It takes its name from India, of course, and it differs from the Atlantic and Pacific in the fact that, in the Northern Hemisphere, it is landlocked and does not reach Arctic waters, thus lacking a temperate-to-cold zone in this area.
In the West, it meets the Atlantic Ocean at Cape Agulhas, at the southern tip of Africa, and its border runs along the 20 E meridian. In the East the limits of the Indian Ocean are less clear, usually they run from South East Cape, in the southern part of Tasmania, along the 147 E meridian, while in the North the limit is usually set from Cape Londonderry in Australia, crossing the Timor Sea to the southern shores of Java, and then across the Sunda Strait to Sumatra. Another of its boundaries is drawn across the Singapore Strait. In the South, it stretches to the recognized borders of the Southern Ocean basin, which are located at latitude 60 S.
Download Cold Zone Sub Indo
Download File 🔥 https://urloso.com/2yGbKa 🔥
Monsoons are also linked with the El Nio and La Nia phenomena and with the Southern Oscillation pattern of the Pacific Ocean basin. The region is subject to strong tropical cyclones that form over the open ocean and usually occur just before and after the southwest monsoon. The northwestern part of the region has the driest climate, while the equatorial regions are the wettest.
Between December and March, cyclones may occur in the East of Madagascar. Warm ocean currents have a warming effect on air temperature by 2 to 3 C in the western trade-wind zone over that in its eastern portion. Precipitation decreases from north to south.
This region lies in the subtropical and temperate latitudes of the Southern Hemisphere, between 30 and 45 S. In the northern part, winds are light and variable, while they become moderate to strong westerly winds in the south. Moving southwards, air temperature decreases. Rainfall is moderate and uniformly distributed.
The surface layer of the Bay of Bengal, on the other hand, is considerably lower in salinity due to the drainage of fresh water from rivers. High surface salinity is also found in the Southern Hemisphere subtropical zone; while low-salinity areas stretch along 10 S from Indonesia to Madagascar.
The Indian Ocean basin, compared to the Atlantic and Pacific, is smaller, geologically younger and more complex. It first opened about 140 million years ago, but it was not until 36 million years ago that the Indian Ocean had reached its present configuration.
Oceanic ridges are rugged, seismically active mountain chains that form part of the worldwide oceanic ridge system. The ridges are features that show as an inverted Y on the ocean floor. One of the most striking is the aseismic Ninetyeast Ridge, the longest and straightest in the world.
We can also find seamounts, extinct submarine volcanoes, that rise from the bottom of the ocean to heights of at least 1,000 m (3,300 ft). In the Indian Ocean basin, these are especially abundant between Runion and Seychelles.
In the Indian Ocean basin, as the greater part of the water area lies within the tropical and temperate zones, the warmth of the water inhibits the growth of phytoplankton, thus limiting the amount of marine animals it can support.
However, in the tropical zone, we find numerous corals and other organisms capable of building reefs and coral islands that shelter a thriving fauna consisting of sponges, crabs, mollusks, sea urchins, brittle stars, starfish, and small reef fish.
The coasts are usually covered with mangrove thickets, which host a specific animal life. Mangroves are important as they stabilise the land and function as breeding ground and nursery for offshore species.
The Indian Ocean basin is also home to many endangered marine species such as turtles, seals and dugongs (also known as sea cows). Another interesting fact is that, when humpback whales travel from cold to warm water over the winter, more than 7,000 humpback whales migrate to the waters around Madagascar to breed and calve.
The most valuable mineral resource found in the Indian Ocean is, by far, petroleum. The Persian Gulf is the largest oil-producing region in the world. Both the Arabian Sea and the Bay of Bengal also are believed to have large resources of natural gas and petroleum, and their exploration is still under way, as are the northwestern coast of Australia and the southwestern coast of Madagascar.
Another valuable mineral resource consists in manganese nodules, which are found in abundance in the Indian Ocean basin. Despite advanced technologies, however, the mining process is complex and this has hindered their commercial extraction. Other valuable minerals are ilmenite (a mix of iron and titanium oxide), tin, monazite, zircon, and chromite.
Deforestation, cultivation, and guano mining carried out by European colonial exploitation had destructive effects on terrestrial ecosystems: by removing vegetation and scraping the land surface, they caused the degradation of much native flora and fauna.
More recently, man-made threats extended to the oceanic environment. The biggest threat is probably pollution, caused by domestic and industrial waste accumulated in coastal waters. This is most evident around India, which is the most populous country of the area.
El Nio is characterized by unusually warm ocean temperatures in the Equatorial Pacific, as opposed to La Nia, which is characterized by unusually cold ocean temperatures in the Equatorial Pacific. El Nio is an oscillation of the ocean-atmosphere system in the tropical Pacific having important consequences for weather around the globe.
Among these consequences are increased rainfall across the southern tier of the US and in Peru, which has caused destructive flooding, and drought in the West Pacific, sometimes associated with devastating brush fires in Australia. Observations of conditions in the tropical Pacific are considered essential for the prediction of short term (a few months to 1 year) climate variations.
To provide necessary data, NOAA operates a network of buoys which measure temperature, currents and winds in the equatorial band. These buoys daily transmit data which are available to researchers and forecasters around the world in real time.
In normal, non-El Nio conditions (left, top diagram) the trade winds blow to the west along the equator from South America towards Asia in the tropical Pacific Ocean. These winds pile up warm surface water off Asia, so that the sea surface is about 1/2 meter (1 1/2 feet) higher at Indonesia than at Ecuador in South America.
The sea surface temperature is about 8C (14F) warmer off the coast of Asia than in the eastern Pacific, due to an upwelling of cold water from deeper levels in the east Pacific. The cooler water off South America is nutrient-rich, supporting high levels of primary productivity, diverse marine ecosystems, and major fisheries. Clouds and rainfall are found in rising air over the warmest water near Asia, whereas the east Pacific is relatively dry.
In the schematic diagrams to the left, the blue band represents the thermocline, which is the depth of water that is 20C (68F). During a normal year, it slopes up from Asia towards South America as the trade winds pile up warm water off the coast of Asia.
During El Nio (bottom schematic diagram), the trade winds relax in the central and western Pacific leading to a flattening of the thermocline (blue band) due to a depression of the thermocline in the eastern Pacific, and an elevation of the thermocline in the west. The observations at 110W show, for example, that during 1982-1983, the 17-degree isotherm dropped to about 150m depth. This reduced the efficiency of upwelling to cool the surface and cut off the supply of nutrient rich thermocline water to the euphotic zone. The result was a rise in sea surface temperature and a drastic decline in primary productivity, the latter of which adversely affected higher trophic levels of the food chain, including commercial fisheries in this region.
The weakening of easterly tradewinds during El Nio is evident in this figure as well. Rainfall follows the warm water eastward, with associated flooding in Peru and drought in Indonesia and Australia. The eastward displacement of the atmospheric heat source overlaying the warmest water results in large changes in the global atmospheric circulation, which in turn force changes in weather in regions far removed from the tropical Pacific.
Normal conditions: In December 1993 (top figure in column to the right), the sea surface temperatures and the winds were near normal, with warm water in the Western Pacific Ocean (right column of images, red on the top panel of the December 1993 plot), and cool water, called the "cold tongue" in the Eastern Pacific Ocean (right column of images, green on the top panel of the December 1993 plot). The winds in the Western Pacific are very weak (see the arrows pointing in the direction the wind is blowing towards), and the winds in the Eastern Pacific are blowing towards the west (towards Indonesia). The bottom panel of the December 1993 plot shows anomalies, the way the sea surface temperature and wind differs from a normal December. In this plot, the anomalies are very small (yellow/green), indicating a normal December.
El Nio conditions: December 1997 (2nd from top in column to the right) was near the peak of a strong El Nio year. In December 1997, the warm water (right column of images, red in the top panel of the December 1997 plot) has spread from the western Pacific Ocean towards the east (in the direction of South America), the "cold tongue" (right column of images, green color in the top panel of the December 1997 plot) has weakened, and the winds in the western Pacific, usually weak, are blowing strongly towards the east, pushing the warm water eastward. The anomalies show clearly that the water in the center of Pacific Ocean is much warmer (red) than in a normal December. 152ee80cbc
graph theory book free download