Comprehensive Notes on Atmospheric Science, ENSO, and Air Pollution

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  • Midterm Exam:
    • Date: Saturday, January 25, 9-11 am
    • Location: In-person at UTM, room assignments will be posted later.
    • No aids are permitted in the exam; arrive by 9 am.

Section 2: El Niño, La Niña, and the Southern Oscillation

  • Topics Covered:
    • Overview of El Niño and La Niña phenomena and the Southern Oscillation.
    • Effects on global weather and wildlife, particularly in the equatorial Pacific.
What is ENSO?
  • Definition: El Niño-Southern Oscillation (ENSO) refers to periodic fluctuations in sea surface temperature and atmospheric pressure in the equatorial Pacific.
  • Characteristics:
    • Temperature and air pressure anomalies.
    • Affects global weather patterns.
    • Climate warming influences ENSO behavior.
ENSO Cycle and Global Impact
  • Weather Impacts:
    • Influences precipitation, temperature, and atmospheric circulation.
    • Affects hurricanes, monsoons, and droughts.
  • Applications:
    • Helps in agriculture, water resource management, and disaster preparedness.
Origin of the Term “El Niño”
  • Etymology: Spanish for "the little boy"; discovered by 19th-century Peruvian fishers noticing warming sea surface temperatures around Christmas.
  • Cool Phase: La Niña means "the little girl"; represents opposite conditions.
ENSO Cycle Phases
  • Phases Include:
    • El Niño, La Niña, and Neutral phases.
    • Phases are irregular and do not strictly sequentially follow.
Southern Oscillation Index (SOI)
  • Definition:
    • Standardized index measuring pressure differences between Tahiti and Darwin, Australia.
    • Negative SOI indicates below-normal SLP at Tahiti (El Niño condition).
  • Correlation with Sea Surface Temperature (SST):
    • Strong relationships indicate weather predictions.
Effects of El Niño and La Niña on Weather Patterns

  • El Niño Phase:

    • Weakened trade winds result in warmer ocean surface temperatures.
    • Suppression of cold water upwelling, affecting marine ecosystems.

  • La Niña Phase:

    • Strong trade winds push warm water west; promotes nutrient-rich upwelling in the East.
    • Cooler ocean surface temperatures lead to wetter conditions in some regions and drier in others.
Impact on Jet Streams
  • El Niño Winters:
    • Polar jet stream weakens, causing more meandering. Increased rainfall in the southern U.S. and drier conditions in parts of Canada.
  • La Niña Winters:
    • Strengthens polar jet streams causing cooler, wetter conditions in northern Canada.

Section 3: Atmospheric Pollutants and Aerosols

  • Focus Areas:
    • Ambient air pollution and contributions to this problem.
    • Role of aerosols in the climate system.
Composition of Air
  • Gaseous Components:
    • Nitrogen (N2): 78.08%, Oxygen (O2): 20.95%, Argon (Ar): 0.93%.
    • Variable gases include Water Vapor (H2O): 0-4%, Carbon Dioxide (CO2): 0.038%.
Environmental and Health Impacts
  • Air Pollutants: Gases and particulates added to the atmosphere, can originate from natural or anthropogenic sources.
    • Pollutant vs Contaminant:
    • Pollutant: harmful contaminant.
    • Contaminant: foreign substance in the environment.
  • PM and Health Risks:
    • Particles smaller than 2.5 µm are particularly harmful, can penetrate lungs and bloodstream.
Role of Aerosols in Climate
  • Definition: Tiny particles/droplets in air; range from natural sources (sea spray, volcanic ash) to anthropogenic (industry).
  • Cloud Formation: Aerosols act as nuclei for cloud formation, greatly influencing cloud properties.
    • Clouds can have both warming/cooling effects on climate based on type and interaction with aerosols.

Section 4: Sources and Types of Air Pollutants

  • Types of Pollutants:
    • Primary Pollutants: Directly harmful emissions (e.g., CO, NOx).
    • Secondary Pollutants: Formed when primary pollutants react with atmospheric compounds (e.g., ozone).
  • Smog Types:
    • Industrial Smog (Grey Air): Associated with SO2 from burning fossil fuels.
    • Photochemical Smog (Brown Air): Forms in sunlight from NOx and VOC reactions, primarily problematic in urban areas.
Acidic Deposition
  • Defined as acid or acid-forming pollutants moving from atmosphere to surfaces.
    • Can cause significant ecological harm, such as acidifying lakes and affecting aquatic life.
Criteria Air Contaminants
  • Include harmful compounds such as SO2, NOx, PM, VOCs, CO, and ammonia.
  • Important for health and need regulation and monitoring due to their effects on air quality.
Conclusion
  • Understanding air pollution's sources, types, and their interaction with the environment is crucial for developing effective management strategies to protect public health and ecosystems.