Microwave radiometer Research Papers - Academia.edu (original) (raw)

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

- by
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- High Frequency, Dielectric Constant, Radiative Transfer, Acoustic Radiative Transfer Model

A dual-channel microwave radiometer that measures precipitable water vapor and cloud liquid was operated during the 1979 Severe Storms and Mesoscale Experiment (Sesame). Conventional retrievals of vapor in the presence of clouds with high liquid content were not satisfactory. To correct these retrievals, an adaptive retrieval algorithm is developed and applied to the Sesame data. During clear conditions, or conditions of light clouds, the new recoveries are quite close to those obtained by conventional statistical inversion; however, during heavy liquid-bearing clouds the recovered vapor agrees better with radiosonde data.

- by E. Westwater
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- Multidisciplinary, Gulf of Mexico, Microwave radiometer, Precipitable Water Vapor

In order to correct the altimeter range for tropospheric humidity, a microwave radiometer is added to altimetry missions. Over open ocean, the combination altimeter/radiometer is satisfactory. This is not the case in coastal zones, where the signal coming from the surrounding land surfaces contaminates the radiometer measurement and makes the humidity retrieval method unsuitable. In this paper, a radiometer simulator is built. This simulator is used to evaluate the current methods to retrieve the wet tropospheric correction in transition areas. The purpose of this paper is to analyze and compare the performances of these methods. After examining simple correction methods (extension of the open sea wet tropospheric correction, use of the meteorological model value), we evaluated the feasibility and performances of two methods which propose to take into account the land surface effect in the brightness temperature estimation. The latter was found to give significantly better results.

- by estelle obligis
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- Geophysics, Geoscience and remote sensing, Models, Field Experiment

The Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) was developed and provided to the National Aeronautics and Space Administration's EOS Aqua satellite by the National Space Development Agency of Japan, as one of the indispensable instruments for Aqua's mission. AMSR-E is a modified version of AMSR that was launched December 2002 aboard the Advanced Earth Observing Satellite-II (ADEOS-II). It is a six-frequency dual-polarized total-power passive microwave radiometer that observes water-related geophysical parameters supporting global change science and monitoring efforts. The hardware improvements over existing spaceborne microwave radiometers for earth imaging include the largest main reflector of its kind and addition of 6.925-GHz channels. These improvements provide finer spatial resolution and the capability to retrieve sea surface temperature and soil moisture information on a global basis. This paper provides an overview of the instrument characteristics, mission objectives, and data products.

- by Roy Spencer
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- Geophysics, Energy, Earth, Climate

To improve efficiency of non-invasive monitoring of the internal brain temperature, a small-size single-channel microwave radiothermograph consisting of a miniature radiometer and a radiometric sensor based on a printed antenna was developed. Such solution is necessary to provide physicians with a system of non-invasive monitoring of diagnosis and treatment processes. Mathematical modeling and experimental verification of the technical solutions obtained are described in this paper. A miniature radiothermometer was developed. It is a balance modulation radiometer designed on the basis of the R.H. Dicke’s circuit with two loads. Taking into account the requirements of miniaturization, a radiometric sensor was developed by means of numerical simulation. As a result of calculations, optimum antenna dimensions were determined (the total size: ø30 mm, the size of the foil flane substrate: ø23 mm, dimensions of the emitter slot: 16 mm×2 mm). According to the mathematical modeling, the depth of detection of thermal anomalies was not less than 20 mm for the printed antenna which is practically the same as for the waveguide antenna successfully used at present in brain radiothermometry. The standing wave coefficient was determined for various head regions: frontal, temporal, parietal, occipital and the transient between the occipital and parietal regions. Experimental tests of the radiothermograph on water phantoms and biological objects have been carried out. A very good coincidence between the data of numerical simulation and the physical SWR experiment in a range of 1.04–1.8 was obtained. As a result of the study, it has been found that the radiothermograph with a printed slot antenna enabled measurement of internal brain temperature with an acceptable accuracy (±0.2 °C). This will ensure control of craniocerebral hypothermia in patients with brain stroke and allow doctors to promptly change the hypothermia tactics. Small size of the created unit will make it possible to combine it with medical robotic systems to improve treatment effectiveness.

- by Sergey Vesnin
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- Biomedical Engineering, Microwave, Temperature Sensors, Microwave radiometer

Data were acquired by the Passive and Active Land S-band airborne sensor (PALS) during the 1999 Southern Great Plains (SGP99) experiment in Oklahoma to study remote sensing of soil moisture in vegetated terrain using low-frequency microwave radiometer and radar measurements. The PALS instrument measures radiometric brightness temperature and radar backscatter at L-and S-band frequencies with multiple polarizations and approximately equal spatial resolutions. The data acquired during SGP99 provide information on the sensitivities of multichannel low-frequency passive and active measurements to soil moisture for vegetation conditions including bare, pasture, and crop surface cover with field-averaged vegetation water contents mainly in the 0-2.5 kg m 2 range. Precipitation occurring during the experiment provided an opportunity to observe wetting and drying surface conditions. Good correlations with soil moisture were observed in the radiometric channels. The 1.41-GHz horizontal-polarization channel showed the greatest sensitivity to soil moisture over the range of vegetation observed. For the fields sampled, a radiometric soil moisture retrieval accuracy of 2.3% volumetric was obtained. The radar channels showed significant correlation with soil moisture for some individual fields, with greatest sensitivity at 1.26-GHz vertical copolarized channel. However, variability in vegetation cover degraded the radar correlations for the combined field data. Images generated from data collected on a sequence of flight lines over the watershed region showed similar patterns of soil moisture change in the radiometer and radar responses. This indicates that under vegetated conditions for which soil moisture estimates may not be feasible using current radar algorithms, the radar measurements nevertheless show a response to soil moisture change, and they can provide useful information on the spatial and temporal variability of soil moisture. An illustration of the change detection approach is given.

- by Venkataraman Lakshmi
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- Geophysics, Algorithms, Remote Sensing, Microwave

A multifrequency passive microwave remote sensing system was deployed during a ground-based experiment. conducted near Huntsville, Alabama in 1996. The S and L band microwave radiometers were able to detect both the large scale moisture changes due to the irrigation and rainfall events and also diurnal fluctuations in surface soil moisture content. Using a two frequency system provides much more information about near-surface soil water dynamics than does a single frequency. SETTING A research testbed was established at Alabama A&M University's Agricultural Experiment Station located about 20 km north of Huntsville, Alabama. The testbed consisted of four 50 x 60 m plots, two without vegetation, one with a tall fescue cover, and another with a mixture of vegetation. Surface soil texture was mostly silty clay loam, but clay content increased with depth from 24% at the surface to about 50% at 1 m. During installation of sensors in the soil pits, major horizons were sampled for analysis of bulk density and hydraulic conductivity.

- by Andrew Manu
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- Remote Sensing, Hydrology, Irrigation, Soil moisture

Introduction The principle of action of microwave radiometers is based on recording microwave radiation from biological objects (BO) whose temperature is above absolute zero. Measurements of the intensity of body radiation can be used to determine its temperature. This method is termed microwave radiometry (MR). MR is a functional diagg nostic method based on passive radiooheat location [1]. In contrast to infrared thermography, MR provides for noninvasive identification of thermal anomalies at depths of several centimeters. MR is currently used to detect breast cancer [2] and melanomas [3], in monitoring the temperature of the brain [4], and in gynecology [5] and other areas. The radiometer includes an antenna applicaa tor (or several antenna applicators) and a highhsensitivity radiometric receiver. The recorded power of the BO defines the brightness temperature (BT), which is linked to the thermodynamic temperature as (1) where T(r) is the thermodynamic temperature of the BO and W(r) is the radiometric weighting function of the antenna. Integration is performed in terms of BO volume, V. W(r) is defined as (2) where P is the electromagnetic power loss density per unit volume due to absorption, P 0 is the total power dissipatt ed, E(r) is the tension of the electric field of the antenna, and σ(r) is electrical conductivity of the BO. Thus, BT is the averaged thermodynamic temperature of the BO with weighting W(r). Methods Microwave radiation in medical radiometers is detected using special antenna applicators − printed types [6610], waveguides [2, 4], and vibrator and frame types [1, 10], as well as intracavity antennas [5]. Waveguide antenn nas are segments of waveguides in contact with the BO. The most widely used are round waveguides, as the sharp angles of rectangular waveguides are traumatic for patients. Waveguide antennas are connected to the input cascade of the radiometer via a coaxial cable, so the outt put is sent to a microwave connector. Matching of the waveguide is done in various ways; the most common uses a "butterfly" slot [5]. Waveguide antennas are simple to design, have small electrical losses, high measurement depth, adequate shielding, and acceptable matching with the body. The size of the waveguide is usually decreased by The physical basis of microwave radiometry and the construction and technical characteristics of different types of antenna applicators used in medical radiometers are discussed. We present results obtained during the devell opment and the potential uses of new types of antenna applicators in different areas of medicine.

Validation is an important and particularly challenging task for remote sensing of soil moisture. A key issue in the validation of soil moisture products is the disparity in spatial scales between satellite and in situ observations. Conventional measurements of soil moisture are made at a point, whereas satellite sensors provide an integrated area/volume value for a much larger spatial extent. In this paper, four soil moisture networks were developed and used as part of the Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) validation program. Each network is located in a different climatic region of the U.S., and provides estimates of the average soil moisture over highly instrumented experimental watersheds and surrounding areas that approximate the size of the AMSR-E footprint. Soil moisture measurements have been made at these validation sites on a continuous basis since 2002, which provided a seven-year period of record for this analysis. The National Aeronautics and Space Administration (NASA) and Japan Aerospace Exploration Agency (JAXA) standard soil moisture products were compared to the network observations, along with two alternative soil moisture products developed using the single-channel algorithm (SCA) and the land parameter retrieval model (LPRM). The metric used for validation is the root-mean-square error (rmse) of the soil moisture estimate as compared to the in situ data. The mission requirement for accuracy defined by the space agencies is 0.06 m 3 /m 3. The statistical results indicate that each algorithm performs differently at each site. Neither the NASA nor the JAXA standard products provide reliable estimates for all the conditions represented by the four watershed sites. The JAXA algorithm performs better than the NASA algorithm under light-vegetation conditions,

- by Shenfu Dong
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- Environmental Science, Geophysics, Algorithms, Microwave
- by Ranendu Ghosh
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- Remote Sensing, Satellite remote sensing, Level Of Detail (LOD), Forest fire
- by Karen St Germain
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- Remote Sensing, Climate Change, Climate Model, Microwave radiometer

Precipitation is a complex phenomenon which is characterized by a significant variability both in time and space. Conventional measurements, such those of rain gauges, can only provide a limited information of its microphysical properties and dynamical features. In this respect, disdrometer surface measurements can help in exploring the raindrop size distribution. This paper provides an overview of these observation techniques, their physical background and some recent results. Specifically, ground-based techniques to observe precipitation using surface disdrometers, multifrequency microwave radiometers and microwave polarimetric radars will be discussed and illustrated. By exploiting this remote and in-situ instrumentation, estimates of precipitation optical thickness, liquid, ice and melted hydrometeor category, and their size distribution can be obtained.

A comparison of the determination of boundary-layer structures by a SODAR, by a RASS, and by a ceilometer is presented. One important structure is the mixing-layer height (MLH). The comparison is focused on 3 days with an evolution of a convective boundary layer over a larger city in Germany. The three instruments give information that partly agree and partly complement each other. By this, a picture of the diurnal evolution of the vertical structure of this urban boundary layer is presented. The ceilometer gives information on the aerosol content of the air and the RASS provides a direct measurement of the vertical temperature distribution in the boundary layer. The RASS and the ceilometer add information on the moisture structure of the boundary layer that is not detected by the SODAR. On the other hand this comparison validates known techniques by which the MLH is derived from SODAR data. Especially the temperature information from the RASS agrees well with lifted inversions derived from the analysis of the SODAR data. The ceilometer, being the smallest instrument, has a potential to be used in future MLH studies. r

- by Stefan Emeis and +1
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- Environmental Engineering, Remote Sensing, Atmospheric sciences, Turbulent boundary layer

In this paper, we present a new method for the design of multi-band microstrip filters. The proposed design method is based on Differential Evolution (DE) with strategy adaptation. This selfadaptive DE (SaDE) uses previous experience in both trial vector generation strategies and control parameter tuning. We apply this algorithm to two design cases of dual and tri-band filters for WiFi and WiMax applications. We select the Open Loop Ring Resonator (OLRR) filters, which are comprised of two uniform microstrip lines and pairs of open loops between them. The results indicate the advantages of this approach and the applicability of this design method.

- by Sotiris Goudos
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- Engineering, Distributed Computing, Microstrip Antennas, Computational Modeling

Detrended fluctuation analysis (DFA) is used to investigate correlations between the monthly average of the maximum daily temperatures for different locations in the continental United States and the different climates these locations have. When we plot the scaling exponents obtained from the DFA versus the standard deviation of the temperature fluctuations, we observe crowding of data points belonging to the same climates. Thus, we conclude that by observing the long-time trends in the fluctuations of temperature it would be possible to distinguish between different climates.

A long-term global atmospheric reanalysis, named ''Japanese 25-year Reanalysis (JRA-25)'' was completed using the Japan Meteorological Agency (JMA) numerical assimilation and forecast system. The analysis covers the period from 1979 to 2004. This is the first long-term reanalysis undertaken in Asia. JMA's latest numerical assimilation system, and specially collected observational data, were used to generate a consistent and high-quality reanalysis dataset designed for climate research and operational monitoring and forecasts. One of the many purposes of JRA-25 is to enhance the analysis to a high quality in the Asian region. Six-hourly data assimilation cycles were performed, producing 6-hourly atmospheric analysis and forecast fields of various physical variables. The global model used in JRA-25 has a spectral resolution of T106 (equivalent to a horizontal grid size of around 120 km) and 40 vertical layers with the top level at 0.4 hPa. In addition to conventional surface and upper air observations, atmospheric motion vector (AMV) wind retrieved from geostationary satellites, brightness temperature from TIROS Operational Vertical Sounder (TOVS), precipitable water retrieved from orbital satellite microwave radiometer radiance and other satellite data are assimilated with three-dimensional variational method (3D-Var). JMA produced daily sea surface temperature (SST), sea ice and three-dimensional ozone profiles for JRA-25. A new quality control method for TOVS data was developed and applied in advance. Many advantages have been found in the JRA-25 reanalysis. Predicted 6-hour global total precipitation distribution and amount are well reproduced both in space and time. The performance of the long time series of the global precipitation is the best among the other reanalyses, with few unrealistic variations from degraded satellite data contaminated by volcanic eruptions. Secondly, JRA-25 is the first reanalysis to assimilate wind profiles around tropical cyclones reconstructed from historical best track information; tropical cyclones were analyzed properly in all the global regions. Additionally, low-level cloud along the subtropical western coast of continents is well simulated and snow depth analysis is also of a good quality. The article also covers material which requires attention when using JRA-25.

- by Kevin Trenberth
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- Environmental Science, Time Series, Data Assimilation, Sea Ice

Satellite observations using microwave radiometers operating near the window regions are strongly affected by surface emissivity. Presently, the measurements obtained over land are not directly utilized in numerical weather prediction models because of uncertainties in estimating the emissivity. This study develops a new model to quantify the land emissivity over various surface conditions. For surfaces such as snow, deserts, and vegetation, volumetric scattering was calculated using a two-stream radiative transfer approximation. The reflection and transmission at the surface-air interface and lower boundary were derived by modifying the Fresnel equations to account for crosspolarization and surface roughness effects. Several techniques were utilized to compute the optical parameters for the medium, which is used in the radiative transfer solution. In the case of vegetation, geometrical optics is used because the leaf size is typically larger than the wavelength. For snow and deserts, a dense medium theory was adopted to take into account the coherent scattering of closely spaced particles. The emissivity spectra at frequencies between4.9 and94 GHz was simulated and compared with the ground-based radiometer measurements for bare soil, grass land, and snow conditions. It is shown that the features including the spectra, variability, and polarization agree well with the measurements. The simulated global distribution of land surface emissivity is also compared with the satellite retrievals from the Advanced Microwave Sounding Unit (AMSU). It is found that the largest discrepancies primarily occur over high latitudes where the snow properties are complex and least understood.

- by Norman Grody
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- Remote Sensing, Multidisciplinary, Surface Roughness, Numerical Simulation

Journal of Oceanography, Vol. 58, pp. 137 to 151, 2002 Review Microwave Remote Sensing of Tropical Cyclones from Space Kristina В. Katsaros1*, Paris W. Vachon2, W. Timothy Liu3 and Peter G. Black1 1 NOAA/Atlantic Océanographie and... more

- by Kristina Katsaros
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- Oceanography, Microwave Remote Sensing, Synthetic Aperture Radar, Typhon

Boundary layer measurements in Nangatchori, Benin were performed over the period of one full year (2006) using a novel ground-based microwave profiler and additional remote-sensing instruments. In this paper, the diurnal cycle of the ITD (Inter-Tropical Discontinuity) in the transition period between dry and wet season during the month of April is described in detail. Dry air masses from the north (Sahel) and moist air from the south (tropical Atlantic Ocean) cause very sharp temperature and humidity gradients in the low troposphere over West Africa.

- by Susanne Crewell
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- Atmospheric sciences, Microwave radiometer, Boundary Layer, Transition Period

In studies of weather changes and, especially, in enhancing the performance of rainfall prediction, it is important to measure the water vapor distribution in the atmosphere. We estimated atmospheric water vapor profiles for fourteen days, including periods of severe weather conditions, by processing ground-based Global Positioning System (GPS) measurements and compared our results with microwave radiometer (MWR) and radiosonde (RAOB) observations. As a result, we found that the standard deviation (STD) of wet refractivity profiles between GPS with MWR was smaller than the STD between RAOB and MWR refractivities; the average STD was 9.3 mm km−1. In particular, we found that GPS-based wet refractivities detected inversion layers close to those from MWR when the observed GPS satellites were well distributed in the azimuth and elevation angle directions. When the satellite geometry was better, the mean error of GPS wet refractivities with respect to MWR was reduced to 0.4 from 3.2 mm km−1 for altitudes lower than 3 km. In some cases, however, the precision of GPS refractivities are lower than that of RAOB ones relative to MWR results.

- by Kwan-Dong Park
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- GPS, Atmospheric sciences, Standard Deviation, Microwave radiometer

The antenna temperature measured by a microwave radiometer is converted in brightness temperature (TB) by removing the different contributions that do not come from the main lobe of the antenna. Among them, the Earth contribution in the sidelobes may be significant as for the Environmental Satellite mission due to the antenna position on the platform. In such a case, simple corrections commonly applied on previous altimetry missions are inadequate, and a more accurate correction should be determined. We propose in this paper a new method based on global seasonal tables of contamination. This allows application of an accurate sidelobe correction in space and time in the retrieved TB computation.

- by ngan tran
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- Geophysics, Earth, Seasonality, Geomatic Engineering

A technique to measure both sea surface temperature and sea-air temperature difference from an airborne platform is described. The technique uses a scanning microwave radiometer operating in the 5-mm oxygen absorption band. To independently measure the sea surface temperature, a nadir-viewing infrared radiometer operating near 10 micrometers was also operated. Retrievals of the water-air temperature difference from the 5-mm wavelength radiometer data are presented and compared with buoy measurements. An additional comparison of water temperature measurements by microwave radiometer, infrared radiometer, and buoys is presented.

- by Vladimir Irisov and +1
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- Sea surface temperature, Water Temperature, Infrared, Air Temperature

The Atmospheric Infrared Sounder (AIRS), the Advanced Microwave Sounding Unit (AMSU) and the HSB (Humidity Sounder Brazil) form an integrated cross-track scanning temperature and humidity sounding system on the Aqua satellite of the Earth Observing System (EOS). AIRS is an infrared spectrometer/radiometer which covers the 3.7 -15.4 µm spectral range with 2378 spectral channels. AMSU is a 15 channel microwave radiometer operating between 23 and 89 GHz, and HSB is a four-channel microwave radiometer between 150 and 190GHz. In addition to supporting NASA's interest in process study and climate research, AIRS is the first hyperspectral infrared radiometer designed to support NOAA/NCEP's operational requirements for medium-range weather forecasting during its nominal 7-year lifetime. AIRS, together with the AMSU and HSB microwave radiometers, will achieve global retrieval accuracy of better then 1K rms in the lower troposphere under clear and partly cloudy conditions. This paper presents an overview of the science objectives, AIRS/AMSU/HSB data products, retrieval algorithms, and the ground data processing concepts. The EOS Aqua was launched on 4 May 2002 from Vandenburg AFB, California, into a 705km high sun synchronous orbit. Based on the excellent radiometric and spectral performance demonstrated by AIRS during pre-launch testing, which has by now been verified during on-orbit testing, we expect the assimilation of AIRS data into the forecast to result in major medium-range forecast improvements.

- by William Smith
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- Geophysics, Design Science, Geoscience, Geomatic Engineering

V l a d i m i r G. Irisov, A l e x e y V. K u z m t n , Mihail N. Pospelov, Jury G. T r o k h i m o v s k y and V a l e n t i n S . E t k i n . Space R e s e a r c h I n s t i t u t e A c a d e m y of Sciences USSR P r o f s o u z n a j a... more

V l a d i m i r G. Irisov, A l e x e y V. K u z m t n , Mihail N. Pospelov, Jury G. T r o k h i m o v s k y and V a l e n t i n S . E t k i n . Space R e s e a r c h I n s t i t u t e A c a d e m y of Sciences USSR P r o f s o u z n a j a s t . , 83/32, ABSTRACT

- by Vladimir Irisov
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- Power Spectrum, Microwave radiometer, Wind Speed, Brightness temperature
- by Paul Tregoning
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- Multidisciplinary, Geophysical, Microwave radiometer, Instruments and Techniques

The fabrication of a miniaturized ground-based water vapor profiling radiometer demonstrates the capability of monolithic microwave and millimeter-wave integrated circuit technology to reduce the mass and volume of microwave remote sensing instrumentation and to reduce substantially the necessary operational power consumption and size of the radiofrequency and intermediate-frequency sections. Since those sections comprise much of the mass and volume of current microwave receivers, the fabrication of this system represents an important contribution to the design of microwave radiometers. This miniaturized radiometer implementation is particularly well suited to benefit from the cost savings associated with mass production. The small size of the radiometer (24 × 18 × 16 cm) reduces the power required by the temperature control system and allows a rapid warm-up to the temperature set point as well as maintenance of a highly stable internal temperature. Exhibiting very similar statistical properties, the four channels of the radiometer have measured Allan times of greater than 40 s. Measurement results demonstrate that the instrument achieves a sensitivity of better than 0.2 K for 3 s of integration time. Preliminary comparisons of measured brightness temperatures with simulation results based on radiosonde data show good agreement, which are consistent with previously reported results.

- by Steven Reising
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- Geophysics, Remote Sensing, Millimeter Wave Antennas, Microwave Remote Sensing

Frequency dependence of brightness temperature (TB) in the range 6–21 GHz is studied as a function of surface roughness, vegetation cover and soil moisture using theoretical models. Frequency dependence of TB is plotted from Multi‐channel Scanning Microwave Radiometer (MSMR) TB data of Indian Remote Sensing Satellite (P‐series) IRS‐P4 for different target types such as ocean, desert, forest, agricultural and snow regions.

- by Hala AlJassar
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- Environmental Science, Remote Sensing, Surface Roughness, Soil moisture
- by mike hersman
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- Calibration, Oscillators, Fluctuations, Transfer Function

1] Within the renewed interest in the study of the Moon, in 2006 the European Space Agency approved a feasibility study for the European Student Moon Orbiter (ESMO) mission. In order to accomplish the ESMO mission objectives, a Microwave Radiometric Sounder (MiWaRS) was selected as a possible payload for flight on the ESMO satellite. This work summarizes the results of a numerical analysis of MiWaRS sounding capabilities. An (inhomogeneous) multilayer model of the microwave emission from the Moon's subsurface is presented, focusing the attention on the Moon's morphological, thermal, and dielectric properties. These properties have been determined and parameterized after a thorough investigation of available measurements and models. To this end, a radiative transfer numerical model, neglecting volume scattering, is coupled with a nonlinear thermal equation to simulate the microwave emission of the Moon's subsurface. Numerical simulations between L and Ka bands are performed to investigate the capability of MiWaRS to sound the characteristics of the Moon's regolith subsurface and detect the presence of rocks and ice under the near-surface regolith layer. Under these forward model assumptions, results show that the Moon's brightness temperature response allows the detection of discontinuities within regolith media down to 2 and 5 m depth when channels at 3 and 1 GHz are used, respectively. Lunar near-surface temperature may be also estimated within an accuracy less than a few kelvins. The discrimination of ice from rock by MiWaRS is hardly practicable and is limited to the presence of ice in the upper layers (with a depth less than 20 cm) beneath the lunar crust.

- by Alessandro Di Carlofelice and +1
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- Remote Sensing, Numerical Analysis, Multidisciplinary, Feasibility Study

The double difference method of inter-calibration between spaceborne microwave radiometers is combined with the vicarious cold calibration method for calibrating an individual radiometer. Vicarious cold calibration minimizes the effects of geophysical variability on radiative transfer models (RTMs) of the brightness temperature (TB) data and it accounts for frequency and incidence angle dissimilarity between radiometers. Double differencing reduces the sensitivity of the inter-calibration to RTM error and improper accounting for geophysical variables in the RTM. When combined together, the two methods significantly improve the confidence with which calibration differences can be identified and characterized. This paper analyzes the performance of the vicarious cold calibration double difference method for conical scanning microwave radiometers and quantifies the improvement this method provides compared to performing a simpler inter-calibration by direct comparison of radiometer measurements.

In the present study, the effectiveness of nowcasting convective activities using a microwave radiometer has
been examined for Kolkata (22.65° N, 88.45° E), a tropical location. It has been found that the standard deviation
of brightness temperature (BT) at 22 GHz and instability indices like Lifting Index (LI), K Index (KI) and Humidity
Index (HI) has shown definite changes before convective events. It is also seen that combination of standard deviation
of BT at 22 GHz and LI can be most effective in predicting convection. A nowcasting algorithm is prepared
using 18 isolated convective events of 2011 and in all cases, a marked variation of these parameters has been seen
an hour before the event. Accordingly, a prediction model is developed and tested on convective events of 2012
and 2013. It is seen that the model gives reasonable success in predicting convective rain about 7075 min in advance
with a prediction efficiency of 80%.

- by Animesh Maitra
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- Microwave radiometer, Nowcasting, Atmospheric instability, Brightness temperature
- by David Goodrich
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- Environmental Science, Geophysics, Algorithms, Microwave

The Agulhas Current system is a complex interplay of currents and eddies with the bathymetry. Components such as the East Madagascar Retro®ection and the Agulhas Return Current evolve signi cantly over a month, and they are thus not adequately resolved by infrequent research-ship cruises. This paper contrasts the abilities of three di¬erent spaceborne sensors for monitoring these complex regimes. A key parameter is sea-surface temperature, measured by both infrared and microwave radiometers. Ocean colour observations of chlorophyll can also be used to distinguish between water masses.

- by Meric Srokosz
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- Physics, Biology, Medicine, Multidisciplinary
- by M. Hallikainen
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- Remote Sensing, Space Technology, Global Positioning System, Frequency

The giant planets of the outer solar system divide into two distinct classes: the 'gas giants' Jupiter and Saturn, which consist mainly of hydrogen and helium; and the 'ice giants' Uranus and Neptune, which are believed to contain... more

- by Leora Peltz and +3
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- Nitrogen, Planetary Systems, Solar System, Microwave radiometer

This paper deals with the development of a microwave, noise-adding radiometer, purposely designed for the fire detection in forest environments. The sensor operates at 12.65 GHz and exploits commercial TV-SAT components such as a parabolic dish and a low noise block (LNB). First, a simple system model is presented in order to estimate the radiometric contrast due to presence of fire (increase of the antenna noise temperature with respect to the background) at a certain distance from the receiving antenna. Then, the design of the sensor is addressed, underlining the key technologies that allow the required performances to be attained at low industrial costs. An experimental characterization of the developed radiometer is reported focusing on both accuracy and sensitivity issues. Thanks to a continuous gain calibration based on the noiseadding procedure, the antenna noise temperature can be retrieved with an absolute error less than 2 K without any thermal stabilization of the instrument electronics. Finally, real fire detection experiments have been carried-out both in laboratory and openspace environments. A radiometric contrast of 8.8 K has been recorded for a wooden fire of 0.2 m 2 placed at a distance of about 30 m from the antenna.

- by L. Roselli and +2
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- Geophysics, Remote Sensing, Remote, Geomatic Engineering

- by Klaus Solbach and +1
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- Geophysics, Remote Sensing, Remote, Geomatic Engineering

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.

- by Christopher Ruf
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- Performance Analysis, Image Reconstruction, Microwave radiometer

RETRIEVAL OF SOIL MOISTURE WITH AIRBORNE AND SATELLITE MICROWAVE SENSORS E.Santi, S.Paloscia, P.Pampaloni, S.Pettinato, M.Brogioni CNR-IFAC, Firenze (Italy) S.Paloscia@ifac.cnr.it ... IGARSS 2009 Page 2. (PROSA) funded by the Italian... more

- by Simone Pettinato and +1
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- Remote Sensing, Earth Observation, Soil moisture, Geoscience

We present an analytical calibration approach for passive microwave polarimeters that is applicable where the instrument can be partitioned into distinct, functional radio-frequency blocks. The methodology is focused on polarimetric system characterization, not polarimetric measurements. It requires characterization of each major internal functional subsystem with a vector network analyzer to obtain a closed-form transfer function. The goals of this approach are to provide a transfer function describing the system in its entirety and to isolate the contribution of each subsystem to the uncertainty in the final modified Stokes parameters. Notably, the approach does not assume ideal polarization isolation in the radiometer system. A significant benefit of this approach is that the cascaded transfer functions serve as a realistic instrument simulator revealing where improvements in component performance would have greatest benefit for system performance over the dynamic range of the instrument. This systems-focused approach is applied to the National Aeronautics and Space Admnistration Goddard Space Flight Center polarimetric Airborne C-band Microwave Radiometer (ACMR), whose architecture allows the necessary subsystem partitioning. The characteristics of each subsystem were extensively measured, converted to a transfer function, and imported into the overall closed-form system model. Inversion of the system model and error analysis inherent to this calibration approach are illustrated by a full Stokes parameter retrieval for a senescent cornfield.

- by Hanh Pham
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- Geophysics, Remote Sensing, Geoscience and remote sensing, Error Analysis

Information on physical snow cover characteristics, such as snow water equivalent (SWE) and the areal coverage fraction of snow covered area (SCA), can be obtained from spaceborne remote sensing data. The feasible instruments include optical spectrometers and microwave radars (SCA mapping), and microwave radiometers (SWE mapping). As data assimilation techniques are applied, the EO data-derived information can improve the performance of river discharge forecasting models and the knowledge on snow climatology. The results discussed here indicate that the assimilation of EO databased SCA estimates to hydrological modeling significantly improves the accuracy of operational river discharge forecasts. The results also indicate that the employment of space-borne microwave radiometer data using the data assimilation technique improves the SWE or snow depth mapping accuracy when compared with the use of values interpolated from synoptic observations.

- by Saku Anttila and +1
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- Remote Sensing, Data Assimilation, SNOW, Microwave radiometer

Airborne microwave radiometer measurements of lake ice have been performed in 2004, 2007, and 2011 in southern Finland. The HUTRAD radiometer system provided data in the 6.9 to 36.5 GHz range using an incidence angle of 50 degrees off... more

- by J. Seppanen and +1
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- Microwave radiometer, Snow Cover, Integrated Circuit, Microwave measurement
- by Hanna Pawlowska
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- Remote Sensing, Atmospheric Aerosols, Large Eddy Simulation, Signal Analysis

Although data available from various earth observation systems have been routinely used in many resource applications, however there have been gaps, and data needs of applications at different levels of details have not been met. There is a growing demand for availability of data at higher repetivity, at higher spatial resolution, in more and narrower spectral bands etc. Some of the thrust areas of applications particularly in the Indian context are; Management of natural resources to ensure sustainable increase in agricultural production, Study the state of the environment, its monitoring and assessment of the impact of. various development actions on the environment, Updating and generation of large scale topographical maps. Exploration/exploitation of marine and mineral resources and Operational meteorology and studying various land and oceanic processes to understand/predict global climate changes. Each of these thrust area of application has many components, related to basic re...

- by Ranganath Navalgund
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- Geography, Forest fire, global Climate change, Mineral exploration

The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS), on-board the European ENVIronmental SATellite (ENVISAT) launched on 1 March 2002, is a middle infrared Fourier Transform spectrometer measuring the atmospheric emission spectrum in limb sounding geometry. The instrument is capable to retrieve the vertical distribution of temperature and trace gases, aiming at the study of climate and atmospheric chemistry and dynamics, and at applications to data assimilation and weather forecasting.

- by Ugo Cortesi
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- Remote Sensing, Atmospheric Chemistry, Data Assimilation, Atmospheric sciences

An intercomparison of ozone-profiling instruments, two differential absorption lidars, a microwave radiometer, electrochemical concentration sendes, and the SAGE II satellite instrument is presented. The ground-based instruments were located at the Network for the Detection of Stratospheric Change (NDSC) primary station at Lauder, New Zealand. The campaign, which took place between April 15 and 29, 1995, strictly followed the NDSC guidelines for a blind intercomparison. Agreement between the measurements was within 15% for single profiles and within 10% for the campaign average, in the region from 20 to 40 km altitude. Outside of this region the differences were greater but can generally be ascribed to the limits of a particular instrument. within the Network for the Detection of Stratosphcric Change (NDSC). To fulfil this role, a variety of instruments have been installed at Lauder in order to make regular measurements of a number of important atmospheric species in accordance with the NDSC goal to make observations through which changes in the physical and chemical state of the stratosphere and upper troposphere can bc determined and understood. In particular, the NDSC aims to make the carllest possible detection of changes in the ozone layer and to discern the cause of such changes. t Jet Propulsion Laboratory, California Institute of Technology, Table Mountain Facility, Wrightwood. Cut short by clouds Suspended several times for clouds •: Different altitude sections of this profile were recorded at different times during this period. Read 4/15/95 as April 15, 1995.

- by F. Ormel
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- Remote Sensing, Multidisciplinary, Global change, New Zealand

From 6 January to 28 February 1993, the second phase of the Pilot Radiation Observation Experiment (PROBE) was conducted in Kavieng, Papua New Guinea. Routine data taken during PROBE included radiosondes released every 6 h and 915-MHz Wind Profiler-Radio Acoustic Sounding System (RASS) observations of winds and temperatures. In addition, a dual-channel Microwave Water Substance Radiometer (MWSR) at 23.87 and 31.65 GHz and a Fourier Transform Infrared Radiometer (FTIR) were operated. The FTIR operated between 500 and 2000 cm −1 and measured some of the first high spectral resolution (1 cm −1 ) radiation data taken in the Tropics. The microwave radiometer provided continuous measurements within 30-s resolution of precipitable water vapor (PWV) and integrated cloud liquid, while the RASS measured virtual temperature profiles every 30 min. In addition, occasional lidar soundings of cloud-base heights were available. The MWSR and FTIR data taken during PROBE were compared with radiosonde data. Significant differences were noted between the MWSR and the radiosonde observations of PWV. The probability distribution of cloud liquid water was derived and is consistent with a lognormal distribution. During conditions that the MWSR did not indicate the presence of cloud liquid water, broadband long-and shortwave irradiance data were used to identify the presence of cirrus clouds or to confirm the presence of clear conditions. Comparisons are presented between measured and calculated radiance during clear conditions, using radiosonde data as input to a line-by-line Radiative Transfer Model. A case study is given of a drying event in which the PWV dropped from about 5.5 cm to a low of 3.8 cm during a 24-h period. The observations during the drying event are interpreted using PWV images obtained from data from the Defense Meteorological Satellite Program/Special Sensor Microwave/Imager and of horizontal flow measured by the wind profiler. The broadband irradiance data and the RASS soundings were also examined during the drying event.

- by Kenneth S Gage and +2
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- Papua New Guinea, Atmospheric sciences, Climate Model, Microwave radiometer