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1

On the development of earth observation satellite systems  

NASA Technical Reports Server (NTRS)

Subsequent to the launching of the first LANDSAT by NASA, Japan has recognized the importance of data from earth observation satellites, has conducted studies, and is preparing to develop an independent system. The first ocean observation satellite will be launched in 1983, the second in 1985. The first land observation satellite is scheduled to be launched in 1987 and by 1990 Japan intends to have both land and ocean observation systems in regular operation. The association reception and data processing systems are being developed.

1977-01-01

2

A crustal movement observation system using quasi-zenith satellites  

Microsoft Academic Search

The proposal for an observation system of crustal movement using two quasi-zenith satellites is presented. In the system, two quasi-zenith satellites have a retro-directive antenna on board and an earth station have two beam antenna in the direction to the two quasi-zenith satellites. The crustal movement at the area of the earth stations is obtained by interfering with two signals

Shinji Kuroda; Tadashi Oshima; Shuji Urasaki

2010-01-01

3

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

4

Satellite Observation Systems for Polar Climate Change Studies  

NASA Technical Reports Server (NTRS)

The key observational tools for detecting large scale changes of various parameters in the polar regions have been satellite sensors. The sensors include passive and active satellite systems in the visible, infrared and microwave frequencies. The monitoring started with Tiros and Nimbus research satellites series in the 1970s but during the period, not much data was stored digitally because of limitations and cost of the needed storage systems. Continuous global data came about starting with the launch of ocean color, passive microwave, and thermal infrared sensors on board Nimbus-7 and Synthetic Aperture Radar, Radar Altimeter and Scatterometer on board SeaSat satellite both launched in 1978. The Nimbus-7 lasted longer than expected and provided about 9 years of useful data while SeaSat quit working after 3 months but provided very useful data that became the baseline for follow-up systems with similar capabilities. Over the years, many new sensors were launched, some from Japan Aeronautics and Space Agency (JAXA), some from the European Space Agency (ESA) and more recently, from RuSSia, China, Korea, Canada and India. For polar studies, among the most useful sensors has been the passive microwave sensor which provides day/night and almost all weather observation of the surface. The sensor provide sea surface temperature, precipitation, wind, water vapor and sea ice concentration data that have been very useful in monitoring the climate of the region. More than 30 years of such data are now available, starting with the Scanning Multichannel Microwave Radiometer (SMMR) on board the Nimbus-7, the Special Scanning Microwave/Imager (SSM/I) on board a Defense Meteorological Satellite Program (DMSP) and the Advanced Microwave Scanning Radiometer on board the EOS/ Aqua satellite. The techniques that have been developed to derive geophysical parameters from data provided by these and other sensors and associated instrumental and algorithm errors and validation techniques will be discussed. An important issue is the organization and storage of hundreds of terabytes of data collected by even just a few of these satellite sensors. Advances in mass storage and computer technology have made it possible to overcome many of the collection and archival problems and the availability of comprehensive satellite data sets put together by NASA's Earth Observing System project will be discussed.

Comiso, Josefino C.

2012-01-01

5

Satellite Altimetry for a Global Ocean Observing System  

NASA Technical Reports Server (NTRS)

Space-age technologies have made satellite remote sensing a powerful new tool to study the Earth on a global scale. However, the opacity of the ocean to electromagnetic sensing has limited spaceborne measurements to the properties of the surface layer of the ocean (such as sea surface temperature and color). The radar altimetric measurement of the height of the sea surface relative to the geoid, the dynamic topography of the ocean, is a very useful quantity for studying the circulation of the ocean. The ability of measuring dynamic topography from space makes satellite altimetry a uniquely useful remote sensing technique because dynamic topography reflects oceanic processes not only at the surface but at depths as well. A simple analysis shows that a one centimeter tilt in the dynamic topography is associated with a mass transport of 1-7 Sv (1Sv= 1 million tons per second) in the open ocean depending on the vertical distribution of current velocity. Such a magnitude is an appreciable fraction of the transport of the Florida Current (circa 30 Sv), for instance. TOPEX/POSEIDON has demonstrated the capability of measuring the time variation of sea level with accuracy approaching to 2 cm when the data are averaged over boxes with several hundred kilometers on each side. The data set has been used for studying ocean circulation phenomena with a wide range of scales, ranging from fast-changing barotropic variability to seasonal and interannual variability such as El Nino and La Nina. The long record of precise measurement of global sea level has also showed great promise for monitoring the variation of mean sea level, an effective indicator of global climate change. Continuation of satellite altimetry missions with capability matching or better than that of TOPEX/POSEIDON should be included as a key component of a Global Ocean Observing System. NASA and CNES have committed to continuing the measurement of TOPEX/POSEIDON with a series of follow-on missions called Jason. The first of the series, Jason-1, is scheduled for launch in May, 2000. Such a series of missions will provide a key data stream for both research and practical applications and benefit the objectives of global programs such as CLIVAR and GODAE.

Fu, Lee-Lueng

2000-01-01

6

Rule-based system architecting of Earth observation satellite systems  

E-print Network

System architecting is concerned with exploring the tradespace of early, high-level, system design decisions with a holistic, value-centric view. In the last few years, several tools and methods have been developed to ...

Selva Valero, Daniel

2012-01-01

7

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

E-print Network

A satellite ocean color observation operator system for eutrophication assessment in coastal waters: Satellite ocean color Observation operator Eutrophication Remote sensing Radiative transfer modeling- nounced for coastal waters and waters optically classified as Case-II. The early success of using

Fontana, Clément

8

Tropospheric Emission Spectrometer (TES) for the Earth Observing System (EOS) CHEM Satellite  

NASA Technical Reports Server (NTRS)

The Tropospheric Emission Spectrometer (TES) is an imaging infrared Fourier transform spectrometer scheduled to be launched into polar sun-synchronous orbit on the Earth Observing System (EOS) CHEM satellite in December 2002.

Beer, R.; Glavich, T.; Rider, D.

2000-01-01

9

How Satellite Observations Impact NWP  

NSDL National Science Digital Library

Satellite observations have a huge impact on numerical weather prediction (NWP) model analyses and forecasts, with sounding data from polar orbiting and GPS-radio occultation satellites reducing model forecast error by almost half. All of this despite the fact that NWP models only assimilate 5% of all satellite observations! This lesson discusses the use of satellite observations in NWP and how model limitations prevent more of the data from being assimilated. The lesson begins by briefly describing the history of satellite observations in NWP and their impact on NWP model forecast skill. The next part provides background information about the types of environmental satellites that provide input to NWP, the satellite observations that are assimilated, the major components of NWP models, and how they forecast atmospheric behavior. This sets the stage for the main part of the lesson, which examines how observations from new satellite instruments are vetted for inclusion in data assimilation systems and how observations deemed acceptable are actually assimilated. The final part describes current challenges to making optimal use of satellite observations in NWP and advances that are expected to address these challenges and improve model forecasts.

Comet

2014-03-12

10

System architecting of a campaign of earth observing satellites  

E-print Network

Given the current level of concern over anthropogenic climate change, and the ongoing debate worldwide regarding what action should be taken to reduce and reverse future warming, the ability to collect data on Earth system ...

Colson, Justin M

2008-01-01

11

Interferometric Observations of Geosynchronous Satellites  

E-print Network

In recent years, a large number of geosynchronous satellites are being planned to provide augmentation services for enhancing the precision to global positioning systems, e.g., GPS, in applications such as aircraft landing. In this paper, we present a scheme for co-locating passive satellite observational facilities with a radio astronomy facility to open a new possibility of providing valuable data for radio astronomical imaging, ionospheric studies and satellite orbit estimation.

Subrahmanya, C R; Somashekar, R

2011-01-01

12

VLBI Observations of Geostationary Satellites  

NASA Astrophysics Data System (ADS)

For a consistent realization of a Global Geodetic Observing System (GGOS), a proper tie between the individual global reference systems used in the analysis of space-geodetic observations is a prerequisite. For instance, the link between the terrestrial, the celestial and the dynamic reference system of artificial Earth orbiters may be realized by Very Long O Baseline Interferometry (VLBI) observations of one or several satellites. In the preparation phase for a dedicated satellite mission, one option to realize this is using a geostationary (GEO) satellite emitting a radio signal in X-Band and/or S-Band and, thus, imitating a quasar. In this way, the GEO satellite can be observed by VLBI together with nearby quasars and the GEO orbit can, thus, be determined in a celestial reference frame. If the GEO satellite is, e.g., also equipped with a GNSS-type transmitter, a further tie between GNSS and VLBI may be realized. In this paper, a concept for the generation of a radio signal is shown. Furthermore, simulation studies for estimating the GEO position are presented with a GEO satellite included in the VLBI schedule. VLBI group delay observations are then simulated for the quasars as well as for the GEO satellite. The analysis of the simulated observations shows that constant orbit changes are adequately absorbed by estimated orbit parameters. Furthermore, the post-fit residuals are comparable to those from real VLBI sessions.

Artz, T.; Nothnagel, A.; La Porta, L.

2013-08-01

13

Future intelligent Earth observing satellites  

Microsoft Academic Search

This paper presents a simulated architecture of an envisioned future intelligent Earth observing satellite system (FIEOS). The proposed system is a space-based architecture for dynamic and comprehensive on-board integration of Earth observing sensors, data processors and communication systems. It is intended to enable simultaneous, global measurements and timely analyses of Earth's environment for a variety of users. This paper also

Guoqing Zhou

2003-01-01

14

Candidate configuration trade study, Stellar-inertial Measurement Systems (SIMS) for an Earth Observation Satellite (EOS)  

NASA Technical Reports Server (NTRS)

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: (1) structure-mounted gyros with structure-mounted star mapper, (2) structure-mounted gyros with gimbaled star tracker, and (3) gimbaled gyros with structure-mounted star mapper. The purpose of the study is to facilitate the decisions pertaining to gimbaled versus structure-mounted gyros and star sensors, and combinations of systems suitable for the EOS satellite.

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

1972-01-01

15

Observing system simulation experiments to assess the potential impact of proposed satellite instruments on hurricane prediction  

NASA Astrophysics Data System (ADS)

Observing System Simulation Experiments (OSSEs) are an important tool for evaluating the potential impact of proposed new observing systems, as well as for evaluating trade-offs in observing system design, and in developing and assessing improved methodology for assimilating new observations. Extensive OSSEs have been conducted at NASA/ GSFC and NOAA/AOML over the last three decades. These OSSEs determined correctly the quantitative potential for several proposed satellite observing systems to improve weather analysis and prediction prior to their launch, evaluated trade-offs in orbits, coverage and accuracy for space-based wind lidars, and were used in the development of the methodology that led to the first beneficial impacts of satellite surface winds on numerical weather prediction. In this paper, we summarize early applications of global OSSEs to hurricane track forecasting and new experiments using both global and regional models. These experiments are aimed at determining (1) the potential impact of unmanned aerial systems, (2) the relative impact of alternative concepts for space-based lidar winds, and (3) the relative impact of alternative concepts for polar and geostationary hyperspectral sounders.

Atlas, Robert; Pagano, Thomas S.

2014-09-01

16

The National Polar-orbiting Operational Environmental Satellite System future US operational Earth observation system  

Microsoft Academic Search

Over the last nine years the Integrated Program Office has been developing the National Polar-orbiting Operational Environmental Satellite System (NPOESS). NPOESS spacecraft will be launched into three orbital planes beginning later this decade to provide significantly improved operational capabilities and benefits to satisfy the critical civil and national security requirements for space-based, remotely sensed environmental data.

John D. Cunningham; Frederick L. Ricker; C. S. Nelson

2003-01-01

17

Nonlinear Observer with Time-Varying Gains for Inertial Navigation Aided by Satellite Reference Systems in Dynamic Positioning  

E-print Network

Nonlinear Observer with Time-Varying Gains for Inertial Navigation Aided by Satellite Reference sensors. I. INTRODUCTION A strapdown inertial navigation system (INS) is mounted on a navigating object-- The measurement quality of Global Navigation Satellites Systems (GNSS) during marine operations will vary over

Johansen, Tor Arne

18

Ionospheric Simulation System for Satellite Observations and Global Assimilative Modeling Experiments (ISOGAME)  

NASA Technical Reports Server (NTRS)

ISOGAME is designed and developed to assess quantitatively the impact of new observation systems on the capability of imaging and modeling the ionosphere. With ISOGAME, one can perform observation system simulation experiments (OSSEs). A typical OSSE using ISOGAME would involve: (1) simulating various ionospheric conditions on global scales; (2) simulating ionospheric measurements made from a constellation of low-Earth-orbiters (LEOs), particularly Global Navigation Satellite System (GNSS) radio occultation data, and from ground-based global GNSS networks; (3) conducting ionospheric data assimilation experiments with the Global Assimilative Ionospheric Model (GAIM); and (4) analyzing modeling results with visualization tools. ISOGAME can provide quantitative assessment of the accuracy of assimilative modeling with the interested observation system. Other observation systems besides those based on GNSS are also possible to analyze. The system is composed of a suite of software that combines the GAIM, including a 4D first-principles ionospheric model and data assimilation modules, an Internal Reference Ionosphere (IRI) model that has been developed by international ionospheric research communities, observation simulator, visualization software, and orbit design, simulation, and optimization software. The core GAIM model used in ISOGAME is based on the GAIM++ code (written in C++) that includes a new high-fidelity geomagnetic field representation (multi-dipole). New visualization tools and analysis algorithms for the OSSEs are now part of ISOGAME.

Pi, Xiaoqing; Mannucci, Anthony J.; Verkhoglyadova, Olga P.; Stephens, Philip; Wilson, Brian D.; Akopian, Vardan; Komjathy, Attila; Lijima, Byron A.

2013-01-01

19

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

20

Design and observations of satellite laser ranging system for daylight tracking at Shanghai Observatory  

Microsoft Academic Search

The first satellite laser ranging system for daylight tracking in China was set up at Shanghai Observatory, Chinese Academy\\u000a of Sciences. Both false alarm probability due to strong background noises and detection probability of the laser returns with\\u000a single photon level from satellite in daylight for our system are analysed. The system design and performance characteristics\\u000a of subsystems, adopted techniques

Fumin Yang; Chikun Xiao; Wanzhen Chen; Zhongping Zhang; Detong Tan; Xiangdong Gong; Juping Chen; Huang Li; Jianhua Zhang

1999-01-01

21

Preliminary design of a satellite observation system for Space Station Freedom  

NASA Technical Reports Server (NTRS)

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 (editor); Gallagher, Chris; Wilson, Brian; Rehfeld, James; Maurer, Alexa; Stern, Dan; Nualart, Jaime; Le, Xuan-Trang

1992-01-01

22

Evolution of the Loop Current System During the Deepwater Horizon Oil Spill Event as Observed With Drifters and Satellites  

Microsoft Academic Search

The ocean circulation patterns of the Gulf of Mexico (GOM) Loop Current (LC) system and their effects on the advection of the oil discharged during the Deepwater Horizon incident are described using in situ surface drifter trajectories and satellite observations from May to August 2010. These observations include altimetry-derived surface geostrophic velocities, sea surface temperature, ocean color, and surface oil

Yonggang Liu; Robert H. Weisberg; Chuanmin Hu; Charles Kovach

2011-01-01

23

Simulating satellite infrared sounding retrievals in support of Observing System Simulation Experiments (OSSEs)  

NASA Astrophysics Data System (ADS)

A new set of Observing System Simulation Experiments (OSSEs) are underway to assess the impact of higher spatial and temporal resolution sounding on hurricane forecast accuracy. To support these studies, we have developed an OSSE retrieval simulation system. The system uses a simulated satellite orbit track to provide sample locations and footprint area of the infrared sounder configuration to be simulated over the region of interest. The data to be sampled are an OSSE nature run developed by the NOAA Atlantic Oceanographic Meteorological Laboratory (AOML) and the University of Miami (UM). The nature run is sampled at the sounder locations and integrated over the sounder footprint area. The resulting averaged profiles are smoothed vertically with simulated averaging kernels for the Atmospheric Infrared Sounder (AIRS) using a linear retrieval simulation to produce calculated temperature and water vapor profiles. With reasonable fidelity, the sampled and smoothed profiles simulate the retrievals we can expect from a sounder like AIRS for the orbit and sampling configurations under test. Three instruments were simulated corresponding to the AIRS 4545km footprint in LEO, a hypothetical sounder at 22km footprint in LEO, and a hypothetical GEO sounder at 55km regional and 10km 10km full disk footprint sizes. RMS error relative to the nature run is calculated to demonstrate the error characteristics of the simulation system. The simulated retrievals as a result of this effort are currently being assessed by NOAA AOML in an OSSE study to determine the impact of advanced hyperspectral infrared sounders on hurricane forecast improvement.

Pagano, Thomas S.; Mathews, William; Irion, Frederick W.; Sturm, Erick J.

2014-09-01

24

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. PMID:23552104

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

2013-01-01

25

Estimating zenith tropospheric delays from BeiDou navigation satellite system observations.  

PubMed

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. PMID:23552104

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

2013-01-01

26

Satellite observation of effusive volcanism  

USGS Publications Warehouse

Infrared emission from an active effusive volcanic eruption on Surtsey, Vestmannaeyjar, Iceland, was recorded by airborne and satellite infrared systems at irregular intervals between 19 August and 3 October 1966. Ground and lava temperature measurements and volumetric lava outflow data permitted a comparison to be made between total thermal-energy yield and radiant emission recorded by the satellite system. The Nimbus HRIR recorded radiant emission at a level of about 3% of the estimated total thermal yield.

Williams, R.S., Jr.; Friedman, J.D.

1970-01-01

27

Geopotential Error Analysis from Satellite Gradiometer and Global Positioning System Observables on Parallel Architecture  

NASA Technical Reports Server (NTRS)

The recovery of a high resolution geopotential from satellite gradiometer observations motivates the examination of high performance computational techniques. The primary subject matter addresses specifically the use of satellite gradiometer and GPS observations to form and invert the normal matrix associated with a large degree and order geopotential solution. Memory resident and out-of-core parallel linear algebra techniques along with data parallel batch algorithms form the foundation of the least squares application structure. A secondary topic includes the adoption of object oriented programming techniques to enhance modularity and reusability of code. Applications implementing the parallel and object oriented methods successfully calculate the degree variance for a degree and order 110 geopotential solution on 32 processors of the Cray T3E. The memory resident gradiometer application exhibits an overall application performance of 5.4 Gflops, and the out-of-core linear solver exhibits an overall performance of 2.4 Gflops. The combination solution derived from a sun synchronous gradiometer orbit produce average geoid height variances of 17 millimeters.

Schutz, Bob E.; Baker, Gregory A.

1997-01-01

28

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

Microsoft Academic Search

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

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

2005-01-01

29

Satellite Observations of Tropospheric Chemistry  

NASA Technical Reports Server (NTRS)

The troposphere is an essential component of the earth's life support system as well as the gateway for the exchange of chemicals between different geochemical reservoirs of the earth. The chemistry of the troposphere is sensitive to perturbation from a wide range of natural phenomena and human activities. The societal concern has been greatly enhanced in recent decades due to ever increasing pressures of population growth and industrialization. Chemical changes within the troposphere control a vast array of processes that impact human health, the biosphere, and climate. A main goal of tropospheric chemistry research is to measure and understand the response of atmospheric composition to natural and anthropogenic perturbations, and to develop the capability to predict future change. Atmospheric chemistry measurements are extremely challenging due to the low concentrations of critical species and the vast scales over which the observations must be made. Available tropospheric data are mainly from surface sites and aircraft missions. Because of the limited temporal extent of aircraft observations, we have very limited information on tropospheric composition above the surface. This situation can be contrasted to the stratosphere, where satellites have provided critical and detailed chemical data on the global distribution of key trace gases.

Singh, Hanwant B.; Jacob, Daniel J.; Hipskind, R. Stephen (Technical Monitor)

2001-01-01

30

Planning and Scheduling of Earth Observing Satellites  

Microsoft Academic Search

The roles and interactions of activity planning and scheduling for Earth Observing Satellites are based on factors such as mission objective, system assets and resources, system and spacecraft constraints, planning criteria, scheduling strategies, timelines, and desired level of automation and operator interaction. Activities are generalized into four categories: accomplish the mission objective, support the mission objective, manage the system resources,

D. Kaslow

2007-01-01

31

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

32

Future Satellite Observations of Solar Irradiance  

NASA Technical Reports Server (NTRS)

Required solar irradiance measurements for climate studies include those now being made by the Total Irradiance Monitor (TIM) and the Spectral Irradiance Monitor (SIM) onboard the SORCE satellite, part of the Earth Observing System fleet of NASA satellites. Equivalent or better measures of Total Solar Irradiance (TSI) and Spectral Solar Irradiance (SSI, 200 to 2000 nm) are planned for the post-2010 satellites of the National Polar-orbiting Operational Environmental Satellite System ("OESS). The design life of SORCE is 5 years, so a "Solar Irradiance Gap Filler" EOS mission is being planned for launch in the 2007 time frame, to include the same TSI and SSI measurements. Besides avoiding any gap, overlap of the data sources is also necessary for determination of possible multi-decadal trends in solar irradiance. We discuss these requirements and the impacts of data gaps, and data overlaps, that may occur in the monitoring of the critical solar radiative forcing.

Cahalan, R. F.; Rottman, G.; Woods, T.; Lawrence, G.; Harder, J.; McClintock, W.; Kopp, G.

2003-01-01

33

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

34

Recent Greenland Ice Mass Loss by Drainage System from Satellite Gravity Observations  

Microsoft Academic Search

Mass changes of the Greenland Ice Sheet resolved by drainage system regions were derived from a local mass concentration analysis of NASA Deutsches Zentrum fr Luft- und Raumfahrt Gravity Recovery and Climate Experiment (GRACE mission) observations. From 2003 to 2005, the ice sheet lost 101 16 gigaton\\/year, with a gain of 54 gigaton\\/year above 2000 meters and a loss

S. B. Luthcke; H. J. Zwally; W. Abdalati; D. D. Rowlands; R. D. Ray; R. S. Nerem; F. G. Lemoine; J. J. McCarthy; D. S. Chinn

2006-01-01

35

The use of small satellites in the NASA Earth Science Enterprise (ESE) Earth Observing System (EOS)  

Microsoft Academic Search

As NASA looks to reshape the Earth Observing System for the post-2002 mission timelines, we argue that small, commercial buses can be modified to carry key instruments as hot spares, technology demonstrations, or in support of new programmatic imperatives. We consider the particular case of the Indium bus flying a new sensor to demonstrate the utility of measuring ozone via

Larry J. Paxton; Jeng-Hwa Yee; Glen Fountain; C. I. Meng

2000-01-01

36

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 47.03N, 22.45E, 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 (44.99N, 26.1E), 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. PMID:23519349

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

2013-01-01

37

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

38

NASA's small satellite missions for Earth observation  

NASA Astrophysics Data System (ADS)

The mission of NASA's Earth Science Enterprise (ESE) is to develop a scientific understanding of the Earth system and its response to natural and human-induced changes to enable improved prediction of climate, weather, and natural hazards for present and future generations. The ESE has an end-to-end strategy to assure that information, understanding, and capabilities derived from its research program achieve maximum usefulness to the scientific and decision-making communities. Small satellites ( <500 kg) have been crucial contributors to satisfying the research strategy since the inception of NASA's Earth observation program in the 1960s. In the last decade, NASA's ESE has placed a renewed emphasis on small satellites. This reemphasis reflects advancements in compact sensor, small satellite bus, and launch vehicle technologies in addition to management innovations. Near term and advanced planning suggest that this trend will continue. A number of related small satellite missions have been recently launched, are in development, or are planned. Multi-satellite constellations under study include small satellites as key architectural elements. Studies indicate that low cost, capable microspacecraft along with compact sensors and increased autonomy are technology enablers to the sensorwebs and associated distributed spacecraft infrastructure required to realize the long-term NASA Earth Science Vision (ESV).

Neeck, Steven P.; Magner, Thomas J.; Paules, Granville E.

2005-01-01

39

Concept design of future intelligent Earth observing satellites  

Microsoft Academic Search

This paper presents a concept design of an envisioned future intelligent Earth observing satellite (FIEOS) system. The proposed system is a space-based architecture for the dynamic and comprehensive on-board integration of Earth observing sensors, data processors and communication systems. The architecture and implementation strategies suggest a seamless integration of diverse components into a smart, adaptable and robust Earth observation satellite

G. Zhou; O. Baysal; J. Kaye; S. Habib; C. Wang

2004-01-01

40

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

41

Jupiter System Observer  

NASA Technical Reports Server (NTRS)

This slide presentation reviews the proposed mission for the Jupiter System Observer. The presentation also includes overviews of the mission timeline, science goals, and spacecraftspecifications for the satellite.

Senske, Dave; Kwok, Johnny

2008-01-01

42

A Regional Climate Model Evaluation System based on contemporary Satellite and other Observations for Assessing Regional Climate Model Fidelity  

NASA Astrophysics Data System (ADS)

Evaluation of climate models against observations is an essential part of assessing the impact of climate variations and change on regionally important sectors and improving climate models. Regional climate models (RCMs) are of a particular concern. RCMs provide fine-scale climate needed by the assessment community via downscaling global climate model projections such as those contributing to the Coupled Model Intercomparison Project (CMIP) that form one aspect of the quantitative basis of the IPCC Assessment Reports. The lack of reliable fine-resolution observational data and formal tools and metrics has represented a challenge in evaluating RCMs. Recent satellite observations are particularly useful as they provide a wealth of information and constraints on many different processes within the climate system. Due to their large volume and the difficulties associated with accessing and using contemporary observations, however, these datasets have been generally underutilized in model evaluation studies. Recognizing this problem, NASA JPL and UCLA have developed the Regional Climate Model Evaluation System (RCMES) to help make satellite observations, in conjunction with in-situ and reanalysis datasets, more readily accessible to the regional modeling community. The system includes a central database (Regional Climate Model Evaluation Database: RCMED) to store multiple datasets in a common format and codes for calculating and plotting statistical metrics to assess model performance (Regional Climate Model Evaluation Tool: RCMET). This allows the time taken to compare model data with satellite observations to be reduced from weeks to days. RCMES is a component of the recent ExArch project, an international effort for facilitating the archive and access of massive amounts data for users using cloud-based infrastructure, in this case as applied to the study of climate and climate change. This presentation will describe RCMES and demonstrate its utility using examples from RCMs applied to the southwest US as well as to Africa based on output from the CORDEX activity. Application of RCMES to the evaluation of multi-RCM hindcast for CORDEX-Africa will be presented in a companion paper in A41.

Waliser, D. E.; Kim, J.; Mattman, C.; Goodale, C.; Hart, A.; Zimdars, P.; Lean, P.

2011-12-01

43

The Effect of Environmental Conditions on Tropical Deep Convective Systems Observed from the TRMM Satellite  

NASA Technical Reports Server (NTRS)

This study uses measurements of radiation and cloud properties taken between January and August 1998 by three Tropical Rainfall Measuring Mission (TRMM) instruments, the Clouds and the Earth's Radiant Energy System (CERES) scanner, the TRMM Microwave Imager (TMI), and the Visible and InfraRed Scanner (VIRS), to evaluate the variations of tropical deep convective systems (DCS) with sea surface temperature (SST) and precipitation. This study finds that DCS precipitation efficiency increases with SST at a rate of approx. 2%/K. Despite increasing rainfall efficiency, the cloud areal coverage rises with SST at a rate of about 7%/K in the warm tropical seas. There, the boundary layer moisture supply for deep convection and the moisture transported to the upper troposphere for cirrus-anvil cloud formation increase by approx. 6.3%/K and approx. 4.0%/K, respectively. The changes in cloud formation efficiency, along with the increased transport of moisture available for cloud formation, likely contribute to the large rate of increasing DCS areal coverage. Although no direct observations are available, the increase of cloud formation efficiency with rising SST is deduced indirectly from measurements of changes in the ratio of DCS ice water path and boundary layer water vapor amount with SST. Besides the cloud areal coverage, DCS cluster effective sizes also increase with precipitation. Furthermore, other cloud properties, such as cloud total water and ice water paths, increase with SST. These changes in DCS properties will produce a negative radiative feedback for the earth's climate system due to strong reflection of shortwave radiation by the DCS. These results significantly differ from some previous hypothesized dehydration scenarios for warmer climates, and have great potential in testing current cloud-system resolving models and convective parameterizations of general circulation models.

Lin, Bing; Wielicki, Bruce A.; Minnis, Patrick; Chambers, Lin H.; Xu, Kuan-Man; Hu, Yongxiang; Fan, Tai-Fang

2005-01-01

44

Applications systems verification and transfer project. Volume 1: Operational applications of satellite snow cover observations: Executive summary. [usefulness of satellite snow-cover data for water yield prediction  

NASA Technical Reports Server (NTRS)

Both LANDSAT and NOAA satellite data were used in improving snowmelt runoff forecasts. When the satellite snow cover data were tested in both empirical seasonal runoff estimation and short term modeling approaches, a definite potential for reducing forecast error was evident. A cost benefit analysis run in conjunction with the snow mapping indicated a $36.5 million annual benefit accruing from a one percent improvement in forecast accuracy using the snow cover data for the western United States. The annual cost of employing the system would be $505,000. The snow mapping has proven that satellite snow cover data can be used to reduce snowmelt runoff forecast error in a cost effective manner once all operational satellite data are available within 72 hours after acquisition. Executive summaries of the individual snow mapping projects are presented.

Rango, A.

1981-01-01

45

GIFTS - the precursor geostationary satellite component of the future Earth Observing System  

Microsoft Academic Search

The Geosynchronous Imaging Fourier Transform Spectrometer (GIFTS) combines advanced technologies to observe surface thermal properties and atmospheric weather and chemistry variables in four dimensions. Large area format Focal Plane detector Arrays (LFPAs) provide near instantaneous large area coverage with high horizontal resolution. A Fourier Transform Spectrometer (FTS) enables atmospheric radiance spectra to be observed simultaneously for all LFPA detector elements

W. L. Smith; F. W. Harrison; D. E. Hinton; H. E. Revercomb; G. E. Bingham; R. Petersen; J. C. Dodge

2002-01-01

46

Observations of planetary satellites with ISO  

NASA Astrophysics Data System (ADS)

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 the data has provided original and precious information on the satellites' surfaces and Titan's atmosphere in particular.

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

47

Satellite observations of polar arcs  

NASA Astrophysics Data System (ADS)

The increased probability of observing polar arcs during periods of northward interplanetary magnetic field (IMF) has tended to obscure their significance in terms of magnetospheric topology because of the presumed 'inactive' state of the magnetosphere. However, satellite imaging has shown that these high latitude features are quite dynamic both in their intensity and spatial variations. The overall morphology of the high latitude aurora has been described by a variety of imaginative terms, but its primary optical characteristic is of a polar arc(s) extending between the dayside and nightside auroral distribution on one or both of the dawn/dusk sides of the high latitude region. This large scale morphology is controlled by the azimuth angle of the IMF and the predominant configuration is one wherein the region between the polar arc and the normal auroral distribution is filled with low intensity diffuse emission. Simultaneous particle and electric field measurements show this region exhibits a closed field line character with predominantly sunward flowing plasma. These large scale polar arcs are connected (in either a diffuse or discrete fashion) to the nightside auroral distribution with essentially equal probabilities, but exhibit a clear peak near 12 MLT. This dayside connection is commonly associated with isolated high latitude features poleward of the normal auroral distribution which probably represent processes occurring on the front surface of the magnetotail poleward of the cusp. The existence of polar arcs is not always controlled by substorm activity: polar arcs can maintain their form and position well past expansion phase suggesting that they represent a fundamental boundary in the magnetosphere which is not modified by even large substorms.

Murphree, J. S.; Austin, J. B.; Hearn, D. J.; Cogger, L. L.; Elphinstone, R. D.; Woch, J.

1994-02-01

48

Connection of two geodetic systems by observations of artificial satellites of the earth  

Microsoft Academic Search

The orientation of the ellipsoid in the earthbody depends on the manner of its localization in respect to the geoid at the origin triangulation point. An alteration of the geodetic coordinates of this point induces a parallel shifting of the geodetic system in respect to the terrestrial system, that is, in regard to the mean axis of the Earth rotation

W. Dobaczewska

1968-01-01

49

Severe storms observing satellite (STORMSAT)  

NASA Technical Reports Server (NTRS)

The primary payload for this satellite is the Advanced Atmospheric Sounding and Imaging Radiometer which will perform precise infrared temperature sounding and visible/infrared imaging from geostationary orbit. A secondary payload instrument which may be utilized on STORMSAT is the Microwave Atmospheric Sounding Radiometer which provides an independent set of temperature and humidity sounding in cloudy, meteorologically active regions. The study provides satellite designs and identifies mission-unique subsystems using the Multimission Modular Spacecraft using a Shuttle/Interim Upper Stage launch vehicle.

1976-01-01

50

Transit satellite system timing capabilities  

NASA Technical Reports Server (NTRS)

Current time transfer capabilities of the Transit Satellite System are reviewed. Potential improvements in the changes in equipment and operational procedures using operational satellites are discussed.

Finsod, T. D.

1978-01-01

51

Sentinel Satellites Initiate New Era in Earth Observation  

NASA Astrophysics Data System (ADS)

With the European Space Agency's (ESA) Sentinel-1A satellite expected to enter into its operational phase later this summer, it ushers in a new series of Earth observation satellites. The first generation of the fleet of satellites, which will total 20 when all are launched, will comprise "the most comprehensive Earth observation system worldwide," according to Josef Aschbacher, head of program planning and coordination for ESA's Earth Observation Programs directorate. The satellites are a key part of Copernicus, the European Earth Observation Program that from 1998 to 2012 was called the Global Monitoring for Environment and Security (GMES) program.

Showstack, Randy

2014-07-01

52

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...

53

Orbit Design of Earth-Observation Satellite  

NASA Astrophysics Data System (ADS)

The purpose of this study is to design a reliable orbit for a medium-resolution scientific satellite to observe Earth for developmental issues such as water resources, agricultural, and industrial. To meet this objective this study firstly, defines the mission, secondly, determines mission constraints, thirdly, design the attitude and orbit control system. As for the observation requirements, and the revisit time are provided as a function of the orbital parameters. Initial orbital parameters are obtained by optimal analysis between observation characteristics and attitude and orbit maintenance costs. Long term station-keeping strategies will be provided for the proposed solutions. Impulsive control will be investigated to provide a reliable and affordable attitude and orbit control system.

Owis, Ashraf

54

Applications systems verification and transfer project. Volume 4: Operational applications of satellite snow cover observations. Colorado Field Test Center  

NASA Technical Reports Server (NTRS)

The study was conducted on six watersheds ranging in size from 277 km to 3460 km in the Rio Grande and Arkansas River basins of southwestern Colorado. Six years of satellite data in the period 1973-78 were analyzed and snowcover maps prepared for all available image dates. Seven snowmapping techniques were explored; the photointerpretative method was selected as the most accurate. Three schemes to forecast snowmelt runoff employing satellite snowcover observations were investigated. They included a conceptual hydrologic model, a statistical model, and a graphical method. A reduction of 10% in the current average forecast error is estimated when snowcover data in snowmelt runoff forecasting is shown to be extremely promising. Inability to obtain repetitive coverage due to the 18 day cycle of LANDSAT, the occurrence of cloud cover and slow image delivery are obstacles to the immediate implementation of satellite derived snowcover in operational streamflow forecasting programs.

Shafer, B. A.; Leaf, C. F.; Danielson, J. A.; Moravec, G. F.

1981-01-01

55

Applications systems verification and transfer project. Volume 5: Operational applications of satellite snow-cover observations, northwest United States  

NASA Technical Reports Server (NTRS)

The study objective was to develop or modify methods in an operational framework that would allow incorporation of satellite derived snow cover observations for prediction of snowmelt derived runoff. Data were reviewed and verified for five basins in the Pacific Northwest. The data were analyzed for up to a 6-year period ending July 1978, and in all cases cover a low, average, and high snow cover/runoff year. Cloud cover is a major problem in these springtime runoff analyses and have hampered data collection for periods of up to 52 days. Tree cover and terrain are sufficiently dense and rugged to have caused problems. The interpretation of snowlines from satellite data was compared with conventional ground truth data and tested in operational streamflow forecasting models. When the satellite snow-covered area (SCA) data are incorporated in the SSARR (Streamflow Synthesis and Reservoir Regulation) model, there is a definite but minor improvement.

Dillard, J. P.

1981-01-01

56

Satellite Observations of Forest Fires  

NSDL National Science Digital Library

The Ocean Remote Sensing Group of the Johns Hopkins University Applied Physics Laboratory has made available a series of maps of some of the fifteen major wildfires that were burning Wednesday across 264,794 acres in six Western states--Oregon, California, Idaho, Wyoming, Utah, and Colorado. The images are not intended as a working fire detection resource, but are offered as interesting observations. Background information is provided, and the subject matter of each image is briefly described. The files are in GIF format and range in size from 200 to 500K. The publicly available data used is from the NOAA polar orbiter AVHRR sensor, which scans the earth beneath six times per second. Links are provided to the Wildland Fire Assessment System of the USDA and Go West forest fire reports, which offers a list of links for each state with major fires.

Sterner, Ray.

1996-01-01

57

Satellite communications system  

NASA Astrophysics Data System (ADS)

A satellite communication system is disclosed which provides an increased probability of reception by selective call receivers. In carrying out the invention in one form, there is provided a method comprising the step of relaying, from two or more locations via at least one satellite, a transmission to a receiver. By relaying the information being transmitted from two different locations (angles) at different points in time, the probability of reception is increased. Programming means are provided for determining the first and second locations and times of transmitting the information.

Schwendeman, Robert J.

1993-04-01

58

NASDA's future Earth observation satellite plan  

Microsoft Academic Search

NASDA studies future Earth observation satellite plan during 2005-2015 to promote global change and application study. There are three primary missions (1) continuos global observation mission for Earth science, (2) society application mission and (3) process study mission under international cooperation. GCOM (Global Change Observation Mission) is primary mission of continuous global observation mission for 15 years with ADEOS-II. For

S. Sobue; N. Tomii; T. Moriyama; C. Ishida; T. Kohji; S. Kamijo

2000-01-01

59

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

60

Magnetopause structure from satellite observations  

NASA Technical Reports Server (NTRS)

Observations on magnetopause structure are reported. Major topics covered include: classical reconnection, transport mechanisms, magnetospheric boundary layers, tearing modes, and Jupiter's magnetopause.

Sonnerup, B. U. O.

1979-01-01

61

Satellite observations of Antarctic subglacial hydrology  

NASA Astrophysics Data System (ADS)

A series of recent discoveries regarding Antarctic subglacial hydrology have shown that the interaction between an ice sheet and its underlying water system is more active and complex than had been imagined. A better understanding of the physical processes and spatial extent of subglacial hydrologic systems is needed to assess their impact on ice sheet dynamics, and to correctly incorporate subglacial hydrology into ice sheet models. This requires a clearer picture of the locations of subglacial reservoirs, the frequency and quantity of water exchanged between them, and the configuration of subglacial conduits. Datasets for studying subglacial hydrology are, however, limited both in spatial and temporal coverage because the environment is remote and inaccessible. Since 2005, satellite observations (InSAR and radar/laser altimetry) have transformed our understanding of the Antarctic subglacial environment. Before this, most known subglacial lakes were near ice divides, and were thought to be isolated, and exerting only localised influence on the ice flow. By inference from rapid, localised surface elevation changes measured by satellite, subglacial water has been observed to move rapidly between sub-ice reservoirs; refill and drainage can occur via steady flow and/or episodic floods. Mapping of surface slope and ice thickness shows that the reservoirs, and inferred conduits, lie precisely in regions of lower hydropotential. Active lakes have been detected throughout many glacial catchment basins; lakes not only exist under the ice divides, but are also present under upper catchment areas and the fast-flowing ice streams. Complex hydrologic systems consisting of interconnected water bodies have been observed in the lower ice streams, with fill-drain cycles of years to decades. Although in one case (Byrd Glacier) a subglacial flooding event led to a temporary 15% increase in mass flux, the impact of these subglacial water systems on ice dynamics and ice sheet mass balance remains largely unknown.

Fricker, H. A.; Carter, S. P.; Scambos, T. A.

2011-12-01

62

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

63

Laser satellite power systems  

SciTech Connect

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 laser beam. The laser SPS may be an alternative to the microwave SPS. Microwaves easily penetrate clouds while laser radiation does not. Although there is this major disadvantage to a laser SPS, that system has four important advantages over the microwave alternative: (1) land requirements are much less, (2) radiation levels are low outside the laser ground stations, (3) laser beam sidelobes are not expected to interfere with electromagnetic systems, and (4) the laser system lends itself to small-scale demonstration. After describing lasers and how they work, the report discusses the five lasers that are candidates for application in a laser SPS: electric discharge lasers, direct and indirect solar pumped lasers, free electron lasers, and closed-cycle chemical lasers. The Lockheed laser SPS is examined in some detail. To determine whether a laser SPS will be worthy of future deployment, its capabilities need to be better understood and its attractiveness relative to other electric power options better assessed. First priority should be given to potential program stoppers, e.g., beam attenuation by clouds. If investigation shows these potential program stoppers to be resolvable, further research should investigate lasers that are particularly promising for SPS application.

Walbridge, E.W.

1980-01-01

64

Satellite freeze forecast system  

NASA Technical Reports Server (NTRS)

Provisions for back-up operations for the satellite freeze forecast system are discussed including software and hardware maintenance and DS/1000-1V linkage; troubleshooting; and digitized radar usage. The documentation developed; dissemination of data products via television and the IFAS computer network; data base management; predictive models; the installation of and progress towards the operational status of key stations; and digital data acquisition are also considered. The d addition of dew point temperature into the P-model is outlined.

Martsolf, J. D. (principal investigator)

1983-01-01

65

Satellite retrieval system  

NASA Technical Reports Server (NTRS)

A satellite retrieval system with first and second pairs of coacting parallel bars are separately mounted in spaced parallel planes on the front of a spacecraft. The bars of one pair are at right angles to bars of the other pair, and together the two pairs of bars effect a variable aperture adapted to close around a rod extending from a second spacecraft to effect the capture of the latter.

Pruett, E. C.; Robertson, K. B.; Loughead, T. E. (inventors)

1983-01-01

66

Generic satellite monitoring expert system  

NASA Astrophysics Data System (ADS)

Air Force Satellite Operations is undergoing major changes. Operators no longer receive detailed satellite training, instead they are taught basic fundamentals of satellite operations and expected to control multiple multimillion dollar satellites. The need is clear. An efficient and economical automated system is necessary to assist the satellite operator in the daily tasks of maintaining these DOD priority resources. Satellite intelligent controllers have been under R&D since the early 1980's to meet this need. These systems, however, have focused on the control of one constellation of satellites. In a military striving for efficiency and lower costs, developing a unique intelligent controller for each satellite constellation is unaffordable. This research provided support for the concept of a generic satellite intelligent controller, through the development of a prototype expert system. This capability would allow a generic rule-base to operate and maintain multiple satellite systems. The initial prototype detected anomalies on one subsystem of two different satellites. After the third satellite prototype was created, a third satellite was analyzed to show support for the viability of the satellite prototype. More research is necessary, but this thesis has created support for the concept of generic satellite controller and has laid the foundation for future extensions.

Kelemen, Loretta A.

1994-12-01

67

ASTER satellite observations for international disaster management  

USGS Publications Warehouse

When lives are threatened or lost due to catastrophic disasters, and when massive financial impacts are experienced, international emergency response teams rapidly mobilize to provide urgently required support. Satellite observations of affected areas often provide essential insight into the magnitude and details of the impacts. The large cost and high complexity of developing and operating satellite flight and ground systems encourages international collaboration in acquiring imagery for such significant global events in order to speed delivery of critical information to help those affected, and optimize spectral, spatial, and temporal coverage of the areas of interest. The International Charter-Space and Major Disasters was established to enable such collaboration in sensor tasking during times of crisis and is often activated in response to calls for assistance from authorized users. Insight is provided from a U.S. perspective into sensor support for Charter activations and other disaster events through a description of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), which has been used to support emergency situations for over a decade through its expedited tasking and near real-time data delivery capabilities. Examples of successes achieved and challenges encountered in international collaboration to develop related systems and fulfill tasking requests suggest operational considerations for new missions as well as areas for future enhancements.

Duda, K.A.; Abrams, M.

2012-01-01

68

The artificial satellite observation chronograph controlled by single chip microcomputer.  

NASA Astrophysics Data System (ADS)

The instrument specifications, hardware structure, software design, and other characteristics of the chronograph mounting on a theodolite used for artificial satellite observation are presented. The instrument is a real time control system with a single chip microcomputer.

Pan, Guangrong; Tan, Jufan; Ding, Yuanjun

1991-06-01

69

Severe storms observing satellite study  

NASA Technical Reports Server (NTRS)

Payload distribution and the attitude control system for the multi-mission modular spacecraft/StormSat configuration are discussed. The design of the advanced atmospheric sounder and imaging radiometer (AASIR) gimbal drive and its servomechanism is described. Onboard data handling, data downlink communications, and ground data handling systems are developed. Additional topics covered include: magnetic unloading at synchronous altitude, north-south stationkeeping, and the feasibility and impact of flying the microwave atmospheric sounding radiometer (MASR) as an additional payload.

Iwens, R. P.; Stern, D. A.

1976-01-01

70

Lightning-Generated Whistler Waves Observed by Probes On The Communication/Navigation Outage Forecast System Satellite at Low Latitudes  

NASA Technical Reports Server (NTRS)

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.

2011-01-01

71

Investigation of mesoscale meteorological phenomena as observed by geostationary satellite  

NASA Technical Reports Server (NTRS)

Satellite imagery plus conventional synoptic observations were used to examine three mesoscale systems recently observed by the GOES-EAST satellite. The three systems are an arc cloud complex (ACC), mountain lee wave clouds and cloud streets parallel to the wind shear. Possible gravity-wave activity is apparent in all three cases. Of particular interest is the ACC because of its ability to interact with other mesoscale phenomena to produce or enhance convection.

Brundidge, K. C.

1982-01-01

72

The observation of artificial satellites and VLBI  

NASA Astrophysics Data System (ADS)

Satellite and lunar laser ranging, very long base interferometry (VLBI), and Doppler and directional measurements of satellites are described. A stationary Nd : YAG ranging system was operated. A modular transportable laser ranging system was developed. Time services based on cesium, rubidium, and Besson quartz frequency standards and a hydrogen maser are discussed. Applications of VLBI to geodesy, geophysics and astrometry are summarized. The TIMEDOC, BONDOC, WESTHARZ, ERIDOC, NIEDOC, ALGEDOP, BLNDOC and CIDOC, Doppler campaigns are outlined. Marine geodesy and ice monitoring are mentioned.

Reinhart, E.; Seeger, H.; Wilson, P.

73

The AMSC mobile satellite system  

Microsoft Academic Search

The American Mobile Satellite Consortium (AMSC) Mobile Satellite Service (MSS) system is described. AMSC will use three multi-beam satellites to provide L-band MSS coverage to the United States, Canada and Mexico. The AMSC MSS system will have several noteworthy features, including a priority assignment processor that will ensure preemptive access to emergency services, a flexible SCPC channel scheme that will

Carson E. Agnew; Jai Bhagat; Edwin A. Hopper; John D. Kiesling; Michael L. Exner; Lawrence Melillo; Gary K. Noreen; Billy J. Parrott

1988-01-01

74

New inclined synchronous satellite system for mobile communications and radiodetermination  

Microsoft Academic Search

A new satellite system using inclined synchronous satellites is proposed. This system can provide radiodetermination services as well as communication services for mobile earth stations in the common satellite system. In this system, two or more satellites can be always observed at the same time from any mobile terminal on the earth (including the polar regions) with an elevation angle

Fumiaki Sugaya; Yutaka Yasuda; Yasuo Hirata

1988-01-01

75

Applications systems verification and transfer project. Volume 2: Operational applications of satellite snow-cover observations and data-collection systems in the Arizona test site  

NASA Technical Reports Server (NTRS)

Ground surveys and aerial observations were used to monitor rapidly changing moisture conditions in the Salt-Verde watershed. Repetitive satellite snow cover observations greatly reduce the necessity for routine aerial snow reconnaissance flights over the mountains. High resolution, multispectral imagery provided by LANDSAT satellite series enabled rapid and accurate mapping of snow-cover distributions for small- to medium-sized subwatersheds; however, the imagery provided only one observation every 9 days of about a third of the watershed. Low resolution imagery acquired by the ITOSa dn SMS/GOES meteorological satellite series provides the daily synoptic observation necessary to monitor the rapid changes in snow-covered area in the entire watershed. Short term runoff volumes can be predicted from daily sequential snow cover observations.

Schumann, H. H.

1981-01-01

76

Comparison of filter predictions with satellite observations  

SciTech Connect

Satellite observations of meteor entry are used to calibrate a filter model of fragmentation. Predicted sizes and masses compare favorably with data and analytic interpretations for objects of all sizes. However, objects that fragment into many large objects should be treated by the decomposition of the radiation signal into the contributions from the different fragments.

Canavan, G.H.

1997-10-01

77

NASA Launches New Earth Observation Satellite  

E-print Network

Charles Bolden said. "This data is a key tool for monitoring climate change and has led to the improvementNASA Launches New Earth Observation Satellite Pg 3 Deciphering the Mysterious Math of the Solar Administration www.nasa.gov Volume 9 Issue 2 March 2013 #12;N ASA's Landsat Data Continuity Mission (LDCM) roared

Christian, Eric

78

Satellite Power System (SPS)  

NASA Technical Reports Server (NTRS)

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 feasibility (both national and international); and cost effectiveness (including environmental and other external costs). Based on these criteria, four organizational alternatives appeared to offer reasonable promise as potential options for SPS. A large number of key issues emerged as being factors which would influence the final selection process. Among these issues were a variety having to do with international law, international institutions, environmental controls, economics, operational flexibility, congressional policies, commercial-vs-governmental ownership, national dedication, and national and operational stategic issues.

Edler, H. G.

1978-01-01

79

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 10⁸ (cm²-sec-sterad-keV)⁻¹. The observations were

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

1976-01-01

80

Scheduling Earth Observing Satellites with Evolutionary Algorithms  

NASA Technical Reports Server (NTRS)

We hypothesize that evolutionary algorithms can effectively schedule coordinated fleets of Earth observing satellites. The constraints are complex and the bottlenecks are not well understood, a condition where evolutionary algorithms are often effective. This is, in part, because evolutionary algorithms require only that one can represent solutions, modify solutions, and evaluate solution fitness. To test the hypothesis we have developed a representative set of problems, produced optimization software (in Java) to solve them, and run experiments comparing techniques. This paper presents initial results of a comparison of several evolutionary and other optimization techniques; namely the genetic algorithm, simulated annealing, squeaky wheel optimization, and stochastic hill climbing. We also compare separate satellite vs. integrated scheduling of a two satellite constellation. While the results are not definitive, tests to date suggest that simulated annealing is the best search technique and integrated scheduling is superior.

Globus, Al; Crawford, James; Lohn, Jason; Pryor, Anna

2003-01-01

81

Satellite observations of Magnetospheric Line Radiation  

NASA Astrophysics Data System (ADS)

Magnetospheric Line Radiation (MLR) events are electromagnetic waves in the frequency range from about 1 to 8 kHz observed both by low-altitude satellites and on the ground that - when represented in a traditional form of frequency-time spectrograms - consist of several nearly horizontal and almost parallel intense lines. Although their existence is known for quite a long time, their origin is still not understood. We analyze the MLR events observed by the DEMETER satellite (altitude about 700 km, nearly Sun-synchronous orbit at 10:30/22:30 LT) during more than 6 years of its mission. This enormous set of data enabled us to compile the largest data set of the satellite observations of MLR events available up to date. We systematically analyze the events, paying a special attention to the frequency spacing between individual lines and their drift rate. DEMETER measurements of energetic particles are used in addition to the wave measurements in order to try to understand the wave-particle interactions taking place. Finally, we have identified an MLR event observed simultaneously by DEMETER and the Cluster spacecraft in the equatorial region at L~4. A detailed wave analysis of the STAFF-SA measurements on board Cluster reveals that the spacecraft were most likely located in the source region of the MLR event. We perform a detailed analysis of this exceptional observation.

Nemec, F.; Parrot, M.; Santolik, O.

2011-12-01

82

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

83

A geopause satellite system concept  

NASA Technical Reports Server (NTRS)

A typical Geopause satellite orbit has a 14 hour period, a mean height of about 4.6 earth radii, and is nearly circular, polar, and normal to the ecliptic. At this height only a relatively few gravity terms have uncertainties corresponding to orbital perturbations above the decimeter level. The orbit is at the geopotential boundary, the geopause. The few remaining environmental quantities which may be significant can be determined by means of orbit analysis and accelerometers. The Geopause satellite system also provides the tracking geometry and coverage needed for determining the orbit, the tracking system biases and the station locations. Five or more fundamental stations well distributed in longitude can view Geopause over the North Pole. Geopause also provides the basic capability for satellite-to-satellite tracking of drag-free satellites for mapping the gravity field and altimeter satellites for surveying the sea surface topography.

Siry, J. W.

1971-01-01

84

Use of meteorological satellite observations in weather modification programs  

NASA Technical Reports Server (NTRS)

The potential value of weather satellite data in field operations of weather modification is appraised. It was found that satellites could play a useful role in operational weather modification projects, particularly in the recognition of treatment opportunities. Satellite cloud photographs and infrared observations appear promising in the identification of treatment opportunities in seeding orographic cloud systems for increased snowpack, in seeding convective clouds for increased rainfall, in identifying hail threats, and in tracking and observing hurricanes as an aid to timing and location of seeding treatments. It was concluded that the potential value of satellite data in the treatment and evaluation phases of operational projects is not as great as in the recognition of treatment opportunity.

Dennis, A. S.; Smith, P. L., Jr.; Biswas, K. R.

1973-01-01

85

Evolution of the Loop Current System During the Deepwater Horizon Oil Spill Event as Observed With Drifters and Satellites  

E-print Network

Evolution of the Loop Current System During the Deepwater Horizon Oil Spill Event as Observed reestablishing a direct LC pathway from the region of the oil spill to the Florida Straits. The mean geostrophic role in advecting the oil from the spill site. On the northern side, shelf currents are generally

Meyers, Steven D.

86

Communications satellite systems capacity analysis  

NASA Technical Reports Server (NTRS)

Analog and digital modulation techniques are compared with regard to efficient use of the geostationary orbit by communications satellites. Included is the definition of the baseline systems (both space and ground segments), determination of interference susceptibility, calculation of orbit spacing, and evaluation of relative costs. It is assumed that voice or TV is communicated at 14/11 GHz using either FM or QPSK modulation. Both the Fixed-Satellite Service and the Broadcasting-Satellite Service are considered. For most of the cases examined the digital approach requires a satellite spacing less than or equal to that required by the analog approach.

Browne, L.; Hines, T.; Tunstall, B.

1982-01-01

87

Geostationary satellite observations of dynamic phytoplankton photophysiology  

NASA Astrophysics Data System (ADS)

June 2010, the Geostationary Ocean Color Imager (GOCI) has been collecting the first diurnally resolved satellite ocean measurements. Here GOCI retrievals of phytoplankton chlorophyll concentration and fluorescence are used to evaluate daily to seasonal changes in photophysiological properties. We focus on nonphotochemical quenching (NPQ) processes that protect phytoplankton from high light damage and cause strong diurnal cycles in fluorescence emission. This NPQ signal varies seasonally, with maxima in winter and minima in summer. Contrary to expectations from laboratory studies under constant light conditions, this pattern is highly consistent with an earlier conceptual model and recent field observations. The same seasonal cycle is registered in fluorescence data from the polar-orbiting Moderate Resolution Imaging Spectroradiometer Aqua satellite sensor. GOCI data reveal a strong correlation between mixed layer growth irradiance and fluorescence-derived phytoplankton photoacclimation state that can provide a path for mechanistically accounting for NPQ variability and, subsequently, retrieving information on iron stress in global phytoplankton populations.

O'Malley, Robert T.; Behrenfeld, Michael J.; Westberry, Toby K.; Milligan, Allen J.; Shang, Shaoling; Yan, Jing

2014-07-01

88

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)] [Los Alamos National Lab., NM (United States)

1995-04-15

89

Land mobile satellite system requirements  

NASA Technical Reports Server (NTRS)

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.

1983-01-01

90

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

91

Satellite positive ion beam system  

Microsoft Academic Search

The Satellite Positive Ion Beam Systems (SPIBS) program was initiated by the Air Force Geophysics Laboratory (AFGL) Aeronomy Division with the long-range objective of operating an ion-ejection instrument on the Air Force SCATHA (Spacecraft Charging at High Altitude) satellite. This report describes the development details for breadboard, engineering, and flight models of the SPIBS instrument. A fourth model, a rocket

T. D. Masek

1978-01-01

92

SSETO-Small Satellite for Exoplanetary Transit Observation  

NASA Astrophysics Data System (ADS)

SSETO is the result of a phase-A study in context of the small satellite program of the University of Stuttgart that demonstrates the capability of a university institute to build a small satellite with a budget of 5 million Euro. The satellite will be capable of observing exoplanets in a Neptune-Earth scale and obtaining data of interstellar dust. Due to a system failure of NASA?s Kepler mission, there is currently (October 2013) a lack of satellites searching for exoplanets. This paper details the design of subsystems and payload, as well as the required test tasks in accordance with the mission profile at a conceptional level. The costs for standard spacecraft testing and integration tasks are included, but not those of launch, ground support, operations and engineer working hours.

Mathies, Johannes; Mauceri, Steffen; Pfeiffer, Lukas; Vietze, Marco; Roeser, Hans-Peter; Boehringer, Felix; Lengowski, Michael

2014-11-01

93

Meteorological Satellites (METSAT) and Earth Observing System (EOS) Advanced Microwave Sounding Unit-A (AMSU-A) Stress Analysis Report  

NASA Technical Reports Server (NTRS)

Stress analysis of the primary structure of the Meteorological Satellites Project (METSAT) Advanced Microwave Sounding Units-A, A1 Module using static loads is presented. The structural margins of safety and natural frequency predictions for the METSAT design are reported.

Heffner, Robert

1996-01-01

94

Satellite laser ranging observation at Shanghai Astronomical Observatory in 1997  

Microsoft Academic Search

This is a report of satellite laser ranging observations at Shanghai Astronomical Observatory in 1997. The total 1118 passes and 477661 observations for 18 satellites are obtained. The acievement of daylight laser ranging at Shanghai Astronomical Observatory is presented.

Fumin Yang; Wanzhen Chen; Juping Chen; Zhongping Zhang; Huang Li; Yongping Xu; Xiaohai Xia; Chikun Xiao

1999-01-01

95

NASA Now: Orbital Mechanics: Earth Observing Satellites  

NASA Video Gallery

This NASA Now program is all about satellites and their orbits. Dr. James Gleason, project scientist for NPP, explains what it takes for a satellite to stay in orbit, why there are different types ...

96

An estimation of the condensation rates in three severe storm systems from satellite observations of the convective mass flux  

NASA Technical Reports Server (NTRS)

A technique was developed for estimating the condensation rates of convective storms using satellite measurements of cirrus anvil expansion rates and radiosonde measurements of environmental water vapor. Three cases of severe convection in Oklahoma were studied and a diagnostic model was developed for integrating radiosonde data with satellite data. Two methods were used to measure the anvil expansion rates - the expansion of isotherm contours on infrared images, and the divergent motions of small brightness anomalies tracked on the visible images. The differences between the two methods were large as the storms developed, but these differences became small in the latter stage of all three storms. A comparison between the three storms indicated that the available moisture in the lowest levels greatly affected the rain rates of the storms. This was evident from both the measured rain rates of the storms and the condensation rates estimated by the model. The possibility of using this diagnostic model for estimating the intensities of convective storms also is discussed.

Mack, R. A.; Wylie, D. P.

1982-01-01

97

The data distribution satellite system  

NASA Technical Reports Server (NTRS)

The Data Distributed Satellite (DDS) will be capable of providing the space research community with inexpensive and easy access to space payloads and space data. Furthermore, the DDS is shown to be a natural outgrowth of advances and evolution in both NASA's Space Network and commercial satellite communications. The roadmap and timescale for this evolution is described along with key demonstrations, proof-of-concept models, and required technology development that will support the projected system evolution toward the DDS.

Bruno, Ronald C.; Weinberg, Aaron

1991-01-01

98

Advanced satellite communication system  

NASA Astrophysics Data System (ADS)

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 is of the Convolve - Multiply - Convolve (CMC) type, utilizing off-the-shelf reflective array compressor (RAC) chirp filters. This satellite receiver, if fully developed, was intended to be used as an on-board multichannel communications repeater. The Advanced Communications Receiver consists of four units: (1) CMC processor, (2) single sideband modulator, (3) demodulator, and (4) chirp waveform generator and individual channel processors. The input signal is composed of multiple user transmission frequencies operating independently from remotely located ground terminals. This signal is Fourier transformed by the CMC Processor into a unique time slot for each user frequency. The CMC processor is driven by a waveform generator through a single sideband (SSB) modulator. The output of the coherent demodulator is composed of positive and negative pulses, which are the envelopes of the chirp transform processor output. These pulses correspond to the data symbols. Following the demodulator, a logic circuit reconstructs the pulses into data, which are subsequently differentially decoded to form the transmitted data. The coherent demodulation and detection of BPSK signals derived from a CMC chirp transform processor were experimentally demonstrated and bit error rate (BER) testing was performed. To assess the feasibility of such advanced receiver, the results were compared with the theoretical analysis and plotted for an average BER as a function of signal-to-noise ratio. Another goal of this SBIR program was the development of a commercial product. The commercial product developed was an arbitrary waveform generator. The successful sales have begun with the delivery of the first arbitrary waveform generator.

Staples, Edward J.; Lie, Sen

1992-05-01

99

Advanced satellite communication system  

NASA Technical Reports Server (NTRS)

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 is of the Convolve - Multiply - Convolve (CMC) type, utilizing off-the-shelf reflective array compressor (RAC) chirp filters. This satellite receiver, if fully developed, was intended to be used as an on-board multichannel communications repeater. The Advanced Communications Receiver consists of four units: (1) CMC processor, (2) single sideband modulator, (3) demodulator, and (4) chirp waveform generator and individual channel processors. The input signal is composed of multiple user transmission frequencies operating independently from remotely located ground terminals. This signal is Fourier transformed by the CMC Processor into a unique time slot for each user frequency. The CMC processor is driven by a waveform generator through a single sideband (SSB) modulator. The output of the coherent demodulator is composed of positive and negative pulses, which are the envelopes of the chirp transform processor output. These pulses correspond to the data symbols. Following the demodulator, a logic circuit reconstructs the pulses into data, which are subsequently differentially decoded to form the transmitted data. The coherent demodulation and detection of BPSK signals derived from a CMC chirp transform processor were experimentally demonstrated and bit error rate (BER) testing was performed. To assess the feasibility of such advanced receiver, the results were compared with the theoretical analysis and plotted for an average BER as a function of signal-to-noise ratio. Another goal of this SBIR program was the development of a commercial product. The commercial product developed was an arbitrary waveform generator. The successful sales have begun with the delivery of the first arbitrary waveform generator.

Staples, Edward J.; Lie, Sen

1992-01-01

100

Applications systems verification and transfer project. Volume 3: Operational applications of satellite snow cover observations in California  

NASA Technical Reports Server (NTRS)

Five southern Sierra snowmelt basins and two northern Sierra-Southern Cascade snowmelt basins were used to evaluate the effect on operational water supply forecasting from satellite imagery. Manual photointerpretation techniques were used to obtain SCA and equivalent snow line for the years 1973 to 1979 for the seven test basins using LANDSAT imagery and GOES imagery. The use of SCA was tested operationally in 1977-79. Results indicate the addition of SCA improve the water supply forecasts during the snowmelt phase for these basins where there may be an unusual distribution of snowpack throughout the basin, or where there is a limited amount of real time data available. A high correlation to runoff was obtained when SCA was combined with snow water content data obtained from reporting snow sensors.

Brown, A. J.; Hannaford, J. F.

1981-01-01

101

Odyssey personal communications satellite system  

NASA Technical Reports Server (NTRS)

The spectacular growth of cellular telephone networks has proved the demand for personal communications. Large regions of the world are too sparsely populated to be economically served by terrestrial cellular communications. Since satellites are well suited to this application, TRW filed with the FCC on May 31, 1993 for the Odyssey construction permit. Odyssey will provide high quality wireless communication services worldwide from satellites. These services will include: voice, data, paging, and messaging. Odyssey will be an economical approach to providing communications. A constellation of 12 satellites will be orbited in three, 55 deg. inclined planes at an altitude of 10,354 km to provide continuous coverage of designated regions. Two satellites will be visible anywhere in the world at all times. This dual visibility leads to high line-of-sight elevation angles, minimizing obstructions by terrain, trees and buildings. Each satellite generates a multibeam antenna pattern that divides its coverage area into a set of contiguous cells. The communications system employs spread spectrum CDMA on both the uplinks and downlinks. This signaling method permits band sharing with other systems and applications. Signal processing is accomplished on the ground at the satellite's 'Gateway' stations. The 'bent pipe' transponders accommodates different regional standards, as well as signaling changes over time. The low power Odyssey handset will be cellular compatible. Multipath fade protection is provided in the handset.

Spitzer, Christopher J.

1993-01-01

102

The American mobile satellite system  

NASA Technical Reports Server (NTRS)

During 1989, the American Mobile Satellite Corporation (AMSC) was authorized to construct, launch, and operate satellites to provide mobile satellite services (MSS) to the U.S. and Puerto Rico. The AMSC has undertaken three major development programs to bring a full range of MSS services to the U.S. The first program is the space segment program that will result in the construction and launch of the satellites as well as the construction and installation of the supporting ground telemetry and command system. The second segment will result in the specification, design, development, construction, and installation of the Network Control System necessary for managing communications access to the satellites, and the specification and development of ground equipment for standard circuit switched and packet switched communications services. The third program is the Phase 1 program to provide low speed data services within the U.S. prior to availability of the AMSC satellites and ground segment. Described here are the present status and plans for these three programs as well as an update on related business arrangements and regulatory matters.

Garner, William B.

1990-01-01

103

The American mobile satellite system  

NASA Astrophysics Data System (ADS)

During 1989, the American Mobile Satellite Corporation (AMSC) was authorized to construct, launch, and operate satellites to provide mobile satellite services (MSS) to the U.S. and Puerto Rico. The AMSC has undertaken three major development programs to bring a full range of MSS services to the U.S. The first program is the space segment program that will result in the construction and launch of the satellites as well as the construction and installation of the supporting ground telemetry and command system. The second segment will result in the specification, design, development, construction, and installation of the Network Control System necessary for managing communications access to the satellites, and the specification and development of ground equipment for standard circuit switched and packet switched communications services. The third program is the Phase 1 program to provide low speed data services within the U.S. prior to availability of the AMSC satellites and ground segment. Described here are the present status and plans for these three programs as well as an update on related business arrangements and regulatory matters.

Garner, William B.

104

Ocean observing satellite study: instrument and satellite constellation architecture options  

NASA Technical Reports Server (NTRS)

This paper provides: (1) an overview of the set of active and passive instruments identified by the IPO designed to make the ocean measurements including visible and infrared medium and high resolution imagers, radiometers, altimeters, and synthetic aperture radars and (2) the instrument and satellite constellation architecture options studied, and their ability to meet the set of measurement requirements.

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

2002-01-01

105

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

106

Inferring Land Surface Model Parameters for the Assimilation of Satellite-Based L-Band Brightness Temperature Observations into a Soil Moisture Analysis System  

NASA Technical Reports Server (NTRS)

The Soil Moisture and Ocean Salinity (SMOS) satellite mission provides global measurements of L-band brightness temperatures at horizontal and vertical polarization and a variety of incidence angles that are sensitive to moisture and temperature conditions in the top few centimeters of the soil. These L-band observations can therefore be assimilated into a land surface model to obtain surface and root zone soil moisture estimates. As part of the observation operator, such an assimilation system requires a radiative transfer model (RTM) that converts geophysical fields (including soil moisture and soil temperature) into modeled L-band brightness temperatures. At the global scale, the RTM parameters and the climatological soil moisture conditions are still poorly known. Using look-up tables from the literature to estimate the RTM parameters usually results in modeled L-band brightness temperatures that are strongly biased against the SMOS observations, with biases varying regionally and seasonally. Such biases must be addressed within the land data assimilation system. In this presentation, the estimation of the RTM parameters is discussed for the NASA GEOS-5 land data assimilation system, which is based on the ensemble Kalman filter (EnKF) and the Catchment land surface model. In the GEOS-5 land data assimilation system, soil moisture and brightness temperature biases are addressed in three stages. First, the global soil properties and soil hydraulic parameters that are used in the Catchment model were revised to minimize the bias in the modeled soil moisture, as verified against available in situ soil moisture measurements. Second, key parameters of the "tau-omega" RTM were calibrated prior to data assimilation using an objective function that minimizes the climatological differences between the modeled L-band brightness temperatures and the corresponding SMOS observations. Calibrated parameters include soil roughness parameters, vegetation structure parameters, and the single scattering albedo. After this climatological calibration, the modeling system can provide L-band brightness temperatures with a global mean absolute bias of less than 10K against SMOS observations, across multiple incidence angles and for horizontal and vertical polarization. Third, seasonal and regional variations in the residual biases are addressed by estimating the vegetation optical depth through state augmentation during the assimilation of the L-band brightness temperatures. This strategy, tested here with SMOS data, is part of the baseline approach for the Level 4 Surface and Root Zone Soil Moisture data product from the planned Soil Moisture Active Passive (SMAP) satellite mission.

Reichle, Rolf H.; De Lannoy, Gabrielle J. M.

2012-01-01

107

Use of Earth Observing Satellites for Operational Hazard Support  

NASA Astrophysics Data System (ADS)

The National Oceanic and Atmospheric Administration (NOAA) relies on Earth observing satellite data to carry out its operational mission to monitor, predict, and assess changes in the Earth's atmosphere, land, and oceans. NOAA's National Environmental Satellite, Data, and Information Service (NESDIS) uses satellite data to help lessen the impacts of natural and man-made disasters due to tropical cyclones, flash floods, heavy snowstorms, volcanic ash clouds (for aviation safety), sea ice (for shipping safety), and harmful algal blooms. Communications systems on NOAA satellites are used to support search and rescue and to relay data from data collection platforms to a variety of users. NOAA's Geostationary (GOES) and Polar (POES) Operational Environmental Satellites are used in conjunction with other satellites to support NOAA's operational mission. While NOAA's National Hurricane Center is responsible for predicting tropical cyclones affecting the U.S. mainland, NESDIS continuously monitors the tropics world wide, relaying valuable satellite interpretations of tropical systems strength and position to users throughout the world. Text messages are sent every six hours for tropical cyclones in the Western Pacific, South Pacific, and Indian Oceans. To support the monitoring, prediction, and assessment of flash floods and winter storms, NESDIS sends out text messages alerting U.S. weather forecast offices whenever NOAA satellite imagery indicates the occurrence of heavy rain or snow. NESDIS also produces a 24-hour rainfall composite graphic image covering those areas affected by heavy precipitation. The International Civil Aviation Organization (ICAO) and other aviation concerns recognized the need to keep aviators informed of volcanic hazards. To that end, nine Volcanic Ash Advisory Centers (VAAC's) were created to monitor volcanic ash plumes within their assigned airspace. NESDIS hosts one of the VAAC's. Although the NESDIS VAAC's primary responsibility is the continental U.S., Carribean, and adjacent oceans, it also tracks volcanic eruptions throughout the world. Text messages are produced along with graphic interpretations. This information, along with volcanic ash forecasts produced by NOAA's National Weather Service, is made available to U.S. Government and international agencies concerned with aviation, seismology, and climate analysis. Earth observing satellites help NESDIS to ensure safe navigation of ships through sea ice by measuring the extent, thickness, and age of ice as well as sea surface winds over the polar regions of the globe, coastal areas, and inland waterways. These satellites also help NESDIS to monitor U.S. coastal areas for dangerous algal blooms or other toxic effects to fish and sea mammals as well as monitoring floods and fires. Experimental fire products can help in the monitoring of fires and fire weather, as well as determining fire risk. Experimental soil moisture products support flood and drought monitoring. Flood extent and damage assessment for a variety of hazards can be determined from several satellites at varying spatial resolutions. The Search and Rescue Satellite Aided Tracking (SARSAT) system detects and locates persons in distress on land or water. NOAA satellites relay distress signals from emergency beacons through a network of ground stations to the U.S. Mission Control Center (USMCC). The USMCC processes the data and alerts the appropriate search and rescue authorities. SARSAT is part of the international Cospas-Sarsat Program. NOAA's GOES Data Collection (DCS) and Argos (jointly with the French space agency) POES Data Collection and Locations Systems transmit data collected from remote land and water based platforms and distributes the data to researchers, governmental and environmental organizations worldwide. The GOES DCS system allows near real time and frequent transmissions, e.g. hourly, over the Americas and much of the Atlantic and Eastern Pacific Oceans. ARGOS transmissions are less frequent, but global and provide the location of moving platforms such as animals and d

Wood, H. M.; Lauritson, L.

108

Using the JPL Tropical Cyclone Information System to study the climatology of hurricane precipitation structure from 10 years of passive microwave satellite observations in the Atlantic  

NASA Astrophysics Data System (ADS)

In spite of recent improvements in hurricane track forecast accuracy, currently there are still many unanswered questions about the physical processes that determine hurricane genesis, and evolution. Furthermore, a significant amount of work remains to be done in validating and improving hurricane forecast models. None of this can be accomplished without a comprehensive set of multi-parameter observations that are relevant to both the large-scale and the storm-scale processes in the atmosphere and in the ocean. Despite the significant amount of satellite observations today, they are still underutilized in hurricane research and operations, due to complexity and volume. To facilitate hurricane research, we developed the JPL Tropical Cyclone Information System (TCIS) of multi-instrument satellite observations pertaining to: i) the thermodynamic and microphysical structure of the storms; ii) the air-sea interaction processes; iii) the larger-scale environment as depicted by the SST and the Total Precipitable Water of the environment (Hristova-Veleva et al., 2008, 2011). Our goal was to create a one-stop place to provide the researchers with an extensive set of observed hurricane data, and their graphical representation, organized in an easy way to determine when coincident observations from multiple instruments are available. In this study we use the 10+ years of passive microwave observations of Atlantic hurricanes to create composite structures that are segregated by hurricane category and by intensification rate. The use of composite structures provides a statistically robust framework (e.g. Rogers et al., 2012). We analyze the storm asymmetry as depicted by several factors - brightness temperatures and their derivatives such as a newly-develop Rain Indicator and a new convective/stratiform separation that is based on the value and the spatial variability of this Rain Indicator. The goal is to determine whether the storm morphology (in particular, the storm asymmetry or lack thereof) carries predictive skills regarding the potential for intensification. The presentation will describe the JPL TCIS and the results of our analysis of the passive microwave satellite observations of the Atlantic hurricanes. Refernces: Hristova-Veleva, S. M., C. Ao, Y. Chao, V. Dang, R. Fovell, M. Garay, Z. Haddad, B. Knosp, B. Lambrigtsen, P. P. Li, K. J. Park, W. Poulsen, H. Su, S. Tanelli, D. Vane, Q. A. Vu, J. Willis, D. L. Wu, 2008: "Using the JPL Tropical Cyclone Information System for Research and Applications", AMS 28th Hurricane and Tropical Meteorology Conference, Orlando, FL, 28Apr.-02May 2008 Hristova-Veleva, S. M., A. Chau, Z. Haddad, B. Knosp, B. Lambrigtsen, P. P. Li, E. Rodriguez, T. -. P. Shen, B. Stiles, H. Su, J. Turk, and Q. Vu, 2011: "Impact of microphysical parameterizations on the structure and intensity of simulated hurricanes: Using satellite data to determine the parameterizations that produce most realistic storms", 14th Conference on Mesoscale Processes, 1-4 August 2011, Los Angeles, California Rogers, R., S. Lorsolo, P. Reasor, J. Gamache, F. Marks, 2012: Multiscale Analysis of Tropical Cyclone Kinematic Structure from Airborne Doppler Radar Composites. Mon. Wea. Rev., 140, 77-99.

Hristova-Veleva, Svetla; Haddad, Ziad; Knosp, Brian; Lambrigtsen, Bjorn; Li, P. Peggy; Poulsen, William; Seo, Eun-Kyoung; Shen, Tsae-Pyng; Turk, Francis J.; Vu, Quoc

2013-04-01

109

Satellite Application for Disaster Management Information Systems  

NASA Astrophysics Data System (ADS)

Abstract Satellites are becoming increasingly vital to modern day disaster management activities. Earth observation (EO) satellites provide images at various wavelengths that assist rapid-mapping in all phases of the disaster management cycle: mitigation of potential risks in a given area, preparedness for eventual disasters, immediate response to a disaster event, and the recovery/reconstruction efforts follo wing it. Global navigation satellite systems (GNSS) such as the Global Positioning System (GPS) assist all the phases by providing precise location and navigation data, helping manage land and infrastructures, and aiding rescue crews coordinate their search efforts. Effective disaster management is a complex problem, because it involves many parameters, which are usually not easy to measure and even identify: Analysis of current situation, planning, optimum resource management, coordination, controlling and monitoring current activities and making quick and correct decisions are only some of these parameters, whose complete list is very long. Disaster management information systems (DMIS) assist disaster management to analyse the situation better, make decisions and suggest further actions following the emergency plans. This requires not only fast and thorough processing and optimization abilities, but also real-time data provided to the DMIS. The need of DMIS for disasters real-time data can be satisfied by small satellites data utilization. Small satellites can provide up-to-data, plus a better media to transfer data. This paper suggests a rationale and a framework for utilization of small Satellite data by DMIS. DMIS should be used before, during and after the disasters. Data provided by the Small Satellites are almost crucial in any period of the disasters, because early warning can save lives, and satellite data may help to identify disasters before they occur. The paper also presents when, where and how small satellite data should be used by DMIS.

Okpanachi, George

110

Sensitivity of satellite observations for freshly produced lightning NOx  

NASA Astrophysics Data System (ADS)

In this study, we analyse the sensitivity of nadir viewing satellite observations in the visible range to freshly produced lightning NOx, i.e. for meteorological and (photo-) chemical conditions found in and around cumulonimbus clouds. For the first time, such a study is performed accounting for photo-chemistry, dynamics, and radiative transfer in a consistent way: A one week episode in the TOGA COARE/CEPEX region (Pacific) in December 1992 is simulated with a 3-D cloud resolving chemistry model. The simulated hydrometeor mixing ratios are fed into a Monte Carlo radiative transfer model to calculate box-Air Mass Factors (box-AMFs) for NO2. From these box-AMFs, together with model NOx profiles, slant columns of NO2 (SNO2), i.e. synthetic satellite measurements, are calculated and set in relation to the actual model NOx vertical column (VNOx), yielding the "sensitivity" SNO2/VNOx. From this study, we find a mean sensitivity of 0.46. NOx below the cloud bottom is mostly present as NO2, but shielded from the satellites' view, whereas NOx at the cloud top or above is shifted to NO due to high photolysis and low temperature, and hence not detectable from space. But a significant fraction of the lightning produced NOx in the middle part of the cloud is present as NO2 and has a good visibility from space. Due to the resulting total sensitivity being quite high, nadir viewing satellites provide a valuable additional platform to quantify NOx production by lightning; strong lightning events over "clean" regions should be clearly detectable in satellite observations. Since the observed enhancement of NO2 column densities over mesoscale convective systems are lower than expected for current estimates of NOx production per flash, satellite measurements can in particular constrain the upper bound of lightning NOx production estimates.

Beirle, S.; Salzmann, M.; Lawrence, M. G.; Wagner, T.

2008-10-01

111

Sensitivity of satellite observations for freshly produced lightning NOx  

NASA Astrophysics Data System (ADS)

In this study, we analyse the sensitivity of nadir viewing satellite observations in the visible range to freshly produced lightning NOx. This is a particular challenge due to the complex and highly variable conditions of meteorology, (photo-) chemistry, and radiative transfer in and around cumulonimbus clouds. For the first time, such a study is performed accounting for photo-chemistry, dynamics, and radiative transfer in a consistent way: A one week episode in the TOGA COARE/CEPEX region (Pacific) in December 1992 is simulated with a 3-D cloud resolving chemistry model. The simulated hydrometeor mixing ratios are fed into a Monte Carlo radiative transfer model to calculate box-Air Mass Factors (box-AMFs) for NO2. From these box-AMFs, together with model NOx profiles, slant columns of NO2 (SNO2), i.e. synthetic satellite measurements, are calculated and set in relation to the actual model NOx vertical column (VNOx), yielding the "sensitivity" SNO2/VNOx. From this study, we find a mean sensitivity of 0.46. NOx below the cloud bottom is mostly present as NO2, but shielded from the satellites' view, whereas NOx at the cloud top or above is shifted to NO due to high photolysis and low temperature, and hence not detectable from space. However, a significant fraction of the lightning produced NOx in the middle part of the cloud is present as NO2 and has a good visibility from space. Due to the resulting total sensitivity being quite high, nadir viewing satellites provide a valuable additional platform to quantify NOx production by lightning; strong lightning events over "clean" regions should be clearly detectable in satellite observations. Since the observed enhancement of NO2 column densities over mesoscale convective systems are lower than expected for current estimates of NOx production per flash, satellite measurements can in particular constrain the upper bound of lightning NOx production estimates.

Beirle, S.; Salzmann, M.; Lawrence, M. G.; Wagner, T.

2009-02-01

112

Earth Observing System/Meteorological Satellite (EOS/METSAT). Advanced Microwave Sounding Unit-A (AMSU-A) Contamination Control Plan  

NASA Technical Reports Server (NTRS)

This Contamination Control Plan is submitted in response the Contract Document requirements List (CDRL) 007 under contract NAS5-32314 for the Earth Observing System (EOS) Advanced Microwave Sounding Unit A (AMSU-A). In response to the CDRL instructions, this document defines the level of cleanliness and methods/procedures to be followed to achieve adequate cleanliness/contamination control, and defines the required approach to maintain cleanliness/contamination control through shipping, observatory integration, test, and flight. This plan is also applicable to the Meteorological Satellite (METSAT) except where requirements are identified as EOS-specific. This plan is based on two key factors: a. The EOS/METSAT AMSU-A Instruments are not highly contamination sensitive. b. Potential contamination of other EOS Instruments is a key concern as addressed in Section 9/0 of the Performance Assurance Requirements for EOS/METSAT Integrated Programs AMSU-A Instrument (MR) (NASA Specification S-480-79).

Fay, M.

1998-01-01

113

Satellite observations of temporal terrestrial features  

NASA Technical Reports Server (NTRS)

The application of satellite data to earth resources and environmental studies and the effects of resolution of the photographs and imagery are discussed. The nature of the data acquired by manned space flight and unmanned satellites is described. Specific applications of remotely sensed data for oceanography, hydrology, geography, and geology are examined.

Rabchevsky, G. A.

1972-01-01

114

An Objectively Optimized Earth Observing System  

Microsoft Academic Search

This paper describes one vision for future Earth observing systems. New in this vision is the desire for symbiotic communication to dynamically guide an observation system. An earth observation system which is not just a single satellite acting on its own but a constellation of satellites, and sub-orbital platforms such as unmanned aerial vehicles, and ground observations interacting with computer

David J. Lary; Oleg Aulov; Andrew Rickert

2007-01-01

115

Atmospheric sounding by global navigation satellite system radio occultation: An analysis of the negative refractivity bias using CHAMP observations  

Microsoft Academic Search

Validation studies of current GPS radio occultation experiments using meteorological analyses consistently report on a negative refractivity bias in the lower troposphere. End-to-end simulations including the GPS receiver's signal tracking process suggest that receiver-induced phase deviations contribute to this observed bias. We propose a heuristic retrieval algorithm based on the canonical transform and the sliding spectral technique, which seems less

G. Beyerle; J. Wickert; T. Schmidt; C. Reigber

2004-01-01

116

Use of Earth Observing Satellites for Operational Hazard Support  

Microsoft Academic Search

The National Oceanic and Atmospheric Administration (NOAA) relies on Earth observing satellite data to carry out its operational mission to monitor, predict, and assess changes in the Earth's atmosphere, land, and oceans. NOAA's National Environmental Satellite, Data, and Information Service (NESDIS) uses satellite data to help lessen the impacts of natural and man-made disasters due to tropical cyclones, flash floods,

H. M. Wood; L. Lauritson

2002-01-01

117

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

118

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 worlds satellite operators.

Comet

2012-01-10

119

Operational Applications of Satellite Snowcover Observations  

NASA Technical Reports Server (NTRS)

LANDSAT and NOAA satellites data were used to study snow depth. These snow measurements were used to help forecast runoff and flooding. Many areas of California, Arizona, Colorado, and Wyoming were emphasized.

Rango, A. (editor)

1975-01-01

120

The investigation of tethered satellite system dynamics  

NASA Technical Reports Server (NTRS)

Tethered satellite system (TSS) dynamics were studied. The dynamic response of the TSS during the entire stationkeeping phase for the first electrodynamic mission was investigated. An out of plane swing amplitude and the tether's bowing were observed. The dynamics of the slack tether was studied and computer code, SLACK2, was improved both in capabilities and computational speed. Speed hazard related to tether breakage or plasma contactor failure was examined. Preliminary values of the potential difference after the failure and of the drop of the electric field along the tether axis have been computed. The update of the satellite rotational dynamics model is initiated.

Lorenzini, E.

1984-01-01

121

Description of the AMSC mobile satellite system  

Microsoft Academic Search

The American Mobile Satellite Corporation will provide a full range of mobile satellite services through a mobile satellite system dedicated to mobile use in the United States. This paper provides a summary of the system architecture with descriptions of each of the major system elements. The elements are the space segment, network control system, mobile earth terminals and feeder-link earth

W. B. Garner

1990-01-01

122

The Earth Observing System  

NASA Technical Reports Server (NTRS)

The restructuring of the NASA Earth Observing System (EOS), designed to provide comprehensive long term observations from space of changes occurring on the Earth from natural and human causes in order to have a sound scientific basis for policy decisions on protection of the future, is reported. In response to several factors, the original program approved in the fiscal year 1991 budget was restructured and somewhat reduced in scope. The resulting program uses three different sized launch vehicles to put six different spacecraft in orbit in the first phase, followed by two replacement launches for each of five of the six satellites to maintain a long term observing capability to meet the needs of global climate change research and other science objectives. The EOS system, including the space observatories, the data and information system, and the interdisciplinary global change research effort, are approved and proceeding. Elements of EOS are already in place, such as the research investigations and initial data system capabilities. The flights of precursor satellite and Shuttle missions, the ongoing data analysis, and the evolutionary enhancements to the integrated Earth science data management capabilities are all important building blocks to the full EOS program.

Shaffer, Lisa Robock

1992-01-01

123

Cassini RADAR Icy Satellite Observation Designs and Results  

NASA Astrophysics Data System (ADS)

Although Titan is the primary target of interest for the Cassini RADAR, whenever possible the radar has observed other icy satellites in the Saturn system. Nearing the end of the prime mission, some have been observed several times, and some have been observed with multi-point scans with real-aperture resolution providing some regional data. Most of the observations are tone transmissions that are processed for their Doppler signature. In a few cases, a full chirp is transmitted which offers the possibility of range processing. In a recent Iapetus observation, the range was low enough to permit synthetic aperture imaging of portions of the facing hemisphere. This presentation will discuss the observation designs used, and the status and prospects for processing of the overall data set. The latest results from the Iapetus imaging observation will be shown. In addition to the active echo data obtained, passive radiometer data has also been obtained and the two data sets have the potential to complement the optical and infrared imaging of the icy satellites and shed more light on the structure and composition of their surfaces. This work is supported by the NASA Cassini Program at the Jet Propulsion Laboratory, California Institute of Technology.

West, R. D.; Ostro, S.; Wye, L.; Zebker, H.; Anderson, Y.; Boehmer, R.; Callahan, P.; Gim, Y.; Hamilton, G.; Janssen, M.; Johnson, W. T.; Kelleher, K.; Stiles, B.; Veeramachaneni, C.; Cassini RADAR Team

2007-12-01

124

Satellite laser ranging observation at Shanghai Observatory in 1996  

Microsoft Academic Search

This is a report of satellite laser ranging observations at Shanghai Observatory in 1996. The total 599 passes and 307202 observations for twelve satellites are obtained and given in tables. The range accuracy of single shot is about 3 cm (rms).

Fumin Yang; Chenzhen Wang; Zhongping Zhang; Juping Chen; Chikun Xiao; Xiangdong Gong; Huang Li; Yongping Xu

1998-01-01

125

Recent La Plata basin drought conditions observed by satellite gravimetry  

E-print Network

The Gravity Recovery and Climate Experiment (GRACE) provides quantitative measures of terrestrial water storage (TWS) change. GRACE data show a significant decrease in TWS in the lower (southern) La Plata river basin of South America over the period 2002-2009, consistent with recognized drought conditions in the region. GRACE data reveal a detailed picture of temporal and spatial evolution of this severe drought event, which suggests that the drought began in lower La Plata in around austral spring 2008 and then spread to the entire La Plata basin and peaked in austral fall 2009. During the peak, GRACE data show an average TWS deficit of ~12 cm (equivalent water layer thickness) below the 7 year mean, in a broad region in lower La Plata. GRACE measurements are consistent with accumulated precipitation data from satellite remote sensing and with vegetation index changes derived from Terra satellite observations. The Global Land Data Assimilation System model captures the drought event but underestimates its in...

Chen, J L; Tapley, B D; Longuevergne, L; Yang, Z L; Scanlon, B R; 10.1029/2010JD014689

2010-01-01

126

Satellite Observed Changes in the Arctic  

NASA Technical Reports Server (NTRS)

The Arctic is currently considered an area in transformation. Glaciers have been retreating, permafrost has been diminishing, snow covered areas have been decreasing, and sea ice and ice sheets have been thinning. This paper provides an overview of the unique role that satellite sensors have contributed in the detection of changes in the Arctic and demonstrates that many of the changes are not just local but a pan-Arctic phenomenon. Changes from the upper atmosphere to the surface are discussed and it is apparent that the magnitude of the trends tends to vary from region to region and from season to season. Previous reports of a warming Arctic and a retreating perennial ice cover have also been updated, and results show that changes are ongoing. Feedback effects that can lead to amplification of the signals and the role of satellite data in enhancing global circulation models are also discussed.

Comiso, Josefino C.; Parkinson, Claire L.

2004-01-01

127

Satellite observations of Mt. St. Helens  

Microsoft Academic Search

The major eruption of Mt. St. Helens on May 18, 1980, was recorded by infrared sensors aboard two U.S. Air Force satellites. The extent of the coverage and the completeness of the data base appear to be unique, providing information unavailable from other sources. The eruption was monitored essentially continuously, beginning at 15:32:57 UT, less than 1 min after the

D. J. Rice; D. K. Watson

1981-01-01

128

The observational environment of astronomical satellites and related software subroutines  

NASA Technical Reports Server (NTRS)

Methods are described for calculating significant factors in the observational environment of orbiting astronomical satellites. These factors must be considered in the process of scheduling observations and in data reduction. Subroutines which perform these calculations are described.

West, D. K.; Greville, E. M.

1972-01-01

129

A review of mobile satellite communication systems  

NASA Astrophysics Data System (ADS)

This article describes mobile satellite systems in the planning or development stage such as MSAT, AMSC and Geostar and mobile satellite communication experiments such as PRODAT. Studies on the system such as T-SAT are also reviewed. In addition, Japanese ETS-V and ETS-VI are described. The development of mobile-satellite communication systems is promoted along with those of communication and satellite technologies.

Kondo, Kimio

1990-03-01

130

Time-Variable Gravity: Using Satellite Laser Ranging as a Tool for Observing Long-Term Changes in the Earth System  

Microsoft Academic Search

Temporal variations in the long-wavelength gravity field have been observed using the satellite-laser-ranging (SLR) technique for the past twenty years. The long-term trends in these estimates have generally been consistent with and attributable to post glacial rebound, in addition to a number of secondary contributors. However, since 1998, the Earth's oblateness parameter J2 reversed its decreasing trend and began increasing.

Christopher Co; Jean-Paul Boy; Benjamin Chao

131

Chinese carbon dioxide observation satellite (TanSat) project  

NASA Astrophysics Data System (ADS)

The Chinese carbon dioxide observation satellite project is one of the national high technology research and development programs. It is funded and supported by the ministry of science and technology of the people's republic of China and the Chinese Academy of Sciences. The TanSat - Chinese carbon dioxide observation satellite (Tan-carbon in Chinese) will be launched in 2015, which is going to monitor the carbon dioxide in Sun-Synchronous orbit. Two instruments will be onboard the TanSat, the main instrument is a high resolution grating spectrometer that measure reflected sunlight with the 0.76 ?m O2 A-band and two CO2 bands at 1.61 and 2.06 ?m. The second instrument is the Cloud and Aerosol Imager, which is a wide field of view moderate resolution imaging spectrometer, it include 0.38, 0.67, 0.87, 1.38 and 1.61?m channels in ultraviolet, visible, and near infrared bands, with two polarization channels in 0.67?m. Soundings recorded from main instrument will be used to retrieve the column-averaged CO2 dry air mole fraction (XCO2), while data from Cloud and Aerosol Imager will be used to correct cloud and aerosol interference. A full physical optimal estimation method will be developed as a retrieval method of XCO2, while other sensitive parameters will be inversed at the same time. Ground based observation network system will be established around China to validate satellite CO2 observation results. The final object is to monitor XCO2 from space with precision of 1%. Global CO2 source and sink will be studied by using XCO2 observation results.

Liu, Y.; Yin, Z.; Yang, Z.; Zheng, Y.; Yan, C.; Yang, D.

2011-12-01

132

Studies of the major planet satellite systems  

NASA Technical Reports Server (NTRS)

A summary is presented of the available data on the satellites of the major planets, including the currently most plausible models for several observed phenomena, for the planning of spacecraft missions to these objects. Some of the important questions likely to be solved by flyby and/or orbital missions to the giant planets are detailed, the importance of these studies to our understanding of the solar system as a whole is indicated.

Frey, H.; Lowman, P. D.

1974-01-01

133

Satellite freeze forecast system: Executive summary  

NASA Technical Reports Server (NTRS)

A satellite-based temperature monitoring and prediction system consisting of a computer controlled acquisition, processing, and display system and the ten automated weather stations called by that computer was developed and transferred to the national weather service. This satellite freeze forecasting system (SFFS) acquires satellite data from either one of two sources, surface data from 10 sites, displays the observed data in the form of color-coded thermal maps and in tables of automated weather station temperatures, computes predicted thermal maps when requested and displays such maps either automatically or manually, archives the data acquired, and makes comparisons with historical data. Except for the last function, SFFS handles these tasks in a highly automated fashion if the user so directs. The predicted thermal maps are the result of two models, one a physical energy budget of the soil and atmosphere interface and the other a statistical relationship between the sites at which the physical model predicts temperatures and each of the pixels of the satellite thermal map.

Martsolf, J. D. (principal investigator)

1983-01-01

134

Assessment of Global Annual Atmospheric Energy Balance from Satellite Observations  

NASA Technical Reports Server (NTRS)

Global atmospheric energy balance is one of the fundamental processes for the earth's climate system. This study uses currently available satellite data sets of radiative energy at the top of atmosphere (TOA) and surface and latent and sensible heat over oceans for the year 2000 to assess the global annual energy budget. Over land, surface radiation data are used to constrain assimilated results and to force the radiation, turbulent heat, and heat storage into balance due to a lack of observation-based turbulent heat flux estimations. Global annual means of the TOA net radiation obtained from both direct measurements and calculations are close to zero. The net radiative energy fluxes into the surface and the surface latent heat transported into the atmosphere are about 113 and 86 Watts per square meter, respectively. The estimated atmospheric and surface heat imbalances are about -8 9 Watts per square meter, values that are within the uncertainties of surface radiation and sea surface turbulent flux estimates and likely systematic biases in the analyzed observations. The potential significant additional absorption of solar radiation within the atmosphere suggested by previous studies does not appear to be required to balance the energy budget the spurious heat imbalances in the current data are much smaller (about half) than those obtained previously and debated at about a decade ago. Progress in surface radiation and oceanic turbulent heat flux estimations from satellite measurements significantly reduces the bias errors in the observed global energy budgets of the climate system.

Lin, Bing; Stackhouse, Paul; Minnis, Patrick; Wielicki, Bruce A.; Hu, Yongxiang; Sun, Wenbo; Fan, Tai-Fang (Alice); Hinkelman, Laura

2008-01-01

135

Tethered Satellite System Contingency Investigation Board  

NASA Technical Reports Server (NTRS)

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.

1992-01-01

136

Costing the satellite power system  

NASA Technical Reports Server (NTRS)

The paper presents a methodology for satellite power system costing, places approximate limits on the accuracy possible in cost estimates made at this time, and outlines the use of probabilistic cost information in support of the decision-making process. Reasons for using probabilistic costing or risk analysis procedures instead of standard deterministic costing procedures are considered. Components of cost, costing estimating relationships, grass roots costing, and risk analysis are discussed. Risk analysis using a Monte Carlo simulation model is used to estimate future costs.

Hazelrigg, G. A., Jr.

1978-01-01

137

Interactive analysis of a large aperture Earth observations satellite  

NASA Technical Reports Server (NTRS)

A system level design and analysis has been conducted on an Earth Observation Satellite (EOS) system using the Interactive Design and Evaluation of Advanced Spacecraft (IDEAS) computer-aided design and analysis program. The IDEAS program consists of about 40 user-friendly technical modules and an interactive graphics display. The reflector support system and feed mast of the EOS spacecraft are constructed with box-truss structural concept, a lattice configuration which can be packaged for delivery in a single Shuttle flight and deployed in orbit. The deployed spacecraft consists of a 120-m by 60-m parabolic focal axis. The spacecraft was modeled for structural, thermal, and control systems analysis and structural elements were designed. On-orbit dynamic and thermal loading analyses were conducted; spacecraft weights and developmental and first unit costs were determined.

Wright, R. L.; Deryder, D. D.; Ferebee, M. J., Jr.; Smith, J. C.

1983-01-01

138

Committee on Earth Observation Satellites (CEOS): International Directory Network (IDN)  

NSDL National Science Digital Library

The Committee on Earth Observation Satellites International Directory Network (CEOS/IDN) is an international effort developed to assist researchers in locating information on remotely sensed datasets. It provides free, on-line access to information on worldwide datasets in the Earth sciences: geoscience, satellite remote sensing; and hydrospheric, biospheric, and atmospheric sciences. Users may search datasets by topic, data category, or text search.

139

Small satellite's role in future hyperspectral Earth observation missions  

Microsoft Academic Search

Along with various advanced satellite onboard sensors, an important place in the near future will belong to hyperspectral instruments, considered as suitable for different scientific, commercial and military missions. As was demonstrated over the last decade, hyperspectral Earth observations can be provided by small satellites at considerably lower costs and shorter timescales, even though with some limitations on resolution, spectral

M. Guelman; F. Ortenberg

2009-01-01

140

EUMETSAT Meteorological Satellite conference, Cordoba, 21/9/2010 observation  

E-print Network

conference, Cordoba, 21/9/2010 ADM-Aeolus · ESA Earth Core Explorer Mission · Doppler wind lidar to measure;7EUMETSAT Meteorological Satellite conference, Cordoba, 21/9/2010 Doppler wind lidar from space )(cosEUMETSAT Meteorological Satellite conference, Cordoba, 21/9/2010 ADM-Aeolus wind observation from

Stoffelen, Ad

141

Perl Tools for Automating Satellite Ground Systems  

NASA Technical Reports Server (NTRS)

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 automate the ground system for the Compton Gamma Ray Observatory (CGRO) and for automating some of the elements in the Earth Observing System Data and Operations System (EDOS) ground system at Goddard Space Flight Center (GSFC). CGRO is an older ground system that was forced to automate because of fund cuts. Three 8 hour shifts were cut back to one 8 hour shift, 7 days per week. EDOS supports a new mission called Terra, launched December 1999 that requires distribution and tracking of mission-critical reports throughout the world. Both of these ground systems use Pert scripts to process data and display it on the Internet as well as scripts to coordinate many of the other systems that make these ground systems work as a coherent whole. Another task called Automated Multimodal Trend Analysis System (AMTAS) is looking at technology for isolation and recovery of spacecraft problems. This effort has led to prototypes that seek to evaluate various tools and technology that meet at least some of the AMTAS goals. The tools, experiences, and lessons learned by implementing these systems are described here.

McLean, David; Haar, Therese; McDonald, James

2000-01-01

142

Observations of orbital debris and satellites in Slovak Republic  

NASA Astrophysics Data System (ADS)

There are many accidental optically tracked artificial objects during observations at Astronom-ical and Geophysical Observatory FMPI CU, Modra, Slovak Republic (AGO). Those objects are usually orbital debris or satellites. A tool to identify such a type of objects was necessary to create. Our software is called SatEph and is used to identify tracked artificial objects and to compute their orbital elements. SatEph is based on analytic propagation model SGP4 and TLE data. Program is still under development and in the near future it will be a part of software for automated search telescope for small near Earth asteroids at AGO. We present orbital debris observation simulation for the new optical searching system. Unlike other aster-oids searching systems (Catalina Sky Survey, LINEAR, Spacewatch etc.) our system should be capable to detect small asteroids in close vicinity of the Earth (smaller then Lunar distance) with high angular speed. The limiting magnitude of observable objects is about +16 magnitude and the pixel scale is 4,6 arcsec/px. This allows us to detect man made objects as well. We studied how many satellites and orbital debris with known orbital elements are able to track per given observing night. We also studied frequency detection of tracked object during one night. The searching system field of view will be 4.4 x 4.4 square degrees and the system will search more then 2000 square degrees per night. Exposure time for every single CCD shot is set to 30 seconds. We found out, there is possible to track from 250 to 450 objects (mostly with geosynchronous orbits) per one night in dependence on given day of the year. More then 200 objects have at least 3 astrometric positions per one night, which can be useful for orbit determination process. The tracked objects are mostly satellites and rocket bodies, which have different orbits, from low Earth orbit to geosynchronous Earth orbit. Data of orbital debris astrometric positions will be offered for national space agencies and used for our own orbit determination. Those data could be useful for orbital elements updating of catalogue, or non catalogue artificial objects.

Silha, Jiri; Toth, Juraj

143

Characterizing user requirements for future land observing satellites  

NASA Technical Reports Server (NTRS)

The objective procedure was developed for identifying probable sensor and mission characteristics for an operational satellite land observing system. Requirements were systematically compiled, quantified and scored by type of use, from surveys of federal, state, local and private communities. Incremental percent increases in expected value of data were estimated for critical system improvements. Comparisons with costs permitted selection of a probable sensor system, from a set of 11 options, with the following characteristics: 30 meter spatial resolution in 5 bands and 15 meters in 1 band, spectral bands nominally at Thematic Mapper (TM) bands 1 through 6 positions, and 2 day data turn around for receipt of imagery. Improvements are suggested for both the form of questions and the procedures for analysis of future surveys in order to provide a more quantitatively precise definition of sensor and mission requirements.

Barker, J. L.; Cressy, P. J.; Schnetzler, C. C.; Salomonson, V. V.

1981-01-01

144

Developing a global aeronautical satellite system  

NASA Technical Reports Server (NTRS)

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.

1988-01-01

145

Description of the AMSC mobile satellite system  

NASA Astrophysics Data System (ADS)

The American Mobile Satellite Corporation will provide a full range of mobile satellite services through a mobile satellite system dedicated to mobile use in the United States. This paper provides a summary of the system architecture with descriptions of each of the major system elements. The elements are the space segment, network control system, mobile earth terminals and feeder-link earth stations. The general transmission plan is also described.

Garner, W. B.

146

Tethered satellite system dynamics and control  

NASA Technical Reports Server (NTRS)

The first tethered satellite system, scheduled for launch in May 1991, is reviewed. The system dynamics, dynamics control, and dynamics simulations are discussed. Particular attention is given to in-plane and out-of-plane librations; tether oscillation modes; orbiter and sub-satellite dynamics; deployer control system; the sub-satellite attitude measurement and control system; the Aeritalia Dynamics Model; the Martin-Marietta and NASA-MSFC Dynamics Model; and simulation results.

Musetti, B.; Cibrario, B.; Bussolino, L.; Bodley, C. S.; Flanders, H. A.; Mowery, D. K.; Tomlin, D. D.

1990-01-01

147

STABILITY OF SATELLITES IN CLOSELY PACKED PLANETARY SYSTEMS  

SciTech Connect

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 R{sub H} (where R{sub H} is the Hill radius) as opposed to 0.5 R{sub H} 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 R{sub H} . 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.; Holman, Matthew J. [Institute for Theory and Computation, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 51, Cambridge, MA 02138 (United States)] [Institute for Theory and Computation, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 51, Cambridge, MA 02138 (United States); Deck, Katherine M. [Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States)] [Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Perets, Hagai B., E-mail: matthewjohnpayne@gmail.com [Technion-Israel Institute of Technology, Haifa 32000 (Israel)

2013-10-01

148

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

149

Satellite Observation Highlights of the 2010 Russian Wildfires  

NASA Technical Reports Server (NTRS)

From late-July through mid-August 2010, wildfires raged in western Russia. The resulting thick smoke and biomass burning products were transported over the highly populated Moscow city and surrounding regions, seriously impairing visibility and affecting human health. We demonstrate the uniqueness of the 2010 Russian wildfires by using satellite observations from NASA's Earth Observing System (EOS) platforms. Over Moscow and the region of major fire activity to the southeast, we calculate unprecedented increases in the MODIS fire count record of 178 %, an order of magnitude increase in the MODIS fire radiative power (308%) and OMI absorbing aerosols (255%), and a 58% increase in AIRS total carbon monoxide (CO). The exceptionally high levels of CO are shown to be of comparable strength to the 2006 El Nino wildfires over Indonesia. Both events record CO values exceeding 30x10(exp 7) molec/ square cm.

Witte, Jacquelyn C.; Douglass, Anne R.; Duncan, Bryan N.; daSilva, Arlindo; Torres, Omar

2010-01-01

150

Precise station positions from VLBI observations to satellites: a simulation study  

NASA Astrophysics Data System (ADS)

Very long baseline interferometry (VLBI) tracking of satellites is a topic of increasing interest for the establishment of space ties. This shall strengthen the connection of the various space geodetic techniques that contribute to the International Terrestrial Reference Frame. The concept of observing near-Earth satellites demands research on possible observing strategies. In this paper, we introduce this concept and discuss its possible benefits for improving future realizations of the International Terrestrial Reference System. Using simulated observations, we develop possible observing strategies that allow the determination of radio telescope positions in the satellite system on Earth with accuracies of a few millimeters up to 1-2 cm for weekly station coordinates. This is shown for satellites with orbital heights between 2,000 and 6,000 km, observed by dense regional as well as by global VLBI-networks. The number of observations, as mainly determined by the satellite orbit and the observation interval, is identified as the most critical parameter that affects the expected accuracies. For observations of global positioning system satellites, we propose the combination with classical VLBI to radio sources or a multi-satellite strategy. Both approaches allow station position repeatabilities of a few millimeters for weekly solutions.

Plank, Lucia; Bhm, Johannes; Schuh, Harald

2014-07-01

151

Initialisation using high spatial, temporal and spectral resolution satellite observations  

NASA Astrophysics Data System (ADS)

Recent advances in numerical weather prediction and data assimilation, combined with the availability of high spatial, temporal and spectral resolution satellite observations and burgeoning computer power are leading to significant improvements in our ability to predict weather phenomena at higher and more appropriate resolutions. Here, we describe recent work, illustrating such improvements. High spatial and temporal (at least hourly) resolution data from sequential geostationary multispectral imagery have been used to initialise a high resolution (15km) 4-D variational assimilation (4-D Var.) system to improve tropical cyclone track prediction. The same wind data, sometimes with the addition of TOVS data from NOAA operational satellites, have also been used at higher resolution (5km) to estimate tropical cyclone intensity, demonstrating the importance of very high resolution modelling and data for this enterprise. Finally, we are using very high resolution (1km) 4-D Var. with very high spatial temporal and spectral resolution observations available from experimental advanced sounder instruments such as the High resolution Interferometer Sounder (HIS) and the NPOESS Aircraft Sounder Testbed - Interferometer (NAST - I) to examine the impact after initialisation of the improved delineation of the thermal and moisture fields by these next-generation sounders. This we believe is the first use of advanced sounder data with 4-D Var. and will assist in exploiting such data from the experimental Advanced Infrared Sounder (AIRS), the operational Infrared Atmospheric Sounding Interferometer (IASI), the Geostationary Imaging Fourier Transform Spectrometer (GIFTS) and Cross-track Interferometer Sounder (CrIS) instruments.

Le Marshall, J. F.; Leslie, L. M.; Smith, W. L.

152

Observing tectonic plate motions and deformations from satellite laser ranging  

NASA Technical Reports Server (NTRS)

The scope of geodesy has been greatly affected by the advent of artificial near-earth satellites. The present paper provides a description of the results obtained from the reduction of data collected with the aid of satellite laser ranging. It is pointed out that dynamic reduction of satellite laser ranging (SLR) data provides very precise positions in three dimensions for the laser tracking network. The vertical components of the stations, through the tracking geometry provided by the global network and the accurate knowledge of orbital dynamics, are uniquely related to the center of mass of the earth. Attention is given to the observations, the methodologies for reducing satellite observations to estimate station positions, Lageos-observed tectonic plate motions, an improved temporal resolution of SLR plate motions, and the SLR vertical datum.

Christodoulidis, D. C.; Smith, D. E.; Kolenkiewicz, R.; Klosko, S. M.; Torrence, M. H.

1985-01-01

153

Satellite Significant Wave Height Observations in Coastal and Shelf Seas  

NASA Astrophysics Data System (ADS)

Significant wave height (SWH) observations from the Jason-1 satellite are compared against buoy observations and a spectral wave model for the North Sea/Baltic Sea region. The comparisons are from year 2005 and demon- strate that the satellite SWH observations are very con- sistent, with a mean bias of 0.07 m and a standard devi- ation of 0.36 m when compared with buoys. The error statistics have been derived for the individual buoys and a detailed validation of the wave model is carried out us- ing the satellite observations. It is shown that the 20 Hz std dev of SWH can be used as an indicator of the quality of the observations and that a significant amount of near coastal observations can be obtained even within 10 km from the coast.

Hyer, J. L.; Nielsen, J. W.

2006-07-01

154

Observations of Reflected Ions and Plasma Turbulence for Satellite Potentials Greater Than the Ion Ram Energy  

NASA Technical Reports Server (NTRS)

During the TSS-1R mission, the behavior of the ions flowing from the forward hemisphere of the Tethered Satellite System (TSS) satellite was examined as the potential on the satellite was changed from below to above 5 Volts. The ram energy of the ambient atomic oxygen ions is about 5 eV. For satellite potentials less than 5 V, no ions were observed on the ram side of the satellite. When the satellite potential was raised above 5 V, ions were observed to be flowing from the forward region of the satellite. In the region sampled, the ion flux was a few percent of the ambient with energies of about 5 eV. The temperature of the outflowing ions was observed to be enhanced, relative to the ambient ionosphere, and had a maximum in a plane containing the center of the satellite and normal to the geomagnetic field. The net current to the probe package became much more noisy for satellite potentials above 5 V as compared with satellite potentials below 5 V indicating a more disturbed plasma environment.

Wright, K. H., Jr.; Stone, N. H.; Sorensen, J.; Winningham, J. D.; Gurgiolo, C.

1997-01-01

155

US EPA: A USER AGENCY PERSPECTIVE ON POLAR SATELLITE OBSERVATIONS  

EPA Science Inventory

The Agency uses satellite sensor observations in its work on measuring, monitoring and modeling the environment and human health. It generates observations in collaboration with states, local and regional governments, tribes and others, and is a consumer of observations from a v...

156

Range bias in Borowiec satellite laser ranging system  

Microsoft Academic Search

The paper reports results of determination of the range bias of the satellite laser ranging system in Borowiec (7811). The range bias was determined from the observations of LAGEOS-1 and LAGEOS-2 satellites by Borowiec SLR analysis group. The results were compared with the range bias determination from four analysis centres. Significant differences in range bias, exceeding 2 cm, were found

Tomasz Celka; Stanislaw Schillak

2003-01-01

157

CEOS Committee on Earth Observations Satellites Consolidated Report, 1992  

NASA Technical Reports Server (NTRS)

A concise overview of the committee on Earth Observations Satellites (CEOS) and its Working Groups, covering the history and purpose of the Committee and its accomplishments to date are provided. The report will be updated annually before each Plenary meeting, and as developments in the Working Groups warrant. The committee on Earth Observations Satellites (originally named the International Earth Observations Satellite committee, IEOS) was treated 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. This group recognized the multidisciplinary nature of satellite Earth observations, and the value of coordinating across all proposed missions. Thus, CEOS combined the previously existing groups for coordination on Ocean Remote-Sensing Satellites (CORSS) and coordination on Land Remote-Sensing Satellites (CLRSS), and established a broad framework for coordination across all spaceborne Earth observations missions. The first three LEOS Plenary meetings focused on treating and guiding the Working Groups deemed necessary to carry out the objectives of the CEOS members. After the third meeting, it was agreed that a more active orientation was required by the Plenary, and additional issues were brought before the group at the fourth meeting. At the fifth Plenary, international scientific programs and relevant intergovernmental organizations accepted invitations and participated as affiliate members of CEOS. This enabled progress toward integrating satellite data users' requirements into the CEOS process. Data exchange principles for global change research were also adopted. An interim CEOS Plenary meeting was held in April 1992, in preparation for the United Nations Conference on Environment and Development (UNCED). Brief encapsulations of the Plenary sessions immediately follow the Terms of Reference that govern the activities of CEOS as a whole; Terms of Reference for the individual Working Groups are included as Appendix A. A complete listing of CEOS members is offered as Appendix B.

1992-01-01

158

Index: piggy-back satellite for aurora observation and technology demonstration  

NASA Astrophysics Data System (ADS)

This paper describes outline of the piggy-back satellite "INDEX" for demonstration of advanced satellite technologies as well as for observation of fine structure of aurora. Aurora observation will be carried out by three cameras(MAC) with a monochromatic UV filter. Electron and ion spectrum analyzer (ESA/ISA) will measure the particle phenomena together with the aurora imaging. INDEX satellite will be launched in 2002 by Japanese H2-A. The satellite is mainly controlled by the high-speed, fault-tolerant on-board RICS processor (three-voting system of SH-3). The attitude control is a compact system of three-axis stabilization. Although the size of INDEX is small (50Kg class), several newly-developed technologies are applied to the satellite system, including silicon-on-insulator devices, variable emittance radiator, solar-concentrated paddles, lithium-ion battery, and GPS receiver with all-sky antenna-coverage.

Saito, H.; Masumoto, Y.; Mizuno, T.; Miura, A.; Hashimoto, M.; Ogawa, H.; Tachikawa, S.; Oshima, T.; Choki, A.; Fukuda, H.; Hirahara, M.; Okano, S.

2001-03-01

159

Principles in Remote Sensing: Earth Observations from Satellites  

NSDL National Science Digital Library

In this self-paced, interactive tutorial, learners become familiar with basic concepts related to remote sensing of the Earth by satellites. Geosynchronous Earth Orbit (GEO) and Low Earth Orbit (LEO) satellites, as well as different types of onboard sensors, are examined for their applicability to various real-world data collection and research applications. This resource is part of the tutorial series, Satellite Observations in Science Education, and is the first of three modules in the tutorial, Principles in Remote Sensing. (Note: requires Java plug-in).

160

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.

161

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

162

Integration of mobile satellite and cellular systems  

NASA Technical Reports Server (NTRS)

By integrating the ground based infrastructure component of a mobile satellite system with the infrastructure systems of terrestrial 800 MHz cellular service providers, a seamless network of universal coverage can be established. Users equipped for both cellular and satellite service can take advantage of a number of features made possible by such integration, including seamless handoff and universal roaming. To provide maximum benefit at lowest posible cost, the means by which these systems are integrated must be carefully considered. Mobile satellite hub stations must be configured to efficiently interface with cellular Mobile Telephone Switching Offices (MTSO's), and cost effective mobile units that provide both cellular and satellite capability must be developed.

Drucker, Elliott H.; Estabrook, Polly; Pinck, Deborah; Ekroot, Laura

1993-01-01

163

Satellite system considerations for computer data transfer  

NASA Technical Reports Server (NTRS)

Communications satellites will play a key role in the transmission of computer generated data through nationwide networks. This paper examines critical aspects of satellite system design as they relate to the computer data transfer task. In addition, it discusses the factors influencing the choice of error control technique, modulation scheme, multiple-access mode, and satellite beam configuration based on an evaluation of system requirements for a broad range of application areas including telemetry, terminal dialog, and bulk data transmission.

Cook, W. L.; Kaul, A. K.

1975-01-01

164

Observation of suspended sediments in Mobile Bay, Alabama from satellite  

USGS Publications Warehouse

As part of a comprehensive geologic study of coastal Alabama and Mississippi, the U.S. Geological Survey is investigating coastal sediment transport in Mobile Bay and the adjacent shelf. Satellite imagery from the NOAA AVHRR is being used to provide data on the variability of spatial patterns in the near-surface suspended sediment concentration. This imagery is processed using atmospheric corrections to remove haze and Rayleigh radiance in order to obtain water reflectances; the reflectances are than converted to approximate sediment concentrations using standard relationships between water reflectance and in situ sediment concentrations. A series of images from early 1990 shows rapid changes in sediment concentrations in response to high river flow of the Alabama-Tombigbee river system. During these times, suspended sediment tends to flow out Mobile Bay without mixing into the eastern lobe of the Bay (Bon Secour Bay). The sediment concentration field also appears to be disturbed by the main ship channel. The sediment plume extends more than 60 km offshore after the peak flow event. One wind event in December 1989 was identified as increasing sediment concentration in the Bay. It is not believed that such an event has been previously observed from satellite.

Stumpf, Richard P.

1991-01-01

165

Satellite Observations of Solar Irradiance and Sun-Climate Impacts  

NASA Technical Reports Server (NTRS)

Solar activity is now near its maximum, with events such as the 2001 "Bastille Day Event", a Coronal Mass Ejection which merited a full session at AGUs annual meeting - and two major sunspot groupings earlier this year, with associated variations in TSI (Total Solar Irradiance). We discuss recent satellite measurements of TSI by ACRIM 2 and 3 and Virgo, and new precision observations of TSI and SSI (Solar Spectral Irradiance) expected from the SORCE mission, planned to launch in fall 2002. SSI has been added to TSI as a required EOS and NPOESS measurement because different spectral components provide energy inputs to different components of the climate system - UV into upper atmosphere and ozone, IR into lower atmosphere and clouds, and Visible into the biosphere. Succeeding satellite missions being planned for 2006 and 2010 will continue to monitor both TSI and SSI. We summarize current ideas about the potential impact of solar variability on Earth's climate on time scales from days to decades to centuries.

Cahalan, Robert; Lau, William K. M. (Technical Monitor)

2002-01-01

166

Satellite Observations of Solar Irradiance and Sun-Climate Impacts  

NASA Technical Reports Server (NTRS)

Solar activity is now near its maximum, with events such as the 2001 "Bastille Day Event", a Coronal Mass Ejection which merited a full session at AGO'S annual meeting - and two major sunspot groupings earlier this year, with associated variations in TSI (Total Solar Irradiance). We discuss recent satellite measurements of TSI by ACRIM 2 and 3 And Virgo, and new precision observations of TSI and SSI (Solar Spectral Irradiance) expected from the SORCE mission, planned to launch in fall 2002. SSG has been added to TSI as a required EOS and NPOESS measurement because different spectral components provide energy inputs to different components of the climate system - UV into upper atmosphere and ozone, IR into lower atmosphere and clouds, and Visible into the biosphere. Succeeding satellite missions being planned for 2006 and 2010 will continue to monitor both TSI and SSI. We summarize current ideas about the potential impact of solar variability on Earth's climate on time scales from days to decades to centuries.

Cahalan, R.; Lau, William K. M. (Technical Monitor)

2002-01-01

167

Unusual satellite data: A black hole?. [International Ultraviolet Explorer observations  

NASA Technical Reports Server (NTRS)

Data obtained by the NASA-launched European Space Agency's International Ultraviolet Explorer satellite suggests the possibility of a massive black hole at the center of some globular clusters (star groups) in our galaxy. Six of these clusters, three of them X-ray sources, were closely examined. Onboard short wavelength UV instrumentation penetrated the background denseness of the clusters 15,000 light years away where radiation, probably from a group of 10 to 20 bright blue stars orbiting the core, was observed. The stars may well be orbiting a massive black hole the size of 1,000 solar systems. The existence of the black hole is uncertain. The dynamics of the stars must be studied first to determine how they rotate in relation to the center of the million-star cluster. This may better indicate what provides the necessary gravitational pull that holds them in orbit.

1978-01-01

168

Observations of Uranus' satellites: Bibliography and literature search  

NASA Astrophysics Data System (ADS)

A literature search has yielded more than 10,000 observations of the satellites of Uranus made from 1787 to 1985. The type (photographic, micrometer) and the number of observations are tabulated in 5 year increments and a complete bibliography is provided.

Jacobson, R. A.

1985-10-01

169

Satellite observation of dehydration in the Arctic Polar stratosphere  

E-print Network

Satellite observation of dehydration in the Arctic Polar stratosphere L. L. Pan,1 W. J. Randel,1 H 2002. [1] We report the first space-borne observation of dehydration in the Arctic polar stratosphere between 23 and 26 km. In some cases, the dehydrated air was downwind from mountain wave induced Polar

Pan, Laura

170

Observations of Uranus' satellites: Bibliography and literature search  

NASA Technical Reports Server (NTRS)

A literature search has yielded more than 10,000 observations of the satellites of Uranus made from 1787 to 1985. The type (photographic, micrometer) and the number of observations are tabulated in 5 year increments and a complete bibliography is provided.

Jacobson, R. A.

1985-01-01

171

The Future of Global Navigation Satellite Systems  

Microsoft Academic Search

Global Navigation Satellite Systems (GNSSs) involve satellites, ground stations and user equipment, and are now used across many areas of society. The Global Positioning System (GPS) from the US is the best known, and only currently fully operational GNSS. Russia also operates its own (not fully deployed) GNSS called GLONASS. Fuelling growth in applications during the next decade will be

Chris RIZOS

172

Orbital Stability of the Uranian Satellite System  

Microsoft Academic Search

We have numerically integrated approximately 500 systems of mutually gravitating bodies which were based on subsets of the uranian satellite system. In each run within a set, the satellite masses were initially multiplied by a common mass enhancement factormf. The simulations were terminated at the crossing time,tc, when mutual perturbations excited eccentricities sufficiently large for orbits of a pair of

Martin J. Duncan; Jack J. Lissauer

1997-01-01

173

Observations of Reflected Ions and Plasma Turbulence for Satellite Potentials Greater than the Ion Ram Energy  

NASA Technical Reports Server (NTRS)

During the TSS-1R mission, the behavior of the ions flowing from the forward hemisphere of the Tethered Satellite System (TSS) satellite was examined as the potential of the satellite was changed from below to above 5 V. The ram energy of the ambient atomic oxygen ions is approximately 5 eV. For satellite potentials less than 5 V, no ions were observed on the ram side of the satellite. When the satellite potential was raised greater than 5 V, ions were observed to be flowing from the forward region of the satellite. In the region sampled, the ion flux was a few percent of the ambient with energies of approximately 5 eV. The temperature of the out-flowing ions was observed to be enhanced, relative to the ambient ionosphere. The net current to the probe package became much more noisy for satellite potentials greater than 5 V as compared with satellite potentials less than 5 V, indicating a more disturbed plasma environment.

Wright, K. H., Jr.; Stone, N. H.; Sorensen, J.; Winningham, J. D.; Gurgiolo, C.

1998-01-01

174

Joint Polar Satellite System Common Ground System Overview  

NASA Astrophysics Data System (ADS)

The National Oceanic and Atmospheric Administration (NOAA) and National Aeronautics and Space Administration (NASA) are jointly acquiring the next-generation civilian weather and environmental satellite system: the Joint Polar Satellite System (JPSS). JPSS will contribute the afternoon orbit component and ground processing system of the restructured National Polar-orbiting Operational Environmental Satellite System (NPOESS). As such, JPSS replaces the current Polar-orbiting Operational Environmental Satellites (POES) managed by NOAA and the ground processing component of both Polar-orbiting Operational Environmental Satellites and the Defense Meteorological Satellite Program (DMSP) replacement, previously known as the Defense Weather Satellite System (DWSS), managed by the Department of Defense (DoD). The JPSS satellites will carry a suite of sensors designed to collect meteorological, oceanographic, climatological, and solar-geophysical observations of the earth, atmosphere, and space. The ground processing system for JPSS is known as the JPSS Common Ground System (JPSS CGS), and consists of a Command, Control, and Communications Segment (C3S) and an Interface Data Processing Segment (IDPS). Both segments are developed by Raytheon Intelligence and Information Systems (IIS). The C3S currently flies the Suomi National Polar Partnership (Suomi NPP) satellite and transfers mission data from Suomi NPP and between the ground facilities. The IDPS processes Suomi NPP satellite data to provide Environmental Data Records (EDRs) to NOAA and DoD processing centers operated by the United States government. When the JPSS-1 satellite is launched in early 2017, the responsibilities of the C3S and the IDPS will be expanded to support both Suomi NPP and JPSS-1. The JPSS CGS currently provides data processing for Suomi NPP, generating multiple terabytes per day across over two dozen environmental data products; that workload will be multiplied by two when the JPSS-1 satellite is launched. The CGS also provides raw data processing for GCOM-W1 to support further processing by NOAA. The CGS provides data routing for numerous missions, including Coriolis/Windsat, NASA SCaN (including EOS), DMSP, POES and Metop. Each of these satellites orbits the Earth 14 times a day, downlinking mission data once or twice per orbit at up to hundreds of megabits per second, to support the generation of tens of terabytes per day across hundreds of environmental data products. This presentation will provide an overview of the JPSS CGS ground architecture features, ConOps, key specifications, developmental and operational facilities, present and future supported missions, and recent enhancements for support of the Suomi NPP mission. Key features include redundant mission management, a global commercial communications network for data routing and delivery, high-availability and low-latency data processing, a DoD 8500 compliant security posture, and a modular and extensible architecture. Key recent enhancements include a technology refresh of IDPS hardware to improve supportability and latency performance, incorporation of data routing and processing for the Global Change Observation Mission (GCOM), and significant software upgrades to improve overall system robustness and operability. These enhancements lay the foundation for the future evolution of the CGS to support additional missions.

Jamilkowski, M. L.; Miller, S. W.; Grant, K. D.

2012-12-01

175

Timing of satellite observations for telescope with TV CCD camera  

NASA Astrophysics Data System (ADS)

The time reference system to be used for linking of the satellite position and brightness measurements to the universal time scale UTC are described. These are used in Odessa astronomical observatory. They provides stable error does not exceeding the absolute value of 0.1 ms. The achieved accuracy of the timing allows us to study a very short-term satellite brightness variations and the actual unevenness of its orbital motion.

Dragomiretskoy, V. V.; Koshkin, N. I.; Korobeinikova, E. A.; Melikyants, C. M.; Ryabov, A. V.; Strahova, S. L.; Terpan, S. S.; Shakun, L. S.

2013-12-01

176

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

177

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

178

Drag-free satellite control system technology  

NASA Technical Reports Server (NTRS)

Some of the technology developed in building a drag-free satellite simulator for laboratory use is described. The design decisions made in order to achieve a 10 to the -11th power g perturbation level for the navigation satellite is discussed. The control system development that will make possible drag-free operation of spinning satellites to reduce perturbation levels by averaging is described.

Debra, D. B.

1971-01-01

179

Licensing of future mobile satellite systems  

NASA Technical Reports Server (NTRS)

The regulatory process for licensing mobile satellite systems is complex and can require many years to complete. This process involves frequency allocations, national licensing, and frequency coordination. The regulatory process that resulted in the establishment of the radiodetermination satellite service (RDSS) between 1983 and 1987 is described. In contrast, each of these steps in the licensing of the mobile satellite service (MSS) is taking a significantly longer period of time to complete.

Lepkowski, Ronald J.

1990-01-01

180

Design of the American Mobile Satellite System  

NASA Technical Reports Server (NTRS)

This paper presents an overview of the American Mobile Satellite Corporation (AMSC) Mobile Satellite System (MSS). A summary of the mobile satellite (MSAT) design and overall performance is provided. The design and components of both the forward link and return link transponders are described in detail. The design and operation of a unique hybrid matrix amplifier that offers flexible power distribution is outlined. The conceptual design and performance of three types of land mobile antennas are described.

Kittiver, Charles

1991-01-01

181

Design of the American Mobile Satellite System  

NASA Astrophysics Data System (ADS)

This paper presents an overview of the American Mobile Satellite Corporation (AMSC) Mobile Satellite System (MSS). A summary of the mobile satellite (MSAT) design and overall performance is provided. The design and components of both the forward link and return link transponders are described in detail. The design and operation of a unique hybrid matrix amplifier that offers flexible power distribution is outlined. The conceptual design and performance of three types of land mobile antennas are described.

Kittiver, Charles

1991-09-01

182

Odyssey, an optimized personal communications satellite system  

NASA Astrophysics Data System (ADS)

Personal communications places severe demands on service providers and transmission facilities. Customers are not satisfied with the current levels of service and want improvements. Among the characteristics that users seek are: lower service rates, hand held convenience, acceptable time delays, ubiquitous service, high availability, reliability, and high quality. The space industry is developing commercial space systems for providing mobile communications to personal telephones. Provision of land mobile satellite service is fundamentally different from the fixed satellite service provided by geostationary satellites. In fixed service, the earth based antennas can depend on a clear path from user to satellite. Mobile users in a terrestrial environment commonly encounter blockage due to vegetation, terrain or buildings. Consequently, high elevation angles are of premium value. TRW studied the issues and concluded that a Medium Earth Orbit constellation is the best solution for Personal Communications Satellite Service. TRW has developed Odyssey, which uses twelve satellites in medium altitude orbit to provide personal communications satellite service. The Odyssey communications system projects a multibeam antenna pattern to the Earth. The attitude control system orients the satellites to ensure constant coverage of land mass and coastal areas. Pointing can be reprogrammed by ground control to ensure optimized coverage of the desired service areas. The payload architecture features non-processing, "bent pipe" transponders and matrix amplifiers to ensure dynamic power delivery to high demand areas. Circuit capacity is 3000 circuits per satellite. Each satellite weighs 1917 kg (4226 pounds) at launch and the solar arrays provide 3126 Watts of power. Satellites are launched in pairs on Ariane, Atlas, or other vehicles. Each satellite is placed in a circular orbit at an altitude of 10,354 km. There are three orbit planes inclined at 55 to the equatorial plane. Deployment of the satellites permits phased introduction of service. After only three launches, in which two satellites are launched into each plane, continuous service can be provided to most of the world. After three more launches for a total of 12 satellites, service can be expanded to all populated regions of the Earth with path diversity to most regions. The Odyssey system is superior to both geostationary satellites and low earth orbiting satellites. Odyssey provides many benefits to the end user which are described in the paper. These include: low cost, convenience, high availability, reliability, and acceptable time delay. Odyssey exhibits benefits for telecommunications operators: simple operations, incremental, phased startup, long space segment life-time, high profitability, dynamic flexibility for adjustment and short time to market. Since submission of an FCC application in 1991, TRW has continued to explore ways to further improve the Odyssey approach by expanding coverage to the entire world and reducing the initial investment while maintaining high quality service.

Rusch, Roger J.

183

A Satellite Observation Information Service for Data Assimilation Applications  

NASA Astrophysics Data System (ADS)

Multi-mission Observation Operator (M2O2) team at NASA is developing a streamlined interface mechanism that simplifies the assimilation process of satellite-observations by providing 'assimilation-ready' observation information 'on-demand'. The 'assimilation-ready' observation information is referred to as L2# (L2-sharp) data in contrast to level-2 (L2) data. The 'on-demand' indicates a web-service protocol for L2# data request handling. A L2# data service is developed for each atmospheric component of a mission to apply component-specific quality screening and post processing and deliver mission-generic observation information required for assimilation. The observation information is organized for sampling (time and location), sounding (pressure profile and averaging kernel), and retrieval results (a priori state, estimated state, and error). The M2O2 extensions to GEOS-Chem (version 9.0.1) and GEOS-Chem-Adjoint (version 34) have been employed to assimilate MLS-O3 (2004-2012), TES-O3 (2005-2009), TES-CH4 (2009) and ACOS-XCO2 (2009-2011). The L2# data services for MLS-O3 (2004-current), ACOS-XCO2 (2009-current), and AIRS-CO (2002-current) have been installed at GES DISC for assimilation-community-wide access. We will present the 'lessons learned' in three areas: 1) diversity of level-2 data product organization, 2) observation information formulation and validation, and 3) generalized model-coupling process. The M2O2 research is supported by NASA's Advancing Collaborative Connections for Earth System Science (ACCESS) program.

Lee, M.; Weidner, R. J.; Lynnes, C.; Gerasimov, I. V.

2013-12-01

184

History of telescopic observations of the Martian satellites  

NASA Astrophysics Data System (ADS)

This article intends to review the different studies of the Mars satellites Phobos and Deimos realized by means of ground-based telescopic observations as well in the astrometry and dynamics domain as in the physical one. This study spans the first period of investigations of the Martian satellites since their discovery in 1877 through the astrometry and the spectrometry methods, mainly before the modern period of the space era. It includes also some other observations performed thanks to the Hubble Space Telescope. The different techniques used and the main results obtained for the positionning, the size estimate, the albedo and surface composition are described.

Pascu, D.; Erard, S.; Thuillot, W.; Lainey, V.

2014-11-01

185

Asian Dust Weather Categorization with Satellite and Surface Observations  

NASA Technical Reports Server (NTRS)

This study categorizes various dust weather types by means of satellite remote sensing over central Asia. Airborne dust particles can be identified by satellite remote sensing because of the different optical properties exhibited by coarse and fine particles (i.e. varying particle sizes). If a correlation can be established between the retrieved aerosol optical properties and surface visibility, the intensity of dust weather can be more effectively and consistently discerned using satellite rather than surface observations. In this article, datasets consisting of collocated products from Moderate Resolution Imaging Spectroradiometer Aqua and surface measurements are analysed. The results indicate an exponential relationship between the surface visibility and the satellite-retrieved aerosol optical depth, which is subsequently used to categorize the dust weather. The satellite-derived spatial frequency distributions in the dust weather types are consistent with China s weather station reports during 2003, indicating that dust weather classification using satellite data is highly feasible. Although the period during the springtime from 2004 to 2007 may be not sufficient for statistical significance, our results reveal an increasing tendency in both intensity and frequency of dust weather over central Asia during this time period.

Lin, Tang-Huang; Hsu, N. Christina; Tsay, Si-Chee; Huang, Shih-Jen

2011-01-01

186

Transient response measurements on a satellite system  

NASA Technical Reports Server (NTRS)

A set of instruments designed to detect the occurance of electrical breakdown was flown on a synchronous-orbit satellite. The LeRC sensors were installed on cables inside the vehicle. Accordingly, they respond to signals coupled into the satellite wiring system. The SRI sensors were located on the exterior of the vehicle and detected the RF noise pulses associated with surface breakdowns. The results of the earlier SRI program are being used to design and develop a set of intrumentation suitable for inclusion as a general piggy-back package for the detection of the onset of satellite charging and breakdowns on synchronous orbit satellites.

Nanevicz, J. E.; Adamo, R. C.

1977-01-01

187

The German telecommunications satellite system DFS - Kopernikus  

NASA Astrophysics Data System (ADS)

The purpose, concept, and status of the German telecommunications satellite system DFS-Copernicus are discussed. The principal applications of the system will be nationwide distribution of regional TV programs, provision of a nationwide network for business services, and establishment of point-to-point connections. A general overview of DFS is given, and the space and ground segments are described. The system configuration, transponder frequency plan, satellite and payload control centers, traffic station interfaces, project organization, service transmission characteristics, satellite system characteristics, payload characteristics, earth station specifications, the interfaces to the switching network are shown.

Schmeller, O.

188

The application of China's land observation satellites within the framework of Digital Earth and its key technologies  

Microsoft Academic Search

Digital Earth is an interdisciplinary field involving space technology, information technology, and geoscience. This article introduces the land observation satellite system of China and discusses the requirements for satellite payloads in terms of spatial, temporal, and spectral resolution to establish a Digital Earth. The applications of land satellites under the framework of Digital Earth are introduced from the perspectives of

Wen Xu

2012-01-01

189

Navy satellite communications systems in transition  

NASA Astrophysics Data System (ADS)

Navy SATCOM programs require advanced system engineering, program management, and long range planning to improve satellite and ground system technology. Solutions are being sought to develop Navy transitional issues within the framework of the total Defense MILSATCOM architecture. Several of the Navy SATCOM transition issues are discussed: the current Navy SATCOM baseline, consisting of three GAPFILLER (MARISAT) satellites and a constellation of geosynchronous FLTSATCOM satellites; a Demand Assignment time-division Multiple Access (DAMA) system, which permits a more efficient use of the 25 kHz FLTSAT hard-limiting transponders. A leased satellite (LEASAT) will provide extended UHF SATCOM service at four geosynchronous orbital locations. The navy also plans to increase connectivity, capacity, and AJ protection of Fleet Satellite Communications by introduction of SHF service.

Newell, J. W.

190

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...

191

Global assessment of ocean carbon export by combining satellite observations  

E-print Network

Global assessment of ocean carbon export by combining satellite observations and food-web models D, to drive a food-web model that estimates the production of sinking zooplankton feces and algal aggregates of incident photosynthetically available radiation (PAR) is found. Fixed organic carbon in the euphotic zone

Buesseler, Ken

192

Sensor Web Interoperability Testbed Results Incorporating Earth Observation Satellites  

NASA Technical Reports Server (NTRS)

This paper describes an Earth Observation Sensor Web scenario based on the Open Geospatial Consortium s Sensor Web Enablement and Web Services interoperability standards. The scenario demonstrates the application of standards in describing, discovering, accessing and tasking satellites and groundbased sensor installations in a sequence of analysis activities that deliver information required by decision makers in response to national, regional or local emergencies.

Frye, Stuart; Mandl, Daniel J.; Alameh, Nadine; Bambacus, Myra; Cappelaere, Pat; Falke, Stefan; Derezinski, Linda; Zhao, Piesheng

2007-01-01

193

Tropical Cyclone Movement Forecasts Based on Observations from Satellites.  

National Technical Information Service (NTIS)

A method to predict 24-hr movement of tropical cyclones using consecutive daily satellite views is described. The method is based on the observation that changes in the location of major structural features of the storm are correlated with changes in the ...

R. W. Fett, S. Brand

1974-01-01

194

Telematics and satellites. Part 1: Information systems  

NASA Astrophysics Data System (ADS)

Telematic systems are identified and described. The applications are examined emphasizing the role played by satellite links. The discussion includes file transfer, examples of distributed processor systems, terminal communication, information retrieval systems, office information systems, electronic preparation and publishing of information, electronic systems for transfer of funds, electronic mail systems, record file transfer characteristics, intra-enterprise networks, and inter-enterprise networks.

Burke, W. R.

1980-06-01

195

Stability of Satellites in Closely Packed Planetary Systems  

E-print Network

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 $\\sim 0.4 R_H$ (where $R_H$ is the Hill Radius) as opposed to $\\sim 0.5 R_H$ 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 to 4.5 mutual Hill radii destabilize most satellites orbits only if $a\\sim 0.65 R_H$. 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 cir...

Payne, Matthew J; Holman, Matthew J; Perets, Hagai B

2013-01-01

196

Globally Gridded Satellite (GridSat) Observations for Climate Studies  

NASA Technical Reports Server (NTRS)

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: there is no central archive of geostationary data for all international satellites, full temporal and spatial resolution data are voluminous, and diverse calibration and navigation formats encumber the uniform processing needed for multi-satellite climate studies. The International Satellite Cloud Climatology Project set the stage for overcoming these issues by archiving a subset of the full resolution geostationary data at approx.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 the netCDF format using standards that permit a wide variety of tools and libraries to quickly and easily process the data. 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, Kenneth R.; Ansari, Steve; Bain, Caroline L.; Bourassa, Mark A.; Dickinson, Michael J.; Funk, Chris; Helms, Chip N.; Hennon, Christopher C.; Holmes, Christopher D.; Huffman, George J.; Kossin, James P.; Lee, Hai-Tien; Loew, Alexander; Magnusdottir, Gudrun

2012-01-01

197

Automated surface observing systems  

NSF Publications Database

Title : Automated surface observing systems Type : Antarctic EAM NSF Org: OD / OPP Date : August 19 ... Action Memorandum (Installation of Automated Surface Observing Systems [ASOS}) To: Director, Office ...

198

MPEG-7 Descriptors for Earth Observation Satellite Images  

NASA Astrophysics Data System (ADS)

The amount of digital multimedia information has experienced a spectacular growth during the last years thanks to the advances on digital systems of image, video and audio acquisition. As a response to the need of organising all this information, ISO/IEC has developed a new standard for multimedia content description called MPEG-7. Among other topics, MPEG-7 defines a set of multimedia descriptors that can be automatically generated using signal processing techniques. Earth Observation Satellites generate large quantities of images stored on enormous databases that can take advantage of the new standard. An automatic indexation of these images using MPEG-7 metadata can improve their contents management as well as simplify interaction between independent databases. This paper gives an overall description on MPEG-7 standard focusing on the low-level Visual Descriptors. These descriptors can be grouped into four categories: color, texture, shape and motion. Visual Color Descriptors represent the colour distribution of an image in terms of a specified colour space. Visual Texture Descriptors define the visual pattern of an image according to its homogenities and non-homogenities. Visual Shape Descriptors describe the shape of 2D and 3D objects being, at the same time, invariant to scaling, rotation and translation. Motion Descriptors give the essential characteristics of objects and camera motions. These descriptors can be used individually or in combination to index and retrieve satellite images of the Earth from a database. For example, oceans and glaciars can be discerned based on their Colour Descriptors, also cities and deserts based on the Texture Descriptors, island images can be grouped using the Shape Descriptors, and cyclone trajectories studied and compared using the Motion Descriptors.

Nieto, X. Giro I.; Marques Acosta, F.

199

Magnetic field observations on the Akebono (EXOS-D) satellite  

NASA Astrophysics Data System (ADS)

The Akebono (EXOS-D) satellite carries triaxial fluxgate and search coil magnetometers with sensors mounted on 5- and 3-m masts, respectively. The fluxgate magnetometer has four automatically switchable ranges from + or - 1024 to + or - 65536 nT (full scale), and resolutions commensurate with a 16-bit A/D converter in each range (0.031 to 2 nT). The rate of sampling is 32 vectors/sec. The triaxial search coil magnetometer has a frequency response up to 800 Hz. Signals in the frequency range higher than 100 Hz are used for VLF plasma wave experiments, while signals less than 100 Hz are used for magnetic field experiments. After the 3- and 5-m masts were extended on March 7 and 8, 1989, respectively, both the magnetometers are operating continuously. Intense small-scale field-aligned currents embedded in the large-scale field-aligned current system were always observed at 1-2 Re altitudes in all local time regions. The region 0 currents which flow in the poleward region adjacent to the region 1 currents were also frequently observed. The search coil magnetometer measured ion cyclotron waves at 1-2 Re altitudes near the equator.

Fukunishi, H.; Fujii, R.; Kokubun, S.; Hayashi, K.; Tohyama, T.

200

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

201

GPS-based satellite tracking system for precise positioning  

NASA Technical Reports Server (NTRS)

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 receiver or an on-board GPS beacon. Operation of the system for all but satellite tracking will begin by 1988. The first major satellite application will be a demonstration of decimeter accuracy in determining the altitude of TOPEX in the early 1990's. By then the system is expected to yield long-baseline accuracies of a few centimeters and instantaneous time synchronization to 1 ns.

Yunck, T. P.; Melbourne, W. G.; Thornton, C. L.

1985-01-01

202

DEMETER Satellite Observations of Particle Burst Prior to Chile Earthquake  

E-print Network

The lithosphere activity during seismogenic or occurrence of one earthquake may emit electromagnetic wave which propagate to ionosphere and radiation belt, then induce disturbance of electric and magnetic field and the precipitation of high energy charged particles. This paper, based on the data detected by DEMETER satellite, present the high energy charged particle burst(PB) with 4 to 6 times enhancement over the average value observed about ten days days before Chile earthquake. The obvious particle burst was also observed in the northern hemisphere mirror points conjugate of epicenter and no PB events in different years over the same epicenter region was found. The energy spectra of the PBs are different from the one averaged within the first three months in 2010. At the same time, the disturbance of the VLF electric spectrum in ionosphere over the epicenter detected by the DEMETER satellite are also observed in the same two orbits. Those observations from energetic PB and VLF electric spectrum disturbance...

Zhang, Zhenxia; Shen, Xuhui; Ma, Yuqian; Chen, Huaran; You, Xinzhao; Yuan, Yahong

2010-01-01

203

Satellite observations of transient radio impulses from thunderstorms  

SciTech Connect

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 with ground based lightning location data from the National Lightning Detection Network (NLDN), shows that localized regions within thunderstorms are responsible for the creation of the satellite detected rf signals. These regions are connected with the areas of strong radar returns from the NEXRAD Doppler radar system, indicating that they are from regions of intense convection. The authors will also show data from several storms detected in the extended Caribbean, in which the height profile of the source regions can be determined. Although as a single low earth orbit satellite FORTE cannot provide global coverage of thunderstorm/lightning events, follow-on satellite constellations should be able to provide detailed information on global lightning in near real-time.

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

1999-06-01

204

Whistler-triggered emissions observed by ISIS satellites  

NASA Technical Reports Server (NTRS)

A statistical examination has been conducted of the ducted and nonducted whistler-triggered emissions (WTEs) observed by the ISIS satellites in the 1979-1981 period. Most WTEs are observed with simultaneous lower hybrid resonance in the topside ionosphere. The VLF emissions triggered by ducted whistlers frequently occur at L of 2-3, while those triggered by nonducted whistlers occur in the wider latitudinal regions at L of 2.2-4.3.

Nakamura, Y.; Ondoh, T.

1989-01-01

205

Observing System Forecast Experiments: Approach I  

E-print Network

network of radiosondes, aircraft and satellites (see 2.3.1). Numerical weather prediction (NWP) has was obtained by removing all the satellite observations so that just surface, radiosonde and air- craft data from surface pressure (used to provide a constraint at the surface) and the surface system was obtained

Froude, Lizzie

206

25-Year Ocean Wind Climatology from Satellite Observations  

NASA Astrophysics Data System (ADS)

A consistently processed ocean wind climatology derived from 10 satellite microwave sensors is now available. This array of satellites extends from 1987 to present and includes 6 SSM/I, AMSR-E, WindSat, F17 SSM/IS, and QuikScat. Two of the satellite sensors, WindSat and QuikScat, provide wind direction in addition to wind speed. This ocean wind climatology is the basis for the cross-calibrated, multi-platform (CCMP) wind product. CCMP assimilates these satellite winds along with conventional ship and buoy wind observations using the ECMWF analysis as a background field to produce 6-hour vector wind fields at a 25-km resolution. The satellite wind retrievals from these multi-platforms have been carefully inter-calibrated, and the typical annual, globally averaged differences among the satellites are less than 0.1 m/s. The error (2-sigma) in the resulting decadal wind trends over the 25-years is estimated to be about 0.06 m/s/decade. Observed large-scale regional wind trends can be as large as 0.5 m/s/decade and hence are well above the noise level of estimating trends. We will present an overview of the ocean wind climatology and the methodology used to inter-calibrate the various sensors. Wind timeseries from the various sensors will be inter-compared with each other and with ocean buoys. An analysis of estimated trend error will be presented. Finally, some examples of global wind trends over the last quarter century will be shown.

Wentz, F. J.; Ricciardulli, L.; Smith, D. K.

2012-12-01

207

Time Resolved Atmospheric Carbon Satellite Observations from Geostationary Orbit  

NASA Astrophysics Data System (ADS)

This presentation describes proposed satellite carbon measurements from CHRONOS (Commercially Hosted spectroRadiometer Observations and New Opportunities for Science). The primary goal of this mission is to measure the atmospheric pollutants carbon monoxide (CO) and methane (CH4) from geostationary orbit, with hourly observations of North America at high spatial resolution. Carbon monoxide is produced by combustion processes such as urban activity and wildfires, and serves as a proxy for other combustion pollutants that are not easily measured. Both CO and CH4 are chemical precursors of tropospheric ozone pollution. Methane has diverse anthropogenic sources ranging from fossil fuel production, animal husbandry, agriculture and waste management. The impact of gas exploration in the Western States of the USA and oil extraction from the Canadian tar sands will be particular foci of the mission, as will the poorly-quantified natural CH4 emissions from wetlands and thawing permafrost. In addition to characterizing pollutant sources, improved understanding of the domestic CH4 budget is a priority for policy decisions related to short-lived climate forcers. A primary motivation for targeting CO is its value as a tracer of atmospheric pollution. The CHRONOS measurements will provide insight into local and long-range transport across the North American continent, as well as the processes governing the entrainment and venting of pollution in and out of the planetary boundary layer. As a result of significantly improved characterization of diurnal changes in atmospheric composition, CHRONOS observations will find direct societal applications for air quality regulation and forecasting. We present a quantification of this expected improvement in the prediction of near-surface concentrations when CHRONOS measurements are used in Observation System Simulation Experiments (OSSEs). If CHRONOS and the planned NASA Earth Venture TEMPO (Tropospheric Emissions: Monitoring of Pollution) mission were implemented concurrently, the resulting measurement suite would efficiently and expeditiously serve to address the science goals of the Decadal Survey proposed GEO-CAPE mission.

Edwards, D. P.; Worden, H. M.; Deeter, M. N.; Worden, H. M.

2013-12-01

208

Time Resolved Atmospheric Carbon Satellite Observations from Geostationary Orbit  

NASA Astrophysics Data System (ADS)

This presentation describes proposed satellite carbon measurements from CHRONOS (Commercially Hosted spectroRadiometer Observations and New Opportunities for Science). The primary goal of this mission is to measure the atmospheric pollutants carbon monoxide (CO) and methane (CH4) from geostationary orbit, with hourly observations of North America at high spatial resolution. Carbon monoxide is produced by combustion processes such as urban activity and wildfires, and serves as a proxy for other combustion pollutants that are not easily measured. Both CO and CH4 are chemical precursors of tropospheric ozone pollution. Methane has diverse anthropogenic sources ranging from fossil fuel production, animal husbandry, agriculture and waste management. The impact of gas exploration in the Western States of the USA and oil extraction from the Canadian tar sands will be particular foci of the mission, as will the poorly-quantified natural CH4 emissions from wetlands and thawing permafrost. In addition to characterizing pollutant sources, improved understanding of the domestic CH4 budget is a priority for policy decisions related to short-lived climate forcers. A primary motivation for targeting CO is its value as a tracer of atmospheric pollution. The CHRONOS measurements will provide insight into local and long-range transport across the North American continent, as well as the processes governing the entrainment and venting of pollution in and out of the planetary boundary layer. As a result of significantly improved characterization of diurnal changes in atmospheric composition, CHRONOS observations will find direct societal applications for air quality regulation and forecasting. We present a quantification of this expected improvement in the prediction of near-surface concentrations when CHRONOS measurements are used in Observation System Simulation Experiments (OSSEs). If CHRONOS and the planned NASA Earth Venture TEMPO (Tropospheric Emissions: Monitoring of Pollution) mission were implemented concurrently, the resulting measurement suite would efficiently and expeditiously serve to address the science goals of the Decadal Survey proposed GEO-CAPE mission.

Edwards, David; Worden, Helen

209

Remote Observing with the Keck Telescope Using the ACTS Satellite  

NASA Technical Reports Server (NTRS)

As a technical demonstration project for the NASA Advanced Communications Technology Satellite (ACTS), we have implemented remote observing on the 10-meter Keck II telescope on Mauna Kea in Hawaii from the California Institute of Technology campus in Pasadena. The data connection consists of optical fiber networks in Hawaii and California, connecting the end-points to high data rate (HDR) ACTS satellite antennae at JPL in Pasadena and at the Tripler Army Medical Center in Honolulu. The terrestrial fiber networks run the asynchronous transfer mode (ATM) protocol at DS-3 (45 Mbit/sec) speeds, providing ample bandwidth to enable remote observing with a software environment identical to that used for on-site observing in Hawaii. This experiment has explored the data requirements of remote observing with a modern research telescope and large-format detector arrays. While the maximum burst data rates are lower than those required for many other applications (e.g., HDTV), the network reliability and data integrity requirements are critical. As we show in this report, the former issue particularly may be the greatest challenge for satellite networks for this class of application. We have also experimented with the portability of standard TCP/IP applications to satellite networks, demonstrating the need for alternative TCP congestion algorithms and minimization of bit error rates (BER). Reliability issues aside, we have demonstrated that true remote observing over high-speed networks provides several important advantages over standard observing paradigms. Technical advantages of the high-speed network access include more rapid download of data to a user's home institution and the opportunity for alternative communication facilities between members of an observing team, such as audio- and videoconferencing.

Cohen, Judy; Shopbell, Patrick; Bergman, Larry

1998-01-01

210

Satellite aerosol observations for air quality: matching the scales of observations and applications  

NASA Astrophysics Data System (ADS)

The combination of satellite observations and numerical models of the atmosphere is a powerful tool for air quality studies. Satellite observations of aerosol optical depth and surface observations of particulate matter concentrations provide complementary views of particulate air quality, and methods are rapidly improving for using these observations together with the aid of atmospheric models. Advances in numerical modeling, together with increased computational power, have greatly improved the spatial resolution of atmospheric models. Air quality scientists have seized on these improvements, recognizing that important variation in pollution transport and air quality conditions can occur at very fine scales. But the scale and coverage of satellite resolutions make them very useful for some specific applications and less useful for others. The raw satellite observations used to retrieve properties of atmospheric aerosols have spatial resolution on the order of hundreds of meters, still finer than most numerical atmospheric models used for air quality. However, current aerosol retrievals require averaging over broader areas to achieve an acceptable signal-to-noise ratio, and steps taken to reduce uncertainty act to reduce the effective resolution of aerosol observations from satellite. This creates a complicated situation where the processing of the satellite data must balance observation accuracy and precision with the need to observe features at the scale appropriate to the problem. The Naval Research Laboratory has developed post-processors for satellite aerosol data that yield products suitable for initialization or validation of aerosol transport models; these post-processors are capable of generating output at a range of spatial resolutions. In this study, these products are used to examine the interaction between spatial averaging and observation uncertainty, and discuss how these tradeoffs affect specific air quality applications related to source characterization and exposure studies. This presentation concludes with a discussion of methods for extracting the optimal information content from the satellite observations for air quality studies at a range of spatial scales.

Hyer, E. J.; Reid, J. S.; Zhang, J.; Curtis, C. A.; Sessions, W. R.; Westphal, D. L.

2012-12-01

211

Satellite voice broadcast. Volume 2: System study  

NASA Technical Reports Server (NTRS)

The Technical Volume of the Satellite Broadcast System Study is presented. Designs are synthesized for direct sound broadcast satellite systems for HF-, VHF-, L-, and Ku-bands. Methods are developed and used to predict satellite weight, volume, and RF performance for the various concepts considered. Cost and schedule risk assessments are performed to predict time and cost required to implement selected concepts. Technology assessments and tradeoffs are made to identify critical enabling technologies that require development to bring technical risk to acceptable levels for full scale development.

Bachtell, E. E.; Bettadapur, S. S.; Coyner, J. V.; Farrell, C. E.

1985-01-01

212

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

213

Assessment of global annual atmospheric energy balance from satellite observations  

Microsoft Academic Search

Global atmospheric energy balance is one of the fundamental processes for the earth's climate system. This study uses currently available satellite data sets of radiative energy at the top of atmosphere (TOA) and surface as well as latent and sensible heat over the oceans for the year 2000 to assess the global annual energy budget. Over land, surface radiation data

Bing Lin; Paul W. Stackhouse; Patrick Minnis; Bruce A. Wielicki; Yongxiang Hu; Wenbo Sun; Tai-Fang Fan; Laura M. Hinkelman

2008-01-01

214

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

215

Principle characteristics of the National Earth Observation Satellite. Project SPOT  

NASA Technical Reports Server (NTRS)

A recent meeting of the Economic and Social Committee examined the programs and means currently being implemented by France in the field in the field of space research and industry which could bring about fast results. This was prompted by man's desire to insure rational resource management of his planet and by man's awareness of the definite contribution that space observation can make to this field of research. Through discussion, the Economic and Social Committee has approved the plan for creating an earth observation satellite. A detailed discussion of the principle characteristics of this earth observation satellite include the objectives, the orbit, characteristics and operations of the platform, maintenance, attitude measurement, the power available and many other characteristics.

Cazenave, M.

1977-01-01

216

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

217

Satellite antenna management system and method  

NASA Technical Reports Server (NTRS)

The antenna management system and method allow a satellite to communicate with a ground station either directly or by an intermediary of a second satellite, thus permitting communication even when the satellite is not within range of the ground station. The system and method employ five major software components, which are the control and initialization module, the command and telemetry handler module, the contact schedule processor module, the contact state machining module, and the telemetry state machine module. The control and initialization module initializes the system and operates the main control cycle, in which the other modules are called. The command and telemetry handler module handles communication to and from the ground station. The contact scheduler processor module handles the contact entry schedules to allow scheduling of contacts with the second satellite. The contact and telemetry state machine modules handle the various states of the satellite in beginning, maintaining and ending contact with the second satellite and in beginning, maintaining and ending communication with the satellite.

Leath, Timothy T (Inventor); Azzolini, John D (Inventor)

1999-01-01

218

A system design for laser time synchronization via geodetic satellite Ajisai  

Microsoft Academic Search

A laser time synchronization system based on a satellite laser ranging system developed in 1990 is described. The target satellite is the Japanese geodetic satellite Ajisai, which is equipped with corner cubes and mirrors. Feasibility of the experiment is studied including the time transfer equation, the observation system, the link budget, and distribution of reflected beam. Simulation study indicates that

Hiroo Kunimori; Fujinobu Takahashi; Atsushi Yamamoto

1992-01-01

219

Extreme ultraviolet explorer satellite observation of Jupiter's Io plasma torus  

NASA Technical Reports Server (NTRS)

We present the first Extreme Ultraviolet Explorer (EUVE) satellite observation of the Jupiter system, obtained during the 2 day period 1993 March 30 through April 1, which shows a rich emission-line spectrum from the Io plasma torus spanning wavelengths 370 to 735 A. The emission features correspond primarily to known multiplets of oxygen and sulfur ions, but a blended feature near 372 A is a plausible Na II transition. The summed detected energy flux of (7.2 +/- 0.2) x 10(exp -11) ergs/sq cm(s) corresponds to a radiated power of approximately equal to 4 x 10(exp 11) W in this spectral range. All ansa emissions show a distinct dawn-dusk brightness asymmetry and the measured dusk/dawn ratio of the bright S III lambda-680 feature is 2.3 +/- 0.3, significantly larger than the ratio measured by the Voyager spacecraft ultraviolet (UV) instruments. A preliminary estimate of ion partitioning indicates that the oxygen/sulfur ion ratio is approximately equal to 2, compared to the value approximately equal to 1.3 measured by Voyager, and that (Na(+))/(e) greater than 0.01.

Hall, D. T; Gladstone, G. R.; Moos, H. W.; Bagenal, F.; Clarke, J. T.; Feldman, P. D.; Mcgrath, M. A.; Schneider, N. M.; Shemansky, D. E.; Strobel, D. F.

1994-01-01

220

NASA Perspectives on Earth Observations from Satellite or 50 Years of Meteorological Satellite Experiments-The NASA Perspective  

NASA Technical Reports Server (NTRS)

The NASA was established in 1959. From those very eady days to the present NASA has been intimately involved with NOAA and the scientific community in the development and operation of satellite and sensor experiments. The early efforts included experiments on the TIROS and geostationary Applications Technology Satellites (ATS) series. In the latter case the spin-scan cameras conceived by Verner Suomi, along with the TIROS cameras, opened new vistas at what could be done in meteorological studies with the daily, nearly global, synoptic views from space-borne sensors As the years passed and the Nimbus series of satellites came into being in the 1960's, more quantitative observations with longer-lifetime, increasingly capable, better calibrated instruments came into being. NASA, in collaboration with and in support of NOAA, implemented operational systems that we now know as the Polar Operational Environmental Satellite (POES) series and the Geostationary Operational Environmental Satellite (GOES) series that provided dependable, continuous, dedicated satellite observations for use by the weather and atmospheric science communities. Through the 1970's, 1980's, and 1990's improved, well-calibrated instruments with more spectral bands extending into the thermal and the microwave portions of the electromagnetic spectrum were provided to obtain accurate soundings of the atmosphere, atmospheric chemistry constituents such as ozone, global sea surface temperature, snow and ice extent, vegetation dynamics, etc. In the 1990's and up to the present the NASA/Earth Observing System (EOS) has been developed, implemented, and operated over many years to provide a very comprehensive suite of observations of the atmosphere, as well as land and ocean parameters. The future looks bright wherein the development of new systems, broadly described by the National Academy of Science Decadal Study, is now underway. NASA, along with collaborations with NOAA, other agencies, and the scientific and applications communities looks forward to achieving in the years to come goals possible with the global information provided by satellites and continuously improved with technology development, joint data assimilation efforts, and attendant research studies.

Einaudi, Franco

2010-01-01

221

Recent developments with the Soviet Union's VHF satellite navigation system  

Microsoft Academic Search

A description of the Soviet Union's VHF satellite navigation system is presented. The system utilizes constellations of satellites and position-fixing is achieved by low-orbiting satellites in near-polar orbit. The military satellites have orbital spacing intervals of 3 deg with satellite identification numbers 1-9 and civilian satellites have a 45 deg with identification numbers from 11-14. The satellite position data transmitted

P. Daly; G. E. Perry

1986-01-01

222

Development of an ice crystal scattering database for the global change observation mission/second generation global imager satellite mission: investigating the refractive index grid system and potential retrieval error.  

PubMed

Computing time and retrieval error of the effective particle radius are important considerations when developing an ice crystal scattering database to be used in radiative transfer simulation and satellite remote sensing retrieval. Therefore, the light scattering database should be optimized based on the specifications of the satellite sensor. In this study, the grid system of the complex refractive index in the 1.6 ?m (SW3) channel of the Global Change Observation Mission/Second Generation Global Imager satellite sensor is investigated for optimizing the ice crystal scattering database. This grid system is separated into twelve patterns according to the step size of the real and imaginary parts of the refractive index. Specifically, the LIght Scattering solver Applicable to particles of arbitrary Shape/Geometrical-Optics Approximation technique is used to simulate the scattering of light by randomly oriented large hexagonal ice crystals. The difference of radiance with different step size of the refractive index is calculated from the developed light scattering database using the radiative transfer (R-STAR) solver. The results indicated that the step size of the real part is a significant factor in difference of radiance. PMID:22945165

Letu, Husi; Nakajima, Takashi Y; Matsui, Takashi N

2012-09-01

223

A land mobile satellite data system  

NASA Technical Reports Server (NTRS)

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.

1990-01-01

224

Observations of RR Lyrae with the ANS satellite  

NASA Technical Reports Server (NTRS)

Photometric observations of RR Lyr in the ultraviolet have been obtained using the Astronomical Netherlands Satellite. The observations are compared with theoretical light curves calculated using synthetic spectra and angular diameters determined as a function of phase for RR Lyr by Manduca et al. from photometry at longer wavelengths. A good agreement is found. A bump in the observed light curves in the phase range 0.6 to 0.8 supports the existence of a shock as predicted by Hutchinson, Hill, and Lillie.

Bonnell, J.; Wu, C.-C.; Bell, R. A.; Hutchinson, J. L.

1982-01-01

225

Ground-based observations coordinated with Viking satellite measurements  

NASA Astrophysics Data System (ADS)

Results are presented from a program of observations from stations in northern Scandinavia coordinated with observations made with the Swedish satellite Viking. The observations are used to study substorm expansion, focusing on the end of a substorm and the associated decay of a westward-travelling surge. The ionospheric conductivities, electric fields, and neutral winds associated with substorm auroras are examined, using Eiscat measuremnets. It is found that the conductivities and electric fields associated with westward-travelling surges are incorrectly represented by existing models.

Opgenoorth, H. J.; Kirkwood, Sheila

226

Large Scale Surface Radiation Budget from Satellite Observation  

NASA Technical Reports Server (NTRS)

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.

1995-01-01

227

The Alignment between Satellites and Central Galaxies: Theory vs. Observations  

E-print Network

Recent studies have shown that the distribution of satellite galaxies is preferentially aligned with the major axis of their central galaxy. The strength of this alignment has been found to depend strongly on the colours of the satellite and central galaxies, and only weakly on the mass of the halo in which the galaxies reside. In this paper we study whether these alignment signals, and their dependence on galaxy and halo properties, can be reproduced in a hierarchical structure formation model of a $\\Lambda$CDM concordance cosmology. To that extent we use a large $N$-body simulation which we populate with galaxies following a semi-analytical model for galaxy formation. We find that if the orientation of the central galaxy is perfectly aligned with that of its dark matter halo, then the predicted central-satellite alignment signal is much stronger than observed. If, however, the minor axis of a central galaxy is perfectly aligned with the angular momentum vector of its dark matter halo, we can accurately reproduce the observed alignment strength as function of halo mass and galaxy color. Although this suggests that the orientation of central galaxies is governed by the angular momentum of their dark matter haloes, we emphasize that any other scenario in which the minor axes of central galaxy and halo are misaligned by $\\sim 40^{\\circ}$ (on average) will match the data equally well. Finally, we show that dependence of the alignment strength on the color of the central galaxy is most likely an artefact due to interlopers in the group catalogue. The dependence on the color of the satellite galaxies, on the other hand, is real and owes to the fact that red satellites are associated with subhaloes that were more massive at their time of accretion.

X. Kang; Frank C. van den Bosch; Xiaohu Yang; Shude Mao; H. J. Mo; Cheng Li; Y. P. Jing

2007-01-05

228

The Ellipso (TM) mobile satellite system  

NASA Technical Reports Server (NTRS)

The Ellipso(trademark) Mobile Satellite System is conceived to extend telecommunication services throughout the world to users that are not well, or not at all served by existing mobile or fixed telephone systems. Unlike cellular telephones, Ellipso(trademark) offers fully nationwide service to every served country, thereby providing service to users located anywhere within the national boundaries, no matter how isolated or remote. With Ellipso(trademark), a user in the middle of a wilderness area will have the same mobile telecommunications service as a user in a major metropolitan area. Ellipso(trademark) uses medium earth orbiting (MEO) satellites and an efficient system design to reach its subscribers directly and at a price that is competitive with terrestrial telephone services. The subscriber only requires a clear view of a serving satellite to achieve a connection and to connect to anyone else served by the national telecommunications system. Subscribers within view of two or more satellites will benefit from Ellipso's(trademark) unique satellite diversity processing, using all available satellites simultaneously to optimize circuit quality.

Castiel, David; Draim, John E.

1995-01-01

229

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

230

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-Franois

2009-07-01

231

SOFT project: a new forecasting system based on satellite data  

NASA Astrophysics Data System (ADS)

The aim of the SOFT project is to develop a new ocean forecasting system by using a combination of satellite dat, evolutionary programming and numerical ocean models. To achieve this objective two steps are proved: (1) to obtain an accurate ocean forecasting system using genetic algorithms based on satellite data; and (2) to integrate the above new system into existing deterministic numerical models. Evolutionary programming will be employed to build 'intelligent' systems that, learning form the past ocean variability and considering the present ocean state, will be able to infer near future ocean conditions. Validation of the forecast skill will be carried out by comparing the forecasts fields with satellite and in situ observations. Validation with satellite observations will provide the expected errors in the forecasting system. Validation with in situ data will indicate the capabilities of the satellite based forecast information to improve the performance of the numerical ocean models. This later validation will be accomplished considering in situ measurements in a specific oceanographic area at two different periods of time. The first set of observations will be employed to feed the hybrid systems while the second set will be used to validate the hybrid and traditional numerical model results.

Pascual, Ananda; Orfila, A.; Alvarez, Alberto; Hernandez, E.; Gomis, D.; Barth, Alexander; Tintore, Joaquim

2002-01-01

232

A Metric to Evaluate Mobile Satellite Systems  

NASA Technical Reports Server (NTRS)

The concept of a "cost per billable minute" methodology to analyze mobile satellite systems is reviewed. Certain assumptions, notably those about the marketplace and regulatory policies, may need to be revisited. Fading and power control assumptions need to be tested. Overall, the metric would seem to have value in the design phase of a system and for comparisons between and among alternative systems.

Young, Elizabeth L.

1997-01-01

233

Critical areas: Satellite power systems concepts  

NASA Technical Reports Server (NTRS)

Critical Areas are defined and discussed in the various areas pertinent to satellite power systems. The presentation is grouped into five areas (General, Space Systems, Solar Energy Conversion, Microwave Systems, and Environment/Ecology) with a sixth area (Power Relay) considered separately in an appendix. Areas for Future Consideration as critical areas are discussed in a second appendix.

1975-01-01

234

Satellite power system salvage and disposal alternatives  

NASA Technical Reports Server (NTRS)

A wide range of salvage options for the SPS satellite, ranging from use in and beyond geosynchronous orbit to use in low Earth orbit in return and use on Earth are presented. The satellite can be used intact to provide power for various purposes, it can be cannibalized or it can be melted down to supply materials for space or ground based products. The use of SPS beyond its nominal lifetime provides value that can be deducted from the SPS capital investment cost. The present value of the salvage value of the SPS satellites, referenced to the system initial operation data, is on the order of five to ten percent of its on-orbit capital cost. (Given a 30 year satellite lifetime and a four percent discount rate, the theoretical maximum salvage value is 30.8 percent of the capital cost.) The SPS demonstration satellite is available some 30 years earlier than the first full scale SPS satellite and has a salvage value on the order of 80 percent of its on-orbit capital cost. In the event that it becomes desirable to dispose of either the demonstration of full scale SPS satellite, a number of disposal options is presented for which intact disposal costs are less than one percent of capital costs.

1980-01-01

235

Sensitivity of satellite microwave and infrared observations to soil moisture at a global scale: Relationship of satellite observations to in situ soil moisture measurements  

Microsoft Academic Search

This study presents a systematic and integrated analysis of the sensitivity of the available satellite observations to in situ soil moisture measurements. Although none of these satellites is optimized for land surface characterization, before the launches of the SMOS- and HYDROS-dedicated missions they are the only potential sources of global soil moisture measurements. The satellite observations include passive microwave emissivities,

Catherine Prigent; Filipe Aires; William B. Rossow; Alan Robock

2005-01-01

236

Odyssey, an optimized personal communications satellite system  

NASA Astrophysics Data System (ADS)

Personal communications places severe demands on service providers and transmission facilities. Customers are not satisfied with the current levels of service and want improvements. Among the characteristics that users seek are: lower service rates, hand held convenience, acceptable time delays, ubiquitous service, high availability, reliability, and high quality. The space industry in developing commercial space systems for providing mobile communications to personal telephones. Provision of land mobile satellite service is fundamentally different from the fixed satellite service provided by geostationary satellites. In fixed service, the earth based antennas can depend on a clear path from user to satellite. Mobile users in a terrestrial environment commonly encounter blockage due to vegetation, terrain or buildings. Consequently, high elevation angles are of premium value. TRW studied the issues and concluded that a Medium Earth Orbit constellation is the best solution for Personal Communications Satellite Service. TRW has developed Odyssey, which uses twelve satellites in medium altitude orbit to provide personal communications satellite service. The Odyssey communications system projects a multibeam antenna pattern to the Earth. The attitude control system orients the satellites to ensure constant coverage of land mass and coastal areas. Pointing can be reprogrammed by ground control to ensure optimized coverage of the desired service areas. The payload architecture features non-processing, 'bent pipe' transponders and matrix amplifiers to ensure dynamic power delivery to high demand areas. Circuit capacity is 3000 circuits per satellite. Each satellite weighs 1917 kg (4226 pounds) at launch and the solar arrays provide 3126 watts of power. Satellites are launched in pairs on Ariane, Atlas, or other vehicles. Each satellite is placed in a circular orbit at an altitude of 10,354 km. satellites permits phased introduction of service. After only three launches, in which two satellites are launched into each plane, continuous service can be provided to most of the world. After three more launches for a total of 12 satellites, service can be expanded to all populated regions of the Earth with path diversity to most regions. *The Odyssey system is superior to both geostationary satellites and low earth orbiting satellites. -Odyssey provides many benefits to the end user which are described in the paper. These include: low cost, convenience, high availability, reliability, and acceptable time delay. Odyssey exhibits benefits for telecommunications operators: simple operations, incremental, phased startup, long space segment life-time, high profitability, dynamic flexibility for adjustment and short time to market. %Since submission of an FCC application in 1991, TRW has continued to explore ways to further improve the Odyssey approach by expanding coverage to the entire world and reducing the initial investment while maintaining high quality service.

Rusch, Roger J.

237

Consistent Satellite and Ground Based Observations and Model Simulations of Tides - CAWSES Global Tidal Campaign Results  

NASA Astrophysics Data System (ADS)

A persistent issue in the study of atmospheric tides has been differences in tidal signatures deduced from different observing systems and models. Recent analyses during the Second CAWSES Global Tidal Campaign Workshop show consistency between satellite observations (primarily from TIMED), ground based radars, lidar wind measurements and model analyses (likely) for the first time. This agreement required suitable reconstruction of components from the satellite and model analyses at the location of the ground based station. In this paper, we describe the campaigns and observations, summarize the analysis process and illustrate the extent to which tidal signatures from the various data types agree.

Ward, W. E.; Goncharenko, L.; Oberheide, J.; Nakamura, T.; Hoffmann, P.; Chang, L.; Du, J.; Greiger, N.; Haefele, A.; Wang, D.; Shei, C.; Yuan, T.

2007-12-01

238

Satellite Laser Ranging Observations of the TRF Origin  

NASA Astrophysics Data System (ADS)

The origin of the Terrestrial Reference System (TRS) is realized through the adopted coordinates of its defining set of positions and velocities at epoch, constituting the conventional Terrestrial Reference Frame (TRF). Since over two decades now, these coordinates are determined through space geodetic techniques, in terms of absolute or relative positions of the sites and their linear and episodic motions. The continuous redistribution of mass within the Earth system causes concomitant changes in the Stokes' coefficients describing the instantaneous terrestrial gravity field, including its longest wavelength components. Seasonal changes in these coefficients have been closely correlated with mass transfer in the atmosphere, hydrosphere and the oceans. The new gravity-mapping missions, CHAMP and GRACE, and to a lesser extent the future mission GOCE, address these temporal changes from the gravimetric point of view. For the very low degree and order terms, there is also a geometric effect that manifests itself in ways that affect the origin and orientation relationship between the instantaneous and the mean reference frame. Satellite Laser Ranging (SLR) data, especially that from LAGEOS 1 and 2, contributed the most accurate observations of this effect yet, demonstrating millimeter level accuracy for weekly averages. Other techniques, like GPS and DORIS, have also contributed and continue to improve their results with better modeling and more uniformly distributed (spatially and temporally) tracking data. We will present the results from the latest analysis of over a decade of LAGEOS 1 and 2 data, discuss their accuracy and compare them to results from other techniques. Finally, we will look into potential improvements in the future, which will likely lead us to even finer resolution and higher accuracy through the constructive combination of the individual time series.

Pavlis, E. C.

2003-12-01

239

Earth Observing System: Global Observations to Study the Earth's Environment  

NASA Technical Reports Server (NTRS)

The Earth Observing System (EOS) is a space-based observing system comprised of a series of satellite sensors by which scientists can monitor the Earth, a Data and Information System (EOSDIS) enabling researchers worldwide to access the satellite data, and an interdisciplinary science research program to interpret the satellite data. During the last couple of years, four EOS science missions were launched, representing observations of (i) total solar irradiance, (ii) Earth radiation budget, (iii) land cover & land use change, (iv) ocean processes (vector wind, sea surface temperature, and ocean color), (v) atmospheric processes (aerosol and cloud properties, water vapor, and temperature and moisture profiles), and (vi) tropospheric chemistry. In succeeding years many more satellites will be launched that will contribute immeasurably to our understanding of the Earth's environment. In this presentation I will describe how scientists are using NASA's Earth science data to examine land use and natural hazards, environmental air quality, including: dust storms over the worlds deserts, cloud and radiation properties, sea surface temperature, and winds over the ocean, with a special emphasis on satellite observations available for studying the southern African environment.

King, Michael D.

2003-01-01

240

Land-mobile satellite communication system  

NASA Technical Reports Server (NTRS)

A satellite communications system includes an orbiting communications satellite for relaying communications to and from a plurality of ground stations, and a network management center for making connections via the satellite between the ground stations in response to connection requests received via the satellite from the ground stations, the network management center being configured to provide both open-end service and closed-end service. The network management center of one embodiment is configured to provides both types of service according to a predefined channel access protocol that enables the ground stations to request the type of service desired. The channel access protocol may be configured to adaptively allocate channels to open-end service and closed-end service according to changes in the traffic pattern and include a free-access tree algorithm that coordinates collision resolution among the ground stations.

Yan, Tsun-Yee (Inventor); Rafferty, William (Inventor); Dessouky, Khaled I. (Inventor); Wang, Charles C. (Inventor); Cheng, Unjeng (Inventor)

1993-01-01

241

Future satellite systems - Market demand assessment  

NASA Technical Reports Server (NTRS)

During 1979-80, a market study was performed regarding the future total demand for communications services, and satellite transmission service at the 4/6 GHz, 12/14 GHz, and 20/30 GHz frequencies. Included in the study were a variety of communications traffic characteristics as well as projections of the cost of C and Ku band satellite systems through the year 2000. In connection with the considered study, a total of 15 major study tasks and subtasks were undertaken and were all interrelated in various ways. The telecommunications service forecasts were concerned with a total of 21 data services, 5 voice services, and 5 video services. The traffic volumes within the U.S. for the three basic services were projected for three time periods. It is found that the fixed frequency allocation for domestic satellites combined with potential interference from adjacent satellites means a near term lack of orbital positions above the U.S.

Reiner, P. S.

1981-01-01

242

A Comparison of Techniques for Scheduling Earth-Observing Satellites  

NASA Technical Reports Server (NTRS)

Scheduling observations by coordinated fleets of Earth Observing Satellites (EOS) involves large search spaces, complex constraints and poorly understood bottlenecks, conditions where evolutionary and related algorithms are often effective. However, there are many such algorithms and the best one to use is not clear. Here we compare multiple variants of the genetic algorithm: stochastic hill climbing, simulated annealing, squeaky wheel optimization and iterated sampling on ten realistically-sized EOS scheduling problems. Schedules are represented by a permutation (non-temperal ordering) of the observation requests. A simple deterministic scheduler assigns times and resources to each observation request in the order indicated by the permutation, discarding those that violate the constraints created by previously scheduled observations. Simulated annealing performs best. Random mutation outperform a more 'intelligent' mutator. Furthermore, the best mutator, by a small margin, was a novel approach we call temperature dependent random sampling that makes large changes in the early stages of evolution and smaller changes towards the end of search.

Globus, Al; Crawford, James; Lohn, Jason; Pryor, Anna

2004-01-01

243

Introduction to Global Navigation Satellite System  

NASA Technical Reports Server (NTRS)

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 a overview and status of other Global Navigation Satellite System (GNSS), specifically GLONASS, Galileo, and QZSS. There is also a review of Satellite based time transfer techniques. The topic is of interest to the Time and Frequency Community, because the Global Positioning system has become the primary system for distributing Time and frequency globally, and because it allows users to synchronize clocks and calibrate and control oscillators in any location that has a GPS antenna.

Moreau, Michael

2005-01-01

244

Improving a Spectral Bin Microphysical Scheme Using TRMM Satellite Observations  

NASA Technical Reports Server (NTRS)

Comparisons between cloud model simulations and observations are crucial in validating model performance and improving physical processes represented in the mod Tel.hese modeled physical processes are idealized representations and almost always have large rooms for improvements. In this study, we use data from two different sensors onboard TRMM (Tropical Rainfall Measurement Mission) satellite to improve the microphysical scheme in the Goddard Cumulus Ensemble (GCE) model. TRMM observed mature-stage squall lines during late spring, early summer in central US over a 9-year period are compiled and compared with a case simulation by GCE model. A unique aspect of the GCE model is that it has a state-of-the-art spectral bin microphysical scheme, which uses 33 different bins to represent particle size distribution of each of the seven hydrometeor species. A forward radiative transfer model calculates TRMM Precipitation Radar (PR) reflectivity and TRMM Microwave Imager (TMI) 85 GHz brightness temperatures from simulated particle size distributions. Comparisons between model outputs and observations reveal that the model overestimates sizes of snow/aggregates in the stratiform region of the squall line. After adjusting temperature-dependent collection coefficients among ice-phase particles, PR comparisons become good while TMI comparisons worsen. Further investigations show that the partitioning between graupel (a high-density form of aggregate), and snow (a low-density form of aggregate) needs to be adjusted in order to have good comparisons in both PR reflectivity and TMI brightness temperature. This study shows that long-term satellite observations, especially those with multiple sensors, can be very useful in constraining model microphysics. It is also the first study in validating and improving a sophisticated spectral bin microphysical scheme according to long-term satellite observations.

Li, Xiaowen; Tao, Wei-Kuo; Matsui, Toshihisa; Liu, Chuntao; Masunaga, Hirohiko

2010-01-01

245

Solar power satellite, system definition study. Part 2, volume 3: SPS satellite systems  

NASA Technical Reports Server (NTRS)

The differences in approach to solar energy conversion by solar cells and thermal engine systems are examined. Systems requirements for the solar power satellite (SPS) are given along with a description of the primary subsystems. Trades leading to exact configuration selection, for example, selection of the Rankine cycle operating temperatures are explained, and two satellite configurations are discussed.

1977-01-01

246

Applications systems verification and transfer project. Volume 7: Cost/benefit analysis for the ASVT on operational applications of satellite snow-cover observations  

NASA Technical Reports Server (NTRS)

The results of the OASSO ASVT's were used to estimate the benefits accruing from the added information available from satellite snowcover area measurement. Estimates of the improvement in runoff prediction due to addition of SATSCAM were made by the Colorado ASVT personnel. The improvement estimate is 6-10%. Data were applied to subregions covering the Western States snow area amended by information from the ASVT and other watershed experts to exclude areas which are not impacted by snowmelt runoff. Benefit models were developed for irrigation and hydroenergy uses. The benefit/cost ratio is 72:1. Since only two major benefit contributors were used and since the forecast improvement estimate does not take into account future satellite capabilities these estimates are considered to be conservative. The large magnitude of the benefit/cost ratio supports the utility and applicability of SATSCAM.

Castruccio, P.; Loats, H.; Lloyd, D.; Newman, P.

1981-01-01

247

Speech compression algorithms in mobile satellite systems  

Microsoft Academic Search

Development of modern satellite systems goes from the existing land-mobile systems (such as INMARSAT-M, INMARSAT-mini-M, AMSC\\/TMI, OPTUS) towards truly mobile near-future systems (such as IRIDIUM, GLOBALSTAR, ICO, ACeS, Thuraya). Upcoming systems represent the personal communication systems with handheld terminals similar to the cellular mobile phones. One of the key technologies that enables this evolution is a design of the very

Milan MarkoviC; Branimir BoSkovic

1999-01-01

248

Measurement based satellite to outdoor channel modeling for multiple satellite systems  

Microsoft Academic Search

In this contribution we present the results of a study on satellite to outdoor channel modeling for satellite systems with multiple satellites. Our model for several satellites is based on a first order Markov channel state model for joint processes. The probability density function (PDF) of the signal amplitude within each state is fitted to the Loo distribution. The parameters

M. Milojevic; Martin Haardt; Albert Heuberger

2008-01-01

249

Present status and future plans of the Japanese earth observation satellite program  

Microsoft Academic Search

Japan is now operating 3 earth observation satellites, i. e. MOS-1 (Marine Observation Satellite-1, Momo-1 in Japanese), EGS (Experimental Geodetic Satellite, Ajisai in Japanese) and GMS (Geostationary Meteorological Satellite, Himawari in Japanese). MOS-1 has 3 different sensors, MESSR (Multispectral Electronic Self Scanning Radiometer), VTIR (Visible and Thermal Infrared Radiometer) and MSR (Microwave Scanning Radiometer) in addition to DCS (Data Collection

Kiyoshi Tsuchiya; Kohei Arai; Tamotsu Igarashi

1989-01-01

250

Stabilizing tethered satellite systems using space manipulators  

Microsoft Academic Search

The use of space manipulators to stabilize a two-body tethered satellite system (TSS) during the stationkeeping and retrieval phases, is considered. The uncontrolled motion of the system in the stationkeeping phase is marginally stable, while during the retrieval phase it is unstable. The stabilization is carried out by means of a two-link space manipulator, similar to the CANADARM. The motion

M. J. Sadight; A. K. Misrax

1994-01-01

251

Novel method of fast satellite movement information acquisition from VLBI observations  

NASA Astrophysics Data System (ADS)

Very Long Baseline Interferometry (VLBI) is a radio astronomy technique. The diameter of a VLBI synthetic telescope equals the longest baseline (>1000 Km). Therefore, VLBI can achieve very high angular resolution, and has unique advantage in the deep space tracking compared with the traditional radio ranging and Doppler tracking technologies. In the satellite VLBI observations, the spacecraft movement information such as delay or delay rate observable is very useful in the spacecraft position and orbit determination. This paper introduces an algorithm of obtaining satellite VLBI delay and delay rate based on short time correlation. Using the Differential One-way Doppler of the telemetry carrier, this method is able to complete fast fringe search, correlation, producing delay and delay rate with high accuracy from the satellite telemetry signals automatically, without any apriori orbit information. A special software correlator--Fast Fringe Searcher (FFS) was developed and successfully used in the data processing of the satellite VLBI experiments, such as the Chinese TC-1 Geospace satellite and the European SMART-1 lunar probe VLBI observations. The delay and delay rate produced by FFS were used in TC-1 orbit determination, which was the first Chinese VLBI satellite orbit determination experiment. Besides, an accurate VLBI correlator delay model can be constructed from FFS output. According to this model, a general VLBI correlator can produce more precise delay and delay rate through long time integration. This method will be applied to the real-time VLBI correlator system of the Chinese lunar exploration project in the near future.

Zheng, Weimin; Yang, Yan

2005-10-01

252

Health Monitoring of a Satellite System  

NASA Technical Reports Server (NTRS)

A health monitoring system based on analytical redundancy is developed for satellites on elliptical orbits. First, the dynamics of the satellite including orbital mechanics and attitude dynamics is modelled as a periodic system. Then, periodic fault detection filters are designed to detect and identify the satellite's actuator and sensor faults. In addition, parity equations are constructed using the algebraic redundant relationship among the actuators and sensors. Furthermore, a residual processor is designed to generate the probability of each of the actuator and sensor faults by using a sequential probability test. Finally, the health monitoring system, consisting of periodic fault detection lters, parity equations and residual processor, is evaluated in the simulation in the presence of disturbances and uncertainty.

Chen, Robert H.; Ng, Hok K.; Speyer, Jason L.; Guntur, Lokeshkumar S.; Carpenter, Russell

2004-01-01

253

Low-power magnetometer observation with satellite data transmission at unmanned site in Antarctica  

NASA Astrophysics Data System (ADS)

We will report technical experiences from 6 years of unmanned low power magnetometer observation in Antarctica with daily data transmission via Iridium satellite telephone link. One of the difficulties of unmanned observation in Antarctica is dark winter months in which power supply from solar panel can not be expected. One solution for this difficulty is to minimize the power consumption (as small as ~1 W) to manage the observation in winter months with limited amount of batteries (~400Ah). Another difficulty is to collect data from the observation site. It is quite expensive and laborious to send a party to the observation site to obtain the data in Antarctica. Although cost for satellite communication is expensive, it is much more economical to collect data via satellite data link by installing a telephone terminal into the observation system. It seems that power consumption of a satellite phone (~10 W) does not fit to the low power system. However, as long as the observed data is not too large (<1 Mbyte per day), turn on period of the satellite phone is short (<1 hour per day) and the daily average of total power consumption lies within the available power of ~1 W. We have developed low-power magnetometer system with Iridium satellite phone data link. Basic design of the low-power system is similar to that developed by British Antarctic Survey (intermittent operation of magnetometer and GPS). However, we have made some improvements; reduced power consumption (0.2 W) at high sampling rate (1Hz) and increased sensitivity (0.2nT), so that geomagnetic pulsation study can be possible. In our observation system, satellite data transfer is only made in sunlit season with the total power consumption of 1 W (0.8W for Iridium phone and 0.2W for others). During dark winter months, observed data are stored in CF memory with diminished power consumption of 0.2W. When the sun comes in spring, the stored data are transmitted along with the daily observed data. It takes nearly two months to complete the transmission of data stored in winter months. We have installed two sets of low-power magnetometer at inland and coastal area in January, 2007. We added one set every austral summer and, by January 2010, 5 magnetometers are deployed within a radius of 700km from Syowa Station. The observed data can be used for the study of magnetic pulsations, as well as small and medium scale structure of ionospheric currents at the time of auroral substorm.

Yamagishi, H.; Kadokura, A.

2012-12-01

254

Contributions of Satellite Observations to Understanding Climate Change  

NASA Technical Reports Server (NTRS)

One of the challenges facing atmospheric scientists is to interpret trends in multi-decadal data records. Although data records from satellite instruments are not as long as some ground-based records, global coverage and resolved vertical profiles provide unique information for identifying signatures of climate change. For example, the Halogen Occultation Experiment (HALOE) on the Upper Atmosphere Research Satellite provided profiles of O3, H2O, HC1, HF, CH4 from October 1991 until November 2005. There are also multi-annual ground based measurements of the column HCl. Middle latitude ground-based measurements show a seasonal cycle, and the HALOE profiles show that this is driven by the seasonal change in the composition and mass of the region between the tropopause and 380K surface (the lowermost stratosphere). Understanding the processes that produce the seasonal cycle makes it possible to interpret a future change in the seasonal cycle as a marker of a change in the stratospheric residual circulation. Satellite observations have also provided key information for improving the physical basis of models used to predict future composition and climate circulation. An example is the "tape recorder" signature in tropical stratospheric water vapor, i.e., the slow ascent of high and low water vapor anomalies roughly corresponding to the tropopause temperature at the time air entered the stratosphere. This signature has become a key diagnostic of performance for climate models.

Douglass, Anne R.

2006-01-01

255

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

256

Domestic mobile satellite systems in North America  

NASA Technical Reports Server (NTRS)

Telest Mobile Inc. (TMI) and the American Mobile Satellite Corporation (AMSC) are authorized to provide mobile satellite services (MSS) in Canada and the United States respectively. They are developing compatible systems and are undertaking joint specification and procurement of spacecraft and ground segment with the aim of operational systems by late 1993. Early entry (phase 1) mobile data services are offered in 1990 using space segment capacity leased from Inmarsat. Here, an overview is given of these domestic MSS with an emphasis on the TMI component of the MSAT systen.

Wachira, Muya

1990-01-01

257

Domestic mobile satellite systems in North America  

NASA Astrophysics Data System (ADS)

Telest Mobile Inc. (TMI) and the American Mobile Satellite Corporation (AMSC) are authorized to provide mobile satellite services (MSS) in Canada and the United States respectively. They are developing compatible systems and are undertaking joint specification and procurement of spacecraft and ground segment with the aim of operational systems by late 1993. Early entry (phase 1) mobile data services are offered in 1990 using space segment capacity leased from Inmarsat. Here, an overview is given of these domestic MSS with an emphasis on the TMI component of the MSAT systen.

Wachira, Muya

258

A relativistic and autonomous navigation satellite system  

E-print Network

A relativistic positioning system has been proposed by Bartolom\\'e Coll in 2002. Since then, several group developed this topic with different approaches. I will present a work done in collaboration with Ljubljana University and the ESA Advanced Concepts Team. We developed a concept, Autonomous Basis of Coordinates, in order to take advantage of the full autonomy of a satellite constellation for navigation and positioning, by means of satellite inter-links. I will present the advantages of this new paradigm and a number of potential application for reference systems, geophysics and relativistic gravitation.

Pacme Delva; Andrej Cadez; Uros Kostic; Sante Carloni

2011-06-16

259

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

260

The Global Ocean Observing System  

NASA Technical Reports Server (NTRS)

A Global Ocean Observing System (GOOS) should be established now with international coordination (1) to address issues of global change, (2) to implement operational ENSO forecasts, (3) to provide the data required to apply global ocean circulation models, and (4) to extract the greatest value from the one billion dollar investment over the next ten years in ocean remote sensing by the world's space agencies. The objectives of GOOS will focus on climatic and oceanic predictions, on assessing coastal pollution, and in determining the sustainability of living marine resources and ecosystems. GOOS will be a complete system including satellite observations, in situ observations, numerical modeling of ocean processes, and data exchange and management. A series of practical and economic benefits will be derived from the information generated by GOOS. In addition to the marine science community, these benefits will be realized by the energy industries of the world, and by the world's fisheries. The basic oceanic variables that are required to meet the oceanic and predictability objectives of GOOS include wind velocity over the ocean, sea surface temperature and salinity, oceanic profiles of temperature and salinity, surface current, sea level, the extent and thickness of sea ice, the partial pressure of CO2 in surface waters, and the chlorophyll concentration of surface waters. Ocean circulation models and coupled ocean-atmosphere models can be used to evaluate observing system design, to assimilate diverse data sets from in situ and remotely sensed observations, and ultimately to predict future states of the system. The volume of ocean data will increase enormously over the next decade as new satellite systems are launched and as complementary in situ measuring systems are deployed. These data must be transmitted, quality controlled, exchanged, analyzed, and archived with the best state-of-the-art computational methods.

Kester, Dana

1992-01-01

261

Second generation business satellite systems for Europe  

NASA Astrophysics Data System (ADS)

Attention is given to the characteristics of the market and its growth trends, and possible second-generation business satellite systems for use in Western Europe starting in about 1990 are described. It is noted that the total satellite traffic may be very large, reaching 530 Mbit/s by 1996, and could be several times greater should a strong video market develop. A single TDMA system is proposed that is designed to meet customer needs. Spectral saturation is obviated by employing multiple spot beams working in both the available European exclusive frequency bands: 12/14 and 20/30 GHz. On-board switching between all the transponders at a common intermediate frequency or at baseband guarantees full user interconnectivity irrespective of earth-station location or operating frequency. Dual-band working also permits extremely economic use of satellite capacity even in the event of an uneven or unpredictable geographical distribution of customers.

Serpell, S. C.

262

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.

263

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 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

264

System specification for the reusable reentry satellite  

NASA Technical Reports Server (NTRS)

The RRS design shall provide a relatively inexpensive method of access to micro and fractional gravity space environments for an extended period of time, with eventual intact recovery on the surface of the Earth. This specification establishes the performance, design, development, and test requirements for the Reusable Reentry Satellite (RRS) system.

1991-01-01

265

Solar power satellite system sizing tradeoffs  

NASA Technical Reports Server (NTRS)

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.

1981-01-01

266

Antenna systems for mobile satellite applications  

Microsoft Academic Search

In the beginning of radio development, mobile communication systems were conceived for the transmission and receiving of telegraphy and telephony signals via mobile antenna at first from ships, and then from cars, trains and aircraft. The consideration of antenna transmission is inevitable, especially in Global Mobile Satellite Communications (GMSC), where their propagation characteristics are much affected by different and changeable

S. D. Ilcev

2009-01-01

267

Satellite Power System (SPS) military implications  

NASA Technical Reports Server (NTRS)

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, and for affecting international relations. In addition, the SPS's relative vulnerability to overt military action, terrorist attacks, and sabotage was considered.

Bain, C. N.

1978-01-01

268

Role of light satellites in the high-resolution Earth observation domain  

NASA Astrophysics Data System (ADS)

Current 'classic' applications using and exploring space based earth imagery are exclusive, narrow niche tailored, expensive and hardly accessible. On the other side new, inexpensive and widely used 'consumable' applications will be only developed concurrently to the availability of appropriate imagery allowing that process. A part of these applications can be imagined today, like WWW based 'virtual tourism' or news media, but the history of technological, cultural and entertainment evolution teaches us that most of future applications are unpredictable -- they emerge together with the platforms enabling their appearance. The only thing, which can be ultimately stated, is that the definitive condition for such applications is the availability of the proper imagery platform providing low cost, high resolution, large area, quick response, simple accessibility and quick dissemination of the raw picture. This platform is a constellation of Earth Observation satellites. Up to 1995 the Space Based High Resolution Earth Observation Domain was dominated by heavy, super-expensive and very inflexible birds. The launch of Israeli OFEQ-3 Satellite by MBT Division of Israel Aircraft Industries (IAI) marked the entrance to new era of light, smart and cheap Low Earth Orbited Imaging satellites. The Earth Resource Observation System (EROS) initiated by West Indian Space, is based on OFEQ class Satellites design and it is capable to gather visual data of Earth Surface both at high resolution and large image capacity. The main attributes, derived from its compact design, low weight and sophisticated logic and which convert the EROS Satellite to valuable and productive system, are discussed. The major advantages of Light Satellites in High Resolution Earth Observation Domain are presented and WIS guidelines featuring the next generation of LEO Imaging Systems are included.

Fishman, Moshe

1999-12-01

269

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 Grbner 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.

270

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

271

Link strategy for the mobile satellite system Iridium  

Microsoft Academic Search

This paper develops crosslink routing strategies for the mobile satellite system Iridium. Motorola's Iridium satellite constellation, based on the orbit design of Adams and Rider [1987] is to provide a mobile satellite service for hand-held personal telephones. The Iridium system will have 66 satellites in 6 orbital planes at an altitude of h=780 km and a minimum elevation angle of

Harald Keller; Horst Salzwedel

1996-01-01

272

LCROSS: Lunar CRater Observation and Sensing Satellite Project  

NASA Technical Reports Server (NTRS)

This slide presentation reviews the success of the Lunar Crater Observation and Sensing Satellite (LCROSS) project. The LCROSS mission science goals was to: (1) Confirm the presence or absence of water ice in a permanently shadowed region on the Moon (2) Identify the form/state of hydrogen observed by at the lunar poles (3) Quantify, if present, the amount of water in the lunar regolith, with respect to hydrogen concentrations (4) Characterize the lunar regolith within a permanently shadowed crater on the Moon. The mission confirmed the presence of water ice on the moon by impacting a part of the spent Centaur upper stage into the Cabeus crater.. The presentation includes pictures of the development of the spacecraft, testing, launch, impact site, impact and a section of what the author called "Lunacy" which showed joking cartoons.

Marmie, John

2010-01-01

273

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

274

Assimilation of hyperspectral satellite radiance observations within tropical cyclones  

NASA Astrophysics Data System (ADS)

The availability of high resolution temperature and water vapor data is critical for the study of mesoscale scale weather phenomena (e.g., convective initiations, and tropical cyclones). As hyperspectral infrared sounders, the Atmospheric Infrared Sounder (AIRS) and Geosynchronous Imaging Fourier Transform Spectrometer (GIFTS) could provide high resolution atmospheric profiles by measuring radiations in many thousands of different channels. This work focuses on the assessment of the potential values of satellite hyperspectral radiance data on the study of convective initiations (CI) and the assimilation of AIRS radiance observations within tropical storms. First, the potential capability of hyperspectral infrared measurements (GIFTS) to provide convective precipitation forecasts has been studied and assessed. Using both the observed and the model-predicted profiles as input to the GIFTS radiative transfer model (RTM), it is shown that the simulated GIFTS radiance could capture the high vertical and temporal variability of the real and modeled atmosphere prior to a convective initiation, as well as the differences between observations and model forecasts. This study suggests the potential for hyperspectral infrared radiance data to make an important contribution to the improvement of the forecast skill of convective precipitation. Second, as the first step toward applying AIRS data to tropical cyclone (TC) prediction, a set of dropsonde profiles during Hurricane Rita (2005) is used to simulate AIRS radiance data and to assess the ability of AIRS data in capturing the vertical variability within TCs through one-dimensional variational (1D-Var) twin experiments. The AIRS observation errors and background errors are first estimated. Five sets of 1D-Var twin experiments are then performed using different combinations of AIRS channels. Finally, results from these 1D-Var experiments are analyzed. Major findings are: (1) AIRS radiance data contain useful information about the vertical variability of the temperature and water vapor within hurricanes; (2) assimilation of AIRS radiances significantly reduced errors in background temperature in the lower troposphere and relative humidity in the upper troposphere; (3) the near-real time (NRT) channel set provided by NOAA/NESDIS seems sufficient for capturing the vertical variability of the atmosphere in the upper troposphere of TCs, but not in the lower troposphere; and (4) the channels with weighting functions peak within the layer between 500-700 hPa could provide useful information to the atmospheric state below 700 hPa. A channel selection method is proposed to capture most vertical variability of temperature and water vapor within TCs contained in AIRS data. Finally, AIRS radiance data within TCs have been assimilated in the 1D-Var experiments with comparisons of the retrieval temperature and water vapor profiles with co-located Global Positioning System (GPS) radio occultation (RO) soundings and dropsonde profiles. The comparisons of AIRS 1DVar retrieval profiles with GPS RO sounding show that AIRS data can greatly improve the analysis of temperature and water vapor profiles within TCs. The comparisons of retrieval profiles with dropsonde data during Hurricane Rita, however, showed some discrepancies partly due to the difference of these two measurements and the uncertainties of the AIRS errors.

Lin, Haidao

275

Observing the earth radiation budget from satellites - Past, present, and a look to the future  

NASA Technical Reports Server (NTRS)

Satellite measurements of the radiative exchange between the planet earth and space have been the objective of many experiments since the beginning of the space age in the late 1950's. The on-going mission of the Earth Radiation Budget (ERB) experiments has been and will be to consider flight hardware, data handling and scientific analysis methods in a single design strategy. Research and development on observational data has produced an analysis model of errors associated with ERB measurement systems on polar satellites. Results show that the variability of reflected solar radiation from changing meteorology dominates measurement uncertainties. As an application, model calculations demonstrate that measurement requirements for the verification of climate models may be satisfied with observations from one polar satellite, provided there is information on diurnal variations of the radiation budget from the ERBE mission.

House, F. B.

1985-01-01

276

Verification of Cloud Cover Forecast with Satellite Observation over West Africa NATHALIE SHNE AND JEAN-PIERRE CHABOUREAU  

E-print Network

Verification of Cloud Cover Forecast with Satellite Observation over West Africa NATHALIE S?HNE exists for improving the skills of weather forecasting over West Africa. 1. Introduction Clouds the Meteosat Second Generation (MSG) satellite were used to document the cloud system variability over West

Guichard, Francoise

277

Subtropical Gyre Variability Observed by Ocean Color Satellites  

NASA Technical Reports Server (NTRS)

The subtropical gyres of the world are extensive, coherent regions that occupy about 40% of the surface of the earth. Once thought to be homogeneous and static habitats, there is increasing evidence that mid-latitude gyres exhibit substantial physical and biological variability on a variety of time scales. While biological productivity within these oligotrophic regions may be relatively small, their immense size makes their total contribution significant. Global distributions of dynamic height derived from satellite altimeter data, and chlorophyll concentration derived from satellite ocean color data, show that the dynamic center of the gyres, the region of maximum dynamic height where the thermocline is deepest, does not coincide with the region of minimum chlorophyll concentration. The physical and biological processes by which this distribution of ocean properties is maintained, and the spatial and temporal scales of variability associated with these processes, are analyzed using global surface chlorophyll-a concentrations, sea surface height, sea surface temperature and surface winds from operational satellite and meteorological sources, and hydrographic data from climatologies and individual surveys. Seasonal and interannual variability in the areal extent of the subtropical gyres are examined using 8 months (November 1996 - June 1997) of OCTS and nearly 5 years (September 1997 - June 02) of SeaWiFS ocean color data and are interpreted in the context of climate variability and measured changes in other ocean properties (i.e., wind forcing, surface currents, Ekman pumping, and vertical mixing). The North Pacific and North Atlantic gyres are observed to be shrinking over this period, while the South Pacific, South Atlantic, and South Indian Ocean gyres appear to be expanding.

McClain, Charles R.; Signorini, Sergio R.; Christian, James R.

2002-01-01

278

Sensitivity of satellite microwave and infrared observations to soil moisture at a global scale  

E-print Network

Sensitivity of satellite microwave and infrared observations to soil moisture at a global scale: Relationship of satellite observations to in situ soil moisture measurements Catherine Prigent,1 Filipe Aires,2 of the sensitivity of the available satellite observations to in situ soil moisture measurements. Although none

279

Combined observations of rock mass movements using satellite SAR interferometry, differential GPS, airborne digital  

E-print Network

Click Here for Full Article Combined observations of rock mass movements using satellite SAR movement due to glacier retreat in the Swiss Alps has been observed between 1976 and 2008 with satellite. Perruchoud, and U. Wegmüller (2010), Combined observations of rock mass movements using satellite SAR

Kääb, Andreas

280

A computer system for geosynchronous satellite navigation  

NASA Astrophysics Data System (ADS)

A computer system specifically designed to estimate and predict Geostationary Operational Environmental Satellite (GOES-4) navigation parameters using Earth imagery is described. The estimates are needed for spacecraft maneuvers while prediction provide the capability for near real-time image registration. System software is composed of four functional subsystems: (1) data base management; (2) image processing; (3) navigation; and (4) output. Hardware consists of a host minicomputer, a cathode ray tube terminal, a graphics/video display unit, and associated input/output peripherals. System validity is established through the processing of actual imagery obtained by sensors on board the Synchronous Meteorological Satellite (SMS-2). Results indicate the system is capable of operationally providing both accurate GOES-4 navigation estimates and images with a potential registration accuracy of several picture elements (pixels).

Koch, D. W.

1980-12-01

281

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, Jos

2010-05-01

282

Satellite Time- and Frequency-Transfer System  

NASA Technical Reports Server (NTRS)

Time synchronized at distant points within nanosecond. Report describes satellite-borne time-and frequency-transfer system proposed for synchronization of clocks at stations around Earth. Orbiting hydrogen-maser clock and frequency standard communicate by microwave links with Earth stations using hydrogen masers as local clocks. Pulsed-laser time-transfer sub-system also operated concurrently, either synchronized or unsynchronized with microwave subsystems.

Vessot, R. F. C.; Penfield, H.; Mattison, E.

1985-01-01

283

Engineering the satellite radio interface of a hybrid satellite-terrestrial system for MBMS delivery  

Microsoft Academic Search

The synergy between satellite and terrestrial mobile networks is regarded as a promising approach for the delivery of broadcast and multicast services to mobile users. This paper evolves around a hybrid satellite-terrestrial system, featuring a unidirectional satellite component that is responsible for the delivery of point-to-multipoint services. It proposes a systematic approach for the satellite system capacity partitioning between streaming

M. Karaliopoulos; K. Narenthiran; B. Evans; M. Neri; G. Albertazzi

2004-01-01

284

Networks for Autonomous Formation Flying Satellite Systems  

NASA Technical Reports Server (NTRS)

The performance of three communications networks to support autonomous multi-spacecraft formation flying systems is presented. All systems are comprised of a ten-satellite formation arranged in a star topology, with one of the satellites designated as the central or "mother ship." All data is routed through the mother ship to the terrestrial network. The first system uses a TCP/lP over ATM protocol architecture within the formation the second system uses the IEEE 802.11 protocol architecture within the formation and the last system uses both of the previous architectures with a constellation of geosynchronous satellites serving as an intermediate point-of-contact between the formation and the terrestrial network. The simulations consist of file transfers using either the File Transfer Protocol (FTP) or the Simple Automatic File Exchange (SAFE) Protocol. The results compare the IF queuing delay, and IP processing delay at the mother ship as well as application-level round-trip time for both systems, In all cases, using IEEE 802.11 within the formation yields less delay. Also, the throughput exhibited by SAFE is better than FTP.

Knoblock, Eric J.; Konangi, Vijay K.; Wallett, Thomas M.; Bhasin, Kul B.

2001-01-01

285

An Examination of Intertidal Temperatures Through Remotely Sensed Satellite Observations  

NASA Astrophysics Data System (ADS)

MODIS Aqua and Terra satellites produce both land surface temperatures and sea surface temperatures using calibrated algorithms. In this study, the land surface temperatures were retrieved during clear-sky (non-cloudy) conditions at a 1 km2 resolution (overpass time at 10:30 am) whereas the sea surface temperatures are also retrieved during clear-sky conditions at approximately 4 km resolution (overpass time at 1:30 pm). The purpose of this research was to examine remotely sensed sea surface (SST), intertidal (IST), and land surface temperatures (LST), in conjunction with observed in situ mussel body temperatures, as well as associated weather and tidal data. In Strawberry Hill, Oregon, it was determined that intertidal surface temperatures are similar to but distinctly different from land surface temperatures although influenced by sea surface temperatures. The air temperature and differential heating throughout the day, as well as location in relation to the shore, can greatly influence the remotely sensed surface temperatures. Therefore, remotely sensed satellite data is a very useful tool in examining intertidal temperatures for regional climatic changes over long time periods and may eventually help researchers forecast expected climate changes and help determine associated biological implications.

Lakshmi, V.

2010-12-01

286

Earth Observing System: Global Observations to Study the Earth's Environment  

NASA Technical Reports Server (NTRS)

The Earth Observing System (EOS) is a space-based observing system comprised of a series of satellite sensors by which scientists can monitor the Earth, a Data and Information System (EOSDIS) enabling researchers worldwide to access the satellite data, and an interdisciplinary science research program to interpret the satellite data. During the last couple of years, four EOS science missions were launched, representing observations of (1) total solar irradiance, (2) Earth radiation budget, (3) land cover & land use change, (4) ocean processes (vector wind, sea surface temperature, and ocean color), (5) atmospheric processes (aerosol and cloud properties, water vapor, and temperature and moisture profiles), and (6) tropospheric chemistry. In succeeding years many more satellites will be launched that will contribute immeasurably to our understanding of the Earth's environment. In this presentation I will describe how scientists are using NASA's Earth science data to examine land use and natural hazards, environmental air quality, including dust storms over the world's deserts, cloud and radiation properties, sea surface temperature, and winds over the ocean.

King, Michael D.

2001-01-01

287

GPS satellites as calibrator sources for solar observations with the PBDA  

NASA Astrophysics Data System (ADS)

The use of standard interferometer calibration techniques and calibrator sources is generally not enough to completely and uniquely solve the problem of calibration of solar interferometer data. Because, in the decimetric range, the celestial calibrators are many orders of magnitude fainter than the Sun, it is almost impossible to obtain an accurate amplitude calibration. Phase calibration is possible only thourgh use of different attenuation, that might insert unknown phase errors in the data. A different approach is presented in this work. Attempts have been made to use satellites of the Global Positioning System (GPS) as calibrator sources for solar observations with the Prototype of the Brazilian Decimetric Array (PBDA). The GPS satellites can be regarded as point sources for most of the solar-observing arrays, and have the advantage that their orbits and the power emitted by their transmitters are well known, and the flux on Earth's surface is higher than that of the Quiet Sun at 1575 MHz. These properties led to the suggestion that these satellites should be possible sources for the calibration of solar interferometric observations. We present results of observations of GPS satellites alone and also of solar observations that were calibrated using this scheme during the period from May to September, 2007. The results indicate that the GPS signals are adequate for interferometer calibration, as can be concluded from the solar maps presented.

Madsen, Felipe; Silva, Jorge; Sawant, Hanumant; Padmanabhan, Janardhan; Cecatto, Jos; Freitas, Ubiratan

288

Satellite Microwave Radar Observations of Antarctic Sea Ice. Chapter 8  

NASA Technical Reports Server (NTRS)

Historical data on Antarctic sea ice extent and concentration have traditionally been derived from visible and near-infrared images acquired by the polar-orbiting National Oceanic and Atmospheric Agency's (NOAA) meteorological satellites, using the Advanced Very High Resolution Radiometer (AVHRR), and more recently by the Defense Meteorological Satellite Program's Operational Linescan System (OLS). The limitation of these systems is that the majority of energy imparted to the Antarctic sea-ice system is transferred during b6y fast-moving low pressure systems. Since the Southern Ocean sea-ice cover is completely bounded at its lower latitude limit by open ocean, these "polar lows" transport large amounts of moisture (contained in warm air masses) over the outer ice cover. The result is that most, if not all, noteworthy periods of wind- and temperature-driven dynamic changes in the ice cover are accompanied by periods where the region is blanketed by cloud, and when the atmosphere is inherently more electromagnetically opaque. During storms, the probability with which the area is cloud covered is extremely high, thereby ruling out use of visible or near-infrared images as a practical method of monitoring the associated changes in ice conditions. Instead, Nimbus-7 Scanning Multichannel Microwave Radiometer (SMMR) and DMSP Special Sensor Microwave/imager (SSM/I) have been the primary workhorses to build up a microwave record of Antarctic sea-ice characteristics. Similar problems, however, occur in passive microwave retrievals of sea-ice concentration, and the algorithms are called into question during these periods of change. The influence of water vapor in the atmosphere alone can modify the ice concentration retrievals by fractions exceeding 105, and that retrievals of ice concentration must compensate for the atmospheric water vapor and liquid water contents.

Drinkwater, Mark R.

1998-01-01

289

Anomalous event diagnosis for environmental satellite systems  

NASA Technical Reports Server (NTRS)

The National Oceanic and Atmospheric Administration's (NOAA) National Environmental Satellite, Data, and Information Service (NESDIS) is responsible for the operation of the NOAA geostationary and polar orbiting satellites. NESDIS provides a wide array of operational meteorological and oceanographic products and services and operates various computer and communication systems on a 24-hour, seven days per week schedule. The Anomaly Reporting System contains a database of anomalous events regarding the operations of the Geostationary Operational Environmental Satellite (GOES), communication, or computer systems that have degraded or caused the loss of GOES imagery. Data is currently entered manually via an automated query user interface. There are 21 possible symptoms (e.g., No Data), and 73 possible causes (e.g., Sectorizer - World Weather Building) of an anomalous event. The determination of an event's cause(s) is made by the on-duty computer operator, who enters the event in a paper based daily log, and by the analyst entering the data into the reporting system. The determination of the event's cause(s) impacts both the operational status of these systems, and the performance evaluation of the on-site computer and communication operations contractor.

Ramsay, Bruce H.

1993-01-01

290

Jupiter System Observer  

NASA Technical Reports Server (NTRS)

This slide presentation reviews the scientific philosophy that is guiding the planning behind the Jupiter System Observer (JSO). The JSO would be a long-term platform for studying Jupiter and the complete Jovian system. The goal is to advance the understanding of the fundamental processes of planetary systems, their formation and evolution.

Senske, Dave; Prockter, Louise

2008-01-01

291

Observations of volcanic emissions using satellite remote sensing  

NASA Astrophysics Data System (ADS)

Volcanoes pose a threat to the human population at regional and global scales and so efficient monitoring is essential in order to effectively manage and mitigate the risks that they pose. Volcano monitoring from space has been possible for over thirty years and now, more than ever, a suite of instruments exists with the capability to observe emissions of gas and ash from a unique perspective. The goal of this research is to demonstrate the use of a range of satellite-based sensors in order to detect and quantify volcanic sulphur dioxide, and to assess the relative performances of each sensor against one another. Such comparisons are important in order to standardise retrievals and permit better estimations of the global contribution of sulphur dioxide to the atmosphere from volcanoes for climate modelling. In this work, retrievals of volcanic sulphur dioxide from a number of instruments are compared, and the individual performances at quantifying emissions from large, explosive volcanic eruptions are assessed. Retrievals vary widely from sensor to sensor, and often the use of a number of sensors in synergy can provide the most complete picture, rather than just one instrument alone. Volcanic emissions have the ability to result significant economic loses by grounding aircraft due to the high risk associated with ash encountering aircraft. As sulphur dioxide is often easier to measure than ash, it is often used as a proxy. This work examines whether this is a reasonable assumption, using the Icelandic eruption in early 2010 as a case study. Results indicate that although the two species are for the most part collocated, separation can occur under some conditions, meaning that it is essential to accurately measure both species in order to provide effective hazard mitigation. Finally, the usefulness of satellite remote sensing in quantifying the passive degassing from Turrialba, Costa Rica is demonstrated. The increase in activity from 2005 - 2010 can be observed in satellite data prior to the phreatic phase of early 2010, and can therefore potentially provide a useful indication of changing activity at some volcanoes.

Thomas, Helen E.

292

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

293

System requirements for satellite laser ranging time transfer  

Microsoft Academic Search

To increase the accuracy of time transfer to hundreds of picoseconds, we have proposed a two way technique using the Japanese geodetic satellite Ajisai. The system would involve two satellite laser ranging (SLR) ground stations simultaneously ranging to the satellite, then depending upon the orientation of the satellite, reflect the laser pulse to the other ground station. When the fire

Bret Engelkemier; Hiroo Kunimori; T. Otsuto; Taizoh Yoshino

1994-01-01

294

Automated tracking for advanced satellite laser ranging systems  

Microsoft Academic Search

NASA's Satellite Laser Ranging Network was originally developed during the 1970s to track satellites carrying corner cube reflectors. Today eight NASA systems, achieving millimeter ranging precision, are part of a global network of more than 40 stations that track 17 international satellites. To meet the tracking demands of a steadily growing satellite constellation within existing resources, NASA is embarking on

Jan F. McGarry; John J. Degnan; Paul Titterton; Harold Sweeney; Brion P. Conklin; Peter J. Dunn; Hughes STX

295

Automated tracking for advanced satellite laser ranging systems  

Microsoft Academic Search

NASA's Satellite Laser Ranging Network was originally developed during the 1970's to track satellites carrying corner cube reflectors. Today eight NASA systems, achieving millimeter ranging precision, are part of a global network of more than 40 stations that track 17 international satellites. To meet the tracking demands of a steadily growing satellite constellation within existing resources, NASA is embarking on

Jan F. McGarry; John J. Degnan; Paul J. Titterton; Harold E. Sweeney; Brion P. Conklin; Peter J. Dunn

1996-01-01

296

Sirius XM Satellite Radio system overview and services  

Microsoft Academic Search

Sirius XM Radio, through its Sirius and XM Satellite Radio systems, broadcasts continuous high quality audio, video and data content to over nineteen million subscribers throughout the Continental United States (CONUS) and Canada. The original Sirius system utilizes three satellites in highly inclined orbits. The original XM system utilizes two satellites in geostationary orbits. Both systems achieve a coverage pattern

Stefano DiPierro; Riza Akturan; Richard Michalski

2010-01-01

297

Development status of first Tethered Satellite System  

NASA Technical Reports Server (NTRS)

An MOU between NASA and Italian research organizations has assigned the responsibilities for the development, payload integration, launch and operation of a Tethered Satellite System (TSS). The TSS will include a deployer mounted on a Spacelab pallet, science equipment on a customized mission support structure and a satellite connected to the Orbiter by a tether. The satellite is 1.6 m in diameter and can weight up to 500 kg. The deployer will be insulated from the Orbiter because of the conductive nature of the tether. The first mission is to demonstrate the TSS technology, perform electrodynamic investigations of the interaction of the tether with ambient space plasma, and gather data on atmospheric interactions in the lower thermosphere, geomagnetic phenomena and gravimetric characteristics. The first TSS will be deployed 20 km outward from the Orbiter and the earth on a strand of tin-coated copper wire wrapped in Teflon insulation, braided Kevlar and a Nomek jacket. The first strand is designed to accommodate 53 N tension. The satellite on the end of the tether will be a multimission platform for facile changeout of the scientific package from mission-to-mission.

Sisson, J. M.

1986-01-01

298

Mutual Events in the Uranian satellite system in 2007  

NASA Astrophysics Data System (ADS)

The equinox time on the giant planets When the Sun crosses the equatorial plane of a giant planet, it is the equinox time occurring every half orbit of the planet, i.e. every 6 years for Jupiter, 14 years for Saturn, 42 years for Uranus and 82 years for Neptune. Except Neptune, each planet have several major satellites orbiting in the equatorial plane, then, during the equinox time, the satellites will eclipse each other mutually. Since the Earth follows the Sun, during the equinox time, a terrestrial observer will see each satellite occulting each other during the same period. These events may be observed with photometric receivers since the light from the satellites will decrease during the events. The light curve will provide information on the geometric configuration of the the satellites at the time of the event with an accuracy of a few kilometers, not depending on the distance of the satellite system. Then, we are able to get an astrometric observation with an accuracy several times better than using direct imaging for positions. Equinox on Uranus in 2007 In 2007, it was equinox time on Uranus. The Sun crossed the equatorial plane of Uranus on December 6, 2007. Since the opposition Uranus-Sun was at the end of August 2007, observations were performed from May to December 2007. Since the declination of Uranus was between -5 and -6 degrees, observations were better to make in the southern hemisphere. However, some difficulties had to be solved: the faintness of the satellites (magnitude between 14 and 16), the brightness of the planet (magnitude 5) making difficult the photometric observation of the satellites. The used of K' filter associated to a large telescope allows to increase the number of observable events. Dynamics of the Uranian satellites One of the goals of the observations was to evaluate the accuracy of the current dynamical models of the motion of the satellites. This knowledge is important for several reasons: most of time the Uranian system is observed "pole-on" and the relative inclinations of the orbits of the satellites are very difficult to know. More, this knowledge should allow us to determine the precession of Uranus which is not yet known. Another reason to improve the dynamics of the Uranian satellites is to quantify the dissipation of energy inside the satellites because of the tides: only very accurate astrometric observations may allow to reach such a result. We used two models for our purpose: the one from Laskar and Jacobson (GUST86) based upon observations made using observations made from 1911 to 1986 [1] and the one from Arlot, Lainey and Thuillot (LA06) [2] based upon a different sets of observations made from 1950 to 2006. Astrometric observations Since the mutual events are observable only every 42 years (in fact, 2007 was the first time where mutual events were observed on the Uranian system), many other astrometric observations were performed, mainly with photographic plates, CCD targets or using a meridian transit circle. These observations and their accuracy will be compared with mutual events. Note that these observations introduce some biases in the data (date of the opposition, absolute position of the planet), different than those of mutual events (equinox time). Observations of mutual events in 2007 Due to the difficulty of the observations, very few observations were made: about 15 events were observed using telescopes with apertures from 40 cm to 8 meters... The observing sites which reported observations were Marseille and Pic du Midi (France), Canarian Islands (Spain), La Silla and Paranal (Chile), Itajuba (Brazil), Tubitak (Turkey), Hanle (India) and Siding Spring (Australia). A preliminary analysis Some light curves were reduced and a comparison has been made with the theoretical calculations of the events. A preliminary analysis shows that LA06 has smaller residuals in the longitudes of the satellites than GUST86 but the residuals are equivalent in latitude. This confirms the problem due to the "pole-on" observation of this system and shows the

Arlot, J. E.

2008-09-01

299

Principle of 1.2m Telescope Satellite Laser Ranging System  

Microsoft Academic Search

Based on light-path characters and ranging control system peculiarity, this paper analyzed and standed the principle of Yunnan Observatory Satellite Laser Ranging system, and expatiated on ranging system work procedure, and presented current base observing status.

Zhu-Lian Li; Yao-Heng Xiong; Miao-Chan He; Xiang-Ming Zheng; Shao-Hui He; Hong-Li Fu

2008-01-01

300

Research opportunities related to ESA's Swarm mission: Potential of combined ground-satellite observations  

NASA Astrophysics Data System (ADS)

ESA's Earth observation Mission Swarm is scheduled for launch middle of 2011. The fleet of three satellites will provide many opportunities for dedicated studies of ionospheric-magnetospheric processes. The Swarm spacecraft are quite similar to the German CHAMP satellite. For that reason experience gained from CHAMP measurements can be regarded as benchmarks for in-vestigations to be considered for Swarm. Here we are reporting on CHAMP results obtained from combined ground-satellite observations. The equatorial electrojet (EEJ) is an intense cur-rent system that can be deduced conveniently from ground and satellite magnetic field data. In a series of studies the EEJ has been better characterised by combining readings from above and below. Another example is the relation between vertical plasma drift and the evolution of the equatorial ionisation anomaly (EIA). By correlating the plasma drift obtained from radar measurements with simultaneous electron density measurements at 400km altitude we could determine, in which way the EIA is responding to changes of the vertical plasma velocity. Fur-thermore, we studied the substorm onset current system. Important new insights where gained by combining ground-based observatory data with CHAMP measurements. The additional constrains of observations from above and below the ionosphere helped to construct a much more detailed substorm current wedge model.

Luehr, Hermann

301

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

302

Thailand Earth Observation System: Mission and Control  

NASA Astrophysics Data System (ADS)

Thailand Earth Observation System (THEOS) comprised of space and ground segment is designed to fulfill the needs of using high resolution data, large swath width and frequent revisit time from satellite remote sensing to monitor and support the exploitation of resources for various applications such as cartography, agriculture, etc. THEOS Control Ground Segment was established in Thailand to provide commands and control of the satellite. The satellite can be programmed for imaging and downlink image data from onboard memory. Facilities have been provided at Control Ground station in Siracha, Thailand to accommodate the monitoring and control of the satellite by Telecommands transmission and Telemetry reception. The aim of this paper is to present the characteristics of THEOS system, its mission & Control Ground Segment and THEOS Operation.

Kiadtikornthaweeyot, W.

2008-08-01

303

Arctic Cloud Changes from Surface and Satellite Observations RYAN EASTMAN AND STEPHEN G. WARREN  

E-print Network

Arctic Cloud Changes from Surface and Satellite Observations RYAN EASTMAN AND STEPHEN G. WARREN of the Arctic are analyzed for total cloud cover. Trends and interannual variations in surface cloud data and Infrared Observation Satellite (TIROS) Operational Vertical Sounder (TOVS) satellite data. Over the Arctic

Hochberg, Michael

304

Satellites: New global observing techniques for ice and snow. [using erts-1 and nimbus 5 satellite  

NASA Technical Reports Server (NTRS)

The relation of aereal extent of snow cover to the average monthly runoff in a given watershed was investigated by comparing runoff records with a series of snowcover maps. Studies using the high spatial resolution available with ERTS-1 imagery were carried out for the Wind River Mountains watersheds in Wyoming, where it was found that the empirical relationship varied with mean elevation of the watershed. In addition, digital image enhancement techniques are shown to be useful for identifying glacier features related to extent of snowcover, moraine characteristics, and debris average. Longer wavelength observations using sensors on board the Nimbus 5 Satellite are shown to be useful for indicating crystal size distributions and onset of melting on glacier snow cover.

Gloersen, P.; Salomonson, V. V.

1974-01-01

305

In-situ observation of aurora fine structure and simulation of satellite-plasma interaction  

NASA Astrophysics Data System (ADS)

INDEX satellite is scheduled to be launched in 2004 by ISAS/JAPAN in order to investigate the aurora fine structure. This satellite is designed to fly polar orbit with hight of 680km. Main instruments are the electron/ion analyzer, the aurora camera and the impedance probe. All insturments are designed to measure small scale plasma parameters down to 100m scale. In order to distinguish background plasma phenomena from the disturbances due to the satellite itself, we have developed a new simulation code which simulates electromagnetic environment in the vicinity of a spacecraft. This code solves plasma particle behavior as well as background electric and magnetic field. The simulation code adopts unstructured-grid as the spatial coordinate system. This enables us to model 3-dimensional shape of the spacecraft. We will be able to show the results from the spacecraft charging simulations and possible applications to the observation of plasma fine structure in the earth's auroral region.

Okada, M.; Ejiri, M.; Sakanoi, T.; Hirahara, M.

2002-12-01

306

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

307

Satellite Telemetry and Command using Big LEO Mobile Telecommunications Systems  

NASA Technical Reports Server (NTRS)

Various issues associated with satellite telemetry and command using Big LEO mobile telecommunications systems are presented in viewgraph form. Specific topics include: 1) Commercial Satellite system overviews: Globalstar, ICO, and Iridium; 2) System capabilities and cost reduction; 3) Satellite constellations and contact limitations; 4) Capabilities of Globalstar, ICO and Iridium with emphasis on Globalstar; and 5) Flight transceiver issues and security.

Huegel, Fred

1998-01-01

308

Low-Earth-orbit satellite systems in ocean science  

Microsoft Academic Search

Scientists and engineers constantly face the challenge of getting data from remote areas of the world's oceans back to their laboratories. Low-Earth-orbit (LEO) satellites already provide routine access to such data. We review the LEO satellite telemetry systems used in ocean sciences. The comparison of available and planned systems includes system design, satellite orbits, data. We review the LEO geographic

P. C. Griffith; D. C. Potts; S. L. Morgan

1996-01-01

309

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

NASA Technical Reports Server (NTRS)

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

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

1975-01-01

310

Observability for hybrid systems  

Microsoft Academic Search

The notion of generic final-state asymptotically determinable hybrid system is introduced. Then, sufficient conditions for a linear hybrid system to be generic final-state asymptotically determinable are given. These conditions show that generic final-state asymptotic determinability can be verified even if each of the continuous subsystems of the hybrid system is not observable. More precisely, these conditions are related to the

Andrea Balluchi; Luca Benvenuti; M. D. Di Benedetto; A. L. Sangiovanni-Vincentelli

2003-01-01

311

Satellite Observations of Antarctic Sea Ice Thickness and Volume  

NASA Technical Reports Server (NTRS)

We utilize satellite laser altimetry data from ICESat combined with passive microwave measurements to analyze basin-wide changes in Antarctic sea ice thickness and volume over a 5 year period from 2003-2008. Sea ice thickness exhibits a small negative trend while area increases in the summer and fall balanced losses in thickness leading to small overall volume changes. Using a five year time-series, we show that only small ice thickness changes of less than -0.03 m/yr and volume changes of -266 cu km/yr and 160 cu km/yr occurred for the spring and summer periods, respectively. The calculated thickness and volume trends are small compared to the observational time period and interannual variability which masks the determination of long-term trend or cyclical variability in the sea ice cover. These results are in stark contrast to the much greater observed losses in Arctic sea ice volume and illustrate the different hemispheric changes of the polar sea ice covers in recent years.

Kurtz, Nathan; Markus, Thorsten

2012-01-01

312

Ambiguity resolution for satellite Doppler positioning systems  

NASA Technical Reports Server (NTRS)

The implementation of satellite-based Doppler positioning systems frequently requires the recovery of transmitter position from a single pass of Doppler data. The least-squares approach to the problem yields conjugate solutions on either side of the satellite subtrack. It is important to develop a procedure for choosing the proper solution which is correct in a high percentage of cases. A test for ambiguity resolution which is the most powerful in the sense that it maximizes the probability of a correct decision is derived. When systematic error sources are properly included in the least-squares reduction process to yield an optimal solution the test reduces to choosing the solution which provides the smaller valuation of the least-squares loss function. When systematic error sources are ignored in the least-squares reduction, the most powerful test is a quadratic form comparison with the weighting matrix of the quadratic form obtained by computing the pseudoinverse of a reduced-rank square matrix. A formula for computing the power of the most powerful test is provided. Numerical examples are included in which the power of the test is computed for situations that are relevant to the design of a satellite-aided search and rescue system.

Argentiero, P.; Marini, J.

1979-01-01

313

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

314

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.

315

Monitoring of global geodynamic processes using satellite observations  

NASA Astrophysics Data System (ADS)

To study mechanisms of destructive geodynamic phenomena including determination of places of possible severe earthquakes, volcano eruptions and some other natural hazards, it is important to have means to evolve areas where maximum changes of the displacement velocities and the terrestrial crust vertical movements are possible. The previous experience has shown that the satellite geodesy techniques including global navigation systems and satellite laser ranging are the most effective for research activities in this field. Permanent control of secular movement of GPS-stations of the international geodynamic network, located in Russia, has allowed improving the reference coordinate frame for North Eurasia since Russian network stations provide representative covering of the largest stable areas (the Siberian and the East European) of the Eurasian plate. Along its southern border, there is a zone consisting of a great number of microplates surrounding the South-Eurasian stable plate. Interaction of these small plates and blocks influences distribution of seismic stresses in internal parts of the continent that is confirmed by the highest seismic activity of the triangle bordered by thrusts of the Himalayas and faults of the Pamirs, the Tien-Shan, the Baikal and the North-Eastern China. One of the active tectonic zones of Egypt located in Aswan, is characterized by regional basement rock uplift and regional faulting. In 1997, the African Regional Geodynamic Network was developed around the northern part of Lake Nasser, consists of 11 points, on both sides of the Lake. Its main goal is to study the geodynamical behavior around the northern part of the lake. The collected data were processed using the Bernese software version 5.0. From the velocity results, including also the African plate motion, it can be noticed that all stations of this network are moved to the northeast direction and it is typically the direction of the African plate motion.

Tatevian, S. K.; Attia, G. F.; Abou-Aly, N.; Ghoneim, R.; Hegazy, M.

2014-06-01

316

Comparisons of Satellite Optical Observations with Ground-Based Observations of Lightning, Then and Now  

Microsoft Academic Search

About 20 years ago, the first and third authors presented a paper comparing the optical observations of lightning from the DMSP Piggy Back Experiment (PBE) with ground-based manually determined lightning ground-strike locations. In one case in 1977 there were eleven optical events from one satellite pass over the region of interest for which there were ground-based data available. In general

W. H. Beasley; C. M. Noble; B. C. Edgar; D. M. Suszcynsky; T. E. Light

2001-01-01

317

The Role of Satellite Earth Observation Data in Monitoring and Verifying International Environmental Treaties  

NASA Technical Reports Server (NTRS)

The term verification implies compliance verification in the language of treaty negotiation and implementation, particularly in the fields of disarmament and arms control. The term monitoring on the other hand, in both environmental and arms control treaties, has a much broader interpretation which allows for use of supporting data sources that are not necessarily acceptable or adequate for direct verification. There are many ways that satellite Earth observation (EO) data can support international environmental agreements, from national forest inventories to use in geographic information system (GIs) tools. Though only a few references to satellite EO data and their use exist in the treaties themselves, an expanding list of applications can be considered in support of multilateral environmental agreements (MEAs). This paper explores the current uses of satellite Earth observation data which support monitoring activities of major environmental treaties and draws conclusions about future missions and their data use. The scope of the study includes all phases of environmental treaty fulfillment - development, monitoring, and enforcement - and includes a multinational perspective on the use of satellite Earth observation data for treaty support.

Johnston, Shaida

2004-01-01

318

Survey of the ionospheric disturbances related with large seismic events in multi-satellite ionospheric observations  

NASA Astrophysics Data System (ADS)

We survey the ionospheric disturbances in the plasma and electro-magnetic wave measurements during the simultaneous observation period of DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions), CHAMP (CHAllenging Minisatellite Payload) and DMSP(Defense Meteorological Satellite Program) missions. The multi-satellite observation around three large earthquakes that occurred between 2004 and 2005 were investigated. The observational evidences of the earth-quake precursory phenomena and the recent progress of physical modeling of the ionospheric disturbances caused by the coupling of the stressed rock, Earth surface charges, atmosphere, and ionosphere system are reviewed. Then, we focus on identifying the precursory disturbances from the well-studied plasma disturbances in the ionosphere, which are known to originate from various physical mechanism other than the seismic activities. Electron density/temperature, ion density/temperature, and electro-magnetic field/wave data measured by various instruments equipped in the satellites were analyzed in finding specific examples of anomaly caused by large seismic activities. Finally, the possibility of forecasting or predicting large earthquakes using the plasma measurements of LEO (low earth orbit) satellites will be discussed.

Ryu, K.; Chae, J.; Lee, E.; Kil, H.

2013-12-01

319

Satellite voice broadcase system study. Volume 1: Executive summary  

NASA Technical Reports Server (NTRS)

The feasibility of providing Voice of America (VOA) broadcasts by satellite relay was investigated. Satellite voice broadcast systems are described for three different frequency bands: HF, FHV, and L-band. Geostationary satellite configurations are considered for both frequency bands. A system of subsynchronous, circular satellites with an orbit period of 8 hours was developed for the HF band. The VHF broadcasts are provided by a system of Molniya satellites. The satellite designs are limited in size and weight to the capability of the STS/Centaur launch vehicle combination. At L-band, only four geostationary satellites are needed to meet the requirements of the complete broadcast schedule. These satellites are comparable in size and weight to current satellites designed for the direct broadcast of video program material.

Horstein, M.

1985-01-01

320

FIDEX: An expert system for satellite diagnostics  

NASA Technical Reports Server (NTRS)

A Fault Isolation and Diagnostic Expert system (FIDEX) was developed for communication satellite diagnostics. It was designed specifically for the 30/20 GHz satellite transponder. The expert system was designed with a generic structure and features that make it applicable to other types of space systems. FIDEX is a frame based system that enjoys many of the inherent frame base features, such as hierarchy that describes the transponder's components, with other hierarchies that provide structural and fault information about the transponder. This architecture provides a flexible diagnostic structure and enhances maintenance of the system. FIDEX also includes an inexact reasoning technique and a primitive learning ability. Inexact reasoning was an important feature for this system due to the sparse number of sensors available to provide information on the transponder's performance. FIDEX can determine the most likely faulted component under the constraint of limited information. FIDEX learns about the most likely faults in the transponder by keeping a record of past established faults. FIDEX also has the ability to detect anomalies in the sensors that provide information on the transponders performance.

Durkin, John; Tallo, Donald; Petrik, Edward J.

1991-01-01

321

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 (7506?S, 12321?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 0.41.0 m range. It was found that for the past decade, the reflectivity change of the site is within 1.35% at 0.64 m, 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-2SeaWiFS, TerraAqua 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

322

Gas Flaring Volume Estimates with Multiple Satellite Observations  

Microsoft Academic Search

Flammable gases (primarily methane) are a common bi-product associated with oil wells. Where there is no infrastructure to use the gas or bring it to market, the gases are typically flared off. This practice is more common at remote sites, such as an offshore drilling platform. The Defense Meteorological Satellite Program (DMSP) is a series of satellites with a low-light

D. C. Ziskin; C. Elvidge; K. Baugh; T. Ghosh; F. C. Hsu

2010-01-01

323

SORCE and Future Satellite Observations of Solar Irradiance  

NASA Technical Reports Server (NTRS)

With solar activity just passing the maximum of cycle 23, SORCE is beginning a 5 year mission to measure total solar irradiance (TSI) with unprecedented accuracy using phase-sensitive detection, and to measure spectral solar irradiance (SSI) with unprecedented spectral coverage, from 1 to 2000 nm. The new Total Irradiance Monitor (TIM) has 4 active cavity radiometers, any one of which can be used as a fixed-temperature reference against any other that is exposed to the Sun via a shutter that cycles at a rate designed to minimize noise at the shutter frequency. The new Spectral Irradiance Monitor (SIM) is a dual Fery prism spectrometer that can employ either prism as a monochromatic source on the other prism, thus monitoring its transmission during the mission lifetime. Either prism can measure SSI from 200 to 2000 nm, employing the same phase-sensitive electrical substitution strategy as TIM. SORCE also carries dual SOLSTICE instruments to cover the spectral range 100-320 nm, similar to the instruments onboard UARS, and also an XUV Photometer System (XPS) similar to that on TIMED. SSI has now been added to TSI as a requirement of EOS and NPOESS, because different spectral components drive different components of the climate system - UV into upper atmosphere and stratospheric ozone, IR into tropospheric water vapor and clouds, and Visible into the oceans and biosphere. Succeeding satellite missions being planned for 2006 and 2011 will continue to monitor these critical solar variables.

Cahalan, Robert F.; Rottman, G.; Woods, T.; Lawrence, G.; Kopp, G.; Harder, J.; McClintock, W.

2003-01-01

324

Advanced Satellite Sounding: The Benefits of Hyperspectral Observation - 2nd Edition  

NSDL National Science Digital Library

This lesson is an update to the 2008 expert lecture on hyperspectral observations presented by Dr. Mitch Goldberg, Program Scientist for NOAA's Joint Polar Satellite System (JPSS) Program. The lesson discusses what hyperspectral observations are, how they are made, some current products, their contributions to improved monitoring of the atmosphere, oceans, and land surfaces, as well as their impact on numerical weather prediction. The lesson begins by discussing the importance of satellite observing systems. From there, it reviews the principles of remote sensing that are needed for deriving products from hyperspectral infrared observations. The third and largest section of the lesson examines results from and operational applications of the AIRS, IASI, and CrIS hyperspectral sounders. The final section discusses the importance of hyperspectral soundings from geostationary satellites. The lesson has been updated from the original presentation to include information about NASA and NOAA's new polar orbiting programs and CrIS, the Cross-track Infrared Sounder on the Suomi NPP polar orbiter.

Comet

2013-07-09

325

Satellite observations of oil spills in Bohai Sea  

NASA Astrophysics Data System (ADS)

Several oil spills occurred at two oil platforms in Bohai Sea, China on June 4 and 17, 2011. The oil spills were subsequently imaged by different types of satellite sensors including SAR (Synthetic Aperture Radar), Chinese HJ-1-B CCD and NOAA MODIS. In order to detect the oil spills more accurately, images of the former three sensors were used in this study. Oil spills were detected using the semi-supervised Texture-Classifying Neural Network Algorithm (TCNNA) in SAR images and gradient edge detection algorithm in HJ-1-B and MODIS images. The results show that, on June 11, the area of oil slicks is 31 km2 and they are observed in the vicinity and to the north of the oilfield in SAR image. The coverage of the oil spill expands dramatically to 244 km2 due to the newly released oil after June 11 in SAR image of June 14. The results on June 19 show that under a cloud-free condition, CCD and MODIS images capture the oil spills clearly while TCNNA cannot separate them from the background surface, which implies that the optical images play an important role in oil detection besides SAR images.

Wei, Y. L.; Tang, Z. Y.; Li, X. F.

2014-03-01

326

Evaluation of High-Resolution Precipitation Estimates from Satellite Observations  

NASA Astrophysics Data System (ADS)

During recent years, a number of satellite-derived, globally complete, high resolution precipitation products with a spatial resolution of at least 0.25 and a temporal resolution of at least three-hourly have been developed and produced regularly. These products generally merge geostationary infra-red data and polar- orbiting passive microwave data to take advantage of the high sampling of the infra-red and the superior quality of the microwave, and sometimes use ancillary data such as radar or gauge observations or model output. The Program to Evaluate High Resolution Precipitation Products (PEHRPP) was established by the International Precipitation Working Group to evaluate and inter-compare these datasets at a variety of spatial and temporal resolutions with the intent of guiding dataset developers and informing the user community regarding the error characteristics of these useful products. This presentation will summarize the current state of PEHRPP-related investigations, including the results from the International PEHRPP Workshop held in December 2007.

Arkin, P.; Turk, J.; Sapiano, M.; Ebert, B.

2008-05-01

327

Study of the NWC electrons belt observed on DEMETER Satellite  

E-print Network

We analyzed the data from 2007 to 2008, which is observed by IDP onboard DEMETER satellite, during ten months of NWC working and seven months of NWC shutdown. The characteristic of the space instantaneous electron belts, which come from the influence of the VLF transmitted by NWC, is studied comprehensively. The main distribution region of the NWC electron belts and the flux change are given. We also studied the distribution characteristic of the average energy spectrum in different magnetic shell at the height of DEMETER orbit and the difference of the average energy spectrum of the electrons in the drift loss-cone between day and night. As a result, the powerful power of NWC transmitter and the 19.8 kHz narrow bandwidth VLF emission not only created a momentary electrons enhancement region, which strides 180 degree in them longitude direction and from 1.6 to 1.9 in L value, with the rise of the electrons flux reaching to 3 orders of magnitude mostly, but also induced the enhancement or loss of electrons in ...

Li, Xinqiao; Wang, Ping; Wang, Huanyu; Lu, Hong; Zhang, Xuemin; Huang, Jianping; Shi, Feng; Yu, Xiaoxia; Xu, Yanbing; Meng, Xiangcheng; Wang, Hui; Zhao, Xiaoyun; Parrot, M

2010-01-01

328

Spectroradiometric considerations for advanced land observing systems  

NASA Technical Reports Server (NTRS)

Research aimed at improving the inflight absolute radiometric calibration of advanced land observing systems was initiated. Emphasis was on the satellite sensor calibration program at White Sands. Topics addressed include: absolute radiometric calibration of advanced remote sensing; atmospheric effects on reflected radiation; inflight radiometric calibration; field radiometric methods for reflectance and atmospheric measurement; and calibration of field relectance radiometers.

Slater, P. N.

1986-01-01

329

Pseudo-coherent demodulation for mobile satellite systems  

NASA Technical Reports Server (NTRS)

This paper proposes three so-called pseudo-coherent demodulation schemes for use in land mobile satellite channels. The schemes are derived based on maximum likelihood (ML) estimation and detection of an N-symbol observation of the received signal. Simulation results for all three demodulators are presented to allow comparison with the performance of differential PSK (DPSK) and ideal coherent demodulation for various system parameter sets of practical interest.

Divsalar, Dariush; Simon, Marvin K.

1993-01-01

330

Joint Polar Satellite System (JPSS) Common Ground System (CGS) Performance for Suomi NPP  

NASA Astrophysics Data System (ADS)

The National Oceanic and Atmospheric Administration (NOAA) and National Aeronautics and Space Administration (NASA) are jointly acquiring the next-generation civilian weather and environmental satellite system: the Joint Polar Satellite System (JPSS). JPSS will contribute the afternoon orbit component and ground processing system of the restructured National Polar-orbiting Operational Environmental Satellite System (NPOESS). As such, the Joint Polar Satellite System replaces the current Polar-orbiting Operational Environmental Satellites (POES) managed by the National Oceanic and Atmospheric Administration and the ground processing component of both Polar-orbiting Operational Environmental Satellites and the Defense Meteorological Satellite Program (DMSP) replacement, previously known as the Defense Weather Satellite System (DWSS), managed by the Department of Defense (DoD). The JPSS satellites will carry a suite of sensors designed to collect meteorological, oceanographic, climatological, and solar-geophysical observations of the earth, atmosphere, and space. The ground processing system for JPSS is known as the JPSS Common Ground System (JPSS CGS), and consists of a Command, Control, and Communications Segment (C3S) and an Interface Data Processing Segment (IDPS). Both segments are developed by Raytheon Intelligence and Information Systems (IIS). The C3S currently flies the Suomi National Polar Partnership (Suomi NPP) satellite and transfers mission data from Suomi NPP and between the ground facilities. The IDPS processes Suomi NPP satellite data to provide Environmental Data Records (EDRs) to NOAA and DoD processing centers operated by the United States government. When the JPSS-1 satellite is launched in early 2017, the responsibilities of the C3S and the IDPS will be expanded to support both Suomi NPP and JPSS-1. The Suomi NPP launched on October 28, 2011. Launch was followed by a phase of sensor activation, and full volume data traffic is now flowing from the satellite through C3S and into the IDPS for data processing. Ground system performance is critical for this operational system. This presentation will provide details of ground system processing performance, such as data rates through each of the C3S nodes, data accounting statistics, and retransmission rates and success, along with IDPS throughput, data availability, and latency.

Idol, J.; Grant, K. D.; Waas, W.; Austin, J.

2012-12-01

331

Multifunction personal and mobile SMM antenna for satellite communications systems  

Microsoft Academic Search

There are a number of personal and mobile communications systems based on the use of microwave links relayed by Earth-orbiting satellites between small, low-cost Earth terminals using antennas of low directivity and broad beam aiming at the appropriate satellites. These satellite communications systems are now either deployed or in various stages of development and planning. For example, there are the

J. J. H. Wang; J. K. Tillery

1997-01-01

332

PLANNING AND DEVELOPMENT OF INDONESIA'S DOMESTIC COMMUNICATIONS SATELLITE SYSTEM PALAPA  

Microsoft Academic Search

On that thirty-first anniversary of Indonesian independence, the country's PALAPA domestic communication satellite system was inaugurated by President Suharto. This occasion made Indonesia the first developing country to acquire its own domestic satellite. This article aims to trace back the decision making process that led Indonesia to acquire its domestic satellite system, far ahead of other developing countries, i.e., six

Marwah Daud Ibrahim

333

Communications satellite systems operations with the space station, volume 2  

NASA Technical Reports Server (NTRS)

A financial model was developed which described quantitatively the economics of the space segment of communication satellite systems. The model describes the economics of the space system throughout the lifetime of the satellite. The expected state-of-the-art status of communications satellite systems and operations beginning service in 1995 were assessed and described. New or enhanced space-based activities and associated satellite system designs that have the potential to achieve future communications satellite operations in geostationary orbit with improved economic performance were postulated and defined. Three scenarios using combinations of space-based activities were analyzed: a spin stabilized satellite, a three axis satellite, and assembly at the Space Station and GEO servicing. Functional and technical requirements placed on the Space Station by the scenarios were detailed. Requirements on the satellite were also listed.

Price, K.; Dixon, J.; Weyandt, C.

1987-01-01

334

Ephemerides of the major Neptunian satellites determined from earth-based astrometric and Voyager imaging observations  

Microsoft Academic Search

The Voyager project used Neptunian satellite ephemerides to support both navigation and acquisition of scientific data. The development of postencounter ephemerides for the satellites Triton, Nereid, and 1989N1 is discussed. Primary results are the final set of model parameters which generate orbits that best fit both the earth-based satellite observations and data acquired by Voyager. The ephemerides are compared with

R. A. Jacobson; G. D. Lewis; W. M. Owen; J. E. Riedel; D. C. Roth; S. P. Synnott; A. H. Taylor

1990-01-01

335

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

336

Determination of long-term changes in the Earth's gravity field from satellite laser ranging observations  

Microsoft Academic Search

Temporal changes in the Earth's gravity field have been determined by analyzing satellite laser ranging (SLR) observations of eight geodetic satellites using data spanning an interval of over 20 years. The satellites used in the analysis include Starlette, LAGEOS 1 and 2, Ajisai, Etalon 1 and 2, Stella, and BE-C. Geophysical parameters, related to both secular and long-period variations in

M. K. Cheng; C. K. Shum; B. D. Tapley

1997-01-01

337

Reduced Toxicity Fuel Satellite Propulsion System  

NASA Technical Reports Server (NTRS)

A reduced toxicity fuel satellite propulsion system including a reduced toxicity propellant supply for consumption in an axial class thruster and an ACS class thruster. The system includes suitable valves and conduits for supplying the reduced toxicity propellant to the ACS decomposing element of an ACS thruster. The ACS decomposing element is operative to decompose the reduced toxicity propellant into hot propulsive gases. In addition the system includes suitable valves and conduits for supplying the reduced toxicity propellant to an axial decomposing element of the axial thruster. The axial decomposing element is operative to decompose the reduced toxicity propellant into hot gases. The system further includes suitable valves and conduits for supplying a second propellant to a combustion chamber of the axial thruster, whereby the hot gases and the second propellant auto-ignite and begin the combustion process for producing thrust.

Schneider, Steven J. (Inventor)

2001-01-01

338

The third-generation satellite laser ranging system at Shanghai Observatory  

Microsoft Academic Search

The paper describes the performance of the third-generation satellite laser ranging system at the Shanghai Observatory, Academia Sinica, and the observation summary of Lageos, Ajisai and Starlette satellites in recent two years. It has been shown that the ranging accuracy of this laser ranging system is about 5 cm (r.m.s.), by means of satellite orbital fitting and the ground target

Fu-Min Yang; De-Tong Tan; Chi-Kun Xiao; You-Ming Zhu; Xiao-Liang Shi; Zhong-De Chen; Wan-Zhen Chen; Hui-Jian He; Yong-Chun Li; Yu-Chen Wang; Jun-Min Yan; Yan-Peng Han; Hai-Chuan Yu

1990-01-01

339

Air Observe System  

E-print Network

This manuscript contains a description and basic principles for observing inaccessible areas using low cost, easily deployed equipment. The basic premise is to suspend a tiny video camera at an altitude of 10 - 200 meters over the area to be surveyed. The TV camera supports at altitude by wind or balloon. The technical challenges regard the means by which the camera is suspended. Such a system may be used by military or police forces or by civil authorities for rescue missions or assessment of natural disasters. The method may be further developed for military applications by integrating the surveillance task with deployment of munitions. Key words: air observer, air suspended system, low altitude video observer.

Alexander Bolonkin

2007-01-10

340

Payload system tradeoffs for mobile communications satellites  

NASA Technical Reports Server (NTRS)

System level trade-offs carried out during Mobile Satellite (M-SAT) design activities are described. These trade-offs relate to the use of low level beam forming, flexible power and spectrum distribution, and selection of the number of beams to cover the service area. It is shown that antenna performance can be improved by sharing horns between beams using a low level beam forming network (BFN). Additionally, greatly increased power utilization is possible using a hybrid matrix concept to share power between beams.

Moody, H. J.

1990-01-01

341

Sentinel-2: next generation satellites for optical land observation from space  

NASA Astrophysics Data System (ADS)

The first Sentinel-2 satellites, which constitute the next generation of operational Earth observation satellites for optical land monitoring from space, are undergoing completion in the facilities at Astrium ready for launch end 2014. Sentinel-2 will feature a major breakthrough in the area of optical land observation since it will for the first time enable continuous and systematic acquisition of all land surfaces world-wide with the Multi-Spectral Instrument (MSI), thus providing the basis for a truly operational service. Flying in the same orbital plane and spaced at 180, the constellation of two satellites, designed for an in-orbit nominal operational lifetime of 7 years each, will acquire all land surfaces in only 5 days at the equator. In order to support emergency operations, the satellites can further be operated in an extended observation mode allowing to image any point on Earth even on a daily basis. MSI acquires images in 13 spectral channels from Visible-to-Near Infrared (VNIR) to Short Wave Infrared (SWIR) with a swath of almost 300 km on ground and a spatial resolution up to 10 m. The data ensure continuity to the existing data sets produced by the series of Landsat and SPOT satellites, and will further provide detailed spectral information to enable derivation of biophysical or geophysical products. Excellent geometric image quality performances are achieved with geolocation better than 16 m, thanks to an innovative instrument design in conjunction with a high-performance satellite AOCS subsystem centered around a 2-band GPS receiver, high-performance star trackers and a fiberoptic gyro. To cope with the high data volume on-board, data are compressed using a state-of-the-art wavelet compression scheme. Thanks to a powerful mission data handling system built around a newly developed very large solid-state mass memory based on flash technology, on-board compression losses will be kept to a minimum. The Sentinel-2 satellite design features a highly flexible operational concept, allowing downlink of all mission data to a nominal X-band core ground stations network. In addition, users could receive mission data sets at selected X-band local user ground stations or through an Optical Communication Payload (OCP) via an inter-orbit optical link to a geostationary EDRS relay satellite at Ka-band user ground stations. Different priority schemes can be selected in flight to allow transmission of critical image data with the shortest possible latency. The system is designed for high system autonomy allowing for pre-programming of the operational schedule for 15 days in advance without interference from ground. Apart from the nominal and extended imaging modes, the satellites also feature a calibration mode to support regular in-orbit radiometric calibration of the instrument. Overall, the Sentinel- 2 satellites are designed to provide in-orbit availability for the instrument data greater than 97%, which fulfills the requirements of a fully operational system for multispectral Earth observation.

Lautenschlger, G.; Gessner, R.; Gockel, W.; Haas, C.; Schweickert, G.; Bursch, S.; Welsch, M.; Sontag, H.

2013-10-01

342

Spatial Cloud Detection and Retrieval System for Satellite Images  

Microsoft Academic Search

In last the decade we witnessed a large increase in data generated by earth observing satellites. Hence, intelligent processing of the huge amount of data received by hundreds of earth receiving stations, with specific satellite image oriented approaches, presents itself as a pressing need. One of the most important steps in earlier stages of satellite image processing is cloud detection.

Noureldin Laban; Ayman Nasr; Alf Maskan; Motaz ElSaban; Hoda Onsi

2012-01-01

343

Influence of inhomogeneous cloud fields on optical properties retrieved from satellite observations  

Microsoft Academic Search

Analyses of solar radiation exchanges between the atmosphere and clouds are vital for the understanding of climate processes and cycles. Comparisons of satellite-to-satellite or satellite-to-ground-truth observations aiming at, elucidating the radiative behavior of atmospheric components (clouds, aerosols, gas, etc.), or validating data of a particular satellite are a common practice in global radiation investigations. In order to assess the quality

Jules R. Dim; Tamio Takamura; Itaru Okada; Takashi Y. Nakajima; Hideaki Takenaka

2007-01-01

344

A Recommendation on SLR Ranging to Future Global Navigation Satellite Systems  

Microsoft Academic Search

The multi-agency US Geodetic Requirements Working Group has recommended that Satellite Laser Retro- reflectors be installed on GPS III satellites as a principal component of the Positioning, Navigation, and Timing mandate of the Global Positioning System. The Working Group, which includes NASA, NGA, NOAA, NRL, USGS, and the USNO, echoes the Global Geodetic Observing System recommendation that SLR retro- reflectors

J. L. Labrecque; J. J. Miller; M. Pearlman

2008-01-01

345

Observations of satellite environment on ETS-V of Japan  

NASA Astrophysics Data System (ADS)

This paper present the results of space and spacecraft environment measurements from the Technical Acquisition Equipment (TEDA) on the Engineering TEST Satellite-V (ETS-V). An empirical model is proposed to analyze the characteristics of spacecraft environments.

Nishimoto, Hironobu; Matsumoto, Haruhisa; Fukuda, Toshiyuki

346

An observational philosophy for GEOS-C satellite altimetry  

NASA Technical Reports Server (NTRS)

The parameters necessary for obtaining a 10 cm accuracy for GEOS-C satellite altimetry are outlined. These data include oceanographic parameters, instrument calibration, pulse propagation, sea surface effects, and optimum design.

Weiffenbach, G. C.

1972-01-01

347

Observing ocean heat content using satellite gravity and altimetry  

E-print Network

with satellite measurements of the Earth's time-varying gravity to give improved estimates of the ocean's heat: Physical: Sea level variations; 1223 Geodesy and Gravity: Ocean/Earth/atmosphere interactions (3339); 1227

Jayne, Steven

348

Satellite Observation of Surface Forcing Over the Warm Pool  

NASA Technical Reports Server (NTRS)

Daily variations of wind and solar forcing derived from satellite data were compared with sea surface temperature and temperature tendency during the Tropical Ocean Global Atmosphere - Coupled Ocean Atmosphere Response Experiment.

Liu, W. T.; Gautier, C.; Landsfeld, M.; Tang, W.

1994-01-01

349

Advanced microelectronics technologies for future small satellite systems  

NASA Astrophysics Data System (ADS)

Future small satellite systems for both Earth observation as well as deep-space exploration are greatly enabled by the technological advances in deep sub-micron microelectronics technologies. Whereas these technological advances are being fueled by the commercial (non-space) industries, more recently there has been an exciting new synergism evolving between the two otherwise disjoint markets. In other words, both the commercial and space industries are enabled by advances in low-power, highly integrated, miniaturized (low-volume), lightweight, and reliable real-time embedded systems. Recent announcements by commercial semiconductor manufacturers to introduce Silicon On Insulator (SOI) technology into their commercial product lines is driven by the need for high-performance low-power integrated devices. Moreover, SOI has been the technology of choice for many space semiconductor manufacturers where radiation requirements are critical. This technology has inherent radiation latch-up immunity built into the process, which makes it very attractive to space applications. In this paper, we describe the advanced microelectronics and avionics technologies under development by NASA's Deep Space Systems Technology Program (also known as X2000). These technologies are of significant benefit to both the commercial satellite as well as the deep-space and Earth orbiting science missions. Such a synergistic technology roadmap may truly enable quick turn-around, low-cost, and highly capable small satellite systems for both Earth observation as well as deep-space missions.

Alkalai, Leon

2000-03-01

350

Advanced Microelectronics Technologies for Future Small Satellite Systems  

NASA Technical Reports Server (NTRS)

Future small satellite systems for both Earth observation as well as deep-space exploration are greatly enabled by the technological advances in deep sub-micron microelectronics technologies. Whereas these technological advances are being fueled by the commercial (non-space) industries, more recently there has been an exciting new synergism evolving between the two otherwise disjointed markets. In other words, both the commercial and space industries are enabled by advances in low-power, highly integrated, miniaturized (low-volume), lightweight, and reliable real-time embedded systems. Recent announcements by commercial semiconductor manufacturers to introduce Silicon On Insulator (SOI) technology into their commercial product lines is driven by the need for high-performance low-power integrated devices. Moreover, SOI has been the technology of choice for many space semiconductor manufacturers where radiation requirements are critical. This technology has inherent radiation latch-up immunity built into the process, which makes it very attractive to space applications. In this paper, we describe the advanced microelectronics and avionics technologies under development by NASA's Deep Space Systems Technology Program (also known as X2000). These technologies are of significant benefit to both the commercial satellite as well as the deep-space and Earth orbiting science missions. Such a synergistic technology roadmap may truly enable quick turn-around, low-cost, and highly capable small satellite systems for both Earth observation as well as deep-space missions.

Alkalai, Leon

1999-01-01

351

Satellite observation of atmosphere and surface interaction parameters  

NASA Technical Reports Server (NTRS)

Atmosphere and ocean surface parameters are being derived from weather satellite data acquired by the High Resolution Infrared Sounder and the Microwave Sounding Unit. In this paper, the global distribution and accuracy of the derived parameters are described, and the satellite-derived skin surface temperature is compared with available shelter temperature. Seasonal and interannual changes are examined to study the response time of large-scale atmospheric changes to changes in surface conditions.

Chahine, Moustafa T.; Haskins, Robert D.; Susskind, Joel; Reuter, Dennis

1987-01-01

352

Current Sounding Capability From Satellite Meteorological Observation With Ultraspectral Infrared Instruments  

NASA Technical Reports Server (NTRS)

Ultraspectral resolution infrared spectral radiance obtained from near nadir observations provide atmospheric, surface, and cloud property information. The intent of the measurement of tropospheric thermodynamic state and trace abundances is the initialization of climate models and the monitoring of air quality. The NPOESS Airborne Sounder Testbed-Interferometer (NAST-I), designed to support the development of future satellite temperature and moisture sounders, aboard high altitude aircraft has been collecting data throughout many field campaigns. An advanced retrieval algorithm developed with NAST-I is now applied to satellite data collected with the Atmospheric InfraRed Sounder (AIRS) on the Aqua satellite launched on 4 May 2002 and the Infrared Atmospheric Sounding Interferometer (IASI) on the MetOp satellite launched on October 19, 2006. These instruments possess an ultra-spectral resolution, for example, both IASI and NAST-I have 0.25 cm-1 and a spectral coverage from 645 to 2760 cm-1. The retrieval algorithm with a fast radiative transfer model, including cloud effects, is used for atmospheric profile and cloud parameter retrieval. The physical inversion scheme has been developed, dealing with cloudy as well as cloud-free radiance observed with ultraspectral infrared sounders, to simultaneously retrieve surface, atmospheric thermodynamic, and cloud microphysical parameters. A fast radiative transfer model, which applies to the clouded atmosphere, is used for atmospheric profile and cloud parameter retrieval. A one-dimensional (1-d) variational multi-variable inversion solution is used to improve an iterative background state defined by an eigenvector-regression-retrieval. The solution is iterated in order to account for non-linearity in the 1-d variational solution. It is shown that relatively accurate temperature and moisture retrievals can be achieved below optically thin clouds. For optically thick clouds, accurate temperature and moisture profiles down to cloud top level are obtained. For both optically thin and thick cloud situations, the cloud top height can be retrieved with relatively high accuracy (i.e., error less than 1 km). Retrievals of atmospheric soundings, surface properties, and cloud microphysical properties with the AIRS and IASI observations are obtained and presented. These retrievals are further inter-compared with those obtained from airborne FTS system, such as the NPOESS Airborne Sounder Testbed? Interferometer (NAST I), dedicated dropsondes, radiosondes, and ground based Raman Lidar. The capabilities of satellite ultra-spectral sounder such as the AIRS and IASI are investigated. These advanced satellite ultraspectral infrared instruments are now playing an important role in satellite meteorological observation for numerical weather prediction.

Zhou, Daniel K.; Liu, Xu; Larar, Allen M.

2008-01-01

353

National Satellite Forest Monitoring systems for REDD+  

NASA Astrophysics Data System (ADS)

Reducing Emissions from Deforestation and Forest Degradation (REDD) is an effort to create a financial value for the carbon stored in forests, offering incentives for developing countries to reduce emissions from forested lands and invest in low-carbon paths to sustainable development. "REDD+" goes beyond deforestation and forest degradation, and includes the role of conservation, sustainable management of forests and enhancement of forest carbon stocks. In the framework of getting countries ready for REDD+, the UN-REDD Programme assists developing countries to prepare and implement national REDD+ strategies. For the monitoring, reporting and verification, FAO supports the countries to develop national satellite forest monitoring systems that allow for credible measurement, reporting and verification (MRV) of REDD+ activities. These are among the most critical elements for the successful implementation of any REDD+ mechanism. The UN-REDD Programme through a joint effort of FAO and Brazil's National Space Agency, INPE, is supporting countries to develop cost- effective, robust and compatible national monitoring and MRV systems, providing tools, methodologies, training and knowledge sharing that help countries to strengthen their technical and institutional capacity for effective MRV systems. To develop strong nationally-owned forest monitoring systems, technical and institutional capacity building is key. The UN-REDD Programme, through FAO, has taken on intensive training together with INPE, and has provided technical help and assistance for in-country training and implementation for national satellite forest monitoring. The goal of the support to UN-REDD pilot countries in this capacity building effort is the training of technical forest people and IT persons from interested REDD+ countries, and to set- up the national satellite forest monitoring systems. The Brazilian forest monitoring system, TerraAmazon, which is used as a basis for this initiative, allows countries to adapt it to country needs and the training on the TerraAmazon system is a tool to enhance existing capacity on carbon monitoring systems. The support with the National Forest Monitoring System will allow these countries to follow all actions related to the implementation of its national REDD+ policies and measures. The monitoring system will work as a platform to obtain information on their REDD+ results and actions, related directly or indirectly to national REDD+ strategies and may also include actions unrelated to carbon assessment, such as forest law enforcement. With the technical assistance of FAO, INPE and other stakeholders, the countries will set up an autonomous operational forest monitoring system. An initial version and the methodologies of the system for DRC and PNG has been launched in Durban, South Africa during COP 17 and in 2012 Paraguay, Viet Nam and Zambia will be launched in Doha, Qatar at COP 18. The access to high-quality satellite data for these countries is crucial for the set-up.

Jonckheere, I. G.

2012-12-01

354

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.; Sma, 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

355

Detailed Analysis of Indian Summer Monsoon Rainfall Processes with Modern/High-Quality Satellite Observations  

NASA Technical Reports Server (NTRS)

We examine, in detail, Indian Summer Monsoon rainfall processes using modernhigh quality satellite precipitation measurements. The focus here is on measurements derived from three NASA cloud and precipitation satellite missionslinstruments (TRMM/PR&TMI, AQUNAMSRE, and CLOUDSATICPR), and a fourth TRMM Project-generated multi-satellite precipitation measurement dataset (viz., TRMM standard algorithm 3b42) -- all from a period beginning in 1998 up to the present. It is emphasized that the 3b42 algorithm blends passive microwave (PMW) radiometer-based precipitation estimates from LEO satellites with infi-ared (IR) precipitation estimates from a world network of CEO satellites (representing -15% of the complete space-time coverage) All of these observations are first cross-calibrated to precipitation estimates taken from standard TRMM combined PR-TMI algorithm 2b31, and second adjusted at the large scale based on monthly-averaged rain-gage measurements. The blended approach takes advantage of direct estimates of precipitation from the PMW radiometerequipped LEO satellites -- but which suffer fi-om sampling limitations -- in combination with less accurate IR estimates from the optical-infrared imaging cameras on GEO satellites -- but which provide continuous diurnal sampling. The advantages of the current technologies are evident in the continuity and coverage properties inherent to the resultant precipitation datasets that have been an outgrowth of these stable measuring and retrieval technologies. There is a wealth of information contained in the current satellite measurements of precipitation regarding the salient precipitation properties of the Indian Summer Monsoon. Using different datasets obtained from the measuring systems noted above, we have analyzed the observations cast in the form of: (1) spatially distributed means and variances over the hierarchy of relevant time scales (hourly I diurnally, daily, monthly, seasonally I intra-seasonally, and inter-annually), (2) time series at these different time scales taken as area-averages over the hierarchy of relevant space scales (Indian sub-Division, Indian sub-continent, and Circumambient Indian Ocean), (3) principal autocorrelation and cross-correlation structures over various monsoon space-time domains, (4) diurnally modulated amplitude-phase properties of rain rates over different monsoon space-time domains, (5) foremost rain rate probability distributions intrinsic to monsoon precipitation, and (6) behavior of extreme events including occurrences of flood and drought episodes throughout the course of inter-annual monsoon processes.

Smith, Eric A.; Kuo, Kwo-Sen; Mehta, Amita V.; Yang, Song

2007-01-01

356

Retrieval of Aerosol Absorption Properties from Satellite Observations  

NASA Technical Reports Server (NTRS)

The Angstrom Absorption Exponent (AAE) is a parameter commonly used to characterize the wavelength-dependence of aerosol absorption optical depth (AAOD). It is closely related to aerosol composition. Black carbon (BC) containing aerosols yield AAE values near unity whereas Organic carbon (OC) aerosol particles are associated with values larger than 2. Even larger AAE values have been reported for desert dust aerosol particles. Knowledge of spectral AAOD is necessary for the calculation of direct radiative forcing effect of aerosols and for inferring aerosol composition. We have developed a satellitebased method of determining the spectral AAOD of absorbing aerosols. The technique uses multi-spectral measurements of upwelling radiation from scenes where absorbing aerosols lie above clouds as indicated by the UV Aerosol Index. For those conditions, the satellite measurement can be explained, using an approximations of Beer's Law (BL), as the upwelling reflectance at the cloud top attenuated by the absorption effects of the overlying aerosol layer. The upwelling reflectance at the cloud-top in an aerosol-free atmospheric column is mainly a function of cloud optical depth (COD). In the proposed method of AAE derivation, the first step is determining COD which is retrieved using a previously developed color-ratio based approach. In the second step, corrections for molecular scattering effects are applied to both the observed ad the calculated cloud reflectance terms, and the spectral AAOD is then derived by an inversion of the BL approximation. The proposed technique will be discussed in detail and application results making use of OMI multi-spectral measurements in the UV-Vis. will be presented.

Torres, Omar; Bhartia, Pawan K.; Jethva, H.; Ahn, Chang-Woo

2012-01-01

357

Oral Reading Observation System Observer's Training Manual.  

ERIC Educational Resources Information Center

A self-instructional program for use by teachers of the handicapped, this training manual was developed to teach accurate coding with the Oral Reading Observation System (OROS)an observation system designed to code teacher-pupil verbal interaction during oral reading instruction. The body of the manual is organized to correspond to the nine

Brady, Mary Ella; And Others

358

Improved monitoring of surface ozone by joint assimilation of geostationary satellite observations of ozone and CO  

NASA Astrophysics Data System (ADS)

Future geostationary satellite observations of tropospheric ozone aim to improve monitoring of surface ozone air quality. However, ozone retrievals from space have limited sensitivity in the lower troposphere (boundary layer). Data assimilation in a chemical transport model can propagate the information from the satellite observations to provide useful constraints on surface ozone. This may be aided by correlated satellite observations of carbon monoxide (CO), for which boundary layer sensitivity is easier to achieve. We examine the potential of concurrent geostationary observations of ozone and CO to improve constraints on surface ozone air quality through exploitation of ozone-CO model error correlations in a joint data assimilation framework. The hypothesis is that model transport errors diagnosed for CO provide information on corresponding errors in ozone. A paired-model analysis of ozone-CO error correlations in the boundary layer over North America in summer indicates positive error correlations in continental outflow but negative regional-scale error correlations over land, the latter reflecting opposite sensitivities of ozone and CO to boundary layer depth. Aircraft observations from the ICARTT campaign are consistent with this pattern but also indicate strong positive error correlations in fine-scale pollution plumes. We develop a joint ozone-CO data assimilation system and apply it to a regional-scale Observing System Simulation Experiment (OSSE) of the planned NASA GEO-CAPE geostationary mission over North America. We find substantial benefit from joint ozone-CO data assimilation in informing US ozone air quality if the instrument sensitivity for CO in the boundary layer is greater than that for ozone. A high-quality geostationary measurement of CO could potentially relax the requirements for boundary layer sensitivity of the ozone measurement. This is contingent on accurate characterization of ozone-CO error correlations. A finer-resolution data assimilation system resolving the urban scale would need to account for the change in sign of the ozone-CO error correlations between urban pollution plumes and the regional atmosphere.

Zoogman, Peter; Jacob, Daniel J.; Chance, Kelly; Worden, Helen M.; Edwards, David P.; Zhang, Lin

2014-02-01

359

Engineering calculations for communications satellite systems planning  

NASA Technical Reports Server (NTRS)

A procedure is described that was used to calculate minimum required satellite separations based on total link carrier to interference requirements. Also summarized are recent results with a switching algorithm for satellite synthesis problems. Analytic solution value bounds for two of the satellite synthesis models studied are described. Preliminary results from an empirical study of alternate mixed integer programming models for satellite synthesis are presented. Research plans for the near future are discussed.

Reilly, Charles H.; Walton, Eric K.; Kohnhorst, Paul

1987-01-01

360

The precision of today's satellite laser ranging systems  

NASA Technical Reports Server (NTRS)

Recent improvements in the accuracy of modern satellite laser ranging (SLR) systems are strengthened by the new capability of many instruments to track an increasing number of geodetic satellite targets without significant scheduling conflict. This will allow the refinement of some geophysical parameters, such as solid Earth tidal effects and GM, and the improved temporal resolution of others, such as Earth orientation and station position. Better time resolution for the locations of fixed observatories will allow us to monitor more subtle motions at the stations, and transportable systems will be able to provide indicators of long term trends with shorter occupations. If we are to take advantage of these improvements, care must be taken to preserve the essential accuracy of an increasing volume of range observations at each stage of the data reduction process.

Dunn, Peter J.; Torrence, Mark H.; Hussen, Van S.; Pearlman, Michael R.

1993-01-01

361

Space Weathering on Icy Satellites in the Outer Solar System  

NASA Astrophysics Data System (ADS)

Space weathering produces well-known optical effects in silicate minerals in the inner Solar System, for example, on the Moon. Space weathering from solar wind and UV is expected to be weaker in the outer Solar System simply because intensities are lower. However, cosmic rays from inner to outer solar system would be similar to first order. Similarly with micrometeoroid bombardment. That, combined with the much higher volatility of icy surfaces means there is the potential for space weathering on icy outer Solar System surfaces to show optical effects. The Cassini spacecraft orbiting Saturn is providing evidence for space weathering on icy bodies. The Cassini VIMS instrument has spatially mapped satellite surfaces and the rings from .35-5 microns and the UVIS instrument from 0.1 to 0.2 microns. These data have sampled a complex mixing space between H2O ice and non-ice components and they show some common spectral properties. Similarly, spectra of the icy Galilean satellites and satellites in the Uranian system have some commonality in spectral properties with those in the Saturn system. The UV absorber is spectrally similar on many surfaces. VIMS has identified CO2, H2 and trace organics in varying abundances on Saturn's satellites. We postulate that through the spatial relationships of some of these compounds that they are created and destroyed through space weathering effects. For example, the trapped H2 and CO2 observed by VIMS in regions with high concentrations of dark material may in part be space weathering products from the destruction of H2O and organic molecules. The dark material, particularly on Iapetus which has the highest concentration in the Saturn system, is well matched by space-weathered silicates in the .4-2.6 micron range, and the spectral shapes closely match those of the most mature lunar soils, another indicator of space weathered material.

Clark, Roger N.; Perlman, Zachary; Pearson, Neil; Cruikshank, Dale P.

2014-11-01

362

KUPON spacecraft of Bankir satellite communication and data transmitting system  

Microsoft Academic Search

The KUPON spacecraft is designed for data retranslation (data transmission, telefax, telephone) between subscribers of the satellite communication network. It was developed for the Bankir satellite communication and data transmitting system of the Central Bank of Russian Federation. The spacecraft was designed on the basis of the Lavochkin satellite communications. That has led to a decrease in terms of development

S. D. Koulikov; K. M. Pitchkhadze; V. I. Makarov; V. I. Kouznetsov

1998-01-01

363

The AMSC mobile satellite system: Design summary and comparative analysis  

Microsoft Academic Search

Mobile satellite communications will be provided in the United States by the American Mobile Satellite Consortium (AMSC). Telesat Mobile, Inc. (TMI) and AMSC are jointly developing MSAT, the first regional Mobile Satellite Service (MSS) system. MSAT will provide diverse mobile communications services - including voice, data and position location - to mobiles on land, water, and in the air throughout

Gary K. Noreen

1989-01-01

364

International Global Navigation Satellite Systems Society IGNSS Symposium 2011  

E-print Network

in frequency of the GPS signal because of the relative movement of satellite and receiver) and 3) the alignment. The Doppler shift depends on the relative movement of the satellite and the receiver. If this is not knownInternational Global Navigation Satellite Systems Society IGNSS Symposium 2011 University of New

Sekercioglu, Y. Ahmet

365

Cirrus cloud-temperature interactions over a tropical station, Gadanki from lidar and satellite observations  

NASA Astrophysics Data System (ADS)

The cirrus clouds play an important role in the radiation budget of the earth's atmospheric system and are important to characterize their vertical structure and optical properties. LIDAR measurements are obtained from the tropical station Gadanki (13.50 N, 79.20 E), India, and meteorological indicators derived from Radiosonde data. Most of the cirrus clouds are observed near to the tropopause, which substantiates the strength of the tropical convective processes. The height and temperature dependencies of cloud height, optical depth, and depolarization ratio were investigated. Cirrus observations made using CALIPSO satellite are compared with lidar data for systematic statistical study of cirrus climatology.

S, Motty G.; Satyanarayana, M.; Krishnakumar, V.; Dhaman, Reji k.

2014-10-01

366

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

367

MY NASA DATA Lesson Plan: Storm Clouds-Fly over a Late Winter Storm onboard a NASA Earth Observing Satellite  

NSDL National Science Digital Library

: This lesson plan uses Clouds and Earth's Radiant Energy System (CERES) cloud data and a weather map to explore cloud coverage during a winter storm. When atmospheric scientists, including meteorologists, study weather patterns, they may use several different sources of information. For example, in studying storm patterns, they may use a combination of Earth Observing Satellite data, such as from CERES, or NOAA weather satellite imagery, and geographical tools to determine locations and paths of storms. As one part of the training to analyze this data and imagery, scientists look at 'case studies' such as the late winter storm shown in the weather satellite imagery included with the lesson. An infrared satellite image looks at the temperature. Cold things (like high clouds) are very bright. Warm things (like Mexico and Florida) are dark. The imagery can be compared to data collected by other satellites, so that improved models of storm patterns can be developed.

2006-01-01

368

System test approach for the SAX satellite  

NASA Technical Reports Server (NTRS)

SAX satellite verification is based on a protoflight approach, in which only one system model is realized at flight standard level, taking into account the utilization of hardware already qualified for other space programs and the necessity to respect the schedule constraints for a scientific objective. In any case, this approach was tailored with some deviations in order to reduce risks inherent in such a choice. The protoflight approach was also pursued at subsystem/unit level in particular for those subsystems and units considered critical from the schedule point of view. Payload Instruments followed the same approach but complete spare units were developed to reduce the risks associated with such an approach. A description of the model philosophy is provided and then, at satellite level, the testing approach and rationale for each model is presented. Finally, a brief description of each test will be given, highlighting objectives, methodologies, and test configurations. Moreover, for the major tests, problems encountered and solutions applied in establishing a correct approach are described.

Giordano, Pietro; Raimondo, Giacomo; Messidoro, Piero

1992-01-01

369

Ionospheric electron density irregularities observed by satellite-to-satellite, dual-frequency, low-low Doppler tracking link  

NASA Technical Reports Server (NTRS)

A low-low, satellite-to-satellite, dual-frequency, Doppler tracking experiment was performed. The data are analyzed here for irregularities in electron density at the altitude of 212 km. The differential Doppler data with the relative motion term removed are integrated to obtain a representation of the electron density variation along the satellite path. Well-known large-scale features such as the equatorial geomagnetic anomaly and day/night ionization level differences are clearly observed in the integrated data. The larger crest of the morning geomagnetic anomaly is seen to occur in the southern (winter) hemisphere in agreement with previous observations. In addition, a sharp peak in the electron density at the day-to-night transition point is observed in two consecutive revolutions. This effect may be due to the previously postulated atmospheric shock wave generated by supersonic motion of the terminator.

Estes, R. D.; Grossi, M. D.

1984-01-01

370

Ameliorating uncertainties in satellite-derived rainfall using GRACE observations over the Congo Basin  

NASA Astrophysics Data System (ADS)

The Congo River has the second largest drainage area in the world, making it very important for the water resources of Africa. Nevertheless, the sparsity of measurements has made the study and modeling of water resources over the basin very difficult and reliant on satellite remote sensing. The Hillslopes River Routing (HRR) model was used to simulate hydrological states and fluxes over the Congo River basin, driven by a TRMM rainfall data product. However, errors in the satellite-derived rainfall, which vary both spatially and temporally, propagate through the model and result in errors in the simulated streamflow and water storage. The GRACE satellite provides measurements of variations of the Earth's gravity field, which can be translated to variations of water storage over large-scale basins. We evaluate a data assimilation system that ingests GRACE water storage variation observations into the HRR model to potentially correct errors in the TRMM precipitation. The data assimilation algorithm, an Ensemble Kalman Filter (EnKF), is able to improve HRR water storage and streamflow predictions when compared with the actual GRACE observations as well as gauge and ENVIsat measurements over select sites, by updating the model rainfall inputs. Additionally, we examine the sensitivity of the rainfall estimates with spatial and temporal scales, i.e. the information content of GRACE observations with respect to estimating TRMM errors. Finally, a Bayesian framework is explored in order to identify the error components that correspond to the HRR parameterization and TRMM inputs.

Andreadis, Konstantinos; Beighley, Edward; Lee, Hyongki; He, Yiping; Alsdorf, Doug; Shum, C. K.

2010-05-01

371

Improving the Transition of Earth Satellite Observations from Research to Operations  

NASA Technical Reports Server (NTRS)

There are significant gaps between the observations, models, and decision support tools that make use of new data. These challenges include: 1) Decreasing the time to incorporate new satellite data into operational forecast assimilation systems, 2) Blending in-situ and satellite observing systems to produce the most accurate and comprehensive data products and assessments, 3) Accelerating the transition from research to applications through national test beds, field campaigns, and pilot demonstrations, and 4) Developing the partnerships and organizational structures to effectively transition new technology into operations. At the Short-term Prediction Research and Transition (SPORT) Center in Huntsville, Alabama, a NASA-NOAA-University collaboration has been developed to accelerate the infusion of NASA Earth science observations, data assimilation and modeling research into NWS forecast operations and decision-making. The SPoRT Center research focus is to improve forecasts through new observation capability and the regional prediction objectives of the US Weather Research Program dealing with 0-1 day forecast issues such as convective initiation and 24-hr quantitative precipitation forecasting. The near real-time availability of high-resolution experimental products of the atmosphere, land, and ocean from the Moderate Resolution Imaging Spectroradiometer (MODIS), the Advanced Infrared Spectroradiometer (AIRS), and lightning mapping systems provide an opportunity for science and algorithm risk reduction, and for application assessment prior to planned observations from the next generation of operational low Earth orbiting and geostationary Earth orbiting satellites. This paper describes the process for the transition of experimental products into forecast operations, current products undergoing assessment by forecasters, and plans for the future. The SPoRT Web page is at (http://www.ghcc.msfc.nasa.gov/sport).

Goodman, Steven J.; Lapenta, William M.; Jedlovec, Gary J.

2004-01-01

372

New Constraints on Additional Satellites of the Pluto System  

E-print Network

Observations of Pluto and its solar-tidal stability zone were made using the Advanced Camera for Surveys' (ACS) Wide Field Channel (WFC) on the Hubble Space Telescope on UT 2005 May 15 and UT 2005 May 18. Two small satellites of Pluto, provisionally designated S/2005 P 1 and S/2005 P 2, were discovered, as discussed by Weaver et al. (2006) and Stern et al. (2006a). Confirming observations of the newly discovered moons were obtained using the ACS in the High Resolution Channel (HRC) mode on 2006 Feb 15 (Mutchler et al. 2006). Both sets of observations provide strong constraints on the existence of any additional satellites in the Pluto system. Based on the May 2005 observations using the ACS/WFC, we place a 90%-confidence lower limit of m_V = 26.8 (m_V = 27.4 for a 50%-confidence lower limit) on the magnitude of undiscovered satellites greater than 5" (1.1x10^5 km) from Pluto. Using the 2005 Feb 15 ACS/HRC observations we place 90%-confidence lower limits on the apparent magnitude of any additional satellites of m_V = 26.4 between 3"-5" (6.9x10^4-1.1x10^5 km) from Pluto, m_V = 25.7 between 1"-3" (2.3x10^4-6.9x10^4 km) from Pluto, and m_V = 24. between 0.3"-1" (6.9x10^3-2.3x10^4 km) from Pluto. The 90%-confidence magnitude limits translate into upper limits on the diameters of undiscovered satellites of 29 km outside of 5" from Pluto, 36 km between 3"-5" from Pluto, 49 km between 1"-3" from Pluto, and 115 km between 0.3"-1" for a comet-like albedo of p_V = 0.04. If potential satellites are assumed to have a Charon-like albedo of p_V = 0.38, the diameter limits are 9 km, 12 km, 16 km, and 37 km, respectively.

A. J. Steffl; M. J. Mutchler; H. A. Weaver; S. A. Stern; D. D. Durda; D. Terrell; W. J. Merline; L. A. Young; E. F. Young; M. W. Buie; J. R. Spencer

2005-11-30

373

Observations in the thermal IR and visible of a retired satellite in the graveyard orbit, and comparisons to active satellites in GEO  

NASA Astrophysics Data System (ADS)

There exists a population of defunct satellites in the geo-stationary arc that potentially pose a hazard to current and future operational satellites. These drifting, non-station-kept objects have a variety of ages and sizes, and many are trapped in libration orbits around the Earth's two gravitational potential wells (the non-spherical nature of the Earth gives rise to two geo-potential wells or stable points that affect objects in geostationary and geosynchronous orbits), whereas others were boosted to higher altitudes into so-called graveyard orbits. We have observed several of the approximately 49 objects in libration orbits about the Western stable point (R. Choc, T. Flohrer, and B. Bastida, Classification of Geosynchronous Objects, Issue 13, ESA/ESOC, February 2011), as well as objects in graveyard orbits. We have carried out an observational campaign utilizing The Aerospace Corporation's 3-13 ?m Broadband Array Spectrograph System (BASS), as well as with several optical sensors to collect data on a representative sample of these objects at a variety of solar phase angles. Here we report on recent BASS observations of a retired satellite in the graveyard orbit, and compare them with data we had collected over six years ago, while the satellite was still active. Data are also presented on similar satellites that are still active. We describe our methods, the data collected, our results, and our future plans.

Skinner, Mark A.; Russell, Ray W.; Kelecy, Tom; Gregory, Steve; Rudy, Richard J.; Kim, Daryl L.; Crawford, Kirk

2014-12-01

374

The Three-dimensional Structure of the M31 Satellite System; Strong Evidence for an Inhomogeneous Distribution of Satellites  

NASA Astrophysics Data System (ADS)

We undertake an investigation into the spatial structure of the M31 satellite system utilizing the distance distributions presented in a previous publication. These distances make use of the unique combination of depth and spatial coverage of the Pan-Andromeda Archaeological Survey to provide a large, homogeneous sample consisting of 27 of M31's satellites, as well as M31 itself. We find that the satellite distribution, when viewed as a whole, is no more planar than one would expect from a random distribution of equal size. A disk consisting of 15 of the satellites is however found to be highly significant, and strikingly thin, with an rms thickness of just 12.34^{+0.75}_{-0.43} kpc. This disk is oriented approximately edge-on with respect to the Milky Way and almost perpendicular to the Milky Way disk. It is also roughly orthogonal to the disk-like structure regularly reported for the Milky Way satellite system and in close alignment with M31's Giant Stellar Stream. A similar analysis of the asymmetry of the M31 satellite distribution finds that it is also significantly larger than one would expect from a random distribution. In particular, it is remarkable that 20 of the 27 satellites most likely lie on the Milky Way side of the galaxy, with the asymmetry being most pronounced within the satellite subset forming the aforementioned disk. This lopsidedness is all the more intriguing in light of the apparent orthogonality observed between the satellite disk structures of the Milky Way and M31.

Conn, A. R.; Lewis, G. F.; Ibata, R. A.; Parker, Q. A.; Zucker, D. B.; McConnachie, A. W.; Martin, N. F.; Valls-Gabaud, D.; Tanvir, N.; Irwin, M. J.; Ferguson, A. M. N.; Chapman, S. C.

2013-04-01

375

TOWARDS USING SATELLITE ALTIMETRY FOR THE OBSERVATION OF COASTAL DYNAMICS.  

E-print Network

but is currently unexploited. Indeed, near coasts, the use of standard satellite altimetric products is challenging and Hydrosphere (CTOH) are developing and testing a new altimetric data processing approach in the coastal zone strategy. The latter consists in eliminating not only flagged data, but also the neighbouring ones which

376

Validation of radiometric standards for the laboratory calibration of reflected-solar Earth-observing satellite instruments  

Microsoft Academic Search

Historically, the traceability of the laboratory calibration of Earth-observing satellite instruments to a primary radiometric reference scale (SI units) is the responsibility of each instrument builder. For the NASA Earth Observing System (EOS), a program has been developed using laboratory transfer radiometers, each with its own traceability to the primary radiance scale of a national metrology laboratory, to independently validate

James J. Butler; B. Carol Johnson; Joseph P. Rice; Steven W. Brown; Robert A. Barnes

2007-01-01

377

Retrofitting a fine-pointing system to satellite optics  

SciTech Connect

This paper describe a system that was added to an existing satellite-borne telescope design for the purpose of compensating the boresight errors that had been observed in earlier flights of similar instruments. Those errors had been found to be caused by thermal distortion of the spaceframe. This retrofit design was subject to severe volume restrictions because it was fitted into an already tightly-packaged instrument envelope. It was found practical to improve the basic design by converting a redundant structure into a statically-determinate one. It was also possible to use portions of the mechanical actuation system to facilitate the position encoding needed for computer interfacing.

Woods, R.O.

1994-12-31

378

On the geometric analysis and adjustment of optical satellite observations. M.S. Thesis  

NASA Technical Reports Server (NTRS)

Satellite geodesy methods were catagorized into three divisions: geometric, dynamic, and mixed. These catagories furnish the basis for distinction between geometric and dynamic satellite geodesy. The dual adjustment, geometric analysis, and Cartesian coodinate determination are examined for two observing stations. Similar illustrations are given when more than two observing stations are used.

Tsimis, E.

1972-01-01

379

Using Satellite Observations to Constrain Parameterizations of Gravity Wave Effects for Global Models  

Microsoft Academic Search

Small-scale gravity waves are common features in atmospheric temperature observations. In satellite observations, these waves have been traditionally difficult to resolve because the footprint or resolution of the measurements precluded their detection or clear identification. Recent advances in satellite instrument resolution coupled to innovative analysis techniques have led in the last decade to some new global datasets describing the temperature

M. Joan Alexander; Christopher Barnet

2007-01-01

380

Satellite observations of ship emission induced transitions from broken to closed cell marine stratocumulus  

E-print Network

Satellite observations of ship emission induced transitions from broken to closed cell marine during 42 h demonstrated that ship emissions are able to convert a marine stratocumulus regime of open (2012), Satellite observations of ship emission induced transitions from broken to closed cell marine

Daniel, Rosenfeld

381

Reconstruction of a flux transfer event based on observations from five THEMIS satellites  

E-print Network

Reconstruction of a flux transfer event based on observations from five THEMIS satellites A. T. Y a flux transfer event (FTE) observed by Time History of Events and Macroscale Interactions during transfer event (FTE) near the dusk magnetopause on 20 May 2007. During this interval, one THEMIS satellite

California at Berkeley, University of

382

Satellite-based observations of surface turbulent stress during severe weather  

E-print Network

Satellite-based observations of surface turbulent stress during severe weather Mark A. Bourassa The environment of severe marine weather is harsh: in situ and satellite observations of surface turbulent stresses are extremely difficult to acquire under such conditions. Even for fair weather conditions

383

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

384

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

NASA Astrophysics Data System (ADS)

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 2003 and will carry out experiments and researches in three years after the launch. In this system, National Institute of Information and Communications Technology (NICT) is mainly in charge of timing system for the satellite positioning system using QZS, such as onboard hydrogen maser atomic clock and precise time management system of the QZSS. We started to develop the engineering model of the time management system for the QZSS. The time management system for the QZSS will be used to compare time differences between QZS and earth station as well as to compare between three onboard atomic clocks. This paper introduces time management of satellite positioning system using the QZSS.

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

385

Satellites around Massive Galaxies Since z ~ 2: Confronting the Millennium Simulation with Observations  

NASA Astrophysics Data System (ADS)

Minor merging has been postulated as the most likely evolutionary path to produce the increase in size and mass observed in the massive galaxies since z ~ 2. In this Letter, we directly test this hypothesis, comparing the population of satellites around massive galaxies in cosmological simulations versus the observations. We use state-of-the-art, publically available, Millennium I and II simulations, and the associated semi-analytical galaxy catalogs to explore the time evolution of the fraction of massive galaxies that have satellites, the number of satellites per galaxy, the projected distance at which the satellites locate from the host galaxy, and the mass ratio between the host galaxies and their satellites. The three virtual galaxy catalogs considered here overproduce the fraction of galaxies with satellites by a factor ranging between 1.5 and 6 depending on the epoch, whereas the mean projected distance and ratio of the satellite mass over host mass are in closer agreement with data. The larger pull of satellites in the semi-analytical samples could suggest that the size evolution found in previous hydrodynamical simulations is an artifact due to the larger number of infalling satellites compared to the real universe. These results advise us to revise the physical ingredients implemented in the semi-analytical models in order to reconcile the observed and computed fraction of galaxies with satellites, and eventually, it would leave some room for other mechanisms explaining the galaxy size growth not related to the minor merging.

Quilis, Vicent; Trujillo, Ignacio

2012-06-01

386

Research on data relay and tracking satellite systems  

NASA Astrophysics Data System (ADS)

An overview of the study on data relay and tracking satellite systems is presented. Study was made on the following subjects: (1) users' data transmission and operation requirements were rearranged and the number of onboard antenna for intersatellite communication and on orbit satellites; (2) function and performance budget for ground stations, data relay and tracking satellites, and users' spacecraft terminals; (3) data and operation interfaces between data relay and tracking satellites, and ground stations and systems; (4) load reduction of users' spacecraft and upgrading of data relay and tracking satellites; (5) circuit quality simulation for international mutual operation and satellite separation angles required between two data relay satellites; and (6) methods of high speed data distribution to overseas organizations.

Anzai, Takao; Douura, Toshio; Nagano, Satoshi

1992-08-01

387

Warming Trends in the Arctic from Clear Sky Satellite Observations  

Microsoft Academic Search

Satellite thermal infrared data on surface temperatures provide pan-Arctic coverage from 1981 to 2001 during cloud-free conditions and reveal large warming anomalies in the 1990s compared to the 1980s and regional variability in the trend. The rms error of the derived surface temperatures when compared with in situ data ranges from 1.5 to 3 K over the 20-yr period. Average

Josefino C. Comiso

2003-01-01

388

DCS: A global satellite environmental data collection system study  

NASA Technical Reports Server (NTRS)

Cost analysis and technical feasibility data are presented on five medium orbiting and six geosynchronous satellite data collection systems with varying degrees of spacecraft and local user terminal complexity. Data are also provided on system approaches, user requirements, and user classes. Systems considered include orbiting ERTS and EOS type satellites and geosynchronous SmS and SEOS type data collectors.

1973-01-01

389

Propagation effects on satellite systems at frequencies below 10 GHz: A handbook for satellite systems design  

NASA Technical Reports Server (NTRS)

Frequencies below 10 GHz continue to be used for a large portion of satellite service, and new applications, including mobile satellite service and the global positioning system, use frequencies below 10 GHz. As frequency decreases below 10 GHz, attenuation due to precipitation and gases decreases and ionospheric effects increase. Thus the ionosphere, which can be largely neglected above 10 GHz, receives major attention. Although attenuation and depolarization due to rain are less severe below 10 GHz than above, they are nevertheless still important and constitute another major topic. The handbook emphasizes the propagation effects on satellite communications but material that is pertinent to radio navigation and positioning systems and deep-space telecommunications is included as well. Chapter 1 through 7 describe the various propagation impairments, and Chapter 9 is devoted to the estimation or calculation of the magnitudes of these effects for use in system design. Chapter 10 covers link power budget equations and the role of propagation effects in these equations. Chapter 8 deals with the complex subject of interference between space and terrestrial systems.

Flock, Warren L.

1987-01-01

390

Texstar: The all-Texas educational satellite system  

NASA Technical Reports Server (NTRS)

Longhorn Satellite Company (LSC) has designed Texstar, and educational satellite communications system which will be considered as a means of equalizing the distribution of educational resources throughout the state of Texas. Texstar will be capable of broadcasting live lectures and documentaries in addition to transmitting data from a centralized receiving-transmitting station. Included in the design of Texstar is the system and subsystem design for the satellite and the design of the ground stations. The launch vehicle used will be the Texas-built Conestoga 421-48. The Texstar system incorporates three small satellites in slightly inclined geosynchronous orbits. Due to the configuration and spacing of these satellites, the system will be accessed as if it were one large, geostationary satellite. Texstar is shown to be a viable option to the educational crisis in the state of Texas.

1990-01-01

391

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

392

Solar power satellite system definition study, volume 4, phase 2  

NASA Technical Reports Server (NTRS)

Results of an overall evaluation of the solar power satellite concept are reported. Specific topics covered include: solid state sandwich configuration; parametric development of reliability design; power distribution system for solid state solar power satellites; multibeam transmission; GEO base system configuration; suppression of the heavy lift launch vehicle trajectory; conceptual design of an offshore space center facility; solar power satellite development and operations scenario; and microwave power transmission technology, advancement, development, and facility requirements.

1979-01-01

393

Orbits design for LEO space based solar power satellite system  

NASA Astrophysics Data System (ADS)

Space Based Solar Power satellites use solar arrays to generate clean, green, and renewable electricity in space and transmit it to earth via microwave, radiowave or laser beams to corresponding receivers (ground stations). These traditionally are large structures orbiting around earth at the geo-synchronous altitude. This thesis introduces a new architecture for a Space Based Solar Power satellite constellation. The proposed concept reduces the high cost involved in the construction of the space satellite and in the multiple launches to the geo-synchronous altitude. The proposed concept is a constellation of Low Earth Orbit satellites that are smaller in size than the conventional system. 7For this application a Repeated Sun-Synchronous Track Circular Orbit is considered (RSSTO). In these orbits, the spacecraft re-visits the same locations on earth periodically every given desired number of days with the line of nodes of the spacecraft's orbit fixed relative to the Sun. A wide range of solutions are studied, and, in this thesis, a two-orbit constellation design is chosen and simulated. The number of satellites is chosen based on the electric power demands in a given set of global cities. The orbits of the satellites are designed such that their ground tracks visit a maximum number of ground stations during the revisit period. In the simulation, the locations of the ground stations are chosen close to big cities, in USA and worldwide, so that the space power constellation beams down power directly to locations of high electric power demands. The j2 perturbations are included in the mathematical model used in orbit design. The Coverage time of each spacecraft over a ground site and the gap time between two consecutive spacecrafts visiting a ground site are simulated in order to evaluate the coverage continuity of the proposed solar power constellation. It has been observed from simulations that there always periods in which s spacecraft does not communicate with any ground station. For this reason, it is suggested that each satellite in the constellation be equipped with power storage components so that it can store power for later transmission. This thesis presents a method for designing the solar power constellation orbits such that the number of ground stations visited during the given revisit period is maximized. This leads to maximizing the power transmission to ground stations.

Addanki, Neelima Krishna Murthy

394

Satellite observations and instrumentation for measuring energetic neutral atoms  

SciTech Connect

Direct measurements of energetic neutral atoms (ENA) and ions have been obtained with the cooled solid state detectors on the low-altitude (220 km) three-axis stabilized S81-1/ stimulated emissions of energetic particles (SEEP) satellite and on the spinning 400 km [times] 5.5 R[sub e] (where R[sub e] is Earth radii) Combined Release and Radiation Effects Satellite (CRRES). During magnetic storms ENA and ion precipitation (E > 10 keV) are evident over the low-altitude equatorial region based on data from the SEEP (ONR 804) spectrometers and CRRES ion mass spectrometer (IMS-HI) (ONR 307-8-3) ion composition and ENA instrument. The IMS-HI neutral atom spectrometer covers the energy range from 20 to 1,500 keV with a geometrical factor of 10[sub [minus]3] cm[sup 2] sr and uses a 7-kG magnetic field to screen out protons less than about 50 MeV. During the strong magnetic storm of 24 March 1991 the first ENA and ion mass composition measurements were obtained of ring current particles below the inner belt and these fluxes are compared to the IMS-HI flux measurements in the ring current. Recently, an advanced spectrometer, the Source/Loss-cone Energetic Particle Spectrometer (SEPS), has been developed to image electrons, ions, and neutrals on the despun platform of the POLAR satellite ([approximately]1.8 [times] 9 R[sub e]) for launch in the mid 1990s as part of NASA's International Solar Terrestrial Physics/Global Geospace Science (ISTP/GGS) program.

Voss, H.D.; Mobilia, J.; Collin, H.L.; Imhof, W.L. (Lockheed Palo Alto Research Lab., CA (United States). Space Sciences Lab.)

1993-12-01

395

Investigating Satellite Microwave observations of Precipitation in Different Climate Regimes  

NASA Astrophysics Data System (ADS)

Microwave satellite remote sensing of precipitation over land is a challenging problem due to the highly variable land surface emissivity, which, if not properly accounted for, can be much greater than the precipitation signal itself, especially in light rain/snow conditions. Additionally, surfaces such as arid land, deserts and snow cover have brightness temperature characteristics similar to precipitation Ongoing work by GPM microwave radiometer team is constructing databases through a variety of means, however, there is much uncertainty as to what is the optimal information needed for the wide array of sensors in the GPM constellation, including examination of regional conditions. The original data sets will focus on stratification by emissivity class, surface temperature and total perceptible water. We'll perform sensitivity studies to determine the potential role of ancillary data (e.g., land surface temperature, snow cover/water equivalent, etc.) to improve precipitation estimation over land in different climate regimes, including rain and snow. In other words, what information outside of the radiances can help describe the background and subsequent departures from it that are active precipitating regions? It is likely that this information will be a function of the various precipitation regimes. Statistical methods such as Principal Component Analysis (PCA) will be utilized in this task. Databases from a variety of sources are being constructed. They include existing satellite microwave measurements of precipitating and non-precipitating conditions, ground radar precipitation rate estimates, surface emissivity climatology from satellites, surface temperature and TPW from NWP reanalysis. Results from the analysis of these databases with respect to the microwave precipitation sensitivity to the variety of environmental conditions in different climate regimes will be discussed.

Wang, N.; Ferraro, R. R.

2013-12-01

396

Satellite observations of smoke from oil fires in kuwait.  

PubMed

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 smoke have been detected in METEOSAT data as far away as 2000 kilometers east of Kuwait, over southwestern Pakistan at heights between 6 and 7 kilometers. The occasional presence of convective clouds over the fires indicates that some scavenging of the smoke is taking place. PMID:17834879

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

1991-06-14

397

Research on far-field diffraction of cube-corner retroreflector in the satellite laser ranging system  

Microsoft Academic Search

Cube-corner retroreflector (CCR) has been widely used in the satellite laser ranging (SLR) systems as a cooperative target based on its direct reflecting. It can increase the energy of laser pulse which is reflected back from the satellite, augment the distance between the satellite and the observing station, and improve the ranging accuracy. In recent years, CCR has become one

Yin-Kan Weng; Song Li; Hui Zhou; Jin-Ling Yang; Guo-Xing Zheng; Pin-Hui Zhang

2010-01-01

398

Interoperability of satellite-based augmentation systems for aircraft navigation  

Microsoft Academic Search

The Federal Aviation Administration (FAA) is pioneering a transformation of the national airspace system from its present ground based navigation and landing systems to a satellite based system using the Global Positioning System (GPS). To meet the critical safety-of-life aviation positioning requirements, a Satellite-Based Augmentation System (SBAS), the Wide Area Augmentation System (WAAS), is being implemented to support navigation for

Donghai Dai

2001-01-01

399

Reusable Reentry Satellite (RRS) system design study  

NASA Technical Reports Server (NTRS)

The Reusable Reentry Satellite (RRS) is intended to provide investigators in several biological disciplines with a relatively inexpensive method to access space for up to 60 days with eventual recovery on Earth. The RRS will permit totally intact, relatively soft, recovery of the vehicle, system refurbishment, and reflight with new and varied payloads. The RRS is to be capable of three reflights per year over a 10-year program lifetime. The RRS vehicle will have a large and readily accessible volume near the vehicle center of gravity for the Payload Module (PM) containing the experiment hardware. The vehicle is configured to permit the experimenter late access to the PM prior to launch and rapid access following recovery. The RRS will operate in one of two modes: (1) as a free-flying spacecraft in orbit, and will be allowed to drift in attitude to provide an acceleration environment of less than 10(exp -5) g. the acceleration environment during orbital trim maneuvers will be less than 10(exp -3) g; and (2) as an artificial gravity system which spins at controlled rates to provide an artificial gravity of up to 1.5 Earth g. The RRS system will be designed to be rugged, easily maintained, and economically refurbishable for the next flight. Some systems may be designed to be replaced rather than refurbished, if cost effective and capable of meeting the specified turnaround time. The minimum time between recovery and reflight will be approximately 60 days. The PMs will be designed to be relatively autonomous, with experiments that require few commands and limited telemetry. Mass data storage will be accommodated in the PM. The hardware development and implementation phase is currently expected to start in 1991 with a first launch in late 1993.

1991-01-01

400

Reusable Reentry Satellite (RRS) system design study  

NASA Astrophysics Data System (ADS)

The Reusable Reentry Satellite (RRS) is intended to provide investigators in several biological disciplines with a relatively inexpensive method to access space for up to 60 days with eventual recovery on Earth. The RRS will permit totally intact, relatively soft, recovery of the vehicle, system refurbishment, and reflight with new and varied payloads. The RRS is to be capable of three reflights per year over a 10-year program lifetime. The RRS vehicle will have a large and readily accessible volume near the vehicle center of gravity for the Payload Module (PM) containing the experiment hardware. The vehicle is configured to permit the experimenter late access to the PM prior to launch and rapid access following recovery. The RRS will operate in one of two modes: (1) as a free-flying spacecraft in orbit, and will be allowed to drift in attitude to provide an acceleration environment of less than 10(exp -5) g. the acceleration environment during orbital trim maneuvers will be less than 10(exp -3) g; and (2) as an artificial gravity system which spins at controlled rates to provide an artificial gravity of up to 1.5 Earth g. The RRS system will be designed to be rugged, easily maintained, and economically refurbishable for the next flight. Some systems may be designed to be replaced rather than refurbished, if cost effective and capable of meeting the specified turnaround time. The minimum time between recovery and reflight will be approximately 60 days. The PMs will be designed to be relatively autonomous, with experiments that require few commands and limited telemetry. Mass data storage will be accommodated in the PM. The hardware development and implementation phase is currently expected to start in 1991 with a first launch in late 1993.

1991-02-01

401

Tracking Cholera in Coastal Regions using Satellite Observations  

PubMed Central

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 outbr