Transcript Geography 120 Earth Systems II: The Atmospheric Environment

Overview II: Importance of the
atmospheric boundary layer
Review of last lecture
• The mission of meteorology is to understand and
predict weather- and climate-related disasters (e.g.
tornados, hurricanes, El Nino and global warming).
• 3 scales: weather, climate, climate change
• The modern climatology (meteorology) was born in the
1940s (a very young science!), but has been growing
very fast! Now we have a global observational network
with many satellites, ships, radars and surface
stations, as well as very comprehensive prediction
models running on the world’s largest computers.
The current status of weather and
climate predictions
• Weather prediction: Generally good within
one week, not good beyond 10 days. The skill
depends on season and location.
• Tropical cyclone (hurricane, typhoon)
prediction: good in track, but bad in intensity
• Climate prediction: Seasonal prediction
generally good within 6 months, but not good
beyond. Skill depends on season.
• Climate projection: All models project global
warming in the 21st century, but with a 3-fold
difference in magnitude.
Why is it so difficult to understand
and predict weather and climate?
Problem I: Different parts of the world are
strongly connected to each other
(The “Teleconnection Problem”)
Global atmospheric flow
Example 1: Global impacts of El Nino
Example 2: Global impacts of the mini
El Nino (Madden-Julian Oscillation)
Factors affecting US weather and
climate
Arctic
N. Atlantic
Atlantic/
Sahel
Madden-Julian
Oscillation
El Nino
Amazon
Any location is affected by all the other
locations, and in turn is affecting all the
other locations
Problem II: Different components of the earth
system (atmosphere, land, ocean, ice, clouds, etc)
are strongly interacting with each other
(The “Feedback Problem”)
Example I: Melting of Arctic sea ice
Video: Ice Albedo feedback
• http://www.youtube.com/watch?v=5rqREjFaRho
Example 2: Generation of hurricanes
Heat from the ocean
Example 3: Generation of El Nino
(Lin 2007, Journal of Climate)
Problem III: The earth system composes of both very big
objects (such as the whole Pacific Ocean) and very small
objects (such as the cloud droplets), making it very difficult
to draw them on the same page
(The “Subgrid-Scale Problem”)
Vertical Structure of the Atmosphere
• Definition of the atmospheric boundary layer (ABL): "that part of
the troposphere that is directly influenced by the presence of the earth's
surface and responds to surface forcings with a time scale of about an
hour or less.”
• Scale: variable, typically between 100 m - 3 km deep
Importance of ABL:
(1) Interface between atmosphere and ocean/
land/ice - flux transfer and feedback
Importance of ABL:
(2) The human beings are living in the ABL
and changing the climate system
• Release of greenhouse gases
• Release of pollutants (aerosols)
• Change of land cover (deforestation and afforestation)
Importance of ABL:
(3) A basic subgrid-scale process
Some Great
Weather/Climate Scientists
Prof. Lonnie Thompson –
OSU
• Father of Tropical Glaciology
• Spent an enormous amount
of time above 5500 m
• Discovered solid record for
Earth’s climate history
• Grown up in West Virginia
• Did three part-time jobs in
high school to make a living
• Worked for many years with
low salary
• Went back to the Himalayas
after heart transplant
Prof. Robert Cess
SUNY at Stony Brook
• World’s leading expert on climate
change and Earth’s energy budget
• Organized the first international
team for supercomputer
prediction of global climate
change, and many NASA and
DOE projects
• Was not even an AMS Fellow
when received the Charney Award
• Finished his Ph.D. in 3 years
while doing a full-time job and
taking care of his first child
• Hobby: Collectible cars
The young generation
Video: Prof. Dargan Frierson and Elizabeth
Maroon sing The World of Daisies (lyrics by Prof.
Mike Wallace) in ATM S 111: Global Warming
• https://www.youtube.com/watch?v=kYySTtFcQlU
Importance of hobbies
• Research is a slow walk: Relax and have fun
• Research is an Art: Intuition and taste
Summary
• The current status of weather and climate predictions:
(1) weather prediction good to 10 days, (2) tropical
cyclone prediction good in track but not in intensity, (3)
climate prediction good to two seasons, (4) climate
change projections have a 3-fold difference in
magnitude.
• The main reasons of the difficulties in weather and
climate predictions: (1) Teleconnection problem, (2)
Feedback problem, and (3) Subgrid-scale problem.
• Importance of the ABL: (1) interface between
atmosphere and ocean/land/ice - flux transfer and
feedback, (2) the human beings are living in the ABL
and change the environment, (3) a basic subgrid-scale
process
• Some great climate scientists. Importance of hobbies.