Abstract. The plasma-wave experiment ASPI (analysis of spectra of plasma waves and instabilities) on board the INTERBALL spacecraft is a combined wave diagnostics experiment. It performs measurements of the DC and AC magnetic ®eld vector by¯ux-gate and searchcoil sensors, the DC and AC electric ®eld vector by Langmuir double probes and the plasma current by Langmuir split probe. Preliminary data analysis shows the low noise levels of the sensors and the compatibility of new data with the results of previous missions. During several months of in-orbit operation a rich collection of data was acquired, examples of which at the magnetopause and plasma sheet are presented in second part of the paper. Scienti®c objectivesThe INTERBALL project is orientated towards the investigation of the interaction between di erent parts of the magnetosphere in relation to changes in the solar wind and ionosphere. First INTERBALL-1 orbits passed through the solar wind, bow shock, magnetosheath and magnetopause regions. Several months later the orbit apogee shifted to the near-Earth magnetotail, so that INTERBALL-1 observed the tail lobes and the plasma sheet. These orbit parameters allow the neutral sheet region to be studied for several hours.Plasma waves and¯uctuations play a crucial role in the highly collisionless space plasma. Waves and¯uctu-ations are of particular importance at the plasma boundaries such as bow shock, magnetopause, neutral sheet, and plasma sheet boundary layer. Wave-particle, interactions in the plasma result in processes like: (1) anomalous transport (pitch-angle and spatial di usion, conductivity, viscosity); (2) energy redistribution and plasma heating; (3) generation of anisotropic distribution functions and their relaxation; (4) triggering of large-scale instabilities.The speci®c objectives of the ASPI wave and ®eld experiment on board INTERBALL-1 are:1. The study of the¯uctuation characteristics in di erent regions of the magnetosphere and the use of these data as high-time-resolution indicators of plasma phenomena. 2. The determination of the micro-scale plasma characteristics (e.g. di usion and anomalous transport coe cients, wave-wave and wave-particle coupling).
In situ registrations of electron density from the Langmuir probe on board Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions satellite are used to study spatial and temporal evolution of nighttime plasma density enhancements (NPDEs). The study introduces the normalized density difference index I NDD in order to provide global estimates of the phenomenon. In the validation test, in situ data are compared with synthetic data set generated with the International Reference Ionosphere model. We find signatures of two most common examples of NPDEs, the Weddell Sea Anomaly (WSA) and midlatitude nighttime summer anomaly (MSNA) with proposed index, in the topside ionosphere. The study provides evidence that the occurrence of the WSA and MSNA is not limited to the local summer conditions. Analyzed annual trend of I NDD and in particular spatial pattern obtained during equinoxes suggest that mechanisms governing the behavior of the equatorial ionosphere cannot be neglected in the explanation of the development of NPDEs.
This paper considers the nature and sedimentary significance of rip currents. Rip currents are the main factor responsible for the transport of coarse sediments from the littoral zone to greater depths. Such sediments, deposited outside the zone of wave deformation, may be identified as storm rip current increments within sediments deposited during fair weather. Composite beds deposited during a given wave cycle by storm rip currents are closely similar to ‘turbidites’ and many so called ‘fluxo‐turbidites’ described from flysch deposits. Using data gathered in studies conducted on the modern Baltic coast, supplemented by experimental work and theoretical considerations, a sedimentary model is proposed. The model may be used to interpret possible rip current deposits among shallow water ‘turbidites’, and both modern storm sediments and ancient ‘tempestites’.
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