week 9

• What are the two types of storms mentioned?

  Frontal storms and convective storms
• What is the energy source for frontal storms?

  Gradient in temperature
• What is the energy source for convective storms?

  Release of latent heat
• How do mid-latitude frontal cyclones travel?

  They travel with the westerlies
• What happens when cold air advances faster than warm air?

  It creates an occluded front
• What type of air is needed for thunderstorms?

  Warm, moist air
• What characterizes an air mass thunderstorm?

  Unequal heating of the surface
• What is a severe thunderstorm characterized by?

  Unequal heating or lift + shear
• What drives hurricanes?

  The ocean's heat
• What is the recipe for a hurricane?

  Thunderstorm + converging air + ocean heat
• How long can hurricanes last?

  A few days to a month
• What are the main parts of this week's lecture structure?

  • Part I: Monsoons
  • Tropical climates
  • Monsoon systems
  • Asian monsoon case study
  • Part II: El Niño Southern Oscillation (ENSO)
  • Definition
  • Historical observations
  • Processes
  • Monitoring and predicting
  • Today's situation
  • Key concepts
• What does ENSO stand for?

  El Niño – Southern Oscillation
• What characterizes the ENSO warm phase (El Niño)?

  Warmer than usual water in the equatorial South Pacific

  
• What happens during the ENSO cool phase (La Niña)?

  Cooler than normal water across the equatorial South Pacific

  
• Who identified the Southern Oscillation phenomenon?

  Sir Gilbert Walker
• What is the periodicity of the ENSO oscillation?

  Every 2 to 10 years
• What was Gilbert Walker's profession?

  Physicist and statistician
• What was the impetus for Walker's research?

  Monsoon failure in 1899
• What does the term 'El Niño' refer to?

  Warm currents near Peru and Ecuador

  
• What climate anomalies were observed in the 1970s?

  Droughts and heavy rainfall
• What is the relationship between El Niño and the Southern Oscillation?

  They are part of the same climate phenomena

  
• What drives the normal conditions in the ocean-atmosphere interaction?

  Trade winds and ocean circulation

  
• What is the role of the Walker circulation?

  It involves high and low pressure with precipitation

  
• What is the primary productivity in the western Pacific warm pool?

  High productivity
• What is the significance of the thermocline in ocean-atmosphere interaction?

  It separates warm surface water from cooler water
• What climate anomalies occurred in the 1970s?

  Droughts and heavy rainfall
• What was the most catastrophic anomaly in the 1970s?

  Collapse of the Peruvian anchovy fishery
• What did the research in the 1970s identify about climate anomalies?

  Many were linked through ocean and atmosphere interactions
• What does ENSO stand for?

  El Niño Southern Oscillation
• What direction do trade winds blow?

  From east to west
• What are the normal conditions in the ocean-atmosphere interaction?

  • Trade winds + ocean circulation
  • Walker circulation aloft
  • High and low pressure with associated precipitation
  • Warm pool in the west
  • Thermocline
  • Primary productivity
  • Southern oscillation

  
• What are the conditions during El Niño in the ocean-atmosphere interaction?

  • Weak/reversed trade winds
  • Ocean current changes
  • Precipitation shifts
  • Warm pool moves eastward
  • Thermocline becomes flat/stable
  • Upwelling stops/reduces

  
• What are the conditions during La Niña in the ocean-atmosphere interaction?

  • Stronger trade winds
  • High productivity
  • Cold water moves further west
  • Thermocline reaches further west
  • Larger area of upwelling
• What is the TAO array?

  A network of moorings in the Tropical Pacific

  
• What data does the TAO array send to shore?

  Oceanographic and meteorological data
• What is the Southern Oscillation Index (SOI) based on?

  Sea level pressure differences between Tahiti and Darwin

  
• What happens when pressure is higher in the east Pacific?

  It is lower in the west Pacific
• What are the signs of an El Niño event?

  • Warm water in the East Pacific
  • Reduced biological productivity in the East Pacific
  • Weak or reversed trade winds
  • Lower pressure in the East Pacific
  • Rain in the eastern section
  • Distant climate anomalies

  
• What are the typical conditions during an El Niño?

  • Warm water in the East Pacific
  • Weak trade winds
  • Increased rainfall in the eastern Pacific
  • Lower biological productivity