A study of atmospheric structures using sodar in relation to land and sea breezes

Simultaneous observations were made by an acoustic sounder and on a meteorological tower during the month of May 1978 at the Atomic Power Station Tarapur. The probing range of the acoustic sounder was 700 m. The meteorological tower could sense wind and temperature at various levels up to a height of 120 m.The site being close to the sea shore, the thermal environment of the lower atmosphere is controlled mostly by land and sea breeze circulations. Thermal convective structures were seen during the daytime and also at night. The frequency of plume formation and the height of the plumes were, however, low during the night. The convective boundary layer in the daytime ranged from 400–500 m while at night it was mostly under 200 m. The observation of thermals at night is explained by the presence of a naturally stable marine layer above 30 m at this site. In the morning hours, winds suddenly change their direction allowing advection of a land breeze which is responsible for the formation of surface-based shear echoes to a height of 200 m during the transition period and for the subsequent development of an elevated layer due to mixing of two different air masses. A marine layer was also seen over Tarapur for a few days during the early evening and night hours. Its height was mostly around 400 m. It may indicate the presence of a subsidence inversion at Tarapur. The need for collection of supporting meteorological data to a height of 500 m by tethered balloon or some other suitable in-situ technique is stressed.     

Studies of the atmospheric stability characteristics during the solar eclipse of February 16, 1980

Observations made with a monostatic sodar and from a 120 m instrumented tower have been used to study the variations in the atmospheric boundary layer at Tarapur (19° 50 N, 72° 41 E) during the solar eclipse of February 16, 1980. Atmospheric instability was reduced below normal values during the eclipse but the atmosphere at no time became stable.     

Mapping and characterization of inland wetlands using remote sensing and GIS

Sustainable management of wetland ecosystem is necessary as it serves the important functions such as food storage, water quality maintenance and providing habitat for different species of wildlife. Hence, an inventory of wetlands in any given area is a pre-requisite for their conservation and management. A study has been carried out to delineate the wetlands of east Champaran district of Bihar, India, using IRS ID LISS III data. The data for the pre and post monsoon seasons have been analysed and the wetlands have been qualitatively characterized based on the turbidity and aquatic vegetation status. The extent of water logging problem in the study area was inferred from the seasonal variation of waterspread during both the seasons. The three categories of wetlands (ponds/lakes, water logged areas and oxbow lakes) have been identified. From the analysis, it has been observed that the inland wetlands constitute 2.7% of the study area, of which 1.8% is subjected to water logging. Thus, this study highlights the usefulness of remotely sensed data for wetland mapping, seasonal monitoring and characterization.     

Modelling of non-point source pollution in a watershed using remote sensing and gis

Assessment of the environmental impact of Non Point Source (NPS) pollutants on a global, regional and localized scale is the key component for achieving sustainability of agriculture as well as preserving the environment. The knowledge and information required to address the problem of assessing the impact of NPS pollutants like Nitrogen (N), Phosphorus (P), etc., on the environment crosses several sub-disciplines like remote sensing, Geographical Information System (GIS), hydrology and soil science. The remote sensing data, by virtue of its potential like synopticity, multi-spectral and multi-temporal capability, computer compatibility, besides providing almost real time information, has enhanced the scope of automation of mapping dynamic elements, such as land use/land cover, degradation profile and computing the priority categorisation of sub-watersheds. The present study demonstrates the application of remote sensing, GIS and distributed parameter model Agricultural Non-Point Source Pollution Model (AGNPS) in the assessment of hazardous non-point source pollution in a watershed. The ARC-INFO GIS and remote sensing provided the input data to support modelling, while the AGNPS model predicted runoff, sediment and pollutant (N and P) transport within a watershed. The integrated system is used to evaluate the sediment pollution in about 2700 ha Karso watershed located in Hazaribagh area of Jharkhand State, India. The predicted values of runoff and sediment yield copared reasonably well with the measured values. It is important to emphasize that this study is not intended to characterise, in an exhaustive manner. Instead, the goal is to illustrate the implications and potential advantages of GIS and remote sensing based Hydrology and Water quality (H/WQ) modelling framework.     

Geo-limis - a decision support system for minimizing locust impact in republic of kazakhstan

Desert locusts (DL) are serious problem during April to August in the deserts and semi-deserts of Republic of Kazakhstan and causing extensive crop damage. There is no institutional and functional mechanism to forecast the habitat of locusts and most of the area remains unnoticed after laying eggs. The key to improve DL forecasting and control depends on the collection and generation of historical database on locusts, weather and habitat from affected region. Looking at the problem, a Spatial Decision Support Systems (DSS) has been developed on ARC/INFO GIS with ergonomic user interface for ingestion and subsequent analysis of locust related information vis-à-vis bio-physical and climatic data acquired from various satellite sensors and hydromet weather server respectively, to identify high frequency breeding areas well before the physiological development is completed. Weather based analytical models for physiological development of DL has been dovetailed with the SDSS for facilitating historic and present data analysis in relation to locust activity. This has augmented the surveying capability and better forecasting.     

Direct delivery of remote sensing data to user computer systems using satellite-based data broadcast techniques

The remote sensing applications are growing very rapidly with the availability of high-resolution data from the state of the art satellites like IRS-1C/1D/P4. The advancement in computer hardware and software in the area of remote sensing also enhance the growth of remote sensing applications. IRS-1C/1D/P4 provides data with the resolution of 5.6m in panchromatic mode giving more information of the ground area covered. The remote sensing satellites with high-resolution sensors and wide coverage capabilities will provide the data with better resolution, coverage and revisit to meet the growing application needs. Many applications like crop acreage and yield estimation, draught monitoring and assessment, flood mapping, waste land mapping, mineral prospectus, forest resource survey etc., have become an integral part of the resources management system in the developing countries. These resource management systems need the data to be transferred in real time or near real time for processing. The transfer of data in real time or near real time calls for advanced data delivery techniques to deliver the data as quickly as possible. Processing of remote sensing data can be performed even on low cost personal computers, which in turn further increases the remote sensing applications enabling by setting up the processing centers even at grass root level i.e., at district, taluk or village level. Setting up of processing centers at grass root level demands for quick, cost effective and efficient data delivery mechanism to transfer remote sensing data with or without value added services. The digital revolution has reached broadcasting with the introduction of direct broadcasting of digital data. These modify the traditional data transfer techniques by separating the actual service from the transmission system, thus enabling the distribution of any kind of digital data to stationary, portable or mobile terminals. This allows remote sensing data to reach a large number of users simultaneously and independent of their location. This article highlights the concepts, possibilities, and implementation mechanisms to realize the remote sensing data transfer through direct broadcasting technique and enhance remote sensing applications.     

Studies of the Marine Boundary Layer at Tarapur

Simultaneous observations were made of the Marine Boundary Layer at Tarapur, a site near Bombay on the sea coast, by acoustic sounder and instrumented tower. The meteorological tower was used to sense wind and temperature at various levels up to a height of 120 m while the acoustic sounder was used to examine the thermal structure of the boundary layer up to a height of 700 m. Data recorded for the year 1982 have been analysed.Analysis of the data shows that while the normal structures of thermal echoes and shear echoes represent the mixing depth of the atmospheric boundary layer, the often observed elevated layers are due to sea breeze reversals with their base giving a measure of the depth of the sea-breeze circulation during the day. A sea breeze has been detected during both spring (March to May) and autumn (October to December) months. The onset times are around 1000 hr during spring months and around noon during the autumn period, the height of development being respectively up to 500 and 350 m. The capability of the sodar to detect the base and thickness of the sea breeze, is clearly revealed.