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Sample records for microwave water radiometer

  1. Monolithic microwave integrated circuit water vapor radiometer

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  2. Microwave Radiometer (MWR) Handbook

    SciTech Connect

    Morris, VR

    2006-08-01

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

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

    NASA Astrophysics Data System (ADS)

    Foth, Andreas; Baars, Holger; Di Girolamo, Paolo; Pospichal, Bernhard

    2016-06-01

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

  4. Using Multiple Instrument Measurements To Assess Integrated Water Vapor Path From A Multispectral Microwave Radiometer

    NASA Astrophysics Data System (ADS)

    Fallon, J.; Han, Z. T.; Gross, B.; Moshary, F.

    2013-12-01

    Microwave Radiometers are mounted on satellites and the ground to collect climatological data. While they provide very useful information about temperature, RH, and water vapor, radiometers should periodically be cross-referenced with other instruments to gauge the veracity of the data. Data available from the closest ground-based GPS receivers and sun photometers was plotted alongside, and used to analyze, data from City College's Microwave Radiometer. Observing all of the data together in a graph allows one to see some of the general advantages and disadvantages of each instrument. The GPS-MET seems to be accurate continuously, while AERONET data is not even available during the night and while there is cloud cover. Lastly, the microwave radiometer collects data continuously, but at certain times the data are about five times higher than the expected values, based on the values given by GPS-MET and AERONET. A good explanation for those spikes is rainfall. For times when it is not raining, the microwave radiometer at City College is sufficiently close to the integrated water vapor data collected by City College's sun photometer and data from Union, New Jersey and East Moriches, New York, as proven by statistical tools.

  5. Microwave radiometer studies of atmospheric water over the oceans, volume 1

    NASA Technical Reports Server (NTRS)

    Katsaros, Kristina B.

    1992-01-01

    Since Seasat carried the Scanning Multichannel Microwave Radiometer (SMMR) into space, shortly followed by the SMMR on Nimbus 7, a new type of data source on atmospheric water vapor and other meteorological parameters has been available for analysis of weather systems over the ocean. Since 1987, the Scanning Multichannel Microwave/Imager (SMM/I) has provided similar data. A collection of work using this data is presented.

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

    NASA Astrophysics Data System (ADS)

    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.

  7. Microwave radiometer studies of atmospheric water over the oceans, volume 2

    NASA Technical Reports Server (NTRS)

    Katsaros, Kristina B.

    1992-01-01

    Since the Seasat carried the Scanning Multichannel Microwave Radiometer (SMMR) into space in July of 1978, shortly followed by the SMMR on Nimbus 7, which operated for almost a decade, a new type of data source on atmospheric water vapor and other meteorological parameters has been available for analysis of weather systems over the ocean. Since 1987, we have had the Scanning Multichannel Microwave/Imager (SSM/I) instrument on Defense Meteorological Satellites providing similar data. We present a collection of our work performed over the last years of the study.

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

    NASA Astrophysics Data System (ADS)

    Huggins, Arlen W.

    1995-02-01

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

  9. Water vapour profiles from Raman lidar automatically calibrated by microwave radiometer data during HOPE

    NASA Astrophysics Data System (ADS)

    Foth, A.; Baars, H.; Di Girolamo, P.; Pospichal, B.

    2015-03-01

    In this paper, we present a method to derive water vapour profiles from Raman lidar measurements calibrated by the integrated water vapour (IWV) from a collocated microwave radiometer during the intense observation campaign HOPE in the frame of the HD(CP)2 initiative. The simultaneous observation of a microwave radiometer and a Raman lidar allowed an operational and continuous measurement of water vapour profiles also during cloudy conditions. The calibration method provides results in a good agreement with conventional methods based on radiosondes. The calibration factor derived from the proposed IWV method is very stable with a relative uncertainty of 6%. This stability allows to calibrate the lidar even in the presence of clouds using the calibration factor determined during the closest in time clear sky interval. Based on the application of this approach, it is possible to retrieve water vapour profiles during all non-precipitating conditions. A statistical analysis shows a good agreement between the lidar measurements and collocated radiosondes. The relative biases amount to less than 6.7% below 2 km.

  10. Water vapour profiles from Raman lidar automatically calibrated by microwave radiometer data during HOPE

    NASA Astrophysics Data System (ADS)

    Foth, A.; Baars, H.; Di Girolamo, P.; Pospichal, B.

    2015-07-01

    In this paper, we present a method to derive water vapour profiles from Raman lidar measurements calibrated by the integrated water vapour (IWV) from a collocated microwave radiometer during the intense observation campaign HOPE in the frame of the HD(CP)2 initiative. The simultaneous observation of a microwave radiometer and a Raman lidar allowed an operational and continuous measurement of water vapour profiles also during cloudy conditions. The calibration method provides results which are in a good agreement with conventional methods based on radiosondes. The calibration factor derived from the proposed IWV method is very stable with a relative uncertainty of 5 %. This stability allows for the calibration of the lidar even in the presence of clouds using the calibration factor determined during the most recent clear sky interval. Based on the application of this approach, it is possible to retrieve water vapour profiles during all non-precipitating conditions. A statistical analysis shows a good agreement between the lidar measurements and collocated radiosondes. The relative biases amount to less than 6.7 % below 2 km.

  11. Wideband Agile Digital Microwave Radiometer

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

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

    NASA Astrophysics Data System (ADS)

    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

  13. Observing atmospheric water in storms with the Nimbus 7 scanning multichannel microwave radiometer

    NASA Technical Reports Server (NTRS)

    Katsaros, K. B.; Lewis, R. M.

    1984-01-01

    Employing data on integrated atmospheric water vapor, total cloud liquid water and rain rate obtainable from the Nimbus 7 Scanning Multichannel Microwave Radiometer (SMMR), we study the frontal structure of several mid-latitude cyclones over the North Pacific Ocean as they approach the West Coast of North America in the winter of 1979. The fronts, analyzed with all available independent data, are consistently located at the leading edge of the strongest gradient in integrated water vapor. The cloud liquid water content, which unfortunately has received very little in situ verification, has patterns which are consistent with the structure seen in visible and infrared imagery. The rain distribution is also a good indicator of frontal location and rain amounts are generally within a factor of two of what is observed with rain gauges on the coast. Furthermore, the onset of rain on the coast can often be accurately forecast by simple advection of the SMMR observed rain areas.

  14. 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

    SciTech Connect

    Liljegren, J.C.; 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.

  15. Water vapour variability during Indian monsoon over Trivandrum observed using Microwave Radiometer and GPS

    NASA Astrophysics Data System (ADS)

    Raju, Suresh C.; Krishna Moorthy, K.; Ramachandran Pillai, Renju; Uma, K. N.; Saha, Korak

    2012-07-01

    The Indian summer monsoon is a highly regular synoptic event, providing most of the annual rainfall received over the sub-continent. Trivandrum, at the southwestern tip of Indian peninsula, is considered as the gate way of Indian monsoon, with its climatological onset on June 01. During this season, the region, experiences large seasonal variation in water vapor, rain fall and wind (speed and direction) in the troposphere. The variability in water vapor and wind information are the vital parameters in forecasting the onset of monsoon. This study focuses on water vapor measurements over the tropical coastal station Trivandrum (8.5oN & 76.9oE) using microwave techniques and the analyses with an effort to link the seasonal variability of water vapor with the onset of monsoon. At Trivandrum a hyper-spectral microwave radiometer profiler (MRP) and a Triple-frequency global positioning system receiver (GPS) have been in regular operation since April 2010. A station-dependent simple empirical relation suitable for the equatorial atmospheric condition is formulated to map the nonhydrostatic component of GPS tropospheric delay to the PWV, based on the columnar water vapor estimated from the multi-year daily radiosonde ascends from Trivandrum. A trained artificial neural network (ANN) with climatological atmospheric data of Trivandrum, is employed to derive the water vapor from the MRP brightness temperature measurements. The accuracy, reliability and consistency of PWV measurements over the tropical coastal station from these two independent instruments are assessed by comparing PWV derived from MRP and GPS measurements which resulted an rms deviation of <1.2mm (with correlation coefficient of ~0.98). This confirms the PWV derived over Trivandrum from microwave measurements are accurate even during the monsoon period in the presence of clouds and rain. PWV from microwave radiometer measurements for more than two years are used to study the water vapour variability during

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

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

    SciTech Connect

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

    1994-09-20

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

  18. A comparative study of microwave radiometer observations over snowfields with radiative transfer model calculations. [for water runoff estimation

    NASA Technical Reports Server (NTRS)

    Chang, A. T. C.; Shiue, J. C.

    1979-01-01

    Truck mounted microwave instrumentation was used to study the microwave emission characteristics of the Colorado Rocky Mountain snowpack in the vicinity of Fraser, Colorado during the winter of 1978. The spectral signatures of 5.0, 10.7, 18, and 37 GHz radiometers with dual polarization were used to measure the snowpack density and temperature profiles, rain profile, and free water content. These data were compared with calculated results based on microscopic scattering models for dry, surface melting, and very wet snowpacks.

  19. Comparisons of line-of-sight water vapor observations using the global positioning system and a pointing microwave radiometer.

    SciTech Connect

    Braun, J.; Rocken, C.; Liljegren, J. C.; Environmental Research; Univ. Corporation for Atmospheric Research

    2003-05-01

    Line-of-sight measurements of integrated water vapor from a global positioning system (GPS) receiver and a microwave radiometer are compared. These two instruments were collocated at the central facility of the Department of Energy's Atmospheric Radiation Measurement Program's Southern Great Plains region, near Lamont, Oklahoma. The comparison was made using 47 days of observations in May and June of 2000. Weather conditions during this time period were variable with total integrated water vapor ranging from less than 10 to more than 50 mm. To minimize errors in the microwave radiometer observations, observations were compared during conditions when the liquid water measured by the radiometer was less than 0.1 mm. The linear correlation of the observations between the two instruments is 0.99 with a root-mean-square difference of the GPS water vapor to a linear fit of the microwave radiometer of 1.3 mm. The results from these comparisons are used to evaluate the ability of networks of GPS receivers to measure instantaneous line-of-sight integrals of water vapor. A discussion and analysis is provided regarding the additional information of the water vapor field contained in these observations compared to time- and space-averaged zenith and gradient measurements.

  20. Salinity surveys using an airborne microwave radiometer

    NASA Technical Reports Server (NTRS)

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

    1972-01-01

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

  1. Inter- annual variability of water vapor over an equatorial coastal station using Microwave Radiometer observations.

    NASA Astrophysics Data System (ADS)

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

    The south-western region of the Indian peninsula is the gateway of Indian summer monsoon. This region experiences continuous monsoon rain for a longer period of about six months from June to November. The amount of water vapor variability is one of the important parameters to study the onset, active and break phases of the monsoon. Keeping this in view, a multi-frequency Microwave Radiometer Profiler (MRP) has been made operational for continuous measurements of water vapor over an equatorial coastal station Thiruvananthapuram (8.5(°) N, 76.9(°) E) since April 2010. The MRP estimated precipitable water vapor (PWV) for different seasons including monsoon periods have been evaluated by comparing with the collocated GPS derived water vapor and radiosonde measurements. The diurnal, seasonal and inter annual variation of water vapor has been studied for the last four years (2010-2013) over this station. The significant diurnal variability of water vapor is found only during the winter and pre-monsoon periods (Dec -April). The vertical distribution of water vapour is studied in order to understand its variability especially during the onset of monsoon. During the building up of south-west monsoon, the specific humidity increases to ˜ 10g/kg in the altitude range of 4-6 km and consistently maintained it throughout the active spells and reduces to below 2g/kg during break spells of monsoon. The instrument details and the results will be presented.

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

    SciTech Connect

    KL Gaustad; DD Turner

    2007-09-30

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

  3. Microwave radiometer observations of interannual water vapor variability and vertical structure over a tropical station

    NASA Astrophysics Data System (ADS)

    Renju, R.; Suresh Raju, C.; Mathew, Nizy; Antony, Tinu; Krishna Moorthy, K.

    2015-05-01

    The intraseasonal and interannual characteristics and the vertical distribution of atmospheric water vapor from the tropical coastal station Thiruvananthapuram (TVM) located in the southwestern region of the Indian Peninsula are examined from continuous multiyear, multifrequency microwave radiometer profiler (MRP) measurements. The accuracy of MRP for precipitable water vapor (PWV) estimation, particularly during a prolonged monsoon period, has been demonstrated by comparing with the PWV derived from collocated GPS measurements based on regression model between PWV and GPS wet delay component which has been developed for TVM station. Large diurnal and intraseasonal variations of PWV are observed during winter and premonsoon seasons. There is large interannual PWV variability during premonsoon, owing to frequent local convection and summer thunderstorms. During monsoon period, low interannual PWV variability is attributed to the persistent wind from the ocean which brings moisture to this coastal station. However, significant interannual humidity variability is seen at 2 to 6 km altitude, which is linked to the monsoon strength over the station. Prior to monsoon onset over the station, the specific humidity increases up to 5-10 g/kg in the altitude region above 5 km and remains consistently so throughout the active spells.

  4. Understanding Microwave Radiometers

    NASA Technical Reports Server (NTRS)

    Stacey, J. M.

    1986-01-01

    Report presents principles of microwave receivers for observing planetary surfaces from space. Report is tutorial and explains operation of receivers in detail to enable reader to specify and qualify them for spaceborne operation. Gives many examples to illustrate practical design procedures.

  5. Biases in Total Precipitable Water Vapor Climatologies from Atmospheric Infrared Sounder and Advanced Microwave Scanning Radiometer

    NASA Technical Reports Server (NTRS)

    Fetzer, Eric J.; Lambrigtsen, Bjorn H.; Eldering, Annmarie; Aumann, Hartmut H.; Chahine, Moustafa T.

    2006-01-01

    We examine differences in total precipitable water vapor (PWV) from the Atmospheric Infrared Sounder (AIRS) and the Advanced Microwave Scanning Radiometer (AMSR-E) experiments sharing the Aqua spacecraft platform. Both systems provide estimates of PWV over water surfaces. We compare AIRS and AMSR-E PWV to constrain AIRS retrieval uncertainties as functions of AIRS retrieved infrared cloud fraction. PWV differences between the two instruments vary only weakly with infrared cloud fraction up to about 70%. Maps of AIRS-AMSR-E PWV differences vary with location and season. Observational biases, when both instruments observe identical scenes, are generally less than 5%. Exceptions are in cold air outbreaks where AIRS is biased moist by 10-20% or 10-60% (depending on retrieval processing) and at high latitudes in winter where AIRS is dry by 5-10%. Sampling biases, from different sampling characteristics of AIRS and AMSR-E, vary in sign and magnitude. AIRS sampling is dry by up to 30% in most high-latitude regions but moist by 5-15% in subtropical stratus cloud belts. Over the northwest Pacific, AIRS samples conditions more moist than AMSR-E by a much as 60%. We hypothesize that both wet and dry sampling biases are due to the effects of clouds on the AIRS retrieval methodology. The sign and magnitude of these biases depend upon the types of cloud present and on the relationship between clouds and PWV. These results for PWV imply that climatologies of height-resolved water vapor from AIRS must take into consideration local meteorological processes affecting AIRS sampling.

  6. Forward Model Studies of Water Vapor Using Scanning Microwave Radiometers, Global Positioning System, and Radiosondes during the Cloudiness Intercomparison Experiment

    SciTech Connect

    Mattioli, Vinia; Westwater, Ed R.; Gutman, S.; Morris, Victor R.

    2005-05-01

    Brightness temperatures computed from five absorption models and radiosonde observations were analyzed by comparing them with measurements from three microwave radiometers at 23.8 and 31.4 GHz. Data were obtained during the Cloudiness Inter-Comparison experiment at the U.S. Department of Energy's Atmospheric Radiation Measurement Program's (ARM) site in North-Central Oklahoma in 2003. The radiometers were calibrated using two procedures, the so-called instantaneous ?tipcal? method and an automatic self-calibration algorithm. Measurements from the radiometers were in agreement, with less than a 0.4-K difference during clear skies, when the instantaneous method was applied. Brightness temperatures from the radiometer and the radiosonde showed an agreement of less than 0.55 K when the most recent absorption models were considered. Precipitable water vapor (PWV) computed from the radiometers were also compared to the PWV derived from a Global Positioning System station that operates at the ARM site. The instruments agree to within 0.1 cm in PWV retrieval.

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

    NASA Astrophysics Data System (ADS)

    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 (<10K) from the LWC, the noise coupling technique is used. Through injecting constant equal noise signal into the two 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.

  8. Atmospheric absorption model for dry air and water vapor at microwave frequencies below 100 GHz derived from spaceborne radiometer observations

    NASA Astrophysics Data System (ADS)

    Wentz, Frank J.; Meissner, Thomas

    2016-05-01

    The Liebe and Rosenkranz atmospheric absorption models for dry air and water vapor below 100 GHz are refined based on an analysis of antenna temperature (TA) measurements taken by the Global Precipitation Measurement Microwave Imager (GMI) in the frequency range 10.7 to 89.0 GHz. The GMI TA measurements are compared to the TA predicted by a radiative transfer model (RTM), which incorporates both the atmospheric absorption model and a model for the emission and reflection from a rough-ocean surface. The inputs for the RTM are the geophysical retrievals of wind speed, columnar water vapor, and columnar cloud liquid water obtained from the satellite radiometer WindSat. The Liebe and Rosenkranz absorption models are adjusted to achieve consistency with the RTM. The vapor continuum is decreased by 3% to 10%, depending on vapor. To accomplish this, the foreign-broadening part is increased by 10%, and the self-broadening part is decreased by about 40% at the higher frequencies. In addition, the strength of the water vapor line is increased by 1%, and the shape of the line at low frequencies is modified. The dry air absorption is increased, with the increase being a maximum of 20% at the 89 GHz, the highest frequency considered here. The nonresonant oxygen absorption is increased by about 6%. In addition to the RTM comparisons, our results are supported by a comparison between columnar water vapor retrievals from 12 satellite microwave radiometers and GPS-retrieved water vapor values.

  9. Design of a geostationary microwave precipitation radiometer

    NASA Astrophysics Data System (ADS)

    Wilson, William J.; Eldred, Daniel B.

    1993-11-01

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

  10. Advanced Microwave Radiometer (AMR) for SWOT mission

    NASA Astrophysics Data System (ADS)

    Chae, C. S.

    2015-12-01

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

  11. Increasing vertical resolution of three-dimensional atmospheric water vapor retrievals using a network of scanning compact microwave radiometers

    NASA Astrophysics Data System (ADS)

    Sahoo, Swaroop

    2011-12-01

    The thermodynamic properties of the troposphere, in particular water vapor content and temperature, change in response to physical mechanisms, including frictional drag, evaporation, transpiration, heat transfer and flow modification due to terrain. The planetary boundary layer (PBL) is characterized by a high rate of change in its thermodynamic state on time scales of typically less than one hour. Large horizontal gradients in vertical wind speed and steep vertical gradients in water vapor and temperature in the PBL are associated with high-impact weather. Observation of these gradients in the PBL with high vertical resolution and accuracy is important for improvement of weather prediction. Satellite remote sensing in the visible, infrared and microwave provide qualitative and quantitative measurements of many atmospheric properties, including cloud cover, precipitation, liquid water content and precipitable water vapor in the upper troposphere. However, the ability to characterize the thermodynamic properties of the PBL is limited by the confounding factors of ground emission in microwave channels and of cloud cover in visible and IR channels. Ground-based microwave radiometers are routinely used to measure thermodynamic profiles. The vertical resolution of such profiles retrieved from radiometric brightness temperatures depends on the number and choice of frequency channels, the scanning strategy and the accuracy of brightness temperature measurements. In the standard technique, which uses brightness temperatures from vertically pointing radiometers, the vertical resolution of the retrieved water vapor profile is similar to or larger than the altitude at which retrievals are performed. This study focuses on the improvement of the vertical resolution of water vapor retrievals by including scanning measurements at a variety of elevation angles. Elevation angle scanning increases the path length of the atmospheric emission, thus improving the signal-to-noise ratio

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

    SciTech Connect

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

    2001-01-01

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

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

    NASA Technical Reports Server (NTRS)

    King, J. L.

    1980-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Stanley, W. D.

    1980-01-01

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

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

    SciTech Connect

    Gaustad, KL; Turner, DD; McFarlane, SA

    2011-07-25

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

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

    SciTech Connect

    Gaustad, KL; Turner, DD

    2009-05-30

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

  17. Microwave Radiometer – 3 Channel (MWR3C) Handbook

    SciTech Connect

    Cadeddu, MP

    2012-05-04

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

  18. Accounting For Nonlinearity In A Microwave Radiometer

    NASA Technical Reports Server (NTRS)

    Stelzried, Charles T.

    1991-01-01

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

  19. The microwave radiometer spacecraft: A design study

    NASA Technical Reports Server (NTRS)

    Wright, R. L. (Editor)

    1981-01-01

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

  20. Microwave Radiometer-High Frequency (MWRHF) Handbook

    SciTech Connect

    Caddedu, MP

    2011-03-17

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

  1. Submarine fresh water outflow detection with a dual-frequency microwave and an infrared radiometer system

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    Since infrared measurements are only very slightly affected by whitecap and banking angle influences, the combined multifrequency radiometric signatures of the L-band, the S-band, and an infrared radiometer are used in identifying freshwater outflows (submerged and superficial). To separate the river and lagoon outflows from the submarine outflows, geographical maps with a scale of 1:100,000 are used. In all, 44 submarine freshwater springs are identified. This is seen as indicating that the submarine freshwater outflow locations are more numerous around the island than had earlier been estimated. Most of the submarine springs are located at the northwest and southeast portion of the Puerto Rican coastline; the success in detecting the submarine springs during both missions at the northwest portion of the island is 39%. Salinity and temperature distribution plots along the flight path in longitude and latitude coordinates reveal that runoff direction can be determined.

  2. Multifrequency microwave radiometer measurements of soil moisture

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

  3. Null-balancing microwave radiometer

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

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

  4. Validation of GPS derived integrated water vapor with microwave radiometer measurements in zenith and satellite tracking mode

    NASA Astrophysics Data System (ADS)

    Heise, Stefan; Shangguan, Ming; Deng, Zhiguo; Dick, Galina; Wickert, Jens; Zus, Florian

    2015-04-01

    Reliable and precise water vapour measurements are important for both, numerical weather prediction and climatological studies. In this context, zenith and slant total delay (ZTD, STD) data from Global Positioning System (GPS) ground observations provide a valuable source of integrated water vapour (IWV) information with high potential for assimilation to numerical weather models and nowcasting applications but also for climatological analysis of longer GPS IWV time series. Therefore it is important to validate the accuracy of GPS IWV with independent observations. For this purpose, in 2012 GFZ started to operate a water vapour radiometer (WVR) in vicinity of the Potsdam GPS station. It measures the absorption lines of atmospheric water vapour and oxygen at 14 frequency channels in the 22-58 GHz range and provides among others integrated water vapour measurements along the respective line of sight. Besides zenith IWV measurements the radiometer is operated in GPS satellite tracking mode enabling direct comparisons with the nearby GPS slant IWV observations (processed at GFZ). In this study we present validation results of GPS slant and zenith IWV data with the collocated radiometer observations. The validation covers all seasons including dry and wet humidity conditions. We address relations between the GPS-WVR differences and corresponding observation conditions that might have influence on the comparison results (elevation angles, ground pressure and temperature, atmospheric humidity).

  5. Retrieval techniques and information content analysis to improve remote sensing of atmospheric water vapor, liquid water and temperature from ground-based microwave radiometer measurements

    NASA Astrophysics Data System (ADS)

    Sahoo, Swaroop

    Observation of profiles of temperature, humidity and winds with sufficient accuracy and fine vertical and temporal resolution are needed to improve mesoscale weather prediction, track conditions in the lower to mid-troposphere, predict winds for renewable energy, inform the public of severe weather and improve transportation safety. In comparing these thermodynamic variables, the absolute atmospheric temperature varies only by 15%; in contrast, total water vapor may change by up to 50% over several hours. In addition, numerical weather prediction (NWP) models are initialized using water vapor profile information, so improvements in their accuracy and resolution tend to improve the accuracy of NWP. Current water vapor profile observation systems are expensive and have insufficient spatial coverage to observe humidity in the lower to mid-troposphere. To address this important scientific need, the principal objective of this dissertation is to improve the accuracy, vertical resolution and revisit time of tropospheric water vapor profiles retrieved from microwave and millimeter-wave brightness temperature measurements. This dissertation advances the state of knowledge of retrieval of atmospheric water vapor from microwave brightness temperature measurements. It focuses on optimizing two information sources of interest for water vapor profile retrieval, i.e. independent measurements and background data set size. From a theoretical perspective, it determines sets of frequencies in the ranges of 20-23, 85-90 and 165-200 GHz that are optimal for water vapor retrieval from each of ground-based and airborne radiometers. The maximum number of degrees of freedom for the selected frequencies for ground-based radiometers is 5-6, while the optimum vertical resolution is 0.5 to 1.5 km. On the other hand, the maximum number of degrees of freedom for airborne radiometers is 8-9, while the optimum vertical resolution is 0.2 to 0.5 km. From an experimental perspective, brightness

  6. High-Precision Laboratory Measurements Supporting Retrieval of Water Vapor, Gaseous Ammonia, and Aqueous Ammonia Clouds with the Juno Microwave Radiometer (MWR)

    NASA Astrophysics Data System (ADS)

    Steffes, Paul G.; Hanley, Thomas R.; Karpowicz, Bryan M.; Devaraj, Kiruthika; Noorizadeh, Sahand; Duong, Danny; Chinsomboon, Garrett; Bellotti, Amadeo; Janssen, Michael A.; Bolton, Scott J.

    2016-08-01

    The NASA Juno mission includes a six-channel microwave radiometer system (MWR) operating in the 1.3-50 cm wavelength range in order to retrieve abundances of ammonia and water vapor from the microwave signature of Jupiter (see Janssen et al. 2016). In order to plan observations and accurately interpret data from such observations, over 6000 laboratory measurements of the microwave absorption properties of gaseous ammonia, water vapor, and aqueous ammonia solution have been conducted under simulated Jovian conditions using new laboratory systems capable of high-precision measurement under the extreme conditions of the deep atmosphere of Jupiter (up to 100 bars pressure and 505 K temperature). This is one of the most extensive laboratory measurement campaigns ever conducted in support of a microwave remote sensing instrument. New, more precise models for the microwave absorption from these constituents have and are being developed from these measurements. Application of these absorption properties to radiative transfer models for the six wavelengths involved will provide a valuable planning tool for observations, and will also make possible accurate retrievals of the abundance of these constituents during and after observations are conducted.

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

    NASA Astrophysics Data System (ADS)

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

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

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  9. Preliminary development of digital signal processing in microwave radiometers

    NASA Technical Reports Server (NTRS)

    Stanley, W. D.

    1980-01-01

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

  10. COBE differential microwave radiometers - Calibration techniques

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  11. Sensor Calibration and Ocean Products for TRMM Microwave Radiometer

    NASA Technical Reports Server (NTRS)

    Wentz, Frank J.; Lawrence, Richard J. (Technical Monitor)

    2003-01-01

    During the three years of finding, we have carefully corrected for two sensor/platform problems, developed a physically based retrieval algorithm to calculate SST, wind speed, water vapor, cloud liquid water and rain rates, validated these variables, and demonstrated that satellite microwave radiometers can provide very accurate SST retrievals through clouds. Prior to this, there was doubt by some scientists that the technique of microwave SST retrieval from satellites is a viable option. We think we have put these concerns to rest, and look forward to making microwave SSTs a standard component of the Earth science data sets. Our TMI SSTs were featured on several network news broadcasts and were reported in Science magazine. Additionally, we have developed a SST algorithm for VIRS to facilitate IR/MW inter-comparisons and completed research into diurnal cycles and air-sea interactions.

  12. Sensor Calibration and Ocean Products for TRMM Microwave Radiometer

    NASA Technical Reports Server (NTRS)

    Lawrence, Richard J. (Technical Monitor); Wentz, Frank J.

    2003-01-01

    During the three years of fundin& we have carefully corrected for two sensor/platform problems, developed a physically based retrieval algorithm to calculate SST, wind speed, water vapor, cloud liquid water and rain rates, validated these variables, and demonstrated that satellite microwave radiometers can provide very accurate SST retrievals through clouds. Prior to this, there was doubt by some scientists that the technique of microwave SST retrieval from satellites is a viable option. We think we have put these concerns to rest, and look forward to making microwave SSTs a standard component of the Earth science data sets. Our TMI SSTs were featured on several network news broadcasts and were reported in Science magazine. Additionally, we have developed a SST algorithm for VIRS to facilitate IR/MW inter-comparisons and completed research into diurnal cycles and air-sea interactions.

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

    NASA Astrophysics Data System (ADS)

    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

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

    NASA Technical Reports Server (NTRS)

    Reehorst, Andrew L.

    2001-01-01

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

  15. Application of microwave radiometers for wetlands and estuaries monitoring

    SciTech Connect

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

    1997-06-01

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

  16. Stratus cloud liquid water and turbulence profiles using a K{sub {alpha}}-band Doppler radar and a microwave radiometer

    SciTech Connect

    Frisch, A.S.; Fairall, C.W.; Snider, J.B.; Lenschow, D.H.

    1994-12-31

    The goal of the Atlantic Stratocumulus Transition Experiment (ASTEX) held in the North Atlantic during June 1992 was to determine the physical reasons for the transition from stratocumulus to broken clouds. Some possible reasons for this transition were such things as cloud top entrainment instability, and the decoupling effects of drizzle. As part of this experiment, the ETL cloud sensing Doppler radar and three channel microwave radiometer were deployed on the island of Porto Santo in the Madeira Islands of Portugal along with a CO{sub 2} Doppler lider. Drizzle properties in stratus were examined using a log-normal droplet distribution model which related the three parameters of the model to the first 3 Doppler spectral moments of the cloud radar. With these moments, the authors are then able to compute the drizzle droplet concentration, modal radius, liquid water and liquid water flux as a function of height.

  17. Multichannel infrared fiber optic radiometer for controlled microwave heating

    NASA Astrophysics Data System (ADS)

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

    1990-07-01

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

  18. Progress report of FY 1999 activities: The application of Kalman filtering to derive water vapor profiles from combined ground-based sensors: Raman lidar, microwave radiometers, GPS, and radiosondes

    SciTech Connect

    Edgeworth R. Westwater; Yong Han

    1999-09-10

    Previously, the proposers have delivered to ARM a documented algorithm, that is now applied operationally, and which derives water vapor profiles from combined remote sensor measurements of water vapor radiometers, cloud-base ceilometers, and radio acoustic sounding systems (RASS). With the expanded deployment of a Raman lidar at the CART Central Facility, high quality, high vertical-resolution, water vapor profiles will be provided during nighttime clear conditions, and during clear daytime conditions, to somewhat lower altitudes. The object of this effort is to use Kalman Filtering, previously applied to the combination of nighttime Raman lidar and microwave radiometer data, to derive high-quality water vapor profiles, during non-precipitating conditions, from data routinely available at the CART site. Input data to the algorithm would include: Raman lidar data, highly quality-controlled data of integrated moisture from microwave radiometers and GPS, RASS, and radiosondes. While analyzing data obtained during the Water Vapor Intensive Operating Period'97 at the SGP CART site in central Oklahoma, several questions arose about the calibration of the ARM microwave radiometers (MWR). A large portion of this years effort was a thorough analysis of the many factors that are important for the calibration of this instrument through the tip calibration method and the development of algorithms to correct this procedure. An open literature publication describing this analysis has been accepted.

  19. Sensitivity of Spacebased Microwave Radiometer Observations to Ocean Surface Evaporation

    NASA Technical Reports Server (NTRS)

    Liu, Timothy W.; Li, Li

    2000-01-01

    Ocean surface evaporation and the latent heat it carries are the major components of the hydrologic and thermal forcing on the global oceans. However, there is practically no direct in situ measurements. Evaporation estimated from bulk parameterization methods depends on the quality and distribution of volunteer-ship reports which are far less than satisfactory. The only way to monitor evaporation with sufficient temporal and spatial resolutions to study global environment changes is by spaceborne sensors. The estimation of seasonal-to-interannual variation of ocean evaporation, using spacebased measurements of wind speed, sea surface temperature (SST), and integrated water vapor, through bulk parameterization method,s was achieved with reasonable success over most of the global ocean, in the past decade. Because all the three geophysical parameters can be retrieved from the radiance at the frequencies measured by the Scanning Multichannel Microwave Radiometer (SMMR) on Nimbus-7, the feasibility of retrieving evaporation directly from the measured radiance was suggested and demonstrated using coincident brightness temperatures observed by SMMR and latent heat flux computed from ship data, in the monthly time scale. However, the operational microwave radiometers that followed SMMR, the Special Sensor Microwave/Imager (SSM/I), lack the low frequency channels which are sensitive to SST. This low frequency channels are again included in the microwave imager (TMI) of the recently launched Tropical Rain Measuring Mission (TRMM). The radiance at the frequencies observed by both TMI and SSM/I were simulated through an atmospheric radiative transfer model using ocean surface parameters and atmospheric temperature and humidity profiles produced by the reanalysis of the European Center for Medium Range Weather Forecast (ECMWF). From the same ECMWF data set, coincident evaporation is computed using a surface layer turbulent transfer model. The sensitivity of the radiance to

  20. Variability of winter-time middle atmospheric water vapour over the Arctic as observed with a ground-based microwave radiometer

    NASA Astrophysics Data System (ADS)

    Tschanz, Brigitte; Kivi, Rigel; Rüfenacht, Rolf; Kämpfer, Niklaus

    2014-05-01

    Middle atmospheric water vapour has a long chemical lifetime and can therefore be used as a tracer for dynamics. The ground-based microwave radiometer MIAWARA-C is designed for the use on campaigns and measures profiles of water vapour in the upper stratosphere and mesosphere and thus provides valuable data for the investigation of atmospheric processes. It has been operational for five years and has successfully participated in measurement campaigns under various climatic conditions in Germany, Switzerland, California, Finland and on la Réunion. The temporal resolution of the obtained water vapour profiles approximately 2 hours depending on tropospheric conditions. During two campaigns from January to June 2010 and from July 2011 to April 2013 in Sodankylä, Finland, MIAWARA-C monitored time series of polar middle atmospheric water vapour for three winters with three Sudden Stratospheric Warmings (SSW) occurring in early 2010, 2012 and 2013. The obtained time series are used to study the effects of the three SSWs on middle-atmospheric water vapour. During an SSW, humid mid- to low-latitude air is transported towards the polar region resulting in a fast increase in water vapour. The descent of water vapour after the SSW allows the estimation of the descent rate over the polar region as the normal wintertime circulation reforms. Results from the three SSWs are compared. The ground-based water vapour data is combined with sonde data of the Finnish Meteorological Institute and ground-based microwave wind measurements for one winter in order to obtain a more complete picture of the dynamics in the polar winter atmosphere.

  1. A Microwave Radiometer for Internal Body Temperature Measurement

    NASA Astrophysics Data System (ADS)

    Scheeler, Robert Patterson

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

  2. Supercooled liquid water content profiling case studies with a new vibrating wire sonde compared to a ground-based microwave radiometer

    NASA Astrophysics Data System (ADS)

    Serke, David; Hall, Emrys; Bognar, John; Jordan, Allen; Abdo, Spencer; Baker, Kirstin; Seitel, Tom; Nelson, Marta; Ware, Randolph; McDonough, Frank; Politovich, Marcia

    2014-11-01

    An improved version of the vibrating wire sensor, used to measure supercooled cloud liquid water content, was developed by Anasphere Inc. and tested during early 2012. The sensor works on the principle that supercooled liquid will freeze to the vibrating wire and reduce the frequency at a known rate proportional to the liquid water content as the sensor rises through the cloud attached to a weather balloon and radiosonde. The disposable Anasphere sensor interfaces with an InterMet Systems iMet radiosonde. This updated sensor reduces the weight of the instrument while updating the technology when compared to the preceding balloon-borne sensor that was developed in the 1980's by Hill and Woffinden. Balloon-borne test flights were performed from Boulder, Colorado during February and March of 2012. These flights provided comparisons to integrated liquid water and profiles of liquid water content derived from a collocated multichannel microwave radiometer, built and operated by Radiometrics Corporation. Inter-comparison data such as these are invaluable for calibration, verification and validation of remote-sensing instruments. The data gathered from this sensor are potentially important to detection of icing hazards to aircraft, validation of microphysical output from numerical models, and calibrating remote sensors measuring supercooled liquid water.

  3. Remote monitoring of soil moisture using airborne microwave radiometers

    NASA Technical Reports Server (NTRS)

    Kroll, C. L.

    1973-01-01

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

  4. Middle atmospheric water vapour measurements obtained at the Maido observatory on la Réunion with a ground-based microwave radiometer

    NASA Astrophysics Data System (ADS)

    Tschanz, Brigitte; Duflot, Valentin; Kämpfer, Niklaus

    2014-05-01

    The ground-based microwave radiometer MIAWARA-C measures middle atmospheric water vapour profiles and is especially designed for the use on campaigns. The instrument is of a compact design, has a simple set up procedure and can be operated remotely. It has been operational for five years and has successfully participated in measurement campaigns under various climatic conditions in Germany, Switzerland, California, Finland and has started to measure on la Réunion (21S, 56E) in September 2013. Under most tropospheric conditions, the instrument can obtain water vapour profiles with a temporal resolution of approximately 2 hours. MIAWARA-C is a reliable instrument and has been validated against similar instruments and satellite experiments. The data sets obtained with MIAWARA-C offer the possibility of comparison with other ground-based instruments and with satellites as well as case studies of atmospheric dynamics. In the southern hemisphere and particularly in the tropical region ground-based measurements of the middle atmosphere are scarce. In MIAWARA-C's water vapour data set a strong seasonal cycle in the stratosphere and signatures of the Semi-Annual Oscillation in the mesosphere are expected. Additionally, the high temporal resolution of the measured data set allows the investigation of short period signals such as diurnal variations. First results after four months of measurements are presented including signatures of the Semi-Annual Oscillation and a first transition to summer condition. In addition, short-term variations observed by MIAWARA-C are analysed.

  5. Precipitation from the GPM Microwave Imager and Constellation Radiometers

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  6. Progress report of FY 1997 activities: The application of Kalman filtering to derive water vapor profiles from combined ground-based sensors: Raman lidar, microwave radiometers, GPS, and radiosondes

    SciTech Connect

    Edgeworth R. Westwater; Yong Han

    1997-10-05

    Previously, the proposers have delivered to ARM a documented algorithm, that is now applied operationally, and which derives water vapor profiles from combined remote sensor measurements of water vapor radiometers, cloud-base ceilometers, and radio acoustic sounding systems (RASS). With the expanded deployment of a Raman lidar at the CART Central Facility, high quality, high vertical-resolution, water vapor profiles will be provided during nighttime clear conditions, and during clear daytime conditions, to somewhat lower altitudes. The object of this proposal was to use Kalman Filtering, previously applied to the combination of nighttime Raman lidar and microwave radiometer data, to derive high-quality water vapor profiles, during non-precipitating conditions, from data routinely available at the CART site. Input data to the algorithm would include: Raman lidar data, highly quality-controlled data of integrated moisture from microwave radiometers and GPS, RASS, and radiosondes. The algorithm will include recently-developed quality control procedures for radiometers. The focus of this years activities has been on the intercomparison of data obtained during an intensive operating period at the SGP CART site in central Oklahoma.

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

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  8. Microwave radiometer for subsurface temperature measurement

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

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

  9. Progress report of FY 1998 activities: The application of Kalman filtering to derive water vapor profiles from combined ground-based sensors: Raman lidar, microwave radiometers, GPS, and radiosondes

    SciTech Connect

    Edgeworth R. Westwater; Yong Han

    1999-10-01

    Previously, the proposers have delivered to ARM a documented algorithm, that is now applied operationally, and which derives water vapor profiles from combined remote sensor measurements of water vapor radiometers, cloud-base ceilometers, and radio acoustic sounding systems (RASS). With the expanded deployment of a Raman lidar at the CART Central Facility, high quality, high vertical-resolution, water vapor profiles will be provided during nighttime clear conditions, and during clear daytime conditions, to somewhat lower altitudes. The object of this effort is to use Kalman Filtering, previously applied to the combination of nighttime Raman lidar and microwave radiometer data, to derive high-quality water vapor profiles, during non-precipitating conditions, from data routinely available at the CART site. Input data to the algorithm would include: Raman lidar data, highly quality-controlled data of integrated moisture from microwave radiometers and GPS, RASS, and radiosondes. The focus of this years activities has been on the intercomparison of data obtained during the Water Vapor Intensive Operating Period'97 at the SGP CART site in central Oklahoma.

  10. Source analysis of spaceborne microwave radiometer interference over land

    NASA Astrophysics Data System (ADS)

    Guan, Li; Zhang, Sibo

    2016-03-01

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

  11. Multiscale assimilation of Advanced Microwave Scanning Radiometer-EOS snow water equivalent and Moderate Resolution Imaging Spectroradiometer snow cover fraction observations in northern Colorado

    NASA Astrophysics Data System (ADS)

    de Lannoy, GabriëLle J. M.; Reichle, Rolf H.; Arsenault, Kristi R.; Houser, Paul R.; Kumar, Sujay; Verhoest, Niko E. C.; Pauwels, Valentijn R. N.

    2012-01-01

    Eight years (2002-2010) of Advanced Microwave Scanning Radiometer-EOS (AMSR-E) snow water equivalent (SWE) retrievals and Moderate Resolution Imaging Spectroradiometer (MODIS) snow cover fraction (SCF) observations are assimilated separately or jointly into the Noah land surface model over a domain in Northern Colorado. A multiscale ensemble Kalman filter (EnKF) is used, supplemented with a rule-based update. The satellite data are either left unscaled or are scaled for anomaly assimilation. The results are validated against in situ observations at 14 high-elevation Snowpack Telemetry (SNOTEL) sites with typically deep snow and at 4 lower-elevation Cooperative Observer Program (COOP) sites. Assimilation of coarse-scale AMSR-E SWE and fine-scale MODIS SCF observations both result in realistic spatial SWE patterns. At COOP sites with shallow snowpacks, AMSR-E SWE and MODIS SCF data assimilation are beneficial separately, and joint SWE and SCF assimilation yields significantly improved root-mean-square error and correlation values for scaled and unscaled data assimilation. In areas of deep snow where the SNOTEL sites are located, however, AMSR-E retrievals are typically biased low and assimilation without prior scaling leads to degraded SWE estimates. Anomaly SWE assimilation could not improve the interannual SWE variations in the assimilation results because the AMSR-E retrievals lack realistic interannual variability in deep snowpacks. SCF assimilation has only a marginal impact at the SNOTEL locations because these sites experience extended periods of near-complete snow cover. Across all sites, SCF assimilation improves the timing of the onset of the snow season but without a net improvement of SWE amounts.

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

    NASA Technical Reports Server (NTRS)

    Harrington, Richard F.

    1993-01-01

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

  13. Satellite microwave observations of soil moisture variations. [by the microwave radiometer on the Nimbus 5 satellite

    NASA Technical Reports Server (NTRS)

    Schmugge, T. J.; Rango, A.; Neff, R.

    1975-01-01

    The electrically scanning microwave radiometer (ESMR) on the Nimbus 5 satellite was used to observe microwave emissions from vegetated and soil surfaces over an Illinois-Indiana study area, the Mississippi Valley, and the Great Salt Lake Desert in Utah. Analysis of microwave brightness temperatures (T sub B) and antecedent rainfall over these areas provided a way to monitor variations of near-surface soil moisture. Because vegetation absorbs microwave emission from the soil at the 1.55 cm wavelength of ESMR, relative soil moisture measurements can only be obtained over bare or sparsely vegetated soil. In general T sub B increased during rainfree periods as evaporation of water and drying of the surface soil occurs, and drops in T sub B are experienced after significant rainfall events wet the soil. Microwave observations from space are limited to coarse resolutions (10-25 km), but it may be possible in regions with sparse vegetation cover to estimate soil moisture conditions on a watershed or agricultural district basis, particularly since daily observations can be obtained.

  14. Remote sensing of soil moisture with microwave radiometers

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

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

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

    NASA Astrophysics Data System (ADS)

    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

  16. Progress in Low-Power Digital Microwave Radiometer Technologies

    NASA Technical Reports Server (NTRS)

    Piepmeier, Jeffrey R.; Kim, Edward J.

    2004-01-01

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

  17. Inflatable Antenna Microwave Radiometer for Soil Moisture Measurement

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

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

  19. Electromagnetic design of a microwave radiometer antenna system

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

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

  20. Scanning mechanism study for multi-frequency microwave radiometers

    NASA Technical Reports Server (NTRS)

    Shin, I.

    1976-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

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

    NASA Technical Reports Server (NTRS)

    1970-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Smoot, George F.

    1992-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Mix, R. F.

    1974-01-01

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

  5. Design and Development of the SMAP Microwave Radiometer Electronics

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Reising, S. C.; Kangaslahti, P.; Brown, S. T.; Tanner, A. B.; Padmanabhan, S.; Parashare, C.; Bosch-Lluis, X.; Nelson, S. P.; Johnson, T. P.; Hadel, V. D.; Dawson, D. E.; Montes, O.; Gaier, T. C.; Khayatian, B.; Gilliam, K. L.; Razavi, B.

    2012-12-01

    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. In fact, Jason-1 and Jason-2 retrievals are flagged as contaminated within 50 km and 25 km of the coasts, respectively. In addition, they do not provide wet path delay estimates over land. A viable approach to meet these needs is the addition of wide-band millimeter-wave window channels at 90-170 GHz with internal calibration, yielding finer spatial resolution for a given antenna size. 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 principal objective of this research is to assess the ability of higher-frequency radiometers to meet the needs of the Surface Water and Ocean Topography (SWOT) mission recommended by the U.S. National Research Council's Earth Science Decadal Survey, accelerated in 2010 and planned for launch in 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, including rivers, lakes, reservoirs, and wetlands. Therefore, an important new science objective of SWOT is to transition satellite radar altimetry into the coastal zone, indicating the need for a novel microwave radiometer to provide fine-scale spatial resolution wet-tropospheric path delay corrections near land. In addition, the Ka-band SWOT radar interferometer will for the first time broaden the altimeter field of view and improve spatial resolution to make coastal and inland surface water measurements, so the variability of atmospheric water vapor

  7. 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

    NASA Astrophysics Data System (ADS)

    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.

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

    SciTech Connect

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

    2009-01-26

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

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

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

  11. Limits of Precipitation Detection from Microwave Radiometers and Sounders

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

  12. The utilization of spaceborne microwave radiometers for monitoring snowpack properties. [United States and Canada

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

    Snow accumulation and depletion at specific locations can be monitored from space by observing related variations in microwave brightness temperatures. Using vertically and horizontally polarized brightness temperatures from the Nimbus 6 electrically scanning microwave radiometer, a discriminant function can be used to separate snow from no snow areas and map snowcovered area on a continental basis. For dry snow conditions on the Canadian high plains, significant relationships between snow depth or water equivalent and microwave brightness temperature were developed which could permit remote determination of these snow properties after acquisition of a wider range of data. The presence of melt water in the snowpack causes a marked increase in brightness temperature which can be used to predict snowpack priming and timing of runoff. As the resolutions of satellite microwave sensors improve the application of these results to snow hydrology problems should increase.

  13. An SSM/I radiometer simulator for studies of microwave emission from soil. [Special Sensor Microwave/Imager

    NASA Technical Reports Server (NTRS)

    Galantowicz, J. F.; England, A. W.

    1992-01-01

    A ground-based simulator of the defense meterological satellite program special sensor microwave/imager (DMSP SSM/I) is described, and its integration with micrometeorological instrumentation for an investigation of microwave emission from moist and frozen soils is discussed. The simulator consists of three single polarization radiometers which are capable of both Dicke radiometer and total power radiometer modes of operation. The radiometers are designed for untended operation through a local computer and a daily telephone link to a laboratory. The functional characteristics of the radiometers are described, together with their field deployment configuration and an example of performance parameters.

  14. Microwave vegetation indices derived from satellite microwave radiometers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Vegetation indices are valuable in many fields of geosciences. Conventional, visible-near infrared, indices are often limited by the effects of atmosphere, background soil conditions, and saturation at high levels of vegetation. In this study, the theoretical basis for a new type of passive microwav...

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

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  16. COBE Differential Microwave Radiometers - Instrument design and implementation

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  17. Mission definition for a large-aperture microwave radiometer spacecraft

    NASA Technical Reports Server (NTRS)

    Keafer, L. S., Jr.

    1981-01-01

    An Earth-observation measurements mission is defined for a large-aperture microwave radiometer spacecraft. This mission is defined without regard to any particular spacecraft design concept. Space data application needs, the measurement selection rationale, and broad spacecraft design requirements and constraints are described. The effects of orbital parameters and image quality requirements on the spacecraft and mission performance are discussed. Over the land the primary measurand is soil moisture; over the coastal zones and the oceans important measurands are salinity, surface temperature, surface winds, oil spill dimensions and ice boundaries; and specific measurement requirements have been selected for each. Near-all-weather operation and good spatial resolution are assured by operating at low microwave frequencies using an extremely large aperture antenna in a low-Earth-orbit contiguous mapping mode.

  18. 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

    NASA Astrophysics Data System (ADS)

    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

  19. Pushbroom microwave radiometer results from HAPEX-MOBILHY

    SciTech Connect

    Nichols, W.E. ); Cuenca, R.H. . Dept. of Bioresource Engineering); Schmugge, T.J. . Agricultural Research Service); Wang, J.R. )

    1993-11-01

    The NASA C-130 remote sensing aircraft was in Toulouse, France from 25 May through 4 July 1986, for participation in the HAPEX-MOBILHY program. Spectral and radiometric data were collected by C-130-borne sensors in the visible, infrared, and microwave wavelengths. This data provided information on the spatial and temporal variations of surface parameters such as vegetation indices, surface temperature, and surface soil moisture. The Pushbroom Microwave Radiometer (PBMR) was used to collect passive microwave brightness temperature data. This four-beam sensor operates at the 21-cm wavelength, providing cross-track coverage approximately 1.2 times the aircraft altitude. Observed brightness temperatures for the period were high, ranging from above 230 K to about 290 K. Brightness temperature images appeared to correspond well to spatial and temporal soil moisture variation. When results from wetter soil conditions encountered in another experiment were included, the regression improved dramatically. Based on similar research with the PBMR and an understanding of the ground data collection program, this result was examined to produce recommendations for improvements to future passive microwave research and data collection programs. Examples of surface soil moisture maps generated with PBMR data are presented which appear to be representative of the actual soil moisture conditions.

  20. Advanced Passive Microwave Radiometer Technology for GPM Mission

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

  1. Millimeter-wave imaging radiometer data processing and development of water vapor retrieval algorithms

    NASA Technical Reports Server (NTRS)

    Chang, L. Aron

    1995-01-01

    This document describes the current status of Millimeter-wave Imaging Radiometer (MIR) data processing and the technical development of the first version of a water vapor retrieval algorithm. The algorithm is being used by NASA/GSFC Microwave Sensors Branch, Laboratory for Hydrospheric Processes. It is capable of a three dimensional mapping of moisture fields using microwave data from airborne sensor of MIR and spaceborne instrument of Special Sensor Microwave/T-2 (SSM/T-2).

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

    SciTech Connect

    Frisch, A.S.; Fairall, C.W.; Snider, J.B.; Lenshow, D.H.; Mayer, S.D.

    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.

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

    NASA Technical Reports Server (NTRS)

    Richter, J. C. (Principal Investigator)

    1981-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2016-01-01

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

  6. Rainfall Intensity Estimation by Ground-Based Dual-Frequency Microwave Radiometers.

    NASA Astrophysics Data System (ADS)

    Liu, Gin-Rong; Liu, Chung-Chih; Kuo, Tsung-Hua

    2001-06-01

    Many investigators have used satellite data to derive rainfall intensity and to compare them with rain gauge data. However, there has always been a problem: what is the optimal time period for the two different types of data? A set of well-controlled data collected by ground-based dual-frequency microwave radiometers at the National Central University (24.9°N, 121.1°E) in Taiwan between January of 1996 and December of 1997 was used to find the answer. The results show that a 1-h interval would be the optimal time period and that hourly data will provide a better accuracy than other options (5, 10, or 30 min or 2 h). Two algorithms, the differential and the brightness temperature, were established to estimate rainfall intensity using ground-based dual-frequency microwave brightness temperature and rain gauge data. The results show that the root-mean-square error and the correlation coefficient are 0.63 mm h1 and 0.88, respectively, for the differential method, and 0.91 mm h1 and 0.71 for the brightness temperature method. The analysis also shows that because the atmospheric background and environmental influence in the continuous observations are identical, the changes in brightness temperature are only caused from the changes in liquid water content in the air. That probably made the differential method a better choice for rainfall intensity estimation than the brightness temperature method. Moreover, ground-based radiometers measure downwelling radiation from bottom up, and little ice-particle scattering or horizontal inhomogeneity is involved. The results can be compared with retrievals from satellite microwave radiometers for a better understanding of the physics of microwave emission and scattering due to raindrops or ice particles.

  7. Advanced Microwave Precipitation Radiometer (AMPR) for remote observation of precipitation

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

    The design, development, and tests of the Advanced Microwave Precipitation Radiometer (AMPR) operating in the 10 to 85 GHz range specifically for precipitation retrieval and mesoscale storm system studies from a high altitude aircraft platform (i.e., ER-2) are described. The primary goals of AMPR are the exploitation of the scattering signal of precipitation at frequencies near 10, 19, 37, and 85 GHz together to unambiguously retrieve precipitation and storm structure and intensity information in support of proposed and planned space sensors in geostationary and low earth orbit, as well as storm-related field experiments. The development of AMPR will have an important impact on the interpretation of microwave radiances for rain retrievals over both land and ocean for the following reasons: (1) A scanning instrument, such as AMPR, will allow the unambiguous detection and analysis of features in two dimensional space, allowing an improved interpretation of signals in terms of cloud features, and microphysical and radiative processes; (2) AMPR will offer more accurate comparisons with ground-based radar data by feature matching since the navigation of the ER-2 platform can be expected to drift 3 to 4 km per hour of flight time; and (3) AMPR will allow underflights of the SSM/I satellite instrument with enough spatial coverage at the same frequencies to make meaningful comparisons of the data for precipitation studies.

  8. Retrieval of Atmospheric Temperature from Airborne Microwave Radiometer Observations

    NASA Astrophysics Data System (ADS)

    Xu, Jian; Schreier, Franz; Kenntner, Mareike; Fix, Andreas; Trautmann, Thomas

    2015-06-01

    Atmospheric temperature is a key geophysical parameter associated with fields such as meteorology, climatology, or photochemistry. There exist several techniques to measure temperature profiles. In the case of microwave remote sensing, the vertical temperature profile can be estimated from thermal emission lines of molecular oxygen. The MTP (Microwave Temperature Profiler) instrument is an airborne radiometer developed at the Jet Propulsion Laboratory (JPL), United States. The instrument passively measures natural thermal emission from oxygen lines at 3 frequencies and at a selection of 10 viewing angles (from near zenith to near nadir). MTP has participated in hundreds of flights, including on DLR’s Falcon and HALO aircrafts. These flights have provided data of the vertical temperature distribution from the troposphere to the lower stratosphere with a good temporal and spatial resolution. In this work, we present temperature retrievals based on the Tikhonov-type regularized nonlinear least squares fitting method. In particular, Jacobians (i.e. temperature derivatives) are evaluated by means of automatic differentiation. The retrieval performance from the MTP measurements is analyzed by using synthetic data. Besides, the vertical sensitivity of the temperature retrieval is studied by weighting functions characterizing the sensitivity of the transmission at different frequencies with respect to changes of altitude levels.

  9. Wiener filtering of the COBE Differential Microwave Radiometer data

    NASA Technical Reports Server (NTRS)

    Bunn, Emory F.; Fisher, Karl B.; Hoffman, Yehuda; Lahav, Ofer; Silk, Joseph; Zaroubi, Saleem

    1994-01-01

    We derive an optimal linear filter to suppress the noise from the cosmic background explorer satellite (COBE) Differential Microwave Radiometer (DMR) sky maps for a given power spectrum. We then apply the filter to the first-year DMR data, after removing pixels within 20 deg of the Galactic plane from the data. We are able to identify particular hot and cold spots in the filtered maps at a level 2 to 3 times the noise level. We use the formalism of constrained realizations of Gaussian random fields to assess the uncertainty in the filtered sky maps. In addition to improving the signal-to-noise ratio of the map as a whole, these techniques allow us to recover some information about the cosmic microwave background anisotropy in the missing Galactic plane region. From these maps we are able to determine which hot and cold spots in the data are statistically significant, and which may have been produced by noise. In addition, the filtered maps can be used for comparison with other experiments on similar angular scales.

  10. Nimbus-7 Scanning Multichannel Microwave Radiometer (SMMR) PARM tape user's guide

    NASA Technical Reports Server (NTRS)

    Han, D.; Gloersen, P.; Kim, S. T.; Fu, C. C.; Cebula, R. P.; Macmillan, D.

    1992-01-01

    The Scanning Multichannel Microwave Radiometer (SMMR) instrument, onboard the Nimbus-7 spacecraft, collected data from Oct. 1978 until Jun. 1986. The data were processed to physical parameter level products. Geophysical parameters retrieved include the following: sea-surface temperatures, sea-surface windspeed, total column water vapor, and sea-ice parameters. These products are stored on PARM-LO, PARM-SS, and PARM-30 tapes. The geophysical parameter retrieval algorithms and the quality of these products are described for the period between Nov. 1978 and Oct 1985. Additionally, data formats and data availability are included.

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

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

  12. Effect of vegetation on soil moisture sensing observed from orbiting microwave radiometers

    NASA Technical Reports Server (NTRS)

    Wang, J. R.

    1985-01-01

    The microwave radiometric measurements made by the Skylab 1.4 GHz radiometer and by the 6.6 GHz and 10.7 GHz channels of the Nimbus-7 Scanning Multichannel Microwave Radiometer were analyzed to study the large-area soil moisture variations of land surfaces. Two regions in Texas, one with sparse and the other with dense vegetation covers, were selected for the study. The results gave a confirmation of the vegetation effect observed by ground-level microwave radiometers. Based on the statistics of the satellite data, it was possible to estimate surface soil moisture in about five different levels from dry to wet conditions with a 1.4 GHz radiometer, provided that the biomass of the vegetation cover could be independently measured. At frequencies greater than about 6.6 GHz, the radiometric measurements showed little sensitivity to moisture variation for vegetation-covered soils. The effects of polarization in microwave emission were studied also.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  14. Blending sequential scanning multichannel microwave radiometer and buoy data into a sea ice model

    NASA Astrophysics Data System (ADS)

    Thomas, D. R.; Rothrock, D. A.

    1989-08-01

    A method is presented for determining the concentrations of open water and of several ice types using multichannel satellite passive microwave data. The method uses the Kalman filter and provides the "best fit" to a time series of data. A crucial element of the procedure is a physical model of how the concentrations of ice types change with time in response to freezing, melting, aging of one ice type to another, and creation of open water by divergence of the ice cover. A measurement model relates the state of the ice cover to the multivariate microwave data. The procedure offers three distinct advantages over algorithms that interpret separately data from each instant in time: it provides a framework for incorporating additional data into the diagnosis of ice concentrations, it takes into account the known uncertainty in the microwave observations and the pure type signatures, and it allows the resolution of ice types with ambiguous signatures. Two examples are presented which make use of scanning multichannel microwave radiometer data and surface temperature and ice velocity data from drifting buoys to estimate the concentrations of open water, first-year, second-year, and older multiyear ice for a Lagrangian region of ice. Two other examples include melt ponds in place of second-year ice. Some of the parameters in the physical model (melt rates) and in the measurement model (signature of second-year ice or of frozen melt ponds) are unknown. Reasonable, but arbitrary, values of the unknown parameters are used in the examples.

  15. Atmospheric moisture measurements - A microwave radiometer-radiosonde comparison

    NASA Technical Reports Server (NTRS)

    England, Martin N.; Schmidlin, F. J.; Johansson, Jan M.

    1993-01-01

    Measurements of the thermal emission of the sky at three frequencies (20.7, 22.2, and 31.4 GHz) with the NASA/Goddard Space Flight Center Crustal Dynamics Project MW Water Vapor Radiometer are reported. These measurements are compared with brightness temperatures inferred from measurements from VAISALA radiosonde packages launched every 3 hr during the experiment period. An error analysis for the radiosonde-inferred brightness temperatures is performed under the assumption of reasonable random uncertainties for the pressure, temperature, and humidity measurements and propagation of these uncertainties through the analysis algorithm. For the assumed uncertainties, the dominant contribution to the total uncertainty comes from the temperature measurement (66-88 percent), whereas the relative humidity measurement contributes only 2-8 percent, except in the vicinity of the water vapor line, where the contribution is 10-20 percent.

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

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

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

  18. Observation of sea ice properties with the Nimbus-7 SMMR. [Scanning Multispectral Microwave Radiometer

    NASA Technical Reports Server (NTRS)

    Cavalieri, D. J.; Gloersen, P.; Campbell, W. J.

    1981-01-01

    Techniques for treating Nimbus-7 scanning multispectral microwave radiometer (SMMR) data to retrieve information on sea ice parameters are discussed. The SMMR produces information on ice concentration, temperature, multiyear ice fraction, thin ice fraction, difference between thin and thick ice temperatures, and atmospheric opacity. Sea ice emissivities as determined from ground truth and Nimbus-7 SMMR observations are provided, noting the necessity to further characterize the values with a larger data base. It was found that longest wavelengths displayed the largest contrast between open water and sea. Ice emissivity polarization differences are no more than 0.15 at any wavelength, while water polarizations are never less than 0.52. Ice emissivity increases directly with wavelength, and water emissivity increases inversely. Algorithmic representations of SMMR data to retrieve sea ice parameters are described.

  19. Low Power Silicon Germanium Electronics for Microwave Radiometers

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Technical Reports Server (NTRS)

    Brown, Shannon T.; Desai, Shailen; Lu, Wenwen; Tanner, Alan B.

    2007-01-01

    Results are presented from the long-term monitoring and calibration of the National Aeronautics and Space Administration Jason Microwave Radiometer (JMR) on the Jason-1 ocean altimetry satellite and the ground-based Advanced Water Vapor Radiometers (AWVRs) developed for the Cassini Gravity Wave Experiment. Both radiometers retrieve the wet tropospheric path delay (PD) of the atmosphere and use internal noise diodes (NDs) for gain calibration. The JMR is the first radiometer to be flown in space that uses NDs for calibration. External calibration techniques are used to derive a time series of ND brightness for both instruments that is greater than four years. For the JMR, an optimal estimator is used to find the set of calibration coefficients that minimize the root-mean-square difference between the JMR brightness temperatures and the on-Earth hot and cold references. For the AWVR, continuous tip curves are used to derive the ND brightness. For the JMR and AWVR, both of which contain three redundant NDs per channel, it was observed that some NDs were very stable, whereas others experienced jumps and drifts in their effective brightness. Over the four-year time period, the ND stability ranged from 0.2% to 3% among the diodes for both instruments. The presented recalibration methodology demonstrates that long-term calibration stability can be achieved with frequent recalibration of the diodes using external calibration techniques. The JMR PD drift compared to ground truth over the four years since the launch was reduced from 3.9 to - 0.01 mm/year with the recalibrated ND time series. The JMR brightness temperature calibration stability is estimated to be 0.25 K over ten days.

  1. Advanced systems requirements for ocean observations via microwave radiometers

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

    A future microwave spectroradiometer operating in several frequency bands will have the capability to step or sweep frequencies on an adaptable or programmable basis. The on-board adaptable frequency shifting can make the systems immune from radio interference. Programmable frequency sweeping with on-board data inversion by high speed computers would provide for instantaneous synoptic measurements or sea surface temperature and salinity, water surface and volume pollution, ice thickness, ocean surface winds, snow depth, and soil moisture. Large structure satellites will allow an order of magnitude improvement in the present radiometric measurement spacial resolution.

  2. TOPEX/Poseidon Microwave Radiometer (TMR): 1. Instrument Description and Antenna Temperature Calibration

    NASA Technical Reports Server (NTRS)

    Ruf, C. S.; Keihm, S. J.; Janssen, M. A.

    1993-01-01

    The TOPEX/Poseidon Microwave Radiometer (TMR) is a 3-frequency radiometer flown on the TOPEX/Poseidon (T/P) satellite in low Earth orbit. It operates at 18, 21 and 37 GHz in a nadir only viewing direction which is co-aligned with the T/P radar altimeters. TMR monitors and corrects for the electrical path delay of the altimeter radar signal due to water vapor and non-precipitating liquid water in the atmosphere. This paper describes the TMR instrument and the radiometric instrument calibration required to derive antenna temperature (T_A) from the raw digital data. T_A precision of 0.4 K is predicted on orbit in all expected thermal environments. T_A accuracy of 0.5-0.6 K is expected following a post-launch field calibration campaign. When uncertainties related to antenna sidelobe corrections are included, this T_A accuracy yields a brightness temperature accuracy of 0.7- 0.8 K...

  3. Short term prediction of dynamic hydra precipitation activity using a microwave radiometer over Eastern Himalaya, India

    NASA Astrophysics Data System (ADS)

    Singh, S.

    2015-12-01

    First ever study of the feasibility of ground based radiometric study to predict a very short term based rain precipitation study has been conducted in eastern Himalaya, Darjeeling (27.01°N, 88.15°E, 2200 masl). Short term prediction or nowcasting relates to forecasting convective precipitation for time periods less than a few hours to avoid its effect on agriculture, aviation and lifestyle. Theoretical models involving radiometric predictions are not well understood and lack in temporal and spatial resolution. In this study specific utilization of a microwave Radiometer (Radiometrics Corporation, USA) for online monitoring of precipitable rainfall activity has been observed repeatability of data has been established. Previous few studies have shown the increase of water vapour and corresponding Brightness Temperature, but in mountain climatic conditions over Darjeeling, due to presence of fog 90 % of the year, water vapour monitoring related predictions can lead to false alarms. The measurement of blackbody emission noise in the bands of 23.8 GHz and 31.4 GHz, using a quadratic regression retrieval algorithm is converted to atmospheric parameters like integrated water vapour and liquid water content. It has been found in our study that the liquid water shows significant activity prior to precipitation events even for mild and stratiform rainfall. The alarm can be generated well 20 mins before the commencement of actual rain events even in the upper atmosphere of 6 Kms, measured by a rain radar also operating in 24 Ghz microwave band. Although few rain events were found and reported which do not respond in the microwave liquid water channel. Efforts to identify such rain events and their possible explanation is going on and shall be reported in near future. Such studies are important to predict flash flooding in the Himalayas. Darjeeling owing to its geographical conditions experiences mild to very heavy rain. Such studies help improve aspects of Himalayas as

  4. Microwave Radiometers from 0.6 to 22 GHz for Juno, a Polar Orbiter around Jupiter

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

    A compact radiometer instrument is under development at JPL for Juno, the next NASA New Frontiers mission, scheduled to launch in 2011. This instrument is called the MWR (MicroWave Radiometer), and its purpose is to measure the thermal emission from Jupiter's atmosphere at selected frequencies from 0.6 to 22 GHz. The objective is to measure the distributions and abundances of water and ammonia in Jupiter's atmosphere, with the goal of understanding the previously unobserved dynamics of the subcloud atmosphere, and to discriminate among models for planetary formation in our solar system. The MWR instrument is currently being developed to address these science questions for the Juno mission. As part of a deep space mission aboard a solar-powered spacecraft, MWR is designed to be compact, lightweight, and low power. The entire MWR instrument consists of six individual radiometer channels with approximately 4% bandwidth at 0.6, 1.25,2.6,5.2, 10,22 GHz operating in direct detection mode. Each radiometer channel has up to 80 dB of gain with a noise figure of several dB. The highest frequency channel uses a corrugated feedhorn and waveguide transmission lines, whereas all other channels use highly phase stable coaxial cables and either patch array or waveguide slot array antennas. Slot waveguide array antennas were chosen for the low loss at the next three highest frequencies and patch array antennas were implemented due to the mass constraint at the two lowest frequencies. The six radiometer channels receive their voltage supplies and control lines from an electronics unit that also provides the instrument communication interface to the Juno spacecraft. For calibration purposes each receiver has integrated noise diodes, a Dicke switch, and temperature sensors near each component that contributes to the noise figure. In addition, multiple sensors will be placed along the RF transmission lines and the antennas in order to measure temperature gradients. All antennas and RF

  5. Interpretation of the cosmic microwave background radiation anisotropy detected by the COBE Differential Microwave Radiometer

    NASA Technical Reports Server (NTRS)

    Wright, E. L.; Meyer, S. S.; Bennett, C. L.; Boggess, N. W.; Cheng, E. S.; Hauser, M. G.; Kogut, A.; Lineweaver, C.; Mather, J. C.; Smoot, G. F.

    1992-01-01

    The large-scale cosmic background anisotropy detected by the COBE Differential Microwave Radiometer (DMR) instrument is compared to the sensitive previous measurements on various angular scales, and to the predictions of a wide variety of models of structure formation driven by gravitational instability. The observed anisotropy is consistent with all previously measured upper limits and with a number of dynamical models of structure formation. For example, the data agree with an unbiased cold dark matter (CDM) model with H0 = 50 km/s Mpc and Delta-M/M = 1 in a 16 Mpc radius sphere. Other models, such as CDM plus massive neutrinos (hot dark matter (HDM)), or CDM with a nonzero cosmological constant are also consistent with the COBE detection and can provide the extra power seen on 5-10,000 km/s scales.

  6. Microwave remote sensing of soil water content

    NASA Technical Reports Server (NTRS)

    Cihlar, J.; Ulaby, F. T.

    1975-01-01

    Microwave remote sensing of soils to determine water content was considered. A layered water balance model was developed for determining soil water content in the upper zone (top 30 cm), while soil moisture at greater depths and near the surface during the diurnal cycle was studied using experimental measurements. Soil temperature was investigated by means of a simulation model. Based on both models, moisture and temperature profiles of a hypothetical soil were generated and used to compute microwave soil parameters for a clear summer day. The results suggest that, (1) soil moisture in the upper zone can be predicted on a daily basis for 1 cm depth increments, (2) soil temperature presents no problem if surface temperature can be measured with infrared radiometers, and (3) the microwave response of a bare soil is determined primarily by the moisture at and near the surface. An algorithm is proposed for monitoring large areas which combines the water balance and microwave methods.

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

    NASA Astrophysics Data System (ADS)

    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.

  8. Dual frequency microwave radiometer measurements of soil moisture for bare and vegetated rough surfaces

    NASA Technical Reports Server (NTRS)

    Lee, S. L.

    1974-01-01

    Controlled ground-based passive microwave radiometric measurements on soil moisture were conducted to determine the effects of terrain surface roughness and vegetation on microwave emission. Theoretical predictions were compared with the experimental results and with some recent airborne radiometric measurements. The relationship of soil moisture to the permittivity for the soil was obtained in the laboratory. A dual frequency radiometer, 1.41356 GHz and 10.69 GHz, took measurements at angles between 0 and 50 degrees from an altitude of about fifty feet. Distinct surface roughnesses were studied. With the roughness undisturbed, oats were later planted and vegetated and bare field measurements were compared. The 1.4 GHz radiometer was less affected than the 10.6 GHz radiometer, which under vegetated conditions was incapable of detecting soil moisture. The bare surface theoretical model was inadequate, although the vegetation model appeared to be valid. Moisture parameters to correlate apparent temperature with soil moisture were compared.

  9. High altitude airborne remote sensing mission using the advanced microwave precipitation radiometer (AMPR)

    NASA Technical Reports Server (NTRS)

    Galliano, J.; Platt, R. H.; Spencer, Roy; Hood, Robbie

    1991-01-01

    The advanced microwave precipitation radiometer (AMPR) is an airborne multichannel imaging radiometer used to better understand how the earth's climate structure works. Airborne data results from the October 1990 Florida thunderstorm mission in Jacksonville, FL, are described. AMPR data on atmospheric precipitation in mesoscale storms were retrieved at 10.7, 19.35, 37.1, and 85.5 GHz onboard the ER-2 aircraft at an altitude of 20 km. AMPR's three higher-frequency data channels were selected to operate at the same frequencies as the spaceborne special sensor microwave/imager (SSM/I) presently in orbit. AMPR uses two antennas to receive the four frequencies: the lowest frequency channel uses a 9.7-in aperture lens antennas, while the three higher-frequency channels share a separate 5.3-in aperture lens antenna. The radiometer's temperature resolution performance is summarized.

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

    NASA Technical Reports Server (NTRS)

    1978-01-01

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

  11. Orbiting multi-beam microwave radiometer for soil moisture remote sensing

    NASA Technical Reports Server (NTRS)

    Shiue, J. C.; Lawrence, R. W.

    1985-01-01

    The effects of soil moisture and other factors on soil surface emissivity are reviewed and design concepts for a multibeam microwave radiometer with a 15 m antenna are described. Characteristic antenna gain and radiation patterns are shown and losses due to reflector roughness are estimated.

  12. Multifrequency Aperture-Synthesizing Microwave Radiometer System (MFASMR). Volume 2: Appendix

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    A number of topics supporting the systems analysis of a multifrequency aperture-synthesizing microwave radiometer system are discussed. Fellgett's (multiple) advantage, interferometer mapping behavior, mapping geometry, image processing programs, and sampling errors are among the topics discussed. A FORTRAN program code is given.

  13. Relocation of Advanced Water Vapor Radiometer 1 to Deep Space Station 55

    NASA Technical Reports Server (NTRS)

    Oswald, J.; Riley, L.; Hubbard, A.; Rosenberger, H.; Tanner, A.; Keihm, S.; Jacobs, C.; Lanyi, G.; Naudet, C.

    2005-01-01

    In June of 2004, the Advanced Water Vapor Radiometer (AWVR) unit no. 1 was relocated to the Deep Space Station (DSS) 55 site in Madrid, Spain, from DSS 25 in Goldstone, California. This article summarizes the relocation activity and the subsequent operation and data acquisition. This activity also relocated the associated Microwave Temperature Profiler (MTP) and Surface Meteorology (SurfMET) package that collectively comprise the Cassini Media Calibration System (MCS).

  14. Iapetus' near surface thermal emission modeled and constrained using Cassini RADAR Radiometer microwave observations

    NASA Astrophysics Data System (ADS)

    Le Gall, A.; Leyrat, C.; Janssen, M. A.; Keihm, S.; Wye, L. C.; West, R.; Lorenz, R. D.; Tosi, F.

    2014-10-01

    most probably >200 J m-2 K-1 s-1/2 is inferred. This suggests a gradient in density with depth or, more likely, that the Radiometer has probed the icy substrate underlying the dark layer. Furthermore, the measured thermal emission is found to arise from the upper few meters of the subsurface, which points to tholins, rather than iron oxide compounds, as the primary contaminants of the dark material. We also find that, although there is a latitudinal decrease probably related to the thinning of the dark layer away from the Equator, the CR region exhibits a high 2.2-cm emissivity, 0.87 in average, which is close to the emissivity of Phoebe, a putative source of the dark matter. In the case of RT + ST, model fitting points to a mean thermal inertia of ∼160 J m-2 K-1 s-1/2 along with the possible presence of an absorbing compound in the regolith of the bright terrains. Nevertheless, this layer is transparent enough for the Radiometer to capture the seasonal contrast between the northern and southern hemispheres. Lastly, a global decline of the microwave emissivity with latitude is revealed; it is probably indicative of a progressive increase of the water ice content in the near surface.

  15. On the determination of atmospheric path length by passive microwave radiometer

    NASA Technical Reports Server (NTRS)

    Webster, W. J., Jr.

    1975-01-01

    Microwave radiometer techniques were evaluated for use in atmospheric path length correction of Pacific Plate Motion Experiment interferometer measurements. It is shown that passive microwave radiometry allows precise measurement of the brightness temperature of the sky. It is also noted that the technological requirements of radiometers are very different from the requirements of radio astronomy. The technology was used in the construction of radiometers which are sufficient for use in the path length correction problem. A simulation study shows that, when combined with surface meteorology data, passive microwave radiometer data would allow a determination of the path length correction to better than 2 cm at the zenith. By a careful choice of frequencies, a dual frequency system would allow a measurement of the path length correction to better than 4 cm at zenith angles as great as 60 deg. Because of the wide range of weather conditions to be expected for the PPME sites (which include Alaska, Hawaii and Massachusetts), it will probably be necessary to use a separate correction algorithm for each site.

  16. Soil moisture detection by Skylab's microwave sensors. [radiometer/scatterometer measurements of Texas

    NASA Technical Reports Server (NTRS)

    Moore, R. K.; Ulaby, F. T. (Principal Investigator); Barr, J. C.; Sobti, A.

    1974-01-01

    The author has identified the following significant results. Terrain microwave backscatter and emission response to soil moisture variations were investigated using Skylab's 13.9 GHz RADSCAT (radiometer/scatterometer) system. Data acquired on June 5, 1973, over a test site in west-central Texas indicated a fair degree of correlation with composite rainfall. The scan made was cross-track contiguous (CTC) with a pitch of 29.4 deg and no roll effect. Vertical polarization was employed with both radiometer and scatterometer. The composite rainfall was computed according to the flood prediction technique using rainfall data supplied by weather reporting stations.

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

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

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

  18. Modeling the frequency response of microwave radiometers with QUCS

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

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

    NASA Astrophysics Data System (ADS)

    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.

  20. Studies on Physical Properties of Snow Based on Multi Channel Microwave Radiometer

    NASA Technical Reports Server (NTRS)

    Tsuchiya, K.; Takeda, K.

    1985-01-01

    The analysis of the data observed over a snow field with a breadboard model of MSR (microwave scanning radiometer) to be installed in MOS-1 (Marine Observation Satellite-1) indicates that: (1) the influence of incident angle on brightness temperature is larger in horizontal polarization component than in vertical polarization component. The effect of incident angle depends upon the property of snow with larger value for dry snow; (2) the difference of snow surface configuration consisting of artifically made parallel ditches of 5 cm depth and 5 cm width with spacing of 10 and 30 cm respectively which are oriented normal to electrical axis do not affect brightness temperature significantly; and (3) there is high negative correlation between brightness temperature and snow depth up to the depth of 70 cm which suggests that the snow depth can be measured with a two channel microwave radiometer up to this depth.

  1. Stratiform and Convective Rain Discrimination from Microwave Radiometer Observations

    NASA Technical Reports Server (NTRS)

    Prabhakara, C.; Cadeddu, M.; Short, D. A.; Weinman, J. A.; Schols, J. L.; Haferman, J.

    1997-01-01

    A criterion based on the SSM/I observations is developed to discriminate rain into convective and stratiform types. This criterion depends on the microwave polarization properties of the flat melting snow particles that fall slowly in the stratiform clouds. Utilizing this criterion and some spatial and temporal characteristics of hydrometeors in TOGA-COARE area revealed by ship borne radars, we have developed an algorithm to retrieve convective and stratiform rain rate from SSM/I data.

  2. Effects of antenna blockage on radio frequency performance of the microwave radiometer spacecraft

    NASA Technical Reports Server (NTRS)

    Sikes, L. D.; Hower, T.

    1981-01-01

    Radio frequency scaled models of the microwave radiometer spacecraft suspended feed concept were tested to determine the effects of aperture blockage on the antenna radiation pattern. Contributors to the uncertainty of the test measurements were evaluated, and an estimate of the blockage effects was made for comparison with the test measurements. The gain loss budget associated with reflector performance characteristics (aperture blockage, surface reflectivity, reflector roughness, and defocus) was determined.

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

    NASA Technical Reports Server (NTRS)

    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.

  4. L band push broom microwave radiometer: Soil moisture verification and time series experiment Delmarva Peninsula

    NASA Technical Reports Server (NTRS)

    Jackson, T. J.; Shiue, J.; Oneill, P.; Wang, J.; Fuchs, J.; Owe, M.

    1984-01-01

    The verification of a multi-sensor aircraft system developed to study soil moisture applications is discussed. This system consisted of a three beam push broom L band microwave radiometer, a thermal infrared scanner, a multispectral scanner, video and photographic cameras and an onboard navigational instrument. Ten flights were made of agricultural sites in Maryland and Delaware with little or no vegetation cover. Comparisons of aircraft and ground measurements showed that the system was reliable and consistent. Time series analysis of microwave and evaporation data showed a strong similarity that indicates a potential direction for future research.

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

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  7. The 1982-1983 El Nino Atlas: Nimbus-7 microwave radiometer data

    NASA Technical Reports Server (NTRS)

    Liu, W. Timothy

    1987-01-01

    Monthly maps of sea surface temperature, atmospheric water vapor, and surface level wind speed as measured by the Scanning Multichannel Microwave Radiometer (SMMR) on the Nimbus-7 satellite for the tropical Pacific from June 1982 to October 1983, during one of the most intense El Nino Southern Oscillations (ENSO) episodes, are presented. The non-ENSO annual cycle was compiled by averaging the 1980 and 1981 data for each calendar month and was removed from monthly fields of 1982 and 1983 to reveal the anomalous distributions. The anomaly fields and part of the non-ENSO annual cycle are also presented. This study and earlier evaluations demonstrate that the Nimbus/SMMR can be used to monitor large scale and low frequency variabilities in the tropical ocean. The SMMR data support and extend conventional measurements. The variabilities of the three parameters are found to represent various aspects of ENSO related through ocean atmosphere interaction. Their simultaneous and quantitative descriptions pave the way for the derivation of ocean atmosphere latent heat exchange and further the understanding of the coupled atmospheric and oceanic thermodynamics.

  8. Microwave Radiometers from 0.6 to 22 GHz for Juno, a Polar Orbiter around Jupiter

    NASA Technical Reports Server (NTRS)

    Pingree, Paula J.; 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 also provides for 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.

  9. Science Data Processing for the Advanced Microwave Scanning Radiometer: Earth Observing System

    NASA Technical Reports Server (NTRS)

    Goodman, H. Michael; Regner, Kathryn; Conover, Helen; Ashcroft, Peter; Wentz, Frank; Conway, Dawn; Lobl, Elena; Beaumont, Bruce; Hawkins, Lamar; Jones, Steve

    2004-01-01

    The National Aeronautics and Space Administration established the framework for the Science Investigator-led Processing Systems (SIPS) to enable the Earth science data products to be produced by personnel directly associated with the instrument science team and knowledgeable of the science algorithms. One of the first instantiations implemented for NASA was the Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E) SIPS. The AMSR-E SIPS is a decentralized, geographically distributed ground data processing system composed of two primary components located in California and Alabama. Initial science data processing is conducted at Remote Sensing Systems (RSS) in Santa Rosa, California. RSS ingests antenna temperature orbit data sets from JAXA and converts them to calibrated, resampled, geolocated brightness temperatures. The brightness temperatures are sent to the Global Hydrology and Climate Center in Huntsville, Alabama, which generates the geophysical science data products (e.g., water vapor, sea surface temperature, sea ice extent, etc.) suitable for climate research and applications usage. These science products are subsequently sent to the National Snow and Ice Data Center Distributed Active Archive Center in Boulder, Colorado for archival and dissemination to the at-large science community. This paper describes the organization, coordination, and production techniques employed by the AMSR-E SIPS in implementing, automating and operating the distributed data processing system.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  12. The Moon as Possible Calibration Reference for Microwave Radiometers

    NASA Astrophysics Data System (ADS)

    Burgdorf, Martin; Buehler, Stefan; Hans, Imke; Lang, Theresa; Michel, Simon

    2016-04-01

    Instruments on satellites for Earth observation on polar orbits usually employ a two-point calibration technique, in which deep space and an on-board calibration target provide two reference flux levels. As the direction of the deep space view is in general close to the celestial equator, the Moon moves sometimes through the field of view and introduces an unwelcome additional signal. One can take advantage of this intrusion, however, by using the Moon as a third flux standard, and this has actually been done for checking the lifetime stability of sensors operating at visible wavelengths. We discuss the advantages and problems of extending this concept to microwaves, concentrating on the frequency of appearances of the Moon in the deep space view, the factors limiting the accuracy of both measurements and models of the Moon's brightness, as well as benefits from complementing the naturally occurring appearances of the Moon with dedicated spacecraft maneuvers. Such pre-planned rotations of the instrument would allow to observe the Moon at a well-defined phase angle and to put it at the exact center of the field of view. This way they would eliminate the need for a model of the Moon's brightness temperature when checking instrumental stability. Finally we investigate the question, whether foreground emission from objects other than the Moon can contaminate the measurements of the Cosmic Microwave Background, which provides the low reference flux in the deep space view. We show that even the brightest discreet sources do not increase significantly the signal from a single scan.

  13. GROMOS-C, a novel ground-based microwave radiometer for ozone measurement campaigns

    NASA Astrophysics Data System (ADS)

    Fernandez, S.; Murk, A.; Kämpfer, N.

    2015-07-01

    Stratospheric ozone is of major interest as it absorbs most harmful UV radiation from the sun, allowing life on Earth. Ground-based microwave remote sensing is the only method that allows for the measurement of ozone profiles up to the mesopause, over 24 hours and under different weather conditions with high time resolution. In this paper a novel ground-based microwave radiometer is presented. It is called GROMOS-C (GRound based Ozone MOnitoring System for Campaigns), and it has been designed to measure the vertical profile of ozone distribution in the middle atmosphere by observing ozone emission spectra at a frequency of 110.836 GHz. The instrument is designed in a compact way which makes it transportable and suitable for outdoor use in campaigns, an advantageous feature that is lacking in present day ozone radiometers. It is operated through remote control. GROMOS-C is a total power radiometer which uses a pre-amplified heterodyne receiver, and a digital fast Fourier transform spectrometer for the spectral analysis. Among its main new features, the incorporation of different calibration loads stands out; this includes a noise diode and a new type of blackbody target specifically designed for this instrument, based on Peltier elements. The calibration scheme does not depend on the use of liquid nitrogen; therefore GROMOS-C can be operated at remote places with no maintenance requirements. In addition, the instrument can be switched in frequency to observe the CO line at 115 GHz. A description of the main characteristics of GROMOS-C is included in this paper, as well as the results of a first campaign at the High Altitude Research Station at Jungfraujoch (HFSJ), Switzerland. The validation is performed by comparison of the retrieved profiles against equivalent profiles from MLS (Microwave Limb Sounding) satellite data, ECMWF (European Centre for Medium-Range Weather Forecast) model data, as well as our nearby NDACC (Network for the Detection of Atmospheric

  14. Advanced Component Development to Enable Low-Mass, Low-Power High-Frequency Microwave Radiometers for Coastal Wet-Tropospheric Correction on SWOT

    NASA Astrophysics Data System (ADS)

    Reising, S. C.; Brown, S.; Kangaslahti, P.; Hoppe, D.; Dawson, D.; Lee, A.; Albers, D.; Montes, O.; Gaier, T.; Khayatian, B.

    2010-12-01

    Critical microwave component and receiver technologies are under development to reduce the risk, cost, volume, mass, and development time for a high-frequency microwave radiometer needed to enable wet-tropospheric correction in the coastal zone and over land as part of the NRC Decadal Survey-recommended Surface Water and Ocean Topography (SWOT) Mission. Current satellite ocean altimeters include a nadir-viewing, co-located 18-37 GHz multi-channel microwave radiometer to measure wet-tropospheric path delay. However, due to the area of the instantaneous fields of view on the surface at these frequencies, the accuracy of wet path retrievals begins to degrade at approximately 50 km from the coasts. Addition of higher-frequency microwave channels to the Jason-class radiometers on the recommended SWOT mission will improve retrievals in coastal regions and enable retrievals over land. Specifically, high-frequency window channels at 92, 130 and 166 GHz are optimum for wet path delay retrievals in coastal regions. New, high-sensitivity, wide-bandwidth mm-wave radiometers using both window and sounding channels show good potential for over-land wet-path delay retrievals. This work focuses on the design and fabrication of a prototype system consisting of: (1) a low-power, low-mass and small-volume direct-detection millimeter-wave radiometer with integrated calibration sources covering frequencies from 90 to 170 GHz that fits within the overall SWOT mission constraints, and (2) a multi-frequency feed horn covering the same frequency range. Three key component technologies are under development to scale the design of the Advanced Microwave Radiometer (AMR) on the OSTM/Jason-2 altimetry mission from 18-34 GHz to 90-170 GHz, i.e. a PIN-diode switch for calibration that can be integrated into the receiver front end, a high-Excess Noise Ratio (ENR) noise source and a single, tri-frequency feed horn. These new components are currently in the process of fabrication and testing, after

  15. Microwave radiometer experiment of soil moisture sensing at BARC test site during summer 1981

    NASA Technical Reports Server (NTRS)

    Wang, J.; Jackson, T.; Engman, E. T.; Gould, W.; Fuchs, J.; Glazer, W.; Oneill, P.; Schmugge, T. J.; Mcmurtrey, J., III

    1984-01-01

    Soil moisture was measured by truck mounted microwave radiometers at the frequencies of 1.4 GHz, 5 GHz, and 10.7 GHz. The soil textures in the two test sites were different so that the soil type effect of microwave radiometric response could be studied. Several fields in each test site were prepared with different surface roughnesses and vegetation covers. Ground truth on the soil moisture, temperature, and the biomass of the vegetation was acquired in support of the microwave radiometric measurements. Soil bulk density for each of the fields in both test sites was sampled. The soils in both sites were measured mechanically and chemically. A tabulation of the measured data is presented and the sensors and operational problems associated with the measurements are discussed.

  16. Design data collection with Skylab microwave radiometer-scatterometer S-193, volume 2

    NASA Technical Reports Server (NTRS)

    Moore, R. K.; Ulaby, F. T. (Principal Investigator)

    1975-01-01

    The author has identified the following significant results. Skylab S-193 radiometer/scatterometer produced terrain responses with various polarizations and observation angles for cells of 100 to 400 sq km area. Classification of the observations into natural categories was achieved by K-means and spatial clustering algorithms. Microwave data acquired over the Great Salt Lake Desert area by sensors aboard Skylab and Nimbus 5 indicate that the microwave emission and backscatter were strongly influenced by contributions from subsurface layers of sediment saturated with brine. Correlations were noted between microwave backscatter response at approximately 33 deg from scatterometer (operating at 13.9 GHz) and the configuration of ground targets in Brazil as discerned from coarse scale maps. With limited, available ground truth, these correlations were sufficient to permit the production of image-like displays which bear a marked resemblance to known terrain features in several instances.

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

    NASA Astrophysics Data System (ADS)

    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.

  18. On-orbit structural dynamic performance of a 15-meter microwave radiometer antenna

    NASA Technical Reports Server (NTRS)

    Wahls, Deborah M.; Farmer, Jeffery T.; Sleight, David W.

    1990-01-01

    The on-orbit structural dynamic performance of a microwave radiometer antenna for Earth science applications is addressed. The radiometer is one of the Earth-observing instruments aboard a proposed geostationary platform as part of the Mission to the Planet Earth. A sequential approach is presented for assessing the ability of an antenna structure to retain its geometric shape subject to a representative onboard disturbance. This approach includes establishing the structural requirements of the antenna, developing the structural and disturbance models, performing modal and forced response analyses, and evaluating the resulting distortions in terms of the antenna's ability to meet stringent structural performance requirements. Two antenna configurations are discussed: free-flying and platform-mounted. These configurations are analyzed for a representative disturbance function which simulates rotation of the subreflector in order to perform a raster-type scan of the Earth disk. Results show that the scanning maneuver modeled would not induce antenna structural errors outside the specified limits.

  19. Large area mapping of soil moisture using the ESTAR passive microwave radiometer

    NASA Technical Reports Server (NTRS)

    Jackson, T. J.; Levine, D. M.; Swift, C. T.; Schmugge, T. J.

    1994-01-01

    Investigations designed to study land surface hydrologic-atmospheric interactions, showing the potential of L band passive microwave radiometry for measuring surface soil moisture over large areas, are discussed. Satisfying the data needs of these investigations requires the ability to map large areas rapidly. With aircraft systems this means a need for more beam positions over a wider swath on each flightline. For satellite systems the essential problem is resolution. Both of these needs are currently being addressed through the development and verification of Electronically Scanned Thinned Array Radiometer (ESTAR) technology. The ESTAR L band radiometer was evaluated for soil moisture mapping applications in two studies. The first was conducted over the semiarid rangeland Walnut Gulch watershed located in south eastern Arizona (U.S.). The second was performed in the subhumid Little Washita watershed in south west Oklahoma (U.S.). Both tests showed that the ESTAR is capable of providing soil moisture with the same level of accuracy as existing systems.

  20. The Split Window Microwave Radiometer (SWMR) for hurricane wind speed measurement from space

    NASA Technical Reports Server (NTRS)

    Swift, Calvin T.; Black, P. G.

    1992-01-01

    The monitoring of hurricanes demands considerable resources each year by the National Oceanic and Atmospheric Administration. Even with the extensive use of satellite and airborne probing of those storms, there is still much uncertainty involved in predicting landfall for timely evacuation of people subject to the threat. The concept of the Split Window Microwave Radiometer (SWMR) is to add an additional capability of remotely measuring surface winds to hopefully improve prediction capabilities or at least define the severity of the storm while it is far from land. Some of the present science and observational needs are addressed in this report as are remote sensing limitations which impact the design of a minimal system which can be launched into low earth orbit by a low cost launch system. This study has concluded that wind speed and rain rate maps of hurricanes can be generated with an X-Band radiometer system with an antenna whose aperture is 2 m on a side.

  1. GROMOS-C, a novel ground based microwave radiometer for ozone measurement campaigns

    NASA Astrophysics Data System (ADS)

    Fernandez, S.; Murk, A.; Kämpfer, N.

    2015-03-01

    Stratospheric ozone is of major interest as it absorbs most of harmful UV radiation from the sun, allowing life on Earth. Ground based microwave remote sensing is the only method that allows to measure ozone profiles up to the mesopause, 24 h and under different weather conditions with high time resolution. In this paper a novel ground based microwave radiometer is presented. It is called GROMOS-C (GRound based Ozone MOnitoring System for Campaigns), and it has been designed to measure the vertical profile of ozone distribution in the middle atmosphere, by observing ozone emission spectra at a frequency of 110.836 GHz. The instrument is designed in a compact way which makes it transportable and suitable for outdoor use in campaigns, an advantageous feature that is lacking in present day ozone radiometers. It is operated through remote control. GROMOS-C is a total power radiometer which uses a preamplified heterodyne receiver, and a digital Fast Fourier Transform spectrometer for the spectral analysis. Among its main new features stands out the incorporation of different calibration loads, including a noise diode and a new type of blackbody target specifically designed for this instrument, based on Peltier elements. The calibration scheme does not depend on the use of liquid nitrogen, therefore GROMOS-C can be operated at remote places with no maintenance requirements. In addition the instrument can be switched in frequency to observe the CO line at 115 GHz. A description of the main characteristics of GROMOS-C is included in this paper, as well as the results of a first campaign at the High Altitude Research Station in Jungfraujoch (HFSJ), Switzerland. The validation is performed by comparison of the retrieved profiles against equivalent profiles from MLS satellite data, ECMWF model data, as well as our nearby NDACC ozone radiometer measuring at Bern.

  2. Development of Low-Mass, Low-Power High-Frequency Microwave Radiometers to Improve Coastal and Enable Over-Land Wet-Tropospheric Correction for SWOT

    NASA Astrophysics Data System (ADS)

    Reising, S. C.; Kangaslahti, P.; Brown, S.; Dawson, D.; Lee, A.; Albers, D.; Hoppe, D.; Montes, O.; Gaier, T.; Khayatian, B.

    2011-12-01

    Current satellite ocean altimeters include nadir-viewing, co-located 18-37 GHz multi-channel 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 begins to degrade at approximately 40 km from the coasts. Higher-frequency radiometers with internal calibration are under development to assess their suitability as part of the Surface Water and Ocean Topography (SWOT) accelerated Tier-2 mission recommended by the National Research Council's Earth Science Decadal Survey and planned for launch in 2020. The addition of these high-frequency radiometers to current Jason-class radiometers is expected to improve retrievals of wet-tropospheric delay in coastal areas and to increase the potential for over-land retrievals. Specifically, high-frequency window channels at 92, 130 and 166 GHz are optimum for wet path delay retrievals in coastal regions. New, high-sensitivity, wide-bandwidth mm-wave radiometers using both window and sounding channels show good potential for over-land wet-path delay retrievals. Critical microwave component and receiver technologies are under development to reduce the risk, cost, volume, mass, and development time for high-frequency microwave radiometers. This project focuses on the design and fabrication of a prototype system consisting of : (1) low-power, low-mass and small-volume direct-detection millimeter-wave radiometers with integrated calibration sources operating from 90 to 170 GHz that fit within the overall SWOT mission constraints, and (2) a multi-frequency feed horn covering the same frequency range. The three key component technologies under development to achieve these objectives are PIN-diode switches for internal calibration that can be integrated into the receiver front end, high-Excess Noise Ratio (ENR) noise sources and a single, tri-frequency feed horn. These new components are being integrated into

  3. A microwave radiometer weather-correcting sea ice algorithm

    NASA Technical Reports Server (NTRS)

    Walters, J. M.; Ruf, C.; Swift, C. T.

    1987-01-01

    A new algorithm for estimating the proportions of the multiyear and first-year sea ice types under variable atmospheric and sea surface conditions is presented, which uses all six channels of the SMMR. The algorithm is specifically tuned to derive sea ice parameters while accepting error in the auxiliary parameters of surface temperature, ocean surface wind speed, atmospheric water vapor, and cloud liquid water content. Not only does the algorithm naturally correct for changes in these weather conditions, but it retrieves sea ice parameters to the extent that gross errors in atmospheric conditions propagate only small errors into the sea ice retrievals. A preliminary evaluation indicates that the weather-correcting algorithm provides a better data product than the 'UMass-AES' algorithm, whose quality has been cross checked with independent surface observations. The algorithm performs best when the sea ice concentration is less than 20 percent.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Technical Reports Server (NTRS)

    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

  6. A Model for Estimation of Rain Rate on Tropical Land from TRMM Microwave Imager Radiometer Observations

    NASA Technical Reports Server (NTRS)

    Prabhakara, C.; Iacovazzi, R., Jr.; Yoo, J.-M.; Kim, Kyu-Myong

    2004-01-01

    Over the tropical land regions observations of the 85 GHz brightness temperature (T(sub 85v)) made by the TRMM Microwave Imager (TMI) radiometer when analyzed with the help of rain rate (R(sub pR)) deduced from the TRMM Precipitation Radar (PR) indicate that there are two maxima in rain rate. One strong maximum occurs when T(sub 85) has a value of about 220 K and the other weaker one when T(sub 85v) is much colder approx. 150 K. Together with the help of earlier studies based on airborne Doppler Radar observations and radiative transfer theoretical simulations, we infer the maximum near 220 K is a result of relatively weak scattering due to super cooled rain drops and water coated ice hydrometeors associated with a developing thunderstorm (Cb) that has a strong updraft. The other maximum is associated with strong scattering due to ice particles that are formed when the updraft collapses and the rain from the Cb is transit2oning from convective type to stratiform type. Incorporating these ideas and with a view to improve the estimation of rain rate from existing operational method applicable to the tropical land areas, we have developed a rain retrieval model. This model utilizes two parameters, that have a horizontal scale of approx. 20km, deduced from the TMI measurements at 19, 21 and 37 GHz (T(sub 19v), T(sub 21v), T(sub 37v). The third parameter in the model, namely the horizontal gradient of brightness temperature within the 20 km scale, is deduced from TMI measurements at 85 GHz. Utilizing these parameters our retrieval model is formulated to yield instantaneous rain rate on a scale of 20 km and seasonal average on a mesoscale that agree well with that of the PR.

  7. Soil moisture verification study of the ESTAR microwave radiometer - Walnut Gulch, AZ 1991

    NASA Technical Reports Server (NTRS)

    Jackson, T. J.; Le Vine, D. M.; Griffis, A.; Goodrich, D. C.; Schmugge, T. J.; Swift, C. T.; O'Neill, P. E.; Roberts, R. R.; Parry, R.

    1992-01-01

    The application of an electronically steered thinned array L-band radiometer (ESTAR) for soil moisture mapping is investigated over the arid rangeland Walnut Gulch Watershed. Antecedent rainfall and evaporation for the flights are very different and result in a wide range of soil moisture conditions. The high spatial variability of rainfall events within this region results in moisture conditions with dramatic spatial patterns. Sensor performance is verified using two approaches. Microwave data are used in conjunction with a microwave emission model to predict soil moisture. These predictions are compared to ground observations of soil moisture. A second verification is possible using an extensive data set. Both tests showed that the ESTAR is capable of providing soil moisture with the same level of accuracy as existing systems.

  8. Errors from Rayleigh-Jeans approximation in satellite microwave radiometer calibration systems.

    PubMed

    Weng, Fuzhong; Zou, Xiaolei

    2013-01-20

    The advanced technology microwave sounder (ATMS) onboard the Suomi National Polar-orbiting Partnership (SNPP) satellite is a total power radiometer and scans across the track within a range of ±52.77° from nadir. It has 22 channels and measures the microwave radiation at either quasi-vertical or quasi-horizontal polarization from the Earth's atmosphere. The ATMS sensor data record algorithm employed a commonly used two-point calibration equation that derives the earth-view brightness temperature directly from the counts and temperatures of warm target and cold space, and the earth-scene count. This equation is only valid under Rayleigh-Jeans (RJ) approximation. Impacts of RJ approximation on ATMS calibration biases are evaluated in this study. It is shown that the RJ approximation used in ATMS radiometric calibration results in errors on the order of 1-2 K. The error is also scene count dependent and increases with frequency.

  9. Preliminary algorithm for retrieving Sea Ice Concentration from the Microwave Radiometer on SAC-D/Aquarius

    NASA Astrophysics Data System (ADS)

    Masuelli, S.; Tauro, C.; Salgado, H.; Jones, L.

    2011-12-01

    This paper presents the first version of the algorithm to estimate Sea Ice Concentration from brightness temperatures measured by the MWR (MicroWave Radiometer) on board of SAC-D/Aquarius satellite, launched in June 2011. The MWR is a three channel microwave radiometer, 23.8GHz (H-pol) and 36.5GHz (V-pol and H-pol), with 8 beams for channel of about 50 km in size. The corresponding 8 horns of each channel are in a pushbroom configuration with two different incident angles: 52° and 58°. The algorithm for ice estimation presented here is based on the Bootstrap and Nasa Team (NT) ones, that use gradient and polarization ratios of the obtained brightness temperatures for their calculations. Usually these algorithms use the band of 19GHz for calculating the polarization ratio (PR), while for the gradient ratio (GR) use 37GHz and 19GHz in V-pol, and additionally other bands such as 23GHz and 85GHz are used as clime filters to improve the accuracy of the estimations obtained. In this way they obtain a distribuition of data for polar areas very similar to a triangle in a PR vs GR plot where it is possible to estimate not only the ice concentration but also classify the ice type. For the MWR we adapted this idea to the characteristics of the sensor. We use the 36.5GHz channel for calculating PR and 36.5GHz and 23.8GHz in H-pol for calculating GR. The combination of those MWR data produces a (PR,GR) distribution very noisy as we could verified using Windsat data and comparing the obtained (PR,GR) plots using NT and our definition of these quantities. As the 23.8GHz and 36.5 GHz bands are very sensitives to water vapor variation and sea roughness respectively, the use combined of these bands is very sensitive to both environmental variables. To reduce this effect we develop our algorithm as auto calibrated one. We summarized the way as the algorithm is applied to each beam: 1) We make a scatter plot in a PR-GR diagram with the data of one day corresponding to higher

  10. Evaluation of geophysical parameters measured by the Nimbus-7 microwave radiometer for the TOGA Heat Exchange Project

    NASA Technical Reports Server (NTRS)

    Liu, W. Timothy; Mock, Donald R.

    1986-01-01

    The data distributed by the National Space Science Data Center on the Geophysical parameters of precipitable water, sea surface temperature, and surface-level wind speed, measured by the Scanning Multichannel Microwave Radiometer (SMMR) on Nimbus-7, are evaluated with in situ measurements between Jan. 1980 and Oct. 1983 over the tropical oceans. In tracking annual cycles and the 1982-83 E1 Nino/Southern Oscillation episode, the radiometer measurements are coherent with sea surface temperatures and surface-level wind speeds measured at equatorial buoys and with precipitable water derived from radiosonde soundings at tropical island stations. However, there are differences between SMMR and in situ measurements. Corrections based on radiosonde and ship data were derived supplementing correction formulae suggested in the databook. This study is the initial evaluation of the data for quantitative description of the 1982-83 E1 Nino/Southern Oscillation episode. It paves the way for determination of the ocean-atmosphere moisture and latent heat exchanges, a priority of the Tropical Ocean and Global Atmosphere (TOGA) Heat Exchange Program.

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

    PubMed

    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

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

    PubMed Central

    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

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

    NASA Astrophysics Data System (ADS)

    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

  14. Rainfall estimation over oceans from scanning multichannel microwave radiometer and special sensor microwave/imager microwave data

    NASA Technical Reports Server (NTRS)

    Prabhakara, C.; Dalu, G.; Liberti, G. L.; Nucciarone, J. J.; Suhasini, R.

    1991-01-01

    The brightness temperature (T sub b) measured at 37 GHz shows fairly strong emission from rain, and only slight effects caused by scattering by ice above the rain clouds. At frequencies below 37 GHz, were the fov is larger and the volume extinction coefficient is weaker, it is found that the observations do not yield appreciable additional information about rain. At 85 GHz (fov = 15 km), where the volume extinction is considerably larger, direct information about rain below the clouds is usually masked. Based on the above ideas, 37 GHz observations with a 30 km fov from SMMR and SSM/I are selected to develop an empirical method for the estimation of rain rate. In this method, the statistics of the observed T sub b's at 37 GHz in a rain storm are related to the rain rate statistics in that storm. The underestimation of rain rate, arising from the inability of the radiometer to respond sensitively to rain rate above a given threshold, is rectified in this technique with the aid of two parameters that depend on the total water vapor content in the atmosphere. The retrieved rain rates compare favorably with radar observations and monthly mean global maps of rain derived from this technique over the oceans.

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

    NASA Astrophysics Data System (ADS)

    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

  16. Design studies of large aperture, high-resolution Earth science microwave radiometers compatible with small launch vehicles

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    High-spatial-resolution microwave radiometer sensing from space with reasonable swath widths and revisit times favors large aperture systems. However, with traditional precision antenna design, the size and weight requirements for such systems are in conflict with the need to emphasize small launch vehicles. This paper describes tradeoffs between the science requirements, basic operational parameters, and expected sensor performance for selected satellite radiometer concepts utilizing novel lightweight compactly packaged real apertures. Antenna, feed, and radiometer subsystem design and calibration are presented. Preliminary results show that novel lightweight real aperture coupled with state-of-the-art radiometer designs are compatible with small launch systems, and hold promise for high-resolution earth science measurements of sea ice, precipitation, soil moisture, sea surface temperature, and ocean wind speeds.

  17. HMMR (High-Resolution Multifrequency Microwave Radiometer) Earth observing system, volume 2e. Instrument panel report

    NASA Technical Reports Server (NTRS)

    1987-01-01

    Recommendations and background are provided for a passive microwave remote sensing system of the future designed to meet the observational needs of Earth scientist in the next decade. This system, called the High Resolution Multifrequency Microwave Radiometer (HMMR), is to be part of a complement of instruments in polar orbit. Working together, these instruments will form an Earth Observing System (EOS) to provide the information needed to better understand the fundamental, global scale processes which govern the Earth's environment. Measurements are identified in detail which passive observations in the microwave portion of the spectrum could contribute to an Earth Observing System in polar orbit. Requirements are established, e.g., spatial and temporal resolution, for these measurements so that, when combined with the other instruments in the Earth Observing System, they would yield a data set suitable for understanding the fundamental processes governing the Earth's environment. Existing and/or planned sensor systems are assessed in the light of these requirements, and additional sensor hardware needed to meet these observational requirements are defined.

  18. TRMM Microwave Radiometer Rain Rate Estimation Method with Convective and Stratiform Discrimination

    NASA Technical Reports Server (NTRS)

    Prabhakara, Cuddapah; Iacovazzi, R.; Weinman, J. A.; Dalu, G.; Einaudi, Franco (Technical Monitor)

    2000-01-01

    Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) radiometer brightness temperature data in the 85 GHz channel (T85) reveal distinct local minima (T85min) in a regional map containing a Mesoscale Convective System (MCS). A map of surface rain rate for that region, deduced from simultaneous measurements made by the Precipitation Radar (PR) on board the TRMM satellite, reveals that these T85min, produced by scattering, correspond to local PR rain maxima. Utilizing the PR rain rate map as a guide, we have developed a TMI algorithm to retrieve convective and stratiform rain. In this algorithm, two parameters are used to classify three kinds of thunderstorms (Cbs) based on the T85 data: a) the magnitude of scattering depression deduced from local T85mi, and b) the mean horizontal gradient of T85 around such minima. Initially, the algorithm is optimized or tuned utilizing the PR and TMI data of a few MCS events. The areal distribution of light (1-10 mm/hr), moderate (10-20 mm/hr), and intense (greater than or equal to 20 mm/hr) rain rates are retrieved on the average with an accuracy of about 15%. Taking advantage of this ability of our retrieval method, one could derive the latent heat input into the atmosphere over the 760 km wide swath of the TMI radiometer in the tropics.

  19. Wind Retrievals under Rain for Passive Satellite Microwave Radiometers and its Applications to Hurricane Tracking

    NASA Technical Reports Server (NTRS)

    Meissner, Thomas; Wentz, Frank J.

    2008-01-01

    We have developed an algorithm that retrieves wind speed under rain using C-hand and X-band channels of passive microwave satellite radiometers. The spectral difference of the brightness temperature signals due to wind or rain allows to find channel combinations that are sufficiently sensitive to wind speed but little or not sensitive to rain. We &ve trained a statistical algorithm that applies under hurricane conditions and is able to measure wind speeds in hurricanes to an estimated accuracy of about 2 m/s. We have also developed a global algorithm, that is less accurate but can be applied under all conditions. Its estimated accuracy is between 2 and 5 mls, depending on wind speed and rain rate. We also extend the wind speed region in our model for the wind induced sea surface emissivity from currently 20 m/s to 40 mls. The data indicate that the signal starts to saturate above 30 mls. Finally, we make an assessment of the performance of wind direction retrievals from polarimetric radiometers as function of wind speed and rain rate

  20. Global Climate Monitoring with the EOS PM-Platform's Advanced Microwave Scanning Radiometer (AMSR-E)

    NASA Technical Reports Server (NTRS)

    Spencer, Roy W.

    2002-01-01

    The Advanced Microwave Scanning 2 Radiometer (AMSR-E) is being built by NASDA to fly on NASA's PM Platform (now called Aqua) in December 2000. This is in addition to a copy of AMSR that will be launched on Japan's ADEOS-II satellite in 2001. The AMSRs improve upon the window frequency radiometer heritage of the SSM/I and SMMR instruments. Major improvements over those instruments include channels spanning the 6.9 GHz to 89 GHz frequency range, and higher spatial resolution from a 1.6 m reflector (AMSR-E) and 2.0 m reflector (ADEOS-II AMSR). The ADEOS-II AMSR also will have 50.3 and 52.8 GHz channels, providing sensitivity to lower tropospheric temperature. NASA funds an AMSR-E Science Team to provide algorithms for the routine production of a number of standard geophysical products. These products will be generated by the AMSR-E Science Investigator-led Processing System (SIPS) at the Global Hydrology Resource Center (GHRC) in Huntsville, Alabama. While there is a separate NASDA-sponsored activity to develop algorithms and produce products from AMSR, as well as a Joint (NASDA-NASA) AMSR Science Team 3 activity, here I will review only the AMSR-E Team's algorithms and how they benefit from the new capabilities that AMSR-E will provide. The US Team's products will be archived at the National Snow and Ice Data Center (NSIDC).

  1. TOPEX Microwave Radiometer - Thermal design verification test and analytical model validation

    NASA Technical Reports Server (NTRS)

    Lin, Edward I.

    1992-01-01

    The testing of the TOPEX Microwave Radiometer (TMR) is described in terms of hardware development based on the modeling and thermal vacuum testing conducted. The TMR and the vacuum-test facility are described, and the thermal verification test includes a hot steady-state segment, a cold steady-state segment, and a cold survival mode segment totalling 65 hours. A graphic description is given of the test history which is related temperature tracking, and two multinode TMR test-chamber models are compared to the test results. Large discrepancies between the test data and the model predictions are attributed to contact conductance, effective emittance from the multilayer insulation, and heat leaks related to deviations from the flight configuration. The TMR thermal testing/modeling effort is shown to provide technical corrections for the procedure outlined, and the need for validating predictive models is underscored.

  2. A synthetic aperture microwave radiometer to measure soil moisture and ocean salinity from space

    NASA Technical Reports Server (NTRS)

    Le Vine, D. M.; Hilliard, L. M.; Swift, C. T.; Ruf, C. S.; Garrett, L. B.

    1991-01-01

    A concept is presented for a microwave radiometer in space to measure soil moisture and ocean salinity as part of an 'Earth Probe' mission. The measurements could be made using an array of stick antennas. The L-band channel (1.4 GHz) would be the primary channel for determining soil moisture, with the S-band (2.65-GHz) and C-band (5.0-GHz) channels providing ancillary information to help correct for the effects of the vegetation canopy and possibly to estimate a moisture profile. A preliminary study indicates that an orbit at 450 km would provide coverage of better than 95 percent of the earth every 3 days. A 10-km resolution cell (at nadir) requires stick antennas about 9.5-m long at L-band. The S-band and C-band sticks would be substantially shorter (5 m and 2.7 m, respectively).

  3. The correction of aberrations computed in the aperture plane of multifrequency microwave radiometer antennas

    NASA Technical Reports Server (NTRS)

    Schmidt, R. F.

    1984-01-01

    An analytical/numerical approach to identifying and correcting the aberrations introduced by a general displacement of the feed from the focal point of a single offset paraboloid antenna used in deployable radiometer systems is developed. A 15 meter reflector with 18 meter focal length is assumed for the analysis, which considers far field radiation pattern quality, focal region fields, and aberrations appearing in the aperture plane. The latter are obtained by ray tracing in the transmit mode and are expressed in terms of optical notation. Attention is given to the physical restraints imposed on corrective elements by real microwave systems and to the intermediate near field aspects of the problem in three dimensions. The subject of wave fronts and caustics in the receive mode is introduced for comparative purposes. Several specific examples are given for aberration reduction at eight beamwidths of scan at a frequency of 1.414 GHz.

  4. Observations of oceanic surface-wind fields from the Nimbus-7 microwave radiometer

    NASA Technical Reports Server (NTRS)

    Miller, J. R.; Geyser, J. E.; Chang, A. T. C.; Wilheit, T. T., Jr.

    1982-01-01

    Brightness temperatures from the five-frequency dual-polarized scanning multichannel microwave radiometer (SMMR) on Nimbus 7 have been used to obtain surface wind fields over the ocean. The satellite-derived wind field for 1200Z, Feb. 19, 1979, in the eastern North Pacific has been compared with an operationally generated surface-wind analysis field. Previous point comparisons at selected locations have indicated that satellite winds are accurate to 3 m/sec. The results, although of a preliminary nature, indicate that SMMR-derived winds may be used to determine large-scale wind fields over the ocean, particularly in areas of strong wind gradients such as found in cyclonic systems.

  5. Aquarius L-Band Microwave Radiometer: Three Years of Radiometric Performance and Systematic Effects

    NASA Technical Reports Server (NTRS)

    Piepmeier, Jeffrey R.; Hong, Liang; Pellerano, Fernando A.

    2015-01-01

    The Aquarius L-band microwave radiometer is a three-beam pushbroom instrument designed to measure sea surface salinity. Results are analyzed for performance and systematic effects over three years of operation. The thermal control system maintains tight temperature stability promoting good gain stability. The gain spectrum exhibits expected orbital variations with 1f noise appearing at longer time periods. The on-board detection and integration scheme coupled with the calibration algorithm produce antenna temperatures with NEDT 0.16 K for 1.44-s samples. Nonlinearity is characterized before launch and the derived correction is verified with cold-sky calibration data. Finally, long-term drift is discovered in all channels with 1-K amplitude and 100-day time constant. Nonetheless, it is adeptly corrected using an exponential model.

  6. A conceptual design of a large aperture microwave radiometer geostationary platform

    NASA Technical Reports Server (NTRS)

    Garn, Paul A.; Garrison, James L.; Jasinski, Rachel

    1992-01-01

    A conceptual design of a Large Aperture Microwave Radiometer (LAMR) Platform has been developed and technology areas essential to the design and on-orbit viability of the platform have been defined. Those technologies that must be developed to the requirement stated here for the LAMR mission to be viable include: advanced radiation resistant solar cells, integrated complex structures, large segmented reflector panels, sub 3 kg/m(exp 2) areal density large antennas, and electric propulsion systems. Technology areas that require further development to enhance the capabilities of the LAMR platform (but are not essential for viability) include: electrical power storage, on-orbit assembly, and on-orbit systems checkout and correction.

  7. Geosynchronous Microwave Atmospheric Sounding Radiometer (MASR) antenna feasibility study. Volume 3: Antenna feasibility

    NASA Technical Reports Server (NTRS)

    Villeneuve, A. T.

    1978-01-01

    Antenna systems capable of operating with a multichannel microwave radiometer intended for mapping severe storm activity over patches on the surface of the earth 750 km square were compared. These systems included a paraboloidal reflector with an offset focal point feed, and a symmetrical Cassegrain reflector system. Both systems are acceptable from the point of view of beam efficiency, however, from the point of view of maintaining the required positional accuracies and surface tolerances, as well as from the point of view of manufacturability, cost effectiveness, and technical risk, the symmetrical Casegrain was selected as the preferred configuration. Performance characteristics were calculated and a mechanical design study was conducted to provide estimates of the technical risk, costs, and development time required for the construction of such an antenna system.

  8. Topical cyclone rainfall characteristics as determined from a satellite passive microwave radiometer

    NASA Technical Reports Server (NTRS)

    Rodgers, E. B.; Adler, R. F.

    1979-01-01

    Data from the Nimbus-5 Electrically Scanning Microwave Radiometer (ESMR-5) were used to calculate latent heat release and other rainfall parameters for over 70 satellite observations of 21 tropical cyclones in the tropical North Pacific Ocean. The results indicate that the ESMR-5 measurements can be useful in determining the rainfall characteristics of these storms and appear to be potentially useful in monitoring as well as predicting their intensity. The ESMR-5 derived total tropical cyclone rainfall estimates agree favorably with previous estimates for both the disturbance and typhoon stages. The mean typhoon rainfall rate (1.9 mm h(-1)) is approximately twice that of disturbances (1.1 mm h(-1)).

  9. The correction of aberrations computed in the aperture plane of multifrequency microwave radiometer antennas

    NASA Astrophysics Data System (ADS)

    Schmidt, R. F.

    1984-05-01

    An analytical/numerical approach to identifying and correcting the aberrations introduced by a general displacement of the feed from the focal point of a single offset paraboloid antenna used in deployable radiometer systems is developed. A 15 meter reflector with 18 meter focal length is assumed for the analysis, which considers far field radiation pattern quality, focal region fields, and aberrations appearing in the aperture plane. The latter are obtained by ray tracing in the transmit mode and are expressed in terms of optical notation. Attention is given to the physical restraints imposed on corrective elements by real microwave systems and to the intermediate near field aspects of the problem in three dimensions. The subject of wave fronts and caustics in the receive mode is introduced for comparative purposes. Several specific examples are given for aberration reduction at eight beamwidths of scan at a frequency of 1.414 GHz.

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

    NASA Astrophysics Data System (ADS)

    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.

  11. The Effect of Sea-Surface Sun Glitter on Microwave Radiometer Measurements

    NASA Technical Reports Server (NTRS)

    Wentz, F. J.

    1981-01-01

    A relatively simple model for the microwave brightness temperature of sea surface Sun glitter is presented. The model is an accurate closeform approximation for the fourfold Sun glitter integral. The model computations indicate that Sun glitter contamination of on orbit radiometer measurements is appreciable over a large swath area. For winds near 20 m/s, Sun glitter affects the retrieval of environmental parameters for Sun angles as large as 20 to 25 deg. The model predicted biases in retrieved wind speed and sea surface temperature due to neglecting Sun glitter are consistent with those experimentally observed in SEASAT SMMR retrievals. A least squares retrieval algorithm that uses a combined sea and Sun model function shows the potential of retrieving accurate environmental parameters in the presence of Sun glitter so long as the Sun angles and wind speed are above 5 deg and 2 m/s, respectively.

  12. Inversion Algorithms for Water Vapor Radiometers Operating at 20.7 and 31.4 Ghz

    NASA Technical Reports Server (NTRS)

    Resch, G. M.

    1984-01-01

    Eight water vapor radiometers (WVRs) were constructed as research and development tools to support the Advanced System Programs in the Deep Space Network and the Crustal Dynamics Project. These instruments are intended to operate at the stations of the Deep Space Network (DSN), various radio observatories, and obile facilities that participate in very long baseline interferometric (VLBI) experiments. It is expected that the WVRs will operate in a wide range of meteorological conditions. Several algorithms are discussed that are used to estimate the line-of-sight path delay due to water vapor and columnar liquid water rom the observed microwave brightness temperatures provided by the WVRs. In particular, systematic effects due to site and seasonal variations are examined. The accuracy of the estimation as indicated by a simulation calculation is approximately 0.3 cm for a noiseless WVR in clear and moderately cloudy weather. With a realistic noise model of WVR behavior, the inversion accuracy is approximately 0.6 cm.

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

    NASA Astrophysics Data System (ADS)

    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

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

    NASA Technical Reports Server (NTRS)

    Harrington, R. F.

    1980-01-01

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

  15. Ice Water Path Retrieval Using Microwave and Submillimetre Wave Observations

    NASA Astrophysics Data System (ADS)

    Brath, Manfred; Grützun, Verena; Mendrok, Jana; Fox, Stuart; Eriksson, Patrick; Buehler, Stefan A.

    2016-04-01

    There is an ongoing need for data on ice clouds. The ice water path as an essential climate variable is a fundamental parameter to describe ice clouds. Combined passive microwave and submillimetre wave measurements are capable to sample the size distribution of the ice particles and are sensitive to relevant particle sizes. This makes combined microwave and submillimetre wave measurements useful for estimates of ice water path. Furthermore, instead of being sensitive for the upper ice column as for example for passive visible and passive infrared measurements, combined microwave and submillimetre wave measurements can sample the full ice column. We developed a retrieval algorithm for ice water path based on a neural network approach using combined microwave and submillimetre wave measurements, from about 20 channels in the range between 89 GHz and 664 GHz of the electromagnetic sprectra. We trained a neural network by using 1D radiative transfer simulations which were conducted using the Atmospheric Radiative Transfer Simulator (ARTS). The radiative transfer simulations were fed by atmospheric profiles from a numerical weather prediction model. We will present an analysis of the retrieval. Additionally, we will present results of retrieved IWP from combined ISMAR (International SubMillimetre Airborne Radiometer) and MARSS (Microwave Airborne Radiometer Scanning System) measurements on board of the Facility for Airborne Atmospheric Measurements (FAAM) aircraft during March 2015 over the North Atlantic.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    Remote sensing of snow mass remains a challenging area of research. Scattering of electromagnetic radiation is sensitive to snow mass, but is also affected by contrasts in the dielectric properties of the snow. Although the argument that errors from simple algorithms average out at large scales has been used to justify current retrieval methods, it is not obvious why this should be the case. This hypothesis needs to be tested more rigorously. A ground-based field experiment was carried out to assess the impact of sub-footprint snow heterogeneity on microwave brightness temperature, in Churchill, Canada in winter in early 2010. Passive microwave measurements of snow were made using sled-mounted radiometers at 75cm intervals over a 5m transect. Measurements were made at horizontal and vertical polarizations at frequencies of 19 and 37 GHz. Snow beneath the radiometer footprints was subsequently excavated, creating a snow trench wall along the centrepoints of adjacent footprints. The trench wall was carefully smoothed and photographed with a near-infrared camera in order to determine the positions of stratigraphic snow layer boundaries. Three one-dimensional vertical profiles of snowpack properties (density and snow specific surface area) were taken at 75cm, 185cm and 355cm from the left hand side of the trench. These profile measurements were used to derive snow density and grain size for each of the layers identified from the NIR image. Microwave brightness temperatures for the 2-dimensional map of snow properties was simulated with the Helsinki University of Technology (HUT) model at 1cm intervals horizontally across the trench. Where each of five ice lenses was identified in the snow stratigraphy, a decrease in brightness temperature was simulated. However, the median brightness temperature simulated across the trench was substantially higher than the observations, of the order of tens of Kelvin, dependent on frequency and polarization. In order to understand and

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

    NASA Technical Reports Server (NTRS)

    Johnson, Benjamin T.; Petty, Grant W.; Skofronick-Jackson, Gail

    2012-01-01

    A simplied framework is presented for assessing the qualitative sensitivities of computed microwave properties, satellite brightness temperatures, and radar reflectivities to assumptions concerning the physical properties of ice-phase hydrometeors. Properties considered included the shape parameter of a gamma size distribution andthe melted-equivalent mass median diameter D0, the particle density, dielectric mixing formula, and the choice of complex index of refraction for ice. We examine these properties at selected radiometer frequencies of 18.7, 36.5, 89.0, and 150.0 GHz; and radar frequencies at 2.8, 13.4, 35.6, and 94.0 GHz consistent with existing and planned remote sensing instruments. Passive and active microwave observables of ice particles arefound to be extremely sensitive to the melted-equivalent mass median diameter D0 ofthe size distribution. Similar large sensitivities are found for variations in the ice vol-ume fraction whenever the geometric mass median diameter exceeds approximately 1/8th of the wavelength. At 94 GHz the two-way path integrated attenuation is potentially large for dense compact particles. The distribution parameter mu has a relatively weak effect on any observable: less than 1-2 K in brightness temperature and up to 2.7 dB difference in the effective radar reflectivity. Reversal of the roles of ice and air in the MaxwellGarnett dielectric mixing formula leads to a signicant change in both microwave brightness temperature (10 K) and radar reflectivity (2 dB). The choice of Warren (1984) or Warren and Brandt (2008) for the complex index of refraction of ice can produce a 3%-4% change in the brightness temperature depression.

  18. Passive Microwave Observation of Soil Water Infiltration

    NASA Technical Reports Server (NTRS)

    Jackson, Thomas J.; Schmugge, Thomas J.; Rawls, Walter J.; ONeill, Peggy E.; Parlange, Marc B.

    1997-01-01

    Infiltration is a time varying process of water entry into soil. Experiments were conducted here using truck based microwave radiometers to observe small plots during and following sprinkler irrigation. Experiments were conducted on a sandy loam soil in 1994 and a silt loam in 1995. Sandy loam soils typically have higher infiltration capabilities than clays. For the sandy loam the observed brightness temperature (TB) quickly reached a nominally constant value during irrigation. When the irrigation was stopped the TB began to increase as drainage took place. The irrigation rates in 1995 with the silt loam soil exceeded the saturated conductivity of the soil. During irrigation the TB values exhibited a pattern that suggests the occurrence of coherent reflection, a rarely observed phenomena under natural conditions. These results suggested the existence of a sharp dielectric boundary (wet over dry soil) that was increasing in depth with time.

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  20. Global Climate Monitoring with the Eos Pm-Platform's Advanced Microwave Scanning Radiometer (AMSR-E)

    NASA Technical Reports Server (NTRS)

    Spencer, Roy W.

    2000-01-01

    The Advanced Microwave Scanning Radiometer (AMSR-E) is being built by NASDA to fly on NASA's PM Platform (now called "Aqua") in December 2000. This is in addition to a copy of AMSR that will be launched on Japan's ADEOS-11 satellite in 2001. The AMSRs improve upon the window frequency radiometer heritage of the SSM[l and SMMR instruments. Major improvements over those instruments include channels spanning the 6.9 GHz to 89 GHz frequency range, and higher spatial resolution from a 1.6 m reflector (AMSR-E) and 2.0 m reflector (ADEOS-11 AMSR). The ADEOS-11 AMSR also will have 50.3 and 52.8 GHz channels, providing sensitivity to lower tropospheric temperature. NASA funds an AMSR-E Science Team to provide algorithms for the routine production of a number of standard geophysical products. These products will be generated by the AMSR-E Science Investigator-led Processing System (SIPS) at the Global Hydrology Resource Center (GHRC) in Huntsville, Alabama. While there is a separate NASDA-sponsored activity to develop algorithms and produce products from AMSR, as well as a Joint (NASDA-NASA) AMSR Science Team activity, here I will review only the AMSR-E Team's algorithms and how they benefit from the new capabilities that AMSR-E will provide. The U.S. Team's products will be archived at the National Snow and Ice Data Center (NSIDC). Further information about AMSR-E can be obtained at http://www.jzhcc.msfc.nasa.Vov/AMSR.

  1. Tropical Rainfall Measuring Mission (TRMM) project. VI - Spacecraft, scientific instruments, and launching rocket. Part 3 - The electrically Scanning Microwave Radiometer and the Special Sensor Microwave/Imager

    NASA Technical Reports Server (NTRS)

    Wilheit, Thomas T.; Yamasaki, Hiromichi

    1990-01-01

    The two microwave radiometers for TRMM are designed to measure thermal microwave radiation upwelling from the earth. The Electrically Scanning Microwave Radiometer (ESMR) scans from 50 deg to the left through nadir to 50 deg to the right in 78 steps with no moving mechanical parts in a band centered at 19.35 GHz. The TRMM concept uses the radar to develop a climatology of rain-layer thickness which can be used for the interpretation of the radiometer data over a swath wider than the radar. The ESMR data are useful for estimating rain intensity only over an ocean background. The Special Sensor Microwave/Imager (SSM/I), which scans conically with three dual polarized channels at 19, 37, and 85 GHz and a single polarized channel at 22 GHz, provides a wider range of rainfall intensities. The SSM/I spins about an axis parallel to the local spacecraft vector and 128 uniformly spaced samples of the 85 GHz data are taken on each scan over a 112-deg scan region simultaneously with 64 samples of the other frequencies.

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

    NASA Astrophysics Data System (ADS)

    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

  3. Preliminary results from the COBE differential microwave radiometers - Large angular scale isotropy of the cosmic microwave background

    NASA Technical Reports Server (NTRS)

    Smoot, G. F.; Aymon, J.; Bennett, C. L.; Kogut, A.; Backus, C.

    1991-01-01

    Preliminary but precise micowave maps are presented of the sky, and thus of the early universe, derived as the first results from the Differential Microwave Radiometers experiment aboard COBE. The dipole anisotropy attributed to the motion of the solar system with respect to the CMB reference frame shows strongly in all six sky maps and is consistent with a Doppler-shifted thermal spectrum. The best-fitted dipole has amplitude 3.3 + or - 0.2 mK in the direction (alpha, delta) = 11.2 h + or - 0.2 h, -7 deg + or - 2 deg (J2000) or (l,b) = 265 deg + or - 2 deg, 48 deg + or - 2 deg. There is no clear evidence in the maps for any other large angular-scale feature. Limits on Delta T/T0 of 3 x 10 to the -5th (T0 = 2.735 K), 4 x 10 to the -5th, and 4 x 10 to the -5th are found for the rms quadrupole amplitude, monochromatic fluctuations, and Gaussian fluctuations, respectively. These measurements place the most severe constraints to date on many potential physical processes in the early universe.

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

    NASA Astrophysics Data System (ADS)

    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

  5. Variations in the Nimbus-7 scanning multichannel microwave radiometer cold reference antenna signals and temperatures during two orbital periods

    NASA Technical Reports Server (NTRS)

    Gloersen, P.; Cavalieri, D. J.; Soule, H. V.

    1980-01-01

    The observed effects of solar radiance on the Nimbus 7 scanning multichannel microwave radiometer (SMMR) cold reference signal are discussed. Unexpected diurnal responses in this signal sometimes larger than the typical cold reference signal resulted from acquisition of the solar disc. Solar heating of the SMMR components as a function of orbital locations was correlated with the cold reference radiances for two sets of sequential orbit six months apart.

  6. Validation and Further Development of HUT Snow Emission Model for Satellite Microwave Radiometer Data Inversion and Assimilation

    NASA Astrophysics Data System (ADS)

    Pulliainen, J.; Kontu, A.; Lemmetyinen, J.; Takala, M.; Luojus, K.

    2008-12-01

    Global mapping of terrestrial snow cover and sea ice is an important application area for space-borne microwave radiometry. The algorithms applied e.g. for estimating snow water equivalent (SWE) oare typically empirical formulas obtained by data delineation or by fitting a regression model to brightness temperatures simulated by a physical forward model. On the other hand, algorithms based on the inversion of a forward brightness temperature model have been also applied. In all cases, an essential factor determining the performance of inversion algorithms or giving information on the validity of empirical approaches is the accuracy of forward brightness temperature modelling. The techniques used for modeling the brightness temperature of snow pack are typically based on the radiative transfer equation. In semi-empirical approaches, some simplifications are made to avoid numerical integration, which enables the use of forward models e.g. in iterative inversion algorithms. Relevant semi- empirical models include the HUT snow emission model and the MEMLS model. They consider snow pack as a single layer (HUT model) or as a multi-layer structure (MEMLS). In practice, the use of any model with space-borne or airborne radiometer data requires that snow ground-interactions as well as influence of vegetation and atmosphere have to be considered. This significantly complicates the modeling task. The HUT snow emission model was developed in 1998 to describe the microwave brightness temperature of snow covered forested terrain. Revisions to improve the consideration of snow extinction coefficient have been made in recent years by different research groups. The model treats different emission contributions and their interactions with simple analytical formulas that are derived either through empirical or semi- theoretical considerations. As the model is relatively simple, it can be used for the inversion of space-borne data in the estimation of quantitative snow pack

  7. Microwave backscatter and emission observed from Shuttle Imaging Radar B and an airborne 1.4 GHz radiometer

    NASA Technical Reports Server (NTRS)

    Wang, J. R.; Schiue, J. C.; Schmugge, T. J.; Engman, E. T.; Mo, T.; Lawrence, R. W.

    1985-01-01

    A soil moisture experiment conducted with the Shuttle Imaging Radar B (SIR-B) is reported. SIR-B operated at 1.28 GHz provided the active microwave measurements, while a 4-beam pushbroom 1.4 GHz radiometer gave the complementary passive microwave measurements. The aircraft measurements were made at an altitude of 330 m, resulting in a ground resolution cell of about 100 m diameter. SIR-B ground resolution from 225 km was about 35 m. More than 150 agricultural fields in the San Joaquin Valley of California were examined in the experiment. The effect of surface roughness height on radar backscatter and radiometric measurements was studied.

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

    NASA Technical Reports Server (NTRS)

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

    SciTech Connect

    Lineweaver, C.H. |

    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 {approximately}20{degree} 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 > 9{sigma}, > 10{sigma} and > 18{sigma} 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{degree} due to the 60{degree} separation of the DMR horns. The mean covariance of 60{degree} is 0.45%{sub {minus}0.14}{sup +0.18} 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.

  10. Snow stratigraphic heterogeneity within ground-based passive microwave radiometer footprints: Implications for emission modeling

    NASA Astrophysics Data System (ADS)

    Rutter, Nick; Sandells, Mel; Derksen, Chris; Toose, Peter; Royer, Alain; Montpetit, Benoit; Langlois, Alex; Lemmetyinen, Juha; Pulliainen, Jouni

    2014-03-01

    Two-dimensional measurements of snowpack properties (stratigraphic layering, density, grain size, and temperature) were used as inputs to the multilayer Helsinki University of Technology (HUT) microwave emission model at a centimeter-scale horizontal resolution, across a 4.5 m transect of ground-based passive microwave radiometer footprints near Churchill, Manitoba, Canada. Snowpack stratigraphy was complex (between six and eight layers) with only three layers extending continuously throughout the length of the transect. Distributions of one-dimensional simulations, accurately representing complex stratigraphic layering, were evaluated using measured brightness temperatures. Large biases (36 to 68 K) between simulated and measured brightness temperatures were minimized (-0.5 to 0.6 K), within measurement accuracy, through application of grain scaling factors (2.6 to 5.3) at different combinations of frequencies, polarizations, and model extinction coefficients. Grain scaling factors compensated for uncertainty relating optical specific surface area to HUT effective grain size inputs and quantified relative differences in scattering and absorption properties of various extinction coefficients. The HUT model required accurate representation of ice lenses, particularly at horizontal polarization, and large grain scaling factors highlighted the need to consider microstructure beyond the size of individual grains. As variability of extinction coefficients was strongly influenced by the proportion of large (hoar) grains in a vertical profile, it is important to consider simulations from distributions of one-dimensional profiles rather than single profiles, especially in sub-Arctic snowpacks where stratigraphic variability can be high. Model sensitivity experiments suggested that the level of error in field measurements and the new methodological framework used to apply them in a snow emission model were satisfactory. Layer amalgamation showed that a three

  11. The New Version of Brightness Temperature Product of Microwave Radiometer AMSR2 onboard GCOM-W1 Satellite

    NASA Astrophysics Data System (ADS)

    Maeda, Takashi; Imaoka, Keiji; Kasahara, Marehito

    2015-04-01

    The Japan Aerospace Exploration Agency (JAXA) launched the GCOM-W1 (Global Change Observation Mission 1st - Water) satellite on 17 May 2012 (UT). The main mission of the GCOM-W1 satellite is to monitor the global water cycle, for which it has onboard the Advanced Microwave Scanning Radiometer-2 (AMSR2). The AMSR2 has multifrequency microwave receivers, and like many other satellite-borne microwave radiometers currently in orbit, its multifrequency feedhorns share a single rotating antenna dish. Because AMSR2 is designed to make a sharp antenna beam for each frequency, the FOV (field of view) size of each frequency differs substantially from one another: the higher the frequency, the smaller the FOV size. Therefore, the multifrequency data (brightness temperature, TB) represent responses of areas quite different from one another, even if the multifrequency TB values are obtained by the same measurement. Lack of consideration of the difference in FOV sizes will be an important reason for the deterioration of the accuracy of geophysical values retrieved from multifrequency TB values. To solve this problem, we can consider to replicate a large FOV of low-target frequency by adequately summing small FOV of high-source frequency spreading within it. One way to achieve this is with the Backus-Gilbert (BG) method, and there have been many studies related to this issue. The BG method provides a way to calculate the intensities for small-source FOVs to replicate a large-target FOV as accurately as possible. TB values that correspond to source FOVs (source TB values) are averaged using these intensities as weighting coefficients. Thus, the TB synthesized from the source TB values, i.e., the weighted mean of the source TB values becomes equivalent to the source frequency's TB measured by a target FOV. The source frequency's synthesized TB and the target frequency's TB enable us to evaluate more accurately the difference in the microwave emission characteristics between the two

  12. Comments on the statistical analysis of excess variance in the COBE differential microwave radiometer maps

    NASA Astrophysics Data System (ADS)

    Wright, E. L.; Smoot, G. F.; Kogut, A.; Hinshaw, G.; Tenorio, L.; Lineweaver, C.; Bennett, C. L.; Lubin, P. M.

    1994-01-01

    Cosmic anisotrophy produces an excess variance sq sigmasky in the Delta maps produced by the Differential Microwave Radiometer (DMR) on cosmic background explorer (COBE) that is over and above the instrument noise. After smoothing to an effective resolution of 10 deg, this excess sigmasky(10 deg), provides an estimate for the amplitude of the primordial density perturbation power spectrum with a cosmic uncertainty of only 12%. We employ detailed Monte Carlo techniques to express the amplitude derived from this statistic in terms of the universal root mean square (rms) quadrupole amplitude, (Q sq/RMS)0.5. The effects of monopole and dipole subtraction and the non-Gaussian shape of the DMR beam cause the derived (Q sq/RMS)0.5 to be 5%-10% larger than would be derived using simplified analytic approximations. We also investigate the properties of two other map statistics: the actual quadrupole and the Boughn-Cottingham statistic. Both the sigmasky(10 deg) statistic and the Boughn-Cottingham statistic are consistent with the (Q sq/RMS)0.5 = 17 +/- 5 micro K reported by Smoot et al. (1992) and Wright et al. (1992).

  13. Evolution of Mesoscale Convective System over the South Western Peninsular India: Observations from Microwave Radiometer and Simulations using WRF

    NASA Astrophysics Data System (ADS)

    Uma, K. N.; Krishna Moorthy, K.; Sijikumar, S.; Renju, R.; Tinu, K. A.; Raju, Suresh C.

    2012-07-01

    Meso-scale Convective Systems (MCS) are important in view of their large cumulous build-up, vertical extent, short horizontal extent and associated thundershowers. The Microwave Radiometer Profiler (MRP) over the equatorial coastal station Thiruvanathapuram (Trivandrum, 8.55oN, 76.9oE), has been utilized to understand the genesis of Mesoscale convective system (MCS), that occur frequently during the pre-monsoon season. Examination of the measurement of relative humidity, temperature and cloud liquid water measurements, over the zenith and two scanning elevation angles (15o) viewing both over the land and the sea respectively revealed that the MCS generally originate over the land during early afternoon hours, propagate seawards over the observational site and finally dissipate over the sea, with accompanying rainfall and latent heat release. The simulations obtained using Advanced Research-Weather Research and Forecast (WRF-ARW) model effectively reproduces the thermodynamical and microphysical properties of the MCS. The time duration and quantity of rainfall obtained by the simulations also well compared with the observations. Analysis also suggests that wind shear in the upper troposphere is responsible for the growth and the shape of the convective cloud.

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

    NASA Astrophysics Data System (ADS)

    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

  15. A TRMM Microwave Radiometer Rain Rate Estimation Method with Convective and Stratiform Discrimination

    NASA Technical Reports Server (NTRS)

    Prabhakara, C.; Iacovazzi, R., Jr.; Weinman, J. A.; Dalu, G.

    1999-01-01

    Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) radiometer brightness temperature data in the 85 GHz channel (T85) reveal distinct local minima (T85min) in a regional map containing a Mesoscale Convective System (MCS). This is because of relatively small footprint size (approximately 5.5 km) and strong extinction properties in this channel of the TMI. A map of surface rain rate for that region, deduced from simultaneous measurements made by the Precipitation Radar (PR) on board the TRMM satellite, reveals that these T85(sub min), produced by scattering, correspond to local PR rain maxima. Utilizing the PR rain rate map as a guide, we infer empirically from TMI data the presence of three different kinds of thunderstorms or Cbs. These Cbs are classified as young, mature, and decaying types, and are assumed to have a scale of about 20 km on the average. Two parameters are used to classify these three kinds of Cbs based on the T85 data: a) the magnitude of scattering depression deduced from local T85(sub min) and b) the mean horizontal gradient of T85 around such minima. Knowing the category of a given Cb, we can estimate the rain rate associated with it. Such estimation is done with the help of relationships linking T85min to rain rate in each Cb type. Similarly, a weak background rain rate in all the areas where T85 is less than 260 K is deduced with another relationship linking T85 to rain rate. In our rain retrieval model, this background rain constitutes stratiform rain where the Cbs are absent. Initially, these relationships are optimized or tuned utilizing the PR and TMI data of a few MCS events. After such tuning, the model is applied to independent MCS cases. The areal distribution of light (1-10 mm/hr), moderate (10-20 mm/hr), and intense (>= 20 mm/hr) rain rates are retrieved satisfactorily. Accuracy in the estimates of the light, moderate, and intense rain areas and the mean rain rates associated with such areas in these independent MCS

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

    NASA Astrophysics Data System (ADS)

    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

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

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

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

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

    NASA Technical Reports Server (NTRS)

    McLinden, Matthew; Piepmeier, Jeffrey

    2013-01-01

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

  19. A Texture-Polarization Method for Estimating Convective/Stratiform Precipitation Area Coverage from Passive Microwave Radiometer Data

    NASA Technical Reports Server (NTRS)

    Olson, William S.; Hong, Ye; Kummerow, Christian D.; Turk, Joseph; Einaudi, Franco (Technical Monitor)

    2000-01-01

    Observational and modeling studies have described the relationships between convective/stratiform rain proportion and the vertical distributions of vertical motion, latent heating, and moistening in mesoscale convective systems. Therefore, remote sensing techniques which can quantify the relative areal proportion of convective and stratiform, rainfall can provide useful information regarding the dynamic and thermodynamic processes in these systems. In the present study, two methods for deducing the convective/stratiform areal extent of precipitation from satellite passive microwave radiometer measurements are combined to yield an improved method. If sufficient microwave scattering by ice-phase precipitating hydrometeors is detected, the method relies mainly on the degree of polarization in oblique-view, 85.5 GHz radiances to estimate the area fraction of convective rain within the radiometer footprint. In situations where ice scattering is minimal, the method draws mostly on texture information in radiometer imagery at lower microwave frequencies to estimate the convective area fraction. Based upon observations of ten convective systems over ocean and nine systems over land, instantaneous 0.5 degree resolution estimates of convective area fraction from the Tropical Rainfall Measuring Mission Microwave Imager (TRMM TMI) are compared to nearly coincident estimates from the TRMM Precipitation Radar (TRMM PR). The TMI convective area fraction estimates are slightly low-biased with respect to the PR, with TMI-PR correlations of 0.78 and 0.84 over ocean and land backgrounds, respectively. TMI monthly-average convective area percentages in the tropics and subtropics from February 1998 exhibit the greatest values along the ITCZ and in continental regions of the summer (southern) hemisphere. Although convective area percentages. from the TMI are systematically lower than those from the PR, monthly rain patterns derived from the TMI and PR rain algorithms are very similar

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

    NASA Technical Reports Server (NTRS)

    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.

  1. Spectroscopy underlying microwave remote sensing of atmospheric water vapor

    NASA Astrophysics Data System (ADS)

    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.

  2. Millimeter-wave Imaging Radiometer (MIR) data processing and development of water vapor retrieval algorithms

    NASA Technical Reports Server (NTRS)

    Chang, L. Aron

    1995-01-01

    This document describes the progress of the task of the Millimeter-wave Imaging Radiometer (MIR) data processing and the development of water vapor retrieval algorithms, for the second six-month performing period. Aircraft MIR data from two 1995 field experiments were collected and processed with a revised data processing software. Two revised versions of water vapor retrieval algorithm were developed, one for the execution of retrieval on a supercomputer platform, and one for using pressure as the vertical coordinate. Two implementations of incorporating products from other sensors into the water vapor retrieval system, one from the Special Sensor Microwave Imager (SSM/I), the other from the High-resolution Interferometer Sounder (HIS). Water vapor retrievals were performed for both airborne MIR data and spaceborne SSM/T-2 data, during field experiments of TOGA/COARE, CAMEX-1, and CAMEX-2. The climatology of water vapor during TOGA/COARE was examined by SSM/T-2 soundings and conventional rawinsonde.

  3. Millimeter-Wave Imaging Radiometer (MIR) Data Processing and Development of Water Vapor Retrieval Algorithms

    NASA Technical Reports Server (NTRS)

    Chang, L. Aron

    1998-01-01

    This document describes the final report of the Millimeter-wave Imaging Radiometer (MIR) Data Processing and Development of Water Vapor Retrieval Algorithms. Volumes of radiometric data have been collected using airborne MIR measurements during a series of field experiments since May 1992. Calibrated brightness temperature data in MIR channels are now available for studies of various hydrological parameters of the atmosphere and Earth's surface. Water vapor retrieval algorithms using multichannel MIR data input are developed for the profiling of atmospheric humidity. The retrieval algorithms are also extended to do three-dimensional mapping of moisture field using continuous observation provided by airborne sensor MIR or spaceborne sensor SSM/T-2. Validation studies for water vapor retrieval are carried out through the intercomparison of collocated and concurrent measurements using different instruments including lidars and radiosondes. The developed MIR water vapor retrieval algorithm is capable of humidity profiling under meteorological conditions ranging from clear column to moderately cloudy sky. Simulative water vapor retrieval studies using extended microwave channels near 183 and 557 GHz strong absorption lines indicate feasibility of humidity profiling to layers in the upper troposphere and improve the overall vertical resolution through the atmosphere.

  4. Detection of Rain-on-Snow (ROS) Events Using the Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) and Weather Station Observations

    NASA Astrophysics Data System (ADS)

    Ryan, E. M.; Brucker, L.; Forman, B. A.

    2015-12-01

    During the winter months, the occurrence of rain-on-snow (ROS) events can impact snow stratigraphy via generation of large scale ice crusts, e.g., on or within the snowpack. The formation of such layers significantly alters the electromagnetic response of the snowpack, which can be witnessed using space-based microwave radiometers. In addition, ROS layers can hinder the ability of wildlife to burrow in the snow for vegetation, which limits their foraging capability. A prime example occurred on 23 October 2003 in Banks Island, Canada, where an ROS event is believed to have caused the deaths of over 20,000 musk oxen. Through the use of passive microwave remote sensing, ROS events can be detected by utilizing observed brightness temperatures (Tb) from AMSR-E. Tb observed at different microwave frequencies and polarizations depends on snow properties. A wet snowpack formed from an ROS event yields a larger Tb than a typical dry snowpack would. This phenomenon makes observed Tb useful when detecting ROS events. With the use of data retrieved from AMSR-E, in conjunction with observations from ground-based weather station networks, a database of estimated ROS events over the past twelve years was generated. Using this database, changes in measured Tb following the ROS events was also observed. This study adds to the growing knowledge of ROS events and has the potential to help inform passive microwave snow water equivalent (SWE) retrievals or snow cover properties in polar regions.

  5. Comparison of atmospheric profiles between microwave radiometer retrievals and radiosonde soundings

    NASA Astrophysics Data System (ADS)

    Xu, Guirong; Xi, Baike; Zhang, Wengang; Cui, Chunguang; Dong, Xiquan; Liu, Yuanyuan; Yan, Guopao

    2015-10-01

    Atmospheric profiles of temperature (T), vapor density (ρv), and relative humidity (RH) retrieved from ground-based microwave radiometer (MWR) measurements are compared with radiosonde soundings at Wuhan, China. The MWR retrievals were averaged in the ±30 min period centered at sounding times of 00 and 12 UTC. A total of 403 and 760 profiles under clear and cloudy skies were selected. Based on the comparisons, temperature profiles have better consistency than the ρv and RH profiles, lower levels are better than upper levels, and the cloudy are better than the clear-sky profiles. Three cloud types (low, middle, and high) were identified by matching the infrared radiation thermometer-detected cloud base temperature to the MWR-retrieved temperature-height profiles. Temperature profile under high cloud has the highest correlation coefficient (R) and the lowest bias and RMS, but under low cloud is in the opposite direction. The ρv profile under middle cloud has the highest R and the lowest bias but under high cloud has the lowest R, the largest bias, and RMS. Based on the radiosonde soundings, both clear and cloudy wind speeds and drifting distances increase with height but increase much faster under clear than cloudy above 4 km. The increased wind speeds and drifting distances with height have resulted in decreased correlation coefficient and increased temperature biases and RMSs with height for both clear and cloudy skies. The differences in R, bias, and RMS between clear and cloudy skies are primarily resulted from their wind speeds and drifting distances.

  6. Polarimetric Scanning Radiometer C and X Band Microwave Observations During SMEX03

    NASA Technical Reports Server (NTRS)

    Jackson, Thomas J.; Bindlish, Rajat; Gasiewski, Albin J.; Stankov, Boba; Klein, Marian; Njoku, Eni G.; Bosch, David; Coleman, Thomas; Laymon, Charles; Starks, Patrick

    2004-01-01

    Soil Moisture Experiments 2003 (SMEX03) was the second in a series of field campaigns using the NOAA Polarimetric Scanning Radiometer (PSR/CX) designed to validate brightness temperature data and soil moisture retrieval algorithms for the Advanced during SMEX03 were: calibration and validation of AMSR-E brightness temperature observations over different climate/vegetation regions of the US. (Alabama, Georgia, Oklahoma), identification of possible sources of Radio Frequency Interference (RFI), comparison of X-band observations from TRMM Microwave Imager (TMI), AMSR-E and PSR/CX, and exploring the potential of soil moisture retrieval algorithms using C and X band imagery in diverse landscapes. In the current investigation, more than one hundred flightlines of PSR/CX data were extensively processed to produce gridded brightness temperature products for the four study regions. Variations associated with soil moisture were not as large as hoped for due to the lack of significant rainfall in Oklahoma. Observations obtained over Alabama include a wide range of soil moisture and vegetation conditions for C and X band frequencies. These results clearly showed a lack of sensitivity to rainfall/soil moisture under forest canopy cover. Quantitative comparisons made between the PSR/CX, AMSR-E for validated that both the PSR/CX and AMSR-E data were well calibrated. X band comparisons of the PSR/CX high resolution and AMSR-E and TMI low-resolution data indicated a linear scaling for the range of conditions studied in SMEX03. These results will form the basis for further soil moisture investigations.

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

    NASA Astrophysics Data System (ADS)

    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.

  8. Atmospheric temperature profiles from ground to stratopause with a new microwave radiometer (51-57 GHz)

    NASA Astrophysics Data System (ADS)

    Stähli, Oliver; Murk, Axel; Kämpfer, Niklaus

    2013-04-01

    This instrument is the first ground-based radiometer which can measure tropospheric and stratospheric temperature profiles at the same time. TEMPERA operates in the frequency range from 51 to 57 GHz in the oxygen-emission region of the microwave spectrum and is measuring continuously since 2012 in our lab on the roof. The spectral analysis is done with a filterbank with 12 channels for the troposphere and with a digital FFT spectrometer which measures two oxygen-emission lines around 53 GHz with 32000 channels for the stratophere. In the measured spectra the influence of the Zeeman effect can be seen. A measurement is built up of a tipping curve from 30 to 70 degree zenith angle. For every zenith angle we change the frequency of the local oscillator to three different frequencies with a synthesizer in combination with an active multiplier. With this method we can measure 12 frequencies with only 4 detectors. The frontend is thermally stabilized with Peltier elements. An off-axis parabolic mirror feeds the incoming microwave radiation to the horn antenna providing an angular resolution of 4 degree (FWHM). Absolute calibration is done with a hot load and a noise diode. The noise diode is calibrated regularly with a liquid nitrogen load and a hot load. The temperature retrieval is done with the optimal estimation method by using the QPack2/ARTS2 software. For the a priori profile of the atmospheric temperature we use monthly mean of radiosonde data for the troposphere and climatology of satellite data (MLS) for the upper atmosphere. The forward model is calculated with the Rosenkranz 98 model. As atmopheric temperature is a key parameter for the investigation of dynamical and chemical processes in the atmosphere, this new instrument provides important information about the local atmospheric temperature over a high altitude range (ground to 50 km). The temporal resolution is about 15 minutes for the troposphere and about 2 hours in the stratosphere. We will present the

  9. A cloud detection algorithm using the downwelling infrared radiance measured by an infrared pyrometer of the ground-based microwave radiometer

    DOE PAGESBeta

    Ahn, M. H.; Han, D.; Won, H. Y.; Morris, Victor R.

    2015-02-03

    For better utilization of the ground-based microwave radiometer, it is important to detect the cloud presence in the measured data. Here, we introduce a simple and fast cloud detection algorithm by using the optical characteristics of the clouds in the infrared atmospheric window region. The new algorithm utilizes the brightness temperature (Tb) measured by an infrared radiometer installed on top of a microwave radiometer. The two-step algorithm consists of a spectral test followed by a temporal test. The measured Tb is first compared with a predicted clear-sky Tb obtained by an empirical formula as a function of surface air temperaturemore » and water vapor pressure. For the temporal test, the temporal variability of the measured Tb during one minute compares with a dynamic threshold value, representing the variability of clear-sky conditions. It is designated as cloud-free data only when both the spectral and temporal tests confirm cloud-free data. Overall, most of the thick and uniform clouds are successfully detected by the spectral test, while the broken and fast-varying clouds are detected by the temporal test. The algorithm is validated by comparison with the collocated ceilometer data for six months, from January to June 2013. The overall proportion of correctness is about 88.3% and the probability of detection is 90.8%, which are comparable with or better than those of previous similar approaches. Two thirds of discrepancies occur when the new algorithm detects clouds while the ceilometer does not, resulting in different values of the probability of detection with different cloud-base altitude, 93.8, 90.3, and 82.8% for low, mid, and high clouds, respectively. Finally, due to the characteristics of the spectral range, the new algorithm is found to be insensitive to the presence of inversion layers.« less

  10. A cloud detection algorithm using the downwelling infrared radiance measured by an infrared pyrometer of the ground-based microwave radiometer

    NASA Astrophysics Data System (ADS)

    Ahn, M.-H.; Han, D.; Won, H. Y.; Morris, V.

    2015-02-01

    For better utilization of the ground-based microwave radiometer, it is important to detect the cloud presence in the measured data. Here, we introduce a simple and fast cloud detection algorithm by using the optical characteristics of the clouds in the infrared atmospheric window region. The new algorithm utilizes the brightness temperature (Tb) measured by an infrared radiometer installed on top of a microwave radiometer. The two-step algorithm consists of a spectral test followed by a temporal test. The measured Tb is first compared with a predicted clear-sky Tb obtained by an empirical formula as a function of surface air temperature and water vapor pressure. For the temporal test, the temporal variability of the measured Tb during one minute compares with a dynamic threshold value, representing the variability of clear-sky conditions. It is designated as cloud-free data only when both the spectral and temporal tests confirm cloud-free data. Overall, most of the thick and uniform clouds are successfully detected by the spectral test, while the broken and fast-varying clouds are detected by the temporal test. The algorithm is validated by comparison with the collocated ceilometer data for six months, from January to June 2013. The overall proportion of correctness is about 88.3% and the probability of detection is 90.8%, which are comparable with or better than those of previous similar approaches. Two thirds of discrepancies occur when the new algorithm detects clouds while the ceilometer does not, resulting in different values of the probability of detection with different cloud-base altitude, 93.8, 90.3, and 82.8% for low, mid, and high clouds, respectively. Finally, due to the characteristics of the spectral range, the new algorithm is found to be insensitive to the presence of inversion layers.

  11. A cloud detection algorithm using the downwelling infrared radiance measured by an infrared pyrometer of the ground-based microwave radiometer

    SciTech Connect

    Ahn, M. H.; Han, D.; Won, H. Y.; Morris, Victor R.

    2015-02-03

    For better utilization of the ground-based microwave radiometer, it is important to detect the cloud presence in the measured data. Here, we introduce a simple and fast cloud detection algorithm by using the optical characteristics of the clouds in the infrared atmospheric window region. The new algorithm utilizes the brightness temperature (Tb) measured by an infrared radiometer installed on top of a microwave radiometer. The two-step algorithm consists of a spectral test followed by a temporal test. The measured Tb is first compared with a predicted clear-sky Tb obtained by an empirical formula as a function of surface air temperature and water vapor pressure. For the temporal test, the temporal variability of the measured Tb during one minute compares with a dynamic threshold value, representing the variability of clear-sky conditions. It is designated as cloud-free data only when both the spectral and temporal tests confirm cloud-free data. Overall, most of the thick and uniform clouds are successfully detected by the spectral test, while the broken and fast-varying clouds are detected by the temporal test. The algorithm is validated by comparison with the collocated ceilometer data for six months, from January to June 2013. The overall proportion of correctness is about 88.3% and the probability of detection is 90.8%, which are comparable with or better than those of previous similar approaches. Two thirds of discrepancies occur when the new algorithm detects clouds while the ceilometer does not, resulting in different values of the probability of detection with different cloud-base altitude, 93.8, 90.3, and 82.8% for low, mid, and high clouds, respectively. Finally, due to the characteristics of the spectral range, the new algorithm is found to be insensitive to the presence of inversion layers.

  12. Investigation of antenna pattern constraints for passive geosynchronous microwave imaging radiometers

    NASA Technical Reports Server (NTRS)

    Gasiewski, A. J.; Skofronick, G. M.

    1992-01-01

    Progress by investigators at Georgia Tech in defining the requirements for large space antennas for passive microwave Earth imaging systems is reviewed. In order to determine antenna constraints (e.g., the aperture size, illumination taper, and gain uncertainty limits) necessary for the retrieval of geophysical parameters (e.g., rain rate) with adequate spatial resolution and accuracy, a numerical simulation of the passive microwave observation and retrieval process is being developed. Due to the small spatial scale of precipitation and the nonlinear relationships between precipitation parameters (e.g., rain rate, water density profile) and observed brightness temperatures, the retrieval of precipitation parameters are of primary interest in the simulation studies. Major components of the simulation are described as well as progress and plans for completion. The overall goal of providing quantitative assessments of the accuracy of candidate geosynchronous and low-Earth orbiting imaging systems will continue under a separate grant.

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

    NASA Astrophysics Data System (ADS)

    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

  14. On-orbit structural dynamic performance of a low-frequency microwave radiometer for Mission to Planet Earth applications

    NASA Technical Reports Server (NTRS)

    Wahls, Deborah M.; Farmer, Jeffery T.

    1991-01-01

    The present paper addresses the on-orbit dynamic performance of a low-frequency microwave radiometer for earth science applications. The radiometer is one of the earth-observing instruments aboard a geostationary platform proposed as part of the Mission to Planet Earth. The paper includes establishing the structural requirements of the antenna, developing the structural and disturbance models, performing modal and forced response analyses, and evaluating the resulting distortions in terms of the antenna's ability to meet stringent structural performance requirements. Two antenna configurations are discussed: free-flying and platform-mounted. These configurations are analyzed for a representative disturbance function which simulates rotation of the subreflector in order to perform a raster-type scan of the earth disk. Results show that the scanning maneuver modeled did not induce antenna performance errors which were outside their estimated limits.

  15. ACA phase calibration scheme with the ALMA water vapor radiometers

    NASA Astrophysics Data System (ADS)

    Asaki, Yoshiharu; Matsushita, Satoki; Morita, Koh-Ichiro; Nikolic, Bojan

    2012-09-01

    In Atacama Large Millimeter/submillimeter Array (ALMA) commissioning and science verification we have conducted a series of experiments of a novel phase calibration scheme for Atacama Compact Array (ACA). In this scheme water vapor radiometers (WVRs) devoted to measurements of tropospheric water vapor content are attached to ACA’s four total-power array (TP Array) antennas surrounding the 7 m dish interferometer array (7 m Array). The excess path length (EPL) due to the water vapor variations aloft is fitted to a simple two-dimensional slope using WVR measurements. Interferometric phase fluctuations for each baseline of the 7 m Array are obtained from differences of EPL inferred from the two-dimensional slope and subtracted from the interferometric phases. In the experiments we used nine ALMA 12-m antennas. Eight of them were closely located in a 70-m square region, forming a compact array like ACA. We supposed the most four outsiders to be the TP Array while the inner 4 antennas were supposed to be the 7 m Array, so that this phase correction scheme (planar-fit) was tested and compared with the WVR phase correction. We estimated residual root-mean-square (RMS) phases for 17- to 41-m baselines after the planar-fit phase correction, and found that this scheme reduces the RMS phase to a 70 - 90 % level. The planar-fit phase correction was proved to be promising for ACA, and how high or low PWV this scheme effectively works in ACA is an important item to be clarified.

  16. An alternate algorithm for correction of the scanning multichannel microwave radiometer polarization radiances using Nimbus-7 observed data

    NASA Technical Reports Server (NTRS)

    Gloersen, P.; Cavalieri, D. J.; Soule, H. V.

    1980-01-01

    The manner in which Nimbus-7 scanning multichannel microwave radiometer (SMMR) scan radiance data was used to determine its operational characteristics is described. The predicted SMMR scan radiance was found to be in disagreement at all wavelengths with a large area of average measured ocean radiances. A modified model incorporating a different phase shift for each of the SMMR horizontal and vertical polarization channels was developed and found to provide good data correlation. Additional study is required to determine the validity and accuracy of this model.

  17. Wearable microwave radiometers for remote fire detection: System-on-Chip (SoC) design and proof of the concept.

    PubMed

    Tasselli, G; Alimenti, F; Fonte, A; Zito, D; Roselli, L; De Rossi, D; Lanatà, A; Neri, B; Tognetti, A

    2008-01-01

    The paper reports the present status of the project aimed at the realization of a wearable low-cost low-power System-on-Chip (SoC) 13-GHz passive microwave radiometer in CMOS 90 nm technology. This sensor has been thought to be inserted into the firemen jacket in order to help them in the detection of a hidden fire behind a door or a wall, especially where the IR technology fail. With respect of the prior art, the SoC is further developed and a proof of the concept is provided by means of a discrete-component prototype.

  18. Wearable microwave radiometers for remote fire detection: System-on-Chip (SoC) design and proof of the concept.

    PubMed

    Tasselli, G; Alimenti, F; Fonte, A; Zito, D; Roselli, L; De Rossi, D; Lanatà, A; Neri, B; Tognetti, A

    2008-01-01

    The paper reports the present status of the project aimed at the realization of a wearable low-cost low-power System-on-Chip (SoC) 13-GHz passive microwave radiometer in CMOS 90 nm technology. This sensor has been thought to be inserted into the firemen jacket in order to help them in the detection of a hidden fire behind a door or a wall, especially where the IR technology fail. With respect of the prior art, the SoC is further developed and a proof of the concept is provided by means of a discrete-component prototype. PMID:19162822

  19. Assessment of Urban Planetary Boundary Layer Dynamics using Lidar, Microwave Radiometer and Ceilometer Observations over New York City Area

    NASA Astrophysics Data System (ADS)

    Gan, C.; Wu, Y.; Gross, B.; Moshary, F.

    2010-12-01

    Planetary Boundary Layer (PBL) dynamics is crucial in providing accurate air quality forecasts and is very useful in assessing air-transport models. In particular, incorrect determination of PBL dynamics can lead to imprecise surface particulate matter (PM) monitoring since aerosols are usually well mixed within the PBL during the convective heating period. However, PBL dynamics is strongly driven by surface flux measurements which are strongly influenced on the complexities of the urban surface including surface albedo and roughness parameters. Therefore direct assessment of the PBL height dynamics using active sensors is desired to assess the different urban parameterizations. This paper presents long term statistical data comparing the convective PBL growth obtained from lidar based measurements with different Weather Research and Forecast (WRF) parameterizations as well as an urbanized high resolution (uWRF) method based on 3 level urban structure parameterizations. We find that the operational bulk parameterizations used by WRF generally overestimate both the initiation and magnitude of the mixing layer height. This can be explained as an underestimate of the urban surface roughness that tends to reduce the surface buoyant flux. However, we find that comparisons with uWRF tend to overcorrect the convective growth. In support of these efforts, we develop an improved method to separate the convective layer from residual layer and clouds within the lidar signal. Further model assessments include water vapor and temperature from a passive Microwave radiometer. In particular, we find that the differential temperature between air and surface temperature is generally overestimated in the standard WRF models which is consistent with PBL height observations. Estimate PBL (black dash line) and Lidar Measurements on July 2, 2010

  20. Standard Dataset of Brightness Temperature Resampled by Antenna Pattern Matching for Microwave Radiometer AMSR2 on GCOM-W1 Satellite

    NASA Astrophysics Data System (ADS)

    Maeda, Takashi; Imaoka, Keiji

    2014-05-01

    The operation of the Advanced Microwave Scanning Radiometer for Earth-Observation System (AMSR-E) loaded on Aqua satellite stopped in October, 2011 after more than 9-years observation. But after that, the successor of AMSR-E (AMSR2) was developed and loaded on GCOM-W1 (Global Change Observation Mission 1st - Water) satellite. GCOM-W1 satellite was successfully launched in May, 2012. AMSR2 is a microwave radiometer almost similar to AMSR-E, but some important improvements are made (i.e., expansion of its main reflector's size, addition of 7.3-GHz channel to detect radio frequency interferences at 6.9 GHz). GCOM-W1 satellite is deployed into a sun-synchronous sub-recurrent orbit, and AMSR2 observes microwave powers emitted from anywhere on the Earth almost twice a day, daytime in an ascending track and nighttime in a descending track. When we use a satellite-borne microwave radiometer data that have a main reflector shared by plural feed horns, there is an inevitable problem, the differences of footprints' sizes among frequencies. In case of AMSR2, the smallest footprint's size of 89 GHz (3 × 5 km2) has just one percent of the broadest one of 6.9 GHz (35 × 62 km2). Under the circumstance, when brightness temperatures (Tb values) of plural frequencies are obtained from the same geolocation, it is difficult to compare them one another because their observation areas are absolutely different. The concept to solve this problem is simple: actually, after a satellite-borne microwave radiometer observed on the Earth's surface, footprints which give brightness temperatures of each frequency densely distribute on it with overlaps at several-kilometer intervals (i.e., 5 km as for 89 GHz and 10 km as for other frequencies in AMSR2). The footprint is an antenna pattern projected to the Earth's surface. The antenna pattern's shape is generally like a 2-dimensional Gaussian distribution. The center of the antenna pattern has strong sensitivity, and its circumjacent part has weak

  1. ARM - Midlatitude Continental Convective Clouds Microwave Radiometer Profiler (jensen-mwr)

    DOE Data Explorer

    Jensen, Mike

    2012-02-01

    A major component of the Mid-latitude Continental Convective Clouds Experiment (MC3E) field campaign was the deployment of an enhanced radiosonde array designed to capture the vertical profile of atmospheric state variables (pressure, temperature, humidity wind speed and wind direction) for the purpose of deriving the large-scale forcing for use in modeling studies. The radiosonde array included six sites (enhanced Central Facility [CF-1] plus five new sites) launching radiosondes at 3-6 hour sampling intervals. The network will cover an area of approximately (300)2 km2 with five outer sounding launch sites and one central launch location. The five outer sounding launch sites are: S01 Pratt, KS [ 37.7oN, 98.75oW]; S02 Chanute, KS [37.674, 95.488]; S03 Vici, Oklahoma [36.071, -99.204]; S04 Morris, Oklahoma [35.687, -95.856]; and S05 Purcell, Oklahoma [34.985, -97.522]. Soundings from the SGP Central Facility during MC3E can be retrieved from the regular ARM archive. During routine MC3E operations 4 radiosondes were launched from each of these sites (approx. 0130, 0730, 1330 and 1930 UTC). On days that were forecast to be convective up to four additional launches were launched at each site (approx. 0430, 1030, 1630, 2230 UTC). There were a total of approximately 14 of these high frequency launch days over the course of the experiment. These files contain brightness temperatures observed at Purcell during MC3E. The measurements were made with a 5 channel (22.235, 23.035, 23.835, 26.235, 30.000GHz) microwave radiometer at one minute intervals. The results have been separated into daily files and the day of observations is indicated in the file name. All observations were zenith pointing. Included in the files are the time variables base_time and time_offset. These follow the ARM time conventions. Base_time is the number seconds since January 1, 1970 at 00:00:00 for the first data point of the file and time_offset is the offset in seconds from base_time.

  2. Cosmic temperature fluctuations from two years of COBE differential microwave radiometers observations

    NASA Technical Reports Server (NTRS)

    Bennett, C. L.; Kogut, A.; Hinshaw, G.; Banday, A. J.; Wright, E. L.; Gorski, K. M.; Wilkinson, D. T.; Weiss, R.; Smoot, G. F.; Meyer, S. S.

    1994-01-01

    The first two years of Cosmic Background Explorer (COBE) Differential Microwave Radiometers (DMR) observations of the cosmic microwave background (CMB) anisotropy are analyzed and compared with our previously published first year results. The results are consistent, but the addition of the second year of data increases the precision and accuracy detected CMB temperature fluctuations. The 2 yr 53 GHz data are characterized by rms temperature fluctuations of (delta-T)(sub rms) (7 deg) = 44 +/- 7 micro-K and (delta-T)(sub rms) (10 deg) = 30.5 +/- 2.7 micro-K at 7 deg and 10 deg angular resolution, respectively. The 53 x 90 GHz cross-correlation amplitude at zero lag is C(0)(sup 1/2) = 36 +/- 5 micro-K (68% CL) for the unsmoothed (7 deg resolution) DMR data. We perform a likelihood analysis of the cross-correlation function, with Monte Carlo simulations to infer biases of the method, for a power-law model of initial density fluctuations, P(k) proportional to R(exp n). The Monte Carlo simulations indicate that derived estimates of n are biased by +0.11 +/- 0.01, while the subset of simulations with a low quadrupole (as observed) indicate a bias of +0.31+/- 0.04. Derived values for 68% confidence intervals are given corrected (and not corrected) for our estimated biases. Including the quadrupole anisotropy, the most likely quadrupole-normalized amplitude is Q(sub rms-PS) = 14.3(sup + 5.2 sub -3.3) micro-K (12.8(sup + 5.2 sub -3.3) micro-K0 with a spectral index n = 1.42(sup + 0.49 sub -0.55)(n = 1.53(sup + 0.49 sub -0.55). With n fixed to 1.0 the most likely amplitude is 18.2 +/- 11.5 micro-K (17.4 +/- 1.5 micro-K). The marginal likelihood of n is 1.42 +/- 0.37 (1.53 +/- 0.37). Excluding the quadrupole anisotropy, the most likely quadrupole-normalized amplitude is Q(sub rms-PS) = 17.4(sup + 7.5 sub -5.2) micro-K (15.8(sup + 7.5 sub -5.2) micro-K) with a spectral index n = 1.11(sup + 0.60 sub -0.55) (n = 1.22(sup + 0.60 sub -0.55). With n fixed to 1.0 the most likely

  3. User's guide for the Nimbus 7 Scanning Multichannel Microwave Radiometer (SMMR) CELL-ALL tape

    NASA Technical Reports Server (NTRS)

    Cu, C. C.; Han, D.; Kim, S. T.; Gloersen, P.

    1988-01-01

    The SMMR instrument onboard the Nimbus-7 satellite has been in operation since October 1978. It provided global coverage of passive microwave observations at 6.6, 10.7, 18, 21, and 37 GHz. The oberved brightness temperature can be used to retrieve geophysical parameters, principally sea surface temperature, atmospheric water vapor and liquid water content over oceans, sea ice concentration, and snow cover over land. The SMME CELL-ALL Tape contains earth-located calibrated brightness temperature data which have been appropriately binned into cells of various grid sizes, allowing intercomparisons of observations made at different frequencies (with corresponding different footprint sizes). This user's guide describes the operation of the instrument, the flow of the data processing the calibration procedure, and the characteristics of the calibrated brightness temperatures and how they are binned. Detailed tape specifications and lists of available data are also provided.

  4. Microwave radiometer measurement of tidally induced salinity changes off the Georgia coast

    NASA Technical Reports Server (NTRS)

    Kendall, B. M.; Blanton, J. O.

    1981-01-01

    A quasi-synoptic survey of tidally induced salinity changes off the Georgia coast was performed by using a L band microwave radiomater onboard a NASA aircraft. Salinity maps were obtained for ebb and flood conditions in order to define the salinity distributions near rivers and sounds and major changes that occur from ebb flow to flood flow. The Savannah River plume dominated the salinity regime and extended out from the Savannah River mouth about 12 km during ebb tidal conditions. The plume merged into a band of low salinity water extending along the Georgia-South Carolina coast which was produced by the many river sources of freshwater entering the coastal waters. The changes in salinity observed offshore of the river plume area were consistent with estimates of the changes that would occur over a typical tidal excursion perpendicular to the observed gradient.

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

    NASA Astrophysics Data System (ADS)

    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

  6. Microwave signatures of snow and fresh water ice

    NASA Technical Reports Server (NTRS)

    Schmugge, T.; Wilheit, T. T.; Gloersen, P.; Meier, M. F.; Frank, D.; Dirmhirn, I.

    1973-01-01

    During March of 1971, the NASA Convair 990 Airborne Observatory carrying microwave radiometers in the wavelength range 0.8 to 21 cm was flown over dry snow with different substrata: Lake ice at Bear Lake in Utah; wet soil in the Yampa River Valley near Steamboat Springs, Colorado; and glacier ice, firm and wet snow on the South Cascade Glacier in Washington. The data presented indicate that the transparency of the snow cover is a function of wavelength. False-color images of microwave brightness temperatures obtained from a scanning radiometer operating at a wavelength of 1.55 cm demonstrate the capability of scanning radiometers for mapping snowfields.

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

    NASA Astrophysics Data System (ADS)

    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

  8. Radiometer Testbed Development for SWOT

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

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

  9. Measurement of dielectric properties and determination of microwave emissivity of polluted waters

    NASA Technical Reports Server (NTRS)

    Blume, H.-J. C.

    1980-01-01

    The dielectric properties of polluted waters are measured with a reflection-type resonant cavity at 1.43 GHz. Very small water samples in quartz tubes of known volume are placed in the center of the maximum electric field. Measurement of the resonance-frequency variation and a change of the cavity's quality factor are used to determine the dielectric properties. The microwave emissivity of the polluted water is then calculated via the Fresnel equation and applied to data reductions of microwave radiometer measurements.

  10. Assimilation of humidity and temperature observations retrieved from ground-based microwave radiometers into a convective-scale NWP model

    NASA Astrophysics Data System (ADS)

    Caumont, Olivier; Vincendon, Béatrice; Cimini, Domenico; Löhnert, Ulrich; Alados-Arboledas, Lucas; Bleisch, René; Buffa, Franco; Enrico Ferrario, Massimo; Haefele, Alexander; Huet, Thierry; Madonna, Fabio; Pace, Giandomenico

    2016-04-01

    Temperature and humidity retrievals from an international network of ground-based microwave radiometers (MWR) have been collected to assess the potential of their assimilation into a convective-scale Numerical Weather Prediction (NWP) system. Thirteen stations over a domain encompassing the western Mediterranean basin were considered for a time period of forty-one days in autumn, when heavy-precipitation events most often plague this area. Prior to their assimilation, MWR data were compared to very-short-term forecasts. Observation-minus-background statistics revealed some biases, but standard deviations were comparable to that obtained with radiosondes. The MWR data were then assimilated in a three-dimensional variational (3DVar) data assimilation system through the use of a rapid update cycle. A set of sensitivity experiments allowed assessing extensively the impact of the assimilation of temperature and humidity profiles, both separately and jointly. The respective benefit of MWR data and radiosonde data on analyses and forecasts was also investigated.

  11. Retrieval of ocean surface parameters from the scanning multifrequency microwave radiometer (SMMR) on the Nimbus-7 satellite

    SciTech Connect

    Wilheit, T.T.; Chang, E.; Gatlin, J.; Greaves, J.; Han, D.; Krupp, B.M.; Milman, A.S.

    1984-03-01

    Sea-surface temperature retrievals have been tested on 2 months of Nimbus-7 scanning multichannel microwave radiometer data. Using the prelaunch versions of the instrument calibration and geophysical parameter retrieval algorithms the initial results were poor. Improved algorithms produced substantially better results. It appears that at least for the night-Southern Hemisphere portion of the Nimbus-7 orbit, a rms measurement accuracy of 1.45/sup 0/C has been achieved. Similar tests with wind speed retrievals yield an accuracy of 2.7 m/s rms with no substantial differences between day and night measurements but limited by availability of surface observations to the Northern Hemisphere. Moreover, it appears that the retrieved wind speed is more nearly related to the square of the wind observed at the surface than to the wind itself.

  12. Non-linearity in measurement systems: Evaluation method and application to microwave radiometers

    NASA Technical Reports Server (NTRS)

    Stelzried, C. T.

    1987-01-01

    A simple method for determination and correction of nonlinaearity in measurement systems is presented. The technique is applicable to a wide range of measuring systems. The basic concept, an analysis, and a sample application are given. Nonlinearity of the Goldstone DSS 13 low noise HEMT 2.3 GHz (S-band) radiometer system results in noise temperature measurement errors. These errors are successfully correct with this method.

  13. A general analysis of the impact of digitization in microwave correlation radiometers.

    PubMed

    Bosch-Lluis, Xavier; Ramos-Perez, Isaac; Camps, Adriano; Rodriguez-Alvarez, Nereida; Valencia, Enric; Park, Hyuk

    2011-01-01

    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. PMID:22163943

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

    NASA Technical Reports Server (NTRS)

    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.

  15. G-Band Vapor Radiometer Precipitable Water Vapor (GVRPWV) Value-Added Product

    SciTech Connect

    Koontz, A; Cadeddu, M

    2012-12-05

    The G-Band Vapor Radiometer Precipitable Water Vapor (GVRPWV) value-added product (VAP) computes precipitable water vapor using neural network techniques from data measured by the GVR. The GVR reports time-series measurements of brightness temperatures for four channels located at 183.3 ± 1, 3, 7, and 14 GHz.

  16. Millimeter-wave imaging radiometer for cloud, precipitation and atmospheric water vapor studies

    NASA Technical Reports Server (NTRS)

    Racette, P. E.; Dod, L. R.; Shiue, J. C.; Adler, R. F.; Jackson, D. M.; Gasiewski, A. J.; Zacharias, D. S.

    1992-01-01

    A millimeter-wave imaging radiometer (MIR) developed by NASA Goddard Space Flight Center is described. The MIR is a nine-channel total power radiometer developed for atmospheric research. Three dual-pass band channels are centered about the strongly opaque 183-GHz water vapor absorption line; the frequencies are 183 +/- 1, +/- 3, and +/- 7 GHz. Another channel is located on the wing of this band at 150 GHz. These four channels have varying degrees of opacity from which the water vapor profile can be inferred. The design and salient characteristics of this instrument are discussed, together with its expected benefits.

  17. Effects of corn stalk orientation and water content on passive microwave sensing of soil moisture

    NASA Technical Reports Server (NTRS)

    Oneill, P. E.; Blanchard, B. J.; Wang, J. R.; Gould, W. I.; Jackson, T. J.

    1984-01-01

    A field experiment was conducted utilizing artificial arrangements of plant components during the summer of 1982 to examine the effects of corn canopy structure and plant water content on microwave emission. Truck-mounted microwave radiometers at C (5 GHz) and L (1.4 GHz) band sensed vertically and horizontally polarized radiation concurrent with ground observations of soil moisture and vegetation parameters. Results indicate that the orientation of cut stalks and the distribution of their dielectric properties through the canopy layer can influence the microwave emission measured from a vegetation/soil scene. The magnitude of this effect varies with polarization and frequency and with the amount of water in the plant, disappearing at low levels of vegetation water content. Although many of the canopy structures and orientations studied in this experiment are somewhat artificial, they serve to improve understanding of microwave energy interactions within a vegetation canopy and to aid in the development of appropriate physically based vegetation models.

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

    NASA Technical Reports Server (NTRS)

    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.

  19. CHARM: A CubeSat Water Vapor Radiometer for Earth Science

    NASA Technical Reports Server (NTRS)

    Lim, Boon; Mauro, David; DeRosee, Rodolphe; Sorgenfrei, Matthew; Vance, Steve

    2012-01-01

    The Jet Propulsion Laboratory (JPL) and Ames Research Center (ARC) are partnering in the CubeSat Hydrometric Atmospheric Radiometer Mission (CHARM), a water vapor radiometer integrated on a 3U CubeSat platform, selected for implementation under NASA Hands-On Project Experience (HOPE-3). CHARM will measure 4 channels at 183 GHz water vapor line, subsets of measurements currently performed by larger and more costly spacecraft (e.g. ATMS, AMSU-B and SSMI/S). While flying a payload that supports SMD science objectives, CHARM provides a hands-on opportunity to develop technical, leadership, and project skills. CHARM will furthermore advance the technology readiness level (TRL) of the 183 GHz receiver subsystem from TRL 4 to TRL 6 and the CubeSat 183 GHz radiometer system from TRL 4 to TRL 7.

  20. Atmospheric water parameters in mid-latitude cyclones observed by microwave radiometry and compared to model calculations

    NASA Technical Reports Server (NTRS)

    Katsaros, Kristina B.; Hammarstrand, Ulla; Petty, Grant W.

    1990-01-01

    Existing and experimental algorithms for various parameters of atmospheric water content such as integrated water vapor, cloud water, precipitation, are used to examine the distribution of these quantities in mid latitude cyclones. The data was obtained from signals given by the special sensor microwave/imager (SSM/I) and compared with data from the nimbus scanning multichannel microwave radiometer (SMMR) for North Atlantic cyclones. The potential of microwave remote sensing for enhancing knowledge of the horizontal structure of these storms and to aid the development and testing of the cloud and precipitation aspects of limited area numerical models of cyclonic storms is investigated.

  1. Profiling atmospheric water vapor by microwave radiometry

    NASA Technical Reports Server (NTRS)

    Wang, J. R.; Wilheit, T. T.; Szejwach, G.; Gesell, L. H.; Nieman, R. A.; Niver, D. S.; Krupp, B. M.; Gagliano, J. A.; King, J. L.

    1983-01-01

    High-altitude microwave radiometric observations at frequencies near 92 and 183.3 GHz were used to study the potential of retrieving atmospheric water vapor profiles over both land and water. An algorithm based on an extended kalman-Bucy filter was implemented and applied for the water vapor retrieval. The results show great promise in atmospheric water vapor profiling by microwave radiometry heretofore not attainable at lower frequencies.

  2. Observations of frozen skin of southern ocean from multifrequency scanning microwave radiometer (MSMR) onboard oceansat - 1

    NASA Astrophysics Data System (ADS)

    Vyas, N.; Bhandari, S.; Dash, M.; Pandey, P.; Khare, N.

    Encircling the Antarctic, Southern Ocean connects all the three oceans of the world with fastest current system found anywhere in the world. The region is thermally very stable and is covered with ice, which has a strong seasonal variability. The sea ice pulsates annually with seasonal migration varying from 4 million square kilometer to 20 million square kilometer during summer and winter respectively. This has strong influence on energy balance of the ocean-ice-atmosphere system, and hence on atmospheric general circulation affecting weather and climate. Sea ice also works as an insulator thus inhibiting the energy flux between ocean and atmosphere. It also influences the ecosystem of the southern ocean, which has rich fish resources with global economic values such as krill and tooth fish. During winter Krill survives on algae found at the under side of the sea ice. The southern ocean is known to have high nutrition but low concentration of chlorophyll-a, which is a proxy of the phytoplankton. It is now understood that iron is the limiting factor as has been shown by various iron fertilization experiments. Passive microwave radiometry from space has been extensively used for the study of sea ice types and concentration in the Arctic and the Antarctic regions. Since late 1970s, data from SMMR and SSM/I have been used to study trends in sea ice extent and area. We have further extended the above studies by using data from OCEANSAT - 1 MSMR. The data, acquired at 18 GHz (H) with 50 kilometer resolution and having a swath of 1360 kilometer and a repeat cycle of 2 days, was processed to generate the brightness temperature maps over the Antarctica for a period of 2 years and the results were analyzed in conjunction with those obtained earlier (since 1978) through the study of SMMR and SSM/I data. Besides strong seasonal variability, our analysis shows an increasing trend in the sea ice extent during the recent years and the rate appears to be accelerating contrary to

  3. Requirements of space-borne microwave radiometers for detecting soil moisture contents

    NASA Technical Reports Server (NTRS)

    Burke, H.-H. K.; Burke, W. J.

    1981-01-01

    A multilayer radiative transfer model for predicting the relationship between soil moisture content and microwave emission is summarized. Attention is also given to the performance of various microwave sensors for soil moisture retrieval; here, the requirements of a satellite sensor system for monitoring large-scale soil moisture conditions are discussed. These requirements are presented in terms of (1) the wavelength, (2) atmospheric contamination, (3) polarization, (4) frequency of observation, and (5) spatial resolution. Each parameter is discussed in terms of microwave response. Previous aircraft data with extensive ground truth information are used to support the theories proposed. Trade-offs between the parameters and an optimum sensor system for space monitoring soil moisture information are discussed.

  4. Classification of Baltic Sea ice types by airborne multifrequency microwave radiometer

    SciTech Connect

    Kurvonen, L.; Hallikainen, M.

    1996-11-01

    An airborne multifrequency radiometer (24, 34, 48, and 94 GHz, vertical polarization) was used to investigate the behavior of the brightness temperature of different sea ice types in the Gulf of Bothnia (Baltic Sea). The measurements and the main results of the analysis are presented. The measurements were made in dry and wet conditions (air temperature above and below 0 C). The angle of incidence was 45{degree} in all measurements. The following topics are evaluated: (a) frequency dependency of the brightness temperature of different ice types, (b) the capability of the multifrequency radiometer to classify ice types for winter navigation purposes, and (c) the optimum measurement frequencies for mapping sea ice. The weather conditions had a significant impact on the radiometric signatures of some ice types (snow-covered compact pack ice and frost-covered new ice); the impact was the highest at 94 GHz. In all cases the overall classification accuracy was around 90% (the kappa coefficient was from 0.86 to 0.96) when the optimum channel combination (24/34 GHz and 94 GHz) was used.

  5. Design Data Collection with Skylab Microwave Radiometer-Scatterometer S-193, Volume 1

    NASA Technical Reports Server (NTRS)

    Moore, R. K.; Ulaby, F. T. (Principal Investigator)

    1975-01-01

    The author has identified the following significant results. Observations with S-193 have provided radar design information for systems to be flown on spacecraft, but only at 13.9 GHz and for land areas over the United States and Brazil plus a few other areas of the world for which this kind of analysis was not made. Observations only extended out to about 50 deg angle of incidence. The value of a sensor with such a gross resolution for most overland resource and status monitoring systems seems marginal, with the possible exception of monitoring soil moisture and major vegetation variations. The complementary nature of the scatterometer and radiometer systems was demonstrated by the correlation analysis. Although radiometers must have spatial resolutions dictated by antenna size, radars can use synthetic aperture techniques to achieve much finer resolutions. Multiplicity of modes in the S-193 sensors complicated both the system development and its employment. An attempt was made in the design of the S-193 to arrange optimum integration times for each angle and type of measurement. This unnecessarily complicated the design of the instrument, since the gains in precision achieved in this way were marginal. Either a software-controllable integration time or a set of only two or three integration times would have been better.

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

    NASA Astrophysics Data System (ADS)

    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.

  7. Arctic sea ice concentrations from special sensor microwave imager and advanced very high resolution radiometer satellite data

    NASA Technical Reports Server (NTRS)

    Emery, W. J.; Fowler, C.; Maslanik, J.

    1994-01-01

    Nearly coincident data from the special sensor microwave imager (SSM/I) and the advanced very high resolution radiometer (AVHRR) are used to compute and compare Arctic sea ice concentrations for different regions and times of the year. To help determine overall accuracies and to highlight sources of differences between passive microwave, optical wavelength, and thermal wavelength data, ice concentrations are estimated using two operational SSM/I ice concentration algorithms and with visible- and thermal-infrared wavelength AVHRR data. All algorithms capture the seasonal patterns of ice growth and melt. The ranges of differences fall within the general levels of uncertainty expected for each method and are similar to previous accuracy estimates. The estimated ice concentrations are all highly correlated, with uniform biases, although differences between individual pairs of observations can be large. On average, the NASA Team algorithm yielded 5% higher ice concentrations than the Bootstrap algorithm, while during nonmelt periods the two SSM/I algorithms agree to within 0.5%. These seasonal differences are consistent with the ways that the 19-GHz and 37-GHz microwave channels are used in the algorithms. When compared to the AVHRR-derived ice concentrations, the Team-algorithm results are more similar on average in terms of correlation and mean differences. However, the Team algorithm underestimates concentrations relative to the AVHRR output by 6% during cold months and overestimates by 3% during summer. Little seasonal difference exists between the Bootstrap and AVHRR results, with a mean difference of about 5%. Although the mean differences are less between the SSM/I-derived concentrations and concentrations estimated using AVHRR channel 1, the correlations appear substantially better between the SSM/I data and concentrations derived from AVHRR channel 4, particularly for the Team algorithm output.

  8. Five-band microwave radiometer system for noninvasive brain temperature measurement in newborn babies: Phantom experiment and confidence interval

    NASA Astrophysics Data System (ADS)

    Sugiura, T.; Hirata, H.; Hand, J. W.; van Leeuwen, J. M. J.; Mizushina, S.

    2011-10-01

    Clinical trials of hypothermic brain treatment for newborn babies are currently hindered by the difficulty in measuring deep brain temperatures. As one of the possible methods for noninvasive and continuous temperature monitoring that is completely passive and inherently safe is passive microwave radiometry (MWR). We have developed a five-band microwave radiometer system with a single dual-polarized, rectangular waveguide antenna operating within the 1-4 GHz range and a method for retrieving the temperature profile from five radiometric brightness temperatures. This paper addresses (1) the temperature calibration for five microwave receivers, (2) the measurement experiment using a phantom model that mimics the temperature profile in a newborn baby, and (3) the feasibility for noninvasive monitoring of deep brain temperatures. Temperature resolutions were 0.103, 0.129, 0.138, 0.105 and 0.111 K for 1.2, 1.65, 2.3, 3.0 and 3.6 GHz receivers, respectively. The precision of temperature estimation (2σ confidence interval) was about 0.7°C at a 5-cm depth from the phantom surface. Accuracy, which is the difference between the estimated temperature using this system and the measured temperature by a thermocouple at a depth of 5 cm, was about 2°C. The current result is not satisfactory for clinical application because the clinical requirement for accuracy must be better than 1°C for both precision and accuracy at a depth of 5 cm. Since a couple of possible causes for this inaccuracy have been identified, we believe that the system can take a step closer to the clinical application of MWR for hypothermic rescue treatment.

  9. Alternative Beam Efficiency Calculations for a Large-aperture Multiple-frequency Microwave Radiometer (LAMMR)

    NASA Technical Reports Server (NTRS)

    Schmidt, R. F.

    1979-01-01

    The fundamental definition of beam efficiency, given in terms of a far field radiation pattern, was used to develop alternative definitions which improve accuracy, reduce the amount of calculation required, and isolate the separate factors composing beam efficiency. Well-known definitions of aperture efficiency were introduced successively to simplify the denominator of the fundamental definition. The superposition of complex vector spillover and backscattered fields was examined, and beam efficiency analysis in terms of power patterns was carried out. An extension from single to dual reflector geometries was included. It is noted that the alternative definitions are advantageous in the mathematical simulation of a radiometer system, and are not intended for the measurements discipline where fields have merged and therefore lost their identity.

  10. Using Passive Microwaves for Open Water Monitoring and Flood Forecasting

    NASA Astrophysics Data System (ADS)

    Parinussa, R.; Johnson, F.; Sharma, A.; Lakshmi, V.

    2015-12-01

    One of the biggest and severest natural disasters that society faces is floods. An important component that can help in reducing the impact of floods is satellite remote sensing as it allows for consistent monitoring and obtaining catchment information in absence of physical contact. Nowadays, passive microwave remote sensing observations are available in near real time (NRT) with a couple of hours delay from the actual sensing. The Advanced Microwave Scanning Radiometer 2 (AMSR2) is a multi-frequency passive microwave sensor onboard the Global Change Observation Mission 1 - Water that was launched in May 2012. Several of these frequencies have a high sensitivity to the land surface and they also have the capacity to penetrate clouds. These advantages come at the cost of the relatively coarse spatial resolution (footprints range from ~5 to ~50 km) which in turn allows for global monitoring. A relatively simple methodology to monitor the fraction of open water from AMSR2 observations is presented here. Low frequency passive microwave observations have sensitivity to the land surface but are modulated by overlying signals from physical temperature and vegetation cover. We developed a completely microwave based artificial neural network supported by physically based components to monitor the fraction of open water. Three different areas, located in China, Southeast Asia and Australia, were selected for testing purposes and several different characteristics were examined. First, the overall performance of the methodology was evaluated against the NASA NRT Global Flood Mapping system. Second, the skills of the various different AMSR2 frequencies were tested and revealed that artificial contamination is a factor to consider. The different skills of the tested frequencies are of interest to apply the methodology to alternative passive microwave sensors. This will be of benefit in using the numerous multi-frequency passive microwaves sensors currently observing our Earth

  11. Stray light effects in above-water remote-sensing reflectance from hyperspectral radiometers.

    PubMed

    Talone, Marco; Zibordi, Giuseppe; Ansko, Ilmar; Banks, Andrew Clive; Kuusk, Joel

    2016-05-20

    Stray light perturbations are unwanted distortions of the measured spectrum due to the nonideal performance of optical radiometers. Because of this, stray light characterization and correction is essential when accurate radiometric measurements are a necessity. In agreement with such a need, this study focused on stray light correction of hyperspectral radiometers widely applied for above-water measurements to determine the remote-sensing reflectance (RRS). Stray light of sample radiometers was experimentally characterized and a correction algorithm was developed and applied to field measurements performed in the Mediterranean Sea. Results indicate that mean stray light corrections are appreciable, with values generally varying from -1% to +1% in the 400-700 nm spectral region for downward irradiance and sky radiance, and from -1% to +4% for total radiance from the sea. Mean corrections for data products such as RRS exhibit values that depend on water type varying between -0.5% and +1% in the blue-green spectral region, with peaks up to 9% in the red in eutrophic waters. The possibility of using one common stray light correction matrix for the analyzed class of radiometers was also investigated. Results centered on RRS support such a feasibility at the expense of an increment of the uncertainty typically well below 0.5% in the blue-green and up to 1% in the red, assuming sensors are based on spectrographs from the same production batch.

  12. Stray light effects in above-water remote-sensing reflectance from hyperspectral radiometers.

    PubMed

    Talone, Marco; Zibordi, Giuseppe; Ansko, Ilmar; Banks, Andrew Clive; Kuusk, Joel

    2016-05-20

    Stray light perturbations are unwanted distortions of the measured spectrum due to the nonideal performance of optical radiometers. Because of this, stray light characterization and correction is essential when accurate radiometric measurements are a necessity. In agreement with such a need, this study focused on stray light correction of hyperspectral radiometers widely applied for above-water measurements to determine the remote-sensing reflectance (RRS). Stray light of sample radiometers was experimentally characterized and a correction algorithm was developed and applied to field measurements performed in the Mediterranean Sea. Results indicate that mean stray light corrections are appreciable, with values generally varying from -1% to +1% in the 400-700 nm spectral region for downward irradiance and sky radiance, and from -1% to +4% for total radiance from the sea. Mean corrections for data products such as RRS exhibit values that depend on water type varying between -0.5% and +1% in the blue-green spectral region, with peaks up to 9% in the red in eutrophic waters. The possibility of using one common stray light correction matrix for the analyzed class of radiometers was also investigated. Results centered on RRS support such a feasibility at the expense of an increment of the uncertainty typically well below 0.5% in the blue-green and up to 1% in the red, assuming sensors are based on spectrographs from the same production batch. PMID:27411122

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

    NASA Technical Reports Server (NTRS)

    Royer, A.; Picard, G.; Arnaud, L.; Brucker, L.; Fily, M..

    2014-01-01

    Space-borne microwave radiometers are among the most useful tools to study snow and to collect information on the Antarctic climate. They have several advantages over other remote sensing techniques: high sensitivity to snow properties of interest (temperature, grain size, density), subdaily coverage in the polar regions, and their observations are independent of cloud conditions and solar illumination. Thus, microwave radiometers are widely used to retrieve information over snow-covered regions. For the Antarctic Plateau, many studies presenting retrieval algorithms or numerical simulations have assumed, explicitly or not, that the subpixel-scale heterogeneity is negligible and that the retrieved properties were representative of whole pixels. In this presentation, we investigate the spatial variations of brightness temperature over arange of a few kilometers in the Dome C area (Antarctic Plateau).

  14. Development of UHF radiometer

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

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

    SciTech Connect

    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

  16. LIRAS mission for lunar exploration by microwave interferometric radiometer: Moon's subsurface characterization, emission model and numerical simulator

    NASA Astrophysics Data System (ADS)

    Pompili, Sara; Silvio Marzano, Frank; Di Carlofelice, Alessandro; Montopoli, Mario; Talone, Marco; Crapolicchio, Raffaele; L'Abbate, Michelangelo; Varchetta, Silvio; Tognolatti, Piero

    2013-04-01

    The "Lunar Interferometric Radiometer by Aperture Synthesis" (LIRAS) mission is promoted by the Italian Space Agency and is currently in feasibility phase. LIRAS' satellite will orbit around the Moon at a height of 100 km, with a revisiting time period lower than 1 lunar month and will be equipped with: a synthetic aperture radiometer for subsurface sounding purposes, working at 1 and 3 GHz, and a real aperture radiometer for near-surface probing, working at 12 and 24 GHz. The L-band payload, representing a novel concept for lunar exploration, is designed as a Y-shaped thinned array with three arms less than 2.5 m long. The main LIRAS objectives are high-resolution mapping and vertical sounding of the Moon subsurface by applying the advantages of the antenna aperture synthesis technique to a multi-frequency microwave passive payload. The mission is specifically designed to achieve spatial resolutions less than 10 km at surface and to retrieve thermo-morphological properties of the Moon subsurface within 5 m of depth. Among LIRAS products are: lunar near-surface brightness temperature, subsurface brightness temperature gross profile, subsurface regolith thickness, density and average thermal conductivity, detection index of possible subsurface discontinuities (e.g. ice presence). The following study involves the preliminary design of the LIRAS payload and the electromagnetic and thermal characterization of the lunar subsoil through the implementation of a simulator for reproducing the LIRAS measurements in response to observations of the Moon surface and subsurface layers. Lunar physical data, collected after the Apollo missions, and LIRAS instrument parameters are taken as input for the abovementioned simulator, called "LIRAS End-to-end Performance Simulator" (LEPS) and obtained by adapting the SMOS End-to-end Performance Simulator to the different instrumental, orbital, and geophysical LIRAS characteristics. LEPS completely simulates the behavior of the satellite

  17. The beam filling error in the Nimbus 5 electronically scanning microwave radiometer observations of Global Atlantic Tropical Experiment rainfall

    NASA Technical Reports Server (NTRS)

    Short, David A.; North, Gerald R.

    1990-01-01

    A comparison of rain rates retrieved from the Nimbus 5 electronically scanning microwave radiometer brightness temperatures and observed from shipboard radars during the Global Atlantic Tropical Experiment (GATE) phase I shows that the beam filling error is the major source of discrepancy between the two. When averaged over a large scene (the GATE radar array, 400 km in diameter), the beam filling error is quite stable, being 50 percent of the observed rain rate. This suggests the simple procedure of multiplying retrieved rain rates by 2 (correction factor). A statistical model of the beam filling error is developed by envisioning an idealized instrument field-of-view that encompasses an entire gamma distribution of rain rates. A modeled correction factor near 2 is found for rain rate and temperature characteristics consistent with GATE conditions. The statistical model also suggests that the correction factor varies from 1.5 to 2.5 for suppressed to enhanced tropical convective regimes, and decreases to 1.5 as the freezing level and average depth of the rain column decreases to 2.5 km.

  18. Development of the Tropospheric Water Vapor and Cloud ICE (TWICE) Millimeter- and Sub-millimeter Wave Radiometer Instrument for 6U-Class Nanosatellites

    NASA Astrophysics Data System (ADS)

    Reising, S. C.; Kangaslahti, P.; Schlecht, E.; Bosch-Lluis, X.; Ogut, M.; Padmanabhan, S.; Cofield, R.; Chahat, N.; Brown, S. T.; Jiang, J. H.; Deal, W.; Zamora, A.; Leong, K.; Shih, S.; Mei, G.

    2015-12-01

    Measurements of upper-tropospheric water vapor and cloud ice at a variety of local times are critically needed to provide information not currently available from microwave sensors in sun-synchronous orbits. Such global measurements would enable increasingly accurate cloud and moisture simulations in global circulation models, improving both climate predictions and knowledge of their uncertainty. In addition, this capability would address the need for measurements of cloud ice particle size distribution and water content in both clean and polluted environments. Complementary measurements of aerosol pollution would allow investigation of its effects on cloud properties and climate. This is particularly important since the uncertainty in the aerosol effect on climate is at least four times as great as the uncertainty in greenhouse gas effects. To address this unmet need, a collaborative team among Colorado State University, Caltech Jet Propulsion Laboratory and Northrop Grumman Corporation is developing and fabricating the Tropospheric Water and Cloud ICE (TWICE) radiometer instrument. TWICE is designed with size, mass, power consumption and downlink data rate compatible with deployment aboard a 6U-Class nanosatellite. TWICE is advancing the state of the art of spaceborne millimeter- and submillimeter-wave radiometers by transitioning from Schottky mixer-based front ends to InP HEMT MMIC low-noise amplifier front ends, substantially reducing the radiometer's mass, volume and power consumption. New low-noise amplifiers and related front-end components are being designed and fabricated by JPL and Northrop Grumman based on InP HEMT MMIC technology up to 670 GHz. The TWICE instrument will provide 16 radiometer channels, including window frequencies near 240, 310 and 670 GHz to perform ice particle sizing and determine total ice water content, as well as four sounding channels each near 118 GHz for temperature sounding and near 183 GHz and 380 GHz for water vapor sounding

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

    NASA Technical Reports Server (NTRS)

    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

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

    NASA Astrophysics Data System (ADS)

    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

  1. Feasibility Study of Graphite Epoxy Antenna for a Microwave Limb Sounder Radiometer (MLSR)

    NASA Technical Reports Server (NTRS)

    1979-01-01

    Results are presented of a feasibility study to design graphite epoxy antenna reflectors for a jet propulsion laboratory microwave limb sounder instrument (MLSR). Two general configurations of the offset elliptic parabolic reflectors are presented that will meet the requirements on geometry and reflector accuracy. The designs consist of sandwich construction for the primary reflectors, secondary reflector support structure and cross-tie members between reflector pairs. Graphite epoxy materials of 3 and 6 plies are used in the facesheets of the sandwich. An aluminum honeycomb is used for the core. A built-in adjustment system is proposed to reduce surface distortions during assembly. The manufacturing and environmental effects are expected to result in surface distortions less than .0015 inch and pointing errors less than .002 degree.

  2. Model studies of the beam-filling error for rain-rate retrieval with microwave radiometers

    NASA Technical Reports Server (NTRS)

    Ha, Eunho; North, Gerald R.

    1995-01-01

    Low-frequency (less than 20 GHz) single-channel microwave retrievals of rain rate encounter the problem of beam-filling error. This error stems from the fact that the relationship between microwave brightness temperature and rain rate is nonlinear, coupled with the fact that the field of view is large or comparable to important scales of variability of the rain field. This means that one may not simply insert the area average of the brightness temperature into the formula for rain rate without incurring both bias and random error. The statistical heterogeneity of the rain-rate field in the footprint of the instrument is key to determining the nature of these errors. This paper makes use of a series of random rain-rate fields to study the size of the bias and random error associated with beam filling. A number of examples are analyzed in detail: the binomially distributed field, the gamma, the Gaussian, the mixed gamma, the lognormal, and the mixed lognormal ('mixed' here means there is a finite probability of no rain rate at a point of space-time). Of particular interest are the applicability of a simple error formula due to Chiu and collaborators and a formula that might hold in the large field of view limit. It is found that the simple formula holds for Gaussian rain-rate fields but begins to fail for highly skewed fields such as the mixed lognormal. While not conclusively demonstrated here, it is suggested that the notionof climatologically adjusting the retrievals to remove the beam-filling bias is a reasonable proposition.

  3. A feasibility study of a microwave water vapor measurement from a space probe along an occultation path

    NASA Technical Reports Server (NTRS)

    Longbothum, R. L.

    1975-01-01

    Stratospheric and mesospheric water vapor measurements were taken using the microwave lines at 22 GHz (22.235 GHz) and 183 GHz (183.31 GHz). The resonant cross sections for both the 22 GHz and the 183 GHz lines were used to model the optical depth of atmospheric water vapor. The range of optical depths seen by a microwave radiometer through the earth's limb was determined from radiative transfer theory. Radiometer sensitivity, derived from signal theory, was compared with calculated optical depths to determine the maximum height to which water vapor can be measured using the following methods: passive emission, passive absorption, and active absorption. It was concluded that measurements using the 22 GHz line are limited to about 50 km whereas the 183 GHz line enables measurements up to and above 100 km for water vapor mixing ratios as low as 0.1 ppm under optimum conditions.

  4. Influence of (FeO + TiO2) abundance on the thermal emission from the lunar regolith using Chang'E-2 microwave radiometer data

    NASA Astrophysics Data System (ADS)

    Meng, Zhiguo; Ping, Jinsong; Xu, Yi; Cai, Zhanchuan; Zheng, Yongchun

    Abstract:The microwave radiometer data obtained from Chang’E-2 mission (CELMS data) has provided new opportunity to study the influence of the (FeO+TiO2) abundance on the microwave thermal emission of the lunar regolith. In this paper, the radiative transfer simulation is employed to study the change of the brightness temperature with (FeO+TiO2) abundance at different frequencies and surface temperature. The (FeO+TiO2) abundance are derived from Clementine UV-VIS data and the samples from Apollo, Luna and Surveyor projects. The simulation results along the Equator indicate that the (FeO+TiO2) abundance has strong impact on the microwave thermal emission of the lunar regolith. However, the data along the Longitude 0° shows that the (FeO+TiO2) abundance is not the dominant influential factor of the microwave thermal emission of the lunar regolith. Specifically, the abnormal brightness temperature at 160°W (Unnamed crater), 138°W (Crater Vavilov), 125°W (Crater Hertzsprung), 116°E (Crater Abul Wáfa), 119°E (Crater Heron), 130°E (Crater Catena Gregory) and 140°E (Crater Catena Mendeleev) shows that the (FeO+TiO2) abundance is not the only influential factor for the observed brightness temperature. In addition, the correlations between the four-channel brightness temperature and the (FeO+TiO2) abundance in Apollo landing site and along the Equator both indicate that the (FeO+TiO2) abundance is slightly decreasing with depth. The research is essential for the inversion of the lunar regolith parameters with the microwave radiometer data from Chang’E satellites. Keywords: lunar regolith, microwave thermal emission, CELMS data, (FeO+TiO2) abundance

  5. PHOCUS radiometer

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

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

  6. PHOCUS radiometer

    NASA Astrophysics Data System (ADS)

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

    2012-01-01

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

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Technical Reports Server (NTRS)

    Meneghini, R.

    2005-01-01

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

  9. Snow parameters from Nimbus-6 electrically scanned microwave radiometer. [(ESMR-6)

    NASA Technical Reports Server (NTRS)

    Abrams, G.; Edgerton, A. T.

    1977-01-01

    Two sites in Canada were selected for detailed analysis of the ESMR-6/ snow relationships. Data were analyzed for February 1976 for site 1 and January, February and March 1976 for site 2. Snowpack water equivalents were less than 4.5 inches for site 1 and, depending on the month, were between 2.9 and 14.5 inches for site 2. A statistically significant relationship was found between ESMR-6 measurements and snowpack water equivalents for the Site 2 February and March data. Associated analysis findings presented are the effects of random measurement errors, snow site physiolography, and weather conditions on the ESMR-6/snow relationship.

  10. Microwave treatment of naphthenic acids in water.

    PubMed

    Mishra, Sabyasachi; Meda, Venkatesh; Dalai, Ajay K; Headley, John V; Peru, Kerry M; McMartin, Dena W

    2010-08-01

    Naphthenic acids (NAs) are natural constituents of bitumen and crude oil. These compounds are concentrated as part of the oil sands process water (OSPW) during petroleum refining and separation from oil sands. NAs are considered among the major water contaminants in OSPW due to their toxicity and environmental recalcitrance. A laboratory scale microwave system was developed and experiments were conducted to determine the efficiency of NA degradation during microwave treatment. The effects of water source and quality (deionized lab water and river water) and of TiO(2) catalyst in the degradation process were also investigated. Degradation kinetic parameters for both total NAs and individual z-family were calculated. The microwave system degraded OSPW NAs and commercial Fluka NAs in river water in the presence of TiO(2) rapidly, producing half-life values of 3.32 and 3.61 hours, respectively. Toxicity assessments of the NA samples pre-and post-treatment indicated that the microwave system reduced overall toxicity of water containing Fluka NAs from high (5 min. IC(50) v/v = 15.85%) to moderate (5 min. IC(50) v/v = 36.45%) toxicity levels. However, a slight increase in toxicity was noted post-treatment in OSPW NAs.

  11. Soil moisture retrievals from the WindSat spaceborne polarimetric microwave radiometer

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Surface soil moisture plays an important role in many water- and energy-balanced related studies. It is an important parameter in several applications, such as numerical weather predictions, global change modelling, forecasting of surface runoff and modelling of evaporation. Soil moisture is conside...

  12. Millimeter-wave Radiometer for High Sensitivity Water Vapor Profiling in Arid Regions

    SciTech Connect

    Pazmany, Andrew

    2006-11-09

    Abstract - ProSensing Inc. has developed a G-band (183 GHz) water Vapor Radiometer (GVR) for long-term, unattended measurements of low concentrations of atmospheric water vapor and liquid water. Precipitable water vapor and liquid water path are estimated from zenith brightness temperatures measured from four double-sideband receiver channels, centered at 183.31 1, 3 and 7, and 14 GHz. A prototype ground-based version of the instrument was deployed at the DOE ARM program?s North Slope of Alaska site near Barrow AK in April 2005, where it collected data continuously for one year. A compact, airborne version of this instrument, packaged to operate from a standard 2-D PMS probe canister, has been tested on the ground and is scheduled for test flights in the summer of 2006. This paper presents design details, laboratory test results and examples of retrieved precipitable water vapor and liquid water path from measured brightness temperature data.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  15. Airborne full polarization radiometry using the MSFC Advanced Microwave Precipitation Radiometer (AMPR)

    NASA Technical Reports Server (NTRS)

    Gasiewski, Al J.; Kunkee, D. B.

    1993-01-01

    The applications of vertically and horizontally polarized brightness temperatures in both atmospheric and surface remote sensing have been long recognized by many investigators, particularly those studying SMMR and SSM/I data. Here, the large contrast between the first two Stokes' parameters (T(sub V) and T(sub H)) can be used for detection of sea ice, measurement of ocean surface wind speed, and measurement of cloud and water vapor opacity. High-resolution aircraft data from instruments such as the NASA/MSFC AMPR is crucial for verifying radiative transfer models and developing retrieval algorithms. Currently, the AMPR is outfitted with single-polarization channels at 10, 18, 37 and 85 GHz. To increase its utility, it is proposed that additional orthogonal linearly polarized channels be added to the AMPR. Since the AMPR's feedhorns are already configured for dual orthogonal linearly polarized modes, this would require only a duplication of the currently existing receivers. To circumvent the resulting polarization basis skew caused by the cross-track scanning mechanism, the technique of Electronic Polarization Basis Rotation is proposed to be implemented. Implementation of EPBR requires precise measurement of the third Stokes parameter and will eliminate polarization skew by allowing the feedhorn basis skew angle to be corrected in software. In addition to upgrading AMPR to dual polarization capability (without skew), the modifications will provide an opportunity to demonstrate EPBR on an airborne platform. This is a highly desirable intermediate step prior to satellite implementation.

  16. The natural oscillations in stratospheric ozone observed by the GROMOS microwave radiometer at the NDACC station Bern

    NASA Astrophysics Data System (ADS)

    Moreira, Lorena; Hocke, Klemens; Navas-Guzmán, Francisco; Eckert, Ellen; von Clarmann, Thomas; Kämpfer, Niklaus

    2016-08-01

    A multilinear parametric regression analysis was performed to assess the seasonal and interannual variations of stratospheric ozone profiles from the GROMOS (GROund-based Millimeter-wave Ozone Spectrometer) microwave radiometer at Bern, Switzerland (46.95° N, 7.44° E; 577 m). GROMOS takes part in the Network for the Detection of Atmospheric Composition Change (NDACC). The study covers the stratosphere from 50 to 0.5 hPa (from 21 to 53 km) and extends over the period from January 1997 to January 2015. The natural variability was fitted during the regression analysis through the annual and semi-annual oscillations (AO, SAO), the quasi-biennial oscillation (QBO), the El Niño-Southern Oscillation (ENSO) and the solar activity cycle. Seasonal ozone variations mainly appear as an annual cycle in the middle and upper stratosphere and a semi-annual cycle in the upper stratosphere. Regarding the interannual variations, they are primarily present in the lower and middle stratosphere. In the lower and middle stratosphere, ozone variations are controlled predominantly by transport processes, due to the long lifetime of ozone, whereas in the upper stratosphere its lifetime is relatively short and ozone is controlled mainly by photochemistry. The present study shows agreement in the observed naturally induced ozone signatures with other studies. Further, we present an overview of the possible causes of the effects observed in stratospheric ozone due to natural oscillations at a northern midlatitude station. For instance regarding the SAO, we find that polar winter stratopause warmings contribute to the strength of this oscillation since these temperature enhancements lead to a reduction in upper stratospheric ozone. We have detected a strong peak amplitude of about 5 % for the solar cycle in lower stratospheric ozone for our 1.5 cycles of solar activity. Though the 11-year ozone oscillation above Bern is in phase with the solar cycle, we suppose that the strong amplitude is

  17. Data Assimilation of Space-Based Passive Microwave Soil Moisture Retrievals and the Correction for a Dynamic Open Water Fraction

    NASA Astrophysics Data System (ADS)

    Gouweleeuw, Ben T.; van Dijik, Albert I. J. M.; Renzullo, Luigi J.

    2011-01-01

    The large observation footprint of low-frequency satellite microwave emissions complicates the interpretation of near-surface soil moisture retrievals. Temporal changes in the extent of smaller water bodies can cause significant and dynamic biases. We analysed the influence of open water on near-surface soil moisture retrievals from the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) for three areas in Oklahoma, USA. Differences between on-ground observations or model estimates and AMSR-E retrievals were compared to dynamic estimates of open water fraction derived from the Moderate Resolution Imaging Spectroradiometer (MODIS). The comparison indicates that seasonally varying biases of up to 20% soil water content can be attributed to the presence of relatively small areas (<5%) of open water in or near the sensor footprint. The results presented here feed into the discussion if the retrieved variable or the observed microwave brightness temperature is most suitable for assimilation with simulated fields from land surface models.

  18. Another Look at the Optimum Frequencies for a Water Vapor Radiometer

    NASA Technical Reports Server (NTRS)

    Resch, G. M.

    1984-01-01

    A water vapor radiometer is used to estimate the columnar content of atmospheric water vapor or equivalently the line-of-sight path delay due to water vapor. Two measurement channels are used in order to separate the effects of the liquid and vapor phases of water. The efficiency of the path delay or columnar vapor estimate is dependent on the choice of on-line frequency channel. Previous analysis of this problem has suggested frequencies from 20.3 to 21 GHz. The frequency that yields the minimum error in the inversion algorithm is shown here to be both site and season dependent. Hence, the concept of an optimum frequency must represent an averaging process over the entire range of meteorological conditions that is expected. For a range of sites and condition representing a cross section of the continental United States the optimum on-line frequency seems to be 20.6 GHz.

  19. Snow water equivalent determination by microwave radiometry

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    One of the most important parameters for accurate snowmelt runoff prediction is snow water equivalent (SWE) which is contentionally monitored using observations made at widely scattered points in or around specific watersheds. Remote sensors which provide data with better spatial and temporal coverage can be used to improve the SWE estimates. Microwave radiation, which can penetrate through a snowpack, may be used to infer the SWE. Calculations made from a microscopic scattering model were used to simulate the effect of varying SWE on the microwave brightness temperature. Data obtained from truck mounted, airborne and spaceborne systems from various test sites were studied. The simulated SWE compares favorable with the measured SWE. In addition, whether the underlying soil is frozen or thawed can be discriminated successfully on the basis of the polarization of the microwave radiation.

  20. Comparison of data from the Scanning Multifrequency Microwave Radiometer (SMMR) with data from the Advanced Very High Resolution Radiometer (AVHRR) for terrestrial environmental monitoring - An overview

    NASA Technical Reports Server (NTRS)

    Townshend, J. R. G.; Choudhury, B. J.; Tucker, C. J.; Giddings, L.; Justice, C. O.

    1989-01-01

    Comparison between the microwave polarized difference temperature (MPDT) derived from 37 GHz band data and the normalized difference vegetation index (NDVI) derived from near-infrared and red bands, from several empirical investigations are summarized. These indicate the complementary character of the two measures in environmental monitoring. Overall the NDVI is more sensitive to green leaf activity, whereas the MPDT appears also to be related to other elements of the above-ground biomass. Monitoring of hydrological phenomena is carried out much more effectively by the MPDT. Further work is needed to explain spectral and temporal variation in MPDT both through modelling and field experiments.

  1. Remote sensing of atmospheric water vapor, liquid water and wind speed at the ocean surface by passive microwave techniques from the Nimbus-5 satellite

    NASA Technical Reports Server (NTRS)

    Chang, A. T. C.; Wilheit, T. T.

    1977-01-01

    The microwave brightness temperature measurements for Nimbus-5 electrically scanned microwave radiometer and Nimbus E microwave spectrometer are used to retrieve the atmospheric water vapor, liquid water and wind speed by a quasi-statistical retrieval technique. It is shown that the brightness temperature can be utilized to yield these parameters under various weather conditions. Observations at 19.35 GHz, 22.235 GHz and 31.4 GHz were input to the regression equations. The retrieved values of these parameters for portions of two Nimbus-5 orbits are presented. Then comparison between the retrieved parameters and the available observations on the total water vapor content and the surface wind speed are made. The estimated errors for retrieval are approximately 0.15 g/sq cm for water vapor content, 6.5 mg/sq cm for liquid water content and 6.6 m/sec for surface wind speed.

  2. Hurricane Imaging Radiometer

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

    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.

  4. Remote Sensing Observatory Validation of Surface Soil Moisture Using Advanced Microwave Scanning Radiometer E, Common Land Model, and Ground Based Data: Case Study in SMEX03 Little River Region, Georgia, U.S.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Optimal soil moisture estimation may be characterized by inter-comparisons among remotely sensed measurements, ground-based measurements, and land surface models. In this study, we compared soil moisture from Advanced Microwave Scanning Radiometer E (AMSR-E), ground-based measurements, and Soil-Vege...

  5. Ten Thousand Solar Constants Radiometer

    NASA Technical Reports Server (NTRS)

    Kendall, J. M., Sr.

    1985-01-01

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

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

    NASA Astrophysics Data System (ADS)

    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

  7. Solar-Collector Radiometer

    NASA Technical Reports Server (NTRS)

    Kendall, J. M., Jr

    1984-01-01

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

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

    NASA Technical Reports Server (NTRS)

    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.

  9. Wave number spectra from temperature-humidity infrared radiometer 6.7-micron water vapor data

    NASA Technical Reports Server (NTRS)

    Manney, Gloria L.; Stanford, John L.

    1990-01-01

    Wave number spectra from Nimbus 7 temperature-humidity infrared radiometer 6.7-micron water vapor data are analyzed using series 4800 km long, in regions free of high clouds and frontal zones. In these regions, the brightness temperatures approximate temperatures on a water vapor isosteric (constant density) surface, rather than averages over a broad vertical layer. Power above the noise can be extracted down to wavelengths of about 60 km. Fitting the power spectrum versus horizontal wave number k to a k to the -nth power law for wavelengths from 60 to a few hundred kilometers gives slopes of n = 2.7 to 3.0, depending on the exact wave numbers that are fitted. Thunderstorms and convective cloud systems may constitute an energy source for the reverse energy cascade which produces a -5/3 spectral slope. The results suggest that when these features are not present, the enstrophy-cascading process that gives a -3 slope may govern the motion at scales smaller than it has heretofore been observed.

  10. [Microwave emission from water in bioanalytical systems].

    PubMed

    Ivanov, Yu D; Malsagova, K A; Tatur, V Yu; Vesnin, S G; Ivanova, N D; Ziborov, V S

    2015-01-01

    Mechanical stimulation of aqueous protein solution was found to be accompanied by electromagnetic radiation in the superhigh frequency range. This radiation was observed at solution temperatures near the phase transitions of water. This effect may occur in various bioanalytical systems, associated with injection of aqueous solutions in these systems, and may have impact on the results of bioalytical measurements. The discovered effect of generation of nonequilibrium microwave emission of water medium (which is the main component of the organism) in the 38-39°C temperature range, i.e. in the range of elevated temperature of the organism (which accompanies pathological condition in humans upon inflammatory diseases, i.e., infactious etc.) may be used for development of new non-invasive methods of disease diagnostics. PMID:27116882

  11. [Microwave emission from water in bioanalytical systems].

    PubMed

    Ivanov, Yu D; Malsagova, K A; Tatur, V Yu; Vesnin, S G; Ivanova, N D; Ziborov, V S

    2015-01-01

    Mechanical stimulation of aqueous protein solution was found to be accompanied by electromagnetic radiation in the superhigh frequency range. This radiation was observed at solution temperatures near the phase transitions of water. This effect may occur in various bioanalytical systems, associated with injection of aqueous solutions in these systems, and may have impact on the results of bioalytical measurements. The discovered effect of generation of nonequilibrium microwave emission of water medium (which is the main component of the organism) in the 38-39°C temperature range, i.e. in the range of elevated temperature of the organism (which accompanies pathological condition in humans upon inflammatory diseases, i.e., infactious etc.) may be used for development of new non-invasive methods of disease diagnostics.

  12. New Technique for Retrieving Liquid Water Path over Land using Satellite Microwave Observations

    SciTech Connect

    Deeter, M.N.; Vivekanandan, J.

    2005-03-18

    We present a new methodology for retrieving liquid water path over land using satellite microwave observations. As input, the technique exploits the Advanced Microwave Scanning Radiometer for earth observing plan (EOS) (AMSR-E) polarization-difference signals at 37 and 89 GHz. Regression analysis performed on model simulations indicates that over variable atmospheric and surface conditions the polarization-difference signals can be simply parameterized in terms of the surface emissivity polarization difference ({Delta}{var_epsilon}), surface temperature, liquid water path (LWP), and precipitable water vapor (PWV). The resulting polarization-difference parameterization (PDP) enables fast and direct (noniterative) retrievals of LWP with minimal requirements for ancillary data. Single- and dual-channel retrieval methods are described and demonstrated. Data gridding is used to reduce the effects of instrumental noise. The methodology is demonstrated using AMSR-E observations over the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site during a six day period in November and December, 2003. Single- and dual-channel retrieval results mostly agree with ground-based microwave retrievals of LWP to within approximately 0.04 mm.

  13. Comparison of ClO measurements by airborne and spaceborne microwave radiometers in the Arctic winter stratosphere 1993

    SciTech Connect

    Crewell, S.; Fabian, R.; Kuenzi, K.

    1995-06-15

    In February 1993 measurements of chlorine monoxide ClO, one of the key substances in catalytic ozone destruction, were performed over Scandinavia by two microwave receivers, the Submillimeter Atmospheric Sounder (SUMAS) on board the German research aircraft FALCON and the Microwave Limb Sounder (MLS) on board the Upper Atmospheric Research Satellite (UARS). High ClO concentrations (>1 ppb) inside the polar vortex at approximately 20km altitude were detected by both experiments. A comparison shows good agreement of both sensors in the location of enhanced ClO. 11 refs., 5 figs.

  14. Maser radiometer for cosmic background radiation anisotropy measurements

    NASA Astrophysics Data System (ADS)

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

    1982-06-01

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

  15. Maser radiometer for cosmic background radiation anisotropy measurements

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

  16. Remote sensing of precipitable water over the oceans from Nimbus-7 microwave measurements

    NASA Technical Reports Server (NTRS)

    Prabhakara, C.; Change, H. D.; Chang, A. T. C.

    1981-01-01

    Global maps of precipitable water over derived from scanning multichannel microwave radiometer (SMMR) data reveal salient features associated with ocean currents and the large scale general circulation in the atmosphere. Nimbus-7 SMMR brightness temperature measurements in the 21 and 18 GHz channels are used to sense the precipitable water in the atmospheric over oceans. The difference in the brightness temperature (T sub 21 -T sub 18), both in the horizontal and vertical polarization, is found to be essentially a function of the precipitable water in the atmosphere. An equation, based on the physical consideration of the radiative transfer in the microwave region, is developed to relate the precipitable water to (T sub 21 - T sub 18). It shows that the signal (T sub 21- T sub 18) does not suffer severely from the noise introduced by variations in the sea surface temperature, surface winds, and liquid water content in non rain clouds. The rms deviation between the estimated precipitable water from SMMR data and that given by the closely coincident ship radiosondes is about 0.25 g/ sq cm

  17. Diurnal physical temperature at Sinus Iridum area retrieved from observations of Chinese Chang'E-1 microwave radiometer

    NASA Astrophysics Data System (ADS)

    Gong, Xiaohui; Jin, Ya-Qiu

    2012-04-01

    According to the incidence and azimuth angles of the Sun during observations of Chinese Chang'E-1 (CE-1) lunar satellite, brightness temperatures (Tb) at different lunar local time observed by the CE-1 multi-channel radiometers, especially at the Sinus Iridum (i.e. Bay of Rainbow) area, are collected from the transformation between the principal and local coordinates at the observed site, which demonstrates the Tb distribution and its diurnal variation. Based on a three-layer radiative transfer model of the lunar media, the CE-1 Tb data at 19.35 and 37.0 GHz channels are applied to invert the physical temperatures of both the dust and the regolith layer at Sinus Iridum area, where might be the CE-3 landing site, at different lunar local times. The physical temperature variations with the lunar local time and other geophysical parameters of lunar layered media are discussed.

  18. First continuous time series of tropical, mid-latitudinal and polar middle-atmospheric wind profile measurements with a ground-based microwave Doppler-spectro-radiometer

    NASA Astrophysics Data System (ADS)

    Rüfenacht, Rolf; Kämpfer, Niklaus; Murk, Axel; Eriksson, Patrick; Buehler, Stefan A.; Kivi, Rigel; Keckhut, Philippe; Hauchecorne, Alain; Duflot, Valentin

    2014-05-01

    Wind is one of the key parameters for the characterisation of the atmosphere and the understanding of its dynamics. Despite this, no continuously operating instrument for wind measurements in the upper stratosphere and lower mesosphere existed so far. Aiming to contribute to the closing of this data gap by exploiting the potential of microwave radiometry the Institute of Applied Physics of the University of Bern built a ground-based 142 GHz Doppler-spectro-radiometer with the acronym WIRA (WInd RAdiometer). WIRA is specifically designed for the measurement of middle-atmospheric horizontal wind and is sensitive to the altitude range between 35 and 70 km. The architecture of the radiometer is fairly compact what 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. The operational use of WIRA started in September 2010. Since a technical upgrade in autumn 2012 which drastically increased the signal to noise ratio of the instrument, the meridional component is permanently measured along with the zonal wind to get a full picture of the horizontal wind field. During the last year the wind retrieval algorithm has been entirely rebuilt and tested. It is now based on the optimal estimation technique (OEM) and uses an upgraded version of the ARTS/QPACK radiative transfer and inversion model. Time series of middle-atmospheric wind from measurement campaigns of 7 to 11 months duration at mid and high latitude sites (Bern, 46°57' N, 7°26' E; Sodankylä, 67°22' N, 26°38' E; Observatoire de Haute-Provence, 43°56' N, 5°43' E) have been obtained. In September 2013 WIRA was moved to Observatoire du Maïdo (21°04' S, 55°23' E) to study the dynamics of the tropical middle atmosphere. The measurements have been compared to the data from the ECMWF model. Generally good agreement has been found in the stratosphere, however systematic discrepancies exist in the mesosphere. At the

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

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

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

  20. Measurement of atmospheric precipitable water using a solar radiometer. [water vapor absorption effects

    NASA Technical Reports Server (NTRS)

    Pitts, D. E.; Dillinger, A. E.; Mcallum, W. E.

    1974-01-01

    A technique is described and tested that allows the determination of atmospheric precipitable water from two measurements of solar intensity: one in a water-vapor absorption band and another in a nearby spectral region unaffected by water vapor.

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

    SciTech Connect

    Caddeau, MP

    2010-06-23

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

  2. High frequency thermal emission from the lunar surface and near surface temperature of the Moon from Chang’E-2 microwave radiometer

    NASA Astrophysics Data System (ADS)

    Fang, Tuo; Fa, Wenzhe

    2014-04-01

    Near surface temperature of the Moon and thermal behaviors of the lunar regolith can provide important information for constraining thermal and magmatic evolution models of the Moon and engineering constrains for in situ lunar exploration system. In this study, China’s Chang’E-2 (CE-2) microwave radiometer (MRM) data at high frequency channels are used to investigate near surface temperature of the Moon given the penetration ability of microwave into the desiccated and porous lunar regolith. Factors that affect high frequency brightness temperature (TB), such as surface slope, solar albedo and dielectric constant, are analyzed first using a revised Racca’s temperature model. Radiative transfer theory is then used to model thermal emission from a semi-infinite regolith medium, with considering dielectric constant and temperature profiles within the regolith layer. To decouple the effect of diurnal temperature variation in the uppermost lunar surface, diurnal averaged brightness temperatures at high frequency channels are used to invert mean diurnal surface and subsurface temperatures based on their bilinear profiles within the regolith layer. Our results show that, at the scale of the spatial resolution of CE-2 MRM, surface slope of crater wall varies typically from about 20° to 30°, and this causes a variation in TB about 10-15 K. Solar albedo can give rise to a TB difference of about 5-10 K between maria and highlands, whereas a ∼2-8 K difference can be compensated by the dielectric constant on the other hand. Inversion results indicate that latitude (ϕ) variations of the mean diurnal surface and subsurface temperatures follow simple rules as cos0.30ϕ and cos0.36ϕ, respectively. The inverted mean diurnal temperature profiles at the Apollo 15 and 17 landing sites are also compared with the Apollo heat flow experiment data, showing an inversion uncertainty <4 K for surface temperature and <1 K for subsurface temperature.

  3. Resolution Enhancement of Spaceborne Radiometer Images

    NASA Technical Reports Server (NTRS)

    Krim, Hamid

    2001-01-01

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

  4. Monitoring snowpack properties by passive microwave sensors on board of aircraft and satellites

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

    Snowpack properties such as water equivalent and snow wetness may be inferred from variations in measured microwave brightness temperatures. This is because the emerged microwave radiation interacts directly with snow crystals within the snowpack. Using vertically and horizontally polarized brightness temperatures obtained from the multifrequency microwave radiometer (MFMR) on board a NASA research aircraft and the electrical scanning microwave radiometer (ESMR) and scanning multichannel microwave radiometer (SMMR) on board the Nimbus 5, 6, and 7 satellites, linear relationships between snow depth or water equivalent and microwave brightness temperature were developed. The presence of melt water in the snowpack generally increases the brightness temperatures, which can be used to predict snowpack priming and timing of runoff.

  5. Estimation of snow depth and snow water equivalent distribution using airborne microwave radiometry in the Binggou Watershed, the upper reaches of the Heihe River basin

    NASA Astrophysics Data System (ADS)

    Che, Tao; Dai, Liyun; Wang, Jian; Zhao, Kai; Liu, Qiang

    2012-07-01

    We estimated the spatial distribution of snow depth/snow water equivalent (SD/SWE) in a mountainous watershed (Binggou, which is in the upper reaches of the Heihe River basin) by an airborne microwave radiometry observational experiment. Two microwave radiometers measuring at K band (18.7 GHz) and Ka band (36 GHz) were used to estimate the volume scatter from snowpacks and infer SD and SWE. Simultaneously, the snow physical properties (such as snow depth, density, grain size and temperature) over four sites were measured, and a simple multi-layer sample scheme was adopted to obtain the stratigraphic information. The microwave emission model of layered snowpacks (MEMLS) was used to simulate the brightness temperatures of snow cover for each measurement point. By comparing TB data that were simulated by MEMLS and observed by radiometers on the aircraft over the four sites, we obtained the retrieval algorithms of SD and SWE based on brightness temperature differences (TBD) at the K- and Ka-bands that are suitable to the local snow properties. The validation shows that the mean absolute and relative errors of SD estimates are approximately 3.5 cm and 14.8%, respectively. SWE from airborne microwave radiometers show that blowing snow and sun radiation are two main factors that determine the spatial distribution of SWE in Binggou Watershed. The local angle of incidence of the microwave radiometer observation can be influenced by mountainous topography, and a sensitivity analysis suggests that changes in the local angle of incidence (e.g., the nominal angle of incidence) will not significantly influence the estimation of SD/SWE. The snow's stratigraphic condition is not an important factor for estimating SD/SWE in this study because the snow was not very deep in the Binggou Watershed. However, the field sampling scheme should be given more attention to obtain the spatial variations of snow properties and to support pixel-by-pixel validation in next field campaign.

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

    NASA Astrophysics Data System (ADS)

    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.

  7. Microwave remote sensing of soil moisture

    NASA Technical Reports Server (NTRS)

    Shiue, J. C.; Wang, J. R.

    1988-01-01

    Knowledge of soil moisture is important to many disciplines, such as agriculture, hydrology, and meteorology. Soil moisture distribution of vast regions can be measured efficiently only with remote sensing techniques from airborne or satellite platforms. At low microwave frequencies, water has a much larger dielectric constant than dry soil. This difference manifests itself in surface emissivity (or reflectivity) change between dry and wet soils, and can be measured by a microwave radiometer or radar. The Microwave Sensors and Data Communications Branch is developing microwave remote sensing techniques using both radar and radiometry, but primarily with microwave radiometry. The efforts in these areas range from developing algorithms for data interpretation to conducting feasibility studies for space systems, with a primary goal of developing a microwave radiometer for soil moisture measurement from satellites, such as EOS or the Space Station. These efforts are listed.

  8. The forward scattering of microwave solar radiation from a water surface

    NASA Technical Reports Server (NTRS)

    Wentz, F. J.

    1978-01-01

    The forward scattering of microwave solar radiation from both smooth and rough water surfaces is computed. The smooth surface is assumed specular, and the rough surface is represented by a two-scale surface, for which two small-scale perturbation parameters, 0.10 and 0.25, are considered. The contribution of the scattered sunlight to the antenna temperature is found using the scalar approximation, and the results are compared with radiometer measurements. The overall agreement is good, but in some cases the smooth-surface measurements are higher than the computations. This discrepancy possibly indicates an absolute calibration error or a slight misalignment of the antennas' boresights. The computations for the two perturbation parameters bracket the rough-surface measurements except when the sun's mirror image is far removed from the boresight direction. The small disagreement in this case may be due to a peaked large-scale slope distribution.

  9. Trend analysis of the 20-year time series of stratospheric ozone profiles observed by the GROMOS microwave radiometer at Bern

    NASA Astrophysics Data System (ADS)

    Moreira, L.; Hocke, K.; Eckert, E.; von Clarmann, T.; Kämpfer, N.

    2015-10-01

    The ozone radiometer GROMOS (GROund-based Millimeter-wave Ozone Spectrometer) has been performing continuous observations of stratospheric ozone profiles since 1994 above Bern, Switzerland (46.95° N, 7.44° E, 577 m). GROMOS is part of the Network for the Detection of Atmospheric Composition Change (NDACC). From November 1994 to October 2011, the ozone line spectra were measured by a filter bench (FB). In July 2009, a fast Fourier transform spectrometer (FFTS) was added as a back end to GROMOS. The new FFTS and the original FB measured in parallel for over 2 years. The ozone profiles retrieved separately from the ozone line spectra of FB and FFTS agree within 5 % at pressure levels from 30 to 0.5 hPa, from October 2009 to August 2011. A careful harmonisation of both time series has been carried out by taking the FFTS as the reference instrument for the FB. This enables us to assess the long-term trend derived from stratospheric ozone observations at Bern. The trend analysis was performed by using a robust multilinear parametric trend model which includes a linear term, the solar variability, the El Niño-Southern Oscillation (ENSO) index, the quasi-biennial oscillation (QBO), the annual and semi-annual oscillation and several harmonics with period lengths between 3 and 24 months. Over the last years, some experimental and modelling trend studies have shown that the stratospheric ozone trend is levelling off or even turning positive. With our observed ozone profiles, we are able to support this statement by reporting a statistically significant trend of +3.14 % decade-1 at 4.36 hPa (37.76 km), covering the period from January 1997 to January 2015, above Bern. Additionally, we have estimated a negative trend over this period of -3.94 % decade-1 at 0.2 hPa (59 km).

  10. Trend analysis of the 20 years time series of stratospheric ozone profiles observed by the GROMOS microwave radiometer at Bern

    NASA Astrophysics Data System (ADS)

    Moreira, L.; Hocke, K.; Eckert, E.; von Clarmann, T.; Kämpfer, N.

    2015-06-01

    The ozone radiometer GROMOS (GROund-based Millimeterwave Ozone Spectrometer) performs continuous observations of stratospheric ozone profiles since 1994 above Bern, Switzerland. GROMOS is part of the Network for the Detection of Atmospheric Composition Change (NDACC). From November 1994 to October 2011, the ozone line spectra were measured by a filter bench (FB). In July 2009, a Fast-Fourier-Transform spectrometer (FFTS) has been added as backend to GROMOS. The new FFTS and the original FB measured in parallel for over two years. The ozone profiles retrieved separately from the ozone line spectra of FB and FFTS agree within 5 % at pressure levels from 30 to 0.5 hPa, from October 2009 to August 2011. A careful harmonisation of both time series has been carried out by taking the FFTS as the reference instrument for the FB. This enables us to assess the long-term trend derived from more than 20 years of stratospheric ozone observations at Bern. The trend analysis has been performed by using a robust multilinear parametric trend model which includes a linear term, the solar variability, the El Niño-Southern Oscillation (ENSO) index, the quasi-biennial oscillation (QBO), the annual and semi-annual oscillation and several harmonics with period lengths between 3 and 24 months. Over the last years, some experimental and modelling trend studies have shown that the stratospheric ozone trend is levelling off or even turning positive. With our observed ozone profiles, we are able to support this statement by reporting a statistically significant trend of +3.14 % decade-1 at 4.36 hPa, covering the period from January 1997 to January 2015, above Bern. Additionally, we have estimated a negative trend over this period of -3.94 % decade-1 at 0.2 hPa.

  11. First Three Years of the Microwave Radiometer Aboard ENVISAT: In-Flight Calibration, Processing and Validation of the Geophysical Products

    NASA Astrophysics Data System (ADS)

    Obligis, E.; Eymard, L.; Tran, N.; Labroue, S.; Femenias, P.

    2006-07-01

    The Envisat microwave rad iometer is designed to correct th e satellite altimeter data for the excess path delay due to tropospheric hu mid ity. Neural networks have been used to formulate the inv ersion algorithm to retrieve this quantity from the measured brightness temp eratures. Th e learning database has been built w ith ECMWF (European Center for Med ium Range Weather Forecast) an alyses and simulated brightness temp eratur es by a r adiative tr ansfer model. The in-flight calibration has been performed in a consisten t way by ad justing measur emen ts on simulated brightness temperatures. Fin ally, co incident rad iosonde measurements ar e used to validate th e Envisat wet tropospheric correction, and this compar ison shows the good performances of the method.

  12. An assessment of microwave absorption models and retrievals of cloud liquid water using clear-sky data

    NASA Astrophysics Data System (ADS)

    Marchand, Roger; Ackerman, Thomas; Westwater, Ed R.; Clough, Shepard A.; Cady-Pereira, Karen; Liljegren, James C.

    2003-12-01

    Passive microwave radiometers have a long history in the remote sensing of atmospheric liquid and water vapor. Retrievals of these quantities are sensitive to variations in pressure and temperature of the liquid and water vapor. Rather than use a statistical or climatological approach to account for the natural variability in atmospheric pressure and temperature, additional information on the atmospheric profile at the time of the radiometer measurements can be directly incorporated into the retrieval process. Such an approach has been referred to in the literature as a "physical-iterative" solution. This paper presents an assessment of the accuracy of the column liquid water path that can be expected using such an iterative technique as a result of uncertainties in the microwave emissions from oxygen and water vapor. It is shown that the retrieval accuracy is influenced by the accuracy of the instrument measurements and the quality of the atmospheric profiles of temperature and pressure, as one would expect. However, also critical is the uncertainty in the absorption coefficients used in the underlying microwave radiative transfer model. The uncertainty in the absorption coefficients is particularly problematic in that it may well bias the liquid water retrieval. The differences between three absorption models examined in this paper are equivalent to a bias of 15 to 30 g/m2, depending on the total column water vapor. An examination of typical liquid water paths from the Southern Great Plains region of the United States shows that errors of this magnitude have significant implications for shortwave radiation and retrievals of cloud effective particle size.

  13. Microwave measurements of the water content of bentonite

    SciTech Connect

    Latorre, V.R.; Glenn, H.D.

    1991-01-01

    The theory of operation of microwave coaxial resonators is described. Sample preparation and the application of resonator techniques to the measurement of the permittivity (dielectric constant) of bentonite is discussed. The results indicate a fairly linear change in resonant frequency for saturation levels at 10, 30, 50, 70, and 90%. The results clearly demonstrate that this microwave technique is a viable method for measuring water content of soils. A discussion of additional applications of microwave methods for determining water content in materials is presented. 3 refs., 5 figs.

  14. Hurricane Imaging Radiometer

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

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

  15. Test tank evaluation of a frequency-scanning, microwave radiometer to estimate oil thickness and physical properties. Final report, September 1994-February 1996

    SciTech Connect

    Murphy, T.J.; McMahon, O.B.; Hover, G.L.

    1996-04-01

    This report describes the testing of a 26-40 GHz (Ka-band) Frequency Scanning Radiometer (FSR) at OHMSETT (the National Oil Spill Response Test Facility) to evaluate the instrument`s ability to detect and measure the thickness of oil films on water. Measurement variables were oil type, oil thickness, and wave conditions. The results indicate that the FSR was able to reliably measure oil thickness under calm conditions and, in some cases, under mild wave conditions. Future hardware development should include (1) a multichannel upgrade to the Ka-band FSR to decrease the data acquisition interval, and (2) the development of a proof-of-concept W-band (75-110 GHz) FSR to measure thinner films. After laboratory testing, these instruments should be evaluated at OHMSETT. Included in the appendices to this report are all of the radiometric brightness temperature (TB) versus measurement frequency plots for the data collected at OHMSETT.

  16. Microwave Extraction of Water from Lunar Regolith Simulant

    NASA Technical Reports Server (NTRS)

    Ethridge, Edwin C.; Kaukler, William

    2007-01-01

    Nearly a decade ago the DOD Clementine lunar orbital mission obtained data indicating that the permanently shaded regions at the lunar poles may have permanently frozen water in the lunar soil. Currently NASA's Robotic Lunar Exploration Program, RLEP-2, is planned to land at the lunar pole to determine if water is present. The detection and extraction of water from the permanently frozen permafrost is an important goal for NASA. Extraction of water from lunar permafrost has a high priority in the In-Situ Resource Utilization, ISRU, community for human life support and as a fuel. The use of microwave processing would permit the extraction of water without the need to dig, drill, or excavate the lunar surface. Microwave heating of regolith is potentially faster and more efficient than any other heating methods due to the very low thermal conductivity of the lunar regolith. Also, microwaves can penetrate into the soil permitting water removal from deep below the lunar surface. A cryogenic vacuum test facility was developed for evaluating the use of microwave heating and water extraction from a lunar regolith permafrost simulant. Water is obtained in a cryogenic cold trap even with soil conditions below 0 C. The results of microwave extraction of water experiments will be presented.

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

    PubMed

    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.

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

    NASA Technical Reports Server (NTRS)

    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.

  19. Using Microwaves for Extracting Water from the Moon

    NASA Technical Reports Server (NTRS)

    Ethridge, Edwin C.

    2009-01-01

    Twenty years ago, the Lunar Prospector remote sensing satellite provided evidence of relatively large hydrogen concentrations at the lunar poles and in particular concentrated in permanently shadowed craters. The scientific hypothesis is that the hydrogen is in the form of cryo-trapped water just under the surface of the soil. If true this would mean that an average of about 2% water ice is mixed with the lunar soil existing in the form of ice at cryogenic temperatures. For 5 years we have been investigating the use of microwaves for the processing of lunar soil. One of the early uses could be to use microwave energy to extract volatiles and in particular water from the lunar permafrost. Prototype experiments have shown that microwave energy at 2.45 GHz, as in consumer microwave ovens, will couple with and heat cryogenically cooled lunar soil permafrost simulant, resulting in the rapid sublimation of water vapor into the vacuum chamber. The water vapor has been collected on a cryogenic cold trap with high efficiency. The primary advantage of microwave processing is that the volatiles can be extracted in situ. Excavation would not be required. Microwave frequency dielectric property measurements are being made of different lunar soil simulants and plans are to measure Apollo lunar soil at different frequencies and over a range of temperatures. The materials properties are being used to evaluate the heating of lunar soil and develop COMSOL models that can be used to evaluate different microwave extraction scenarios. With COMSOL the heating from cryogenic temperatures can be calculated and COMSOL will permit temperature dependent materials properties to be used during the heating process. Calculations at different microwave frequencies will allow the evaluation of the type of hardware that would be needed to most efficiently extract the water and other volatiles.

  20. Using Microwaves for Extracting Water from the Moon

    NASA Technical Reports Server (NTRS)

    Ethridge, Edwin C.; Kaukler, William; Hepburn, Frank

    2009-01-01

    This disk contains a video that accompanies the talk. Twenty years ago, the Lunar Prospector remote sensing satellite provided evidence of relatively large hydrogen concentrations at the lunar poles and in particular concentrated in permanently shadowed craters. The scientific hypothesis is that the hydrogen is in the form of cryo-trapped water just under the surface of the soil. If true this would mean that an average of about 2% water ice is mixed with the lunar soil existing in the form of ice at cryogenic temperatures. For 5 years we have been investigating the use of microwaves for the processing of lunar soil. One of the early uses could be to use microwave energy to extract volatiles and in particular water from the lunar permafrost. Prototype experiments have shown that microwave energy at 2.45 GHz, as in consumer microwave ovens, will couple with and heat cryogenically cooled lunar soil permafrost simulant, resulting in the rapid sublimation of water vapor into the vacuum chamber. The water vapor has been collected on a cryogenic cold trap with high efficiency. The primary advantage of microwave processing is that the volatiles can be extracted in situ. Excavation would not be required. Microwave frequency dielectric property measurements are being made of different lunar soil simulants and plans are to measure Apollo lunar soil at different frequencies and over a range of temperatures. The materials properties are being used to evaluate the heating of lunar soil and develop COMSOL models that can be used to evaluate different microwave extraction scenarios. With COMSOL the heating from cryogenic temperatures can be calculated and COMSOL will permit temperature dependent materials properties to be used during the heating process. Calculations at different microwave frequencies will allow the evaluation of the type of hardware that would be needed to most efficiently extract the water and other volatiles. The video shows the partial results of the COMSOL

  1. Using Microwaves for Extracting Water from the Moon

    NASA Technical Reports Server (NTRS)

    Ethridge, Edwin C.; Kaukler, William; Hepburn, Frank

    2009-01-01

    This disk contains 2 videos that accompanies the talk. Twenty years ago, the Lunar Prospector remote sensing satellite provided evidence of relatively large hydrogen concentrations at the lunar poles and in particular concentrated in permanently shadowed craters. The scientific hypothesis is that the hydrogen is in the form of cryo-trapped water just under the surface of the soil. If true this would mean that an average of about 2% water ice is mixed with the lunar soil existing in the form of ice at cryogenic temperatures. For 5 years we have been investigating the use of microwaves for the processing of lunar soil. One of the early uses could be to use microwave energy to extract volatiles and in particular water from the lunar permafrost. Prototype experiments have shown that microwave energy at 2.45 GHz, as in consumer microwave ovens, will couple with and heat cryogenically cooled lunar soil permafrost simulant, resulting in the rapid sublimation of water vapor into the vacuum chamber. The water vapor has been collected on a cryogenic cold trap with high efficiency. The primary advantage of microwave processing is that the volatiles can be extracted in situ. Excavation would not be required. Microwave frequency dielectric property measurements are being made of different lunar soil simulants and plans are to measure Apollo lunar soil at different frequencies and over a range of temperatures. The materials properties are being used to evaluate the heating of lunar soil and develop COMSOL models that can be used to evaluate different microwave extraction scenarios. With COMSOL the heating from cryogenic temperatures can be calculated and COMSOL will permit temperature dependent materials properties to be used during the heating process. Calculations at different microwave frequencies will allow the evaluation of the type of hardware that would be needed to most efficiently extract the water and other volatiles. The 1st video shows the results of the COMSOL

  2. Microwave Extraction of Lunar Water for Rocket Fuel

    NASA Technical Reports Server (NTRS)

    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

  3. An algorithm for retrieval of ocean surface and atmospheric parameters from the observations of the scanning multichannel microwave radiometer (SMMR)

    NASA Technical Reports Server (NTRS)

    Wilheit, T. T.; Chang, A. T. C.

    1979-01-01

    A formalism was developed which can be used to interpret the data in terms of sea surface temperature, sea surface wind speed, and the atmospheric overburden of water vapor and liquid water. It was shown with reasonable instrumental performance assumptions, these parameters could be derived to useful accuracies. Although the algorithms were not derived for use in rain, it is shown that, at least, token rain rates can be tolerated without invalidating the retrieved geophysical parameters.

  4. Microwave-Based Water Decontamination System

    NASA Technical Reports Server (NTRS)

    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.

  5. How accurate are precipitation retrievals from space-borne passive microwave radiometers? - Evaluation of satellite retrieval errors in rain estimates from TMI, AMSR-E, SSM/I, SSMIS, AMSU-B, and MHS over the continental United States

    NASA Astrophysics Data System (ADS)

    tang, ling; tian, yudong; lin, xin

    2014-05-01

    Precipitation retrievals from space-borne Passive Microwave (PMW) radiometers are the major source in modern satellite-based global rainfall dataset. The error characteristics in these individual retrievals directly affect the merged end products and applications, but have not been systematically studied. In this paper, we undertake a critical investigation of the seasonal and sensor type skill and errors of both in PMW radiometers over the continental United States (CONUS). A high-resolution ground radar-based datasets - NOAA's National Severe Storms Laboratory (NSSL) Q2 radar derived precipitation estimates are used as the ground reference. The high spatial and temporal resolution of the reference data allows near-instantaneous collocation (within 5 minutes) and relatively more precise comparison with the satellite overpasses. We compare precipitation retrievals from twelve satellites, including six imagers (one TMI, AMSR-E, SSM/I and three SSMIS) and six sounders (three AMSU-B and three MHS) against the Q2 radar precipitation. Results show that precipitation retrievals from PMW radiometers exhibit fairly systematic biases depending on season and precipitation intensity, with overestimates in summer at moderate to high precipitation rates and underestimates in winter at low and moderate precipitation rates. This result is also showing in satellite-based multi-sensor precipitation products, indicating the transferring of uncertainties from single sensor input to multi-sensor precipitation estimates. Meanwhile, retrievals from the microwave imagers have notably better performance than those from the microwave sounders. The sounders have higher biases, about two times at small rain rates and two-three times at the moderate to high end rain rates, compared to the imagers. The sounders also have a narrower dynamic range, and higher random errors, which are also detailed in the paper.

  6. The conical scan radiometer

    NASA Astrophysics Data System (ADS)

    Prosch, T.; Hennings, D.

    1982-07-01

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

  7. Tracking Water Vapor in the Winter High Arctic using the Microwave Humidity Sounder

    NASA Astrophysics Data System (ADS)

    Duck, T. J.; Lesins, G. B.; Drummond, J. R.

    2010-12-01

    The cold and dry conditions during the darkness of the winter High Arctic have been a challenge for the retrieval of tropospheric water vapor amounts from satellites. Water vapor remains the most important greenhouse gas even in these dry conditions and so its variability has a direct bearing on the radiative forcing at the surface. The presence of the surface-based temperature inversion helps to amplify the response of the surface temperature to fluctuations in water vapor column. The ability to track the movement and magnitude of water vapor intrusions into the Arctic has important operational forecast as well as climate implications associated with rapid Arctic warming and sea ice loss. The water vapor field also determines the cloud and precipitation development. The first high temporal and high spatial resolution satellite retrievals of precipitable water in the winter High Arctic without interference from clouds and precipitation were done by Melsheimer and Heygster (2008) using the 5 AMSU-B microwave channels near the strong 183 GHz water vapor line and the window channel at 150 GHz. We have applied their algorithm to the Microwave Humidity Sounder (MHS) that is installed on the NOAA-18, -19 and MetOp-A satellites. The MHS is the next generation instrument replacing the AMSU-B. The retrievals have a sensitivity of less than 0.5 mm of column water with a nadir spatial resolution of 17 km. Numerous passes over the entire Arctic take place every day providing a high resolution map of the distribution of water vapor over the entire Arctic without masking from clouds or precipitation. The calibration procedures, including comparisons with multiple ground-based microwave radiometers, will be presented along with results of the water vapor tracking experiments for the 2009-2010 winter season in the High Arctic. Movies depicting the movement and evolution of the water vapor column will be shown. These show frequent intrusions of lobes of moisture associated with

  8. Microwave Radar Retrieval of Snow Water Equivalent

    NASA Astrophysics Data System (ADS)

    Yueh, S. H.; Rott, H.; Nagler, T. F.; Cline, D. W.; Duguay, C. R.; Essery, R.; Etchevers, P.; Hajnsek, I.; Kern, M.; Macelloni, G.; Malnes, E.; Pulliainen, J. T.; Tsang, L.; Xu, X.; Marshall, H.; Elder, K.

    2010-12-01

    Fresh water stored in snow on land is an important component of the global water cycle. In many regions of the world it is vital to health and commerce. To make global observations of snow water equivalent (SWE), the Cold Regions Hydrology High Resolution Observatory (CoReH2O) candidate mission based on X- and Ku-band synthetic aperture radar (SAR) technologies is currently going through the Phase-A study, sponsored by the European Space Agency. In addition, the Snow and Cold Land Processes (SCLP) mission, also based on the dual-frequency SAR concept, was one of the satellite missions recommended for future NASA implementation. The frequency range for the CoReH2O and SCLP microwave radar, chosen to optimize the sensitivity to volumetric snowpack properties, is 8-18 GHz (X- and Ku-bands). The overall radar SWE measurement principle has been demonstrated by measurements in 1980s-1990s and more recently the NASA Cold Land Processes Experiments in Colorado and Alaska, 2006-2008, the SARALPS-2007 and Helisnow-2008 campaigns in Europe. Ku-band has the capability to estimate SWE in shallow snowpacks, while X-band provides greater penetration for deeper snow. A dual-polarization (VV and VH) SAR will enable discrimination of the radar backscatter into volume and background vegetation/surface components, while the dual frequency design offers the capability of resolving a wide range of snow depths and snow grains. The baseline CoReH2O algorithm statistically minimizes the differences between radar measurements and radiative transfer model for snowpack. The performance of the retrieval algorithm has been studied with Ku- and X-band backscatter data measured by ground-based scatterometers at test sites in the Austrian Alps. The algorithm has also been applied to the airborne POLSCAT and satellite TerraSAR-X data acquired for the CLPX-II Kuparuk River Study Site in the tundra region of northern Alaska. The comparison with the field measurements reveals a RMSE of 0.7 cm for SWE

  9. Comparing Water Vapor Trends Derived From Infrared and Microwave Radiometry

    NASA Astrophysics Data System (ADS)

    Fishbein, E.; Lambrigtsen, B.; Fetzer, E.

    2005-12-01

    The Cross-track Infrared Sounder (CrIS) and Advanced Technology Microwave Sounder. (ATMS) are the primary instruments on NPOESS and NPP for measuring profiles of atmospheric temperature and humidity but have the observations have different error characteristics. CrIS is an infrared radiometer using 6 micron thermal radiances to infer humidity while ATMS uses 183 GHz radiances. CrIS has good vertical resolution and but lose sensitivity with cloudiness while ATMS has poorer vertical resolution but is insensitive to nonprecipitating clouds. The error characteristics of humidity are complicated by the interaction of the errors from the two instruments propagating through a highly nonlinear combined CrIS and ATMS retrieval and are highly state dependent because cloudiness is correlated with relative humidity by dynamical processes involving uplift such as cumulus convection and baroclinic instability. We assess how these error sources impact climate trend analysis using data from the sounders on NASA's Aqua satellite. The Atmospheric Infrared Sounder (AIRS), the Advanced Microwave Sounder-A (AMSU-A) and the Humidity Sounder for Brazil (HSB) fly on the Aqua satellite and have similar capabilities to CrIS and ATMS. We have produced humidity profiles from the AIRS/AMSU/HSB radiances using the AIRS unified retrieval system in four modes of different combinations of instruments: 1) all three instruments, 2) AIRS and AMSU, 3) AMSU and HSB and 4) AIRS alone. These correspond to the 1) CrIS and ATMS operating together using cloud clearing, 2) CrIS and ATMS operating in together but without the microwave humidity profiling channels, 3) ATMS alone and 4) CrIS alone using hole hunting. Trend analysis of zonal means from the four datasets is compared and mapped products are used to illustrate how measurement capabilities affect the derived trends.

  10. GPM Plans for Radiometer Intercalibration

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  11. Estimation of snow water equivalent using microwave radiometry over Arctic first-year sea ice

    NASA Astrophysics Data System (ADS)

    Barber, D. G.; Iacozza, J.; Walker, A. E.

    2003-12-01

    The magnitude and spatial distribution of snow on sea ice are both integral components of the ocean-sea-ice-atmosphere system. Although there exists a number of algorithms to estimate the snow water equivalent (SWE) on terrestrial surfaces, to date there is no precise method to estimate SWE on sea ice. Physical snow properties and in situ microwave radiometry at 19, 37 and 85 GHz, V and H polarization were collected for a 10-day period over 20 first-year sea ice sites.We present and compare the in situ physical, electrical and microwave emission properties of snow over smooth Arctic first-year sea ice for 19 of the 20 sites sampled. Physical processes creating the observed vertical patterns in the physical and electrical properties are discussed. An algorithm is then developed from the relationship between the SWE and the brightness temperature measured at 37 GHz (55°) H polarization and the air temperature. The multiple regression between these variables is able to account for over 90% of the variability in the measured SWE. This algorithm is validated with a small in situ data set collected during the 1999 field experiment. We then compare our data against the NASA snow thickness algorithm, designed as part of the NASA Earth Enterprise Program. The results indicated a lack of agreement between the NASA algorithm and the algorithm developed here. This lack of agreement is attributed to differences in scale between the Special Sensor Microwave/Imager and surface radiometers and to differences in the Antarctic versus Arctic snow physical and electrical properties. Copyright

  12. Microwave sensing from orbit

    NASA Technical Reports Server (NTRS)

    Kritikos, H. N.; Shiue, J.

    1979-01-01

    Microwave sensors, used in conjunction with the traditional sensors of visible and infrared light to extend present capabilities of global weather forecasts and local storm watches, are discussed. The great advantage of these sensors is that they can penetrate or 'see' through cloud formations to monitor temperature, humidity and wind fields below the clouds. Other uses are that they can penetrate the earth deeper than optical and IR systems; they can control their own angle of incidence; they can detect oil spills; and they can enhance the studies of the upper atmosphere through measurement of temperature, water vapor and other gaseous species. Two types of microwave sensors, active and passive, are examined. Special attention is given to the study of the microwave radiometer and the corresponding temperature resolution as detected by the antenna. It is determined that not only will the microwave remote sensors save lives by allowing close monitoring of developing storms, but also save approximately $172 million/year.

  13. Assimilating Spaceborne Passive Microwave Measurements into a Land Surface Model to Estimate Snow Water Equivalent in the Yampa River Basin

    NASA Astrophysics Data System (ADS)

    Kim, R. S.; Li, D.; Durand, M. T.

    2014-12-01

    Acquiring accurate spatiotemporal snow information over large areas for understanding snowcover in the global and regional water and energy balances is crucial and has motivated snow characterization via remote sensing. The passive microwave (PM) measurements have been widely used and invested in order to obtain information about snowpack properties. In this paper, we utilize a snow data assimilation system to estimate snow water equivalent (SWE) in the Yampa River basin in the Colorado Rockies within the NASA Cold Land Processes Experiment (CLPX) area of 2002-2003. The Advanced Microwave Scanning Radiometer Earth Observing System (AMSR-E) observations were used. Forcing data were derived from the North American Land Data Assimilation v2 (NLDAS-2) dataset. Also, the Microwave Emission Model of Layered Snowpacks (MEMLS) was used to convert the snow state variables to brightness temperatures. The ensemble Kalman filter was directly employed to assimilate PM brightness temperature data into a land surface model snow scheme. Assimilation results are compared with SNOTEL and snow course observations.

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

    SciTech Connect

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

    1996-04-01

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

  15. Influence of microwaves on the water surface tension.

    PubMed

    Parmar, Harisinh; Asada, Masahiro; Kanazawa, Yushin; Asakuma, Yusuke; Phan, Chi M; Pareek, Vishnu; Evans, Geoffrey M

    2014-08-26

    In this study, microwave irradiation was applied to hanging droplets of both water and ethylene glycol. Once the irradiation had ceased and the droplet was allowed to return to its original temperature, it was found that the surface tension of ethylene glycol returned to its original value. In contrast, the water surface tension remained well below its original value for an extended period of time. Similar observations have been reported for magnetically treated water, but this is the first time that such a lasting effect has been reported for microwave irradiation. The effect can be attributed to the unique hydrogen bonds of interfacial water molecules. While the irradiation intensities used in this study are well above those in household devices, there is certainly the potential to apply the methodology to industrial applications where the manipulation of surface tension is required without the use of chemical addition.

  16. An Airborne Conical Scanning Millimeter-Wave Imaging Radiometer (CoSMIR)

    NASA Technical Reports Server (NTRS)

    Piepmeier, J.; Racette, P.; Wang, J.; Crites, A.; Doiron, T.; Engler, C.; Lecha, J.; Powers, M.; Simon, E.; Triesky, M.; Krebs, Carolyn A. (Technical Monitor)

    2001-01-01

    An airborne Conical Scanning Millimeter-wave Imaging Radiometer (CoSMIR) for high-altitude observations from the NASA Research Aircraft (ER-2) is discussed. The primary application of the CoSMIR is water vapor profile remote sensing. Four radiometers operating at 50 (three channels), 92, 150, and 183 (three channels) GHz provide spectral coverage identical to nine of the Special Sensor Microwave Imager/Sounder (SSMIS) high-frequency channels. Constant polarization-basis conical and cross-track scanning capabilities are achieved using an elevation-under-azimuth two-axis gimbals.

  17. Water detection in fuel tanks using the microwave reflection technique

    NASA Astrophysics Data System (ADS)

    Khalid, Kaida; Valeriu Grozescu, Ionel; Keng Tiong, Lim; Teck Sim, Lee; Mohd, Roslim

    2003-11-01

    Water is often present in fuel tanks due to night and day temperature changes, resulting in a build-up of condensed water within the inner surface of the tank. The expectancy of water infiltration in fuel tanks is even higher in flooding prone areas. Water settlement at the bottom of the tank causes internal corrosion. In this work, a simple, low cost and accurate microwave reflection type system for detection of water in fuel tanks has been developed. A module consisting of a microwave generator and a detecting diode is used to measure the microwave reflection coefficient at various positions through the fuel tank. In the course of the study, a motion control and data acquisition system has been developed. Software written using the LabVIEW programming language is used to control the movement of the sensor and for the data acquisition. Theoretical and experimental results show the ability of the system to detect the presence of a water level down to approximately 1 mm. A simple theoretical model for power prediction of the reflected signal at various positions of the sensor in the tank is also presented.

  18. MAPIR: An Airborne Polarmetric Imaging Radiometer in Support of Hydrologic Satellite Observations

    NASA Technical Reports Server (NTRS)

    Laymon, C.; Al-Hamdan, M.; Crosson, W.; Limaye, A.; McCracken, J.; Meyer, P.; Richeson, J.; Sims, W.; Srinivasan, K.; Varnevas, K.

    2010-01-01

    In this age of dwindling water resources and increasing demands, accurate estimation of water balance components at every scale is more critical to end users than ever before. Several near-term Earth science satellite missions are aimed at global hydrologic observations. The Marshall Airborne Polarimetric Imaging Radiometer (MAPIR) is a dual beam, dual angle polarimetric, scanning L band passive microwave radiometer system developed by the Observing Microwave Emissions for Geophysical Applications (OMEGA) team at MSFC to support algorithm development and validation efforts in support of these missions. MAPIR observes naturally-emitted radiation from the ground primarily for remote sensing of land surface brightness temperature from which we can retrieve soil moisture and possibly surface or water temperature and ocean salinity. MAPIR has achieved Technical Readiness Level 6 with flight heritage on two very different aircraft, the NASA P-3B, and a Piper Navajo.

  19. Microwave Spectrum of the Isopropanol-Water Dimer

    NASA Astrophysics Data System (ADS)

    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.

  20. High Frequency PIN-Diode Switches for Radiometer Applications

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  1. Refraction of microwave signals by water vapor

    NASA Technical Reports Server (NTRS)

    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).

  2. The free jet microwave spectrum of 2-phenylethylamine-water.

    PubMed

    Melandri, Sonia; Maris, Assimo; Giuliano, Barbara M; Favero, Laura B; Caminati, Walther

    2010-09-21

    We observed the rotational spectrum of the 1:1 molecular adduct between 2-phenylethylamine and water (normal and H(2)(18)O species) by free jet absorption microwave spectroscopy in the frequency region 60-78 GHz. The dominant spectrum belongs to the structure where the PEA moiety is in the most stable gauche conformation and the water molecule is hydrogen bound to the nitrogen lone pair. The orientation of the water molecule is such that the oxygen atom is almost equidistant (ca. 2.5 A) from the closest methylenic and aromatic hydrogen atoms.

  3. An evaluation of water vapor radiometer data for calibration of the wet path delay in very long baseline interferometry experiments

    NASA Technical Reports Server (NTRS)

    Kuehn, C. E.; Himwich, W. E.; Clark, T. A.; Ma, C.

    1991-01-01

    The internal consistency of the baseline-length measurements derived from analysis of several independent VLBI experiments is an estimate of the measurement precision. The paper investigates whether the inclusion of water vapor radiometer (WVR) data as an absolute calibration of the propagation delay due to water vapor improves the precision of VLBI baseline-length measurements. The paper analyzes 28 International Radio Interferometric Surveying runs between June 1988 and January 1989; WVR measurements were made during each session. The addition of WVR data decreased the scatter of the length measurements of the baselines by 5-10 percent. The observed reduction in the scatter of the baseline lengths is less than what is expected from the behavior of the formal errors, which suggest that the baseline-length measurement precision should improve 10-20 percent if WVR data are included in the analysis. The discrepancy between the formal errors and the baseline-length results can be explained as the consequence of systematic errors in the dry-mapping function parameters, instrumental biases in the WVR and the barometer, or both.

  4. Interpretation of Nimbus-7 37 GHz microwave brightness temperature data in semi-arid southern Africa

    NASA Technical Reports Server (NTRS)

    Prince, S. D.; Choudhury, B. J.

    1989-01-01

    Monthly 37 GHz microwave polarization difference temperatures (MPDT) derived from the Nimbus-7 scanning multichannel microwave radiometer (SMMR) for southern Africa from 1979 to 1985 are compared with rainfall and Advanced Very High Resolution Radiometer (AVHRR) normalized difference vegetation index (NDVI) data. MPDT rose sharply during a drought episode which occurred within the period included in the data. The rise was seen not only in the growing season, but also in the dry season MPDT when no actively photosynthetic, water-containing leaves are present. The results suggest that scattering of the emitted microwave radiation by dead and living vegetation is a more important factor than has previously been recognized.

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

    NASA Astrophysics Data System (ADS)

    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.

  6. A test of water vapor radiometer-based troposphere calibration using VLBI observations on a 21-kilometer baseline

    NASA Technical Reports Server (NTRS)

    Linfield, R. P.; Teitelbaum, L. P.; Skjerve, L. J.; Keihm, S. J.; Walter, S. J.; Mahoney, M. J.; Treuhaft, R. N.

    1995-01-01

    Simultaneous very long baseline interferometry (VLBI) and water vapor radiometer (WVR) measurements on a 21 km baseline showed that calibration by WVRs removed a significant fraction of the effect of tropospheric delay fluctuations for these experiments. From comparison of the residual delay variations within scans and between scans, the total tropospheric contribution t the delay residuals for each of the three 5 to 20 hour sessions was estimated as 1, 17, and 10%, with the first value being uncertain. The observed improvement in rms residual delay from WVR calibration during these three sessions was 4, 16, and 2%, respectively. The improvement is consistent with the estimated 2 to 3 mm path delay precision of current WVRs. The VLBI measurements, of natural radio sources, were conducted in April and May 1993 at Goldstone, California. Dual-frequency (2.3 and 8.4 GHz) observations were employed to remove the effects of charged particles from the data. Measurements with co-pointed WVRs, located within 50 m of the axis of each antenna, were performed to test the ability of the WVRs to calibrate line-of-sight path delays. Factors that made WVR performance assessment difficult included (1) the fact that the level of tropospheric fluctuations was smaller than is typical for Goldstone during these experiments and (2) VLBI delay variations on longer time scales (i.e., over multiple scans) contained uncalibrated instrumental effects (probably a result of slow temperature variations in the VLBI hardware) that were larger than the tropospheric effects.

  7. The Millimeter-Wave Imaging Radiometer (MIR)

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

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

    PubMed Central

    Wang, Miaomiao; Li, Bofeng

    2016-01-01

    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

  9. Retrieving of atmospheric parameters from multi-GNSS in real time: Validation with water vapor radiometer and numerical weather model

    NASA Astrophysics Data System (ADS)

    Li, Xingxing; Zus, Florian; Lu, Cuixian; Dick, Galina; Ning, Tong; Ge, Maorong; Wickert, Jens; Schuh, Harald

    2015-07-01

    The multiconstellation Global Navigation Satellite Systems (GNSS) (e.g., GPS, GLObal NAvigation Satellite System (GLONASS), Galileo, and BeiDou) offers great opportunities for real-time retrieval of atmospheric parameters for supporting numerical weather prediction nowcasting or severe weather event monitoring. In this study, the observations from different GNSS are combined to retrieve atmospheric parameters based on the real-time precise point positioning technique. The atmospheric parameters, retrieved from multi-GNSS observations of a 180 day period from about 100 globally distributed stations, including zenith total delay, integrated water vapor, horizontal gradient, and slant total delay (STD), are analyzed and evaluated. The water vapor radiometer data and a numerical weather model, the operational analysis of the European Centre for Medium-Range Weather Forecasts (ECMWF), are used to independently validate the performance of individual GNSS and also demonstrate the benefits of multiconstellation GNSS for real-time atmospheric monitoring. Our results show that the GLONASS and BeiDou have the potential capability for real-time atmospheric parameter retrieval for time-critical meteorological applications as GPS does, and the combination of multi-GNSS observations can improve the performance of a single-system solution in meteorological applications with higher accuracy and robustness. The multi-GNSS processing greatly increases the number of STDs. The mean and standard deviation of STDs between each GNSS and ECMWF exhibit a good stability as function of the elevation angle, the azimuth angle, and time, in general. An obvious latitude dependence is confirmed by a map of station specific mean and standard deviations. Such real-time atmospheric products, provided by multi-GNSS processing with higher accuracy, stronger reliability, and better distribution, might be highly valuable for atmospheric sounding systems, especially for nowcasting of extreme weather.

  10. Temperature/pressure and water vapor sounding with microwave spectroscopy

    NASA Technical Reports Server (NTRS)

    Muhleman, D. O.; Janssen, M. A.; Clancy, R. T.; Gulkis, S.; Mccleese, D. J.; Zurek, R.; Haberle, R. M.; Frerking, M.

    1992-01-01

    Two intense microwave spectra lines exist in the martian atmosphere that allow unique sounding capabilities: water vapor at 183 GHz and the (2-1) rotational line of CO at 230 GHz. Microwave spectra line sounding is a well-developed technique for the Earth's atmosphere for sounding from above from spacecraft and airplanes, and from below from fixed surface sites. Two simple instruments for temperature sounding on Mars (the CO line) and water vapor measurements are described. The surface sounder proposed for the MESUR sites is designed to study the boundary layer water vapor distribution and the temperature/pressure profiles with vertical resolution of 0.25 km up to 1 km with reduced resolution above approaching a scale height. The water channel will be sensitive to a few tenths of a micrometer of water and the temperature profile will be retrieved to an accuracy between 1 and 2 K. The latter is routinely done on the Earth using oxygen lines near 60 GHz. The measurements are done with a single-channel heterodyne receiver looking into a 10-cm mirror that is canned through a range of elevation angles plus a target load. The frequency of the receiver is sweep across the water and CO lines generating the two spectra at about 1-hr intervals throughout the mission. The mass and power for the proposed instrument are 2 kg and 5-8 W continuously. The measurements are completely immune to the atmospheric dust and ice particle loads. It was felt that these measurements are the ultimate ones to properly study the martian boundary layer from the surface to a few kilometers. Sounding from above requires an orbiting spacecraft with multichannel microwave spectrometers such as the instrument proposed for MO by a subset of the authors, a putative MESUR orbiter, and a proposed Discovery mission called MOES. Such an instrument can be built with less than 10 kg and use less than 15 W. The obvious advantage of this approach is that the entire atmosphere can be sounded for temperature and

  11. Spectral characterization of water stress impact on some agricultural crops: II. Studies on alfalfa using handheld radiometer

    NASA Astrophysics Data System (ADS)

    Shakir Hanna, Safwat H.; Girmay-Gwahid, B.

    1998-12-01

    Remotely sensed reflectance from stressed and non-stressed crop vegetative cover can be predicted from two combination of spectral bands as a ratio or as normalized vegetation indices. The most common spectral bands used lie in the red and infrared region (350 - 800 nm) and are dominated by the absorption of chlorophyll and other accessory pigments. In addition, reflectance in the middle infrared is dominated by absorption from liquid water contained in plant's tissues. The objectives of the present work are: (1) to evaluate the reflectance data from frequently irrigated and water stressed alfalfa using a handheld radiometer and assess the spectral correlation with the ground-truth and; (2) to evaluate the applications of a Hyperspectral Structure Component Index (HSCI) proposed by Shakir and Girmay-Gwahid (1998). The experiment was designed to collect reflectance data from alfalfa (pure alfalfa stand and a plot where alfalfa was mixed with sedge grass) planted at the Blythe Research Station, California. The size of the plots was 30 X 50 ft2. With a field spectrometer, the scan over each treatment was made at 1 hr intervals between 10:00 a.m. and 2:00 p.m. Pacific Day Time (PDT). Vegetative samples were taken from the two treatments during the initial sampling for purposes of conducting chemical analysis. Soil samples were collected to determine the amount of available soil moisture differences in the two treatments. The results of this experiment showed that in the 850 - 1150 nm wavelength range the stressed alfalfa plots showed lower reflectance than unstressed plots. However; the reflectance of stressed alfalfa was higher than the unstressed stands above the 1150 nm. This is probably due to the absorption from liquid water contained in the unstressed plant tissues. The analysis of data using the (HSCI) model showed that the stressed pure alfalfa plots have values less than 1 and under unstressed alfalfa plots have the value greater than 1. This means that the

  12. Radiometer Calibration and Characterization

    1994-12-31

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

  13. Thermal infrared radiometer calibration and experimental measurements

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

  14. Compact Radiometers Expand Climate Knowledge

    NASA Technical Reports Server (NTRS)

    2010-01-01

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

  15. A physically-based retrieval of cloud liquid water from SSM/I measurements

    NASA Technical Reports Server (NTRS)

    Greenwald, Thomas J.; Stephens, Graeme L.; Vonder Haar, Thomas H.

    1992-01-01

    A simple physical scheme is proposed for retrieving cloud liquid water over the ice-free global oceans from Special Sensor Microwave/Imager (SSM/I) observations. Details of the microwave retrieval scheme are discussed, and the microwave-derived liquid water amounts are compared with the ground radiometer and AVHRR-derived liquid water for stratocumulus clouds off the coast of California. Global distributions of the liquid water path derived by the method proposed here are presented.

  16. Low-level water vapor fields from the VISSR atmospheric sounder (VAS) split window channels at 11 and 12 microns. [visible infrared spin scan radiometer

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

    A series of high-resolution water vapor fields were derived from the 11 and 12 micron channels of the VISSR Atmospheric Sounder (VAS) on GOES-5. The low-level tropospheric moisture content was separated from the surface and atmospheric radiances by using the differential adsorption across the 'split window' along with the average air temperature from imbedded radiosondes. Fields of precipitable water are presented in a time sequence of five false color images taken over the United States at 3-hour intervals. Vivid subsynoptic and mesoscale patterns evolve at 15 km horizontal resolution over the 12-hour observing period. Convective cloud formations develop from several areas of enhanced low-level water vapor, especially where the vertical water vapor gradient relatively strong. Independent verification at radiosonde sites indicates fairly good absolute accuracy, and the spatial and temporal continuity of the water vapor features indicates very good relative accuracy. Residual errors are dominated by radiometer noise and unresolved clouds.

  17. The impact of microwave absorber and radome geometries on GNSS measurements of station coordinates and atmospheric water vapour

    NASA Astrophysics Data System (ADS)

    Ning, T.; Elgered, G.; Johansson, J. M.

    2011-01-01

    We have used microwave absorbing material in different geometries around ground-based Global Navigation Satellite System (GNSS) antennas in order to mitigate multipath effects on the estimates of station coordinates and atmospheric water vapour. The influence of a hemispheric radome - of the same type as in the Swedish GPS network SWEPOS - was also investigated. Two GNSS stations at the Onsala Space Observatory were used forming a 12 m baseline. GPS data from October 2008 to November 2009 were analyzed by the GIPSY/OASIS II software using the Precise Point Positioning (PPP) processing strategy for five different elevation cutoff angles from 5° to 25°. We found that the use of the absorbing material decreases the offset in the estimated vertical component of the baseline from ˜27 mm to ˜4 mm when the elevation cutoff angle varies from 5° to 20°. The horizontal components are much less affected. The corresponding offset in the estimates of the atmospheric Integrated Water Vapour (IWV) decreases from ˜1.6 kg/m2 to ˜0.3 kg/m2. Changes less than 5 mm in the offsets in the vertical component of the baseline are seen for all five elevation cutoff angle solutions when the antenna was covered by a hemispheric radome. Using the radome affects the IWV estimates less than 0.4 kg/m2 for all different solutions. IWV comparisons between a Water Vapour Radiometer (WVR) and the GPS data give consistent results.

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

    MedlinePlus

    ... Products Risk of Burns from Eruptions of Hot Water Overheated in Microwave Ovens Share Tweet Linkedin Pin ... What Can Consumers Do to Avoid Super-Heated Water? Follow the precautions and recommendations found in the ...

  19. The Hurricane Imaging Radiometer: Present and Future

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Gloersen, P.

    1976-01-01

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

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

    SciTech Connect

    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.

  2. Interpretation of observed microwave signatures from ground dual polarization radar and space multi frequency radiometer for the 2011 Grímsvötn volcanic eruption

    NASA Astrophysics Data System (ADS)

    Montopoli, M.; Vulpiani, G.; Cimini, D.; Picciotti, E.; Marzano, F. S.

    2013-07-01

    The important role played by ground-based microwave weather radars for the monitoring of volcanic ash clouds has been recently demonstrated. The potential of microwaves from satellite passive and ground-based active sensors to estimate near-source volcanic ash cloud parameters has been also proposed, though with little investigation of their synergy and the role of the radar polarimetry. The goal of this work is to show the potentiality and drawbacks of the X-band Dual Polarization radar measurements (DPX) through the data acquired during the latest Grímsvötn volcanic eruptions that took place on May 2011 in Iceland. The analysis is enriched by the comparison between DPX data and the observations from the satellite Special Sensor Microwave Imager/Sounder (SSMIS) and a C-band Single Polarization (SPC) radar. SPC, DPX, and SSMIS instruments cover a large range of the microwaves spectrum, operating respectively at 5.4, 3.2, and 0.16-1.6 cm wavelengths. The multi-source comparison is made in terms of Total Columnar Concentration (TCC). The latter is estimated from radar observables using the "Volcanic Ash Radar Retrieval for dual-Polarization X band systems" (VARR-PX) algorithm and from SSMIS brightness temperature (BT) using a linear BT-TCC relationship. The BT-TCC relationship has been compared with the analogous relation derived from SSMIS and SPC radar data for the same case study. Differences between these two linear regression curves are mainly attributed to an incomplete observation of the vertical extension of the ash cloud, a coarser spatial resolution and a more pronounced non-uniform beam filling effect of SPC measurements (260 km far from the volcanic vent) with respect to the DPX (70 km from the volcanic vent). Results show that high-spatial-resolution DPX radar data identify an evident volcanic plume signature, even though the interpretation of the polarimetric variables and the related retrievals is not always straightforward, likely due to the

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

    NASA Technical Reports Server (NTRS)

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

    2009-01-01

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

  4. Microwave remote sensing from space

    NASA Technical Reports Server (NTRS)

    Carver, K. R.; Elachi, C.; Ulaby, F. T.

    1985-01-01

    Spaceborne microwave remote sensors provide perspectives of the earth surface and atmosphere which are of unique value in scientific studies of geomorphology, oceanic waves and topography, atmospheric water vapor and temperatures, vegetation classification and stress, ice types and dynamics, and hydrological characteristics. Microwave radars and radiometers offer enhanced sensitivities to the geometrical characteristics of the earth's surface and its cover, to water in all its forms - soil and vegetation moisture, ice, wetlands, oceans, and atmospheric water vapor, and can provide high-resolution imagery of the earth's surface independent of cloud cover or sun angle. A brief review of the historical development and principles of active and passive microwave remote sensing is presented, with emphasis on the unique characteristics of the information obtainable in the microwave spectrum and the value of this information to global geoscientific studies. Various spaceborne microwave remote sensors are described, with applications to geology, planetology, oceanography, glaciology, land biology, meteorology, and hydrology. A discussion of future microwave remote sensor technological developments and challenges is presented, along with a summary of future missions being planned by several countries.

  5. Water - The key to global change. [of weather and climate

    NASA Technical Reports Server (NTRS)

    Soffen, Gerald A.

    1988-01-01

    The role of water in processes of global change is discussed. The importance of water in global warming, the loss of biological diversity, the activity of the El Nino southern oscillation, and the melting of polar ice are examined. Plans for a mission to measure tropical rainfall using a two frequency radar, a visible/IR radiometer and a passive microwave radiometer are noted. The way in which global change is affected by changes in patterns of available water is considered.

  6. WindSat Passive Microwave Soil Moisture Retrievals

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Technical Abstract: WindSat is a spaceborne fully polarimetric conical scanning microwave radiometer. It operates at frequencies and polarizations that match other radiometers such as the Advanced Microwave Scanning Radiometer (AMSR-E) and in addition it acquires additional polarimetric measurements...

  7. First extended validation of satellite microwave liquid water path with ship-based observations of marine low clouds

    NASA Astrophysics Data System (ADS)

    Painemal, David; Greenwald, Thomas; Cadeddu, Maria; Minnis, Patrick

    2016-06-01

    We present the first extended validation of satellite microwave (MW) liquid water path (LWP) for low nonprecipitating clouds, from four operational sensors, against ship-borne observations from a three-channel MW radiometer collected along ship transects over the northeast Pacific during May-August 2013. Satellite MW retrievals have an overall correlation of 0.84 with ship observations and a bias of 9.3 g/m2. The bias for broken cloud scenes increases linearly with water vapor path and remains below 17.7 g/m2. In contrast, satellite MW LWP is unbiased in overcast scenes with correlations up to 0.91, demonstrating that the retrievals are accurate and reliable under these conditions. Satellite MW retrievals produce a diurnal cycle amplitude consistent with ship-based observations (33 g/m2). Observations taken aboard extended ship cruises to evaluate not only satellite MW LWP but also LWP derived from visible/infrared sensors offer a new way to validate this important property over vast oceanic regions.

  8. Microwave Radiometer Observations of Snowpack Properties and Comparison of U.S. Japanese Results. [Hokkaido, Japan and Vermont and North Dakota test sites

    NASA Technical Reports Server (NTRS)

    Chang, A. T. C.

    1985-01-01

    Microwave data collected by field experiments over Vermont and Hokkaido and Nimbus-7 SMMR over North Dakota and Hokkaido were studied. The measured 37 GHz brightness temperatures show considerable effect of volume scattering by snow grains. The 37 GHz brightness for a new snowpack with average grain radius of 0.25 mm is generally about 40 K higher than the naturally compacted pack with average grain radius of 0.4 mm. The scattering effect is much less distinct for the 6.6 GHz. However, the layering effect is much stronger at the longer wavelength. For 10.7 and 18 GHz, the effect of layering and scattering vary due to different combinations of internal snow grain distribution and layering structures. Over the Hokkaido test site, the SMMR data are too coarse for the snow field. A better spatial resolution is required to study these snow fields.

  9. Infrared and Microwave Spectra of Ne-WATER Complex

    NASA Astrophysics Data System (ADS)

    Liu, Xunchen; Thomas, Javix; Xu, Yunjie; Hou, Dan; Li, Hui

    2016-06-01

    The binary complex of rare gas atom and water is an ideal model to study the anisotropic potential energy surface of van der Waals interaction and the large amplitude motion. Although Xe-H_2O, Kr-H_2O, Ar-H_2O, Ar-D_2O and even Ne-D_2O complexes were studied by microwave or high resolution infrared spectroscopy, the lighter Ne-H_2O complex has remained unidentified. In this talk, we will present the theoretical and experimental investigation of the Ne-H_2O complex. A four-dimension PES for H_2O-Ne which only depended on the intramolecular (Q2) normal-mode coordinate of H2O monomer was calculated in this work to determine the rovibrational energy levels and mid-infrared transitions. Aided with the calculated transitions, we were able to assigned the high resolution mid-infrared spectra of both 20Ne-H_2O and 22Ne-H_2O complexes that are generated with a pulsed supersonic molecular beam in a multipass direct absorption spectrometer equiped with an external cavity quantum cascade laser at 6 μm. Several bands of both para and ortho Ne-H2O were assigned and fitted using the Hamiltonian with strong Coriolis and angular-radical coupling terms. The predicted groud state energy levels are then confirmed by the J=1-0 and J=2-1 transitions measurement using a cavity based Fourier transform microwave spectrometer.

  10. Dielectric constants of soils at microwave frequencies

    NASA Technical Reports Server (NTRS)

    Geiger, F. E.; Williams, D.

    1972-01-01

    A knowledge of the complex dielectric constant of soils is essential in the interpretation of microwave airborne radiometer data of the earth's surface. Measurements were made at 37 GHz on various soils from the Phoenix, Ariz., area. Extensive data have been obtained for dry soil and soil with water content in the range from 0.6 to 35 percent by dry weight. Measurements were made in a two arm microwave bridge and results were corrected for reflections at the sample interfaces by solution of the parallel dielectric plate problem. The maximum dielectric constants are about a factor of 3 lower than those reported for similar soils at X-band frequencies.

  11. Retrieval of Ocean Surface Windspeed and Rainrate from the Hurricane Imaging Radiometer (HIRAD) Brightness Temperature Observations

    NASA Technical Reports Server (NTRS)

    Biswas, Sayak K.; Jones, Linwood; Roberts, Jason; Ruf, Christopher; Ulhorn, Eric; Miller, Timothy

    2012-01-01

    The Hurricane Imaging Radiometer (HIRAD) is a new airborne synthetic aperture passive microwave radiometer capable of wide swath imaging of the ocean surface wind speed under heavy precipitation e.g. in tropical cyclones. It uses interferometric signal processing to produce upwelling brightness temperature (Tb) images at its four operating frequencies 4, 5, 6 and 6.6 GHz [1,2]. HIRAD participated in NASA s Genesis and Rapid Intensification Processes (GRIP) mission during 2010 as its first science field campaign. It produced Tb images with 70 km swath width and 3 km resolution from a 20 km altitude. From this, ocean surface wind speed and column averaged atmospheric liquid water content can be retrieved across the swath. The column averaged liquid water then could be related to an average rain rate. The retrieval algorithm (and the HIRAD instrument itself) is a direct descendant of the nadir-only Stepped Frequency Microwave Radiometer that is used operationally by the NOAA Hurricane Research Division to monitor tropical cyclones [3,4]. However, due to HIRAD s slant viewing geometry (compared to nadir viewing SFMR) a major modification is required in the algorithm. Results based on the modified algorithm from the GRIP campaign will be presented in the paper.

  12. Multibubble plasma production and solvent decomposition in water by slot-excited microwave discharge

    SciTech Connect

    Ishijima, T.; Hotta, H.; Sugai, H.; Sato, M.

    2007-09-17

    Intense microwaves are injected from a slot antenna into water partly filling a metal vessel. When the vessel is evacuated to saturated vapor pressure ({approx}5x10{sup 3} Pa) of water, microwave breakdown gives rise to plasmas in many bubbles in the boiling water. Gas bubbling technique enables production of multibubble plasmas in water even at atmospheric pressure. Optical emissions from the exited species are investigated to identify radical species in water. In order to demonstrate application to purification of polluted water, methylene blue and trichlorethylene solution in 8 l water were observed to rapidly decrease with multibubble plasma treatment.

  13. Joint analysis of multiparameter radar and radiometer measurements of convective storms

    NASA Technical Reports Server (NTRS)

    Vivekanandan, J.; Turk, J.; Stephens, G. L.

    1989-01-01

    An account is given of the radiative properties of hydrometeors in order to evaluate the influences of water, ice, and melting layers on the upwelling microwave radiances of convective storms. Attention is given to storm overflights conducted by the ER-2 aircraft in coordination with the NCAR dual-polarization/dual-wavelength mode radar. Radar-radiometer comparisons are conducted for one overflight from each day of the study campaign, using the various multiparameter radar observations to delineate regions of water, ice, and melting, as well as to obtain raindrop-size distribution. Model-computed brightness temperatures are compared with the ER-2 aircraft measurements.

  14. Six mechanisms used on the SSM/1 radiometer

    NASA Technical Reports Server (NTRS)

    Ludwig, H. R.

    1985-01-01

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

  15. Radiant Temperature Nulling Radiometer

    NASA Technical Reports Server (NTRS)

    Ryan, Robert (Inventor)

    2003-01-01

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

  16. Analysis of radiometer calibration effects with TOUCHSTONE

    NASA Technical Reports Server (NTRS)

    Stanley, William D.

    1990-01-01

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

  17. Radiometer on a Chip

    NASA Technical Reports Server (NTRS)

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

    2009-01-01

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

  18. Combined Radar and Radiometer Analysis of Precipitation Over Land

    NASA Astrophysics Data System (ADS)

    Hammerschmidt, B.; Kummerow, C.

    2007-12-01

    Passive microwave imagers have long been used to detect rainfall over the world's oceans. Over land, passive microwave imagers have historically relied on the use of high frequencies (i.e., 85 GHz) to detect ice scattering signals and relate this scattering signal to a surface rainfall. Errors with this retrieval are caused by inexact retrievals of the ice water paths, the relationship between ice water path and surface rainfall and by the parallax effect - a geometric displacement between the ice scattering and surface rainfall introduced by the viewing geometry of microwave sensor. This study analyzed precipitation over the southeast United States in the summer months of 1998 to 2000, using the TRMM Microwave Imager (TMI) and Precipitation (PR) on board the Tropical Rainfall Measuring Mission (TRMM). Correlations between 85-GHz brightness temperatures (Tb) and PR-derived surface rainfall, without accounting for the parallax effect, ranged from -0.16 to -0.47 for individual months. By accounting for the parallax effect and retrieving a surface rain rate directly below the ice layer that is being observed, the correlations with Tb 85 improved slightly to the -0.23 to -0.52 range. Further analysis of the ice scattering signal showed that stratiform precipitation with moderate ice scattering had improved correlations with rainfall rate when observed 37-GHz Tbs were used instead of 85 GHz. Correlations between Tb37 and surface rainfall ranged from -0.36 to -0.71, while Tb 85 versus surface rainfall had correlations that ranged from -0.22 to - 0.47 in this rainfall category. This was a result of 37-GHz Tbs being influenced more directly by scattering and emission from the liquid layer. Correlation between the IWP, as derived from the TRMM radar, and the 85-GHz Tb depressions ranged from -0.47 to -0.72. This indicates that significant improvements in rainfall retrievals can still be achieved from either an improved understanding of the ice physics (needed to improve the

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

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

  20. [The effect of the microwave energy on the water, contaminated by vegetative forms of microorganisms].

    PubMed

    Klimarev, S I; Smirennyĭ, A L; Zagibalova, L B; Starkova, L V

    2000-01-01

    The paper presents a technology and a device for super-high sterilization, and results of investigation on the effect of microwave energy on water contaminated by vegetative forms of microorganisms. Temperatures bringing death to microorganisms in water flow were determined. In addition to the thermal effect of microwave energy, a non-thermal "specific" effect of super-high frequencies on various microorganisms (staphylococci, E. coli and Pseudomonas aeruginosa) was also studied.

  1. The Free Jet Microwave Spectrum of 2-PHENYLETHYLAMINE-WATER

    NASA Astrophysics Data System (ADS)

    Melandri, Sonia; Giuliano, B. Michela; Maris, Assimo; Caminati, Walther

    2009-06-01

    2-Phenylethylamine (PEA) is the parent structure for a variety of important compounds including dopamine, tyrosine, anphetamine and adrenaline. Due to the flexibility of the side chain, the conformational hypersurface of the isolated molecule contains several minima at relatively low energy. The conformational surface was studied by various spectroscopic and theoretical techniques and four of the five stable conformers were detected. The most stable conformers observed in isolated conditions are those in which the methylene side chain is folded into a gauche structure and the amino hydrogen is oriented towards the aromatic ring to form a weakly hydrogen bonded structure, while in the less stable conformers the amino group is in the anti position, thus the energy difference between the gauche and anti conformers (ca 4 kJ mol^{-1}) represents the energy associated with this weak interaction. Since bioactive molecules can be found in different environments including aqueous media and rotational spectroscopy coupled with high level ab initio calculations gives the most detailed structural picture, we studied the free jet microwave spectrum of the adducts formed between PEA and water in the region 60-78 GHz. The dominant spectrum is that of the 1:1 adduct of PEA and water where PEA is in its most stable gauche conformation and the water molecole is bound to the nitrogen lone pair. The orientation of the water molecole is such that the oxygen atom is closest (ca 2.5 Å) and equidistant from the ring and chain hydrogen atoms. The experimental data were complemented by ab initio calculations at the MP2/6311++G** level of theory; several stable conformations of the PEA-W have been characterized and the observed structure corresponds to the global minimum. The bonding of water seems to affect only slightly the structure of isolated PEA and the main structural parameters of the flexible amino side chain remain basically unaltered. Some lines still remain unassigned in the

  2. Assessing the utility of passive microwave data for Snow Water Equivalent (SWE) estimation in the Sutlej River Basin of the northwestern Himalaya

    NASA Astrophysics Data System (ADS)

    Brandt, T.; Bookhagen, B.; Dozier, J.

    2014-12-01

    Since 1978, space based passive microwave (PM) radiometers have been used to comprehensively measure Snow Water Equivalent (SWE) on a global basis. The ability of PM radiometers to directly measure SWE at high temporal frequencies offers some distinct advantages over optical remote sensors. Nevertheless, in mountainous terrain PM radiometers often struggle to accurately measure SWE because of wet snow, saturation in deep snow, forests, depth hoar and stratigraphy, variable relief, and subpixel heterogeneity inherent in large pixel sizes. The Himalaya, because of their high elevation and high relief—much above tree line—offer an opportunity to examine PM products in the mountains without the added complication of trees. The upper Sutlej River basin— the third largest Himalayan catchment—lies in the western Himalaya. The river is a tributary of the Indus River and seasonal snow constitutes a substantial part of the basin's hydrologic budget. The basin has a few surface stations and river gauges, which is unique for the region. As such, the Sutlej River basin is a good location to analyze the accuracy and effectiveness of the current National Snow and Ice Data Center's (NSIDC) standard AMSR-E/Aqua Daily SWE product in mountainous terrain. So far, we have observed that individual pixels can "flicker", i.e. fluctuate from day to day, over large parts of the basin. We consider whether this is an artifact of the algorithm or whether this is embedded in the raw brightness temperatures themselves. In addition, we examine how well the standard product registers winter storms, and how it varies over heavily glaciated pixels. Finally, we use a few common measures of algorithm performance (precision, recall and accuracy) to test how well the standard product detects the presence of snow, using optical imagery for validation. An improved understanding of the effectiveness of PM imagery in the mountains will help to clarify the technology's limits.

  3. GPM Intercalibrated Radiometer Brightness Temperatures

    NASA Astrophysics Data System (ADS)

    Stocker, Erich Franz; Chou, Joyce

    2013-04-01

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

  4. Evaluation of dielectric mixing models for microwave soil moisture retrieval using data from the Combined Radar/Radiometer (ComRAD) ground-based SMAP simulator

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil moisture measurements are required to improve our understanding of hydrological processes, ecosystem functions, and linkages between the Earth’s water, energy, and carbon cycles. The efficient retrieval of soil moisture depends on various factors in which soil dielectric mixing models are consi...

  5. DIRECT SYNTHESIS OF TERTIARY AMINES IN WATER USING MICROWAVES

    EPA Science Inventory

    A direct synthesis of tertiary amines is presented that proceeds expeditiously via N-alkylation of amines using alkyl halides in alkaline aqueous medium. This environmentally benign reaction is accelerated upon exposure to microwave irradiation resulting in shortened reaction tim...

  6. Preliminary results of passive microwave snow experiment during February and March 1978

    NASA Technical Reports Server (NTRS)

    Chang, A. T. C.; Shiue, J. C.; Boyne, H.; Ellerbruch, D.; Counas, G.; Wittmann, R.; Jones, R.

    1979-01-01

    The purpose of the experiment was to determine if remote microwave sensing of snowpack data could be used to predict runoff, thereby allowing more efficient management of the water supply. A four-frequency microwave radiometer system was attached to a truck-mounted aerial lift and was used to gather data on snowpacks at three different sites in the Colorado Rocky Mountains. Ground truth data measurements (density, temperature, grain size, hardness, and free-liquid water content) were taken at each site corresponding to each microwave scan.

  7. Potential Application of Airborne Passive Microwave Observations for Monitoring Inland Flooding Caused by Tropical Cyclones

    NASA Technical Reports Server (NTRS)

    Hood, Robbie E.; Radley, C.D.; LaFontaine, F.J.

    2008-01-01

    Inland flooding from tropical cyclones can be a significant factor in storm-related deaths in the United States and other countries. Information collected during NASA tropical cyclone field studies suggest surface water and flooding induced by tropical cyclone precipitation can be detected and therefore monitored using passive microwave airborne radiometers. In particular, the 10.7 GHz frequency of the NASA Advanced Microwave Precipitation Radiometer (AMPR) flown on the NASA ER-2 has demonstrated high resolution detection of anomalous surface water and flooding in numerous situations. This presentation will highlight the analysis of three cases utilizing primarily satellite and airborne radiometer data. Radiometer data from the 1998 Third Convection and Moisture Experiment (CAMEX-3) are utilized to detect surface water during landfalling Hurricane Georges in both the Dominican Republic and Louisiana. A third case is landfalling Tropical Storm Gert in Eastern Mexico during the Tropical Cloud Systems and Processes (TCSP) experiment in 2005. AMPR data are compared to topographic data and vegetation indices to evaluate the significance of the surface water signature visible in the 10.7 GHz information. The results of this study suggest the benefit of an aircraft 10 GHz radiometer to provide real-time observations of surface water conditions as part of a multi-sensor flood monitoring network.

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

    NASA Astrophysics Data System (ADS)

    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

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  10. High Resolution UAV-based Passive Microwave L-band Imaging of Soil Moisture

    NASA Astrophysics Data System (ADS)

    Gasiewski, A. J.; Stachura, M.; Elston, J.; McIntyre, E. M.

    2013-12-01

    Due to long electrical wavelengths and aperture size limitations the scaling of passive microwave remote sensing of soil moisture from spaceborne low-resolution applications to high resolution applications suitable for precision agriculture requires use of low flying aerial vehicles. This presentation summarizes a project to develop a commercial Unmanned Aerial Vehicle (UAV) hosting a precision microwave radiometer for mapping of soil moisture in high-value shallow root-zone crops. The project is based on the use of the Tempest electric-powered UAV and a compact digital L-band (1400-1427 MHz) passive microwave radiometer developed specifically for extremely small and lightweight aerial platforms or man-portable, tractor, or tower-based applications. Notable in this combination are a highly integrated UAV/radiometer antenna design and use of both the upwelling emitted signal from the surface and downwelling cold space signal for precise calibration using a lobe-correlating radiometer architecture. The system achieves a spatial resolution comparable to the altitude of the UAV above the ground while referencing upwelling measurements to the constant and well-known background temperature of cold space. The radiometer incorporates digital sampling and radio frequency interference mitigation along with infrared, near-infrared, and visible (red) sensors for surface temperature and vegetation biomass correction. This NASA-sponsored project is being developed both for commercial application in cropland water management, L-band satellite validation, and estuarian plume studies.

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

    NASA Technical Reports Server (NTRS)

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

    2009-01-01

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

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

    PubMed

    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.

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

    PubMed

    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. PMID:22284877

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

    PubMed

    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.

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

    PubMed

    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. PMID:27128164

  16. The BAMM IIA Radiometer

    NASA Astrophysics Data System (ADS)

    Pohlman, R. T.

    1984-01-01

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

  17. Changes in North American snowpacks for 1979-2007 detected from the snow water equivalent data of SMMR and SSM/I passive microwave and related climatic factors

    NASA Astrophysics Data System (ADS)

    Gan, Thian Yew; Barry, Roger G.; Gizaw, Mesgana; Gobena, Adam; Balaji, Rajagopalan

    2013-07-01

    Changes to the North American snowpacks for 1979-2007 were detected from snow water equivalent (SWE) retrieved empirically from horizontally polarized brightness temperature (TB) of a scanning multichannel microwave radiometer (18 and 37 GHz) and special sensor microwave imager (19 and 37 GHz) passive microwave data using the nonparametric Kendall's test. The predominant SWE trends detected agree with negative anomalies in snow cover observed in Northern Hemisphere since the 1980s, and both the SWE and snow cover results should be related to the significant increase in the surface temperature of North America (NA) observed since the 1970s. About 30% of detected decreasing trends of SWE for 1979-2007 are statistically significant, which is three times more than the significant increasing trends of SWE detected in NA. Significant decreasing SWE trends are more extensive in Canada than in the United States. The mean trend magnitudes detected for December-April are -0.4 to -0.5 mm/yr, which means an overall reduction of snow depth of about 5-8 cm in 29 years (assuming a snowpack density between 200 and 250 kg/m3), which can impact regions relying on spring snowmelt for water supply. From detected increasing (decreasing) trends of gridded temperature (precipitation) based on the North American Regional Reanalysis data set and the University of Delaware data set for NA, their respective correlations with SWE data and other findings, such as global scale decline of snow cover, longer rainfall seasons, etc., it seems the extensive decreasing trends in SWE detected mainly in Canada are more caused by increasing temperatures than by decreasing precipitation. However, climate anomalies could also contribute to the detected trends, such as PC1 of NA's SWE, which is found to be correlated to the Pacific Decadal Oscillation index and marginally correlated to the Pacific North American pattern.

  18. The Boundary Layer Radiometer

    NASA Astrophysics Data System (ADS)

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

    2010-10-01

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

  19. Juno Microwave Radiometer Patch Array Antennas

    NASA Technical Reports Server (NTRS)

    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.

  20. [Comparison of thawing of plasma by microwave or water bath: preliminary longitudinal biological study of hemostatic parameters].

    PubMed

    Gris, J C; Joussemet, M; Bourin, P; Fabre, G; Schved, J F

    1988-10-01

    Exploration of haemostasis was performed on plasmas thawed in an experimental microwave oven comparatively to a 37 degrees C water bath. Factor VIII:R:Ag, procoagulant and antigenic fibrinogen, and Fg:C/Fg:Ag ratio were found to be significantly, slightly decreased with microwave thawing. Factor VIII:C and VIII:C/VIII:R:Ag ratio were found to be increased with microwaves. Antigenic fractions were decreased because of partial precipitation. In addition, Fibrinogen slightly lost its activity; on the contrary, factor VIIIC was activated by micro-waves. All this allows to select parameters for new experimental microwave ovens development.

  1. Aquarius L-band scatterometer and radiometer observations over a Tibetan Plateau site

    NASA Astrophysics Data System (ADS)

    Wang, Qiang; van der Velde, Rogier; Su, Zhongbo; Wen, Jun

    2016-03-01

    In this paper, the impact of freeze-thaw, soil moisture and vegetation on L-band backscatter and emission is studied using Aquarius scatterometer/radiometer measurements collected from August 2011 to May 2013 over the northeastern part of the Tibetan Plateau. The study area is the Maqu region that holds a regional-scale monitoring network consisting of twenty soil moisture/temperature stations, which is selected as one of the core international Calibration/Validation (Cal/Val) sites for NASA's Soil Moisture Active Passive (SMAP) mission. Comparisons of Aquarius scatterometer/radiometer measurements with soil moisture recorded by capacitance probes installed at a 5-cm soil depth illustrate that (i) L-band microwave observations are also sensitive to the amount of liquid water in soil below freezing point, and (ii) the sensitivity of Aquarius observations over the Maqu area dissipates above soil moisture contents of 0.3 m3 m-3. Further effects of vegetation become directly noticeable only within passive microwave observations at moisture levels larger than 0.4 m3 m-3. The impact of vegetation is studied in more detail through analysis of the Radar Vegetation Index (RVI). Although seasonal variability is captured, the dynamic range of the RVI is insufficient for a meaningful signal-to-noise. Further vegetation optical depth (τ) is estimated using the τ-ω concept by reconstructing the Microwave Polarization Difference Index (MPDI) derived from Aquarius radiometer data. Peaks in the τ estimates are noted in the months January/February and July/August. Evidence suggests that the magnitude of τ is a measure for the frost depth when temperatures are below freezing point whereas the behavior of τ in the warm season is in line with the vegetation dynamics.

  2. Retrievals of cloud optical depth and effective radius from Thin-Cloud Rotating Shadowband Radiometer measurements

    SciTech Connect

    Yin B.; Vogelmann A.; Min Q.; Duan M.; Bartholomew M. J.; Turner D. D.

    2011-12-13

    A Thin-Cloud Rotating Shadowband Radiometer (TCRSR) was developed and deployed in a field test at the Atmospheric Radiation Measurement Climate Research Facility's Southern Great Plains site. The TCRSR measures the forward-scattering lobe of the direct solar beam (i.e., the solar aureole) through an optically thin cloud (optical depth < 8). We applied the retrieval algorithm of Min and Duan (2005) to the TCRSR measurements of the solar aureole to derive simultaneously the cloud optical depth (COD) and cloud drop effective radius (DER), subsequently inferring the cloud liquid-water path (LWP). After careful calibration and preprocessing, our results indicate that the TCRSR is able to retrieve simultaneously these three properties for optically thin water clouds. Colocated instruments, such as the MultiFilter Rotating Shadowband Radiometer (MFRSR), atmospheric emitted radiance interferometer (AERI), and Microwave Radiometer (MWR), are used to evaluate our retrieval results. The relative difference between retrieved CODs from the TCRSR and those from the MFRSR is less than 5%. The distribution of retrieved LWPs from the TCRSR is similar to those from the MWR and AERI. The differences between the TCRSR-based retrieved DERs and those from the AERI are apparent in some time periods, and the uncertainties of the DER retrievals are discussed in detail in this article.

  3. Radiometer requirements for Earth-observation systems using large space antennas

    NASA Technical Reports Server (NTRS)

    Keafer, L. S., Jr.; Harrington, R. F.

    1983-01-01

    Requirements are defined for Earth observation microwave radiometry for the decade of the 1990's by using large space antenna (LSA) systems with apertures in the range from 50 to 200 m. General Earth observation needs, specific measurement requirements, orbit mission guidelines and constraints, and general radiometer requirements are defined. General Earth observation needs are derived from NASA's basic space science program. Specific measurands include soil moisture, sea surface temperature, salinity, water roughness, ice boundaries, and water pollutants. Measurements are required with spatial resolution from 10 to 1 km and with temporal resolution from 3 days to 1 day. The primary orbit altitude and inclination ranges are 450 to 2200 km and 60 to 98 deg, respectively. Contiguous large scale coverage of several land and ocean areas over the globe dictates large (several hundred kilometers) swaths. Radiometer measurements are made in the bandwidth range from 1 to 37 GHz, preferably with dual polarization radiometers with a minimum of 90 percent beam efficiency. Reflector surface, root mean square deviation tolerances are in the wavelength range from 1/30 to 1/100.

  4. Impact of microwave derived soil moisture on hydrologic simulations using a spatially distributed water balance model

    NASA Technical Reports Server (NTRS)

    Lin, D. S.; Wood, E. F.; Famiglietti, J. S.; Mancini, M.

    1994-01-01

    Spatial distributions of soil moisture over an agricultural watershed with a drainage area of 60 ha were derived from two NASA microwave remote sensors, and then used as a feedback to determine the initial condition for a distributed water balance model. Simulated hydrologic fluxes over a period of twelve days were compared with field observations and with model predictions based on a streamflow derived initial condition. The results indicated that even the low resolution remotely sensed data can improve the hydrologic model's performance in simulating the dynamics of unsaturated zone soil moisture. For the particular watershed under study, the simulated water budget was not sensitive to the resolutions of the microwave sensors.

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

    NASA Technical Reports Server (NTRS)

    Picard, Ghislain; Brucker, Ludovic; Roy, Alexandre; DuPont, FLorent; Champollion, Nicolas; Morin, Samuel

    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).

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

    NASA Technical Reports Server (NTRS)

    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.

  7. Aquarius Radiometer Status

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

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

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

    NASA Technical Reports Server (NTRS)

    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

  9. Quantifying Boundary Layer Water Vapor with Near-Infrared and Microwave Imagery

    NASA Astrophysics Data System (ADS)

    Millan Valle, L. F.; Lebsock, M. D.; Fishbein, E.; Kalmus, P.; Teixeira, J.

    2015-12-01

    This study investigates the synergy of collocated microwave radiometry and near-infrared imagery to estimate the planetary boundary layer water vapor. Microwave radiometry provides the total column water vapor, while the near-infrared imagery provides the water vapor above the cloud layers. The difference between the two gives the vapor between the surface and the cloud top, which may be interpreted as the boundary layer water vapor. In combining the two data sets, we apply several flags as well as proximity tests to remove pixels with high clouds and / or intrapixel heterogeneity. Comparisons against radiosondes (MAGIC, VOCALS-REX, etc) and ECMWF reanalysis data demonstrate the robustness of these boundary layer water vapor estimates. It is shown that the measured AMSR-MODIS boundary layer water vapor can be analyzed using sea surface temperature and cloud top pressure information by employing simple equations based on the Clausius-Clapeyron relationship.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    Asakuma, Yusuke; Munenaga, Takuya; Nakata, Ryosuke

    2015-10-01

    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.

  12. Microwave-induced increase of water and conductivity in submaxillary salivary gland of rats

    SciTech Connect

    Mikolajczyk, H.

    1981-01-01

    Hypersalivation is an important mechanism for heat dissipation by animals without sweat glands. The water content and conductivity (at 20 kHz) in submaxillary salivary glands (SSG) and in other tissues were investigated in adult male rats exposed to microwaves (2880 MHz, 1.5 microsecond pulses at 1000 Hz) or to conventional heat at 40 degrees C. Eighty rats in one series were exposed, one at a time, for 30 min to microwaves producing a specific absorption rate (SAR) of 4.2, 6.3, 6.8, 8.4, 10.8 or 12.6 W/kg. Fifty rats were sham-exposed under similar environmental conditions. In the second series, ten rats were sham-exposed, 33 rats were exposed one at time, for 15, 30 or 60 min to microwaves at a SAR of 9.5 W/kg, and 32 rats were exposed for similar periods to conventional heat at 40 degrees C. In rats of the first series colonic temperatures were elevated significantly at a SAR of 4.2 W/kg, while SSG water content and conductivity increased significantly at SAR values of 6.3 W/kg and higher. In the second series of experiments increases in colonic temperature and SSG water content were greater after 15 and 30 min of microwave exposure than after exposure to heat. Also, SSG conductivity was significantly depressed by heat and significantly increased by microwaves after exposure for 15 or 30 min. The results support the hypothesis that water content and conductivity of SSG of rats can be used as a sensitive specific test of a microwave induced thermal response.

  13. Stable radiometal antibody immunoconjugates

    DOEpatents

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

    1994-01-01

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

  14. Stable radiometal antibody immunoconjugates

    DOEpatents

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

    1994-08-02

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

  15. Sustainable synthesis of chemical entities by microwave heating with nano-catalysis in water

    EPA Science Inventory

    •Sustainable synthesis of chemical entities by microwave heating with nano-catalysis in water •CRADA’s with the private companies, CEM corporation and VeruTEK Technologies •Green Chemistry principles are accommodated via multi-faceted approach. Learning from nature- using na...

  16. Dielectric measurements of water in the radio microwave frequencies by time domain reflectometry

    SciTech Connect

    Merabet, M.; Bose, T.K.

    1988-10-20

    The time domain reflectometric method is used with success to measure the dielectric properties of water from 10 MHz to 8 GHz. It is shown that special precautions must be taken into account in order to determine the dielectric properties of a substance with high dielectric constant in the microwave region.

  17. Venus: implications from microwave spectroscopy of the atmospheric content of water vapor.

    PubMed

    Pollack, J B; Wood, A T

    1968-09-13

    From comparison of theoretical and observed microwave brightness temperatures of Venus at 1.35 centimeters, the center of a water-vapor line, we obtain an upper limit of 0.8 percent for the water-vapor mixing ratio in the lower atmosphere. This limit is consistent with the amount of water vapor detected by Venera 4, the existence of aqueous ice clouds, and a greenhouse effect caused by water vapor and carbon dioxide. The computed spectra suggest that a sensitive procedure for detection of water vapor is examination of the wavelength region between I and 1.4 centimeters.

  18. Improvement of coal water slurry property through coal physicochemical modifications by microwave irradiation and thermal heat

    SciTech Connect

    Jun Cheng; Junhu Zhou; Yanchang Li; Jianzhong Liu; Kefa Cen

    2008-07-15

    To improve the coal water slurry (CWS) property made from Chinese Shenhua coal with high inherent moisture and oxygen contents, microwave irradiation and thermal heat were employed to modify the coal physicochemical property. Microwave irradiation reduces the inherent moisture and reforms the oxygenic function groups, while it decreases the total specific surface area. Thermal heat markedly decreases the inherent moisture, volatile, and oxygen contents, while it dramatically increases the total specific surface area. Therefore, microwave irradiation gives a higher CWS concentration and a better rheological behavior than thermal heat, while it remarkably reduces the operation time and energy consumption. The maximum CWS concentration given by microwave irradiation at 420 W for 60 s is 62.14%, which is not only higher than that of 60.41% given by thermal heat at 450{sup o}C for 0.5 h but also higher than the initial 58.23%. Meanwhile, the minimum shear stress given by microwave irradiation is 36.4 Pa at the shear rate of 100 s{sup -1}, which is not only lower than that of 42.4 Pa given by thermal heat but also lower than the initial 79.8 Pa. The minimum unit energy consumption of 0.115 kWh/(kg of coal) and electricity cost of 4.6 U.S. $/(ton of coal) for CWS concentration promotion by 1% are obtained at 420 W for 20 s in the microwave oven. The unit energy consumptions for CWS concentration promotion and inherent moisture removal by thermal heat are, respectively, 214 and 22.5 times higher than those by microwave irradiation, while the energy use efficiencies are on the converse. 27 refs., 11 figs., 2 tabs.

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

    NASA Astrophysics Data System (ADS)

    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.

  20. MCM Polarimetric Radiometers for Planar Arrays

    NASA Technical Reports Server (NTRS)

    Kangaslahti, Pekka; Dawson, Douglas; Gaier, Todd

    2007-01-01

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

  1. Loss-compensated radiometer

    SciTech Connect

    Lobo, P.C.

    1984-05-01

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

  2. A Compact L-band Radiometer for High Resolution sUAS-based Imaging of Soil Moisture and Surface Salinity Variations

    NASA Astrophysics Data System (ADS)

    Gasiewski, A. J.; Stachura, M.; Dai, E.; Elston, J.; McIntyre, E.; Leuski, V.

    2014-12-01

    Due to the long electrical wavelengths required along with practical aperture size limitations the scaling of passive microwave remote sensing of soil moisture and salinity from spaceborne low-resolution (~10-100 km) applications to high resolution (~10-1000 m) applications requires use of low flying aerial vehicles. This presentation summarizes the status of a project to develop a commercial small Unmanned Aerial System (sUAS) hosting a microwave radiometer for mapping of soil moisture in precision agriculture and sea surface salinity studies. The project is based on the Tempest electric-powered UAS and a compact L-band (1400-1427 MHz) radiometer developed specifically for extremely small and lightweight aerial platforms or man-portable, tractor, or tower-based applications. Notable in this combination are a highly integrated sUAS/radiometer antenna design and use of both the upwelling emitted signal from the surface and downwelling cold space signal for precise calibration using a unique lobe-differencing correlating radiometer architecture. The system achieves a spatial resolution comparable to the altitude of the UAS above the surface while referencing upwelling measurements to the constant and well-known background temperature of cold space. The radiometer has been tested using analog correlation detection, although future builds will include infrared, near-infrared, and visible (red) sensors for surface temperature and vegetation biomass correction and digital sampling for radio frequency interference mitigation. This NASA-sponsored project is being developed for commercial application in cropland water management (for example, high-value shallow root-zone crops), landslide risk assessment, NASA SMAP satellite validation, and NASA Aquarius salinity stratification studies. The system will ultimately be capable of observing salinity events caused by coastal glacier and estuary fresh water outflow plumes and open ocean rainfall events.

  3. Stability and Demulsification of Water-in-Crude Oil (w/o) Emulsions Via Microwave Heating

    NASA Astrophysics Data System (ADS)

    Nour, Abdurahman. H.; Rosli; Yunus, Mohd.

    Formation of emulsions during oil production and processing is a costly problem, both in terms of chemicals used and production losses. Experimental data are presented to show the influences of Triton X-100, Low sulphur Wax Residue (LSWR), Sorbitan monooleate (Span 83) and Sodium Dedocyl Sulphate (SDDS) on the stability and microwave demulsification of emulsions. It was found that emulsion stability was related to some parameters such as, the surfactant concentrations, water-oil phase ratio (10-90%), temperature and agitation speed. For economic and operational reasons, it is necessary to separate the water completely from the crude oils before transporting or refining them. In this regard, the present study found that microwave radiation method can enhance the demulsification of water-in-oil (w/o) emulsions in a very short time compared to the conventional heating methods.

  4. Remote sensing of snow properties by passive microwave radiometry: GSFC truck experiment

    NASA Technical Reports Server (NTRS)

    Chang, A. T. C.; Rango, A.; Shiue, J.

    1980-01-01

    Recent results indicate that microwave radiometry has the potential for inferring the snow depth and water equivalent information from snowpacks. In order to assess this potential for determining the water equivalent of a snowpack, it is necessary to understand the microwave emission and scattering behavior of the snow at various wavelengths under carefully controlled conditions. Truck-mounted microwave instrumentation was used to study the microwave characteristics of the snowpack in the Colorado Rocky Mountain region during the winters of 1977 to 78 and 7978 to 79. The spectral signatures of C, X, K sub u, and K sub a band radiometers with dual polarization were used, together with measurements of snowpack density, temperature an ram profiles, liquid water content, and rough characterization of the crystal sizes. These data compared favorably with calculated results based on recent microscopic scattering models.

  5. The Radiometer Atmospheric Cubesat Experiment

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  6. Disintegration of water molecules in a steam-plasma torch powered by microwaves

    SciTech Connect

    Uhm, Han S.; Kim, Jong H.; Hong, Yong C.

    2007-07-15

    A pure steam torch is generated by making use of 2.45 GHz microwave. Steam from a steam generator enters the discharge tube as a swirl gas at a temperature higher than 150 deg. C. This steam becomes a working gas and produces a stable steam torch. The torch volume is almost linearly proportional to the microwave power. The temperature of the torch flame is measured by making use of optical spectroscopy and a thermocouple device. Two distinctive regions are exhibited, a bright, whitish region of a high-temperature zone and a reddish, dimmer region of a relatively low-temperature zone. The bright, whitish region is a typical torch based on plasma species and the reddish, dimmer region is hydrogen burning in oxygen. Study of water molecule disintegration and gas temperature effects on the molecular fraction characteristics in steam-plasma of a microwave plasma torch at the atmospheric pressure is carried out. An analytical investigation of water disintegration indicates that a substantial fraction of water molecules disintegrate and form other compounds at high temperatures in the steam-plasma torch. Emission profiles of the hydroxide radical and water molecules confirm the theoretical predictions of water disintegration in the torch.

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

    NASA Technical Reports Server (NTRS)

    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.

  8. Separation of oil-water-sludge emulsions coming from palm oil mill process through microwave techniques.

    PubMed

    Pérez-Páez, Rocío; Catalá-Civera, José Manuel; García-Baños, Beatriz; Castillo, Edgar F; Bastos, Johanna M; Zambrano, Luz S

    2008-01-01

    The palm oil mills extraction process requires the separation of oil-water-sludge emulsions. For this purpose, the use of sedimentation and/or centrifugation techniques have been required until now. However, significant losses persist in different process flows and new methods are needed to further decrease them, such as methods based on electromagnetic waves application. In the study, emulsions obtained from two flow processes, namely press liquor stream (PL) and recovered stream of the centrifugal step (RC), were exposed to microwave radiation with different exposure times. In the case of the press liquor stream, different oil/water dilution ratios were also studied. The sedimentation speed and efficiency were studied for the irradiated samples and compared to those obtained for the same fluids with no radiation. Also, chromatographic tests were performed on the recovered oil to determine the effect on the oil quality after microwave radiation. The obtained results allow us to conclude that microwave exposure during periods below 1 minute lead to better sedimentation speed and efficiency. It was observed that microwaves facilitate the break of the charges and polarities balances in the emulsions at considerably lower temperatures than the corresponding in the conventional process, without affecting the recovered oil quality.

  9. Design and implementation of a continuous microwave heating system for ballast water treatment.

    PubMed

    Boldor, Dorin; Balasubramanian, Sundar; Purohit, Shreya; Rusch, Kelly A

    2008-06-01

    A continuous microwave system to treat ballast water inoculated with different invasive species was designed and installed atthe Louisiana State University Agricultural Center. The effectiveness of the system to deliver the required heating loads to inactivate the organisms present was studied. The targeted organisms were microalgae (Nannochloropsis oculata), zooplankton at two different growth stages (newly hatched brine shrimp-Artemia nauplii and adult Artemia), and oyster larvae (Crassosstrea virginica). The system was tested at two different flow rates (1 and 2 liters per min) and power levels (2.5 and 4.5 kW). Temperature profiles indicate that, depending on the species present and the growth stage, the maximum temperature increase will vary from 11.8 to 64.9 degrees C. The continuous microwave heating system delivered uniform and near-instantaneous heating at the outlet proving its effectiveness. The power absorbed and power efficiency varied for the species present. More than 80% power utilization efficiency was obtained at all flow rate and microwave power combinations for microalgae, Artemia nauplii and adults. Test results indicated that microwave treatment can be an effective tool for ballast water treatment, and current high treatment costs notwithstanding, this technique can be added as supplemental technology to the palette of existing treatment methods. PMID:18589975

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  12. Microwave Brightness Of Land Surfaces From Outer Space

    NASA Technical Reports Server (NTRS)

    Kerr, Yann H.; Njoku, Eni G.

    1991-01-01

    Mathematical model approximates microwave radiation emitted by land surfaces traveling to microwave radiometer in outer space. Applied to measurements made by Scanning Multichannel Microwave Radiometer (SMMR). Developed for interpretation of microwave imagery of Earth to obtain distributions of various chemical, physical, and biological characteristics across its surface. Intended primarily for use in mapping moisture content of soil and fraction of Earth covered by vegetation. Advanced Very-High-Resolution Radiometer (AVHRR), provides additional information on vegetative cover, thereby making possible retrieval of soil-moisture values from SMMR measurements. Possible to monitor changes of land surface during intervals of 5 to 10 years, providing significant data for mathematical models of evolution of climate.

  13. Venus: new microwave measurements show no atmospheric water vapor.

    PubMed

    Janssen, M A; Hills, R E; Thornton, D D; Welch, W J

    1973-03-01

    Two sets of passive radio observations of Venus-measurements of the spectrum of the disk temperature near the 1-centimeter wavelength, and interferometric measurements of the planetary limb darkening at the 1.35-centimeter water vapor resonance-show no evidence of water vapor in the lower atmosphere of Venus. The upper limit of 2 x 10(-3) for the mixing ratio of water vapor is substantially less than the amounts derived from the Venera space probes (0.5 x 10(-2) to 2.5 x 10(-2)). This amount of water vapor cannot produce dense clouds, and it is doubtful that it may contribute significantly to a greenhouse effect.

  14. High resolution Microwave Spectrometer Sounder (HIMSS) instrument program. Appendix: TRMM study (an instrument for NASA's tropical rainfall measuring mission)

    NASA Technical Reports Server (NTRS)

    Lobl, E. (Editor)

    1991-01-01

    The TRMM (Tropical Rain Measuring Mission) Study shows the feasibility of a conically scanned, total power radiometer. The heritage of the TRMM radiometer is the Special Sensor Microwave/Imager (SSM/I) flying for the Air Force DMSP.

  15. Microwave radiometry for cement kiln temperature measurements.

    PubMed

    Stephan, Karl D; Wang, Lingyun; Ryza, Eric

    2007-01-01

    The maximum temperature inside a cement kiln is a critical operating parameter, but is often difficult or impossible to measure. We present here the first data that show a correlation between cement kiln temperature measured using a microwave radiometer and product chemistry over an eight-hour period. The microwave radiometer senses radiation in the 12-13 GHz range and has been described previously [Stephan and Pearce (2002), JMPEE 37: 112-124].

  16. Latitudinal survey of middle atmospheric water vapor revealed by shipboard microwave spectroscopy. Master's thesis

    SciTech Connect

    Schrader, M.L.

    1994-05-01

    Water vapor is one of the most important greenhouse gases and is an important tracer of atmospheric motions in the middle atmosphere. It also plays an important role in the chemistry of the middle atmosphere and through its photodissociation by solar radiation, it is the major source of hydrogen escaping to space. Ground-based microwave measurements conducted in the 1980s have provided a fair understanding of the seasonal variation of mesospheric water vapor in the northern hemisphere mid-latitudes, but the global distribution of water vapor in the middle atmosphere is only beginning to be revealed by space-based measurements.

  17. Influence of microwave parameters and water activity on radical generation in rice starch.

    PubMed

    Fan, Daming; Liu, Yixiao; Hu, Bo; Lin, Lufen; Huang, Luelue; Wang, Liyun; Zhao, Jianxin; Zhang, Hao; Chen, Wei

    2016-04-01

    Radical generation in rice starch under microwave treatment as well as the related chemical bond changes were investigated by electron paramagnetic resonance (EPR) and Raman spectroscopy. Samples with water activity of 0.4 and 0.7 have been treated and analyzed. It was found that microwave power level and water content could influence the amount of radicals along with the radical components and their contribution. Raman spectra showed corresponding changes in vibrational features of chemical bonds. During storage the signal intensity started to drop after a short period of increase. Rice starch radicals were relatively stable and could exist a long time in room temperature. Through signal simulation, 3 main components were separated from the original spectra and the evolving process was investigated. The main component was the radical located on C1 position in the glucose ring. PMID:26593462

  18. Influence of microwave parameters and water activity on radical generation in rice starch.

    PubMed

    Fan, Daming; Liu, Yixiao; Hu, Bo; Lin, Lufen; Huang, Luelue; Wang, Liyun; Zhao, Jianxin; Zhang, Hao; Chen, Wei

    2016-04-01

    Radical generation in rice starch under microwave treatment as well as the related chemical bond changes were investigated by electron paramagnetic resonance (EPR) and Raman spectroscopy. Samples with water activity of 0.4 and 0.7 have been treated and analyzed. It was found that microwave power level and water content could influence the amount of radicals along with the radical components and their contribution. Raman spectra showed corresponding changes in vibrational features of chemical bonds. During storage the signal intensity started to drop after a short period of increase. Rice starch radicals were relatively stable and could exist a long time in room temperature. Through signal simulation, 3 main components were separated from the original spectra and the evolving process was investigated. The main component was the radical located on C1 position in the glucose ring.

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

    NASA Astrophysics Data System (ADS)

    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

  20. Water vapor from sunradiometry in comparison wit microwave and balloon-sonde measurements at the Southern Great Plains ARM site

    SciTech Connect

    Michalsky, J.J.; Harrison, L.C.; Liljegren, J.C.

    1994-12-31

    Water vapor plays an important role in weather in climate; it is the most important greenhouse gas and the most variable in space and time. The DOE Atmospheric Radiation Measurement (ARM) program is studying the column abundance and distribution of water vapor with altitude. Although the Multi-Filter Rotating Shadowband Radiometer (MFRSR) is mainly for measurements of spectral short-wave radiation and spectral extinction by aerosol, it can also measure total column water vapor. This paper reports a preliminary investigation of MFRSR`s capabilities for total column water vapor under cloudless conditions.

  1. Time series inversion of spectra from ground-based radiometers

    NASA Astrophysics Data System (ADS)

    Christensen, O. M.; Eriksson, P.

    2013-07-01

    Retrieving time series of atmospheric constituents from ground-based spectrometers often requires different temporal averaging depending on the altitude region in focus. This can lead to several datasets existing for one instrument, which complicates validation and comparisons between instruments. This paper puts forth a possible solution by incorporating the temporal domain into the maximum a posteriori (MAP) retrieval algorithm. The state vector is increased to include measurements spanning a time period, and the temporal correlations between the true atmospheric states are explicitly specified in the a priori uncertainty matrix. This allows the MAP method to effectively select the best temporal smoothing for each altitude, removing the need for several datasets to cover different altitudes. The method is compared to traditional averaging of spectra using a simulated retrieval of water vapour in the mesosphere. The simulations show that the method offers a significant advantage compared to the traditional method, extending the sensitivity an additional 10 km upwards without reducing the temporal resolution at lower altitudes. The method is also tested on the Onsala Space Observatory (OSO) water vapour microwave radiometer confirming the advantages found in the simulation. Additionally, it is shown how the method can interpolate data in time and provide diagnostic values to evaluate the interpolated data.

  2. Time series inversion of spectra from ground-based radiometers

    NASA Astrophysics Data System (ADS)

    Christensen, O. M.; Eriksson, P.

    2013-02-01

    Retrieving time series of atmospheric constituents from ground-based spectrometers often requires different temporal averaging depending on the altitude region in focus. This can lead to several datasets existing for one instrument which complicates validation and comparisons between instruments. This paper puts forth a possible solution by incorporating the temporal domain into the maximum a posteriori (MAP) retrieval algorithm. The state vector is increased to include measurements spanning a time period, and the temporal correlations between the true atmospheric states are explicitly specified in the a priori uncertainty matrix. This allows the MAP method to effectively select the best temporal smoothing for each altitude, removing the need for several datasets to cover different altitudes. The method is compared to traditional averaging of spectra using a simulated retrieval of water vapour in the mesosphere. The simulations show that the method offers a significant advantage compared to the traditional method, extending the sensitivity an additional 10 km upwards without reducing the temporal resolution at lower altitudes. The method is also tested on the OSO water vapour microwave radiometer confirming the advantages found in the simulation. Additionally, it is shown how the method can interpolate data in time and provide diagnostic values to evaluate the interpolated data.

  3. Atmospheric Water Content over the Tropical Pacific Derived from the Nimbus-6 Scanning Microwave Spectrometer.

    NASA Astrophysics Data System (ADS)

    Grody, N. C.; Gruber, A.; Shen, W. C.

    1980-08-01

    The scanning microwave spectrometer (SCAMS) aboard Nimbus-6 contains a 22.23 GHz water vapor channel and 31.65 GHz window channel for deriving integrated water vapor (precipitable water) and cloud liquid water through a column over the oceans. The SCAMS derived parameters are based on a nonlinear relationship between the two channel measurements, and is shown to be more accurate than a linear model, particularly for the large values of precipitable water found in the tropics. Comparisons are made between the SCAMS derived precipitable water and 163 radiosonde measurements collected from 19 island stations over the tropical Pacific for the period between 18 August and 4 September 1975. The SCAMS values of precipitable water are shown to display the same variability as the radiosonde data, with a 0.5 cm rms difference.Fields of both precipitable water and liquid water derived by the SCAMS were averaged for the 2-week period for the ocean area between 130°E-100°W and 35°N-35°S. The Intertropical Convergence Zone was delineated near 10°N and contained greater than 5 cm of precipitable water and greater than 0.4 mm of liquid water. The Southern Convergence Zone is similarly well defined. Also exhibited were the dry zones in both hemispheres containing less than 3.5 cm of moisture and less than 0.2 mm of liquid water. These microwave derived parameters are of sufficient detail to be useful in studying both synoptic and climatic variations in the atmospheric water cycle.

  4. RF Reference Switch for Spaceflight Radiometer Calibration

    NASA Technical Reports Server (NTRS)

    Knuble, Joseph

    2013-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

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

  6. The Airborne Conical Scanning Millimeter-Wave Imaging Radiometer (CoSMIR)

    NASA Technical Reports Server (NTRS)

    Piepmeier, J. R.; Manning, W.; Wang, J. R.; Racette, P.; Krebs, Carolyn A. (Technical Monitor)

    2002-01-01

    Results of the first science flight of the airborne Conical Scanning Millimeter-wave Imaging Radiometer (CoSMIR) for high-altitude observations from the NASA ER-2 is discussed. Imagery collected from the flight demonstrates CoSMIR's unique conical/cross-track imaging mode and provides comparison of CoSMIR measurements to those of the Special Sensor Microwave/Temperature-2 (SSM/T-2) satellite radiometer.

  7. Characterization of an Ellipsoidal Radiometer

    PubMed Central

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

    2003-01-01

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

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

    PubMed

    Lofland, S E; Mazzatenta, J D; Croman, J; Tyagi, S D

    2007-03-01

    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 degrees 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.

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

    NASA Astrophysics Data System (ADS)

    Lofland, S. E.; Mazzatenta, J. D.; Croman, J.; Tyagi, S. D.

    2007-03-01

    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 °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 × 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.

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

    NASA Astrophysics Data System (ADS)

    Riffler, M.; Lieberherr, G.; Wunderle, S.

    2015-02-01

    Lake water temperature (LWT) is an important driver of lake ecosystems and it has been identified as an indicator of climate change. Consequently, the Global Climate Observing System (GCOS) lists LWT as an essential climate variable. 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, offering a unique opportunity for satellite-based climate studies. Herein we present a satellite-based lake surface water temperature (LSWT) data set for European water bodies in or near the Alps 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. The LSWT retrieval is based on a simulation-based scheme making use of the Radiative Transfer for TOVS (RTTOV) Version 10 together with ERA-interim reanalysis data from the European Centre for Medium-range Weather Forecasts. The resulting LSWTs were extensively compared with in situ measurements from lakes with various sizes between 14 and 580 km2 and the resulting biases and RMSEs were found to be within the range of -0.5 to 0.6 K and 1.0 to 1.6 K, respectively. The upper limits of the reported errors could be rather attributed to uncertainties in the data comparison between in situ and satellite observations than inaccuracies of the satellite

  11. Spectral characterization of water stress impact on some agricultural crops: III. Studies on Sudan grass and other different crops using handheld radiometer

    NASA Astrophysics Data System (ADS)

    Shakir Hanna, Safwat H.; Girmay-Gwahid, B.

    1999-12-01

    Vegetation monitoring has been one of the major targets of remote sensing studies. Remotely sensed reflectance concerning the impact of environmental factors upon crop vegetative cover can be predicted from two combinations of spectral bands as a ratio or as normalized vegetation indices. The most common spectral bands used lie in the red and infrared region (350 - 800 nm) and are dominated by the absorption of chlorophyll and other accessory pigments. In addition, reflectance in the middle infrared is dominated by absorption from liquid water contained in plant's tissues. The objectives of the present work are: (1) to evaluate the reflectance data from frequently irrigated and water stressed Sudan grass and other crops using a handheld radiometer and assess the spectral correlation with the ground-truth; (2) to evaluate the applications of a Hyperspectral Structure Component Index (HSCI) developed by Shakir and Girmay-Gwahid in 1998; and (3) to evaluate the application of Index of Relative Stress (IRS) proposed by Shakir and Girmay-Gwahid in 1998. The experiment was designed to collect reflectance data from Sudan grass and other crops planted at the Blythe Research Station, California in rows. The size of the plots for Sudan grass was in rows, the unstressed mature stands were 9 feet tall, and the stressed mature stands were 5 feet tall. The other fields are in nearby and planted with cotton crops in different stages of maturity. With a field spectrometer, the scan over each treatment was made at 1-hr intervals between 10:00 a.m. and 2:00 p.m. Pacific DayTime (PDT). Vegetative samples were taken from the two treatments during the initial sampling for purposes of conducting chemical analysis. Soil samples were collected to determine the amount of available soil moisture differences in the two treatments. The results of this experiment showed that in the 850 - 1150 nm wavelength ranges, the stressed Sudan grass stands showed lower reflectance than unstressed stands

  12. Empirical studies of the microwave radiometric response to rainfall in the tropics and midlatitudes

    NASA Technical Reports Server (NTRS)

    Petty, Grant W.; Katsaros, Kristina B.

    1989-01-01

    Results are presented from quantitative comparisons between satellite microwave radiometer observations and digital radar observations of equatorial convective cloud clusters and midlatitude frontal precipitation. Simultaneous data from the Winter Monsoon Experiment digital radar and the SMMR for December 1978 are analyzed. It is found that the most important differences between the microwave response to rainfall in the equatorial tropics and to stratiform rain in oceanic midlatitude fronts is caused by the different spatial characteristics of stratiform and convective rainfall and by the different background brightness temperature fields associated with tropical and midlatitude levels of atmospheric water vapor.

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

    PubMed

    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.

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

    SciTech Connect

    Turner, D. D.; McFarlane, S. A.; Riihimaki, L.; Shi, Y.; Lo, C.; Min, Q.

    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.

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

    NASA Astrophysics Data System (ADS)

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

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

  16. Estimating Soil Moisture from Satellite Microwave Observations

    NASA Technical Reports Server (NTRS)

    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

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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

  19. Nulling Infrared Radiometer for Measuring Temperature

    NASA Technical Reports Server (NTRS)

    Ryan, Robert

    2003-01-01

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

  20. Radiometers Optimize Local Weather Prediction

    NASA Technical Reports Server (NTRS)

    2010-01-01

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

  1. A hydrological analysis of east Australian floods using Nimbus-5 electrically scanning radiometer data

    NASA Technical Reports Server (NTRS)

    Allison, L. J.; Schmugge, T. J.; Byrne, G.

    1979-01-01

    The chronological development and diminution of six floods in eastern Australia during January, February, and March 1974 were mapped for the first time by the Nimbus Electrically Scanning Microwave Radiometer (ESMR). Day and nighttime ESMR (19.35 GHz) coverage was analyzed for the low gradient, flooded Darling River system in New South Wales. Apparent movement of surface water as indicated by low brightness temperatures (less than 250 K, day and less than 240 K, night) was easily followed around the curved runoff basin along the northern shoreline of the flooded Darling River during this 3-month period. This pattern was in good agreement with flood crest data at selected river height gage stations, even under cloudy conditions.

  2. Snow cover of the Upper Colorado River Basin from satellite passive microwave and visual imagery

    USGS Publications Warehouse

    Josberger, E.G.; Beauvillain, E.

    1989-01-01

    A comparison of passive microwave images from the Nimbus-7 Scanning Multichannel Microwave Radiometer (SMMR) and visual images from the Defense Meteorological Satellite Program (DMSP) of the Upper Colorado River Basin shows that passive microwave satellite imagery can be used to determine the extent of the snow cover. Eight cloud-free DMSP images throughout the winter of 1985-1986 show the extent of the snowpack, which, when compared to the corresponding SMMR images, determine the threshold microwave characteristics for snow-covered pixels. With these characteristics, the 27 sequential SMMR images give a unique view of the temporal history of the snow cover extent through the first half of the water year. -from Authors

  3. Pre-Launch Calibration and Performance Study of the PolarCube 3U Temperature Sounding Radiometer Mission

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    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 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. To ensure fidelity of data from the instrument, the following goals are being achieved: (i) precise numerical analysis of the diffracted field produced by corrugated feed and spinning reflector antenna system to the determination of an optimal feed horn and reflector geometry such that the system efficiencies are maximized and precisely known (ii) precise calibration of the receiver by accurate characterization of the sensitivity of radiometer components to physical temperature variations (iii) retrieval of atmospheric

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

    PubMed

    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.

  5. Temperature-dependent daily variability of precipitable water in special sensor microwave/imager observations

    NASA Technical Reports Server (NTRS)

    Gutowski, William J.; Lindemulder, Elizabeth A.; Jovaag, Kari

    1995-01-01

    We use retrievals of atmospheric precipitable water from satellite microwave observations and analyses of near-surface temperature to examine the relationship between these two fields on daily and longer time scales. The retrieval technique producing the data used here is most effective over the open ocean, so the analysis focuses on the southern hemisphere's extratropics, which have an extensive ocean surface. For both the total and the eddy precipitable water fields, there is a close correspondence between local variations in the precipitable water and near-surface temperature. The correspondence appears particularly strong for synoptic and planetary scale transient eddies. More specifically, the results support a typical modeling assumption that transient eddy moisture fields are proportional to transient eddy temperature fields under the assumption f constant relative humidity.

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

    NASA Astrophysics Data System (ADS)

    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.

  7. Characterizing Open Water Bodies and Wetland Ecosystems Using Optical and Microwave Remote Sensing

    NASA Astrophysics Data System (ADS)

    Podest, E.; McDonald, K. C.; Jensen, K.; Schroeder, R.

    2015-12-01

    Inundated vegetation and open water bodies are common features across the landscape and exert major impacts on hydrologic processes and surface-atmosphere carbon exchange. Their carbon emissions can have a large impact on global climate. It is therefore of great importance to assess their spatial extent and temporal variations in order to improve upon carbon balance estimates. Despite their importance in the global cycling of carbon and water and climate forecasting, they remain poorly characterized and modeled, primarily because of the scarcity of suitable regional-to-global remote sensing data for characterizing wetlands distribution and dynamics. Spaceborne microwave sensors are an effective tool for characterizing these ecosystems since they are sensitive to surface water and vegetation structure, and they can monitor large areas on a temporal basis regardless of atmospheric conditions or solar illumination. Optical sensors however provide much higher spatial resolution as well as information on water color. We developed a methodology using data from the Advanced Land Observing Satellite (ALOS) Phased Array L-Band Synthetic Aperture Radar (PALSAR) to map wetland ecosystems at 100 meter resolution for target regions as well as SMAP radar data at 1 km resolution. We also used optical data from Landsat to map open water bodies and their color properties at 15 meter resolution. Inundation dynamics of these ecosystems was assessed using a coarser resolution, 25 km microwave product on surface water fraction, which was derived using combined active and passive microwave data from QuikSCAT and AMSR-E on a weekly basis. We compare information content and accuracy of the coarse resolution products to the PALSAR, SMAP and Landsat based datasets to ensure information harmonization. The combination of high and low resolution datasets will allow for characterization of wetlands and open water bodies and assessment of their flooding status. This work has been undertaken

  8. HELIOS dual swept frequency radiometer

    NASA Technical Reports Server (NTRS)

    White, J. R.

    1975-01-01

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

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

    NASA Technical Reports Server (NTRS)

    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

  10. Soil moisture sensing with microwave techniques

    NASA Technical Reports Server (NTRS)

    Schmugge, T.

    1980-01-01

    Microwave approaches for the remote sensing of soil moisture are discussed, with the advantages described as follows: (1) the all-weather capability, (2) the greater penetration depth into the soil and through vegetation than with optical or infrared sensors, and (3) the large changes in the dielectric properties of soil produced by changes in water content. Both active and passive microwave approaches are discussed. The dependence of the relationship between microwave response and soil moisture on such things as soil texture, surface roughness, vegetative cover and nonuniform moisture and temperature profiles is analyzed from both the experimental and theoretical viewpoints. The dielectric properties of the soil are analyzed quantitatively, as these control the reflective and emissive properties of the soil surface, and a model for estimating a soil's dielectric properties from its texture and moisture content is also presented. Emissivity is calculated using the Fresnel equation of electromagnetic theory, and reflectivity is shown to be decreased by surface roughness, while the backscatter coefficient increases. It is demonstrated, that microwave radiometers are sensitive to soil moisture for a wide range of surface conditions, and that the longer wavelengths are best for soil moisture sensing.

  11. Recent Improvements in Retrieving Near-Surface Air Temperature and Humidity Using Microwave Remote Sensing

    NASA Technical Reports Server (NTRS)

    Roberts, J. Brent

    2010-01-01

    Detailed studies of the energy and water cycles require accurate estimation of the turbulent fluxes of moisture and heat across the atmosphere-ocean interface at regional to basin scale. Providing estimates of these latent and sensible heat fluxes over the global ocean necessitates the use of satellite or reanalysis-based estimates of near surface variables. Recent studies have shown that errors in the surface (10 meter)estimates of humidity and temperature are currently the largest sources of uncertainty in the production of turbulent fluxes from satellite observations. Therefore, emphasis has been placed on reducing the systematic errors in the retrieval of these parameters from microwave radiometers. This study discusses recent improvements in the retrieval of air temperature and humidity through improvements in the choice of algorithms (linear vs. nonlinear) and the choice of microwave sensors. Particular focus is placed on improvements using a neural network approach with a single sensor (Special Sensor Microwave/Imager) and the use of combined sensors from the NASA AQUA satellite platform. The latter algorithm utilizes the unique sampling available on AQUA from the Advanced Microwave Scanning Radiometer (AMSR-E) and the Advanced Microwave Sounding Unit (AMSU-A). Current estimates of uncertainty in the near-surface humidity and temperature from single and multi-sensor approaches are discussed and used to estimate errors in the turbulent fluxes.

  12. Radiometer system to map the cosmic background radiation.

    PubMed

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

    1978-04-01

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

  13. Radiometer system to map the cosmic background radiation

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

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

  14. Mapping the spatial distribution and time evolution of snow water equivalent with passive microwave measurements

    USGS Publications Warehouse

    Guo, J.; Tsang, L.; Josberger, E.G.; Wood, A.W.; Hwang, J.-N.; Lettenmaier, D.P.

    2003-01-01

    This paper presents an algorithm that estimates the spatial distribution and temporal evolution of snow water equivalent and snow depth based on passive remote sensing measurements. It combines the inversion of passive microwave remote sensing measurements via dense media radiative transfer modeling results with snow accumulation and melt model predictions to yield improved estimates of snow depth and snow water equivalent, at a pixel resolution of 5 arc-min. In the inversion, snow grain size evolution is constrained based on pattern matching by using the local snow temperature history. This algorithm is applied to produce spatial snow maps of Upper Rio Grande River basin in Colorado. The simulation results are compared with that of the snow accumulation and melt model and a linear regression method. The quantitative comparison with the ground truth measurements from four Snowpack Telemetry (SNOTEL) sites in the basin shows that this algorithm is able to improve the estimation of snow parameters.

  15. High power water load for microwave and millimeter-wave radio frequency sources

    DOEpatents

    Ives, R. Lawrence; Mizuhara, Yosuke M.; Schumacher, Richard V.; Pendleton, Rand P.

    1999-01-01

    A high power water load for microwave and millimeter wave radio frequency sources has a front wall including an input port for the application of RF power, a cylindrical dissipation cavity lined with a dissipating material having a thickness which varies with depth, and a rear wall including a rotating reflector for the reflection of wave energy inside the cylindrical cavity. The dissipation cavity includes a water jacket for removal of heat generated by the absorptive material coating the dissipation cavity, and this absorptive material has a thickness which is greater near the front wall than near the rear wall. Waves entering the cavity reflect from the rotating reflector, impinging and reflecting multiple times on the absorptive coating of the dissipation cavity, dissipating equal amounts of power on each internal reflection.

  16. Observations of precipitable water vapor fluctuations in convective boundary layer via microwave interferometry

    SciTech Connect

    Shao, X.M.; Carlos, R.C.; Kirkland, M.W.; Kao, C.J.; Jacobson, A.R.

    1999-07-01

    At microwave frequencies, each centimeter of precipitable water vapor (PWV) causes about 6.45 cm of extra electrical path length relative to the {open_quotes}dry{close_quotes} air. The fluctuations of the water vapor dominate the changes of the effective path length through the atmosphere in a relatively short time period of a few hours. In this paper we describe a microwave interferometer developed for water vapor investigations and present the observation results. The interferometer consists of 10 antennas along two orthogonal 400-m arms that form many baselines (antenna pairs) ranging from 100 to 400 m. All the antennas receive a common CW signal (11.7 GHz) from a geostationary television satellite, and phase differences between pairs of antennas are measured. The phase differences reflect the column-integrated water vapor differences from the top of the atmosphere to the spatially separated antennas at the ground. The interferometric, baseline-differential measurements allow us to study the statistical properties of the PWV fluctuations, as well as the turbulent activity of the convective boundary layer (CBL). Structure function analysis of the interferometer measurements shows good agreement with results obtained from the Very Large Array (VLA) and with a theoretical model developed for radio astronomical very long baseline interferometry (VLBI), reported previously by other investigators. The diurnally varying structure constant correlates remarkably well with the combination of the latent and sensible heat fluxes measured simultaneously from a 10-m meteorological tower. The average drift velocity of the PWV over the interferometer was also derived from the measurements. The derived velocity agrees well during the morning hours with the wind measured by an anemometer at the center of the interferometer. {copyright} 1999 American Geophysical Union

  17. Microwave Limb Sounder/El Nino Watch - Water Vapor Measurement, October, 1997

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This image shows atmospheric water vapor in Earth's upper troposphere, about 10 kilometers (6 miles) above the surface, as measured by the Microwave Limb Sounder (MLS) instrument flying aboard the Upper Atmosphere Research Satellite. These data collected in early October 1997 indicate the presence of El Nino by showing a shift of humidity from west to east (blue and red areas) along the equatorial Pacific Ocean. El Nino is the term used when the warmest equatorial Pacific Ocean water is displaced toward the east. The areas of high atmospheric moisture correspond to areas of very warm ocean water. Warmer water evaporates at a higher rate and the resulting warm moist air then rises, forming tall cloud towers. In the tropics, the warm water and the resulting tall cloud towers typically produce large amounts of rain. The MLS instrument, developed at NASA's Jet Propulsion Laboratory, measures humidity at the top of these clouds, which are very moist. This rain is now occurring in the eastern Pacific Ocean and has left Indonesia (deep blue region) unusually dry, resulting in the current drought in that region. This image also shows moisture moving north into Mexico, an effect of several hurricanes spawned by the warm waters of El Nino.

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

    NASA Technical Reports Server (NTRS)

    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

  19. Effects of “natural” water and “added” water on prediction of moisture content and bulk density of shelled corn from microwave dielectric properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 oC. Results of measurements of attenuation, phase shift and dielectric constant and loss factor at 9 GHz show no difference betw...

  20. Utilization of active microwave roughness measurements to improve passive microwave soil moisture estimates over bare soils

    NASA Technical Reports Server (NTRS)

    Theis, S. W.; Blanchard, B. J.; Blanchard, A. J.

    1984-01-01

    Multisensor aircraft data were used to establish the potential of the active microwave sensor response to be used to compensate for roughness in the passive microwave sensor's response to soil moisture. Only bare fields were used. It is found that the L-band radiometer's capability to estimate soil moisture significantly improves when surface roughness is accounted for with the scatterometers.