Indian Ocean and It's Uniqueness
Among the three tropical oceans, the Indian Ocean is unique as its circulation differs from the other two tropical oceans.
The circulation of the the Indian Ocean nurtures the life of a lot of species that live in the ocean and land. But what shapes this circulation, I wonder. Do you wonder too? Let's dive into the details together..... … . . .
“When you're circling the Earth every 90 minutes, what becomes clearest is that it's mostly water; the continents look like they're floating objects.” -- Loren Shriver. NASA astronaut (2008)
The Indian Ocean is the third largest Ocean, and it is unique as compared to the other two tropical oceans (Pacific and Atlantic). Well, this statement seems to convey something special about the Indian Ocean, but it is much much complex in reality. If you don't like complex things, don't worry, here we learn about this statement in a more simple way. But if you love to discuss the complexity then don't hesitate to contact me.
Let's Dig in:
Processes in the atmosphere and ocean is a coupled phenomena and their existence depends on each other. The circulation in the atmosphere or the pattern of wind in the atmosphere is the main driving force for the surface circulation of the ocean. The wind in the equator is easterly (the direction of the wind is referred to as from which side the wind is coming, here it is coming from the east) in the tropical oceans except in the Indian Ocean. The pattern of wind over the equatorial Indian Ocean changes seasonally. Why this is happening over the only Indian Ocean? Well, the answer is very simple. Other oceans are connected to both poles directly but not the Indian Ocean. The Asia continent restricts the northward movement further 30°N. Due to the presence of the huge landmass land-sea temperature difference plays a major role in shaping the wind pattern over the Indian Ocean. Oceans usually need more heat to increase their temperature by 1°C as compared to land. During summer the Indian subcontinent heats up more quickly and intensely as compared to the Indian Ocean, which forms a thermal gradient between land and sea that drives the wind from the Indian Ocean to the subcontinent (winds move from high pressure (less temperature) to low pressure (high temperature)) and vice versa for wintertime. This wind, that flows from the ocean to the Indian subcontinent carries a lot of moisture and causes precipitation. This branch of wind is known as monsoon wind and it is the major wind pattern over the Indian Ocean from June - to September. On the other hand, the wind that flows from land (northeast) to the ocean during October - December is mostly dry and causes rainfall over very few regions.
Wind causes the surface circulation of the ocean right to its direction in the northern hemisphere and left to its direction in the southern hemisphere. This is due to Coriolis's force. In the equator, the direction of wind and ocean current (circulation of ocean mass is often referred to as current) are both is same because of the absence of Coriolis force. This causes the surface circulation of the Indian Ocean to alter seasonally. And due to this, some processes that are permanent in the other two topical oceans either become seasonal or absent in the Indian Ocean. However, some new features are also present here for this seasonality.
What we have learned here
The circulation of the Indian Ocean is quite different compared to the other two tropical oceans. The presence of landmass to the north and a seasonally reversible wind makes the Indian Ocean unique as compared to the other two tropical oceans. Due to the presence of the seasonal reversible wind the circulation over the Indian Ocean also changes its direction seasonally. Ocean and land heating play a major role in the formation of this wind.
