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At least 55 records · Page 3

Seasat views North America, the Caribbean, and Western Europe with imaging radar

Forty-one digitally correlated Seasat synthetic-aperture radar images of land areas in North America, the Caribbean, and Western Europe are presented to demonstrate this microwave orbital imagery. The characteristics of the radar images, the types of information that can be extracted from them, and certain of their inherent distortions are briefly described. Each atlas scene covers an area of 90 X 90 kilometers, with the exception of the one that is the Nation's Capital. The scenes are grouped according to salient features of geology, hydrology and water resources, urban landcover, or agriculture. Each radar image is accompanied by a corresponding image in the optical or near-infrared range, or by a simple sketch map to illustrate features of interest. Characteristics of the Seasat radar imaging system are outlined.

Ford, J. P.↗

The SPACELAB Project: A Transatlantic challenge for Europe

The contribution of Europe to the U.S. space program is related to the development of Spacelab. The Federal Republic of Germany is to contribute 53% and Italy 18% of the expenses. The industrial team conducting the development work for the Spacelab consists of experts from firms of the ten nations participating financially in the program. Attention is given to organizational problems, details on the development program, aspects of mission preparation, and future developments.

Ottemeyer, D. R.↗

Vertical density and temperature structure over northern Europe

Vertical profiles of upper-atmosphere temperature and density over northern Europe constructed from data obtained in November and December 1980, as part of the Energy Budget Campaign, are presented and discussed. Temperature sondes, passive spheres, accelerometers, mass and IR spectrometers, and density gauges were rocket launched from ESRANGE, Sweden and Andoya, Norway; the data are combined with ground measurements to construct 20-120-km-altitude profiles for night periods of severe, moderate, and minimal geomagnetic storm activity. The profiles are compared with each other and with the 1976 U.S. Standard Atmosphere (USSA). In the temperature profiles, increased geomagnetic activity is associated with lower temperatures and flattened profiles in the stratopause region, and higher temperatures in the 70-90-km range. The density profiles show a variation of less than about 15 percent, except for a 25-percent range for the moderate-geomagnetic-activity period. The inferred wavelengths and periods are those expected for internal gravity waves at this altitude, and the divergence from USSA is accounted for by season and latitude dependence.

Philbrick, C. R.↗

Reduced to Pole Long-wavelength Magnetic Anomalies of Africa and Europe

To facilitate analysis of the tectonic framework for Africa, Europe and adjacent marine areas, MAGSAT scalar anomaly data are differentially reduced to the pole and compared to regional geologic information and geophysical data including surface free-air gravity anomaly data upward continued to satellite elevation (350 km) on a spherical Earth. Comparative analysis shows magnetic anomalies correspond with both ancient as well as more recent Cenozoic structural features. Anomalies associated with ancient structures are primarily caused by intra-crustal lithologic variations such as the crustal disturbance associated with the Bangui anomaly in west-central Africa. Anomalies correlative with Cenozoic tectonic elements appear to be related to Curie isotherm perturbations. A possible example of the latter is the well-defined trend of magnetic minima that characterize the Alpine orogenic belt from the Atlas mountains to Eurasia. In contrast, a well-defined magnetic satellite minimum extends across the stable craton from Finland to the Ural mountains. Prominent magnetic maxima characterize the Arabian plate, Iceland, the Kursk region of the central Russian uplift, and generally the Precambrian shields of Africa.

Hinze, W. J.↗

Satellite Magnetic Anomalies of Africa and Europe

Preliminary MAGSAT scalar magnetic anomaly data of Africa, Europe, and adjacent marine areas were reduced to the pole assuming a constant inducing Earth's magnetic field of 60,000 nT. This process leads to a consistent anomaly data set free from marked variations in directional and intensity effects of the Earth's magnetic field over this extensive region. The resulting data are correlated with long wave length-pass filtered free-air gravity anomalies; regional heat flow, and tectonic data to investigate magatectonic elements and the region's geologic history. Magnetic anomalies are related to both ancient as well as more recent Cenozoic structural features.

Hinze, W. J.↗

The Middle Atmosphere Program: Winter In Northern Europe (MAP/WINE)

The goals of map/wind (winter in Northern Europe) are to better understand: (1) the interaction of planetary waves of tropospheric origin; (2) the temporal and spatial development of sudden stratospheric warmings; (3) the temporal and spatial development of mesospheric cooling events in conjunction with stratospheric warmings; (4) the vertical and horizontal transport of minor constituents; (5) the effects on the chemistry of neutral and charged species of the large temperature changes occurring during stratospheric warmings and mesospheric cooling; (6) sources of turbulent energy; (7) the temporal and spatial development of turbulent layers; and (8) the contributions of dynamical processes to the heating and cooling of the mesospheric and turbopause region.

Vonzahn, U.↗

Winter in Northern Europe (WINE) Project

The scientific aims, work plan, and organization of the Middle Atmosphere Program winter in northern Europe (MAP/WINE) are described. Proposed contributions to the MAP/WINE program from various countries are enumerated. Specific atmospheric parameters to be examined are listed along with the corresponding measurement technique.

Vonzahn, U.↗

Synopsis of Mid-latitude Radio Wave Absorption in Europe

Radio wave absorption data covering almost two years from Europe to Central Asia are presented. They are normalized by relating them to a reference absorption. Every day these normalized data are fitted to a mathematical function of geographical location in order to obtain a daily synopsis of radio wave absorption. A film of these absorption charts was made which is intended to reveal movements of absorption or absorption anomaly. In addition, radiance (temperature) data from the lower D-region are also plotted onto these charts.

Torkar, K. M.↗

Changes in the Ozone Content over Central Europe During Reversals of Stratospheric Circulation in Late Winter

A superposed epoch analysis during late winter zonal wind reversals was carried out from 18 year observation series (1963 to 1980) of the meridional geopotential height gradient in the 30 mb level (latitude mean) and of the ozone content over central Europe. Experimental data suggest that if planetary waves are responsible for the additional meridional ozone transport during stratospheric warmings, this transport has to take place at heights other than those up to the ozone maximum in the middle latitudes.

Entzian, G.↗

An air-breathing ballistic space transporter for Europe

With increasing transport requirements, reusable space transporters again receive serious consideration in Europe as successors to the Ariane family. The paper deals with a hydrogen-ramjet-propelled, 1-1/2-stage reusable ballistic space transporter with vertical take-off and landing and using liquid hydrogen/oxygen rockets. This novel concept was developed in a theoretical study at the University of Stuttgart. The results are compared with recently published studies of several other European space transporter concepts. The data derived for the Istra - concept are: 15.4 Mg payload into low Earth-orbit, 155 Mg gross lift-off mass, 10% payload ratio, which represents a 57% propellant saving, and 44% reduction in dry mass (structure and engines) compared with comparable two-stage pure rocket concepts.

Kramer, P. A.↗

Jet fuel property changes and their effect on producibility and cost in the U.S., Canada, and Europe

The effects of changes in properties and blending stocks on the refinery output and cost of jet fuel in the U.S., Canada, and Europe were determined. Computerized refinery models that minimize production costs and incorporated a 1981 cost structure and supply/demand projections to the year 2010 were used. Except in the West U.S., no changes in jet fuel properties were required to meet all projected demands, even allowing for deteriorating crude qualities and changes in competing product demand. In the West U.S., property changes or the use of cracked blendstocks were projected to be required after 1990 to meet expected demand. Generally, relaxation of aromatics and freezing point, or the use of cracked stocks produced similar results, i.e., jet fuel output could be increased by up to a factor of three or its production cost lowered by up to $10/cu m. High quality hydrocracked stocks are now used on a limited basis to produce jet fuel. The conversion of U.S. and NATO military forces from wide-cut to kerosene-based jet fuel is addressed. This conversion resulted in increased costs of several hundred million dollars annually. These costs can be reduced by relaxing kerosene jet fuel properties, using cracked stocks and/or considering the greater volumetric energy content of kerosene jet fuel.

Varga, G. M., Jr.↗

Reduced to pole long-wavelength magnetic anomalies of Africa and Europe

To facilitate analysis of the tectonic framework for Africa, Europe and adjacent marine areas, MAGSAT scalar anomaly data are differentially reduced to the pole and compared to regional geologic information and geophysical data including surface free-air gravity anomaly data upward continued to satellite elevation (350 km) on a spherical Earth. Comparative analysis shows magnetic anomalies correspond with both ancient as well as more recent Cenozoic structural features. Anomalies associated with ancient structures are primarily caused by intra-crustal lithologic variations such as the crustal disturbance associated with the Bangui anomaly in west-central Africa. Anomalies correlative with Cenozoic tectonic elements appear to be related to Curie isotherm perturbations. A possible example of the latter is the well-defined trend of magnetic minima that characterize the Alphine orogenic belt from the Atlas mountains to Eurasia. In contrast, a well-defined magnetic satellite minimum extends across the stable craton from Finland to the Ural mountains. Prominent magnetic maxima characterize the Arabian plate, Iceland, the Kursk region of the central Russian uplift, and generally the Precambrian shields of Africa.

Olivier, R.↗

Circulation in the mesosphere and lower thermosphere during the MAP (Middle Atmosphere Program)/WINE (Winter in the Northern Europe) period

One of the scientific programs in the MAP project, Winter in the Northern Europe (WINE) 1983 to 1984 involved an analysis of circulation processes in the middle atmosphere which characterized that winter period. Rocket soundings were conducted at many stations. In order to investigate deviations of the mean winds for the MAP/WINE period from the circulation conditions of other winters and from the climatic norm, rocket sounding data of Churchill and Barrow stations was well as the Pressure Modulated Radiometer channel 3000 data enabled the compilation of geopotential fields and the calculation of winds in the geostrophic approximation for comparison with the meteor winds. The large scale processes of the winter which determined the circulation in the period of the experiment were analyzed briefly. The analysis and results are discussed.

Tarasenko, D. A.↗

Recent developments of Loran-C in Europe

Even if recent developments, both technical and political, are affecting the satellite Global Positioning System (GPS) and GLONASS navigation systems, alone, in conjunction, or with a possible civilian overlay via INMARSAT or other satellites, time has proven that Loran-C can still be a viable solution for many problems. The aims here are twofold, to present a panorama of the most recent developments in the world and mostly in Europe, and to consider some technical aspects of two problems regarding the Mediterranean Sea chain. This chain is based on four stations, two in Italy, one in Spain and one in Turkey. The fate of the station in Turkey is known, in the sense that this station will not operate when the U.S. support will cease; the future of the Spanish station is not yet known, while Italy has expressed its intention to operate the two remaining stations. Consequently two problems need to be solved to assure at least the coverage of Italy and of the eastern Mediterranean Sea.

Leschiutta, Sigfrido↗

LLM: An L-band multibeam land mobile payload for Europe

The European Space Agency is developing, in the context of the ARTEMIS program, a multibeam reconfigurable mobile payload to provide pre-operational land-mobile satellite services at the L-band over Europe. The L-band Land-Mobile (LLM) payload features high capacity at L-band, efficient use of the L-band spectrum resources, and flexibility in reconfiguring the allocation of bandwith and RF power resources to the different beams. Additionally, a number of features were added to the payload purely for experimental purposes, like the provision of one steerable spot beam which can be repositioned anywhere within the coverage area, and the possibility to reuse L-band frequencies by spatial discrimination between non-adjacent beams, or via orthogonal polarizations. The architecture of the payload and the hardware implementation of the most critical subsystems are described.

Benedicto, J.↗

Comparison of JPL-AIRSAR and DLR E-SAR images from the MAC Europe 1991 campaign over testsite Oberpfaffenhofen: Frequency and polarization dependent backscatter variations from agricultural fields

On July 12, the MAC Europe '91 (Multi-Sensor Airborne Campaign) took place over test site Oberpfaffenhofen. The DLR Institute of Radio-Frequency Technology participated with its C-VV, X-VV, and X-HH Experimental Synthetic Aperture Radar (E-SAR). The high resolution E-SAR images with a pixel size between 1 and 2 m and the polarimetric AIRSAR images were analyzed. Using both sensors in combination is a unique opportunity to evaluate SAR images in a frequency range from P- to X-band and to investigate polarimetric information.

Schmullius, C.↗

Trends in surface ozone over Europe, 1978-1990

It has been suggested that surface ozone concentrations in rural areas of Europe have been increasing at a rate of 1 to 3 percent per year over the past two to three decades, presumably due to human influences (Feister and Warmbt, 1987; Bojkov, 1988; Penkett, 1989). Recently, we have analyzed surface ozone data from 20 European stations of differing character (remote, rural, suburban and urban) for a common period of 1978-1988 (Low et al., 1992). It was found that there were pronounced annual and seasonal variations in the linear trends in different areas, and there was no dominant region-wide trend. In spring and, most notably, summer, stations on the maritime fringe of the network generally exhibited negative trends whilst those located further into the continental interior exhibited positive trends. In winter, most of the stations in the network exhibited positive trends. Relatively few of these trends were statistically significant. This paper updates our earlier analysis by extending the data sets of the network up to the year 1990. The spatial variations in surface ozone trends over the extended period 1978-1990 are examined and discussed in comparison to the 1978-1988 patterns. The update confirms the overall conclusions of the earlier analysis, specifically that caution should be exercised in interpreting the results of trend analyses based on station data representative of a limited period of time and/or geographical area.

Low, Pak Sum↗

Ozone formation during an episode over Europe: A 3-D chemical/transport model simulation

A 3-D regional photochemical tracer/transport model for Europe and the Eastern Atlantic has been developed based on the NASA/GISS CTM. The model resolution is 4x5 degrees latitude and longitude with 9 layers in the vertical (7 in the troposphere). Advective winds, convection statistics and other meteorological data from the NASA/GISS GCM are used. An extensive gas-phase chemical scheme based on the scheme used in our global 2D model has been incorporated in the 3D model. In this work ozone formation in the troposphere is studied with the 3D model during a 5 day period starting June 30. Extensive local ozone production is found and the relationship between the source regions and the downwind areas are discussed. Variations in local ozone formation as a function of total emission rate, as well as the composition of the emissions (HC/NO(x)) ratio and isoprene emissions) are elucidated. An important vertical transport process in the troposphere is by convective clouds. The 3D model includes an explicit parameterization of this process. It is shown that this process has significant influence on the calculated surface ozone concentrations.

Berntsen, Terje↗