1 Carl Schreck History El Niño/La Niña Climate Modes

2 History El Niño/La Niña Climate Modes

3  Emergency Managers  Raises public awareness  Reinsurance Industry  Companies that insure the companies you buy insurance from  Risk Prediction Initiative (RPI2.0) is a leader in bringing new forecast methods to the industry  Energy Traders  Oil and natural gas drilling in the Gulf is vulnerable  Futures prices respond to the seasonal forecasts History El Niño/La Niña Climate Modes

4  Bill Gray (Colorado State University) discovered the basic hurricane ingredients in the 1960s  Many of those ingredients can be driven by large scale climate modes  Climate modes in winter and springtime can predict hurricane activity for upcoming season History El Niño/La Niña Climate Modes

5  West African Rainfall  Intense rainfall produced stronger easterly waves  Sea level pressure anomaly in Caribbean  Lower = more activity  200 mb zonal wind anomaly in Caribbean  If positive, more vertical wind shear over area, less activity  Tended to persist from spring into hurricane season  ENSO  Warm phase created more wind shear over Atlantic, less TC activity Landsea and Gray (1992, BAMS) History El Niño/La Niña Climate Modes

6  January-March Atlantic SST  March Atlantic SLP  February-March Pacific SLP  ECMWF ENSO forecast History El Niño/La Niña Climate Modes

7  Physics-based dynamical models are getting better at seasonal prediction  Ensembles of these models provide estimate the range of possible outcomes  Generally not as good as statistical forecasts…yet Schemm et al. (2012, CDPW) History El Niño/La Niña Climate Modes

8 History El Niño/La Niña Climate Modes

9  Anomalous low (high) pressure in the western (eastern) Pacific  Stronger than normal trade winds across Pacific  Dry (Wet) conditions in the east (west) Pacific  Deep thermocline in the west – shallow in the east Courtesy of C.C. Hennon, UNC Asheville History El Niño/La Niña Climate Modes

10  Anomalous low (high) pressure in the eastern (western) Pacific  Weak or even reversed trade winds across Pacific  Dry (Wet) conditions in the west (east) Pacific  Deep thermocline in the east – upwelling capped Courtesy of C.C. Hennon, UNC Asheville History El Niño/La Niña Climate Modes

11  Southern Oscillation Index (SOI)  Tracks the see-saw in pressure between western Pacific/Indian Ocean and central Pacific  Uses pressure observations from Tahiti and Darwin, Australia  Sea-surface Temperature (SST) based methods  Average SST anomalies over various regions of the Pacific x Tahiti x Darwin History El Niño/La Niña Climate Modes

12 iri.columbia.edu History El Niño/La Niña Climate Modes

13 cpc.ncep.noaa.gov History El Niño/La Niña Climate Modes

14  Dynamical Models  Starts with the current state of the atmosphere/ocean on a grid  Uses physics approx. to predict its evolution  Statistical Models  Based on current atmospheric and ocean conditions  All models struggle during January–May  “Spring Barrier”  Better forecasts in April through June when conditions are already developing History El Niño/La Niña Climate Modes

15 History El Niño/La Niña Climate Modes

16  Atlantic SSTs vary with a period of 60– 80 years  Hurricane activity follows a similar pattern  Recent warmth is a combination of climate change and the AMO  Thought to be driven by the thermohaline circulation, but we don’t know Trenberth & Shea (2006, GRL) History El Niño/La Niña Climate Modes

17  Dipole of SST between the North and South Atlantic ≈ TNA – TSA  Closely related to the AMO  But AMM has a stronger relationship with Hurricane activity Kossin and Vimont (2007, BAMS) Genesis locations, SST anomalies (shading) and Shear anomalies (contours) AMM loading pattern TNA TSA History El Niño/La Niña Climate Modes

18  Hurricane Ingredient: Conditionally unstable atmosphere  Warm air rises, but only if it’s warmer than its surroundings  Surface temperatures from around the globe get distributed into the atmosphere  Key Climate Change Debate:  Do Hurricanes respond to Total or Relative changes in SST? data.giss.nasa.gov History El Niño/La Niña Climate Modes

19  Sun goes through 11- year cycles in its output  These cycles affect surface temperatures  Not clear how Solar flux would be a better predictor than temperature  But empirical relationships can lead to new discoveries History El Niño/La Niña Climate Modes

20  Based on the locations of high and low pressure centers  Related to variations in the jet stream  Not clear how they affect hurricanes  Variations in shear?  Downstream variations in the Bermuda High? Arctic Oscillation (AO)North Atlantic Oscillation (NAO) East Pacific/North Pacific Oscillation (EPO) Pacific–North American Pattern (PNA) cpc.ncep.noaa.gov History El Niño/La Niña Climate Modes

21 Ingredients Climate Modes Deep Warm Ocean Layer Conditionally Unstable Atmosphere Moist Mid-Troposphere Pre-existing Convection Cyclonic Low-Level Vorticity Weak Vertical Shear El Niño/La Niña MDR Sea Surface Temperature MDR Sea-Level Pressure MDR Vertical Wind Shear Atlantic Multi-decadal Oscillation (AMO) Atlantic Meridional Mode (AMM) Global/Hemispheric Surface Temperature History El Niño/La Niña Climate Modes