Understanding El Niño and La Niña: Impacts and Ocean Analysis

GEOL 1330 N ame: Global Warming Lab #5 1. (15 points) Explore the website https://www.pmel.noaa.gov/elnino/ to answer the following questions about El Niño/La Niña: What changes from “normal” conditions in the tropical Pacific Ocean (in terms of winds and distribution of ocean temperatures) occur during El Niño years? From El N ino, some changes have occurred in the change in direction of trade winds that usually blow east to west (usually along the equator) and have weakened or even changed direction. This change is caused by warmer-than-average sea surface temperatures. There is also a cell of air that has grown much stronger which can cause the wind to move from north to south rather than east to west How is La Niña characterized? La N ina is usually characterized by cooler than average temperatures based in the eastern Pacific, so the opposite of El N ino. So during this, even the central and eastern Pacific are usually cooler than the western Pacific. Describe the impacts of El Niño on climate and weather for both the western Pacific (such as Indonesia and Australia) and the eastern Pacific (such as Peru and Ecuador). What impacts can El Niño have on the west coast of the U.S.? El N ino is usually followed by with droughts and wildfire risk centers around Australia and India along with generally warmer and drier conditions \. While in Peru and Ecuador, it is 1

very much the opposite with an overall increase in rainfall and possible flooding. I N terms of the U.S. coast the El N ino event brings in more rain and possible flooding due to the increase in temperature causing more evaporation in general. There is also a possibility for a warmer winter due once again to the rise in temperature. 2

2. (20 points) In the space below make a sketch of a cross section of the ocean from the surface to 500 m depth extending from the western Pacific (coast of Australia) to the eastern Pacific (coast of South America) during a “normal” year and an El Niño year. Draw arrows (and label them) to illustrate (1) the direction of the prevailing winds, (2) the direction of movement of the surface water that would create upwelling off the coast of Peru, (3) the relative thickness of the well-mixed surface water layer across the basin, and (4) the slope/ shape of the thermocline. “Normal” conditions El Niño conditions 3 ------ I A · i - 3 ~ 3 5 * S ↑ 1 1 - - - - ⑭ --- B - - - 1 - - = ! nee nee = S - 1

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3. (15 points) The TAO/TRITON buoys are used to survey conditions in the equatorial Pacific Ocean. Open the following website: https://www.pmel.noaa.gov/gtmba/pmel-theme/pacific- ocean-tao . Explore the website to find out what range of latitudes and longitudes is covered by the TAO mooring array. Latitudes: Longitudes: Click Moorings under the Technical Information heading. Scroll down on the moorings page. What is the range of depths where temperature measurements are made on each mooring in the Pacific? 4. Study the plots below, generated at https://www.pmel.noaa.gov/tao/drupal/disdel/ , and answer the following questions. a) (10 points) The upper panel of this figure (entitled “Means”) shows a map view of the tropical Pacific Ocean mean surface temperatures for a recent 5-day period across the array, whereas the lower panel displays temperature anomalies. Were there any temperature anomalies at the sea surface across the Pacific? Consider any anomaly of + or – 1 degree Celsius to be a potentially 4 8 degrees north to 8 degrees south 8 degrees north to 8 degrees south The range of depths are shallow (1000-2000m), deep (2000-4000m), and very deep (4000,6000m)

significant anomaly. If so, where are the anomalies approximately located? b) (10 points) The upper panel of this figure shows a cross-section view of average temperatures at each mooring depth across the array on the equator for recent 5 days (averaged between 2° N and 2° S). Briefly summarize what the data shown in the upper panel indicate about current conditions across the Pacific: Where is the warm surface layer of water at its thickest and thinnest, how does the position and thickness of the thermocline change across the basin? Are there currently any significant (>+/- 1°C) temperature anomalies (lower panel) below the ocean surface in the tropical Pacific Ocean? If so, describe where (give approximate range of 5 Looking at the map you do notice anomalies ; there is the large red area stretching across the western pacific mainly Philippines to Japan which show waters that are 1-3 degrees warmer than average. Another anomaly is near the center pacific which is 1-3 degrees warmer the eastern pacific was 1-3 degrees colder The panel shows a view of average temperatures of each morning recording. Overall they show how there us an warmer surface level in the western pacific and colder surface lever in the eastern pacific. With that being said it can be implied that the thickets warmest layers would be in the western pacific and the thinnest in the eastern. What is shown in the thermocline is that it is shallower and more vertical in the pacific which backs up that the western pacific is getting that warmer layer while the eastern is staying cool.

latitude/longitude and depths): c) (10 points) We will now explore the 1997 El Niño event, which was particularly large. The upper panels show sea surface temperatures (SSTs) and wind conditions for January 1997, the lower panels for September 1997. Describe changes in the SSTs and winds that occurred between January and September 1997. 6 There does seem to be significant anomalies in the 10n and 10s latitude showing an 1-3 degree change that is higher than normal In January the recording were pretty much normal but by September they seemed to have had a drastic increase. This was probably cause why the change of direction in the trade winds we mention earlier. Strong winds shifted during the even which weakened some wind direction and even reversed them in som areas. These wind changes cause global weather changes like increase rain, droughts and flooding. Overall the change was cause by the warming of temperatures due to the weakening and reversing of trade winds.

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d) (20 points) Now we will examine how the tropical Pacific has varied over the past 35 years. View this plot carefully and think about what it is showing. Over this time period, how many individual El Niño events can you identify and what years did they occur in? How many La Niña events can you identify and what years did they occur in? (Hint: Remember to refer to the “Anomalies” to get a sense of the deviation from normal conditions. Assume that anomalies of greater than ~+/- 1° C are significant). El Niño events (years): La Niña events (years): Put an asterisk (*) next to the year of the strongest El Niño and La Niña events. 7 Years include 1982-1983, 1986-1987, 1991-1992 and 2015-2016 Years include 1988-1989, 1998-1999 and 2007-2008 A * * *

5. EXTRA CREDIT (10 points) Visit the website https://www.ncdc.noaa.gov/teleconnections/ pdo/ to explore the Pacific Decadal Oscillation (PDO). What does the PDO have in common with ENSO, and what are the differences between the two? What is the current status of the PDO? 6. EXTRA CREDIT (10 points) Now visit the website https://www.ncdc.noaa.gov/ teleconnections/nao/ to explore the North Atlantic Oscillation (NAO). How is the NAO index defined (what does positive vs. negative mean)? What are the associated temperature anomalies in the eastern US? What is the current status of the NAO? 8 One thing they have in common is that’s they can both affect weather patterns globally which mentas temperature, whether and atmospheric behaviors. A major difference is that PDO just covers more area in general when comparing the two It seems to be currently negative The N AO is defined as the difference in atmospheric pressures of two locations. When it comes to positive it means strong pressure in difference so negative means a weakened pressure difference. Currently negative with some positive anomalies

Teamwork in the lab is encouraged. However, each student must provide his/her own answer. Copying of answers results in a grade of zero for all students involved. 9

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Lab 5 GEOL 1330 final

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