Note: This page contains sample records for the topic observing system satellites from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: November 12, 2013.
1

Atarashii Joho Shisutemu: Eisei Kansoku (New Information System: Satellite Observation).  

National Technical Information Service (NTIS)

Today, several countries launched satellites for geophysical observation, which includes stationary satellites and polar satellites. By combination of these satellites, it is possible to observe the entire Earth. The low resolution and wide swath data can...

T. Sakata

1991-01-01

2

SLR system improvement for GIOVE-A satellite observation  

NASA Astrophysics Data System (ADS)

Galileo system consists of 27 satellites distributed in three uniformly separated planes. At the end of 2005, one satellite, Galileo In-Orbit Validation Element-A (GIOVE-A), was launched as planned into an MEO with an altitude of 23,260 kilometers. Carrying a payload of rubidium clocks, signal-generation units, and a phase-array antenna of individual L-band elements. GIOVE-A started broadcasting on January 28, 2006, securing the frequencies allocated by the ITU for Galileo. Performance of the on-board atomic clocks, antenna infrastructure, and signal properties is evaluated through precise orbit determination, supported by Satellite Laser Ranging (SLR), an independent high-precision range measurement technique for orbit determination based on a global network of stations that measure the round-trip flight-time of ultra short laser pulses to satellites equipped with laser retro reflector arrays (LRAs). SLR provides instantaneous range measurements of millimeter-level precision which can be compiled to provide accurate orbits and to measure the on-board clock error. Given the importance of SLR data for the characterization of the GIOVE-A clocks, the Changchun SLR station in northeast China was selected among the Chinese stations contributing to the ILRS because it had demonstrated strong MEO satellite tracking; collocation with an existing International GPS Service station; and good weather conditions. This paper introduces the SLR system improvement for tracking GIOVE-A satellite in Changchun station. During the more than two months improvement, the new servo and encoder systems were installed, primary mirror, second mirror and some other mirrors have been cleaned and recoated, and the laser system was adjusted in order to improve the laser efficiency and output energy. The paper gives out the improvement results, and the GIOVE-A satellite observation results.

Zhao, You; Fan, Cunbo; Han, Xingwei; Yang, Dingjiang; Chen, Nianjiang; Xue, Feng; Geng, Lin

2008-03-01

3

Tropospheric emission spectrometer for the Earth Observing System's Aura satellite  

Microsoft Academic Search

The Tropospheric Emission Spectrometer (TES) is an imaging infrared Fourier-transform spectrometer scheduled to be launched into polar Sun-synchronous orbit aboard the Earth Observing System 's Aura satellite in June 2003. The primary objective of the TES is to make global three-dimensional measurements of tropospheric ozone and of the physical -chemical factors that control its formation, destruction, and distribution. Such an

Reinhard Beer; Thomas A. Glavich; David M. Rider

2001-01-01

4

The application of error quaternion and PID control method in Earth observation satellite's attitude control system  

Microsoft Academic Search

Because of its payload's work characteristic, it requires much higher precision in Earth observation satellite's attitude control systems than others. Most Earth observation satellites use zero-momentum three-axis stabilization control method. This paper investigates this control method in satellite control system, deducing the dynamics and kinematics of satellite attitude's model expressed by attitude error quaternion, applying PID control method in this

Qiyu Wang; Jianping Yuan; Zhanxia Zhu

2006-01-01

5

Tropospheric emission spectrometer for the Earth Observing System's Aura satellite.  

PubMed

The Tropospheric Emission Spectrometer (TES) is an imaging infrared Fourier-transform spectrometer scheduled to be launched into polar Sun-synchronous orbit aboard the Earth Observing System's Aura satellite in June 2003. The primary objective of the TES is to make global three-dimensional measurements of tropospheric ozone and of the physical-chemical factors that control its formation, destruction, and distribution. Such an ambitious goal requires a highly sophisticated cryogenic instrument operating over a wide frequency range, which, in turn, demands state-of-the-art infrared detector arrays. In addition, the measurements require an instrument that can operate in both nadir and limb-sounding modes with a precision pointing system. The way in which these mission objectives flow down to the specific science and measurement requirements and in turn are implemented in the flight hardware are described. A brief overview of the data analysis approach is provided. PMID:18357244

Beer, R; Glavich, T A; Rider, D M

2001-05-20

6

Observation of solar-system objects with the ISO satellite  

Microsoft Academic Search

The ISO (Infrared Space Observatory) mission was an ESA earth-orbiting satellite devoted to the infrared observation of astronomical sources. The 60-cm helium-cooled telescope was launched in November 1995 and ended its life in May 1998. The satellite was equipped with 4 focal-plane instruments: a camera (CAM, 2.5-17 microns), a photometer (PHT, 2-200 microns) and two spectrometers, SWS (2.3-45 microns) and

Therese Encrenaz

1998-01-01

7

A view finder control system for an earth observation satellite  

NASA Astrophysics Data System (ADS)

A real time TV view finder is used on-board a low earth orbiting (LEO) satellite to manually select targets for imaging from a ground station within the communication footprint of the satellite. The attitude control system on the satellite is used to steer the satellite using commands from the groundstation and a television camera onboard the satellite will then downlink a television signal in real time to a monitor screen in the ground station. The operator in the feedback loop will be able to manually steer the boresight of the satellite's main imager towards interested target areas e.g. to avoid clouds or correct for any attitude pointing errors. Due to a substantial delay (in the order of a second) in the view finding feedback loop and the narrow field of view of the main imager, the operator has to be assisted by the onboard attitude control system to stabilise and track the target area visible on the monitor screen. This paper will present the extended Kalman filter used to estimate the satellite's attitude angles using quaternions and the bias vector component of the 3-axis inertial rate sensors (gyros). Absolute attitude sensors (i.e. sun, horizon and magnetic) are used to supply the measurement vectors to correct the filter states during the view finder manoeuvres. The target tracking and rate steering reaction wheel controllers to accurately point and stabilise the satellite will be presented. The reference generator for the satellite to target attitude and rate vectors as used by the reaction wheel controllers will be derived.

Steyn, H.

2004-11-01

8

Candidate Configuration Trade Study, Stellar-Inertial Measurement Systems (Sims) for an Earth Observation Satellite (Eos).  

National Technical Information Service (NTIS)

The results of analytical and simulation studies of the stellar-inertial measurement system (SIMS) for an earth observation satellite are presented. Subsystem design analyses and sensor design trades are reported. Three candidate systems are considered: (...

G. Ogletree J. Coccoli M. Smith R. Mckern R. White

1972-01-01

9

Observation or telecommunication satellites  

US Patent & Trademark Office Database

The low earth orbit radar remote sensing or telecommunication satellite includes an antenna forming member in a plane passing through the center of Earth, for example, the plane of its orbit. The antenna(s) are on one or both faces of the member. The height of the antenna forming member is greater than its dimension in the direction of travel of the satellite, so that the satellite is naturally stabilized by the gravity gradient. The solar generator cells are carried by the antenna forming member on the face that is kept facing towards the Sun in the case of a 6 H/18 H local time heliosynchronous orbit. The antenna forming member comprising a plurality of hinged panels over which the received or transmitted wave phase control means are distributed, it includes a plurality of GPS sensors distributed over the panels, enabling measurement and subsequent compensation by the phase-shifters of deformations of the member. At launch, the panels are folded into an elongate cylindrical shell along the launch system axis and having a pyrotechnic trap allowing deployment of the panels. In orbit, this shell constitutes the equipment module integrating all the equipment units other than the panels.

Aguttes; Jean-Paul (Toulouse, FR); Conde; Eric (Aigrefeuille, FR); Sombrin; Jacques (Toulouse, FR)

2001-04-10

10

The Effect of Satellite Observing System Changes on MERRA Water and Energy Fluxes  

NASA Astrophysics Data System (ADS)

Because reanalysis data sets offer state variables and fluxes at regular space / time intervals, these products have become a mainstay of the climate community for diagnostic purposes and for driving offline ocean and land models. Although one weakness of these data sets is the susceptibility of the flux products to uncertainties because of shortcomings in parameterized model physics, another issue, perhaps less appreciated, is the fact that continual but discreet changes in the evolving observational system, particularly from satellite sensors, may also introduce artifacts in the time series of quantities. In this paper we examine the ability of the NASA MERRA (Modern Era Retrospective Analysis for Research and Applications) to determine variability in the climate system over the satellite record (~ the last 30 years). In particular we highlight the effect on the reanalysis of discontinuities at the onset of passive microwave imaging (Special Sensor Microwave Imager, SSMI) in late 1987 as well as improved sounding and imaging with the Advanced Microwave Sounding Unit, AMSU-A, in 1998. We first examine MERRA fluxes from the perspective of how physical modes of variability (e.g. ENSO events, Pacific Decadal Variability) are contamined by artificial step-like trends induced by the onset of new moisture data these two satellite observing systems. Secondly, we show how Redundancy Analysis, a statistical regression methodology, is effective in relating these artifact signals in the moisture and temperature analysis increments to their presence in the physical flux terms (e.g. precipitation, radiation). This procedure is shown to be effective greatly reducing the artificial trends in the flux quantities.

Robertson, F. R.; Bosilovich, M. G.; Chen, J.; Miller, T. L.

2010-12-01

11

Cold War Space Policy and Observation Satellites  

Microsoft Academic Search

Constellations of observation satellites resemble the ''Panopticon'' system ima- gined by British philosopher Jeremy Bentham in his 18th century project for an ideal jailhouse—a system that Michel Foucault analyzed in Discipline and Punish (1975). Just as the warden in the central tower watches the prison- ers without their being able to see him, satellites watch the Earth while observed countries

Laurence Nardon

2007-01-01

12

A satellite observation system simulation experiment for carbon monoxide in the lowermost troposphere  

NASA Astrophysics Data System (ADS)

We demonstrate the feasibility of using observing system simulation experiment (OSSE) studies to help define quantitative trace gas measurement requirements for satellite missions and to evaluate the expected performance of proposed observing strategies. The 2007 U.S. National Research Council Decadal Survey calls for a geostationary (GEO) satellite mission for atmospheric composition and air quality applications (Geostationary Coastal and Air Pollution Events Mission (GEO-CAPE)). The requirement includes a multispectral (near-infrared and thermal infrared) measurement of carbon monoxide (CO) at high spatiotemporal resolution with information on lowermost troposphere concentration. We present an OSSE to assess the improvement in surface CO characterization that would result from the addition of a GEO-CAPE CO measurement to current low Earth orbit (LEO) thermal infrared-only measurements. We construct instrument simulators for these two measurement scenarios and study the case of July 2004 when wildfires in Alaska and Canada led to significant CO pollution over the contiguous United States. Compared to a control experiment, an ensemble-based data assimilation of simulated satellite observations in a global model leads to improvements in both the surface CO distributions and the time evolution of CO profiles at locations affected by wildfire plumes and by urban emissions. In all cases, an experiment with the GEO-CAPE CO measurement scenario (overall model skill of 0.84) performed considerably better than the experiment with the current LEO/thermal infrared measurement (skill of 0.58) and the control (skill of 0.07). This demonstrates the advantages of increased sampling from GEO and enhanced measurement sensitivity to the lowermost troposphere with a multispectral retrieval.

Edwards, David P.; Arellano, Avelino F.; Deeter, Merritt N.

2009-07-01

13

A satellite ocean color observation operator system for eutrophication assessment in coastal waters  

NASA Astrophysics Data System (ADS)

During the INSEA project the potential positive role that remote sensing products can play in coastal eutrophication assessment systems using assimilation into coupled hydrodynamic-biogeochemical models has been shown. However, products derived from satellite ocean color data continue to suffer from high levels of inaccuracy when compared with in situ measurements of the surface layer of the ocean. This has been particularly pronounced for coastal waters and waters optically classified as Case-II. The early success of using empirical relationships between chlorophyll and simple band ratios to derive estimates of surface layer chlorophyll from the first ocean color satellite sensors' data (i.e. CZCS), has led mainstream ocean color remote sensing and standard ocean color products towards following this approach for subsequent sensors (e.g. SeaWiFS and MODIS). Chlorophyll has continued to be the main focus product but is only related to one of the optical properties of sea water, namely the absorption of light by phytoplankton, whereas empirical band ratio approaches use wavelength banded water leaving radiance resultant from all absorption and scattering of light by all the optically active components of the ocean surface layer. We suggest that using approaches that do not fully exploit remote sensing optical data through a parameterization of the optical properties of sea water, is the main reason for the poor performance of many ocean color products when compared with in situ data. This is in concordance with the International Ocean Color Coordinating Group (IOCCG) and following their recent guidelines, novel inherent optical properties approaches (e.g. for MERIS) and the lines of research that are being used in atmospheric remote sensing, we present a demonstration 'observation operator' system that is based on biogeochemical model output, optical properties (apparent and inherent), and radiative transfer modeling. In the forward mode we demonstrate the system by producing MODIS and SeaWiFS synthetic images of water leaving radiance for the coastal test sites of INSEA. We show that the observation operator approach has the potential to allow the consistent mapping of model variables into observed quantities which simplifies the transport of measurement errors and reduces the need for approximations inherent in previous approaches. In conclusion we discuss the future development and potential of inversion of the system in order to obtain more accurate ocean color biogeochemical products (including chlorophyll) from satellite radiance data for eutrophication assessment. We also highlight the additional advantages there may be for ecological models from having stronger links to bio-optics.

Banks, Andrew Clive; Prunet, Pascal; Chimot, Julien; Pina, Pedro; Donnadille, Jerome; Jeansou, Eric; Lux, Muriel; Petihakis, Giorgos; Korres, Gerasimos; Triantafyllou, Giorgos; Fontana, Clement; Estournel, Claude; Ulses, Caroline; Fernandez, Luis

2012-06-01

14

Modulation of tropical convective systems by environmental conditions as observed from multiple satellite measurements  

NASA Astrophysics Data System (ADS)

During the Indoex experiment, a specific effort was done in LMD, France, for collecting the satellite data relevant to the region and period, and put them in a well conditioned data base. Meteosat-5 was moved by EUMETSAT over the Indian Ocean, and is the leading satellite for the studies presented here. METEOSAT allows the study and tracking of the convective systems and events, as well as estimation of the upper tropospheric humidity. Other satellite information on the water vapour in the atmosphere or precipitation come from microwave instruments as SSM/I or the instruments of TRMM. Concerning the radiative budget components, ScaRaB on the Russian satellite RESURS was providing outgoing radiative fluxes. All this information is combined here in order to study the fluctuations of convection at different time space scales and its relationship to environmental conditions such as humidity, sea surface temperature,…

Desbois, Michel; Roca, Remy; Viollier, Michel; Rao, Kusuma G.; Monge, Jean-Louis

2003-04-01

15

Preliminary design of a satellite observation system for Space Station Freedom  

NASA Astrophysics Data System (ADS)

Degobah Satellite Systems (DSS), in cooperation with the University Space Research Association (USRA), NASA - Johnson Space Center (JSC), and the University of Texas, has completed the preliminary design of a satellite system to provide inexpensive on-demand video images of all or any portion of Space Station Freedom (SSF). DSS has narrowed the scope of the project to complement the work done by Mr. Dennis Wells at Johnson Space Center. This three month project has resulted in completion of the preliminary design of AERCAM, the Autonomous Extravehicular Robotic Camera, detailed in this design report. This report begins by providing information on the project background, describing the mission objectives, constraints, and assumptions. Preliminary designs for the primary concept and satellite subsystems are then discussed in detail. Included in the technical portion of the report are detailed descriptions of an advanced imaging system and docking and safing systems that ensure compatibility with the SSF. The report concludes by describing management procedures and project costs.

Cabe, Greg; Gallagher, Chris; Wilson, Brian; Rehfeld, James; Maurer, Alexa; Stern, Dan; Nualart, Jaime; Le, Xuan-Trang

1992-12-01

16

Estimating Zenith Tropospheric Delays from BeiDou Navigation Satellite System Observations  

PubMed Central

The GNSS derived Zenith Tropospheric Delay (ZTD) plays today a very critical role in meteorological study and weather forecasts, as ZTDs of thousands of GNSS stations are operationally assimilated into numerical weather prediction models. Recently, the Chinese BeiDou Navigation Satellite System (BDS) was officially announced to provide operational services around China and its neighborhood and it was demonstrated to be very promising for precise navigation and positioning. In this contribution, we concentrate on estimating ZTD using BDS observations to assess its capacity for troposphere remote sensing. A local network which is about 250 km from Beijing and comprised of six stations equipped with GPS- and BDS-capable receivers is utilized. Data from 5 to 8 November 2012 collected on the network is processed in network mode using precise orbits and in Precise Point Positioning mode using precise orbits and clocks. The precise orbits and clocks are generated from a tracking network with most of the stations in China and several stations around the world. The derived ZTDs are compared with that estimated from GPS data using the final products of the International GNSS Service (IGS). The comparison shows that the bias and the standard deviation of the ZTD differences are about 2 mm and 5 mm, respectively, which are very close to the differences of GPS ZTD estimated using different software packages.

Xu, Aigong; Xu, Zongqiu; Ge, Maorong; Xu, Xinchao; Zhu, Huizhong; Sui, Xin

2013-01-01

17

New tabu search heuristic in scheduling earth observation satellites  

Microsoft Academic Search

Scheduling system of low earth orbit (LEO) satellite operations is one of the important tasks performed in satellites. Satellite specific constraints, satellite priorities, priorities of certain payload and special operations, as well as visibility conflicts are taken into consideration while generating the operations schedules in an optimum way. This paper proposes a tabu search heuristic for earth observation satellite scheduling

A. Sarkheyli; B. G. Vaghei; A. Bagheri

2010-01-01

18

A statistical comparison of deep convective cloud objects observed by an Earth Observing System satellite and simulated by a cloud-resolving model  

Microsoft Academic Search

The single scanner footprint (SSF) data product produced by the Clouds and the Earth's Radiant Energy System (CERES) instrument on board the Tropical Rainfall Measuring Mission (TRMM) satellite is used to diagnose 68 deep convective cloud objects observed in March 1998. The probability density functions (PDFs) of several observed and retrieved fields from the CERES SSF data product are used

Zachary A. Eitzen; Kuan-Man Xu

2005-01-01

19

Ocean observer study: A proposed national asset to augment the future U.S. operational satellite system  

USGS Publications Warehouse

The next generation of U.S. polar orbiting environmental satellites, are now under development. These satellites, jointly developed by the Department of Defense (DoD), the Department of Commerce (DOC), and the National Aeronautics and Space Administration (NASA), will be known as the National Polar-orbiting Operational Environmental Satellite System (NPOESS). It is expected that the first of these satellites will be launched in 2010. NPOESS has been designed to meet the operational needs of the U.S. civilian meteorological, environmental, climatic, and space environmental remote sensing programs, and the Global Military Space and Geophysical Environmental remote sewing programs. This system, however, did not meet all the needs of the user community interested in operational oceanography (particularly in coastal regions). Beginning in the fall of 2000, the Integrated Program Office (IPO), a joint DoD, DOC, and NASA office responsible for the NPOESS development, initiated the Ocean Observer Study (OOS). The purpose of this study was to assess and recommend how best to measure the missing or inadequately sampled ocean parameters. This paper summarizes the ocean measurement requirements documented in the OOS, describes the national need to measure these parameters, and describes the satellite instrumentation required to make those measurements.

Cunningham, J. D.; Chambers, D.; Davis, C. O.; Gerber, A.; Helz, R.; McGuire, J. P.; Pichel, W.

2003-01-01

20

A Global Observing System for Mars: The dual satellite Mars Astrobiology and Climate Observatory (MACO)  

Microsoft Academic Search

We summarize a planetary decadal survey white paper describing the rationale for and key elements of a dual satellite orbiting mission (DSM) concept called the Mars Astrobiology and Climate Observatory (MACO). MACO uses mm-wavelength satellite to satellite (sat-sat) occultations in combination with solar occultations (SO) to answer and strongly constrain many key lower and middle atmosphere Mars science questions previously

E. R. Kursinski; J. Lyons; C. Newman; M. I. Richardson; D. Ward; A. C. Otarola

2009-01-01

21

A comparison of mapped and measured total ionospheric electron content using global positioning system and beacon satellite observations  

Microsoft Academic Search

Total ionospheric electron contents (TEC) were measured by global positioning system (GPS) dual-frequency receivers developed by the Jet Propulsion Laboratory. The measurements included P-code (precise ranging code) and carrier phase data for six GPS satellites during multiple five-hour observing sessions. A set of these GPS TEC measurements were mapped from the GPS lines of sight to the line of sight

Gabor E. Lanyi; Titus Roth

1988-01-01

22

The benefits of combined processing of observations from different Global Navigation Satellite Systems  

Microsoft Academic Search

The Galileo GNSS and the modernisation of the existing GPS and GLONASS systems will offer many exciting opportunities and challenges in the field of geosciences in the next decade. However, in order to obtain any positive effects on our geodetic and geophysical estimates the different GNSS systems will have to be observed by multi-system receivers that track all systems on

T. Springer; F. Dilssner; J. Tegedor; D. Escobar; J. Dow; R. Zandbergen

2009-01-01

23

Ka-band High-speed Communication Systems on Small Satellites for Future Advanced Communication Networks and Earth Observations  

NASA Astrophysics Data System (ADS)

The goal of this paper is to describe the capabilities and application methods of Ka-band communication systems for small satellites indicating contributions to future advanced communication networks and Earth observations. This study is based on the actual experience on the design of the Ka-band high-speed communication system of the small satellite Flying Laptop, which is developed at the Institute of Space Systems of the Universität Stuttgart. The objectives of the Ka-band communication system is to demonstrate high-speed communications with a data rate of up to 500 Mbit/s as well as to conduct scientific Earth observations. Flying Laptop satellite is also equipped with a Ku-band signal transmitter. The attenuation of the two transmission signals in Ka-/Ku-bands are measured with ground stations to estimate the local precipitation rate. The mathematical background and operational scenario of this measurement is summarized. The received Ka-band transmission signal is measured in different meteorological conditions to identify attenuation characteristics of the Ka-band signal due to rain, clouds, trace gases and so forth, which is of great interest for utilization of Ka-band frequencies for future broadband communications.

Kuwahara, Toshinori; Lengowski, Michael; Beyermann, Ulrich; Uryu, Alexander; Roeser, Hans-Peter

24

Comparison of mapped and measured total ionospheric electron content using global positioning system and beacon satellite observations  

SciTech Connect

Total ionospheric electron contents (TEC) were measured by global positioning system (GPS) dual-frequency receivers developed by the Jet Propulsion Laboratory. The measurements included P-code (precise ranging code) and carrier phase data for six GPS satellites during multiple five-hour observing sessions. A set of these GPS TEC measurements were mapped from the GPS lines of sight to the line of sight of a Faraday beacon satellite by statistically fitting the TEC data to a simple model of the ionosphere. The mapped GPS TEC values were compared with the Faraday rotation measurements. Because GPS transmitter offsets are different for each satellite and because some GPS receiver offsets were uncalibrated, the sums of the satellite and receiver offsets were estimated simultaneously with the TEC in a least squares procedure. The accuracy of this estimation procedure is evaluated indicating that the error of the GPS-determined line of sight TEC can be at or below 1 x 10 to the 16th el/sq cm. Consequently, the current level of accuracy is comparable to the Faraday rotation technique; however, GPS provides superior sky coverage. 15 references.

Lanyi, G.E.; Roth, T.

1988-08-01

25

SST subseasonal variability in the Benguela upwelling system from satellite observations  

NASA Astrophysics Data System (ADS)

Subseasonal variability of sea surface temperature (SST) in the Benguela upwelling system is investigated using TMI satellite derived data over the period 2000-2008. Spatio-temporal characteristics of subseasonal variability are documented based on Empirical Orthogonal Functions (EOF) decomposition and wavelet analysis. Two regimes of variability are evidenced: submonthly with a dominant 11-days oscillation and a lower frequency intraseasonal with a dominant 61-days oscillation. Both regimes are consistent with Ekman dynamics and are modulated, to a large extent, by the local surface wind stress. The seasonality of the relationship between wind stress and SST for submonthly (intraseasonal) regime is characterized by a marked semi-annual (seasonal) cycle, which is explained in terms of the impact of seasonal change of the ocean stratification on the vertical advection process. The wind-driven SST subseasonal variability is shown to be associated with eastward-propagating disturbance in the mid-latitudes. The results also suggest a role of the Antarctic Oscillation in modulating the intraseasonal upwelling variability. The characteristics of the equatorial intraseasonal Kelvin waves are documented in order to discuss possible impact of remote oceanic forcing on SST variability along the coast in the Benguela upwelling system.

Goubanova, Katerina; Illig, Séréna; Machu, Eric; Garēon, Véronique

2013-04-01

26

Observations of geostationary satellites at Helwan Observatory.  

NASA Astrophysics Data System (ADS)

Conditions and possibility of photographic observations of geostationary satellites by camera AFU-75 at Helwan Observatory are shown. 39 positions for 13 satellites are given, according to the results of observations on October 15, 1985.

Bakhtigaraev, N. S.; Baghos, B. B.; Towadrous, M. J.; Hilaly, Y. E.

27

Voyager 2 radio science observations of the uranian system: atmosphere, rings, and satellites.  

PubMed

Voyager 2 radio occultation measurements of the Uranian atmosphere were obtained between 2 and 7 degrees south latitude. Initial atmospheric temperature profiles extend from pressures of 10 to 900 millibars over a height range of about 100 kilometers. Comparison of radio and infrared results yields mole fractions near the tropopause of 0.85 and 0.15 +/- 0.05 for molecular hydrogen and helium, respectively, if no other components are present; for this composition the tropopause is at about 52 kelvins and 110 millibars. Distinctive features in the signal intensity measurements for pressures above 900 millibars strongly favor model atmospheres that include a cloud deck of methane ice. Modeling of the intensity measurements for the cloud region and below indicates that the cloud base is near 1,300 millibars and 81 kelvins and yields an initial methane mole fraction of about 0.02 for the deep atmosphere. Scintillations in signal intensity indicate small-scale stucture throughout the stratosphere and upper troposphere. As judged from data obtained during occultation ingress, the ionosphere consists of a multilayer structure that includes two distinct layers at 2,000 and 3,500 kilometers above the 100-millibar level and an extended topside that may reach altitudes of 10,000 kilometers or more. Occultation measurements of the nine previously known rings at wavelengths of 3.6 and 13 centimeters show characteristic values of optical depth between about 0.8 and 8; the maxim value occurs in the outer region of the in ring, near its periapsis. Forward-scattered signals from this ring have properties that differ from those of any of Saturn's rings, and they are inconsistent with a discrete scattering object or local (three-dimensional) assemblies of orbiting objects. These signals suggest a new kdnd of planetary ring feature characterized by highly ordered cylindrical substructures of radial scale on the order of meters and azimuthal scale of kilometers or more. From radio data alone the mass of the Uranian system is GM(sys) = 5,794,547- 60 cubic kilometers per square second; from a combination of radio and optical navigation data the mass of Uranus alone is GM(u) = 5,793,939+/- 60 cubic kilometers per square second. From all available Voyager data, induding imaging radii, the mean uncompressed density of the five major satellites is 1.40+/- 0.07 grams per cubic centimeter; this value is consistent with a solar mix of material and apparently rules out a cometary origin of the satellites. PMID:17812893

Tyler, G L; Sweetnam, D N; Anderson, J D; Campbell, J K; Eshleman, V R; Hinson, D P; Levy, G S; Lindal, G F; Marouf, E A; Simpson, R A

1986-07-01

28

Overview of the Ocean Observer Satellite Study  

NASA Astrophysics Data System (ADS)

A two-year study of ocean satellite remote sensing requirements and instrument/satellite options is nearing completion. This Ocean Observer Study was sponsored by the U.S. Dept. of Commerce/Dept. of Defense/National Aeronautics and Space Administration Integrated Program Office, whose mission is to develop the future U.S. National Polar-Orbiting Operational Environmental Satellite System (NPOESS). A comprehensive Ocean Observer User Requirements Document has been drafted by a team of over 150 government, academic, and private sector scientists, engineers, and administrators. Included are requirements for open and coastal ocean surface, cryospheric, hydrologic, and some land/hazard and atmospheric boundary layer parameters. This document was then used as input to the instrument and satellite study (conducted by the Jet Propulsion Laboratory) which produced five different instrument/satellite configuration options designed to address the maximum number of requirements which will not be met with the already-approved NPOESS instruments. Instruments studied include a synthetic aperture radar (SAR), an altimeter, and a hyper-spectral coastal infrared/visible imager. After analyzing the alternatives, it appears that one of the best options is a two-satellite system consisting of (1) an altimeter mission in the Topex/Poseidon orbit carrying both wide-swath and delayed doppler altimeters, and (2) a multi-polarization, multi-frequency, multi-mode interferometric SAR mission including a coastal imager in a polar sun-synchronous orbit. This paper summarizes the user requirements process, briefly describes the notional satellite configuration, and presents some of the capabilities of the instruments.

Cunningham, J. D.; McGuire, J. P.; Pichel, W. G.; Gerber, A. J.

2002-12-01

29

Civil satellite navigation systems  

NASA Astrophysics Data System (ADS)

The use of satellite navigation for civil purposes is examined critically to compare the merits and costs of existing and practical satellite systems. Accuracy and range considerations are reviewed, and the basic requirements of radionavigation systems are set forth. Specific data are given regarding coverage area, integration with ground-based systems, monitoring and control, and accuracy. Systems reviewed include 'Starfix,' Inmarsat, EVA Vavsat, and Geostar/Locstar/Omnitracs, and extensive illustrations are provided to demonstrate constellation geometries. When in view, two or three geosynchronous satellites can provide acceptable fixing, and 9 satellites can provide global coverage. It is argued that systems such as 'Starfix' are commercially viable with less than 100 users, and Inmarsat is identified as an effective European civil system.

Blanchard, Walter F.

1991-07-01

30

Joint polar satellite system  

NASA Astrophysics Data System (ADS)

The Joint Polar Satellite System (JPSS) is a joint NOAA/NASA mission comprised of a series of polar orbiting weather and climate monitoring satellites which will fly in a sun-synchronous orbit, with a 1330 equatorial crossing time. JPSS resulted from the decision to reconstitute the National Polar-orbiting Operational Environmental Satellite System (NPOESS) into two separate programs, one to be run by the Department of Defense (DOD) and the other by NOAA. This decision was reached in early 2010, after numerous development issues caused a series of unacceptable delays in launching the NPOESS system.

Trenkle, Timothy; Driggers, Phillip

2011-10-01

31

Validation of the version 5 Goddard Earth Observing System (GEOS-5) using Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO)  

NASA Astrophysics Data System (ADS)

This dissertation compares the Planetary Boundary Layer (PBL) height produced by the Goddard Earth Observing System-version 5 (GEOS-5) model with Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO). Part of GEOS-5 is an Atmosphere Global Circulation Model (GCM). Developers are uncertain of the precision of model PBL height predictions (i.e. climatology), since there are limited direct observations of the PBL height. Validation of the PBL height serves as a diagnostic on whether the physics and dynamics packages are correct in the model. Thus, verification is needed. For the first time ever, PBL heights have been derived from CALIPSO using a new hybrid standard deviation algorithm, which in some cases is more sensitive than traditional approaches (i.e. Haar wavelet method). Observations made at the UMBC Elastic Lidar Facility (ELF) have been used to determine the validity of the satellite-derived PBL estimate. This is the first global observational study of PBL heights using CALIPSO with match-ups to the GEOS-5 MERRA model. Extensive comparisons between the model output and satellite observations in the western Hemisphere and over Africa gave model-measurement correlation coefficients between 0.47--0.73. Comparisons have been performed for regions over land and water using clouds, aerosols and mixed cloud-aerosol features to detect the PBL. The present study provides insight of PBL height variances in the GEOS-5 model. A case over the Equatorial Pacific indicates that PBL heights from the GEOS-5 model are greater than 25%, on average, than the satellite-derived PBL parameter. PBL height biases in the Equatorial Pacific may be related to the General Circulation Model (GCM) coupling scheme implemented in GEOS-5.

Jordan, Nikisa Samantha

32

Measurements of Tropospheric NO2 in Romania Using a Zenith-Sky Mobile DOAS System and Comparisons with Satellite Observations  

PubMed Central

In this paper we present a new method for retrieving tropospheric NO2 Vertical Column Density (VCD) from zenith-sky Differential Optical Absorption Spectroscopy (DOAS) measurements using mobile observations. This method was used during three days in the summer of 2011 in Romania, being to our knowledge the first mobile DOAS measurements peformed in this country. The measurements were carried out over large and different areas using a mobile DOAS system installed in a car. We present here a step-by-step retrieval of tropospheric VCD using complementary observations from ground and space which take into account the stratospheric contribution, which is a step forward compared to other similar studies. The detailed error budget indicates that the typical uncertainty on the retrieved NO2tropospheric VCD is less than 25%. The resulting ground-based data set is compared to satellite measurements from the Ozone Monitoring Instrument (OMI) and the Global Ozone Monitoring Experiment-2 (GOME-2). For instance, on 18 July 2011, in an industrial area located at 47.03°N, 22.45°E, GOME-2 observes a tropospheric VCD value of (3.4 ± 1.9) × 1015 molec./cm2, while average mobile measurements in the same area give a value of (3.4 ± 0.7) × 1015 molec./cm2. On 22 August 2011, around Ploiesti city (44.99°N, 26.1°E), the tropospheric VCD observed by satellites is (3.3 ± 1.9) × 1015 molec./cm2 (GOME-2) and (3.2 ± 3.2) × 1015 molec./cm2 (OMI), while average mobile measurements give (3.8 ± 0.8) × 1015 molec./cm2. Average ground measurements over “clean areas”, on 18 July 2011, give (2.5 ± 0.6) × 1015 molec./cm2 while the satellite observes a value of (1.8 ± 1.3) × 1015 molec./cm2.

Constantin, Daniel-Eduard; Merlaud, Alexis; Van Roozendael, Michel; Voiculescu, Mirela; Fayt, Caroline; Hendrick, Francois; Pinardi, Gaia; Georgescu, Lucian

2013-01-01

33

Development of marine observation satellite in Japan  

NASA Astrophysics Data System (ADS)

An outline of Japan's Marine Observation Satellite-1 (MOS-1), to be launched by an N-II vehicle in 1986, is presented. Satellite mission objectives are to collect ground data, and to develop remote sensing technology. MOS-1 nominal orbit is sun-synchronous at a 909 km altitude and an inclination of 99.1 deg, and the satellite will include three sensors: (1) a multispectral electronic self-scanning radiometer (2) a visible and thermal infrared radiometer, and (3) a microwave scanning radiometer. MOS-1 height is about 300 cm, length is approximately 150 cm, width is approximately 140 cm, and total weight is nearly 750 kg. In addition, ground segment systems are the tracking and control system, the operation control system (the main feature), and the data acquisition and distribution system. The data acquisition system will be installed about 50 km northwest of Tokyo, and the next MOS-1 is being considered, examining the usefulness of ocean phenomena satellite measurements.

Matsumoto, K.; Niwa, S.; Doura, T.; Yamamoto, S.

1982-09-01

34

The Earth observing system microwave limb sounder (EOS MLS) on the aura Satellite  

Microsoft Academic Search

The Earth Observing System Microwave Limb Sounder measures several atmospheric chemical species (OH, HO2, H2O, O3, HCl, ClO, HOCl, BrO, HNO3, N2O, CO, HCN, CH3CN, volcanic SO2), cloud ice, temperature, and geopotential height to improve our understanding of stratospheric ozone chemistry, the interaction of composition and climate, and pollution in the upper troposphere. All measurements are made simultaneously and continuously,

Joe W. Waters; Lucien Froidevaux; Robert S. Harwood; Robert F. Jarnot; Herbert M. Pickett; William G. Read; Peter H. Siegel; Richard E. Cofield; Mark J. Filipiak; Dennis A. Flower; James R. Holden; Gary K. Lau; Nathaniel J. Livesey; Gloria L. Manney; Hugh C. Pumphrey; Michelle L. Santee; Dong L. Wu; David T. Cuddy; Richard R. Lay; Mario S. Loo; Vincent S. Perun; Michael J. Schwartz; Paul C. Stek; Robert P. Thurstans; Mark A. Boyles; Kumar M. Chandra; Marco C. Chavez; Gun-Shing Chen; Bharat V. Chudasama; Randy Dodge; Ryan A. Fuller; Michael A. Girard; Jonathan H. Jiang; Yibo Jiang; Brian W. Knosp; Remi C. LaBelle; Jonathan C. Lam; Karen A. Lee; Dominick Miller; John E. Oswald; Navnit C. Patel; David M. Pukala; Ofelia Quintero; David M. Scaff; W. Van Snyder; Michael C. Tope; Paul A. Wagner; Marc J. Walch

2006-01-01

35

Small satellite launch system  

NASA Astrophysics Data System (ADS)

The World Administrative Radio Conference (WARC 92) delegates agreed to worldwide frequency allocation changes that will introduce new space communications services through low earth orbit (LEO) satellite systems. Iridium, Odyssey and Orbcomm are major proposals for these services, and each proposal is to launch 77, 12 and 18 small communications satellites. In this way, the new era of small satellites is going to be initiated. The anticipation of the expansion of the small satellite launch market, new cost-effective and flexible launch systems have been developed. In 1990 Orbital Science Corp. successfully completed the maiden flight of the PEGASUS winged launch vehicle and now has been developing the new TAURUS launch vehicle. Arianespace successfully completed two ASAP (Arian Structure for Auxiliary Payloads) missions, and its new small satellites deployment system is in the process of development. McDonnel Douglas is thinking of Delta II launch vehicle applications for small satellites. This trend is seen to continue through the 1990s. This paper describes the trend of the small satellite launch market and the availability of a planned launch system in Japan.

Kochiyama, Jiro

36

Satellite Power System (SPS).  

National Technical Information Service (NTIS)

Potential organizational options for a solar power satellite system (SPS) were investigated. Selection and evaluation criteria were determined to include timeliness, reliability, and adequacy to contribute meaningfully to the U.S. supply; political feasib...

H. G. Edler

1978-01-01

37

Cyberinfrastructure Initiatives of the Committee on Earth Observation Satellites (CEOS) Working Group on Information Systems and Services (WGISS)  

NASA Astrophysics Data System (ADS)

The Committee on Earth Observation Satellites (CEOS) was established in 1984 in response to a recommendation from the Economic Summit of Industrialized Nations Working Group on Growth, Technology, and Employment's Panel of Experts on Satellite Remote Sensing. CEOS participants are Members, who are national or international governmental organizations who operate civil spaceborne Earth observation satellites, and Associates who are governmental organizations with civil space programs in development or international scientific or governmental bodies who have an interest in and support CEOS objectives. The primary objective of CEOS is to optimize benefits of satellite Earth observations through cooperation of its participants in mission planning and in development of compatible data products, formats, services, applications and policies. To pursue its objectives, CEOS establishes working groups and associated subgroups that focus on relevant areas of interest. While the structure of CEOS has evolved over its lifetime, today there are three permanent working groups. One is the Working Group on Calibration and Validation that addresses sensor-specific calibration and validation and geophysical parameter validation. A second is the Working Group on Education, Training, and Capacity Building that facilitates activities that enhance international education and training in Earth observation techniques, data analysis, interpretation and applications, with a particular focus on developing countries. The third permanent working group is the Working Group on Information Systems and Services (WGISS). The purpose of WGISS is to promote collaboration in the development of the systems and services based on international standards that manage and supply the Earth observation data and information from participating agencies' missions. WGISS places great emphasis on the use of demonstration projects involving user groups to solve the critical interoperability issues associated with the achievement of global services and its structure reflects that objective. The Technology and Services Subgroup initiates tasks to explore emerging technologies that can be employed to create data and information systems and to develop interoperable services. The interests of the subgroup span the full range of the information processing chain from the initial ingestion of satellite data into archives through to the incorporation of derived information into end-user applications. The subgroup has overseen the creation of an Interoperable Directory Network and an Interoperable Catalog System and has tasks that are investigating the use of new technologies such as Web Services, Grid, and Open Geographical Information Systems to provide enhanced capabilities. The WGISS Projects and Applications Subgroup works with outside organizations to understand their requirements and then helps them to exploit the tools and services available through WGISS and its members and associates. WGISS has instituted the concept of a WGISS Test Facility to test and develop information systems and services prototypes collaboratively with these organizations to meet their specific requirements. This approach has the dual benefit of addressing real information systems and services needs of science and applications projects and helping WGISS to expand and improve its capabilities based on the experience and lessons learned from working with the projects.

McDonald, K. R.; Faundeen, J. L.; Petiteville, I.

2005-12-01

38

A Global Observing System for Mars: The dual satellite Mars Astrobiology and Climate Observatory (MACO)  

NASA Astrophysics Data System (ADS)

We summarize a planetary decadal survey white paper describing the rationale for and key elements of a dual satellite orbiting mission (DSM) concept called the Mars Astrobiology and Climate Observatory (MACO). MACO uses mm-wavelength satellite to satellite (sat-sat) occultations in combination with solar occultations (SO) to answer and strongly constrain many key lower and middle atmosphere Mars science questions previously considered unachievable from orbit. On the climate side, MACO would focus on the hydrological, dust and energy cycles of Mars. MACO would measure the transport of water in the present Martian climate, identify sources and sinks and constrain processes in order to better understand present and past Martian climate and glacial and subsurface water reservoirs. Dust-penetrating, satellite-to-satellite mm-wave occultations would profile water vapor to 3%, temperature to 0.4K, geopotential height of pressure to 10 m, line of sight winds to < 2 m/s and balanced winds via pressure gradients, as well turbulence and certain trace constituents with 60 meter diffraction limited vertical resolution and high precision extending down to the surface. A prototype mm-wave occultation instrument will be demonstrated in 2010 via high altitude aircraft to aircraft occultations. MACO will make coincident thermal IR and shortwave measurements to characterize airborne dust to understand dust storm initiation and evolution and how atmospheric dust concentrations are maintained in general. The combination of sensitivity, accuracy and vertical resolution from the satellite to satellite occultation is simply not possible with radiometers and will provide ~30,000 globally distributed near-entry probe quality profiles each Martian year profiling the boundary layer and exchange between the atmosphere and surface. A near-IR solar occultation instrument, such as the French SOIR or a derivative of the Canadian ACE FTIR instrument, would survey chemical trace species such as methane in the Martian atmosphere to look for signatures of subsurface processes related to possible habitable zones and life. MACO’s winds will be key in tracing plumes back to their source regions. Proposed near-surface ion-related heterogeneous chemistry will be assessed by profiling near surface concentrations of H2O2, H2O and dust to look for predicted enhancements in of H2O2 and how they vary with H2O and dust concentrations. MACO’s combined capabilities are a superset of the Mars Science Orbiter (MSO) recommended by the Calvin et al. (2007) report. MACO would fit as a moderate scale mission in the 2016 launch opportunity. Alternatively, since NASA and ESA have recently announced their intent to fly a single orbiter, trace gas mission in 2016, the MACO mm occultation receiver (which can also measure thermal emission and solar occultations) could be flown on that mission and the occultation transmitter could be carried on another mission flown by an international partner such as Japan or India.

Kursinski, E. R.; Lyons, J.; Newman, C.; Richardson, M. I.; Ward, D.; Otarola, A. C.

2009-12-01

39

The National Polar-orbiting Operational Environmental Satellite System: Capabilities for Atmospheric Remote Sensing for NWP and Climate -- Moving Towards a Global Earth Observation System of Systems  

NASA Astrophysics Data System (ADS)

Over the last decade, the tri-agency Integrated Program Office (IPO), comprised of the National Oceanic and Atmospheric Administration (NOAA), the Department of Defense (DoD), and the National Aeronautics and Space Administration (NASA), has been managing the development of the National Polar-orbiting Operational Environmental Satellite System (NPOESS). Once operational later this decade, NPOESS will replace NOAA's Polar-orbiting Operational Environmental Satellites (POES) and DoD's Defense Meteorological Satellite Program (DMSP) systems. The IPO, through its Acquisition and Operations contractor, Northrop Grumman, will launch NPOESS spacecraft into three orbital planes to provide a single, national system capable of satisfying both civil and national security requirements for space-based, remotely sensed environmental data. With the development of NPOESS, we are evolving the existing "weather" satellites into integrated environmental observing systems by expanding our capabilities to observe, assess, and predict the total Earth system - ocean, atmosphere, land, and the space environment. The NPOESS will enable more accurate short-term weather forecasts and severe storm warnings and improved monitoring of atmospheric phenomena. NPOESS will also provide continuity of critical data for monitoring, understanding, and predicting climate change and assessing the impacts of climate change on seasonal and longer time scales. For these purposes, the NPOESS Integrated Program Office [IPO] is developing a suite of advanced, atmospheric sounding/probing instruments as a major part of the next generation meteorological, environmental and climate operational satellite system in polar, low earth orbit [LEO]. The IPO is developing the CrIS, Cross-track Infrared Sounder, an Ozone Mapping & Profiler Suite [OMPS]and a Visible and Infrared Imager and Radiometer Suite [VIIRS] and NASA is developing an Advanced Technology Microwave Sounder [ATMS]. These four instruments will be key parts of the NPOESS operational satellite system and its precursor, bridging and risk-reduction mission - the NPOESS Preparatory Project [NPP]. The CrIS/ATMS/OMPS (& VIIRS) and, later on NPOESS, a Conical-scanning Microwave Imager and Sounder [CMIS] will represent a USA highly capable, complementary sounding and imaging suite for the next generation. In the same time frame the European community, EUMETSAT, European Organization for the Exploitation of Meteorological Satellite Systems, will be flying their next generation, operational, polar-orbiting LEO system, METOP. METOP will have a highly capable FTS sounder, IASI [Infrared Atmospheric Sounder Interferometer], an Advanced Microwave Sounding Unit [AMSU], a Global Ozone Monitoring Experiment [GOME-2], a GNSS Receiver for Atmospheric Sounding [GRAS]and an Advanced Very High Resolution Radiometer [AVHRR]. The NPOESS & METOP sounders and imagers will represent a significant contribution to a polar-orbiting, atmospheric sounding and imaging component of an emerging Global Earth Observation System of Systems [GEOSS] for NWP and Climate. Similarly the Geostationary Operational Environmental Satellite System [GOES-R] & Meteosat Second Generation [MSG] sounders and imagers will represent an important geostationary component of such a GEOSS.

Mango, S. A.; Hinnant, F.; Hoffman, C. W.; Smehil, D. L.; Schneider, S. R.; Simione, S.; Needham, B.; Stockton, D.

2005-12-01

40

Hurricane generated waves as observed by satellite  

Microsoft Academic Search

A data set consisting of observations of significant wave height and wind speed within mature hurricanes has been obtained from the GEOSAT satellite mission. Due to the global coverage of the satellite, this data set is extensive, consisting of 100 hurricanes. In addition, as the satellite rapidly propagates across the region influenced by the hurricane wind field, an almost instantaneous

I. R Young; G. P Burchell

1996-01-01

41

Observations of planetary satellites with ISO  

Microsoft Academic Search

Several observational programmes were conducted with ISO (Kessler et al., 1996) aiming at the investigation of the near- and far- infrared spectrum of the satellites of the giant planets. Thus, Jupiter's satellites Callisto, Io and Ganymede were explored mainly with the spectrometers, while the spectrum of Titan, Saturn's largest satellite, was investigated thoroughly by all the instruments. The analysis of

A. Coustenis; Th. Encrenaz; E. Lellouch; A. Salama; Th. Müller; M. J. Burgdorf; B. Schmitt; H. Feuchtgruber; B. Schulz; S. Ott; Th. de Graauw; M. J. Griffin; M. F. Kessler

2002-01-01

42

Satellite observations of mesospheric ozone  

NASA Astrophysics Data System (ADS)

A method is presented by which measurements of O2 Atmospheric band volume emission rate and temperature can be used to infer ozone mixing ratios in the mesosphere. The retrieval relies on the fact that a significant portion of the dayglow originates from ozone photolysis. This method is used to derive ozone concentrations from observations made by the High Resolution Doppler Imager (HRDI) on board the Upper Atmosphere Research Satellite. Five years of measurements are presented, with coverage up to 72° in latitude and an altitude range of 65 to 97 km. Observations show repeatable seasonal variability, with equatorial ozone showing a predominantly semi-annual variation at all altitudes. Equatorial ozone maximizes at equinox, with the amplitude of the variation being greater than 15% of the annual mean between 75 and 95 km. At mid-latitudes the variation changes to an annual cycle, with minimum ozone concentrations at 80 km seen during summer solstice. This is coincident with a maximum in water vapor measured by the Halogen Occultation Experiment (HALOE). At 95 km mid-latitude ozone peaks during summer solstice, coinciding with a minimum in observed temperatures. Simulations using a 1-dimensional photochemical model, constrained to observed temperatures and water vapor concentrations, successfully reproduce the relative changes in ozone. The minimum in ozone at 80 km is due to increased destruction of odd-oxygen by odd- hydrogen resulting from photolysis of water vapor. The maximum at 95 km is a result of the temperature dependence on odd-oxygen partitioning, as well as increased photolytic production of atomic oxygen. A unique feature of the HRDI mesospheric ozone dataset is that all daylight local times are sampled. In the mesopause region large diurnal variability is observed, which is the result of a combination of chemical and dynamical control. Below 80 km the daytime variation in ozone is determined by photochemical reactions that affect the concentrations of atomic oxygen and hydrogen species. Above 80 km modeling studies show that ozone is sensitive to vertical motions. In particular, an enhancement in afternoon ozone seen during equinox is successfully modeled as a result of tidal advection of atomic oxygen from the lower thermosphere.

Marsh, Daniel Robert

43

Systems approach to developing a climate data record from satellite observations  

NASA Astrophysics Data System (ADS)

A Climate Data Record (CDR) consists of a body of information of some observable of the Earth's climate that is of sufficient information content and accuracy to allow climate science to be performed with this record now and in the distant future. We examine the generation of a hyperspectral infrared CDR for the Atmospheric Infrared Sounder (AIRS) instrument as good example. For the information to be accurate, extensive pre-flight and in-flight calibration and characterization is required for spatial, spectral, polarimetric and radiometric performance. Maintaining the accuracy in orbit requires either inherent stability, or the ability to stabilize the calibration using additional information such as an ocean buoy network, or ground calibration sites. In addition to having excellent data quality, documentation and archiving are also critical. Details of the instrument design and test procedures must be recorded. All data acquired during the preflight testing must be archived in a format and medium that will be accessible by computers several decades into the future. A Systems Engineering approach is used to define the requirements for the AIRS hyperspectral infrared climate data record, for performance, characterization, and documentation. Examples are given from the AIRS project activities on how the record can be created including a comprehensive drawing database, a document archive for all pre-flight and in-flight procedures and reports, software and data archiving, and instrument performance verification and validation for compliance with climate science requirements.

Broberg, Steve E.; Pagano, Thomas S.; Aumann, Hartmut H.; Elliott, Denis A.; O'Callaghan, Fred

2010-08-01

44

Measurements of tropospheric NO2 in Romania using a zenith-sky mobile DOAS system and comparisons with satellite observations.  

PubMed

In this paper we present a new method for retrieving tropospheric NO2 Vertical Column Density (VCD) from zenith-sky Differential Optical Absorption Spectroscopy (DOAS) measurements using mobile observations. This method was used during three days in the summer of 2011 in Romania, being to our knowledge the first mobile DOAS measurements peformed in this country. The measurements were carried out over large and different areas using a mobile DOAS system installed in a car. We present here a step-by-step retrieval of tropospheric VCD using complementary observations from ground and space which take into account the stratospheric contribution, which is a step forward compared to other similar studies. The detailed error budget indicates that the typical uncertainty on the retrieved NO2tropospheric VCD is less than 25%. The resulting ground-based data set is compared to satellite measurements from the Ozone Monitoring Instrument (OMI) and the Global Ozone Monitoring Experiment-2 (GOME-2). For instance, on 18 July 2011, in an industrial area located at 47.03°N, 22.45°E, GOME-2 observes a tropospheric VCD value of (3.4 ± 1.9) × 1015 molec./cm2, while average mobile measurements in the same area give a value of (3.4 ± 0.7) × 10(15) molec./cm2. On 22 August 2011, around Ploiesti city (44.99°N, 26.1°E), the tropospheric VCD observed by satellites is (3.3 ± 1.9) × 10(15) molec./cm2 (GOME-2) and (3.2 ± 3.2) × 10(15) molec./cm2 (OMI), while average mobile measurements give (3.8 ± 0.8) × 10(15) molec./cm2. Average ground measurements over "clean areas", on 18 July 2011, give (2.5 ± 0.6) × 10(15) molec./cm2 while the satellite observes a value of (1.8 ± 1.3) × 10(15) molec./cm2. PMID:23519349

Constantin, Daniel-Eduard; Merlaud, Alexis; Van Roozendael, Michel; Voiculescu, Mirela; Fayt, Caroline; Hendrick, Franēois; Pinardi, Gaia; Georgescu, Lucian

2013-03-20

45

Earth observing satellite plans in India  

NASA Astrophysics Data System (ADS)

One of the major objectives of the Indian Space Programme is to develop, launch and operate earth observing satellites to cater to the data needs of the remote sensing user community. Towards this, development of suitable multispectral sensors through satellites and aircraft have played a crucial role. The Rohini and Bhaskara satellites launched during early 1980's provided the base for further development. Presently the first of a series of Remote Sensing satellites, IRS-1A is in orbit and is providing data. The necessary expertise to utilise the remotely sensed data was developed through a set of application projects under Indian Remote Sensing Satellite - Utilisation Programme (IRS-UP) and Remote Sensing Application Mission (RSAM) being carried out with active collaboration of several Central/State user departments/agencies. The application projects cover several themes such as agriculture, water resources, forestry, soil, marine resources etc. in addition to natural calamities such as flood and drought. The IRS-UP projects initiated in 1983, has helped in developing several methodology packages for operational utilisation of remote sensing for natural resources monitoring. Nationwide projects such as Wasteland Mapping, Drinking Water Technology Mission etc. have remote sensing as a major input. Towards ensuring requisite infrastructure and facility, 5 Regional Remote Sensing Service Centres are being operationalised with VAX-11/780 computer based image processing system, in addition to setting up of remote sensing centres in each State/Union Territory. The training of adequate manpower has been another area of attention. The country is poised to reap the advantages of remote sensing technology towards its development.

Rajan, Y. S.; Behera, G.; Gupta, A. K.; Manikiam, B.

46

Satellite Observations From the International Polar Year  

NASA Astrophysics Data System (ADS)

To realize the benefit of the growing number of international satellites to the scientific objectives of the 2007-2008 International Polar Year (IPY), the Global Interagency IPY Polar Snapshot Year (GIIPSY) was established in November 2005 to develop a consensus on polar science requirements and objectives for IPY that could best and perhaps only be met using the Earth-observing satellites. Requirements focused on all aspects of the cryosphere and ranged from sea ice and ice sheets to permafrost and snow cover. Individual topics included how best to develop high-resolution digital elevation models of outlet glaciers using stereo-optical systems, measure ice sheet surface velocity using interferometric synthetic aperture radar (InSAR), and repeatedly measure sea ice motion using optical and microwave imaging instruments. Because of this foresight, several IPY science objectives were well met using satellite observations, allowing a wealth of valuable data to be collected on cryospheric processes (Figure 1). Further, the framework for coordinating these remote sensing efforts serves as a valuable model for future coordinated efforts to monitor cryospheric dynamics.

Jezek, Kenneth; Drinkwater, Mark

2010-04-01

47

Cloud Forecasting for Earth Observation Satellites.  

National Technical Information Service (NTIS)

The project 'Cloud Forecasting for Earth Observation Satellites' is conducted by NEO, Netherlands Geomatics and Earth Observation B.V., Lelystad, The Netherlands and KNMI, Royal Netherlands Meteorological Institute, De Bilt, The Netherlands. The project h...

H. Roozekrans N. van der Linden R. Beck S. van der Veen W. Som de Cerff

1999-01-01

48

Dactyl: Galileo Observations of Ida's Satellite  

Microsoft Academic Search

Galileo's flyby of 243 Ida in August 1993 led to the discovery of a small satellite, Dactyl, some 85 km from the asteroid's center. From Earth at mean opposition, the satellite is aV= +20.3 mag object (some 6.7 magnitudes fainter than Ida). Forty-seven images of the satellite at 18 different observing times were played back, including one multicolor sequence in

J. Veverka; P. C. Thomas; P. Helfenstein; P. Lee; A. Harch; S. Calvo; C. Chapman; M. J. S. Belton; K. Klaasen; T. V. Johnson; M. Davies

1996-01-01

49

Satellite Observations for Detecting and Tracking Changes in Atmospheric Composition  

EPA Science Inventory

The international scientific community's Integrated Global Atmosphere Chemistry Observation System report outlined a plan for ground-based, airborne and satellite Measurements, and models to integrate the observations into a 4-dimensional representation of the atmosphere (space a...

50

Heuristics for scheduling Earth observing satellites  

NASA Astrophysics Data System (ADS)

This paper describes several methods for assigning tasks to Earth Observing Systems Satellites (EOS). We present empirical results for three heuristics, called: Priority Dispatch (PD), Look Ahead (LA), and Genetic Algorithm (GA). These heuristics progress from simple to complex, from less accurate to more accurate, and from fast to slow. We present empirical results as applied to the Window-Constrained Packing problem (WCP). The WCP is a simplified version of the EOS scheduling problem. We discuss the problem of having more than one optimization criteria. We will also discuss the relationship between the WCP and the more traditional Knapsack and Weighted Early/Tardy problems.

Wolfe, William J.; Sorensen, Stephen E.

1999-09-01

51

Satellite system providing optimal space situational awareness  

US Patent & Trademark Office Database

A satellite system for observing space objects includes two or more satellites positioned in an Earth orbit and configured to observe objects in various orbits including those viewed (i) against the Earth's background; (ii) against a sunlit Earth background; and (iii) against a space background. An electromagnetic sensor may be provided on at least one of the satellites that is responsive to electromagnetic radiation having a wavelength that discriminates against substantial reflection of electromagnetic radiation from the Earth's atmosphere to observe the space object. A method of observing a space object using a satellite system is also disclosed.

Robinson; Ian (Redondo Beach, CA)

2013-08-20

52

Satellite Navigation Systems  

NSDL National Science Digital Library

The Global Positioning System (GPS) has been in operation for several years, and its use is continually rising. GPS is the main satellite navigation system developed by the United States. There are countless applications of this technology, and numerous international efforts are currently underway.The Topcon Positioning Systems company provides an excellent introduction to GPS technology in its online book (1). The first couple chapters describe the evolution of GPS and its fundamentals, and the remaining material focuses on some specific issues. A more advanced tutorial is given through the IBM Web site (2). A brief, free registration is required to view it, and some familiarity with Java is recommended. The European Space Agency provides this page about satellite navigation (3), which describes, among other things, Galileo. This is not the astronomer; Galileo is Europe's version of GPS, scheduled for completion in 2008. Another system, developed by Russia, is detailed on the Space and Technology Web site (4). The short summary describes the 20-year history of the Global Navigation Satellite System (GLONASS), as well as upgrades that are in progress. Differential GPS, a service that is more accurate than standard GPS in areas with poor coverage, is operated by the US Coast Guard Navigation Center (5). Some information about the status of nationwide DGPS expansion is given. Several research and development projects, technology highlights, and GPS implementations are covered on the UNAVCO home page (6). The facility primarily fosters work to expand the applications of satellite navigation. With the wave of kidnapping cases reported across the country, a novel use of GPS is being marketed to keep track of children (7). These portable devices can be worn on the wrist, like a watch, so parents can always know where their kids are. Another news story describes the use of GPS in mining operations (8). The technology allows operators of huge three-story dump trucks to detect obstacles and maneuver the vehicle with only limited visibility.

Leske, Cavin.

2002-01-01

53

Atmospheric Density Determination from Satellite Observations.  

National Technical Information Service (NTIS)

The atmospheric density at perigee height is computed from satellite observations by the following procedure: (1) obtain accurate orbital elements from a differential orbit correction procedure, (2) fit each element as a function of time, (3) analyze thee...

R. J. Greenfield J. P. Rossoni P. Sconzo

1964-01-01

54

Global Warming Trend of Mean Tropospheric Temperature Observed by Satellites  

Microsoft Academic Search

We have analyzed the global tropospheric temperature for 1978 to 2002 with the use of passive microwave sounding data from the NOAA series of polar orbiters and the Earth Observing System Aqua satellite. To accurately retrieve the climatic trend, we combined the satellite data with an analytic model of temperature that contains three different time scales: a linear trend and

Konstantin Y. Vinnikov; Norman C. Grody

2003-01-01

55

Integrate satellite observing images for the Gulf of Mexico  

Microsoft Academic Search

A number of satellite image sources providing meteorological and environmental information are available over the Gulf of Mexico (GOM). Those satellite images are taken periodically in order to observe weather changes. However, users usually face problems when they want to search, retrieve and combine images from multiple data sources. Without an adequate system and skilled personnel for managing data, the

Longzhuang Li; Shanxian Mao

2010-01-01

56

Polar Airborne Observations Fill Gap in Satellite Data  

Microsoft Academic Search

In October 2009, NASA's Ice, Cloud, and land Elevation Satellite (ICESat) stopped collecting science data. However, noting the progressive degradation of ICESat's Geoscience Laser Altimeter System (GLAS), NASA had begun the previous year to plan a series of instrumented aircraft missions to fill the impending gap in satellite observations due to the loss of GLAS. Called Operation IceBridge, the project

Lora Koenig; Seelye Martin; Michael Studinger; John Sonntag

2010-01-01

57

Terrestrial Observations from NOAA Operational Satellites.  

PubMed

Important applications to oceanography, hydrology, and agriculture have been developed from operational satellites of the National Oceanic and Atmospheric Administration and are currently expanding rapidly. Areas of interest involving the oceans include sea surface temperature, ocean currents, and ocean color. Satellites can monitor various hydrological phenomena, including regional and global snow cover, river and sea ice extent, and areas of global inundation. Agriculturally important quantities derived from operational satellite observations include precipitation, daily temperature extremes, canopy temperatures, insolation, and snow cover. This overview describes the current status of each area. PMID:17776018

Yates, H; Strong, A; McGinnis, D; Tarpley, D

1986-01-31

58

Development of the Large-Scale Statistical Analysis System of Satellites Observations Data with Grid Datafarm Architecture  

NASA Astrophysics Data System (ADS)

In the Solar-Terrestrial Physics (STP) field, the amount of satellite observation data has been increasing every year. It is necessary to solve the following three problems to achieve large-scale statistical analyses of plenty of data. (i) More CPU power and larger memory and disk size are required. However, total powers of personal computers are not enough to analyze such amount of data. Super-computers provide a high performance CPU and rich memory area, but they are usually separated from the Internet or connected only for the purpose of programming or data file transfer. (ii) Most of the observation data files are managed at distributed data sites over the Internet. Users have to know where the data files are located. (iii) Since no common data format in the STP field is available now, users have to prepare reading program for each data by themselves. To overcome the problems (i) and (ii), we constructed a parallel and distributed data analysis environment based on the Gfarm reference implementation of the Grid Datafarm architecture. The Gfarm shares both computational resources and perform parallel distributed processings. In addition, the Gfarm provides the Gfarm filesystem which can be as virtual directory tree among nodes. The Gfarm environment is composed of three parts; a metadata server to manage distributed files information, filesystem nodes to provide computational resources and a client to throw a job into metadata server and manages data processing schedulings. In the present study, both data files and data processes are parallelized on the Gfarm with 6 file system nodes: CPU clock frequency of each node is Pentium V 1GHz, 256MB memory and40GB disk. To evaluate performances of the present Gfarm system, we scanned plenty of data files, the size of which is about 300MB for each, in three processing methods: sequential processing in one node, sequential processing by each node and parallel processing by each node. As a result, in comparison between the number of files and the elapsed time, parallel and distributed processing shorten the elapsed time to 1/5 than sequential processing. On the other hand, sequential processing times were shortened in another experiment, whose file size is smaller than 100KB. In this case, the elapsed time to scan one file is within one second. It implies that disk swap took place in case of parallel processing by each node. We note that the operation became unstable when the number of the files exceeded 1000. To overcome the problem (iii), we developed an original data class. This class supports our reading of data files with various data formats since it converts them into an original data format since it defines schemata for every type of data and encapsulates the structure of data files. In addition, since this class provides a function of time re-sampling, users can easily convert multiple data (array) with different time resolution into the same time resolution array. Finally, using the Gfarm, we achieved a high performance environment for large-scale statistical data analyses. It should be noted that the present method is effective only when one data file size is large enough. At present, we are restructuring the new Gfarm environment with 8 nodes: CPU is Athlon 64 x2 Dual Core 2GHz, 2GB memory and 1.2TB disk (using RAID0) for each node. Our original class is to be implemented on the new Gfarm environment. In the present talk, we show the latest results with applying the present system for data analyses with huge number of satellite observation data files.

Yamamoto, K.; Murata, K.; Kimura, E.; Honda, R.

2006-12-01

59

Global warming: Evidence from satellite observations  

Microsoft Academic Search

Observations made in Channel 2 (53.74 GHz) of the Microwave Sounding Unit (MSU) radiometer, flown on-board sequential, sun-synchronous, polar-orbiting NOAA operational satellites, indicate that the mean temperature of the atmosphere over the globe increased during the period 1980 to 1999. In this study, we have minimized systematic errors in the time series introduced by satellite orbital drift in an objective

C. Prabhakara; J.-M. Yoo; G. Dalu

2000-01-01

60

Examining the wind forced velocity structure of the California Current system using observations derived from satellite remote sensing  

NASA Astrophysics Data System (ADS)

Methodology is derived to observe mesoscale time-dependent wind-driven ocean velocities. The procedure involves the removal of a geostrophic component from "total flow" velocity observations. Total flow measuring data sets are investigated by statistical analysis, searching for theoretical characteristic signals of wind-driven flow. These signals are found in drifting buoy data, acoustic Doppler current profiler data (ADCP) data, and velocity data extracted from satellite imagery using the maximum cross-correlation technique (MCC), demonstrating that these products observe both the geostrophic and the wind-driven components of the ocean flow. Initial tests, used altimeter mean absolute dynamic topography (MADT) data as the geostrophic signal removed. This resulted in residual velocities that were dominated by vertical geostrophic shear. Methodology was then developed to combine CTD (conductivity, depth, temperature) data, which provides estimates of the geostrophic current relative to the surface, with the MADT product, to produce geostrophic velocity estimates at depth. For MCC derived observations to be used in this analysis, the depth of this product required consideration. Statistical comparison with coincident ADPC and drifter velocity observations suggest that the MCC derived velocities are characteristics of ocean currents at ˜30 m depth. This characteristic is hypothesized to be a result of the inherent average velocity observations produced by the MCC method and the nature of the variability of the ocean currents. A 12-year time series of wind-driven velocity observations is then produced using this methodology applied to the satellite and in situ data sets. Observations generated demonstrate characteristics consistent with Ekman theory. Strong temporal agreement was found in the fluctuations wind velocity observations derived from satellite scatterometry and the wind-driven observations. Regression models, driven by the wind and the wind-driven current observations, are then used to characterize the response of the ocean to wind-forcing. The vertical response demonstrated strong linear magnitude decay with depth. The horizontal response shows complex structure that demonstrates little connection to the spatial patterns of wind velocity. To attempt to understand these patterns of wind-influence EOF and principal axis analysis are used. The results suggest that the spatial variation of frictional wind influence is strongly modulated by the shape of the coastline. Further analysis suggests that these regions of increased wind influence are driving a significant portion of the variability of the California Current. Future work will involve generating coastal altimetry observations to increase the spatial coverage of this wind-driven velocity product.

Matthews, Dax Kristopher

61

Lightning-generated whistler waves observed by probes on the Communication/Navigation Outage Forecast System satellite at low latitudes  

NASA Astrophysics Data System (ADS)

Direct evidence is presented for a causal relationship between lightning and strong electric field transients inside equatorial ionospheric density depletions. In fact, these whistler mode plasma waves may be the dominant electric field signal within such depletions. Optical lightning data from the Communication/Navigation Outage Forecast System (C/NOFS) satellite and global lightning location information from the World Wide Lightning Location Network are presented as independent verification that these electric field transients are caused by lightning. The electric field instrument on C/NOFS routinely measures lightning-related electric field wave packets or sferics, associated with simultaneous measurements of optical flashes at all altitudes encountered by the satellite (401-867 km). Lightning-generated whistler waves have abundant access to the topside ionosphere, even close to the magnetic equator.

Holzworth, R. H.; McCarthy, M. P.; Pfaff, R. F.; Jacobson, A. R.; Willcockson, W. L.; Rowland, D. E.

2011-06-01

62

Earth System: Satellites  

NSDL National Science Digital Library

There are thousands of artificial satellites circling our planet for navigation, communications, entertainment, and science. These satellites are an integral part of our everyday life, and they collect data which cannot be obtained from Earth's surface. This video segment describes the basic components of a satellite and some of applications that have been developed for both geostationary and orbiting satellites. The segment is three minutes fifty seconds in length. A background essay and discussion questions are included.

63

Scheduling earth observation activities in LEO satellites using graph coloring problem  

Microsoft Academic Search

Scheduling system of low earth orbit (LEO) satellite operations is one of the important tasks performed in satellites. Satellite specific constraints, satellite priorities, revenue of certain payloads and special operations, as well as visibility conflicts are taken into consideration while generating the operations schedules in an optimum way. This paper uses graph coloring problem for earth observation satellite scheduling, where

Arezoo Sarkheyli; Bahman Ghorbani Vaghei; Reza Askari Moghadam; Alireza Bagheri

2010-01-01

64

Naval EarthMap Observer (NEMO) satellite  

NASA Astrophysics Data System (ADS)

The Office of Naval Research (ONR) and the Naval Research Laboratory (NRL) have initiated the Hyperspectral Remote Sensing Technology (HRST) program to demonstrate the utility of a hyperspectral earth-imaging system to support Naval needs for characterization of the littoral regions of the world. One key component of the HRST program is the development of the Naval EarthMap Observer (NEMO) satellite system to provide a large hyperspectral data base. NEMO will carry the Coastal Ocean Imaging Spectrometer (COIS) which will provide images of littoral regions with 210 spectral channels over a bandpass of 0.4 to 2.5 micrometer. Since ocean environments have reflectances typically less than 5%, this system requires a very high signal-to-noise ratio (SNR). COIS will sample over a 30 km swath width with a 60 m Ground Sample Distance (GSD) with the ability to go to a 30 m GSD by utilizing the systems attitude control system to 'nod' (i.e., use ground motion compensation to slow down the ground track of the field of view). Also included in the payload is a co-registered 5 m Panchromatic Imager (PIC) to provide simultaneous high spatial resolution imagery. A sun-synchronous, 97.81 degree inclination, circular orbit of 605 km allows continuous repeat coverage of the whole earth. One unique aspect of NEMO is an on-board processing system, a feature extraction and data compression software package developed by NRL called the Optical Real-Time Spectral Identification System (ORASIS). ORASIS employs a parallel, adaptive hyperspectral method for real time scene characterization, data reduction, background suppression, and target recognition. The use of ORASIS is essential for management of the massive amounts of data expected from the NEMO HSI system, and for developing Naval products under HRST. The combined HSI and panchromatic images will provide critical phenomenology to aid in the operation of Naval systems in the littoral environment. The imagery can also satisfy a number of commercial and science community requirements for moderate spatial and high spectral resolution remote sensing data over land and water. Specific areas of interest for the Navy include bathymetry, water clarity, bottom type, atmospheric visibility, bioluminescence potential, beach characterization, underwater hazards, total column atmospheric water vapor, and detection and mapping of subvisible cirrus. These data support requirements for Joint Strike and Joint Littoral warfare, particularly for environmental characterization of the littoral ocean. Demonstrations of direct downlinking of near real-time data to the warfighter are also being formulated. The NEMO satellite is planned to launch in 2000 followed by an operational period of 3 to 5 years.

Wilson, Thomas L.; Davis, Curtiss O.

1999-10-01

65

Dactyl: Galileo Observations of Ida's Satellite  

NASA Astrophysics Data System (ADS)

Galileo's flyby of 243 Ida in August 1993 led to the discovery of a small satellite, Dactyl, some 85 km from the asteroid's center. From Earth at mean opposition, the satellite is a V= +20.3 mag object (some 6.7 magnitudes fainter than Ida). Forty-seven images of the satellite at 18 different observing times were played back, including one multicolor sequence in which the satellite is resolved adequately to distinguish surface markings (˜105 m/pxl) and three higher resolution single-color views (89, 39, and 24 m/pxl). The satellite, mean radius = 0.7 km, is an elongated, but not angular body with principal diameters of 1.6 × 1.4 × 1.2 km. In the highest resolution view, the longest axis points approximately in the direction of Ida, and its shortest axis is perpendicular to the orbital plane. The spin period is slow (> 8 hr?) and may be synchronous. The satellite shows no conspicuous sharp edges and is much less irregular in shape than Ida. Limb profiles are remarkably smooth over distances of 200-300 m. The geometric albedos of the two objects are similar (0.20 vs 0.21), as are the 0.4-1.0-?m colors. Like Ida, Dactyl is an S-asteroid, but has a slightly deeper 1-?m band than Ida (by 5-8%). While no identical regions (in color) are seen on Ida, the color difference is consistent with color variations reported within the Koronis family and may be due to a slightly higher pyroxene/olivine ratio on the satellite. More than a dozen craters ranging from ?90 to 280 m diameter are visible in the best image (39 m/pxl at 47° phase). The largest contains an off-centered, positive relief feature some 75 m across. The image includes an intriguing crater chain, but no grooves, ridges, or sharp edges are evident. In terms of limb roughness, Dactyl is much smoother than Ida, but comparable to the two satellites of Mars, Phobos and Deimos. While the satellite's origin is uncertain, a likely scenario would have the satellite date from the breakup of the Koronis family. It is interesting that crater densities on the satellite are similar to those on Ida itself.

Veverka, J.; Thomas, P. C.; Helfenstein, P.; Lee, P.; Harch, A.; Calvo, S.; Chapman, C.; Belton, M. J. S.; Klaasen, K.; Johnson, T. V.; Davies, M.

1996-03-01

66

Satellite Ring effect observations of aerosol properties  

NASA Astrophysics Data System (ADS)

The Ring effect describes the so-called ‘filling-in' of solar Fraunhofer lines in the spectra of scattered sun light compared to direct sun light observations. It was first observed by Shefov (1959) and Grainger and Ring (1962). Observations of the Ring effect can be used to investigate details of the atmospheric radiative transfer. The filling-in of Fraunhofer lines depends in particular on the presence and properties of clouds and aerosols. Several algorithms for cloud properties from Ring effect observations were developed in recent years and successfully applied to observations from TOMS, GOME, and OMI satellite instruments. In this study we extend the application of satellite Ring effect observations to the retrieval of information on tropospheric aerosols. In contrast to observations of absorptions of the oxygen molecule O2 or dimer O4, the Ring effect shows only a rather weak dependence on surface albedo. Thus the presence of aerosols usually leads to a decrease of the Ring effect (depending on layer height), because aerosols shield possible Raman scattering events inside and below the aerosol layer. We present a case study for Beijing, for which we find that with increasing aerosol optical depth (determined from sun photometers on the ground) the Ring effect in satellite observations systematically decreases. Also a dependence on aerosol layer altitude is found. This finding is in agreement with radiative transfer simulations. The dependence of the Ring effect on the aerosol layer height offers the interesting possibility to determine aerosol profile information from passive UV/vis satellite instruments. This might be of special importance for future satellite missions with small ground pixels, because of the smaller probability of cloud contamination.

Wagner, Thomas; Penning de Vries, Marloes; Deutschmann, Tim

2010-05-01

67

Satellite clocks characterization and monitoring for global navigation satellite systems  

Microsoft Academic Search

In Global Navigation Satellite Systems (GNSS) the user’s position is determined measuring the time of flight of the signals broadcast from satellites, which is proportional to the distance between the user and each satellite of the constellation. Time and frequency metrology has an essential role in satellite navigation systems: since a distance can be measured from a time, any error

A. Cernigliaro; I. Sesia

2011-01-01

68

Global canopy interception from satellite observations  

Technology Transfer Automated Retrieval System (TEKTRAN)

A new methodology for retrieving rainfall interception rates from multi satellite observations is presented. The approach makes use of the daily productof the Global Precipitation Climatology Project (GPCP) as driving data and applies Gash’s analytical model to derive interception rates at global sc...

69

Ballistic missile track initiation from satellite observations  

Microsoft Academic Search

An algorithm is presented to initiate tracks of a ballistic missile in the initial exoatmospheric phase, using line of sight (LOS) measurements from one or more moving platforms (typically satellites). The major feature of this problem is the poor target motion observability which results in a very ill-conditioned estimation problem. The Gauss-Newton iterative least squares minimization algorithm for estimating the

M. Yeddanapudi; Y. Bar-Shalom; K. R. Pattipati; S. Deb

1995-01-01

70

Satellite systems for maritime navigation  

NASA Astrophysics Data System (ADS)

The principles underlying the design of Doppler satellite navigation systems are examined, and the characteristics of existing and proposed satellite systems for maritime navigation are described. Particular attention is given to the COSPAS-SARSAT system, GPS/Navstar, and the Navsat, Granas, and Geostar projects. The features of shipboard navigation instruments are examined.

Bogdanov, Valerii Anatol'evich; Sorochinskii, Valentin Alekseevich; Iakshevich, Evgenii Viktorovich

71

Satellite systems for maritime navigation  

Microsoft Academic Search

The principles underlying the design of Doppler satellite navigation systems are examined, and the characteristics of existing and proposed satellite systems for maritime navigation are described. Particular attention is given to the COSPAS-SARSAT system, GPS\\/Navstar, and the Navsat, Granas, and Geostar projects. The features of shipboard navigation instruments are examined.

Valerii Anatol'evich Bogdanov; Valentin Alekseevich Sorochinskii; Evgenii Viktorovich Iakshevich

1987-01-01

72

Satellite observations of an ionospheric acceleration mechanism  

Microsoft Academic Search

A satellite-borne energetic ion mass spectrometer experiment has detected fluxes of O\\/sup +\\/ and H\\/sup +\\/ ions flowing up out of the ionosphere in the auroral and polar regions. The observed ions have energies in the keV range, narrow pitch-angle distributions aligned along the magnetic field direction and peak flux intensities of the order of 10āø (cmĀ²-sec-sterad-keV)ā»Ā¹. The observations were

E. G. Shelley; R. D. Sharp; R. G. Johnson

1976-01-01

73

Cloud observations from future Japanese satellite missions  

NASA Astrophysics Data System (ADS)

The paper presents the present status, scientific tentative results, plan of the future Japanese satellite missions related to the cloud sciences. There are three missions that will contribute to the cloud observations; GOSAT, EarthCARE, and GCOM-C (-W). Among the sensors aboard the satellites, we focus on the multi-spectral imagers. Each imager has different number of bands and observation swath according to the primary objectives. A principal aim of the CAI/GOSAT, for the cloud application, is providing the cloud screening to mitigate the uncertainty of CO2 retrieval by the FTS aboard the GOSAT. The MSI/EarthCARE will observe quasi-3D field of clouds together with active sensors, CPR and ATLID. The SGLI/GCOM-C, the follow-on mission of GLI/ADES-II, is the most precision imager among all Japanese future multi-spectral imagers. It has 19 bands from 380nm to 12?m, two of polarization bands.

Nakajima, Takashi Y.; Ishida, Haruma; Nakajima, Teruyuki; Shimoda, Haruhisa

2007-10-01

74

Globally Gridded Satellite observations for climate studies  

USGS Publications Warehouse

Geostationary satellites have provided routine, high temporal resolution Earth observations since the 1970s. Despite the long period of record, use of these data in climate studies has been limited for numerous reasons, among them that no central archive of geostationary data for all international satellites exists, full temporal and spatial resolution data are voluminous, and diverse calibration and navigation formats encumber the uniform processing needed for multisatellite climate studies. The International Satellite Cloud Climatology Project (ISCCP) set the stage for overcoming these issues by archiving a subset of the full-resolution geostationary data at ~10-km resolution at 3-hourly intervals since 1983. Recent efforts at NOAA's National Climatic Data Center to provide convenient access to these data include remapping the data to a standard map projection, recalibrating the data to optimize temporal homogeneity, extending the record of observations back to 1980, and reformatting the data for broad public distribution. The Gridded Satellite (GridSat) dataset includes observations from the visible, infrared window, and infrared water vapor channels. Data are stored in Network Common Data Format (netCDF) using standards that permit a wide variety of tools and libraries to process the data quickly and easily. A novel data layering approach, together with appropriate satellite and file metadata, allows users to access GridSat data at varying levels of complexity based on their needs. The result is a climate data record already in use by the meteorological community. Examples include reanalysis of tropical cyclones, studies of global precipitation, and detection and tracking of the intertropical convergence zone.

Knapp, K. R.; Ansari, S.; Bain, C. L.; Bourassa, M. A.; Dickinson, M. J.; Funk, C.; Helms, C. N.; Hennon, C. C.; Holmes, C. D.; Huffman, G. J.; Kossin, J. P.; Lee, H. -T.; Loew, A.; Magnusdottir, G.

2011-01-01

75

Comparison of high-level clouds represented in a global cloud system–resolving model with CALIPSO\\/CloudSat and geostationary satellite observations  

Microsoft Academic Search

Vertical and horizontal distributions of high-level clouds (ice and snow) simulated in high-resolution global cloud system–resolving simulations by the Nonhydrostatic Icosahedral Atmospheric Model (NICAM) are compared with satellite observations. Ice and snow data in a 1 week experiment by the NICAM 3.5 km grid mesh global simulation initiated at 0000 UTC 25 December 2006 are used in this study. The

Toshiro Inoue; Masaki Satoh; Yuichiro Hagihara; Hiroaki Miura; Johannes Schmetz

2010-01-01

76

Advanced Satellite Communication System.  

National Technical Information Service (NTIS)

The objective of this research program was to develop an innovative advanced satellite receiver/demodulator utilizing surface acoustic wave (SAW) chirp transform processor and coherent BPSK demodulation. The algorithm of this SAW chirp Fourier transformer...

E. J. Staples S. Lie

1992-01-01

77

Greenhouse Gases Observation from the GOSAT Satellite  

NASA Astrophysics Data System (ADS)

The Greenhouse gases Observing Satellite (GOSAT) is a satellite to monitor the carbon dioxide (CO2) and the methane (CH4) globally from orbit. The two instruments are accommodated on GOSAT. The Greenhouse gases Observing Sensor is a Fourier-Transform Spectrometer (FTS), which detects gas absorption spectra of the solar short wave infrared (SWIR) reflected on the earth_fs surface as well as of the thermal infrared (TIR) radiated from the ground and the atmosphere. The FTS is capable of detecting three narrow bands (0.76, 1.6, and 2 micron) and a wide band (5.5-14.3 micron) with 0.2 cm-1 spectral resolution. The cloud and aerosol sensor is an imager of ultraviolet (UV), visible, and SWIR to correct cloud and aerosol interference. The presentation includes the instrument design, pre-launch calibration and onboard calibration schemes; as well as, some test results using the Bread Board Model (BBM).

Kuze, A.; Kondo, K.; Kaneko, Y.; Hamazaki, T.

2005-12-01

78

The satellite configuration of satellite-TV navigation system  

NASA Astrophysics Data System (ADS)

The positioning accuracy and availability of navigation system are affected directly by the quality of satellite configuration. The possible satellite configurations for satellite-TV navigation system are discussed and estimated in this paper. The results show that a well setted configuration or a resonable integration of satellite-TV navigation system and Chinese Loran-C will improve the positioning accuracy and availability of the system.

Gao, Yu-Ping

2001-02-01

79

Lightning activity related to satellite and radar observations of a mesoscale convective system over Texas on 7 8 April 2002  

NASA Astrophysics Data System (ADS)

A multi-sensor study of the leading-line, trailing-stratiform (LLTS) mesoscale convective system (MCS) that developed over Texas in the afternoon of 7 April 2002 is presented. The analysis relies mainly on operationally available data sources such as GOES East satellite imagery, WSR-88D radar data and NLDN cloud-to-ground flash data. In addition, total lightning information in three dimensions from the LDAR II network in the Dallas Ft. Worth region is used. GOES East satellite imagery revealed several ring-like cloud top structures with a diameter of about 100 km during MCS formation. The Throckmorton tornadic supercell, which had formed just ahead of the developing linear MCS, was characterized by a high CG+ percentage below a V-shaped cloud top overshoot north of the tornado swath. There were indications of the presence of a tilted electrical dipole in this storm. Also this supercell had low average CG- first stroke currents and flash multiplicities. Interestingly, especially the average CG+ flash multiplicity in the Throckmorton storm showed oscillations with an estimated period of about 15 min. Later on, in the mature LLTS MCS, the radar versus lightning activity comparison revealed two dominant discharge regions at the back of the convective leading edge and a gentle descent of the upper intracloud lightning region into the trailing stratiform region, apparently coupled to hydrometeor sedimentation. There was evidence for an inverted dipole in the stratiform region of the LLTS MCS, and CG+ flashes from the stratiform region had high first return stroke peak currents.

Dotzek, Nikolai; Rabin, Robert M.; Carey, Lawrence D.; Macgorman, Donald R.; McCormick, Tracy L.; Demetriades, Nicholas W.; Murphy, Martin J.; Holle, Ronald L.

2005-07-01

80

QSAT: The Satellite for Polar Plasma Observation  

NASA Astrophysics Data System (ADS)

This paper introduces QSAT, the satellite for polar plasma observation. The QSAT project began in 2006 as an initiative by graduate students of Kyushu University, and has the potential to contribute greatly to IHY (International Heliophysical Year) by showing to the world the beauty, importance, and relevance of space science. The primary objectives of the QSAT mission are (1) to investigate plasma physics in the Earth’s aurora zone in order to better understand spacecraft charging, and (2) to conduct a comparison of the field-aligned current observed in orbit with ground-based observations. The QSAT project can provide education and research opportunities for students in an activity combining space sciences and satellite engineering. The QSAT satellite is designed to be launched in a piggyback fashion with the Japanese launch vehicle H-IIA. The spacecraft bus is being developed at the Department of Aeronautics and Astronautics of Kyushu University with collaboration of Fukuoka Institute of Technology. Regarding the payload instruments, the Space Environment Research Center of Kyushu University is developing the magnetometers, whereas the Laboratory of Spacecraft Environment Interaction Engineering of Kyushu Institute of Technology is developing the plasma probes. We aim to be ready for launch in 2009 or later.

Tsuruda, Yoshihiro; Fujimoto, Akiko; Kurahara, Naomi; Hanada, Toshiya; Yumoto, Kiyohumi; Cho, Mengu

2009-04-01

81

Land mobile satellite system requirements  

NASA Astrophysics Data System (ADS)

A Land Mobile Satellite System (LMSS) provides voice, data and related communications services to moving vehicles and persons. Communications between the mobiles and satellite are in the 806-890 MHz band. The satellite translates these signals to a ""fixed services band'' such as 14/12 GHz band (Ku-band), and communicates in this band with fixed terminals called gateways. The gateways are located at convenient places such as telephone switches (which provide entry into the national telephone system), dispatcher headquarters, computer centers, etc. Communications are therefore principally mobile to fixed. A third communications link, also at Ku-band, is needed between the satellite and a single fixed ground station. This link provides satellite command, telemetry and ranging and also provides a network control function. The latter, through a common signalling system, receives requests and assigns channel slots, and otherwise controls, monitors and polices the network and collects billing information.

Kiesling, J. D.

1983-05-01

82

Satellite observations of transionospheric pulse pairs  

SciTech Connect

The BLACKBEARD payload aboard the ALEXIS satellite has been making broadband observations in the VHF band of the radio spectrum. Since November of 1993 several hundred unusual signals have been recorded. The peculiar nature of these bursts of radio noise is that they have a duration of approximately 10 {mu}sec, are typically 20 to 40 dB brighter than the average background, and occur in pairs separated by approximately 50 {mu}sec. The authors have dubbed these emissions TransIonospheric Pulse Pairs, or TIPP events. They do not know what the source of these emissions is, but the dispersion of these signals is consistent with an origin at or near the earth`s surface. The satellite field of view and time of day when TIPP events are generally detected are consistent with regions of thunderstorm activity such as south-central Africa or Indonesia. 4 refs., 5 figs.

Holden, D.N.; Munson, C.P.; Devenport, J.C. [Los Alamos National Lab., NM (United States)

1995-04-15

83

CCD observations of saturnian satellites (Grosheva+, 2011)  

NASA Astrophysics Data System (ADS)

All observations were carried out with 26-inch Zeiss refractor(D=650mm, F=10413mm, scale is 19.80"/mm) at Pulkovo (code is 084). CCD camera FLI Pro Line 09000 (3056x3056pix) was used. Scale per pixel is 0.24" and field observed with this camera is 12'x12'. Time of exposures is 1.5s. All presented positions are topocentric. Ephemerides for comparison are given by web-server "Natural Satellites Ephemeride Server MULTI-SAT" developed by N.V. Emelyanov (http://lnfm1.sai.msu.ru/neb/nss/nssephmr.htm). (3 data files).

Grosheva, E. A.; Izmailov, I. S.; Kiseleva, T. P.

2011-10-01

84

Frequent Rain Observation From Geostationary Satellite  

NASA Astrophysics Data System (ADS)

The target 3-h observing cycle of GPM will meet requirements from Global NWP and, to a large extent, Regional NWP; and be supportive of VIS/IR-derived rain estimates from geostationary satellites for the purpose of Nowcasting. MW rain observation from geostationary orbit at, say, 15 min intervals, would fully meet Regional NWP requirements and have greatest impact on Nowcasting: but this implies either unprac- tically large antennas or unacceptably coarse resolution. Concepts to overcome this problem have been developed in the US within the study called GEM (Geostationary Microwave Observatory), and now there is in Europe a proposal for a demonstration satellite submitted to ESA as GOMAS (Geostationary Observatory for Microwave Atmospheric Sounding). To overcome the problem of resolution, use of Sub-mm fre- quencies is envisaged: e.g., at 425 GHz, a 10-km resolution at nadir would require a 3-m antenna. The observing principle is based on the use of absorption bands of oxygen (54, 118 and 425 GHz) and of water vapour (183 and 380 GHz). Narrow- bandwidths channels are implemented (for a total of about 40 in the five bands) so as to observe the full profile of temperature and water vapour. Profiles from different bands are differently affected by liquid and ice water of different drop size, and fi- nally by precipitation. Simultaneous retrieval of temperature/humidity profiles, cloud liquid/ice water (total-columns and gross profile) and precipitation rate is in principle possible, and partially demonstrated by several airborne MW/Sub-mm instruments. To transfer this demonstrations in the geostationary orbit, the problem of radiometric sensitivity (additional to that one of the antenna size) has to be solved. With current technology, it is feasible to get sufficient accuracy if scan is limited to about 1/12 of the Earth disk, which is sufficient to abundantly cover Europe, the Mediterranean and Eastern Atlantic. The imaged area can be moved everywhere within the disk, and the satellite itself can migrate along the equator to perform experiments from the Ameri- can continent to the Indian Ocean. As an example, the GOMAS concept (capitalising on the GEM concept) will be illustrated, for a relatively small satellite capable of ob- serving, each 15 min: temperature profile (30 km resolution), water vapour profile and cloud liquid/ice water total-columns or gross profile (20 km resolution), and precipita- tion rate (10 km resolution). Challenging aspects exist (e.g., active control of antenna deformations, simultaneous retrieval algorithm implying accurate cloud modelling, etc.), but it is felt that the satellite could be launched in the 2007-2009 timeframe.

Bizzarri, B.; Gomas Science Team

85

Navy Navigation Satellite System status  

NASA Astrophysics Data System (ADS)

It is pointed out that the Navy Navigation Satellite System (TRANSIT) provides a global basis for operational navigation and for Doppler surveying. TRANSIT is widely used throughout the U.S. Navy and by commercial shipping as a worldwide highly reliable and highly precise all-weather navigation system. The operational constellation contains currently six satellites. TRANSIT was developed to support the Polaris missile firing submarine and has been in continuous use by the U.S. Navy Strategic Systems Project Office since 1963. It was released for public use by Presidential directive in 1967. Attention is given to a systems overview, the operational satellite configuration, the Nova satellite configuration, the tracking network, and ionospheric refraction correction. The current status of TRANSIT is briefly examined. It is found that TRANSIT remains a reliable aid to all which utilize it.

Hoskins, G. W.

86

Trace gas assimilation of Mars satellite observations  

NASA Astrophysics Data System (ADS)

Ozone, water vapour and argon are minor constituents in the Martian atmosphere, observations of which can be of use in constraining atmospheric dynamical and physical processes. This is especially true in the winter season of each hemisphere, when the bulk of the main constituent in the atmosphere (CO2) condenses in the polar regions shifting the balance of atmospheric composition to a more trace gas rich air mass. Current Mars Global Circulation Models (MGCMs) [5, 7, 9] are able to represent the photochemistry occuring in the atmosphere, with constraints being imposed by comparisons with observations. However, a long term comparison using data assimilation provides a more robust constraint on the model. We aim to provide a technique for trace gas data assimilation for the analysis of observations from current and future satellite missions (such as ExoMars) which observe the spatial and temporal distribution of trace gases on Mars.

Holmes, J. A. M.; Lewis, S. R.; Patel, M. R.

2012-09-01

87

On the cloud observations in JAXA's next coming satellite missions  

NASA Astrophysics Data System (ADS)

The use of JAXA's next generation satellites, the EarthCARE and the GCOM-C, for observing overall cloud systems on the Earth is discussed. The satellites will be launched in the middle of 2010-era and contribute for observing aerosols and clouds in terms of climate change, environment, weather forecasting, and cloud revolution process study. This paper describes the role of such satellites and how to use the observing data showing concepts and some sample viewgraphs. Synergistic use of sensors is a key of the study. Visible to infrared bands are used for cloudy and clear discriminating from passively obtained satellite images. Cloud properties such as the cloud optical thickness, the effective particle radii, and the cloud top temperature will be retrieved from visible to infrared wavelengths of imagers. Additionally, we are going to combine cloud properties obtained from passive imagers and radar reflectivities obtained from an active radar in order to improve our understanding of cloud evolution process. This is one of the new techniques of satellite data analysis in terms of cloud sciences in the next decade. Since the climate change and cloud process study have mutual beneficial relationship, a multispectral wide-swath imagers like the GCOM-C SGLI and a comprehensive observation package of cloud and aerosol like the EarthCARE are both necessary.

Nakajima, Takashi Y.; Nagao, Takashi M.; Letu, Husi; Ishida, Haruma; Suzuki, Kentaroh

2012-11-01

88

Satellites  

SciTech Connect

The present work is based on a conference: Natural Satellites, Colloquium 77 of the IAU, held at Cornell University from July 5 to 9, 1983. Attention is given to the background and origins of satellites, protosatellite swarms, the tectonics of icy satellites, the physical characteristics of satellite surfaces, and the interactions of planetary magnetospheres with icy satellite surfaces. Other topics include the surface composition of natural satellites, the cratering of planetary satellites, the moon, Io, and Europa. Consideration is also given to Ganymede and Callisto, the satellites of Saturn, small satellites, satellites of Uranus and Neptune, and the Pluto-Charon system.

Burns, J.A.; Matthews, M.S.

1986-01-01

89

Remote sensing aerosols using satellite infrared observations  

NASA Astrophysics Data System (ADS)

Aerosol detection techniques using infrared wavelengths have a distinct advantage over visible techniques by providing coverage over bright surfaces and during the night. This study investigates detection of volcanic and soil-derived aerosols, two important aerosols in studies of the earth's climate, using infrared observations at the following approximate wavelengths 8.5, 11, and 12 ?m. Detection is based on brightness temperature differences among the three channels BT11-BT12 and BT8-BT11. It is demonstrated that these three infrared channels are useful for detecting stratospheric volcanic aerosols over oceans. Theoretical simulations agree with observations from current satellite instruments. Detection of the stratospheric aerosol over land is complicated by spectral variation of surface emissivity. Retrieving aerosol optical depth over land requires defining the surface spectral emittance. Detecting the presence of soil-derived aerosols can also be aided with infrared observations. Increasing the dust optical depth increases BT11-BT12 and BT8-BT11. The effect is opposite to that of an H2SO4 stratospheric aerosol and differs from an increase in atmospheric precipitable water, though addition of ice clouds moves the differences in the same direction. Retrievals of aerosol optical depth over the desert must account for surface emissivity and the vertical distribution of the dust. Negative differences in BT11-BT12 are observed to occur for dust storms over the Arabian Peninsula, Africa, and the southwest United States and is useful for remote sensing source regions of dust outbreaks. These negative differences can be simulated using the theoretical model but requires a specific dust aerosol model. There are inconsistencies between theoretical simulations of the infrared properties of heavy dust loadings and the satellite observations. Negative differences in BT11-BT12 are useful for detecting and tacking dust storms.

Ackerman, Steven A.

1997-07-01

90

Satellite observations of explosive volcanic eruptions  

NASA Astrophysics Data System (ADS)

Satellite data are used to study the explosive volcanic eruptions of El Chichon, Mt. Spurr, and Bezymianny volcanoes. The 1992 eruption of the Crater Peak vent of Mount Spurr, Alaska was investigated using Advanced Very High Resolution Radiometer (AVHRR) satellite data. Volcanic clouds generally have a negative AVHRR band 4 minus band 5 brightness temperature difference (BTD), while meteorological clouds generally have a positive BTD signal. Volcanic clouds imaged during and shortly after eruption are optically thick and can contain abundant water droplets and (or) ice, and these characteristics cause their spectral signal to closely resemble a meteorological cloud (e.g. positive BTD). As the volcanic cloud becomes translucent, the BTD signal changes, becoming negative first at the edge, and then throughout the entire cloud. The 1982 eruption of El Chichon, Mexico was observed using AVHRR image data and the Total Ozone Mapping Spectrometer (TOMS). Comparisons are presented of satellite retrievals from the AVHRR sensor, which detects and estimates the mass of fine grained volcanic ash, and the TOMS sensor, which detects and estimates the mass of sulfur dioxide, for three days following the two large eruptions on April 4, 1982. Analysis of the satellite imagery and wind data show that the main mass of volcanic ash moved east and south, at an altitude at or near the tropo-pause, while the main mass of sulfur dioxide moved to the west in the stratosphere. It is likely that the separation of volcanic ash and sulfur dioxide observed in the imagery is the result of vertical segregation of the two components, caused by the sedimentation of ash, and the subsequent dispersal by winds of different directions and (or) velocities. One of the primary public safety objectives of the Alaska Volcano Observatory (AVO) is to mitigate the hazard posed by volcanic ash clouds drifting into the busy North Pacific air traffic routes. A case study of the December 4, 1997 eruption of Bezymianny volcano, Russia, is used to illustrate how real-time remote sensing and hazard communication are used to mitigate the, threat of volcanic ash to aircraft. (Abstract shortened by UMI.)

Schneider, David Joseph

2000-10-01

91

Vision Autonomous Relative Navigation Algorithm for Distributed Micro\\/Nano Satellite Earth Observation System Based on Motor Algebra  

Microsoft Academic Search

Along with the development of space science and technology, it is not a heart-stirring thing to launch a satellite successfully any more. But we pay greatly attention to space autonomous rendezvous and docking (AR&D) in space operations, such as maintaining, assembling, attacking etc. And that autonomous relative position and pose is one of key technologies of these space actions. Currently,

Kezhao Li; Qinglin Wang; Qin Zhang; Chaoying Zhao

2009-01-01

92

A Comparison of Ground and Satellite Observations of Cloud Cover.  

NASA Astrophysics Data System (ADS)

A processing scheme that determines cloud height and amount based on radiances from the Visible Infrared Spin Scan Radiometer Atmospheric Sounder (VAS) using a CO2 absorption technique has been installed on the National Environmental Satellite Data and Information Service VAS Data Utilization Center computer system in Washington, D.C. The processed data will complement the Automated Surface Observing System (ASOS). ASOS uses automated ground equipment that provides near-continuous observations of surface weather data that are currently manually obtained. Geostationary multispectral infrared measurements are available every hour with information on clouds above the ASOS laser ceilometer viewing limit of 12 000 ft. The combined ASOS/satellite system will be able to depict cloud conditions at all levels up to 50 000 ft. The error rate of combined ASOS and satellite observations is less than 4% of the total sample in a comparison test with manual observations performed by National Weather Service personnel during March and April 1992. An attempt to distinguish thin from opaque clouds, by using a satellite-determined effective cloud amount, resulted in a substantial reduction in the discrepancies.

Schreiner, Anthony J.; Unger, David A.; Menzel, W. Paul; Ellrod, Gary P.; Strabala, Kathy I.; Pellet, Jackson L.

1993-10-01

93

A satellite failure database system  

Microsoft Academic Search

The authors describe a database, supported by various application programs, to provide easy and rapid access to satellite failure information. The basic system handles over 40 Mbytes of failure and hardware configuration information in a PC-based system. This system provides a user-friendly interface with good response time and sufficient flexibility in the search for information, and, to date, has proven

R. Neogy; C.-P. Siu

1988-01-01

94

Three-dimensional tropospheric water vapor in coupled climate models compared with observations from the AIRS satellite system  

Microsoft Academic Search

Changes in the distribution of water vapor in response to anthropogenic forcing will be a major factor determining the warming the Earth experiences over the next century, so it is important to validate climate models' distribution of water vapor. In this work the three-dimensional distribution of specific humidity in state-of-the-art climate models is compared to measurements from the AIRS satellite

David W. Pierce; Tim P. Barnett; Eric J. Fetzer; Peter J. Gleckler

2006-01-01

95

Global warming trend of mean tropospheric temperature observed by satellites.  

PubMed

We have analyzed the global tropospheric temperature for 1978 to 2002 with the use of passive microwave sounding data from the NOAA series of polar orbiters and the Earth Observing System Aqua satellite. To accurately retrieve the climatic trend, we combined the satellite data with an analytic model of temperature that contains three different time scales: a linear trend and functions that define the seasonal and diurnal cycles. Our analysis shows a trend of +0.22 degrees to 0.26 degrees C per 10 years, consistent with the global warming trend derived from surface meteorological stations. PMID:12970572

Vinnikov, Konstantin Y; Grody, Norman C

2003-09-11

96

Ground based and satellite observations of interactive double stars  

NASA Astrophysics Data System (ADS)

Observational data for interactive double star systems, from different spectral bands of the electromagnetic spectrum gathered from ground based and space born observatories, can be used for the determination of the physical parameters of the interactive double stars as well as the investigation of the interactions and the physical processes which take place in these double stars systems. The data bases from ground base and satellite observations for these systems provide light curves for thousands new double stars systems for which systematic observation of high accuracy may be done. In addition, in the frame of ground base and space born observational programs, it is expected that many new discovering of interesting double systems, including double systems of low mass stars as well as star-planet systems. In addition the most important ground base and space born, running or future, programs on interactive double stars systems are presented. (in Geeks)

Niarchos, P. G.

2013-01-01

97

Volcanic SO2 plume forecasts based on UV satellite observations  

NASA Astrophysics Data System (ADS)

We present how SO2 observations from satellites were used to facilitate forecasts of volcanic sulphur dioxide (SO2) plumes. Volcanic SO2 is often co-located with volcanic ash and can in many cases be considered as a proxy for volcanic ash. Satellite retrievals of SO2 total columns from GOME-2, OMI and SCIAMACHY for the eruptions of Grķmsvötn and Eyjafjallajökull in May 2011 and 2010 were inter-compared and used to (i) estimate source strength and injection height and (ii) to provide SO2 initial conditions for forecasts by means of data assimilation. The forecasts were carried out as an activity within the European MACC project (Monitoring of atmospheric composition and climate). MACC builds and runs a near-real-time system for the forecast of global atmospheric composition using the integrated forecast system of ECMWF. Our study found that OMI retrievals had the highest maximum values and that GOME-2 observations provided the most complete spatial coverage. Basic estimates of plume parameters were inferred from the satellite retrievals by finding the best match with an ensemble of plume forecasts injected at different levels. Further, the SO2 retrievals were assimilated with ECMWF's 4D-VAR algorithm to obtain initial conditions for the plume forecasts. These initialized plume forecasts were also used to validate the consistency of the satellite observations for consecutive days. The Grķmsvötn plume could mostly be predicted by the initialized forecasts, whereas the forecasts of the Eyjafjallajökull plume benefited more from the source term estimate.

Flemming, J.; Inness, A.

2012-04-01

98

Ozone Gravitywave Observations from the AIM Satellite  

NASA Astrophysics Data System (ADS)

The CIPS (Cloud Imaging and Particle Size) instrument aboard the newly launched AIM (Aeronomy of Ice in the Mesosphere) satellite has been analyzed for the presence of gravity waves in the observed albedo. AIM is in a sun synchronous orbit with an equatorial local time currently centered near noon. CIPS is a nadir viewing CCD imager with a field of view of approximately 2000 km along track and 1000 km across track. The pixel size at nadir is 2 km by 1 km. CIPS observes albedo at 265 nm. At this wavelength and in the absence of PMCs (Polar Mesospheric Clouds), variations in ozone densities in the 40 to 70 km altitude region dominate the deviations in albedo which would be expected from an unchanging atmosphere across the field of view. Under the assumption that ozone is the sole driver for the albedo structure observed, high resolution 2D ozone structure has been inferred from the images. Initial analysis has indicated that the principle scale of ozone structure is typically on the order of 1000km. Typical amplitudes are on the order of 2% (4% peak to trough) in ozone density.

Carstens, J. N.; Bailey, S. M.; Russell, J. M.; Rusch, D. W.; McClintock, W.; Thomas, G. E.; Taylor, M. J.; Randall, C.; Merkel, A. W.

2007-12-01

99

Monitoring vegetation using DOAS satellite observations  

NASA Astrophysics Data System (ADS)

Vegetation-cycles are of general interest for many applications. Be it for harvest-predictions, global monitoring of climate-change or as input to atmospheric models. From novel spectrally resolving UV/vis satellite instruments (like GOME or SCIAMACHY) the spectral signatures of different types of vegetation can be identified and analysed. Although the spatial resolution of GOME and SCIAMACHY observations is much coarser than those of conventional satellite instruments for vegetation monitoring, our data sets on different vegetation types add new and useful information, not obtainable from other sources. Common vegetation indices are based on the fact that the difference between Red and Near Infrared reflection is higher than in any other material on Earth's surface. This gives a very high degree of confidence for vegetation-detection. The spectrally resolving data from GOME and SCIAMACHY provide the chance to concentrate on finer spectral features throughout the red and near infrared spectrum. We look at these features using a technique known as Differential Optical Absorption Spectroscopy (DOAS). Although originally developed to retrieve information on trace gases, it can also be used to gain information on vegetation. Another advantage is that this method automatically corrects for atmospheric effects. This renders the vegetation-information easily comparable over long time-spans. In addition, high-frequency-structures from vegetation also effect the retrieval of tropospheric trace-gases and aerosols. To optimize vegetation monitoring with DOAS we produce spectrally resolved reference spectra from different vegetation types using our own instrumentation. We analyze the effect of different Pigments on high-frequency-structures of the DOAS Retrieval. Applying these results we investigate how well we can distinguish vegetation types from space.

Eigemeier, Ellen; Beirle, Steffen; Marbach, Thierry; Platt, Ulrich; Wagner, Thomas

2010-05-01

100

Modeling elves observed by FORMOSAT-2 satellite  

NASA Astrophysics Data System (ADS)

The ISUAL experiment on the FORMOSAT-2 satellite has confirmed the existence of ionization and Lyman-Birge-Hopfield (LBH) band emissions in elves. In this paper, an in-depth study of the ISUAL recorded elves was carried out. Numerical simulation results of elves based on an electromagnetic finite difference time domain (FDTD) model of the emissions between 185-800 nm and of their spatial-temporal evolution are presented. To account for the effect of atmospheric attenuation, three major attenuation mechanisms: O2, O3, and molecular Rayleigh scattering are considered. Validations of the electromagnetic FDTD model were conducted in three ways: by comparing the calculated and observed photon fluxes in the ISUAL spectrophotometric channels, by directly comparing the simulated and observed morphologies of elves, and by comparing the computed photon counts of the ISUAL Imager based on the derived peak currents for two elve-associated NLDN (National Lightning Detection Network) cloud-to-ground discharges (CGs) with those recorded by the ISUAL Imager. In all three ways, very good agreement was achieved.

Kuo, Cheng-Ling; Chen, A. B.; Lee, Y. J.; Tsai, L. Y.; Chou, R. K.; Hsu, R. R.; Su, H. T.; Lee, L. C.; Cummer, S. A.; Frey, H. U.; Mende, S. B.; Takahashi, Y.; Fukunishi, H.

2007-11-01

101

Tether satellite system collision study  

Microsoft Academic Search

A study was performed to determine the probability of collision with resident space objects and untrackable debris for the tether component of the Tethered Satellite System (TSS) after it broke away from the space shuttle orbiter (mission STS-75) in February 1996. Both an analytical and a numerical approach were used in this study, and the results obtained with these two

V. A. Chobotov; D. L. Mains

1999-01-01

102

Tether Satellite System Collision Study  

Microsoft Academic Search

A study was performed to determine the probability of collision with resident space objects and untrackable debris for the tether component of the Tethered Satellite System (TSS) after it broke away from the Space Shuttle orbiter (mission STS-75) in February 1996. Both an analytical and a numerical approach were used in this study, and the results obtained with these two

V. A. Chobotov; D. L. Mains

1999-01-01

103

Morelos Satellite System for Mexico  

NASA Astrophysics Data System (ADS)

The telephone, television, and data communication services that the Morelos Satellite System (MSS) provides are discussed. The design and functions of the MSS which consists of two geosynchronous communication satellites that operate in C and Ku frequency bands and are located at 113.5 deg and 116.5 deg W longitude are described. The capabilities of the antenna, communication, attitude control, telemetry, command, reaction control, electrical power, and thermal control subsystems are studied. The components of the earth station are examined. The economic and social benefits possible from the application of the MSS to banking, rural clinics, food distribution services, and the oil and electric industries are analyzed.

Sanchez Ruiz, M. E.

1986-03-01

104

The Mexican national satellite system  

NASA Astrophysics Data System (ADS)

The satellites, tracking, telemetry, command, and monitoring facilities, and the earth station complex for the Mexican national satellite system, Morelos, are described. The spacecraft are intended to provide educational television, rural telephony, data transmission, and business and industrial services. Scheduled for 1985 launch, the satellites will be placed in GEO and use the C and Ku bands with 12 narrow band and six wideband transponders. Spin-stabilized and solar cell powered, the functional mass will be 666 kg, including propellant. The solar panels will provide 940 W of power and 830 W will be available from NiCd batteries during eclipse conditions. The earth station will be located at Iztapalapa, which will have a 12 m antenna, redundant uplink and downlink radios, and command and ranging equipment. Back-up capability will be provided by a station at Tulancingo. Ku band and C band stations are in planning.

Sanchez Ruiz, M. E.; Briskman, R. D.

1983-10-01

105

Satellite Atmosphere and Io Torus Observations  

NASA Astrophysics Data System (ADS)

NASA's Planetary Astronomy Program has supported a vigorous three-year program of groundbased observations and detailed analysis of the Jupiter/Io system. Our work focused on Io's escaping atmosphere and the plasma torus that it creates.

Schneider, Nicholas

2004-01-01

106

Monitoring the Climate System with Satellites  

NSDL National Science Digital Library

The international science community has identified a set of Essential Climate Variables (ECVs) that should be monitored for measuring the climate system, how it is changing, and its likely impact on future climate. Environmental satellites play an important role in this effort. They are uniquely positioned to provide broad, spatially consistent, and continuous global sampling of many of the ECVs. This module explores the benefits of monitoring the climate system with satellites. We begin by reviewing how satellites observe key atmospheric elements and features that are found in a variety of climate cycles and are important for studying long-term climate trends. From there, we explore events at the different scales (from seasonal to long-term) and the contributions that satellites make to improving our understanding, monitoring, and prediction of them. Finally, we discuss the challenges involved in monitoring climate with satellites. Among these is the need for continuous, stable, high-resolution, and validated measurements that are coordinated with the worldās satellite operators.

Dills, Patrick

2012-01-11

107

Chaotic Dynamics of Satellite Systems  

NASA Astrophysics Data System (ADS)

We consider the problem of calculating the Lyapunov time (the characteristic time of predictable dynamics) of chaotic motion in the vicinity of separatrices of orbital resonances in satellite systems. The primary objects of study are the chaotic regimes that have occurred in the history of the orbital dynamics of the second and fifth Uranian satellites (Umbriel and Miranda) and the first and third Saturnian satellites (Mimas and Tethys). We study the dynamics in the vicinity of separatrices of the resonance multiplets corresponding to the 3 : 1 commensurability of mean motions of Miranda and Umbriel and the multiplets corresponding to the 2 : 1 commensurability of mean motions of Mimas and Tethys. These chaotic regimes have most probably contributed much to the long-term orbital evolution of the two satellite systems. The equations of motion have been numerically integrated to estimate the Lyapunov time in models corresponding to various epochs of the system evolution. Analytical estimates of the Lyapunov time have been obtained by a method (Shevchenko, 2002) based on the separatrix map theory. The analytical estimates have been compared to estimates obtained by direct numerical integration.

Mel'Nikov, A. V.; Shevchenko, I. I.

2005-07-01

108

Cloud Detection and Clearing for the Earth Observing System Terra Satellite Measurements of Pollution in the Troposphere (MOPITT) Experiment.  

PubMed

The Measurements of Pollution in the Troposphere (MOPITT) instrument, which was launched aboard the Earth Observing System (EOS) Terra spacecraft on 18 December 1999, is designed to measure tropospheric CO and CH(4) by use of a nadir-viewing geometry. The measurements are taken at 4.7 mum in the thermal emission and absorption for the CO mixing ratio profile retrieval and at 2.3 and 2.2 mum in the reflected solar region for the total CO column amount and CH(4) column amount retrieval, respectively. To achieve the required measurement accuracy, it is critical to identify and remove cloud contamination in the radiometric signals. We describe an algorithm to detect cloudy pixels, to reconstruct clear column radiance for pixels with partial cloud covers, and to estimate equivalent cloud top height for overcast conditions to allow CO profile retrievals above clouds. The MOPITT channel radiances, as well as the first-guess calculations, are simulated with a fast forward model with input atmospheric profiles from ancillary data sets. The precision of the retrieved CO profiles and total column amounts in cloudy atmospheres is within the expected ?10% range. Validations of the cloud-detecting thresholds with the moderate-resolution imaging spectroradiometer airborne simulator data and MOPITT airborne test radiometer measurements were performed. The validation results showed that the MOPITT cloud detection thresholds work well for scenes covered with more than 5-10% cloud cover if the uncertainties in the model input profiles are less than 2 K for temperature, 10% for water vapor, and 5% for CO and CH(4). PMID:18357114

Warner, J X; Gille, J C; Edwards, D P; Ziskin, D C; Smith, M W; Bailey, P L; Rokke, L

2001-03-10

109

Cloud microphysical properties as revealed by the CAIPEEX and satellite observations and evaluation of a cloud system resolving model simulation of contrasting large scale environments  

NASA Astrophysics Data System (ADS)

Clouds add the largest uncertainty in the current general circulation model. The numerical representation of clouds in the models can be improved by a better understanding of cloud processes in the tropics. This can be accomplished provided there is observational data at a good spatio-temporal resolution to capture the cloud scale processes. One such issue is addressed in the “Cloud-Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX)” over the Indian region during May-Sep, 2009. The objective of this paper is to bring out the microphysics of clouds during two contrasting days of Indian Summer Monsoon (ISM) based on the CAIPEEX data as well as on satellite observations over the region of Central India (CI). The paper also intends to study as to what extent the Weather Research and Forecasting (WRF) Model simulation at cloud system resolving grid (27-9-3 km) could capture the observed cloud types and properties. The rainfall observations on July 15 and August 18, 2009 suggest, respectively, an active and suppressed monsoon convection over central India. Upon analysis, it has been found that during an active or break phase of monsoon, significant heterogeneity exists in cloud distribution and types. The WRF simulation is able to capture some of the observed features of the cloud but could not simulate the middle and low level clouds. Thus a modification in cloud parameterization schemes may be helpful to improve the model biases, which in turn could improve the forecast of cloud life cycle vis-ą-vis precipitation.

Chakravarty, Kaustav; Mukhopadhyay, Parthasarathi; Taraphdar, Sourav

2011-08-01

110

Satellite observed preferential states in soil moisture  

NASA Astrophysics Data System (ADS)

This study presents observational evidence for the existence of preferential states in soil moisture content. Recently there has been much debate about the existence, location and explanations for preferential states in soil moisture. A number of studies have provided evidence either in support or against the hypothesis of a positive feedback mechanism between soil moisture and subsequent precipitation in certain regions. Researchers who support the hypothesis that preferential states in soil moisture holds information about land atmosphere feedback base their theory on the impact of soil moisture on the evaporation process. Evaporation recycles moisture to the atmosphere and soil moisture has a direct impact on the supply part of this process but also on the partitioning of the available energy for evaporation. According to this theory, the existence of soil moisture bimodality can be used as an indication of possible land-atmosphere feedbacks, to be compared with model simulations of soil moisture feedbacks. On the other hand, other researchers argue that seasonality in the meteorological conditions in combination with the non-linearity of soil moisture response alone can induce bimodality. In this study we estimate the soil moisture bimodality at a global scale as derived from the recently available 30+ year ESA Climate Change Initative satellite soil moisture dataset. An Expectation-Maximization iterative algorithm is used to find the best Gaussian Mixture Model, pursuing the highest likelihood for soil moisture bimodality. With this approach we mapped the regions where bi-modal probability distribution of soil moisture appears for each month for the period between 1979-2010. These bimodality areas are analyzed and compared to maps of model simulations of soil moisture feedbacks. The areas where more than one preferential state exists compare surprisingly well with the map of land-atmosphere coupling strength from model simulations. This approach might therefore be useful as an additional tool to further enhance our knowledge on land-atmosphere interactions.

Vilasa, Luis U.; De Jeu, Richard A. M.; Dolman, Han A. J.; Wang, Guojie

2013-04-01

111

Multimedia Systems Based on Satellite Technology  

Microsoft Academic Search

In this paper we review the evolution of satellite based multimedia systems. We focus especially on digital TV technology over satellite. This architecture takes advantage of the broadcasting capability of satellite systems to provide a low cost broadcast link towards a huge population of receivers. This ability makes the system especially suitable for the provision of multimedia services targeted to

Francisco Javier Ruiz Pińar; Angel Fernįndez; Carlos Miguel; Leon Vidaller; Antonio Mart??nez Mas; Juan Antonio Carral Pelayo

1998-01-01

112

Satellite Beacon Observations from 1964 to 1970.  

National Technical Information Service (NTIS)

From October 1964 to May 1969 the 40 MHz, 41 MHz, and 360 MHz signals of the satellite Explorer 22, were recorded at Lindau (51,650 deg N; 10,125 deg E). The Faraday effect recordings at 40 MHz and 41 MHz and dispersive Doppler effect recordings at 40 MHz...

G. K. Hartmann K. Oberlaender G. Schmidt J. P. Schoedel

1972-01-01

113

GPS-Based Satellite Tracking System for Precise Positioning  

Microsoft Academic Search

NASA is developing a Global Positioning System (GPS) based measurement system to provide precise determination of Earth satellite orbits, geodetic baselines, ionospheric electron content, and clock offsets between worldwide tracking sites. The system will employ variations on the differential GPS observing technique and will use a network of nine fixed ground terminals. Satellite applications will require either a GPS flight

THOMAS P. YUNCK; WILLIAM G. MELBOURNE; C. L. Thoenton

1985-01-01

114

Observations of iodine monoxide columns from satellite  

NASA Astrophysics Data System (ADS)

Iodine species in the troposphere are linked to ozone depletion and new particle formation. In this study, a full year of iodine monoxide (IO) columns retrieved from measurements of the SCIAMACHY satellite instrument is presented, coupled with a discussion of their uncertainties and the detection limits. The largest amounts of IO are found near springtime in the Antarctic. A seasonal variation of iodine monoxide in Antarctica is revealed with high values in springtime, slightly less IO in the summer period and again larger amounts in autumn. In winter, no elevated IO levels are found in the areas accessible to satellite measurements. This seasonal cycle is in good agreement with recent ground-based measurements in Antarctica. In the Arctic region, no elevated IO levels were found in the period analysed. This implies that different conditions with respect to iodine release exist in the two Polar Regions. To investigate possible release mechanisms, comparisons of IO columns with those of tropospheric BrO, and ice coverage are described and discussed. Some parallels and interesting differences between IO and BrO temporal and spatial distributions are identified. Overall, the large spatial coverage of satellite retrieved IO data and the availability of a long-term dataset provide new insight about the abundances and distributions of iodine compounds in the troposphere.

Schönhardt, A.; Richter, A.; Wittrock, F.; Kirk, H.; Oetjen, H.; Roscoe, H. K.; Burrows, J. P.

2008-02-01

115

Observations of mutual phenomena of Galilean's satellites at Catania  

NASA Astrophysics Data System (ADS)

The mutual phenomena between Jupiter and Saturn's satellites occur every half orbital period of these planets, when the Earth and the Sun cross their equatorial plane. At Physics and Astronomy Department of Catania University the events between Jupiter's satellites have been observed during the 1973, 1979, 1985/86, 1991, 1997 and 2009 campaigns and the ones between Saturn's satellites during the 1980/81 and 1995 campaigns. An overview of the main results obtained since 1973 is presented.

Fulvio, Daniele; Blanco, Carlo

2010-01-01

116

Co-ordination of satellite and data programs: The committee on earth observation satellites' approach  

NASA Astrophysics Data System (ADS)

Every year, an average of eight new civilian remote sensing satellite missions are launched. Cumulatively, over 250 such missions, each with a cost equivalent in current value to between US 100 million to US 1000 million, have been sponsored by space agencies in perhaps two dozen countries. These missions produce data and information products which are vital for informed decision making all over the world, on matters relating to natural resource exploitation, health and safety, sustainable national development, infrastructure planning, and a host of other applications. By contributing to better scientific understanding of global changes in the atmosphere, land surface, oceans and ice caps, these silently orbiting sentinels in the sky make it possible for governments and industries to make wiser environmental policy decisions and support the economic development needs of humanity. The international Committee on Earth Observation Satellites (CEOS) is the premier world body for co-ordinating and planning civilian satellite missions for Earth observation. Through its technical working groups and special task teams, it endeavours to: • maximise the international benefits from Earth observation satellites; and • harmonise practice in calibration, validation, data management and information systems for Earth observation. CEOS encompasses not only space agencies (data providers), but also the great international scientific and operational programs which rely on Earth science data from space. The user organisations affiliated with CEOS, together with the mission operators, attempt to reconcile user needs with the complex set of considerations — including national interests, cost, schedule — which affect the undertaking of space missions. Without such an internationally co-ordinated consensual approach, there is a much greater risk of waste through duplication, and of missed opportunity, or through the absence of measurements of some vital physical or biological parameter by space borne sensors. Mechanisms used by CEOS to carry out these tasks are built upon consensus and understanding, as well as on technology transfer between countries. An area of recent heightened endeavour in CEOS has been to determine and address the special needs of developing countries in respect of Earth observation data. In the next several years, a new wave of Earth observation will break, as the private sector, revitalised with decommissioned military technology, brings exciting new capabilities to international remote sensing. With rapidly burgeoning markets in spatial information or geomatics, as well as the continuing thirst of science programs for spatial information, there is a challenge upon the international space community to reassess continually, the most expedient and socially constructive means of making available in a fair and open way, geographically-reference information obtained with space observation systems.

Embleton, B. J. J.; Kingwell, J.

1997-01-01

117

Astrometry in the Uranian system of satellites  

NASA Astrophysics Data System (ADS)

The predicted occultation between the satellites Miranda(UV) and Oberon(UIV) was observed on July 30, 2007 using SpeX/IRTF system and CODAM-Paris Observatory facility. Data analysis reveals that the predicted magnitude drop for this phenomenon was overestimated and we establish an upper limit of 0m.05 for the phenomenon, perhaps due to a non-lambertian limb scattering. The astrometry obtained from this run reveals good agreement with the LA06 numerical model.

Birlan, Mirel; Nedelcu, Dan Alin

2008-09-01

118

Assessing the impact of satellite, aircraft, and surface observations on CO2 flux estimation using an ensemble-based 4-D data assimilation system  

NASA Astrophysics Data System (ADS)

The potential impacts of various types of CO2 concentration data obtained from surface, satellite (by the GOSAT project), and aircraft (by the CONTRAIL project) measurements on the estimation of surface CO2 fluxes have been investigated using an ensemble-based data assimilation approach. A four-dimensional ensemble Kalman filter with a 3 day assimilation window was used for analyzing surface fluxes of CO2 at every model grid point (horizontal resolution of 2.8°). Observation system simulation experiments have demonstrated a way to make efficient use of various observations and have shown that conventional surface network data contribute to large flux error reductions in the continental areas of the northern extratropics, while GOSAT XCO2 and CONTRAIL profile data provide strong additional constraints. The GOSAT data show a large error reduction over North and South America, South Africa, and temperate and boreal Asia, but the correction in tropical fluxes is lower than expected because of the poor data coverage caused by cloud abstraction. The CONTRAIL data provide large error reductions over Europe and tropical and temperate Asia. The assimilation of the upper tropospheric data gathered by CONTRAIL results in distinct error reductions over Siberia. By combining the information obtained from all the data sets, the global flux estimation is significantly improved. Meanwhile, many sources of error in the observations and the transport model strongly decrease the usefulness of each observation, and this can become a limiting factor in real data assimilation; for example, realistic systematic errors in the GOSAT data can reduce their usefulness by a factor of 2.

Miyazaki, Kazuyuki; Maki, Takashi; Patra, Prabir; Nakazawa, Takakiyo

2011-08-01

119

Improving National Air Quality Forecasts with Satellite Aerosol Observations.  

NASA Astrophysics Data System (ADS)

Accurate air quality forecasts can allow for mitigation of the health risks associated with high levels of air pollution. During September 2003, a team of NASA, NOAA, and EPA researchers demonstrated a prototype tool for improving fine particulate matter (PM2.5) air quality forecasts using satellite aerosol observations. Daily forecast products were generated from a near-real-time fusion of multiple input data products, including aerosol optical depth (AOD) from the Moderate Resolution Imaging Spectroradiometer (MODIS)/ Earth Observing System (EOS) instrument on the NASA Terra satellite, PM2.5 concentration from over 300 state/local/national surface monitoring stations, meteorological fields from the NOAA/NCEP Eta Model, and fire locations from the NOAA/National Environmental Satellite, Data, and Information Service (NESDIS) Geostationary Operational Environmental Satellite (GOES) Wildfire Automated Biomass Burning Algorithm (WF_ABBA) product. The products were disseminated via a Web interface to a small group of forecasters representing state and local air management agencies and the EPA. The MODIS data improved forecaster knowledge of synoptic-scale air pollution events, particularly over oceans and in regions devoid of surface monitors. Forecast trajectories initialized in regions of high AOD offered guidance for identifying potential episodes of poor air quality. The capability of this approach was illustrated with a case study showing that aerosol resulting from wildfires in the northwestern United States and southwestern Canada is transported across the continent to influence air quality in the Great Lakes region a few days later. The timing of this demonstration was selected to help improve the accuracy of the EPA's AIRNow (www.epa.gov/airnow/) air quality index next-day PM2.5 forecast, which began on 1 October 2003. Based on the positive response from air quality managers and forecasters, this prototype was expanded and transitioned to an operational provider during the summer of 2004.


Al-Saadi, Jassim; Szykman, James; Pierce, R. Bradley; Kittaka, Chieko; Neil, Doreen; Chu, D. Allen; Remer, Lorraine; Gumley, Liam; Prins, Elaine; Weinstock, Lewis; MacDonald, Clinton; Wayland, Richard; Dimmick, Fred; Fishman, Jack

2005-09-01

120

Tethered Satellite System Contingency Investigation Board  

NASA Astrophysics Data System (ADS)

The Tethered Satellite System (TSS-1) was launched aboard the Space Shuttle Atlantis (STS-46) on July 31, 1992. During the attempted on-orbit operations, the Tethered Satellite System failed to deploy successfully beyond 256 meters. The satellite was retrieved successfully and was returned on August 6, 1992. The National Aeronautics and Space Administration (NASA) Associate Administrator for Space Flight formed the Tethered Satellite System (TSS-1) Contingency Investigation Board on August 12, 1992. The TSS-1 Contingency Investigation Board was asked to review the anomalies which occurred, to determine the probable cause, and to recommend corrective measures to prevent recurrence. The board was supported by the TSS Systems Working group as identified in MSFC-TSS-11-90, 'Tethered Satellite System (TSS) Contingency Plan'. The board identified five anomalies for investigation: initial failure to retract the U2 umbilical; initial failure to flyaway; unplanned tether deployment stop at 179 meters; unplanned tether deployment stop at 256 meters; and failure to move tether in either direction at 224 meters. Initial observations of the returned flight hardware revealed evidence of mechanical interference by a bolt with the level wind mechanism travel as well as a helical shaped wrap of tether which indicated that the tether had been unwound from the reel beyond the travel by the level wind mechanism. Examination of the detailed mission events from flight data and mission logs related to the initial failure to flyaway and the failure to move in either direction at 224 meters, together with known preflight concerns regarding slack tether, focused the assessment of these anomalies on the upper tether control mechanism. After the second meeting, the board requested the working group to complete and validate a detailed integrated mission sequence to focus the fault tree analysis on a stuck U2 umbilical, level wind mechanical interference, and slack tether in upper tether control mechanism and to prepare a detailed plan for hardware inspection, test, and analysis including any appropriate hardware disassembly.

1992-11-01

121

Earth Observing System (EOS) Homepage  

NSDL National Science Digital Library

The Earth Observing System (EOS) consists of a series of Earth-observing satellites, a data system, and teams of scientists who will study the data. Educators can access a set of links to educational materials and publications, and real-time satellite tracking data. Other materials include mission profiles, information on the 24 measurements taken by EOS, research papers and reports, news articles, and others. A data services section provides access to datasets.

122

Advanced technologies for future environmental satellite systems  

NASA Astrophysics Data System (ADS)

Environmental satellites today are designed to meet the most requirements possible within the constraints of budget, reliability, availability, robustness, manufacturability, and the state of the art in affordable technology. As we learn more and more about observing and forecasting, requirements continue to be developed and validated for measurements that can benefit from for advances in technology. The goal is to incorporate new technologies into operational systems as quickly as possible. Technologies that exist or are being developed in response to growing requirements can be categorized as "requirements pull" whereas technologies rooted in basic research and engineering exploration fall in to a "technology push" category. NOAA has begun exploration into technologies for future NOAA satellite systems. Unmet requirements exist that drive the need to locate, explore, exploit, assess, and encourage development in several technologies. Areas needing advanced technologies include: atmospheric aerosols; cloud parameters; precipitation; profiles of temperature, moisture, pressure, and wind; atmospheric radiation; trace gas abundance and distribution; land surface; ocean surface; and space weather components such as neutral density and electron density. One of the more interesting ideas in the technology push category is a constellation of satellites at Medium Earth Orbit (MEO) altitudes, here described as circular orbits near 11,000 km altitude. Consider the vision of being able to observe the environment anywhere on the Earth, at anytime, with any repeat look frequency, and being able to communicate these measurements to anyone, anywhere, anytime, in real time. Studies suggest that a constellation of MEO satellites occupying equatorial and polar orbits (inclination = 90 degrees) could, in principle, accomplish this task. Also new on the horizon is solar sail technology. NOAA has been looking at solar sails as providing a propulsive system that could be used to maintain a satellite in a position closer to the Sun than L1. L1 is that point between the Earth and the sun where the gravitational forces of the Earth and the sun are equal. The sail would allow the increased gravitational force from the Sun to be balanced by the propulsive force of the solar sail. This capability could increase the lead-time for measuring and predicting the impact of solar events. Solar sails could also allow a satellite to be positioned over the Earth's polar regions continuously, filling a critical gap in current orbital observations and services. The combination of these technologies will enable the NOAA Satellites and Information Service to meet important requirements currently unmet and help satisfy NOAA strategic goals.

Dittberner, Gerald J.; Crison, Michael J.; Bajpai, Shyam; Diedrich, Benjamin L.

2004-09-01

123

GRB observed with RHESSI satellite (Ripa+, 2009)  

NASA Astrophysics Data System (ADS)

The Ramaty High Energy Solar Spectroscopic Imager (RHESSI) is a NASA Small Explorer satellite designed to study hard X-rays and gamma-rays from solar flares (Lin et al., 2002, Sol. Phys., 210, 3). We used the RHESSI GRB Catalog (Wigger et al., 2008, http://grb.web.psi.ch) and the Cosmic Burst List (Hurley, 2008, http://www.ssl.berkeley.edu/ipn3/masterli.html ) to detect 487 GRBs in the RHESSI data between 2002 February 14 and 2008 April 25. (1 data file).

Ripa, J.; Meszaros, A.; Wigger, C.; Huja, D.; Hudec, R.; Hajdas, W.

2009-06-01

124

Tracer Transport by the Diabatic Circulation Deduced from Satellite Observations  

Microsoft Academic Search

Mean meridional circulations for the months of November through May 1979 are deduced from the net radiative heating rates obtained from detailed calculations based on satellite observations of temperature and radiatively important trace species. The satellite data are also used to calculate the rates of photochemical processes that destroy the atmospheric tracers, methane and nitrous oxide. The deduced circulations along

S. Solomon; J. T. Kiehl; R. R. Garcia; W. Grose

1986-01-01

125

On classifying rain types using satellite microwave observations  

Microsoft Academic Search

Classification of rain type in satellite microwave observations is useful for various studies ranging from numerical weather prediction and precipitation climatology to satellite retrieval of rain amounts. In this study we have first examined the possibility of determining the distribution of convective\\/stratiform rain within a typical microwave radiometric pixel size area represented by the Tropical Rainfall Measuring Mission Microwave Imager

Atul Kumar Varma; Guosheng Liu

2010-01-01

126

The observation, detection and research on satellites of asteroids  

Microsoft Academic Search

Evidence is presented for the existence of asteroidal satellites. Instances wherein the occultation of a star occurred when a known asteroid was close to the line of sight of the star are discussed, and the implication that the eclipses were caused by satellites of the asteroids is considered. The role of amateur astronomers in these observations is reviewed, and possible

P. D. Maley

1980-01-01

127

Detection and orbit determination of tethered satellite systems  

NASA Astrophysics Data System (ADS)

A systematic algorithm for determining which satellites are tether-connected is described. It is assumed that observations in the forms of range, azimuth and elevation data, for several satellites, including singles, two-satellite tethered systems, and three-satellite tethered systems are available. The detection process is performed using the dynamic model and a minimum variance batch filter to process simulated observations over a period of ten minutes. In the process, the estimated acceleration per unit length between pairs of satellites due to a tether is assumed to be constant during this "short arc" observation period. The values of acceleration per unit length are used as indicators of which pairs of satellites are connected. Use of the algorithm is illustrated by applying it to a set of nine satellites that includes two tethered pairs. For small librational motion of the tethered pairs, values of the constraint accelerations per unit length that are large relative to zero were obtained. On the other hand, values very close to zero were obtained for un-tethered pairs. These results indicate that non-librating, two-satellite tethered systems can be successfully identified (i.e. "detected") when perfect and small-level noise corrupted observations are available. However, identification of two-satellite tethered systems with the large libration angle, or those with a very short tether when medium and large levels of noise are present is more difficult. The detection of a three-satellite tethered system was also performed with the same algorithm. After detection of a two-satellite tethered system (or three-satellite) is performed, its orbit may be determined by using long arcs of observations (over one orbital period). In the long arc estimation process used herein, the constraint acceleration per unit length is considered to be a time-varying variable. For an exemplary set of satellites, results for long arc estimations were obtained. Since observation data for both satellites in a tethered system were used and few approximations of the tether dynamics were made, the results are very accurate. The orbital motion of the three-satellite tether system was found to be similar to that of two-satellite tether system when the librational motion was small. The major difference was that larger tether accelerations were present due to another tether connected body. It should be relatively easy to incorporate the new method for detection and motion determination developed in this study into a general orbit determination process. (Abstract shortened by UMI.)

Choe, Nammi Jo

128

Future communication satellite systems and technology trends  

Microsoft Academic Search

Technological trends in communication satellite design and requirements were identified. The Intelsat program, TDR satellite systems, and the European large GEO platforms project were reviewed. There is a tendency towards modularized satellite buildup, large unfurlable lightweight multiple beam antennas 4 to 10 m for high frequencies (12 to 30 GHz) and up to larger than 100 m for lower frequencies,

H. Kellermeier; D. E. Koelle

1981-01-01

129

Developing a global aeronautical satellite system  

NASA Astrophysics Data System (ADS)

Arinc, an airline industry-owned and operated company in the United States, has taken steps toward establishing a global aeronautical satellite communications system. Plans call for initiation of a thin-route data operation in 1989, upgrading to establish voice communications via shared spot-beam transponders carried on other satellites, and deploying a worldwide network using dedicated satellites by 1994.

Dement, Donald K.

1988-05-01

130

Satellite observations of transient radio impulses from thunderstorms  

Microsoft Academic Search

Transient radio emissions from thunderstorms detected by satellites were first reported in 1995. The nature and source of these emissions remained a mystery until the launch of the FORTE satellite in 1997. FORTE, with its more sophisticated triggering and larger memory capacity showed that these emissions were connected to major thunderstorm systems. The analysis reported here, connecting FORTE RF events

P. E. Argo; M. Kirkland; A. Jacobson; R. Massey; D. Suszynsky; K. Eack; T. J. Fitzgerald; D. Smith

1999-01-01

131

Stability of Satellites in Closely Packed Planetary Systems  

NASA Astrophysics Data System (ADS)

We perform numerical integrations of four-body (star, planet, planet, satellite) systems to investigate the stability of satellites in planetary systems with tightly packed inner planets (STIPs). We find that the majority of closely spaced stable two-planet systems can stably support satellites across a range of parameter-space which is only slightly decreased compared to that seen for the single-planet case. In particular, circular prograde satellites remain stable out to ~0.4 RH (where RH is the Hill radius) as opposed to 0.5 RH in the single-planet case. A similarly small restriction in the stable parameter-space for retrograde satellites is observed, where planetary close approaches in the range 2.5-4.5 mutual Hill radii destabilize most satellites orbits only if a ~ 0.65 RH . In very close planetary pairs (e.g., the 12:11 resonance) the addition of a satellite frequently destabilizes the entire system, causing extreme close approaches and the loss of satellites over a range of circumplanetary semi-major axes. The majority of systems investigated stably harbored satellites over a wide parameter-space, suggesting that STIPs can generally offer a dynamically stable home for satellites, albeit with a slightly smaller stable parameter-space than the single-planet case. As we demonstrate that multi-planet systems are not a priori poor candidates for hosting satellites, future measurements of satellite occurrence rates in multi-planet systems versus single-planet systems could be used to constrain either satellite formation or past periods of strong dynamical interaction between planets.

Payne, Matthew J.; Deck, Katherine M.; Holman, Matthew J.; Perets, Hagai B.

2013-10-01

132

Global distribution of pauses observed with satellite measurements  

NASA Astrophysics Data System (ADS)

Several studies have been carried out on the tropopause, stratopause, and mesopause (collectively termed as `pauses') independently; however, all the pauses have not been studied together. We present global distribution of altitudes and temperatures of these pauses observed with long-term space borne high-resolution measurements of Global Positioning System (GPS) Radio Occultation (RO) and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) aboard Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite. Here we study the commonality and differences observed in the variability of all the pauses. We also examined how good other datasets will represent these features among (and in between) different satellite measurements, re-analysis, and model data. Hemispheric differences observed in all the pauses are also reported. In addition, we show that asymmetries between northern and southern hemispheres continue up to the mesopause. We analyze inter and intra-seasonal variations and long-term trends of these pauses at different latitudes. Finally, a new reference temperature profile is shown from the ground to 110 km for tropical, mid-latitudes, and polar latitudes for both northern and southern hemispheres.

Ratnam, M. Venkat; Kishore, P.; Velicogna, Isabella

2013-04-01

133

Analysis of stellar radiance contamination in observed satellite spectra  

NASA Astrophysics Data System (ADS)

Reflectance spectra of Earth orbiting satellites can be readily observed with small diameter telescopes (D < 1 m) by utilizing a method known as slitless spectroscopy. Satellite spectra can be observed by simply placing a transmission grating within the collimated optical path of the telescope without the need to image through a slit. The simplicity of the slitless spectroscopy design makes it a promising alternative to spatially resolving satellites with larger and more expensive diameter telescopes for applications of space situational awareness. However, accurately observing satellite re ectance spectra without imaging through a slit requires a dark and homogeneous background. This requirement is frequently violated as background stars streak across the image due to the slewing motion of the telescope during satellite tracking. Rather than throwing out all images with noticeable stellar contamination, a principle component analysis of contaminated images from three geostationary satellite observations showed that it may still be possible to assess and identify satellite characteristics depending upon the amount of stellar contamination in the spectral region of interest. Additionally, a simple technique for automatic removal of contaminated frames is proposed based on an outlier analysis using Gaussian statistics and was found to successfully remove all signicantly contaminated frames.

Vincent, R. Anthony; Chun, Francis K.; Dearborn, Michael E.; Tippets, Roger D.

2012-09-01

134

Autonomous satellite navigation methods using the Global Positioning Satellite System  

Microsoft Academic Search

This investigation considers the problem of autonomous satellite navigation using the NAVSTAR Global Positioning System (GPS). The major topics covered include the design, implementation, and validation of onboard navigation filter algorithms by means of computer simulations. The primary errors that the navigation filter design must minimize are computational effects and modeling inaccuracies due to limited capability of the onboard computer.

M. Murata; B. D. Tapley; B. E. Schutz

1982-01-01

135

Perl Tools for Automating Satellite Ground Systems  

Microsoft Academic Search

The freeware scripting language Perl offers many opportunities for automating satellite ground systems for new satellites as well as older, in situ systems. This paper describes a toolkit that has evolved from of the experiences gained by using Perl to automate the ground system for the Compton Gamma Ray Observatory (CGRO) and for automating some of the elements in the

David McLean; Therese Haar; James McDonald

136

Maritime and Aeronautical Satellite Navigation Systems  

Microsoft Academic Search

This paper inciudes a brief survey of the generic types of radio navigation aids, including satellite navigation; then a more detailed review of the TRANSIT and NAVSTAR systems, thus encompassing the principal developmental and operational satellite navigation systems. The precision and accuracy of these systems, their basic operating characteristics, and the ancillary equipment required for their operations will be covered.

J. Litton

1977-01-01

137

Remote sensing aerosols using satellite infrared observations  

Microsoft Academic Search

Aerosol detection techniques using infrared wavelengths have a distinct advantage over visible techniques by providing coverage over bright surfaces and during the night. This study investigates detection of volcanic and soil-derived aerosols, two important aerosols in studies of the earth's climate, using infrared observations at the following approximate wavelengths 8.5, 11, and 12 mum. Detection is based on brightness temperature

Steven A. Ackerman

1997-01-01

138

Remote sensing aerosols using satellite infrared observations  

Microsoft Academic Search

Aerosol detection techniques using infrared wavelengths have a distinct advantage over visible techniques by providing coverage over bright surfaces and during the night. This study investigates detection of volcanic and soil- derived aerosols, two important aerosols in studies of the earth's climate, using infrared observations at the following approximate wavelengths 8.5, 11, and 12\\/m. Detection is based on brightness temperature

Steven A. Ackerman

1997-01-01

139

Recent state of the Aral sea from regular satellite observations.  

NASA Astrophysics Data System (ADS)

The Aral Sea disaster is one of the most significant examples of ecological catastrophe caused by mismanagement of water resources. Aral sea level dropped on 22 meters for the last 35 years. The sea separated in to two independent parts , the Large Sea(Southern) and the Small Sea (Northern), loosing more than 90% of its original water masses. After the collapse of the former Soviet Union, satellite retrieved data became the main source of information on this perishing system. Regular observations from AVHRR, SeaWiFS, MODIS and ASTER satellite sensors were used for our investigations. Sea surface temperature (SST) data of the AVHRR sensor and digital bottom map topography were used for sea level drop calculations. The Sea level defined as the digital map isobate corresponds quite well to the satellite derived coastline for the Eastern part of the Large Sea with a bottom slope of ˜ 0.00015. For the period 1989-2002 the sea level of the Large Sea dropped on 9.2 meters. However in 2003 the sea level remained stable. This stabilisation was due to an increase of water output of the rivers Amu--Darya and Syr-Darya in 2003. High resolution ASTER data showed that the main amount of Syr-Darya waters is discharged into the Large Sea. The dried bottom area now covers more than 45000 km2. On the base of AVHRR-SST data the temperature regime for different parts of the Aral Sea was calculated for the years 2002-2003. The annual amplitude of the SST variation reaches 37° C for the open waters. The observed minimum freezing point was -7° C due to very high salinity. Estimations from satellite retrieved freezing points show an increase of salinity up to 10% in the Eastern part of the Large Sea. It is almost paradox that on satellite images the ice appears warmer than the water. Strong variations of the water temperature (up to 5° C) within a few days could be observed from April to August and could be related to wind induced mixing. SeaWiFS ocean colour data were used for the investigation of the optical properties of the water in different parts of the Aral Sea for the years 2002-2003. A significant relation of optical properties with wind and temperature was obtained. Strong changes of the thermal regimes of the Sea can cause variations in local climatic conditions: The analysis of AVHRR NDVI - data for the surrounding areas demonstrated a shift in the annual vegetation cycle. In addition phenomena like: salt storms, wind driven tides, sources of groundwater, eddies and frontal structures as well as ice coverage of the Aral Sea were demonstrated on satellite images.

Stanichny, S.; Davidov, A.; Djenidi, S.; Horstmann, U.; Stanichnaya, R.; Soloviev, D.

140

Time Management System for Satellite Positioning System using Quasi-Zenith Satellites  

Microsoft Academic Search

The first Japanese Quasi-Zenith satellite (QZS) will be launched FY 2008. The QZS System (QZSS) is studied as an integrated satellite service system for communications, broadcasting, and positioning for mobile users in throughout specified regions in Japan from a high angle of elevation. The purpose of the satellite positioning system using QZS is to complement and augment the GPS. The

Y. Takahashi; M. Fujieda; J. Amagai; S. Yokota; K. Kimura; S. Hama; I. Kawano; S. Kogure

141

Pert Tools for Automating Satellite Ground Systems.  

National Technical Information Service (NTIS)

The freeware scripting language Pert offers many opportunities for automating satellite ground systems for new satellites as well as older, in situ systems. This paper describes a toolkit that has evolved from of the experiences gained by using Pert to au...

D. McLean T. Haar J. McDonald

2000-01-01

142

The Public Broadcasting Satellite Interconnection System.  

ERIC Educational Resources Information Center

A satellite system to interconnect the Public Broadcasting Service (PBS) and 165 public television stations (PTV) is planned to replace the present terrestrial system. Stations are located on and outside of the United States mainland. Advantages offered by satellite are: (1) equal cost of program originations from points close to and remote from…

Ball, John E. D.

143

Research on Complicated Imaging Condition of GEO Optical High Resolution Earth Observing Satellite  

NASA Astrophysics Data System (ADS)

The requirement for high time and space resolution of optical remote sensing satellite in disaster, land resources, environment, marine monitoring and meteorology observation, etc is getting urgent and strict. For that reason, a remote sensing satellite system solely located in MEO or LEO cannot operate continuous observation and Surveillance. GEO optical high resolution earth observing satellite in the other hand can keep the mesoscale and microscale target under continuous surveillance by controlling line of sight(LOS), and can provide imaging observation of an extensive region in a short time. The advantages of GEO satellite such as real-time observation of the mesoscale and microscale target, rapid response of key events, have been recognized by lots of countries and become a new trend of remote sensing satellite. As many advantages as the GEO remote sensing satellite has, its imaging condition is more complicated. Many new characteristics of imaging observation and imaging quality need to be discussed. We analyze each factor in the remote sensing link, using theoretical analysis and modeling simulation to get coefficient of each factor to represent its effect on imaging system. Such research achievements can provide reference for satellite mission analysis and system design.

Guo, Linghua

2012-07-01

144

Ground and satellite observations of substorm onset arcs  

NASA Astrophysics Data System (ADS)

Auroral features and associated particles and fields are investigated for a sequence of substorm onsets observed at ˜1900 MLT on 24 October 2000. During a 30-min interval at 1020-1050 UT, we identified three Pi 2 wave packets with positive H enhancements at midlatitudes and associated auroral brightenings in auroral images obtained by a ground all-sky camera and the IMAGE FUV imager. The DMSP F15 satellite crossed brightening arcs during the third Pi 2 pulsation in the field-of-view of the ground camera at Tixie (66.0° MLAT), Russia. The crossing was 1-2 hours duskside of the main onset local time. The brightening arcs were located in the region 1 upward field-aligned current system. The most equatorward arc, which brightened just after the second Pi 2 pulsation, was at the equatorward boundary of the region 1 current and in the sunward convection region. The arcs corresponded to inverted-V accelerated electrons with energies of ˜10 keV. On the basis of these simultaneous ground-satellite measurements, we discuss substorm onset models of reconnection/flow braking and near-Earth plasma sheet instabilities.

Shiokawa, K.; Yago, K.; Yumoto, K.; Baishev, D. G.; Solovyev, S. I.; Rich, F. J.; Mende, S. B.

2005-12-01

145

Polar Airborne Observations Fill Gap in Satellite Data  

NASA Astrophysics Data System (ADS)

In October 2009, NASA's Ice, Cloud, and land Elevation Satellite (ICESat) stopped collecting science data. However, noting the progressive degradation of ICESat's Geoscience Laser Altimeter System (GLAS), NASA had begun the previous year to plan a series of instrumented aircraft missions to fill the impending gap in satellite observations due to the loss of GLAS. Called Operation IceBridge, the project has been collecting data since March 2009 and will continue until the scheduled launch of ICESat's replacement, ICESat-2, in about 2015. The primary goal of IceBridge is to use airborne laser altimetry to monitor rapidly changing areas of ice sheets, glaciers, and sea ice; a secondary goal is to acquire ice-penetrating-radar data to map the bedrock topography beneath the ice sheets. Data collected by IceBridge will yield a three-dimensional view of ice sheets and sea ice as they change. IceBridge will improve modeling efforts and knowledge of the contribution of the Greenland and Antarctic ice sheets to sea level rise. The project will also contribute to scientific understanding of changes in the extent and thickness of the sea ice cover as the planet warms. IceBridge flights maintain altimetry time series over outlet glaciers started by NASA in the early 1990s, expand airborne altimeter coverage to new areas, and add grids of ice-penetrating-radar data to better resolve bedrock topography.

Koenig, Lora; Martin, Seelye; Studinger, Michael; Sonntag, John

2010-09-01

146

Small satellite radiometric measurement system  

SciTech Connect

A critical need for the US Global Change Research Program is to provide continuous, well-calibrated radiometric data for the earth's radiation budget. This paper describes a new, compact, relatively light-weight, adaptable radiometer which will provide both spectrally integrated measurements and data in selected spectral bands. The radiometer design is suitable for use on small satellites, aircraft, or remotely piloted aircraft (RPAs). An example of the implementation of this radiometer on a small satellite is given. Significant benefits derive from simultaneous measurements of specific narrow (in wavelength) spectral features; such data may be obtained by combining LARI with a compact spectrometer on the same platform. Well-chosen satellite orbits allow one to use data from other satellites (e.g. DMSP) to enhance the data product, or to provide superior coverage of specific locations. 23 refs.

Weber, P.G.

1992-01-01

147

Small satellite radiometric measurement system  

SciTech Connect

A critical need for the US Global Change Research Program is to provide continuous, well-calibrated radiometric data for the earth`s radiation budget. This paper describes a new, compact, relatively light-weight, adaptable radiometer which will provide both spectrally integrated measurements and data in selected spectral bands. The radiometer design is suitable for use on small satellites, aircraft, or remotely piloted aircraft (RPAs). An example of the implementation of this radiometer on a small satellite is given. Significant benefits derive from simultaneous measurements of specific narrow (in wavelength) spectral features; such data may be obtained by combining LARI with a compact spectrometer on the same platform. Well-chosen satellite orbits allow one to use data from other satellites (e.g. DMSP) to enhance the data product, or to provide superior coverage of specific locations. 23 refs.

Weber, P.G.

1992-01-01

148

A review of satellite observations of atmospheric ozone  

NASA Astrophysics Data System (ADS)

This paper overviews the development of the satellite ozone methodology since about 1980, with emphasis on the solar backscattered UV technique, the IR emission technique, and the solar occultation technique. The instruments used in these methods are discussed with special consideration given to the error estimates of the instruments. Future measurement systems are discussed with particualr attention given to the ten instruments and their primary measurements planned for the Upper Atmosphere Research Satellite which will be launched in about 1991.

Miller, Alvin J.

1989-12-01

149

Special program of observations of Jovian and Saturnian satellites for 2009  

NASA Astrophysics Data System (ADS)

Noteworthy phenomena, viz., mutual occultations and eclipses in the system of Jupiter’s Galilean satellites and in the system of Saturn’s principal satellites, will occur in 2009. The relatively simple photometry of these phenomena makes it possible to obtain positional data at a higher accuracy than can be achieved in regular astrometric observations. The visibility conditions for the satellites are described here and observational recommendations are given. The ephemerides of these phenomena are available via the Internet from the MULTI-SAT ephemerides server at http:/www.sai.msu.ru/neb/nss/index.htm.

Emel'Yanov, N. V.

2008-10-01

150

Case study - Australian national satellite system  

NASA Astrophysics Data System (ADS)

This paper provides background information on a number of aspects of the decision to proceed to develop an Australian national satellite system, and on the system design. Relevant information includes the Australian geography, climate, and population distribution, the terrestrial telecommunications system, and the broadcasting scene in Australia. The main services to be carried via the satellite system are described, together with the details of the system design against which tenders were called.

Johnson, R. C.

151

Satellite Television Corporations's DBS system - An update  

NASA Astrophysics Data System (ADS)

In late 1980, a request was made for approval of a direct broadcast satellite (DBS) system. The considered DBS system is to provide nationwide pay-television service on a subscription basis. The system proposed in the application to the Federal Communications Commission would provide three channels of television, using four three-channel satellites. Attention is given to the system configuration, system tradeoffs, a plan of the 1983 Regional Administrative Radio Conference, orbit locations and channel frequencies, satellite status, home equipment status, advanced concepts, and the status of the Las Vegas Broadcast Complex. AIAA Paper 84-0664

Martin, E. R.

152

Satellite observations of Schumann resonances in the Earth's ionosphere  

NASA Astrophysics Data System (ADS)

Using electric field measurements gathered on the C/NOFS satellite, we report, Schumann resonance signatures detected in space, well beyond the upper boundary of the resonant cavity formed by the earth's surface and the lower edge of the ionosphere. The resonances are routinely observed in the satellite ELF data during nighttime conditions within the altitude region of 400-850 km sampled by the satellite. They exhibit the distinctive frequency patterns predicted for Schumann resonances and are consistent with the corresponding frequency characteristics of ground-based observations of this phenomenon. The observations of Schumann resonances in space support a leaky cavity interpretation of the ionosphere and call for revisions of models of extremely low frequency wave propagation in the ionosphere. They suggest new remote sensing capabilities for investigating atmospheric electricity on Earth and other planets.

Simões, Fernando; Pfaff, Robert; Freudenreich, Henry

2011-11-01

153

Satellite systems for Latin American telecommunication requirements  

NASA Astrophysics Data System (ADS)

Aspects of satellite telecommunications systems of interest to Latin America are discussed. Presently existing systems are described, including both state-run and international services. Services planned for the region are examined, including Geostar, a service that provides satellite radio determination and message services, a system which will provide a high-capacity digital voice and data service for airlines, and direct broadcast satellites. Applications of these systems in education, rural telephony, data transmission, news services, publishing, emergency communications, and mobile communications are addressed.

Elizondo, Eduardo L.

154

Ionospheric effects on satellite land mobile systems  

Microsoft Academic Search

Satellite-ground radio systems are now so sensitive that ionospheric changes can disrupt their performance. This paper discusses some satellite-to-ground propagation problems in the UHF and L bands caused by the Earth's ionosphere. Such problems include signal time delay, signal dispersion, Faraday rotation, and scintillation.

Kenneth Davies; Ernest K. Smith

2002-01-01

155

REPORT ON SATELLITE AND SPACE PROPULSION SYSTEMS  

Microsoft Academic Search

Low-thrust propulsion systems that can be used to extend satellite ; orbits, to control or modify satellite orbits, and for lunar and interplanetary ; exploration are surveyed. The most feasible combinations of energy sources ; (chemicals, radioisotopes, solar rays, nuclear fission, and nuclear fusion), ; electric generators (chemical batteries, radioisotope batteries, thermopiles, ; solar batteries, turboelectric generators, and plasma induction),

Partel

1962-01-01

156

Plan of Time Management of Satellite Positioning System using Quasi-zenith Satellite  

Microsoft Academic Search

The Quasi-Zenith satellites System (QZSS) is developed as an integrated satellite service system of communication, broadcasting and positioning for mobile users in specified regions of Japan from high elevation angle. Purposes of the satellite positioning system using Quasi-Zenith satellite (QZS) are to complement and augment the GPS. The national institutes concerned have been developing the positioning system using QZS since

Yasuhiro Takahashi; Miho Fujieda; Jun Amagai; Shoichiro Yokota; Kazuhiro Kimura; Hiroyuki Ito; Shin'ichi Hama; Takao Morikawa; Isao Kawano; Satoshi Kogure

2005-01-01

157

Upper Atmosphere Research Satellite observations of a Pi2 pulsation  

NASA Astrophysics Data System (ADS)

Satellites in low-altitude orbits provide unique opportunities to study the ionospheric screening effects on ULF waves propagating from the magnetosphere. This paper presents the first report of observation of a Pi2 pulsation from the Upper Atmosphere Research Satellite (UARS) at an altitude of ~580 km. The Pi2 pulsation occurred on November 18, 1993, when the satellite was over the Pacific near the three ground magnetometer sites, Chichijima (L=1.14, MLT=23), Ewa Beach (L=1.17, MLT=03), and Guam (L=1.07, MLT=23). On the ground the Pi2 was visible in the H (northward) component from 1337 to 1343 UT at all locations with the same period of 43 s but with an amplitude ranging from 2.1 nT (Guam) to 0.6 nT (Ewa Beach). At the satellite the same pulsation was detected in the H component with an amplitude of 1.7 nT. The transverse radial component and the parallel component at the satellite oscillated in phase, consistent with previous Active Magnetospheric Particle Tracer Explorers Charge Composition Explorer observations at L>2. When the ground signals are linearly interpolated to the geographic longitude and latitude of UARS, the orientation of the major axis of polarization agreed well with that observed by UARS, as is expected for a fastmode wave propagating through the ionosphere.

Takahashi, Kazue; Anderson, Brian J.; Yumoto, Kiyohumi

1999-11-01

158

Satellite-to-Satellite Tracking Study for the Global Positioning System (Rotating-Y Configuration).  

National Technical Information Service (NTIS)

A global satellite positioning system is evaluated. The methods and techniques involved in satellite-to-satellite tracking to determine orbital accuracies are described, and results of these accuracies are presented. The positional accuracy of ground user...

E. Simental

1974-01-01

159

Small satellite radiometric measurement system  

SciTech Connect

The Los Alamos Radiometric Instrument (LARI) is a compact, lightweight, adaptable radiometer for climate change-related measurements which could be carried by small satellites, manned aircraft, and RPVs for remote sensing. LARI can furnish both spectrally-integrated measurements and data in selected spectral bands. Attention is given to the benefits derived from the simultaneous operation of LARI with a compact spectrometer. The basic LARI package can be inserted into orbit with the Pegasus air-launched vehicle; well-chosen orbits facilitate the use of data from other satellites to enhance data products. 23 refs.

Weber, P.G. (Los Alamos National Laboratory, NM (United States))

1992-03-01

160

Solar System Observations with NHST  

Microsoft Academic Search

Solar system observations using HST have been tremendously successful in many scientific areas, taking advantage of the wealth of information from high angular resolution images and high sensitivity UV to IR spectra. These capabilities have led to major advances in the areas of planetary atmospheres, surfaces, aurora and magnetospheres, and planetary satellites. While solar system objects are normally considered to

J. T. Clarke

2003-01-01

161

Can oceanic submesoscale processes be observed with satellite altimetry?  

NASA Astrophysics Data System (ADS)

High-resolution (2 km and hourly) observations of surface currents from High-Frequency Radars are analyzed in terms of sea level anomalies (SLA) and compared with data from two satellite altimeter ground tracks. Purpose is to investigate whether ocean submesoscale processes can be observed with satellite altimetry. Our results highlight two major problems that must be overcome before being able to resolve submesoscale processes with altimetry: (i) signal contamination from high-frequency motions and in particular from incoherent internal tides (near-inertial oscillations have no effect on SLA), and (ii) measurement noise which prevents the computation of accurate cross-track currents on scales $\\cal{O (10 km). The latter may be overcome by future satellite altimeter missions, but the former will require taking into account the effect of mesoscale variability on internal tide propagation in regions where internal tides are significant.

Chavanne, Cédric P.; Klein, Patrice

2010-11-01

162

Satellite observations of aerosol and CO over Mexico City  

NASA Astrophysics Data System (ADS)

The development of remote sensing satellite technology potentially will lead to the technical means to monitor air pollution emitted from large cities on a global basis. This paper presents observations by the moderate resolution imaging spectroradiometer (MODIS) and measurements of pollution in the troposphere (MOPITT) experiments of aerosol optical depths and CO mixing ratios, respectively, in the vicinity of Mexico City to illustrate current satellite capabilities. MOPITT CO mixing ratios over Mexico City, averaged between January-March 2002-2005, are 19% above regional values and the CO plume extends over 10° 2 in the free troposphere at 500 hPa. Time series of Red Automatica de Monitoreo Ambiental (RAMA) PM10, and (Aerosol Robotic Network) AERONET and MODIS aerosol optical depths, and RAMA and MOPITT CO time series are inter-compared to illustrate the different perspectives of ground based and satellite instrumentation. Finally, we demonstrate, by examining MODIS and MOPITT data in April 2003, that satellite data can be used to identify episodes in which pollution form fires influences the time series of ground based and satellite observations of urban pollution.

Massie, Steven T.; Gille, John C.; Edwards, David P.; Nandi, Sreela

163

Combined Satellite- and Surface-Based Observations of Clouds.  

NASA Astrophysics Data System (ADS)

A new method for combining satellite and surface-based cloud observations into a self-consistent three-dimensional field is presented. This method derives the probabilities of the cloud states, which are most consistent with all of the observations and assumptions concerning the nature and relative uncertainties of the observations. It is applied to a three-layer atmosphere using monthly satellite- and surface-based cloud observations. The reconstructions of the observed fields usually lead to modifications of the surface-observed low cloud amount of less than 0.008 fractional cloud cover. Over the ocean the satellite-view low cloud amounts are usually decreased by between 0.06 and 0.12 for most of the middle latitudes and southeastern tropical Pacific. Over land the adjustments in the satellite low cloud amounts are generally smaller. The method leads to increases in satellite high cover of between 0.03 and 0.09 over most regions, and increases in middle cloud cover of up to around 0.03 over the subtropical oceans. Comparisons between derived total cloud cover and that calculated with the commonly used random and mixed overlap assumptions suggest that the mixed assumption generally better fits the results. On the whole there is overall fairly good agreement between the percent low cloud relative to total cloud cover in the reconstructed observations and a global climate model, but the model has a far larger percentage of high clouds nearly everywhere, especially in the tropical convective regions and over the Indian subcontinent.

Weare, Bryan C.

1999-03-01

164

Telesat Canada's mobile satellite system  

Microsoft Academic Search

Telesat Canada plans to begin instituting mobile satellite ('Msat') services in the early 1990s, in order to permit voice and data communications between land vehicles, aircraft, and ships throughout the remote northern regions and the 200-mile offshore regions of Canada and any other point on Canadian territory. An account is presently given of Msat's overall configuration and projected capacity, together

E. Bertenyi; M. Wachira

1987-01-01

165

Optical System in Laser Inter-Satellites Communication  

Microsoft Academic Search

We know that Inter-satellites communication is a very important to us. However, real global coverage can only be achieved by satellite systems. Satellites communication is the most important mean of the communication network. The traditional satellites communication and inter-satellites links are built by microwave. Recent years, laser links for inter-satellites communication are becoming more and more important.

Zhou Li; Wen Chuanhua; Liu Baoming

2008-01-01

166

CORRECTING PHOTOLYSIS RATES ON THE BASIS OF SATELLITE OBSERVED CLOUDS  

EPA Science Inventory

Clouds can significantly affect photochemical activities in the boundary layer by altering radiation intensity, and therefore their correct specification in the air quality models is of outmost importance. In this study we introduce a technique for using the satellite observed c...

167

First UV satellite observations of mesospheric water vapor  

Microsoft Academic Search

We report the first UV satellite observations of mesospheric water vapor. The measurements are of nonthermal OH prompt emission between 300–330 nm produced directly from the photodissociation of water vapor by H Lyman-?. This technique is most sensitive to water vapor concentrations between 70–90 km altitude. We present OH data from two limb scanning experiments: the Middle Atmosphere High Resolution

Michael H. Stevens; R. L. Gattinger; J. Gumbel; E. J. Llewellyn; D. A. Degenstein; M. Khaplanov; G. Witt

2008-01-01

168

Earth observation satellite performance using convolutional coding techniques  

Microsoft Academic Search

This paper shows an analytical approach for the evaluation of the tight upper bound of the bit error rate (BER) with CDMA-DS and applying the soft decision of Viterbi decoder technique as a contribution for future satellites applied to the earth observation. In this first part, the model is not stressed by some random signals as a jammer or some

Ivan Ramirez Ayala; C. San Martin Salas

2009-01-01

169

Tropospheric effects of satellite power systems  

SciTech Connect

The construction and operation of a system of solar power satellites is expected to have a variety of effects on the troposphere. The launching of large space vehicles affects the air quality in the vicinity of the launch site, and the ground cloud associated with such a launch is known to stimulate the growth of water clouds under some circumstances. The transmission of power from satellite to the Earth's surface may affect certain meteorological parameters in the vicinity of the rectenna site. These and other effects are discussed in reference to the proposed solar power satellite system.

Brubaker, K.L.; Lee, J.

1980-01-01

170

Introduction to Global Navigation Satellite System.  

National Technical Information Service (NTIS)

This viewgraph presentation reviews the fundamentals of satellite navigation, and specifically how GPS works. It presents an overview and status of Global Positioning System, for both the current GPS, and plans to modernize it in the future. There is also...

M. Moreau

2005-01-01

171

Generation of VLF saucer emissions observed by the Viking satellite  

SciTech Connect

The authors report observations of V shaped saucer emissions by the Viking satellite. This V shaped saucer emission refers to the observational feature of the VLF or ELF emissions which shows a v shaped appearance on a plot of frequency as a function of time. Viking provided not only wave, but electric and magnetic field measurements, as well as charged particle measurements. These measurements show electrons flowing upwards with enegies of up to a few hundred eV in conjunction with the saucer emissions. Other wave structures observed in this same region may originate from the electron flows. The satellite observations also find such events at altitudes from 4000 to 13000km, where the generation region is found to be much more spread out in space.

Loennqvist, H. [Swedish Institute of Space Physics, Uppsala (Sweden); Andre, M.; Matson, L. [Univ. of Umea (Sweden); Bahnsen, A. [Danish Space Research Institute, Lyngby (Denmark); Blomberg, L.G. [Royal Institute of Technology, Stockholm (Sweden); Erlandson, R.E. [Johns Hopkins Univ., Laurel, MD (United States)

1993-08-01

172

Satellite Observations for Evaluating CMIP5/IPCC Simulations  

NASA Astrophysics Data System (ADS)

Taylor et al (2008) have defined the protocol for the CMIP5 simulations that will be used for the next IPCC Assessment Report, AR5. The protocol defines the scope of simulations that will be undertaken by the participating modeling groups. For several of the prescribed retrospective simulations (e.g, decadal hindcasts, AMIP and 20th Century coupled simulations) observational data sets can be used to evaluate and diagnose the simulation outputs. In this presentation, we will report on a collaborative activity between NASA and PCMDI that has provided the community of researchers with a set of observations that align with key physical variables in these simulation outputs. These datasets contain temperature, specific humidity, ozone, ocean surface winds, SST, SSH, TOA outgoing radiation, and cloud fraction measurements from NASA satellites that have been formatted to match the CMIP5/IPCC climate model data sets. Each dataset is accompanied by a technical note that explains key details the user needs to be aware of in performing comparisons of the data with model output. The data sets are accessible via the same Earth System Grid (ESG) web portal as the model data. Community input is welcome on the long-term aspects of this project in terms of additional data sets, analysis capabilities, performance metrics, and relevant information technology issues (e.g., ESG).

Ferraro, R.; Waliser, D. E.; Teixeira, J.; Gleckler, P. J.

2011-12-01

173

Modeling Prairie Pothole Lakes: Linking Satellite Observation and Calibration (Invited)  

Microsoft Academic Search

This paper examines the response of a complex lake wetland system to variations in climate. The focus is on the lakes and wetlands of the Missouri Coteau, which is part of the larger Prairie Pothole Region of the Central Plains of North America. Information on lake size was enumerated from satellite images, and yielded power law relationships for different hydrological

F. W. Schwartz; G. Liu; B. Zhang; Z. Yu

2009-01-01

174

The plasmapause observed by DEMETER satellite during 2005-2009  

NASA Astrophysics Data System (ADS)

The micro-satellite DEMETER was launched into a polar and circular orbit with an altitude of 700 km on June 29, 2004, and has been providing a continuous survey of whistlers since May 2005. From ELF-VLF electric field measurements, each whistler is identified by the neural network system RNF experiment onboard DEMETER. Whistlers are electromagnetic impulses generated during lightning and propagating along the Earth’s magnetic field line, which is used to examine the plasmapause. In this study, we present and discuss the characteristics of the plasmapause in various seasons of the 5-year of 2005-2009 by means of the DEMETER satellite.

Ho, Y.; Liu, J. G.; Parrot, M.; Pinēon, J.

2010-12-01

175

FPGA Platform for Satellite Observations of VLF Emissions  

NASA Astrophysics Data System (ADS)

Transient Luminous Events (TLEs) are unique high-altitude phenomena which have recently been the subject of intense study because they may provide insight into the energy exchange and electromagnetic coupling of the high atmosphere and ionosphere. The systematic observation of TLEs is a difficult problem due to their rare occurrence and low signal levels. Historically, optical observations have been the primary method, and recent research indicates a potential correlation between TLE optical emissions and Very Low Frequency (VLF) radio emissions of a particular signature. Two opportunities present themselves for unique instrumentation development: first, a low-order "always-on" sensor placed in-situ on board an observational satellite can record all VLF emissions and gather statistical data on the correlation and rate of occurrence of these VLF signatures. Secondly, such a sensor can serve as a triggering mechanism to activate high-fidelity optical instruments to catch the TLE events in real time. Both of these scenarios present difficult challenges - real-time signal detection requires fast computations; and the space-environment requires both low-power consumption and high resilience to radiation. In light of these constraints, the preferred method is a specialized digital signal processor (DSP) implemented as a Field Programmable Gate Array (FPGA). This technology enables highly parallelizable data processing and due to the specialized hardware specific to this application, power consumption can be reduced. The development of FPGA platforms also offers the capability for extensibility and interoperability with similar ground-stations; additional features such as data recording, user-interfacing, and network connectivity are possible without total system redesign via the FPGA's unique development methodology. Currently, a hardware prototype has been developed which successfully performs the basic functionality for real-time signal processing and data presentation. Using satellite data from the DEMETER probe, algorithms were designed which could suitably detect the VLF signatures of interest, and these techniques were translated into the FPGA's platform for real-time performance. Systematic benchmarking with this data has verified that the implementation is capable of sustaining high-sensitivity detection, even in noisy environments, by dynamically adapting to the signal environment. This instrument enables statistical characterization of these VLF signatures; further work on the prototype platform will enable rapid delivery and visualization of the scientific data.

Moussa, N.; Linscott, I.; Inan, U.

2008-12-01

176

Possible satellite-based observations of the 1997 Leonid meteoroids  

SciTech Connect

The Block IIA GPS satellites are equipped with a sensor designed to detect electromagnetic transients. Several phenomena will produce triggers in this sensor. They include earth-based electromagnetic transients such as lightning and two space-based phenomena--deep dielectric discharge and meteoroid or hyper-velocity micro-gram particle impact (HMPI). Energetic electrons in the GPS environment cause the deep dielectric charging. HMPIs cause triggers through the transient electric fields generated by the ejecta plasma. During the 1997 Leonid passage the energetic particle fluxes were very low. In the presence of such low fluxes the typical median trigger rate is 20 per minute with a standard deviation of about 20 per minute. Between 0800 UT and 1200 UT on November 17, 1997, the sensor on a specially configured satellite observed trigger rates more than 10 sigma above the nominal median rate. Sensors on other Block IIA GPS satellites also observed excess triggers during November. Detection is enhanced when the sensor antenna is oriented into the Leonid radiant. While many questions persist the authors feel that it is likely that the excess events during the November interval were caused by the close approach of the satellites to the Leonid meteoroid path.

Pongratz, M.B.; Carlos, R.C.; Cayton, T.

1998-12-01

177

Satellite observations cap the atmospheric organic aerosol budget  

NASA Astrophysics Data System (ADS)

Limited understanding of the production and loss of organic aerosol (OA) to the atmosphere has resulted in poorly constrained source estimates ranging from 140 to 910 TgCyr-1 [Goldstein and Galbally, 2007]. We use satellite observations to quantitatively estimate the atmospheric burden of organic aerosol and the associated production. We find that attributing the mid-visible continental aerosol optical depth (AOD) observed by the MISR satellite entirely to OA implies a global source of 430 TgCyr-1 of sub-micron OA. We use a model (GEOS-Chem) to remove the contribution of inorganic aerosol, dust and soot from the observed AOD and derive a continental OA production of 150 TgCyr-1 (equivalent burden of 2.5 TgC), with 80% uncertainty. This result significantly reduces the uncertainty in the global OA budget and provides an upper limit for the “missing source” of OA.

Heald, Colette L.; Ridley, David A.; Kreidenweis, Sonia M.; Drury, Easan E.

2010-12-01

178

Evaluating cloud tuning in a climate model with satellite observations  

NASA Astrophysics Data System (ADS)

This study examines the validity of a tunable cloud parameter, the threshold particle radius triggering the warm rain formation, in a climate model. Alternate values of the model's particular parameter within uncertainty have been shown to produce severely different historical temperature trends due to differing magnitude of aerosol indirect forcing. Three different threshold radii are evaluated against satellite observations in terms of the statistics depicting microphysical process signatures of the warm rain formation. The results show that the simulated temperature trend best matches to observed trend when the model adopts the threshold radius that worst reproduces satellite?observed microphysical statistics and vice versa. This inconsistency between the "bottom?up" process?based constraint and the "top?down" temperature trend constraint implies the presence of compensating errors in the model.

Suzuki, Kentaroh; Golaz, Jean-Christophe; Stephens, Graeme L.

2013-08-01

179

Spectroscopic Observations of Geo-Stationary Satellites Over the Korean Peninsula  

NASA Astrophysics Data System (ADS)

Low resolution spectroscopic observations of geo-stationary satellites over the Korean peninsula have been carried out at the KyungHee Optical Satellite Observing Facility (KOSOF) with a 40cm telescope. We have observed 9 telecommunication satellites and 1 weather satellite of 6 countries. The obtained spectral data showed that satellites could be classified and grouped with similar basic spectral feature. We divided the 10 satellites into 4 groups based on spectral slop and reflectance. It is suggested that the material types of the satellites can be determined through spectral comparisons with the ground laboratory data. We will continuously observe additional geo-stationary satellites for the accurate classification of spectral features.

Lee, D. K.; Kim, S. J.; Han, W. Y.; Park, J. S.; Min, S. W.

2001-11-01

180

A land mobile satellite data system  

NASA Astrophysics Data System (ADS)

The Telesat Mobile Incorporated (TMI) Mobile Data System (MDS) was developed to apply satellite technology to the transportation industry's requirement for a fleet management system. It will provide two-way messaging and automatic position reporting capabilities between dispatch centers and customers' fleets of trucks. The design was based on the Inmarsat L-Band space segment with system link parameters and margins adjusted to meet the land mobile satellite channel characteristics. The system interfaces with the Teleglobe Des Laurentides earth station at Weir, Quebec. The signaling protocols were derived from the Inmarsat Standard C packet signalling system with unique trucking requirements incorporated where necessary.

Kent, John D. B.

181

Introducing relativity in global navigation satellite systems  

NASA Astrophysics Data System (ADS)

Today, the Global Navigation Satellite Systems, used as global positioning systems, are the GPS and the GLONASS. They are based on a Newtonian model and hence they are only operative when several relativistic effects are taken into account. The most important relativistic effects (to order 1/c(2) ) are: the Einstein gravitational blue shift effect of the satellite clock frequency (Equivalence Principle of General Relativity) and the Doppler red shift of second order, due to the motion of the satellite (Special Relativity). On the other hand, in a few years the Galileo system will be built, copying the GPS system unless an alternative project is designed. In this work, it will be also shown that the SYPOR project, using fully relativistic concepts, is an alternative to a mere copy of the GPS system. According to this project, the Galileo system would be exact and there would be no need for relativistic corrections.

Pascual-Sįnchez, J.-F.

2007-04-01

182

Quantitative comparisons of satellite observations and cloud models  

NASA Astrophysics Data System (ADS)

Microwave radiation interacts directly with precipitating particles and can therefore be used to compare microphysical properties found in models with those found in nature. Lower frequencies (< 37 GHz) can detect the emission signals from the raining clouds over radiometrically cold ocean surfaces while higher frequencies (? 37 GHz) are more sensitive to the scattering of the precipitating-sized ice particles in the convective storms over high-emissivity land, which lend them particular capabilities for different applications. Both are explored with a different scenario for each case: a comparison of two rainfall retrievals over ocean and a comparison of a cloud model simulation to satellite observations over land. Both the Goddard Profiling algorithm (GPROF) and European Centre for Medium-Range Weather Forecasts (ECMWF) one-dimensional + four-dimensional variational analysis (1D+4D-Var) rainfall retrievals are inversion algorithms based on the Bayes' theorem. Differences stem primarily from the a-priori information. GPROF uses an observationally generated a-priori database while ECMWF 1D-Var uses the model forecast First Guess (FG) fields. The relative similarity in the two approaches means that comparisons can shed light on the differences that are produced by the a-priori information. Case studies have found that differences can be classified into four categories based upon the agreement in the brightness temperatures (Tbs) and in the microphysical properties of Cloud Water Path (CWP) and Rain Water Path (RWP) space. We found a category of special interest in which both retrievals converge to similar Tb through minimization procedures but produce different CWP and RWP. The similarity in Tb can be attributed to comparable Total Water Path (TWP) between the two retrievals while the disagreement in the microphysics is caused by their different degrees of constraint of the cloud/rain ratio by the observations. This situation occurs frequently and takes up 46.9% in the one month 1D-Var retrievals examined. To attain better constrained cloud/rain ratios and improved retrieval quality, this study suggests the implementation of higher microwave frequency channels in the 1D-Var algorithm. Cloud Resolving Models (CRMs) offer an important pathway to interpret satellite observations of microphysical properties of storms. High frequency microwave brightness temperatures (Tbs) respond to precipitating-sized ice particles and can, therefore, be compared with simulated Tbs at the same frequencies. By clustering the Tb vectors at these frequencies, the scene can be classified into distinct microphysical regimes, in other words, cloud types. The properties for each cloud type in the simulated scene are compared to those in the observation scene to identify the discrepancies in microphysics within that cloud type. A convective storm over the Amazon observed by the Tropical Rainfall Measuring Mission (TRMM) is simulated using the Regional Atmospheric Modeling System (RAMS) in a semi-ideal setting, and four regimes are defined within the scene using cluster analysis: the 'clear sky/thin cirrus' cluster, the 'cloudy' cluster, the 'stratiform anvil' cluster and the 'convective' cluster. The relationship between Tb difference of 37 and 85 GHz and Tb at 85 GHz is found to contain important information of microphysical properties such as hydrometeor species and size distributions. Cluster-by-cluster comparison between the observations and the simulations discloses biases in the model including overproduction of supercooled water and large hail particles. The detected biases shed light on how the model should be adjusted to generate more realistic microphysical relationships for each cluster. Guided by the model/observation discrepancies in the 'convective' cloud cluster, a new simulation is performed to provide dynamic adjustments by generating more but smaller hail particles.

Wang, Fang

183

A Space Based Solar Power Satellite System  

NASA Astrophysics Data System (ADS)

(SPoTS) supplying other satellites with energy. SPoTS is due to be commercially viable and operative in 2020. of Technology designed the SPoTS during a full-time design period of six weeks as a third year final project. The team, organized according to the principles of systems engineering, first conducted a literature study on space wireless energy transfer to select the most suitable candidates for use on the SPoTS. After that, several different system concepts have been generated and evaluated, the most promising concept being worked out in greater detail. km altitude. Each SPoTS satellite has a 50m diameter inflatable solar collector that focuses all received sunlight. Then, the received sunlight is further redirected by means of four pointing mirrors toward four individual customer satellites. A market-analysis study showed, that providing power to geo-stationary communication satellites during their eclipse would be most beneficial. At arrival at geo-stationary orbit, the focused beam has expended to such an extent that its density equals one solar flux. This means that customer satellites can continue to use their regular solar arrays during their eclipse for power generation, resulting in a satellite battery mass reduction. the customer satellites in geo-stationary orbit, the transmitted energy beams needs to be pointed with very high accuracy. Computations showed that for this degree of accuracy, sensors are needed, which are not mainstream nowadays. Therefore further research must be conducted in this area in order to make these high-accuracy-pointing systems commercially attractive for use on the SPoTS satellites around 2020. Total 20-year system lifetime cost for 18 SPoT satellites are estimated at approximately USD 6 billion [FY2001]. In order to compete with traditional battery-based satellite power systems or possible ground based wireless power transfer systems the price per kWh for the customer must be significantly lower than the present one. Based on the expected revenues from about 300 customers, SPoTS needs a significant contribution from public funding to be commercial viable. However, even though the system might seem to be a huge investment first, it provides a unique steppingstone for future space based wireless transfer of energy to the Earth. Also the public funding is considered as an interest free loan and is due to be paid back over de lifetime period of SPoTS. These features make the SPoTS very attractive in comparison to other space projects of the same science field.

Engel, J. M.; Polling, D.; Ustamujic, F.; Yaldiz, R.; et al.

2002-01-01

184

Satellite Power Systems (SPS) cost review  

SciTech Connect

A study to determine estimated costs for three selected SPS designs is presented. One SPS concept uses silicon solar cells with a concentration ratio of one; one concept uses gallium arsenide solar cells with a concentration ratio of two; and the third (reference) design incorporates features of the first two. Selected system definition assumptions and cost estimating relationships for each of the three SPS concept designs were independently reviewed. The systems within the SPS designs chosen include: rectenna construction, graphite fiber reinforced thermoplastic structures, solar cells, satellite electrical slip rings, satellite electrical systems, and ground rectenna electrical systems. Procedures and results are detailed. (WHK)

Crowley, J.H.; Ziegler, E.J.

1980-05-01

185

Global ammonia distribution derived from infrared satellite observations  

NASA Astrophysics Data System (ADS)

Global ammonia emissions have more than doubled since pre-industrial times, largely owing to agricultural intensification and widespread fertilizer use. In the atmosphere, ammonia accelerates particulate matter formation, thereby reducing air quality. When deposited in nitrogen-limited ecosystems, ammonia can act as a fertilizer. This can lead to biodiversity reductions in terrestrial ecosystems, and algal blooms in aqueous environments. Despite its ecological significance, there are large uncertainties in the magnitude of ammonia emissions, mainly owing to a paucity of ground-based observations and a virtual absence of atmospheric measurements. Here we use infrared spectra, obtained by the IASI/MetOp satellite, to map global ammonia concentrations from space over the course of 2008. We identify several ammonia hotspots in middle-low latitudes across the globe. In general, we find a good qualitative agreement between our satellite measurements and simulations made using a global atmospheric chemistry transport model. However, the satellite data reveal substantially higher concentrations of ammonia north of 30?N, compared with model projections. We conclude that ammonia emissions could have been significantly underestimated in the Northern Hemisphere, and suggest that satellite monitoring of ammonia from space will improve our understanding of the global nitrogen cycle.

Clarisse, Lieven; Clerbaux, Cathy; Dentener, Frank; Hurtmans, Daniel; Coheur, Pierre-Franēois

2009-07-01

186

Large Scale Surface Radiation Budget from Satellite Observation  

NASA Astrophysics Data System (ADS)

During the current reporting period, the focus of our work was on preparing and testing an improved version of our Surface Radiation Budget algorithm for processing the ISCCP D1 data routinely at the SRB Satellite Data Analysis Center (SDAC) at NASA Langley Research Center. The major issues addressed are related to gap filling and to testing whether observations made from ERBE could be used to improve current procedures of converting narrowband observations, as available from ISCCP, into broadband observations at the TOA. The criteria for selecting the optimal version are to be based on results of intercomparison with ground truth.

Pinker, R. T.

1995-12-01

187

Satellite observations of continental shelf front in Northern China Sea  

NASA Astrophysics Data System (ADS)

Continental Shelf Front ( CSF ) is one kind of oceanographic phenomena which occurs usually at shallow water or shelf slope and is caused by tide mixing effect. Northern China Sea ( Yellow Sea ) is surrounded by Chinese mainland and Korea peninsula and is fovourable to the generation of CSF on the consequence of strong tidal mixing in this region. Presented in this paper are satellite observations of CSF from NOAA infrared imagery. Its geographic location, variability and relationship with tidal activities are also discussed.

Huang, R.; Wang, Q.; Zhao, B.

1993-05-01

188

Satellite microwave SST observations of transequatorial tropical instability waves  

Microsoft Academic Search

Satellite measurements of sea-surface temper- ature (SST) by the TRMM Microwave Imager reveal pre- viously unreported features of tropical instability waves (TIWs). In the Pacic, TIW-related variability is observed from the eastern boundary to at least 160E. Cusp-shaped distortions of SST fronts and associated trains of anticy- clonic vortices both north and south of the equator prop- agate westward at

Dudley B. Chelton; Frank J. Wentz; Chelle L. Gentemann; Roland A. de Szoeke; Michael G. Schlax

2000-01-01

189

First UV satellite observations of mesospheric water vapor  

Microsoft Academic Search

We report the first UV satellite observations of mesospheric water vapor. The measurements are of nonthermal OH prompt emission between 300-330 nm produced directly from the photodissociation of water vapor by H Lyman-alpha. This technique is most sensitive to water vapor concentrations between 70-90 km altitude. We present OH data from two limb scanning experiments: the Middle Atmosphere High Resolution

Michael H. Stevens; R. L. Gattinger; J. Gumbel; E. J. Llewellyn; D. A. Degenstein; M. Khaplanov; G. Witt

2008-01-01

190

Improving National Air Quality Forecasts with Satellite Aerosol Observations  

Microsoft Academic Search

Accurate air quality forecasts can allow for mitigation of the health risks associated with high levels of air pollution. During September 2003, a team of NASA, NOAA, and EPA researchers demonstrated a prototype tool for improving fine particulate matter (PM2.5) air quality forecasts using satellite aerosol observations. Daily forecast products were generated from a near-real-time fusion of multiple input data

Jassim Al-Saadi; James Szykman; R. Bradley Pierce; Chieko Kittaka; Doreen Neil; D. Allen Chu; Lorraine Remer; Liam Gumley; Elaine Prins; Lewis Weinstock; Clinton MacDonald; Richard Wayland; Fred Dimmick; Jack Fishman

2005-01-01

191

Satellite observations of lightning-induced electron precipitation  

Microsoft Academic Search

Lightning-induced electron precipitation (LEP) from the Earth's radiation belt has been observed on numerous occasions with detectors on the low-altitude S81-1\\/SEEP satellite. A sequence of seven LEP events on September 9, 1982, and eight events on October 20, 1982, are correlated on a one-to-one basis with one-hop whistlers at Palmer, Antarctica. The temporal profile within a LEP burst has a

H. D. Voss; M. Walt; W. L. Imhof; J. Mobilia

1998-01-01

192

Satellite observations of formaldehyde over North America from GOME  

Microsoft Academic Search

Formaldehyde (HCHO) is an important indicator of tropospheric hydrocarbon emissions and photochemical activity. We present HCHO observations over North America for July 1996 from the GOME instrument on-board the ESA ERS-2 satellite. Slant columns are determined to <4×1015moleculescm-2 sensitivity by directly fitting GOME radiance measurements. These show a distinct enhancement over the southeastern United States, consistent with a large regional

Kelly Chance; Paul I. Palmer; Robert J. D. Spurr; Randall V. Martin; Thomas P. Kurosu; Daniel J. Jacob

2000-01-01

193

Appropriate satellite systems for rural telecommunications  

NASA Astrophysics Data System (ADS)

In order to provide a minimum, basic telecommunications service to as large a segment of the unserved rural population as possible, the system objective should be to place one or a few telephone instruments in as many localities as possible, instead of placing a larger number of subscriber instruments in fewer localities. A high value of satellite figure of merit (G/T) combined with high transponder gain would facilitate the utilization of low transmit power from the earth station; it is claimed that this would be the key to the success of an operational rural telecommunications service via satellite. It is noted that demand assigned SCPC transmission techniques are ideally suited for this service. It is concluded that, for satellite communications to provide minimum basic rural telephone service within a reasonable time span, it will be necessary to employ properly designed high-transfer-gain satellites with large production runs of small low-cost earth stations.

Nickelson, R. L.

194

Astrometric observations and comparison with theory of Saturn's satellites from Bordeaux Observatory, 1984  

SciTech Connect

The astrometric observations of Saturn's satellites reported in this paper have been reduced from the SAO catalog. Observed positions of the satellites are given both in absolute topocentric astrometric coordinates and in differential coordinates by using a reference satellite. Residuals derived from comparison between observed and computed positions of the satellites are also reported. A discussion shows that Iapetus, which presents the highest residuals, needs, more than all other observed satellites, an improvement of its theory of motion. 7 refs.

Dourneau, G.; Le Campion, J.F.; Dulou, M.R. (Bordeaux I Universite, Observatoire, Floirac (France))

1989-08-01

195

Revolutionary next generation satellite communications architectures and systems  

Microsoft Academic Search

This paper describes possible revolutionary next generation communications satellite missions and architectures. The satellite communications evolutionary background, current GSO's (geostationary orbit satellites), `Little', `Big' and `Broadband' NGSO's (non-GSO's), and enabling satellite technologies are briefly discussed. Converging technological and economic forces will drive us inevitably to the next decade's communication satellite systems and network architectures. The increasing pace of new capabilities,

J. R. Stuart; J. G. Stuart

1997-01-01

196

Precise two way time synchronization for distributed satellite system  

Microsoft Academic Search

The satellite to satellite precise ranging and time synchronization are necessary to distributed satellite system (DSS) and autonomous formation flyer (AFF) application. In satellite formation flying, the range between a cluster of co-orbiting or constellation satellites is very close, they collaborate with each other and perform special scientific missions cooperatively, so they can be regarded as a large single conventional

Li Gun; Huang Feijiang

2009-01-01

197

Performance analysis of randomized MAC for satellite telemetry systems  

Microsoft Academic Search

The overwhelming success of the Internet provides scientists new tools to understand our mother nature. Argos is a worldwide satellite system dedicated to Earth observation and environmental research. Argos system has an excellent track record for data collection, processing and dissemination to the scientific and international community and gains popularity steadily. However, when the number of Argos users exceeds certain

Haoling Ma; Lin Cai

2010-01-01

198

Combined analysis of GNSS and SLR observations for the GIOVE satellites  

NASA Astrophysics Data System (ADS)

The GGSP (Galileo Geodetic Service Provider) is responsible to provide the geodetic basement of the future European GNSS, the Galileo system. The AIUB is one partner of the consortium of seven institutions. In the context of this project, the data of 13 GESS (Galileo Experimental Sensor Stations) are processed together with the GPS data of about 120 IGS sites. Apart from the station coordinates also the satellite orbits, ERPs, and clock corrections are computed. Since the 13 GESS do not only provide GPS data but also track the two first Galileo satellites (i.e., GIOVE-A and GIOVE-B), a combined processing of the GPS and Galileo data using microwave data is possible. Due to the sparse network of GESS the GPS data highly support the Galileo related products (the orbits and satellite clock corrections). Nevertheless, the quality of the GIOVE orbits is limited to about 20 cm. As both GIOVE are equipped with retro-reflector arrays, the satellites are tracked by satellite laser ranging (SLR), as it is already done for some GLONASS satellites and those two GPS satellites equipped with retro-reflectors. The availability of SLR data allows a validation of the satellite orbits determined from GNSS observations. The range residuals show whether there is any systematic difference between the GNSS and SLR system and, thus, may help to improve the orbit modeling for the GIOVE satellites. Furthermore, we will include the SLR tracking data into the orbit determination in order to derive a combined GNSS+SLR orbit. It will be studied whether the inclusion of SLR data shows any significant improvement for the combined orbit compared to the GNSS-only orbit. This study can be seen as a further step toward the combined processing of GNSS and SLR observations for a fully integrated multi-technique data analysis.

Thaller, D.; Steinbach, A.; Dach, R.

2009-04-01

199

Satellite reconnaissance  

NASA Astrophysics Data System (ADS)

The potential of the observation equipment in remote sensing satellites is described. United States meteorology, land use and oceanography satellites and the major US Earth observation programs are listed. Imaging satellite systems are described such as: visible light and near infrared, thermal IR window, and microwave window. It is concluded that a geometrical resolution between 10 and 40 m can be expected. In order to reduce the data flow from the satellite system the input side of the system (the object-sensor interaction) has to be known. Satellites with synthetic aperture radar are increasingly important, but satellites can never fully replace observations with aircraft and drones.

Deloor, G. P.

1984-06-01

200

Laser satellite power systems - Concepts and issues  

NASA Astrophysics Data System (ADS)

A laser satellite power system (SPS) converts solar power captured by Earth-orbiting satellites into electrical power on the Earth's surface, the satellite-to-ground transmission of power being effected by a laser beam. The laser SPS is an alternative to the microwave SPS. Lasers and how they work are described, as are the types of lasers - electric discharge, direct and indirect solar pumped, free electron, and closed-cycle chemical - that are candidates for application in a laser SPS. The advantages of a laser SPS over the microwave alternative are pointed out. One such advantage is that, for the same power delivered to the utility busbar, land requirements for a laser system are much smaller (by a factor of 21) than those for a microwave system. The four laser SPS concepts that have been presented in the literature are described and commented on. Finally key issues for further laser SPS research are discussed.

Walbridge, E. W.

201

National Trends in Satellite Observed Lighting: 1992-2009  

NASA Astrophysics Data System (ADS)

A time series of global annual satellite maps of nighttime lights reveals several distinct patterns linked to population changes, economic development and the improvements in lighting efficiency. Six categories of national lighting trends have been defined: 1) Rapid growth in lighting driven by population and economic growth, 2) Population driven changes in nighttime lights, 3) Economic driven changes in nighttime lights, 4) Erratic, with wide interannual variation in nighttime lights and little affinity to population and economic changes, 5) Stable, with little change over time and little affinity to population and economic changes, and 6) Transitional countries not fitting in to the other five classes, in many cases due to a shift from one class to another midway through the time series. The results indicate that there are national level differences in the behavior of nighttime lights over time. Recognition of these patterns may lead to improved spatial modeling of socioeconomic processes based on satellite observed nighttime lights.

Elvidge, C. D.; Sutton, P. C.; Baugh, K.; Ziskin, D. C.; Ghosh, T.; Anderson, S.

2011-12-01

202

Television pickup system for satellite location  

Microsoft Academic Search

The use of a television camera in the considered system makes it possible to correct the obtained satellite position on the basis of the image on the television receiver screen. The decisive factor regarding the design of such a system is related to the selection of a suitable television camera tube with the required high sensitivity. Special tubes with image

E. Maase

1977-01-01

203

On classifying rain types using satellite microwave observations  

NASA Astrophysics Data System (ADS)

Classification of rain type in satellite microwave observations is useful for various studies ranging from numerical weather prediction and precipitation climatology to satellite retrieval of rain amounts. In this study we have first examined the possibility of determining the distribution of convective/stratiform rain within a typical microwave radiometric pixel size area represented by the Tropical Rainfall Measuring Mission Microwave Imager (TMI) and then formulated an empirical relation between the convective to stratiform ratio and observed brightness temperatures. Rain classification with satellite microwave observation is hampered by the small size of the rain events. It is found from the rain observations during July 2000 that a significant number of 53% convective and 28% stratiform rain fill less than one fourth of the TMI pixel size area. The nonlinear relationship between brightness temperature and rain rate, along with horizontal and vertical inhomogeneity of the rain type distribution within the pixel, makes it difficult to work out the exact proportion of convective to stratiform distribution within the pixel. Here an algorithm is proposed to determine rain type on the basis of regression with 10 functions of 19, 37, and 85 GHz channels into three broad convective-stratiform proportions. This algorithm is able to identify rain types in about 70% of the TMI pixels accurately. To broaden the utility of the proposed method, a procedure has been developed by which the method can be applied to any other microwave radiometers with similar channels to TMI. Using this procedure, a successful application of the algorithm to Special Sensor Microwave Imager observations is demonstrated.

Varma, Atul Kumar; Liu, Guosheng

2010-04-01

204

Advanced technologies for future environmental satellite systems  

Microsoft Academic Search

Environmental satellites today are designed to meet the most requirements possible within the constraints of budget, reliability, availability, robustness, manufacturability, and the state of the art in affordable technology. As we learn more and more about observing and forecasting, requirements continue to be developed and validated for measurements that can benefit from for advances in technology. The goal is to

Gerald J. Dittberner; Michael J. Crison; Shyam Bajpai; Benjamin L. Diedrich

2004-01-01

205

Satellite observations with a single radar tracking station  

NASA Astrophysics Data System (ADS)

Handicaps in observations due to the relative motion between a satellite and the radar station are highlighted. It is shown that decaying high-risk space objects can be observed by a single radar tracking station. But less than 10% of an orbit and 50% of all orbits per day are within line-of-sight of the radar station. Breaks of 14 hr between 2 consecutive passages are possible. This can cause total target loss because of outdated orbit data. Cooperation with observation stations in other parts of the world is therefore desirable. In order to fit the observation requirements the radar should deliver angular direction, range, and at least echo amplitude measurements.

Mehrholz, D.

206

Comparing soil moisture memory in satellite observations and models  

NASA Astrophysics Data System (ADS)

A major obstacle to a correct parametrization of soil processes in large scale global land surface models is the lack of long term soil moisture observations for large parts of the globe. Currently, a compilation of soil moisture data derived from a range of satellites is released by the ESA Climate Change Initiative (ECV_SM). Comprising the period from 1978 until 2010, it provides the opportunity to compute climatological relevant statistics on a quasi-global scale and to compare these to the output of climate models. Our study is focused on the investigation of soil moisture memory in satellite observations and models. As a proxy for memory we compute the autocorrelation length (ACL) of the available satellite data and the uppermost soil layer of the models. Additional to the ECV_SM data, AMSR-E soil moisture is used as observational estimate. Simulated soil moisture fields are taken from ERA-Interim reanalysis and generated with the land surface model JSBACH, which was driven with quasi-observational meteorological forcing data. The satellite data show ACLs between one week and one month for the greater part of the land surface while the models simulate a longer memory of up to two months. Some pattern are similar in models and observations, e.g. a longer memory in the Sahel Zone and the Arabian Peninsula, but the models are not able to reproduce regions with a very short ACL of just a few days. If the long term seasonality is subtracted from the data the memory is strongly shortened, indicating the importance of seasonal variations for the memory in most regions. Furthermore, we analyze the change of soil moisture memory in the different soil layers of the models to investigate to which extent the surface soil moisture includes information about the whole soil column. A first analysis reveals that the ACL is increasing for deeper layers. However, its increase is stronger in the soil moisture anomaly than in its absolute values and the first even exceeds the latter in the deepest layer. From this we conclude that the seasonal soil moisture variations dominate the memory close to the surface but these are dampened in lower layers where the memory is mainly affected by longer term variations.

Stacke, Tobias; Hagemann, Stefan; Loew, Alexander

2013-04-01

207

A native IP satellite communications system  

NASA Astrophysics Data System (ADS)

? In the framework of ESA's ARTES-5 program the Institute of Applied Systems Technology (Joanneum Research) in cooperation with the Department of Communications and Wave Propagation has developed a novel meshed satellite communications system which is optimised for Internet traffic and applications (L*IP—Local Network Interconnection via Satellite Systems Using the IP Protocol Suite). Both symmetrical and asymmetrical connections are supported. Bandwidth on demand and guaranteed quality of service are key features of the system. A novel multi-frequency TDMA access scheme utilises efficient methods of IP encapsulation. In contrast to other solutions it avoids legacy transport network techniques. While the DVB-RCS standard is based on ATM or MPEG transport cells, the solution of the L*IP system uses variable-length cells which reduces the overhead significantly. A flexible and programmable platform based on Linux machines was chosen to allow the easy implementation and adaptation to different standards. This offers the possibility to apply the system not only to satellite communications, but provides seamless integration with terrestrial fixed broadcast wireless access systems. The platform is also an ideal test-bed for a variety of interactive broadband communications systems. The paper describes the system architecture and the key features of the system.

Koudelka, O.; Schmidt, M.; Ebert, J.; Schlemmer, H.; Kastner-Puschl, S.; Riedler, W.

2004-08-01

208

Satellite-based Observation of the Tectonics of Southern Tibet  

SciTech Connect

The Himalayas and the Tibetan Plateau were formed as a result of the collision of India and Asia, and provide an excellent natural laboratory for the investigation of the mechanical response of the outer 100 km of the Earth (the lithosphere) to tectonic stress. Geophysicists are divided in their views on the nature of this response with one group advocating homogeneously distributed deformation in which the lithosphere deforms as a fluid continuum while others contend that deformation is highly localized with the lithosphere deforming as a system of rigid blocks. These rigid blocks or plate undergo little internal deformation. The latter group draws support from the high slip-rates recently observed on strike-slip faults along the northern edge of the Plateau (the Altyn Tagh Fault, ATF), coupled with seismic observations suggesting that these faults penetrate the entire lithosphere. These ''lithospheric faults'' define continental lithospheric plates and facilitate the eastward extrusion of the ''central Tibet plate''. If extrusion of a rigid Tibet occurs then there must be equivalent features at its southern boundary with slip-rates similar to those in the north. The southern boundary of Tibet, defined by the Main Himalayan Thrust (MHT), has no lateral component of motion and is therefore kinematically incompatible with motion in the north. However, a series of features, the Karakorum Fault, the Karakorum-Jiali Fracture Zone (KJFZ), the Jiali Fault and the Red River Fault which lie to the north of the MHT may define the actual, kinematic, southern boundary of this ''central Tibet plate''. We have investigated the rate of slip along the Karakorum Fault (KKF), the major strike-slip fault in southwestern Tibet. If the KKF represents the actual, kinematic, southern boundary of this Tibet, and is the only feature accommodating eastward extrusion of Tibet, then its slip-rate should be similar to that of the ATF in the north. Offsets along the Karakorum Fault ranging from tens of meters to kilometers have been mapped using satellite imagery and field mapping, and samples ages determined by cosmic-ray exposure dating. Near Bulong Kol (39{sup o}N, 75{sup o}E) cosmogenic dating of a 40 m fluvial offset yields a slip rate of {approx}6.5 mm/yr. Near Mt. Kailas (31.5{sup o}N, 80.7{sup o}E), a glacial moraine offset by {approx}350 m has been dated at 32.3 {+-} 9.5 thousand years, yielding a slip rate of 10.8 {+-} 3.6 mm/yr. In the Gar Valley (32{sup o}N, 80{sup o}E) a river channel incised in glacial sediments yields an offset of 1750 m and an age of 283,000 years equivalent to a slip-rate of 6 mm/yr. Relative to the ATF, the slip rates on the KKF are lower than expected, and since these measurements cover almost the entire length of the KKF, the disparity cannot be attributed to along strike variation in the rate. Based upon the analysis of satellite images along the Karakorum Fault, we believe that this apparent slip deficit may be to the en echelon arrangement of multiple strike slip fault segments that characterize what should more appropriately be called the Karakorum Fault Zone. The geometric arrangement of parallel fault segments produces the ''pull apart'' basins that form the valleys along the KKF. Hence, at any given latitude, slip along the KKF may be distributed among numerous fault segments. This investigation supports efforts to understand the structure and mechanical response of the Earth's crust and supports the application of remote sensing methods.

Ryerson, F J; Finkel, R; van der Woerd, J

2003-02-06

209

Regional performance of quantitative precipitation estimates from satellite observations  

NASA Astrophysics Data System (ADS)

The estimation of rainfall has been a major focus for research and operational activities at both regional and global scales. The retrieval of precipitation (rainfall and snowfall) has exploited a large number of Earth Observation missions with a range of sensors spanning the visible, infrared and microwave regions of the spectrum. Methodologies have included empirical and physical techniques, utilising data from single and multi-sensor observations. These have not only improved our understanding of the precipitation processes within the atmosphere, but also the occurrence, distribution and accumulation of precipitation across the globe. The retrieval of precipitation from satellite observations over the tropical regions has undergone significant development due to the advanced observational capabilities provided by the Tropical Rainfall Measuring Mission suite of sensors. However, retrievals of precipitation at mid and high latitudes are more problematic: cloud-rainfall relationships that form the basis of visible/infrared techniques are poor, while passive microwave retrievals are hindered by snow and shallow precipitation. Some advances in retrieval techniques are being facilitated through the use of satellite radar measurements (i.e. CLOUDSAT), although these are of limited coverage, both spatially and temporally. Furthermore the sensitivity to low-level and light precipitation remains a major problem: low intensity precipitation contributes an increasingly large amount at these latitudes with significant underestimation by both passive and active microwave retrievals. This paper provides an overview of the progress in global satellite precipitation estimation to date. The results of the International Precipitation Working Group will be highlighted from a number of regional validation sites used for the evaluation of daily 0.25x0.25 degree precipitation products. Results generally show that the satellite estimates perform best during the warm season, but perform less well in the cold season. These results are, in part, due to the precipitation processes and the inability of techniques to usefully retrieve data over cold surface background. Regional variations in performance are also noticeable: these may be attributable to the sensitivity of individual techniques to light-intensity precipitation.

Kidd, Chris; Ebert, Beth; Janowiak, John; Vila, Daniel

2010-05-01

210

Fluid dynamic forces on tethered satellite systems  

Microsoft Academic Search

This paper deals with the modeling of the fluid dynamic interaction of a molecular gas with an element of the outer surface of a space vehicle in flow conditions which are characterized by a great variation of the Knudsen number. The results are applied to the evaluation of the aerodynamic forces on parts of a tethered satellite system.

N. Bellomo; N. de Divitiis; L. M. de Socio

1991-01-01

211

Satellite Power System (SPS) Public Acceptance.  

National Technical Information Service (NTIS)

The purpose of this report is to develop a preliminary perspective on the public acceptability of the Solar Satellite Power System (SPS) Program, and a means to monitor it. A literature review and informal contacts with interest groups likely to take a po...

A. Bachrach

1978-01-01

212

Satellite Power System (SPS) Military Implications.  

National Technical Information Service (NTIS)

The military implications of the reference satellite power system (SPS) were examined is well as important military related study tasks. Primary areas of investigation were the potential of the SPS as a weapon, for supporting U.S. military preparedness, a...

C. N. Bain

1978-01-01

213

Satellite Power System (SPS) Public Outreach Experiment.  

National Technical Information Service (NTIS)

An outreach experiment was conducted to improve the results of the satellite power system (SPS) concept development and evaluation program. The objectives of the outreach were to: (1) determine the areas of major concern relative to the SPS concept and (2...

S. R. Mcneal

1980-01-01

214

Solar power satellite system sizing tradeoffs  

SciTech Connect

Technical and economic tradeoffs of smaller solar power satellite systems configured with larger antennas, reduced output power, and smaller rectennas, are considered. The differential costs in electricity for seven antenna/rectenna configurations operating at 2.45 GHz and five satellite systems operating at 5.8 GHz are calculated. Two 2.45 GHz configurations dependent upon the ionospheric power density limit are chosen as examples. If the ionospheric limit could be increased to 54 mW sq/cm from the present 23 mW sq/cm level, a 1.53 km antenna satellite operating at 2.45 GHz would provide 5.05 GW of output power from a 6.8 km diameter rectenna. This system gives a 54 percent reduction in rectenna area relative to the reference solar power satellite system at a modest 17 percent increase in electricity costs. At 5.8 GHz, an 0.75 km antenna providing 2.72 GW of power from a 5.8 km diameter rectenna is selected for analysis. This configuration would have a 67 percent reduction in rectenna area at a 36 percent increase in electricity costs. Ionospheric, atmospheric, and thermal limitations are discussed. Antenna patterns for three configurations to show the relative main beam and sidelobe characteristics are included.

Arndt, G.D.; Monford, L.G.

1981-02-01

215

Vertical Component of Satellite Navigation Systems  

Microsoft Academic Search

The altitude is one of four coordinates of the user's position obtained from Satellite Navigation System (SNS) measurements. The distributions (in per cent) of VDOP coefficient value for different constellations of three SNS - GPS, GLONASS and Galileo - for different masking elevation angles for different user's latitudes are presented in the paper. The results of the measurements of GPS

Jacek Januszewski

2010-01-01

216

Satellite Power Systems - Promise and perspective  

NASA Astrophysics Data System (ADS)

The future energy requirements of the earth and the problems and possibilities associated with energy generation for the future are briefly discussed. The main trends and ultimate requirements are emphasized, and the use of satellite power systems with the potential to provide an inexhaustible source of clean safe energy is discussed in this context.

Martin, A. R.

217

Mobile antenna system for direct broadcasting satellite  

Microsoft Academic Search

A television broadcasting service via a direct broadcasting satellite (DBS) is already operational in Japan with many residential subscribers. In addition, many people want to watch the DBS broadcasting even in cars, because DBS broadcasting has advantages over terrestrial television broadcasting such as high quality, simultaneity, and wide coverage. Several mobile antenna systems for the DBS have been developed previously.

T. Watanabe; M. Ogawa; K. Nishikawa; T. Harada; E. Teramoto; M. Morita

1996-01-01

218

Long-term observations of tropospheric NO2 from satellite  

NASA Astrophysics Data System (ADS)

Nitrogen oxides (NOx = NO + NO2 ) are key species in atmospheric chemistry. Together with volatile organic compounds they determine the amount of ozone present in the troposphere. Through the formation of nitric acid they are involved in acid rain formation and in addition they contribute to radiative forcing both directly and indirectly. As nitrogen dioxide adversely affects human health it is also regulated by environmental laws. While ground-based networks provide long-term data of surface concentrations of nitrogen oxides at high temporal resolution in many countries, truly global observations can only be performed from space. By using the Differential Optical Absorption Spectroscopy (DOAS) method on spectrally resolved UV/vis measurements of scattered sunlight, column amounts of NO2 can be determined from nadir satellite observations. With additional assumptions on stratospheric NO2 and the radiative transfer, the tropospheric NO2 amounts can be retrieved. In this work, satellite observations of NO2 from several sensors (GOME, SCIAMACHY, OMI, and GOME-2) are used to study the long-term evolution of tropospheric NO2 amounts on a global scale. A particular focus is on the comparison of results retrieved from the different sensors in times of overlapping measurements and the degree of consistency achieved in regions of both large and small pollution signals. The effects of sampling statistics, time of overpass and spatial resolution are discussed as well as the influence of clouds.

Richter, Andreas; Hilboll, Andreas; Noguchi, Katsuyuki; Leitao, Joana; Burrows, John P.

219

1 cm Observations of Asteroids and Galilelean Satellites  

NASA Astrophysics Data System (ADS)

Asteroids 1 Ceres, 2 Pallas, and 4 Vesta and Galilean satellites Ganymede, Callisto, and Europa were observed in February and March, 2012 near 1 cm with the Green Bank Telescope in order to look for and characterize any deviations from a blackbody curve. The Caltech Continuum Backend instrument on that telescope provides uniquely useful information by simultaneously measuring 4 continuum bands between 7 and 11 mm, thus enabling the direct measurement of continuum slope. Ceres and Vesta are both successfully detected and show non-zero slopes in brightness temperature. Vesta's 1 cm continuum also shows some change with longitude that may be related to the previously detected light-curve at 3 mm (Müller and Barnes 2007). Observing the icy Galilean satellites is complicated by contamination from Jupiter's presence in the sidelobes of a single dish telescope. A technique for detecting and removing this contamination is applied. Overall, brightness temperature numbers are in agreement with previous observations at other wavelengths, but non-zero slopes in brightness temperature are also detected which require further analysis.

Ries, Paul

2012-10-01

220

Ice cloud microphysics inferred from PARASOL satellite observations  

NASA Astrophysics Data System (ADS)

Cirrus clouds are an important element in the radiative balance of the earth, so a good understanding of their radiative and microphysical properties is essential. Remote sensing of cirrus clouds using the state of polarization of the reflected solar radiation in addition to its intensity can provide more information about the microphysics of the ice contained in the cloud. In this study, the reflected solar radiation from cirrus clouds with different mixtures of ice crystals is simulated and compared with satellite observations. Both smooth and roughened particles are considered, including those used for the current operational MODIS collection 5 ice cloud products and a new habit mixture under consideration for the upcoming collection 6 products. The simulations are performed with an adding-doubling model developed by de Haan et al. (1987) which gives the full Stokes vector at the top of the atmosphere (TOA). The simulated results are compared with observations from the POLDER (POLarization and Directionality of the Earth's Reflectances) instrument on the PARASOL (Polarization and Anisotropy of Reflectances for Atmospheric Sciences coupled with Observations from a Lidar) satellite.

Cole, B. H.; Yang, P.; Baum, B. A.; Riedi, J.

2011-12-01

221

Satellite observations of desert dust-induced Himalayan snow darkening  

NASA Astrophysics Data System (ADS)

The optically thick aerosol layer along the southern edge of the Himalaya has been subject of several recent investigations relating to its radiative impacts on the South Asian summer monsoon and regional climate forcing. Prior to the onset of summer monsoon, mineral dust from southwest Asian deserts is transported over the Himalayan foothills on an annual basis. Episodic dust plumes are also advected over the Himalaya, visible as dust-laden snow surface in satellite imagery, particularly in western Himalaya. We examined spectral surface reflectance retrieved from spaceborne MODIS observations that show characteristic reduction in the visible wavelengths (0.47 µm) over western Himalaya, associated with dust-induced solar absorption. Case studies as well as seasonal variations of reflectance indicate a significant gradient across the visible (0.47 µm) to near-infrared (0.86 µm) spectrum (VIS-NIR), during premonsoon period. Enhanced absorption at shorter visible wavelengths and the resulting VIS-NIR gradient is consistent with model calculations of snow reflectance with dust impurity. While the role of black carbon in snow cannot be ruled out, our satellite-based analysis suggests the observed spectral reflectance gradient dominated by dust-induced solar absorption during premonsoon season. From an observational viewpoint, this study underscores the importance of mineral dust deposition toward darkening of the western Himalayan snow cover, with potential implications to accelerated seasonal snowmelt and regional snow albedo feedbacks.

Gautam, Ritesh; Hsu, N. Christina; Lau, William K.-M.; Yasunari, Teppei J.

2013-03-01

222

Multipath Study for a Low Altitude Satellite Utilizing a Data Relay Satellite System.  

National Technical Information Service (NTIS)

Technical considerations associated with a low altitude satellite operating in conjuction with a data relay satellite system are reported. Emphasis was placed on the quantitative characterization of mulipath phenomenon and determination of power received ...

D. Eggert

1970-01-01

223

An automated mapping satellite system ( Mapsat).  

USGS Publications Warehouse

The favorable environment of space permits a satellite to orbit the Earth with very high stability as long as no local perturbing forces are involved. Solid-state linear-array sensors have no moving parts and create no perturbing force on the satellite. Digital data from highly stabilized stereo linear arrays are amenable to simplified processing to produce both planimetric imagery and elevation data. A satellite imaging system, called Mapsat, including this concept has been proposed to produce data from which automated mapping in near real time can be accomplished. Image maps as large as 1:50 000 scale with contours as close as a 20-m interval may be produced from Mapsat data. -from Author

Colvocoresses, A. P.

1982-01-01

224

Determination of motion extrema in multi-satellite systems  

NASA Astrophysics Data System (ADS)

Spacecraft, or satellite formation flight has been a topic of interest dating back to the Gemini program of the 1960s. Traditionally space missions have been designed around large monolithic assets. Recent interest in low cost, rapid call up mission architectures structured around fractionated systems, small satellites, and constellations has spurred renewed efforts in spacecraft relative motion problems. While such fractionated, or multi-body systems may provide benefits in terms of risk mitigation and cost savings, they introduce new technical challenges in terms of satellite coordination. Characterization of satellite formations is a vital requirement for them to have utility to industry and government entities. Satellite formations introduce challenges in the form of constellation maintenance, inter-satellite communications, and the demand for more sophisticated guidance, navigation, and control systems. At the core of these challenges is the orbital mechanics which govern the resulting motion. New applications of algebraic techniques are applied to the formation flight problem, specifically Gröbner basis tools, as a means of determining extrema of certain quantities pertaining to formation flight. Specifically, bounds are calculated for the relative position components, relative speed, relative velocity components, and range rate. The position based metrics are relevant for planning formation geometry, particularly in constellation or Earth observation applications. The velocity metrics are relevant in the design of end game interactions for rendezvous and proximity operations. The range rate of one satellite to another is essential in the design of radio frequency hardware for inter-satellite communications so that the doppler shift can be calculated a priori. Range rate may also have utility in space based surveillance and space situational awareness concerns, such as cross tagging. The results presented constitute a geometric perspective and have utility to mission designers, particularly for missions involving rendezvous and proximity operations.

Allgeier, Shawn E.

225

Wideband VLF electromagnetic bursts observed on the DE 1 satellite  

SciTech Connect

Wideband VLF electromagnetic bursts are observed on the DE 1 satellite by both the electric and magnetic field sensors in the frequency range of 0.650 kHz to 16.0 kHz. The impulsive signals endure for a relatively short time ({approximately}1s or less) and exist in the frequency range from well below to well above the local gyrofrequency. They are typically found at L > 4 over a {approximately} 40{degree} range of latitudes including the geomagnetic equator and are often accompanied by discrete emissions or a band of hiss. Some observed features are consistent with previous observations of electrostatic plasma waves (Ondoh et al., 1989; Reinleitner et al., 1983); however, the magnetic measurements clearly indicate that the impulsive signals are electromagnetic in nature, a result that has not been reported before. The possibility of spacecraft discharge effects as the cause of these signals is discussed.

Sonwalkar, V.S.; Helliwell, R.A.; Inan, U.S. (Stanford Univ., CA (USA))

1990-10-01

226

A system for autonomous determination of the location and velocity of TV satellites  

NASA Astrophysics Data System (ADS)

An original method for observing a future TV satellite of Yugoslav television and automatic correction of its location is presented. Combining TV satellite equipment with the appropriate instrumentation of three earth stations yields a telemetric system for determining the satellite's location and velocity.

Golubovic, L. R.

1991-05-01

227

Modeling Prairie Pothole Lakes: Linking Satellite Observation and Calibration (Invited)  

NASA Astrophysics Data System (ADS)

This paper examines the response of a complex lake wetland system to variations in climate. The focus is on the lakes and wetlands of the Missouri Coteau, which is part of the larger Prairie Pothole Region of the Central Plains of North America. Information on lake size was enumerated from satellite images, and yielded power law relationships for different hydrological conditions. More traditional lake-stage data were made available to us from the USGS Cottonwood Lake Study Site in North Dakota. A Probabilistic Hydrologic Model (PHM) was developed to simulate lake complexes comprised of tens-of-thousands or more individual closed-basin lakes and wetlands. What is new about this model is a calibration scheme that utilizes remotely-sensed data on lake area as well as stage data for individual lakes. Some ¼ million individual data points are used within a Genetic Algorithm to calibrate the model by comparing the simulated results with observed lake area-frequency power law relationships derived from Landsat images and water depths from seven individual lakes and wetlands. The simulated lake behaviors show good agreement with the observations under average, dry, and wet climatic conditions. The calibrated model is used to examine the impact of climate variability on a large lake complex in ND, in particular, the “Dust Bowl Drought” 1930s. This most famous drought of the 20th Century devastated the agricultural economy of the Great Plains with health and social impacts lingering for years afterwards. Interestingly, the drought of 1930s is unremarkable in relation to others of greater intensity and frequency before AD 1200 in the Great Plains. Major droughts and deluges have the ability to create marked variability of the power law function (e.g. up to one and a half orders of magnitude variability from the extreme Dust Bowl Drought to the extreme 1993-2001 deluge). This new probabilistic modeling approach provides a novel tool to examine the response of the behavior of a complex of closed lakes vary in scale from the footprint of a small house to that of a small city.

Schwartz, F. W.; Liu, G.; Zhang, B.; Yu, Z.

2009-12-01

228

An Analysis of Satellite State Vector Observability Using SST Tracking Data.  

National Technical Information Service (NTIS)

Observability of satellite state vectors, using only SST tracking data was investigated by covariance analysis under a variety of satellite and station configurations. These results indicate very precarious observability in most short arc cases. The conse...

T. S. Englar C. L. Hammond

1976-01-01

229

GOME-2 satellite observations of NOx emissions from ships  

NASA Astrophysics Data System (ADS)

The volume of international shipping has been rapidly increasing over the last decades, and further increases are expected for the coming years. A large fraction of the shipping is close to coastal areas but for intercontinental transport, shipping routes also pass through the remote oceans. As the volume of transported goods is increasing, so is the amount of shipping related pollutant emissions into the marine boundary layer. As result of the lack of legislation on shipping emissions, in particular in international waters, in combination with substantial emission reductions for many land based sources, the relative importance of pollution from ships is increasing. Satellite observations of NO2 and HCHO by GOME and SCIAMACHY have been used to identify shipping emissions mainly in the Indian Ocean, where high vessel densities and low background pollution levels facilitate the detection of small signals. With the better spatial coverage of recent satellite instruments such as GOME-2 and OMI, the statistics improved and better detection limits can now be achieved. In this study, three years of GOME-2 data of NO2 have been systematically examined for shipping signals. Compared to previous studies, additional shipping tracks could be identified in the NO2 maps. Comparison with SCIAMACHY measurements shows interesting changes in the paths taken by the ships in the Gulf of Aden and the Indian Ocean. The observed patterns in ship emissions will be discussed with respect to reported vessel densities and GOME-2 measurement uncertainties.

Richter, Andreas; Hilboll, Andreas; Zien, Achim; Burrows, John P.

2010-05-01

230

Alaskan mountain glacial melting observed by satellite gravimetry  

NASA Astrophysics Data System (ADS)

We use satellite gravity measurements from the Gravity Recovery and Climate Experiment (GRACE) as an indication of mass change to study potential long-term mountain glacial melting in southern Alaska and West Canada. The first 3.5 yr of GRACE monthly gravity data, spanning April 2002-November 2005, show a prominent glacial melting trend in the mountain regions around the Gulf of Alaska (GOA). GRACE-observed surface mass changes correlate remarkably well with available mass balance data at Gulkana and Wolverine, two benchmark glaciers of the U.S. Geological Survey (USGS), although the GRACE signals are smaller in magnitude. In addition, terrestrial water storage (TWS) changes estimated from an advanced land surface model show significant mass loss in this region during the same period. After correcting for the leakage errors and removing TWS contributions using model estimates, we conclude that GRACE-observed glacial melting in the GOA mountain region is equivalent to ˜ - 101 ± 22 km 3/yr, which agrees quite well with the assessment of ˜ - 96 ± 35 km 3/yr based on airborne laser altimetry data, and is consistent with an earlier estimate based on the first 2 yr of GRACE data. This study demonstrates the significant potentials of satellite gravity measurements for monitoring mountain glacial melting and regional climate change.

Chen, J. L.; Tapley, B. D.; Wilson, C. R.

2006-08-01

231

Communications satellite system for Africa  

NASA Astrophysics Data System (ADS)

Earlier established requirement estimations were improved upon by contacting African administrations and organizations. An enormous demand is shown to exist for telephony and teletype services in rural areas. It is shown that educational television broadcasting should be realized in the current African transport and communications decade (1978-1987). Radio broadcasting is proposed in order to overcome illiteracy and to improve educational levels. The technical and commercial feasibility of the system is provided by computer simulations which demonstrate how the required objectives can be fulfilled in conjunction with ground networks.

Kriegl, W.; Laufenberg, W.

1980-09-01

232

Determination of the reference frames deflections from optical observations of GNSS satellites  

NASA Astrophysics Data System (ADS)

Optical observations of navigation satellites were carried out at Terskol observatory during 2007-2010 with the aim to determine the deflection angles between GPS and GLONASS dynamical reference frames. There were three different observations strategies: celestial equator crossing, intersection of visible satellite paths, occultation of astrometric stars with the satellite. We present methodology of observation, data processing and the first results.

Choliy, V. Ya.; Zhaborovskyy, V. P.; Taradiy, V.; Rykhlova, L.

2011-01-01

233

Interkosmos: Summer School for Observers with Laser Satellite Rangefinders.  

National Technical Information Service (NTIS)

Papers are presented which deal with the theory, instruments, and techniques of satellite rangefinding using laser methods. The topics covered include: the first INTERKOSMOS laser satellite rangefinder, digital measurement of time intervals, the time base...

P. Navara

1975-01-01

234

Optical design of resource satellite system  

NASA Astrophysics Data System (ADS)

The optical system of an infrared multi-spectrum scanner used on the resource satellite is presented in this paper. The principles of spectrum-dividing and imaging, the designing of optical system, the optimization of the assemblage and the adjusting of relay optical system are discussed. According to the general principles of infrared systems, R-C system is used in designing of the primary optical system. There are two methods to design the relay optical system, one of which consists of a complex prism and the other uses a binary optical element. The results and imaging quality of the two methods generated by ZEMAX are given. In the system using complex prism, each wavelength band consists of an R-C system. The diffractive system uses diffractive-refractive hybrid systems to divide spectrum, image and achromatize. The results show that the image quality of the designed system is good enough to meet the practical requirements.

Cao, Yinhua; Li, Lin; Liu, Jiaguo; Liu, Yufeng; Huang, Yifan

2005-02-01

235

Military implications of a satellite power system  

NASA Astrophysics Data System (ADS)

If a satellite power system (SPS), such as is described in the NASA Reference Design Report, were to be undertaken to provide significant quantities of power to the United States and perhaps to other countries as well, significant military implications would ensue. These would arise, first, from the possible uses of such satellites and supporting systems as weapons or as supportive elements of other military systems, and, second, from the necessity of ensuring the security of such important economic assets in space. This paper summarizes some of the highlights of an extensive assessment of the military threats posed by SPS, the vulnerabilities of the Reference Design SPS, and potential safeguards against these threats and vulnerabilities. It is found that no threat issues have been revealed which cannot be mitigated by a judicious combination of safeguards.

Vajk, J. P.; Stutzke, R. D.; Salkeld, R.; Driggers, G. W.; Stine, G. H.

236

Assessing the quality of the snow model used in the European Flood Awareness System (EFAS) against MODIS satellite observations over 8 years  

NASA Astrophysics Data System (ADS)

The European Flood Alert System is under development at the European Commission Joint Research Centre since 2003 to foster international information exchange on early flood warning within Europe. The aim of EFAS is to provide catchment-wide flood forecasts indicating the probability of upcoming events between 3-10 days in advance with emphasis on transnational river basins. EFAS is designed to use full sets of Ensemble Prediction Systems (EPS) in the short- and medium term. EFAS consists of a rainfall-runoff model with a routing component (LISFLOOD) that is set-up on a 5km grid for entire Europe and runs in pre-operational model twice a day. The LISFLOOD model also includes a snow model based on a degree-day scheme. For this, each pixel is divided in 3 zones in order to represent the heterogeneity of the area regarding altitude. Then, snow is melt according to the air temperature, the amount of rainfall, and a calibrated snowmelt rate. The aim of this study is to compare the snow simulated by the LISFLOOD model (in fact the snow cover fraction) to the observed MODIS Snow Cover Area data. The period of this study is July 2002 - June 2010 and the area covers the entire Europe. For this work, the LISFLOOD model is forced by observations, not by forecasts, which means that the initial states of EFAS are in fact analyzed. A first comparison has been performed, between the version of the LISFLOOD model previously used in EFAS (until November 2011), and the current version. For the new version, better meteorological input (precipitation and temperature) were used, and the snow model has been improved (artifact to mimic glaciers, better distribution of the three altitudinal zones - Gaussian instead of linear-, and seasonal variation of the snowmelt rate). This comparison showed the important overall improvement of agreement for the new LISFLOOD version between the model and the observed MODIS data. The second step was to measure the impact of some of the important parameters related to snow that LISFLOOD uses in its current version: the temperature at which the snow melts (by default 1°C), the temperature that discriminates precipitation between rainfall and snowfall (1°C), and the amplitude of the seasonal variation of the snowmelt rate (1°C). We will try to isolate conditions on which the default values of these parameters are valid, and on which they could be improved (sun exposure for instance).

Thirel, G.; Burek, P.

2012-04-01

237

Satellite Observations For Calibration of Ground Radar Networks  

NASA Astrophysics Data System (ADS)

Calibration differences between weather service ground radars is one source of error that can lead to bias in quantitative precipitation estimates. In the U.S., calibration differences among Weather Service Radar-1988 Doppler (WSR-88D) radars are know to vary by up to several decibels in reflectivity. Such differences have been shown to cause significant radar-to-radar observation differences, and can lead to significant error in precipitation estimates. The calibration of 21 WSR-88D radars in the southeast U.S. was assessed using methods developed for NASA's Global Precipitation Mission (GPM) Validation Network (VN) prototype. The VN performs geometric matching of Precipitation Radar (PR) data from the Tropical Rainfall Measuring Mission (TRMM) satellite to ground radars. The VN geometric matching method averages PR reflectivity (both raw and attenuation corrected) and rain rate, and ground radar (GR) reflectivity at the geometric intersection of the PR rays with the individual GR elevation sweeps. The algorithm thus averages the minimum PR and GR sample volumes needed to ''matchup'' the spatially coincident PR and ground radar data types. This geometric matching method has been demonstrated to out-perform gridding techniques by providing better estimates of GR-to-PR bias. TRMM PR data were used as the calibration reference because analyses of the PR performance estimated the instrument calibration to be stable and accurate to within less than 1dBZ (3-sigma). The calibration accuracy of the 21 WSR-88D radars was assessed for the period of record from August 2006 to July 2011. For purposes of calibration assessments, the data were restricted to PR-GR match-up volumes >750m above the bright band in stratiform rain areas where PR radar attenuation is not at issue. Based on space and ground radar matchups, most WSR-88D radars were found to have a mean PR-GR bias of less than 1 dBZ. Several adjacent WSR-88D sites near or along the Gulf Coast between Louisiana and Florida (KLCH, KLIX, KSHV, KTBW, and KTLH) exhibit a PR-GR bias of -1 dBZ or lower, indicating a positive calibration offset of the WSR-88D radar. This set of Gulf Coast radars, KEVX and KMOB excepted, seem to be well calibrated to one another, but run ''hot'' compared to the other WSR-88D sites in the VN subset. Additional analyses were performed to examine the temporal variability of mean PR-GR reflectivity differences to identify ground radar calibration drift. Several sites (KAMX, KBYX, KCRP, and KMLB) show consistent, small biases with respect to the PR, indicating a stable calibration of these WSR-88D systems.

Schwaller, M.; Morris, K.

2011-12-01

238

Satellite reconnaissance  

Microsoft Academic Search

The potential of the observation equipment in remote sensing satellites is described. United States meteorology, land use and oceanography satellites and the major US Earth observation programs are listed. Imaging satellite systems are described such as: visible light and near infrared, thermal IR window, and microwave window. It is concluded that a geometrical resolution between 10 and 40 m can

G. P. Deloor

1984-01-01

239

Combination of different satellite observation data for ionosphere modelling  

NASA Astrophysics Data System (ADS)

Electromagnetic measurements from various satellite missions are influenced on their way through the ionosphere by free electrons and thus could be used to improve our knowledge on the distribution of electron density in this region of the earth atmosphere and to provide a tool for correcting other measurements. At DGFI a procedure for multi-dimensional ionospheric modelling has been developed. It consists of a given reference part (e.g. IRI2007) and an unknown corrections part expanded in terms of multi-dimensional base functions (e.g. B-splines). The corresponding series coefficients are calculated from satellite measurements by parameter estimation. To take advantage of the different characteristics of the various measurement techniques we do a joint adjustment of COSMIC/FORMOSAT-3 GNSS measurements together with ground based GNSS and measurements from dual-frequency radar altimetry. The weights of the different techniques are estimated by a variance component estimation (VCE). In this contribution we will introduce our model approach and present first results of the combination of different observation techniques. We will focus on vertical integrated electron density (vertical electron content, VTEC) models which will be compared to other VTEC maps available from a variety of institutions.

Dettmering, D.; Schmidt, M.; Zeilhofer, C.; Tsai, L.-C.; Zhang, J.; Bosch, W.; Shum, C. K.; Tseng, K. H.

2009-04-01

240

Teacher Effectiveness via Interactive Satellite: Preliminary Findings from Observation of Three Teachers over the TI-IN Interactive Satellite Network.  

ERIC Educational Resources Information Center

Communications satellites transmit live interactive television broadcasts from a host site classroom to small and geographically isolated rural high schools. Using the research on effective teaching practices, this study examined the effectiveness of instruction delivered by satellite. Researchers observed 15 hours of three courses (Computer…

Barker, Bruce O.; Patrick, Kenneth R.

241

Polarization aberration in resource satellite system  

NASA Astrophysics Data System (ADS)

Polarization aberration is one of the most important factors affecting the performance of optical systems, especially in systems which have many reflectors. The polarization response characters of the reflectors will change the polarization state of the incident light and the polarization aberration will affect the imaging quality of the system. In many resource satellites R-C reflective systems are often used in primary optical systems. The main elements of the R-C reflective systems are reflectors coated with thin films, so polarization aberration must be controlled to improve the imaging quality of the systems. In this paper ZEMAX software is used to realize the simulation of the optical system of a resource satellite and polarization analysis of the system is presented. According to the results of the polarization analysis, the whole optical system is optimized and the ways to control the polarization aberration are summarized. As a result of the study, a conclusion can be drawn that polarization is an important aspect in optical design. To achieve good imaging quality, polarization aberration must be controlled very well, moreover, optical thin film design should be considered while designing optical systems.

Zhang, Ying; Li, Lin; Huang, Yifan; Gao, Guangjun; Cao, Yinhua

2005-02-01

242

Satellite observations support to disaster monitoring: the operational use of COSMO-SkyMed constellation  

NASA Astrophysics Data System (ADS)

The aim of this work is to show some experiences recently made by ASI and DPC, with the collaboration of Italian research institutes and academies, in using satellite observations to monitor different steps of emergency management in Italy: the 2012 Emilia earthquakes and the 2012 seismic sequence in the Mt. Pollino area, the volcano Stromboli eruption, the floods occurred in Tuscany and Lazio. The effectiveness of the satellite observations contribution to the disaster management is to day in phase of demonstration, and the encouraging results obtained up to now rely not only on the maturity of the data processing and interpretation techniques (more exploited), but also on the coordination in accessing and programming satellites systems. During the past year, COSMO-SkyMed has been successfully used to acquire, in very short times, high quality images of disaster areas. When the emergency evolution made it necessary, after the set up the monitoring service went on several months. Our experience confirmed how important is the availability of consistent series of satellite data, acquired on disaster prone areas in order to enable and facilitate post-disaster activities. Moreover, some results have been made possible thanks to science oriented initiatives sponsored by ASI and to the long-lasting cooperation among DPC and the national research institutions. In general, to meet civil protection needs after a disaster, typical activities based on earth observation techniques, as rapid mapping, recovery and first evaluation of damage, require the following observation capabilities: • medium-to-high spatial resolution • high revisit time, coupled with large spatial and spectral coverage • night/daylight and all-weather observations • capability of very short response time and frequent revisit opportunities for the study area • availability of a good reference archive • access and provision of satellite data for operational purposes, based on well defined rules and procedures. The experience made shows how all these characteristics play a key role during real emergencies. Many players, each with its specific role but working as a single team, are involved in the emergency management: the Italian Space Agency, the national Department of Civil Protection, and the scientific institutions that are in charge to elaborate and interpret satellite data. The work done up to now shows the importance of coordination for a sustained access to data source, in order to meet the requirements of the disaster monitoring and fully exploit the satellite system capabilities. This experience paves the way for a more effective and enlarged use of satellite observations in the civil protection domain.

Candela, Laura; Cardaci, Chiara; Coletta, Alessandro; Corina, Angela; Di Bucci, Daniela; Giuliani, Roberta; Pagliara, Paola; Zoffoli, Simona; Boni, Giorgio

2013-04-01

243

Regional satellite systems - Required or redundant  

NASA Astrophysics Data System (ADS)

It is shown that the development of such regional satellite systems as the Arab League's Arabsat, the South American Aseta, and the ASEAN nations' Palapa II, will be redundant if Intelsat moves ahead with its expanded service options with multiple frequency and beam configurations. Attention is given to direct broadcast satellite systems and the geostationary platform concept, which would incorporate C-band high-volume trunking, meteorological data relay, interplatform link, and Ku-band TV distribution and could be constructed in orbit by the Space Shuttle. The platform concept offers antenna reflectors that could be utilized by many 'feeds' or multiple-phase arrays, permitting frequency reuse many hundreds of times over.

Filep, R.

1981-09-01

244

A digital satellite communications system for SPRINT  

NASA Astrophysics Data System (ADS)

Switched voice, digital data and private line traffic are scheduled to be implemented in 1984-1988 by a digital satellite system encompassing the Spacenet and Gstar satellites. This system features TDMA terminals operating at 60, 90, and 120 Mbps with 36, 54 or 72 MHz-bandwidth transponders, respectively. The network topology will identify two application types: that designated 'on-net', whose earth stations will be strategically located at major junctions of the existing microwave backbone, near the larger cities, and will carry long haul, heavy route traffic between those junctions; and that designated 'off-net', whose earth stations are located off the microwave backbone at smaller cities and will access the backbone, and thence the entire SPRINT network, via gateway earth stations located at major junction sites.

Pourmand, B.; Jacobs, A.

245

Improved Resolution and Image Separation (IRIS) Satellite: astronomical observations with a large occulting satellite  

NASA Astrophysics Data System (ADS)

Natural occultations have long been used to study sources on small angular scales, while coronographs have been used to study high contrast sources. We propose launching the Improved Resolution and Image Selection (IRIS) Satellite, a large steerable occulting satellite. IRIS will have several advantages over standard occulting bodies. IRIS woudl block over 99.8 percent of the visible light from an occulted point source. Because the occultation occurs outside both the telescope and the atmosphere, seeing and optical imperfections do not degrade this performance. If placed in Earth orbit, integration times of 160-1600 s can be achieved from most major telescope sites for objects in over 90 percent of the sky. Alternately, IRIS could be combined with a 2-4 meter space telescope at the Earth-Sun L2 point to yield very long integration times. Applications for IRIS include direct imaging of planets around nearby stars, and resolution of micro-lensed images of LMC and Galactic bulge stars into distinct image pairs. Resolution of microlensed stars would greatly improve our understanding of the massive compact halo objects comprising 20-90 percent of the mass of our galaxy. Direct imaging of planets, would enhance our understanding of star formation, formation of planetary systems, and perhaps ultimately help evaluate the probability of extraterrestrial life.

Copi, Craig J.; Starkman, Glenn D.

1998-08-01

246

Planetocentric versus heliocentric impacts in the Jovian and Saturnian satellite system  

Microsoft Academic Search

Readily applicable equations are derived for calculating the impact velocities, collision intervals, and cumulative crater frequencies in a satellite system for planetocentric and heliocentric impactors. Observed cumulative crater frequencies in the Saturnian satellite system and a sometimes observed lack of apex-antapex asymmetry of crater frequencies favor crater-producing projectiles orbiting initially in elliptic orbits round the parent planet (planetocentric impactors). On

G. P. Horedt; G. Neukum

1984-01-01

247

Earth observations satellite data policy: Process and outcome  

SciTech Connect

The National Aeronautics and Space Administration (NASA) develops, launches, and operates satellites to observe and monitor the Earth and its environment. This study categorizes each program based on the relationship between NASA and external organizations. A program can be an autonomous mission undertaken for NASA`s own constituency, or it can involve a client agency or a partner. These relationships affect how data policy decisions are made and implemented, and how the valuable output of NASA`s Earth observations satellites is managed. The process in NASA for determining which programs will be approved is very informal. Ideas and concepts surface and reach the consciousness of NASA management; if sufficient support is achieved, a proposal can move to the feasibility study phase and from there become an approved and funded mission. The handling of data can be an important consideration in generating political support for program approval. Autonomous programs tend to have decisions made at lower levels and documented informally or not at all. Data policy is part of routine implementation of programs and does not generally rise to the visibility of the agency head or congressional staff or the Executive Office of the President. Responsibility for data management for autonomous missions is retained at NASA centers. Client programs involve higher level decision makers, and are the subject of political interest because they cross agency boundaries. The data policy process includes presidential statements on data access. As part of the client relationship, NASA often provides resources to the client for data handling and analysis, and shares these responsibilities. Data policy for partner programs is the result of bargaining between the partners, either foreign government agencies or private companies.

Shaffer, L.R.

1994-12-31

248

Telecom 1: French domestic communications satellite system  

NASA Astrophysics Data System (ADS)

Services supplied by TELECOM 1, the components of the TELECOM 1 system, the industrial organization, and the project schedule are described. The TELECOM 1 system: provides broadband digital links between companies in France and neighboring states; routes telephone communications and television broadcasts between France and its overseas territories; and handles government communications. A ground control and monitoring station operates the TDMA system and supervises ground station performance, synchronizes the bursts from each station, surveys the repeaters and provides the billing. Three satellites, including one spare, developed from OTS, MARECS and ECS designs, are launched by Ariane.

1981-05-01

249

An expert system for geostationary orbit satellite breakdown analysis  

Microsoft Academic Search

Two prototypes of expert systems for breakdown diagnosis on synchronous orbit satellites are described. The first prototype monitors the attitude and orbit control system of the French Telecom 1 satellite. The second prototype monitors the Power Conditioning Subsystem (PCS) of the TDF1 satellite. Both prototypes are intended for use by operation engineers in flight control centers. Both systems use the

L. Gibet

1990-01-01

250

Fuel models and fire potential from satellite and surface observations  

USGS Publications Warehouse

A national 1-km resolution fire danger fuel model map was derived through use of previously mapped land cover classes and ecoregions, and extensive ground sample data, then refined through review by fire managers familiar with various portions of the U.S. The fuel model map will be used in the next generation fire danger rating system for the U.S., but it also made possible immediate development of a satellite and ground based fire potential index map. The inputs and algorithm of the fire potential index are presented, along with a case study of the correlation between the fire potential index and fire occurrence in California and Nevada. Application of the fire potential index in the Mediterranean ecosystems of Spain, Chile, and Mexico will be tested.

Burgan, R. E.; Klaver, R. W.; Klarer, J. M.

1998-01-01

251

Generation of global surface albedo data set from archived geostationary satellite observations  

NASA Astrophysics Data System (ADS)

Monitoring and understanding climate changes of the Earth require the generation of long-term and consistent global data set from observation. In this context, geostationary satellite observations could play a significant role thanks to the long duration of the missions and the corresponding archives, often covering more than two decades. In particular, their frequent cycle of acquisition can be used to document the anisotropy of the surface and thereby surface albedo. Hence, EUMETSAT has developed the so-called Geostationary Surface Albedo (GSA) algorithm based on an algorithm proposed by Pinty et al. This algorithm is capable of processing observations of any geostationary satellites to derive the surface albedo, accounting for the effects of the surface anisotropy and the aerosols. This algorithm has been implemented in the Operational reprocessing facility of EUMETSAT in order to generate reliable albedo dataset starting from the 1982, through the analysis of data acquired by the six different Meteosat first generation platforms for the satellites located at the 0 degree longitude. Observations acquired by the EUMETSAT satellites located over the Indian Ocean since 1998 have also been processed. The GSA algorithm has also been implemented at the Japanese Meteorological Agency (JMA) for the processing of the GMS-5 archive. EUMETSAT has the responsibility to integrate all these level-2 products into a unique level-3 broadband surface albedo product. The evaluation of this global surface albedo product relies on the comparison of pairs of contemporaneous products generated from two adjacent satellites sharing a common observation area and with the equivalent MODIS product. This latter comparison has revealed that both products agree within 10% relative difference. This study is performed under the framework of the Co-Ordinated Processing of Environmental Satellite Data for Climate Monitoring (SCOPE-CM) project, a WMO initiative to establish a network of facilities ensuring continuous and sustained provision of high-quality satellite products related to the Essential Climate Variables (ECV), on a global scale, responding to the requirements of the Global Climate Observing system (GCOS). It demonstrates the contribution of operational weather satellites into the generation of consistent time series of surface albedo.

Govaerts, Yves; Okuyama, Arata; Latanzio, Alessio

2010-05-01

252

Sensing the Earth using Global Navigation Satellite System signals  

NASA Astrophysics Data System (ADS)

International Workshop on GNSS Remote Sensing for Future Missions and Sciences; Shanghai, China, 7-9 August 2011 The Global Navigation Satellite System (GNSS) has been widely used in navigation, positioning, and geoscience applications. Recently, the versatility of GNSS as a new remote sensing tool has been demonstrated with the use of refracted, reflected, and scattered GNSS signals to sound the atmosphere and ionosphere, ocean, land surfaces (including soil moisture), and cryosphere. Existing GPS radio occultation (RO) missions—e.g., the U.S.-Argentina SAC-C, German Challenging Minisatellite Payload (CHAMP), U.S.-Germany Gravity Recovery and Climate Experiment (GRACE), Taiwan-U.S. Formosa Satellite Mission-3/Constellation Observing System for Meteorology, Ionosphere, and Climate (FORMOSAT-3/COSMIC) satellites, German TerraSAR-X satellite, and European MetOp—together with groundbased GNSS observations, have provided precise and high-resolution information on tropospheric water vapor, pressure, temperature, tropopause parameters, ionospheric total electron content, and electron density profiles. GNSS signals reflected from the ocean and land surface can determine the ocean height, ocean surface wind speed and wind direction, soil moisture, and ice and snow thickness. With improvement expected due to the next generation of multifrequency GNSS systems and receivers, and new space-based instruments tracking GNSS reflected and refracted signals, new scientific applications of GNSS are expected in the near future across a number of environmental remote sensing fields.

Jin, Shuanggen; Rizos, Chris; Rius, Antonio

2011-11-01

253

Satellite system for tactical MILSATCOM applications  

NASA Astrophysics Data System (ADS)

The communication requirements for continuous MILSATCOM service can be met by augmenting the current and planned MILSATCOM systems with a functionally simple, low-cost, maneuverable, user-dedicated satellite constellation for tactical applications (TACSAT) whose payloads are under direct control of the theater Commander in Chief (CINC). A perspective on moderately hardened, low-cost SHF and EHF satellites that have minimal impact on the ground infrastructure to satisfy such missions is presented. The communication and coverage requirements of the theater CINCs are discussed, followed by an SHF versus EHF comparison. Four different SHF payloads (including an enhanced DSCS replenishment) and two EHF payloads are evaluated. The spacecraft systems to integrate these payload options, including the spacecraft, launch vehicles, and ground segment, are addressed. Parametric trade studies of communication capacity and satellite life/maneuverability are presented. Ground segment operational scenarios based on a computer simulation of ground mobile forces (GMF) network for a given connectivity are presented. The various architectures proposed are analyzed and compared by generating a figure-of-merit unit per 1 MHz transponder capacity for each option.

Vaddiparty, S. V.; Monte, P. A.; Pidgeon, D. J.; Louie, M.

254

Improved satellite-based emergency alerting system  

NASA Astrophysics Data System (ADS)

Rapid-onset natural hazards have claimed more than 2.8 million lives worldwide in the past 20 years. This category includes such events as earthquakes, landslides, hurricanes, tornadoes, floods, volcanic eruptions, wildfires, and tsunamis. Effective hazard mitigation is particularly difficult in such cases, since the time available to issue warnings can be very short or even nonexistent. A general approach to mitigate the effects of these disasters was demonstrated in 1988 that included preevent emergency planning, real-time hazard assessment, and rapid warning via satellite communication links. This article reports on improvements in this satellite-based emergency alerting communication system that have reduced the response time from 87 to 17 sec and expanded the broadcast coverage from 40 percent to 62 percent of the earth's surface.

Bernard, E. N.; Milburn, H. B.

1991-12-01

255

Intelligent Satellite Data Information System (ISIS)  

NSDL National Science Digital Library

The Intelligent Satellite Data Information System is "the central user interface" to the data archived at the German Remote Sensing Data Center (DFD) and offers descriptions of (and facilitates access to) numerous online resources. For general information about remote sensing and the ISIS site, see the News section (including announcements of upcoming electronic resources), the Thesaurus (containing synonyms for about 7,000 important scientific terms), and the Infoboard section (including tutorials in English and German, a list of data products, and an array of links to related resources). The ISIS homepage also offers a new WWW-Gateway to the Data, in which users may search or browse Earth Science data "from various participating archive centers around the globe." For the latest satellite images, see the Special section, which features spectacular color images of The weather in Europe, Temperatures and vegetation, and Ozone-concentration, electron-density and chlorophyll-content.

256

A collection of Galilean satellite eclipse observations, 1652-1983. I  

NASA Astrophysics Data System (ADS)

The most complete collection of extant Galilean satellite eclipse observations since 1652 has been assembled. Since many of the old data exist only in manuscript form or in archaic forms (e.g., apparent time, local time, sidereal time, Julian calendar, etc.), they have been reduced to a modern proleptic Universal Time (UT) system (where the day begins at midnight) on the Gregorian calendar. Many of the data had been presumed to be lost for more than a century and since they are very valuable for discussion of long-term effects on the satellites, they are presented here for present as well as future generations of astronomers. The data are invaluable for long-term studies of Galilean satellite motion and for the determination of physical parameters.

Lieske, J. H.

1986-01-01

257

Global Observing Systems Information Center (GOSIC)  

NSDL National Science Digital Library

This extensive site was established at the College of Marine Studies of the University of Delaware, to provide a single entry point for users of data and information produced by three global observing systems. The Global Climate Observing System (GCOS) focuses on satellite and in situ observations for climate in the atmospheric, oceanic, and terrestrial domain. Ocean Observing Systems for climate are planned jointly with the Global Ocean Observing System (GOOS). Terrestrial climate observing systems are planned jointly with the Global Terrestrial Observing System (GTOS). The site features data, maps, diagrams, data matrices, and data flow diagrams.

Gosic

258

NOAA's future earth observations from advanced GOES satellites  

Microsoft Academic Search

IAF-95-B.2.01This paper describes early progress made toward defining the next generation of GOES satellites. These satellites could be first launched in 2008. The paper is divided into four main sections. First, the actual process of starting a new satellite program is presented as it has occurred during the past two years. NOAA formed 12 internal teams to determine requirements and

Gerald Dittberner; Ronald Gird; Roger Heymann; Edward Howard; Steve Kirkner; Louis Uccellini

1996-01-01

259

Whistler-triggered emissions observed by ISIS satellites  

SciTech Connect

VLF emissions triggered by whistlers are often observed at middle and high latitudes in the topside ionosphere by ISIS satellites. Most of them are so-called LHR emissions lasting for a few seconds. Latitudinal distributions of the occurrence rate for the whistler-triggered emissions in the topside ionosphere have been obtained by using VLF electric field data received from the ISIS 1 and 2 satellites at Kashima station, Communications Research Laboratory, Japan. These VLF emissions are classified into two groups according to the type of whistlers, i.e., ducted whistlers with a continuous trace over the full frequency range of the spectrum and nonducted whistlers without a complete trace below f{sub LHR}. The latitudinal distribution of the occurrence rate for emissions triggered by ducted whistlers is considerably different from that for emissions triggered by nonducted whistlers, especially at high latitudes. The occurrence rate for the emissions by nonducted whistlers is distributed rather randomly in latitude between L = 2.0 and L = 4.2. The occurrence rate for emissions by ducted whistlers increases with latitudes between L = 1.5 and L = 2.9, and it attains a maximum of 0.33 at L = 2.7. It then abruptly drops to 0.1 at L = 3.0, and it remains below 0.1 between L = 3.0 and L = 4.0. The decrease of the occurrence rate for emissions by ducted whistlers at L = 3.0 seems to be caused by the decrease of the radiation belt electron flux near the slot region. These results suggest that the VLF emissions triggered by ducted whistlers in the topside ionosphere are generated by the cyclotron resonant interaction of ducted whistlers with the magnetospheric electrons near the geomagnetic equatorial plane.

Nakamura, Y.; Ondoh, T. (Communications Research lab., Tokyo (Japan))

1989-01-01

260

Trend detection in satellite observations of formaldehyde tropospheric columns  

NASA Astrophysics Data System (ADS)

Being an intermediate product in the oxidation of a large number of non-methane volatile organic compounds (NMVOCs), formaldehyde (H2CO) is a useful indicator of biogenic, pyrogenic and anthropogenic hydrocarbon emissions. We present the first trend study performed on H2CO satellite columns, retrieved from the GOME and SCIAMACHY instruments between 1997 and 2009. A linear model with a seasonal component is used to fit the time series of monthly averaged columns. The error and statistical significance of the inferred trends are estimated. The study focuses on Asia but results are also provided for large cities worldwide. Statistically significant positive trends of formaldehyde columns are observed over northeastern China (4% yr-1) and India (1.6% yr-1), related to strong increases in anthropogenic NMVOC emissions, whereas negative trends of about -3% yr-1 are observed over Tokyo as well as over cities of the northeast U.S. urban corridor as a result of effective pollution regulation measures.

De Smedt, I.; Stavrakou, T.; Müller, J.-F.; van der A, R. J.; Van Roozendael, M.

2010-09-01

261

Establishing the Antarctic Dome C community reference standard site towards consistent measurements from Earth observation satellites  

USGS Publications Warehouse

Establishing satellite measurement consistency by using common desert sites has become increasingly more important not only for climate change detection but also for quantitative retrievals of geophysical variables in satellite applications. Using the Antarctic Dome C site (75°06?S, 123°21?E, elevation 3.2 km) for satellite radiometric calibration and validation (Cal/Val) is of great interest owing to its unique location and characteristics. The site surface is covered with uniformly distributed permanent snow, and the atmospheric effect is small and relatively constant. In this study, the long-term stability and spectral characteristics of this site are evaluated using well-calibrated satellite instruments such as the Moderate Resolution Imaging Spectroradiometer (MODIS) and Sea-viewing Wide Field-of-view Sensor (SeaWiFS). Preliminary results show that despite a few limitations, the site in general is stable in the long term, the bidirectional reflectance distribution function (BRDF) model works well, and the site is most suitable for the Cal/Val of reflective solar bands in the 0.4–1.0 µm range. It was found that for the past decade, the reflectivity change of the site is within 1.35% at 0.64 µm, and interannual variability is within 2%. The site is able to resolve calibration biases between instruments at a level of ~1%. The usefulness of the site is demonstrated by comparing observations from seven satellite instruments involving four space agencies, including OrbView-2–SeaWiFS, Terra–Aqua MODIS, Earth Observing 1 (EO-1) – Hyperion, Meteorological Operational satellite programme (MetOp) – Advanced Very High Resolution Radiometer (AVHRR), Envisat Medium Resolution Imaging Spectrometer (MERIS) – dvanced Along-Track Scanning Radiometer (AATSR), and Landsat 7 Enhanced Thematic Mapper Plus (ETM+). Dome C is a promising candidate site for climate quality calibration of satellite radiometers towards more consistent satellite measurements, as part of the framework for climate change detection and data quality assurance for the Global Earth Observation System of Systems (GEOSS).

Cao, C.; Uprety, S.; Xiong, J.; Wu, A.; Jing, P.; Smith, D.; Chander, G.; Fox, N.; Ungar, S.

2010-01-01

262

Influence of cloud properties on satellite total ozone observations  

Microsoft Academic Search

Clouds represent one of the most important atmospheric factors that can significantly reduce the accuracy of satellite total ozone column (TOC) data. The influence of clouds on the TOC retrieval from satellites is usually assessed by means of theoretical studies using radiative transfer models. In contrast, few experimental results were found in the literature about the effects of the cloud

Manuel Antón; Diego Loyola

2011-01-01

263

Air Density in the Upper Atmosphere from Satellite Orbit Observations  

Microsoft Academic Search

FROM the rate of change of period of a satellite, it is possible to derive the density of the atmosphere at the altitude of the perigee of the orbit. Now that some ten successful satellite launchings have taken place, giving orbits with various perigee heights, the variation of air density with height can be derived over a considerable range of

G. V. Groves

1959-01-01

264

Observations of the ionosphere by the Ionosphere Sounding Satellite \\/ISS  

Microsoft Academic Search

The design and electronics of a global ionospheric sounding satellite are described. The satellite missions consisted of studying the global distribution of ionospheric critical frequencies and the virtual range vs frequency characteristics of the sounding echo; study of the global distribution of radio noise intensities and the occurrence frequency of atmospherics; study of such plasma parameters as electron and ion

N. Matuura; R. Nishizaki

1977-01-01

265

Communication Systems through Artificial Earth Satellites (Selected Pages).  

National Technical Information Service (NTIS)

Contents: Principles of the Construction of Communication Systems Through Artificial Earth Satellites; Motion of Satellites and Duration of Periods of Communication; Signal Level at the Input of Receiver; Noise Level at the Input of a Receiver; Calculatio...

N. I. Kalashnikov

1987-01-01

266

Satellite observations of large power plants and megacities from GOSAT  

NASA Astrophysics Data System (ADS)

Fossil fuel CO2 emissions are a major source of CO2 to the global carbon cycle over decadal time scales and international efforts to curb those missions are required for mitigating climate change. Although emissions from nations are estimated and reported to help monitor their compliance of emission reductions, we still lack an objective method to monitor emissions directly. Future carbon-observing space missions are thus expected to provide an independent tool for directly measuring emissions. We proposed and have implemented satellite observations specifically over intense large point sources (LPS), including large fossil-fueled power plants and megacities, worldwide (N > 300) using the Japanese Greenhouse Gases Observing SATelllite (GOSAT). Our target LPS sites have been occasionally included in the observation schedule of GOSAT and the measurements are made using the target observation mode. This proposal was officially accepted by the GOSAT project office and we have attempted to use these data to detect signatures of man-made greenhouse gas emissions. We have submitted our locations of interest on a monthly basis two month prior to observation. We calculated the X_CO2 concentration enhancement due to the LPS emissions. We analyzed GOSAT X_CO2 retrievals from four research groups (five products total): the National Institute for Environmental Studies (NIES) (both the NIES standard Level 2 and NIES-PPDF products), the NASA Atmospheric CO2 from Space (ACOS) team (ACOS Level 2 product), the Netherlands Institute for Space Research (SRON)/Karlsruhe Institute of Technology, Germany (RemoTeC), and the University of Leicester, UK (Full-Physics CO2 retrieval dataset). Although we obtained fewer retrieved soundings relative to what we requested (probably due to geophysical difficulties in the retrievals), we did obtain statistically significant enhancements at some LPS sites where weather condition were ideal for viewing. We also implemented simulations of enhanced X_CO2 using a global Eulerian-Lagrangian coupled atmospheric transport model (GELCA) and a high-resolution fossil fuel emissions dataset (Odiac). Odiac includes emissions information on the power plants requested in our target observations. Our model simulations tend to underestimate the enhancements, but showed good correlation with observed enhancements.

Oda, Tom; Maksyutov, Shamil; Boesch, Hartmut; Butz, Andre; Ganshin, Alexander; Guerlet, Sandrine; Parker, Robert; O'Dell, Chris; Oshchepkov, Sergey; Yoshida, Yukio; Zhuravlev, Ruslan; Yokota, Tatsuya

2013-04-01

267

Assessing the impact of satellite, aircraft, and surface observations on CO2 flux estimation using an ensemble-based 4-D data assimilation system  

Microsoft Academic Search

A data assimilation system is developed to estimate surface CO2 fluxesGOSAT XCO2 and CONTRAIL aircraft data provide strong additional constraintsSimultaneous use of various type data improves the flux estimates globally

Kazuyuki Miyazaki; Takashi Maki; Prabir Patra; Takakiyo Nakazawa

2011-01-01

268

Status and Future of Global Flood and Landslide Nowcasts and Forecasts Using Satellite Precipitation Observations (Invited)  

NASA Astrophysics Data System (ADS)

The advent of quasi-global, real-time precipitation analyses has lead to the reality of running global hydrological models and algorithms for the estimation of the occurrence of floods and rain-induced landslides. These calculations provide information useful to national and international agencies in understanding the intensity, timeline and impact on populations of these significant hazard events. The quality of such applied hydrological estimations should improve with time due to continuation and improvement of multi-satellite precipitation observations through the Global Precipitation Measurement (GPM) program and the further development of the models and algorithms. This talk will summarize the results from the NASA-based, real-time flood and landslide nowcasts and forecasts and describe directions for improving results going into the GPM era. Global flood and landslide estimation systems have been running in real-time at 0.25° latitude/longitude resolution using multi-satellite rainfall analyses for several years, with results available through the TRMM website (trmm.gsfc.nasa.gov). Published evaluations of the current system indicate useful skill in comparison with global event inventories. The evaluations indicate higher skill for larger rainfall systems (e.g., tropical cyclone landfall vs. flash flood). This result is reasonable considering the resolution of the rainfall information (0.25° and 3-hr) and the resolution of the current models/algorithms (0.25°). Improvements over the next few years will include 1) better precipitation analyses utilizing space-time interpolations that maintain accurate intensity distributions, 2) improved rain estimation for shallow, orographic rainfall systems and some types of monsoon rainfall, 3) higher resolution landslide algorithms with combined physical/empirical approaches, 4) higher resolution flood models with accurate routing and regional calibration, and 5) use of satellite soil moisture for more accurate pre-conditions. In addition, the satellite rainfall and surface observations will be integrated with regional atmospheric models to provide enhanced information for the hydrologic calculations. One example of an experimental step in the use of atmospheric models is the linking of the satellite rainfall to global numerical rainfall forecasts to extend the usefulness of the flood and landslide forecasts. In this example of potential enhancement the model rainfall is adjusted by the satellite observations to provide improved rainfall amounts and flood forecasts. In addition recent results with an improved global hydrological model running at 1/8th degree resolution will be discussed that are shown to produce more realistic evolution of flooding events and more detailed information. These improvements are a few steps in a continuous pathway to simultaneously improve satellite rainfall estimates and their applications to increase the accuracy of hazard estimation and forecasts on a global basis.

Adler, R. F.; Wu, H.; Kirschbaum, D. B.; Policelli, F.; Hong, Y.; Tian, Y.; Pierce, H.

2010-12-01

269

The design of the optical system of the second-generation satellite laser ranging system  

NASA Astrophysics Data System (ADS)

This paper deals with the characteristics of the design of the optical system of the second-generation satellite laser ranging system. The figures of the primary optical systems and the image quality of the main optical path are shown. At Shanghai Observatory, observations have been carried out with this system since Oct.1983, with which the good results have been obtained.

Yu, Erhui; Shen, Hongjun

270

Ionospheric and plasmaspheric effects in satellite navigation systems  

Microsoft Academic Search

A satellite navigation concept requires determination of time (or phase) delays that satellite-emitted signals experience when traversing the distance between satellite and observer. A pulse propagating this distance is slowed down somewhat from its free space velocity-by an amount directly proportional to the total number of free electrons (TEC) along its path. Ranging accuracy requirements mandate compensation for this additional

H. Soicher

1977-01-01

271

Global anthropogenic aerosol direct forcing derived from satellite and ground-based observations  

Microsoft Academic Search

A global estimate of the direct effects of anthropogenic aerosols on solar radiation in cloudy skies is obtained by integrating satellite and ground-based observations with models of aerosol chemistry, transport, and radiative transfer. The models adopt global distribution of aerosol optical depths (from MODIS), clouds, water vapor, ozone, and surface albedo from various satellite climatology. Gaps and errors in satellite

Chul Eddy Chung; V. Ramanathan; Dohyeong Kim; I. A. Podgorny

2005-01-01

272

A Quantitative Explanation of the Observed Population of Milky Way Satellite Galaxies  

Microsoft Academic Search

We revisit the well known discrepancy between the observed number of Milky Way (MW) dwarf satellite companions and the predicted population of cold dark matter (CDM) subhalos, in light of the dozen new low-luminosity satellites found in imaging data from the Sloan Digital Sky Survey (SDSS) and our recent calibration of the SDSS satellite detection efficiency, which implies a total

Sergey E. Koposov; Jaiyul Yoo; Hans-Walter Rix; David H. Weinberg; Andrea V. Macciņ; Jordi Miralda Escudé

2009-01-01

273

Evaluation of methods to derive green-up dates based on daily NDVI satellite observations  

Microsoft Academic Search

Bridging the gap between satellite derived green-up dates and in situ phenological observations has been the purpose of many studies over the last decades. Despite substantial advancements in satellite technology and data quality checks there is as yet no universally accepted method for extracting phenological metrics based on satellite derived vegetation indices. Dependent on the respective method derived green-up dates

Daniel Doktor

2010-01-01

274

Vertical Component of Satellite Navigation Systems  

NASA Astrophysics Data System (ADS)

The altitude is one of four coordinates of the user's position obtained from Satellite Navigation System (SNS) measurements. The distributions (in per cent) of VDOP coefficient value for different constellations of three SNS - GPS, GLONASS and Galileo - for different masking elevation angles for different user's latitudes are presented in the paper. The results of the measurements of GPS position and vertical accuracy in mode "3D" and position accuracy in mode "2D" for different GPS receivers and different receiver's antenna heights are demonstrated also. Additionally the use of vertical component of SNS in maritime navigation like the determination highly accurate sea-floor depths is presented.

Januszewski, Jacek

2010-01-01

275

Ship satellite-navigation systems (2nd revised and enlarged edition)  

NASA Astrophysics Data System (ADS)

Principles for the construction of automated satellite-based navigation systems for ships are reviewed. Topics covered include satellite navigation principles; the apparent motion of navigation satellites; the analysis of ephemeris observational errors; and the optimization of both equipment solutions and algorithms for navigation information processing. The present theoretical analysis is supported by results of mathematical modeling, by geometric interpretation of separate positions, and by examples of applications in the Transit and Navstar GPS systems.

Volosov, P. S.; Dubinko, Iu. S.; Mordvinov, B. G.; Shinkov, V. D.

276

Observations of A0535 + 26 with the SMM satellite  

SciTech Connect

An examination of archival data from the hard X-ray instruments on the Solar Maximum Mission (SMM) satellite has revealed a previously undetected outburst from the recurrent X-ray transient, A0535 + 26. The outburst occurred in June 1983 and reached a peak intensity of about 2 crab units in the energy range 32-91 keV. The outburst was detected over a span of 18 days, and the pulse period was observed to spin-up with an average rate of about -6 x 10 to the -8th s/s. A recently proposed model for A0535 + 26 has a pulsar powered by a short-lived accretion disk. A thin accretion disk model is fitted to the present data, assuming an orbital period of 111 days. Two solutions to the magnetic moment of the neutron star are derived. The slow rotator solution is more consistent with the model than the fast rotator, on the grounds that the conditions for the formation of an accretion disk are more favorable for a lower magnetic field strength. 30 refs.

Sembay, S.; Schwartz, R.A.; Orwig, L.E.; Dennis, B.R.; Davies, S.R. (New Hampshire Univ., Durham (USA) NASA, Goddard Space Flight Center, Greenbelt, MD (USA) Southampton Univ. (England))

1990-03-01

277

Satellite orbits, their observables, and tests of gravity theories  

NASA Astrophysics Data System (ADS)

Spectrometric detector complex ZINA-NT is intended to study a radiation conditions onboard satellite and characteristics of hard X-ray and gamma-ray fluxes from GRB, solar flares and to detect other non-stationary fluxes of cosmic gamma-rays. The advantages for using of this new detector for modification of present neutral particles detector on base of CsI(Tl) are discussed. Scintillation detectors based on BrilLanCe series crystal has a very small lighting time, an excellent energy resolution and light output, more intensive than devices based on CsI(Tl). Using of BrilLanCe series crystal instead of CsI(Tl) ones allows to detect both terrestrial gamma flashes and solar gamma ray bursts and flares with smaller time durations and intensities. Moreover, the counts rate linearity region of BrilLanCe detectors is extended up to 106 s-1 and it allows to observe a very intensive events. So, the using of such type of detector permits us the possibility to separate gamma-quanta and neutrons on the timescales less than 50 microseconds.

Laemmerzahl, Claus; Perlick, Volker

278

Multi-satellite Observations During Theta Aurora Evolution  

NASA Astrophysics Data System (ADS)

As the interplanetary magnetic field (IMF) rotates northward the number of convection reversal boundaries (CRB's) in the high-latitude ionospheric plasma flow increases from two to four (or more). Regions of sunward plasma flow at highest latitudes are characteristic of most convection signatures observed when the IMF has a northward component. In addition, some of the CRB's located at highest latitudes may be associated with precipitating particles on closed field lines and transpolar arcs (theta aurora). We present two case studies encompassing detailed relationships between plasma convection, field-aligned current, auroral emission, and particle precipitation boundaries. Electric and magnetic field and precipitating particle data are provided by DMSP and Astrid-2, while the Polar UVI instrument provides measurements of auroral emissions. Ace, Wind, and IMP-8 provide solar wind velocity, density and IMF measurements. Utilizing satellite data, the KTH model provides the high-latitude global potential pattern. We illustrate the influence of the IMF By component on theta aurora development by showing two events during which the theta originates on both the dawn and dusk sides of the auroral oval. Both theta then move across the entire polar region and become part of the opposite side of the auroral oval. Motion of the TPA and changes in the plasma convection pattern are correlated with the magnetosphere topology.

Cumnock, J. A.; Blomberg, L. G.; Heelis, R. A.

2001-12-01

279

Analysis of ground-based observations of the satellites of Saturn 1874 - 1988  

NASA Astrophysics Data System (ADS)

We have analyzed over 40,000 ground-based observations of the major satellites of Saturn (except Hyperion) by fitting analytical theories to the observations using the method of least-squares. In this paper, we use the observed-minus-computed residuals to compare the quality of the numerous sets of observations of the satellites made during the period 1874 to 1988.

Harper, D.; Taylor, D. B.

1994-04-01

280

Rocket and satellite observations of the local interstellar medium  

SciTech Connect

The purpose of the study described in this thesis was to obtained new information on the structure of the local interstellar medium (ISM). Two separate experiments using different instruments were used in this study. The first experiment employed a spectrometer with a spectral bandpass from 350-1150 {angstrom} which was placed at the focus of a 95 cm, f/2.8 normal incidence telescope flown on an Aries sounding rocket. The purpose of this experiment was to measure the interstellar absorption edges, due to neutral helium and neutral hydrogen, in the spectrum of a hot white dwarf. The hot white dwarf G191-B2B was observed for 87 seconds during the flight. Unfortunately, due to high pressure in the rocket, no scientifically useful data was obtained during the flight. The second experiment utilized the high resolution spectrometer on the International Ultraviolet Explorer satellite. The purpose of the experiment was to observe interstellar absorption lines in the spectrum of hot white dwarfs. A new method of determining the equivalent widths of absorption lines and their uncertainties was developed. The neutral hydrogen column density is estimated from the N I, Si II, and C II columns. Unfortunately, the uncertainties in the neutral hydrogen columns are very large, only two are constrained to better than an order of magnitude. High ionization species (N V, Si IV, and C IV) are seen in five of the stars. Upper limits to the temperature of the ISM are determined from the velocity dispersions. The temperature of the low ionization gas toward four of the stars is constrained to be less than 50,000 K.

Jelinsky, P.N.

1988-01-01

281

Optical observations of navigation satellites for determination of dynamical reference frames deflections  

NASA Astrophysics Data System (ADS)

Three summer sessions of optical observations of GNSS satellites were taken at Terskol observatory. GPS and GLONASS satellites were photographed among stars during their crossing of celestial equator. Optical coordinates were determined and used as reference values for intercomparison of dynamical reference frame of GPS satellites against the dynamical reference frame of GLONASS satellites. Possible differences of two dynamical reference frames may cause additional errors during joint processing of GNSS satellites observations and should be taken into account. Some results are presented. Sources of possible errors are analysed.

Choliy, Vasyl; Taradiy, Volodymyr; Rykhlova, Lidiya; Zhaborovsky, Vitaliy

2010-05-01

282

Antartic Sea Ice, 1973 - 1976: Satellite Passive-Microwave Observations.  

National Technical Information Service (NTIS)

Data from the Electrically Scanning Microwave Radiometer (ESMR) on the Nimbus 5 satellite are used to determine the extent and distribution of Antarctic sea ice. The characteristics of the southern ocean, the mathematical formulas used to obtain quantitat...

H. J. Zwally J. C. Comiso C. L. Parkinson W. J. Campbell F. D. Carsey

1983-01-01

283

Accessing Recent Trend of Land Surface Temperature from Satellite Observations  

NASA Astrophysics Data System (ADS)

Land surface temperature (LST) is an important element to measure the state of the terrestrial ecosystems and to study the surface energy budgets. In support of the land cover/land use change related international program MAIRS (Monsoon Asia Integrated Regional Study), we have collected the global monthly LST measured by MODIS since the beginning of the missions. The MODIS LST time series have ~11 years of data from Terra since 2000 and ~9 years of data from Aqua since 2002, which makes possible to study the recent climate, such as trend and variability. In this study, monthly climatology from two satellite platforms are calculated and compared. The spatial patterns of LST trends are accessed, focusing on the Asian Monsoon region. Furthermore, the MODIS LST trends are compared with the skin temperature trend from the NASA's atmospheric assimilation model, MERRA (MODERN ERA RETROSPECTIVE-ANALYSIS FOR RESEARCH AND APPLICATIONS), which has longer data record since 1979. The calculated climatology and anomaly of MODIS LST will be integrated into the online visualization system, Giovanni, at NASA GES DISC for easy access and use by scientists and general public.

Shen, S.; Leptoukh, G. G.; Romanov, P.

2011-12-01

284

GLOBAL PRECIPITATION CLIMATOLOGY FROM AMSU PASSIVE MICROWAVE SATELLITE OBSERVATIONS  

Microsoft Academic Search

1. ABSTRACT, This paper,presents a preliminary climatological study of global precipitation space-time statistics based,on a rain-rate estimation algorithm derived for the ,Advanced ,Microwave,Sounding ,Unit (AMSU) aboard the NOAA-15, -16, and -17 satellites, and aboard the NASA Aqua satellite with the Humidity Sounder for Brazil (HSB). The algorithm,uses ,brightness temperatures ,in 17 channels, principally in the 54-GHz oxygen band and the

Frederick W. Chen; David H. Staelin

285

NASA Now Minute: Orbital Mechanics: Earth Observing Satellites  

NASA Video Gallery

Dr. James Gleason, project scientist for NPP, explains what it takes for a satellite to stay in orbit, why there are different types of orbits, and why satellites orbit Earth at different altitudes depending on their purpose. NASA Now Minutes are excerpts from a weekly current events program available for classroom use at the NASA Explorer Schools Virtual Campus located at: › http://explorerschools.nasa.gov.

Heather Deiss

2011-11-01

286

Technical comparison of several global mobile satellite communications systems  

NASA Astrophysics Data System (ADS)

The era of satellite-based mobile satellite communications (MSC) systems started with the first MARISAT satellite which was launched into a geostationary orbit over the Pacific Ocean in 1976 to provide communications between ships and shore stations. The combination of high cost and unacceptably large equipment has kept the space-based MSC systems from appealing to the wider market of personal mobile communications. The progress made over the last ten years, however, in digital voice processing, satellite technology, and component miniaturization has resulted in the viability of satellite-based mobile satellite communications systems to meet the growing market in personal mobile communications using handsets similar to those currently in use with land-based cellular systems. Three of the more mature LEO/MEO satellite systems are addressed in this paper including GLOBALSTAR, Iridium, and Odyssey. The system architectures of each system are presented along with a description of the satellite and user handset designs and the multiaccess techniques employed. It will be shown that, although a number of similarities exist among the system addressed, each system is unique in a variety of significant design areas. It is concluded that the technical feasibility of satellite-based mobile satellite communications systems seems to be secure. It will be challenging, however, for the vendors to actually develop and deploy these systems in a cost effective, timely, and reliable way that meets a continually evolving set of requirements based upon a rapidly changing technology base.

Comparetto, Gary M.

287

Satellite power system (SPS) public outreach experiment  

SciTech Connect

To improve the results of the Satellite Power System (SPS) Concept Development and Evaluation Program, an outreach experiment was conducted. Three public interest groups participated: the L-5 Society (L-5), Citizen's Energy Project (CEP), and the Forum for the Advancement of Students in Science and Technology (FASST). Each group disseminated summary information about SPS to approximately 3000 constituents with a request for feedback on the SPS concept. The objectives of the outreach were to (1) determine the areas of major concern relative to the SPS concept, and (2) gain experience with an outreach process for use in future public involvement. Due to the combined efforts of all three groups, 9200 individuals/organizations received information about the SPS concept. Over 1500 receipients of this information provided feedback. The response to the outreach effort was positive for all three groups, suggesting that the effort extended by the SPS Project Division to encourage an information exchange with the public was well received. The general response to the SPS differed with each group. The L-5 position is very much in favor of SPS; CEP is very much opposed and FASST is relatively neutral. The responses are analyzed, and from the responses some questions and answers about the satellite power system are presented in the appendix. (WHK)

McNeal, S.R.

1980-12-01

288

Evaluation of snow models in terrestrial biosphere models using ground observation and satellite data: impact on terrestrial ecosystem processes  

Microsoft Academic Search

Snow is important for water management, and an important component of the terrestrial biosphere and climate system. In this study, the snow models included in the Biome-BGC and Terrestrial Observation and Prediction System (TOPS) terrestrial biosphere models are compared against ground and satellite observations over the Columbia River Basin in the US and Canada and the impacts of differences in

Kazuhito Ichii; Michael A. White; Petr Votava; Andrew Michaelis; Ramakrishna R. Nemani

2007-01-01

289

Progress in Near Real-Time Volcanic Cloud Observations Using Satellite UV Instruments  

NASA Astrophysics Data System (ADS)

Volcanic clouds from explosive eruptions can wreak havoc in many parts of the world, as exemplified by the 2010 eruption at the Eyjafjöll volcano in Iceland, which caused widespread disruption to air traffic and resulted in economic impacts across the globe. A suite of satellite-based systems offer the most effective means to monitor active volcanoes and to track the movement of volcanic clouds globally, providing critical information for aviation hazard mitigation. Satellite UV sensors, as part of this suite, have a long history of making unique near-real time (NRT) measurements of sulfur dioxide (SO2) and ash (aerosol Index) in volcanic clouds to supplement operational volcanic ash monitoring. Recently a NASA application project has shown that the use of near real-time (NRT,i.e., not older than 3 h) Aura/OMI satellite data produces a marked improvement in volcanic cloud detection using SO2 combined with Aerosol Index (AI) as a marker for ash. An operational online NRT OMI AI and SO2 image and data product distribution system was developed in collaboration with the NOAA Office of Satellite Data Processing and Distribution. Automated volcanic eruption alarms, and the production of volcanic cloud subsets for multiple regions are provided through the NOAA website. The data provide valuable information in support of the U.S. Federal Aviation Administration goal of a safe and efficient National Air Space. In this presentation, we will highlight the advantages of UV techniques and describe the advances in volcanic SO2 plume height estimation and enhanced volcanic ash detection using hyper-spectral UV measurements, illustrated with Aura/OMI observations of recent eruptions. We will share our plan to provide near-real-time volcanic cloud monitoring service using the Ozone Mapping and Profiler Suite (OMPS) on the Joint Polar Satellite System (JPSS).

Krotkov, N. A.; Yang, K.; Vicente, G.; Hughes, E. J.; Carn, S. A.; Krueger, A. J.

2011-12-01

290

An expert system for geostationary orbit satellite breakdown analysis  

NASA Astrophysics Data System (ADS)

Two prototypes of expert systems for breakdown diagnosis on synchronous orbit satellites are described. The first prototype monitors the attitude and orbit control system of the French Telecom 1 satellite. The second prototype monitors the Power Conditioning Subsystem (PCS) of the TDF1 satellite. Both prototypes are intended for use by operation engineers in flight control centers. Both systems use the same expert system programming software generator EMICAT development tool.

Gibet, L.

1990-10-01

291

Project 'VOLCANO': Electronics of tethered satellite system  

NASA Astrophysics Data System (ADS)

The main goal of the 'VOLCANO' project developed jointly by the Institute of Radio Engineering and Electronics and space concern 'ENERGIA' is experimental investigation of the current-voltage characteristics of the 'Collector-Boom-Emitter' system simulating the long Tethered Satellite System (TSS) in the real space flight conditions on the transport ship 'PROGRESS'. These measurements will allow scientists to determine the attainable current values for different combinations of collectors and emitters (passive metallic sphere, thermocathode, hollow cathodes and show up some prospects of active TSS. The report is concerned with the concept, purpose and tasks of the project, the planned set up of the measurement equipment on the 'PROGRESS' ship and in the container extended on the deployable 100 m long boom end.

Savich, N. A.

292

ORIGIN OF THE DIFFERENT ARCHITECTURES OF THE JOVIAN AND SATURNIAN SATELLITE SYSTEMS  

SciTech Connect

The Jovian regular satellite system mainly consists of four Galilean satellites that have similar masses and are trapped in mutual mean-motion resonances except for the outer satellite, Callisto. On the other hand, the Saturnian regular satellite system has only one big icy body, Titan, and a population of much smaller icy moons. We have investigated the origin of these major differences between the Jovian and Saturnian satellite systems by semi-analytically simulating the growth and orbital migration of proto-satellites in an accreting proto-satellite disk. We set up two different disk evolution/structure models that correspond to Jovian and Saturnian systems, by building upon previously developed models of an actively supplied proto-satellite disk, the formation of gas giants, and observations of young stars. Our simulations extend previous models by including the (1) different termination timescales of gas infall onto the proto-satellite disk and (2) different evolution of a cavity in the disk, between the Jovian and Saturnian systems. We have performed Monte Carlo simulations and have shown that in the case of the Jovian systems, four to five similar-mass satellites are likely to remain trapped in mean-motion resonances. This orbital configuration is formed by type I migration, temporal stopping of the migration near the disk inner edge, and quick truncation of gas infall caused by Jupiter opening a gap in the solar nebula. The Saturnian systems tend to end up with one dominant body in the outer regions caused by the slower decay of gas infall associated with global depletion of the solar nebula. The total mass and compositional zoning of the predicted Jovian and Saturnian satellite systems are consistent with the observed satellite systems.

Sasaki, T.; Ida, S. [Earth and Planetary Sciences, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551 (Japan); Stewart, G. R., E-mail: takanori@geo.titech.ac.j, E-mail: ida@geo.titech.ac.j, E-mail: gstewart@lasp.colorado.ed [Laboratory for Atmospheric and Space Physics, University of Colorado, Campus Box 392, Boulder, CO 80309-0392 (United States)

2010-05-10

293

Satellite graphics output station. [PAGES System  

SciTech Connect

The Los Alamos National Laboratory Computer Division has developed a satellite graphics output station. This station serves to directly accept user requests for output via a large computer network. The system orders these requests and schedules output on one of several devices consistently with the user's request and the overall job turnaround requirements of the Laboratory. The system translates a standard Metafile into a device-specific format and efficiently generates the requested output. At this same time, PAGES provides some graphics processing, previously provided by the large supercomputers. The system provides current information on queues, jobs being processed, and the devices. An effective quality control program is an integral part of the system design. This system will continue to reduce user interface changes, hold down operational cost, make effective use of supercomputer time, and produce quality output. The system was made possible by LANL standardization efforts including development of the Common Graphics System, the CGS Metafile, the standard file header and ICN standards.

Wolf, R.

1981-01-01

294

Design of the high resolution optical instrument for the PLEIADES HR Earth observation satellites  

NASA Astrophysics Data System (ADS)

As part of its contribution to Earth observation from space, ALCATEL SPACE designed, built and tested the High Resolution cameras for the European intelligence satellites HELIOS I and II. Coming after the SPOT program, it was decided to go ahead with the PLEIADES HR program. PLEIADES HR is the optical high resolution component of a larger optical and radar multi-sensors system : ORFEO. The first optical satellite of the PLEIADES HR constellation will be launched in mid-2008, the second will follow in 2009. To minimize the development costs, a mini satellite approach has been selected, leading to a compact concept for the camera design. The paper describes the design and performance budgets of this novel high resolution and large field of view optical instrument with emphasis on the technological features. This new generation of camera represents a breakthrough in comparison with the previous SPOT cameras owing to a significant step in on-ground resolution, which approaches the capabilities of aerial photography. Recent advances in detector technology, optical fabrication and electronics make it possible for the PLEIADES HR camera to achieve their image quality performance goals while staying within weight and size This camera design delivers superior performance using an innovative low power, low mass, scalable architecture, which provides a versatile approach for a variety of imaging requirements and allows for a wide number of possibilities of accommodation with a mini-satellite class platform.

Lamard, Jean-Luc; Gaudin-Delrieu, Catherine; Valentini, David; Renard, Christophe; Tournier, Thierry; Laherrere, Jean-Marc

2004-06-01

295

Observational Constraints on the ``Missing Satellite'' Problem from SDSS  

NASA Astrophysics Data System (ADS)

We quantify the algorithmic detectability of stellar Milky Way satellites in data release 5 (DR5) of the Sloan Digital Sky Survey (SDSS), and use this to estimate the luminosity function of faint satellite galaxies in our halo. We develop a satellite detection algorithm based on the convolution of the DR5 star catalog with a kernel of zero net flux that is the difference of a narrow positive Gaussian and a much wider negative Gaussian, which removes the background star-count level. This permits us to assess the significance of any (positive) detection in terms of deviations of this map. The efficiency of this algorithm is tested by computing the recovery rate of a large set of mock objects added to SDSS DR5 as a function of their luminosity, size and distance from the Sun. Most of the recent Milky Way satellite discoveries, made by SDSS, are shown to lie very close to the survey’s detection limits. Calculating the maximum accessible volume Vmax for all faint detected objects makes it possible for the first time to calculate the luminosity function for the Milky Way satellite galaxies, accounting consistently and algorithmically for their detection biases. The number density of satellite galaxies continues to rise towards low luminosities, but may flatten at MV ˜ -5. Within the uncertainties the luminosity function can be described by a simple power law dN/dMV= 10 × 100.1(MV+5), spanning luminosities from MV=-2.5 all the way to the bright end. Comparing these results to several galaxy formation models, we find the predicted properties differ from the data.

Koposov, Sergey; Belokurov, Vasily

296

The global Earth observation system of systems  

NASA Astrophysics Data System (ADS)

Recognizing the growing need for improved Earth observations, 140 governments and leading international organizations have established the Group on Earth Observations, or GEO, to collaborate and implement a Global Earth Observation System of Systems (GEOSS) by the year 2015. Countries and organizations are contributing their respective Earth monitoring systems, from satellites in space and in situ instruments on land, in the oceans and in the atmosphere. They are interlinking these systems so that, together, they provide a more complete picture of Earth's systems dynamics. GEO is developing common technical standards to pool observations and ensure their cross calibration and validation. It is building a web-based infrastructure to ensure easy access to the wealth of data and services contributed to, or generated by, GEOSS. GEO has been promoting the free and open sharing and dissemination of Earth observation data which has already driven significant changes in data distribution policies of several key Earth observing satellites: Landsat, Cbers and the future Sentinels of GMES. GEO is also reflecting on solutions to transition research systems into operational observing systems and ensure their long-term sustainability. First, the current status of GEOSS implementation and these core activities of GEO will be presented. Then, examples of global data sets and information systems or services developed through GEOSS will be presented: - a high-resolution global digital elevation model (DEM) based on Aster data was released by Japan and the USA. In situ measurements are now being used to improve the model as well as the stacking procedure used to develop it; - the Supersites initiative ensures coordinated access to data and information on natural hazards in geologically active regions. In light of the recent tragedy in Haiti, this project created a dedicated web site regularly updated with maps of seismicity, tectonics, Coulomb stress changes, topography, real and synthetic interferograms, as well as damage maps, data, and space images. See http://supersites.unavco.org/haiti.php; - the global carbon observation and analysis system combines observations, reanalysis and product development to provide regional information on emission variations. It addresses the three components of the carbon cycle (atmosphere, land, ocean). The project includes the improvement of global networks of atmospheric CO2 observations, air-surface exchange flux networks, surface ocean CO2 and related marine biochemistry observations, as well as space-based measurements combining Sciamachy , Airs and the newly launched Japanese Gosat; - the Forest Carbon Tracking (FCT) project coordinates the acquisition of observations from multi-spectral and radar (X, C and L-band) satellites, their processing through different models and methodologies and their validation by in situ measurements in 7 selected countries. The aim is to demonstrate the feasibility of a global monitoring and verification system for carbon storage and change in forests. Data and results can be viewed on-line at www.geo-fct.org. This portal allows users to visualize the FCT National Demonstrators, the relevant validation sites and the inventory of the coordinated acquisitions of satellite and in-situ data. Maps and information resulting from the processing of the data will also be posted here when available.

Achache, José

2010-05-01

297

LCROSS (Lunar Crater Observation and Sensing Satellite) Observation Campaign: Strategies, Implementation, and Lessons Learned  

NASA Astrophysics Data System (ADS)

NASA's LCROSS (Lunar Crater Observation and Sensing Satellite) mission was designed to explore the nature of previously detected enhanced levels of hydrogen near the lunar poles. The LCROSS mission impacted the spent upper stage of the launch vehicle into a permanently shadowed region of the lunar surface to create an ejecta plume. The resultant impact crater and plume were then observed by the LCROSS Shepherding Spacecraft as well as a cadre of telescopes on the Earth and in space to determine the nature of the materials contained within the permanently shadowed region. The Shepherding Spacecraft then became a second impactor which was also observed by multiple assets. The LCROSS Observation Campaign was a key component of the LCROSS mission. The goal of the Observation Campaign was to realize the scientific benefits of extending the LCROSS observations to multiple ground and space-based assets. This paper describes the LCROSS Observation Campaign and provides an overview of the Campaign coordination and logistics as well as a summary of the observation techniques utilized at a multitude of observatories. Lessons learned from the LCROSS Observation Campaign are also discussed to assist with the planning of future unique observing events.

Heldmann, Jennifer L.; Colaprete, Anthony; Wooden, Diane H.; Ackermann, Robert F.; Acton, David D.; Backus, Peter R.; Bailey, Vanessa; Ball, Jesse G.; Barott, William C.; Blair, Samantha K.; Buie, Marc W.; Callahan, Shawn; Chanover, Nancy J.; Choi, Young-Jun; Conrad, Al; Coulson, Dolores M.; Crawford, Kirk B.; DeHart, Russell; de Pater, Imke; Disanti, Michael; Forster, James R.; Furusho, Reiko; Fuse, Tetsuharu; Geballe, Tom; Gibson, J. Duane; Goldstein, David; Gregory, Stephen A.; Gutierrez, David J.; Hamilton, Ryan T.; Hamura, Taiga; Harker, David E.; Harp, Gerry R.; Haruyama, Junichi; Hastie, Morag; Hayano, Yutaka; Hinz, Phillip; Hong, Peng K.; James, Steven P.; Kadono, Toshihiko; Kawakita, Hideyo; Kelley, Michael S.; Kim, Daryl L.; Kurosawa, Kosuke; Lee, Duk-Hang; Long, Michael; Lucey, Paul G.; Marach, Keith; Matulonis, Anthony C.; McDermid, Richard M.; McMillan, Russet; Miller, Charles; Moon, Hong-Kyu; Nakamura, Ryosuke; Noda, Hirotomo; Okamura, Natsuko; Ong, Lawrence; Porter, Dallan; Puschell, Jeffery J.; Rayner, John T.; Rembold, J. Jedadiah; Roth, Katherine C.; Rudy, Richard J.; Russell, Ray W.; Ryan, Eileen V.; Ryan, William H.; Sekiguchi, Tomohiko; Sekine, Yasuhito; Skinner, Mark A.; Sōma, Mitsuru; Stephens, Andrew W.; Storrs, Alex; Suggs, Robert M.; Sugita, Seiji; Sung, Eon-Chang; Takatoh, Naruhisa; Tarter, Jill C.; Taylor, Scott M.; Terada, Hiroshi; Trujillo, Chadwick J.; Vaitheeswaran, Vidhya; Vilas, Faith; Walls, Brian D.; Watanabe, Jun-ihi; Welch, William J.; Woodward, Charles E.; Yim, Hong-Suh; Young, Eliot F.

2012-05-01

298

A satellite terminal system for the Arctic  

SciTech Connect

Experience has shown that ice rubble fields form around artificial islands in the Beaufort Sea, the extent depending upon water depth, island slopes, and overall island configuration. If sand islands or retained islands are used for production and product storage, there is a possibility that access by export tankers to docking facilities adjacent to the island would be impeded by the rubble formations. It is for this reason that the feasibility of installing a terminal remote from the production facility was examined. This paper covers the basic philosophies used in the layout of the satellite terminal system; the choice of structural shape; the ice loading return periods; the action of ice around the structure; and the proposed methods for mooring and loading.

Bruce, J.C.; Charpentier, K.J.

1983-05-01

299

Optical Observations of the Artificial Earth-Satellites.  

National Technical Information Service (NTIS)

A camera equipped with a Boyer 'Saphir' objective (F=450 mm, D/F = 1:4.5), and with a chopper occulting the object, is being used to obtain a satellite trace exhibiting a number of interruptions which are recorded by means of an oscillograph. With a good ...

E. Z. Gindin G. A. Leikin A. M. Lozinskii A. G. Masevich

1965-01-01

300

Satellite Observations of Smoke from Oil Fires in Kuwait  

Microsoft Academic Search

Extensive dark smoke clouds associated with burning oil wells in Kuwait have been seen in data from weather satellites since early February 1991. The smoke is dispersed over a wide area. Variable and strong low level winds have held most of the smoke plume below 3 to 5 kilometers within a few hundred kilometers of the source. Thin veils of

S. S. Limaye; V. E. Suomi; C. Velden; G. Tripoli

1991-01-01

301

Dynamic deformation of Etna volcano observed by satellite radar interferometry  

Microsoft Academic Search

Satellite radar interferometry of Mt. Etna volcano, Sicily, Italy, reveals a sequence of deformation characterized by deflation during the end of the 1993 eruption, inflation from 1993-1995 with an increase in the inflation rate immediately before its resumed eruptive activity in late 1995. This was followed by very low deformation levels during the following year. The source of the deformation

Riccardo Lanari; Paul Lundgren; Eugenio Sansosti

1998-01-01

302

Satellite Observation of Great Lakes Ice - Winter 1978-79.  

National Technical Information Service (NTIS)

Ice conditions on the five Great Lakes and Lake St. Clair were monitored from satellite imagery. The formation, movement, and dissipation of lake ice were traced from December 1978 through May 1979. Wind speeds and directions were correlated with ice move...

J. Wartha-Clark

1980-01-01

303

Dwindling groundwater resources in northern India, from satellite gravity observations  

Microsoft Academic Search

Northern India and its surroundings, home to roughly 600 million people, is probably the most heavily irrigated region in the world. Temporal changes in Earth's gravity field in this region as recorded by the GRACE satellite mission, reveal a steady, large-scale mass loss that we attribute to excessive extraction of groundwater. Combining the GRACE data with hydrological models to remove

V. M. Tiwari; J. Wahr; S. Swenson

2009-01-01

304

Satellite Observations of the Mt. Pinatubo Stratospheric Cloud  

Microsoft Academic Search

The Mt. Pinatubo eruption of 1991 was one of the largest climatically significant volcanic eruptions of the 20th century. The resulting stratospheric cloud of sulfuric acid aerosol was almost entirely undisturbed by other eruptions over a ten-year period. During this time, the cloud was constantly monitored by a number of satellite missions. It thus presents an excellent case study to

P. Hamill; H. Houben; R. W. Bergstrom

2001-01-01

305

Mobile satellite communications systems - Toward global personal communications  

NASA Astrophysics Data System (ADS)

The constraints imposed by the RF environment are reviewed. An overview of present and planned mobile satellite systems is given. Present systems refer to those already in operation, while planned systems refer to those that have authority to offer the services and have either a satellite in orbit or one being built to support the systems. Future directions for mobile satellite communications systems are discussed. One approach emerging is the use of large satellites, with large antennas, operating at much higher carrier frequencies. A second approach is to use low-earth orbiting (LEO) satellites, in order to reduce the path loss. The LEO approach also results in much smaller propagation delays than those experienced with geostationary satellites.

Lodge, John H.

1991-11-01

306

Observers for multivariable systems  

Microsoft Academic Search

Often in control design it is necessary to construct estimates of state variables which are not available by direct measurement. If a system is linear, its state vector can be approximately reconstructed by building an observer which is itself a linear system driven by the available outputs and inputs of the original system. The state vector of annth order system

D. Luenberger

1966-01-01

307

Regional tropical temperature trends from radiosondes, reanalyses, and satellite observations  

NASA Astrophysics Data System (ADS)

We compare seasonal 20th century atmospheric temperature trends in the Tropics (30°S-30°N) from radiosonde observations (CHUAN, HadAT, IUK, RAOBCORE/RICH, RATPAC) and reanalyses (ERA-40, NCEP/NCAR (NNR), Twentieth Century reanalysis (20CR), CFSR, ERA-Interim, MERRA). Large differences are found between the magnitudes, vertical profiles of the temperature trends (even for time periods > 3 decades), and chronological sequences of bidecadal, regional warming and cooling periods in the reanalyses. Long term zonal mean vertical trend profiles from CHUAN and from the reanalyses reaching back to the time before the satellite era reveal an amplified upper tropospheric warming for all longest periods of dataset overlap (1901-99, 1901-57, 1948-99, 1957-99). ERA-40 and NNR show a second warming maximum in the lower troposphere which is missing in 20CR. The agreement of the vertical structure and temporal behaviour of regional, bidecadal trends in the long reanalyses for 4 regions in the Tropics with CHUAN is generally best for ERA-40, followed by a less good agreement with trends from NNR and 20CR. The performance of ERA-40 is best in the Americas sector, and less so in the Asian and Pacific sectors. The agreement of NNR with CHUAN is significantly worse than that of ERA-40 for all tropical regions, especially with respect to the vertical structure of the trends. The 20CR temporal behaviour and vertical structure of the tropical trends is often different from CHUAN, ERA-40 and NNR, especially around the tropopause, and in all sectors. For the more recent but shorter reanalyses, ERA-Interim is generally closer to ERA-40 than CFSR and MERRA. For the period of overlap (1951-99) CHUAN itself agrees reasonably well with HadAT, IUK, RAOBCORE/RICH and RATPAC on the general picture. However, some disagreement on the trend sign can be seen a) for the American sector during 1961-80 with RAOBCORE/RICH and RATPAC and during 1971-90 with RAOBCORE/RICH, b) for the Asian sector during 1961-80 with RAOBCORE/RICH.

Stickler, Alexander; Brönnimann, Stefan

2013-04-01

308

Communication satellite system beyond the year 2000  

NASA Astrophysics Data System (ADS)

The primary evolutionary factors of satellite communications technologies are reviewed based on the results of a study of novel satellite developments. A critical evaluation of the viability and availability of the technologies is utilized in conjunction with market forecasts to determine promising commercial strategies. Modern technologies are almost prepared for the development of a class of communications satellites and include bandwidth utilization, spacecraft bus modularity, and functional integration.

Robertson, G. J.; Fourquet, J. M.

1991-10-01

309

Measurement requirements for constraining the origin of the Galilean satellite system  

NASA Astrophysics Data System (ADS)

One of the primary science objectives of the JUpiter ICy moon Explorer (JUICE) mission is to characterize the origin and evolution of the Galilean satellites. Here we discuss the observational tests that could be performed via a Ion and Neutral Mass Spectrometer (INMS) aboard the JUICE mission and that would shed light on the formation circumstances of the Galilean satellite system.

Mousis, O.; Waite, J. H.; Lunine, J. I.

2012-09-01

310

Quantifying the measurement requirements needed to understand the origin of the Galilean satellite system  

NASA Astrophysics Data System (ADS)

One of the primary science objectives of the JUpiter ICy moon Explorer (JUICE) mission is to characterize the origin and evolution of the Galilean satellites. Here we discuss the observational tests that could be performed via a Ion and Neutral Mass Spectrometer (INMS) aboard the JUICE mission and that would shed light on the formation circumstances of the Galilean satellite system.

Mousis, O.; Waite, J. H.; Lunine, J. I.

2011-12-01

311

Small satellite plan for imaging observation of the ionosphere, mesosphere, thermosphere and plasmasphere  

Microsoft Academic Search

A small satellite project is planned for the global imaging observation of the ionosphere mesosphere thermosphere and plasmasphere by a Japanese scientist group The satellite is designed in aiming to be launched to the geo-transfer orbit in the next solar maximum between 2011 and 2013 The observation is focused on the Earth s upper atmospheres in the mid- and low-latitude

A. Saito

2006-01-01

312

The first observations of laser satellites from plasma created by high intense laser pulses  

Microsoft Academic Search

Laser satellites, i.e. spectral lines caused by non-linear interaction of strong laser radiation with multicharged ions, are observed for the first time. Their identification are carried out by comparison of both experimental wavelengths and intensities with theoretical ones. It is shown that observation of laser satellites allows to measure directly the energies of ionic metastable states.

I. Yu Skobelev; A. Ya Faenov; A. I. Magunov; A. Osterheld; B. Young; J. Dunn; R. E. Stewart

1997-01-01

313

SCIENTIFIC OBJECTIVES AND OBSERVING METHODS FOR A MINIMUM ARTIFICIAL EARTH SATELLITE  

Microsoft Academic Search

The problems of systematic and accurate observations of a proposed ; minlmum earth satellite were studied. Limitations imposed by scientific ; objectives of a satellite vehicle, size of the vehicle, kinds of orbits possible, ; existing instrumentation technology and the suitability of instrumentation sites ; were considered. lt is concluded that a combination of optical and electronic ; observing methods

L. G. deBey; W. W. Berning; D. Reuyl; H. M. Cobb

1955-01-01

314

Evaluation of sulfate aerosol optical depths over the North Atlantic and comparison with satellite observations  

SciTech Connect

It has been postulated that scattering of sunlight by aerosols can significantly reduce the amount of solar energy absorbed by the climate system. Aerosol measurement programs alone cannot provide all the information needed to evaluate the radiative forcing due to anthropogenic aerosols. Thus, comprehensive global-scale aerosol models, properly validated against surface-based and satellite measurements, are a fundamental tool for evaluating the impacts of aerosols on the planetary radiation balance. Analyzed meteorological fields from the European Centre for Medium-Range Weather Forecasts are used to drive a modified version of the PNL Global Chemistry Model, applied to the atmospheric sulfur cycle. The resulting sulfate fields are used to calculate aerosol optical depths, which in turn are compared to estimates of aerosol optical depth based on satellite observations.

Berkowitz, C.M.; Ghan, S.J. [Pacific Northwest Lab., Richland, WA (United States); Benkovitz, C.M.; Wagener, R.; Nemesure, S.; Schwartz, S.E. [Brookhaven National Lab., Upton, NY (United States)

1993-11-01

315

The gap filler technology for mobile satellite system  

Microsoft Academic Search

Satellite mobile communication systems have rapidly come into widespread use and user have begun to require high speed multimedia services in mobile environments in any place; even if high speed train. In response to these demands, mobile satellite communication system is the key solution to provide high speed multimedia services in high speed train. Nowadays the high speed portable system

Joon Gyu Ryu; Min-Su Shin; S. M. Han; D. I. Jang; Ho-Jin Lee

2007-01-01

316

The Operation of the NOAA Polar Satellite System.  

National Technical Information Service (NTIS)

The report is to summarize the NOAA Polar Satellite System and to provide interested people with a perspective of the operational NOAA polar orbiting satellite system. The NOAA polar system description serves as a reference for developers of short-range m...

J. J. Fortuna L. N. Hambrick

1974-01-01

317

Diode laser satellite systems for beamed power transmission  

Microsoft Academic Search

A power system composed of an orbiting laser satellite and a surface-based receiver\\/converter is described. Power is transmitted from the satellite to the receiver\\/converter by laser beam. The satellite components are: (1) solar collector; (2) blackbody; (3) photovoltaic cells; (4) heat radiators; (5) laser system; and (6) transmission optics. The receiver\\/converter components are: receiver dish; lenticular lens; photocells; and heat

M. D. Williams; J. H. Kwon; G. H. Walker; D. H. Humes

1990-01-01

318

Climatology of upper thermospheric daytime neutral winds from satellite observations  

Microsoft Academic Search

We studied the global climatology of mid- and low- latitude F region daytime neutral winds using extensive measurements by the Wind Imaging Interferometer (WINDII) instrument on board the Upper Atmosphere Research Satellite (UARS). Quiet-time winds are mostly poleward and westward during the day, and are generally 5-20 m\\/s smaller in the longitudinal sector closest to the magnetic pole, compared to

John T. Emmert

2001-01-01

319

Precipitation measurements using 183GHz AMSU satellite observations  

Microsoft Academic Search

The 183-GHz humidity channels of the Advanced Microwave Sounding Unit (AMSU) on the NOAA-15 operational weather satellite respond in part to precipitation. The 15-km resolution data at 183.31±7 and 183.31±1 GHz were combined to yield point precipitation estimates from a simple neural network trained using NEXRAD radar precipitation data. A computer used these estimates to locate all significant precipitation cells

D. H. Staelin; F. W. Chen; A. Fuentes

1999-01-01

320

DEMETER satellite observations of lightning-induced electron precipitation  

Microsoft Academic Search

DEMETER spacecraft detects short bursts of lightning-induced electron precipitation (LEP) simultaneously with newly-injected upgoing whistlers, and sometimes also with once-reflected (from conjugate hemisphere) whistlers. For the first time causative lightning discharges are definitively geo-located for some LEP bursts aboard a satellite. The LEP bursts occur within <1 s of the causative lightning and consist of 100-300 keV electrons. First in-situ

D. Piddyachiy; W. B. Peter; J. A. Sauvaud; M. Parrot

2007-01-01

321

Satellite Clouds and Precipitation Observations for Meteorology and Climate  

Microsoft Academic Search

Measuring precipitation from space is a long standing issue of meteorology and climatology. Since the launch of the first\\u000a meteorological satellites in the 60s several visible\\/infrared\\/microwave techniques for “inferring”, rather than “measuring”\\u000a rainfall intensity from space were conceived, but seldom reached operational application. Algorithms have greatly evolved\\u000a and now offer an acceptable quality level when products are averaged over suitable

Vincenzo Levizzani

322

Results from comparing THEMIS satellite and ground based observations.  

NASA Astrophysics Data System (ADS)

The NASA Time History of Events and Macroscale Interactions during Substorms (THEMIS) project is intended to investigate the major controversy in substorm science, the uncertainty whether the instability leading to the substorm is initiated near the Earth or in the more distant >20 Re magnetic tail. THEMIS will use the timing of the occurrence of substorm signatures at five satellites and at ground based all-sky imagers and magnetometers to infer the propagation direction. The array of stations consists of 20 all-sky imagers and 30 plus magnetometers deployed in the North American continent from Alaska to Labrador. Each ground based observatory contains a white light imager taking auroral images at a 3 second repetition rate and a magnetometer that records the 3 axis variation of the magnetic field at 2 Hz frequency. During the winter of 2007-08 the THEMIS satellites achieved their intended strategic locations to monitor substorms. For example in the time period between 06 and 09 UT on the 2nd of February 2008 several substorms occurred while the THEMIS satellites P1, P2, P3, P4, and P5 were located in the tail of the magnetosphere at approximately 29.6, 18.5, 11, 11 and 8Re downtail distance (GSM) respectively. The weather was relatively clear permitting the recording of the auroral features while the particle and field measurements were taken. In this paper we will discuss the preliminary results drawn from the data taken during substorms that occur during THEMIS conjunctions.

Mende, Stephen; Frey, Harald; Donovan, Eric; Jackel, Brian; Angelopoulos, V.

323

2.5aA laser satellite ranging system--Part I: Equipment description  

Microsoft Academic Search

A laser tracking system has been used to track three satellites equipped with retroreflectors. An rms scatter of one to two meters derived from 200-200 observations per pass agrees with the expected instrumental precision.

T. S. JOHNSON; H. H. PLOTKIN; P. L. SPADIN

1967-01-01

324

Deburi Kansoku/Hokaku Jikken Eisei (Debris Observation and Arresting Experiment Satellite).  

National Technical Information Service (NTIS)

An overview of the present status and condition of, and future of the observation of debris in space is presented. The results of a survey on documents concerning debris disposal methods are outlined. Missions of debris observation and arresting satellite...

T. Yukawa

1992-01-01

325

Global distribution of cirrus clouds from CloudSat\\/Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) measurements  

Microsoft Academic Search

The cirrus clouds of the upper troposphere are globally widespread and are important regulators of the radiative balance, and hence climate, of the Earth-atmosphere system. Despite their wide distribution, however, cirrus are difficult to study from satellite radiance measurements or from scattered ground observing sites because they can occur as part of multilayered cloud systems and are characteristically optically thin.

Kenneth Sassen; Zhien Wang; Dong Liu

2008-01-01

326

SatCam: A mobile application for coordinated ground/satellite observation of clouds and validation of satellite-derived cloud mask products.  

NASA Astrophysics Data System (ADS)

SatCam is an application for iOS devices that allows users to collect observations of local cloud and surface conditions in coordination with an overpass of the Terra, Aqua, or NPP satellites. SatCam allows users to acquire images of sky conditions and ground conditions at their location anywhere in the world using the built-in iPhone or iPod Touch camera at the same time that the satellite is passing overhead and viewing their location. Immediately after the sky and ground observations are acquired, the application asks the user to rate the level of cloudiness in the sky (Completely Clear, Mostly Clear, Partly Cloudy, Overcast). For the ground observation, the user selects their assessment of the surface conditions (Urban, Green Vegetation, Brown Vegetation, Desert, Snow, Water). The sky condition and surface condition selections are stored along with the date, time, and geographic location for the images, and the images are uploaded to a central server. When the MODIS (Terra and Aqua) or VIIRS (NPP) imagery acquired over the user location becomes available, a MODIS or VIIRS true color image centered at the user's location is delivered back to the SatCam application on the user's iOS device. SSEC also proposes to develop a community driven SatCam website where users can share their observations and assessments of satellite cloud products in a collaborative environment. SSEC is developing a server side data analysis system to ingest the SatCam user observations, apply quality control, analyze the sky images for cloud cover, and collocate the observations with MODIS and VIIRS satellite products (e.g., cloud mask). For each observation that is collocated with a satellite observation, the server will determine whether the user scored a "hit", meaning their sky observation and sky assessment matched the automated cloud mask obtained from the satellite observation. The hit rate will be an objective assessment of the accuracy of the user's sky observations. Users with high hit rates will be identified automatically and their observations will be used globally to evaluate the performance of the MODIS cloud mask algorithm for Terra and Aqua and the VIIRS cloud mask algorithm for NPP. The user's assessment of the ground conditions will also be used to evaluate the cloud mask accuracy in selecting the correct surface type at the user's location, which is an important element in the decision path used internally by the cloud mask algorithm. This presentation will describe the SatCam application, how it is used, and show examples of SatCam observations.

Gumley, L.; Parker, D.; Flynn, B.; Holz, R.; Marais, W.

2011-12-01

327

Determination of source thunderstorms for VHF emissions observed by the FORTE satellite  

Microsoft Academic Search

This paper explains a method of locating groups of satellite-observed VHF signals from lightning that emanate from isolated storm regions. LF\\/VLF signals recorded and located by the National Lightning Detection Network (NLDN) are often accompanied by broadband VHF emissions of sufficient intensity to trigger satellite-based RF receivers. It has previously been shown that events recorded by the FORTE satellite and

Heidi E. Tierney; Abram R. Jacobson; William H. Beasley; Paul E. Argo

2001-01-01

328

Observability of complex systems.  

PubMed

A quantitative description of a complex system is inherently limited by our ability to estimate the system's internal state from experimentally accessible outputs. Although the simultaneous measurement of all internal variables, like all metabolite concentrations in a cell, offers a complete description of a system's state, in practice experimental access is limited to only a subset of variables, or sensors. A system is called observable if we can reconstruct the system's complete internal state from its outputs. Here, we adopt a graphical approach derived from the dynamical laws that govern a system to determine the sensors that are necessary to reconstruct the full internal state of a complex system. We apply this approach to biochemical reaction systems, finding that the identified sensors are not only necessary but also sufficient for observability. The developed approach can also identify the optimal sensors for target or partial observability, helping us reconstruct selected state variables from appropriately chosen outputs, a prerequisite for optimal biomarker design. Given the fundamental role observability plays in complex systems, these results offer avenues to systematically explore the dynamics of a wide range of natural, technological and socioeconomic systems. PMID:23359701

Liu, Yang-Yu; Slotine, Jean-Jacques; Barabįsi, Albert-Lįszló

2013-01-28

329

C-Band Satellite TV Broadcast Reception System.  

National Technical Information Service (NTIS)

A home reception system for satellite TV broadcasts has been developed and commercialized to receive the US TV broadcasts of cable TV operators in the C band (3.7 to 4.2 GHz), which utilizes a geostationary satellite. The reception system consists of a lo...

Y. Shiomi O. Shizuya N. Omoto H. Fujisaki Y. Yoshimura

1986-01-01

330

Study of sub-auroral radio emissions observed by ICE experiment onboard DEMETER satellite  

NASA Astrophysics Data System (ADS)

We report on the terrestrial kilometric and hectometric radio emissions recorded by the DEMETER/ICE (Instrument Champ Electrique) experiment. This instrument measures the electric field components of electromagnetic and electrostatic waves in the frequency range from DC to 3.25 MHz. Despite the limited satellite invariant latitude (data acquisition below about 65°), specific events have been observed, close to the sub-auroral region, in the frequency range from 100 kHz to about 1 MHz. This range covers the well-known auroral kilometric radiation (AKR), the terrestrial kilometric continuum, and the sub-auroral terrestrial emission at higher frequency up to 3 MHz. The high spectral capability of the experiment leads us to distinguish between the bursty and the continuum emissions. Selected events have been found to principally occur in the late evening and early morning sectors of the magnetosphere (22 MLT - 02 MLT) but others have been observed on the dayside. Our first results are compared to previous radio observations performed on board INTERBALL-1 (Kuril'chik et al, Cosmic Research, 43, 2005) and GEOTAIL (Hashimoto et al., JGR, 104, 1999) satellites. We also discuss the common and different features of the Earth and Jovian radio emissions. We emphasis on the observational parameters: the occurrence probability, the emission beam and the spectral emission types. We show that the physical interpretation of the auroral phenomena needs a good knowledge of the geometric configuration of the source and observer and the reception system (antenna beam and receivers).

Boudjada, M. Y.; Galopeau, P. H. M.; Mogilevski, M. M.; Sawas, S.; Blecki, J.; Berthelier, J. J.; Voller, W.

2012-04-01

331

Feasibility of microminiature satellites  

NASA Astrophysics Data System (ADS)

A conceptual study is conducted on technical problems and system design techniques to accomplish higher performance microminiature satellites by smaller systems. Applications of microminiature satellite technology to practical satellite mission are mentioned. Concepts of microminiature satellites, measures to miniaturize satellites, and micro-miniaturization technologies for communication and data processing, electric solar power paddle, attitude and orbit control, structure, thermal control, propulsion, and instrumentation systems are outlined. Examples of miniaturizing satellite missions such as planet exploration, low-altitude communication networks, space positioning system, low-altitude earth observation mission, clustered satellites, tethered satellites, and timely observation are described. Satellite miniaturizing technology can also be used to launch systems by lasers, and superconductive linear catapults (space escalator). It is pointed out that keys to promote satellite miniaturization are electronics, precision machining, raw material, electric power source technologies, and system design technology to integrate those technologies.

Imai, Ryouichi

1991-07-01

332

Tracking Cholera in Coastal Regions using Satellite Observations.  

PubMed

Cholera remains a significant health threat across the globe. The pattern and magnitude of the seven global pandemics suggest that cholera outbreaks primarily originate in coastal regions and then spread inland through secondary means. Cholera bacteria show strong association with plankton abundance in coastal ecosystems. This review study investigates relationship(s) between cholera incidence and coastal processes and explores utility of using remote sensing data to track coastal plankton blooms, using chlorophyll as a surrogate variable for plankton abundance, and subsequent cholera outbreaks. Most studies over the last several decades have primarily focused on the microbiological and epidemiological understanding of cholera outbreaks. Accurate identification and mechanistic understanding of large scale climatic, geophysical and oceanic processes governing cholera-chlorophyll relationship is important for developing cholera prediction models. Development of a holistic understanding of these processes requires long and reliable chlorophyll dataset(s), which are beginning to be available through satellites. We have presented a schematic pathway and a modeling framework that relate cholera with various hydroclimatic and oceanic variables for understanding disease dynamics using latest advances in remote sensing. Satellite data, with its unprecedented spatial and temporal coverage, have potentials to monitor coastal processes and track cholera outbreaks in endemic regions. PMID:21072249

Jutla, Antarpreet S; Akanda, Ali S; Islam, Shafiqul

2010-08-01

333

Satellite Power System (SPS) International Agreements.  

National Technical Information Service (NTIS)

This study identifies the problems in obtaining international agreements on geostationary orbit availability, microwave frequency allocations and microwave frequency standards for satellites transmitting solar power. Its findings and recommendations are b...

S. Grove

1978-01-01

334

LOCSTAR: A Satellite Radiodetermination System for Europe.  

National Technical Information Service (NTIS)

The LOCSTAR radiodetermination satellite service is described. It is designed to provide accurate location information to mobile users and their home bases, and a two-way exchange of short messages between these segments. The results of market surveys in ...

R. Rosso

1989-01-01

335

Observing the Solar System  

NASA Astrophysics Data System (ADS)

1. Earth and sky; 2. Moon and planet observer's hardware; 3. The Solar System framed; 4. Stacking up the Solar System; 5. Our Moon; 6. Mercury and Venus; 7. Mars; 8. Jupiter; 9. Saturn, Uranus and Neptune; 10. Small worlds; 11. Comets; 12. Our daytime star; Appendices; Index.

North, Gerald

2012-10-01

336

A study of a Hurricane Katrina–induced phytoplankton bloom using satellite observations and model simulations  

Microsoft Academic Search

Satellite observations of sea surface temperature (SST) and chlorophyll-a concentration from the Moderate Resolution Imaging Spectroradiometer (MODIS) on Aqua revealed a phytoplankton bloom event in the vicinity of the Loop Current (LC) in the Gulf of Mexico after Hurricane Katrina's passage in August 2005. The sea surface height (SSH) anomaly data derived from satellite altimetry measurements indicated that the phytoplankton

Xiaoming Liu; Menghua Wang; Wei Shi

2009-01-01

337

SATELLITE OBSERVATIONS OF THERMAL EMISSION BEFORE, DURING, AND AFTER, THE JANUARY 2002 ERUPTION OF NYIRAGONGO  

Microsoft Academic Search

This paper presents a two-year archive of thermal observations made before, during, and after the January 2002 eruption of Nyiragongo volcano, Democratic Republic of Congo. Infrared satellite data acquired by the Moderate Resolution Imaging Spectro- radiometer (modis), a multi-spectral scanner carried onboard the National Aeronautical and Space Administration's (nasa) Terra and Aqua satellites, indicate an absence of significant thermal activity

Robert Wright; Luke P. Flynn

338

A Comparison of Heuristic Methods for Scheduling Earth Observing Satellites Fleet  

Microsoft Academic Search

This paper addressed the planning and scheduling problem for earth observing satellites fleet of China. The author first described the problem scope naturally, then proposed a mixed-integer programming model for a simplified version of the problem, which only considered the data-take activities of the satellites. Then the author gave two heuristic methods for it and made experimental comparisons based on

Pei Wang; Yuejin Tan; Gerhard Reinelt

2009-01-01

339

Quasistationary areas of chlorophyll concentration in the world ocean as observed satellite data  

Microsoft Academic Search

To estimate the seasonal progress of the production process over the planet and its long-standing trend it is important to measure not only the spatial distributions of pigment that represent the rates of photosynthesis but also their time variability. Anthropogenic impact on natural complexes can be efficiently estimated by satellite observations of phytopigment dynamics. This study presents CZCS satellite data

A. P. Shevyrnogov; G. S. Vysotskaya; J. I. Gitelson

1996-01-01

340

Significant results from using earth observation satellites for mineral and energy resource exploration  

Microsoft Academic Search

A large number of Earth-observation satellites orbit our world several times each day, providing new information about the land and sea surfaces and the overlying thin layer of atmosphere that makes our planet unique. Meteorological satellites have had the longest history of experimental use and most are now considered operational. The geologic information collected by the Landsat, Polar Orbiting Geophysical

W. D. Carter

1981-01-01

341

Launch and Observation Program of the Experimental Geodetic Satellite of Japan  

Microsoft Academic Search

The Experimental Geodetic Satellite (EGS) of Japan has been developed by the National Space Development Agency of Japan and was completed in mid-1985. The functions of the EGS are 1) to reflect input laser light back toward the ground for precise ranging and 2) to reflect solar light to determine the direction to the satellite from an observation site. The

MINORU SASAKIAND; Hidekazu Hashimoto

1987-01-01

342

Collisional Evolution of Irregular Satellite Swarms: Detectable Dust around Solar System and Extrasolar Planets  

Microsoft Academic Search

Since the 1980's it has been becoming increasingly clear that the Solar\\u000aSystem's irregular satellites are collisionally evolved. We derive a general\\u000amodel for the collisional evolution of an irregular satellite swarm and apply\\u000ait to the Solar System and extrasolar planets. Our model reproduces the Solar\\u000aSystem's complement of observed irregulars well, and suggests that the\\u000acompetition between grain-grain

Grant M. Kennedy; Mark C. Wyatt

2010-01-01

343

The ESA technological development activity for domestic communications satellite systems  

NASA Astrophysics Data System (ADS)

Domestic and rural satellite communications, when compared to more traditional satellite systems such as Intelsat and Eutelsat, present different system requirements which result in different technological solutions both for the space segment and the ground segment. In view of preparing European industry to be competitive in an international 'Call for Tenders' expected for such systems, especially from less developed countries, the European Space Agency started in 1982 a program of technological development of specific components, subsystems, and systems described in this communication. After introducing background concepts of Domestic Communication Satellite Systems, the article reviews the technological developments in both the space segment and the earth segment.

Bichi, A. F.

1986-10-01

344

Satellite-Observed Algae Blooms in China's Lake Taihu  

NASA Astrophysics Data System (ADS)

During the spring of 2007, a massive blue-green algae (Microcystis) bloom broke out in Lake Taihu, one of the largest inland lakes in China. This freshwater lake is located in the Yangtze River delta (Figure 1), one of the world's most urbanized and heavily populated areas. The massive bloom event became an environmental crisis that prompted officials to cut tap water supply to several million residents in nearby Wuxi city in China's Jiangsu province. The outbreak, which the Chinese government identified as a major natural disaster, forced unprepared residents to rush to buy bottled water for their normal usage. This article presents results from an analysis of that event that demonstrate an application of satellite-derived imagery for inland lake water quality monitoring, assessment, and management.

Wang, Menghua; Shi, Wei

2008-05-01

345

Dwindling groundwater resources in northern India, from satellite gravity observations  

NASA Astrophysics Data System (ADS)

Northern India and its surroundings, home to roughly 600 million people, is probably the most heavily irrigated region in the world. Temporal changes in Earth's gravity field in this region as recorded by the GRACE satellite mission, reveal a steady, large-scale mass loss that we attribute to excessive extraction of groundwater. Combining the GRACE data with hydrological models to remove natural variability, we conclude the region lost groundwater at a rate of 54 ± 9 km3/yr between April, 2002 (the start of the GRACE mission) and June, 2008. This is probably the largest rate of groundwater loss in any comparable-sized region on Earth. Its likely contribution to sea level rise is roughly equivalent to that from melting Alaskan glaciers. This trend, if sustained, will lead to a major water crisis in this region when this non-renewable resource is exhausted.

Tiwari, V. M.; Wahr, J.; Swenson, S.

2009-09-01

346

Genesis of tropical cyclone Nargis revealed by multiple satellite observations  

NASA Astrophysics Data System (ADS)

Tropical cyclone (TC) Nargis recently battered Myanmar on May 2 2008 is one of the most deadly tropical storms in history. Nargis was initiated by an abnormally strong intraseasonal westerly event associated with Madden-Julian oscillation (MJO) in the eastern Indian Ocean. An incipient cyclonic disturbance emerged as an emanation of Rossby wave-induced vortex when the intraseasonal convective anomaly reached the Maritime Continent. The northeastward movement of MJO convection facilitated further development of the disturbance. The incipient disturbance became a tropical disturbance (TD) with a central warm-core structure on April 26. The further development from the TD to TC formation on April 28 is characterized by two distinctive stages: a radial contraction followed by a rapid intensification. The processes responsible for contraction and rapid intensification are discussed by diagnosis of multiple satellite data. This proposed new scenario is instrumental for understanding how a major TC develops in the northern Indian Ocean.

Kikuchi, Kazuyoshi; Wang, Bin; Fudeyasu, Hironori

2009-03-01

347

Application of high resolution satellite observations to monitor urban ecosystems  

NASA Astrophysics Data System (ADS)

Topographic identification and mapping were carried out for different key plots in Moscow according to satellite images using geoinformation technologies; a complex ecological map was constructed for the key plots. The main advantage of this project is using the remote information for obtaining quick-look data on the ecosystem's state. The following ecological parameters were determined during the mapping: the percentage of forest area, the canopy's density, and the sites of forest uprooting in forests-parks; the recreational load on the soil cover in the forests, valleys of small rivers, and public gardens; the areas of disturbances of the herbaceous cover and soil overcompaction in lawns; the vertical and lateral structure of line plantings in community landscapes; and the disturbances in the land use in the territory of water-control areas of small rivers.

Gorokhova, I. N.

2011-02-01

348

Satellite augmentation of cellular type mobile radio telephone systems  

NASA Astrophysics Data System (ADS)

An experiment in which the ATS-6 satellite relayed voice bandwidth communications between five trucks and the trucking company dispatchers as the trucks traveled about the northeastern part of the U.S. is described. The experiment demonstrated that propagation characteristics are much different for the satellite-mobile links than for terrestrial-mobile links. It is found that a properly designed satellite system can provide high quality, reliable voice and data communications except where the vehicle-satellite path is shadowed by a structure or terrain feature.

Anderson, R. E.

1981-09-01

349

Analysis of Meteorological Satellite Location and Data Collection System Concepts.  

National Technical Information Service (NTIS)

A satellite system that employs a spaceborne RF interferometer to determine the location and velocity of data collection platforms attached to meteorological balloons is proposed. This meteorological advanced location and data collection system (MALDCS) i...

R. G. Wallace D. L. Reed

1981-01-01

350

Dynamic Simulation Facility for Satellite Attitude Control Systems.  

National Technical Information Service (NTIS)

A dynamical test facility was constructed for the evaluation and acceptance tests of the attitude control system of the satellite Symphonie. The actual components of the attitude control system are used as hardware in the simulation. The dynamical test fa...

H. Holzach J. Puls K. Reinel

1974-01-01

351

Electro-Magnetic Propulsion System (EMPS) for Spacecrafts and Satellites  

NASA Astrophysics Data System (ADS)

The electro-magnetic propulsion system (EMPS) for driving satellites and other spacecraft has smaller mass, smaller volume, and more efficiency compared with the known systems applied in space technology.

Szentesi, J.

2012-03-01

352

Formation of multiple-satellite systems from circumplanetary particle disks  

NASA Astrophysics Data System (ADS)

In the solar system, most of the planets have satellite systems around them. In systems with a single satellite such as Earth-Moon system, satellite mass is relatively high compared to the host planet’s mass. On the other hand, giant planets such as Jupiter, Saturn have multiple-satellite systems. Generally, their inner major satellites called regular satellites exist outside their Roche limit with relatively small mass ratio to the host planet. Those inner satellites are on nearly circular prograde orbits with low inclination. Formation of large regular satellites of Jupiter and Saturn has been explained by accretion in a circumplanetary gas disk (Canup & Ward 2009). On the other hand, it has been recently shown that regular satellites of Saturn, Uranus and Neptune can be formed from a circumplanetary particle disks within the Roche limit (Crida & Charnoz 2012). Formation of satellites from those particle disks was first studied in the context of lunar formation (Ida, S., et al., 1997). Initially, particles are distributed within the Roche limit and their accretion is prohibited. Then, the disk spreads with time. As the disk spreads and the disk materials diffuse beyond the Roche limit, the materials start to form gravitationally bound aggregates. In the case of relatively massive disk, a large single satellite is its outcome (Ida, S., et al., 1997). However, if the initial disk is less massive, the viscosity of the disk is low and the time scale of disk diffusion is much longer. These aspects expect to lead to the different outcomes. Crida and Charnoz (2012) developed an analytic model for the formation of multiple satellites from a circumplanetary particle disk, with the assumption that the mass flow through the Roche limit is constant. Their model successfully explains the characteristics of the masses and orbits in the satellite systems of Saturn, Uranus and Neptune. However, the details of the evolution of less massive disk are still unclear. In the present work, we perform N-body simulations in order to see the evolution of less massive circumplanetary particle disks, and show that another satellite is secondly formed from a residual disk after the formation of the first satellite.

Hyodo, Ryuki; Ohtsuki, K.; Takeda, T.

2013-10-01

353

Broadband VHF observations for lightning impulses from a small satellite SOHLA-1 (Maido 1)  

NASA Astrophysics Data System (ADS)

Lightning Research Group of Osaka University (LRG-OU) has been developing VHF Broadband Digital Interferometer (DITF) to image precise lightning channels and monitor lightning activity widely. The feature of broadband DITF is its ultrawide bandwidth (from 25MHz to 100MHz) and implicit redundancy for estimating VHF source location. LRG-OU considers an application of the broadband DITF to the spaceborne measurement system and joins the SOHLA (Space Oriented Higashi-Osaka Leading Associate) satellite project. The SOHLA satellite project represents a technology transfer program to expand the range of the space development community in Japan. The objective is to get SMEs (Small and Medium sized manufacturing Enterprises) involved in small space projects and new space technologies. Under the cooperative agreement, JAXA (Japan Aerospace Exploration Agency) intends to contribute to socio-economic development by returning its R&D results to society, and SOHLA tries to revitalize the local economy through the commercialization of versatile small satellites. According to the agreement, JAXA provides SOHLA its technical information on small satellites and other technical assistance for the development of the small satellites, SOHLA-1. The prime objective of the SOHLA-1 program is to realize low-cost and short term development of a microsatellite which utilizes the components and bus technologies of JAXA’s MicroLabSat. SOHLA-1 is a spin-stabilized microsatellite of MicroLabSat heritage (about 50 kg). The spin axis is fixed to inertial reference frame. The spin axis (z-axis) lies in the plane containing the solar direction and the normal to the orbital plane. LRG-OU takes responsibility for a science mission of SOHLA-1. To examine the feasibility of the DITF receiving VHF lightning impulses in space, LRG-OU proposes the BMW (Broadband Measurement of Waveform for VHF Lightning Impulses). BMW consists of a single pair of an antenna, a band-pass filter, an amplifier, and an analog-to-digital converter (ADC) to record broadband VHF pulses in orbit. The waveforms of 100 EM pulses in VHF band emitted from a lightning flash are obtained. Three pairs of BMW with accurate synchronized 3-channel-ADC are needed to realize DITF. From the successful satellite observation like TRMM/LIS, the effectiveness and impact of satellite observations for lightning are obvious. The combination of optical and VHF lightning observations are complimentary each other. ISS/JEM is a candidate platform to realize the simplest DITF and synchronous observations with optical sensors. SOHLA-1 was launched by a HII-A rocket at January 23, 2009 and named Maido-1. Then BMW has worked well and recorded VHF EM waveforms. The development of Maido-1 and its observations results will be presented.

Morimoto, T.; Kikuchi, H.; Ushio, T.; Kawasaki, Z.; Hidekazu, H.; Aoki, T.

2009-12-01

354

FPGA Based On-Board Computer System for the "Flying Laptop" Micro-Satellite  

NASA Astrophysics Data System (ADS)

The availability of new high density FPGA technologies enables innovative approaches to the architecture of onboard computer systems (OBCS) for demanding small satellite applications. In the paper, we present the architecture of a highly integrated satellite computer exploit- ing the powerful features of Xilinx's Virtex-II Pro FPGA technology. The computing resources of the "Flying Laptop" satellite are provided by a single OBCS performing the control functions of a traditional satellite bus controller (SBC) as well as all tasks of the payload data handling and processing system (PDH). The unification of the different computing functions on board the satellite onto a single but highly redundant computer system results in clear-cut system structure and provides a high degree of fault tolerance with minimal resource requirements. The "Flying Laptop" micro satellite is under development at the Institute of Space Systems at the Universität Stuttgart. The primary mission objective is to demonstrate and qualify new small-satellite technologies for the future projects. In addition, the three main scientific payloads of the satellite will allow performing a number of ambitious earth observation experiments. According to the primary mission objectives, the OBCS itself will be a subject for evaluations of its innovative concepts and for qualification of its underlying hardware.

Huber, F.; Behr, P.; Röser, H.-P.; Pletner, S.

2007-08-01

355

Modular Antenna Pointing System for the Explorer Platform Satellite.  

National Technical Information Service (NTIS)

A Modular Antenna Pointing System (MAPS) is described which was designed for on-orbit servicing and on-orbit exchange. The MAPS provides a data link between the Explorer Platform (EP) satellite and the Tracking and Data Relay Satellite (TDRS). The MAPS co...

J. Andrus E. Korzeniowski

1992-01-01

356

Multiple-satellite observation of the high-latitude auroral activity on January 11, 1983  

SciTech Connect

Unusual high-latitude auroral activity occurred on January 11, 1983, during a period of persistent interplanetary magnetic field Bz > 0, By > 0, and Bx > 0. This activity, which lasted from 0600 to 2100 UT, was characterized by numerous high-latitude sun-aligned arcs and a diffuse oval. Near 1500 UT, a single broad (250 km) sun-aligned arc was observed by the optical line scan system on Defense Meteorological Satellite Program (DMSP) F6. The arc was continguous with the dawn auroral oval and extended across the northern polar cap, similar to previously reported theta aurora configurations. The fortunate orbital locations of the DMSP F6, NOAA 7, and NOAA 6 satellites allow a detailed analysis of the precipitating-particle populations responsible for both the sun-aligned arc and oval auroras. Specifically, NOAA 7 and DMSP F6 cross the broad sun-aligned arc almost simultaneously in the northern hemisphere, with NOAA 7 crossing the arc 1500 km farther toward the dayside. During the arc crossing, NOAA 7 observes electron fluxes, temperatures, and accelerations similar to those observed by DMSP F6 but observes ion fluxes diminished by a factor of 50 in comparison with DMSP. Almost simultaneously, NOAA 6 crosses the southern polar cap and observes flux levels in an apparent high-latitude arc comparable to those observed by DMSP. The results are consistent with, but supplementary to, previous observations of high-latitude auroral observations and thus place meaningful constraints on emerging theoretical concepts of this phenomenon.

Gorney, D.J.; Evans, D.S.; Gussenhoven, M.S.; Mizera, P.F.

1986-01-01

357

Global Terrestrial Observing System  

NSDL National Science Digital Library

The Global Terrestrial Observing System (GTOS) is used to facilitate communication regarding world ecological research networks. There are also tools on this website to describe the three regional observation programs in Southern Africa and Central and Eastern Europe. The shared information includes data on Net Primary Production (NPP), Terrestrial Carbon Observation (TCO), Terrestrial Panel on Climate (TOPC), and Global Observation of Landcover Dynamics. Users can also access Terrestrial Ecosystem Monitoring Sites (TEMS), which concentrate on remote sensing data collection from over 500 individual sites located in primarily mountain or coastal regions. The TEMS program began in the early 1990's and is the international equivalent of Long Term Ecological Research sites found primarily in North America. TEMS are used to link ground and remotely sensed observations as well as to provide temporal assessment of ecological conditions. Other general data collected includes land quality, water resources, climate change, biodiversity, pollution and toxicity, global/ regional/ national environments, and international conventions.

2002-01-17

358

The National Polar-orbiting Operational Environmental Satellite System  

NASA Astrophysics Data System (ADS)

The tri-agency Integrated Program Office (IPO) is responsible for managing the development of the National Polar-orbiting Operational Environmental Satellite System (NPOESS). NPOESS will replace the current military and civilian operational polar-orbiting ``weather'' satellites. The Northrop Grumman Space Technology - Raytheon team was competitively selected in 2002 as the Acquisition and Operations contractor team to develop, integrate, deploy, and operate NPOESS satellites to meet the tri-agency user requirements for NPOESS over the 10-year (2009-2018) operational life of the program. Beginning in 2009, NPOESS spacecraft will be launched into three orbital planes to provide significantly improved operational capabilities and benefits to satisfy critical civil and national security requirements for space-based, remotely sensed environmental data. With the development of NPOESS, we are evolving operational ``weather'' satellites into integrated environmental observing systems by expanding our capabilities to observe, assess, and predict the total Earth system - atmosphere, ocean, land, and the space environment. In recent years, the operational weather forecasting and climate science communities have levied more rigorous requirements on space-based observations of the Earth's system that have significantly increased demands on performance of the instruments, spacecraft, and ground systems required to deliver NPOESS data, products, and information to end users. The ``end-to-end'' system consists of: the spacecraft; instruments and sensors on the spacecraft; launch support capabilities; the command, control, communications, and data routing infrastructure; and data processing hardware and software. NPOESS will observe significantly more phenomena simultaneously from space than its operational predecessors. NPOESS is expected to deliver large volumes of more accurate measurements at higher spatial (horizontal and vertical) and temporal resolution at much higher data rates and with more frequent space-to-ground data communications than are currently in use. When NPOESS reaches full operational capability in 2013, spacecraft in all three orbital planes will provide global coverage with a data refresh rate of approximately four hours for most observations. User demands for more real-time data from NPOESS are driving the space and ground-based architectures for data routing and retrieval that will dramatically shorten data latency. To meet user-validated requirements for 55 geophysical parameters, NPOESS will deliver global data to four U.S. centers for processing and distribution to end users. Global data will be down-linked to 15 globally-distributed, low-cost, unmanned ground stations that will be tied to these four processing centers via commercial fiber-optic networks. This innovative ground system will deliver 75% of the global (daily average) within 15 minutes and 95% of the data (daily average) within 26 minutes from the time of on-orbit collection. NPOESS spacecraft will also simultaneously broadcast two types of real-time data to suitably equipped ground stations. Early flight-testing of instruments will reduce development risk and demonstrate and validate global imaging and sounding instruments, algorithms, and pre-operational ground systems prior to the first NPOESS flight in 2009. Four NPOESS sensors are scheduled to fly on the joint National Aeronautics and Space Administration (NASA)/IPO NPOESS Preparatory Project (NPP) mission in 2006. Early system-level integration and testing will provide ``lessons learned'' and allow for any required modifications in time to support readiness for the first NPOESS launch in 2009. NPP will demonstrate the utility of improved imaging and radiometric data in short-term weather ``nowcasting'' and forecasting and in other oceanic and terrestrial applications, such as harmful algal blooms, volcanic ash, and wildfire detection. NPP will help ensure continuity of important climate-quality measurements during the transition from NASA's Earth Observing System Terra and Aqua research mis

Bloom, H.

359

Solar Power Satellite System Definition Study, Phase 2. Volume 2: Reference System Description.  

National Technical Information Service (NTIS)

System descriptions and cost estimates for the reference system of the solar power satellite program are presented. The reference system is divided into five principal elements: the solar power satellites; space construction and support; space and ground ...

1979-01-01

360

Direct broadcast satellite systems in Europe  

NASA Astrophysics Data System (ADS)

The technologies implemented by DBS services to meet the WARC '77 guidelines for European coverage are detailed for each member of the EEC. The national footprints are required to have a power flux density of -103 dBW/sq m at the edge and be receivable by a 0.9 m diam antenna. An antenna maximum beamwidth of 2 deg was specified, while satellite output powers can range from 40-230 W, depending on the region of coverage. The TDF-1, TV-Sat, Tele-X, and Olympus satellites are under development for the various countries. It is noted that overspill at the transmitter powers selected will cause significant transnational broadcasting to occur. Smaller countries are negotiating leases on some of the transponders of satellites developed in larger countries to lower their own developmental costs. Uncertainties in the markets for the DBS services have delayed nationally funded projects from being launched.

Tydeman, J.

1985-01-01

361

Analysis of the Arctic heat and moisture budgets in WRF: a comparison with reanalyses and satellite observations  

Microsoft Academic Search

Satellite based observations indicate negative trends in Arctic sea ice extent in all months, sharpest for September. Declining ice extent will have profound impacts on the Arctic's energy and moisture budgets, with cascading influences on the atmospheric circulation and the Arctic's hydrologic cycle. Few of the IPCC AR4 global climate system models can reproduce the strong downward trend in September

D. Porter; J. J. Cassano; M. C. Serreze

2009-01-01

362

The impact of orbital sampling, monthly averaging and vertical resolution on climate chemistry model evaluation with satellite observations  

Microsoft Academic Search

Ensemble climate model simulations used for the Intergovernmental Panel on Climate Change (IPCC) assessments have become important tools for exploring the response of the Earth System to changes in anthropogenic and natural forcings. The systematic evaluation of these models through global satellite observations is a critical step in assessing the uncertainty of climate change projections. This paper presents the technical

A. M. Aghedo; K. W. Bowman; D. T. Shindell; G. Faluvegi

2011-01-01

363

Engineering calculations for communications satellite systems planning  

NASA Astrophysics Data System (ADS)

Progress is reported on a computer code to improve the efficiency of spectrum and orbit utilization for the Broadcasting Satellite Service in the 12 GHz band for Region 2. It implements a constrained gradient search procedure using an exponential objective function based on aggregate signal to noise ratio and an extended line search in the gradient direction. The procedure is tested against a manually generated initial scenario and appears to work satisfactorily. In this test it was assumed that alternate channels use orthogonal polarizations at any one satellite location.

Martin, C. H.; Gonsalvez, D. J.; Levis, C. A.; Wang, C. W.

1983-12-01

364

Gamma-Ray Burst Groups Observed by Different Satellites  

SciTech Connect

Two classes of gamma-ray bursts have been identified in the BATSE catalogs characterized by durations shorter and longer than about 2 seconds. There are, however, some indications for the existence of a third one. Swift satellite detectors have different spectral sensitivity than pre-Swift ones for gamma-ray bursts. Therefore it is worth to reanalyze the durations and their distribution and also the classification of GRBs. In this paper we are going to analyze the bursts' duration distribution and also the duration-hardness bivariate distribution, published in The First BAT Catalog, whether it contains two, three or maybe more groups. Similarly to the BATSE data, to explain the BAT GRBs duration distribution three components are needed. Although, the relative frequencies of the groups are different than they were in the BATSE GRB sample, the difference in the instrument spectral sensitivities can explain this bias in a natural way. This means theoretical models may have to explain three different type of gamma-ray bursts.

Horvath, Istvan [Bolyai Military University, Budapest (Hungary); Balazs, Lajos G. [Konkoly Observatory, Budapest (Hungary); Veres, Peter [Bolyai Military University, Budapest (Hungary); Eotvos University, Budapest (Hungary)

2009-05-25

365

Electromagnetic ELF radiation from earthquake regions as observed by low-altitude satellites  

Microsoft Academic Search

Seismoelectromagnetic waves observed by low-altitude satellites passing over seismic regions were studied. The data of the Cosmos-1809 satellite were analyzed over an earthquake region. Intense EM radiation at frequencies below 450 Hz was observed at the L-shells of the earthquake, during 12 orbits out of the 13 that passed within 6 deg in longitude from the epicenter, and during 1

O. N. Serebriakova; S. V. Bilichenko; V. M. Chmyrev; M. Parrot; J. L. Rauch; F. Lefeuvre; O. A. Pokhotelov

1992-01-01

366

Climate Observing Systems: Data System Challenges  

NASA Astrophysics Data System (ADS)

Existing observing and data systems have provided considerable information about past climate variations and changes. The recent reports by the Intergovernmental Panel on Climate Change, the National Research Council, and the USGCRP National Assessment of Climate Variability and Change are testaments to a vast array of knowledge. These reports also expose some serious deficiencies in our ability to discern past climate variations and change which lead to substantial uncertainties in key climate state, climate feedback, and climate forcing variables. How significant are these uncertainties? For climate trends that have our highest confidence, like the change in mean global surface temperature, the 95 percent confidence intervals amount to about two-thirds of the calculated change. With such large uncertainties it is exceedingly difficult to discern accelerated changes. For other variables, especially variables related to climate feedbacks and forcings (with exceptions for long-lived and well-mixed greenhouse gases like CO2 or CH4) or climate and weather extremes, we often have little or no information to discern trends or cannot objectively assess confidence intervals. Do we know how to reduce existing uncertainties? First and foremost, a climate observation oversight and monitoring capability is needed that tracks the gathering of the data, the processing system, and the performance of the observations, especially time-dependent biases. An organized capability does not now exist, but could be developed at a new and/or existing centers. This center(s) should then have the means and influence to fix problems and be able to establish requirements for new in-situ and satellite observing including related data systems. Such a capability should complement the following: (1) Climate observations from both space-based and in-situ platforms that are taken in ways that address climate needs and adhere to the ten principles outlined by the NRC (1999 Adequacy of Climate Observing Systems) and GCOS. An international framework is vital. (2) A global telecommunications network and satellite data telemetry capacity to enable data and products to be disseminated. (3) A climate observations analysis capability that produces global and regional analyses of various products for the atmosphere, oceans, land surface and hydrology, and the cryosphere. (4) Four dimensional data assimilation capabilities that process the multivariate data in a physically consistent framework to enable production of the analyses, not just for the atmosphere but also for the oceans, land surface and so on. (5) Global climate models that encompass all parts of the climate system and which are utilized to design effective sampling strategies and evaluate observations. These improvements primarily relate to the data system, after the observation has been made, but they must be accompanied with a concerted effort to improve our instrumentation, platforms, and sampling resolutions for key climate variables. How much would such a data system cost? Practical experience has shown that an effective archive and access system can be designed for about 5 to 10 percent of the total cost of the observing system. Building on a solid investment in data management infrastructure and hardware (including data quality control, access, and long-term stewardship), a comparable investment would be required to address oversight, monitoring, data analysis, data assimilation, and adherence to the ten principles. An implementation time frame on the order of five to ten years is probably a realistic time frame, similar to the planning and implementation horizon of major new observing systems.

Karl, T. R.

2001-12-01

367

Mobile-satellite systems: a perspective on technology and trends  

Microsoft Academic Search

Upto just past the turn of the century several mobile-satellite systems will be in commercial operation. These systems will co-exist with terrestrial cellular systems augmenting their coverage and providing wide area roaming via the use of dual-mode (satellite-cellular) phones. Handheld phones that are competitive in size and features with cellular phones are a key factor for commercial success of a

N. Rydbeck; S. Chennakeshu; P. Dent; A. Hassan

1996-01-01

368

Japanese climate change observation system for next generation  

NASA Astrophysics Data System (ADS)

Japanese satellite for climate change observation, named ADEOS-II, was lost in October 2003. A quick concept study to compensate the loss of ADEOS-II was made. Regarding climate change study, we found the importance to monitor human activity effect for climate change is important as well as to study the natural climate system and variation by global observation. Moreover, the results from previous satellite ADEOS-II suggests the possibility of global observation and human activity monitoring, which requires certain resolution to distinguish regional change. Thus, the concept of the mission objectives is focusing human activity effect on climate change. The new system, named Global Change Observation Mission: GCOM, consists of two satellites. One satellite carrying microwave radiometer: AMSR2 and a scattarometer, and another satellite carrying multi-spectral imaging radiometer: SGLI. These satellites are named GCOM-winds: GCOM-W and GCOM-climate: GCOM-C, respectively. This system will be continued for over 13 years to observe climate change together with other specific Japanese or Japanese joined satellites, namely, Greenhouse gas observation satellites: GOSAT, Global precipitation measurement: GPM with NASA and Earth cloud aerosol and radiation explorer: EarthCARE with ESA. GCOM-W and GCOM-C are proposed to be launched in 2009 and 2010, respectively.

Kimura, Toshiyoshi; Tange, Yoshio; Matsuura, Naoto; Otsuki, Fumio; Shimoda, Haruhisa

2005-01-01

369

Satellite tracking system analysis through computer simulation  

Microsoft Academic Search

An outline of the Satellite Orbit Determination Program (SORD-II), developed at Yokosuka Electrical Communication Laboratory, is presented. This program uses the general perturbation theory proposed by Kozai (1959) and the weighted least squares method. Through computer simulation, it is confirmed that the program works satisfactorily. At the same time, several conclusions are reached about tracking station disposition conditions and tracking

Y. Nagai

1977-01-01

370

Image sets for satellite image processing systems  

NASA Astrophysics Data System (ADS)

The development of novel image processing algorithms requires a diverse and relevant set of training images to ensure the general applicability of such algorithms for their required tasks. Images must be appropriately chosen for the algorithm's intended applications. Image processing algorithms often employ the discrete wavelet transform (DWT) algorithm to provide efficient compression and near-perfect reconstruction of image data. Defense applications often require the transmission of images and video across noisy or low-bandwidth channels. Unfortunately, the DWT algorithm's performance deteriorates in the presence of noise. Evolutionary algorithms are often able to train image filters that outperform DWT filters in noisy environments. Here, we present and evaluate two image sets suitable for the training of such filters for satellite and unmanned aerial vehicle imagery applications. We demonstrate the use of the first image set as a training platform for evolutionary algorithms that optimize discrete wavelet transform (DWT)-based image transform filters for satellite image compression. We evaluate the suitability of each image as a training image during optimization. Each image is ranked according to its suitability as a training image and its difficulty as a test image. The second image set provides a test-bed for holdout validation of trained image filters. These images are used to independently verify that trained filters will provide strong performance on unseen satellite images. Collectively, these image sets are suitable for the development of image processing algorithms for satellite and reconnaissance imagery applications.

Peterson, Michael R.; Horner, Toby; Temple, Asael

2011-05-01

371

Joint Polar Satellite System Common Ground System Overview  

NASA Astrophysics Data System (ADS)

Jointly acquired by NOAA & NASA, the next-generation civilian environmental satellite system, Joint Polar Satellite System (JPSS), will supply the afternoon orbit & ground system of the restructured NPOESS program. JPSS will replace NOAA's current POES satellites and the ground processing part of both POES & DoD's Defense Weather Satellite System (DWSS)(DMSP replacement). JPSS sensors will collect meteorological, oceanographic, climatological and solar-geophysical data. The ground system, or JPSS Common Ground System (CGS), has 6 integrated product teams/segments: Command, Control & Communications (C3S); Interface Data Processing (IDPS); Field Terminal (FTS); Systems Engineering, Integration & Test (SEIT); Operations & Support (O&S); and Sustainment developed by Raytheon Intelligence & Information Systems. The IDPS will process JPSS data to provide Environmental Data Records (EDRs) to NOAA & DoD processing centers beginning with the NPOESS Preparatory Project (NPP) and through JPSS & DWSS eras. C3S will: manage overall JPSS & DWSS missions from control/status of space/ground assets to ensure timely delivery of high-quality data to IDPS; provide globally-distributed ground assets to collect/transport mission, telemetry and command data between satellites & processing locations; provide all commanding & state-of-health monitoring functions of NPP, JPSS and DWSS satellites, and delivery of mission data to each Central IDP and monitor/report system-wide health/status and data communications with external systems and between CGS segments. SEIT leads the overall effort, including: manage/coordinate/execute JPSS CGS activities with NASA participation/oversight; plan/conduct all activities related to systems engineering, develop & ensure completeness of JPSS CGS functional & technical baselines and perform integration, deployment, testing and verification; sponsor/support modeling & simulation, performance analysis and trade studies; provide engineering for the product segments to implement proper security controls and directly manage integration, test & verification of product segments into the system. O&S operates the JPSS CGS, performs all mission operations and provides onsite support & logistics. O&S responsibilities range from developing, training, maintaining, and executing operational procedures; tracking/resolving anomalies; scheduling, measuring, trending and tracking all Program resources; to securing all assets. O&S has operated/supported the NPP C3S & IDPS baselines since Oct 2008 and Jul 2009 deliveries, respectively. Sustainment updates & maintains H/W & S/W baselines at Raytheon facilities in Colorado & Nebraska. They have done this for the NPP C3S & IDPS baselines since Oct 2008 and Jul 2009, respectively. This presentation will also give an overview of the JPSS CGS ground architecture features & enhancements for the JPSS (post-NPP) era. These include: C3S-provided space-to-ground connectivity, reliable/secure data delivery and insight/oversight of total operations; added ground receptor sites to reduce data latency; delivery of added sensor data products from NPP-like and additional JPSS sensors and expansion to 2 more Centrals (FNMOC & NAVO). The IDPS will act as a buffer to minimize changes in how users request/receive data products.

Jamilkowski, M. L.; Smith, D. C.

2011-12-01

372

Satellite Observations of Elevated Carbon Monoxide in Eyjafjallajökull Volcanic Emissions  

NASA Astrophysics Data System (ADS)

Volcanic degassing before, during, and after eruptions produces gases such as H2O, CO2, and SO2 (dominant species) as well as H2, H2S, HCl, CO, and S2 (minor species). While dominant volcanic gases have been successfully analyzed from orbit in the past, the minor components are still measured only in situ, with all the consequent limitations in safety and sampling, and at elevated costs. Here we present a case study where (for the first time, to our knowledge) elevated CO values consistent with a volcanic origin (the 2010 Eyjafjallajökull eruption in Iceland) were identified in satellite data products from MOPITT and IASI (the Measurements of Pollution in the Troposphere instrument and the Infrared Atmospheric Sounding Interferometer, respectively). Remote measurements of volcanic CO would contribute to a better understanding of volcanic degassing and improve atmospheric chemistry models. The 2010 Eyjafjallajökull eruption extended over three months, emitting an estimated 150,000 tonnes/day of CO2 and up to 6,800 tonnes/day of SO2. The plume-like positive anomaly we have detected in MOPITT CO retrievals coincides spatially and temporally with positive IASI CO, IASI SO2, and OMI SO2 anomalies, as well as with an optically thick plume emanating from the Eyjafjallajökull Volcano, evident in MODIS visible data. Initial MOPITT modeling results show that uncertainties in water vapor content alone could not explain the CO anomaly. We will further discuss the effect of elevated water vapor and aerosols (both abundant during volcanic activity) in the MOPITT CO retrievals. We will also contrast the CO anomaly with the expected amount of volcanic CO emissions, given CO2 and SO2 measurements available for the Eyjafjallajökull eruption and the SO2/CO and CO2/CO ratios documented in the literature for other eruptions in similar tectonic settings.

Martinez-Alonso, S.; Deeter, M. N.; Worden, H. M.; Clerbaux, C.; Mao, D.; Gille, J. C.

2011-12-01

373

Velocity observations of the California Current derived from satellite imagery  

NASA Astrophysics Data System (ADS)

This research examines the potential of ocean velocity observations generated from the maximum cross-correlation technique (MCC) applied to thermal infrared imagery to capture the total current at a high sampling rate, especially in the nearshore region, allowing for a novel view of the California Current. Comparison of 12 years of weekly ocean velocity fields derived from the MCC method with velocity observations from drifting buoys reveals strong correspondence between the data sets. The MCC method, however, is able to produce over ˜10 times the number of observations. Comparison of MCC velocities with geostrophic velocities from altimetry demonstrates differences that suggest ageostrophic currents in the MCC observations that are likely wind driven. The time-averaged mean velocity field from MCC observations reveals strong offshore jet-like features that extend off of coastline promontories. Eddy statistics from the MCC velocity observations indicate dramatically different dynamics in the nearshore and offshore regions. Differences in spatial statistics derived from the MCC observations compared to previous studies of the region are attributed to wind-driven currents in the observations that can dominate the variability of the current in the nearshore region.

Matthews, D. K.; Emery, W. J.

2009-08-01

374

Replacing climatological potential evapotranspiration estimates with dynamic satellite-based observations in operational hydrologic prediction models  

NASA Astrophysics Data System (ADS)

In the face of a changing climate, growing populations, and increased human habitation in hydrologically risky locations, both short- and long-range planners increasingly require robust and reliable streamflow forecast information. Current operational forecasting utilizes watershed-scale, conceptual models driven by ground-based (commonly point-scale) observations of precipitation and temperature and climatological potential evapotranspiration (PET) estimates. The PET values are derived from historic pan evaporation observations and remain static from year-to-year. The need for regional dynamic PET values is vital for improved operational forecasting. With the advent of satellite remote sensing and the adoption of a more flexible operational forecast system by the National Weather Service, incorporation of advanced data products is now more feasible than in years past. In this study, we will test a previously developed satellite-derived PET product (UCLA MODIS-PET) in the National Weather Service forecast models and compare the model results to current methods. The UCLA MODIS-PET method is based on the Priestley-Taylor formulation, is driven with MODIS satellite products, and produces a daily, 250m PET estimate. The focus area is eight headwater basins in the upper Midwest U.S. There is a need to develop improved forecasting methods for this region that are able to account for climatic and landscape changes more readily and effectively than current methods. This region is highly flood prone yet sensitive to prolonged dry periods in late summer and early fall, and is characterized by a highly managed landscape, which has drastically altered the natural hydrologic cycle. Our goal is to improve model simulations, and thereby, the initial conditions prior to the start of a forecast through the use of PET values that better reflect actual watershed conditions. The forecast models are being tested in both distributed and lumped mode.

Franz, K. J.; Bowman, A. L.; Hogue, T. S.; Kim, J.; Spies, R.

2011-12-01

375

Petermann Glacier, North Greenland: Large Ice-Discharge Episodes from 20 Years of Satellite Observations  

NASA Astrophysics Data System (ADS)

The major marine-terminating outlet glaciers of Greenland can undergo large mass losses through calving of icebergs and bottom melting from floating ice tongues. Recent observations of outlet glaiers around Greenland have shown that large and rapid changes in solid-ice fluxes are possible. The Petermann glacier in remote northern Greenland is the region’s largest floating-tongue glacier (~70 km by 10 km). In summer 2008 a large calving event was observed, as well as large cracks upstream of the remaining calving front, portending a more massive near-term loss. These observations may herald extraordinary and unprecedented change. However, the long-term variability of calving events and ice velocities are poorly known. Our research goal here is to identify the temporal variability and possible trends in solid-ice flux indicators - variability of the calving front and ice velocity - for Petermann glacier. The methodological approach is observational, based primarily on analysis of 20 years of repetitive satellite data over a period starting from 1990, together with sporadic earlier observations. The multisensor data range from high-resolution optical images from Landsat, SPOT and Terra ASTER and high-resolution synthetic aperture radar (SAR) images from ERS and ENVISAT. These disparate data have been imported, geo-registered and analysed within a Geographic Information System. The following measurements are made: (1) delineating changes in the calving front, (2) estimating the area of glacial ice loss during calving events, and (3) estimating the ice-surface velocity using sequential satellite images. We find evidence of a number of previous calving episodes of similar magnitude to the summer 2008. The ice-velocity estimates compare well with other estimates for particular years, and moreover are relatively consistent during the 20-year period. These findings suggest business-as-usual for Petermann glacier; however, a near-term calving event exceeding those observed over the past 20 years cannot be ruled out.

Babiker, M.; Johannessen, O. M.; Miles, M. W.; Miles, V. V.

2009-12-01

376

The changing world of global navigation satellite systems  

NASA Astrophysics Data System (ADS)

The world of global navigation satellite systems (GNSS) has been changing very rapidly during the last years. New constellations are being developed in Europe (Galileo), India (IRNSS), Japan (QZNSS) and China (Compass), while both the US GPS and the Russian GLONASS programmes are engaged in very significant mediumto long-term improvements, which will make them even more valuable in the coming years to an ever wider range of civilian users. In addition, powerful regional augmentation systems are becoming (or have already become) operational, providing users with important real time information concerning the integrity of the signals being broadcast by those two systems: these include the US WAAS, the European EGNOS, the Japanese MSAS, the Indian GAGAN and others. Following a number of United Nations sponsored regional workshops, a report by an ad hoc UN "GNSS Action Team" and several preparatory meetings, the International Committee on GNSS (ICG) was established in December 2005 in Vienna, Austria. The ICG is an informal body with the main objective of promoting cooperation on matters of mutual interest related to civil satellite-based positioning, navigation, timing, and value-added services, as well as compatibility and interoperability among the GNSS systems. A further important objective is to encourage the use of GNSS to support sustainable development, particularly in the developing countries. The United Nations Office for Outer Space Affairs (UNOOSA) plays a key role in facilitating the work of the ICG. The members of the Committee are GNSS system providers, while international organisations representing users of GNSS can qualify for participation in the work of the Committee as associate members or observers. The interests of the space geodetic, mapping and timing communities are represented in particular through ICG associate membership of the IGS, IAG, FIG, IERS, while BIPM is an ICG observer. This paper will highlight the background of these developments and focus on the concerns of the ICG, especially from the point of view of the user organisations.

Dow, John M.; Neilan, Ruth E.; Higgins, Matt; Arias, Felicitas

377

The study of enhanced earth observations on a satellite image chain  

NASA Astrophysics Data System (ADS)

The Multi-Spectral Camera (MSC) on the KOrea Multi-Propose SATellite (KOMPSAT)-2 was developed and launched as a main payload to provide a One(1) m panchromatic image and four(4) band four(4) m multi-spectral images at an altitude of 685 km covering a swath width of 15 km. These images, archived around the world, are a useful resource for space applications in agriculture, cartography, geology, forestry, regional planning, surveillance, and national security. The image quality of KOMPSAT-2 depends upon its image chain, which is comprised of an on-board system in the satellite and a processing system at the ground station. Therefore, in this study we determine the factors that have a major impact on the image quality through an investigation of the entire image chain. Consequently, two methods, involving a compression algorithm and a deconvolution technique, were determined as having a significant influence on the KOMPSAT-2 image quality. The compression algorithm of KOMPSAT-2 is rate-controlled JPEG-like algorithm that controls the mismatch between the input and output data rate. The ability to control the input/output data rate may be useful during the operation of the satellite but can also lower the overall image quality. The deconvolution technique may increase the sharpness of images, but it can also amplify the image noise level. Therefore, we propose methods of wavelet-based compression and denoising as an alternative to currently existing algorithms. Satisfactory results were obtained through experimentation with these two algorithms, and they are expected to be successfully implemented into the future KOMPSAT series to yield high-quality images for enhanced earth observation.

Yong, Sang-Soon; Choi, Myungjin; Ra, Sung-Woong

2011-10-01

378

Space-based augmentation for global navigation satellite systems.  

PubMed

This paper describes space-based augmentation for global navigation satellite systems (GNSS). Space-based augmentations increase the accuracy and integrity of the GNSS, thereby enhancing users' safety. The corrections for ephemeris, ionospheric delay, and clocks are calculated from reference station measurements of GNSS data in wide-area master stations and broadcast via geostationary earth orbit (GEO) satellites. This paper discusses the clock models, satellite orbit determination, ionospheric delay estimation, multipath mitigation, and GEO uplink subsystem (GUS) as used in the Wide Area Augmentation System developed by the FAA. PMID:22481784

Grewal, Mohinder S

2012-03-01

379

Defense satellite communications system - Past, present, and future  

NASA Astrophysics Data System (ADS)

This is a critical point in the long history of the Defense Satellite Communications System. This workhorse communications system has developed from the humble beginnings in the 1960s into today's highly capable backbone of U.S. Government Communications. After a long delay these satellites are being launched again and plan to quickly rebuild this critical national asset which has been held together by determination and sweat following the Challenger disaster. The critical issue is what services shall DSCS provide in the future. The process of defining the SHF communications capability of the next generation of these satellites to support the military needs of the next century is under way.

Cook, Robert G.

1992-03-01

380

Queueing Models for Designing Digital Communication Satellite Systems.  

National Technical Information Service (NTIS)

Satellites have an enormous potential for providing efficient communication links between many widely scattered ground stations. By interpreting the messages as customers in a queueing system, an unusual type of queueing model can be formulated to describ...

F. S. Hillier B. Jabbari

1982-01-01

381

Alternative Multiple-Access Techniques for Mobile Satellite Systems.  

National Technical Information Service (NTIS)

The use of Code Division Multiple Access (CDMA) to satisfy the diverse requirements of a generic (land, maritime, aeronautical) mobile satellite system (MSS) network design is discussed. Comparisons between CDMA and Frequency Division Multiple Access (FDM...

P. O. Smith E. Geraniotis

1989-01-01

382

Use of Iridium, a Commercial Telecommunications Satellite System, in Wartime.  

National Technical Information Service (NTIS)

This study investigates the capabilities and limitations of the commercial telecommunications satellite system, Iridium. In view of the increasing demands for immediate communications in the modern theaters of war, the study analyzes the utility that Irid...

T. L. Yoder

1996-01-01

383

Observing System Simulation Experiment for Global Precipitation Mission  

Microsoft Academic Search

From the suite of future Global Precipitation Mission (GPM) satellites we have selected 11 of the possible contributors to the NASA's International precipitation measurement program. The Observing System Simulation Experiments (OSSE) presented here explores the predictive usefulness of this suite of satellites. In order to carry out such experiments a Nature Run based on results from a state of the

A. K. Mishra; T. N. Krishnamurti

2011-01-01

384

The role of satellite observations through the whole disaster monitoring cycle: the impact of new satellite constellations and of collaborative approaches  

NASA Astrophysics Data System (ADS)

The contribution of satellite observations to the complete disaster monitoring cycle is to day not fully demonstrated. Several isolated examples exist for the monitoring of the various phases of a disaster cycle. None of them is showing the full capability of satellite observations to contribute to the whole cycle. Recent more open-minded approaches, based on a collaborative use of satellite resources and observation capabilities, show a promise of an improved availability of satellite observations to support the whole disaster monitoring cycle. Several initiatives pave the way towards a more effective and enlarged use of satellite observations in this domain. The International Charter for disaster monitoring, created in 1998 by CNES and ESA, has been extremely effective in demonstrating the interest of satellite observations in the post-event activities but, by itself, it falls short of demonstrating an operational, long term and sustainable contribution of satellite data to the complete disaster monitoring cycle. CEOS has since long attempted a system approach to disaster monitoring, and its recent "Consensus Report" of the ad hoc disaster team shows clearly how a collaborative approach, organizing the potential contributions of different missions and actors, may well provide a more consistent and sustained response to the requirements expressed by stakeholders and actors. GEO has sponsored some important activities, also supported by CEOS and a plethora of actors in the field: the science oriented GEO-hazards supersites initiative is undoubtedly one of the most promising efforts of coordination in the domain. The paper will introduce the opportunities offered by the GMES Collaborative Ground Segment to develop sustainable EO-based services to be operated at national level. These initiatives show the importance of coordination and of the need for a sustained access to several data sources, in order to meet the requirements of the disaster monitoring cycle. The same initiatives indicate that substantial efforts are underway to make available consistent series of satellite data for the long term monitoring of disaster prone areas and in order to facilitate post-disaster activities. The paper will depict, on this background, how local efforts have to connect to global initiatives, taking into account the specificity of disaster situations, how in particular a favourable situation is developing in Europe with the coming into operation of the sentinel satellites and with the availability of national missions of extreme interest for disaster monitoring. The European picture guarantees a long term availability of critical data sets and indicates the way for a wider international cooperation, which is well in the makings by the agencies in CEOS. Without large scale cooperation and a well conceived approach to coordinated observations, all efforts in this domain are bound to fail. Without extremely efficient local nodes for data access and tailored services no large scale international coordination will succeed.

Bruzzi, Stefano; Candela, Laura

2013-04-01

385

A conceptual design of PRISM-2 for Advanced Land Observing Satellite-3(ALOS-3)  

NASA Astrophysics Data System (ADS)

The Japan Aerospace Exploration Agency (JAXA) is planning a satellite system including Advanced Land Observing Satellites 2 and 3 (ALOS-2 and ALOS-3) for the ALOS follow-on program. ALOS-3 will carry the optical sensor named "PRISM-2" and extend the capabilities of earlier ALOS missions. PRISM-2 will be able to collect high-resolution (0.8m) and wide-swath (50 km) imagery with high geo-location accuracy, as well as provide precise digital surface models (DSMs) using stereo pair images acquired by two telescopes. These capabilities are ideal for obtaining large-scale geographical information such as elevation and land cover-maps for use in many research areas and practical applications, including disaster management support. JAXA has conducted a phase A study of the ALOS-3 spacecraft and PRISM-2, and is now working on prototype models of key components of PRISM-2's telescope, focal plane, and data compressor. This paper introduces a conceptual design for PRISM-2 and the ALOS-3 system.

Imai, Hiroko; Katayama, Haruyoshi; Sagisaka, Masakazu; Hatooka, Yasushi; Suzuki, Shinichi; Osawa, Yuji; Takahashi, Masuo; Tadono, Takeo

2012-09-01

386

Refractive aiming corrections for satellite observation of stars  

SciTech Connect

Standard references describe how apparent zenith angles differ from true zenith angles for observers on the Earth. In fact, correction formulae are available for aiming Earth-based sensors at stars; some corrections give variations as a function of observer altitude. Such corrections have not been available for observers in space. This report develops formulae appropriate for proper aiming from space-based sensors toward the relatively few stars that are near the Earth`s limb at any given time. These formulae correct for refractive effects and may be critical for steerable space-borne sensors with fields of view less than one degree, tasked to observe starlight passing near the Earth`s surface. Ray tracing in the U.S. Standard Atmosphere, 1976 including H{sub 2}O effects, is used to determine relations between the refracted tangent height, the apparent tangent height resulting from observation at the sensor, and the angle through which the detected rays have deviated. Analytic fits of the ray deviation as a function of apparent tangent height allows quick determination of corrections needed for a space-borne sensor. Using those results that apply in the plane of incidence and using the necessary coordinate rotations, alterations in the star`s apparent right ascension and declination are evaluated to improve the aim. Examples illustrate that alterations can be larger than one degree, with effects lasting up to a few minutes.

Vittitoe, C.N.; Schmidt, R.L.

1997-03-01

387

Refractive aiming corrections for satellite observation of stars  

NASA Astrophysics Data System (ADS)

Standard references describe how apparent zenith angles differ from true zenith angles for observers on the Earth. In fact, correction formulae are available for aiming Earth-based sensors at stars; some corrections give variations as a function of observer altitude. Such corrections have not been available for observers in space. This report develops formulae appropriate for proper aiming from space-based sensors toward the relatively few stars that are near the Earth's limb at any given time. These formulae correct for refractive effects and may be critical for steerable space-borne sensors with fields of view less than one degree, tasked to observe starlight passing near the Earth's surface. Ray tracing in the U.S. Standard Atmosphere, 1976 including H2O effects, is used to determine relations between the refracted tangent height, the apparent tangent height resulting from observation at the sensor, and the angle through which the detected rays have deviated. Analytic fits of the ray deviation as a function of apparent tangent height allows quick determination of corrections needed for a space-borne sensor. Using those results that apply in the plane of incidence and using the necessary coordinate rotations, alterations in the star's apparent right ascension and declination are evaluated to improve the aim. Examples illustrate that alterations can be larger than one degree, with effects lasting up to a few minutes.

Vittitoe, C. N.; Schmidt, R. L.

1997-03-01

388

IRECIN Nano-satellite communication system and ground segment  

Microsoft Academic Search

On board resources necessary to perform the mission tasks are very limited in nano-satellites. This paper proposes a real-time multi-processing system for the communication system between ground segment and IRECIN nano-satellite.The first microprocessor is devoted to interface to the rice-transceiver subsystem decoding packet information and the second one is in charge to communicate with the other subsystems through I2C bus.

M. Ferrante; M. Povia; L. Di Ciolo; A. Ortenzi; M. Petrozzi

2005-01-01

389

Multiple satellite observations of leakage of particles from the magnetosphere  

NASA Astrophysics Data System (ADS)

The properties of four potential sources for energetic ions and electrons in the magnetosheath are considered: upstream Fermi acceleration and shock drift acceleration of incident solar wind particles at the bow shock, acceleration of magnetosheath ions through merging at the magnetopause, and escape from the magnetosphere. A review of previous observations suggests that the magnetosphere is the dominant source of the magnetosheath energetic particle population. Despite recent work to the contrary, it is questioned whether energetic particle observations alone provide any evidence for merging at the dayside magnetopause.

Sibeck, D. G.; McEntire, R. W.

390

New Horizons/LEISA Observations of the Icy Galilean Satellites  

NASA Astrophysics Data System (ADS)

We present compositional characterization of the surfaces of Europa, Ganymede, and Callisto using data from the Linear Etalon Imaging Spectral Array (LEISA) on the New Horizons spececraft, which flew through the Jupiter system in early 2007.

Emery, J. P.; Grundy, W. M.; Lunsford, A.; Hibbitts, C. A.; Phillips, C. B.; Mastrapa, R. M. E.

2011-03-01

391

622 Mbps High-speed satellite communication system for WINDS  

NASA Astrophysics Data System (ADS)

WINDS is the experimental communications satellite currently under joint development by Japanese Aerospace Exploration Agency (JAXA) and the National Institute of Information and Communications Technology (NICT). The high-speed satellite communication system is very effective for quick deployment of high-speed networks economically. The WINDS will realize ultra high-speed networking and demonstrate operability of satellite communication systems in high-speed internet. NICT is now developing high-speed satellite communication system for WINDS. High-speed TDMA burst modem with high performance TPC error correction is underdevelopment. Up to the DAC on the transmitter and from the ADC on the receiver, all modem functions are performed in the digital processing technology. Burst modem has been designed for a user data rate up to 1244 Mbps. NICT is developing the digital terminal as a user interface and a network controller for this earth station. High compatibility with the Internet will be provided.

Ogawa, Yasuo; Hashimoto, Yukio; Yoshimura, Naoko; Suzuki, Ryutaro; Gedney, Richard T.; Dollard, Mike

2006-07-01

392

Determination of source thunderstorms for VHF emissions observed by the FORTE satellite  

NASA Astrophysics Data System (ADS)

This paper explains a method of locating groups of satellite-observed VHF signals from lightning that emanate from isolated storm regions. LF/VLF signals recorded and located by the National Lightning Detection Network (NLDN) are often accompanied by broadband VHF emissions of sufficient intensity to trigger satellite-based RF receivers. It has previously been shown that events recorded by the FORTE satellite and the NLDN, which have occurrence-time differences of 0.3 ms or less, can be assumed to originate at the same approximate geolocation with 97.5% reliability. For such event pairs, the VHF events recorded by FORTE were assigned the NLDN locations. We use graphical analysis to identify groups of satellite data that can be assumed to originate from the same storms as the located events. To accomplish this, a value of total electron content (TEC) is derived from the frequency dispersion of each VHF signal recorded by FORTE. Scatterplots of TEC versus time often reveal curved clusters of satellite data. The variation of TEC with satellite elevation angle, and time, is consistent with a model in which the length of a signal's required propagation path through the ionosphere changes with satellite and storm position. We use the values of TEC for the located satellite data, a simple model of the ionosphere, and NLDN data to help us identify TEC clusters that can be assumed to originate from relatively compact, and unambiguous, geolocations. For the time period of April through September of 1998 we geolocate 65 groups of satellite data records. A total of 6131 satellite data records, which were not previously located, have been assigned the median NLDN coordinates of their corresponding storm.

Tierney, Heidi E.; Jacobson, Abram R.; Beasley, William H.; Argo, Paul E.

393

Retrieval of CFC concentrations from thermal infrared spectrum observed by Greenhouse gases Observation SATellite (GOSAT)  

NASA Astrophysics Data System (ADS)

Chemical substances emitted by the anthropological activities cause serious environmental problems. Among them, CFCs have been depleting ozone layer in the stratosphere. Also, it is reported that their radiative forcing is 0.268 W/m2 and they could largely account for global warming. To mitigate these problems, it is important to estimate their distribution and amount globally with good accuracy. Though on site measurements provide considerably precise data, the observation sites are quite limited. In contrast, results retrieved from data obtained by remote sensing may contain more errors, but its wide spatial coverage is great advantage to monitor atmosphere globally and continuously for long term. The purpose of this study is to retrieve concentrations of CFC-11 and CFC-12, and replacements for CFCs from thermal infrared spectrum data obtained by Greenhouse gases Observation SATellite (GOSAT). We use spectrum data taken from its main sensor, Fourier transform spectrometer TANSO-FTS, particularly its band 4 (5.5 - 14.3?m). The sub-sensor called TANSO-CAI is used for cloud screening. To calculate simulated spectrum using a radiative transfer model, LBLRTM, the meteorological reanalysis data including atmospheric information at each point such as surface temperature and atmospheric composition are prepared. As the first step, we focus on CFC-11 and CFC-12 which have strong absorption band near 850 cm-1 and 920 cm-1 respectably. For retrieving the gases, the baselines of the observed and calculated spectrum need to be matched. However, it is not always true due to the uncertainty of information in the reanalysis data. To match baselines, we first set the constant emissivity and estimate the surface temperature. Even after the procedure, spectral residue still remained particularly on the peaks of water vapor absorption lines. We will retrieve more precise surface temperature and the amount of water vapor from observed each spectrum so that we could get better a priori for gas retrieval. We will also discuss how accurately CFC-11 and CFC-12 can be retrieved by GOSAT data.

Inagoya, A.; Imasu, R.; Hayashi, Y.

2011-12-01

394

C\\/NOFS satellite observations of equatorial ionospheric plasma structures supported by multiple ground-based diagnostics in October 2008  

Microsoft Academic Search

In early October 2008, the C\\/NOFS satellite orbited near the magnetic equator at its perigee altitude of ˜400 km at dusk in the Peruvian sector. This provided an ideal opportunity for a comparison, under the current very low solar flux condition, of equatorial ionospheric disturbances observed with the Communication\\/Navigation Outage Forecasting System (C\\/NOFS) in situ measurements and ground-based observations available

M. Nishioka; Su. Basu; C. E. Valladares; R. E. Sheehan; P. A. Roddy; K. M. Groves

2011-01-01

395

FAST satellite observations of large-amplitude solitary structures  

Microsoft Academic Search

We report observations of ``fast solitary waves'' that are ubiquitous in downward current regions of the mid-altitude auroral zone. The single-period structures have large amplitudes (up to 2.5 V\\/m), travel much faster than the ion acoustic speed, carry substantial potentials (up to ~100 Volts), and are associated with strong modulations of energetic electron fluxes. The amplitude and speed of the

R. E. Ergun; C. W. Carlson; J. P. McFadden; F. S. Mozer; G. T. Delory; W. Peria; C. C. Chaston; M. Temerin; I. Roth; L. Muschietti; R. Elphic; R. Strangeway; R. Pfaff; C. A. Cattell; D. Klumpar; E. Shelley; W. Peterson; E. Moebius; L. Kistler

1998-01-01

396

Satellite microwave observations of the Utah Great Salt Lake Desert  

Microsoft Academic Search

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. This phenomenon was observed by Skylab's S-194 radiometer operating at 1.4 GHz, S-193 RADSCAT (Radiometer-Scatterometer) operating at 13.9 GHz, and the Nimbus 5

Fawwaz T. Ulaby; Louis F. Dellwig; Thomas Schmugge

1975-01-01

397

Scheduling satellite-based SAR acquisition for sequential assimilation of water level observations into flood modelling  

NASA Astrophysics Data System (ADS)

We assimilate satellite SAR-derived water level with an ensemble filter (ETKF).We evaluate the forecast sensitivity to satellite first visit and revisit time.Online correction of imposed bias clearly improves the 2D flood model/DA forecast.Imagery obtained early in the flood has a large influence on the forecast.Revisit interval is most influential for early observations.

Garcķa-Pintado, Javier; Neal, Jeff C.; Mason, David C.; Dance, Sarah L.; Bates, Paul D.

2013-07-01

398

An analysis of the 1985 observations of mutual phenomena of the Galilean satellites  

SciTech Connect

This paper derives midtimes and relative satellite positions from nearly 200 light curves of mutual eclipses and occultations of the Galilean satellites that occurred in 1985. It is shown that, at least for observations of the highest quality, the standard errors on the midtimes are smaller than 1 s and close to 0.01 arcsec on the positional offsets in right ascension and declination. 12 refs.

Franklin, F.A.; Africano, J.; Allen, W.; Aksnes, K.; Birch, P. (Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States) Kitt Peak National Observatory, Tucson, AZ (United States) Adams Lane Observatory, Blenheim (New Zealand) Cerro Tololo Inter-American Observatory, La Serena (Chile) Lowell Observatory, Flagstaff, AZ (United States) Perth Observatory (Australia))

1991-08-01

399

Systematic and random errors between collocated satellite ice water path observations  

NASA Astrophysics Data System (ADS)

remains large disagreement between ice-water path (IWP) in observational data sets, largely because the sensors observe different parts of the ice particle size distribution. A detailed comparison of retrieved IWP from satellite observations in the Tropics (±30° latitude) in 2007 was made using collocated measurements. The radio detection and ranging(radar)/light detection and ranging (lidar) (DARDAR) IWP data set, based on combined radar/lidar measurements, is used as a reference because it provides arguably the best estimate of the total column IWP. For each data set, usable IWP dynamic ranges are inferred from this comparison. IWP retrievals based on solar reflectance measurements, in the moderate resolution imaging spectroradiometer (MODIS), advanced very high resolution radiometer-based Climate Monitoring Satellite Applications Facility (CMSAF), and Pathfinder Atmospheres-Extended (PATMOS-x) datasets, were found to be correlated with DARDAR over a large IWP range (~20-7000 g m-2). The random errors of the collocated data sets have a close to lognormal distribution, and the combined random error of MODIS and DARDAR is less than a factor of 2, which also sets the upper limit for MODIS alone. In the same way, the upper limit for the random error of all considered data sets is determined. Data sets based on passive microwave measurements, microwave surface and precipitation products system (MSPPS), microwave integrated retrieval system (MiRS), and collocated microwave only (CMO), are largely correlated with DARDAR for IWP values larger than approximately 700 g m-2. The combined uncertainty between these data sets and DARDAR in this range is slightly less MODIS-DARDAR, but the systematic bias is nearly an order of magnitude.

Eliasson, S.; Holl, G.; Buehler, S. A.; Kuhn, T.; Stengel, M.; Iturbide-Sanchez, F.; Johnston, M.

2013-03-01

400

47 CFR 25.159 - Limits on pending applications and unbuilt satellite systems.  

Code of Federal Regulations, 2011 CFR

...Limits on pending applications and unbuilt satellite systems. 25.159 Section 25.159...CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Applications and Licenses...Limits on pending applications and unbuilt satellite systems. (a)...

2011-10-01

401

47 CFR 25.159 - Limits on pending applications and unbuilt satellite systems.  

Code of Federal Regulations, 2012 CFR

...Limits on pending applications and unbuilt satellite systems. 25.159 Section 25.159...CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Applications and Licenses...Limits on pending applications and unbuilt satellite systems. (a)...

2012-10-01

402

A digital transmission system for global maritime satellite communications  

Microsoft Academic Search

A digital transmission system for global maritime satellite communications has been designed, and experimental communications equipment has been developed, taking account of its potential application to the Inmarsat system where analog modulation is currently used for telephone signal transmission. This paper discusses possible digital technologies to realize an efficient digital transmission system, and presents a concept for the designed system.

Y. Hirata; Y. Yasuda; H. Okinaka; K. Kashiki

1984-01-01

403

Satellite masses in the Uranus and Neptune systems  

SciTech Connect

Satellite masses are derivation with emphasis on implications for bulk densities and albedos is reviewed. In the Uranian system the inner satellites have lower densities and/or higher albedos than the outer ones. However, uncertainties are great enough that all five satellites may have nearly equal densities. In such a case the albedo would decrease with semimajor axis. A more severe constraint is placed on Miranda's mass, and hence on its density and albedo. The recent radiometric value for Triton's diameter, combined with mass determinations, yields a density greater than 4 gm/cm3.

Greenberg, R.

1984-10-01

404

The Tracking and Data Relay Satellite System - The next decade  

NASA Astrophysics Data System (ADS)

As currently envisioned, NASA's Tracking and Data Relay Satellite System (TDRSS) will support the tracking and telecommunications requirements of LEO user satellites until the late 1990s, when existing TDRSS satellites will reach the end of their service lives. Spacecraft replacement is conceived as inseparable from network expansion for the accommodation of user population growth and the improvement of user services. The objective is to achieve a cost-effective/low-risk transition from TDRSS to Advanced TDRSS without interruption of user support. Attention is presently given to Advanced TDRSS architectural candidates studied and the choices which have emerged through technical tradeoff assessments.

Guion, William S.; Chang, Robert W.

1990-09-01

405

End-to-end simulator for Global Navigation Satellite System Reflectometry space mission  

Microsoft Academic Search

This paper presents an end-to-end simulator to assess the performances of Global Navigation Satellite System Reflectometry (GNSS-R) space missions for altimetry or sea state determination. The presented simulator is capable of simulating the GNSS-R observation scenario including the states of the transmitting and receiving satellites, the full instrument modeling, and scattering physical modeling based on an actual geophysical database. It

Hyuk Park; Juan Fernando Marchan-Hernandez; Nereida Rodriguez-Alvarez; Enric Valencia; Isaac Ramos-Perez; Xavier Bosch-Lluis; Adriano Camps

2010-01-01

406

NPR and intermodulation in mobile satellite systems  

NASA Astrophysics Data System (ADS)

Various topics related to Noise Power Ratio (NPR) and intermodulation products are reviewed in connection with the design of a spacecraft payload. Findings of some of the basic studies carried out at Telesat Canada in connection with the mobile satellite program are presented. Effects of voice activation and bandwidth spreading on the service performance in terms of carrier-to-intermodulation noise ratio are studied. Power amplifier linearization and its impact on NPR, intermodulation products and dc to RF conversion efficiency are also discussed. Software simulation and laboratory results are compared. The reduction of the impact of intermodulation noise on the wanted signals using different payload configurations is considered.

Amlekar, Pat

407

A common mass scaling for satellite systems of gaseous planets.  

PubMed

The Solar System's outer planets that contain hydrogen gas all host systems of multiple moons, which notably each contain a similar fraction of their respective planet's mass (approximately 10(-4)). This mass fraction is two to three orders of magnitude smaller than that of the largest satellites of the solid planets (such as the Earth's Moon), and its common value for gas planets has been puzzling. Here we model satellite growth and loss as a forming giant planet accumulates gas and rock-ice solids from solar orbit. We find that the mass fraction of its satellite system is regulated to approximately 10(-4) by a balance of two competing processes: the supply of inflowing material to the satellites, and satellite loss through orbital decay driven by the gas. We show that the overall properties of the satellite systems of Jupiter, Saturn and Uranus arise naturally, and suggest that similar processes could limit the largest moons of extrasolar Jupiter-mass planets to Moon-to-Mars size. PMID:16778883

Canup, Robin M; Ward, William R

2006-06-15

408

Satellite thermal observation of oil slicks on the Persian Gulf  

SciTech Connect

A possibility of oil slicks detection is discussed for oil slicks spread in the vicinity of the Nowruz oil fields in the Persian Gulf since March 1983 to July 1983 with considering an apparent thermal inertia. The apparent thermal was computed from continuous observations of sea surface temperature and albedo by the Advanced Very High Resolution Radiometer (AVHRR) on the NOAA-7 through day and night with 12 h interval. The apparent thermal inertia is defined as a function of a temperature difference between the daytime and the nighttime and an apparent albedo. Sea surface temperature used for computing the apparent thermal inertia was obtained through an atmospheric correction with an empirical equation which uses an energy difference between two thermal channels of the AVHRR. Although there was an ambiguity on a selection of same object on water body, the computed apparent thermal inertia showed the possibility of oil slicks detection from sea water. 17 references.

Asanuma, I.; Muneyama, K.; Sasaki, Y.; Iisaka, J.; Yasuda, Y.

1986-04-01

409

System-dependent center-of-mass correction for spherical geodetic satellites  

NASA Astrophysics Data System (ADS)

The temporal spread of optical pulse signals due to reflection from multiple onboard reflectors is now a critical problem in satellite laser ranging. The full rate residual profile of single-photon laser ranging can be used to model the response function of geodetic satellites, resolving the uncertainty of far-field diffraction. We constructed the response function model for three types of laser ranging targets already in Earth orbit, the LAGEOS, AJISAI, and ETALON satellites. The center-of-mass correction depends on the ranging system and observation policy at terrestrial stations and varies about 1 cm for LAGEOS and 5 cm for AJISAI and ETALON.

Otsubo, Toshimichi; Appleby, Graham M.

2003-04-01

410

Workshop on Satellite and In situ Observations for Climate Prediction  

SciTech Connect

Participants in this workshop, which convened in Venice, Italy, 6-8 May 1993, met to consider the current state of climate monitoring programs and instrumentation for the purpose of climatological prediction on short-term (seasonal to interannual) timescales. Data quality and coverage requirements for definition of oceanographic heat and momentum fluxes, scales of inter- and intra-annual variability, and land-ocean-atmosphere exchange processes were examined. Advantages and disadvantages of earth-based and spaceborne monitoring systems were considered, as were the structures for future monitoring networks, research programs, and modeling studies.

Acker, J.G.; Busalacchi, A. [Hughes STX Corp., Lanham, MD (United States)]|[NASA, Goddard Space Flight Center, Greenbelt, MD (United States)

1995-02-01

411

Solar system planets observed with Suzaku  

Microsoft Academic Search

Recent results of solar system planets observed with the Japanese X-ray astronomy satellite Suzaku are reviewed. Thanks to the low instrumental background and good energy resolution, X-ray CCDs onboard Suzaku are one of the best probes to study diffuse X-ray emission. An overview of the Suzaku data of Jupiter and Earth is presented, along with preliminary results of Mars. Firstly,

Yuichiro Ezoe; Kumi Ishikawa; Takaya Ohashi; Noriko Y. Yamasaki; Kazuhisa Mitsuda; Ryuichi Fujimoto; Yoshizumi Miyoshi; Naoki Terada; Yasunobu Uchiyama; Yoshifumi Futaana

2011-01-01

412

Different greenhouse gases as a possible origin of the different behaviour of TIR anomalies observed from satellite in seismogenic areas  

Microsoft Academic Search

Many studies have been suggesting for decades a relation between Thermal Infrared (TIR) anomalies, observed from satellite, and seismic activity. In particular, the Robust Satellite Technique (RST) for the first time provided a statistics-based definition of \\

C. Aliano; R. Corrado; C. Filizzola; V. Lanorte; M. Lisi; R. Paciello; N. Pergola; V. Tramutoli; T. Tsamalashvili

2009-01-01

413

Formation of the Jovian and Saturnian Satellite Systems (Invited)  

NASA Astrophysics Data System (ADS)

The Jovian and Saturnian regular satellites likely formed within circumplanetary disks of gas (primarily hydrogen) and solids (rock and ice). Here I will focus on a model [1-3] in which gas giant satellites form within disks produced by the final stages of gas accretion by the planets [4]. Small solids carried into the disk by gas inflowing from solar orbit provide the raw material for accreting satellites. Each satellite can grow no larger than a critical mass, at which point its orbit spirals into the planet due to density wave interactions with the gas disk (Type I migration). This critical mass is comparable to those of the Galilean satellites and Titan. Multiple generations of satellites having this critical mass are predicted to form and be lost to collision with the planet. The final surviving satellites are those that form as gas inflow to the planet ends, the circumplanetary gas disk dissipates, and the satellite orbits stabilize. In this model, all the gas giant satellites accrete slowly, at a rate governed by the rate of delivery of solid material to the disk. This implies that the final large satellites form on a timescale comparable to the solar nebula dissipation timescale, which was likely ~ 10^6 yr. Such a slow accretion can allow large, outer ice-rock satellites to remain undifferentiated or to undergo only partial differentiation as they form [5-6]. The model produces final satellite systems having either several large satellites (like the Galilean satellites) or a single large satellite (like Saturn’s Titan) [2,7]. A Saturn-like system is produced when large, Titan-sized satellites orbiting interior to Titan spiral into the planet and are lost as gas inflow ends, leaving Titan as the sole large survivor [2]. As the final large satellite lost from the Saturn system spirals within the Roche limit, planetary tides preferentially strip material from its outer layers, producing a massive ice ring [8]. Such conditions offer a new explanation for the origin of Saturn’s main rings and the Saturnian ice-rich satellites interior to and including Tethys [8]. [1] Canup, R.M. & W.R. Ward, AJ, 124, 3404 (2002); [2] Canup, R.M. & W.R. Ward, Nature 441, 834 (2006). [3] Ward, W.R. & R.M. Canup, In Europa, Univ. Az. Press (2009). [4] Ward, W.R. & R.M. Canup, AJ, in press (2010); [5] Barr, A.C. & R.M. Canup, Icarus 198, 163 (2008); [6] Barr, A.C., Citron, R. & R.M. Canup, Icarus, in press (2010); [7] Sasaki, T., G.R. Stewart, & S. Ida. ApJ, 714, 1052 (2010). [8] Canup, R.M., Nature, submitted (2010). Support from NASA’s OPR and PGG programs is gratefully acknowledged.

Canup, R. M.

2010-12-01

414

Virtual satellite observations of plasmoids generated by fast reconnection in the geomagnetic tail  

NASA Astrophysics Data System (ADS)

The present paper studies fundamental features of plasmoid propagation by virtual satellite observations in the simulation box. The plasmoid domain is divided into the plasmoid reconnection region P, where magnetized plasmas with reconnected field lines, heated by dissipation mechanisms of fast reconnection, are accumulated, and the plasmoid core region C, where magnetized plasmas with sheared field lines, initially embedded in the current sheet, is adiabatically compressed. When the virtual satellite is located in a position through which the plasmoid core region passes, it detects distinct changes in quantities at the interface between the regions P and C, where the north-south field component Bz has the bipolar profile and the sheared field component By has the peak value. The observed magnetic field profile is, both quantitatively and qualitatively, in good agreement with the standard one detected by actual satellite observations, although when the satellite location is very close to the X neutral line, where reconnection occurs, the Bz field profile becomes dipolarization-like rather than bipolar. If the satellite detects only the plasmoid region P outside region C, the standard magnetic field profile becomes obscure even if notable plasmoid signatures, such as enhanced plasma temperature and plasma flow, are observed. Unlike the traditional flux rope model based on multiple reconnections, it is demonstrated that the standard magnetic field profile, observed for plasmoids propagating in the geomagnetic tail, is the direct outcome of the single fast reconnection evolution.

Ugai, M.

2011-08-01

415

Satellite Power System (SPS) concept definition study (exhibit C)  

Microsoft Academic Search

The major outputs of the study are the constructability studies which resulted in the definition of the concepts for satellite, rectenna, and satellite construction base construction. Transportation analyses resulted in definition of heavy-lift launch vehicle, electric orbit transfer vehicle, personnel orbit transfer vehicle, and intra-orbit transfer vehicle as well as overall operations related to transportation systems. The experiment\\/verification program definition

G. M. Haley

1979-01-01

416

Observations of Planetary and Satellite Atmospheres and Surfaces  

NASA Astrophysics Data System (ADS)

The full opening of the submillimeter range with the operation of Herschel is expected to prove very useful for the study of planetary atmospheres and surfaces. Areas of anticipated progress include: (i) the origin and evolution of the Giant Planets, from improved determinations of the abundance of deuterium and helium (ii) the origin of the external source of oxygen in the Giant Planets and Titan (iii) several compositional and physical aspects of planetary atmospheres, especially the issue of vertical transport in Uranus and Neptune and the martian photochemistry and (iv) the thermophysical and compositional properties of planetary surfaces, including the size distribution of transneptunian objects. The high sensitivity of all instruments and the diversity of their spectral resolutions is well suited to the diversity of size and atmospheric pressure within the bodies of the Solar System.

Lellouch, E.

2001-07-01

417

Estimation of gross primary production capacity from global satellite observations  

NASA Astrophysics Data System (ADS)

To estimate gross primary production (GPP), the process of photosynthesis was considered as two separate phases: capacity and reduction. The reduction phase is influenced by environmental conditions such as soil moisture and weather conditions such as vapor pressure differences. For a particular leaf, photosynthetic capacity mainly depends on the amount of chlorophyll and the RuBisCO enzyme. The chlorophyll content can be estimated by the color of the leaf, and leaf color can be detected by optical sensors. We used the chlorophyll content of leaves to estimate the level of GPP. A previously developed framework for GPP capacity estimation employs a chlorophyll index. The index is based on the linear relationship between the chlorophyll content of a leaf and the maximum photosynthesis at PAR =2000 (?molm -2s-1) on a light-response curve under low stress conditions. As a first step, this study examined the global distribution of the index and found that regions with high chlorophyll index values in winter corresponde