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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 451 records · Page 25
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NASA NTRS1988

MODIS information, data and control system (MIDACS) level 2 functional requirements

The MODIS Information, Data and Control System (MIDACS) Level 2 Functional Requirements Document establishes the functional requirements for MIDACS and provides a basis for the mutual understanding between the users and the designers of the EosDIS, including the requirements, operating environment, external interfaces, and development plan. In defining the requirements and scope of the system, this document describes how MIDACS will operate as an element of the EOS within the EosDIS environment. This version of the Level 2 Requirements Document follows an earlier release of a preliminary draft version. The sections on functional and performance requirements do not yet fully represent the requirements of the data system needed to achieve the scientific objectives of the MODIS instruments and science teams. Indeed, the team members have not yet been selected and the team has not yet been formed; however, it has been possible to identify many relevant requirements based on the present concept of EosDIS and through interviews and meetings with key members of the scientific community. These requirements have been grouped by functional component of the data system, and by function within each component. These requirements have been merged with the complete set of Level 1 and Level 2 context diagrams, data flow diagrams, and data dictionary.

Han, D.↗
NASA NTRS1988

MODIS information, data and control system (MIDACS) operations concepts

The MODIS Information, Data, and Control System (MIDACS) Operations Concepts Document provides a basis for the mutual understanding between the users and the designers of the MIDACS, including the requirements, operating environment, external interfaces, and development plan. In defining the concepts and scope of the system, how the MIDACS will operate as an element of the Earth Observing System (EOS) within the EosDIS environment is described. This version follows an earlier release of a preliminary draft version. The individual operations concepts for planning and scheduling, control and monitoring, data acquisition and processing, calibration and validation, data archive and distribution, and user access do not yet fully represent the requirements of the data system needed to achieve the scientific objectives of the MODIS instruments and science teams. The teams are not yet formed; however, it is possible to develop the operations concepts based on the present concept of EosDIS, the level 1 and level 2 Functional Requirements Documents, and through interviews and meetings with key members of the scientific community. The operations concepts were exercised through the application of representative scenarios.

Han, D.↗
NASA NTRS1988

Earth Observing System (EOS) advanced altimetry

In the post-TOPEX era, satellite radar altimeters will be developed with the capability of measuring the earth's surface topography over a wide swath of coverage, rather than just at the satellite's nadir. The identification of potential spacecraft flight missions in the future was studied. The best opportunity was found to be the Earth Observing System (EOS). It is felt that an instrument system that has a broad appeal to the earth sciences community stands a much better chance of being selected as an EOS instrument. Consequently, the Topography and Rain Radar Imager (TARRI) will be proposed as a system that has the capability to profile the Earth's topography regardless of the surface type. The horizontal and height resolutions of interest are obviously significantly different over land, ice, and water; but, the use of radar to provide an all-weather observation capability is applicable to the whole earth. The scientific guidance for the design and development of this instrument and the eventual scientific utilization of the data produced by the TARRI will be provided by seven science teams. The teams are formed around scientific disciplines and are titled: Geology/Geophysics, Hydrology/Rain, Oceanography, Ice/Snow, Geodesy/Orbit/Attitude, Cartography, and Surface Properties/Techniques.

Parsons, C. L.↗
NASA NTRS1988

Adapting the NSCAT data system to changing requirements

The data system of the spaceborne eight-beam NASA scatterometer for measuring ocean backscatter is a nonreal-time ground-based science data processing system which inputs backscatter telemetry, processes the data into wind vectors, and archives and distributes the wind vector data and other products. Special attention is given to changes to the baseline design intended to meet new requirements for the data granularity, the data needs of the science team receiving the data, and the telemetry data source.

Benada, J. R.↗
NASA NTRS1990

Earth Radiation Budget Experiment (ERBE) validation

During the past 4 years, data from the Earth Radiation Budget Experiment (ERBE) have been undergoing detailed examination. There is no direct source of groundtruth for the radiation budget. Thus, this validation effort has had to rely heavily upon intercomparisons between different types of measurements. The ERBE SCIENCE Team chose 10 measures of agreement as validation criteria. Late in August 1988, the Team agreed that the data met these conditions. As a result, the final, monthly averaged data products are being archived. These products, their validation, and some results for January 1986 are described. Information is provided on obtaining the data from the archive.

Barkstrom, Bruce R.↗
NASA NTRS1990

Reflectivities of uniform and broken stratiform clouds: An update

The reflectivities of uniform and broken stratiform clouds obtained from the NOAA-9 and NOAA-10 overpasses collected during the FIRE Marine Stratocumulus Intensive Field Observations (IFO) were compared, and these reflectivities were compared with those obtained through radiative transfer calculation performed for plane-parallel cloud models. The objective was to determine the extent to which plane-parallel radiative transfer calculations could reproduce the reflectivities observed for uniform clouds and to determine the extent to which finite cloud effects cause broken clouds to reflect differently than uniform clouds. The latter study is to provide guidance in the parameterization of finite cloud effects in general circulation climate models as well as to assess the ability of plane-parallel theory, which is used by ISCCP to retrieve cloud properties, to treat the reflectivities of broken clouds. Some results from this study were reported at the last FIRE Science Team meeting and some were reported elsewhere (Coakley and Briegleb, 1989). Improvements since the previous reports include: (1) the analysis of additional satellite passes, and (2) a modification to the analysis which helps to show the significance of the differences in reflectivities for uniform and broken clouds.

Coakley, James A., Jr.↗
NASA NTRS1990

Observed cloud reflectivities and liquid water paths: An update

The FIRE microwave radiometer observations of liquid water path from San Nicolas Island and simultaneous NOAA AVHRR observations of cloud reflectivity were used to test a relationship between cloud liquid water path and cloud reflectivity that is often used in general circulation climate models (Stephens, 1978). The results of attempts to improve the data analysis which was described at the previous FIRE Science Team Workshop and elsewhere (Coakley and Snider, 1989) are reported. The improvements included the analysis of additional satellite passes over San Nicolas and sensitivity studies to estimate the effects on the observed reflectivities due to: (1) nonzero surface reflectivities beneath the clouds; (2) the anisotropy of the reflected radiances observed by the AVHRR; (3) small scale spatial structure in the liquid water path; and (4) adjustments to the calibration of AVHRR.

Coakley, James A., Jr.↗
NASA NTRS1989

Earth Radiation Budget Experiment (ERBE) archival and April 1985 results

This paper describes the Earth Radiation Budget Experiment (ERBE) data products being made available to the community. The Science Team used ten validation criteria to judge the acceptability of the data for archival. These criteria are listed, and uncertainty estimates based on them for four typical data products are presented. A brief description of the radiation budget for April 1985 from the combined data of ERBE and NOAA-9 concludes this paper.

Barkstrom, B.↗
NASA NTRS1990

A synopsis of Langley Research Center's lidar effort for the 1986 FIRE IFO

The lidar data obtained by the Langley Aircraft Lidar in October 1986 in Wisconsin is being reduced in a transparent, simple fashion and will be published in its reduced form in a NASA Reference Publication (RP). This reduced data will also be submitted to the FIRE data archives. Some of this reduced data will be presented at the FIRE FSET Workshop to acquaint the science team with the data format to be used in the archive and the upcoming catalog contained in the RP. A new method was utilized in Wisconsin for obtain the depolarization ratio of aerosols. This method involves using a half-wave plate to calibrate the lidar under field conditions. The theory behind this technique will be presented at this workshop as well as some of the lidar calibration results. The lidar calibration will be utilized in interpreting some of the dual polarization lidar data obtained during the IFO in Wisconsin. Some of these data are also discussed. A continuous wave laser lab-type lidar simulator was constructed during the previous year. One of the primary reasons for the construction of the simulator was to attempt dual-polarization lidar-like calibrations under laboratory, rather than field conditions. The data collected by this system was used to experimentally check and thus, inspire confidence in the algorithms being used to interpret the lidar data obtained in the field. A computer program which simulates noisy lidar data was used as a part of this effort in order to obtain some feel for the noise in the inversion parameters as a function of noise in the actual measurements. The lidar simulation will be described in addition to presenting some of the lab-generated calibration data.

Alvarez, Jose M.↗
NASA NTRS1990

Mars Observer remote science operations

The objectives and the background of the Mars Observer mission are briefly reviewed with emphasis on the remote science operations portion of the mission. In particular, the discussion covers observational planning and instrument sequences, data retrieval, instrument health monitoring, and science analysis. Attention is also given to workstation technology utilization, science team, project data base, common data formats, and security.

Kahn, Peter B.↗
NASA NTRS1990

Triton's plumes - The dust devil hypothesis

Triton's plumes are narrow columns 10 km in height, with tails extending horizontally for distances over 100 km. This structure suggests that the plumes are an atmospheric rather than a surface phenomenon. The closest terrestrial analogs may be dust devils, which are atmospheric vortices originating in the unstable layer close to the ground. Since Triton has such a low surface pressure, extremely unstable layers could develop during the day. Patches of unfrosted ground near the subsolar point could act as sites for dust devil formation because they heat up relative to the surrounding nitrogen frost. The resulting convection would warm the atmosphere to temperatures of 48 k or higher, as observed by the Voyager radio science team. Assuming that velocity scales as the square root of temperature difference times the height of the mixed layer, a velocity of 20 m/sec is derived for the strongest dust devils on Triton. Winds of this speed could raise particles provided they are a factor of 1000 to 10,000 less cohesive than those on earth.

Ingersoll, Andrew P.↗
NASA NTRS1991

An overview of the results of the FIFE-87 and FIFE-89 campaigns

Results of a major land surface-atmosphere exchange study, the First ISLSCP Field Experiment (FIFE) are summarized. Findings result from nearly 80 days of field measurements over a 15 kilometer square area involving 30 science teams, seven remote sensing aircraft, and 5 satellites which acquired over 1200 low resolution and 35 high spatial resolution satellite images, maps of remotely sensed temperature, vegetation index and soil moisture, surface flux measurements from more than 20 ground stations and airborne sensors, and transects of vegetation, soil moisture and soil chemistry. Relationships between in situ, airborne, and spaceborne remote measurements and the problem of scaling will be discussed. Energy balance comparisons among sites were made. Diurnal measurements of latent heat fluxes indicated a strong correlation between the evaporative fraction at midday and the daytime average value.

Murphy, R. E.↗
NASA NTRS1991

Airborne precursor missions in support of SIR-C/X-SAR

The NASA DC-8 and DLR E-SAR airborne imaging radars have been deployed over several sites in Europe and the U.S. in support of SIR-C/X-SAR (Shuttle Imaging Radar-C/X-Synthetic Aperture Radar) science team investigations. To date, data have been acquired in support of studies of alpine glaciers, forests, geology, oceanography, and calibration. An experimental campaign with airborne sensors will take place in Europe in June to July 1991 which will allow multitemporal surveys of several Europeans sites. Current plans are for calibration and ecology experiments to be undertaken in Germany, the Netherlands, Italy, France, and the United Kingdom. Coordinated multitemporal aircraft and ground campaigns are planned in support of hydrology experiments in Italy, the United Kingdom, and Austria. Data will also be acquired in support of oceanogrqhy in the Gulf of Genova, North Atlantic, Straits of Messina and the North Sea. Geology sites will include Campi Flegrei and Vesuvio, Italy.

Evans, D.↗
NASA NTRS1990

Stratosphere-troposphere exchange project management

The purpose is to manage the Stratosphere Troposphere Exchange Project (STEP). This includes holding and planning science team meetings, organizing sessions at conferences devoted to the results and objectives of STEP field programs, putting together special journal issues or special sections of journal issues devoted to the results of STEP, and planning and producing technical memoranda on STEP. Summary of progress and results are given.

Russell, Philip B.↗
NASA NTRS1991

The dynamics and energetics of midlatitude western boundary currents: A comparison of the Kuroshio Extension and the Gulf Stream

We will use TOPEX/POSEIDON altimetry in combination with ongoing and planned efforts, including data from the European Remote Sensing satellite (ERS-1), in situ measurements designed specifically to complement satellite altimetry, and assimilation of these several data types into eddy-resolving numerical models in order to understand the dynamics and energetics of midlatitude western boundary currents (specifically, the Gulf Stream and the Kuroshio Extension). A better understanding of the recirculation of midlatitude gyres can best be undertaken in the format of such regional, eddy-resolving experiments. Such regional programs will enhance and be enhanced by the larger scale circulation studies of the World Ocean Circulation Experiment (WOCE) as well as by global-scale eddy-resolving models that we will develop prior to the TOPEX/POSEIDON mission. This effort includes participation on the TOPEDX/POSEIDON Science Team.

Mitchell, James L.↗
NASA NTRS1993

The effects of cloud inhomogeneities upon radiative fluxes, and the supply of a cloud truth validation dataset

A series of cloud and sea ice retrieval algorithms are being developed in support of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Science Team objectives. These retrievals include the following: cloud fractional area, cloud optical thickness, cloud phase (water or ice), cloud particle effective radius, cloud top heights, cloud base height, cloud top temperature, cloud emissivity, cloud 3-D structure, cloud field scales of organization, sea ice fractional area, sea ice temperature, sea ice albedo, and sea surface temperature. Due to the problems of accurately retrieving cloud properties over bright surfaces, an advanced cloud classification method was developed which is based upon spectral and textural features and artificial intelligence classifiers.

Welch, Ronald M.↗
NASA NTRS1993

Sources Sought for Innovative Scientific Instrumentation for Scientific Lunar Rovers

Lunar rovers should be designed as integrated scientific measurement systems that address scientific goals as their main objective. Scientific goals for lunar rovers are presented. Teleoperated robotic field geologists will allow the science team to make discoveries using a wide range of sensory data collected by electronic 'eyes' and sophisticated scientific instrumentation. rovers need to operate in geologically interesting terrain (rock outcrops) and to identify and closely examine interesting rock samples. Enough flight-ready instruments are available to fly on the first mission, but additional instrument development based on emerging technology is desirable. Various instruments that need to be developed for later missions are described.

Meyer, C.↗
NASA NTRS1992

Astrometric performance characteristics of the Hubble Space Telescope fine guidance sensors

Each of the three fine guidance sensors for the Hubble Space Telescope constitutes a sixth science instrument to be used for astrometry. We detail the tests and results used in choosing one of the three sensors to be the prime astrometer. The Astrometry Science Team has chosen Fine Guidance Sensor (FGS) 3. FGS 3 produces position measurements on a star with V = 17 with a peraxis precision of 0.003 arcsec. The interferometer response function should permit double-star astrometry at least down to V = 16 for the central region of FGS 3. In a 10-h test of the stability of POS-mode astrometric measurements made in FGS 3, we found no scale or orientation variations greater than two parts in 100,000. During this same time period, we found no statistically significant systematic guide-star radial separation changes. Spacecraft jitter is found to be the prime determinant of astrometry success or failure.

Benedict, G. F.↗