EL NIÑO, LA NIÑA AND MLD .pptx

This document discusses the ENSO (El Niño-Southern Oscillation) phenomenon, including El Niño and La Niña, their effects, and methods for detecting ENSO. It also briefly covers Mixed Layer Depth (MLD), its importance, and detection methods.

1. EL NIÑO, LA NIÑA AND MLD

2. INTRODUCTION Tropical pacific ocean Caused by abnormalities in the pattern of SST, ocean current & pressure system El ni ño – little boy, christ child Southern Oscillation - discovered by, Sir Gilbert Walker East- west balancing movement of air masses between the Pacific and Indo- Australian areas. ENSO – El ni ño Southern Oscillation By, Jocob Bjerknes La ni ñ a – the little girl It occur every 2- 7 years and can last up to 18 months ( el niño episods ) This Photo by Unknown Author is licensed under CC BY-SA

3. ENSO- el niño Southern Oscillation It is a recurring climate pattern involving changes in the temperature of water in the central and eastern tropical pacific ocean. The oscillating warming and cooling – ENSO cycle 3 phases –-- El niño (warm phase) Neutral phase La niña (cool phase) E l niño & La niña – ocean part Southern oscillation – atmospheric changes

4. In normal condition Source : Scijinks

5. During el niño High pressure Low pressure

6. El Niño causes the Pacific jet stream to move south and spread further east. During winter, this leads to wetter conditions than usual in the Southern U.S. and warmer and drier conditions in the North.

7. Effect of el niño Western side of south America- wetter than normal conditions & floods Other parts- drier conditions, drought & forest fire Reduction in Peru current Reduced upwelling near the negative impact on fisheries cost of south America flash floods Intense hurricanes Rise in sea surface temperature Weakens the trade winds Gaint waves Coral bleaching Influence crop season Disrupting agricultural activities Damaging crops

8. Food insecurity, flooding, rains & temperature rise cause health problems: Malnutrition, Heat stress

9. During la niña High pressure Low pressure

10. La Niña causes the jet stream to move northward and to weaken over the eastern Pacific. During La Niña winters, the South sees warmer and drier conditions than usual. The North and Canada tend to be wetter and colder.

11. Effect of la niña Causes increased rainfall in some world regions and drought in others Increase in Atlantic hurricane activity Beneficial to Indian economy, which depends on the monsoon for agriculture and industry Cause catastrophic floods in northern Australia Have positive impact on fishing industry of western south America

12. Detection of ENSO Buoys Consist of approximately 70 moored ocean buoys in tropical Pacific ocean array consists of NOAA TAO moorings in the eastern and central Pacific and Japanese TRITON moorings in the western Pacific TAO- Tropical Atmosphere Ocean array(managed by NOAA- National Oceanic Atmospheric Administration). TRITON- Triangle Trans- Ocean buoy Network (managed by JAMSTEC- Japan Agency for Marine Earth Science and Technology) Measure SST, air temp., currents, winds, humidity, etc

13. Oceanic niño Index (ONI) A standard used by NOAA. defined as the 3-month average SST departures in the niño -3.4 region Used to measure deviations from normal sea surface temperature

14. Southern Oscillation Index (SOI) Help to understand the development and intensity of el niño / la niña events Calculated using the pressure difference between Tahiti and Darwin.

15. Sea WiFs Sea- viewing Wide Field of view Sensors Launched by NASA Designed to detect ocean colour (indicator of microscopic plant life in ocean) Growth of such plants is affected by change in SST that are related to el niño & la niña

16. MIXED LAYER DEPTH (MLD) Widely used parameter for physical, chemical & biological oceanography. MLD is the thickness of ocean where air , ocean interference occur, it interface with the sun. Adequately mixed by wind, ocean current and waves Region which directly influenced by the atmosphere. Where the ocean capture heat & help in the regulation of heat  mixed-layer is the layer between the ocean surface and a depth usually ranging between 10- 200m Characterized by uniform temperature, salinity and density

17. Below mixed layer, water temperature rapidly decreases with depth Depth and temp of MLD varies from day to day and season to season.

18. Importance of MLD Affecting the ocean and climate Regulate the quality of sun penetrating deeper parts of sea water Affect biological productivity in the ocean Affect primary production and the timing of spring phytoplankton bloom Determine the average light intensity experienced by phytoplankton

19. Detection of MLD CTD- mechanical instrument used to measure conductivity, temperature, and depth Calculated from Sea Surface Temperature Density threshold method Fixed density criterion

20. THANK YOU This Photo by Unknown Author is licensed under CC BY-SA-NC