MICHAEL A. ALEXANDER, ILEANA BLADE, MATTHEW NEWMAN, JOHN R. LANZANTE

AND NGAR-CHEUNG LAU, JAMES D. SCOTT

Mike Groenke

(Atmospheric Sciences Major)

El Nino-Southern Oscillation (ENSO) Tropical Pacific region Associated sea surface temperature (SST) anomalies Warm=El Nino…Cold=La Nina ENSO events drive ocean SST anomalies around

globe “Atmospheric bridge” because connects the world’s

oceans

Better explanation

http://www.youtube.com/watch?v=IvmeUStFvz8

Q-net: net surface heat flux We=entrainment heat flux Vek=Ekman transport

Wait, why do we care? Essential for prediction of SSTs in tropical

Atlantic Contributes to leading patterns of SSTs on

many times scales around globe Tests ability to simulate global atmospheric

response to ENSO Separate between atmospheric forcing and

ocean feedbacks Influence on marine ecosystems

ENSO Really Matters

Questions that remain Ocean-atmosphere interactions via changes in

solar radiation, precipitation, and boundary layer processes.

Indian Ocean response to ENSO

Feedback from SST anomalies beyond equatorial East Pacific

Purpose of this study

Review of how well we understand the “atmospheric bridge”

Present new data/observations

Focus on Pacific North America (PNA) region

Modeling Used

3 major models were used “Control model” “MLM” or mixed layer model “NP-MLM” or North Pacific mixed layer

model

NCEP-NCAR re-analysis project data also used

Methods Look at observations from past

Interpret data and form hypotheses and assumptions

Run models and look for reproduction of observed data

Interpret results

Main Focus

Global precipitation influences from ENSO

Related SST anomalies on different times scales around the globe

Relationship between SST and SLP

Effects On Global Precip Changes in jet stream

speeds from ENSO

Anomalous clockwise

flow=higher precip

ENSO Felt Around the World

North Pacific

Opposite sign of ENSO

Pacific Decadal Oscillation

influenced by tropical and

extra-tropical forcing

Far north near “sub arctic

front” not correlated

SST AnomaliesSST Anomalies

Current Example

ENSO Felt Around the World Tropical Atlantic:

Warm waters just north of equatorial Atlantic found with El Nino in spring after ENSO peak

Southern Atlantic only weak links plus 3-6 months lag time

Indian OceanWarms with El NinoLag time of 3-6 months, but earlier than AtlanticOften during summer/fall also

Relationship in SLP & SST’s Stronger Aleutian low (by 9mb) during Nino vs. Nina Causes increased westerlies in north Pacific Advects cold air into northern waters and warm air

along west coast of North America Consistent with previous SST map Model differences likely due to error and missing

ocean dynamics

Check out the pressure! Observed MLM Simulation

Shaded areas indicated a 95% statistical significance in difference between taking local coupling effects into account or not

Other ENSO Induced Effects MLD (Mixed Layer Depth)

The depth at which the temperature is 1 degree C cooler than the surface

Salinity Reemergence of SST anomalies

Fades during summer, but effects next winter

Summary Atmospheric response to changes in SST’s due to

ENSO influences conditions across the rest of the globe

This connection is called the “Atmospheric Bridge” Clear link in ENSO SST anomalies and other

anomalies in Northern Pacific, north tropical Atlantic, and Indian Oceans

Atmospheric response affects SLP and jet stream patterns across the globe including deep trough near Alaska

Summary (cont’d) Other impacts include effects on MLD, salinity, and

the reemergence of anomalies during the following year

Changes in net heat flux are the leading driver of SST anomalies in the ENSO region

Ocean-air coupling modifies effects on pressure fields in the North Pacific

My Thoughts

Good review of impacts from El Nino/La Nina events

Too many assumptions that reader knows extremely technical processes

Further research in this field could improve seasonal forecasting

Lacked significant mention of effects from climate change