El Nino

Here is some excellent information on El Nino. Click on the image below.

I decided to do a quick recap of our discussions about El Nino (actually this includes today and tomorrow). This might help with your notes.

Ocean circulation and how it changes during El Nino. 

• Factors that influence currents: winds, land masses, Coriolis effect
• Normal non-El Nino Pacific currents: strong easterly trade winds, easterly equatorial currents, mounding of warm surface waters in the western Pacific, cold deep water upwelling along South America
• El Nino changes: weak or reversed trade winds, equatorial currents reverse (flow down hill) towards east, central and eastern Pacific warm, western Pacific cools, upwelling ceases.

Relationship between ocean and atmospheric circulation during El Nino:

• Changes in pacific equatorial currents and warming of central and western Pacific affects Walker Cell circulation. Normal Walker Cell circulation collapses and warm moist air raises over the central and eastern Pacific, low pressure moves east.
• Jet streams move south across US
• Changes in these circulations affect the weather around the globe

Weather impacts in Central Florida:

• Changes to jet stream results in fewer hurricanes due to increase wind shear aloft, hurricanes that do form tend to be pushed more towards the north Atlantic.
• Temperatures do not vary significantly, some slight cooling in winter months of about 2-3°
• Increased cloud cover and rainfall, an additional 10 inches (30%). This may have some negative impacts on crops and tourism, however it helps to recharge the aquifers and reduce the number of brush fires
• Increased likelihood of tornadoes

Relationship between ocean circulation, the aquatic food chain and El Nino:

• During non El nino years upwelling occurs along the west coast of south America. This upwelling bring nutrient rich cold bottom waters to the surface where it helps feed small organisms called phytoplankton. Phytoplankton are producers and form the bottom rung of the ocean food chain.
• During El Nino years the upwelling stops which results in significantly less phytoplankton. The reduced levels of phytoplankton means each level higher up on the food chain will have insufficient food.

How El Nino changes might affect the food chain/production in Florida:

• While El Nino has a significant negative affect on the fishing industry along the west coast of South America, it does not have a significant impact on fishing in Florida. El Nino is an event in the Pacific ocean not the Atlantic. However it may affect imports of certain fish and fish products raising prices due to decreased catch
• El Nino does affect our winter crops in Florida with increased rainfall and reduced sun. Increased rain might delay planting or increase diseases. Different varieties may need to be planted or different planting techniques used. El Nino even affects cattle raised in Florida, as pasture area is less productive.