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LIVE INTERACTIVE LEARNING @ YOUR DESKTOP. NOAA/NSTA Web Seminar: The Ocean’s Role in Weather and Climate. http://institute.nsta.org/web_seminars.asp.

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slide1

LIVE INTERACTIVE LEARNING @ YOUR DESKTOP

NOAA/NSTA Web Seminar:

The Ocean’s Role in Weather and Climate

http://institute.nsta.org/web_seminars.asp

slide2

The influence of the Atlantic ocean on climate, from Atlantic hurricanes to African droughtThomas L. DelworthGeophysical Fluid Dynamics Laboratory/NOAAPrinceton, NJ

  • Outline:
  • Basics of the Atlantic Ocean
  • Multidecadal changes in the Atlantic: impact on climate
    • African drought
    • Conditions for tropical storms
    • Hemispheric temperature
  • 3. Global warming and the Atlantic
slide3

Schematic of Atlantic Ocean Circulation

Sinking water

at high latitudes

Ocean moves

heat poleward

1.3*1015 Watts

from “Earth's Climate Past and Future”, Ruddiman.

slide7

Question: The rate of heat (energy) transported by the Atlantic ocean is ~1.3 *1015 Watts. The amount of energy moved poleward by the Atlantic Ocean each year is the equivalent to approximately how many years of total U.S. electricity generation:

slide8

Observed Atlantic Sea Surface Temperature

Temperature (Deg C)

(60oW-20oW,6oN-18oN)

Tropical North Atlantic

slide9

Outline:

  • Basics of the Atlantic Ocean
  • Multidecadal changes in the Atlantic: impact on climate
    • African drought
    • Conditions for tropical storms
    • Hemispheric temperature
  • 3. Global warming and the Atlantic
slide10

Atlantic Ocean Temperature

(80oW-0oW,0oN-60oN)

slide11

Observed change in Sea Surface Temperature (Deg C)

1996-2005 minus 1970-1990

Where did the largest warming take place?

Data from

Aug-Oct

slide12

Tree ring records show that AMO-like fluctuations

have existed for centuries.

Gray et al., 2004, Geophysical Research Letters

slide13

How can we better understand (and predict) the impact of the North Atlantic ocean on climate?

  • Diagnostic analyses of observational data
  • Use computer models of the climate system to better understand how the climate system works (cause and effect) and to predict its future evolution

Computer climate model is a “Virtual Earth”, in which we can perform many experiments to better understand the system.

slide14

In models, the earth’s land, ocean and atmosphere are chopped into 5 million grid cells.

Horizontal Grid (Latitude-Longitude)

Vertical Grid (Height or Pressure)

Climate models use world’s fastest supercomputers … but need

computers that are 1000 times faster (at least!).

slide16

Where is climate modeling done?

ENGLAND

JAPAN

CANADA

GERMANY

USA

Princeton, NJ

New York, NY

Boulder, Colorado

AUSTRALIA

slide17

Observed

Precipitation

(mm/month)

100 mm/month is

about 50 inches per year

Data from Univ. of

East Anglia,

Climatic Research

Unit (CRU)

January

Sahel

Seasonal migration

of Intertropical

Convergence

Zone (ITCZ)

July

1950 2000 trends in observed and simulated precipitation jas
1950-2000 trends in observed and simulated precipitation (JAS)

Simulated

Observed

(Atmosphere model forced with

observed SSTs 1950-2000)

slide19

Simulated rainfall changes

Modeled AMO Index

Observed AMO Index

Observed rainfall changes

slide20

Let’s do a poll question!

The rainy season in the Sahel region of Africa is:

slide21

Simulated Summer Rainfall Changes Associated with Warm North Atlantic

Blue means more rainfall

when the North Atlantic

is warm

Units: cm/day

slide22

Simulated multidecadal JJAS surface air temperature difference (K) (1931-1960) – (1961-1990)

slide25

Reduction in Wind Shear when North Atlantic Warms relative to South Atlantic

Observations

Model (GFDL CM2.1)

Zhang and Delworth, 2006

Red means less shear, and therefore more favorable conditions for hurricanes.

CONCLUSION: Models demonstrate that a warming North Atlantic (relative to the South Atlantic) CAUSES atmospheric circulation changes that are favorable for tropical activity.

slide26

Outline:

  • Basics of the Atlantic Ocean
  • Multidecadal changes in the Atlantic: impact on climate
    • African drought
    • Conditions for tropical storms
    • Hemispheric temperature
  • 3. Global warming and the Atlantic
slide28

Let’s do a poll question!

If all emissions of carbon dioxide were stopped tomorrow, how long would the ocean continue to warm?

observed and modeled tropical north atlantic sst
Observed and Modeled Tropical North Atlantic SST

Modeled (GFDL CM2.1)

Observed

Key uncertainty:

Role of aerosols

In late 20th century

Steady or slightly

cooling temps

Rapid

Warming

looking at 21 st century simulations projected atlantic sst change relative to 1991 2004 mean
Looking at 21st Century SimulationsProjected Atlantic SST Change (relative to 1991-2004 mean)

Areal average

70oW-0oW

0oN-60oN

Results from

GFDL CM2.1

Global Climate

Model

(SRES A1B)

Observed

Trend from

1950-2004

slide32

Summary/Discussion

  • - Atlantic Ocean plays a crucial role in climate through
  • transporting large amounts of heat from the Tropics to
  • higher latitudes.
  • - Multidecadal fluctuations in ocean circulation have
  • strong influence on climate, including African and Indian
  • monsoon rainfall, Atlantic hurricane activity, and North
  • American temperature.
  • - Increasing greenhouse gases are significantly warming
  • the Atlantic, and will continue to do so in the future.
slide33

National Science Teachers Association

Gerry Wheeler, Executive Director

Frank Owens, Associate Executive Director Conferences and Programs

Al Byers, Assistant Executive Director e-Learning

NSTA Web Seminars

Flavio Mendez, Program Manager

Jeff Layman, Technical Coordinator

Judith Lopes, Administrative Assistant

Susan Hurstcalderone, Volunteer Chat Moderator

LIVE INTERACTIVE LEARNING @ YOUR DESKTOP