Weather and Climate Prediction ATM S 380

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1 Weather and Climate Prediction ATM S 380 Course web site Instructor: Professor Cecilia Bitz PhD in UW atmospheric sciences 1997, masters in physics Prof in atmospheric science and on faculty in Astrobiology Lecture notes and/or ppt will be posted ASAP after class

2 Learning Goals/Objectives How weather and climate models are applied to solving problems in atmospheric sciences Use of models and visualization as resources for professional careers in the environmental sciences. Basics in numerical methods and high-performance computing Phenomenological approach to understanding complex problems Empower undergraduates with research skills for independent learning and to assist with university research projects

3 Grading 50% Homework 10% Participation 15% Midterm 25% Final Final may be a final project or exam depending on class preference Midterm will likely be a take home

4 Textbook: By Kendal McGuffie and Ann Henderson-Sellers Third Edition Additional reading, especially about weather

5 The next few slides show examples of figures that you will make in homework assignments this term. They will be explained more at the time of the assignments. These are to give you an idea of what kinds of things you will do in this class.

6 Initial Conditions: Start with purely westerly jet, centered on equator NO DIABATIC HEATING (i.e., no sun, no longwave radiative loss to space, no moisture) Jablonowski et al 2008, NCAR Tech Note

7 850hPa Temperature Northern Hemisphere latitude longitude

8 latitude longitude

9 zonal wind at about 500hPa Wind average along latitudes and height latitude height relative to surface longitude Sea Level Pressure latitude Temperature average along latitudes and height

11 Zonal Wind Field at about 200hPa Black lines mark the maximum of the wind speed along meridians

12 Zonal Wind Field at about 200hPa Black lines mark the maximum of the wind speed along meridians for an ensemble. Note where they agree/disagree

13 The temperature field on a planet that always faces the sun at a single point in the center of the eyeball above

14 The Hadley Circulation on the eyeball planet looks like a mushroom cloud

15 Please tell me what interests you most and I will tailor the assignments to your interest. Would you like to see

16 More Idealized Dynamics Experiments? Initial Conditions: Start with purely westerly jet, centered on equator NO DIABATIC HEATING (i.e., no sun, no longwave radiative loss to space, no moisture) Jablonowski et al 2008, NCAR Tech Note

17 Hard-core atmospheric dynamics experiments?

18 Climate system experiments? -6 to -8 C +4 to +6 C T global = -3.4 C T global = +2.7 C

19 A brief history of modeling

Lewis Fry Richardson 1881-1953 Imagine a large hall like a theatre, except that the circles and galleries go right round through the space usually occupied by the stage.

20 Lewis Fry Richardson Imagine a large hall like a theatre, except that the circles and galleries go right round through the space usually occupied by the stage. The walls of this chamber are painted to form a map of the globe...a myriad computers are at work upon the weather of the part of the map where each sits, but each computer attends only to one equation or part of an equation... Numerous little "night signs" display the instantaneous values so that neighbouring computers can read them. in his book titled Weather Prediction by Numerical Process,1922

21 Lewis Fry Richardson Attempted the first weather prediction, after the fact It took 2 years and he found P = 145 hpa in 6 hours Wrong because he didnʼt filter the initial conditions to remove gravity waves and his prediction assumed the time derivative of the pressure field was accurate for too long (time step was too long)

22 Failure or Success? Took him 1000 hours of hand calculations to make the first predictions Found pressure would change by 145 mbar in 6 hours Hugely, hugely wrong. Richardson himself realized that noisy wind data was likely the problem He suggested 5 different smoothing methods to fix this

23 First Weather Prediction on Computers May 1955: Joint Numerical Weather Prediction Unit, Maryland First operational computer forecasts in US Global coverage since 1973 Computers surpassed human forecasts: 1980s?

The ENIAC Computer (ca 1943-56) 17,468 Vacuum Tubes, was 1000 times faster that previous computing machines.

24 The ENIAC Computer (ca ) 17,468 Vacuum Tubes, was 1000 times faster that previous computing machines. Weather forecast done in 1950 can now be done on a cell phone. ENIAC (Electrical Numerical Integrator and Calculator)

25 Pioneer in Climate Modeling Let the model tell you the answer" paraphrased from Manabe, 2005 Make the model physics as accurate as you possibly can and it will be better at predicting the climate than you could reason with pencil and paper. Syukuro Manabe meteorologist, Princeton

26 First Coupled Climate Model Manabe and Bryan (1969): First climate model with an ocean

27 Other Early Manabe Studies Early papers explored many influences on climate 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 solar radiation, doubling CO2, ice sheets, clouds, soil moisture, etc

Is there a difference between climate and weather? http://vorschau.emetsoc.

28 Is there a difference between climate and weather? has a nice series of slides about the merging of climate and weather prediction by Palmer

29 Goosse H., P.Y. Barriat, W. Lefebvre, M.F. Loutre and V. Zunz, Introduction to climate dynamics and climate modeling. Online textbook available at Fig 3.1

Weather and Climate Prediction ATM S 380

Weather and Climate Prediction ATM S 380 Course web site http://www.atmos.washington.edu/academics/classes/2011q1/380/ Instructor: Professor Cecilia Bitz, PhD in UW atmospheric sciences 1997 Lecture notes