Effect of volcanic debris on stratospheric ion conductivity

The reduction is reported of stratospheric ion conductivities in the altitude range of 20 to 27 km attributable to the aerosols injected into the stratosphere by the eruption of volcano Nevado Del Ruiz on November 13, 1985. Three balloon experiments were conducted from Hyderabad, India (17.5 N, 78.6 E) carrying a Langmuir probe payload for measuring stratospheric ion conductivities. The first flight took place about 9 months before the volcanic eruption, the second 3 weeks after the eruption and the third about a year later. Lidar observations from Japan, Hawaii and Europe reported detection of aerosol layers in the 18 to 25 km altitude range attributable to the Nevado Del Ruiz volcanic eruption. A comparison of the conductivity profiles shows that the reduction of ion conductivities is: 57.3 percent at 20 km and 31 percent at 25 km. A year after the eruption, conductivities at all heights tended to recover

Sequential sporadic-E layers at low latitudes in the Indian sector

International audienceA study of the formation and movement of sequential Sporadic-E layers observed during the night-time hours at two Indian low-latitude stations, SHAR (dip 10°N) and Waltair (dip 20°N) shows that the layer are formed around 19:00 h. IST at altitudes of ~180 km. They descend to the normal E-region altitude of about 100 km in three to four hours and becomes blanketing type of Es before they disappear. However, the absence of these descending layers at an equatorial station, Trivandrum (dip 2°N) gives the experimental evidence for wind shear theory. The meridional neutral wind derived from the height variation of the F-layer showed significant poleward wind during the descent of these layers. Hence it is inferred that these layers are formed as a consequence of the convergence of plasma by the poleward wind and the equatorward propagating gravity waves (inferred from the height fluctuations of F-layer)

Search for physiologically active compounds. Part IX. Synthesis of naphthoxazoles from amino-naphthols and aromatic aldehydes

2-Aryl naphth-(1, 2) and naphth-(2, 1) oxazoles have been prepared by condensing 2-amino 1-naphthol and 1-amino 2-naphthol hydrochlorides respectively with nine aldehydes. The isomeric naphthoxazoles can be distinguished by the IR and UV absorption spectra

Prawn seed exploitation along Kakinada coast : a preliminary appraisal with a note on the brooder exploitation of Penaeus monodon

In recent times there is a steep increase in the exploitation of prawn seed in order to cater to the needs of prawn fanners along the Andhra Pradesh coast. There is demand mostly for seed P. monodon by the prawn farmers of this state. There are no official or reliable estimates of the total extent of prawn farms in Andhra Pradesh

Occurrence of whale shark off south Andhra coast

The whale shark Rhincodon typus known to occur In the Indian seas is occasionally caught by gill-nets, purse-seines and trawls. A male whale shark measuring 4.45 m in length caught in a trawlnet on 24-9-1992 at a depth of about 40m off Anthervedi Palli Palem, nearly 100 km south of Kakinada was landed at Kakinada

AMS facility at institute of physics, Bhubaneswar: inter-laboratory comparison of results

Radiocarbon dating has found wide applications in many areas of science like archaeology, geology, oceanography, palaeoseismology and palaeoclimatology. As a tracer, radiocarbon has applications in biology and medicine. Radiocarbon dating using Accelerator Mass Spectrometry (AMS) provides several advantages over the conventional decay counting method. The first AMS facility in India for radiocarbon dating has become operational at the Institute of Physics, Bhubaneswar. This note describes the operational features of this facility and inter-laboratory comparison of data

Results of rocket measurements of D-region ionization over Thumba in MAP

Under MAP, two rockets were launched from Thumba (8.5 N, 76.8 E) around 1030 hrs Lt with identical payloads on 7 and 10 March 1986 for D region studies. Positive ion densities were measured by spherical probe and Gerdien condenser and electron densities were measured by Langmuir probe and propagation experiments. In both flights a valley in ionization height profile was noticed around 83 km. The density of ionization at this altitude was about 4 x 10(2) cu cm. A detailed positive ion-chemical scheme was used to reproduce the measured ionization height profiles. The density of NO needed to reproduce the valley in ionization at 83 km came around 5 x 10(5) cu cm. A photochemical treatment without diffusion process was found inadequate to explain this value of NO. Calculations showed that the value of vertical eddy diffusion needed to reproduce the value of NO was around 10(6)sq cm/s. Interestingly, the same value of eddy diffusion coefficient was obtained when derived in the manner described by Thrane and his coworkers using only the positive ion current data of spherical probes