AOSC 200

1
AOSC 200

• Lectures 21 to 24

2
Weather Forecasts

• Persistence - The weather tomorrow will be the
  same as the weather today (two times out of
  three)
• Climatology - The average weather for a
  particular month is the same each year
• Trend
• Analog
• Numerical Weather Prediction
• Observations
• Data Assimilation
• Forecast Model
• Tweaking
• Ensemble Forecasts

3
Present Climate

• Climate
• long term behavior
• Includes averages and extremes
• Climate Controls
• Latitude
• Elevation
• Topography
• Proximity of large bodies of water
• Atmospheric oceanic circulation

4
Climate system components

• Atmosphere
• Hydrosphere
• Cryosphere
• Solid Earth
• Biosphere

5
CLIMATE ZONES

• VLADIMIR KOPPEN ZONES
• TROPICAL MOIST A
• Wet or Wet dry or Monsoon
• DRY B
• Steppe or Arid
• Cold or Warm
• MOIST WITH MILD WINTERS C
• Marine or Humid Sub Tropical or Mediterranean
• MOIST WITH SEVERE WINTERS D
• Humid continental or subarctic
• POLAR E
• Tundra or Ice cap
• HIGHLAND H

6
Fig. 14-3, p. 414
7
Climate Change

• Very hard to accurately detect in short term data
• Satellite Data only goes back 20 to 30 years
• Other Instrument Data at best goes back several
  centuries with older data often unreliable
• Climate Proxies

8
Limitations of Climate Proxies

• Resolution
• most cannot resolve annual features
• Many cannot resolve decadal features
• There can be difficulty assessing the resolution
• Calibration
• How accurate is the correspondence between the
  measured proxy (isotope ratio) and the desired
  valued (temperature).
• What errors are present in the measurement itself
• Geographic extent
• How many places can we measure?
• What area affects the proxy? Is is local,
  regional or global?

9
NATURAL CAUSES OF CLIMATE CHANGE

• UNRELATED TO HUMAN ACTIVITY.
• VOLCANIC ACTIVITY
• ASTEROID IMPACTS
• SOLAR VARIABILITY
• VARIATIONS IN THE EARTH'S ORBIT
• PLATE TECTONICS
• CHANGES IN THE OCEAN CIRCULATION PATTERNS

10
Human Influences on Climate

• Greenhouse effect
• Feedbacks
• Northward movement of the jet streams
• Changing Land Surfaces
• Heat Islands

11
Possitive Feedback
12
Negative Feedback
13
More on Climate Change

• Movement of Jet Steams Large Scale Circulation
  Features
• Surface changes
• Land Use
• Water Use
• Ice Cover
• Sea Level Changes