Showing papers on "Monsoon published in 1971"

Coexistence of species of Acartiidae (Copepoda) in the Cochin Backwater, a monsoonal estuarine lagoon

Abstract: A study was made of copepods of the family Acartiidae which form the dominant component of the plankton in the Cochin Backwater (Kerala, India). At least nine species inhabit the backwater at one time or another, more than have been recorded for any other area. Reasons were sought for this diversity. The surface plankton was sampled from the head of the estuary to the mouth and from one season to another. There were large seasonal changes in salinity (0 to 35 ‰), due to monsoonal flooding, and associated changes in species composition. Species diversity was highest during the dry season and lowest in the wet. It is suggested that this annual catastrophic flooding leads, in the long run, to high species diversity by imposing a regular check on interspecific competition.

West Indian Ocean phytoplankton: a numerical investigation of phytohydrographic regions and their characteristic phytoplankton associations

Abstract: Phytoplankton samples were collected from a large area of the West Indian Ocean and 237 different species identified. The object of this study was to define structure in the species distributions and to relate this to environmental factors. Numerical methods of cluster analysis are described, with adaptation and application to this ecological study of phytoplankton. The phytoplankton stations were grouped according to their phytoplankton populations; these groupings were related firstly to the monsoon seasons, and secondly to the hydrology, in order to derive phytohydrographic regions. The species were then grouped according to hydrographical distribution in order to derive the floral elements (species associations) which typify the different regions. The samples divided seasonally into 2 overlapping clusters, those sampled prior to the South West Monsoon, and those sampled subsequently. In both seasonal groups 4 main phytohydrographic regions were isolated from (1) equatorial subsurface water; (2) the equatorial undercurrent boundary; (3) the South Equatorial Current; (4) the surface tropical water. A total of 11 different floral elements were derived to account for the phytohydrographic groupings. The distribution of the largest element (50 species) was centred in equatorial subsurface water. This element dominated all samples, and was considered to comprise the endemic Indian Ocean flora. The effects of the other minor floral elements were superimposed on the dominance or otherwise of this element in the samples. These different minor floral elements were characteristic of (a) different seasonal divisions; (b) regional differences in equatorial subsurface water; (c) traversing currents; (d) nutrientrich regions of instability.

Monsoonal response in the western Indian Ocean

Abstract: Infrared observations from spacecraft are used to investigate the response of the Somali Current to the onset of the southwest monsoon. Selected satellite observations from three years were available for this study (Nimbus series 1966, 1969, and 1970). The time-dependent development of horizontal temperature gradients at the sea surface serves as an indicator for the formation of the baroclinic structure of the Somali Current. A comparison is made with the simultaneous development of the southwest component of the monsoon wind. The investigation reveals that the temperature gradients during the early formation stage in all years are directly proportional to the wind speed. The phase lag between the development of wind and temperature gradient during the buildup of the boundary current has a mean value of twelve days. During the decay period in late summer and fall, the lag increases continuously up to forty days. The observations suggest that two phenomena of different spatial scales play an important role during the formation of the Somali Current; in the early stage (May, June), local wind-induced upwelling seems to be the more important source of baroclinicity; in the later stage of the buildup (July), large-scale geostrophic effects seem to be dominating.

Distribution function for seasonal and annual rainfall over india

Abstract: Distribution functions for seasonal (southwest monsoon) and annual rainfall at 53 long-record stations in India have been obtained. It was found that the frequency distributions are right skewed. Tests for normality show that while normal distribution gives a good fit to seasonal and annual rainfall at stations in some parts of India it does not give a good fit to seasonal and annual rainfall at stations over the major portion of the country. Tests of goodness of fit of the Gamma distribution, however, clearly indicate that this distribution provides a good fit to seasonal and annual rainfall at stations in different parts of the country.

Estimates of kinetic energy over the Indian monsoon trough zone

Abstract: Averaged radiosonde/rawin/pibal data for July and August have been used to study the kinetic energy budget of the troposphere over a quasi-elliptical area containing the Indian monsoon trough. Incoming and outgoing kinetic energy fluxes have been evaluated. The computations show that the export of kinetic energy from the monsoon ellipse is about 57 × 106 Joules day−1. This export takes place in the upper troposphere, mostly above 300 mb. Production of kinetic energy occurs mainly in the upper troposphere in the southern periphery of the huge quasi-static South Asiatic ridge in the upper troposphere.

Independence of monthly and bimonthly rainfall over southeast asia during the summer monsoon season1

Abstract: Independence of monthly and bimonthly rainfall has been investigated for 39 well-distributed and long-record stations in the field of the Asian summer monsoon. The study reveals: (1) monthly rainfall is pairwise independent but is not tripletwise or quadrupletwise independent and (2) rainfall during the first half of the summer monsoon season is independent of rainfall during the second half. The implications of these results are discussed.

The wind drifts off the west coast of india and their influence on the oil sardine fishery

Abstract: The wind drifts off the west coast of India during the winter season have been examined in terms of barometric pressure differences along the coastline. Changes in the oil sardine landings seem to be related to the long-term changes of the wind drifts. The data prior to the rapid growth of the fishing industry indicate that the north-east monsoon season which helps in the development or strengthening of the northerly drifts in the waters off the coast appears to be favourable for the fishery.

Surface Wind Vergence over the Tropical Indian Ocean

Abstract: From surface wind estimates published in the Dutch Atlas monthly charts of surface wind vergence over the Indian Ocean down to 50S were computed. Since the original data were smoothed by a low-pass filter, the charts exhibit only regional and large-scale features. The vergence distributions are not zonally symmetric; rather, they show a cell-like structure. The vergence patterns are discussed in terms of latitudinal-time sections, both for the Arabian Sea and the Bay of Bengal longitude range, and compared with similar plots of the precipitation frequency. North of 10–20S there seem to exist three different circulation regimes, separated by sharply defined transition periods, a characteristic of the Indian monsoon climate. A simple description of this threefold monsoonal rhythm is given in terms of the first and second harmonies of the annual march of temperature.

Coastal circulation near kakinada bay during monsoon period

Abstract: With a view of understanding the various processes responsible for the deposition of sand in the vicinity of Kakinada Bay and Godavari Point, an intensive study of currents in the coastal waters has been made using floats. The circulation has high variability in both magnitude and direction related to the three current components namely wind currents, tidal currents and wave currents. The circulation pattern rapidly changes with the change in the phase of the tide and local winds of land and see breeze. The littoral currents directed up-coast during premonsoon and monsoon seasons have insignificant effect across the bay opening due to the sheltering effect of the sand bar. The study is found helpful for understanding the geomorphological changes of the shoreline in this region from time to time.