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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Satellite observation and mapping of wintertime ozone variability in the lower stratosphere

Comparison is made between 30 mbar ozone fields that are generated by a transport chemistry model utilizing the winds from the Goddard Space Flight Center stratospheric data assimilation system (STRATAN), observations from the LIMS instrument on Nimbus-7, and the ozone fields that result from 'flying' a mathematical simulation of LIMS observations through the transport chemistry model ozone fields. The modeled ozone fields were found to resemble the LIMS observations, but the model fields show much more temporal and spatial structure than do the LIMS observations. The 'satellite mapped' model results resemble the LIMS observations much more closely. These results are very consistent with the earlier discussions of satellite space-time sampling by Salby.

Geller, M. A.↗
NASA NTRS1991

Correspondence of surface temperatures and terrain variables over a tallgrass prairie

The time-dependent correspondence between maps of surface brightness temperature derived from Landsat Thematic Mapper data and mapped terrain variables over a tallgrass prairie in northeastern Kansas is examined. Individual terrain variables including burning treatment, vegetation cover type (agriculture, prairie, woody vegetation), hillslope position, and greenness exhibit varying degrees of association with surface temperature. Burning treatment is most strongly associated with mid-morning surface temperature. Examination of terrain strata based on combinations of terrain variables, notably burning treatment and hillslope position, suggest that terrain variables interact in affecting surface temperature. Interaction between hillslope position, burning treatment, and surface temperature is more important in August than in May.

Friedl, Mark A.↗
NASA NTRS1986

Mapping permafrost in the boreal forest with Thematic Mapper satellite data

A geographic data base incorporating Landsat TM data was used to develop and evaluate logistic discriminant functions for predicting the distribution of permafrost in a boreal forest watershed. The data base included both satellite-derived information and ancillary map data. Five permafrost classifications were developed from a stratified random sample of the data base and evaluated by comparison with a photo-interpreted permafrost map using contingency table analysis and soil temperatures recorded at sites within the watershed. A classification using a TM thermal band and a TM-derived vegetation map as independent variables yielded the highest mapping accuracy for all permafrost categories.

Morrissey, L. A.↗
NASA NTRS1989

Covariance of greenness and terrain variables over the Konza Prairie

An analysis is made of time-dependent covariance of the greenness vegetation index with mapped terrain variables over the Konza Prarie (Kansas) during the 1987 growing season. The analysis was part of an ongoing project to establish appopriate ground-sampling and data-integration strategies for satellite-based monitoring of land surface climate conditions. Greenness images for six dates between May and October were derived from atmospherically corrected thematic mapper (TM) data and coregistered with maps of woody vegetation, fire, and soils. Local variance in greenness peaked in mid-June, falling rapidly until mid-August, and declining gradually thereafter. Greenness images exhibited positive autocorrelation up to distances of 180-210 m, but the dominant scale of pattern occurred at a block size of 60 m by 60 m throughout the growing season. 40-44 percent of total scene variance in July and August was accounted for by the effects of woody vegetation (8.9 percent of the area), prairie burning, and soil type. The effect of these terrain variables was fairly consistent between June and late August and was manifested as additional high-frequency spatial variation in imagery from that period.

Davis, Frank W.↗
NASA NTRS1987

Landsat classification of the barren hydrolittoral areas of Lake Yli-Kitka, north-eastern Finland

As a part of the project 'Landsat-studies for Mapping the Variables within Water Areas' this study deals with the classification possibilities of evaluating and mapping depth relations and bottom materials within the barren and clear-watered shores of Lake Yli-Kitka, North-Eastern Finland. It has been discovered that it is possible to distinguish open water areas with a water depth of more than about half of the Secchi disk depth from those of shallower hydrolittoral areas. The morainic, sandy and only slightly vegetated subareas of the shallow shores and shoals can possibly be identified by using a simple classification procedure. The data used were recorded by the coarse-resolution Landsat MSS imagery system, and better results are expected after the experiences of the Landsat TM data and the availability of the SPOT material.

Raitala, J.↗
NASA NTRS1985

Global mean sea surface computation based upon a combination of SEASAT and GEOS-3 satellite altimeter data

A mean sea surface map was computed for the global ocean areas between 70 deg N latitude and 62 deg S latitude based upon the 70 day SEASAT and 3.5 year GEOS-3 altimeter data sets. The mean sea surface is presented in the form of a global contour map and a 0.25 deg x 0.25 deg grid. A combination of regional adjustments based upon crossover techniques and the subsequent adjustment of the regional solutions into a global reference system was employed in order to minimize the effects of radial orbit error. A global map of the crossover residuals after the crossover adjustments are made is in good agreement with earlier mesoscale variability contour maps based upon the last month of SEASAT collinear data. This high level of agreement provides good evidence that relative orbit error was removed to the decimeter level on a regional basis. This represents a significant improvement over our previous maps which contained patterns, particularly in the central Pacific, which were due to radial orbit error. Long wavelength, basin scale errors are still present with a submeter amplitude due to errors in the PGS-S4 gravity model. Such errors can only be removed through the improvement of the Earth's gravity model and associated geodetic parameters.

Marsh, J. G.↗
NASA NTRS1991

Chemical and biological structure and transport of a cool filament associated with a jet-eddy system of northern California in July 1986 (OPTOMA21)

The distributions of nutrient, pigment, bio-optical, and physical variables were mapped in a jet-eddy system off Point Reyes and Point Arena, California, from July 7 to 19, 1986, in order to describe the 3D variability of the filament and its relation to the nutrient and phytoplankton distributions offshore, to examine the interaction between the filament and coastal water, and to estimate the transport of nutrients and phytoplankton by the jet system. Several cool filaments were distinguishable at distances of more than 35-50 km from the coast in satellite imagery during this period. The juxtaposition of these features as well as the presence of an offshore anticyclone and a cyclone south of the filament anchored to the coast at Point Arena led to complex patterns in all variables, aided by the apparent alongshore variability in the source of upwelled water. This structure has implications for the fluxes of organic material in the region and is probably significant in organizing the interactions among different trophic levels within the system.

Jones, Burton H.↗
NASA NTRS1998

Variability of Arctic Sea Ice as Viewed from Space

Over the past 20 years, satellite passive-microwave radiometry has provided a marvelous means for obtaining information about the variability of the Arctic sea ice cover and particularly about sea ice concentrations (% areal coverages) and from them ice extents and the lengths of the sea ice season. This ability derives from the sharp contrast between the microwave emissions of sea ice versus liquid water and allows routine monitoring of the vast Arctic sea ice cover, which typically varies in extent from a minimum of about 8,000,000 sq km in September to a maximum of about 15,000,000 sq km in March, the latter value being over 1.5 times the area of either the United States or Canada. The vast Arctic ice cover has many impacts, including hindering heat, mass, and y momentum exchanges between the oceans and the atmosphere, reducing the amount of solar radiation absorbed at the Earth's surface, affecting freshwater transports and ocean circulation, and serving as a vital surface for many species of polar animals. These direct impacts also lead to indirect impacts, including effects on local and perhaps global atmospheric temperatures, effects that are being examined in general circulation modeling studies, where preliminary results indicate that changes on the order of a few percent sea ice concentration can lead to temperature changes of 1 K or greater even in local areas outside of the sea ice region. Satellite passive-microwave data for November 1978 through December 1996 reveal marked regional and interannual variabilities in both the ice extents and the lengths of the sea ice season, as well as some statistically significant trends. For the north polar ice cover as a whole, maximum ice extents varied over a range of 14,700,000 - 15,900,000 km(2), while individual regions showed much greater percentage variations, e.g., with the Greenland Sea experiencing a range of 740,000 - 1,1110,000 km(2) in its yearly maximum ice coverage. Although variations from year to year and region to region are large, overall the Arctic ice extents did show a statistically significant, 2.8%/ decade negative trend over the 18.2-year period. Ice season lengths, which vary from only a few weeks near the ice margins to the full year in the large region of perennial ice coverage, also experienced interannual variability, and mapping their trends allows detailed geographic information on exactly where the ice season lengthened and where it shortened. Over the 18 years, ice season lengthening occurred predominantly in the western hemisphere and was strongest in the western Labrador Sea, while ice season shortening occurred predominantly in the eastern hemisphere and was strongest in the eastern Barents Sea. Much information about other important Arctic sea ice variables has also been obtained from satellite data, including information about melt ponding, temperature, snow cover, and ice velocities. For instance, maps of ice velocities have now been made from satellite scatterometry data, including information about melt ponding, temperature, snow cover, and ice velocities.

Parkinson, Claire L.↗
NASA NTRS2002

Application of Thermal Infrared Remote Sensing for Quantitative Evaluation of Crop Characteristics

Evidence suggests that thermal infrared emittance (TIR) at the field-scale is largely a function of the integrated crop/soil moisture continuum. Because soil moisture dynamics largely determine crop yields in non-irrigated farming (85 % of Alabama farms are non-irrigated), TIR may be an effective method of mapping within field crop yield variability, and possibly, absolute yields. The ability to map yield variability at juvenile growth stages can lead to improved soil fertility and pest management, as well as facilitating the development of economic forecasting. Researchers at GHCC/MSFC/NASA and Auburn University are currently investigating the role of TIR in site-specific agriculture. Site-specific agriculture (SSA), or precision farming, is a method of crop production in which zones and soils within a field are delineated and managed according to their unique properties. The goal of SSA is to improve farm profits and reduce environmental impacts through targeted agrochemical applications. The foundation of SSA depends upon the spatial and temporal characterization of soil and crop properties through the creation of management zones. Management zones can be delineated using: 1) remote sensing (RS) data, 2) conventional soil testing and soil mapping, and 3) yield mapping. Portions of this research have concentrated on using remote sensing data to map yield variability in corn (Zea mays L.) and soybean (Glycine max L.) crops. Remote sensing data have been collected for several fields in the Tennessee Valley region at various crop growth stages during the last four growing seasons. Preliminary results of this study will be presented.

Shaw, J.↗
NASA NTRS2013

Evaluating and Quantifying the Climate-Driven Interannual Variability in Global Inventory Modeling and Mapping Studies (GIMMS) Normalized Difference Vegetation Index (NDVI3g) at Global Scales

Satellite observations of surface reflected solar radiation contain informationabout variability in the absorption of solar radiation by vegetation. Understanding thecauses of variability is important for models that use these data to drive land surface fluxesor for benchmarking prognostic vegetation models. Here we evaluated the interannualvariability in the new 30.5-year long global satellite-derived surface reflectance index data,Global Inventory Modeling and Mapping Studies normalized difference vegetation index(GIMMS NDVI3g). Pearsons correlation and multiple linear stepwise regression analyseswere applied to quantify the NDVI interannual variability driven by climate anomalies, andto evaluate the effects of potential interference (snow, aerosols and clouds) on the NDVIsignal. We found ecologically plausible strong controls on NDVI variability by antecedent precipitation and current monthly temperature with distinct spatial patterns. Precipitation correlations were strongest for temperate to tropical water limited herbaceous systemswhere in some regions and seasons 40 of the NDVI variance could be explained byprecipitation anomalies. Temperature correlations were strongest in northern mid- to-high-latitudes in the spring and early summer where up to 70 of the NDVI variance was explained by temperature anomalies. We find that, in western and central North America,winter-spring precipitation determines early summer growth while more recent precipitation controls NDVI variability in late summer. In contrast, current or prior wetseason precipitation anomalies were correlated with all months of NDVI in sub-tropical herbaceous vegetation. Snow, aerosols and clouds as well as unexplained phenomena still account for part of the NDVI variance despite corrections. Nevertheless, this study demonstrates that GIMMS NDVI3g represents real responses of vegetation to climate variability that are useful for global models.

interference↗
NASA NTRS2012

NASA Tech Briefs, February 2012

This issue contains the following briefs: (1) Optical Comb from a Whispering Gallery Mode Resonator for Spectroscopy and Astronomy Instruments Calibration (2) Real-Time Flight Envelope Monitoring System (3) Nemesis Autonomous Test System (4) Mirror Metrology Using Nano-Probe Supports (5) Automated Lab-on-a-Chip Electrophoresis System (6) Techniques for Down-Sampling a Measured Surface Height Map for Model Validation (7) Multi-Component, Multi-Point Interferometric Rayleigh/Mie Doppler Velocimeter (8) Frequency to Voltage Converter Analog Front-End Prototype (9) Dust-Tolerant Intelligent Electrical Connection System (10) Gigabit Ethernet Asynchronous Clock Compensation FIFO (11) High-Speed, Multi-Channel Serial ADC LVDS Interface for Xilinx Virtex-5 FPGA (12) Glovebox for GeoLab Subsystem in HDU1-PEM (13) Modified Process Reduces Porosity when Soldering in Reduced Gravity Environments (14) Use of Functionalized Carbon Nanotubes for Covalent Attachment of Nanotubes to Silicon (15) Flexible Plug Repair for Shuttle Wing Leading Edge (16) Three Dimensionally Interlinked, Dense, Solid Form of Single-Walled CNT Ropes (17) Axel Robotic Platform for Crater and Extreme Terrain Exploration (18) Site Tamper and Material Plow Tool - STAMP (19) Magnetic Interface for Segmented Mirror Assembly (20) Transpiration-Cooled Spacecraft-Insulation-Repair Fasteners (21) Fluorescence-Based Sensor for Monitoring Activation of Lunar Dust (22) Aperture Ion Source (23) Virtual Ultrasound Guidance for Inexperienced Operators (24) Model-Based Fault Diagnosis: Performing Root Cause and Impact Analyses in Real Time (25) Interactive Schematic Integration Within the Propellant System Modeling Environment (26) Magnetic and Electric Field Polarizations of Oblique Magnetospheric Chorus Waves (27) Variable Sampling Mapping.

Source record↗
NASA NTRS1982

A proposal for observations of upper and middle tropospheric clouds

A proposal for a multi-institutional investigation of the processes involved in the growth and maintenance of high level extended clouds is presented. Mapping of variability of the cloud and of its radiative characteristics in terms of the meteorological environment of the cloud; performance of case studies involving observation of the cloud microphysics and radiation characteristics; and investigation of the processes responsible for the generation, maintenance, and dissipation of the cloud system are recommended. Both modeling and monitoring activities are considered. The specific research projects which the author proposes to carry out are described. Suggestions for the administrative organization of the total effort are presented.

Source record↗
NASA NTRS1982

Gravity and magnetic anomaly data analysis

Progress on the analysis MAGSAT data is reported. The MAGSAT data from 40 deg S to 70 deg N latitude and 30 deg W to 60 E longitude was reduced to radial polarization. In addition, gravity anomaly data from this area were processed and a variety of filtered maps were prepared for combined interpretation of the gravity and magnetic data in conjunction with structural and tectonic maps of the area. The VERSATEC listings and cross-reference maps of variable and array names for the spherical Earth analysis programs NVERTSM, SMFLD, NVERTG, and GFLD were also prepared.

Braile, L. W.↗
NASA NTRS1991

Interannual variability of the spatial distribution of sea ice in the north polar region

The interannual variability of the monthly average spatial distributions of northern hemisphere sea ice was examined for the 1973-1987 period of the electrically scanning microwave radiometer on the Nimbus 5 satellite and the scanning multichannel microwave radiometer on the Nimbus 7 satellite passive microwave data record. Strong seasonal and spatial contrasts in the amount of interannual variability are mapped and identified. The maps and analyses provide a baseline against which future northern hemisphere sea ice distributions can be compared in the continuing attempt to analyze global climate and to determine whether or not significant climate change is occurring.

Parkinson, Claire L.↗
NASA NTRS1992

Millimeter and hard x ray/gamma ray observations of solar flares during the June 1991 GRO campaign

We have carried out high-spatial-resolution millimeter observations of solar flares using the Berkeley-Illinois-Maryland Array (BIMA). At the present time, BIMA consists of only three elements, which is not adequate for mapping highly variable solar phenomena, but is excellent for studies of the temporal structure of flares at millimeter wavelengths at several different spatial scales. We present BIMA observations made during the Gamma Ray Observatories (GRO)/Solar Max 1991 campaign in Jun. 1991 when solar activity was unusually high. Our observations covered the period 8-9 Jun. 1991; this period overlapped the period 4-15 Jun. when the Compton Telescope made the Sun a target of opportunity because of the high level of solar activity.

Kundu, M. R.↗
NASA NTRS1990

Footprint prediction of scalar fluxes - Reliability and implications for airborne flux measurements over the FIFE site

Estimates of the location and extension of the upwind ground area that affects flux observations most directly are examined to determine the reliability of airborne versus near-ground flux measurements. The theoretical issues regarding the 'footprint' are examined, and specific observations are analyzed by studying the data over a grid regarding sensible heat, latent heat, CO2, and greenness. The grid is footprint-corrected to correlate better with independently observed surface characteristics, and an optimized footprint is developed that satisfies the relationships between the observed variables. Optimized mapping of the surface flux is given which demonstrates the importance of considering local advection to correlate airborne and ground-based flux observations. The technique is particularly applicable to situations in which significant variations in the surface flux density exist.

Schuepp, P. H.↗