A cooperative synchronous observation of winds in the tropical lower stratosphere and mesosphere was carried out using VHF radars at Jicamarca (11.95°S, 76.87°W) and at Arecibo (18.35°N, 66.75°W) on 19-21 or 23 November 1981. The comparison between observations about symmetrical north and south of the equator is focussed on the mean and tidal wind characteristics. Vertical structures of the mean zonal winds at both observational stations are in fairly good agreement with the CIRA (1972) zonal circulation model at the corresponding latitudes. The nature of lower stratospheric diurnal tides is similar between Jicamarca and Arecibo. Their vertical profiles generally correspond to the theoretical predictions based on the fundamental tidal modes. The vertical scale of the tidal components including higher-order modes is shown to be longer than 10km. In the mesosphere, vertically propagating diurnal tide which is expected to be predominant at lower latitudes is partially detected in daytime at Arecibo, while it is not so well-defined at Jicamarca, suggesting a variable nature of the relevant tidal modes.

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The lidar measurements on polar stratospheric aerosols at Syowa Station (69°00′S, 39°35′E), Antarctica revealed that the content of stratospheric particulate matter noticeably increased in winter. Two different phases were found in the winter enhancement event of the Antarctic stratospheric aerosol layer. In the first phase of the enhancement the layer thickness increased to about 15km, but in the second phase the thickness of the layer gradually decreased although the column density of the aerosol particle was as large as that of the first stage. The height of aerosol layer center defined by ∫Z B₂ (Z) dZ/∫B₂ (Z) dZ, Z and B₂ (Z) are height and the backscattering coefficient of aerosols respectively, also had similar tendency with the layer thickness. These changes seem to be associated with the movement of the very cold region with lower than -80°C in winter stratosphere.

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By the impedance probe (IMP) on board the Hinotori satellite, that was launched on February 21, 1981, into the semi-equatorial orbit with inclination of 31° and nearly constant altitude of 650km, data of electron density profiles along more than 1500 orbits have been obtained with an error less than ±3%. The detected profiles of electron density contain the data of the equatorial plasma bubbles. Preliminary statistic studies on the occurrence frequency indicate that there are at least three types of the plasma bubbles. The plasma bubbles that belong to the first type grow mainly from the evening to the midnight period with large depletion rates of electron density; since the depletion regions are sequencially aligned those are called here multiple plasma bubbles (MPB). The second type plasma bubbles are enhanced mainly after midnight, even in sunlit condition, with periodic features and are called here quasi periodic plasma bubbles (QPB). There is a third type of plasma bubble characterized by its solitary features called here solitary plasma bubble (SPB). The SPB phenomena takes place in all of the night time period. In the topside region of the ionosphere near the edge of the occurrence region of the plasma bubble, there frequently appear electron density enhancements with deviation of a few percent to the background electron density. These newly discovered phenomena are called here plasma blob. Occurrence characteristics of the plasma blob are also discussed.

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The statistical analyses of occurrence characteristics of the plasma bubbles and blobs are made by using more than 1000 cases of observation data from the swept frequency impedance probe aboard the Hinotori satellite. The results show that formations of the plasma bubbles have the following characteristics. 1) The spatial distribution of the occurrence of the plasma bubbles is in the equatorial region within ±30° of the magnetic dip latitude centered around the magnetic equator, 2) the occurrence of the plasma bubbles is limited in the nighttime; favorable periods of the plasma bubble formation depend on the type of the plasma bubbles; multiple plasma bubbles (MPB) have tendency to be generated in pre-midnight, while quasi periodic plasma bubbles (QPB) show their maximum occurrence in the post-midnight period. Solitary plasma bubbles (SPB) occur, however, rather independently to the local time in so far as in the night period, 3) the magnetic activity also controls the occurrence of the plasma bubbles; the occurrence of MPB phenomena shifts the peak period to the midnight side with increasing magnetic activity and the occurrence of QPB phenomena which covers the period from midnight to the morning side shows the expansion of their occurrence into late morning period with increasing magnetic activity, 4) correlation of the occurrence of the plasma bubbles to the solar radiation flux represented by F_10.7 solar radio flux is evident for MPB and QPB while there is no relation between F_10.7 and the occurrence of SPB. Occurrence of the plasma blobs has a complementary nature with that of the plasma bubbles. The occurrence region of the plasma blobs is limited in the edge parts of the plasma bubble occurrence region being limited in the nighttime. The occurrence of the plasma blobs decreases with increasing magnetic activity, while there is a strong anti-correlation of the occurrence of the plasma blobs to the solar radiation (F_10.7). The relation of occurrence of the plasma bubbles and blobs to the development of the equatorial anomaly and the asymmetrical distributions of the background electron density suggests the importance of the generalized Rayleigh-Taylor instability including the effects of the electric field and the neutral wind in addition to the gravitational force for the generation of the plasma bubbles and blobs.

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A significant area of abnormal conductivity, directed substantially SW-NE, can be found by studying the variations of the total intensity of the earth's magnetic field in the Montagne Pelée volcanic massif. The extremum of that abnormal effect occurs on the SW slopes of the volcano in the vicinity of the Morne Plumé. That result means an abnormally conductive feature that is probably to be related to the regional tectonics, directed SW-NE in the north of the Martinique island.
The search for a possible volcanomagnetic effect that would accompany the activity of the volcano itself is conducted in such a way that the transient variations (“reduction defects”) encountered throughout the massif are taken into account. Through continuous computer recording of magnetic data, the transient variations over 24 hour long periods can be evaluated quite readily and a simple relationship can be proposed to account for a possible volcanomagnetic effect and the uncertainty about it. Thanks to the digital acquisition system, that effect can be assessed on a daily basis or at a higher rate.

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