🌡️Intro to Climate Science Unit 4 – Atmospheric & Oceanic Circulation

Key Concepts

• Atmospheric circulation transports heat, moisture, and momentum around the planet
• Ocean currents play a crucial role in redistributing heat and influencing climate patterns
• Interactions between the atmosphere and ocean drive global climate and weather systems
• Climate drivers (external factors) and feedbacks (internal processes) shape Earth's climate
• Global atmospheric and oceanic circulation patterns have regional variations and impacts
• Measurement techniques (satellites, buoys) and modeling approaches are used to study circulation
• Understanding circulation is essential for weather forecasting, climate predictions, and various applications

Atmospheric Circulation Patterns

• Hadley cells are large-scale tropical atmospheric circulation patterns driven by solar heating and the Coriolis effect
  • Rising motion near the equator, poleward flow aloft, descending motion in the subtropics, and equatorward flow near the surface
• Ferrel cells are mid-latitude circulation patterns characterized by rising motion in subpolar regions and sinking motion in the subtropics
• Polar cells are small-scale circulation patterns in high latitudes with descending cold air and surface divergence
• Jet streams are narrow, fast-moving air currents in the upper atmosphere that steer weather systems and influence global circulation
  • Polar jet stream is located between the Ferrel and Polar cells, while the subtropical jet stream is between the Hadley and Ferrel cells
• Rossby waves are large-scale atmospheric waves that propagate in the mid-latitudes and influence weather patterns
• Trade winds are persistent easterly winds near the Earth's surface in the tropics, driven by the Hadley circulation
• Monsoons are seasonal changes in atmospheric circulation and precipitation, driven by differential heating between land and sea

Ocean Currents and Circulation

• Surface currents are primarily driven by wind stress and influenced by the Coriolis effect, forming large-scale gyres
  • Examples include the Gulf Stream (North Atlantic), Kuroshio Current (North Pacific), and Antarctic Circumpolar Current
• Thermohaline circulation (global ocean conveyor belt) is driven by density differences due to temperature and salinity variations
  • Includes deep water formation in polar regions (North Atlantic, Southern Ocean) and upwelling in other areas
• Ekman transport is the net movement of surface water perpendicular to the wind direction due to the Coriolis effect
• Upwelling occurs when deep, cold, nutrient-rich water rises to the surface, often driven by wind-induced Ekman transport
• Downwelling involves the sinking of surface water, typically in convergence zones or areas of high salinity
• Eddies are small-scale, circular currents that can transport heat, nutrients, and energy in the ocean
• El Niño and La Niña are oscillations in the Pacific Ocean characterized by changes in surface temperature, affecting global climate patterns

Interactions Between Air and Sea

• Ocean-atmosphere coupling involves the exchange of heat, moisture, and momentum between the two systems
• Sea surface temperature (SST) influences atmospheric circulation by altering heat and moisture fluxes
  • Warm SSTs can fuel tropical cyclones, enhance precipitation, and affect air temperature and humidity
• Wind stress on the ocean surface drives currents, waves, and vertical mixing
  • Influences upwelling, downwelling, and the distribution of heat and nutrients in the upper ocean
• Evaporation from the ocean surface is a key source of atmospheric moisture, affecting precipitation patterns and the global water cycle
• Air-sea gas exchange involves the transfer of gases (carbon dioxide, oxygen) between the atmosphere and ocean
  • Plays a crucial role in the global carbon cycle and ocean acidification
• Sea ice influences air-sea interactions by altering surface albedo, heat exchange, and momentum transfer
• Teleconnections are long-distance relationships between atmospheric and oceanic phenomena, such as El Niño's impact on global weather patterns

Climate Drivers and Feedbacks

• Solar radiation is the primary external driver of Earth's climate system, providing energy for atmospheric and oceanic circulation
• Greenhouse gases (carbon dioxide, water vapor, methane) trap heat in the atmosphere, influencing global temperatures and circulation patterns
• Volcanic eruptions can temporarily cool the climate by injecting aerosols into the stratosphere, reflecting incoming solar radiation
• Orbital variations (Milankovitch cycles) affect the amount and distribution of solar energy reaching Earth on long timescales
• Albedo feedback involves changes in the reflectivity of Earth's surface (snow, ice, vegetation) that amplify or dampen climate changes
• Water vapor feedback is a positive feedback mechanism where warmer temperatures lead to increased atmospheric moisture, further enhancing the greenhouse effect
• Cloud feedback can have both positive and negative effects on climate, depending on cloud type, altitude, and optical properties
• Carbon cycle feedbacks involve the exchange of carbon between the atmosphere, oceans, and land, influencing atmospheric CO2 concentrations

Global Impact and Regional Variations

• Latitudinal temperature gradients drive atmospheric and oceanic circulation, with heat transported from the equator to the poles
• Atmospheric and oceanic circulation patterns influence the distribution of precipitation, leading to wet and dry regions
  • Hadley circulation contributes to the formation of deserts in the subtropics and tropical rainforests near the equator
• Monsoon systems (South Asian, West African, North American) are characterized by seasonal reversals in wind direction and precipitation patterns
• El Niño-Southern Oscillation (ENSO) affects global temperature and precipitation patterns, with regional impacts on agriculture, natural disasters, and ecosystems
• The Intertropical Convergence Zone (ITCZ) is a region of low pressure and heavy rainfall near the equator, influenced by atmospheric circulation
• Arctic amplification refers to the enhanced warming of the Arctic region compared to the global average, with implications for sea ice, permafrost, and global climate
• Ocean circulation redistributes heat, impacting regional climates and influencing phenomena such as the formation of tropical cyclones and the moderation of coastal temperatures

Measurement and Modeling Techniques

• Satellites provide global observations of atmospheric and oceanic variables, such as temperature, moisture, wind, and sea surface height
• Weather balloons (radiosondes) measure vertical profiles of temperature, humidity, and wind in the atmosphere
• Buoys and drifters are used to collect data on ocean temperature, salinity, currents, and air-sea interactions
• Argo floats are autonomous underwater vehicles that measure temperature and salinity profiles in the upper 2,000 meters of the ocean
• Climate models simulate atmospheric and oceanic circulation using mathematical equations and numerical methods
  • General Circulation Models (GCMs) represent the large-scale behavior of the atmosphere and ocean
• Data assimilation techniques combine observations with model simulations to improve the accuracy of weather forecasts and climate predictions
• Reanalysis datasets provide consistent, long-term records of atmospheric and oceanic variables by combining observations and model simulations

Real-World Applications and Case Studies

• Weather forecasting relies on understanding atmospheric circulation patterns to predict short-term changes in temperature, precipitation, and wind
• Climate predictions and projections use knowledge of atmospheric and oceanic circulation to assess long-term changes and impacts
• Ocean circulation models are used for applications such as marine ecosystem management, oil spill response, and search and rescue operations
• Studying the impact of climate change on atmospheric and oceanic circulation is crucial for adaptation and mitigation strategies
  • Changes in the strength and position of the jet stream can affect weather patterns and the frequency of extreme events
• Monsoon prediction is essential for agricultural planning, water resource management, and disaster preparedness in affected regions
• Understanding El Niño and La Niña events helps in forecasting their impacts on global weather patterns, agriculture, and natural hazards
• Investigating the role of ocean circulation in heat transport and carbon sequestration informs climate change mitigation efforts
• Atmospheric and oceanic circulation knowledge is applied in renewable energy industries, such as wind and wave power generation