Oceanic circulation- NADW

EL NINO AND LA NINA In normal, non-El Niño conditions (top panel of schematic diagram), the trade winds blow towards the west across the tropical Pacific. These winds pile up warm surface water in the west Pacific, so that the sea surface is about 1/2 meter higher at Indonesia than at Ecuador. The sea surface temperature is about 8 degrees C higher in the west, with cool temperatures off South America, due to an upwelling of cold water from deeper levels. This cold water is nutrient-rich, supporting high levels of primary productivity, diverse marine ecosystems, and major fisheries. Rainfall is found in rising air over the warmest water, and the east Pacific is relatively dry.

During El Niño, the trade winds relax in the central and western Pacific leading to a depression of the thermocline in the eastern Pacific, and an elevation of the thermocline in the west. This reduces the efficiency of upwelling to cool the surface and cut off the supply of nutrient rich thermocline water to the euphotic zone. The result is a rise in sea surface temperature and a drastic decline in primary productivity. Rainfall follows the warm water eastward, with associated flooding in Peru and drought in Indonesia and Australia. The eastward displacement of the atmospheric heat source overlaying the warmest water results in large changes in the global atmospheric circulation, which in turn force changes in weather in regions far removed from the tropical Pacific. (Europe)

http://www. cpc. ncep. noaa http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ensoyears.shtml http://www.pmel.noaa.gov/tao/elnino/nino-home.html

Explain how each of altitude and oceanic circulation influence climate. (10 marks) Level 1 (1-4 marks)(Midpoint 3) Simple statements of influence of altitude and oceanic circulation on climate. No specific detail or elaboration is provided; or discussion of one aspect only. Level 2 (5-8 marks) (Midpoint 6) Both elements covered with specific or detailed statements of influence of altitude or oceanic circulation on climate; may be still an imbalance of influence. Level 3 (9-10 marks) (Midpoint 9) A fully developed answer, with good elaboration and explanation of a range of influences, with both elements reaching a Level 2 response. The answer demonstrates both breadth and depth of understanding There have been no other short mark questions on this section of the specification apart from the ones in this PowerPoint so will next year be the lucky year…

To what extent is oceanic circulation the main driving force behind the Earth’s climate -40 marks What are the key points? What needs to be in your introduction? What else do you need to cover? ‘to what extent’ so…? What will your conclusion be?