Class Meets: Wednesday 10:30am-1:15pm

Office Hours• Whenever my door is open• By appointment

Emails: use subject CLIM713Course Website: http://mason.gmu.edu/~kpegion/teaching/clim713/

CLIM 713 Atmosphere-Ocean Interactions

Dr. Kathy Pegion (kpegion@gmu.edu)Research Hall 260

Course Format & Expectations

• Grading

a) 40% Labs/Homework (4)b) 20% Mid-Term (Mar 4)c) 40% Project/Term Paper (see schedule for

due dates)

• Class Discussion!

Course Format & Expectations

Policy on collaboration for homework, labs, projects:

• You are encouraged to discuss homework, labs, and projects with each other.

• Each student turns in their own version, written in their own words.

• Each student writes their own code and makes their own plots.

Class Schedule

Some Logistics

1. Bring your laptops to class

2. COLA computing accounts

a) Write your name & a phonetic spelling of your name

b) 3 things about yourself: 2 are true, 1 is not

c) What are your research interests?

d) What questions do you have about air/sea interactions and ENSO & what do you want to learn?

e) What is your level of experience/comfort using GrADS to view and analyze climate datasets (scale of 0-10)?

Introductions

1. Lecturea) Overview of the Tropical Coupled Ocean-Atmosphere

Systemb) What is ENSO?c) Why is it important?d) How do we monitor and predict it?

2. 5min Break

3. Laba) Introduction to UNIX and GrADSb) Where to find datac) How to Plot datad) Plotting basic ocn & atm datasets

Winds

SST Atm Heating/Convec

tion

Atmosphere-Ocean

Interactions

How do winds impact the ocean to cause changes in SST?

How do changes in SST impact atmospheric heating/convection?

How do changes in convection produce changes in winds in the atmosphere?

Overview of Tropical Ocean-Atmosphere System

September-October-November Sea Surface Temperature Climatology

Credit: B. Kirtman, University of Miami

Why is SST colder in the Eastern Pacific than in the Western Pacific?

Zonal Momentum Flux (Wind Stress)

Credit: B. Kirtman, University of Miami

September-October-November Equatorial Temperature Climatology

Credit: B. Kirtman, University of Miami

Air-Sea Heat Flux

Heat Flux INTO the Ocean Heat Flux OUT OF the Ocean

Credit: B. Kirtman, University of MiamiWhy is there seasonal difference?

Ocean Mixed-Layer

September-October-November Equatorial Temperature Climatology

Credit: B. Kirtman, University of Miami

Credit: B. Kirtman, University of Miami

Ocean Mixed-Layer

Credit: B. Kirtman, University of MiamiWhy is there a seasonal difference?

Credit: NOAA/NCEP/Climate Prediction Center

Walker Circulation

Summary

1. Large scale SST – Identify warm pool, cold tongue, why is SST colder in the east and warmer in the west? Why do SSTs change seasonally?

2. What is the Walker Circulation?3. Ocn mixed layer - what is it? What is the thermocline? How does it change with the

seasons/regions and why?

Key point: Wind (or wind stress) has a large impact on the ocean and its variability

Part a of Lab/Homework #1

Winds

SST Atm Heating/Convec

tion

Atmosphere-Ocean

Interactions

How do winds impact the ocean to cause changes in SST?

How do changes in SST impact atmospheric heating/convection?

How do changes in convection produce changes in winds in the atmosphere?

What is ENSO?

ENSO=> El Niño – Southern OscillationYear-to-year (interannual) coupled ocean-atmosphere

variability about the mean annual cycle in the tropical Pacific

El Nino/La Nina (ocean) – alternating warm and cold SST anomalies in the tropical Pacific; there are corresponding anomalies in the ocean subsurface.

Southern Oscillation (atmosphere) – alternating high and low surface pressure between the eastern (Tahiti) and western (Darwin) Pacific Ocean – a measure of the Walker Circulation

Timescale: on average 4 years; ranges from 2-7yrs

December 1982-2001SST Climatology

December 1997Total SST

December 1997SST Anomaly

Credit: B. Kirtman, University of Miami

December 1997 ( El Nino) Thermocline Depth Anomalies

Credit: B. Kirtman, University of Miami

El Nino vs. Normal Thermocline Depth

Thermocline is Shallower than Normal

Negative Depth Anomaly

Thermocline is Deeper than Normal

Positive Depth AnomalyCredit: B. Kirtman, University of Miami

Credit: NOAA/NCEP/Climate Prediction Center

Credit: NOAA/NCEP/Climate Prediction Center

Credit: NOAA/NCEP/Climate Prediction Center

Summary

1. What is ENSO? – atmosphere and ocean component2. Explain El Nino and La Nina Conditions in terms of changes in winds, SST,

thermocline, surface pressure, precipitation, and the Walker Circulation relative to normal conditions

Parts b & c of Lab/Homework #1

Why is ENSO important?

• Dominant example of coupled ocean-atmosphere interactions

• Major climate and economic impacts on countries around the tropical Pacific, and further afield.

• Droughts in some regions, floods in others

• Collapse of coastal fishery in Peru(largest average annual catch of marine fish in the world)

Credit: NOAA/NCEP/Climate Prediction Center

Summary

1. ENSO is important because it has global impacts

ENSO Monitoring, Current Conditions, and Prediction

Credit: NOAA/NCEP/Climate Prediction Center

Credit: NOAA/NCEP/Climate Prediction Center

Credit: NOAA/PMEL

Warm Upper Layer

Cold Lower Layer

Thermocline

Credit: NMME Team

Summary

1. Observational network of Buoys in tropical Oceans and coupled ocn-atmosphere models are used to monitor and predict ENSO

2. There is still room for improvement in ENSO prediction

1. COLA accounts & GrADS Latest version found here:

/usr/local/grads/2.1/grads Copy files in

~kpegion/classes/sp2015/clim713/labs/practice/assignment/

2. Run the GrADS script: plotSSTSEAS.gs

3. Verify that your plot (SSTSEAS.png) looks like the test plot (SSTSEAS.test.png)

In Class Activity:

4. Look at the script plotSSTSEAS.gs – Do you understand what it is doing? (Hint: You can look up GrADS commands at: http://grads.iges.org/grads/gadoc/

gadocindex.html)

5. Modify script to plot SST data from SODAGrADS .ctl files are located in:/data/ccsm4/rean2/monthly/soda/ctl/

6. Modify the script to plot zonal and meridional wind stress (taux and tauy)

For Next Week….

1) Contact Tom for a COLA account if you don’t have one or don’t know how to login

2) If you are new to GrADS, work through the GrADS tutorial

3) Lab #1 (Due at the beginning of class)4) Half page (3-5 sentences) on your project idea

• Does not have to be a well thought out idea; you will have a chance to discuss it, change it, refine it.

• Work related to your dissertation or project in another class is allowed.