Showing papers on "Monsoon published in 1968"

Upwelling along the east coast of India

Abstract: An examination of the physical characteristics of the shelf waters off Karaikal in the premonsoon period and off Madras and Waltair in the premonsoon and monsoon periods reveals the presence of upwelling along the East Coast of India but with the following differences: (1) Off Madras and Karaikal, weak upwelling is indicated. Water from shallow depths reach the surface nearshore and there is no marked lowering of the surface temperature near the coast. (2) Upwelling is prominent off Waltair during the premonsoon and monsoon periods. Waters from deeper layers of the shelf appear to reach the surface causing considerable fall of surface temperature near the coast. The probable causes for these differences in upwelling along the coast are discussed.

Carbon dioxide in surface ocean waters: 3. Measurements on Lusiad Expedition 1962-1963

Abstract: Direct measurements of carbon dioxide in equatorial surface waters during Lusiad Expedition, 1962–1963, indicate that high concentration relative to atmospheric CO2 is associated with eastward-flowing equatorial undercurrents in the Indian and Atlantic oceans. In the tropical Indian Ocean the measurements are sufficient to construct the areal distribution during two seasons. A broad band of high CO2 occurs during the northeast monsoon but not during the southwest monsoon. An undercurrent is observed only during the former period. Adjacent to the equatorial zone the CO2 concentration is generally lower than equilibrium with the atmosphere in all oceans. In the South Indian Ocean the concentration rises sharply southward on approaching the northern limit of the antarctic circumpolar current. In the western North Pacific Ocean the concentration attains very low values in the east-flowing extension of the Kuroshio Current. In general, low concentration in surface waters exists when rapid cooling occurs and when withdrawal of CO2 by marine organisms exceeds replenishment by physical transport; high concentration exists when rapid warming occurs and when upwelling or vertical mixing supplies more CO2 than can be withdrawn by plants or can escape to the atmosphere.

Diurnal rainfall variation in malaya1

Abstract: In low latitudes, where seasonal differences of climate are small and usually limited to factors such as winds and precipitation, the weather is largely controlled by diurnal processes. The diurnal variation of rainfall is the most important result of these processes and it is a characteristic part of the climate. In Malaya, diurnal rainfall regimes show seasonal variations, which are closely related to the system of the southeast Asian monsoons. The seasonal variations differ according to location, and three regional types can be recognized, which are found, respectively, at the west coast, the east coast, and at inland stations. Singapore, because of its extreme location at the southern tip of the peninsula, does not fit in this classification.

Weather patterns in Southern West Pakistan

Abstract: Southern West Pakistan is an area of transition between the Indian summer monsoon system to the east and the winter cyclonic system of southwest Asia to the west. As a transition area, it receives scanty, unreliable rainfall averaging less than 10 in. (254 mm) per year from several storm types. Six main weather patterns cross the region: the large subtropical anticylonic high pressure cell which predominates most of the year; western depressions originating over the Mediterranean Sea; Arabian Sea cyclones; local thunderstorms and dust storms; a modified monsoon pattern; and eastern depressions originating over the Bay of Bengal or central India. A discussion of the physical and synoptic characteristics for each weather pattern and storm type is presented and summary charts of the weather patterns are included.

On the instantaneous distribution of vertical velocity in the monsoon field and structure of the monsoon circulation

Abstract: An approximate representation of the instantaneous three-dimensional circulation of the Asian summer monsoon has been obtained using data and analysis at a given map time in July 1963 during the International Indian Ocean Expedition (1963–65). For this purpose, vertical velocity was computed using the continuity equation and by stepwise integration of the divergence field, at the standard isobaric levels at every five-degree grid-point along seven meridional sections extending from 50° E to 140° E between latitudes 35° N and 25° S. In conjunction with the meridional and zonal components of the winds, the vertical velocities yielded the instantaneous vertical circulation patterns and these are presented along seven meridional and four zonal sections. The isobaric distribution of vertical velocity is presented along four standard pressure surfaces, viz. 850, 700, 500 and 100 mb. The computed vertical velocities show three well-defined updraft areas over the landmass of Asia, one over Arabia, one over India, and the third over China. A few localized updraft cells of feeble intensity appear over the sea areas, e.g. one in the equatorial region between Gan Island (00°41? S, 73°09? E) and Indonesia and another in western central Pacific, east of the Philippines. Extensive downdraft areas are found over the land area between India and Arabia, over western Himalayas and Tibet, and over most of the sea areas lying to the south of the continental landmass. Practically the whole of the west Arabian Sea appears under intense downdraft. Over many areas, however, the computed vertical velocities increase continually with height showing little or no vertical compansation. This is, of course, due to analysis Notwithstanding this basic problem, the computed vertical velocity patterns are found to be compatible with the observed distribution of temperature, humidity, vorticity, rainfall, and jet streams. The presence of a belt of equatorial westerlies (south of the Equator) in the Indian Ocean area would also seem to support computed updraft in this region. The evidences furnished in the paper strongly suggest that it is only a three-dimensional thermal convective model that can describe the giant monsoon circulation over the north Indian Ocean and adjoining Asian continent adequately. DOI: 10.1111/j.2153-3490.1968.tb00403.x

An analysis of upwelling off the south-east Arabian coast during the summer monsoon

Abstract: approved: Robert L. Smith A method is described for determining the absolute dynamic topography of the sea surface. Using hydrographic and wind data obtamed in 1963, the surface topography and the horizontal and vertical mass transports off the southeast Arabian coast during the summer monsoon are calculated. As indicated by the calculations, upwelling occurs throughout a region extending at least 400 km offshore and paralleling the Arabian coast for over 1000 km. Upwelling is most intense in a narrow band adjacent to the coast. Because of the great breadth of the upwelling zone, the upwelled water is supplied from levels considerably deeper than those observed elsewhere in coastal upwelling areas. Redacted for Privacy An Analysis of tJpwelling off the Southeast Arabian Coast During the Summer Monsoon

Air-Mass Dynamics or Subsidence Processes in the Arabian Sea Summer Monsoon?.

Abstract: Two papers with the same title, \"The Summer Atmospheric Circulation over the Arabian Sea\", were recently published in this JOURNAL (Ramage, 1966; Desai, 1967), which gave different opinions to aproblem which has been under discussion for several years, i.e., Is the Inversion over the Arabian Sea and over northwest India and West Pakistan due to conversative air-mass properties or due to subsidence? Desai considers the former interpretation, substantially valid up to some years ago, while Ramage's paper makes a contribution to more quantitative considerations of the effects of large-scale subsidence in causing the droughts in parts of the Arabian Sea and northwest India. In the Meteorological Institute of the University of Bonn investigations of this problem have also been made; the results will be presented in two maps. 2. Divergence and convergence over the Arabian Sea

Atmospheric and precipitation radioactivity in India

Abstract: The contribution of the major nuclear weapon test series in 1961 and 1962 to the ground-level activity in India during 1962–1965, has been estimated from fission product ratios in the ground-level air and precipitation samples collected at eight stations in India. Induced activity Mn-54 produced in the 1961 and 1962 tests has also been examined in relation to the fission product activity. Fission products Cs-137, Sb-125, Ru-106, Ce-144 and Zr-95, and induced activity of Mn-54 were estimated by gamma spectrometry. These measurements have also shown that, ( a ) while the well known spring increase is observed at all these stations, the time of peak values show significant differences at the various stations which could be related to the monsoon winds, ( b ) the gradient in activity along the latitude band of 10° N–32° N shows seasonal differences which can also be attributed to changes in surface winds, ( c ) Mn-54/Cs-137 activity ratios show that the radioactive debris present at high altitudes during 1962 had started descending to ground-level by the spring of 1963. Concentrations of natural isotope Pb-210 were also measured at all these stations. Seasonal variations in Pb-210 differed markedly from the seasonal variations in Cs-137. However, both Cs-137 and Pb-210 show higher levels at the stations in the northern latitudes in India. On the basis of the measured ground-level concentrations of fission products in 1963, 1964 and 1965, estimates of stratospheric residence time have been discussed. DOI: 10.1111/j.2153-3490.1968.tb00368.x

Causes of aridity and inversion over the desert areas of West Pakistan and neighbourhood during the south-west monsoon season

Abstract: Views of Flohn (1965, 1966) and of Ramage (1966) regarding the causes of aridity and inversion over the desert areas of West Pakistan and neighbourhood have been examined. It is shown on the basis of climatic features of the area that the inversion is due to air masses andnot due to subsidence; the aridity of the region is due to absence usually of a mechanism which can break up the inversion andnot due to the restricted depth of the moist current.

Forecasting minimum cloudiness over the red river delta during the summer monsoon

Abstract: : The amount of convective cloudiness over Southeast Asia during the summer monsoon responds to synoptic scale circulation changes Minimum cloudiness of less than 3/10 over the Red River Delta occurs under lower tropospheric ridging Case study analyses of the synoptic changes which produce sufficient ridging in depth are presented to demonstrate (1) clearing in advance of typhoons, and (2) the early July singularity of 5 to 7 days of fine weather over North Vietnam and southern China caused by the northward progression, from the equatorial region, of the 'buffer' system A case study is also presented to show the combination of synoptic changes which are favorable for the development of tropical storms in the South China Sea (Author)

Surface Winds Over the South China Sea During the Northeast Monsoon Season.

Abstract: : Meteorological services in support of South China Sea naval operations during the Northeast Monsoon season may conveniently be divided into three parts, insofar as the surface wind field is concerned: (1) Specification of the current wind field, especially of wind speed; (2) prediction of monsoon 'surges'; and (3) special computations regarding the 'Gulf of Tonkin Eddy.' These three topics are discussed in the report.

Some inferences on the equatorial undercurrent inthe Indian Ocean based on the physical properties ofthe waters

Abstract: The International Indian Ocean Expedition, conducted during the period 1960-65, has provided a good amount of oceanographic data facilitating a study of the various features of the Equatorial Indian Ocean, which is least investigated of the three major Oceans, from the point, of view of the current structure. One of the most fascinating problems of the study during the expedition concerns the subsurface currents. In view of the unique nature of the Indian Ocean due to its exposure to the monsoons, a study of the Equatorial Undercurrent in the Indian Ocean and its differences from the Equatorial Undercwrents iji the other two major Oceans will be of special significance and interest. It is possible that a good knowledge of the subsurface currents of the Indian Ocean should help in gaining understanding of the true nature of the Undercurrent and in evaluating the various conflicting explanations of the Pacific and Atlantic Equatorial Undercurrents.

Temperature Salinity, and Density of the World's Seas: East China Sea.

Abstract: : The variation and distribution of temperature, salinity, and density in the East China Sea are influenced by the monsoonal rains, continental runoff, waters of the Kuroshio, and bottom topography. During the winter monsoon, mixing produces a homogeneous vertical water structure over the Continental Shelf and a deep mixed layer in the basin portion of the sea. Conversely, during the summer monsoon, a warmer, less saline surface layer develops as a result of increased solar radiation, continental runoff, and precipitation. (Author)