Appearance of VLF and ELF-noises in topside ionosphere under the action of high power radio wave from data of satellite intercosmos-24

Results of a satellite experiment are presented on detection of VLF and ELF-waves excited by irradiation of the night ionosphere F-region by the field of a nonmodulated high-power radio wave. The excited VLF and ELF-waves have been detected at the topside ionosphere heights h=500–1000 km in the frequency bands 8 kHz相似文献   

Radar Imagery of Oil Slicks

A joint agency controlled oil slick experiment, sponsored by the United States Coast Guard, was conducted in the Pacific Ocean in the Fall of 1970. The Naval Research Laboratory's synthetic aperature radar was used to detect and monitor the slicks at frequencies of 428, 1228, 4455, and 8910 MHz during the low sea state conditions encountered. At frequencies of 1228 MHz and higher, the slicks were depicted with sharp boundaries. At 428 MHz, the boundaries were indistinct. Approximately 400 liters of oil was detected as it was being discharged from the generating ship and larger spills were mapped from the initial thickness to equilibrium thicknesses of 1 micron or less. Thin streamers of oil and wind blown films were also imaged. Area growth rates were obtained for 2500 liter spills of API 26.1 crude oil and API 9.7 fuel oil on a calm sea. The respective rates, from approximately 1 to 4 hours after the spills, were 134 m2/s and 16 m2/s.     

Konus-W gamma-ray burst experiment for the GGS Wind spacecraft

The Konus-W experiment to be flown on board the GGS-Wind spacecraft is designed to observe gamma-ray bursts and solar flares with moderate spectral and high time resolution. Two large scintillators are used to provide omnidirectional sensitivity. The primary scientific objectives are the study of the continuum energy spectra and spectral features of these events in the energy range of 10 keV to 10 MeV, as well as their time histories in soft, medium, and hard energy bands, with a time resolution to 2 ms.     

Structural and functional organisation of regenerated plant protoplasts exposed to microgravity on Biokosmos 9.

Preparatory experiments for the IML-1 mission using plant protoplasts, were flown on a 14-day flight on Biokosmos 9 in September 1989. Thirty-six hours before launch of the biosatellite, protoplasts were isolated from hypocotyl cells of rapeseed (Brassica napus) and suspension cultures of carrot (Daucus carota). Ultrastructural and fluorescence analysis of cell aggregates from these protoplasts, cultured under microgravity conditions, have been performed. In the flight samples as well as in the ground controls, a portion of the total number of protoplasts regenerated cell walls. The processes of cell differentiation and proliferation under micro-g did not differ significantly from those under normal gravity conditions. However, in micro-g differences were observed in the ultrastructure of some organelles such as plastids and mitochondria. There was also an increase in the frequency of the occurrence of folds formed by the plasmalemma together with an increase in the degree of complexity of these folds. In cell cultures developed under micro-g conditions, the calcium content tends to decrease, compared to the ground control. Different aspects of using isolated protoplasts for clarifying the mechanisms of biological effects of microgravity are discussed.     

The generation of DC and AC electric fields, and electron fluxes in a rocket experiment with barium injection in the auroral ionosphere

The results of an active rocket experiment with barium injection in the auroral ionosphere designed to check possible scenario of the initial phase of substorm are presented and discussed.     

Small Scale Alfvénic Structure in the Aurora

This paper presents a comprehensive review of dispersive Alfvén waves in space and laboratory plasmas. We start with linear properties of Alfvén waves and show how the inclusion of ion gyroradius, parallel electron inertia, and finite frequency effects modify the Alfvén wave properties. Detailed discussions of inertial and kinetic Alfvén waves and their polarizations as well as their relations to drift Alfvén waves are presented. Up to date observations of waves and field parameters deduced from the measurements by Freja, Fast, and other spacecraft are summarized. We also present laboratory measurements of dispersive Alfvén waves, that are of most interest to auroral physics. Electron acceleration by Alfvén waves and possible connections of dispersive Alfvén waves with ionospheric-magnetospheric resonator and global field-line resonances are also reviewed. Theoretical efforts are directed on studies of Alfvén resonance cones, generation of dispersive Alfvén waves, as well their nonlinear interactions with the background plasma and self-interaction. Such topics as the dispersive Alfvén wave ponderomotive force, density cavitation, wave modulation/filamentation, and Alfvén wave self-focusing are reviewed. The nonlinear dispersive Alfvén wave studies also include the formation of vortices and their dynamics as well as chaos in Alfvén wave turbulence. Finally, we present a rigorous evaluation of theoretical and experimental investigations and point out applications and future perspectives of auroral Alfvén wave physics.     

Responses to satellite remote sensing opportunities in East and Southern Africa

Since 1978 the U.S. Agency for International Development (USAID) has funded a regional remote sensing project for East and Southern Africa. The project, hosted by the Regional Centre for Services in Surveying Mapping and Remote Sensing, has provided a programme of training courses, user services and project support. This included the equipping and establishment of a photo-laboratory complex for processing Landsat images and the provision of advice and support for agencies undertaking natural resources analysis.Response to the training programme has been very good. Courses are usually over subscribed and there is a continued demand for training. Assessments of the courses by participants are highly positive and the courses have featured consultants of international calibre. Requests for follow-up courses, and for specialist group training indicate a strong response to this training activity. User services are active, consultations with staff, use of the browse file and interpretation equipment and the purchase of data for project work all produce an average demand of 12 active enquiries per working week. The photo-laboratory is particularly active and demand for products exceeds available capacity.Project work is now being supported but limited resources restrict the range and amount of project activity. Response to the opportunities offered for projects has been favourable and this activity is ripe for expansion. The difficulty in expanding to meet the expressed demand is primarily financial. The east and southern Africa region is not economically strong and has a great need for natural resources data for development work and planning. The responses to satellite remote sensing opportunities will be limited by these financial constraints which effectively means by the level of international aid directed to this activity. For such aid to be effective it must be coordinated and firmly attached to the region. Such coordinated aid programmes would avoid fragmentation of distribution and applications work. Fragmentation could seriously disrupt the present growth in natural resources activity based on remote sensing data from satellites. The lack of financing for a regional ground receiving station is also a significant limiting factor.     

Quantifying energy and mass transfer in crop canopies: sensors for measurement of temperature and air velocity.

Here we report on the in situ performance of inexpensive, miniature sensors that have increased our ability to measure mass and energy fluxes from plant canopies in controlled environments: 1. Surface temperature. Canopy temperature measurements indicate changes in stomatal aperture and thus latent and sensible heat fluxes. Infrared transducers from two manufacturers (Exergen Corporation, Newton, MA; and Everest Interscience, Tucson, AZ, USA) have recently become available. Transducer accuracy matched that of a more expensive hand-held infrared thermometer. 2. Air velocity varies above and within plant canopies and is an important component in mass and energy transfer models. We tested commercially-available needle, heat-transfer anemometers (1 x 50 mm cylinder) that consist of a fine-wire thermocouple and a heater inside a hypodermic needle. The needle is heated and wind speed determined from the temperature rise above ambient. These sensors are particularly useful in measuring the low wind speeds found within plant canopies. 3. Accurate measurements of air temperature adjacent to plant leaves facilitates transport phenomena modeling. We quantified the effect of radiation and air velocity on temperature rise in thermocouples from 10 to 500 micrometers. At high radiation loads and low wind speeds, temperature errors were as large as 7 degrees C above air temperature.     

Immediate and long-term prospects for helioseismology

Recent extensive measurements of frequencies of free oscillation of the Sun have permitted a first direct estimate of the variation of sound speed and angular velocity throughout the Sun. The results hint that the answers to some tantalizing questions concerning the Sun's interior structure and its history are almost within grasp. Optimists like myself believe that in a few years a worldwide network of ground-based observing stations will give us important clues. However, it may be necessary to make observations from space before we can be sure of the answers.