SOUTH-WEST INDIAN OCEAN MONSOON SYSTEM (SWIOMS)

SOUTH-WEST INDIAN OCEAN MONSOON SYSTEM (SWIOMS)

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Mention has been made in Article:  The Weather and Summer Season 2017-2018’:


“The Weather Systems, forming and evolving in the Southern Indian Ocean Basin, have undergone significant changes. The Patterns of previous years do not seem to be consistent. Meteorologists, Forecasters and Scientists are obliged to do their homework competently.”


Furthermore, the Southern Hemisphere of the Indian Ocean appears, no doubt, to develop some particular Dynamism in terms of Cyclones and Rainfalls. The Dynamics of Climate, Weather and Hydrology are crystal clear during the Summer Season 2017-2018.



Climate, Weather and Hydrology in brief


The continents of Australia, Africa and Antarctica constitute the real barometers of Climate and Weather Systems in the Southern Indian Ocean.


Australia, the smallest continent of the Blue Planet, is about 7,692,000 sq km in area. Besides, it is the lowest and the flattest land mass and also as dry as Antarctica. Emissions of Carbon (CO2), Methane (CH4), Nitrous Oxide (N2O) and others which escape mainly from industrial and mining activities contribute to a large extent Global Warming in this region. Deadly natural forest fires, extreme cyclones and floods are very common. Temperature even reached 520Celsius two years ago.


According to the ‘State of Climate Report 2014’ issued by the Australian Bureau of Meteorology:

‘Australia’s mean surface air temperature has warmed by 0.9°C since 1910.

Seven of the ten warmest years on record have occurred since 1998.

Over the past 15 years, the frequency of very warm months has increased five-fold and the frequency of very cool months has declined by around a third, compared to 1951–1980.

Sea-surface temperatures in the Australian region have warmed by 0.9°C since 1900…

There has been an increase in extreme fire weather, and a longer fire season, across large parts of Australia…Atmospheric greenhouse gas concentrations continue to rise and continued emissions will cause further warming over this century’.  



This ‘Kangaroo Land’ located just along the Tropic and Sub-Tropic of Capricorn transfers its Green House Gas (GHG), global and anthropogenic, across the continent and in the directions of Asia and the Indian Ocean. This can be explained by the fact that, with the rotation of the Blue Marble from West to East, all GHG are bound to shift mainly towards the West of the Indian Ocean until they are dumped in continental Africa.


The Warm Pool located in the West of Pacific Ocean is found just in the North of Continental Australia. As this is the ‘bubbling basin’ of the EL NINO Phenomenon Cyclones, Tornadoes, Typhoons, Droughts and Floods ooze out and invade Asia, the Indian Ocean and the rest of the world. The Weather Systems are channelled along the Equator through both the Tropics of Cancer and Capricorn. This track is commonly known as the Inter Tropical Convergence Zone (ITCZ) in the South of which Mauritius is found. The South East Trade Winds also contribute in propelling Heat, Humidity and Rain Clouds towards the West of the Indian Ocean.

                              

Africa, the 2nd largest continent of Mother Earth, is about 30,200,000 km2. It covers both Tropics of Cancer and of Capricorn and also extends until both the Sub-Tropic near the South Pole and until the Mediterranean Sea in the North. Its Climate and Weather Systems are very complex.


Apart from the global impact of the EL NINO, the Madden Julian Oscillation (MJO) appears to have a considerable influence along the periphery of and across the Indian Ocean, on Continental Africa and in the Atlantic Ocean. Heavy Rainfalls and Floods are mostly triggered by this Atmospheric System. The Madden-Julian Oscillation (MJO) isa 30-to-60 day weather pattern… a large, slow-moving area of enhanced thunderstorm activity that moves eastward from the Indian Ocean into the Pacific and can affect rainfall over Africa’, as explained by NASA Scientist following the Deadly Flood in Zimbabwe, Zambia, Tanzania, Malawi and Mozambique in January 2008.


This Weather System operates as from the Sub-Saharan region and shifts Southwards, Eastwards, Northwards and also Westwards. It is this MJO which causes Rainfall Patterns in Africa, Indian Ocean and other regions. Unfortunately, it appears that the Meteorological Services of Mauritius, including those in the region and those of most African countries fail to understand this Phenomenon.

The African Ministerial Conference on Meteorology (AMCOMET) has rightly decided, after the Cape Verde Conference on 10-12 February 2015, to introduce a ‘Strategic Plan for the Establishment of a Regional Climate Centre (RCC) in Central Africa’. It is hoped that this Institution will endeavour to enhance ‘Climate Knowledge’ for the welfare of everyone.


Sub-Saharan Africa top lists all countries in Global Biomass Burning. It should be noted that Africa is also the second most populous Continent. Refer to NASA Image.


Continental Africa is also under the threat of Lightning. The South African Weather Service (SAWS) stated in its Media Article dated 19 March 2015:

‘on Thursday 18 March 2015, six construction workers died and another five were injured when they were struck by lightning in Botshabelo, Free State. The workers took refuge under a shelter when a thunderstorm moved over.

On Wednesday 17 March 2015, a school pupil died after being struck by lightning on a hockey field in Mpumalanga. A thunderstorm moved over the area and the children were instructed to run to the cafeteria for shelter. A boy was struck by lightning on his way to the cafeteria.’                                                                                                                                                                                                       

Desmond Manatsa, a Climate Scientist at Bindura University of Science in Zimbabwe ‘found that the ozone hole would have altered Southern Hemisphere wind patterns. These changes, in turn, would have intensified the Angola Low, a low-pressure system in the atmosphere mostly located over Angola, situated on the west coast of southern Africa. This, in turn, would have led warm air from near the equator to flow into southern Africa.’


The Mozambique Channel situated between Eastern Africa and Western Madagascar, is another ‘Boiling Pot’ which accelerates Atmospheric Global Warming in the African Zone caused by economic and human activities- deforestation, fires, pollution of rivers and coastal areas by agricultural pesticides, etc. Cyclones, Heavy Rainfalls and Floods are ‘cooked’ here. It is worthwhile to note that 40% of Cyclones which evolve in the Southern Indian Ocean take birth here. Madagascar and the neighbours often experience, inevitably, Extreme Weather Conditions almost each Summer Season.


NB: The Weather Patterns of previous years seem to have changed this Summer Season 2017-2018, as mentioned in recent articles of this Website.

Antarctica, the 5th largest continent, is about 14,245,000 km2. Located at the South Pole and at the bottom of Mother Earth, it is the remotest land mass and also the coldest, windiest and driest-0.117mm rain. The Atmosphere is usually very cold, chilly and 98% of its surface is covered with ice reaching 1.9 km in thickness. The Temperature can reach minus 890 Celsius. There is no permanent human settlement, except a few thousands of researchers and scientists who go there for a short time.


The Antarctic Continent is surrounded by three oceans-Indian, Pacific and Atlantic. The Antarctic Circumpolar Current (ACC) propels the ocean waves and atmospheric currents all around from West to East, that is, clockwise. The ACC Transports 150 million cubic meters of water per second which is equivalent to 100 times the flow of all rivers of the world. There are also zones of Anti-Cyclones and of Low Pressure Systems which circulate around the Antarctica, thereby warming it up and acidifying it. The Anti-Cyclones move from West to East in the anti-clockwise mode and cause instability and cold front systems. Eventually, Strong Winds/ Gusts and Ocean High Waves/Surge take place almost in whole of the Tropic of Capricorn.


The main feature of this Southern Wind Current is that it tends to move towards the North during its clockwise movement. As such, it ventilates, like the wings of a fan, the Tropic of Capricorn with its cold air. According to my observations made in the Southern Indian Ocean during 2008-2010, the Antarctic Circumpolar Current (ACC)unlashes its tentacles’ towards the Tropic of Capricorn for a period of 3-5 days. There is also a 3-5 days- time scale between the strong ‘tentacles’. As it is the most vigorous Wind Current of the Blue Marble, it is capable of neutralizing all Weather Systems- Cyclones and Precipitations which evolve along the ITCZ and the MJO especially during the Summer Season. While doing so, there are lots of convection zones and the scenario appears both dangerous and graceful depending on the distance of the Atmospheric Systems and the land masses. From the destructive point of view, the ACC may drag a cyclone pole ward all along the land masses of Madagascar, Reunion, Mauritius and Rodrigues mainly. In the positive scenario, this may occur far from the islands without provoking landfall. Several examples are available during the cyclonic seasons.


The same pattern may occur regarding Cumulus Rain Clouds. The ‘Marine Stratocumulus Clouds’ which tracked towards the South Indian Ocean on 11 March 2013 appears to be an example. It is also presumed that the Extreme Events in Mauritius and Rodrigues, namely the Deadly Flood of 26 March 2008, the Torrential Rain of 13 February 2013, the Deadly Flash Flood of 30 March 2013, the Torrential Rain of 14 March 2014 (ROD) and others, have been influenced by the impact of the ACC and the MJO fusion.



Causes of Sea Swells in Southern Indian Ocean


The land mass of the Antarctic Continent located in the South Pole is calculated to be around 14, 000,000 sq./kms in area, making it the fifth largest continent of the Blue Planet. It was part of the Super Continent of Gondwanaland 170 m years ago.


Besides, it is:

  1. Remotest- reachable nearest as from Argentina;
  2. Coldest: minus 890 Degrees Celsius; 97% is covered with ice sheets ‘a little over 2 kilometers (1.2 miles) thick. If all of this ice melted, it would raise global sea level by about 60 meters’..NASA. 
  3. Driest-10 mm of Rain per year (East Antarctica);
  4. Windiest –about 28 to 45 kph of wind force and
  5. Highest- 2,300 metres from sea level, ‘on average highest continent on Earth’..NASA.

The Antarctic Circumpolar Current (ACC) is the strongest flow of water and air of the Blue Marble. It moves from the West towards the East, in a clock-wise mode, all-round the Antarctic Continent.  The ‘modus operandi’ of the ACC or the ‘West Wind Drift’ is complex, but can be easily understood. This Ocean Current is capable of transporting an estimated 150 million cubic metres of water per second (some years ago the figure was 130m cu mt). The energy so generated is calculated to be more than 100 times all the world rivers combined together. (There are lots of researches and reports which continue to be carried out by various international teams.)


The ACC generates, simultaneously, both the Ocean and Atmospheric Currents. It can be explained by the rotation, on the axis, of Mother Earth from West to East and to the effect of the Coriolis Force. The Wind Current tends to penetrate almost the whole of the Tropic of Capricorn while meeting Southern Indian Ocean. As observed, it moves Northwards during a lapse of 3-5 days and retreats Southwards at the same pace. During its interaction, it is capable of interfering and of, thereby, neutralizing the South-East Trade Wind (SETW), the Inter-Tropical Convergence Zone (ITCZ), the Madden-Julian Oscillation (MJO) and the ‘Malgache Wind’ which has faded out since a few decades.


As such the ACC, is so robust that all Depressions, Cyclones and Flood Storms are pulled down towards the cold waters of the Sub-Tropic and the South Pole. This process is mostly seen to cause Weather Instability, Convection, Troughs and Fronts (Cold or Warm) in the Atmosphere and Sea Swells along its track.


https://en.wikipedia.org/wiki/Coriolis_force#/media/File:Corioliskraftanimation.gif


http://oceanservice.noaa.gov/education/kits/currents/05currents1.html

The ACC is the only Current which meets three Oceans-Indian, Atlantic and Pacific which are mostly warm and acidic. This System carries many pockets of Low Pressure Systems, following the impacts of Global Warming. Moreover, the depletion of the Ozone accelerates heat and subsequent ice melting.

 

The ACC generates Anti-Cyclones which blow counter-clock-wise and move from the West to the East. As the ACC brings cold air and cold water, it ventilates the three Oceans. The Anti-cyclones act as the ‘wings of a fan’, thereby generating cold wind whose gusts may reach 90 kph and cold water whose energy may cause upwelling and High Waves up to 5 metres in height or more.

 

It is worthwhile to say that when the Ocean and Atmospheric Currents prevail, the sea is churned so much so that the navigation of aeroplanes and ships become risky. There is also interaction with the surface ocean current like South Equatorial Current which surfs to the East or the West according to the seasons.

 

See picture and animation: 

http://oceanservice.noaa.gov/education/kits/currents/05currents1.html

 

and also of the deep sea currents. Refer to picture here:

http://oceanservice.noaa.gov/education/kits/currents/06conveyor2.html

 

Keep Watch for Updates.

 

PKANHYE.14.14 hrs MONDAY 27 JANUARY 2020.

Satellite Animation