Moisture relationships for the Southern Hemisphere

Values for mean precipitable water are computed for four seasons of the year and for different regions of the Southern Hemisphere. Relationships between surface dew-point temperature and precipitable water were studied for these regions. A harmonic analysis of our data on precipitable water is attempted. Out results are presented and discussed.     

Studies on radiation balance at a tropical station

Summary Studies of various radiation fluxes, namely solar radiation, albedo (reflection coefficient), long-wave radiation of the earth and the atmosphere and net radiation observed at a tropical station are presented in this paper. The time variation of these fluxes are examined in relation to various meteorological parameters and atmospheric conditions.The constants of the general radiation balance equation are determined. The calculated radiation balance equation with new constants for the station isR=0.86 (1–)S–4.2. A high correlation coefficient 0.99 is obtained between net short-wave radiation (1–)S and net radiationR. The radiation balance at a tropical station is evaluated. It is found over a year there is a net surplus of 94 kilo-langleys.     

Study of sensible fluxes from different climatic stations

Summary Two methods of the evaluation of sensible heat flux are briefly presented from the view point of their application to micrometeorology. The comparison of sensible fluxes for coastal and inland stations is presented, in order to explain the influence of the marine atmosphere on these fluxes. They reach a maximum value in summer at the coastal stations, due to maximum wind speed and high convective activity developed by the influence of the marine atmosphere.     

Energy flux partitioning over the Amazon forest

The present study involved determination of the experimental energy receipt partitioning over the tropical Amazon forest. Diurnal variation of net radiation (Q ^*), sensible heat flux (Q _H) and latent heat flux (Q _E) is presented. The daytimeQ _E is in phase withQ ^* and it is always an important term in the energy balance. The daily averagedQ _E is 59 to 100% of the dailyQ ^* whereasQ _H is 5 to 28% at the Amazon forest site (2° 57 S; 59° 57 W) for the sample periods. The results present evidence thatQ _E over the Amazon forest is greater thanQ ^* in the afternoon hours. The role of sensible heat advection in maintaining largeQ _E over the forest surface is discussed. Hourly Bowen ratio () values for two campaigns of the Amazon forest micrometeorological experiment are presented. During daylight hours, the differences in are not significant, and exhibit a systematic pattern. The only time that the variation in Bowen ratio increased significantly was at sunrise and sunset when the thermal structure of the air was changing from a strong inversion to lapse and vice versa. The diurnal values changed from –3.50 to 0.85. The mean hourly calculated from values from 07.00 to 16.00 h, varied from 0.05 to 0.85.Diese Studie beschäftigt sich mit der Aufteilung der empfangenen Energie über dem tropischen Amazonasurwald. Es wird der Tagesgang der Strahlungsbilanz (Q ^*), des fühlbaren (Q _H) und des latenten Wärmestromes (Q _E) vorgestellt. Während der Tagesstunden istQ _E in Phase mitQ ^* und ist immer ein wichtiger Term der Energiebilanz. Das Tagesmittel vonQ _E beträgt 59 bis 100%,Q _H 5 bis 28% des täglichenQ ^* an den Meßtagen bei der Amazonasurwaldstation (2° 57 S; 59° 57 W). Die Ergebnisse legen nahe, daß in den NachmittagsstundenQ _E über dem Amazonasurwald größer ist alsQ ^*. Die Rolle der Advektion von fühlbarer Wärme zur Aufrechterhaltung des großenQ _E über der Waldoberfläche wird diskutiert. Für zwei Meßkampagnen wurden die stündlichen Bowenverhältnisse () vorgestellt. Während der Tagesstunden ergaben sich keine signifikanten Änderungen von, während bei Sonnenaufgang und -untergang, wenn der thermische Aufbau der Luft von einer starken Inversion zu neutral und umgekehrt wechselt, die Unterschiede deutlich anstiegen. Die Tageswerte von lagen zwischen –3.50 und 0.85. Die Stundenmittel von 7.00 bis 16.00 Uhr schwankten zwischen 0.05 und 0.85.

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With 3 Figures     

Air pollution potential over South India

The potential of the atmosphere to disperse and dilute pollutants emitted into it by myriad sources, depends upon various factors such as wind, vertical mixing, inversion of temperature in the vertical, etc. A study of such parameters is attempted in the present article over south India. The spatial distribution of isothermals, inversions, lapse conditions, mixing heights and ventilation coefficients over south India is studied for the months of January, April, July and October, which are typical of winter, premonsoon, monsoon and post monsoon seasons, respectively. Diurnal variations are also studied.     

Land Surface Layer Characteristics During Monsoon at a Tropical Station

—The atmospheric surface layer over land may behave differently in the tropics, particu larly during the monsoon. A preliminary attempt is made to observe the behavior of surface layer characteristics such as fluxes of momentum, sensible heat and latent heat, friction velocity, friction temperature, M-O length scale, Richardson number and Bowen’s ratio over Kharagpur (22°20′N, 87°18′E), a typical moist tropical station. The diurnal and day-to-day variations have been studied. It is observed that during the active phase of the monsoon the sensible heat flux and Bowen’s ratio are low. The diurnal variation is apparent for most parameters. Mostly near neutral conditions are observed.     

Variations in Concentrations and Fluxes of Dimethylsulfide (DMS) from the Indian Estuaries

In order to examine the variations in concentrations of dimethylsulfide (DMS) and its fluxes to the atmosphere, 25 major and medium estuaries from Indian subcontinent were sampled during wet and dry periods. River discharge brought substantial amount of nutrients and suspended particulate matter (SPM) to the Indian estuaries; however, the concentration of phytoplankton biomass was severely limited by latter due to shallowing of photic depth. Bacillariophyceae was the dominant phytoplankton group in the Indian estuaries followed by green algae, Cyanophyceae, and Dinophyceae. Relatively higher concentrations of DMS were observed in the estuaries located along the east (3.6 ± 5.7 nM) than the west coast of India (0.8 ± 0.3 nM) during wet period whereas no significant differences were observed during dry period. The concentrations of DMS were significantly lower during wet than dry period and it was consistent with the phytoplankton biomass. The slope of the relation between DMS and phytoplankton biomass displayed a significant spatial variation due to contribution of different groups of phytoplankton in the Indian estuaries. The concentrations of DMS in the Indian estuaries were higher than other estuaries in the world except some Chinese estuaries. The annual mean flux (1.95 ± 2.5 μmol m^?2 day^?1) from the Indian estuaries is lower than that of other estuaries in the world, except Pearl River estuary due to inhibition of phytoplankton growth by suspended load and low flushing rates.     

A preliminary study of precipitable water over Brazil

A preliminary study of precipitable water over Brazil is attempted. Mean values for January are presented in this paper. A regression equation connecting the surface dew-point temperature and the precipitable water was computed along the lines of studies made by Reitan (1963), and the results are presented.     

An estimation of wind energy along the Indian coasts

Of several non-conventional energy sources, wind is probably the most suitable and cost effective for generating electricity and for water pumping. It is essential to establish the available wind energy (AWE) for any given region so as to assess the relative potential at different sites. In the present paper, an attempt is made to study the AWE over south India, an area that is peninsular in nature. A climatological estimate is made for January. April, July and October which are typical of winter, pre-monsoon, monsoon and post-monsoon seasons, respectively. The energy pattern factor is also estimated. The spatial and seasonal variation of AWE is studied.