A. Tanner

California Institute of Technology, Pasadena, California, United States

Are you A. Tanner?

Claim your profile

Publications (78)50.03 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: A new geometry for synthetic aperture radiometers is presented which increases the distance between adjacent elements in the array without changing the visibility sample density in the u-v plane. This provides room for higher elemental antenna gain, which improves both the overall system sensitivity and alias rejection in the synthesized image-both critical requirements for the Earth observing application. The geometry is derived from the simple Y -array geometry by shifting alternate elements within an otherwise linear array arm into two or more rows of antennas. The resulting system largely retains the same hexagonal sample grid in the u-v plane of the visibility function, yet allows for an elemental antenna aperture that is physically larger than the u-v sample spacing. Only the shortest visibility baselines are lost, and a small dedicated low-gain array must be added to the system to recover these baselines. The radiometer is thus divided between a large high-gain array and a small low-gain array. Since the sensitivity (delta-T) of the system is dominated by that of the large array, this approach greatly improves the overall system sensitivity-in this letter, by a factor of 9 (or, equivalently, factor 81 integration time).
    IEEE Geoscience and Remote Sensing Letters 07/2014; 11(8). · 1.82 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Currently, wet-tropospheric path delay measurements over inland water and coastal areas are extremely sparse. They are generally limited to twice-per-day radiosonde launches and a small number of ground-based GPS or radiometer path delay measurements, as well as radar measurements of phase delay to a small number of fixed targets on the ground. Knowledge of the wet-tropospheric path delay is necessary for next-generation high-resolution altimeters, such as the Surface Water and Ocean Topography (SWOT) mission, in formulation and planned for launch in 2020. SWOT has two major science objectives. First, the oceanographic objective is to characterize ocean mesoscale and sub-mesoscale circulation with horizontal resolution of 10 km and order of 1 cm height precision. Second, the hydrological objective is to provide global height measurements of inland surface water bodies with area of greater than 250 square meters and flow rate of rivers with width greater than 100 m. Wet-tropospheric path delay retrieval over coastal and inland-water areas is needed to achieve both of these objectives with sufficient height accuracy. In addition, information on total precipitable water vapor under nearly all weather conditions is needed to improve initialization of numerical weather prediction models. Currently, 18-34 GHz microwave radiometers provide wet-path delay corrections for the Jason series of nadir-viewing altimeters. However, these retrievals are limited to open ocean, and land incursion is unacceptable within 40 km of coastlines. The addition of millimeter-wave radiometers (70-170 GHz) is needed to address this problem by providing smaller surface footprint dimensions proportional to wavelength. In this work, we present a prototype algorithm to demonstrate the potential to retrieve wet-tropospheric path delay from brightness temperatures measured by millimeter-wave radiometers using the Brightness Temperature Deflection Ratio (BTDR) method. The BTDR algorithm retrieves wet-path delay without the use of a-priori data by using background contrast in the ground scenes while avoiding the need for specific knowledge of their characteristics. The algorithm uses a deflection ratio, of brightness temperature differences measured by the radiometer viewing two adjacent scenes to resolve the transmissivity of the atmosphere due to water vapor. This transmissivity is mapped to wet-path delay using state-of-the-art atmospheric absorption models. Brightness temperatures measured by the Special Sensor Microwave Image/Sounder (SSMIS) are used to demonstrate the algorithm's capability. An error analysis technique to assess the self-consistency of the retrieval shows that the error of the retrieved wet path delays is less than 1.5 cm. Retrievals are demonstrated over coastlines and inland water bodies and compared to independently derived total precipitable water products from the GPROF 2010 algorithm using measurements from SSMIS and other space-borne microwave and millimeter-wave radiometers.
    04/2013;
  • [Show abstract] [Hide abstract]
    ABSTRACT: 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 technology has been recently developed for such sources at 90 to 170 GHz millimeter-wave frequencies. This instrument development and airborne flight demonstration will (1) assess wet-tropospheric path delay variability on 10-km and smaller spatial scales, (2) demonstrate millimeter-wave radiometry using both window and sounding channels to improve both coastal and over-land retrievals of wet-tropospheric path delay, and (3) provide an instrument for calibration and validation in support of the SWOT mission. We will describe on-going instrument development, as well as our plans for initial remote sensing test flights aboard a Twin Otter aircraft.
    04/2013;
  • [Show abstract] [Hide abstract]
    ABSTRACT: We currently achieve 3.4 dB noise figure at 183GHz and 2.1 dB noise figure at 90 GHz with our MMIC low noise amplifiers (LNAs) in room temperature. These amplifiers and the receivers we have built using them made it possible to conduct highly accurate airborne measurement campaigns from the Global Hawk unmanned aerial vehicle, develop millimeter wave internally calibrated radiometers for altimeter radar path delay correction, and build prototypes of large arrays of millimeter receivers for a geostationary interferometric sounder. We use the developed millimeter wave receivers to measure temperature and humidity profiles in the atmosphere and in hurricanes as well as to characterize the path delay error in ocean topography altimetry.
    Microwave Symposium Digest (MTT), 2012 IEEE MTT-S International; 01/2012
  • [Show abstract] [Hide abstract]
    ABSTRACT: The Geostationary Synthetic Thinned Aperture Radiometer (GeoSTAR) team recently concluded its second Earth Science Technology Office (ESTO) IIP-07, “GeoSTAR technology development and risk reduction for PATH”. The major accomplishments during this project at JPL were:1) Demonstrate performance and scalability of the 183 GHz receivers 2) Local oscillator phasing architecture and technology 3) Subarray design validation including feedhorns, manifolds and alignment 4) System demonstration of signal distribution topology and measurements. Significant progress has been made to retiring risk of the various subsystems.
    Geoscience and Remote Sensing Symposium (IGARSS), 2012 IEEE International; 01/2012
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We describe the development and progress of the GeoSTAR-II risk reduction activity for the NASA Earth Science Decadal Survey PATH Mission. The activity directly addresses areas of technical risk including the system design, low noise receiver production, sub-array development, signal distribution and digital signal processing.
    Geoscience and Remote Sensing Symposium (IGARSS), 2011 IEEE International; 08/2011
  • [Show abstract] [Hide abstract]
    ABSTRACT: Receivers with broad frequency bandwidth and low noise provide improved sensitivity for millimeter wave remote sensing and astrophysical observations, because the signal is wideband gaussian noise. For the study of the water cycle and rapidly evolving phenomena, such as hurricanes, the soundings of temperature and humidity profiles of atmosphere are achieved around the resonant frequencies of 118 GHz (oxygen) and 183 GHz (water) correspondingly. We developed a single horn receiver front end that achieved these goals. This broadband single horn receiver is especially beneficial for large interferometric sounding instruments that can now be integrated with only a single array of receivers for both temperature and humidity sounding.
    Microwave Symposium Digest (MTT), 2011 IEEE MTT-S International; 07/2011
  • [Show abstract] [Hide abstract]
    ABSTRACT: The Jet Propulsion Laboratory's High-Altitude Monolithic Microwave Integrated Circuit (MMIC) Sounding Radiometer (HAMSR) is a 25-channel cross-track scanning microwave sounder with channels near the 60- and 118-GHz oxygen lines and the 183-GHz water-vapor line. It has previously participated in three hurricane field campaigns, namely, CAMEX-4 (2001), Tropical Cloud Systems and Processes (2005), and NASA African Monsoon Multidisciplinary Analyses (2006). The HAMSR instrument was recently extensively upgraded for the deployment on the Global Hawk (GH) unmanned aerial vehicle platform. One of the major upgrades is the addition of a front-end low-noise amplifier, developed by JPL, to the 183-GHz channel which reduces the noise in this channel to less than 0.1 K at the sensor resolution (~2 km). This will enable HAMSR to observe much smaller scale water-vapor features. Another major upgrade is an enhanced data system that provides onboard science processing capability and real-time data access. HAMSR has been well characterized, including passband characterization, along-scan bias characterization, and calibrated noise-performance characterization. The absolute calibration is determined in-flight and has been estimated to be better than 1.5 K from previous campaigns. In 2010, HAMSR participated in the NASA Genesis and Rapid Intensification Processes campaign on the GH to study tropical cyclone genesis and rapid intensification. HAMSR-derived products include observations of the atmospheric state through retrievals of temperature, water-vapor, and cloud-liquid-water profiles. Other products include convective intensity, precipitation content, and 3-D storm structure.
    IEEE Transactions on Geoscience and Remote Sensing 01/2011; 49(9):3291-3301. · 3.47 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Although hyperspectral infrared sounders, such as AIRS and IASI, have become important weather and climate sensors for both operational and research use, microwave sounders, in spite of their coarser spatial resolution and poorer sounding accuracy, still play a crucial role. That is because infrared sounders do not sample certain weather and climate regimes well, particularly those associated with full cloud cover and storms. In part one this paper we review recent results obtained with the High Altitude MMIC Sounding Radiometer (HAMSR), an aircraft-based microwave sounder developed at the Jet Propulsion Laboratory and recently deployed on the NASA Global Hawk unmanned aircraft as part of the NASA Genesis and Rapid Intensification Processes (GRIP) hurricane field campaign. Here the emphasis is on the benefits of the high spatial resolution that is possible with suborbital sensors. In part two we will review plans to deploy a microwave sounder on a geostationary satellite in the relatively near future, where the emphasis is on the high temporal resolution that is possible from GEO. We focus on the Geostationary Synthetic Thinned Aperture Radiometer (GeoSTAR) now being developed at JPL for the Precipitation and All-weather Temperature and Humidity (PATH) mission - one of the 15 missions recommended by the National Research Council in its recent ``decadal survey'' of Earth satellite missions.
    AGU Fall Meeting Abstracts. 12/2010;
  • [Show abstract] [Hide abstract]
    ABSTRACT: Weather forecasting, hurricane tracking and atmospheric science applications depend on humidity sounding of atmosphere. Current instruments provide these measurements from ground based, airborne and LEO satellites by measuring radiometric temperature on the flanks of the 183 GHz water vapor line. We have developed miniature low noise receivers that will enable these measurements from a geostationary thinned array sounder. This geostationary instrument is based on hundreds of low noise receivers that convert the 180 GHz signal directly to baseband in-phase and quadrature signals for digitization and correlation. The developed receivers provided a noise temperature of 450 K from 165 to 183 GHz (NF = 4.1 dB) and had a mass of 3 g while consuming 24 mW of power. These are the most sensitive broadband I-Q receivers at this frequency range that operate at room temperature, and are significantly lower in mass and power consumption than previously reported receivers.
    Microwave Symposium Digest (MTT), 2010 IEEE MTT-S International; 06/2010
  • [Show abstract] [Hide abstract]
    ABSTRACT: The Precipitation and All-weather Temperature and Humidity (PATH) mission is one of the NASA missions recommended by the NRC in its recent Earth Science “Decadal Survey.” The focus of this mission is on the hydrologic cycle in the atmosphere, with applications from weather forecasting to climate research. PATH will deploy a microwave sounder, a passive radiometer that measures upwelling thermal radiation, in geostationary orbit and will for the first time provide a time-continuous view of atmospheric temperature and all three phases of water under nearly all weather conditions. This is possible because microwave radiation is sensitive to but also penetrates both clouds and precipitation, as has been demonstrated with similar sensors on low-earth-orbiting satellites. Data from those sensors, despite observing a particular location only twice a day, have had more impact on weather prediction accuracy than any other type of satellite sensor, and it is expected that PATH will have a similar impact with its ability to continuously observe the entire life cycle of storm systems. Such sensors have also played an important role in climate research and have been used to estimate long-term temperature trends in the atmosphere. An important application of PATH data will be to improve the representation of cloud formation, convection, and precipitation in weather and climate models, particularly the diurnal variation in those processes. In addition to measuring the three-dimensional distribution of temperature, water vapor, cloud liquid water, and ice, PATH also measures sea surface temperature under full cloud cover. Such observations make a number of important applications possible. Depending on the application focus and the geostationary orbit location, PATH can serve as anything from a hurricane and severe-storm observatory to an El Niño observatory. A geostationary orbit offers many advantages, as has been demonstrated with visible and infrared imag- - ers and sounders deployed on weather satellites, but those sensors cannot penetrate clouds. It has not been possible until now to build a microwave radiometer with a large enough antenna aperture to attain a reasonable spatial resolution from a GEO orbit. A new approach, using aperture synthesis, has recently been developed by NASA at the Jet Propulsion Laboratory, and that is what makes PATH possible. Key technology enabling the large array of receivers in such a system has been developed, and a proof-of-concept demonstrator was completed in 2006. The state of the art in this area is now such that PATH mission development could start in 2010 and be ready for launch in 2015, but the actual schedule depends on the availability of funding. An option to fly PATH as a joint NASA-NOAA mission is being explored.
    Proceedings of the IEEE 06/2010; · 6.91 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Imaging of temperature and humidity profiles of the atmosphere on a global scale with high temporal and spatial resolution requires a large aperture millimeter wave radiometer on geostationary orbit. We developed a prototype 50 GHz millimeter wave synthetic aperture radiometer and low noise amplifier (LNA) MMICs and receiver technology for a 180 GHz synthetic aperture system. The 50 GHz system was tested in laboratory and in field with a 4-meter target disk by refocusing the array to near-field by digital phase corrections. The 180 GHz system development included novel 180 GHz MMIC LNAs that provide more than 100 GHz of bandwidth with more than 15 dB of gain and a noise figure of 3.7 dB.
    Infrared, Millimeter and Terahertz Waves, 2008. IRMMW-THz 2008. 33rd International Conference on; 10/2008
  • [Show abstract] [Hide abstract]
    ABSTRACT: The Precipitation and All-weather Temperature and Humidity (PATH) mission is one of 15 Earth space missions that the U.S. National Research Council recently recommended that NASA undertake in the next decade. The PATH mission will place a microwave atmospheric sounder, operating in the same temperature and water vapor bands used by the low-earth-orbiting Advanced Microwave Sounding Units (AMSU), into geostationary orbit. The objective is to enable time-continuous observations of severe storms, tropical cyclones and atmospheric processes associated with the hydrologic cycle under all weather conditions. The ultimate goal is to improve models in these areas, provide initial conditions and assimilation data for improved forecasts, and develop long time series to support climate studies. Both NOAA and NASA have long sought to develop such a sensor, but it is only recently that new techniques have emerged that enable such a mission. The Geostationary Synthetic Thinned Aperture Radiometer (GeoSTAR) is a microwave sounder concept based on aperture synthesis that has been developed at the Jet Propulsion Laboratory. A small proof-of-concept prototype was completed in 2006 under the NASA Instrument Incubator Program, and this demonstrator proves that the aperture synthesis method is a feasible approach for attaining the very large aperture required for adequate spatial resolution. The performance of the prototype and projections to a full-scale space version indicate that GeoSTAR, unlike alternative approaches, can meet all measurement requirements. It is therefore now considered the baseline PATH payload and is expected to be implemented by NASA in the next decade.
    Geoscience and Remote Sensing Symposium, 2008. IGARSS 2008. IEEE International; 08/2008
  • Source
    B.H. Lim, C.S. Ruf, A.B. Tanner
    [Show abstract] [Hide abstract]
    ABSTRACT: A proposed instrument for deployment on next generation Geostationary Operational Environmental Satellite (GOES) platforms is the Geostationary Synthetic Thinned Aperture Radiometer (GeoSTAR) [1,2]. A high resolution full earth disk model has been developed to aid in the development of the instrument design and to characterize sensor performance. A variety of publicly available geophysical fields are used as data inputs into a full radiative transfer model that also accounts for the propagation and viewing geometries from GEO. The resulting model simulates full disk microwave images with the highest known resolution. The model can be used in concert with an instrument simulator to conduct design tradeoff studies. With the capability of generating high resolution brightness images at different frequencies, atmospheric profile retrievals can be evaluated.
    Geoscience and Remote Sensing Symposium, 2008. IGARSS 2008. IEEE International; 08/2008
  • [Show abstract] [Hide abstract]
    ABSTRACT: Ground based tests of the GeoSTAR (geostationary synthetic thinned array radiometer) demonstrator instrument are reported which simulate the view of the Earth from geosynchronous Earth orbit (GEO). The test used a 4-meter target disk mounted on a tower above the instrument to simulate the brightness of the earth with a contrasting cold background. Continuous observations at 50.3 GHz for over 100 hours, along with simultaneous atmospheric measurements from independent radiometers, yielded an excellent data set with which to test all aspects of the GeoSTAR calibration. This paper presents a preliminary look at these data, and presents an algorithm to remove the aliased background from the synthesized image.
    Aerospace Conference, 2008 IEEE; 04/2008
  • [Show abstract] [Hide abstract]
    ABSTRACT: The Geostationary Synthetic Thinned Aperture Radiometer (GeoSTAR) is a new Earth remote sensing instrument concept that has been under development at the Jet Propulsion Laboratory. First conceived in 1998 as a NASA New Millennium Program mission and subsequently developed in 2003-2006 as a proof-of-concept prototype under the NASA Instrument Incubator Program, it is intended to fill a serious gap in our Earth remote sensing capabilities - namely the lack of a microwave atmospheric sounder in geostationary orbit. The importance of such observations have been recognized by the National Academy of Sciences National Research Council, which recently released its report on a "Decadal Survey" of NASA Earth Science activities. One of the recommended missions for the next decade is a geostationary microwave sounder. GeoSTAR is well positioned to meet the requirements of such a mission, and because of the substantial investment NASA has already made in GeoSTAR technology development, this concept is fast approaching the necessary maturity for implementation in the next decade. NOAA is also keenly interested in GeoSTAR as a potential payload on its next series of geostationary weather satellites, the GOES-R series. GeoSTAR, with its ability to map out the three-dimensional structure of temperature, water vapor, clouds, precipitation and convective parameters on a continual basis, will significantly enhance our ability to observe hurricanes and other severe storms. In addition, with performance matching that of current and next generation of low-earth-orbiting microwave sounders, GeoSTAR will also provide observations important to the study of the hydrologic cycle, atmospheric processes and climate variability and trends. In particular, with GeoSTAR it will be possible to fully resolve the diurnal cycle. We discuss the GeoSTAR concept and basic design, the performance of the prototype, and a number of science applications that will be possible with GeoSTAR. The work reported on here was performed at the Jet Propulsion Laboratory, California Institute of Technology under a contract with the National Aeronautics and Space Administration.
    Proc SPIE 10/2007;
  • [Show abstract] [Hide abstract]
    ABSTRACT: The geostationary synthetic thinned aperture radiometer (GeoSTAR) is a new instrument design that has been under development at the Jet Propulsion Laboratory in the form of a proof-of-concept prototype. It is intended to fill a serious gap in our Earth remote sensing capabilities - namely the lack of a microwave atmospheric sounder in geostationary orbit. Such sensors have long been part of low-earth-orbiting (LEO) operational weather satellites and research satellites and have had a major impact ranging from numerical weather prediction to climate research. A similar capability in GEO is highly desired because of the advantageous observing point GEO offers, with continuous views of the entire visible Earth disc - crucial for the observation of hurricanes and other rapidly evolving atmospheric phenomena. GEO also enables full resolution of the diurnal cycle, which is particularly important in the study of atmospheric processes and climate variability where clouds and convection play a role, since those phenomena are known to have strong diurnal variability and are difficult to sample properly with sun synchronous LEO satellites. The GeoSTAR prototype produced the first interferometric radiometric images obtained at sounding frequencies in early 2005, and subsequent tests have demonstrated that the system exhibits excellent stability, accuracy and sensitivity and performs even better than predicted. This can be characterized as a breakthrough development. The technology required to implement GeoSTAR is at a level of maturity that a space mission can be contemplated. Such a mission is recommended by the U.S. National Research Council in its recent Decadal Survey of Earth missions and is being considered by both NASA and NOAA for the coming decade. Recent studies indicate that it is indeed feasible to implement a GeoSTAR mission in the 2014-16 time frame. We discuss possible mission scenarios as well as the science benefits that would ensue. The benefits are particular- ly significant in the area of tropical cyclones and severe storms, where there currently is a dearth of observations. With a geostationary microwave sounder it is possible to obtain the 3-dimensional distribution of temperature, water vapor and liquid water continuously and regardless of cloud cover, and atmospheric stability indices such as lifted index (LI) and convective available potential energy (CAPE) can be derived nearly everywhere. That will make it possible, for example, to detect severe-storm precursor conditions even if the area is under cloud cover. Recent progress in radiative transfer models now also makes it possible to obtain those parameters in the presence of moderate precipitation, and rain rates and snow rates can be derived as well. Aircraft based field campaign observations have also shown that a microwave sounder can be used to derive measures of convective intensity and precipitation in deep-convective systems from scattering due to ice particles formed by such systems. This can be used to estimate the intensity of tropical cyclones and can be used to detect sudden intensification and weakening in near-real time.
    Geoscience and Remote Sensing Symposium, 2007. IGARSS 2007. IEEE International; 08/2007
  • [Show abstract] [Hide abstract]
    ABSTRACT: The Jet Propulsion Laboratory's High Altitude MMIC Sounding Radiometer (HAMSR) is a 25 channel microwave sounder with channels near the 60 GHz and 118 GHz oxygen lines and near the 183 GHz water vapor line. It participated in three hurricane field campaigns, CAMEX-4, TCSP and NAMMA The absolute calibration of the HAMSR brightness temperatures is shown to be better than 1.5 K. A non-linear iterative optimal estimation based retrieval algorithm is developed to retrieve atmospheric temperature and absolute humidity profiles. Comparisons of the retrieved profiles with coincident dropsonde profiles during NAMMA show excellent agreement at all altitudes, with the exception of a 30% residual dry bias in the absolute humidity profile above 4 km. The warm core structure of Hurricane Erin in 2001 and Hurricane Emily in 2005 is retrieved. The 60/118 GHz channels which have matched clear air weighting functions are used to assess convective intensity in the eye wall through the relative scatter darkening between the two channels.
    Geoscience and Remote Sensing Symposium, 2007. IGARSS 2007. IEEE International; 08/2007
  • [Show abstract] [Hide abstract]
    ABSTRACT: GeoSTAR is a radiometer concept to provide high resolution microwave images of the Earth from geostationary Earth orbit (GEO) in bands from 50 to 183 GHz. The system consists of a Y-array of correlation interferometers, and uses aperture synthesis to achieve high resolution hemispheric coverage of the Earth. A ground-based 50 GHz demonstration instrument has been built and tested at the Jet Propulsion Laboratory which has now validated the calibration approach and error analysis. These analysis show that the antenna gain of the original design is marginal, since only about 42 percent of the received energy originates in the Earth disk as viewed from GEO. This degrades signal-to-noise (delta-T), and poses a problem for the 183 GHz bands where receiver noise and resolution requirements are greatest. This paper presents a new approach to the array geometry which solves this problem by arranging the majority of elemental antennas along two rows within each of the three array arms. The new geometry provides a factor of SQRT(3) times more distance between adjacent elements, and therefore enough physical space to raise the gain of the antenna elements by a factor of 3. The visibility sample grid and number of elements are unchanged. Only the shortest baselines retain the original design.
    Geoscience and Remote Sensing Symposium, 2007. IGARSS 2007. IEEE International; 08/2007
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The geostationary synthetic thinned array radiometer represents a promising new approach to microwave atmospheric sounding from geostationary orbit based on passive interferometry. Distortion due to mechanical or thermal constraints produces a displacement of the ideal antenna positions in the array that causes sampling errors. In this paper, the impact of array distortion on radiometric error is analyzed in detail so as to identify the dominant sources of error. A preliminary analysis showing that array distortion can be well corrected by means of an external phase reference is also presented.
    IEEE Transactions on Geoscience and Remote Sensing 08/2007; · 3.47 Impact Factor

Publication Stats

638 Citations
50.03 Total Impact Points

Institutions

  • 1993–2014
    • California Institute of Technology
      • Jet Propulsion Laboratory
      Pasadena, California, United States
  • 2008
    • University of Michigan
      • Department of Atmospheric, Oceanic and Space Sciences
      Ann Arbor, MI, United States
  • 2007
    • NASA
      Washington, West Virginia, United States
  • 1994
    • Pennsylvania State University
      University Park, Maryland, United States