper focuses on using data fusion method to solve the problem that the global sea is not seamlessly covered by the along-track sea surface temperature (SST) data of scanning microwave radiometer on board Haiyang-2A (HY-2A), which is the first ocean dynamic environment satellite of China launched on 16th August 2011. The procedure includes following steps. Firstly, the HY-2A SST data within 200 km of the coastline were identified and removed, the outliers of the HY-2A SST data and the background SST data were also identified and removed. Secondly, the HY-2A SST data were gridded, filtered and corrected. The background SST data were only filtered. Finally, the HY-2A SST data were merged into background SST data by the inverse distance weighted method. Next, the above procedure was tested in the ocean area on the southeast of China. The global 1-km sea surface temperature (G1SST) data were used as the reference data. The results of the procedure with and without the second step were made comparisons, and the results implied that the application of median filter and third-order polynomial curve fitting in the second step could help to improve performance of the merged SST data. The along-track SST data of HY-2A can be merged into OSTIA SST data successfully by the above procedure, and the gaps between tracks were filled up.

  15. Microwaves energy in curing process of water glass molding sands

    Directory of Open Access Journals (Sweden)

    Granat K.

    2007-01-01

    Full Text Available This work presents the results of investigation of microwave heating on hardening process of water glass molding sands. Essential influence of this heating process on basic properties such as: compression, bending and tensile strength as well as permeability and abrasion resistance has been found. It has been proved, that all investigated sorts of sodium water glass with a module between 2.0 and 3.3 can be used as a binder of molding sands in microwave curing process. It has been found during analysis of research results of sands with 2.5 % water glass addition that they are practically the same as in case of identical molding sands dried for 120 minutes at the temperature of 110°C, used for comparative purposes. Application of microwave curing of molding sands with water glass, however, guarantees reduction of hardening time (from 120 to 4 minutes as well as significant reduction of energy consumption. Attempts of two stage hardening of the investigated water glass molding sands have also been carried out, that is after an initial hardening during a classical CO2 process (identical sands have also been tested for comparison after CO2 blowing process and additional microwave heating. It has been found that application of this kind of treatment for curing sands with 2.5 % sodium water glass content and module from 2.0 up to 3.3 results in the improvement of properties in comparison to classical CO2 process.

  16. Ice hydrometeor profile retrieval algorithm for high-frequency microwave radiometers: application to the CoSSIR instrument during TC4

    Science.gov (United States)

    Evans, K. F.; Wang, J. R.; O'C Starr, D.; Heymsfield, G.; Li, L.; Tian, L.; Lawson, R. P.; Heymsfield, A. J.; Bansemer, A.

    2012-09-01

    A Bayesian algorithm to retrieve profiles of cloud ice water content (IWC), ice particle size (Dme), and relative humidity from millimeter-wave/submillimeter-wave radiometers is presented. The first part of the algorithm prepares an a priori file with cumulative distribution functions (CDFs) and empirical orthogonal functions (EOFs) of profiles of temperature, relative humidity, three ice particle parameters (IWC, Dme, distribution width), and two liquid cloud parameters. The a priori CDFs and EOFs are derived from CloudSat radar reflectivity profiles and associated ECMWF temperature and relative humidity profiles combined with three cloud microphysical probability distributions obtained from in situ cloud probes. The second part of the algorithm uses the CDF/EOF file to perform a Bayesian retrieval with a hybrid technique that uses Monte Carlo integration (MCI) or, when too few MCI cases match the observations, uses optimization to maximize the posterior probability function. The very computationally intensive Markov chain Monte Carlo (MCMC) method also may be chosen as a solution method. The radiative transfer model assumes mixtures of several shapes of randomly oriented ice particles, and here random aggregates of spheres, dendrites, and hexagonal plates are used for tropical convection. A new physical model of stochastic dendritic snowflake aggregation is developed. The retrieval algorithm is applied to data from the Compact Scanning Submillimeter-wave Imaging Radiometer (CoSSIR) flown on the ER-2 aircraft during the Tropical Composition, Cloud and Climate Coupling (TC4) experiment in 2007. Example retrievals with error bars are shown for nadir profiles of IWC, Dme, and relative humidity, and nadir and conical scan swath retrievals of ice water path and average Dme. The ice cloud retrievals are evaluated by retrieving integrated 94 GHz backscattering from CoSSIR for comparison with the Cloud Radar System (CRS) flown on the same aircraft. The rms difference in

  17. Ice hydrometeor profile retrieval algorithm for high-frequency microwave radiometers: application to the CoSSIR instrument during TC4

    Directory of Open Access Journals (Sweden)

    K. F. Evans

    2012-09-01

    Full Text Available A Bayesian algorithm to retrieve profiles of cloud ice water content (IWC, ice particle size (Dme, and relative humidity from millimeter-wave/submillimeter-wave radiometers is presented. The first part of the algorithm prepares an a priori file with cumulative distribution functions (CDFs and empirical orthogonal functions (EOFs of profiles of temperature, relative humidity, three ice particle parameters (IWC, Dme, distribution width, and two liquid cloud parameters. The a priori CDFs and EOFs are derived from CloudSat radar reflectivity profiles and associated ECMWF temperature and relative humidity profiles combined with three cloud microphysical probability distributions obtained from in situ cloud probes. The second part of the algorithm uses the CDF/EOF file to perform a Bayesian retrieval with a hybrid technique that uses Monte Carlo integration (MCI or, when too few MCI cases match the observations, uses optimization to maximize the posterior probability function. The very computationally intensive Markov chain Monte Carlo (MCMC method also may be chosen as a solution method. The radiative transfer model assumes mixtures of several shapes of randomly oriented ice particles, and here random aggregates of spheres, dendrites, and hexagonal plates are used for tropical convection. A new physical model of stochastic dendritic snowflake aggregation is developed. The retrieval algorithm is applied to data from the Compact Scanning Submillimeter-wave Imaging Radiometer (CoSSIR flown on the ER-2 aircraft during the Tropical Composition, Cloud and Climate Coupling (TC4 experiment in 2007. Example retrievals with error bars are shown for nadir profiles of IWC, Dme, and relative humidity, and nadir and conical scan swath retrievals of ice water path and average Dme. The ice cloud retrievals are evaluated by retrieving integrated 94 GHz backscattering from CoSSIR for comparison

  18. Risk of Burns from Eruptions of Hot Water Overheated in Microwave Ovens

    Science.gov (United States)

    ... Burns from Eruptions of Hot Water Overheated in Microwave Ovens Share Tweet Linkedin Pin it More sharing options ... after it had been over-heated in a microwave oven. Over-heating of water in a cup can ...

  19. The new Passive microwave Neural network Precipitation Retrieval (PNPR) algorithm for the cross-track scanning ATMS radiometer: description and verification study over Europe and Africa using GPM and TRMM spaceborne radars

    Science.gov (United States)

    Sanò, Paolo; Panegrossi, Giulia; Casella, Daniele; Marra, Anna C.; Di Paola, Francesco; Dietrich, Stefano

    2016-11-01

    The objective of this paper is to describe the development and evaluate the performance of a completely new version of the Passive microwave Neural network Precipitation Retrieval (PNPR v2), an algorithm based on a neural network approach, designed to retrieve the instantaneous surface precipitation rate using the cross-track Advanced Technology Microwave Sounder (ATMS) radiometer measurements. This algorithm, developed within the EUMETSAT H-SAF program, represents an evolution of the previous version (PNPR v1), developed for AMSU/MHS radiometers (and used and distributed operationally within H-SAF), with improvements aimed at exploiting the new precipitation-sensing capabilities of ATMS with respect to AMSU/MHS. In the design of the neural network the new ATMS channels compared to AMSU/MHS, and their combinations, including the brightness temperature differences in the water vapor absorption band, around 183 GHz, are considered. The algorithm is based on a single neural network, for all types of surface background, trained using a large database based on 94 cloud-resolving model simulations over the European and the African areas. The performance of PNPR v2 has been evaluated through an intercomparison of the instantaneous precipitation estimates with co-located estimates from the TRMM Precipitation Radar (TRMM-PR) and from the GPM Core Observatory Ku-band Precipitation Radar (GPM-KuPR). In the comparison with TRMM-PR, over the African area the statistical analysis was carried out for a 2-year (2013-2014) dataset of coincident observations over a regular grid at 0.5° × 0.5° resolution. The results have shown a good agreement between PNPR v2 and TRMM-PR for the different surface types. The correlation coefficient (CC) was equal to 0.69 over ocean and 0.71 over vegetated land (lower values were obtained over arid land and coast), and the root mean squared error (RMSE) was equal to 1.30 mm h-1 over ocean and 1.11 mm h-1 over vegetated land. The results showed a

  20. Validation and statistical analysis of temperature, humidity profiles and Integrated Water Vapor (IWV) from microwave measurements over Granada (Spain)

    Science.gov (United States)

    Bedoya, Andres; Navas-Guzmán, Francisco; Guerrero-Rascado, Juan Luis; Alados-Arboledas, Lucas

    2017-04-01

    Profiles of meteorological variables such as temperature, relative humidity and integrated water vapor derived from a ground-based microwave radiometer (MWR, RPG-HATPRO) are continuously monitored since 2012 at Granada station (Southeastern Spain). During this period up to 210 collocated meteorological balloons, equipped with a radiosonde DFM-09 (GRAWMET), were launched. This study is carried out with a twofold goal. On one hand, a validation of the MWR products such as temperature and water vapor mixing ratio profiles and the IWV from MWR is carried out comparing with radiosonde measurements. The behavior of MWR retrievals under clear and cloudy conditions and for special situations such as inversions has been analyzed. On the other hand, the whole period with continuous measurements is used for a statistical evaluation of the meteorological variables derived from MWR in order to thermodynamically characterize the atmosphere over Granada.

  1. 海洋二号卫星微波辐射计的动平衡设计仿真与试验%Dynamic balancing design simulation and test for HY-2A satellite microwave radiometer

    Institute of Scientific and Technical Information of China (English)

    王朋朋; 牛宝华; 艾永强; 王三民

    2016-01-01

    In order to realize high precision attitude control of a satellite,the dynamic balancing design simulation and test for large rotating payload of microwave radiometer should be conducted.Combining with the research and development of HY-2A satellite,the dynamic balancing design and simulation of its microwave radiometer was performed to provide the basis for its structural optimization and layout design.The effects of air resistant force on the radiometer's dynamic balancing were analyzed.The influences of gravity,thermal expansion and variation of bearing radial clearance on the radiometer's dynamic balancing were also considered.Finally,the radiometer's dynamic balancing test was performed in vacuum environment and its dynamic balance target was achieved with very small added weights.%为了实现卫星的高精度姿态控制,需要对以辐射计为代表的大型回转载荷进行严格的动平衡设计仿真与试验。结合海洋二号卫星研制需求,在产品设计初期开展了针对微波辐射计的动平衡设计仿真,以提供优化产品结构和布局的依据。为了评估空气环境对动平衡配平的影响,进行了辐射计动平衡配平的风阻影响分析。考虑了重力因素、在轨热变形和无重力下轴承径向游隙变化对辐射计动平衡的影响。最终在真空环境下开展了针对辐射计的动平衡试验,以很小的配重质量,实现了微波辐射计的配平。

  2. Assessment of Radiometer Calibration with GPS Radio Occultation for the MiRaTA CubeSat Mission.

    Science.gov (United States)

    Marinan, Anne D; Cahoy, Kerri L; Bishop, Rebecca L; Lui, Susan S; Bardeen, James R; Mulligan, Tamitha; Blackwell, William J; Leslie, R Vincent; Osaretin, Idahosa; Shields, Michael

    2016-12-01

    The Microwave Radiometer Technology Acceleration (MiRaTA) is a 3U CubeSat mission sponsored by the NASA Earth Science Technology Office (ESTO). The science payload on MiRaTA consists of a tri-band microwave radiometer and Global Positioning System (GPS) radio occultation (GPSRO) sensor. The microwave radiometer takes measurements of all-weather temperature (V-band, 50-57 GHz), water vapor (G-band, 175-191 GHz), and cloud ice (G-band, 205 GHz) to provide observations used to improve weather forecasting. The Aerospace Corporation's GPSRO experiment, called the Compact TEC (Total Electron Content) and Atmospheric GPS Sensor (CTAGS), measures profiles of temperature and pressure in the upper troposphere/lower stratosphere (∼20 km) and electron density in the ionosphere (over 100 km). The MiRaTA mission will validate new technologies in both passive microwave radiometry and GPS radio occultation: (1) new ultra-compact and low-power technology for multi-channel and multi-band passive microwave radiometers, (2) the application of a commercial off the shelf (COTS) GPS receiver and custom patch antenna array technology to obtain neutral atmospheric GPSRO retrieval from a nanosatellite, and (3) a new approach to spaceborne microwave radiometer calibration using adjacent GPSRO measurements. In this paper, we focus on objective (3), developing operational models to meet a mission goal of 100 concurrent radiometer and GPSRO measurements, and estimating the temperature measurement precision for the CTAGS instrument based on thermal noise. Based on an analysis of thermal noise of the CTAGS instrument, the expected temperature retrieval precision is between 0.17 K and 1.4 K, which supports the improvement of radiometric calibration to 0.25 K.

  3. Comparative evaluation of surface porosities in conventional heat polymerized acrylic resin cured by water bath and microwave energy with microwavable acrylic resin cured by microwave energy

    Directory of Open Access Journals (Sweden)

    Sunint Singh

    2013-01-01

    Full Text Available Background: Conventional heat cure poly methyl methacrylate (PMMA is the most commonly used denture base resin despite having some short comings. Lengthy polymerization time being one of them and in order to overcome this fact microwave curing method was recommended. Unavailability of specially designed microwavable acrylic resin made it unpopular. Therefore, in this study, conventional heat cure PMMA was polymerized by microwave energy. Aim and Objectives: This study was designed to evaluate the surface porosities in PMMA cured by conventional water bath and microwave energy and compare it with microwavable acrylic resin cured by microwave energy. Materials and Methods: Wax samples were obtained by pouring molten wax into a metal mold of 25 mm × 12 mm × 3 mm dimensions. These samples were divided into three groups namely C, CM, and M. Group C denotes conventional heat cure PMMA cured by water bath method, CM denotes conventional heat cure PMMA cured by microwave energy, M denotes specially designed microwavable acrylic denture base resin cured by microwave energy. After polymerization, each sample was scanned in three pre-marked areas for surface porosities using the optical microscope. As per the literature available, this instrument is being used for the first time to measure the porosity in acrylic resin. It is a reliable method of measuring area of surface pores. Portion of the sample being scanned is displayed on the computer and with the help of software area of each pore was measured and data were analyzed. Results: Conventional heat cure PMMA samples cured by microwave energy showed maximum porosities than the samples cured by conventional water bath method and microwavable acrylic resin cured by microwave energy. Higher percentage of porosities was statistically significant, but well within the range to be clinically acceptable. Conclusion: Within the limitations of this in-vitro study, conventional heat cure PMMA can be cured by

  4. Compensation Method of Radiowave Refraction Correction by Microwave Radiometer at Low-Angle%用辐射计进行低角电波折射修正的补偿方法

    Institute of Scientific and Technical Information of China (English)

    张瑜

    2001-01-01

    用微波辐射计进行电波折射修正是一种快速、精确的好方法。但由于它没有考虑电波射线弯曲所引起的折射误差,因此只适用在雷达天线仰角较高的条件,如在低仰角下使用该方法就会产生较大的误差。为了扩大其应用范围,本文提出了用微波辐射计进行低角电波折射修正的补偿方法,并且给出了精度检验结果。%The radiowave refraction correction by microwave radiometer is a fast and accurate way.But it ignores the bend refractive error,thus it can be used only under the condition of higher elevation.It will lead to bigger losses if the method is used at lower elevation. This paper presents a compensation method of radiowave refraction correction by microwave radiometer at low-angle and gives out the result of precision test.

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

    Energy Technology Data Exchange (ETDEWEB)

    Michalsky, J.; Harrison, L.; Min, Q. [State Univ. of New York, Albany, NY (United States)] [and others

    1996-04-01

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

  6. Microwave Spectrum of the Isopropanol-Water Dimer

    Science.gov (United States)

    Mead, Griffin; Finneran, Ian A.; Carroll, Brandon; Blake, Geoffrey

    2016-06-01

    Microwave spectroscopy provides a unique opportunity to study model non-covalent interactions. Of particular interest is the hydrogen bonding of water, whose various molecular properties are influenced by both strong and weak intermolecular forces. More specifically, measuring the hydrogen bonded structures of water-alcohol dimers investigates both strong (OH ··· OH) and weak (CH ··· OH) hydrogen bond interactions. Recently, we have measured the pure rotational spectrum of the isopropanol-water dimer using chirped-pulse Fourier transform microwave spectroscopy (CP-FTMW) between 8-18 GHz. Here, we present the spectrum of this dimer and elaborate on the structure's strong and weak hydrogen bonding.

  7. Combining ground-based microwave radiometer and the AROME convective scale model through 1DVAR retrievals in complex terrain: an Alpine valley case study

    Directory of Open Access Journals (Sweden)

    P. Martinet

    2017-09-01

    Full Text Available A RPG-HATPRO ground-based microwave radiometer (MWR was operated in a deep Alpine valley during the Passy-2015 field campaign. This experiment aims to investigate how stable boundary layers during wintertime conditions drive the accumulation of pollutants. In order to understand the atmospheric processes in the valley, MWRs continuously provide vertical profiles of temperature and humidity at a high time frequency, providing valuable information to follow the evolution of the boundary layer. A one-dimensional variational (1DVAR retrieval technique has been implemented during the field campaign to optimally combine an MWR and 1 h forecasts from the French convective scale model AROME. Retrievals were compared to radiosonde data launched at least every 3 h during two intensive observation periods (IOPs. An analysis of the AROME forecast errors during the IOPs has shown a large underestimation of the surface cooling during the strongest stable episode. MWR brightness temperatures were monitored against simulations from the radiative transfer model ARTS2 (Atmospheric Radiative Transfer Simulator and radiosonde launched during the field campaign. Large errors were observed for most transparent channels (i.e., 51–52 GHz affected by absorption model and calibration uncertainties while a good agreement was found for opaque channels (i.e., 54–58 GHz. Based on this monitoring, a bias correction of raw brightness temperature measurements was applied before the 1DVAR retrievals. 1DVAR retrievals were found to significantly improve the AROME forecasts up to 3 km but mainly below 1 km and to outperform usual statistical regressions above 1 km. With the present implementation, a root-mean-square error (RMSE of 1 K through all the atmospheric profile was obtained with values within 0.5 K below 500 m in clear-sky conditions. The use of lower elevation angles (up to 5° in the MWR scanning and the bias correction were found to improve the

  8. Combining ground-based microwave radiometer and the AROME convective scale model through 1DVAR retrievals in complex terrain: an Alpine valley case study

    Science.gov (United States)

    Martinet, Pauline; Cimini, Domenico; De Angelis, Francesco; Canut, Guylaine; Unger, Vinciane; Guillot, Remi; Tzanos, Diane; Paci, Alexandre

    2017-09-01

    A RPG-HATPRO ground-based microwave radiometer (MWR) was operated in a deep Alpine valley during the Passy-2015 field campaign. This experiment aims to investigate how stable boundary layers during wintertime conditions drive the accumulation of pollutants. In order to understand the atmospheric processes in the valley, MWRs continuously provide vertical profiles of temperature and humidity at a high time frequency, providing valuable information to follow the evolution of the boundary layer. A one-dimensional variational (1DVAR) retrieval technique has been implemented during the field campaign to optimally combine an MWR and 1 h forecasts from the French convective scale model AROME. Retrievals were compared to radiosonde data launched at least every 3 h during two intensive observation periods (IOPs). An analysis of the AROME forecast errors during the IOPs has shown a large underestimation of the surface cooling during the strongest stable episode. MWR brightness temperatures were monitored against simulations from the radiative transfer model ARTS2 (Atmospheric Radiative Transfer Simulator) and radiosonde launched during the field campaign. Large errors were observed for most transparent channels (i.e., 51-52 GHz) affected by absorption model and calibration uncertainties while a good agreement was found for opaque channels (i.e., 54-58 GHz). Based on this monitoring, a bias correction of raw brightness temperature measurements was applied before the 1DVAR retrievals. 1DVAR retrievals were found to significantly improve the AROME forecasts up to 3 km but mainly below 1 km and to outperform usual statistical regressions above 1 km. With the present implementation, a root-mean-square error (RMSE) of 1 K through all the atmospheric profile was obtained with values within 0.5 K below 500 m in clear-sky conditions. The use of lower elevation angles (up to 5°) in the MWR scanning and the bias correction were found to improve the retrievals below 1000 m. MWR

  9. Refraction of microwave signals by water vapor

    Science.gov (United States)

    Goldfinger, A. D.

    1980-01-01

    Tropospheric water vapor causes a refractive path length effect which is typically 5-10% of the 'dry' tropospheric effect and as large as several meters at elevation angles below 5 deg. The vertical water vapor profile is quite variable, and measurements of intensive atmospheric parameters such as temperature and humidity limited to the surface do not adequately predict the refractive effect. It is suggested that a water vapor refraction model that is a function of the amount of precipitable water alone can be successful at low elevation angles. From an extensive study of numerical ray tracings through radiosonde balloon data, such a model has been constructed. The model predicts the effect at all latitudes and elevation angles between 2 and 10 deg to an accuracy of better than 4% (11 cm at 3 deg elevation angle).

  10. Estimating vegetation optical depth using L-band passive microwave airborne data in HiWATER

    Science.gov (United States)

    Wang, Qi; Chai, Linna

    2014-11-01

    In this study, a relationship between polarization differences of soil emissivity at different incidence angles was constructed from a large quantity of simulated soil emissivity based on the Advanced Integrated Emission Model (AIEM) input parameters include: a frequency of 1.4 GHz (L-band), incident angles varying from 1°to 60° at a 1° interval, a wide range of soil moisture content and land surface roughness parameters. Then, we used this relationship and the ω-τ zero-order radiation transfer model to develop an inversion method of low vegetation optical depth at L-band, this work were under the assumption that there was no significant polarization difference between the vegetation signals. Based on this inversion method of low vegetation optical depth, we used the land surface passive microwave brightness temperature of Heihe Watershed obtained by airborne Polarimetric L-band Multibeam Radiometer (PLMR) in 2012 Heihe Watershed Allied Telemetry Experimental Research (HiWATER) to retrieve the corn optical depth in the flight areas, then the results were compared with the measured corn LAI. Results show that the retrieved corn optical depths were consisted with the measured LAI of corn. It proved that the corn optical depth inversion method proposed in this study was feasible. Moreover, the method was promising to apply to the satellite observations.

  11. Analysis of a hailstorm event in the middle Yangtze River basin using ground microwave radiometers%地基微波辐射计对咸宁一次冰雹天气过程的监测分析

    Institute of Scientific and Technical Information of China (English)

    唐仁茂; 李德俊; 向玉春; 徐桂荣; 李跃清; 陈英英

    2012-01-01

    A hailstorm event in the middle basin of the Yangtze River on 12 April 2010 is observed by the ground microwave radiometer located at Xianning, Hubei Province, China. The results show:(1) In the hail cloud very strong the updraft caused volatility of the cloud base height, while continuous upward transport of low-level air sensible heat and latent heat lead isotherms to upward lifting, with the other processes associated with the Bergeron effect and ice crystal depletion. Because of these macro and micro processes, the integrated water vapor and integrated liquid water content experinced continuous decline or rise, resulting in a multi-peak structure. (2) It is clear that, in the 4. 2 -8 km supercooled layer of hail cloud, dynamic exchange among water solid, liquid and vapor phases is very complex during the period of 08:40- 13:00 UTC. characterized by alternating among droplet-ice depletion, Bergeron process and droplet-ice growth, causing an area of relative humidity less than 80% below 6 km with the liquid water content large value area of 0. 7 - 1. 8 g/m3 occuring in the height of 4. 2 - 8 km, which results in forming the hail growth environment of alternating between wet and dry growth, conducive to the hail particles rapid accumulation and growth in stratified groups. (3) Using the microwave radiometer data to calculate the four instability indices MKI, KI, TT and HI, we find these indicators have a good indication to severe convective weather, and show a potential to severe weather nowcasting. If KI ≥38 is selected as early warning indicators of severe convective weather in the region, early warning can be issued 45 min ahead for the first hail severe convective weather, and it can issue early warning of the 2nd, 3rd, 4th convective cell that will impact the region, 20 min, 40 min and 42 min ahead of time, respectively.%利用咸宁MP-3000A地基微波辐射计探测资料对2010年4月12日发生在咸宁的一次冰雹天气过程进

  12. Cross-validation of two liquid water path retrieval algorithms applied to ground-based microwave radiation measurements by RPG-HATPRO instrument

    Science.gov (United States)

    Kostsov, Vladimir; Ionov, Dmitry; Biryukov, Egor; Zaitsev, Nikita

    2017-04-01

    A built-in operational regression algorithm (REA) of liquid water path (LWP) retrieval supplied by the manufacturer of the RPG-HATPRO microwave radiometer has been compared to a so-called physical algorithm (PHA) based on the inversion of the radiative transfer equation. The comparison has been performed for different scenarios of microwave observations by the RPG-HATPRO instrument that has been operating at St.Petersburg University since June 2012. The data for the scenarios have been collected within the time period December 2012 - December 2014. The estimations of bias and random error for both REA and PHA have been obtained. Special attention has been paid to the analysis of the quality of the LWP retrievals during and after rain events that have been detected by the built-in rain sensor. The estimation has been done of the time period after a rain event when the retrieval quality has to be considered as insufficient.

  13. Microwave measurements of temperature profiles, integrated water vapour, and liquid water path at Thule Air Base, Greenland.

    Science.gov (United States)

    Pace, Giandomenico; Di Iorio, Tatiana; di Sarra, Alcide; Iaccarino, Antonio; Meloni, Daniela; Mevi, Gabriele; Muscari, Giovanni; Cacciani, Marco

    2017-04-01

    A RPG Humidity And Temperature PROfiler (HATPRO-G2 ) radiometer was installed at Thule Air Base (76.5° N, 68.8° W), Greenland, in June 2016 in the framework of the Study of the water VApour in the polar AtmosPhere (SVAAP) project. The Danish Meteorological Institute started measurements of atmospheric properties at Thule Air Base in early '90s. The Thule High Arctic Atmospheric Observatory (THAAO) has grown in size and observing capabilities during the last three decades through the international effort of United States (NCAR and University of Alaska Fairbanks) and Italian (ENEA, INGV, University of Roma and Firenze) institutions (http://www.thuleatmos-it.it). Within this context, the intensive field campaign of the SVAAP project was aimed at the investigation of the surface radiation budget and took place from 5 to 28 July, 2016. After the summer campaign the HATPRO has continued to operate in order to monitor the annual variability of the temperature profile and integrated water vapour as well as the presence and characteristics of liquid clouds in the Artic environment. The combined use of the HATPRO together with other automatic instruments, such as a new microwave spectrometer (the water Vapour Emission Spectrometer for Polar Atmosphere VESPA-22), upward- and downward-looking pyranometers and pyrgeometers, a zenith-looking pyrometer operating in the 9.6-11.5 µm spectral range, an all sky camera, and a meteorological station, allows to investigate the clouds' physical and optical properties, as well as their impact on the surface radiation budget. This study will present and discuss the first few months of HATPRO observations; the effectiveness of the statistical retrieval used to derive the physical parameters from the HATPRO brightness temperatures will also be investigated through the comparison of the temperature and humidity profiles, and integrated water vapour, with data from radiosondes launched during the summer campaign and in winter time.

  14. L-Band Radiometers Measuring Salinity From Space: Atmospheric Propagation Effects

    DEFF Research Database (Denmark)

    Skou, Niels; Hofman-Bang, Dorthe

    2005-01-01

    Microwave radiometers can measure sea surface salinity from space using L-band frequencies around 1.4 GHz. However, requirements to the accuracy of the measurements, in order to be satisfactory for the user, are so stringent that the influence of the intervening atmosphere cannot be neglected....... The present paper will describe and quantify the effect of losses in the atmosphere caused by oxygen, water vapor, clouds, and rain, and indicate possible correction actions to be taken....

  15. A 200 MHz Bandwidth, 4096 Spectral Channels, 3 W Power Consumption, Digital Auto-Correlation Spectrometer Chip for Spaceborne Microwave Radiometers Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA?s program for Exploration of the Solar System requires high-resolution microwave spectrometers for the analysis of chemical composition and physical properties...

  16. Evaluation of Empirical Tropospheric Models Using Satellite-Tracking Tropospheric Wet Delays with Water Vapor Radiometer at Tongji, China.

    Science.gov (United States)

    Wang, Miaomiao; Li, Bofeng

    2016-02-02

    An empirical tropospheric delay model, together with a mapping function, is commonly used to correct the tropospheric errors in global navigation satellite system (GNSS) processing. As is well-known, the accuracy of tropospheric delay models relies mainly on the correction efficiency for tropospheric wet delays. In this paper, we evaluate the accuracy of three tropospheric delay models, together with five mapping functions in wet delays calculation. The evaluations are conducted by comparing their slant wet delays with those measured by water vapor radiometer based on its satellite-tracking function (collected data with large liquid water path is removed). For all 15 combinations of three tropospheric models and five mapping functions, their accuracies as a function of elevation are statistically analyzed by using nine-day data in two scenarios, with and without meteorological data. The results show that (1) no matter with or without meteorological data, there is no practical difference between mapping functions, i.e., Chao, Ifadis, Vienna Mapping Function 1 (VMF1), Niell Mapping Function (NMF), and MTT Mapping Function (MTT); (2) without meteorological data, the UNB3 is much better than Saastamoinen and Hopfield models, while the Saastamoinen model performed slightly better than the Hopfield model; (3) with meteorological data, the accuracies of all three tropospheric delay models are improved to be comparable, especially for lower elevations. In addition, the kinematic precise point positioning where no parameter is set up for tropospheric delay modification is conducted to further evaluate the performance of tropospheric delay models in positioning accuracy. It is shown that the UNB3 model is best and can achieve about 10 cm accuracy for the N and E coordinate component while 20 cm accuracy for the U coordinate component no matter the meteorological data is available or not. This accuracy can be obtained by the Saastamoinen model only when meteorological data is

  17. Evaluation of Empirical Tropospheric Models Using Satellite-Tracking Tropospheric Wet Delays with Water Vapor Radiometer at Tongji, China

    Directory of Open Access Journals (Sweden)

    Miaomiao Wang

    2016-02-01

    Full Text Available An empirical tropospheric delay model, together with a mapping function, is commonly used to correct the tropospheric errors in global navigation satellite system (GNSS processing. As is well-known, the accuracy of tropospheric delay models relies mainly on the correction efficiency for tropospheric wet delays. In this paper, we evaluate the accuracy of three tropospheric delay models, together with five mapping functions in wet delays calculation. The evaluations are conducted by comparing their slant wet delays with those measured by water vapor radiometer based on its satellite-tracking function (collected data with large liquid water path is removed. For all 15 combinations of three tropospheric models and five mapping functions, their accuracies as a function of elevation are statistically analyzed by using nine-day data in two scenarios, with and without meteorological data. The results show that (1 no matter with or without meteorological data, there is no practical difference between mapping functions, i.e., Chao, Ifadis, Vienna Mapping Function 1 (VMF1, Niell Mapping Function (NMF, and MTT Mapping Function (MTT; (2 without meteorological data, the UNB3 is much better than Saastamoinen and Hopfield models, while the Saastamoinen model performed slightly better than the Hopfield model; (3 with meteorological data, the accuracies of all three tropospheric delay models are improved to be comparable, especially for lower elevations. In addition, the kinematic precise point positioning where no parameter is set up for tropospheric delay modification is conducted to further evaluate the performance of tropospheric delay models in positioning accuracy. It is shown that the UNB3 model is best and can achieve about 10 cm accuracy for the N and E coordinate component while 20 cm accuracy for the U coordinate component no matter the meteorological data is available or not. This accuracy can be obtained by the Saastamoinen model only when

  18. An atlas of mean distribution of precipitable water vapour over the tropical Indian Ocean for the year 1979

    Digital Repository Service at National Institute of Oceanography (India)

    RameshKumar, M.R.; Sathe, P.V.; Muraleedharan, P.M.; Rao, L.V.G.

    The monthly mean maps of the precipitable water (PW) over the tropical Indian Ocean are prepared using the data derived from the Nimbus 7 Scanning Multichannel Microwave Radiometer (SMMR) sensor for the period January to December, 1979. The PW...

  19. The Cubesat Radiometer Radio Frequency Interference Technology Validation (CubeRRT) Mission

    Science.gov (United States)

    Misra, S.; Johnson, J. T.; Ball, C.; Chen, C. C.; Smith, G.; McKelvey, C.; Andrews, M.; O'Brien, A.; Kocz, J.; Jarnot, R.; Brown, S. T.; Piepmeier, J. R.; Lucey, J.; Miles, L. R.; Bradley, D.; Mohammed, P.

    2016-12-01

    Passive microwave measurements made below 40GHz have experienced increased amounts of man-made radio frequency interference (RFI) over the past couple of decades. Such RFI has had a degenerative impact on various important geophysical retrievals such as soil-moisture, sea-surface salinity, atmospheric water vapor, precipitation etc. The commercial demand for spectrum allocation has increased over the past couple of years - infringing on frequencies traditionally reserved for scientific uses such as Earth observation at passive microwave frequencies. With the current trend in shared spectrum allocations, future microwave radiometers will have to co-exist with terrestrial RFI sources. The CubeSat Radiometer Radio Frequency Interference Technology Validation (CubeRRT) mission is developing a 6U Cubesat system to demonstrate RFI detection and filtering technologies for future microwave radiometer remote sensing missions. CubeRRT will operate between 6-40GHz, and demonstrate on-board real-time RFI detection on Earth brightness temperatures tuned over 1GHz steps. The expected launch date for CubeRRT is early 2018. Digital subsystems for higher frequency microwave radiometry require a larger bandwidth, as well as more processing power and on-board operation capabilities for RFI filtering. Real-time and on-board RFI filtering technology development is critical for future missions to allow manageable downlink data volumes. The enabling CubeRRT technology is a digital FPGA-based spectrometer with a bandwidth of 1 GHz that is capable of implementing advanced RFI filtering algorithms that use the kurtosis and cross-frequency RFI detection methods in real-time on board the spacecraft. The CubeRRT payload consists of 3 subsystems: a wideband helical antenna, a tunable analog radiometer subsystem, and a digital backend. The following presentation will present an overview of the system and results from the latest integration and test.

  20. Space-based passive microwave soil moisture retrievals and the correction for a dynamic open water fraction

    Directory of Open Access Journals (Sweden)

    B. T. Gouweleeuw

    2012-06-01

    Full Text Available The large observation footprint of low-frequency satellite microwave emissions complicates the interpretation of near-surface soil moisture retrievals. While the effect of sub-footprint lateral heterogeneity is relatively limited under unsaturated conditions, open water bodies (if not accounted for cause a strong positive bias in the satellite-derived soil moisture retrieval. This bias is generally assumed static and associated with large, continental lakes and coastal areas. Temporal changes in the extent of smaller water bodies as small as a few percent of the sensor footprint size, however, can cause significant and dynamic biases. We analysed the influence of such small open water bodies on near-surface soil moisture products derived from actual (non-synthetic data from the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E for three areas in Oklahoma, USA. Differences between on-ground observations, model estimates and AMSR-E retrievals were related to dynamic estimates of open water fraction, one retrieved from a global daily record based on higher frequency AMSR-E data, a second derived from the Moderate Resolution Imaging Spectroradiometer (MODIS and a third through inversion of the radiative transfer model, used to retrieve soil moisture. The comparison demonstrates the presence of relatively small areas (<0.05 of open water in or near the sensor footprint, possibly in combination with increased, below-critical vegetation density conditions (optical density <0.8, which contribute to seasonally varying biases in excess of 0.2 (m3 m−3 soil water content. These errors need to be addressed, either through elimination or accurate characterisation, if the soil moisture retrievals are to be used effectively in a data assimilation scheme.

  1. Retrieving cloudy atmosphere parameters from RPG-HATPRO radiometer data

    Science.gov (United States)

    Kostsov, V. S.

    2015-03-01

    An algorithm for simultaneously determining both tropospheric temperature and humidity profiles and cloud liquid water content from ground-based measurements of microwave radiation is presented. A special feature of this algorithm is that it combines different types of measurements and different a priori information on the sought parameters. The features of its use in processing RPG-HATPRO radiometer data obtained in the course of atmospheric remote sensing experiments carried out by specialists from the Faculty of Physics of St. Petersburg State University are discussed. The results of a comparison of both temperature and humidity profiles obtained using a ground-based microwave remote sensing method with those obtained from radiosonde data are analyzed. It is shown that this combined algorithm is comparable (in accuracy) to the classical method of statistical regularization in determining temperature profiles; however, this algorithm demonstrates better accuracy (when compared to the method of statistical regularization) in determining humidity profiles.

  2. Time series analysis of ground-based microwave measurements at K- and V-bands to detect temporal changes in water vapor and temperature profiles

    Science.gov (United States)

    Panda, Sibananda; Sahoo, Swaroop; Pandithurai, Govindan

    2017-01-01

    Ground-based microwave measurements performed at water vapor and oxygen absorption line frequencies are widely used for remote sensing of tropospheric water vapor density and temperature profiles, respectively. Recent work has shown that Bayesian optimal estimation can be used for improving accuracy of radiometer retrieved water vapor and temperature profiles. This paper focuses on using Bayesian optimal estimation along with time series of independent frequency measurements at K- and V-bands. The measurements are used along with statistically significant but short background data sets to retrieve and sense temporal variations and gradients in water vapor and temperature profiles. To study this capability, the Indian Institute of Tropical Meteorology (IITM) deployed a microwave radiometer at Mahabubnagar, Telangana, during August 2011 as part of the Integrated Ground Campaign during the Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX-IGOC). In this study, temperature profiles for the first time have been estimated using short but statistically significant background information so as to improve the accuracy of the retrieved profiles as well as to be able to detect gradients. Estimated water vapor and temperature profiles are compared with those taken from the reanalysis data updated by the Earth System Research Laboratory, National Oceanic and Atmospheric Administration (NOAA), to determine the range of possible errors. Similarly, root mean square errors are evaluated for a month for water vapor and temperature profiles to estimate the accuracy of the retrievals. It is found that water vapor and temperature profiles can be estimated with an acceptable accuracy by using a background information data set compiled over a period of 1 month.

  3. ARIS-Campaign: intercomparison of three ground based 22 GHz radiometers for middle atmospheric water vapor at the Zugspitze in winter 2009

    Directory of Open Access Journals (Sweden)

    C. Straub

    2011-09-01

    Full Text Available This paper presents the Alpine Radiometer Intercomparison at the Schneefernerhaus (ARIS, which took place in winter 2009 at the high altitude station at the Zugspitze, Germany (47.42° N, 10.98° E, 2650 m. This campaign was the first direct intercomparison between three new ground based 22 GHz water vapor radiometers for middle atmospheric profiling with the following instruments participating: MIRA 5 (Karlsruhe Institute of Technology, cWASPAM3 (Max Planck Institute for Solar System Research, Katlenburg-Lindau and MIAWARA-C (Institute of Applied Physics, University of Bern. Even though the three radiometers all measure middle atmospheric water vapor using the same rotational transition line and similar fundamental set-ups, there are major differences between the front ends, the back ends, the calibration concepts and the profile retrieval. The spectrum comparison shows that all three radiometers measure spectra without severe baseline artifacts and that the measurements are in good general agreement. The measurement noise shows good agreement to the values theoretically expected from the radiometer noise formula. At the same time the comparison of the noise levels shows that there is room for instrumental and calibration improvement, emphasizing the importance of low elevation angles for the observation, a low receiver noise temperature and an efficient calibration scheme.

    The comparisons of the retrieved profiles show that the agreement between the profiles of MIAWARA-C and cWASPAM3 with the ones of MLS is better than 0.3 ppmv (6% at all altitudes. MIRA 5 has a dry bias of approximately 0.5 ppm (8% below 0.1 hPa with respect to all other instruments. The profiles of cWASPAM3 and MIAWARA-C could not be directly compared because the vertical region of overlap was too small. The comparison of the time series at different altitude levels show a similar evolution of the H2O volume mixing ratio (VMR for the ground based

  4. Compact Radiometers Expand Climate Knowledge

    Science.gov (United States)

    2010-01-01

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

  5. Design of High-Speed Digital Correlator in Fully Polarimetric Microwave Radiometer%全极化微波辐射计系统中高速数字相关器设计

    Institute of Scientific and Technical Information of China (English)

    陆浩; 王振占; 刘憬怡; 姜景山

    2011-01-01

    Fully polarimetric microwave radiometer is a new type of passive microwave sensor for measuring ocean wind vector.Digital correlation technology is used inside it to get all the four Stokes parameters of ocean emission in this paper. Digital correlator is the main part of the fully polarimetric radiometer. In the paper, design of a novel digital correlator is presented. Two high-speed, dual A/D converters are used to sample four signals, and the sampling results are operated in FPGA-Vertex5 to make both self- and cross-correlation calculations. The testing results of the correlator are given. The sampling rate is 360 MHz with effective number of bits more than 7.2 bits in 8 bits resolution. For both 100 MHz and ISO MHz input, the correlation coefficient between the measurements and their theoretical results is more than 0.9999999.The whole power of digital correlator is 11.3 W.%海面风场直接影响大气与大洋环流相互作用,是研究海流运动规律的必要条件.全极化微波辐射计是一种用于海洋表面风场测量的新型被动微波遥感器.数字相关器是全极化辐射计的核心部件.文中详细介绍了一种新型数字相关器的设计和实现.两片高速A/D转换器采样四路信号并通过XILINX公司新一代的FPGA-Vertex5作相关运算.同时本文给出了数字相关器的测试结果.相关器采样率360MHz,8bit量化,测试有效位数在7.2bit以上.100MHz和150MHz信号输入下,测量值与理论值之间的相关系数在0.9999999以上.系统功耗11.3W.

  6. Cloud effective particle size and water content profile retrievals using combined lidar and radar observations: 2. Comparison with IR radiometer and in situ measurements of ice clouds

    Science.gov (United States)

    Donovan, D. P.; van Lammeren, A. C. A. P.; Hogan, R. J.; Russchenberg, H. W. J.; Apituley, A.; Francis, P.; Testud, J.; Pelon, J.; Quante, M.; Goddard, J.

    2001-11-01

    A new combined iidar/radar inversion procedure has been developed for cloud effective radius and water content retrievals. The algorithm treats the lidar extinction, derived effective particle size, and multiple-scattering effects together in a consistent fashion. This procedure has been applied to data taken during the Netherlands Cloud and Radiation (CLARA) campaign and the Cloud Lidar and Radar Experiment (CLARE'98) multisensor cloud measurement campaign. The results of the algorithm compare well with simultaneous IR radiometer cloud measurements as well as with measurements made by using aircraft-mounted two-dimensional probe particle-sizing instruments.

  7. Design of a Shadowband Spectral Radiometer for the Retrieval of Thin Cloud Optical Depth, Liquid Water Path, and the Effective Radius

    Energy Technology Data Exchange (ETDEWEB)

    Bartholomew M. J.; Reynolds, R. M.; Vogelmann, A. M.; Min, Q.; Edwards, R.; Smith, S.

    2011-11-01

    The design and operation of a Thin-Cloud Rotating Shadowband Radiometer (TCRSR) described here was used to measure the radiative intensity of the solar aureole and enable the simultaneous retrieval of cloud optical depth, drop effective radius, and liquid water path. The instrument consists of photodiode sensors positioned beneath two narrow metal bands that occult the sun by moving alternately from horizon to horizon. Measurements from the narrowband 415-nm channel were used to demonstrate a retrieval of the cloud properties of interest. With the proven operation of the relatively inexpensive TCRSR instrument, its usefulness for retrieving aerosol properties under cloud-free skies and for ship-based observations is discussed.

  8. The Hurricane Imaging Radiometer: Present and Future

    Science.gov (United States)

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

    2013-01-01

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

  9. Water promoted,microwave-assisted oxidative novel deamination of N-aminoquinazolinones

    Institute of Scientific and Technical Information of China (English)

    M.Arfan; Rasool Khan; Shazia Anjum; Shabir Ahmad; M.Iqbal Choudhary

    2008-01-01

    A novel deamination of 2-alkyl/aryl 3-amino-4(3H)-qninazolinones series using aqueous KMnO4 under thermal condition and microwave irradiation is described.Compared to thermal condition,significantly higher yields in much shorter times were observedfor reactions under microwave irradiation.A plausible mechanism has been proposed for the oxidative water-promoted deamination.

  10. Microwave Powered Gravitationally Independent Medical Grade Water Generation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Development of an innovative microwave-based continuous flow sterilization system for the energy efficient gravitationally independent production of Medical Grade...

  11. Microwave superheated water extraction of polysaccharides from spent coffee grounds.

    Science.gov (United States)

    Passos, Cláudia P; Coimbra, Manuel A

    2013-04-15

    The spent coffee grounds (SCG) are a food industry by-product that can be used as a rich source of polysaccharides. In the present work, the feasibility of microwave superheated water extraction of polysaccharides from SCG was studied. Different ratios of mass of SCG to water, from 1:30 to 1:5 (g:mL) were used for a total volume of 80 mL. Although the amount of material extracted/batch (MAE1) increased with the increase of the concentration of the sample, the amount of polysaccharides achieved a maximum of 0.57 g/batch for 1:10. Glycosidic-linkage composition showed that all extraction conditions allowed to obtain mainly arabinogalactans. When the unextracted insoluble material was re-extracted under the same conditions (MAE2), a further extraction of polysaccharides was observed (0.34 g/batch for 1:10), mainly galactomannans. Also, a high amount of oligosaccharides, mainly derived from galactomannans, can be obtained in MAE2 (0.96 g/batch for 1:10). This technology allows to obtain galactomannans and arabinogalactans in proportions that are dependent on the operating conditions.

  12. Determination of water vapor and ozone profiles in the middle atmosphere by microwave-spectroscopy. Bestimmung von Wasserdampf- und Ozonprofilen in der mittleren Atmosphaere durch Millimeterwellenspektroskopie

    Energy Technology Data Exchange (ETDEWEB)

    Puliafito, S.E.

    1989-10-17

    This work was performed at the Max-Planck-Institut fuer Aeronomie (F.R.G.) and treats the following points: 1. Satellite borne microwave radiometry. Principles for a real-time evaluation of the MAS-Limb-Sounding measurements. (MAS: Millimeter Wave Atmospheric Sounder from Space Shuttle as part of the NASA ATLAS Missions, 1991-1997). (a) Deconvolution of the 60 GHz-antenna. (b) Test of different inversion proceedings. A detailed study of the boundary conditions and 'error influence' as well as a discussion of the radiometer specifications. (c) Near real time inversion of microwave spectral lines of the Earth atmosphere. i. The possibility of a (near) real time evaluation (retrieval of the profiles of the atmospheric components) was proved for the first time with a space proof microprocessor. ii. Data reduction of about a factor > 10{sup 3} in comparison with other methods. 2. Airborne and ground based microwave radiometry. (a) Study of the possibilities of ground- and aircraft based measurements for validation and cross calibration of the satellite measurements. (b) Study of the possibilities of ground based radiometric measurements of water vapour in the Artic or Antartica. Precise boundary conditions were given for the first time in order to perform ground based millimeter radiometric measurements in these areas. (orig.).

  13. Water Vapor Radiometer-Global Positioning System Comparison Measurements and Calibration of the 20 to 32 Gigahertz Tropospheric Water Vapor Absorption Model

    Science.gov (United States)

    Keihm, S. J.; Bar-Sever, Y.; Liljegren, J.

    2000-10-01

    Collocated measurements of opacity (from water vapor radiometer (WVR) brightness temperatures) and wet path delay (from ground-based tracking of Global Positions System (GPS) satellites) are used to constrain the model of atmospheric water vapor absorption in the 20 to 32 GHz band. A differential approach is presented in which the slope of opacity-versus-wet delay data is used as the absorption model constraint. This technique minimizes the effects of radiometric calibration errors and oxygen model uncertainties in the derivation of a best-fit vapor absorption model. A total of approximately 5 months of data were obtained from two experiment sites. At the Cloud and Radiation Testbed (CART) site near Lamont, Oklahoma, three independent WVRs provided near-continuous opacity measurements over the interval from July through September 1998. At NASA's Goldstone tracking station in the California desert, two WVRs obtained opacity data over the September through October 1997 interval. At both sites, a GPS receiver and surface barometer obtained the data required for deriving the zenith wet delays over the same time frames. Measured values of the opacity-versus-wet delay slope parameter were obtained at four WVR frequencies (20.7, 22.2, 23.8, and 31.4 GHz) and compared with predictions of three candidate absorption models referenced in the recent literature. With one exception, all three models provide agreement within approximately 5 percent of the opacity-versus-wet delay slope measurements at all WVR frequencies at both sites. One model provides agreement for all channels at both sites to the 2 to 3 percent level. This accuracy is sufficient to meet the requirements of the tropospheric calibration system now being deployed at Goldstone to support the Cassini Gravitational Wave Experiment.

  14. Nanopigmented Acrylic Resin Cured Indistinctively by Water Bath or Microwave Energy for Dentures

    Directory of Open Access Journals (Sweden)

    L. S. Acosta-Torres

    2014-01-01

    Full Text Available The highlight of this study was the synthesis of nanopigmented poly(methyl methacrylate nanoparticles that were further processed using a water bath and/or microwave energy for dentures. The experimental acrylic resins were physicochemically characterized, and the adherence of Candida albicans and biocompatibility were assessed. A nanopigmented acrylic resin cured by a water bath or by microwave energy was obtained. The acrylic specimens possess similar properties to commercial acrylic resins, but the transverse strength and porosity were slightly improved. The acrylic resins cured with microwave energy exhibited reduced C. albicans adherence. These results demonstrate an improved noncytotoxic material for the manufacturing of denture bases in dentistry.

  15. Comparison of tropospheric integrated water vapor content by using GPS, radiosonde, radiometer data and models for the tropical Island of Tahiti (French Polynesia)

    Science.gov (United States)

    Serafini, J.; Barriot, J.; Fadil, A.; Sichoix, L.

    2011-12-01

    The integrated precipitable water (IPW) in the troposphere can be subject to strong spatial and temporal variations, in particular over tropical zones. The IPW is estimated at the Geodetic Tahiti Observatory site from GPS, radiosonde, radiometer measurements. 8 years (2001-2008) of GPS observations at the IGS THTI station are processed with the GIPSY-OASIS II software package following the precise point positioning (PPP) mode. We compare the IPW of the permanent GPS data with those derived from the collocated radiometer and radiosonde data. The Global Forecast System (GFS) model which covers the entire globe with one degree latitude and longitude grid spacing, is then used to obtain the IPW at the same site. The meteorological surface data (pressure, temperature and relative humidity) also help to compute the IPW by using the Saastamoinen model. Finally, the analysis of the correlation between all these IPW estimates leads us to re-adjust the Saastamoinen parameters such that correction coefficients now better constrain the tropospheric model.

  16. Analysis of radiometer calibration effects with TOUCHSTONE

    Science.gov (United States)

    Stanley, William D.

    1990-01-01

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

  17. Radiometer on a Chip

    Science.gov (United States)

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

    2009-01-01

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

  18. Sensitivity of Forward Radiative Transfer Model on Spectroscopic Assumptions and Input Geophysical Parameters at 23.8 GHz and 183 GHz Channels and its Impact on Inter-calibration of Microwave Radiometers

    Science.gov (United States)

    Datta, S.; Jones, W. L.; Ebrahimi, H.; Chen, R.; Payne, V.; Kroodsma, R.

    2014-12-01

    The first step in radiometric inter-calibration is to ascertain the self-consistency and reasonableness of the observed brightness temperature (Tb) for each individual sensor involved. One of the widely used approaches is to compare the observed Tb with a simulated Tb using a forward radiative transfer model (RTM) and input geophysical parameters at the geographic location and time of the observation. In this study we intend to test the sensitivity of the RTM to uncertainties in the input geophysical parameters as well as to the underlying physical assumptions of gaseous absorption and surface emission in the RTM. SAPHIR, a cross track scanner onboard Indo-French Megha-Tropique Satellite, gives us a unique opportunity of studying 6 dual band 183 GHz channels at an inclined orbit over the Tropics for the first time. We will also perform the same sensitivity analysis using the Advance Technology Microwave Sounder (ATMS) 23 GHz and five 183 GHz channels. Preliminary analysis comparing GDAS and an independent retrieved profile show some sensitivity of the RTM to the input data. An extended analysis of this work using different input geophysical parameters will be presented. Two different absorption models, the Rosenkranz and the MonoRTM will be tested to analyze the sensitivity of the RTM to spectroscopic assumptions in each model. Also for the 23.8 GHz channel, the sensitivity of the RTM to the surface emissivity model will be checked. Finally the impact of these sensitivities on radiometric inter-calibration of radiometers at sounding frequencies will be assessed.

  19. Process Parameter Study on Microwave-assisted Foam-mat Drying Properties of Corn Soaking Water

    Institute of Scientific and Technical Information of China (English)

    Zheng Xian-zhe

    2016-01-01

    In order to study the microwave-assisted foam-mat drying properties of corn soaking water and optimize process parameters, a quadratic regression orthogonal rotary method was used to analyze the influence of microwave power, material weight, material thickness and drying time on moisture content (dry basis), color value and protein content. Results showed that the primary and secondary sequence of parameters with regard to moisture content (d. b.) was drying time, microwave power, material weight and material thickness; the primary and secondary sequence of parameters with regard to color value was material weight, drying time, microwave power and material thickness; the primary and secondary sequence of parameters with regard to protein content was drying time, material weight, microwave power and material thickness. Optimum conditions were obtained as microwave power of 560 W, material weight of 46.88 g, material thickness of 6.20 mm and drying time of 8.01 min. The results might provide the theoretical basis and technical support for the microwave-assisted foam-mat drying of corn soaking water to produce yeast protein power.

  20. Investigation of the effects of summer melt on the calculation of sea ice concentration using active and passive microwave data

    Science.gov (United States)

    Cavalieri, Donald J.; Burns, Barbara A.; Onstott, Robert G.

    1990-01-01

    The effects of ice surface melt on microwave signatures and errors in the calculation of sea ice concentration are examined, using active and passive microwave data sets from the Marginal Ice Zone Experiment aircraft flights in the Fram Strait region. Consideration is given to the possibility of using SAR to supplement passive microwave data to unambiguously discriminate between open water areas and ponded floes. Coincident active multichannel microwave radiometer and SAR measurements of individual floes are used to describe the effects of surface melt on sea ice concentration calculations.

  1. Optimizing available water capacity using microwave satellite data for improving irrigation management

    Science.gov (United States)

    Gupta, Manika; Bolten, John; Lakshmi, Venkat

    2015-04-01

    This work addresses the improvement of available water capacity by developing a technique for estimating soil hydraulic parameters through the utilization of satellite-retrieved near surface soil moisture. The prototype involves the usage of Monte Carlo analysis to assimilate historical remote sensing soil moisture data available from the Advanced Microwave Scanning Radiometer (AMSR-E) within the hydrological model. The main hypothesis used in this study is that near-surface soil moisture data contain useful information that can describe the effective hydrological conditions of the basin such that when appropriately In the method followed in this study the hydraulic parameters are derived directly from information on the soil moisture state at the AMSR-E footprint scale and the available water capacity is derived for the root zone by coupling of AMSR-E soil moisture with the physically-based hydrological model. The available capacity water, which refers to difference between the field capacity and wilting point of the soil and represent the soil moisture content at 0.33 bar and 15 bar respectively is estimated from the soil hydraulic parameters using the van Genuchten equation. The initial ranges of soil hydraulic parameters are taken in correspondence with the values available from the literature based on Soil Survey Geographic (SSURGO) database within the particular AMSR-E footprint. Using the Monte Carlo simulation, the ranges are narrowed in the region where simulation shows a good match between predicted and near-surface soil moisture from AMSR-E. In this study, the uncertainties in accurately determining the parameters of the nonlinear soil water retention function for large-scale hydrological modeling is the focus of the development of the Bayesian framework. Thus, the model forecasting has been combined with the observational information to optimize the model state and the soil hydraulic parameters simultaneously. The optimization process is divided into

  2. Enhanced heating of salty water and ice under microwaves: Molecular dynamics study

    OpenAIRE

    Tanaka, Motohiko; Sato, Motoyasu

    2008-01-01

    By molecular dynamics simulations, we have studied the enhanced heating process of salty ice and water by the electric field of applied microwaves at 2.5 GHz, and those in the range 2.5-10 GHz for the frequency dependence. We show that water molecules in salty ice are allowed to rotate in response to the microwave electric field to the extent comparable to those in pure water, because the molecules in salty ice are loosely tied by hydrogen bonds with adjacent molecules unlike the case of rigi...

  3. Removal of caffeine from green tea by microwave-enhanced vacuum ice water extraction.

    Science.gov (United States)

    Lou, Zaixiang; Er, Chaojuan; Li, Jing; Wang, Hongxin; Zhu, Song; Sun, Juntao

    2012-02-24

    In order to selectively remove caffeine from green tea, a microwave-enhanced vacuum ice water extraction (MVIE) method was proposed. The effects of MVIE variables including extraction time, microwave power, and solvent to solid radio on the removal yield of caffeine and the loss of total phenolics (TP) from green tea were investigated. The optimized conditions were as follows: solvent (mL) to solid (g) ratio was 10:1, microwave extraction time was 6 min, microwave power was 350 W and 2.5 h of vacuum ice water extraction. The removal yield of caffeine by MVIE was 87.6%, which was significantly higher than that by hot water extraction, indicating a significant improvement of removal efficiency. Moreover, the loss of TP of green tea in the proposed method was much lower than that in the hot water extraction. After decaffeination by MVIE, the removal yield of TP tea was 36.2%, and the content of TP in green tea was still higher than 170 mg g(-1). Therefore, the proposed microwave-enhanced vacuum ice water extraction was selective, more efficient for the removal of caffeine. The main phenolic compounds of green tea were also determined, and the results indicated that the contents of several catechins were almost not changed in MVIE. This study suggests that MVIE is a new and good alternative for the removal of caffeine from green tea, with a great potential for industrial application. Copyright © 2011 Elsevier B.V. All rights reserved.

  4. The influence of microwave curing time and water glass kind on the properties of molding sands

    Directory of Open Access Journals (Sweden)

    K. Granat

    2007-12-01

    Full Text Available This work presents results of research on the influence of microwave heating time on the process of hardening of water glass molding sands. Essential influence of this drying process on basic properties such as: compression, bending and tensile strength as well as permeability and wear resistance, has been found. It has been proved, that all the investigated sorts of sodium water glass could be used as binding material of molding sands intended for curing with the microwave process heating. It has been found, while analyzing the results of property studies of microwave heated molding sands with 2.5% addition of water glass, that all available on the market kinds of this binding agent (including the most frequently used in foundry 145 and 149 kinds after microwave heating guarantee very good compression, bending and tensile strength as well as permeability and wear resistance. Moreover, it has been determined that the optimal curing time of molding sands containing various kinds of water glass is 240 seconds. After this time, all basic properties of molding sands are stable. The use of microwave curing of water glass molding sands results in a significant decrease of hardening process time, full stabilization of molding sands as well as much lower energy consumption.

  5. Microwave-enhanced pyrolysis of natural algae from water blooms.

    Science.gov (United States)

    Zhang, Rui; Li, Linling; Tong, Dongmei; Hu, Changwei

    2016-07-01

    Microwave-enhanced pyrolysis (MEP) of natural algae under different reaction conditions was carried out. The optimal conditions for bio-oil production were the following: algae particle size of 20-5 mesh, microwave power of 600W, and 10% of activated carbon as microwave absorber and catalyst. The maximum liquid yield obtained under N2, 10% H2/Ar, and CO2 atmosphere was 49.1%, 51.7%, and 54.3% respectively. The energy yield of bio-products was 216.7%, 236.9% and 208.7% respectively. More long chain fatty acids were converted into hydrocarbons by hydrodeoxygenation under 10% H2/Ar atmosphere assisted by microwave over activated carbon containing small amounts of metals. Under CO2 atmosphere, carboxylic acids (66.6%) were the main products in bio-oil because the existence of CO2 vastly inhibited the decarboxylation. The MEP of algae was quick and efficient for bio-oil production, which provided a way to not only ameliorate the environment but also obtain fuel or chemicals at the same time.

  6. Signatures of the two day wave and sudden stratospheric warmings in Arctic water vapour observed by ground-based microwave radiometry

    Directory of Open Access Journals (Sweden)

    B. Tschanz

    2015-01-01

    Full Text Available The ground-based microwave radiometer MIAWARA-C recorded the upper stratospheric and lower mesospheric water vapour distribution continuously from June 2011 to March 2013 above the Arctic station of Sodankylä, Finland (67.4° N, 26.6° E without major interruptions and offers water vapour profiles with temporal resolution of one hour for average conditions. Over the measurement period, the instrument monitored the changes in water vapour linked to two sudden stratospheric warmings in early 2012 and 2013. Based on the water vapour measurements, the descent rate in the vortex after the warmings is 364 m d−1 for 2012 and 315 m d−1 for 2013. The water vapour time series of MIAWARA-C shows strong periodic variations in both summer and winter related to the quasi two day wave. In the mesosphere the amplitudes are strongest in summer. The stratospheric wintertime two day wave is pronounced for both winters and reaches a maximum amplitude of 0.8 ppmv in November 2011.

  7. Determination of water content in clay and organic soil using microwave oven

    Science.gov (United States)

    Kramarenko, V. V.; Nikitenkov, A. N.; Matveenko, I. A.; Molokov, V. Yu; Vasilenko, Ye S.

    2016-09-01

    The article deals with the techniques of soil water content determination using microwave radiation. Its practical application would allow solving the problems of resource efficiency in geotechnical survey due to reduction of energy and resource intensity of laboratory analysis as well as its acceleration by means of decreasing labour intensity and, as a result, cost reduction. The article presents a detail analysis of approaches to soil water content determination and soil drying, considers its features and application. The study in soil of different composition, typical for Western Siberia including organic and organic-mineral ones, is a peculiarity of the given article, which makes it rather topical. The article compares and analyzes the results of the investigation into soil water content, which are obtained via conventional techniques and the original one developed by the authors, consisting in microwave drying. The authors also give recommendation on microwave technique application to dry soil.

  8. Observations of cloud liquid water path over oceans: Optical and microwave remote sensing methods

    Science.gov (United States)

    Lin, Bing; Rossow, William B.

    1994-01-01

    Published estimates of cloud liquid water path (LWP) from satellite-measured microwave radiation show little agreement, even about the relative magnitudes of LWP in the tropics and midlatitudes. To understand these differences and to obtain more reliable estimate, optical and microwave LWP retrieval methods are compared using the International Satellite Cloud Climatology Project (ISCCP) and special sensor microwave/imager (SSM/I) data. Errors in microwave LWP retrieval associated with uncertainties in surface, atmosphere, and cloud properties are assessed. Sea surface temperature may not produce great LWP errors, if accurate contemporaneous measurements are used in the retrieval. An uncertainty of estimated near-surface wind speed as high as 2 m/s produces uncertainty in LWP of about 5 mg/sq cm. Cloud liquid water temperature has only a small effect on LWP retrievals (rms errors less than 2 mg/sq cm), if errors in the temperature are less than 5 C; however, such errors can produce spurious variations of LWP with latitude and season. Errors in atmospheric column water vapor (CWV) are strongly coupled with errors in LWP (for some retrieval methods) causing errors as large as 30 mg/sq cm. Because microwave radiation is much less sensitive to clouds with small LWP (less than 7 mg/sq cm) than visible wavelength radiation, the microwave results are very sensitive to the process used to separate clear and cloudy conditions. Different cloud detection sensitivities in different microwave retrieval methods bias estimated LWP values. Comparing ISCCP and SSM/I LWPs, we find that the two estimated values are consistent in global, zonal, and regional means for warm, nonprecipitating clouds, which have average LWP values of about 5 mg/sq cm and occur much more frequently than precipitating clouds. Ice water path (IWP) can be roughly estimated from the differences between ISCCP total water path and SSM/I LWP for cold, nonprecipitating clouds. IWP in the winter hemisphere is about

  9. Pre-Launch Calibration and Performance Study of the Polarcube 3u Temperature Sounding Radiometer Mission

    Science.gov (United States)

    Periasamy, L.; Gasiewski, A. J.; Sanders, B. T.; Rouw, C.; Alvarenga, G.; Gallaher, D. W.

    2016-12-01

    The positive impact of passive microwave observations of tropospheric temperature, water vapor and surface variables on short-term weather forecasts has been clearly demonstrated in recent forecast anomaly growth studies. The development of a fleet of such passive microwave sensors especially at V-band and higher frequencies in low earth orbit using 3U and 6U CubeSats could help accomplish the aforementioned objectives at low system cost and risk as well as provide for regularly updated radiometer technology. The University of Colorado's 3U CubeSat, PolarCube is intended to serve as a demonstrator for such a fleet of passive sounders and imagers. PolarCube supports MiniRad, an eight channel, double sideband 118.7503 GHz passive microwave sounder. The mission is focused primarily on sounding in Arctic and Antarctic regions with the following key remote sensing science and engineering objectives: (i) Collect coincident tropospheric temperature profiles above sea ice, open polar ocean, and partially open areas to develop joint sea ice concentration and lower tropospheric temperature mapping capabilities in clear and cloudy atmospheric conditions. This goal will be accomplished in conjunction with data from existing passive microwave sensors operating at complementary bands; and (ii) Assess the capabilities of small passive microwave satellite sensors for environmental monitoring in support of the future development of inexpensive Earth science missions. Performance data of the payload/spacecraft from pre-launch calibration will be presented. This will include- (i) characterization of the antenna sub-system comprising of an offset 3D printed feedhorn and spinning parabolic reflector and impact of the antenna efficiencies on radiometer performance, (ii) characterization of MiniRad's RF front-end and IF back-end with respect to temperature fluctuations and their impact on atmospheric temperature weighting functions and receiver sensitivity, (iii) results from roof

  10. The Boundary Layer Radiometer

    Science.gov (United States)

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

    2010-10-01

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

  11. Juno Microwave Radiometer Patch Array Antennas

    Science.gov (United States)

    Chamberlain, N.; Chen, J.; Focardi, P.; Hodges, R.; Hughes, R.; Jakoboski, J.; Venkatesan, J.; Zawadzki, M.

    2009-01-01

    Juno is a mission in the NASA New Frontiers Program with the goal of significantly improving our understanding of the formation and structure of Jupiter. This paper discusses the modeling and measurement of the two patch array antennas. An overview of the antenna architecture, design and development at JPL is provided, along with estimates of performance and the results of measurements.

  12. The DMRT-ML Model: Numerical Simulations of the Microwave Emission of Snowpacks Based on the Dense Media Radiative Transfer Theory

    Science.gov (United States)

    Brucker, Ludovic; Picard, Ghislain; Roy, Alexandre; Dupont, Florent; Fily, Michel; Royer, Alain

    2014-01-01

    Microwave radiometer observations have been used to retrieve snow depth and snow water equivalent on both land and sea ice, snow accumulation on ice sheets, melt events, snow temperature, and snow grain size. Modeling the microwave emission from snow and ice physical properties is crucial to improve the quality of these retrievals. It also is crucial to improve our understanding of the radiative transfer processes within the snow cover, and the snow properties most relevant in microwave remote sensing. Our objective is to present a recent microwave emission model and its validation. The model is named DMRT-ML (DMRT Multi-Layer), and is available at http:lgge.osug.frpicarddmrtml.

  13. Measurements on Active Cold Loads for Radiometer Calibration

    DEFF Research Database (Denmark)

    Skou, Niels; Søbjærg, Sten Schmidl; Balling, Jan E.

    2008-01-01

    Two semi-conductor Active Cold Loads (ACLs) to be used as cold references in spaceborne microwave radiometers have been developed. An X-band frequency was chosen, and the target noise temperature value was in the 50 to 100 K range. The ACLs are characterized in the operating temperature range 0 50...

  14. Measurements on Active Cold Loads for Radiometer Calibration

    DEFF Research Database (Denmark)

    Søbjærg, Sten Schmidl; Skou, Niels; Balling, Jan E.

    2009-01-01

    Two semiconductor active cold loads (ACLs) to be used as cold references in spaceborne microwave radiometers have been developed. An X-band frequency was chosen, and the target noise temperature value was in the 50-100-K range. The ACLs are characterized in the operating temperature range of 0deg...

  15. Performance Measurements on Active Cold Loads for Radiometer Calibration

    DEFF Research Database (Denmark)

    Skou, Niels; Søbjærg, Sten Schmidl; Balling, Jan E.

    2007-01-01

    Two semi-conductor Active Cold Loads (ACLs) to be used as cold references in spaceborne microwave radiometers have been developed. An X-band frequency has been chosen, and the target noise temperature value is in the 50 to 100 K range. The ACLs are to be characterized in the operating temperature...

  16. Measurement of small antenna reflector losses for radiometer calibration budget

    DEFF Research Database (Denmark)

    Skou, Niels

    1997-01-01

    Antenna reflector losses play an important role in the calibration budget for a microwave radiometer. If the losses are small, they are difficult to measure by traditional means. However, they can be assessed directly by radiometric means using the sky brightness temperature as incident radiation...

  17. Observation of bubble formation in water during microwave irradiation by dynamic light scattering

    Science.gov (United States)

    Asakuma, Yusuke; Munenaga, Takuya; Nakata, Ryosuke

    2016-09-01

    A microwave reactor was designed for in situ observation of nano- and micro-bubbles, and size profiles during and after irradiation were measured with respect to irradiation power and time. Bubble formation in water during irradiation was observed even at temperatures below the boiling point of water. The maximum size strongly depended on radiation power and time, even at a given temperature. Nano-particles in the dispersion medium were found to play an important role in achieving more stable nucleation of bubbles around particles, and stable size distributions were obtained from clear autocorrelation by a dynamic light scattering system. Moreover, a combination of microwave induction heating and the addition of nano-particles to the dispersion medium can prevent heterogeneous nucleation of bubbles on the cell wall. Quantitative nano-bubble size profiles obtained by in situ observation provide useful information regarding microwave-based industrial processes for nano-particle production.

  18. Dynamic Characterization of a Low Cost Microwave Water-Cut Sensor in a Flow Loop

    KAUST Repository

    Karimi, Muhammad Akram

    2017-03-31

    Inline precise measurement of water fraction in oil (i.e. water-cut [WC]) finds numerous applications in oil and gas industry. This paper presents the characterization of an extremely low cost, completely non-intrusive and full range microwave water-cut sensor based upon pipe conformable microwave T-resonator. A 10″ microwave stub based T-resonator has been implemented directly on the pipe surface whose resonance frequency changes in the frequency band of 90MHz–190MHz (111%) with changing water fraction in oil. The designed sensor is capable of detecting even small changes in WC with a resolution of 0.07% at low WC and 0.5% WC at high WC. The performance of the microwave WC sensor has been tested in an in-house flow loop. The proposed WC sensor has been characterized over full water-cut range (0%–100%) not only in vertical but also in horizontal orientation. The sensor has shown predictable response in both orientations with huge frequency shift. Moreover, flow rate effect has also been investigated on the proposed WC sensor’s performance and it has been found that the sensor’s repeatability is within 2.5% WC for variable flow rates.

  19. Electron Cyclotron Emission Radiometer

    Science.gov (United States)

    Morales, Cristina

    2009-11-01

    There is much interest in studying plasmas that generate hot electrons. The goal of this project is to develop a wide band electron cyclotron radiometer to measure the non-Maxwellian rapid rises in electron temperature. These rapid increases in temperature will then be correlated to instabilities in the plasma. This project explores a type of noncontact temperature measurement. We will attempt to show the feasibility of electron cyclotron emissions to measure the Maryland Centrifugal Experiment's electron plasma temperature. The radiometer has been designed to have 100dB of gain and a sensitivity of 24mV/dB given by its logarithmic amplifier. If successful, this radiometer will be used as a diagnostic tool in later projects such as the proposed experiment studying magnetic reconnection using solar flux loops.

  20. High-Altitude MMIC Sounding Radiometer for the Global Hawk Unmanned Aerial Vehicle

    Science.gov (United States)

    Brown, Shannon T.; Lim, Boon H.; Tanner, Alan B.; Tanabe, Jordan M.; Kangaslahti, Pekka P.; Gaier, Todd C.; Soria, Mary M.; Lambrigtsen, Bjorn H.; Denning, Richard F.; Stachnik, Robert A.

    2012-01-01

    Microwave imaging radiometers operating in the 50-183 GHz range for retrieving atmospheric temperature and water vapor profiles from airborne platforms have been limited in the spatial scales of atmospheric structures that are resolved not because of antenna aperture size, but because of high receiver noise masking the small variations that occur on small spatial scales. Atmospheric variability on short spatial and temporal scales (second/ km scale) is completely unresolved by existing microwave profilers. The solution was to integrate JPL-designed, high-frequency, low-noise-amplifier (LNA) technology into the High-Altitude MMIC Sounding Radiometer (HAMSR), which is an airborne microwave sounding radiometer, to lower the system noise by an order of magnitude to enable the instrument to resolve atmospheric variability on small spatial and temporal scales. HAMSR has eight sounding channels near the 60-GHz oxygen line complex, ten channels near the 118.75-GHz oxygen line, and seven channels near the 183.31-GHz water vapor line. The HAMSR receiver system consists of three heterodyne spectrometers covering the three bands. The antenna system consists of two back-to-back reflectors that rotate together at a programmable scan rate via a stepper motor. A single full rotation includes the swath below the aircraft followed by observations of ambient (roughly 0 C in flight) and heated (70 C) blackbody calibration targets located at the top of the rotation. A field-programmable gate array (FPGA) is used to read the digitized radiometer counts and receive the reflector position from the scan motor encoder, which are then sent to a microprocessor and packed into data files. The microprocessor additionally reads telemetry data from 40 onboard housekeeping channels (containing instrument temperatures), and receives packets from an onboard navigation unit, which provides GPS time and position as well as independent attitude information (e.g., heading, roll, pitch, and yaw). The raw

  1. Calibration of Correlation Radiometers Using Pseudo-Random Noise Signals

    Directory of Open Access Journals (Sweden)

    Sebastián Pantoja

    2009-08-01

    Full Text Available The calibration of correlation radiometers, and particularly aperture synthesis interferometric radiometers, is a critical issue to ensure their performance. Current calibration techniques are based on the measurement of the cross-correlation of receivers’ outputs when injecting noise from a common noise source requiring a very stable distribution network. For large interferometric radiometers this centralized noise injection approach is very complex from the point of view of mass, volume and phase/amplitude equalization. Distributed noise injection techniques have been proposed as a feasible alternative, but are unable to correct for the so-called “baseline errors” associated with the particular pair of receivers forming the baseline. In this work it is proposed the use of centralized Pseudo-Random Noise (PRN signals to calibrate correlation radiometers. PRNs are sequences of symbols with a long repetition period that have a flat spectrum over a bandwidth which is determined by the symbol rate. Since their spectrum resembles that of thermal noise, they can be used to calibrate correlation radiometers. At the same time, since these sequences are deterministic, new calibration schemes can be envisaged, such as the correlation of each receiver’s output with a baseband local replica of the PRN sequence, as well as new distribution schemes of calibration signals. This work analyzes the general requirements and performance of using PRN sequences for the calibration of microwave correlation radiometers, and particularizes the study to a potential implementation in a large aperture synthesis radiometer using an optical distribution network.

  2. A Multifrequency Radiometer System

    DEFF Research Database (Denmark)

    Skou, Niels

    1977-01-01

    A radiometer system having four channels: 5 GHz, l7 GHz, 34 GHz, all vertical polarization, and a 34 GHz sky horn, will be described. The system which is designed for collecting glaciological and oceanographic data is intended for airborne use and imaging is achieved by means of a multifrequency ...... elaborate processing later, using ground facilities. In conjunction with a side looking radar which is under development at present, the radiometers are intended as the remote sensing basis for an all-weather ice reconnaissance service in the Greenland seas....

  3. Measurement errors with low-cost citizen science radiometers

    OpenAIRE

    Bardají, Raúl; Piera, Jaume

    2016-01-01

    The KdUINO is a Do-It-Yourself buoy with low-cost radiometers that measure a parameter related to water transparency, the diffuse attenuation coefficient integrated into all the photosynthetically active radiation. In this contribution, we analyze the measurement errors of a novel low-cost multispectral radiometer that is used with the KdUINO. Peer Reviewed

  4. In-situ calibration of the water vapor channel for multi-filter rotating shadowband radiometer using collocated GPS, AERONET and meteorology data

    Science.gov (United States)

    Chen, Maosi; Zempila, Melina-Maria; Davis, John M.; King, Robert W.; Gao, Wei

    2016-09-01

    The difficulty of in-situ calibration on the 940 nm channel of Multi-Filter Rotating Shadowband Radiometer (MFRSR) stems from the distinctive non-linear relationship between the amount of precipitable water vapor (PW) and its optical depth (i.e. curve of growth) compared to the counterpart of aerosols. Previous approaches, the modified Langley methods (MLM), require exact aerosol optical depth (AOD) values and a constant PW value at all points participating the regression. Instead, we propose a new method that substitutes the PW optical depth derived from collocated GPS zenith wet delay retrieval in conjunction with meteorology data and requires a constant AOD value at all points participating the regression. The main benefits of the new method include: (1) Aerosol stability is easier to fulfill than PW stability; (2) AOD stability could be inferred from adjacent channels (e.g. 672 and 870 nm) of MFRSR itself without measurements of a collocated AERONET sun photometer; and (3) When applicable, the time interval of GPS derived PW (i.e. 3 minutes) is more compatible with the MFRSR sampling interval (i.e. 3 minutes) than AERONET interpolated AOD (i.e. 15 minutes). Both MLM and the new method were applied to the MFRSR of USDA UV-B Monitoring and Research Program at the station in Billings, Oklahoma (active for 18 years so far) on July 28, 2015. The performances of the two methods are compared in order to assess their accuracy and the advantages and disadvantages.

  5. Effect of methanol on the liquefaction reaction of biomass in hot compressed water under microwave energy

    Science.gov (United States)

    Junming Xu; Jianchun Jiang; Chun-Yun Hse; Todd F. Shupe

    2013-01-01

    Liquefaction of sawdust was studied in methanol-water solutions using an acid catalyst under microwave energy. The effect of the methanol concentration on the changes of components in the liquefied products was analyzed by gas chromatography−mass spectrometry (GC−MS). It was found that 5-hydroxymethylfurfural (HMF) and levulinic acid are the...

  6. Migration of bisphenol A into water from polycarbonate baby bottles during microwave heating

    NARCIS (Netherlands)

    Ehlert, K.A.; Beumer, C.W.E.; Groot, M.C.E.

    2008-01-01

    A comprehensive migration database was established for bisphenol A from polycarbonate baby bottles into water during exposure to microwave heating. Eighteen different brands of polycarbonate baby bottles sold in Europe were collected. Initial residual content of bisphenol A and migration after micro

  7. Migration of bisphenol A into water from polycarbonate baby bottles during microwave heating

    NARCIS (Netherlands)

    Ehlert, K.A.; Beumer, C.W.E.; Groot, M.C.E.

    2008-01-01

    A comprehensive migration database was established for bisphenol A from polycarbonate baby bottles into water during exposure to microwave heating. Eighteen different brands of polycarbonate baby bottles sold in Europe were collected. Initial residual content of bisphenol A and migration after

  8. Enhancement of solubility and dissolution rate of poorly water soluble raloxifene using microwave induced fusion method

    OpenAIRE

    Payal Hasmukhlal Patil; Veena Sailendra Belgamwar; Pratibha Ramratan Patil; Sanjay Javerilal Surana

    2013-01-01

    The objective of the present work was to enhance the solubility and dissolution rate of the drug raloxifene HCl (RLX), which is poorly soluble in water. The solubility of RLX was observed to increase with increasing concentration of hydroxypropyl methylcellulose (HPMC E5 LV). The optimized ratio for preparing a solid dispersion (SD) of RLX with HPMC E5 LV using the microwave-induced fusion method was 1:5 w/w. Microwave energy was used to prepare SDs. HPMC E5 LV was used as a hydrophilic carri...

  9. Statistical Topics Concerning Radiometer Theory

    CERN Document Server

    Hunter, Todd R

    2015-01-01

    We present a derivation of the radiometer equation based on the original references and fundamental statistical concepts. We then perform numerical simulations of white noise to illustrate the radiometer equation in action. Finally, we generate 1/f and 1/f^2 noise, demonstrate that it is non-stationary, and use it to simulate the effect of gain fluctuations on radiometer performance.

  10. Effect of Microwave Heating on Potato and Tapioca Starches in Water Suspension

    Directory of Open Access Journals (Sweden)

    Nurul Nadiah Ismail

    2016-01-01

    Full Text Available Abstract— The effects of microwave heating on properties of starch were studied on potato and tapioca starches in water suspension at different temperature (50°C and 60°C. Potato and tapioca starches were adjusted to 30% (w/v and heat-moisture treated in a microwave oven and conventional heating.Conventional heating was carried out by direct heating the moisture heated sample at 50ºC and 60ºC while the microwave heating was carried out by microwave oven and the temperature was controlled approximately to 50ºC and 60ºC. The heated starch samples were analyzed for amylose content, pasting properties, swelling and solubility, thermal properties, light microscopy, scanning electron microscopy (SEM and X-ray diffraction. There were present several changes on physicochemical and functional properties of heated starch for both heating methods. However, microwave method gave higher affect on heating treatment rather than conventional heating. Microwave heating was evidenced in affecting pasting properties of potato and tapioca starches by increase the pasting temperature and the paste stability. Microwave heating also significantly increased the amylose content and swelling power but reduced the solubility and enthalpy of gelatinization (ΔH of those starches. There were changes in granule structure of starch observed by loss of birefringence and ruptures granule in SEM micrographs in both heating treatment. A change in the X-ray diffraction pattern from B-type to A-type was occurred in potato starch but tapioca starch shows no changes in X-ray pattern.  

  11. Effect of Microwave Heating on Potato and Tapioca Starches in Water Suspension

    Directory of Open Access Journals (Sweden)

    Nurul Nadiah binti Ismail

    2015-04-01

    Full Text Available The effects of microwave heating on properties of starch were studied on potato and tapioca starches in water suspension at different temperature (50°C and 60°C. Potato and tapioca starches were adjusted to 30% (w/v and heat-moisture treated in a microwave oven and conventional heating.Conventional heating was carried out by direct heating the moisture heated sample at 50oC and 60oC while the microwave heating was carried out by microwave oven and the temperature was controlled approximately to 50oC and 60oC. The heated starch samples were analyzed for amylose content, pasting properties, swelling and solubility, thermal properties, light microscopy, scanning electron microscopy (SEM and X-ray diffraction. There were present several changes on physicochemical and functional properties of heated starch for both heating methods. However, microwave method gave higher affect on heating treatment rather than conventional heating. Microwave heating was evidenced in affecting pasting properties of potato and tapioca starches by increase the pasting temperature and the paste stability. Microwave heating also significantly increased the amylose content and swelling power but reduced the solubility and enthalpy of gelatinization (ΔH of those starches. There were changes in granule structure of starch observed by loss of birefringence and ruptures granule in SEM micrographs in both heating treatment. A change in the X-ray diffraction pattern from B-type to A-type was occurred in potato starch but tapioca starch shows no changes in X-ray pattern.

  12. Monitoring System for Atmospheric Water Vapor with a Ground-Based Multi-Band Radiometer: Meteorological Application of Radio Astronomy Technologies

    Science.gov (United States)

    Nagasaki, T.; Araki, K.; Ishimoto, H.; Kominami, K.; Tajima, O.

    2016-08-01

    High-resolution estimation of thermodynamic properties in the atmosphere can help to predict and mitigate meteorological disasters, such as local heavy rainfall and tornadic storms. For the purposes of short-term forecasting and nowcasting of severe storms, we propose a novel ground-based measurement system, which observes the intensity of atmospheric radiation in the microwave range. Our multi-band receiver system is designed to identify a rapid increase in water vapor before clouds are generated. At frequencies between 20 and 30 GHz, our system simultaneously measures water vapor as a broad absorption peak at 22 GHz as well as cloud liquid water. Another band at 50-60 GHz provides supplementary information from oxygen radiation to give vertical profiles of physical temperature. For the construction of this cold receiver system, novel technologies originally developed for observations of cosmic microwave background radiation were applied. The input atmospheric signal is amplified by a cold low-noise amplifier maintained below 10 K, while the spectrum of this amplified signal is measured using a signal analyzer under ambient conditions. The cryostat also contains a cold black body at 40 K to act as a calibration signal. This calibration signal is transported to each of the receivers via a wire grid. We can select either the atmospheric signal or the calibration signal by changing the orientation of this wire. Each receiver can be calibrated using this setup. Our system is designed to be compact (<1 m3), with low power consumption (˜ 1.5 kW). Therefore, it is easy to deploy on top of high buildings, mountains, and ship decks.

  13. Multi-Decadal Variability of Polynya Characteristics and Ice Production in the North Water Polynya by Means of Passive Microwave and Thermal Infrared Satellite Imagery

    Directory of Open Access Journals (Sweden)

    Andreas Preußer

    2015-11-01

    Full Text Available The North Water (NOW Polynya is a regularly-forming area of open-water and thin-ice, located between northwestern Greenland and Ellesmere Island (Canada at the northern tip of Baffin Bay. Due to its large spatial extent, it is of high importance for a variety of physical and biological processes, especially in wintertime. Here, we present a long-term remote sensing study for the winter seasons 1978/1979 to 2014/2015. Polynya characteristics are inferred from (1 sea ice concentrations and brightness temperatures from passive microwave satellite sensors (Advanced Microwave Scanning Radiometer (AMSR-E and AMSR2, Scanning Multichannel Microwave Radiometer (SMMR, Special Sensor Microwave Imager/Sounder (SSM/I-SSMIS and (2 thin-ice thickness distributions, which are calculated using MODIS ice-surface temperatures and European Center for Medium-Range Weather Forecasts (ECMWF atmospheric reanalysis data in a 1D thermodynamic energy-balance model. Daily ice production rates are retrieved for each winter season from 2002/2003 to 2014/2015, assuming that all heat loss at the ice surface is balanced by ice growth. Two different cloud-cover correction schemes are applied on daily polynya area and ice production values to account for cloud gaps in the MODIS composites. Our results indicate that the NOW polynya experienced significant seasonal changes over the last three decades considering the overall frequency of polynya occurrences, as well as their spatial extent. In the 1980s, there were prolonged periods of a more or less closed ice cover in northern Baffin Bay in winter. This changed towards an average opening on more than 85% of the days between November and March during the last decade. Noticeably, the sea ice cover in the NOW polynya region shows signs of a later-appearing fall freeze-up, starting in the late 1990s. Different methods to obtain daily polynya area using passive microwave AMSR-E/AMSR2 data and SSM/I-SSMIS data were applied. A comparison

  14. Enhancement of solubility and dissolution rate of poorly water soluble raloxifene using microwave induced fusion method

    Directory of Open Access Journals (Sweden)

    Payal Hasmukhlal Patil

    2013-09-01

    Full Text Available The objective of the present work was to enhance the solubility and dissolution rate of the drug raloxifene HCl (RLX, which is poorly soluble in water. The solubility of RLX was observed to increase with increasing concentration of hydroxypropyl methylcellulose (HPMC E5 LV. The optimized ratio for preparing a solid dispersion (SD of RLX with HPMC E5 LV using the microwave-induced fusion method was 1:5 w/w. Microwave energy was used to prepare SDs. HPMC E5 LV was used as a hydrophilic carrier to enhance the solubility and dissolution rate of RLX. After microwave treatment, the drug and hydrophilic polymer are fused together, and the drug is converted from the crystalline form into an amorphous form. This was confirmed through scanning electron microscopy (SEM, differential scanning calorimetry (DSC and powder X-ray diffraction (PXRD studies. These results suggested that the microwave method is a simple and efficient method of preparing SDs. The solubility and dissolution rate of the SDs were increased significantly compared with pure RLX due to the surfactant and wetting properties of HPMC E5 LV and the formation of molecular dispersions of the drug in HPMC E5 LV. It was concluded that the solubility and dissolution rate of RLX are increased significantly when an SD of the drug is prepared using the microwave-induced fusion method.

  15. Microwave-assisted synthesis of α-hydroxy aromatic ketones from α-bromo aromatic ketones in water

    Institute of Scientific and Technical Information of China (English)

    Xiang Liu; Hai Bo Chen; Zheng Guang Pan; Jian He Xu; He Xing Li

    2011-01-01

    A reaction of α-bromo aromatic ketones in water with microwave irradiation gave the corresponding α-hydroxy aromatic ketones in good yields.The use of microwaves was found to significantly improve yields and shorten the reaction time.This reaction afforded a very clean,convenient method for the synthesis of α-hydroxy aromatic ketones.

  16. Enhanced heating of salty ice and water under microwaves: molecular dynamics study.

    Science.gov (United States)

    Tanaka, Motohiko; Sato, Motoyasu

    2008-01-01

    Through the use of molecular dynamics simulations, we have studied the enhanced heating of salty ice and water by the electric field of applied microwaves at 2.5 GHz, and in the range of 2.5-10 GHz for the frequency dependence. We show that water molecules in salty ice are allowed to rotate in response to the microwave electric field to the extent comparable to those in pure water because the molecules in salty ice are loosely tied by hydrogen bonds with adjacent molecules unlike rigidly bonded pure ice. The weakening of hydrogen-bonded network of molecules in salty ice is mainly due to the electrostatic effect of salt ions rather than the short-range geometrical (size) effect of salt since the presence of salt ions with small radii causes similar enhanced heating.

  17. Extraction of Water from Polar Lunar Permafrost with Microwaves - Dielectric Property Measurements

    Science.gov (United States)

    Ethridge, Edwin C.; Kaukler, William

    2009-01-01

    Remote sensing indicates the presence of hydrogen rich regions associated with the lunar poles. The logical hypothesis is that there is cryogenically trapped water ice located in craters at the lunar poles. Some of the craters have been in permanent darkness for a billion years. The presence of water at the poles as well as other scientific advantages of a polar base, have influenced NASA plans for the lunar outpost. The lunar outpost has water and oxygen requirements on the order of 1 ton per year scaling up to as much as 10 tons per year. Microwave heating of the frozen permafrost has unique advantages for water extraction. Proof of principle experiments have successfully demonstrated that microwaves will couple to the cryogenic soil in a vacuum and the sublimed water vapor can be successfully captured on a cold trap. The dielectric properties of lunar soil will determine the hardware requirements for extraction processes. Microwave frequency dielectric property measurements of lunar soil simulant have been measured.

  18. The effect of microwave power and heating time pretreatment on biogas production from fresh and dried water hyacinth (Eichhornia crassipes)

    Science.gov (United States)

    Sumardiono, Siswo; Budiyono, Mardiani, Dini Tri

    2015-12-01

    The objective of this research was to study the effect of microwave pretreatment of fresh and dried water hyacinth on biogas production. The variations of microwave power levels are 240; 400; 560 and 800 W. The variations of microwave heating time are 5; 7 and 9 min. The unpretreated fresh and dried water hyacinth are used as control. The result of research showed that almost all pretreated water hyacinth produced biogas were higher compare tounpretreated water hyacinth. The maximum of biogas production from fresh and dried water hyacinthwere obtained at 560 W for 7 min and 400 W for 7 min of microwave pretreatment. In this condition, pretreated fresh and dried water hyacinth resulted biogas production of 75,12 and 53,06 mL/g TS, respectively. The unpretreated fresh and dried water hyacinth produced biogas of 37,56 and 33,56 mL/g TS, respectively. The microwave pretreatment of water hyacinth improved biogas production. Microwave pretreatment had a positive impact on anaerobic biodegradability of water hyacinth.

  19. Microwave-assisted headspace single-drop microextration of chlorobenzenes from water samples.

    Science.gov (United States)

    Vidal, Lorena; Domini, Claudia E; Grané, Nuria; Psillakis, Elefteria; Canals, Antonio

    2007-05-29

    A one-step and in-situ sample preparation method used for quantifying chlorobenzene compounds in water samples has been developed, coupling microwave and headspace single-drop microextraction (MW-HS-SDME). The chlorobenzenes in water samples were extracted directly onto an ionic liquid single-drop in headspace mode under the aid of microwave radiation. For optimization, a Plackett-Burman screening design was initially used, followed by a mixed-level factorial design. The factors considered were: drop volume, aqueous sample volume, stirring speed, ionic strength, extraction time, ionic liquid type, microwave power and length of the Y-shaped glass-tube. The optimum experimental conditions found from this statistical evaluation were: a 5 microL microdrop of 1-hexyl-3-methylimidazolium hexafluorophosphate exposed for 20 min to the headspace of a 30 mL aqueous sample, irradiated by microwaves at 200 W and placed in a 50 mL spherical flask connected to a 25 cm Y-shaped glass-tube. Under the optimised experimental conditions, the response of a high performance liquid chromatographic system was found to be linear over the range studied and with correlation coefficients ranging between 0.9995 and 0.9999. The method showed a good level of repeatability, with relative standard deviations varying between 2.3 and 8.3% (n=5). Detection limits were found in the low microg L(-1) range varying between 0.016 and 0.039 microg L(-1). Overall, the performance of the proposed method demonstrated the favourable effect of microwave sample irradiation upon HS-SDME. Finally, recovery studies from different types of environmental water samples revealed that matrix had little effect upon extraction.

  20. Microwave-assisted headspace single-drop microextration of chlorobenzenes from water samples

    Energy Technology Data Exchange (ETDEWEB)

    Vidal, Lorena [Departamento de Quimica Analitica, Nutricion y Bromatologia, Universidad de Alicante, P.O. Box 99, E-03080 Alicante (Spain); Domini, Claudia E. [Departamento de Quimica Analitica, Nutricion y Bromatologia, Universidad de Alicante, P.O. Box 99, E-03080 Alicante (Spain); Grane, Nuria [Departamento de Quimica Analitica, Nutricion y Bromatologia, Universidad de Alicante, P.O. Box 99, E-03080 Alicante (Spain); Psillakis, Elefteria [Department of Environmental Engineering, Technical University of Crete, Polytechneioupolis, GR-73100 Chania, Crete (Greece); Canals, Antonio [Departamento de Quimica Analitica, Nutricion y Bromatologia, Universidad de Alicante, P.O. Box 99, E-03080 Alicante (Spain)]. E-mail: a.canals@ua.es

    2007-05-29

    A one-step and in-situ sample preparation method used for quantifying chlorobenzene compounds in water samples has been developed, coupling microwave and headspace single-drop microextraction (MW-HS-SDME). The chlorobenzenes in water samples were extracted directly onto an ionic liquid single-drop in headspace mode under the aid of microwave radiation. For optimization, a Plackett-Burman screening design was initially used, followed by a mixed-level factorial design. The factors considered were: drop volume, aqueous sample volume, stirring speed, ionic strength, extraction time, ionic liquid type, microwave power and length of the Y-shaped glass-tube. The optimum experimental conditions found from this statistical evaluation were: a 5 {mu}L microdrop of 1-hexyl-3-methylimidazolium hexafluorophosphate exposed for 20 min to the headspace of a 30 mL aqueous sample, irradiated by microwaves at 200 W and placed in a 50 mL spherical flask connected to a 25 cm Y-shaped glass-tube. Under the optimised experimental conditions, the response of a high performance liquid chromatographic system was found to be linear over the range studied and with correlation coefficients ranging between 0.9995 and 0.9999. The method showed a good level of repeatability, with relative standard deviations varying between 2.3 and 8.3% (n = 5). Detection limits were found in the low {mu}g L{sup -1} range varying between 0.016 and 0.039 {mu}g L{sup -1}. Overall, the performance of the proposed method demonstrated the favourable effect of microwave sample irradiation upon HS-SDME. Finally, recovery studies from different types of environmental water samples revealed that matrix had little effect upon extraction.

  1. A New Generation of Micro Satellite Radiometers for Atmospheric Remote Sensing

    Science.gov (United States)

    He, jieying

    2017-04-01

    The need for low-cost, mission-flexible, and rapidly deployable space borne sensors that meet stringent performance requirements pervades the extreme weather monitoring programs, including especially the strong rainfall and typhoon. New technologies have enabled a novel approach toward this science observational goal, and in this paper we describe recent technology develop efforts to address the challenges above through the use of radiometers on a Micro-sized Microwave Atmospheric Satellite (Microsat), which operates in the type of constellation, and enable the capabilities of rapidly progressing. Recent work has involved the design and development of highly integrated radiometer component technologies that would enable the realization of a high-performance, multi-band sounder that would conform to the 3U CubeSat size (10 x 10 x 30 cm), weight, and power requirements. This paper partly focuses on the constellation to realize a scalable CubeSat-based system that will pave the path towards improved revisit rates over critical earth regions, and achieve state-of-the-art performance relative to current systems with respect to spatial, spectral, and radiometric resolution. As one of the important payloads on the platform, sub-millimeter radiometer is advised to house for providing atmospheric and oceanographic information all weather and all day. The first portion of the radiometer comprises a horn-fed reflector antenna, with a full-width at half-maximum (FWHM) beamwidth of 1.2°. Hence, the scanned beam has an approximate footprint diameter of 9.6 km at nadir incidence from a nominal altitude of 500 km. The antenna system is designed for a minimum 95% beam efficiency. Approximately 98 pixels are sampled for every scanning line, which covers a range of 1500km. The period of a round is about 94.47 minutes and re-visit period is four days. For the radiometer, which is a passive cross-track-scanning microwave spectrometer operating near the 118.75-GHz oxygen absorption

  2. Rapid Microwave-promoted Base-free Suzuki Coupling Reaction of Sodium Tetraphenylborate with Hypervalent Iodonium Salts in Water

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The palladium chloride-catalyzed Suzuki coupling reaction of sodium tetraphenylborate with hypervalent iodonium salts was achieved under microwave irradiation in water without base in excellent yield. A convenient and rapidmethod for formation of carbon-carbon bonds was afforded.

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

    Science.gov (United States)

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

    2000-01-01

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

  4. Characterization of a Digital Microwave Radiometry System for Noninvasive Thermometry using Temperature Controlled Homogeneous Test Load

    Science.gov (United States)

    Arunachalam, K; Stauffer, P R; Maccarini, PF; Jacobsen, S; Sterzer, F

    2009-01-01

    Microwave radiometry has been proposed as a viable noninvasive thermometry approach for monitoring subsurface tissue temperatures and potentially controlling power levels of multielement heat applicators during clinical hyperthermia treatments. With the evolution of technology, several analog microwave radiometry devices have been developed for biomedical applications. In this paper, we describe a digital microwave radiometer with built-in electronics for signal processing and automatic self-calibration. Performance of the radiometer with an Archimedean spiral receive antenna is evaluated over a bandwidth of 3.7–4.2GHz in homogeneous and layered water test loads. Controlled laboratory experiments over the range of 30–50°C characterize measurement accuracy, stability, repeatability and penetration depth sensitivity. The ability to sense load temperature through an intervening water coupling bolus of 6mm thickness is also investigated. To assess clinical utility and sensitivity to electromagnetic interference (EMI), experiments are conducted inside standard clinical hyperthermia treatment rooms with no EM shielding. The digital radiometer provided repeatable measurements with 0.075°C resolution and standard deviation of 0.217°C for homogeneous and layered tissue loads at temperatures between 32–45°C. Within the 3.7–4.2GHz band, EM noise rejection was good other than some interference from overhead fluorescent lights in the same room as the radiometer. The system response obtained for ideal water loads suggests that this digital radiometer should be useful for estimating subcutaneous tissue temperatures under a 6mm waterbolus used during clinical hyperthermia treatments. The accuracy and stability data obtained in water test loads of several configurations support our expectation that single band radiometry should be sufficient for sub-surface temperature monitoring and power control of large multielement array superficial hyperthermia applicators. PMID

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

    Science.gov (United States)

    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

  6. Influence of wet activation of used inorganic binder on cyclically refreshed water glass moulding sands hardened by microwaves

    OpenAIRE

    Mateusz Stachowicz; Kazimierz Granat

    2016-01-01

    The paper presents the research results of using an innovative method to reclaim the waste moulding sands containing water glass. Two of the examined processes are connected with "dry" or "wet" activation of inorganic binder in waste moulding sand mixtures physically hardened by microwave radiation. The sand mixtures consisting of high-silica sand and water-glass with average molar module 2.5, were subjected to the following cyclical process: mixing the components, compacting, microwave heati...

  7. Soil moisture, dielectric permittivity and emissivity of soil: effective depth of emission measured by the L-band radiometer ELBARA

    Science.gov (United States)

    Usowicz, Boguslaw; Lukowski, Mateusz; Marczewski, Wojciech; Usowicz, Jerzy; Lipiec, Jerzy; Rojek, Edyta; Slominska, Ewa; Slominski, Jan

    2014-05-01

    Due to the large variation of soil moisture in space and in time, obtaining soil water balance with an aid of data acquired from the surface is still a challenge. Microwave remote sensing is widely used to determine the water content in soil. It is based on the fact that the dielectric constant of the soil is strongly dependent on its water content. This method provides the data in both local and global scales. Very important issue that is still not solved, is the soil depth at which radiometer "sees" the incoming radiation and how this "depth of view" depends on water content and physical properties of soil. The microwave emission comes from its entire profile, but much of this energy is absorbed by the upper layers of soil. As a result, the contribution of each layer to radiation visible for radiometer decreases with depth. The thickness of the surface layer, which significantly contributes to the energy measured by the radiometer is defined as the "penetration depth". In order to improve the physical base of the methodology of soil moisture measurements using microwave remote sensing and to determine the effective emission depth seen by the radiometer, a new algorithm was developed. This algorithm determines the reflectance coefficient from Fresnel equations, and, what is new, the complex dielectric constant of the soil, calculated from the Usowicz's statistical-physical model (S-PM) of dielectric permittivity and conductivity of soil. The model is expressed in terms of electrical resistance and capacity. The unit volume of soil in the model consists of solid, water and air, and is treated as a system made up of spheres, filling volume by overlapping layers. It was assumed that connections between layers and spheres in the layer are represented by serial and parallel connections of "resistors" and "capacitors". The emissivity of the soil surface is calculated from the ratio between the brightness temperature measured by the ELBARA radiometer (GAMMA Remote

  8. Portable Diagnostic Radiometer.

    Science.gov (United States)

    1985-07-01

    noise. The single-throw-double-pole switch is usually realized with an electronically- switched , latching ferrite circulator; however, at these...R2. Dl, D2 and R2 are then displayed on the liquid crystal display. The Q lines are next set to switch the latching switches into the 800 MHz...operation is basically as follows: On start- up, the CPU resets the Q line (P1-6) which sets the latching switches (see Fig. 18) to the 4 GHz radiometer

  9. 基于雨雪天气背景的微波辐射计斜路径与天顶观测的反演结果对比分析%Comparative analysis of the zenith and off-zenith retrieved results from microwave radiometer in rain and snow weather conditions

    Institute of Scientific and Technical Information of China (English)

    陈英英; 杨凡; 徐桂荣; 李德俊; 袁正腾; 熊洁

    2015-01-01

    In order to test the improvement of results in the off-zenith directions under rain and snow weather, the retrieved temperature, hu-midity, vapor density and liquid water density profiles from MP-3000A microwave radiometer (MWR) of the zenith and off-zenith observa-tions from 17 to 18 February 2014 are studied by comparing them with the Thies Clima laser precipitation monitor,L-band sounding data and precipitable water retrieved from GPS-MET from Wuhan station. Results are as follows. (1) If observed at off-zenith, the brightness tempera-ture signal saturation phenomenon at K and V bands can be eliminated effectively. Brightness temperature varies with rainfall intensity. (2) The correlation coefficient between the MWR product retrieved in off-zenith observation and sounding is better. (3) Although precipitable wa-ter vapor (PWV) retrieved in off-zenith observation is larger than the GPS/PWV, their trends are consistent. In contrast, there is a clear jump for the result in zenith observation after precipitation occurs. (4) There is a good corresponding relationship between the accumulation of cloud liquid water retrieved in off-zenith observation and the enhancement precipitation intensity.%为检验斜路径观测反演方法对雨雪天气背景下微波辐射计反演结果的改进,以2014年2月17-18日发生在武汉的一次雨雪过程为例,利用武汉观象台MP-3000A型微波辐射计天顶方向和斜路径观测反演的温度、相对湿度、水汽密度、液态水含量等廓线产品,分别与武汉观象台L波段探空资料,以及GPS-MET和Thies Clima激光雨滴谱仪的观测资料进行了对比检验.结果表明:(1)微波辐射计以斜路径方向观测,可以较好地消除K、V波段亮温信号饱和现象,亮温随降水强度的变化出现起伏波动的特征;(2)微波辐射计斜路径方向的反演产品与探空观测的相关性较好;(3)与GPS-MET观测的大气整层可降水量(PWV)比较,斜路径观测反演的PWV虽然

  10. Utilization of downscaled microwave satellite data and GRACE Total Water Storage anomalies for improving streamflow prediction in the Lower Mekong Basin

    Science.gov (United States)

    Lakshmi, V.; Gupta, M.; Bolten, J. D.

    2016-12-01

    The Mekong river is the world's eighth largest in discharge with draining an area of 795,000 km² from the Eastern watershed of the Tibetan Plateau to the Mekong Delta including, Myanmar, Laos PDR, Thailand, Cambodia, Vietnam and three provinces of China. The populations in these countries are highly dependent on the Mekong River and they are vulnerable to the availability and quality of the water resources within the Mekong River Basin. Soil moisture is one of the most important hydrological cycle variables and is available from passive microwave satellite sensors (such as AMSR-E, SMOS and SMAP), but their spatial resolution is frequently too coarse for effective use by land managers and decision makers. The merging of satellite observations with numerical models has led to improved land surface predictions. Although performance of the models have been continuously improving, the laboratory methods for determining key hydraulic parameters are time consuming and expensive. The present study assesses a method to determine the effective soil hydraulic parameters using a downscaled microwave remote sensing soil moisture product based on the NASA Advanced Microwave Scanning Radiometer (AMSR-E). The soil moisture downscaling algorithm is based on a regression relationship between 1-km MODIS land surface temperature and 1-km Moderate Resolution Imaging Spectroradiometer (MODIS) Normalized Difference Vegetation Index (NDVI) to produce an enhanced spatial resolution ASMR-E-based soil moisture product. Since the optimized parameters are based on the near surface soil moisture information, further constraints are applied during the numerical simulation through the assimilation of GRACE Total Water Storage (TWS) within the land surface model. This work improves the hydrological fluxes and the state variables are optimized and the optimal parameter values are then transferred for retrieving hydrological fluxes. To evaluate the performance of the system in helping improve

  11. Multimode near-field microwave monitoring of free water content of skin and imaging of tissue

    Energy Technology Data Exchange (ETDEWEB)

    Lofland, S E [Department of Physics and Astronomy, Rowan University, 201 Mullica Hill Road, Glassboro, NJ 08028 (United States); Mazzatenta, J D [Department of Physics and Astronomy, Rowan University, 201 Mullica Hill Road, Glassboro, NJ 08028 (United States); Croman, J [Department of Physics and Astronomy, Rowan University, 201 Mullica Hill Road, Glassboro, NJ 08028 (United States); Tyagi, S D [Department of Physics, Drexel University, 34th and Chestnut Sts., Philadelphia, PA 19104 (United States)

    2007-03-07

    We have used the near-field scanning microwave microscopy (NSMM) technique in the 1-10 GHz range to monitor the free water content of skin. The water content is interpreted from the measured dielectric properties of the epidermis. The finger skin was first hydrated by soaking in water at 37 {sup 0}C for 30 min followed by monitoring of water content as the free water evaporated under ambient conditions. The same technique has also been employed to image a 1 cm x 1 cm sample of chicken skin. It has been shown that variations exist in the resonant frequencies and quality factors of tissue under varying physical parameters. The samples analysed were as-received and thermally dehydrated or damaged chicken tissue samples. We contrast between the dielectric properties with the optical images. We also discuss possible application of our imaging technique in clinical monitoring of the wound healing process.

  12. RF Reference Switch for Spaceflight Radiometer Calibration

    Science.gov (United States)

    Knuble, Joseph

    2013-01-01

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

  13. Recent Progresses of Microwave Marine Remote Sensing

    Science.gov (United States)

    Yang, Jingsong; Ren, Lin; Zheng, Gang; Wang, He; He, Shuangyan; Wang, Juan; Li, Xiaohui

    2016-08-01

    It is presented in this paper the recent progresses of Dragon 3 Program (ID. 10412) in the field of microwave marine remote sensing including (1) ocean surface wind fields from full polarization synthetic aperture radars (SAR), (2) joint retrieval of directional ocean wave spectra from SAR and wave spectrometer, (3) error analysis on ENVISAT ASAR wave mode significant wave height (SWH) retrievals using triple collocation model, (4) typhoon observation from SAR and optical sensors, (5) ocean internal wave observation from SAR and optical sensors, (6) ocean eddy observation from SAR and optical sensors, (7) retrieval models of water vapor and wet tropospheric path delay for the HY-2A calibration microwave radiometer, (8) calibration of SWH from HY-2A satellite altimeter.

  14. Radio-frequency interference mitigating hyperspectral L-band radiometer

    Science.gov (United States)

    Toose, Peter; Roy, Alexandre; Solheim, Frederick; Derksen, Chris; Watts, Tom; Royer, Alain; Walker, Anne

    2017-02-01

    Radio-frequency interference (RFI) can significantly contaminate the measured radiometric signal of current spaceborne L-band passive microwave radiometers. These spaceborne radiometers operate within the protected passive remote sensing and radio-astronomy frequency allocation of 1400-1427 MHz but nonetheless are still subjected to frequent RFI intrusions. We present a unique surface-based and airborne hyperspectral 385 channel, dual polarization, L-band Fourier transform, RFI-detecting radiometer designed with a frequency range from 1400 through ≈ 1550 MHz. The extended frequency range was intended to increase the likelihood of detecting adjacent RFI-free channels to increase the signal, and therefore the thermal resolution, of the radiometer instrument. The external instrument calibration uses three targets (sky, ambient, and warm), and validation from independent stability measurements shows a mean absolute error (MAE) of 1.0 K for ambient and warm targets and 1.5 K for sky. A simple but effective RFI removal method which exploits the large number of frequency channels is also described. This method separates the desired thermal emission from RFI intrusions and was evaluated with synthetic microwave spectra generated using a Monte Carlo approach and validated with surface-based and airborne experimental measurements.

  15. Effects of water washing and torrefaction pretreatments on rice husk pyrolysis by microwave heating.

    Science.gov (United States)

    Zhang, Shuping; Dong, Qing; Zhang, Li; Xiong, Yuanquan; Liu, Xinzhi; Zhu, Shuguang

    2015-10-01

    The influences of water washing, torrefaction and combined water washing-torrefaction pretreatments on microwave pyrolysis of rice husk samples were investigated. The results indicated that the process of combined water washing-torrefaction pretreatment could effectively remove a large portion of inorganics and improve the fuel characteristics to a certain extent. The gas products were rich in combustible compositions and the syngas quality was improved by pretreatment process. The liquid products contained less moisture content, acids and furans, while more concentrated phenols and sugars from microwave pyrolysis of rice husk after pretreatments, especially after the combined water washing-torrefaction pretreatment. Biochar, produced in high yield, has the alkaline pH (pH 8.2-10.0) and high surface area (S(BET) 157.81-267.84 m(2)/g), they have the potential to be used as soil amendments. It is noteworthy that water washing increased the pore surface area of biochar, but torrefaction reduced the pore surface area.

  16. Lake surface water temperatures of European Alpine lakes (1989–2013 based on the Advanced Very High Resolution Radiometer (AVHRR 1 km data set

    Directory of Open Access Journals (Sweden)

    M. Riffler

    2014-05-01

    Full Text Available Lake water temperature (LWT is an important driver of lake ecosystems and it has been identified as an indicator of climate change. Thus, the Global Climate Observing System (GCOS lists LWT as an Essential Climate Variable (ECV. Although for some European lakes long in situ time series of LWT do exist, many lakes are not observed or only on a non-regular basis making these observations insufficient for climate monitoring. Satellite data can provide the information needed. However, only few satellite sensors offer the possibility to analyse time series which cover 25 years or more. The Advanced Very High Resolution Radiometer (AVHRR is among these and has been flown as a heritage instrument for almost 35 years. It will be carried on for at least ten more years finally offering a unique opportunity for satellite-based climate studies. Herein we present a satellite-based lake surface water temperature (LSWT data set for European (pre-alpine water bodies based on the extensive AVHRR 1 km data record (1989–2013 of the Remote Sensing Research Group at the University of Bern. It has been compiled out of AVHRR/2 (NOAA-07, -09, -11, -14 and AVHRR/3 (NOAA-16, -17, -18, -19 and Metop-A data. The high accuracy needed for climate related studies requires careful pre-processing and consideration of the atmospheric state. Especially data from NOAA-16 and prior satellites were prone to noise, e.g., due to transmission errors or fluctuations in the instrument's thermal state. This has resulted in partly corrupted thermal calibration data and may cause errors of up to several Kelvin in the final resulting LSWT. Thus, a multi-stage correction scheme has been applied to the data to minimize these artefacts. The LSWT retrieval is based on a simulation-based scheme making use of the Radiative Transfer for TOVS (RTTOV Version 10 together with operational analysis and reanalysis data from the European Centre for Medium Range Weather Forecasts. The resulting LSWTs

  17. Measurement of small antenna reflector losses for radiometer calibration budget

    OpenAIRE

    Skou, Niels

    1997-01-01

    Antenna reflector losses play an important role in the calibration budget for a microwave radiometer. If the losses are small, they are difficult to measure by traditional means. However, they can be assessed directly by radiometric means using the sky brightness temperature as incident radiation. This paper describes how such measurements are carried out as well as a suitable experimental setup. The main reflector of the European Space Agency's MIMR system is used to demonstrate the principle

  18. Accurate antenna reflector loss measurements for radiometer calibration budget

    DEFF Research Database (Denmark)

    Skou, Niels

    1996-01-01

    Antenna reflector losses may play an important role in the calibration budget for a microwave radiometer. If the losses are small they are difficult to measure by traditional means. However, they can be assessed directly by radiometric means using the sky brightness temperature as incident radiat...... radiation. The paper describes how such measurements are carried out as well as a suitable experimental set-up. The main reflector of the European Space Agency's MIMR system is used to demonstrate the principle...

  19. A General,Highly Efficient Ullmann C-O Coupling Reaction under Microwave Irradiation and the Effects of Water

    Institute of Scientific and Technical Information of China (English)

    ZHU,Xin-Hai; CHEN,Gong; MA,Yan; SONG,Hua-Can; XU,Zun-Le; WAN,Yi-Qian

    2007-01-01

    A general,rapid and highly efficient method for the synthesis of diaryl ethers under the assistance of microwave irradiation was described.A series of diaryl ethers were prepared by direct coupling of phenols and aryl halides in good to excellent yields in anhydrous DMF or NMP at 150℃ within 20 min.The presence of water was found to have a significant impact on the Ullmann C-O coupling reaction between aryl halides and phenols under microwave irradiation.

  20. Extended Special Sensor Microwave Imager (SSM/I) Temperature Data Record (TDR) in netCDF

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Special Sensor Microwave Imager (SSM/I) is a seven-channel linearly polarized passive microwave radiometer that operates at frequencies of 19.36 (vertically and...

  1. Extended Special Sensor Microwave Imager (SSM/I) Sensor Data Record (SDR) in netCDF

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Special Sensor Microwave Imager (SSM/I) is a seven-channel linearly polarized passive microwave radiometer that operates at frequencies of 19.36 (vertically and...

  2. Cloud Optical Properties from the Multifilter Shadowband Radiometer (MFRSRCLDOD). An ARM Value-Added Product

    Energy Technology Data Exchange (ETDEWEB)

    Turner, D. D. [DOE ARM Climate Research Facility, Washington, DC (United States); McFarlane, S. A. [DOE ARM Climate Research Facility, Washington, DC (United States); Riihimaki, L. [DOE ARM Climate Research Facility, Washington, DC (United States); Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Shi, Y. [DOE ARM Climate Research Facility, Washington, DC (United States); Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lo, C. [DOE ARM Climate Research Facility, Washington, DC (United States); Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Min, Q. [State University of New York, Albany; DOE ARM Climate Research Facility, Washington, DC (United States)

    2014-02-01

    The microphysical properties of clouds play an important role in studies of global climate change. Observations from satellites and surface-based systems have been used to infer cloud optical depth and effective radius. Min and Harrison (1996) developed an inversion method to infer the optical depth of liquid water clouds from narrow band spectral Multifilter Rotating Shadowband Radiometer (MFRSR) measurements (Harrison et al. 1994). Their retrieval also uses the total liquid water path (LWP) measured by a microwave radiometer (MWR) to obtain the effective radius of the warm cloud droplets. Their results were compared with Geostationary Operational Environmental Satellite (GOES) retrieved values at the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site (Min and Harrison 1996). Min et al. (2003) also validated the retrieved cloud optical properties against in situ observations, showing that the retrieved cloud effective radius agreed well with the in situ forward scattering spectrometer probe observations. The retrieved cloud optical properties from Min et al. (2003) were used also as inputs to an atmospheric shortwave model, and the computed fluxes were compared with surface pyranometer observations.

  3. Estimating Soil Moisture from Satellite Microwave Observations

    Science.gov (United States)

    Owe, M.; VandeGriend, A. A.; deJeu, R.; deVries, J.; Seyhan, E.

    1998-01-01

    Cooperative research in microwave remote sensing between the Hydrological Sciences Branch of the NASA Goddard Space Flight Center and the Earth Sciences Faculty of the Vrije Universiteit Amsterdam began with the Botswana Water and Energy Balance Experiment and has continued through a series of highly successful International Research Programs. The collaboration between these two research institutions has resulted in significant scientific achievements, most notably in the area of satellite-based microwave remote sensing of soil moisture. The Botswana Program was the first joint research initiative between these two institutions, and provided a unique data base which included historical data sets of Scanning Multifrequency Microwave Radiometer (SN4NM) data, climate information, and extensive soil moisture measurements over several large experimental sites in southeast Botswana. These data were the basis for the development of new approaches in physically-based inverse modelling of soil moisture from satellite microwave observations. Among the results from this study were quantitative estimates of vegetation transmission properties at microwave frequencies. A single polarization modelling approach which used horizontally polarized microwave observations combined with monthly composites of Normalized Difference Vegetation Index was developed, and yielded good results. After more precise field experimentation with a ground-based radiometer system, a dual-polarization approach was subsequently developed. This new approach realized significant improvements in soil moisture estimation by satellite. Results from the Botswana study were subsequently applied to a desertification monitoring study for the country of Spain within the framework of the European Community science research programs EFEDA and RESMEDES. A dual frequency approach with only microwave data was used for this application. The Microwave Polarization Difference Index (MPDI) was calculated from 37 GHz data

  4. Utilization of surface cover composition to improve the microwave determination of snow water equivalent in a mountain basin

    Science.gov (United States)

    Chang, A. T. C.; Foster, J. L.; Rango, A.

    1991-01-01

    Satellite microwave data have been used to derive areal snow water equivalent in flat homogeneous areas. Over heterogeneous mountainous areas different algorithms are needed to retrieve the water equivalent of the snow cover. A mixed pixel model based on the percentage of vegetation cover within a pixel has been developed to simulate the microwave brightness temperatures for the Rio Grande basin in southwestern Colorado. A relationship between the difference in microwave-brightness temperature at two different frequencies (37- and 18-GHz horizontal polarization), and the basin-wide average snow water equivalent was obtained. The areal snow-water equivalent values derived from the model were consistent with values generated by a reliable snowmelt run-off model using snow-cover extent data.

  5. Characterization of a digital microwave radiometry system for noninvasive thermometry using a temperature-controlled homogeneous test load.

    Science.gov (United States)

    Arunachalam, K; Stauffer, P R; Maccarini, P F; Jacobsen, S; Sterzer, F

    2008-07-21

    Microwave radiometry has been proposed as a viable noninvasive thermometry approach for monitoring subsurface tissue temperatures and potentially controlling power levels of multielement heat applicators during clinical hyperthermia treatments. With the evolution of technology, several analog microwave radiometry devices have been developed for biomedical applications. In this paper, we describe a digital microwave radiometer with built-in electronics for signal processing and automatic self-calibration. The performance of the radiometer with an Archimedean spiral receive antenna is evaluated over a bandwidth of 3.7-4.2 GHz in homogeneous and layered water test loads. Controlled laboratory experiments over the range of 30-50 degrees C characterize measurement accuracy, stability, repeatability and penetration depth sensitivity. The ability to sense load temperature through an intervening water coupling bolus of 6 mm thickness is also investigated. To assess the clinical utility and sensitivity to electromagnetic interference (EMI), experiments are conducted inside standard clinical hyperthermia treatment rooms with no EM shielding. The digital radiometer provided repeatable measurements with 0.075 degrees C resolution and standard deviation of 0.217 degrees C for homogeneous and layered tissue loads at temperatures between 32-45 degrees C. Within the 3.7-4.2 GHz band, EM noise rejection was good other than some interference from overhead fluorescent lights in the same room as the radiometer. The system response obtained for ideal water loads suggests that this digital radiometer should be useful for estimating subcutaneous tissue temperatures under a 6 mm waterbolus used during clinical hyperthermia treatments. The accuracy and stability data obtained in water test loads of several configurations support our expectation that single band radiometry should be sufficient for sub-surface temperature monitoring and power control of large multielement array superficial

  6. Characterization of a digital microwave radiometry system for noninvasive thermometry using a temperature-controlled homogeneous test load

    Energy Technology Data Exchange (ETDEWEB)

    Arunachalam, K; Stauffer, P R; Maccarini, P F [Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710 (United States); Jacobsen, S [Department of Physics and Technology, University of Tromso, N-9037 (Norway); Sterzer, F [MMTC, Inc. Princeton, NJ 08540 (United States)], E-mail: kavitha.arunachalam@duke.edu

    2008-07-21

    Microwave radiometry has been proposed as a viable noninvasive thermometry approach for monitoring subsurface tissue temperatures and potentially controlling power levels of multielement heat applicators during clinical hyperthermia treatments. With the evolution of technology, several analog microwave radiometry devices have been developed for biomedical applications. In this paper, we describe a digital microwave radiometer with built-in electronics for signal processing and automatic self-calibration. The performance of the radiometer with an Archimedean spiral receive antenna is evaluated over a bandwidth of 3.7-4.2 GHz in homogeneous and layered water test loads. Controlled laboratory experiments over the range of 30-50 deg. C characterize measurement accuracy, stability, repeatability and penetration depth sensitivity. The ability to sense load temperature through an intervening water coupling bolus of 6 mm thickness is also investigated. To assess the clinical utility and sensitivity to electromagnetic interference (EMI), experiments are conducted inside standard clinical hyperthermia treatment rooms with no EM shielding. The digital radiometer provided repeatable measurements with 0.075 deg. C resolution and standard deviation of 0.217 deg. C for homogeneous and layered tissue loads at temperatures between 32-45 deg. C. Within the 3.7-4.2 GHz band, EM noise rejection was good other than some interference from overhead fluorescent lights in the same room as the radiometer. The system response obtained for ideal water loads suggests that this digital radiometer should be useful for estimating subcutaneous tissue temperatures under a 6 mm waterbolus used during clinical hyperthermia treatments. The accuracy and stability data obtained in water test loads of several configurations support our expectation that single band radiometry should be sufficient for sub-surface temperature monitoring and power control of large multielement array superficial hyperthermia

  7. Characterization of a digital microwave radiometry system for noninvasive thermometry using a temperature-controlled homogeneous test load

    Science.gov (United States)

    Arunachalam, K.; Stauffer, P. R.; Maccarini, P. F.; Jacobsen, S.; Sterzer, F.

    2008-07-01

    Microwave radiometry has been proposed as a viable noninvasive thermometry approach for monitoring subsurface tissue temperatures and potentially controlling power levels of multielement heat applicators during clinical hyperthermia treatments. With the evolution of technology, several analog microwave radiometry devices have been developed for biomedical applications. In this paper, we describe a digital microwave radiometer with built-in electronics for signal processing and automatic self-calibration. The performance of the radiometer with an Archimedean spiral receive antenna is evaluated over a bandwidth of 3.7-4.2 GHz in homogeneous and layered water test loads. Controlled laboratory experiments over the range of 30-50 °C characterize measurement accuracy, stability, repeatability and penetration depth sensitivity. The ability to sense load temperature through an intervening water coupling bolus of 6 mm thickness is also investigated. To assess the clinical utility and sensitivity to electromagnetic interference (EMI), experiments are conducted inside standard clinical hyperthermia treatment rooms with no EM shielding. The digital radiometer provided repeatable measurements with 0.075 °C resolution and standard deviation of 0.217 °C for homogeneous and layered tissue loads at temperatures between 32-45 °C. Within the 3.7-4.2 GHz band, EM noise rejection was good other than some interference from overhead fluorescent lights in the same room as the radiometer. The system response obtained for ideal water loads suggests that this digital radiometer should be useful for estimating subcutaneous tissue temperatures under a 6 mm waterbolus used during clinical hyperthermia treatments. The accuracy and stability data obtained in water test loads of several configurations support our expectation that single band radiometry should be sufficient for sub-surface temperature monitoring and power control of large multielement array superficial hyperthermia applicators.

  8. Satellite derived integrated water vapor and rain intensity patterns - Indicators of rapid cyclogenesis

    Science.gov (United States)

    Mcmurdie, Lynn; Katsaros, Kristina

    1992-01-01

    We examine integrated water vapor fields and rain intensity patterns derived from the Scanning Multichannel Microwave Radiometer (SMMR) and Special Sensor Microwave/Imager (SSM/I) for several rapidly deepening and non-rapidly deepening midlatitude cyclones in the North Atlantic. Our goal is to identify features in the satellite data unique to the rapidly deepening cases, and to explore how these data can potentially be used in the analysis and forecasting of these events.

  9. Satellite derived integrated water vapor and rain intensity patterns: Indicators of rapid cyclogenesis

    Science.gov (United States)

    Mcmurdie, Lynn; Katsaros, Kristina

    1992-01-01

    We examine integrated water vapor fields and rain intensity patterns derived from the Scanning Multichannel Microwave Radiometer (SMMR) and Special Sensor Microwave/Imager (SSM/I) for several rapidly deepening and non-rapidly deepening midlatitude cyclones in the North Atlantic. Our goal is to identify features in the satellite data unique to the rapidly deepening cases, and to explore how these data can potentially be used in the analysis and forecasting of these events.

  10. Estimation of Hydraulic properties of a sandy soil using ground-based active and passive microwave remote sensing

    KAUST Repository

    Jonard, François

    2015-06-01

    In this paper, we experimentally analyzed the feasibility of estimating soil hydraulic properties from 1.4 GHz radiometer and 0.8-2.6 GHz ground-penetrating radar (GPR) data. Radiometer and GPR measurements were performed above a sand box, which was subjected to a series of vertical water content profiles in hydrostatic equilibrium with a water table located at different depths. A coherent radiative transfer model was used to simulate brightness temperatures measured with the radiometer. GPR data were modeled using full-wave layered medium Green\\'s functions and an intrinsic antenna representation. These forward models were inverted to optimally match the corresponding passive and active microwave data. This allowed us to reconstruct the water content profiles, and thereby estimate the sand water retention curve described using the van Genuchten model. Uncertainty of the estimated hydraulic parameters was quantified using the Bayesian-based DREAM algorithm. For both radiometer and GPR methods, the results were in close agreement with in situ time-domain reflectometry (TDR) estimates. Compared with radiometer and TDR, much smaller confidence intervals were obtained for GPR, which was attributed to its relatively large bandwidth of operation, including frequencies smaller than 1.4 GHz. These results offer valuable insights into future potential and emerging challenges in the development of joint analyses of passive and active remote sensing data to retrieve effective soil hydraulic properties.

  11. Influence of water content on RF and microwave dielectric behavior of foods.

    Science.gov (United States)

    Nelson, Stuart O; Trabelsi, Samir

    2009-01-01

    The importance of dielectric properties of food materials is discussed with respect to their influence on the heating of materials by radio-frequency and microwave energy and their use for rapid, nondestructive sensing of quality characteristics of such materials. Data are presented graphically showing the frequency and temperature dependence of the dielectric constant and loss factor of wheat, fresh chicken breast meat, several fresh fruits, and apple juice, representing food materials with a wide range of moisture content. The influence of moisture or water content on the dielectric behavior of these materials is discussed, and that behavior is explained in terms of dipolar relaxation and ionic conduction.

  12. Evaluating Frontal Precipitation with a Spectral Microphysics Mesoscale Model and a Satellite Simulator as Compared to Radar and Radiometer Observations

    Science.gov (United States)

    Han, M.; Braun, S. A.; Matsui, T.; Iguchi, T.; Williams, C. R.

    2013-12-01

    The Advanced Microwave Scanning Radiometer for EOS (AMSR-E) onboard NASA Aqua satellite and a ground-based precipitation profiling radar sampled a frontal precipitation event in the US west coast on 30 to 31 December 2005. Simulations with bulk microphysics schemes in the Weather Research and Forecast (WRF) model have been evaluated with those remote sensing data. In the current study, we continue similar work to evaluate a spectral bin microphysics (SBM) scheme, HUCM, in the WRF model. The Goddard-Satellite Data Simulation Unit (G-SDSU) is used to simulate quantities observed by the radar and radiometer. With advanced representation of cloud and precipitation microphysics processes, the HUCM scheme predicts distributions of 7 hydrometeor species as storms evolve. In this study, the simulation with HUCM well captured the structure of the precipitation and its microphysics characteristics. In addition, it improved total precipitation ice mass simulation and corrected, to a certain extent, the large low bias of ice scattering signature in the bulk scheme simulations. However, the radar reflectivity simulations with the HUCM scheme were not improved as compared to the bulk schemes. We conducted investigations to understand how microphysical processes and properties, such as snow break up parameter and particle fall velocities would influence precipitation size distribution and spectrum of water paths, and further modify radar and/or radiometer simulations. Influence by ice nuclei is going to be examined as well.

  13. Microwave-hydrothermal method for the synthesis of composite materials for removal of arsenic from water.

    Science.gov (United States)

    Andjelkovic, Ivan; Jovic, Bojan; Jovic, Milica; Markovic, Marijana; Stankovic, Dalibor; Manojlovic, Dragan; Roglic, Goran

    2016-01-01

    Composite material Zr-doped TiO2, suitable for the removal of arsenic from water, was synthetized with fast and simple microwave-hydrothermal method. Obtained material, Zr-TiO2, had uniform size and composition with zirconium ions incorporated into crystal structure of titanium dioxide. Synthetized composite material had large specific surface area and well-developed micropore and mesopore structure that was responsible for fast adsorption of As(III) and As(V) from water. The influence of pH on the adsorption capacity of arsenic was studied. The kinetics and isotherm experiments were also performed. The treatment of natural water sample containing high concentration of arsenic with composite material Zr-TiO2 was efficient. The concentration of arsenic was reduced to the value recommended by WHO.

  14. Low Cost and Pipe Conformable Microwave-Based Water-Cut Sensor

    KAUST Repository

    Karimi, Muhammad Akram

    2016-08-11

    Efficient oil production and refining processes require the precise measurement of water content in oil. This paper presents a novel planar microwave sensor for entirely non-intrusive in situ water cut (WC) sensing over the full range of operation, i.e., 0%-100%. A planar configuration has enabled the direct implementation of WC sensor on the pipe surface using low cost method, i.e., screen printing using 3D printed mask. Modified ground plane-based T-resonator design makes this WC sensor usable for the wide range of pipe sizes present in the oil industry. The viability of this sensor has been confirmed through electromagnetic simulations as well as through a prototype characterization. Two cases of oil and water mixtures, namely, separate phases and homogeneous mix, have been studied. Measurements performed over two independently built prototypes show the root mean square variation in results of only 0.1%.

  15. Description and Performance of an L-Band Radiometer with Digital Beamforming

    Directory of Open Access Journals (Sweden)

    Juan F. Marchan-Hernandez

    2010-12-01

    Full Text Available This paper presents the description and performance tests of an L-band microwave radiometer with Digital Beamforming (DBF, developed for the Passive Advanced Unit (PAU for ocean monitoring project. PAU is an instrument that combines, in a single receiver and without time multiplexing, a microwave radiometer at L-band (PAU-RAD and a GPS-reflectometer (PAU-GNSS-R. This paper focuses on the PAU‑RAD beamformer’s first results, analyzing the hardware and software required for the developed prototype. Finally, it discusses the first results measured in the Universitat Politècnica de Catalunya (UPC anechoic chamber.

  16. Application of the Markov Chain Monte Carlo method for snow water equivalent retrieval based on passive microwave measurements

    Science.gov (United States)

    Pan, J.; Durand, M. T.; Vanderjagt, B. J.

    2015-12-01

    Markov Chain Monte Carlo (MCMC) method is a retrieval algorithm based on Bayes' rule, which starts from an initial state of snow/soil parameters, and updates it to a series of new states by comparing the posterior probability of simulated snow microwave signals before and after each time of random walk. It is a realization of the Bayes' rule, which gives an approximation to the probability of the snow/soil parameters in condition of the measured microwave TB signals at different bands. Although this method could solve all snow parameters including depth, density, snow grain size and temperature at the same time, it still needs prior information of these parameters for posterior probability calculation. How the priors will influence the SWE retrieval is a big concern. Therefore, in this paper at first, a sensitivity test will be carried out to study how accurate the snow emission models and how explicit the snow priors need to be to maintain the SWE error within certain amount. The synthetic TB simulated from the measured snow properties plus a 2-K observation error will be used for this purpose. It aims to provide a guidance on the MCMC application under different circumstances. Later, the method will be used for the snowpits at different sites, including Sodankyla, Finland, Churchill, Canada and Colorado, USA, using the measured TB from ground-based radiometers at different bands. Based on the previous work, the error in these practical cases will be studied, and the error sources will be separated and quantified.

  17. Sequential microwave superheated water extraction of mannans from spent coffee grounds.

    Science.gov (United States)

    Passos, Cláudia P; Moreira, Ana S P; Domingues, M Rosário M; Evtuguin, Dmitry V; Coimbra, Manuel A

    2014-03-15

    The feasibility of using sequential microwave superheated water extraction (MAE) for the recovery of mannans from spent coffee grounds (SCG) was studied. Due to the high contents of mannose still present in the SCG residue left after two consecutive MAE, the unextracted material was re-suspended in water and submitted to a third microwave irradiation (MAE3) at 200 °C for 3 min. With MAE3, mannose recovery achieved 48%, increasing to 56% by MAE4, and reaching a maximum of 69% with MAE5. Glycosidic-linkage analysis showed that in MAE3 mainly galactomannans were recovered, while debranched galactomannans were recovered with MAE4 and MAE5. With increasing the number of extractions, the average degree of polymerization of the mannans decreased, as observed by size-exclusion chromatography and by methylation analysis. Scanning electron microscopy images showed a decrease on cell walls thickness. After final MAE5, the remaining un-extracted insoluble material, representing 22% of the initial SCG, was composed mainly by cellulose (84%).

  18. Passive Microwave Measurements of Salinity: The Gulf Stream Experiment

    Science.gov (United States)

    LeVine, D. M.; Koblinsky, C.; Haken, M.; Howden, S.; Bingham, F.; Hildebrand, Peter H. (Technical Monitor)

    2001-01-01

    Passive microwave sensors at L-band (1.4 GHz) operating from aircraft have demonstrated that salinity can be measured with sufficient accuracy (I psu) to be scientifically meaningful in coastal waters. However, measuring salinity in the open ocean presents unresolved issues largely because of the much greater accuracy (approximately 0.2 psu) required of global maps to be scientifically viable. The development of a satellite microwave instrument to make global measurements of SSS (Sea Surface Salinity) is the focus of a joint JPL/GSFC/NASA ocean research program called Aquarius. In the summer of 1999 a series of measurements called, The Gulf Stream Experiment, were conducted as part of research at the Goddard Space Flight Center to test the potential for passive microwave remote sensing of salinity in the open ocean. The measurements consisted of airborne microwave instruments together with ships and drifters for surface truth. The study area was a 200 km by 100 km rectangle about 250 km east of Delaware Bay between the continental shelf waters and north wall of the Gulf Stream. The primary passive instruments were the ESTAR radiometer (L-band, H-pol) and the SLFMR radiometer (L-band, V-pol). In addition, the instruments on the aircraft included a C-band radiometer (ACMR), an ocean wave scatterometer (ROWS) and an infrared radiometer (for surface temperature). These instruments were mounted on the NASA P-3 Orion aircraft. Sea surface measurements consisted of thermosalinograph data provided by the R/V Cape Henlopen and the MN Oleander, and data from salinity and temperature sensors on three surface drifters deployed from the R/V Cape Henlopen. The primary experiment period was August 26-September 2, 1999. During this period the salinity field within the study area consisted of a gradient on the order of 2-3 psu in the vicinity of the shelf break and a warm core ring with a gradient of 1-2 psu. Detailed maps were made with the airborne sensors on August 28 and 29 and

  19. Modeling of Microwave Reflection from the Surface of Water Basins with Spills of Water-Cut Oil

    Science.gov (United States)

    Krotikov, V. D.; Pelushenko, S. A.; Rakut', I. V.; Savelyev, V. Yu.

    2015-06-01

    We consider specific features of reflection of microwaves from the surface of a water basin for the two-layer model of oil spills, which are determined by a water-cut-oil film. Within the spill model, the dielectric properties of water were allowed for in accordance with the Debye theory, and the dielectric properties of the water-cut oil, in accordance with the theory developed for binary systems. The data about variations in the values of reflection coefficients depending on the frequency, viewing angle, thickness of the oil film, and moisture content in the film are obtained. The dependences of reflection coefficients on the film thickness are determined for various values of volume content of the water fraction in oil. Complex values of the dielectric permittivity of oil-water emulsions with preset volume moisture content are found. Describing the obtained dependences of the complex dielectric permittivity of the emulsion on the volume moisture content requires application of asymmetrical formulas for the mixture of polar and nonpolar fluids.

  20. Radiometer system to map the cosmic background radiation

    Science.gov (United States)

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

    1978-01-01

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

  1. Planck-LFI radiometers' spectral response

    Energy Technology Data Exchange (ETDEWEB)

    Zonca, A [INAF-IASF Milano, Via E. Bassini 15, 20133 Milano (Italy); Franceschet, C; Mennella, A; Bersanelli, M [Universita di Milano, Dipartimento di Fisica, Via G. Celoria 16, 20133 Milano (Italy); Battaglia, P; Silvestri, R [Thales Alenia Space Italia S.p.A., S.S. Padana Superiore 290, 20090 Vimodrone, Milano (Italy); Villa, F; Butler, R C; Cuttaia, F; Mandolesi, N [INAF-IASF Bologna, Via P. Gobetti 101, 40129 Bologna (Italy); D' Arcangelo, O [IFP-CNR, via Cozzi 53, 20125 Milano (Italy); Artal, E [Departamento de IngenierIa de Comunicaciones, Universidad de Cantabria, Avenida de los Castros s/n. 39005 Santander (Spain); Davis, R J [Jodrell Bank Centre for Astrophysics, Alan Turing Building, The University of Manchester, Manchester, M13 9PL (United Kingdom); Galeotta, S; Maris, M [INAF-OATs, Via G.B. Tiepolo 11, I-34131, Trieste (Italy); Hughes, N; Jukkala, P; Kilpiae, V-H [DA-Design Oy, Keskuskatu 29, FI-31600, Jokioinen (Finland); Laaninen, M [Ylinen Electronics Oy, Teollisuustie 9A, FIN-02700, Kauniainen (Finland); Mendes, L, E-mail: andrea.zonca@fisica.unimi.i [ESA - ESAC, Camino bajo del Castillo, s/n, Villanueva de la Canada 28692 Madrid (Spain)

    2009-12-15

    The Low Frequency Instrument (LFI) is an array of pseudo-correlation radiometers on board the Planck satellite, the ESA mission dedicated to precision measurements of the Cosmic Microwave Background. The LFI covers three bands centred at 30, 44 and 70 GHz, with a goal bandwidth of 20% of the central frequency. The characterization of the broadband frequency response of each radiometer is necessary to understand and correct for systematic effects, particularly those related to foreground residuals and polarization measurements. In this paper we present the measured band shape of all the LFI channels and discuss the methods adopted for their estimation. The spectral characterization of each radiometer was obtained by combining the measured spectral response of individual units through a dedicated RF model of the LFI receiver scheme. As a consistency check, we also attempted end-to-end spectral measurements of the integrated radiometer chain in a cryogenic chamber. However, due to systematic effects in the measurement setup, only qualitative results were obtained from these tests. The measured LFI bandpasses exhibit a moderate level of ripple, compatible with the instrument scientific requirements.

  2. Artificial neural network coupled with wavelet transform for estimating snow water equivalent using passive microwave data

    Indian Academy of Sciences (India)

    A B Dariane; S Azimi; A Zakerinej

    2014-10-01

    Snow Water Equivalent (SWE) is an important parameter in hydrologic engineering involving the stream-flow forecasting of high-elevation watersheds. In this paper, the application of classic Artificial Neural Network model (ANN) and a hybrid model combining the wavelet and ANN (WANN) is investigated in estimating the value of SWE in a mountainous basin. In addition, k-fold cross validation method is used in order to achieve a more reliable and robust model. In this regard, microwave images acquired from Spectral Sensor Microwave Imager (SSM/I) are used to estimate the SWE of Tehran sub-basins during 1992–2008 period. Also for obtaining measured SWE within the corresponding Equal-Area Scalable Earth-Grid (EASE-Grid) cell of SSM/I image, approach of Cell-SWE extraction using height–SWE relations is applied in order to reach more precise estimations. The obtained results reveal that the wavelet-ANN model significantly increases the accuracy of estimations, mainly because of using multi-scale time series as the ANN inputs. The Nash–Sutcliffe Index (NSE) for ANN and WANN models is respectively 0.09 and 0.44 which shows a firm improvement of 0.35 in NSE parameter when WANN is applied. Similar trend is observed in other parameters including RMSE where the value is 0.3 for ANN and 0.07 for WANN.

  3. Precipitation Estimation Using Combined Radar/Radiometer Measurements Within the GPM Framework

    Science.gov (United States)

    Hou, Arthur

    2012-01-01

    The Global Precipitation Measurement (GPM) Mission is an international satellite mission specifically designed to unify and advance precipitation measurements from a constellation of research and operational microwave sensors. The GPM mission centers upon the deployment of a Core Observatory in a 65o non-Sun-synchronous orbit to serve as a physics observatory and a transfer standard for intersatellite calibration of constellation radiometers. The GPM Core Observatory will carry a Ku/Ka-band Dual-frequency Precipitation Radar (DPR) and a conical-scanning multi-channel (10-183 GHz) GPM Microwave Radiometer (GMI). The DPR will be the first dual-frequency radar in space to provide not only measurements of 3-D precipitation structures but also quantitative information on microphysical properties of precipitating particles needed for improving precipitation retrievals from microwave sensors. The DPR and GMI measurements will together provide a database that relates vertical hydrometeor profiles to multi-frequency microwave radiances over a variety of environmental conditions across the globe. This combined database will be used as a common transfer standard for improving the accuracy and consistency of precipitation retrievals from all constellation radiometers. For global coverage, GPM relies on existing satellite programs and new mission opportunities from a consortium of partners through bilateral agreements with either NASA or JAXA. Each constellation member may have its unique scientific or operational objectives but contributes microwave observations to GPM for the generation and dissemination of unified global precipitation data products. In addition to the DPR and GMI on the Core Observatory, the baseline GPM constellation consists of the following sensors: (1) Special Sensor Microwave Imager/Sounder (SSMIS) instruments on the U.S. Defense Meteorological Satellite Program (DMSP) satellites, (2) the Advanced Microwave Scanning Radiometer-2 (AMSR-2) on the GCOM-W1

  4. Synergistic effects of ajoene and the microwave power density memories of water on germination inhibition of fungal spores.

    Science.gov (United States)

    Rai, S; Singh, U P; Mishra, G D; Singh, S P; Samarketu; Wagner, K G

    1995-05-01

    The synergistic effects of ajoene and the microwave power density memories of water on germination inhibition of some fungal spores are examined. The study reveals power memory varying different synergistic effects of different concentrations of ajoene on the inhibition of spore germination.

  5. Improved Dielectric Model for Polyvinyl Alcohol-Water Hydrogel at Microwave Frequencies

    Directory of Open Access Journals (Sweden)

    You K. Yeow

    2010-01-01

    Full Text Available Problem statement: The study described rigorous dielectric modeling for Polyvinyl Alcohol (PVA-water hydrogel mixture at microwave frequencies. Approach: A commercial open-ended coaxial sensor was used to measure the dielectric constant, loss factor and ionic conductivity, σ of PVA-water hydrogel mixture ranging concentration of 80-100% water content. Results: The sensor was operating between 0.13 and 20 GHz at and above of room temperature (25±1°C. Indirectly, the relaxation time, τ, activation energy, Q and entropy change, ΔS of the hydrogel mixtures are determined based on linear fitting of measured data using Debye and Arrhenius approaches. Conclusion/Recommendations: Two main relaxation processes were found ranging 2-10 and 10-20 GHz, respectively. Dielectric dispersion is suggested to describe by combination of Cole-Davidson (CD and Debye (Dy processes. The results are discussed qualitatively based on bound states of water in hydrogel mixtures.

  6. Microwave-Assisted Preparation of Biodegradable Water Absorbent Polyacrylonitrile/Montmorillonite Clay Nanocomposite

    Directory of Open Access Journals (Sweden)

    Prafulla K. Sahoo

    2011-01-01

    Full Text Available Polyacrylonitrile (PAN/Montmorillonite (MMT clay nanocomposite was prepared in a microwave oven using a transition metal Co(III complex taking ammonium persulfate (APS as initiator with a motive of converting hydrophobic PAN into hydrophilic nanocomposite material via nanotechnology by the inclusion of MMT to the virgin polymer. UV-visible spectral analysis revealed various interactions between the developed complex with other reaction components. The formation of the PAN/MMT nanocomposites was characterized by FTIR. Furthermore, as evidenced by X-ray diffraction (XRD, transmission electron microscopy (TEM, the composite so obtained was found to have nano-order. XRD and TEM were suggesting that montmorillonite layers were exfoliated during the polymerization process. An increasing in the thermal stability for the developed nanocomposite was recorded by thermogravimetric analysis (TGA. The water absorption and biodegradation properties were carried out for its ecofriendly nature and better commercialization.

  7. An integrating sphere radiometer as a solution for high power calibrations in fibre optics

    Science.gov (United States)

    Carrasco-Sanz, Ana; Rodríguez-Barrios, Félix; Corredera, Pedro; Martín-López, Sonia; González-Herráez, Miguel; Hernanz, María Luisa

    2006-04-01

    This paper describes the design, characterization and calibration of a high power transfer standard for optical power measurements in optical fibres based on an integrating sphere radiometer. This radiometer, based on two detectors (Si and InGaAs), can measure powers between 100 nW and 10 W within the wavelength range of (400-1700) nm. The radiometer has been calibrated over the total spectral range of use against an electrically calibrated pyroelectric radiometer and different fibre laser diodes and ion lasers. The total uncertainty obtained is lower than ±1.5% for these wavelengths and power ranges (excluding the water absorption region).

  8. Machine Learning on Images: Combining Passive Microwave and Optical Data to Estimate Snow Water Equivalent

    Science.gov (United States)

    Dozier, J.; Tolle, K.; Bair, N.

    2014-12-01

    We have a problem that may be a specific example of a generic one. The task is to estimate spatiotemporally distributed estimates of snow water equivalent (SWE) in snow-dominated mountain environments, including those that lack on-the-ground measurements. Several independent methods exist, but all are problematic. The remotely sensed date of disappearance of snow from each pixel can be combined with a calculation of melt to reconstruct the accumulated SWE for each day back to the last significant snowfall. Comparison with streamflow measurements in mountain ranges where such data are available shows this method to be accurate, but the big disadvantage is that SWE can only be calculated retroactively after snow disappears, and even then only for areas with little accumulation during the melt season. Passive microwave sensors offer real-time global SWE estimates but suffer from several issues, notably signal loss in wet snow or in forests, saturation in deep snow, subpixel variability in the mountains owing to the large (~25 km) pixel size, and SWE overestimation in the presence of large grains such as depth and surface hoar. Throughout the winter and spring, snow-covered area can be measured at sub-km spatial resolution with optical sensors, with accuracy and timeliness improved by interpolating and smoothing across multiple days. So the question is, how can we establish the relationship between Reconstruction—available only after the snow goes away—and passive microwave and optical data to accurately estimate SWE during the snow season, when the information can help forecast spring runoff? Linear regression provides one answer, but can modern machine learning techniques (used to persuade people to click on web advertisements) adapt to improve forecasts of floods and droughts in areas where more than one billion people depend on snowmelt for their water resources?

  9. Future spaceborne ocean missions using high sensitivity multiple-beam radiometers

    DEFF Research Database (Denmark)

    Skou, Niels; Søbjærg, Sten Schmidl; Kristensen, Steen Savstrup

    2014-01-01

    Design considerations concerning a scanning as well as a push-broom microwave radiometer system are presented. Strict requirements to spatial and radiometric resolution leads to a multiple-beam scanner achieving good sensitivity through integration over many beams, or to a push-broom system where...

  10. On-board digital RFI and polarimetry processor for future spaceborne radiometer systems

    DEFF Research Database (Denmark)

    Skou, Niels; Kristensen, Steen Savstrup; Ruokokoski, T.

    2012-01-01

    Man-made Radio Frequency Interference (RFI) is an increasingly threatening problem for passive microwave radiometry from space. The problem is presently very evident in L-band data from SMOS, but it is realized that it is already now a problem at other traditional radiometer bands at C, X, and Ku...

  11. An optical fiber sensor based on cladding photoluminescence for high power microwave plasma ultraviolet lamps used in water treatment

    Science.gov (United States)

    Fitzpatrick, C.; Lewis, E.; Al-Shamma'A, A.; Pandithas, I.; Cullen, J.; Lucas, J.

    2001-11-01

    Low-pressure mercury lamps are commonly used for germicidal applications such as water and wastewater sterilisation. The germicidal effect is due to the emission of light at 254 nm, which leads to the destruction of most waterborne bacteria. The Microwave plasma ultraviolet lamp (MPUVL) is a new technology for generating a high intensity ultraviolet (UV) light. A Fluorescent optical fiber based sensor is presented which is used for monitoring the output of a high power microwave UV light source and its control. This sensor is a fiber which has had its cladding removed and been coated with a phosphor doped polymer.

  12. Ozone profiles obtained by DIAL technique at Maïdo Observatory in La Reunion Island: comparisons with ECC ozone-sondes, ground-based FTIR spectrometer and microwave radiometer measurements

    Directory of Open Access Journals (Sweden)

    Portafaix T.

    2016-01-01

    Full Text Available A DIAL lidar system performing stratospheric ozone profile measurements from 15 to 45 km is installed at Reunion Island (southwest of Indian Ocean. The purpose of this communication is to present this DIAL system mounted now at the new Maïdo Observatory since February 2013, and the ozone profile retrieval. The first stratospheric ozone profiles obtained during 2013 and 2014 will be presented and discussed. Inter-comparison and differences observed with other high vertical resolution ozone profiles performed by ECC ozonesonde will be shown. Finally, comparisons with low vertical resolution ozone profiles retrieved from microwave and FTIR remote sensing measurements performed at Maïdo will be carried out, making appropriate use of the associated averaging kernels

  13. Ozone profiles obtained by DIAL technique at Maïdo Observatory in La Reunion Island: comparisons with ECC ozone-sondes, ground-based FTIR spectrometer and microwave radiometer measurements

    Science.gov (United States)

    Portafaix, T.; Godin-Beekmann, S.; Payen, G.; de Mazière, M.; Langerock, B.; Fernandez, S.; Posny, F.; Cammas, J. P.; Metzger, J. M.; Bencherif, H.; Vigouroux, C.; Marquestaut, N.

    2016-06-01

    A DIAL lidar system performing stratospheric ozone profile measurements from 15 to 45 km is installed at Reunion Island (southwest of Indian Ocean). The purpose of this communication is to present this DIAL system mounted now at the new Maïdo Observatory since February 2013, and the ozone profile retrieval. The first stratospheric ozone profiles obtained during 2013 and 2014 will be presented and discussed. Inter-comparison and differences observed with other high vertical resolution ozone profiles performed by ECC ozonesonde will be shown. Finally, comparisons with low vertical resolution ozone profiles retrieved from microwave and FTIR remote sensing measurements performed at Maïdo will be carried out, making appropriate use of the associated averaging kernels

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

    Science.gov (United States)

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

    2016-09-01

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

  15. Microwave Soil Moisture Retrieval Under Trees

    Science.gov (United States)

    O'Neill, P.; Lang, R.; Kurum, M.; Joseph, A.; Jackson, T.; Cosh, M.

    2008-01-01

    Soil moisture is recognized as an important component of the water, energy, and carbon cycles at the interface between the Earth's surface and atmosphere. Current baseline soil moisture retrieval algorithms for microwave space missions have been developed and validated only over grasslands, agricultural crops, and generally light to moderate vegetation. Tree areas have commonly been excluded from operational soil moisture retrieval plans due to the large expected impact of trees on masking the microwave response to the underlying soil moisture. Our understanding of the microwave properties of trees of various sizes and their effect on soil moisture retrieval algorithms at L band is presently limited, although research efforts are ongoing in Europe, the United States, and elsewhere to remedy this situation. As part of this research, a coordinated sequence of field measurements involving the ComRAD (for Combined Radar/Radiometer) active/passive microwave truck instrument system has been undertaken. Jointly developed and operated by NASA Goddard Space Flight Center and George Washington University, ComRAD consists of dual-polarized 1.4 GHz total-power radiometers (LH, LV) and a quad-polarized 1.25 GHz L band radar sharing a single parabolic dish antenna with a novel broadband stacked patch dual-polarized feed, a quad-polarized 4.75 GHz C band radar, and a single channel 10 GHz XHH radar. The instruments are deployed on a mobile truck with an 19-m hydraulic boom and share common control software; real-time calibrated signals, and the capability for automated data collection for unattended operation. Most microwave soil moisture retrieval algorithms developed for use at L band frequencies are based on the tau-omega model, a simplified zero-order radiative transfer approach where scattering is largely ignored and vegetation canopies are generally treated as a bulk attenuating layer. In this approach, vegetation effects are parameterized by tau and omega, the microwave

  16. A low cost and pipe conformable microwave-based water-cut sensor

    KAUST Repository

    Karimi, Muhammad Akram

    2016-08-15

    Efficient oil production and refining processes require the precise measurement of water content in oil (i.e., water-cut [WC]) which is extracted during oil production as a by-product. Traditional laboratory water fraction measurements are precise but incapable of providing real-time information, while recently reported inline WC measurements are either incapable of sensing the full WC range (0-100%), restricted to a limited selection of pipe sizes, bulky, intrusive or extremely expensive. This work presents a novel planar microwave sensor for entirely non-intrusive in situ WC sensing over the full range of operation. Its planar configuration has enabled the direct implementation of this sensor on the pipe surface using two low cost methods i.e. copper tape and 3D printed mask. The innovative ground plane design makes this WC sensor usable for the wide range of pipe sizes present in the oil industry. The viability of this sensor has been confirmed through EM simulations as well as through characterization of two types of prototype. The proposed design offers very fine resolution due to its wide sensing range (>110%) in the frequency band of 90-190MHz and repeatability of 0.1%.

  17. A simple method to minimize orientation effects in a profiling radiometer

    Digital Repository Service at National Institute of Oceanography (India)

    Suresh, T.; Talaulikar, M.; Desa, E.; Matondkar, S.G.P.; SrinivasaKumar, T.; Lotlikar, A.

    -fall radiometer is found to be a better option for measuring underwater light parameters as it avoids the effects of ship shadow and is easy to operate, the measurements demand profiling the radiometer vertical in water with minimum tilt. Here we present...

  18. Digital Array Gas Radiometer (DAGR) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The innovation proposed here is a digital array gas radiometer (DAGR), a new design for a gas filter correlation radiometer (GFCR) to accurately measure and monitor...

  19. Microwave Spectrum of Hydrogen Bonded HEXAFLUOROISOPROPANOL•••WATER Complex

    Science.gov (United States)

    Shahi, Abhishek; Arunan, Elangannan

    2014-06-01

    Stabilizing α-helical structure of protein and dissolving a hard to dissolve polymer, polythene terphthalete, are some of the unique properties of the organic solvent Hexafluoroisopropanol (HFIP). After determining the complete microwave spectrum of HFIP monomer, we have recorded the spectrum of HFIP***H_2O complex. Ab initio calculations were used to optimize three different possible structures. The global minimum, structure 1, had HFIP as proton donor. Another promising structure, Structure 2, has been obtained from a molecular dynamic study. A total of 46 observed lines have been fitted well for obtaining the rotational and distortion constants within experimental uncertainty. The observed rotational constants are A = 1134.53898(77) MHz, B = 989.67594(44) MHz and C = 705.26602(20) MHz. Interestingly, the rotational constants of structure 1, structure 2 and experiments were very close. Experimentally observed distortion constants were close to structure 1. b-type transitions were stronger than c-type which is also consistent with the calculated dipole moment components of structure 1. Calculations predict a non-zero a-dipole moment but experimentally a-type transitions were absent. Microwave spectra of two of the deuterium isotopologues of this complex i.e. HFIP***D_2O (30 transitions) and HFIP***HOD (33 transitions) have been also observed. Search for other isotopologues are in progress. To characterize the nature of hydrogen bonding, Atoms in Molecules and Natural Bond Orbital theoretical analysis have been done. Experimental structure and these theoretical analyses indicate that the hydrogen bonding in HFIP***H_2O complex is stronger than that in water dimer. A. Shahi and E. Arunan, Talk number RK16, 68th International Symposium on Molecular Spectroscopy 2013, Ohio, USA. Yamaguchi, T.; Imura, S.; Kai, T.; Yoshida, K. Zeitschrift für Naturforsch. A 2013, 68a, 145.

  20. Laboratory panel and radiometer calibration

    CSIR Research Space (South Africa)

    Deadman, AJ

    2011-07-01

    Full Text Available AND RADIOMETER CALIBRATION A.J Deadmana, I.D Behnerta, N.P Foxa, D. Griffithb aNational Physical Laboratory (NPL), United Kingdom bCouncil for Scientific and Industrial Research (CSIR), South Africa ABSTRACT This paper presents the results...

  1. Effects of "natural" water and "added" water on prediction of moisture content and bulk density of shelled corn from microwave dielectric properties.

    Science.gov (United States)

    Trabelsi, Samir; Nelson, Stuart O; Lewis, Micah A

    2010-01-01

    Dielectric properties of samples of shelled corn of "natural" water content and those prepared by adding water were measured in free space at microwave frequencies and 23 degrees C. Results of measurements of attenuation, phase shift and dielectric constant and loss factor at 9 GHz show no difference between the samples with "natural" water and those in which water was added artificially. Bulk densities and moisture contents predicted from calibration equations expressed in terms of dielectric properties of both natural and added water samples agreed closely, and standard errors were less than 1% for moisture content and relative error for bulk density was less than 5%.

  2. Evaluation of Radar Vegetation Indices for Vegetation Water Content Estimation Using Data from a Ground-Based SMAP Simulator

    Science.gov (United States)

    Srivastava, Prashant K.; O'Neill, Peggy; Cosh, Michael; Lang, Roger; Joseph, Alicia

    2015-01-01

    Vegetation water content (VWC) is an important component of microwave soil moisture retrieval algorithms. This paper aims to estimate VWC using L band active and passive radar/radiometer datasets obtained from a NASA ground-based Soil Moisture Active Passive (SMAP) simulator known as ComRAD (Combined Radar/Radiometer). Several approaches to derive vegetation information from radar and radiometer data such as HH, HV, VV, Microwave Polarization Difference Index (MPDI), HH/VV ratio, HV/(HH+VV), HV/(HH+HV+VV) and Radar Vegetation Index (RVI) are tested for VWC estimation through a generalized linear model (GLM). The overall analysis indicates that HV radar backscattering could be used for VWC content estimation with highest performance followed by HH, VV, MPDI, RVI, and other ratios.

  3. Microwave-Assisted Polyol Synthesis of Water Dispersible Red-Emitting Eu3+-Modified Carbon Dots

    Directory of Open Access Journals (Sweden)

    Hailong Dong

    2016-12-01

    Full Text Available Eu3+-modified carbon dots (C-dots, 3–5 nm in diameter, were prepared, functionalized, and stabilized via a one-pot polyol synthesis. The role of Eu2+/Eu3+, the influence of O2 (oxidation and H2O (hydrolysis, as well as the impact of the heating procedure (conventional resistance heating and microwave (MW heating were explored. With the reducing conditions of the polyol at the elevated temperature of synthesis (200–230 °C, first of all, Eu2+ was obtained resulting in the blue emission of the C-dots. Subsequent to O2-driven oxidation, Eu3+-modified, red-emitting C-dots were realized. However, the Eu3+ emission is rapidly quenched by water for C-dots prepared via conventional resistance heating. In contrast to the hydroxyl functionalization of conventionally-heated C-dots, MW-heating results in a carboxylate functionalization of the C-dots. Carboxylate-coordinated Eu3+, however, turned out as highly stable even in water. Based on this fundamental understanding of synthesis and material, in sum, a one-pot polyol approach is established that results in H2O-dispersable C-dots with intense red Eu3+-line-type emission.

  4. Aerosol Remote Sensing Applications for Airborne Multiangle, Multispectral Shortwave Radiometers

    Science.gov (United States)

    von Bismarck, Jonas; Ruhtz, Thomas; Starace, Marco; Hollstein, André; Preusker, René; Fischer, Jürgen

    2010-05-01

    Aerosol particles have an important impact on the surface net radiation budget by direct scattering and absorption (direct aerosol effect) of solar radiation, and also by influencing cloud formation processes (semi-direct and indirect aerosol effects). To study the former, a number of multispectral sky- and sunphotometers have been developed at the Institute for Space Sciences of the Free University of Berlin in the past two decades. The latest operational developments were the multispectral aureole- and sunphotometer FUBISS-ASA2, the zenith radiometer FUBISS-ZENITH, and the nadir polarimeter AMSSP-EM, all designed for a flexible use on moving platforms like aircraft or ships. Currently the multiangle, multispectral radiometer URMS/AMSSP (Universal Radiation Measurement System/ Airborne Multispectral Sunphotometer and Polarimeter) is under construction for a Wing-Pod of the high altitude research aircraft HALO operated by DLR. The system is expected to have its first mission on HALO in 2011. The algorithms for the retrieval of aerosol and trace gas properties from the recorded multidirectional, multispectral radiation measurements allow more than deriving standard products, as for instance the aerosol optical depth and the Angstrom exponent. The radiation measured in the solar aureole contains information about the aerosol phasefunction and therefore allows conclusions about the particle type. Furthermore, airborne instrument operation allows vertically resolved measurements. An inversion algorithm, based on radiative transfer simulations and additionally including measured vertical zenith-radiance profiles, allows conclusions about the aerosol single scattering albedo and the relative soot fraction in aerosol layers. Ozone column retrieval is performed evaluating measurements from pixels in the Chappuis absorption band. A retrieval algorithm to derive the water-vapor column from the sunphotometer measurements is currently under development. Of the various airborne

  5. 微波辐射计在雷测数据折射误差修正中的应用%Application of microwave radiometer in the refractive error correction of radar measurement data

    Institute of Scientific and Technical Information of China (English)

    刘宗伟; 刘夫体; 甘友谊; 程显海

    2011-01-01

    Based on the study of atmospheric refractivity profile(RP)retrieved by microwave radiometer(MR),and compared with the radiosonde measurement data,the result indicates that the RP retrieved by MR could reflect the distribution of refractivity at the radar stations.By applying the two RP to calculate the radiowave refraction error of radar measurement data,the residual error shows that it is effective to apply the RP retrieved by MR to the radiowave refraction error correction of radar.It provides the theoretical and experimental basis for applying MR to high-precision maneuvering radar and improving the data processing precision.%基于用微波辐射计实时测量反演大气折射率剖面的研究,并与施放气象探空仪直接测量的结果进行比对,结果表明微波辐射计实时测量反演得到的大气折射率剖面能够较好地反映雷达站所在地的折射率分布。将反演和实测折射率剖面应用于某次雷达测量数据的电波折射误差计算中,由修正量比对残差分析结果得出:将微波辐射计实时测量反演的大气折射率剖面用于电波折射误差修正是有效的。为微波辐射计应用于高精度机动测控雷达,提高测量数据处理的精度提供了理论和试验依据。

  6. Ground-based Remote Sensing of Cloud Liquid Water Path

    Science.gov (United States)

    Crewell, S.; Loehnert, U.

    Within the BALTEX Cloud LIquid WAter NETwork (CLIWA-NET) measurements of cloud parameters were performed to improve/evaluate cloud parameterizations in numerical weather prediction and climate models. The key variable is the cloud liq- uid water path (LWP) which is measured by passive microwave radiometry from the ground during three two-month CLIWA-NET observational periods. Additionally to the high temporal resolution time series from the ground, LWP fields are derived from satellite measurements. During the first two campaigns a continental scale network consisting of 12 stations was established. Most stations included further cloud sen- sitive instruments like infrared radiometer and lidar ceilometer. The third campaign started with a two-week long microwave intercomparison campaign (MICAM) in Cabauw, The Netherlands, and proceeded with a regional network within a 100 by 100 km area. The presentation will focus on the accuracy of LWP derived from the ground by in- vestigating the accuracy of the microwave brightness temperature measurement and examining the LWP retrieval uncertainty. Up to now microwave radiometer are no standard instruments and the seven radiometer involved in MICAM differ in frequen- cies, bandwidths, angular resolution, integration time etc. The influence of this instru- ment specifications on the LWP retrieval will be discussed.

  7. GHRSST Level 2P Regional Subskin Sea Surface Temperature from the Tropical Rainfall Mapping Mission (TRMM) Microwave Imager (TMI) for the Atlantic Ocean (GDS version 1)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) is a well calibrated passive microwave radiometer, similar to SSM/I, that contains lower...

  8. GHRSST L2P Gridded Global Subskin Sea Surface Temperature from the Tropical Rainfall Mapping Mission (TRMM) Microwave Imager (TMI) (GDS version 1)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) is a well calibrated passive microwave radiometer, similar to SSM/I, that contains lower...

  9. GHRSST Level 2P Global Subskin Sea Surface Temperature from TRMM Microwave Imager (TMI) onboard Tropical Rainfall Measurement Mission (TRMM) satellite (GDS versions 1 and 2)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — GDS2 Version -The Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) is a well calibrated passive microwave radiometer, similar to the Special Sensor...

  10. Microwave radiometry and applications

    Science.gov (United States)

    Polívka, Jiří

    1995-09-01

    The radiometry in general is a method of detecting the radiation of matter. All material bodies and substances radiate energy in the form of electromagnetic waves according to Planck s Law. The frequency spectrum of such thermal radiation is determined, beyond the properties of a blackbody, by the emissivity of surfaces and by the temperature of a particular body. Also, its reflectivity and dispersion take part. Investigating the intensity of radiation and its spectral distribution, one may determine the temperature and characterize the radiating body as well as the ambient medium, all independently of distance. With the above possibilities, the radiometry represents a base of scientific method called remote sensing. Utilizing various models, temperature of distant bodies and images of observed scenes can be determined from the spatial distribution of radiation. In this method, two parameters are of paramount importance: the temperature resolution, which flows out from the detected energy, and the spatial resolution (or, angular resolution), which depends upon antenna size with respect to wavelength. An instrument usable to conduct radiometric observations thus consists of two basic elements: a detector or radiometer, which determines the temperature resolution, and an antenna which determines the angular or spatial resolution. For example, a photographic camera consists of an objective lens (antenna) and of a sensitive element (a film or a CCD). In remote sensing, different lenses and reflectors and different sensors are employed, both adjusted to a particular spectrum region in which certain important features of observed bodies and scenes are present: frequently, UV and IR bands are used. The microwave radiometry utilizes various types of antennas and detectors and provides some advantages in observing various scenes: the temperature resolution is recently being given in milikelvins, while the range extends from zero to millions of Kelvins. Microwaves also offer

  11. Microwave synthesis of Titanium Dioxide nanotubes for use in water treatment

    CSIR Research Space (South Africa)

    Sikhwivhilu, L

    2010-09-01

    Full Text Available during hydrothermal processing2,3. In our study, TiO2 nanostructures are synthesised using conventional heating and microwave-assisted hydrothermal procedure. The effects of heating on the size, shape and crystallinity of materials are studied. Microwave...

  12. Imaging radiometers employing linear thermoelectric arrays

    Science.gov (United States)

    McManus, Timothy J.; Mickelson, Steve

    1999-07-01

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

  13. The influence of Glassex additive on properties of microwave-hardened and self- hardened moulding sands with water glass

    Directory of Open Access Journals (Sweden)

    K. Major-Gabryś

    2012-01-01

    Full Text Available The article takes into consideration the researches concerning inserting the Glassex additive to the microwaved-hardened and self- hardened moulding sands with water glass. In the research different types of ester hardeners to self-hardened moulding sands with water glass were used. The influence of Glassex additive on retained strength of moulding sands with different hardeners and prepared by different technologies of hardening were tested. The influence of different hardeners and the technology of hardening on retained strength of moulding sand with water glass and the Glassex additive were also estimated.

  14. The microwave opacity of ammonia and water vapor: Application to remote sensing of the atmosphere of Jupiter

    Science.gov (United States)

    Hanley, Thomas Ryan

    2008-06-01

    The object of this research program has been to provide a baseline for microwave remote sensing of ammonia and water vapor in the atmosphere of Jupiter through laboratory measurements of their microwave absorption properties. Jupiter is not only the largest planet in our solar system, but one of the most interesting and complex. Despite a handful of spacecraft missions and many astronomical measurements, much of Jupiter's atmospheric dynamics and composition remain a mystery. Although constraints have been formed on the amount of certain gases present, the global abundances and distributions of water vapor (H 2 O) and ammonia (NH 3 ) are relatively unknown. Measurements of H 2 O and NH 3 in the Jovian atmosphere to hundreds of bars of pressure are best accomplished via passive microwave emission measurements. For these measurements to be accurately interpreted, however, the hydrogen and helium pressure-broadened microwave opacities of H 2 O and NH 3 must be well characterized, a task that is very difficult if based solely on theory and limited laboratory measurements. Therefore, accurate laboratory measurements have been taken under a broad range of conditions that mimic those of the Jovian atmosphere. These measurements, performed using a newly redesigned high- accuracy system, and the corresponding models of microwave opacity that have been developed from them comprise the majority of this work. The models allow more accurate retrievals of H 2 O and NH 3 abundances from previous as well as future missions to Jupiter and the outer planets, such as the NASA New Frontiers class Juno mission scheduled for launch in 2011. This information will enable a greater understanding of the concentration and distribution of H 2 O and NH 3 in the Jovian atmosphere, which will reveal much about how Jupiter and our solar system formed and how similar planets could form in other solar systems, even planets that may be hospitable to life.

  15. Field campaign LINEX 96/1 - possibilities of water vapor observation in the free atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Steinhagen, H.; Dier, H.; Engelbart, D.; Goersdorf, U.; Lehmann, V.; Leiterer, U.; Neisser, J. [Deutscher Wetterdienst, Lindenberg (Germany). Meteorologisches Observatorium; Bakan, S. [Hamburg Univ. (Germany). Meteorologisches Inst.; Boesenberg, J.; Jansen, F.; Wulfmeyer, V. [Max-Planck-Institut fuer Meteorologie, Hamburg (Germany); Fischer, J. [Freie Univ. Berlin (Germany). Inst. fuer Weltraumwissenschaften; Gendt, G. [GeoForschungsZentrum Potsdam (Germany); Gueldner, J. [Deutscher Wetterdienst, Potsdam (Germany). Meteorologisches Observatorium

    1998-12-01

    LINEX 96/1 was a field experiment to assess information content, accuracy, and availability for different remote sensing techniques measuring water vapor. An important goal of LINEX 96/1 was the test of a new differential absorption lidar (DIAL) developed by the MPI fuer meteorologie Hamburg. Comparisons of DIAL with rawinsonde and tethersonde measurements showed an excellent accuracy of the DIAL method in the determination of water vapor with high vertical and temporal resolution. The operation of the microwave radiometer WVR-1100 showed a high availability of water vapor and liquid water column content measurements except during rain. Microwave radiometers are reliable systems to measure the precipitable water vapor and liquid water content under unattended operational conditions with high accuracy and temporal resolution. Measurements of the water vapor column content by ground-based GPS receivers proved highly reliable. Comparisons with corresponding values of the microwave radiometer showed a bias less than 0.6 mm and a standard deviation less than 0.9 mm. The main problem of an operational use of this new information is that the evaluated data are not available in real-time because, at present, the data have to be postprocessed in a ground control center. During LINEX 96/1, possibilities for estimation of water vapor column content from sun and star photometer measurements were also demonstrated. The comparison of the precipitable water vapor content measurements of sun and star photometers, microwave radiometer, and rawinsondes RS 80 showed a good agreement. Unfortunately, the use of optical methods like sun and star photometers is restricted by cloudy conditions. 28 refs.

  16. Atom-efficient coupling reaction of aryl bromideswith sodium tetraphenylborate catalyzed by reusable Pd/C in water under focused microwave irradiation

    Institute of Scientific and Technical Information of China (English)

    Lin Bai

    2009-01-01

    A rapid and heterogeneous Pal/C-catalyzed atom-efficient phenylation of aryl bromides by sodium tetraphenylborate takes place under focused microwave irradiation in water.The palladium catalyst can be easily recovered and reused.

  17. Microwave-assisted synthesis of spheroidal vaterite CaCO 3 in ethylene glycol-water mixed solvents without surfactants

    Science.gov (United States)

    Chen, Yinxia; Ji, Xianbing; Wang, Xiaobo

    2010-10-01

    Spheroidal vaterite CaCO 3 composed of irregular nanoparticals have been synthesized by a fast microwave-assisted method. The structures are fabricated by the reaction of Ca(CH 3COO) 2 with (NH 4) 2CO 3 at 90 °C in ethylene glycol-water mixed solvents without any surfactants. The diameters of the spheroidal vaterite CaCO 3 range from 1 to 2 μm, and the average size of the nanoparticals is about 70 nm. Bundle-shaped aragonite and rhombohedral calcite are also obtained by adjusting the experimental parameters. Our experiments show that the ratio of ethylene glycol to water, microwave power, reaction time, and two sources of ammonium ions and acetate anions are key parameters for the fabrication of spheroidal vaterite CaCO 3. A possible growth mechanism for the spheroidal structures has been proposed, which suggests that the spheroidal vaterite CaCO 3 is formed by an aggregation mechanism.

  18. Advanced modelling of the Planck-LFI radiometers

    Energy Technology Data Exchange (ETDEWEB)

    Battaglia, P [Thales Alenia Space Italia S.p.A., S.S. Padana Superiore 290, 20090 Vimodrone (Italy); Franceschet, C; Bersanelli, M; Maino, D; Mennella, A [Universita di Milano, Dipartimento di Fisica, Via G. Celoria 16, I-20133 Milano (Italy); Zonca, A [INAF-IASF Milano, Via E. Bassini 15, I-20133 Milano (Italy); Butler, R C; Mandolesi, N [INAF-IASF Bologna, Via P. Gobetti, 101, I-40129 Bologna (Italy); D' Arcangelo, O; Platania, P [IFP-CNR, via Cozzi 53, 20125 Milano (Italy); Davis, R J [Jodrell Bank Centre for Astrophysics, Alan Turing Building, The University of Manchester, Manchester, M13 9PL (United Kingdom); Galeotta, S [INAF-OATs, Via G.B. Tiepolo 11, I-34131, Trieste (Italy); Guzzi, P [Numonyx, R and D Technology Center, Via C. Olivetti 2, 20041 Agrate Brianza (Italy); Hoyland, R [Instituto de AstrofIsica de Canarias, C/ Via Lactea S/N, E-38200, La Laguna (Tenerife) (Spain); Hughes, N; Jukkala, P [DA-Design Oy Jokioinen (Finland); Kettle, D [School of Electrical and Electronic Engineering, University of Manchester, Manchester, M60 1QD (United Kingdom); Laaninen, M [Ylinen Electronics Oy Kauniainen (Finland); Leonardi, R; Meinhold, P, E-mail: paola.battaglia@thalesaleniaspace.co [Department of Physics, University of California, Santa Barbara, CA 93106-9530 (United States)

    2009-12-15

    The Low Frequency Instrument (LFI) is a radiometer array covering the 30-70 GHz spectral range on-board the ESA Planck satellite, launched on May 14th, 2009 to observe the cosmic microwave background (CMB) with unprecedented precision. In this paper we describe the development and validation of a software model of the LFI pseudo-correlation receivers which enables to reproduce and predict all the main system parameters of interest as measured at each of the 44 LFI detectors. These include system total gain, noise temperature, band-pass response, non-linear response. The LFI Advanced RF Model (LARFM) has been constructed by using commercial software tools and data of each radiometer component as measured at single unit level. The LARFM has been successfully used to reproduce the LFI behavior observed during the LFI ground-test campaign. The model is an essential element in the database of LFI data processing center and will be available for any detailed study of radiometer behaviour during the survey.

  19. Single-step microwave-assisted hot water extraction of hemicelluloses from selected lignocellulosic materials - A biorefinery approach.

    Science.gov (United States)

    Mihiretu, Gezahegn T; Brodin, Malin; Chimphango, Annie F; Øyaas, Karin; Hoff, Bård H; Görgens, Johann F

    2017-10-01

    The viability of single-step microwave-induced pressurized hot water conditions for co-production of xylan-based biopolymers and bioethanol from aspenwood sawdust and sugarcane trash was investigated. Extraction of hemicelluloses was conducted using microwave-assisted pressurized hot water system. The effects of temperature and time on extraction yield and enzymatic digestibility of resulting solids were determined. Temperatures between 170-200°C for aspenwood and 165-195°C for sugarcane trash; retention times between 8-22min for both feedstocks, were selected for optimization purpose. Maximum xylan extraction yields of 66 and 50%, and highest cellulose digestibilities of 78 and 74%, were attained for aspenwood and sugarcane trash respectively. Monomeric xylose yields for both feedstocks were below 7%, showing that the xylan extracts were predominantly in non-monomeric form. Thus, single-step microwave-assisted hot water method is viable biorefinery approach to extract xylan from lignocelluloses while rendering the solid residues sufficiently digestible for ethanol production. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Influence of System Variables on the Heating Characteristics of Water during Continuous Flow Microwave Heating

    Directory of Open Access Journals (Sweden)

    Hosahalli S. Ramaswamy

    2011-01-01

    Full Text Available A domestic microwave oven (1000 W was modified to permit the continuous flow of liquids run through a helical coil centrally located inside the oven cavity. Heating characteristics were evaluated by measuring inlet and outlet temperatures of coil as a function of system variables. The influence of number of turns, coil diameter, tube diameter, pitch and initial temperature were evaluated at different flow rates. The average residence time of water was computed by dividing the coil volume by the volumetric flow rate. The influence of Dean number was evaluated. Results from this study showed that (1 higher number of turns resulted in lower heating rate, lower temperature fluctuations, higher exit temperature and longer time to achieve temperature equilibrium; (2 larger tube or coil diameter gave larger coil volume causing the heating rate to decrease; (3 faster flow rates resulted in lower exit temperatures, lower temperature fluctuation, higher Dean number and slightly higher heating rate; (4 higher initial temperatures resulted in higher exit temperatures; (5 higher Dean number resulted in more uniform heating and slightly higher heating rate. Overall, the coil volume was the more dominant factor affecting heating rate as compared with flow rate and Dean number.

  1. Ballistic Protons and Microwave-induced Water Solitons in Bioenergetic Transformations

    Directory of Open Access Journals (Sweden)

    Reuven Tirosh

    2006-09-01

    Full Text Available Active streaming (AS of liquid water is considered to generate and overcomepressure gradients, so as to drive cell motility and muscle contraction by hydrauliccompression. This idea had led to reconstitution of cytoplasm streaming and musclecontraction by utilizing the actin-myosin ATPase system in conditions that exclude acontinuous protein network. These reconstitution experiments had disproved a contractileprotein mechanism and inspired a theoretical investigation of the AS hypothesis, aspresented in this article. Here, a molecular quantitative model is constructed for a chemicalreaction that might generate the elementary component of such AS within the pure waterphase. Being guided by the laws of energy and momentum conservation and by the physicalchemistry of water, a vectorial electro-mechano-chemical conversion is considered, asfollows: A ballistic H+ may be released from H2O-H+ at a velocity of 10km/sec, carrying akinetic energy of 0.5 proton*volt. By coherent exchange of microwave photons during 10-10sec, the ballistic proton can induce cooperative precession of about 13300 electrically-polarized water molecule dimers, extending along 0.5 μm. The dynamic dimers rearrangealong the proton path into a pile of non-radiating rings that compose a persistent rowing-likewater soliton. During a life-time of 20 msec, this soliton can generate and overcome amaximal pressure head of 1 kgwt/cm2 at a streaming velocity of 25 μm/sec and intrinsicpower density of 5 Watt/cm3. In this view, the actin-myosin ATPase is proposed to catalyzestereo-specific cleavage of H2O-H+ , so as to generate unidirectional fluxes of ballisticprotons and water solitons along each actin filament. Critical requirements and evidentialpredictions precipitate consistent implications to the physical chemistry of water, enzymatichydrolysis and synthesis of ATP, trans-membrane signaling, intracellular transport, cellmotility, intercellular interaction, and associated

  2. Cloud Top Scanning radiometer (CTS)

    Science.gov (United States)

    1978-01-01

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

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

    Directory of Open Access Journals (Sweden)

    C. Pettersen

    2015-12-01

    Full Text Available Multi-instrument, ground-based measurements provide unique and comprehensive datasets of the atmosphere for a specific location over long periods of time and resulting data compliments past and existing global satellite observations. This 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 2010–2013. 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−2 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 225 GHz. 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. This measured ice signature was then compared to an equivalent brightness temperature difference calculated with a radiative transfer model including microwave single scattering properties for several ice habits. Initial model results compare well against the four years of summer season isolated ice signature in the high-frequency microwave channels.

  4. Atmospheric correction for sea surface temperature retrieval from single thermal channel radiometer data onboard Kalpana satellite

    Science.gov (United States)

    Shahi, Naveen R.; Agarwal, Neeraj; Mathur, Aloke K.; Sarkar, Abhijit

    2011-06-01

    An atmospheric correction method has been applied on sea surface temperature (SST) retrieval algorithm using Very High Resolution Radiometer (VHRR) single window channel radiance data onboard Kalpana satellite (K-SAT). The technique makes use of concurrent water vapour fields available from Microwave Imager onboard Tropical Rainfall Measuring Mission (TRMM/TMI) satellite. Total water vapour content and satellite zenith angle dependent SST retrieval algorithm has been developed using Radiative Transfer Model [MODTRAN ver3.0] simulations for Kalpana 10.5-12.5 μm thermal window channel. Retrieval of Kalpana SST (K-SST) has been carried out for every half-hourly acquisition of Kalpana data for the year 2008 to cover whole annual cycle of SST over Indian Ocean (IO). Validation of the retrieved corrected SST has been carried out using near-simultaneous observations of ship and buoys datasets covering Arabian Sea, Bay of Bengal and IO regions. A significant improvement in Root Mean Square Deviation (RMSD) of K-SST with respect to buoy (1.50-1.02 K) and to ship datasets (1.41-1.19 K) is seen with the use of near real-time water vapour fields of TMI. Furthermore, comparison of the retrieved SST has also been carried out using near simultaneous observations of TRMM/TMI SST over IO regions. The analysis shows that K-SST has overall cold bias of 1.17 K and an RMSD of 1.09 K after bias correction.

  5. Microwave-assisted convenient synthesis of N-arylpyrrolidines in water

    Institute of Scientific and Technical Information of China (English)

    Hong Bo Li; Wu Liang; Lang Liu; Kai Chen; Yi Wu

    2011-01-01

    An efficient and clean synthesis of N-arylpyrrolidines from arylamines and 1,4-dimesyloxybutane was developed using microwave irradiation in an aqueous potassium carbonate medium without any catalyst. The procedure is rapid, simple and convenient.

  6. Estimation of global snow cover using passive microwave data

    Science.gov (United States)

    Chang, Alfred T. C.; Kelly, Richard E.; Foster, James L.; Hall, Dorothy K.

    2003-04-01

    This paper describes an approach to estimate global snow cover using satellite passive microwave data. Snow cover is detected using the high frequency scattering signal from natural microwave radiation, which is observed by passive microwave instruments. Developed for the retrieval of global snow depth and snow water equivalent using Advanced Microwave Scanning Radiometer EOS (AMSR-E), the algorithm uses passive microwave radiation along with a microwave emission model and a snow grain growth model to estimate snow depth. The microwave emission model is based on the Dense Media Radiative Transfer (DMRT) model that uses the quasi-crystalline approach and sticky particle theory to predict the brightness temperature from a single layered snowpack. The grain growth model is a generic single layer model based on an empirical approach to predict snow grain size evolution with time. Gridding to the 25 km EASE-grid projection, a daily record of Special Sensor Microwave Imager (SSM/I) snow depth estimates was generated for December 2000 to March 2001. The estimates are tested using ground measurements from two continental-scale river catchments (Nelson River and the Ob River in Russia). This regional-scale testing of the algorithm shows that for passive microwave estimates, the average daily snow depth retrieval standard error between estimated and measured snow depths ranges from 0 cm to 40 cm of point observations. Bias characteristics are different for each basin. A fraction of the error is related to uncertainties about the grain growth initialization states and uncertainties about grain size changes through the winter season that directly affect the parameterization of the snow depth estimation in the DMRT model. Also, the algorithm does not include a correction for forest cover and this effect is clearly observed in the retrieval. Finally, error is also related to scale differences between in situ ground measurements and area-integrated satellite estimates. With AMSR

  7. Weak microwave can alleviate water deficit induced by osmotic stress in wheat seedlings.

    Science.gov (United States)

    Chen, Yi-Ping; Jia, Jing-Fen; Han, Xiao-Ling

    2009-01-01

    The aim of the investigation is to determine the effect of microwave pretreatment of wheat seeds on the resistance of seedlings to osmotic stress. Changes in biophysical, physiological and biochemical characters were measured. The results showed: (1) The magnetic field intensity and seeds temperature increased progressively with microwave pretreatments of 5, 10, 15, 20 s and 25 s compared with controls. Although each microwave pretreatment resulted in an increase in alpha-amylase activity and photon emission intensity, the increase of alpha-amylase activity and photon emission intensity was maximal at a microwave pretreatment of 10 s. (2) Osmotic stress induced by PEG treatment enhanced the concentration of malondialdehyde, while decreasing the activities of nitricoxide synthase, catalase, peroxidase, superoxide dismutase and the concentration of nitric oxide, ascorbic acid, glutathione in the seedlings compared with controls. However, compared to osmotic stress alone, in the seedlings treated with microwave irradiation plus osmotic stress the concentration of malondialdehyde decreased, while the activities of nitricoxide synthase, catalase, peroxidase, superoxide dismutase and the concentration of nitric oxide, ascorbic acid and glutathione increased. These results suggest that a suitable dose of microwave radiation can enhance the capability to eliminate free radicals induced by osmotic stress in wheat seedlings resulting in an increase in resistance to osmotic stress.

  8. Global Snow Mass Measurements and the Effect of Stratigraphic Detail on Inversion of Microwave Brightness Temperatures

    Science.gov (United States)

    Richardson, Mark; Davenport, Ian; Gurney, Robert

    2014-05-01

    Snow provides large seasonal storage of freshwater, and information about the distribution of snow mass as snow water equivalent (SWE) is important for hydrological planning and detecting climate change impacts. Large regional disagreements remain between estimates from reanalyses, remote sensing and modelling. Assimilating passive microwave information improves SWE estimates in many regions, but the assimilation must account for how microwave scattering depends on snow stratigraphy. Physical snow models can estimate snow stratigraphy, but users must consider the computational expense of model complexity versus acceptable errors. Using data from the National Aeronautics and Space Administration Cold Land Processes Experiment and the Helsinki University of Technology microwave emission model of layered snowpacks, it is shown that simulations of the brightness temperature difference between 19 and 37 GHz vertically polarised microwaves are consistent with advanced microwave scanning radiometer-earth observing system and special sensor microwave imager retrievals once known stratigraphic information is used. Simulated brightness temperature differences for an individual snow profile depend on the provided stratigraphic detail. Relative to a profile defined at the 10-cm resolution of density and temperature measurements, the error introduced by simplification to a single layer of average properties increases approximately linearly with snow mass. If this brightness temperature error is converted into SWE using a traditional retrieval method, then it is equivalent to ±13 mm SWE (7 % of total) at a depth of 100 cm. This error is reduced to ±5.6 mm SWE (3 % of total) for a two-layer model.

  9. Retrieval assessment using the microwave simulation tool for the High Altitude and LOng range aircraft HALO: humidity, temperature and hydrometeor profiles

    Science.gov (United States)

    Mech, M.; Crewell, S.; Orlandi, E.; Hirsch, L.

    2011-12-01

    New cloud observation techniques are needed to improve our understanding of the impact of clouds on the Earth's water cycle and radiation budget, which still represents one of the largest uncertainties in global and regional climate modelling. An airborne platform for such observation techniques will be provided by the new German research aircraft HALO (High Altitude LOng Range). In early 2013 a dedicated remote sensing mission NARVAL employing the microwave package HAMP (HALO Microwave Package; 36 channels microwave radiometer and 35.5 GHz Doppler radar), wind and water vapour lidar as well as auxiliary measurements will invest cloud systems in the North Atlantic in much higher detail than feasible on space-borne platforms. An advanced set of microwave remote cloud sensing instruments is to be operated on board of HALO. It consists of a cloud radar and a suite of passive radiometers in different frequency bands. The radar MIRA-36 operates at 35.5 GHz. The frequencies for the passive microwave radiometers were selected in allusion to the AMSU-A and -B sounder. In addition to the channels along the 60 GHz oxygen complex measurements along the 118 GHz oxygen line hint at the vertical distribution of liquid water that show a strong emission increase with frequency. This combination can be used for precipitation retrieval. In addition to include channels in the water vapor lines at 22.235 GHz and 183.31 GHz, information about the water vapor distribution throughout the troposphere can be retrieved. By including higher microwave channels sensitive to scattering in the ice phase various precipitation retrieval algorithms can be compared with measurements from HAMP. Retrieval algorithms and potential flight patterns are investigated using a simulation test bed combining cloud model and radiative transfer simulations. Thereby the cloud resolving model simulations and the forward radiative transfer calculations include a one- and two-moment cloud microphysical scheme with

  10. Research of MMW radiometer virtual prototyping technology

    Institute of Scientific and Technical Information of China (English)

    Fan Qinghui; Li Xingguo; Zhang Guangfeng

    2008-01-01

    The idea of millimeter-wave (MMW) radiometer virtual prototyping is discussed in this paper. Designing en-vironment, designing method and the main modeling components of virtual MMW radiometer are researched. Important external parameters, which have significant influence to composing system, are used to components modeling, and then components are taken to buildup virtual MMW radiometer system. Moreover, the effect to output is contrasted whether there is a low-noise amplifier or not.

  11. Low cost and conformal microwave water-cut sensor for optimizing oil production process

    KAUST Repository

    Karimi, Muhammad Akram

    2015-08-01

    Efficient oil production and refining processes require the precise measurement of water content in oil (i.e., water-cut) which is extracted out of a production well as a byproduct. Traditional water-cut (WC) laboratory measurements are precise, but are incapable of providing real-time information, while recently reported in-line WC sensors (both in research and industry) are usually incapable of sensing the full WC range (0 – 100 %), are bulky, expensive and non-scalable for the variety of pipe sizes used in the oil industry. This work presents a novel implementation of a planar microwave T-resonator for fully non-intrusive in situ WC sensing over the full range of operation, i.e., 0 – 100 %. As opposed to non-planar resonators, the choice of a planar resonator has enabled its direct implementation on the pipe surface using low cost fabrication methods. WC sensors make use of series resonance introduced by a λ/4 open shunt stub placed in the middle of a microstrip line. The detection mechanism is based on the measurement of the T-resonator’s resonance frequency, which varies with the relative percentage of oil and water (due to the difference in their dielectric properties). In order to implement the planar T-resonator based sensor on the curved surface of the pipe, a novel approach of utilizing two ground planes is proposed in this work. The innovative use of dual ground planes makes this sensor scalable to a wide range of pipe sizes present in the oil industry. The design and optimization of this sensor was performed in an electromagnetic Finite Element Method (FEM) solver, i.e., High Frequency Structural Simulator (HFSS) and the dielectric properties of oil, water and their emulsions of different WCs used in the simulation model were measured using a SPEAG-dielectric assessment kit (DAK-12). The simulation results were validated through characterization of fabricated prototypes. Initial rapid prototyping was completed using copper tape, after which a

  12. Effects of Atmospheric Water Vapor and Clouds on NOAA (National Oceanic and Atmospheric Administration) AVHRR (Advanced Very High Resolution Radiometer) Satellite Data.

    Science.gov (United States)

    1984-07-01

    smoke , smog, dust and water ;erosols usually falls within the Mie Regime. The combination of Rayleigh and Mie scattering causes the selective...T. L., 1984. Department of Commerce, NOAA, NESDIS, Assesment Services Center, Columbia, MO, Personal Communications. Barnett, T. L. and Thompson, D...Washington, D.C., NOAA Technical Memorandum, NESS 107, 73 pp. LeDuc, S. K., 1984. U.S. Department of Commerce, NOAA, NESDIS, Assesment Information Services

  13. Sky Radiometers on Stand for Downwelling Radiation

    Data.gov (United States)

    Oak Ridge National Laboratory — The Sky Radiation (SKYRAD) collection of radiometers provides each Atmospheric Radiation and Cloud Station (ARCS) with continuous measurements of broadband shortwave...

  14. Millimeter-Wave Radiometer Imager

    Science.gov (United States)

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

    1988-01-01

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

  15. Passive microwave soil moisture research

    Science.gov (United States)

    Schmugge, T.; Oneill, P. E.; Wang, J. R.

    1986-01-01

    During the four years of the AgRISTARS Program, significant progress was made in quantifying the capabilities of microwave sensors for the remote sensing of soil moisture. In this paper, a discussion is provided of the results of numerous field and aircraft experiments, analysis of spacecraft data, and modeling activities which examined the various noise factors such as roughness and vegetation that affect the interpretability of microwave emission measurements. While determining that a 21-cm wavelength radiometer was the best single sensor for soil moisture research, these studies demonstrated that a multisensor approach will provide more accurate soil moisture information for a wider range of naturally occurring conditions.

  16. Surface Wind Vector and Rain Rate Observation Capability of Future Hurricane Imaging Radiometer (HIRAD)

    Science.gov (United States)

    Miller, Timothy; Atlas, Robert; Bailey, M. C.; Black, Peter; El-Nimri, Salem; Hood, Robbie; James, Mark; Johnson, James; Jones, Linwood; Ruf, Christopher; Uhlhorn, Eric

    2009-01-01

    The Hurricane Imaging Radiometer (HIRAD) is the next-generation Stepped Frequency Microwave Radiometer (SFMR), and it will offer the capability of simultaneous wide-swath observations of both extreme ocean surface wind vector and strong precipitation from either aircraft (including UAS) or satellite platforms. HIRAD will be a compact, lightweight, low-power instrument with no moving parts that will produce valid wind observations under hurricane conditions when existing microwave sensors (radiometers or scatterometers) are hindered by precipitation. The SFMR i s a proven aircraft remote sensing system for simultaneously observing extreme ocean surface wind speeds and rain rates, including those of major hurricane intensity. The proposed HIRAD instrument advances beyond the current nadir viewing SFMR to an equivalent wide-swath SFMR imager using passive microwave synthetic thinned aperture radiometer technology. The first version of the instrument will be a single polarization system for wind speed and rain rate, with a dual-polarization system to follow for wind vector capability. This sensor will operate over 4-7 GHz (C-band frequencies) where the required tropical cyclone remote sensing physics has been validated by both SFMR and WindSat radiometers. HIRAD incorporates a unique, technologically advanced array antenna and several other technologies successfully demonstrated by NASA s Instrument Incubator Program. A brassboard (laboratory) version of the instrument has been completed and successfully tested in a test chamber. Development of the aircraft instrument is underway, with flight testing planned for the fall of 2009. Preliminary Observing System Simulation Experiments (OSSEs) show that HIRAD will have a significant positive impact on surface wind analyses as either a new aircraft or satellite sensor. New off-nadir data collected in 2008 by SFMR that affirms the ability of this measurement technique to obtain wind speed data at non-zero incidence angle will

  17. Analysis of RFI Identification and Mitigation in CAROLS Radiometer Data Using a Hardware Spectrum Analyser

    Directory of Open Access Journals (Sweden)

    Christophe Caudoux

    2011-03-01

    Full Text Available A method to identify and mitigate radio frequency interference (RFI in microwave radiometry based on the use of a spectrum analyzer has been developed. This method has been tested with CAROLS L-band airborne radiometer data that are strongly corrupted by RFI. RFI is a major limiting factor in passive microwave remote sensing interpretation. Although the 1.400–1.427 GHz bandwidth is protected, RFI sources close to these frequencies are still capable of corrupting radiometric measurements. In order to reduce the detrimental effects of RFI on brightness temperature measurements, a new spectrum analyzer has been added to the CAROLS radiometer system. A post processing algorithm is proposed, based on selective filters within the useful bandwidth divided into sub-bands. Two discriminant analyses based on the computation of kurtosis and Euclidian distances have been compared evaluated and validated in order to accurately separate the RF interference from natural signals.

  18. Technique for Radiometer and Antenna Array Calibration with Two Antenna Noise Diodes

    Science.gov (United States)

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

    2011-01-01

    This paper presents a new technique to calibrate a microwave radiometer and phased array antenna system. This calibration technique uses a radiated noise source in addition to an injected noise sources for calibration. The plane of reference for this calibration technique is the face of the antenna and therefore can effectively calibration the gain fluctuations in the active phased array antennas. This paper gives the mathematical formulation for the technique and discusses the improvements brought by the method over the existing calibration techniques.

  19. Determination of application possibilities of microwave heating in the curing process of water glass molding sands with fluid esters. Part 1

    Directory of Open Access Journals (Sweden)

    K. Granat

    2009-01-01

    Full Text Available This article presents results of the experimental trial of combination of the chemical method of water glass molding sands’ curing, used in foundry industry, with an innovative microwave heating. The research objective was to indicate at new areas of microwave energy application. The sands prepared, according to recommendations for curing technology, with the use of ethylene glycol diacetate, have been subject to microwave influence. The attempt at determination of microwave influence on qualitative changes of the binding bridges created during the curing process concerned such parameters as: bending and tensile strength, permeability as well as wear resistance. Moreover,we also determined the influence of microwave curing on the phenomena accompanying the process as well as bond stability (storage time of the prepared molding and core sands. It has been found, basing on the result analysis, that the innovative microwave heating might constitute a very good supplementation of the ester curing method. The advantages of the combined chemical and microwave gelation process include, among others, improvement of the described resistance and technological parameters as well as significant decrease of preparation time of foundry moulds and cores. The subject discussed in this article will be continued in its second part.

  20. Measuring the instrument function of radiometers

    Energy Technology Data Exchange (ETDEWEB)

    Winston, R. [Univ. of Chicago, IL (United States); Littlejohn, R.G. [Univ. of California, Berkeley, CA (United States)

    1997-12-31

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

  1. System for Control,Data Collection and Processing in 8 mm Portable Microwave Radiometer—Scatterometer

    Institute of Scientific and Technical Information of China (English)

    李毅; 方振和; 等

    2002-01-01

    In this paper we describe a system used to control,collect and process data in 8mm portable microwave radiometer-scatterometer,We focus on hardware and software design of the system based on a PIC16F874 chip.The system has been successfully used in an 8mm portable microwave radiometer-scatterometer,compared with other similar systems,the system modularization miniatureization and intelligentization are improved so as to meet portable instrument requirements.

  2. Statistical Analysis of the Correlation between Microwave Emission Anomalies and Seismic Activity Based on AMSR-E Satellite Data

    Science.gov (United States)

    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

  3. Characterization of Different Land Classes and Disaster Monitoring Using Microwave Land Emissivity for the Indian Subcontinent

    Science.gov (United States)

    Saha, Korak; Raju, Suresh; Antony, Tinu; Krishna Moorthy, K.

    Despite the ability of satellite borne microwave radiometers to measure the atmospheric pa-rameters, liquid water and the microphysical properties of clouds, they have serious limitations over the land owing its large and spatially heterogeneous emissivity compared to the relatively low and homogenous oceans. This calls for determination of the spatial maps of land-surface emissivity with accuracies better than ˜2%. In this study, the characterization of microwave emissivity of different land surface classes over the Indian region is carried out with the forth-coming Indo-French microwave satellite program Megha-Tropiques in focus. The land emissivity is retrieved using satellite microwave radiometer data from Special Sensor Microwave/Imager (SSM/I) and TRMM Microwave Imager (TMI) at 10, 19, 22, 37 and 85 GHz. After identify-ing the clear sky daily data, the microwave radiative transfer computation, is applied to the respective daily atmospheric profile for deducing the upwelling and downwelling atmospheric radiations. This, along with the skin temperature data, is used to retrieve land emission from satellites data. The emissivity maps of placecountry-regionIndia for three months representing winter (January) and post-monsoon (September-October) seasons of 2008 at V and H polar-izations of all the channels (except for 22 GHz) are generated. Though the land emissivity values in V-polarization vary between 0.5 and ˜1, some land surface classes such as the desert region, marshy land, fresh snow covered region and evergreen forest region, etc, show distinct emissivity characteristics. On this basis few typical classes having uniform physical properties over sufficient area are identified. Usually the Indian desert region is dry and shows low emis-sivity (˜0.88 in H-polarisation) and high polarization difference, V-H (˜0.1). Densely vegetated zones of tropical rain forests exhibit high emissivity values (˜0.95) and low polarization dif-ference (lt;0.01). The

  4. The High Altitude MMIC Sounding Radiometer on the GLOBAL HAWK: From Technology Development to Science Discovery

    Science.gov (United States)

    Brown, Shannon; Denning, Richard; Lambrigtsen, Bjorn; Lim, Boon; Tanabe, Jordan; Tanner, Alan

    2013-01-01

    This paper presents results from the High Altitude MMIC Sounding Radiometer (HAMSR) during three recent field campaigns on the Global Hawk Unmanned Ariel Vehicles (UAV), focusing on the enabling technology that led to unprecedented observations of significant weather phenomenon, such as thermodynamic evolution of the tropical cyclone core during rapid intensification and the high resolution three dimensional mapping of several atmospheric river events. HAMSR is a 25 channel cross-track scanning microwave sounder with channels near the 60 and 118 GHz oxygen lines and the 183 GHz water vapor line. HAMSR was originally designed and built at the Jet Propulsion Laboratory as a technology demonstrator in 1998. Subsequent to this, HAMSR participated in three NASA hurricane field campaigns, CAMEX-4, TCSP and NAMMA. Beginning in 2008, HAMSR was extensively upgraded to deploy on the NASA Global Hawk (GH) platform and serve as an asset to the NASA sub-orbital program. HAMSR has participated on the Global Hawk during the 2010 Genesis and Rapid Intensification (GRIP) campaign, the 2011 Winter Storms and Atmospheric Rivers (WISPAR) campaign and is currently participating in the NASA Ventures Hurricane and Severe Storm Sentinel (HS3) campaign (2011-2015).

  5. On direct passive microwave remote sensing of sea spray aerosol production

    Directory of Open Access Journals (Sweden)

    I. B. Savelyev

    2014-06-01

    Full Text Available This study addresses and attempts to mitigate persistent uncertainty and scatter among existing approaches for determining the rate of sea spray aerosol production by breaking waves in the open ocean. The new approach proposed here utilizes passive microwave emissions from the ocean surface, which are known to be sensitive to surface roughness and foam. Direct, simultaneous, and collocated measurements of the aerosol production and microwave emissions were collected on-board FLoating Instrument Platform (FLIP in deep water ∼150 km off the coast of California over a period of ∼4 days. Vertical profiles of coarse-mode aerosol (0.25–23.5 μm concentrations were measured with a forward scattering spectrometer and converted to surface flux using dry deposition and vertical gradient methods. Back trajectory analysis of Northeast Pacific meteorology verified the clean marine origin of the sampled air mass over at least 5 days prior to measurements. Vertical and horizontal polarization surface brightness temperatures were measured with a microwave radiometer at 10.7 GHz frequency. Data analysis revealed a strong sensitivity of the brightness temperature polarization difference to the rate of aerosol production. An existing model of microwave emission from the ocean surface was used to determine the empirical relationship and to attribute its underlying physical basis to microwave emissions from surface roughness and foam within active and passive phases of breaking waves. A possibility of and initial steps towards satellite retrievals of the sea spray aerosol production are briefly discussed in concluding remarks.

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

    Science.gov (United States)

    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.

  7. HAMP - the microwave package on the upcoming High Altitude and LOng range aircraft HALO

    Science.gov (United States)

    Mech, M.; Crewell, S.; Peters, G.; Hirsch, L.

    2009-04-01

    New cloud observation techniques are needed to improve our understanding of the impact of clouds on the earth's water cycle and radiation budget, which represents still one of the largest uncertainties in global and regional climate modeling. An airborne platform for such observation techniques will be provided by the new German research aircraft HALO (High Altitude Long Range) that will be commissioned in 2009. HALO will open a new dimension for climate and atmospheric research. By HALO it will be possible to survey the atmosphere on continental scales but with much finer resolution and with more powerful instrumentation than feasible on space borne platforms. An advanced set of microwave remote cloud sensing instruments (HAMP - HALO Microwave Package) will be operated on board of HALO. It consists of a cloud radar and a suite of passive radiometers in different frequency bands. The radar MIRA-36 operates at 36.5 GHz. Although this is an unusual low frequency, it benefits from the wider range of applications due to less signal attenuation in deep clouds and rain, compared to the 94 GHz radar operated on CloudSat. The frequencies for the passive microwave radiometers were selected in allusion to the AMSU-A and -B sounder. Thereby the 150 GHz channel of AMSU-B has been replaced by frequencies in the 118 GHz oxygen band. In combination with the 60 GHz oxygen complex channels, this frequencies can be used for precipitation retrieval after Bauer and Mugnai (2003). Furthermore by including channels in the water vapor lines at 22.235 GHz and 183.31 GHz and higher microwave channels sensitive to scattering in the ice phase, various precipitation retrieval algorithms can be compared by measurements with HAMP. This presentation introduces the microwave package on HALO. It further shows the potential of the observations by presenting results of a simulation study for the selected microwave frequencies and the cloud radar. The potential of the selected frequencies for

  8. Aircraft observations of the vertical structure of stratiform precipitation relevant to microwave radiative transfer

    Energy Technology Data Exchange (ETDEWEB)

    Chang, A.T.C. (NASA Goddard Space Flight Center, Greenbelt, MD (United States)); Barnes, A.; Glass, M. (Phillips Lab., Hanscom AFB, MA (United States)); Kakar, R. (NASA Headquarters, Washington, DC (United States)); Wilheit, T.T. (Texas A M Univ., College Station (United States))

    1993-06-01

    The retrieval of rainfall intensity over the oceans from passive microwave observations is based on a radiative transfer model. direct rainfall observations of oceanic rainfall are virtually nonexistent making validation of the retrievals extremely difficult. Observations of the model assumptions provide an alternative approach for improving and developing confidence in the rainfall retrievals. In the winter of 1983, the NASA CV-990 aircraft was equipped with a payload suitable for examining several of the model assumptions. The payload included microwave and infrared radiometers, mirror hygrometers, temperature probes, and PMS probes. On two occasions the aircraft ascended on a spiral track through stratiform precipitation providing an opportunity to study the atmospheric parameters. The assumptions concerning liquid hydrometeors, water vapor, lapse rate, and nonprecipitating clouds were studied. Model assumptions seem to be supported by these observations. 23 refs., 7 figs.

  9. Physics of the Microwave Oven

    Science.gov (United States)

    Vollmer, Michael

    2004-01-01

    This is the first of two articles about the physics of microwave ovens. This article deals with the generation of microwaves in the oven and includes the operation of the magnetrons, waveguides and standing waves in resonant cavities. It then considers the absorption of microwaves by foods, discussing the dielectric relaxation of water,…

  10. Physics of the Microwave Oven

    Science.gov (United States)

    Vollmer, Michael

    2004-01-01

    This is the first of two articles about the physics of microwave ovens. This article deals with the generation of microwaves in the oven and includes the operation of the magnetrons, waveguides and standing waves in resonant cavities. It then considers the absorption of microwaves by foods, discussing the dielectric relaxation of water,…

  11. Microwave-assisted Palladium-micelle-catalyzed Suzuki Cross-coupling Reaction in Water

    Institute of Scientific and Technical Information of China (English)

    LIN Li; LI Sheng-hai; JIANG Ri-hua

    2011-01-01

    A microwave-accelerated Suzuki coupling procedure was developed via guanidinium ionic liquids(GILs)stabilized Pd-micelle.The Pd micelle/GILs play a key role in enhancing the activity,due to the highly dispersed Pd active sites and the phase transfer function of GILs,which ensures the adsorption of reactants and facilitates the translation of the intermediates to the surface of the micelle.

  12. MERITXELL: The Multifrequency Experimental Radiometer with Interference Tracking for Experiments over Land and Littoral-Instrument Description, Calibration and Performance.

    Science.gov (United States)

    Querol, Jorge; Tarongí, José Miguel; Forte, Giuseppe; Gómez, José Javier; Camps, Adriano

    2017-05-10

    MERITXELL is a ground-based multisensor instrument that includes a multiband dual-polarization radiometer, a GNSS reflectometer, and several optical sensors. Its main goals are twofold: to test data fusion techniques, and to develop Radio-Frequency Interference (RFI) detection, localization and mitigation techniques. The former is necessary to retrieve complementary data useful to develop geophysical models with improved accuracy, whereas the latter aims at solving one of the most important problems of microwave radiometry. This paper describes the hardware design, the instrument control architecture, the calibration of the radiometer, and several captures of RFI signals taken with MERITXELL in urban environment. The multiband radiometer has a dual linear polarization total-power radiometer topology, and it covers the L-, S-, C-, X-, K-, Ka-, and W-band. Its back-end stage is based on a spectrum analyzer structure which allows to perform real-time signal processing, while the rest of the sensors are controlled by a host computer where the off-line processing takes place. The calibration of the radiometer is performed using the hot-cold load procedure, together with the tipping curves technique in the case of the five upper frequency bands. Finally, some captures of RFI signals are shown for most of the radiometric bands under analysis, which evidence the problem of RFI in microwave radiometry, and the limitations they impose in external calibration.

  13. MERITXELL: The Multifrequency Experimental Radiometer with Interference Tracking for Experiments over Land and Littoral—Instrument Description, Calibration and Performance

    Science.gov (United States)

    Querol, Jorge; Tarongí, José Miguel; Forte, Giuseppe; Gómez, José Javier; Camps, Adriano

    2017-01-01

    MERITXELL is a ground-based multisensor instrument that includes a multiband dual-polarization radiometer, a GNSS reflectometer, and several optical sensors. Its main goals are twofold: to test data fusion techniques, and to develop Radio-Frequency Interference (RFI) detection, localization and mitigation techniques. The former is necessary to retrieve complementary data useful to develop geophysical models with improved accuracy, whereas the latter aims at solving one of the most important problems of microwave radiometry. This paper describes the hardware design, the instrument control architecture, the calibration of the radiometer, and several captures of RFI signals taken with MERITXELL in urban environment. The multiband radiometer has a dual linear polarization total-power radiometer topology, and it covers the L-, S-, C-, X-, K-, Ka-, and W-band. Its back-end stage is based on a spectrum analyzer structure which allows to perform real-time signal processing, while the rest of the sensors are controlled by a host computer where the off-line processing takes place. The calibration of the radiometer is performed using the hot-cold load procedure, together with the tipping curves technique in the case of the five upper frequency bands. Finally, some captures of RFI signals are shown for most of the radiometric bands under analysis, which evidence the problem of RFI in microwave radiometry, and the limitations they impose in external calibration. PMID:28489056

  14. Microwave engineering

    CERN Document Server

    Pozar, David M

    2012-01-01

    The 4th edition of this classic text provides a thorough coverage of RF and microwave engineering concepts, starting from fundamental principles of electrical engineering, with applications to microwave circuits and devices of practical importance.  Coverage includes microwave network analysis, impedance matching, directional couplers and hybrids, microwave filters, ferrite devices, noise, nonlinear effects, and the design of microwave oscillators, amplifiers, and mixers. Material on microwave and RF systems includes wireless communications, radar, radiometry, and radiation hazards. A large

  15. Sierra Nevada Winter Storms: a Study Using Microwave Radiometry, Ice Crystal and Isotopic Analysis Technique

    Science.gov (United States)

    Demoz, Belay Berhane

    An observational study has been made of ice-phase winter storm clouds over the Sierra Nevada mountains. In Part I, two microwave radiometers, one designed with a spinning reflector to shed precipitation particles while the other radiometer's reflector was fixed, are compared. The absence/presence of contaminated periods in the data was attributed to difference in design. These apparent contaminated periods led to lower correlation coefficients between the radiometers. Comparison of radiometer and rawinsonde resulted in a correlation coefficient of 0.97 for the spinning reflector as opposed to 0.8 for the fixed reflector radiometer. In Part II, stable water isotopes were used to study mesoscale and microscale storm modifications by the Sierra Nevada. Initially, a low level warm front lay across the region and its elevation lowered with time from 2.5 km to 1.7 km. This decrease of frontal surface height was accompanied by a steady increase in the delta ^{18}O values. In the pre-cold frontal period, the delta^{18 }O values at the upwind site signified warmer origin ice crystals than the downwind site. This is explained by orographic effects and the production of supercooled liquid water at low elevations on the upslope side. The delta^{18}O value peaked around -13perthous which translates to an "equivalent temperature" of -10.7^circC for ice phase water capture at the upwind site. At the downwind site, this was some 5 to 6 centigrade degrees colder. During surface cold front passage, the differences in delta^{18}O at the two sites are small probably because, during frontal passage, the orography plays a less significant role in the precipitation production process. In Part III, observations of precipitation rates, ice crystals, wind and supercooled liquid water (SLW) upwind and downwind of the Sierra Nevada are presented. Observations show that the stage of development of the storms was important in the liquid and vapor development. High SLW, and increased riming were

  16. Remotely sensed water vapor variations during CLEOPATRA `92

    Energy Technology Data Exchange (ETDEWEB)

    Meischner, P.F. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Wessling (Germany). Inst. fuer Physik der Atmosphaere; Kiemle, C. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Wessling (Germany). Inst. fuer Physik der Atmosphaere; Ehret, G. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Wessling (Germany). Inst. fuer Physik der Atmosphaere; Kaestner, M. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Wessling (Germany). Inst. fuer Physik der Atmosphaere; Schreiber, H.G. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Wessling (Germany). Inst. fuer Physik der Atmosphaere; Evtushenko, A.V. [Rossijskaya Akademiya Nauk, Moscow (Russian Federation). Inst. Radiotekhniki i Ehlektroniki; Kutuza, B.G. [Rossijskaya Akademiya Nauk, Moscow (Russian Federation). Inst. Radiotekhniki i Ehlektroniki; Petrenko, B.Z. [Rossijskaya Akademiya Nauk, Moscow (Russian Federation). Inst. Radiotekhniki i Ehlektroniki; Smirnov, M.T. [Rossijskaya Akademiya Nauk, Moscow (Russian Federation). Inst. Radiotekhniki i Ehlektroniki

    1994-11-01

    Total atmospheric water vapor contents have been measured during CLEOPATRA `92 using different methods. A multifrequency microwave radiometer system from IRE, Moskow operated from ground and an airborne DIAL system, DLR, performed measurements above the radiometer site. The results compare well if the atmosphric conditions are sufficiently homogeneous in the mesoscale and complement in a high space resolution for the DIAL measurements and a high time resolution of the microwave system. Under these conditions both measurement results further agree with radiosoundings and aircraft in situ measurements within the estimated measurement errors. Coordinated observations by the different systems with high time and high space resolution open a good change to separate between transports caused by advection or convection. Microwave radiometer measurements from ground are best suited for monitoring long term trends as well as fast fluctuations, whereas the DIAL measurements give more detailed insight in the diffusion processes within the atmospheric boundary layer ABL. The measurements on May 29 very impressively show the moisture fluxes from local lakes into the ABL. The observations support the ABL to act as a flux-averaging medium, thus contributing naturally to an upscaling which improves the use of remote measurements from space for the estimation of area averaged moisture fluxes. (orig.)

  17. Multifilter Rotating Shadowband Radiometer (MFRSR) Handbook With subsections for derivative instruments: Multifilter Radiometer (MFR) Normal Incidence Multifilter Radiometer (NIMFR)

    Energy Technology Data Exchange (ETDEWEB)

    Hodges, Gary B [National Oceanic and Atmospheric Administration (NOAA), Boulder, CO (United States). Earth System Research Lab.; Michalsky, Joseph J [National Oceanic and Atmospheric Administration (NOAA), Boulder, CO (United States). Earth System Research Lab.

    2016-03-01

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

  18. Airborne microwave radiometry on a semi-arid area during HAPEX-Sahel

    Science.gov (United States)

    Chanzy, A.; Schmugge, T. J.; Calvet, J.-C.; Kerr, Y.; van Oevelen, P.; Grosjean, O.; Wang, J. R.

    1997-02-01

    Airborne microwave radiometric measurements in the framework of the HAPEX-Sahel Experiment were performed by the Push Broom Microwave Radiometer (PBMR) and the PORTOS radiometer. The flights of both radiometers produced an original set of data covering the 1.4-90 GHz range of frequency. The East and West Central Super Sites were the areas most intensively observed by the microwave radiometers. Over those sites, several brightness temperature ( TB) maps are available at seven dates distributed over a 1 month period in the middle of the rainy season. A comparison of the two radiometers demonstrates their radiometric quality and the precision of the localization of the microwave observations. At 1.4 GHz, the vegetation had very little effect on the soil microwave emission. Maps of soil moisture were developed using a single linear relationship between TB and the surface soil moisture. There is an important spatial heterogeneity in the soil moisture distribution, which is explained by both the soil moisture hydrodynamic properties and the localization of the precipitation fields. At 5.05 GHz, the vegetation must be accounted for to infer soil moisture from the microwave observations. A method based on a simple radiative transfer model and on microwave data has shown encouraging results.

  19. Remote sensing of atmospheric water content from Bhaskara SAMIR data. [using statistical linear regression analysis

    Science.gov (United States)

    Gohil, B. S.; Hariharan, T. A.; Sharma, A. K.; Pandey, P. C.

    1982-01-01

    The 19.35 GHz and 22.235 GHz passive microwave radiometers (SAMIR) on board the Indian satellite Bhaskara have provided very useful data. From these data has been demonstrated the feasibility of deriving atmospheric and ocean surface parameters such as water vapor content, liquid water content, rainfall rate and ocean surface winds. Different approaches have been tried for deriving the atmospheric water content. The statistical and empirical methods have been used by others for the analysis of the Nimbus data. A simulation technique has been attempted for the first time for 19.35 GHz and 22.235 GHz radiometer data. The results obtained from three different methods are compared with radiosonde data. A case study of a tropical depression has been undertaken to demonstrate the capability of Bhaskara SAMIR data to show the variation of total water vapor and liquid water contents.

  20. Microwave spectroscopic and theoretical investigations of the strongly hydrogen bonded hexafluoroisopropanol···water complex.

    Science.gov (United States)

    Shahi, A; Arunan, E

    2015-10-14

    This paper reports microwave spectroscopic and theoretical investigations on the interaction of water with hexafluoroisopropanol (HFIP). The HFIP monomer can exist in two conformations, antiperiplanar (AP) and synclinical (SC). The former is about 5 kJ mol(-1) more stable than the latter. Theoretical calculations predicted three potential minima for the complex, two having AP and one having SC conformations. Though, the binding energy for the HFIP(SC)···H2O turned out to be larger than that for the other two conformers having HFIP in the AP form, the global minimum for the complex in the potential energy hypersurface had HFIP in the AP form. Experimental rotational constants for four isotopologues measured using a pulsed nozzle Fourier transform microwave spectrometer, correspond to the global minimum in the potential energy hypersurface. The structural parameters and the internal dynamics of the complex could be determined from the rotational spectra of the four isotopologues. The global minimum has the HFIP(AP) as a hydrogen bond donor forming a strong hydrogen bond with H2O. To characterize the strength of the bonding and to probe the other interactions within the complex, atoms in molecules, non-covalent interaction index and natural bond orbital theoretical analyses have been performed.

  1. One-step microwave-assisted synthesis of water-dispersible Fe3O4 magnetic nanoclusters for hyperthermia applications

    Science.gov (United States)

    Sathya, Ayyappan; Kalyani, S.; Ranoo, Surojit; Philip, John

    2017-10-01

    To realize magnetic hyperthermia as an alternate stand-alone therapeutic procedure for cancer treatment, magnetic nanoparticles with optimal performance, within the biologically safe limits, are to be produced using simple, reproducible and scalable techniques. Herein, we present a simple, one-step approach for synthesis of water-dispersible magnetic nanoclusters (MNCs) of superparamagnetic iron oxide by reducing of Fe2(SO4)3 in sodium acetate (alkali), poly ethylene glycol (capping ligand), and ethylene glycol (solvent and reductant) in a microwave reactor. The average size and saturation magnetization of the MNC's are tuned from 27 to 52 nm and 32 to 58 emu/g by increasing the reaction time from 10 to 600 s. Transmission electron microscopy images reveal that each MNC composed of large number of primary Fe3O4 nanoparticles. The synthesised MNCs show excellent colloidal stability in aqueous phase due to the adsorbed PEG layer. The highest SAR value of 215 ± 10 W/gFe observed in 52 nm size MNC at a frequency of 126 kHz and field of 63 kA/m suggest the potential use of these MNC in hyperthermia applications. This study further opens up the possibilities to develop metal ion-doped MNCs with tunable sizes suitable for various biomedical applications using microwave assisted synthesis.

  2. The STARTWAVE atmospheric water database

    Directory of Open Access Journals (Sweden)

    J. Morland

    2006-01-01

    Full Text Available The STARTWAVE (STudies in Atmospheric Radiative Transfer and Water Vapour Effects project aims to investigate the role which water vapour plays in the climate system, and in particular its interaction with radiation. Within this framework, an ongoing water vapour database project was set up which comprises integrated water vapour (IWV measurements made over the last ten years by ground-based microwave radiometers, Global Positioning System (GPS receivers and sun photometers located throughout Switzerland at altitudes between 330 and 3584 m. At Bern (46.95° N, 7.44° E tropospheric and stratospheric water vapour profiles are obtained on a regular basis and integrated liquid water, which is important for cloud characterisation, is also measured. Additional stratospheric water vapour profiles are obtained by an airborne microwave radiometer which observes large parts of the northern hemisphere during yearly flight campaigns. The database allows us to validate the various water vapour measurement techniques. Comparisons between IWV measured by the Payerne radiosonde with that measured at Bern by two microwave radiometers, GPS and sun photometer showed instrument biases within ±0.5 mm. The bias in GPS relative to sun photometer over the 2001 to 2004 period was –0.8 mm at Payerne (46.81° N, 6.94° E, 490 m, which lies in the Swiss plains north of the Alps, and +0.6 mm at Davos (46.81° N, 9.84° E, 1598 m, which is located within the Alps in the eastern part of Switzerland. At Locarno (46.18° N, 8.78° E, 366 m, which is located on the south side of the Alps, the bias is +1.9 mm. The sun photometer at Locarno was found to have a bias of –2.2 mm (13% of the mean annual IWV relative to the data from the closest radiosonde station at Milano. This result led to a yearly rotation of the sun photometer instruments between low and high altitude stations to improve the calibrations. In order to demonstrate the capabilites of the database for studying

  3. Digital Array Gas Radiometer (DAGR) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The digital array gas radiometer (DAGR) is a new sensor design for accurate measurement and monitoring of trace gases in the boundary layer from space, aircraft, or...

  4. Influence of wet activation of used inorganic binder on cyclically refreshed water glass moulding sands hardened by microwaves

    Directory of Open Access Journals (Sweden)

    Mateusz Stachowicz

    2016-11-01

    Full Text Available The paper presents the research results of using an innovative method to reclaim the waste moulding sands containing water glass. Two of the examined processes are connected with "dry" or "wet" activation of inorganic binder in waste moulding sand mixtures physically hardened by microwave radiation. The sand mixtures consisting of high-silica sand and water-glass with average molar module 2.5, were subjected to the following cyclical process: mixing the components, compacting, microwave heating, cooling-down, thermally loading the mould to 800 °C, cooling-down to ambient temperature, and knocking-out. After being knocked-out, the waste moulding sands were subjected to either dry or wet activation of the binder. To activate thermally treated inorganic binder, each of the examined processes employed the surface phenomenon usually associated to mechanical reclamation. The study also covered possible use of some elements of wet reclamation to rehydrate waste binder. To evaluate the effectiveness of the two proposed methods of waste binder activation, selected strength and technological parameters were measured. After each subsequent processing cycle, the permeability, tensile strength and bending strength were determined. In addition, the surface of activated sand grains was examined with a scanning electron microscope. Analysis of the results indicates that it is possible to re-activate the used binder such as sodium silicate, and to stabilize the strength parameters in both activation processes. Permeability of the refreshed moulding sands strongly depends on the surface condition of high-silica grains. The wet activation process by wetting and buffering knocked-out moulding sands in closed humid environment makes it possible to reduce the content of refreshing additive in water-glass. The moulding sands cyclically prepared in both processes do not require the addition of fresh high-silica sand. The relatively high quality achieved in the

  5. Using a conformal water bolus to adjust heating patterns of microwave waveguide applicators

    Science.gov (United States)

    Stauffer, Paul R.; Rodrigues, Dario B.; Sinahon, Randolf; Sbarro, Lyndsey; Beckhoff, Valeria; Hurwitz, Mark D.

    2017-02-01

    Background: Hyperthermia, i.e., raising tissue temperature to 40-45°C for 60 min, has been demonstrated to increase the effectiveness of radiation and chemotherapy for cancer. Although multi-element conformal heat applicators are under development to provide more adjustable heating of contoured anatomy, to date the most often used applicator to heat superficial disease is the simple microwave waveguide. With only a single power input, the operator must be resourceful to adjust heat treatment to accommodate variable size and shape tumors spreading across contoured anatomy. Methods: We used multiphysics simulation software that couples electromagnetic, thermal and fluid dynamics physics to simulate heating patterns in superficial tumors from commercially available microwave waveguide applicators. Temperature distributions were calculated inside homogenous muscle and layered skin-fat-muscle-tumor-bone tissue loads for a typical range of applicator coupling configurations and size of waterbolus. Variable thickness waterbolus was simulated as necessary to accommodate contoured anatomy. Physical models of several treatment configurations were constructed for comparison of simulation results with experimental specific absorption rate (SAR) measurements in homogenous muscle phantom. Results: Accuracy of the simulation model was confirmed with experimental SAR measurements of three unique applicator setups. Simulations demonstrated the ability to generate a wide range of power deposition patterns with commercially available waveguide antennas by controllably varying size and thickness of the waterbolus layer. Conclusion: Heating characteristics of 915 MHz waveguide antennas can be varied over a wide range by controlled adjustment of microwave power, coupling configuration, and waterbolus lateral size and thickness. The uniformity of thermal dose delivered to superficial tumors can be improved by cyclic switching of waterbolus thickness during treatment to proactively shift

  6. Determination of nitrate in lettuce by ion chromatography after microwave water extraction

    Directory of Open Access Journals (Sweden)

    Humberto Brevilato Novaes

    2009-01-01

    Full Text Available Lettuce is worldwide known as the most important vegetable. In this context, most farmers are searching new techniques for best quality products including hydropony. However, nitrate is of great concern, since it has a negative impact on human metabolism. The main objective of the present work was to evaluate the nitrate content of lettuce produced by conventional and hydroponic systems. The determination was conducted by ion chromatography and a new method of extraction was tested using microwave oven digestion. The results indicated that nitrate level produced in the conventional system was lower than in the hydroponic system.

  7. Microwave Remote Sensing: Needs and Requirements Concerning Technology

    DEFF Research Database (Denmark)

    Skou, Niels

    2003-01-01

    Spaceborne microwave remote sensing instruments, like the imaging radiometer and the synthetic aperture radar, are over timed faced with two partly conflicting requirements: performance expectations (resolutions, sensitivity, coverage) steadily increase with resource allocations (weight, power, b......, bulk, cost) decrease. This results in needs and requirements to the development of advanced technology thus enabling the future advanced systems to be viable and realistic.......Spaceborne microwave remote sensing instruments, like the imaging radiometer and the synthetic aperture radar, are over timed faced with two partly conflicting requirements: performance expectations (resolutions, sensitivity, coverage) steadily increase with resource allocations (weight, power...

  8. MICROWAVE SENSOR DEVELOPMENT IN RECENT TWO YEARS IN CHINA

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The development of microwave sensors in recent two years in China are in troduced with an emphasis on spaceborne sensors without the applications in cluded. The microwave sensors as the main payloads to be boarded on the future operational satellites, such as FY-3 meteorological satellites and HY-2 marine satellite are introduced with much in detail. Besides these, four new sensors are outlined, i.e. the imaging radar altimeter,synthetic aperture radiometer, and polarimetric radiometer. Two recently conducted flight experiment campaigns are also introduced with results shown.

  9. Microwave Radiometry for Oil Pollution Monitoring, Measurements, and Systems

    DEFF Research Database (Denmark)

    Skou, Niels

    1986-01-01

    Work is presently carried out in Europe to change the Status of the microwave radiometer, namely, to develop it from a research instrument to an operational instrument-especially for measuring oil pollution on the sea surface. The Technical University of Denmark (TUD), with its long experience...... in airborne microwave radiometry, is heavily involved in this process. The TUD multichannel imaging radiometer system has been flown in several large-scale oil-pollution experiments, the collected data have been analyzed, and they have revealed that care must be exercised to obtain accurate oil volume...

  10. Multifilter Rotating Shadowband Radiometer (MFRSR) Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Hodges, GB; Michalsky, JJ

    2011-02-07

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

  11. Multifilter Rotating Shadowband Radiometer (MFRSR) Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Hodges, GB; Michalsky, JJ

    2011-02-07

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

  12. Atmospheric correction for sea surface temperature retrieval from single thermal channel radiometer data onboard Kalpana satellite

    Indian Academy of Sciences (India)

    Naveen R Shahi; Neeraj Agarwal; Aloke K Mathur; Abhijit Sarkar

    2011-06-01

    An atmospheric correction method has been applied on sea surface temperature (SST) retrieval algorithm using Very High Resolution Radiometer (VHRR) single window channel radiance data onboard Kalpana satellite (K-SAT). The technique makes use of concurrent water vapour fields available from Microwave Imager onboard Tropical Rainfall Measuring Mission (TRMM/TMI) satellite. Total water vapour content and satellite zenith angle dependent SST retrieval algorithm has been developed using Radiative Transfer Model [MODTRAN ver3.0] simulations for Kalpana 10.5–12.5 m thermal window channel. Retrieval of Kalpana SST (K-SST) has been carried out for every half-hourly acquisition of Kalpana data for the year 2008 to cover whole annual cycle of SST over Indian Ocean (IO). Validation of the retrieved corrected SST has been carried out using near-simultaneous observations of ship and buoys datasets covering Arabian Sea, Bay of Bengal and IO regions. A significant improvement in Root Mean Square Deviation (RMSD) of K-SST with respect to buoy (1.50–1.02 K) and to ship datasets (1.41–1.19 K) is seen with the use of near real-time water vapour fields of TMI. Furthermore, comparison of the retrieved SST has also been carried out using near simultaneous observations of TRMM/TMI SST over IO regions. The analysis shows that K-SST has overall cold bias of 1.17 K and an RMSD of 1.09 K after bias correction.

  13. Microwave Ovens

    Science.gov (United States)

    ... ovens heat food using microwaves, a form of electromagnetic radiation similar to radio waves. Microwaves have three characteristics ... that their microwave oven products meet the strict radiation safety standard ... if your microwave oven has damage to its door hinges, latches, or seals, or ...

  14. Conventional and microwave-assisted multicomponent reaction of alkyne, halide and sodium azide catalyzed by copper apatite as heterogeneous base and catalyst in water

    Directory of Open Access Journals (Sweden)

    Sandip Kale

    2012-04-01

    Full Text Available The conventional and microwave assisted multicomponent synthesis of disubstituted 1,2,3-triazoles from terminal alkynes and in situ generated organic azide using copper apatite catalyst in water is reported. The catalytic activity is intimately connected to the basicity of the catalyst. The best activities were observed with the copper hydroxyapatite. The catalyst could be used ten times without further treatment and activation under controlled microwave heating. The protocol was also applicable for various alkynes and halides which affords desired product in good to excellent yield.

  15. Evaluation of Deep Space Ka-Band Data Transfer using Radiometeorological Forecasts and Radiometer Measurements

    Science.gov (United States)

    Montopoli, Mario; Marzano, Frank S.; Biscarini, Marianna; Milani, Luca; Cimini, Domenico; De Sanctis, Klaide; Di Fabio, Saverio

    2016-04-01

    framework of the Radio-Meteorological Operations Planner (RMOP) project promoted by ESA for supporting the BepiColombo mission to Mercury. More in detail, the methodology used in this work foresees the use of Fifth-Generation Penn State/NCAR Mesoscale Model (MM5) coupled with an Eddington-like radiative transfer model in order to convert the forecasted meteorological variables into radio-propagation parameters. Thus, in-situ observations from microwave radiometers are used to validate the weather forecasts in terms of integrated water paths in clear sky whereas radiosoundings and rain gauges will provide a reference for temperature and rain accumulations, respectively. Eventually, the final results will be shown in terms of improvements in the transferred data volume when the RMOP chain is implemented.

  16. Investigating Satellite Microwave observations of Precipitation in Different Climate Regimes

    Science.gov (United States)

    Wang, N.; Ferraro, R. R.

    2013-12-01

    Microwave satellite remote sensing of precipitation over land is a challenging problem due to the highly variable land surface emissivity, which, if not properly accounted for, can be much greater than the precipitation signal itself, especially in light rain/snow conditions. Additionally, surfaces such as arid land, deserts and snow cover have brightness temperature characteristics similar to precipitation Ongoing work by GPM microwave radiometer team is constructing databases through a variety of means, however, there is much uncertainty as to what is the optimal information needed for the wide array of sensors in the GPM constellation, including examination of regional conditions. The original data sets will focus on stratification by emissivity class, surface temperature and total perceptible water. We'll perform sensitivity studies to determine the potential role of ancillary data (e.g., land surface temperature, snow cover/water equivalent, etc.) to improve precipitation estimation over land in different climate regimes, including rain and snow. In other words, what information outside of the radiances can help describe the background and subsequent departures from it that are active precipitating regions? It is likely that this information will be a function of the various precipitation regimes. Statistical methods such as Principal Component Analysis (PCA) will be utilized in this task. Databases from a variety of sources are being constructed. They include existing satellite microwave measurements of precipitating and non-precipitating conditions, ground radar precipitation rate estimates, surface emissivity climatology from satellites, surface temperature and TPW from NWP reanalysis. Results from the analysis of these databases with respect to the microwave precipitation sensitivity to the variety of environmental conditions in different climate regimes will be discussed.

  17. Microwave imaging

    CERN Document Server

    Pastorino, Matteo

    2010-01-01

    An introduction to the most relevant theoretical and algorithmic aspects of modern microwave imaging approaches Microwave imaging-a technique used in sensing a given scene by means of interrogating microwaves-has recently proven its usefulness in providing excellent diagnostic capabilities in several areas, including civil and industrial engineering, nondestructive testing and evaluation, geophysical prospecting, and biomedical engineering. Microwave Imaging offers comprehensive descriptions of the most important techniques so far proposed for short-range microwave imaging-in

  18. Aqueous microwave-assisted solid-phase peptide synthesis using Fmoc strategy. III: racemization studies and water-based synthesis of histidine-containing peptides.

    Science.gov (United States)

    Hojo, Keiko; Shinozaki, Natsuki; Hidaka, Koushi; Tsuda, Yuko; Fukumori, Yoshinobu; Ichikawa, Hideki; Wade, John D

    2014-10-01

    In this study, we describe the first aqueous microwave-assisted synthesis of histidine-containing peptides in high purity and with low racemization. We have previously shown the effectiveness of our synthesis methodology for peptides including difficult sequences using water-dispersible 9-fluorenylmethoxycarbonyl-amino acid nanoparticles. It is an organic solvent-free, environmentally friendly method for chemical peptide synthesis. Here, we studied the racemization of histidine during an aqueous-based coupling reaction with microwave irradiation. Under our microwave-assisted protocol using 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride, the coupling reaction can be efficiently performed with low levels of racemization of histidine. Application of this water-based microwave-assisted protocol with water-dispersible 9-fluorenylmethoxycarbonyl-amino acid nanoparticles led to the successful synthesis of the histidine-containing hexapeptide neuropeptide W-30 (10-15), Tyr-His-Thr-Val-Gly-Arg-NH₂, in high yield and with greatly reduced histidine racemization.

  19. Snowmelt and Surface Freeze/Thaw Timings over Alaska derived from Passive Microwave Observations using a Wavelet Classifier

    Science.gov (United States)

    Steiner, N.; McDonald, K. C.; Dinardo, S. J.; Miller, C. E.

    2015-12-01

    Arctic permafrost soils contain a vast amount of organic carbon that will be released into the atmosphere as carbon dioxide or methane when thawed. Surface to air greenhouse gas fluxes are largely dependent on such surface controls as the frozen/thawed state of the snow and soil. Satellite remote sensing is an important means to create continuous mapping of surface properties. Advances in the ability to determine soil and snow freeze/thaw timings from microwave frequency observations improves upon our ability to predict the response of carbon gas emission to warming through synthesis with in-situ observation, such as the 2012-2015 Carbon in Arctic Reservoir Vulnerability Experiment (CARVE). Surface freeze/thaw or snowmelt timings are often derived using a constant or spatially/temporally variable threshold applied to time-series observations. Alternately, time-series singularity classifiers aim to detect discontinuous changes, or "edges", in time-series data similar to those that occur from the large contrast in dielectric constant during the freezing or thaw of soil or snow. We use multi-scale analysis of continuous wavelet transform spectral gradient brightness temperatures from various channel combinations of passive microwave radiometers, Advanced Microwave Scanning Radiometer (AMSR-E, AMSR2) and Special Sensor Microwave Imager (SSM/I F17) gridded at a 10 km posting with resolution proportional to the observational footprint. Channel combinations presented here aim to illustrate and differentiate timings of "edges" from transitions in surface water related to various landscape components (e.g. snow-melt, soil-thaw). To support an understanding of the physical basis of observed "edges" we compare satellite measurements with simple radiative transfer microwave-emission modeling of the snow, soil and vegetation using in-situ observations from the SNOw TELemetry (SNOTEL) automated weather stations. Results of freeze/thaw and snow-melt timings and trends are

  20. View-limiting shrouds for insolation radiometers

    Science.gov (United States)

    Dennison, E. W.; Trentelman, G. F.

    1985-01-01

    Insolation radiometers (normal incidence pyrheliometers) are used to measure the solar radiation incident on solar concentrators for calibrating thermal power generation measurements. The measured insolation value is dependent on the atmospheric transparency, solar elevation angle, circumsolar radiation, and radiometer field of view. The radiant energy entering the thermal receiver is dependent on the same factors. The insolation value and the receiver input will be proportional if the concentrator and the radiometer have similar fields of view. This report describes one practical method for matching the field of view of a radiometer to that of a solar concentrator. The concentrator field of view can be calculated by optical ray tracing methods and the field of view of a radiometer with a simple shroud can be calculated by using geometric equations. The parameters for the shroud can be adjusted to provide an acceptable match between the respective fields of view. Concentrator fields of view have been calculated for a family of paraboloidal concentrators and receiver apertures. The corresponding shroud parameters have also been determined.

  1. Investigation on water content in fresco mock-ups in the microwave and near-IR spectral regions

    Science.gov (United States)

    Magrini, Donata; Cucci, Costanza; Olmi, Roberto; Picollo, Marcello; Riminesi, Cristiano

    2017-02-01

    Water diffusion inside masonry is responsible for the majority of the decay phenomena observed in wall paintings and frescos. Thus, the diagnostics of moisture and water content and their monitoring represent a key issue. In order to preserve the integrity of surfaces of artistic interest, investigations by means of non-destructive techniques (NDT) are preferred over others. The aim of this research is to determine methodologies to quantify the moisture content (MC) of frescos by means of the integrated use of two non-invasive techniques, namely fiber optic reflectance spectroscopy (FORS) in the near-IR region and evanescent field dielectrometry (EFD) in the microwave range. The FORS technique has been employed in order to assess the amount of water adsorbed from the surface by means of an analysis of the reflectance spectra in the Vis-NIR (350-2200 nm) range. This technique investigates the electronic and vibrational transitions that are characteristic of each compound and enables their identification. The water content is evaluated on the basis of the 1920 nm and 1450 nm absorption bands. The EFD system consists of a resonant probe connected to a network analyzer. The resonance frequency of the cavity under different moisture-content conditions of frescos is in the 1.0-1.5 GHz range. The device makes it possible to compute, in real time, the MC from a measurement of the transmission coefficient (amplitude versus frequency) through the probe. Fresco mock-ups have been prepared in collaboration with the Opificio delle Pietre Dure in order to recreate most of the possible chromatic shades obtained by mixing iron oxides and hydroxide-based pigments. Measurements were performed by employing both techniques on fresco models after wet-dry cycles obtained by means of poultices with a known water content. The results obtained with these two techniques were compared, and cross relationships between the EFD and FORS data were defined.

  2. A Method for Combined Passive-Active Microwave Retrievals of Cloud and Precipitation Profiles.

    Science.gov (United States)

    Olson, William S.; Kummerow, Christian D.; Heymsfield, Gerald M.; Giglio, Louis

    1996-10-01

    Three-dimensional tropical squall-line simulations from the Goddard cumulus ensemble (GCE) model are used as input to radiative computations of upwelling microwave brightness temperatures and radar reflectivities at selected microwave sensor frequencies. These cloud/radiative calculations form the basis of a physical cloud/precipitation profile retrieval method that yields estimates of the expected values of the hydrometeor water contents. Application of the retrieval method to simulated nadir-view observations of the aircraft-borne Advanced Microwave Precipitation Radiometer (AMPR) and NASA ER-2 Doppler radar (EDOP) produce random errors of 23%, 19%, and 53% in instantaneous estimates of integrated precipitating liquid, integrated precipitating ice, and surface rain rate, respectively.On 5 October 1993, during the Convection and Atmospheric Moisture Experiment (CAMEX), the AMPR and EDOP were used to observe convective systems in the vicinity of the Florida peninsula. Although the AMPR data alone could be used to retrieve cloud and precipitation vertical profiles over the ocean, retrievals of high-resolution vertical precipitation structure and profile information over land required the combination of AMPR and EDOP observations.No validation data are available for this study; however, the retrieved precipitation distributions from the convective systems are compatible with limited radar climatologies of such systems, as well as being radiometrically consistent with both the AMPR and EDOP observations. In the future, the retrieval method will be adapted to the passive and active microwave measurements from the Tropical Rainfall Measuring Mission (TRMM) satellite sensors.

  3. Synergies of the European Microwave Remote Sensing Missions SMOS and ASCAT for Monitoring Soil Moisture

    Science.gov (United States)

    Scipal, K.; Wagner, W.

    2003-04-01

    The lack of global soil moisture observations is one of the most glaring and pressing deficiencies in current research activities of related fields, from climate monitoring and ecological applications to the quantification of biogeophysical fluxes. This has implications for important issues of the international political agenda like managing global water resources, securing food production and studying climate change. Currently it is held that only microwave remote sensing offers the potential to produce reliable global scale soil moisture information economically. Recognising the urgent need for a soil moisture mission several international initiatives are planning satellite missions dedicated to monitor the global hydrological cycle among them two European microwave satellites. ESA is planning to launch the Soil Moisture and Ocean Salinity Mission SMOS, in 2006. SMOS will measure soil moisture over land and ocean salinity over the oceans. The mission rests on a passive microwave sensor (radiometer) operated in L-band which is currently believed to hold the largest potential for soil moisture retrieval. One year before (2005) EUMETSAT will launch the Meteorological Operational satellite METOP which carries the active microwave system Advanced Scatterometer ASCAT on board. ASCAT has been designed to retrieve winds over the oceans but recent research has established its capability to retrieve soil moisture. Although currently it is hold that, using active microwave techniques, the effect of surface roughness dominates that of soil moisture (while the converse is true for radiometers), the ERS scatterometer was successfully used to derive global soil moisture information at a spatial resolution of 50 km with weekly to decadal temporal resolution. The quality of the soil moisture products have been assessed by independent experts in several pilot projects funded by the European Space Agency. There is evidence to believe that both missions will provide a flow of

  4. Comparison of Columnar Water Vapor Measurements During The Fall 1997 ARM Intensive Observation Period: Optical Methods

    Science.gov (United States)

    Schmid, Beat; Michalsky, J.; Slater, D.; Barnard, J.; Halthore, R.; Liljegren, J.; Holben, B.; Eck, T.; Livingston, J.; Russell, P.; Hipskind, R. Stephen (Technical Monitor)

    2000-01-01

    In the fall of 1997 the Atmospheric Radiation Measurement (ARM program conducted an intensive Observation Period (IOP) to study water vapor at its Southern Great Plains (SGP) site. Among the large number of instruments, four sun-tracking radiometers were present to measure the columnar water vapor (CWV). All four solar radiometers retrieve CWV by measuring solar transmittance in the 0.94-micrometer water vapor absorption band. As one of the steps in the CWV retrievals the aerosol component is subtracted from the total transmittance, in the 0.94-micrometer band. The aerosol optical depth comparisons among the same four radiometers are presented elsewhere. We have used three different methods to retrieve CWV. Without attempting to standardize on the same radiative transfer model and its underlying water vapor spectroscopy we found the CWV to agree within 0.13 cm (rms) for CWV values ranging from 1 to 5 cm. Preliminary results obtained when using the same updated radiative transfer model with updated spectroscopy for all instruments will also be shown. Comparisons to the microwave radiometer results will be included in the comparisons.

  5. Treatment of Paper Waste Water by Microwave Radiation%微波辐射处理造纸工业污水

    Institute of Scientific and Technical Information of China (English)

    于兰平

    2012-01-01

    Microwave radiation technology was used to treat paper waste water. Using FeSO4-loaded slag as the wave-absorbing and oxidation-catalyzlng carrier, microwave radiation could effectively decompose organic pollutant in paper waste water. The activity of slag treated by microwave was better than that by normal furnace. The optimal conditions were determined by orthogonal experiment: the consumption of supported slag was 28 g per 50 mL waste water, time of microwave treatment was 17 min, and power of microwave radiation was 800 W. Under the optimal conditions, the removal rate of COD could reach 95%. The activated slag was reused, and some must be damaged; therefore the removal rate of COD declined.%采用微波辐射技术对造纸工业废水进行处理研究.以FeSO4负载炉渣为吸波催化载体,微波辐射处理造纸废水,可有效降解其有机污染物.炉渣微波活化活性优于普通炉活化.正交优化实验得到微波处理最优条件为:负载型炉渣用量为28g、微波辐射时间为17min、微波功率为800W,最优条件下COD去除率可达95%.活化炉渣重复使用,COD去除率明显下降,炉渣破损是效率下降的主要原因.

  6. Hurricane Imaging Radiometer Wind Speed and Rain Rate Retrievals during the 2010 GRIP Flight Experiment

    Science.gov (United States)

    Sahawneh, Saleem; Farrar, Spencer; Johnson, James; Jones, W. Linwood; Roberts, Jason; Biswas, Sayak; Cecil, Daniel

    2014-01-01

    Microwave remote sensing observations of hurricanes, from NOAA and USAF hurricane surveillance aircraft, provide vital data for hurricane research and operations, for forecasting the intensity and track of tropical storms. The current operational standard for hurricane wind speed and rain rate measurements is the Stepped Frequency Microwave Radiometer (SFMR), which is a nadir viewing passive microwave airborne remote sensor. The Hurricane Imaging Radiometer, HIRAD, will extend the nadir viewing SFMR capability to provide wide swath images of wind speed and rain rate, while flying on a high altitude aircraft. HIRAD was first flown in the Genesis and Rapid Intensification Processes, GRIP, NASA hurricane field experiment in 2010. This paper reports on geophysical retrieval results and provides hurricane images from GRIP flights. An overview of the HIRAD instrument and the radiative transfer theory based, wind speed/rain rate retrieval algorithm is included. Results are presented for hurricane wind speed and rain rate for Earl and Karl, with comparison to collocated SFMR retrievals and WP3D Fuselage Radar images for validation purposes.

  7. An Algorithm for Soil Moisture Retrieval using Multi-frequency Observations for Future the Water Cycle Observation Mission (WCOM)

    Science.gov (United States)

    Chen, Liang; Zhao, Tianjie; Wang, Cheng; Wan, Xiaoyun

    2017-04-01

    Soil moisture is one of the important parts in the global land surface ecosystem, water cycle and energy cycle, which control the water and heat energy exchange between land and atmosphere. Earth observation satellites play a critical role in providing information for understanding the global water cycle, which dominates the Earth-climate system. A new satellite concept of global Water Cycle Observation Mission (WCOM) is proposed in China, aiming to provide higher accuracy and consistent measurements of key elements of water cycle from space, including soil moisture, ocean salinity, freeze-thaw, snow water equivalent and etc. The expected more consistent and accurate datasets would be used to refine existing long-time series of satellite measurements, to constrain hydrological model projections and to detect the trends necessary for global change studies. The WCOM mission concept is a combination of active and passive microwave instruments. There will be three payloads: 1) an L-S-C tri-frequency Full-Polarized Interferometric synthetic aperture microwave Radiometer (FPIR); 2) a Polarized Microwave radiometric Imager (PMI) covering 6.8 GHz to 150 GHz bands; 3) an X-Ku Dual-Frequency Polarized SCATterometer (DFPSCAT). A soil moisture retrieval algorithm using the multi-frequency radiometer measurements is developed in this study. Through analyzing the simulated database of the Advanced Integral Equation Model (AIEM) under WCOM (Water Cycle Observation Mission) sensor configurations, a parameterized surface reflectivity model for multi-frequency Full-Polarized Interferometric synthetic aperture microwave Radiometer (FPIR) and Polarized Microwave radiometric Imager (PMI) are developed. In this model, influences of surface roughness parameters (e.g. RMS height, correlation length and type of autocorrelation function) on surface reflectivity are considered. It is found that the surface roughness and temperature can be cancelled out using the relationship of the multi

  8. Boreal Inundation Mapping with SMAP Radiometer Data for Methane Studies

    Science.gov (United States)

    Kim, Seungbum; Brisco, Brian; Poncos, Valentin

    2017-04-01

    Inundation and consequent anoxic condition induce methane release, which is one of the most potent greenhouse gases. Boreal regions contain large amounts of organic carbon, which is a potentially major methane emission source under climatic warming conditions. Boreal wetlands in particular are one of the largest sources of uncertainties in global methane budget. Wetland spatial extent together with the gas release rate remains highly unknown. Characterization of the existing inundation database is poor, because of the inundation under clouds and dense vegetation. In this work, the inundation extent is derived using brightness temperature data acquired by the L-band Soil Moisture Active Passive (SMAP) satellite, which offers the L-band capabilities to penetrate clouds and vegetation at 3-day revisit. The fidelity of the SMAP watermask is assessed as a first step in this investigation by comparing with the following data sets: 3-m resolution maps derived using Radarsat synthetic aperture radar (SAR) data in northern Canada and multi-sensor climatology over Siberia. Because Radarsat coverages are limited despite its high spatial resolution, at the time and location where Radarsats are not available, we also compare with 3-km resolution SMAP SAR data that are concurrent with the SMAP radiometer data globally until July 2015. Inundation extents were derived with Radarsat, SMAP SAR, and SMAP radiometer over the 60 km x 60km area at Peace Athabasca Delta (PAD), Canada on 6 days in spring and summer 2015. The SMAP SAR results match the locations of Radarsat waterbodies. However, the SMAP SAR underestimates the water extent, mainly over mixed pixels that have subpixel land presence. The threshold value (-3 dB) applied to the SMAP SAR was determined previously over the global domain. The threshold is dependent on the type of local landcover within a mixed pixel. Further analysis is needed to locally optimize the threshold. The SMAP radiometer water fraction over Peace

  9. Recent divergences in stratospheric water vapor measurements by frost point hygrometers and the Aura Microwave Limb Sounder

    Science.gov (United States)

    Hurst, Dale F.; Read, William G.; Vömel, Holger; Selkirk, Henry B.; Rosenlof, Karen H.; Davis, Sean M.; Hall, Emrys G.; Jordan, Allen F.; Oltmans, Samuel J.

    2016-09-01

    Balloon-borne frost point hygrometers (FPs) and the Aura Microwave Limb Sounder (MLS) provide high-quality vertical profile measurements of water vapor in the upper troposphere and lower stratosphere (UTLS). A previous comparison of stratospheric water vapor measurements by FPs and MLS over three sites - Boulder, Colorado (40.0° N); Hilo, Hawaii (19.7° N); and Lauder, New Zealand (45.0° S) - from August 2004 through December 2012 not only demonstrated agreement better than 1 % between 68 and 26 hPa but also exposed statistically significant biases of 2 to 10 % at 83 and 100 hPa (Hurst et al., 2014). A simple linear regression analysis of the FP-MLS differences revealed no significant long-term drifts between the two instruments. Here we extend the drift comparison to mid-2015 and add two FP sites - Lindenberg, Germany (52.2° N), and San José, Costa Rica (10.0° N) - that employ FPs of different manufacture and calibration for their water vapor soundings. The extended comparison period reveals that stratospheric FP and MLS measurements over four of the five sites have diverged at rates of 0.03 to 0.07 ppmv year-1 (0.6 to 1.5 % year-1) from ˜ 2010 to mid-2015. These rates are similar in magnitude to the 30-year (1980-2010) average growth rate of stratospheric water vapor ( ˜ 1 % year-1) measured by FPs over Boulder (Hurst et al., 2011). By mid-2015, the FP-MLS differences at some sites were large enough to exceed the combined accuracy estimates of the FP and MLS measurements.

  10. Broadband Microwave Spectroscopy as a Tool to Study Intermolecular Interactions in the Diphenyl Ether - Water System

    Science.gov (United States)

    Fatima, Mariyam; Perez, Cristobal; Schnell, Melanie

    2017-06-01

    Many biological processes, such as chemical recognition and protein folding, are mainly controlled by the interplay of hydrogen bonds and dispersive forces. This interplay also occurs between organic molecules and solvent water molecules. Broadband rotational spectroscopy studies of weakly bound complexes are able to accurately reveal the structures and internal dynamics of molecular clusters isolated in the gas phase. Amongst them, water clusters with organic molecules are of particular interest. In this work, we investigate the interplay between different types of weak intermolecular interactions and how it controls the preferred interaction sites of aromatic ethers, where dispersive interactions may play a significant role. We present our results on diphenyl ether (C_{12}H_{10}O, 1,1'-Oxydibenzene) complexed with up to three molecules of water. Diphenyl ether is a flexible molecule, and it offers two competing binding sites for water: the ether oxygen and the aromatic π system. In order to determine the structure of the diphenyl ether-water complexes, we targeted transitions in the 2-8 GHz range using broadband rotational spectroscopy. We identify two isomers with one water, one with two water, and one with three water molecules. Further analysis from isotopic substitution measurements provided accurate structural information. The preferred interactions, as well as the observed structural changes induced upon complexation, will be presented and discussed.

  11. Retrieval of Precipitation from Microwave Airborne Sensors during TOGA COARE.

    Science.gov (United States)

    Viltard, Nicolas; Obligis, Estelle; Marecal, Virginie; Klapisz, Claude

    1998-07-01

    The aim of this paper is to report on the retrieval of the vertically averaged liquid cloud water content and vertically averaged precipitation rates (rain and ice) from microwave airborne radiometric observations in a two-plane parallel layer atmosphere. The approach is based on the inversion of a simple radiative transfer model in which a raindrop size distribution derived from microphysical measurements is introduced. The microwave data (18.7, 21, 37, and 92 GHz) used were acquired by the Airborne Multichannel Microwave Radiometer and Advanced Microwave Moisture Sounder on board NASA DC8 within a mesoscale convective system on 6 February 1993 during the Tropical Oceans Global Atmosphere Coupled Ocean-Atmosphere Response Experiment.Before interpreting the results, the quality of the inversion is checked. The fit between the measured and the model-retrieved brightness temperatures is good when compared to the model and measurements uncertainties. Doppler radar data from three other aircraft help the result's interpretation, providing reflectivity and wind fields. The cloud liquid content seems to be difficult to retrieve. The ice and liquid rain rates are consistent with the other data sources: order of magnitude for convective and stratiform regions, presence of ice and liquid precipitation correlated with cell structure, and presence of cloud particles in the lighter precipitating regions.A quantitative comparison is done between the radiometric rainfall rates and those derived from the Airborne Rain Mapping Radar observations (also on board NASA DC8). There is a good agreement between the two from the statistical point of view (mean and standard deviation values). Moreover, the finescale rain structures that appear in radar results are rather well reproduced in the radiometric results. The importance of the new drop size distribution introduced in the radiative transfer model is emphasized by this last comparison.

  12. Microwave Photonics

    OpenAIRE

    Seeds, A.J.; Liu, C. P.; T. Ismail; Fice, M. J.; Pozzi, F; Steed, R. J.; Rouvalis, E.; Renaud, C.C.

    2010-01-01

    Microwave photonics is the use of photonic techniques for the generation, transmission, processing and reception of signals having spectral components at microwave frequencies. This tutorial reviews the technologies used and gives applications examples.

  13. Design and Dynamic Characterization of an Orientation Insensitive Microwave Water-Cut Sensor

    KAUST Repository

    Karimi, Muhammad Akram

    2017-06-12

    Modern reservoir management in oil and gas industry relies on accurate water fraction measurement which is produced as a by-product with oil. This paper presents a novel and contactless water fraction (also known as water-cut) measurement technique which is independent of geometric distribution of oil and water inside the pipe. The sensor is based on a modified T-resonator implemented directly on the pipe\\'s outer surface and whose resonance frequency decreases by increasing the water content in oil. The E-fields have been made to rotate and distribute well inside the pipe, despite having narrow and curved ground plane. It makes the sensor\\'s reading dependent only on the water fraction and not on the mixture distribution inside the pipe. That is why, the presented design does not require any flow conditioner to homogenize the oil/water mixture unlike many commercial water-cut (WC) sensors. The presented sensor has been realized by using extremely low-cost methods of screen printing and reusable 3-D printed mask. Complete characterization of the proposed WC sensor, both in horizontal and vertical orientations, has been carried out in an industrial flow loop. Excellent repeatability of the sensor\\'s response has been observed in \\'dispersed bubble\\' as well as in \\'stratified wavy\\' flow regimes. The performance test of the sensor confirms that the water fraction measurement is independent of the flow pattern, flow rate or orientation. The measured performance results of the sensor show full range accuracy of $± $2%-3% while tested under random orientations and wide range of flow rates.

  14. Characterization of a Digital Microwave Radiometry System for Noninvasive Thermometry using Temperature Controlled Homogeneous Test Load

    OpenAIRE

    2008-01-01

    Microwave radiometry has been proposed as a viable noninvasive thermometry approach for monitoring subsurface tissue temperatures and potentially controlling power levels of multielement heat applicators during clinical hyperthermia treatments. With the evolution of technology, several analog microwave radiometry devices have been developed for biomedical applications. In this paper, we describe a digital microwave radiometer with built-in electronics for signal processing and automatic self-...

  15. Microwave radiometric system for biomedical 'true temperature' and emissivity measurements.

    Science.gov (United States)

    Lüdeke, K M; Köhler, J

    1983-09-01

    A novel type of radiometer is described, which solves the problem of emissivity-(mismatch)-independent noise temperature measurements by simultaneous registration of an object's apparent temperature and its reflectivity with just one microwave receiver and real-time calculation of the object's emissivity and its actual temperature.

  16. Impact of advanced technology microwave sounder data in the NCMRWF 4D-VAR data assimilation system

    Science.gov (United States)

    Rani, S. Indira; Srinivas, D.; Mallick, Swapan; George, John P.

    2016-05-01

    This study demonstrates the added benefits of assimilating the Advanced Technology Microwave Sounder (ATMS) radiances from the Suomi-NPP satellite in the NCMRWF Unified Model (NCUM). ATMS is a cross-track scanning microwave radiometer inherited the legacy of two very successful instrument namely, Advanced Microwave Sounding Unit-A (AMSU-A) and Microwave Humidity Sounder (MHS). ATMS has 22 channels: 11 temperature sounding channels around 50-60 GHz oxygen band and 6 moisture sounding channels around the 183GHz water vapour band in addition to 5 channels sensitive to the surface in clear conditions, or to water vapour, rain, and cloud when conditions are not clear (at 23, 31, 50, 51 and 89 GHz). Before operational assimilation of any new observation by NWP centres it is standard practice to assess data quality with respect to NWP model background (short-forecast) fields. Quality of all channels is estimated against the model background and the biases are computed and compared against that from the similar observations. The impact of the ATMS data on global analyses and forecasts is tested by adding the ATMS data in the NCUM Observation Processing system (OPS) and 4D-Var variational assimilation (VAR) system. This paper also discusses the pre-operational numerical experiments conducted to assess the impact of ATMS radiances in the NCUM assimilation system. It is noted that the performance of ATMS is stable and it contributes to the performance of the model, complimenting observations from other instruments.

  17. Wearable system-on-a-chip radiometer for remote temperature sensing and its application to the safeguard of emergency operators.

    Science.gov (United States)

    Fonte, A; Alimenti, F; Zito, D; Neri, B; De Rossi, D; Lanatà, A; Tognetti, A

    2007-01-01

    The remote sensing and the detection of events that may represent a danger for human beings have become more and more important thanks to the latest advances of the technology. A microwave radiometer is a sensor capable to detect a fire or an abnormal increase of the internal temperature of the human body (hyperthermia), or an onset of a cancer, or even meteorological phenomena (forest fires, pollution release, ice formation on road pavement). In this paper, the overview of a wearable low-cost low-power system-on-a-chip (SoaC) 13 GHz passive microwave radiometer in CMOS 90 nm technology is presented. In particular, we focused on its application to the fire detection for civil safeguard. In detail, this sensor has been thought to be inserted into the fireman jacket in order to help the fireman in the detection of a hidden fire behind a door or a wall. The simulation results obtained by Ptolemy system simulation have confirmed the feasibility of such a SoaC microwave radiometer in a low-cost standard silicon technology for temperature remote sensing and, in particular, for its application to the safeguard of emergency operators.

  18. Innovative microwave hardening of water-glass containing sandmixes in technical-economic approach

    OpenAIRE

    A. Małachowska; Stachowicz, M.; K. Granat

    2012-01-01

    In recent years, observed is increasing interest in sandmixes containing inorganic binders. These binders, including also water-glass, are harmless for the environment, neutral for humans and relatively cheap. In spite of numerous advantages, their wide application is restricted by poor knock-out properties and problems related to rebonding. Therefore, numerous researches aimed at eliminating disadvantages of water-glass binder are directed, among others, to modifying structure of hydrated so...

  19. The benzoic acid-water complex: a potential atmospheric nucleation precursor studied using microwave spectroscopy and ab initio calculations.

    Science.gov (United States)

    Schnitzler, Elijah G; Jäger, Wolfgang

    2014-02-14

    The pure rotational, high-resolution spectrum of the benzoic acid-water complex was measured in the range of 4-14 GHz, using a cavity-based molecular beam Fourier-transform microwave spectrometer. In all, 40 a-type transitions and 2 b-type transitions were measured for benzoic acid-water, and 12 a-type transitions were measured for benzoic acid-D2O. The equilibrium geometry of benzoic acid-water was determined with ab initio calculations, at the B3LYP, M06-2X, and MP2 levels of theory, with the 6-311++G(2df,2pd) basis set. The experimental rotational spectrum is most consistent with the B3LYP-predicted geometry. Narrow splittings were observed in the b-type transitions, and possible tunnelling motions were investigated using the B3LYP/6-311++G(d,p) level of theory. Rotation of the water moiety about the lone electron pair hydrogen-bonded to benzoic acid, across a barrier of 7.0 kJ mol(-1), is the most likely cause for the splitting. Wagging of the unbound hydrogen atom of water is barrier-less, and this large amplitude motion results in the absence of c-type transitions. The interaction and spectroscopic dissociation energies calculated using B3LYP and MP2 are in good agreement, but those calculated using M06-2X indicate excess stabilization, possibly due to dispersive interactions being over-estimated. The equilibrium constant of hydration was calculated by statistical thermodynamics, using ab initio results and the experimental rotational constants. This allowed us to estimate the changes in percentage of hydrated benzoic acid with variations in the altitude, region, and season. Using monitoring data from Calgary, Alberta, and the MP2-predicted dissociation energy, a yearly average of 1% of benzoic acid is expected to be present in the form of benzoic acid-water. However, this percentage depends sensitively on the dissociation energy. For example, when using the M06-2X-predicted dissociation energy, we find it increases to 18%.

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

    Science.gov (United States)

    Kruse, Paul W.

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

  1. Dielectric Relaxation in Dimethyl Sulfoxide/Water Mixtures Studied by Microwave Dielectric Relaxation Spectroscopy

    Science.gov (United States)

    Lu, Zijie; Manias, Evangelos; MacDonald, Digby D.; Lanagan, Michael

    2009-10-01

    Dielectric spectra of dimethyl sulfoxide (DMSO)/water mixtures, over the entire concentration range, have been measured using the transmission line method at frequencies from 45 MHz to 26 GHz and at temperatures of 298-318 K. The relaxation times of the mixtures show a maximum at an intermediate molar fraction of DMSO. The specific structure of mixtures in different concentration regions was determined by the dielectric relaxation dynamics, obtained from the effect of temperature on the relaxation time. A water structure "breaking effect" is observed in dilute aqueous solutions. The average number of hydrogen bonds per water molecule in these mixtures is found to be reduced compared to pure water. The increase in the dielectric relaxation time in DMSO/water mixtures is attributed to the spatial (steric) constraints of DMSO molecules on the hydrogen-bond network, rather than being due to hydrophobic hydration of the methyl groups. The interaction between water and DMSO by hydrogen bonding reaches a maximum at a DMSO molar fraction of 0.33, reflected by the maximum activation enthalpy for dielectric relaxation in this concentration, suggesting the formation of a stoichiometric compound, H2O-DMSO-H2O. In highly concentrated solutions, negative activation entropies are observed, indicating the presence of aggregates of DMSO molecules. A distinct antiparallel arrangement of dipoles is obtained for neat DMSO in the liquid state according to the Kirkwood correlation factor (gK = 0.5), calculated from the static permittivity. The similarity of the dielectric behavior of pure DMSO and DMSO-rich mixtures suggests that dipole-dipole interactions contribute significantly to the rotational relaxation process in these solutions.

  2. Evaluation of Trace Metal Content by ICP-MS Using Closed Vessel Microwave Digestion in Fresh Water Fish

    Directory of Open Access Journals (Sweden)

    Sreenivasa Rao Jarapala

    2014-01-01

    Full Text Available The objective of the present study was to investigate trace metal levels of different varieties of fresh water fish using Inductively Coupled Plasma Mass Spectrophotometer after microwave digestion (MD-ICPMS. Fish samples were collected from the outlets of twin cities of Hyderabad and Secunderabad. The trace metal content in different varieties of analyzed fish were ranged from 0.24 to 1.68 mg/kg for Chromium in Cyprinus carpio and Masto symbollon, 0.20 to 7.52 mg/kg for Manganese in Labeo rohita and Masto symbollon, 0.006 to 0.07 mg/kg for Cobalt in Rastrelliger kanagurta and Pampus argenteus, 0.31 to 2.24 mg/kg for Copper in Labeo rohita and Penaeus monodon, 3.25 to 14.56 mg/kg for Zinc in Cyprinus carpio and Macrobrachium rosenbergii, and 0.01 to 2.05 mg/kg for Selenium in Rastrelliger kanagurta and Pampus argenteus, respectively. Proximate composition data for the different fishes were also tabulated. Since the available data for different trace elements for fish is scanty, here an effort is made to present a precise data for the same as estimated on ICP-MS. Results were in accordance with recommended daily intake allowance by WHO/FAO.

  3. Retrieval of atmospheric water vapor content in polar regions using spaceborne microwave radiometry; Bestimmung des atmosphaerischen Wasserdampfgehaltes in Polargebieten mit Hilfe der passiven Mikrowellenradiometrie

    Energy Technology Data Exchange (ETDEWEB)

    Miao, J. [Bremen Univ. (Germany). Inst. fuer Umweltphysik

    1998-12-31

    The concern on the possibly adverse effects of global warming has made monitoring the Earth environment a high priority item. Satellites have been widely used since the 60`s to measure atmospheric parameters from space. Over open oceans, the atmospheric water vapor content has been successfully measured using passive microwave radiometry. However, this measurement was limited to the non polar regions. The difficulties encountered in polar regions arise from the very low water vapor burden of the atmosphere and from the highly variable surface conditions of polar ice. It is the goal of this thesis to improve this situation by carefully investigating the information content of the Special Sensor Microwave/Water Vapor (SSM/T2), which is part of the United States Defense Meteorological Satellite Program (DMSP). SSM/T2 has three channels located on the wing of the storage water vapor absorption line at 183.31 GHz and is therefore very sensitive to water vapor. In addition, the center frequencies of these channels are close enough, so that the polar ice shows nearly the same emission properties at all these channels. On the contrary, these channels have quite different sensitivities to water vapor, therefore it appears possible to extract information on tropospheric water vapor. (orig.)

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  6. Radiometer calibration methods and resulting irradiance differences: Radiometer calibration methods and resulting irradiance differences

    Energy Technology Data Exchange (ETDEWEB)

    Habte, Aron [National Renewable Energy Laboratory, Golden CO 80401 USA; Sengupta, Manajit [National Renewable Energy Laboratory, Golden CO 80401 USA; Andreas, Afshin [National Renewable Energy Laboratory, Golden CO 80401 USA; Reda, Ibrahim [National Renewable Energy Laboratory, Golden CO 80401 USA; Robinson, Justin [GroundWork Renewables Inc., Logan UT 84321 USA

    2016-10-07

    Accurate solar radiation measured by radiometers depends on instrument performance specifications, installation method, calibration procedure, measurement conditions, maintenance practices, location, and environmental conditions. This study addresses the effect of different calibration methodologies and resulting differences provided by radiometric calibration service providers such as the National Renewable Energy Laboratory (NREL) and manufacturers of radiometers. Some of these methods calibrate radiometers indoors and some outdoors. To establish or understand the differences in calibration methodologies, we processed and analyzed field-measured data from radiometers deployed for 10 months at NREL's Solar Radiation Research Laboratory. These different methods of calibration resulted in a difference of +/-1% to +/-2% in solar irradiance measurements. Analyzing these differences will ultimately assist in determining the uncertainties of the field radiometer data and will help develop a consensus on a standard for calibration. Further advancing procedures for precisely calibrating radiometers to world reference standards that reduce measurement uncertainties will help the accurate prediction of the output of planned solar conversion projects and improve the bankability of financing solar projects.

  7. Low-cost microwave radiometry for remote sensing of soil moisture

    Science.gov (United States)

    Chikando, Eric Ndjoukwe

    2007-12-01

    Remote sensing is now widely regarded as a dominant means of studying the Earth and its surrounding atmosphere. This science is based on blackbody theory, which states that all objects emit broadband electromagnetic radiation proportional to their temperature. This thermal emission is detectable by radiometers---highly sensitive receivers capable of measuring extremely low power radiation across a continuum of frequencies. In the particular case of a soil surface, one important parameter affecting the emitted radiation is the amount of water content or, soil moisture. A high degree of precision is required when estimating soil moisture in order to yield accurate forecasting of precipitations and short-term climate variability such as storms and hurricanes. Rapid progress within the remote sensing community in tackling current limitations necessitates an awareness of the general public towards the benefits of the science. Information about remote sensing instrumentation and techniques remain inaccessible to many higher-education institutions due to the high cost of instrumentation and the current general inaccessibility of the science. In an effort to draw more talent within the field, more affordable and reliable scientific instrumentation are needed. This dissertation introduces the first low-cost handheld microwave instrumentation fully capable of surface soil moisture studies. The framework of this research is two-fold. First, the development of a low-cost handheld microwave radiometer using the well-known Dicke configuration is examined. The instrument features a super-heterodyne architecture and is designed following a microwave integrated circuit (MIC) system approach. Validation of the instrument is performed by applying it to various soil targets and comparing measurement results to gravimetric technique measured data; a proven scientific method for determining volumetric soil moisture content. Second, the development of a fully functional receiver RF front

  8. Irradiation, microwave and alternative energy-based treatments for low water activity foods

    Science.gov (United States)

    There is an increasing recognition of low water activity foods as vectors for human pathogens. Partially or fully dried agricultural commodities, along with modern formulated dried food products, are complex, and designed to meet a variety of nutritional, sensory, and market-oriented goal. This comp...

  9. Real-time microwave sensor system for detection of polluting substances in pure water

    Science.gov (United States)

    Neves, A. L.; Georget, E.; Cochinaire, N.; Sabouroux, P.

    2017-08-01

    In the present work, a real-time coaxial sensor for detecting foreign substances in aqueous solutions was developed and tested. This tool, based on a coaxial propagation line for determining the electromagnetic parameters of materials, was updated into a liquid permittivity monitoring sensor of continuous flow. A few solutions of different nature were tested, and while adding a liquid or electrolyte substance, named "pollutant," variations in the base solution were documented. Ethanol and water mixtures were used as reference, while the ability of the system to detect emulsions (such as oil in water solutions) was also evaluated. The system shows great potential for the quantification and qualification of liquid mixtures, having a threshold of reduced volume/volume fractions of foreign substances or pollutants, a property which is shown to be extremely useful in an analogue of high glycaemia (diabetes disease)—thus, opening the possibilities of monitoring biological liquids.

  10. MACHYDRO-90 - The microwave aircraft experiment for hydrology

    Science.gov (United States)

    Engman, Edwin T.

    1991-01-01

    MACHYDRO-90 is a multisensor aircraft campaign (MAC) that was held in central Pennsylvania over an eleven day period in July 1990. The emphasis of the campaign was on the microwave measurements of soil moisture, although other aspects of hydrology and microwave-target interactions were also studied. A description is given of the experiment, its organization, and the meteorological conditions during the eleven days. Preliminary results are also presented from PBMR (Push-Broom Microwave Radiometer) and SAR (synthetic aperture radar) measurements of soil moisture. These results are portrayed in the context of the hydrology, which, during this experiment, exhibited dry and wet extremes.

  11. EDITORIAL: Microwave Moisture Measurements

    Science.gov (United States)

    Kaatze, Udo; Kupfer, Klaus; Hübner, Christof

    2007-04-01

    Microwave moisture measurements refer to a methodology by which the water content of materials is non-invasively determined using electromagnetic fields of radio and microwave frequencies. Being the omnipresent liquid on our planet, water occurs as a component in most materials and often exercises a significant influence on their properties. Precise measurements of the water content are thus extremely useful in pure sciences, particularly in biochemistry and biophysics. They are likewise important in many agricultural, technical and industrial fields. Applications are broad and diverse, and include the quality assessment of foodstuffs, the determination of water content in paper, cardboard and textile production, the monitoring of moisture in sands, gravels, soils and constructions, as well as the measurement of water admixtures to coal and crude oil in reservoirs and in pipelines. Microwave moisture measurements and evaluations require insights in various disciplines, such as materials science, dielectrics, the physical chemistry of water, electrodynamics and microwave techniques. The cooperation of experts from the different fields of science is thus necessary for the efficient development of this complex discipline. In order to advance cooperation the Workshop on Electromagnetic Wave Interaction with Water and Moist Substances was held in 1993 in Atlanta. It initiated a series of international conferences, of which the last one was held in 2005 in Weimar. The meeting brought together 130 scientists and engineers from all over the world. This special issue presents a collection of some selected papers that were given at the event. The papers cover most topics of the conference, featuring dielectric properties of aqueous materials, electromagnetic wave interactions, measurement methods and sensors, and various applications. The special issue is dedicated to Dr Andrzej W Kraszewski, who died in July 2006 after a distinguished career of 48 years in the research of

  12. Ozone monitoring with an infrared heterodyne radiometer

    Science.gov (United States)

    Menzies, R. T.; Seals, R. K., Jr.

    1977-01-01

    Measurements of the total burden and of the concentration-versus-altitude profiles of ozone have been made with a ground-based heterodyne radiometer at Pasadena, California. The measurements were made in the 9.5-micron wavelength region, where a strong ozone infrared absorption band exists. The radiometer measured solar absorption at selected wavelengths with a spectral resolution of 0.001 reciprocal centimeter, equivalent to the half-width of an ozone absorption line at the 10-millibar altitude level. A carbon dioxide laser served as the local oscillator. This technique can be used to gather important data on both tropospheric and stratospheric ozone, which are not readily accessible with other remote-sensing techniques.

  13. Dual-Polarization, Multi-Frequency Antenna Array for use with Hurricane Imaging Radiometer

    Science.gov (United States)

    Little, John

    2013-01-01

    Advancements in common aperture antenna technology were employed to utilize its proprietary genetic algorithmbased modeling tools in an effort to develop, build, and test a dual-polarization array for Hurricane Imaging Radiometer (HIRAD) applications. Final program results demonstrate the ability to achieve a lightweight, thin, higher-gain aperture that covers the desired spectral band. NASA employs various passive microwave and millimeter-wave instruments, such as spectral radiometers, for a range of remote sensing applications, from measurements of the Earth's surface and atmosphere, to cosmic background emission. These instruments such as the HIRAD, SFMR (Stepped Frequency Microwave Radiometer), and LRR (Lightweight Rainfall Radiometer), provide unique data accumulation capabilities for observing sea surface wind, temperature, and rainfall, and significantly enhance the understanding and predictability of hurricane intensity. These microwave instruments require extremely efficient wideband or multiband antennas in order to conserve space on the airborne platform. In addition, the thickness and weight of the antenna arrays is of paramount importance in reducing platform drag, permitting greater time on station. Current sensors are often heavy, single- polarization, or limited in frequency coverage. The ideal wideband antenna will have reduced size, weight, and profile (a conformal construct) without sacrificing optimum performance. The technology applied to this new HIRAD array will allow NASA, NOAA, and other users to gather information related to hurricanes and other tropical storms more cost effectively without sacrificing sensor performance or the aircraft time on station. The results of the initial analysis and numerical design indicated strong potential for an antenna array that would satisfy all of the design requirements for a replacement HIRAD array. Multiple common aperture antenna methodologies were employed to achieve exceptional gain over the entire

  14. Continuous Water Vapor Profiles for the Fixed Atmospheric Radiation Measurement Sites

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Troyan, D. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2006-01-09

    The Atmospheric Radiation Measurement (ARM) Program defined a specific metric for the first quarter of Fiscal Year 2006 to complete a continuous time series of the vertical profile of water vapor for selected 30-day periods from each of the fixed ARM sites. In order to accomplish this metric, a new technique devised to incorporate radiosonde data, microwave radiometer data and analysis information from numerical weather forecast models has been developed. The product of this analysis, referred to as the merged sounding value-added product, includes vertical profiles of atmospheric water vapor concentration and several other important thermodynamic state variables at 1-minute time intervals and 266 vertical levels.

  15. Oxidative decomposition of atrazine in water in the presence of hydrogen peroxide using an innovative microwave photochemical reactor

    Energy Technology Data Exchange (ETDEWEB)

    Chen Huilun [Department of Environmental Engineering, Civil and Environment Engineering School, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing 100083 (China); Italian National Research Council-Istituto di Chimica dei Composti Organometallici (ICCOM), Via G. Moruzzi 1, 56124 Pisa (Italy); Bramanti, Emilia, E-mail: ebramanti@iccom.cnr.it [Italian National Research Council-Istituto di Chimica dei Composti Organometallici (ICCOM), Via G. Moruzzi 1, 56124 Pisa (Italy); Longo, Iginio [Italian National Research Council-National Institute of Optics (INO), Via G. Moruzzi 1, 56124 Pisa (Italy); Onor, Massimo [Italian National Research Council-Istituto di Chimica dei Composti Organometallici (ICCOM), Via G. Moruzzi 1, 56124 Pisa (Italy); Ferrari, Carlo [Italian National Research Council-National Institute of Optics (INO), Via G. Moruzzi 1, 56124 Pisa (Italy)

    2011-02-28

    The simultaneous application of microwave (MW) power and UV light leads to improved results in photochemical processes. This study investigates the oxidative decomposition of atrazine in water using an innovative MW and UV photochemical reactor, which activates a chemical reaction with MW and UV radiation using an immersed source without the need for a MW oven. We investigated the influence of reaction parameters such as initial H{sub 2}O{sub 2} concentrations, reaction temperatures and applied MW power and identified the optimal conditions for the oxidative decomposition of atrazine. Atrazine was completely degraded by MW/UV/H{sub 2}O{sub 2} in a very short time (i.e. t{sub 1/2} = 1.1 min for 20.8 mg/L in optimal conditions). From the kinetic study, the disappearance rate of atrazine can be expressed as dX/dt = k{sub PH}[M]{sub 0}(b - X)(1 - X), where b {identical_to} [H{sub 2}O{sub 2}]{sub 0}/[M]{sub 0} + k{sub OH}[{center_dot}OH]/k{sub PH}[M]{sub 0}, and X is the atrazine conversion, which correlates well with the experimental data. The kinetic analysis also showed that an indirect reaction of atrazine with an OH radical is dominant at low concentrations of H{sub 2}O{sub 2} and a direct reaction of atrazine with H{sub 2}O{sub 2} is dominant when the concentration of H{sub 2}O{sub 2} is more than 200 mg/L.

  16. Microwave Microscope

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Makes ultra-high-resolution field measurements. The Microwave Microscope (MWM) has been used in support of several NRL experimental programs involving sea...

  17. Total Power Radiometer for Medical Sensor Applications Using Matched and Mismatched Noise Sources.

    Science.gov (United States)

    Park, Woojin; Jeong, Jinho

    2017-09-14

    This paper presents a simple total power radiometer to noninvasively measure the temperature of the human body. The proposed 3-GHz radiometer consists of an antenna collecting the noise power generated by a target, a low-noise and high-gain receiver amplifying the noise power, and a detector converting the noise power to voltage. A single-pole-triple-throw (SP3T) switch is placed between the antenna and the receiver, while a personal computer is used to control the SP3T switch, collect and process the data such as detector output voltages and physical temperatures of the reference noise sources and the target. The fabricated radiometer shows a good performance agreement with a thermometer in the temperature measurement of water from 25.0 to 43.1 °C. For the accurate prediction of the target temperature, the radiometer is calibrated adaptively to the environment and radiometer variations. For this purpose, two reference noise sources (hot and cold) are proposed using matched and mismatched resistors at room temperature. These resistor-based noise sources offer a reliable performance without complex temperature control systems. Furthermore, they can be easily calibrated in real time by periodically measuring the physical temperatures of the resistors. In addition, the logarithmic detector with wide dynamic range is adopted and logarithmically-fitted based on the measurement results instead of linear approximation, which reduces the error caused by the limited dynamic range of resistor-based noise sources. In order to further increase the accuracy, the performance imbalances between ports in the SP3T switch are also taken into account by employing offsets in the radiometer output voltages.

  18. Space-qualified submillimeter radiometer

    Science.gov (United States)

    Huguenin, G. R.

    1987-01-01

    The purpose of this research was to develop a reliable submillimeter wave spectrometer for space-borne high frequency spectral line work. The emphasis was on improving the efficiency of frequency multipliers to limit the system components to rugged, low power consumption solid-state devices. This research has allowed Millitech to develop increased efficiency and performance in Millitech's existing line of submillimeter components and systems. Millitech has fabricated and tested a complete solid-state spectrometer front end for use at 560 GHz (the 1(sub 10) to 1(sub 01) transition of water vapor). The spectrometer was designed with the rigors of flight conditions in mind. The spectrometer uses a phase-locked, solid-state Gunn diode oscillator as the local oscillator, employing a tripler to produce about 3 mW of power at 285 GHz, and a low noise second harmonic waveguide mixer which requires less than 2 mW of LO power. The LO (and the signal) is injected into the mixer by means of a quasioptical diplexer. The measured system noise temperature is 2800 K (DSB) over 400 MHz. The whole spectrometer front end is compact (21 cm by 21 cm by 24 cm), light (7.4 kg), and has a power consumption of less than 8 W. Other topics explored in this work include compact frequency agile phase lock loops, optical filters, and InP Gunn oscillators for low noise applications. As a result of this research, the improvement in the design of multipliers and harmonic mixers will allow their use as the LO power for a variety of satellite-borne receivers operating in the 200 to 600 GHz frequency range.

  19. [Determination of sodium, magnesium, calcium, lithium and strontium in natural mineral drinking water by microwave plasma torch spectrometer with nebulization sample introduction system].

    Science.gov (United States)

    Zhou, Wei; Xiong, Hai-long; Feng, Guo-dong; Yu, Ai-min; Chen, Huan-wen

    2014-06-01

    The microwave plasma torch (MPT) was used as the emission light source. Aqueous samples were introduced with a nebulizer and a desolvation system. A method for the determination of Na, Mg, Ca, Li and Sr in natural mineral drinking water by argon microwave plasma torch spectrometer (ArMPT spectrometer) was established. The effects of microwave power, flow rate of carrier gas and support gas were investigated in detail and these parameters were optimized. Under the optimized condition, the experiments for the determination of Na, Mg, Ca, Li and Sr in 11 kinds of bottled mineral drinking water were carried out by ArMPT spectrometer. The limit-of-detection (LOD) of Na, Mg, Ca, Li and Sr was found to be 4.4, 21, 56, 11 and 84 μg x mL(-1), respectively. Relative standard deviation (n = 6) was in the range of 1.30%-5.45% and standard addition recoveries were in the range of 84.6%-98.5%. MPT spectrometer was simpler, more convenient and of lower cost as compared to ICP unit. MPT spectrometer demonstrated its rapid analysis speed, accuracy, sensitivity and simultaneous multi element analysis ability during the analysis process. The results showed that MPT spectrometer was suitable for metal elements detection for natural mineral drinking water. This approach provides not only one way for resisting the illegal dealings, but also a security for the quality of drinking water. Moreover, the usability of MPT spectrometer in the field of food security; drug safety; clinical diagnostic is promised.

  20. Performance of a novel microwave-based treatment technology for atrazine removal and destruction: Sorbent reusability and chemical stability, and effect of water matrices

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Erdan; Hu, Yuanan [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Cheng, Hefa, E-mail: hefac@umich.edu [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); MOE Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871 (China)

    2015-12-15

    Highlights: • Cu{sup 2+} and Fe{sup 3+} in zeolite pores enhance atrazine sorption and MW-induced degradation. • Exchanged zeolites perform well over multiple sorption–regeneration cycles. • Fe{sup 3+} species in the zeolite micropores have much greater stability than those of Cu{sup 2+}. • DOC in natural waters can compromise the sorption capacity of exchanged zeolites. • Iron-exchanged dealuminated Y zeolites hold great promise for practical applications. - Abstract: Transition metal-exchanged dealuminated Y zeolites were used to adsorb atrazine from aqueous solutions, followed by regeneration of the sorbents and destruction of the sorbed atrazine with microwave irradiation. Exchange of copper and iron into the zeolite's micropores significantly enhanced its sorption capacity and selectivity toward atrazine, and increased the microwave-induced degradation rate of the sorbed atrazine by 3–4-folds. Both the copper- and iron-exchanged zeolites could be regenerated and reused multiple times, while the catalytic activity of the latter was more robust due to the much greater chemical stability of Fe{sup 3+} species in the micropores. The presence of humic acid, and common cations and anions had little impact on the sorption of atrazine on the transition metal-exchanged zeolites. In the treatment of atrazine spiked in natural surface water and groundwater samples, sorptive removal of atrazine was found to be impacted by the level of dissolved organic carbon, probably through competition for the micropore spaces and pore blocking, while the water matrices exhibited no strong effect on the microwave-induced degradation of sorbed atrazine. Overall, iron-exchanged dealuminated Y zeolites show great potential for removal and destruction of atrazine from contaminated surface water and groundwater in practical implementation of the novel treatment technology.

  1. Improved detectability in medical microwave radio-thermometers as obtained by active antennas.

    Science.gov (United States)

    Jacobsen, Svein; Klemetsen, Øystein

    2008-12-01

    Microwave radiometry is a spectral measurement technique for resolving blackbody radiation of heated matter above absolute zero. The emission levels vary with frequency and are at body temperatures maximized in the infrared spectral band. Medical radio-thermometers are mostly noninvasive short-range instruments that can provide temperature distributions in subcutaneous biological tissues when operated in the microwave region. However, a crucial limitation of the microwave radiometric observation principle is the extremely weak signal level of the thermal noise emitted by the lossy material (-174 dBm/Hz at normal body temperature). To improve the radiometer SNR, we propose to integrate a tiny, moderate gain, low-noise preamplifier (LNA) close to the antenna terminals as to obtain increased detectability of deep seated thermal gradients within the volume under investigation. The concept is verified experimentally in a lossy phantom medium by scanning an active antenna across a thermostatically controlled water phantom with a hot object embedded at 38 mm depth. Three different setups were investigated with decreasing temperature contrasts between the target and ambient medium. As a direct consequence of less ripple on the raw radiometric signal, statistical analysis shows a marked increase in signal-to-clutter ratio of the brightness temperature spatial scan profiles, when comparing active antenna operation with conventional passive setups.

  2. IAP RAS microwave radiometry complex: sounding atmospheric thermal structure from the ground up to 55km.

    Science.gov (United States)

    Belikovich, Mikhail; Shvetsov, Alexander; Ryskin, Vitaly; Mukhin, Dmitry; Kulikov, Mikhail; Feigin, Alexander

    2016-04-01

    Thermal structure is the key characteristic of the atmosphere. Depending on the altitude, it is measured by different methods. In troposphere a plethora of in-situ techniques exists while in middle atmosphere remote sensing is primary type of measurement. The remote sensing is conducted in different wavelengths: optical, infrared and microwave. Satellite based measurements are the most popular kind of remote sensing measurements as it provides global coverage. Ground based passive microwave remote sensing technique has its place when one need permanent monitoring with high time resolution in order to study short-term local events like gravity waves. Institute of Applied Physics of the Russian Academy of Sciences (IAP RAS) develops multi-purpose radiometry complex for constant atmospheric monitoring. For now, it measures temperature profiles from ground to 55km, tropospheric water vapor and ozone. It consists of several radiometers with spectral bands ranging from 20 to 112 GHz. In 2015 two radiometers were added in order to measure thermal structure at surface level and troposphere: scanning device operating in 55-59GHz, and device at 50-55GHz. The change led to modifying the retrieval software. The work presents the description of the radiometry complex and corresponding retrieval software. The main part is devoted to new radiometers and enhancements in retrieval procedure. The retrieval algorithms are described: for each device separately and for the whole temperature retrieval part of the complex. The use of the single procedure for the group of radiometers helps to merge the profile with each other correctly. The main issue of the single procedure (numerical complexity aside) is dealing with the possible difference in calibration of the devices. Error analysis of the procedures is conducted. The characteristics of the complex and the retrieval algorithms are presented. The capabilities of the algorithms are shown on simulated and real data; the last one was

  3. Engineered biochar from microwave-assisted catalytic pyrolysis of switchgrass for increasing water-holding capacity and fertility of sandy soil

    Energy Technology Data Exchange (ETDEWEB)

    Mohamed, Badr A. [Department of Chemical and Biological Engineering, University of British Columbia, Vancouver BC V6T 1Z3 (Canada); Agricultural Engineering Department, Cairo University, Giza (Egypt); Ellis, Naoko [Department of Chemical and Biological Engineering, University of British Columbia, Vancouver BC V6T 1Z3 (Canada); Kim, Chang Soo [Department of Chemical and Biological Engineering, University of British Columbia, Vancouver BC V6T 1Z3 (Canada); Clean Energy Research Center, Korea Institute of Science and Technology, 14 gil 5 Hwarang-no Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Bi, Xiaotao, E-mail: tony.bi@ubc.ca [Department of Chemical and Biological Engineering, University of British Columbia, Vancouver BC V6T 1Z3 (Canada); Emam, Ahmed El-raie [Agricultural Engineering Department, Cairo University, Giza (Egypt)

    2016-10-01

    Engineered biochars produced from microwave-assisted catalytic pyrolysis of switchgrass have been evaluated in terms of their ability on improving water holding capacity (WHC), cation exchange capacity (CEC) and fertility of loamy sand soil. The addition of K{sub 3}PO{sub 4}, clinoptilolite and/or bentonite as catalysts during the pyrolysis process increased biochar surface area and plant nutrient contents. Adding biochar produced with 10 wt.% K{sub 3}PO{sub 4} + 10 wt.% clinoptilolite as catalysts to the soil at 2 wt% load increased soil WHC by 98% and 57% compared to the treatments without biochar (control) and with 10 wt.% clinoptilolite, respectively. Synergistic effects on increased soil WHC were manifested for biochars produced from combinations of two additives compared to single additive, which may be the result of increased biochar microporosity due to increased microwave heating rate. Biochar produced from microwave catalytic pyrolysis was more efficient in increasing the soil WHC due to its high porosity in comparison with the biochar produced from conventional pyrolysis at the same conditions. The increases in soil CEC varied widely compared to the control soil, ranging from 17 to 220% for the treatments with biochars produced with 10 wt% clinoptilolite at 400 °C, and 30 wt% K{sub 3}PO{sub 4} at 300 °C, respectively. Strong positive correlations also exist among soil WHC with CEC and biochar micropore area. Biochar from microwave-assisted catalytic pyrolysis appears to be a novel approach for producing biochar with high sorption affinity and high CEC. These catalysts remaining in the biochar product would provide essential nutrients for the growth of bioenergy and food crops. - Highlights: • High quality biochar was made by catalytic pyrolysis in a microwave reactor. • High heating rate and good biochar quality were achieved using K{sub 3}PO{sub 4} and clinoptilolite mixture. • Biochars showed significant increase in soil WHC and CEC.

  4. Synergistic Utilization of Microwave Satellite Data and GRACE-Total Water Storage Anomaly for Improving Available Water Capacity Prediction in Lower Mekong Basin

    Science.gov (United States)

    Gupta, M.; Bolten, J. D.; Lakshmi, V.

    2015-12-01

    The Mekong River is the longest river in Southeast Asia and the world's eighth largest in discharge with draining an area of 795,000 km² from the eastern watershed of the Tibetan Plateau to the Mekong Delta including three provinces of China, Myanmar, Lao PDR, Thailand, Cambodia and Viet Nam. This makes the life of people highly vulnerable to availability of the water resources as soil moisture is one of the major fundamental variables in global hydrological cycles. The day-to-day variability in soil moisture on field to global scales is an important quantity for early warning systems for events like flooding and drought. In addition to the extreme situations the accurate soil moisture retrieval are important for agricultural irrigation scheduling and water resource management. The present study proposes a method to determine the effective soil hydraulic parameters directly from information available for the soil moisture state from the recently launched SMAP (L-band) microwave remote sensing observations. Since the optimized parameters are based on the near surface soil moisture information, further constraints are applied during the numerical simulation through the assimilation of GRACE Total Water Storage (TWS) within the physically based land surface model. This work addresses the improvement of available water capacity as the soil hydraulic parameters are optimized through the utilization of satellite-retrieved near surface soil moisture. The initial ranges of soil hydraulic parameters are taken in correspondence with the values available from the literature based on FAO. The optimization process is divided into two steps: the state variable are optimized and the optimal parameter values are then transferred for retrieving soil moisture and streamflow. A homogeneous soil system is considered as the soil moisture from sensors such as AMSR-E/SMAP can only be retrieved for the top few centimeters of soil. To evaluate the performance of the system in helping

  5. Engineered biochar from microwave-assisted catalytic pyrolysis of switchgrass for increasing water-holding capacity and fertility of sandy soil.

    Science.gov (United States)

    Mohamed, Badr A; Ellis, Naoko; Kim, Chang Soo; Bi, Xiaotao; Emam, Ahmed El-Raie

    2016-10-01

    Engineered biochars produced from microwave-assisted catalytic pyrolysis of switchgrass have been evaluated in terms of their ability on improving water holding capacity (WHC), cation exchange capacity (CEC) and fertility of loamy sand soil. The addition of K3PO4, clinoptilolite and/or bentonite as catalysts during the pyrolysis process increased biochar surface area and plant nutrient contents. Adding biochar produced with 10wt.% K3PO4+10 wt.% clinoptilolite as catalysts to the soil at 2wt% load increased soil WHC by 98% and 57% compared to the treatments without biochar (control) and with 10wt.% clinoptilolite, respectively. Synergistic effects on increased soil WHC were manifested for biochars produced from combinations of two additives compared to single additive, which may be the result of increased biochar microporosity due to increased microwave heating rate. Biochar produced from microwave catalytic pyrolysis was more efficient in increasing the soil WHC due to its high porosity in comparison with the biochar produced from conventional pyrolysis at the same conditions. The increases in soil CEC varied widely compared to the control soil, ranging from 17 to 220% for the treatments with biochars produced with 10wt% clinoptilolite at 400°C, and 30wt% K3PO4 at 300°C, respectively. Strong positive correlations also exist among soil WHC with CEC and biochar micropore area. Biochar from microwave-assisted catalytic pyrolysis appears to be a novel approach for producing biochar with high sorption affinity and high CEC. These catalysts remaining in the biochar product would provide essential nutrients for the growth of bioenergy and food crops.

  6. Microwave brightness temperature and thermal inertia - towards synergistic method of high-resolution soil moisture retrieval

    Science.gov (United States)

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

    2017-04-01

    Soil moisture is an important parameter in many environmental studies, as it influences the exchange of water and energy at the interface between the land surface and the atmosphere. Accurate assessment of the soil moisture spatial and temporal variations is crucial for numerous studies; starting from a small scale of single field, then catchment, mesoscale basin, ocean conglomeration, finally ending at the global water cycle. Despite numerous advantages, such as fine accuracy (undisturbed by clouds or daytime conditions) and good temporal resolution, passive microwave remote sensing of soil moisture, e.g. SMOS and SMAP, are not applicable to a small scale - simply because of too coarse spatial resolution. On the contrary, thermal infrared-based methods of soil moisture retrieval have a good spatial resolution, but are often disturbed by clouds and vegetation interferences or night effects. The methods that base on point measurements, collected in situ by monitoring stations or during field campaigns, are sometimes called "ground truth" and may serve as a reference for remote sensing, of course after some up-scaling and approximation procedures that are, unfortunately, potential source of error. Presented research concern attempt to synergistic approach that join two remote sensing methods: passive microwave and thermal infrared, supported by in situ measurements. Microwave brightness temperature of soil was measured by ELBARA, the radiometer at 1.4 GHz frequency, installed at 6 meters high tower at Bubnow test site in Poland. Thermal inertia around the tower was modelled using the statistical-physical model whose inputs were: soil physical properties, its water content, albedo and surface temperatures measured by an infrared pyrometer, directed at the same footprint as ELBARA. The results coming from this method were compared to in situ data obtained during several field campaigns and by the stationary agrometeorological stations. The approach seems to be

  7. An assessment of arctic sea ice concentration retrieval based on “HY-2” scanning radiometer data using field observations during CHINARE-2012 and other satellite instruments

    Institute of Scientific and Technical Information of China (English)

    SHI Lijiang; LU Peng; CHENG Bin; KARVONEN Juha; WANG Qimao; LI Zhijun; HAN Hongwei

    2015-01-01

    A retrieval algorithm of arctic sea ice concentration (SIC) based on the brightness temperature data of “HY-2” scanning microwave radiometer has been constructed. The tie points of the brightness temperature were selected based on the statistical analysis of a polarization gradient ratio and a spectral gradient ratio over open water (OW), first-year ice (FYI), and multiyear ice (MYI) in arctic. The thresholds from two weather filters were used to reduce atmospheric effects over the open ocean. SIC retrievals from the “HY-2” radiom-eter data for idealized OW, FYI, and MYI agreed well with theoretical values. The 2012 annual SIC was calcu-lated and compared with two reference operational products from the National Snow and Ice Data Center (NSIDC) and the University of Bremen. The total ice-covered area yielded by the “HY-2” SIC was consistent with the results from the reference products. The assessment of SIC with the aerial photography from the fifth Chinese national arctic research expedition (CHINARE) and six synthetic aperture radar (SAR) images from the National Ice Service was carried out. The “HY-2” SIC product was 16% higher than the values de-rived from the aerial photography in the central arctic. The root-mean-square (RMS) values of SIC between “HY-2” and SAR were comparable with those between the reference products and SAR, varying from 8.57% to 12.34%. The “HY-2” SIC is a promising product that can be used for operational services.

  8. Microwave assisted synthesis of polyacrylamide grafted starch (St-g-PAM) and its applicability as flocculant for water treatment.

    Science.gov (United States)

    Mishra, Sumit; Mukul, Ankita; Sen, Gautam; Jha, Usha

    2011-01-01

    Polyacrylamide grafted starch (St-g-PAM) was made by a novel method of synthesis, involving combination of microwave radiation and a chemical free radical initiator (ceric ammonium nitrate) to initiate grafting reaction. This method (microwave assisted synthesis) is quick, highly reliable, reproducible and yields high quality product as compared to the conventional method (which uses a chemical free radical initiator alone to initiate the grafting reaction).The St-g-PAM grades synthesized were characterized by various physicochemical techniques. Further, its application as flocculant for wastewater treatment was investigated.

  9. Satellite microwave assessment of Northern Hemisphere lake ice phenology from 2002 to 2015

    Science.gov (United States)

    Du, Jinyang; Kimball, John S.; Duguay, Claude; Kim, Youngwook; Watts, Jennifer D.

    2017-01-01

    A new automated method enabling consistent satellite assessment of seasonal lake ice phenology at 5 km resolution was developed for all lake pixels (water coverage ≥ 90 %) in the Northern Hemisphere using 36.5 GHz H-polarized brightness temperature (Tb) observations from the Advanced Microwave Scanning Radiometer for EOS and Advanced Microwave Scanning Radiometer 2 (AMSR-E/2) sensors. The lake phenology metrics include seasonal timing and duration of annual ice cover. A moving t test (MTT) algorithm allows for automated lake ice retrievals with daily temporal fidelity and 5 km resolution gridding. The resulting ice phenology record shows strong agreement with available ground-based observations from the Global Lake and River Ice Phenology Database (95.4 % temporal agreement) and favorable correlations (R) with alternative ice phenology records from the Interactive Multisensor Snow and Ice Mapping System (R = 0.84 for water clear of ice (WCI) dates; R = 0.41 for complete freeze over (CFO) dates) and Canadian Ice Service (R = 0.86 for WCI dates; R = 0.69 for CFO dates). Analysis of the resulting 12-year (2002-2015) AMSR-E/2 ice record indicates increasingly shorter ice cover duration for 43 out of 71 (60.6 %) Northern Hemisphere lakes examined, with significant (p regional trends toward earlier ice melting for only five lakes. Higher-latitude lakes reveal more widespread and larger trends toward shorter ice cover duration than lower-latitude lakes, consistent with enhanced polar warming. This study documents a new satellite-based approach for rapid assessment and regional monitoring of seasonal ice cover changes over large lakes, with resulting accuracy suitable for global change studies.

  10. A new radiometer for earth radiation budget studies

    Energy Technology Data Exchange (ETDEWEB)

    Weber, P.G.

    1992-01-01

    A critical need for the US Global Change Research Program is to provide continuous, well-calibrated radiometric data for radiation balance studies. This paper describes a new, compact, relatively light-weight, adaptable radiometer which will provide both spectrally integrated measurements and data in selected spectral bands. The radiometer design is suitable for use on (small) satellites, aircraft, or Unmanned Aerospace Vehicles (UAVs). Some considerations for the implementation of this radiometer on a small satellite are given. 17 refs.

  11. Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER)

    Data.gov (United States)

    National Aeronautics and Space Administration — This dataset represents multiple products archived at the Land Processes DAAC for ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) aboard the...

  12. Galileo Net Flux Radiometer Data Analysis

    Science.gov (United States)

    Sromovsky, Lawrence A.

    1999-01-01

    This report describes analysis of the Galileo Net Flux Radiometer (NFR), an instrument mounted on the Galileo probe, a spacecraft designed for entry into and direct measurements of Jupiter's atmosphere. The grant period for NAG2-1028 began on 1 April 1996, nearly four months after Jupiter atmospheric entry on 7 December 1995, and at which time the probe data were fully recovered and quick look analysis completed. This grant supported the detailed data analysis, resulting in a preliminary paper in Science in May 1996 and a final paper in the journal of Geophysical Research in .September 1998, with conference papers presented within this period.

  13. Synthesis and Characterization of Iron-impregnated Pre-oxidized Activated Carbon Prepared by Microwave Radiation for As(V) Removal from Water

    Science.gov (United States)

    Yurum, Yuda; Yurum, Alp; Ozlem Kocabas, Zuleyha; Semiat, Raphael

    2013-04-01

    One of the most efficient ways to treat water is probably by adsorption and catalytic oxidation. Surely, for such a process to be economical, the catalyst and the adsorber should have a high catalytic activity and adsorption capacity, and be inexpensive. One of these materials is iron oxide, which is studied and used in areas like catalysis and environmental applications. It is known that synthesizing iron oxides in nano size enhances the catalytic activity. Pre-oxidized activated carbons impregnated with iron-based nanoparticles are prepared in a single step under hydrothermal conditions with microwave radiation. The hydrothermal treatment provides an important advantage by forming fine particles that can easily impregnate deep in to the porous support by the help of water. Their efficiency for the removal of As(V) from water was compared with the pure pre-oxidized activated carbon and iron oxide nanoparticles impregnated without microwave radiation. The synthesized nanomaterials with different iron oxide loadings were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) surface area analyzer. Iron loadings were calculated using flame atomic absorbance. Microwave radiation provided much faster iron impregnation on the active carbon surface. At the first stage of microwave radiation iron oxide impregnation is low but after 6 minutes, iron oxide nanoparticles of 100 nm size started to cover the surface homogeneously. Further treatment with microwave increased the size of particles and the amount of surface coverage. Additionally, with microwave hydrothermal treatment, relatively higher iron oxide loadings were achieved within 10 minutes. From the XRD characterization it was seen that at the first stage of radiation, iron deposited in the form of β-FeOOH, but after the first stage the structure became Fe2O3. While radiation increased the surface area of the material during the first stages, at the last stage

  14. Microwave Measurements

    CERN Document Server

    Skinner, A D

    2007-01-01

    The IET has organised training courses on microwave measurements since 1983, at which experts have lectured on modern developments. Their lecture notes were first published in book form in 1985 and then again in 1989, and they have proved popular for many years with a readership beyond those who attended the courses. The purpose of this third edition of the lecture notes is to bring the latest techniques in microwave measurements to this wider audience. The book begins with a survey of the theory of current microwave circuits and continues with a description of the techniques for the measureme

  15. Microwave photonics

    CERN Document Server

    Lee, Chi H

    2006-01-01

    Wireless, optical, and electronic networks continue to converge, prompting heavy research into the interface between microwave electronics, ultrafast optics, and photonic technologies. New developments arrive nearly as fast as the photons under investigation, and their commercial impact depends on the ability to stay abreast of new findings, techniques, and technologies. Presenting a broad yet in-depth survey, Microwave Photonics examines the major advances that are affecting new applications in this rapidly expanding field.This book reviews important achievements made in microwave photonics o

  16. Remote monitoring of soil moisture using passive microwave-based technologies – theoretical basic and overview of selected algorithms for AMSR-E

    Science.gov (United States)

    Satellite-based passive microwave remote sensing has been shown to be a valuable tool in mapping and monitoring global soil moisture. The Advanced Microwave Scanning Radiometer on the Aqua platform (AMSR-E) has made significant contributions to this application. As the result of agency and individua...

  17. Microfluidic Radiometal Labeling Systems for Biomolecules

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-12-29

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

  18. Infrared Correlation Radiometer for GEO-CAPE

    Science.gov (United States)

    Neil, D. O.; Boldt, J.; Edwards, D. P.; Yee, J.

    2009-12-01

    We present our plans as part of NASA’s Instrument Incubator Program to characterize the performance of a 2.3 μm infrared correlation radiometer (IRCR) prototype subsystem for an instrument designed specifically to measure carbon monoxide (CO) from geostationary orbit. The Earth Science and Applications Decadal Survey mission GEO-CAPE specifies infrared correlation radiometry to measure CO in two spectral regions. CO measurements at 2.3 μm are uniformly sensitive throughout the troposphere, and 4.7 μm measurements are most sensitive to the free troposphere. In combination, the measurements yield information of this Criteria Pollutant near Earth's surface. The success of NASA’s Shuttle-based Measurement of Air Pollution from Satellites (MAPS) and Terra/MOPITT infrared gas correlation radiometers for CO measurements at 4.7 μm shifts the technology focus toward improving existing 2.3 μm CO measurement capability. GEO-CAPE uses this robust IRCR measurement technique at GEO, nearly 50 times farther away than the Terra/MOPITT orbit, to determine hourly changes in CO across a continental domain. We have structured the IRCR project around an analytical performance model to enable rapid evaluation of design specifics once the mission is defined. We present the architecture of the performance model, and the design of the simulator hardware and test plan which will populate the performance model.

  19. Microwave generator

    Science.gov (United States)

    Kwan, T.J.T.; Snell, C.M.

    1987-03-31

    A microwave generator is provided for generating microwaves substantially from virtual cathode oscillation. Electrons are emitted from a cathode and accelerated to an anode which is spaced apart from the cathode. The anode has an annular slit there through effective to form the virtual cathode. The anode is at least one range thickness relative to electrons reflecting from the virtual cathode. A magnet is provided to produce an optimum magnetic field having the field strength effective to form an annular beam from the emitted electrons in substantial alignment with the annular anode slit. The magnetic field, however, does permit the reflected electrons to axially diverge from the annular beam. The reflected electrons are absorbed by the anode in returning to the real cathode, such that substantially no reflexing electrons occur. The resulting microwaves are produced with a single dominant mode and are substantially monochromatic relative to conventional virtual cathode microwave generators. 6 figs.

  20. Cosmic microwave background theory.

    Science.gov (United States)

    Bond, J R

    1998-01-06

    A long-standing goal of theorists has been to constrain cosmological parameters that define the structure formation theory from cosmic microwave background (CMB) anisotropy experiments and large-scale structure (LSS) observations. The status and future promise of this enterprise is described. Current band-powers in -space are consistent with a DeltaT flat in frequency and broadly follow inflation-based expectations. That the levels are approximately (10(-5))2 provides strong support for the gravitational instability theory, while the Far Infrared Absolute Spectrophotometer (FIRAS) constraints on energy injection rule out cosmic explosions as a dominant source of LSS. Band-powers at 100 suggest that the universe could not have re-ionized too early. To get the LSS of Cosmic Background Explorer (COBE)-normalized fluctuations right provides encouraging support that the initial fluctuation spectrum was not far off the scale invariant form that inflation models prefer: e.g., for tilted Lambda cold dark matter sequences of fixed 13-Gyr age (with the Hubble constant H0 marginalized), ns = 1.17 +/- 0.3 for Differential Microwave Radiometer (DMR) only; 1.15 +/- 0.08 for DMR plus the SK95 experiment; 1.00 +/- 0.04 for DMR plus all smaller angle experiments; 1.00 +/- 0.05 when LSS constraints are included as well. The CMB alone currently gives weak constraints on Lambda and moderate constraints on Omegatot, but theoretical forecasts of future long duration balloon and satellite experiments are shown which predict percent-level accuracy among a large fraction of the 10+ parameters characterizing the cosmic structure formation theory, at least if it is an inflation variant.

  1. Optimum Conditions for Microwave Assisted Extraction for Recovery of Phenolic Compounds and Antioxidant Capacity from Macadamia (Macadamia tetraphylla Skin Waste Using Water

    Directory of Open Access Journals (Sweden)

    Adriana Dailey

    2015-12-01

    Full Text Available This study aimed to develop optimal microwave assisted extraction conditions for recovery of phenolic compounds and antioxidant properties from the macadamia skin, an abundant waste source from the macadamia industry. Water, a safe, accessible, and inexpensive solvent, was used as the extraction solvent and Response Surface Methodology (RSM was applied to design and analyse the conditions for microwave-assisted extraction (MAE. The results showed that RSM models were reliable for the prediction of extraction of phenolic compounds and antioxidant properties. Within the tested ranges, MAE radiation time and power, as well as the sample-to-solvent ratio, affected the extraction efficiency of phenolic compounds, flavonoids, proanthocyanidins, and antioxidant properties of the macadamia skin; however, the impact of these variables was varied. The optimal MAE conditions for maximum recovery of TPC, flavonoids, proanthocyanidins and antioxidant properties from the macadamia skin were MAE time of 4.5 min, power of 30% (360 W and sample-to-water ratio of 5 g/100 mL. Under these conditions, an extract could be prepared with TPC of 45 mg/g, flavonoids of 29 mg RUE/g of dried macadamia skin.

  2. All-sky homogeneity of precipitable water vapour over Paranal

    CERN Document Server

    Querel, Richard R

    2014-01-01

    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. The unit measures several channels across the strong water vapour emission line at 183 GHz, necessary for resolving the low levels of precipitable water vapour (PWV) that are prevalent on Paranal (median ~2.4 mm). The instrument consists of a humidity profiler (183-191 GHz), a temperature profiler (51-58 GHz), and an infrared camera (~10 {\\mu}m) for cloud detection. We present, for the first time, a statistical analysis of the homogeneity of all-sky PWV using 21 months of periodic (every 6 hours) all-sky scans from the radiometer. These data provide unique insight into the spatial and temporal variation of atmospheric conditions relevant for astronomical observations, particularly in the infrared. We find the PWV over Paranal to be remarkably homogeneous across the sky down to 27.5{\\deg} el...

  3. Microwave photonics

    CERN Document Server

    Lee, Chi H

    2013-01-01

    Microwave photonics continues to see rapid growth. The integration of optical fiber and wireless networks has become a commercial reality and is becoming increasingly pervasive. Such hybrid technology will lead to many innovative applications, including backhaul solutions for mobile networks and ultrabroadband wireless networks that can provide users with very high bandwidth services. Microwave Photonics, Second Edition systematically introduces important technologies and applications in this emerging field. It also reviews recent advances in micro- and millimeter-wavelength and terahertz-freq

  4. Water equivalent of snow retrieved from data of passive microwave scanning with the use of artificial neural networks over the Russian Federation territory

    Directory of Open Access Journals (Sweden)

    A. A. Volchek

    2016-01-01

    Full Text Available Using of the Chang model for calculation of the snow water equivalent on the basis of measurements of the Earth thermo-microwave radiation by means of scanning polarimeters (SMMR, SSM/I, AMSR-E from board of orbital satellites does not allow obtaining the accuracy needed hydrological purposes. Low accuracy of the calculations is caused by both simplified character of the mathematical model, and due to significant influence of the surface characteristics (relief, vegetation and complex structure of snow thickness upon the microwave radiation propagation. This work was aimed at finding a way to increase accuracy of calculations of the snow water equivalent on the Russian Federation territory with its different climate conditions by means of application the neural network approach for processing of results of the passive microwave scanning of the Earth surface. Feed-forward multi-layer artificial neural network was trained by back-propagation algorithm using SSM/I data and results of snow water equivalent in situ measurements obtained at 117 meteorological stations during the period from January 1st, 1988 till December 31st, 1988. Validation was performed using data from the same sources collected during 7 years (1992–1998. Results of performed numerical experiments and obtained values of rootmean-square error (σ = 24.9 мм; r = 0.39±0,01 allow coming to conclusion that the best estimation of water equivalent of a snow cover is provided by artificial neural network using as the input data a set of the SSM/I channels 19.35, 37.0, 85.5 GHz of horizontal and vertical polarizations with meteorological data differentiated by types of the snow survey route.It is shown that low correlation coefficients (< 0.5 as compared with similar studies on small areas is not caused by the chosen mathematical model and its realization but it is due to a strong diversity of climatic conditions and low density of meteorological stations on the land areas

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

    Science.gov (United States)

    Harrington, Richard F.

    1994-01-01

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

  6. Water as a green solvent for efficient synthesis of isocoumarins through microwave-accelerated and Rh/Cu-catalyzed C-H/O-H bond functionalization

    Energy Technology Data Exchange (ETDEWEB)

    Li, Qiu; Yan, Yunnan; Wang, Xiaowei; Gong, Binwei; Tang, Xiaobo; Shi, JingJing; Xu, H. Eric; Yi, Wei [Shenyang; (Gannan); (Van Andel); (UST - China); (Chinese Aca. Sci.)

    2014-08-14

    Green chemistry that uses water as a solvent has recently received great attention in organic synthesis. Here we report an efficient synthesis of biologically important isocoumarins through direct cleavage of C–H/O–H bonds by microwave-accelerated and Rh/Cu-catalyzed oxidative annulation of various substituted benzoic acids, where water is used as the only solvent in the reactions. The remarkable features of this “green” methodology include high product yields, wide tolerance of various functional groups as substrates, and excellent region-/site-specificities, thus rendering this methodology a highly versatile and eco-friendly alternative to the existing methods for synthesizing isocoumarins and other biologically important derivatives such as isoquinolones.

  7. Estimating flooded area and mean water level using active and passive microwaves: the example of Paraná River Delta floodplain

    Directory of Open Access Journals (Sweden)

    M. Salvia

    2011-08-01

    Full Text Available This paper describes a procedure to estimate both the fraction of flooded area and the mean water level in vegetated river floodplains by using a synergy of active and passive microwave signatures. In particular, C band Envisat ASAR in Wide Swath mode and AMSR-E at X, Ku and Ka band, are used. The method, which is an extension of previously developed algorithms based on passive data, exploits also model simulations of vegetation emissivity. The procedure is applied to a long flood event which occurred in the Paraná River Delta from December 2009 to April 2010. Obtained results are consistent with in situ measurements of river water level.

  8. Estimating flooded area and mean water level using active and passive microwaves: the example of Paraná River Delta floodplain

    Directory of Open Access Journals (Sweden)

    M. Salvia

    2011-03-01

    Full Text Available This paper describes a procedure to estimate both the fraction of flooded area and the mean water level in vegetated river floodplains by using a synergy of active and passive microwave signatures. In particular, C Band Envisat ASAR in Wide Scan mode and AMSR-E at X, Ku and Ka Band, are used. The method, which is an extension of previously developed algorithms based on passive data, exploits also model simulations of vegetation emissivity. The procedure is applied to a long flood event which occurred in the Paraná River Delta from December 2009 to April 2010. Obtained results are consistent with in situ measurements of river water level.

  9. Novel multi-beam radiometers for accurate ocean surveillance

    DEFF Research Database (Denmark)

    Cappellin, C.; Pontoppidan, K.; Nielsen, P. H.

    2014-01-01

    Novel antenna architectures for real aperture multi-beam radiometers providing high resolution and high sensitivity for accurate sea surface temperature (SST) and ocean vector wind (OVW) measurements are investigated. On the basis of the radiometer requirements set for future SST/OVW missions...

  10. A novel L-band polarimetric radiometer featuring subharmonic sampling

    DEFF Research Database (Denmark)

    Rotbøll, J.; Søbjærg, Sten Schmidl; Skou, Niels

    2003-01-01

    A novel L-band radiometer trading analog components for digital circuits has been designed, built and operated. It is a fully polarimetric radiometer of the correlation type, and it is based on the subharmonic sampling principle in which the L-band signal is directly sampled by a fast A to D...

  11. Seasonal Snow Extent and Snow Mass in South America using SMMR and SSM/I Passive Microwave Data (1979-2006)

    Science.gov (United States)

    Foster, J. L.; Hall, D. K.; Kelly, R. E. J.; Chiu, L.

    2008-01-01

    Seasonal snow cover in South America was examined in this study using passive microwave satellite data from the Scanning Multichannel Microwave Radiometer (SMMR) on board the Nimbus-7 satellite and the Special Sensor Microwave Imagers (SSM/I) onboard Defense Meteorological Satellite Program (DMSP) satellites. For the period from 1979-2006, both snow cover extent and snow water equivalent (snow mass) were investigated during the coldest months (May-September), primarily in the Patagonia area of Argentina and in the Andes of Chile, Argentin