// lecture 23

Question 1

why is CO2 highly correlated to ice volume?

Answer 1

incomplete answer: colder oceans can dissolve more atmospheric CO2.
- but possibly more plankton active taking CO2 out of atmosphere and/or seawater exchange between surface and deep was greater

Question 2

Younger Dryas (YD)

Answer 2

• example of rapid climate change
• 14700 kbp, the warming trend reversed
• relatively cold period lasted about 2,000 years
• warmed very abruptly about 12,000 years ago, and has been relatively stable since

Question 3

cause of YD

Answer 3

• probably by ice sheet breakup and flooding in the northern N. Atlantic
• meltwater pulse could cause the thermohaline circulation to shutdown
• reducing heat transport into northern n. atlantic

Question 4

numerical weather prediction (NWP)

Answer 4

• improvement in weather prediction data over the last 60 years is among the most impressive accomplishments of society; 3, 5, and 7 day forecasts have improved in both NH and SH

Question 5

Lewis Fry Richardson

Answer 5

• made the first numerical weather prediction in 1922

Question 6

Richardson’s Dream: The Forecast Factory

Answer 6

• filled with employees (“Computers”) doing calculations; estimated 64,000 people would be necessary to forecast over the global

Question 7

Richardson’s Experiment

Answer 7

• used data from - May 20, 1910 and made Leipzig charts for surface pressure and temp.
• data was taken when haley’s comet was passing through; all values were tabulated by hand.

Question 8

Richardson’s calculations

Answer 8

• took 10,000 hours of work to perform calculations

- book lost during a battle, but eventually recovered and published in 1922

Question 9

Richardson… failure or success?

Answer 9

• first prediction was for pressure to change by 145 mbar in 6 hrs… that would be record setting
• he realized that noisy wind data was likely the problem and suggested 5 diff. filtering methods to fix this
• but he couldn’t try this experiment again, need computer’s of today

Question 10

computer forecast w/ richardson’s proposed fix

Answer 10

• becomes a good forecast with his filtering methods used

Question 11

first weather prediction on computers

Answer 11

• 1950: Charney, Fjortoft and von Neumann paper
• May 1955: Joint numerical weather prediction unit, maryland: first operational computer forecasts in US
• global coverage since 1973
• computers surpassed human forecasts: 1980’s?

Question 12

ENIAC computer (1943-56)

Answer 12

• 17,468 vacuum tubes, was 1000 times faster than that of previous computing machines
• original computer weather forecast done in 1950 can now be done on a cell phone

Question 13

weather vs climate forecasting

Answer 13

• similar bc use similar mathematical equations

- but weather is short term; climate is long term

Question 14

Chaos Theory

Answer 14

• Ed Lorenz was running a computer model and put in slightly different inputs; found the predictions were similar for a while but then wildly diverged to diff. solutions

Question 15

Butterfly effect

Answer 15

• Ed Lorenz; weather forecasts depend on initial observations but climate models don’t

Question 16

Climate forecasts

Answer 16

examples
- summer is hotter than winter, after a strong volcano erupts, the earth will cool, the earth will be hotter with more GHG’s, shifts in weather patterns when El nino is present

Question 17

Suki Manabe: father of climate modeling

Answer 17

• gradually builds up more sophisticated climate models:
• radiation only model (LW and SW): M. and Moller (1961)
• above plus convection: M. and Strickler (1964)
• model with atmospheric motions (but no ocean yet): Smagorinsky, M. and Holloway (1965)

Question 18

first coupled climate model

Answer 18

Manabe and Bryan (1969)

Question 19

first global warming forecast

Answer 19

Manabe and Wetherald (1975)

Question 20

other early manabe studies

Answer 20

• effect of ocean circulation on climate: turn off ocean model
• effect of moisture: don’t allow condensation to occur
• effect of mountains: bulldoze all topography
• effect of changing soalr radiation, doubling CO2, ice sheets, clouds, soil moisture, etc.

Question 21

GCM (global climate model) Components

Answer 21

• equations of fluid motion on a rotating sphere
• both the atmosphere and ocean are just fluids
• equations put simple physics principles in mathematical form

Question 22

parts of climate model - 1968

Answer 22

• uses laws of physics
• momentum equation
• heat equation
• water equation
• for both atmosphere and surface and later ocean too

Question 23

change in resolution overtime

Answer 23

FAR -> TAR -> SAR -> AR4

Question 24

within each grid cell

Answer 24

there are things that are not explicitly modeled (clouds) that must be approx. or parameterized

Question 25

cloud schemes

Answer 25

cloud interactions are the most uncertain process in GCMs, lead to the largest differences between models