Space technology and oceanography

Space Technology has developed modern sensing devices which carried on aircraft and spacecraft platforms can obtain repetitive synoptic data over large oceanic areas. It has also developed aspects of systems-theory, information-theory, data processing methodology etc., which can be applied to the large volumes of data collected over the oceans. This integrated technique of surveying oceans for its resources is known as Remote Sensing. Water colour, sea-state, surface winds, temperature, chlorophyll, surface-currents, sediment transport and surface salinity are some of the parameters collected through Remote Sensing. The data so collected have applications to shipping, meteorology, coastal geography and marine biology. It is suggested that it is time for drawing up plans for taking observations over specific sites in the Arabian Sea and the Bay of Bengal from aircraft and ocean-craft platforms simultaneous with the expected overflights of NASA's Earth Resources Technology Satellites, already orbited and to be orbited in future

Introduction to remote sensing

Remote sensing consists of gathering information about objects and features without placing instruments in contact with them. The sensors are placed on aircraft or spacecraft platforms and the earth’s surface surveyed for its natural resources. Electromagnetic radiation (EMR) in the visible, infrared and microwave bands are employed, mostly solar radiation or natural emissions. The interactions of EMR with the objects are impressed as "signatures" on the reflected, scattered, transmitted or emitted EMR. The sensors employed are (i) cameras with normal or special films sensitive to infrared, (ii) electro-optical systems in the scanning mode using solid state detectors, (iii) imaging tubes and devices and (iv) microwave systems which can gather data even when clouds intervene. The data gathered with the sophisticated systems are converted into imagery or directly processed on electronic computers. The processed data are then interpreted in terms of known ground truths or 'EMR signatures' of the objects. Remote sensing has wide applications in agriculture, forestry, geology, hydrology cartography and oceanography

On the multiple spots and streamers exhibited by the (111) dynamic reflections in diamond

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Extreme daily rainfall in Pakistan and north India: scale-interactions, mechanisms, and precursors

While much of India is used to heavy precipitation and frequent low-pressure systems during the summer monsoon, towards the northwest and into Pakistan, such events are uncommon. Here, as much as a third of the annual rainfall is delivered sporadically during the winter monsoon by western disturbances. Such events of sparse but heavy precipitation in this region of typically mountainous valleys in the north and desert in the south can be catastrophic, as in the case of the Pakistan floods of July 2010. In this study, we identify extreme precipitation events (EPEs) in a box approximately covering this region (65◦ -78◦W, 25◦ -38◦N) using the APHRODITE gauge-based precipitation product. The role of the large-scale circulation in causing EPEs is investigated: it is found that, during winter, they often coexist with an upper-tropospheric Rossby wave train that has prominent anomalous southerlies over the region of interest. These winter EPEs are also found to be strongly colocated with incident western disturbances whereas those occurring during the summer are found to have a less direct relationship. Conversely, summer EPEs are found to have a strong relationship with tropical lows. A detailed Lagrangian method is used to explore possible sources of moisture for such events, and suggests that in winter, the moisture is mostly drawn from the Arabian Sea, whereas during the summer, it comes from along the African coast and the Indian monsoon trough region

Anthropogenic Space Weather

Anthropogenic effects on the space environment started in the late 19th century and reached their peak in the 1960s when high-altitude nuclear explosions were carried out by the USA and the Soviet Union. These explosions created artificial radiation belts near Earth that resulted in major damages to several satellites. Another, unexpected impact of the high-altitude nuclear tests was the electromagnetic pulse (EMP) that can have devastating effects over a large geographic area (as large as the continental United States). Other anthropogenic impacts on the space environment include chemical release ex- periments, high-frequency wave heating of the ionosphere and the interaction of VLF waves with the radiation belts. This paper reviews the fundamental physical process behind these phenomena and discusses the observations of their impacts.Comment: 71 pages, 35 figure

Remote sensing applications for resource development

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