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Results of the survey on 01/15/13:

Results of the survey on 01/15/13:. Rainfall, snow, severe storms formation and intensity, drought and flood Climate phenomenon, model, prediction, Ecosystem, hydrology How earth climate system works together, Ecosystem, hydrology, ocean current, ice cap, greenhouse effects

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Results of the survey on 01/15/13:

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  1. Results of the survey on 01/15/13: • Rainfall, snow, severe storms formation and intensity, drought and flood • Climate phenomenon, model, prediction, • Ecosystem, hydrology • How earth climate system works together, Ecosystem, hydrology, ocean current, ice cap, greenhouse effects • Planetary atmosphere • Winds and its processes

  2. 1. Compositions of the atmosphere: Key questions: • How do compositions and physical structure of the atmosphere and ocean influence climate at different spatial/temporal scales? • What climate consequence should we expect if they change? Reading assignment: Chs. 1 (p 1-22) of the Textbook, Wallace and Hobbs GEO 387P: assigned papers

  3. 1.1 A Brief survey of the atmosphere • Depth and mass • Composition • Vertical structure • Winds and pressure • precipitation

  4. The most important factors that determine the earth’s climate?

  5. Chemical composition: Constituent Molecular weight Fractional concentration by volume Nitrogen (N2) 28.013 78.08% Oxygen (O2) 32.000 20.95% Argon (Ar) 39.95 0.93% Water vapor (H2O) 18.02 0 − 5% Carbon dioxide (CO2) 44.01 380 ppm Neon (Ne) 20.18 18 ppm Helium (He) 4.00 5. ppm Methane (CH4) 16.04 1.75 ppm Krypton (Kr) 83.80 1. ppm Hydrogen (H2) 2.02 0.5 ppm Nitrous oxide (N2O) 56.03 0.3 ppm Ozone (O3) 48.00 0−0.1 ppm

  6. What constituents are important to climate? • Are they well mixed? Why?

  7. Rank greenhouse gases by their importance for greenhouse effect: Now: 394.39

  8. Question-1 • During the past 100 years, the increase of greenhouse gases has caused an increase of downward longwave radiation of ~ 3 Wm-2. • a) What would be the rate of surface air temperature change (at 1 m above the surface)? Assume that other energy fluxes, the surface air density remain as 1 Kg/m3. • B) Why hasn’t earth surface temperature rising so fast?

  9. The vertical structure: • What cause atmospheric density and pressure to decrease with height? • How does this density profile influence atmospheric thermodynamic stability? • If the vertical gradient of air density increase, would you expect more or less clear sky? Why? r(z) Fig. 1.8 Vertical profiles of pressure in units of hPa, density in units of kg m−3, and mean free path (in meters) for the U.S. Standard Atmosphere.

  10. Question-2: • What does surface pressure, Ps, represent?

  11. What does surface pressure, Ps, represent? RE

  12. Scale Height: • What is scale height? • The e-folding depth of the atmosphere, where bulk of the air mass is located, a characteristics of thickness for atmosphere layer • useful in estimate height of various pressure levels, range from 7-8 km in the lowest 100 km atmosphere

  13. Question-3 • Estimate height of 200 mb pressure level, assume H=8 km, sea-level pressure 1000 hPa, using z/H=ln(Po/P) • Discussion: Do you expect scale height change in a warmer climate? If so, how would it change?

  14. Estimate height of 200 mb pressure level, assume H=8 km, sea-level pressure 1000 hPa, using z/H=ln(Po/P) • Height of 100 mb pressure level? • Answer: 18.42 km for H=8km,

  15. The typical vertical temperature structure: • Troposphere: 0-15 km, but varies from tropics to polar-region (Can you guess how is varies?), where most of weather processes occur. • Why does T decrease with height in the troposphere? • Why do most of weather related process occur in the troposphere, but not stratosphere? • If the lapse rate, increases, would you expect more clouds and rainfall or less?

  16. Troposphere lapse rate, G=-dT/dz • Mean lapse rate: G=-dT/dz=-(Ttropopause-Tsfc)/ztropopause =-(-80C-27C)/17 km=6.3 C/km Is the atmospheric lapse greater or smaller in tropics compared to high latitudes? Why? How is latitudinal change of the lapse rate related to climate difference?

  17. Stratosphere: 15-50 km, • T increases with height. • Why? • How is this related to very stable atmosphere in this layer? • Importance to climate • QBO, sudden warming • O3 • Stratosphere-troposphere coupling and influence on surface • Stratosphere aerosols

  18. Mesosphere: 50-80km, • T decreases again with height. • Why? • Not as important to climate as troposphere and stratosphere, but important to telecommunication.

  19. Solar forcing Volcanoes • How would an increase of CO2 influence lapse rate of the troposphere? • Some climate model simulations suggest that inject aerosols to stratosphere may reduce rainfall. Can you speculate the reason? Ozone changes Greenhouse gases IPCC 2007; chapter 9

  20. T and wind at the surface and middle troposphere: • What is relationship between surface temperature and winds? • What are the differences between the surface and mid-tropospheric T/G and winds?

  21. Horizontal distribution of Wind and pressure: Large-scale surface winds are determined by surface pressure gradient and frictional forces Above the atmospheric boundary layer, large-scale winds are mainly determined by pressure gradient. Pressure gradient is mainly determined by surface temperature gradient;

  22. Zonal mean meridional tropospheric circulation: Easterly wind: wind from the east Westerly: wind from the west Why? • Annual mean: Easterly in tropics, westerly in middle and higher latitudes. • Strong seasonal change Question: • Why does easterly wind occur in tropics and westerly in mid-latitude?

  23. Monsoon winds Monsoon winds are driven by seasonal change of land-ocean surface temperature gradient Winds blow from ocean to land in summer, vice versa in winter Major monsoon regions: Asia-Australia (South and East Asian monsoons, Australia monsoon) Africa monsoon (E. and W. Africa) American monsoons (S. and N American monsoons)

  24. Precipitation and clouds: What is your impression about rainfall and cloud distributions? How are rainfall and cloud distributions related to winds? Can you identify important weather and climate systems in these maps?

  25. Summary: • In addition to the earth’s orbital configuration, atmosphere composition, esp. greenhouse gases, and their radiative properties determine the atmospheric temperature profile and layers; • Pressure gradient in the atmospheric is the most important driving force of the air motion. The atmospheric pressure at the given height is determined by the weight of air column above that height. It is influenced by T, q of the atmosphere. The unit is hPa=100 N/m2. • Variables that key for describing the atmospheric pressure and temperature stratification: scale height (H) and lapse rate (G).

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