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17 Water Mass Characteristics of Indian Ocean

by Ayu Mesdya

Each ocean has its own characteristics, as in the previous discussion of unique characters in of the Pacific Ocean. In this post, we will discuss 17 water mass characteristics of Indian Ocean. Below is the discussion on 17 water mass characteristics of Indian Ocean.

1. The Water Masses form

The water mass is formed at sea level and submerged in a way dependent on its density. This applies to all water masses except water on the equator, the Indian and Pacific oceans. The process of mixing beneath the surface is what distinguishes the mass of water in the Indian Ocean with other oceans. According to some researchers found that there is a vertical structure that matches the typical zonal currents in the Pacific Ocean below the westward current. It is associated with an east wind anomaly along the Indian Ocean.

2. Geographical Position

One of the characteristics of water masses of Indian ocean is the geographical position. The Indian Ocean is the body of salt water between Africa, Asia, Australia, and America. It stretches for more than 10.000 km between the southern tips of Africa and Australia. Its marginal seas have an area about 73.440.000 square km. Some people said that the origin and evolution of Indian Ocean are the most complicated. Its formation began about 180 million years ago start from Gondawa until the movement of Africa and separation of Australia from Antartica which 53 million years ago.

3. Climate Conditions

The Indian Ocean has unusual climate variability in all its territories. Climate variations are caused by monsoons commonly known as Indian Ocean Dipole (IOD). IOD is divided into three events, namely positive, negative, and neutral. At a positive IOD, the temperature in the western region is warm while in the east it is cold. Secondly, the negative IOD is if the western region is in normal temperature while in the east the temperature is cold. Last IOD is neutral, the western temperature feels cool while on the east it feels warm.

IOD is the existence of two modes of oceanic atmosphere between easterlies and westerlies scales. IOD plays an important role to help make predictions about seasonal and inter-ethnic climate variations between the western and eastern regions of the Indian Ocean.

4. Temperature and Salinity

Several studies have shown that water masses can be identified by the relation of properties to temperature and salinity. The Indian Ocean is the temperature and climatology of the most widely used ocean salinity in the world. World Ocean Atlas (WOA) includes all available hydrographic data as well as temperature and salinity data for the Indian Ocean. The researchers say that the mass of water can be seen with plot data as coordinates as well. The T-S diagram is a salinity temperature diagram.

This diagram is used to study water masses. This diagram only interacts with the atmosphere and the water mixture. When the water is well mixed, the mass of water can be represented by a single point and is called the “water type”. Here we will see that the line is generally straight. If water is mixed with other water mass there will be a line above or below it. The TS curve line will be modified by itself.

5. Asymmetric Shape

The Indian Ocean has an asymmetrical shape mainly due to the Asian continent. Asymmetric configurations lead to poor dissemination of circulation and renewal of water in the Indian Ocean depths, especially in the North. This weak water distribution affects the mass of water in the Indian Ocean. The studies said that the circulation of the Indian ocean is similar to that occurring in the estuary. The heavy water on the bottom spreads to the head of the bay, and a light water in the upper layer. There is only a part of the Indian Ocean lies in the northern hemisphere.The meridional circulation is initiated by the water masses of the Red Sea and the Persian Gulf.

6. Current Pattern

We remember that the Indian oceans have currents and these are called monsoons. Indian currents and monsoons also affect the Indian Ocean water mass. The behavior of North India is currently different from other oceans. The currents in the northern Indian Ocean change direction from season to season in response to monsoonal rhythms.

The winter circulation, north and south equatorial current start from the south of the Indonesian archipelago, and it moves from east to west. The north-eastern monsoon moves water along the coast of the Bay of Bengal in a counterclockwise direction. Water also lies along the coast of the Arabian Sea circulating in anti-clock circulation. In addition, in summer the water circulation in the north of the sea this season clockwise. Because, in the absence of equatorial currents, strong currents flow from west to east.

7. Equatorial water mass

The Indian Equatorial water mass is also called as North Indian high salinity intermediate water. It forms by Australian water and Indian central water. This water spreads between 2,000 and 3,300 feet. It also spreads west into the Bay of Bengal and as far south as Madagascar and Sumatera. Equatorial water mass is found on the south side of the equator of the Pacific Ocean and the Indian Ocean. The salinity value is very high compared to the number of water masses found in the northern part of the Indian Ocean. The reason may be that mixing with the waters of the Red Sea makes its salinity value high.

8. Indian Central water

The Indian Central Water mass is referred as the subtropical maximum salinity. It’s found in the upper layers of the South Indian Ocean between 40 Degrees South and 10 degrees South. It’s formed by sinking near the subtropical convergence.This water mass is a straight line with temperatures 8-10 degrees Celcius and salinity 34.6-35.5. These T-S characteristics are similar to those of the South Atlantic Central Water mass.

The Indian Central Water mass towards north beyond 10 degrees South, it’s halted by the hydrological front. This water mass is not extended towards south from the region of its formation. This Central mass actually can be found in the entire south tropical region and it has a temperature range from 15 to 23 degrees Celcius.

9. Antartic Intermediate Water Mass

The Antartic Intermediate water mass is present below the central water mass and above the deep water mass in the south Indian Ocean. This mass has cold low salinity which is pressed by the prevailing west winds and meets the warmer waters of higher salinity in the Antartic Polar front. This low salinity layer has a thickness of 500 meters or more. The temperature-salinity values of the Antartic Intermediate Water are increased from 4 degrees Celcius and 34.3 at 40 degrees S to 7 degrees Celcius and 34.7 near 10 degrees S.

The characteristic of Antartic Intermediate water is the minimum salinity core and it’s present in the entire area. It lies in the Sub-Antartic region and then sinks rapidly northwards to 900-1300 meters north of the convergence.

10. The South Indian Deep Water Mass

The South Indian deep water mass is found between 1500 and 4000 m depths in the South Indian ocean. This deep water originates mainly from the North Atlantic Deepwater. It comes as well from the Antartic Circumpolar water and from the North-west Indian deep water. These three of water masses bring the deep water into the South Indian. This deep water has a minimum of an oxygen but the value of salinity is maximum.

11. The South-West Indian Deep Water Mass

The South-west Indian ocean consists of the North Indian Deep Water and the Atlantic Deep Water. Some studies said that water mass characteristics in the South-west Indian ocean are associated with the Deepwater under the Agulhas current.It would be composed of the North Atlantic Deep Water mixed with the North Indian Deep Water. This deep water mass in the South-west Indian ocean also has low oxygen values.

12. Antartic Bottom Water Mass

The Antartic bottom water mass is found in the bottom layer below 400 meters in the Indian Ocean. This bottom water characterized by very low temperatures and it’s clearly of Antartic origin. The Antartic bottom water mass in the Indian Ocean are similar which has a low temperature and salinity. This bottom water enters the Indian ocean from south-west and south-east.

13. The Persian Gulf Salinity

The Persian Gulf is the arm of Arabian Sea, it’s bordered by Oman and the United Arab Emirates to the south, to the west by Qatar and Saudi Arabia, the north by Kuwait and Iraq and finally, it’s along the entire east coast by Iran. The Persian Gulf water mass is characterized by high salinity. It is found around the equator from 55-90 degrees East and the average depth of about 200 meters. This water mass is one of the North Indian Ocean.

14. The Red Sea Water Mass

The Red Sea lies between Africa and Asia. It has an area roughly 2250 km long and it has a maximum depth of 9.970 ft. This sea is one of the saltiest bodies of water in the world. The average of its salinity is 40 %. The Red Sea also has high salinity like the Persian Gulf as well. The Red Sea water mass enters the Arabian Sea, and it spreads towards the south. The Red Sea water mass along its southern limit of distribution in the central and eastern parts of the Indian Ocean. This mass is found as deep as 800-900 meters.

15. The Arabian Sea Water Mass

The Arabian sea water mass is affected by the monsoons. The effect of the monsoon is dominated on the surface layers. This water mass forms at the surface of the North Arabian Sea. It has high salinity and density with the value between 24 and 25. In the north-east monsoon seasons, the cold winds blowing from the northern Arabian Sea. The north-east monsoon and high salinity together lead to the formation of the water. It makes a lower salinity in the north-west corner of the Arabian Sea.

16. The North Indian Deep Water Mass

This North Indian deep water mass is present at depths of about 1500-3500 meters in the Arabian Sea. This deep water mass is characterized by relatively high values of salinity, dissolved silica concentration and the low values of dissolved oxygen. This deep water is known to enter the Arabian Sea at depths more than 3800 meters. It flows northward towards the equator along the western boundary of the Somali Basin. Some waters also move over to the bottom water of the Arabian Sea also. All the water must rise upward and it is transformed into North Indian deep water mass.

17. The Bay of Bengal Water Mass

The bay of Bengal can be found in the north-eastern corner of the Indian ocean. It’s enclosed on the northern, western, and eastern sides. The northern Indian ocean wind and the Himalaya mountains cause the highest rainfall. It drains into the Bay of Bengal. The water mass characteristics in the bay of Bengal is divided into the North Dilute water mass and the Southern Bay of Bengal.

The North Dilute water mass is formed during October and November. It is largely different in salinity between the areas to the north and the south bay. All of the fresh water from all the rivers, the salinity of the Bay in Bengal is low. Besides the Southern Bay of Bengal water have the salinity range between 33.0 and 34.0. This water mass is found entering the southeastern Bay and the western and middle parts of the Central Bay.

Hopefully, above the discussion 17 water mass characteristics of Indian Ocean may help you in the study as well. Above the discussion is really facts based on the researchers. You can also read the other post below as following as well.

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