PHYS-575/CSI-655 Introduction to Atmospheric Physics and Chemistry Lecture Notes #10: Climate Dynamics

1. PHYS-575/CSI-655Introduction to Atmospheric Physics and ChemistryLecture Notes #10: Climate Dynamics • The Present Day Climate • Climate Variability • Climate Equilibria, Sensitivity, and Feedbacks • Greenhouse Warming • Climate Monitoring and Prediction • Epilogue

2. Term Paper Topics PHYS 575: Jorge Aviles – Lunar resources for colonization, gas from minerals Jorge Cardona-Uribe – Hyperspectral data of atmospheric gases Jason Lee – Atmospheric Escape from Dwarf Ice Planets (e.g. Pluto) Sonny Louie – Earth & Venus: Comparative Greenhouse Effects Diana Marcu – Aurora on other planets Emily Mathison – Atmospheric Aurora Dana Ostrenga – Atmospheric Trends and Hurricanes Charley Sabateir – Sprites, Jets, and Elves Judy Shiple – Icecaps, Pollution and UV Radiation CSI 655: Liangbo Deng – Atmospheric Aurora and Airglow Min Li – Regional Effects of Climate Change Bill Mikelonis – IR Transmission & Atmospheric Correction Melissa Soriano – Regional Effects of Global Warming Eric Stofferahn – Climate Change and Human Migration Luan Vuong – Artificial weather modification Danqing Xiao – Mars Climate and effects of CO2

3. Term Paper Presentations • 8 minutes maximum for presentation • less than 8 (4-6 best) viewgraphs or figures • Additional 1-2 minutes Q&A • Overhead projector ok • Email PowerPoint file to me by noon 5/14

4. Climate Dynamics • Climateis the mean state of the atmosphere and related Earth components. • The mean state, including diurnal and seasonal variations, is referred to as the climatologically mean. • Departures from this mean state are called climate anomalies. • Climate variability refers to long-term changes in the mean state.

5. Types of Climate Variability • Intra-seasonal climate variability denotes month-to-month variations about the seasonally varying climatological mean that occur within the same season (e.g., the distinction between an abnormally warm January and an abnormally cold February. • Inter-annual variability denotes year-to-year variations of annual or seasonal averages (e.g., between the mean temperatures observed in successive winter seasons. • Decadal, century-scale, etc. denotes decade-to-decade, century-to-century, etc. scale variations.

6. 1. The Present-Day Climate • The mean state of the climate system is determined by: • The emission of radiation from the sun • The Earth’s rotation rate and orbital characteristics • The composition of the atmosphere • The interactions between the atmosphere and the other components • of the Earth system that determine the fluxes of mass, energy, and • momentum at the Earth’s surface. • The Earth’s history (occasional and mostly unpredictable internal and • external influences)

7. Annual Mean Conditions Stefan-Boltzmann Law Energy Flux from a Blackbody = σ T4 Albedo of Surface (Reflectivity) = A Luminosity of Sun at Earth: Ls = 1370 Watts m-2 Energy Flux from Sun at Distance D (in astronomical units) = Ls/D2 Equilibrium Temperature of a Planet of radius R: 4πR2σTe4 = (1 – A) πR2 Ls/D2 Tmean = 288K Tequilibrium = 255K The Role of the Atmosphere Tg > Te

8. Annural Mean Energy Budget

9. Global Energy Balance

10. Small Scale Drivers of Climate Variability:Sensible, Latent Heat and Radiation

11. Radiation vs. Convection

12. Vertical Energy Transport Conduction: Solar extreme ultraviolet (EUV) photons absorbed in the upper atmosphere deposit energy which is conducted downwards. Radiation: Stratospheric ozone (O3) absorb solar ultraviolet photons which cause local heating. Convection: The steep vertical temperature gradient produces unstable air parcels.

13. Solar Absorbed Visible Radiation and Terrestrial Infrared Radiation The spatial variation of solar visible and terrestrial IR flux is indicative of energy transport processes within the Earth’s atmosphere and ocean systems. The atmosphere and oceans contribute comparable amounts in the equator to pole energy flow.

14. 2. Climate Variability • Most of what we know about climate variability is based upon numerical • experiments with atmospheric models. Although we have only one Earth • climate system, we can do numerous simulations of that climate system • in order to explore the relative influence of the many factors that contribute • to the mean state and its variability. These numerical experiments show • That the Earth’s climate variability is controlled by a few general types of • affects: • Internally generated climate variability (e.g., NAO, PNA, etc) which • control weather spatial patterns such as storm tracks. • (2)Coupled climate variability: • Ocean: (e.g., ENSO) that control SST and precipitation patterns. • Biosphere: CO2, desertification, hydrology • Earth’s crust: weathering, biological pump • (3) Externally forced climate variability: • Solar variability • Volcanic eruptions

15. The North Atlantic Oscillation (NAO) is a persistent Sea Level Pressure Anomaly Internally Generated Climate Variability

16. Coupled Climate Variability:SST Anomalies and ENSO

17. SST Anomalies During El Nino Years

18. El Nino Southern Oscillation: ENSO

19. Regional Impacts of El Nino

20. SST and Surface Winds El Nino Cold Year

21. Marine Productivity SST from TOPEX/Poseidon

22. Externally Forced Climate Variability:Solar Variability

23. Sunspot Cycle

24. Solar Flux Variability

25. Volcanic Perturbations

26. Atmospheric Aerosols

27. 3. Climate Equilibria, Sensitivity, and Feedbacks • The Earth’s climate system is greatly influence by a variety of both positive • and negative feedbacks. • Water vapor feedback (water, temperature) • Clouds and water (albedo, water) • Vegetation and albedo (water, precipitation) • Hydrological cycle (ocean, precipitation) • Carbon dioxide (weathering, ocean solubility) • Ice coverage (albedo, temperature) • Oxygen, carbon dioxide (photosynthesis, respiration) • Positive Feedback: Water vapor – temperature • Temperature – Carbon Dioxide • Many of these act in way to minimize large climate variability (homeostasis). • Carbon cycle – weathering

28. Daisyworld: An Example of Homeostasis Consider a planet covered by only two kinds of daisies, white and black. Most daisies grow optimally within a narrow range of temperature. If the temperature is too high or too cold they die. When the solar flux is low and the surface temperature would be correspondingly low, black daisies would grow better by absorbing more energy and thus staying warmer. A lower albedo would warm the Earth. As the solar flux increases, the surface temperature would tend to increase and eventually only white daisies would be able to keep cool enough to survive.

29. Daisyworld http://203.237.194.159/gaia/chp5.html

30. Daisyworld

31. Daisyworld

32. 4. Greenhouse Warming http://www.koshland-science-museum.org/exhibitgcc/images/causes02.jpg http://www.agu.org/eos_elec/99148efig1.gif

33. The Greenhouse Effect

34. Atmospheric Carbon Dioxide

35. Greenhouse Gases Contributors

36. What is Global Warming? http://upload.wikimedia.org/wikipedia/en/f/f4/Instrumental_Temperature_Record.png

37. Global Temperature Anomaly

38. Retreat of Permafrost and Glaciers

39. Global Sea Level Rise

40. Questions for Discussion • What is the most important external driver of climate change? • What internal processes cause climate change? • Can episodic events, such as an asteroid strike, change the long term climate of a planet? • Can life modulate climate? • Is the Goldilocks problem really a problem? • Is global warming a certainty? • Is a runaway greenhouse for Earth inevitable?

41. Greenhouse Gases Contributors