 |
| El Niño is a climatic phenomenon that leads to changes in the temperature of water in the eastern Pacific ocean.It usually leads to drier monsoons in countries like India and Australia. But the effect has less significance as there was normal or excess rainfall in half of the time when El Niño effect took place. (Picture from: http://nishurs.blogspot.com/) |
Western Pacific Ocean has the most unique characteristics compared with other places in the world. These waters are so complex and complicated both from the terminology of biology and dynamics oseanografinya. There are still many puzzles unsolved and became a very warm discussion by experts on marine and fisheries.
The region is often referred to as warm waterpool (WWP) is well known since the birth of El Nino reveal that the embryo was derived from here. To the public, El Nino is always associated with a prolonged drought that effect not only on issues of human basic needs of water, but extends to other sectors such as agriculture-related crop failure, livestock, plantations, forest fires, health, and transportation. El Nino is seen as an effect of climate change impacts not only on a regional scale, but also the global climate.
Covering the area bounded and surrounded by an imaginary line is crossed by the South Equatorial Current (Southern Equatorial Current) and the North Equatorial Current (Northern Equatorial Current) and Low-Latitude Western Boundary Current (L-WBC) in the west. Having the character of warm sea surface temperatures with an annual average of 28°C, sea surface temperature can reach over 29°C make this area as the warmest waters in the world, especially when the ongoing La Nina event.
Salinity in the surface layer is more fresh (32-33 psu) compared to surrounding waters (35-36 psu) due to high precipitation compared to evaporation. Mass of warm water with a character and more fresh water is a characteristic mass that accumulates in the tropical western Pacific as a piping by blowing trade wind. The result is the formation of the barrier layer which acts as an insulator, inhibiting the increase in mass of the water is colder and more salty than the layer beneath it (up Welling).
Barrier layer stratification is typical of tropical waters by the oseanographer defined as the vertical distance between the lower limit mixed layer (mixed layer) is characterized by a nearly uniform density boundary layer above the thermocline, a layer where the vertical temperature gradient is very sharp. The role of barrier layer can be likened to insulate the walls of the flow of heat (heat) from the layer above it, also increased the mass of cold water rich in nutrients from the layer underneath. Therefore, it is understood, the region is the sea with low primary productivity or in other words a place that no potential for fisheries.
What are the main attraction of ocean pelagic fish such as skipjack (Katsuwonus pelamis), yellow fin tuna (Thunnus albacores), as well as large eye tuna (Thunnusobesus) come in and get comfortable place for their survival in the "desert" that is "hot" and arid this?
The key, there is the presence of barrier layer. One consequence of stratification is the retention layer barrier penetration of wind energy generation westerlies or known as the Westerly wind bursts (WWBs) to the bottom layer. Wasterly wind bursts are the distinctive character of the wind in the western Pacific associated with the variation of intraseasonal (30-90 day period) waves of the ocean atmosphere between the Madden Julian Oscillation (MJO), which comes from the Indian Ocean. During the phase of El Nino, this WWBs intensified, increasing the momentum WWBs trapped in the surface layer, resulting in the maximum mass flow of water to the east along the equatorial western Pacific to the middle. Along with that, also participated in warm pool shifts eastward towards the Central Pacific to include a barrier layer beneath the layer.
Absence barrier layer in the waters of the western Pacific wind allows the voltage rise WWBs able to stir the deeper water masses in the mixed layer column. Meanwhile in the layer below it, the mass of cold water and saltier and nutrient-rich circulation are also more easily hold on the layer above it. The change process is then induces an increase in the productivity of phytoplankton which is the foundation stone of the marine food chain cycle.
Blooming of phytoplankton (associated with a high abundance of tuna) often occur in these waters, it can even reach as far as length of 4.000 kilometers, as well as the 1997-1998 El Nino event in which bands formed from plankton to the east of the Philippines Mindanao to 160°-180 ° East Longitude. By experts remote sensing much describes as "The Ribbon Dark". However, this condition is situational and highly dependent on the intensity of El Nino at the time (index of El Nino).
Meanwhile, in the waters along the northern coast of Papua, where El Nino embryo is formed, there was an increase in primary productivity to a remarkable spread far to the east. During this phase khlorofil concentration at the surface can be increased three times compared with normal conditions, produce the number of meals of tuna and tuna exceptional recruitment in the western equatorial Pacific.
Is anchovy (Encrasicholina punctifer), skipjack tuna species feed key and YFT in the Western Pacific waters are very warm temperature waters. The population of this species tends to overflow after a lag time of about 3-4 weeks after blooming of phytoplankton, especially the phase during El Nino events.
What happens at sea is very contradictory with the situation on the ground. When droughts hit in most parts of Indonesia, the conditions at sea on the contrary, the productivity of the waters in this region abundant incredible ....! During the years 1995-2002, approximately 520,000 tons per year can be harvested YFT in the Pacific region. *** [GENTIO HARSONO | PIKIRAN RAKYAT 15092011]
The region is often referred to as warm waterpool (WWP) is well known since the birth of El Nino reveal that the embryo was derived from here. To the public, El Nino is always associated with a prolonged drought that effect not only on issues of human basic needs of water, but extends to other sectors such as agriculture-related crop failure, livestock, plantations, forest fires, health, and transportation. El Nino is seen as an effect of climate change impacts not only on a regional scale, but also the global climate.
Covering the area bounded and surrounded by an imaginary line is crossed by the South Equatorial Current (Southern Equatorial Current) and the North Equatorial Current (Northern Equatorial Current) and Low-Latitude Western Boundary Current (L-WBC) in the west. Having the character of warm sea surface temperatures with an annual average of 28°C, sea surface temperature can reach over 29°C make this area as the warmest waters in the world, especially when the ongoing La Nina event.
Salinity in the surface layer is more fresh (32-33 psu) compared to surrounding waters (35-36 psu) due to high precipitation compared to evaporation. Mass of warm water with a character and more fresh water is a characteristic mass that accumulates in the tropical western Pacific as a piping by blowing trade wind. The result is the formation of the barrier layer which acts as an insulator, inhibiting the increase in mass of the water is colder and more salty than the layer beneath it (up Welling).
 |
| Satellite images capture the signal of phytoplankton blooming "The Ribbon Dark" on a data tape SeaWIFS when El Nino 1998. (Picture from: PIKIRAN RAKYAT 15092011) |
What are the main attraction of ocean pelagic fish such as skipjack (Katsuwonus pelamis), yellow fin tuna (Thunnus albacores), as well as large eye tuna (Thunnusobesus) come in and get comfortable place for their survival in the "desert" that is "hot" and arid this?
The key, there is the presence of barrier layer. One consequence of stratification is the retention layer barrier penetration of wind energy generation westerlies or known as the Westerly wind bursts (WWBs) to the bottom layer. Wasterly wind bursts are the distinctive character of the wind in the western Pacific associated with the variation of intraseasonal (30-90 day period) waves of the ocean atmosphere between the Madden Julian Oscillation (MJO), which comes from the Indian Ocean. During the phase of El Nino, this WWBs intensified, increasing the momentum WWBs trapped in the surface layer, resulting in the maximum mass flow of water to the east along the equatorial western Pacific to the middle. Along with that, also participated in warm pool shifts eastward towards the Central Pacific to include a barrier layer beneath the layer.
Absence barrier layer in the waters of the western Pacific wind allows the voltage rise WWBs able to stir the deeper water masses in the mixed layer column. Meanwhile in the layer below it, the mass of cold water and saltier and nutrient-rich circulation are also more easily hold on the layer above it. The change process is then induces an increase in the productivity of phytoplankton which is the foundation stone of the marine food chain cycle.
Blooming of phytoplankton (associated with a high abundance of tuna) often occur in these waters, it can even reach as far as length of 4.000 kilometers, as well as the 1997-1998 El Nino event in which bands formed from plankton to the east of the Philippines Mindanao to 160°-180 ° East Longitude. By experts remote sensing much describes as "The Ribbon Dark". However, this condition is situational and highly dependent on the intensity of El Nino at the time (index of El Nino).
Meanwhile, in the waters along the northern coast of Papua, where El Nino embryo is formed, there was an increase in primary productivity to a remarkable spread far to the east. During this phase khlorofil concentration at the surface can be increased three times compared with normal conditions, produce the number of meals of tuna and tuna exceptional recruitment in the western equatorial Pacific.
 |
Evolution of El Nino embryo in the North PNG from Sea Surface Temperature data. (Picture from: PIKIRAN RAKYAT 15092011)
|
What happens at sea is very contradictory with the situation on the ground. When droughts hit in most parts of Indonesia, the conditions at sea on the contrary, the productivity of the waters in this region abundant incredible ....! During the years 1995-2002, approximately 520,000 tons per year can be harvested YFT in the Pacific region. *** [GENTIO HARSONO | PIKIRAN RAKYAT 15092011]
No comments:
Post a Comment