EL NINO LA NINA ENSO AND SEASONAL WEATHER

EL NINO, LA NINA, ENSO AND SEASONAL WEATHER PRESENTED TO: SMYRNA YACHT CLUB - FEBRUARY 4, 2016 DR. CHRIS HERBSTER METEOROLOGY PROGRAM EMBRY-RIDDLE AERONAUTICAL UNIVERSITY HERBSTEC@ERAU. EDU http: //wx. erau. edu/faculty/herbster/demo/presentations/

OVERVIEW • A LITTLE ABOUT ME • WHY DO WE HAVE WEATHER? • WHAT ARE NORMAL CONDITIONS? • WHAT ARE EL NINO AND LA NINA? • WHAT ARE THE CURRENT CONDITIONS? • WHAT DOES THIS MEAN FOR CENTRAL FLORIDA, AND THE REST OF THE U. S. ?

A LITTLE ABOUT ME • GREW UP SAILING OUT OF RYE NY, ON LONG ISLAND SOUND • STARTED IN ENGINEERING AT UNIV. OF MICH. • B. S. ATMOSPHERIC SCIENCE FROM SUNY STONY BROOK • M. S. AND PHD IN METEOROLOGY FROM FLORIDA STATE UNIVERSITY • MS – MARINE BOUNDARY LAYER TURBULENT FLUX STUDY • PHD – OBSERVATIONAL AND MODELING STUDY OF THE FL SEA BREEZE

WHY DO WE HAVE “WEATHER? ” • WHAT YOU AND I CALL “WEATHER” (THAT IS, THOSE TIMES WHEN THE SKY IS NOT CLEAR AND/OR THE WIND IS NOT CALM) IS THE RESPONSE THAT IS SET INTO MOTION BY AN ENERGY IMBALANCE. • WHEN THE WEATHER IS THUNDERSTORMS, THE IMBALANCE IS DOMINATED IN THE VERTICAL DIRECTION. • WHEN THE WEATHER IS ASSOCIATED WITH LARGE REGIONS OF WARM AND COLD AIR, THEN THE IMBALANCE IS LARGELY HORIZONTAL. • THIS IS MORE COMMON IN THE WINTER SEASON, THAN IN SUMMER. • SPRING AND FALL HAVE LESS CONTRAST THAN WINTER, AND GENERALLY WEAKER EVENTS, BUT THESE ARE TRANSITION SEASONS WHICH MAY HAVE BIG EVENTS TOO. • THE JET STREAM IS CREATED/INFLUENCED BY GREATER CONTRAST DURING THE PERIOD BEING OBSERVED. • STRONGEST IN WINTER, LESS DEFINED IN SUMMER.

ANNUAL ENERGY BUDGET • TROPICS EXPERIENCE A NET SURPLUS OF ENERGY (I. E. NET WARMING) • POLES EXPERIENCE A NET DEFICIT (I. E. NET COOLING) • ENERGY TRANSPORT FROM TROPICS TO POLES IS REQUIRED

PLANETARY HEAT TRANSPORT • OCEAN CURRENTS – TRANSPORT HUGE QUANTITIES OF WARM WATER POLE WARD AND COLD WATER TOWARD THE EQUATOR. (~⅓ OF TOTAL) • NORTH/SOUTH WINDS – ADVECTIVE TRANSPORT OF WARM AND COLD AIR INTO NEW (CONTRASTING) REGIONS. (~⅓ OF TOTAL) • LATENT HEAT EXCHANGES – ENERGY LOSS FOR SURFACE DUE TO EVAPORATION AND GAIN FOR THE ATMOSPHERE DUE TO CONDENSATION. (~⅓ OF TOTAL)

AVERAGE PLANETARY-SCALE CIRCULATIONS

FLORIDA SEA BREEZE DUE TO LOCAL CONTRASTS A local contrast in temperature creates motions that lead to the upward transport of energy away from the warm surface.

HORIZONTAL CONTRAST CREATES THE JET STREAM

LARGE SCALE TEMPERATURE CONTRAST Cold Air Warm Air

ATMOSPHERIC CIRCULATIONS

PACIFIC OCEAN INFLUENCE • THE PACIFIC OCEAN PLAYS AN IMPORTANT ROLE IN SHAPING THE WEATHER THAT IS EXPERIENCED ACROSS ALL OF THE CONUS, AS WELL AS ALASKA, AND ULTIMATELY EVERYWHERE ELSE AROUND THE WORLD. • THE OCEAN [SEA] SURFACE TEMPERATURE (SST) CAN VARY BY QUITE A FEW DEGREES BETWEEN A COLD EVENT COMPARED WITH A WARM EVENT, BUT EVEN JUST A FEW DEGREE CHANGE IN SST CAN HAVE A VERY LARGE EFFECT ON WEATHER.

NON EL NIÑO YEARS = NORMAL = “LA NADA” • COLDER WATER IS NORMALLY FOUND IN THE EASTERN TROPICAL PACIFIC COMPARED WITH THE WESTERN SIDE OF THE BASIN • THE NORMAL EASTERLY TRADE WINDS OF THE TROPICS DRAG THE SURFACE WATERS OF THE EASTERN PACIFIC AWAY FROM THE COASTLINES OF THE AMERICAS. • UPWELLING IN THE EASTERN PACIFIC BRINGS COLDER WATER UP FROM DEEPER LEVELS TO REPLACE THE SURFACE WATER THAT HAS BEEN DRAGGED AWAY • THIS NORMALLY COLD WATER IS NUTRIENT RICH AND FULL OF MARINE LIFE (ESPECIALLY ANCHOVIES) http: //www. cpc. noaa. gov/products/analysis_monitoring/ensocycle/means st. gif

PACIFIC OCEAN SST AND SST ANOMALIES

EL NIÑO AND LA NIÑA EL NINO OCCURS WHEN PACIFIC OCEAN WATERS NEAR THE EQUATOR ARE WARMER THAN NORMAL (LEFT) LA NINA OCCURS WHEN PACIFIC OCEAN WATERS NEAR THE EQUATOR ARE COLDER THAN NORMAL (RIGHT) THESE CONTRASTS FROM NORMAL RESULT IN SHIFTS IN THE JET STREAMS AND STORM TRACKS. El Niño - SST warmer than normal La Niña - SST colder than normal http: //www. cpc. noaa. gov/products/precip/CWlink/

WHAT’S NORMAL? • THE TRADE WINDS ACCUMULATE WARM SURFACE WATER AROUND INDONESIA, RAISING THE SEA LEVEL ROUGHLY HALF A METER HIGHER IN THE WESTERN PACIFIC. • AS UPWELLING PERSISTS, THE LEVEL OF THERMOCLINE RISES TO SHALLOWER DEPTHS OFF THE SOUTH AMERICAN COAST AND IS DEPRESSED IN THE WESTERN PACIFIC. • THE UPWELLED WATER IS RICH IN NUTRIENTS AND SUPPORTS AN ABUNDANCE OF FISH AND MARINE LIFE. • AS SURFACE WATER PROPAGATES WESTWARD, IT IS HEATED BY THE ATMOSPHERE AND THE SUN, ALLOWING WARMER WATERS TO ACCUMULATE IN THE WESTERN PACIFIC. • THE COOLER WATER IN THE EASTERN PACIFIC COOLS THE AIR ABOVE IT, AND CONSEQUENTLY THE AIR BECOMES TOO DENSE TO RISE AND PRODUCE CLOUDS AND RAIN. • IN THE WESTERN PACIFIC HOWEVER, THE OVERLYING AIR IS HEATED BY THE WARMER WATERS BELOW, DESTABILIZING THE LOWER ATMOSPHERE AND INCREASING THE LIKELIHOOD OF PRECIPITATION

El Nino and the Southern Oscillation

La Niña (Index > 0. 5 o. C for at least 5 consecutive months) Neutral (Index between 0. 5 o. C and -0. 5 o. C) El Niño (Index < -0. 5 o. C for at least 5 consecutive months) http: //www. bom. gov. au/lam/Students_Teachers/elnanim/elani. shtml

How an El Nino Episode Happens • EVERY FEW YEARS, THE PRESSURE PATTERN BREAKS DOWN SURFACE PRESSURE RISES OVER THE WESTERN PACIFIC AND FALLS OVER THE EASTERN PACIFIC • TRADE WINDS REVERSE, WARM WATER HEADS EASTWARD VIA A KELVIN WAVE • THE ATMOSPHERIC PRESSURE REVERSAL IS CALLED THE SOUTHERN OSCILLATION • SINCE THE ATMOSPHERIC PRESSURE REVERSAL AND OCEAN WARMING ARE SIMULTANEOUS, IT IS CALLED EL-NINO-SOUTHERN OSCILLATION (ENSO) • CONDITIONS OPPOSITE OF EL NINO ARE CALLED LA NINA • ANOMALOUSLY HIGH PRESSURE AND COLD WATER IN EASTERN PACIFIC • ANOMALOUSLY LOW PRESSURE AND WARM WATER IN EASTERN PACIFIC

El Nino Formation A WARM WATER KELVIN WAVE MOVING EASTWARD OVER THE TROPICAL PACIFIC DURING THE STRONG EL-NINO OF 1997

El Nino and the Southern Oscillation

Typical winter weather patterns under El Niño and La Niña conditions

El Nino and La Nina Formation LA NINA FORMATION EL NINO FORMATION

El Nino vs. La Nina EL-NINO (RED) VS. LA NINA (BLUE) Source: NOAA/ESRL

AN OBSERVED KELVIN WAVE HINTS AT A SIGNIFICANT EL NINO • OVER THE FIRST QUARTER OF 2014 A LARGE WAVE OF SUBSURFACE WARM WATER TRAVELED ACROSS THE PACIFIC OCEAN. SUGGESTING AN EL NINO EVENT WAS COMING • THIS HAS BEEN OBSERVED JUST PRIOR TO OTHER SIGNIFICANT EVENTS IN THE PAST.

The next several slides contain information taken from the Climate Prediction Center’s Weekly ENSO Briefing http: //www. cpc. ncep. noaa. gov/products/analysis_monitoring/enso_advisory/index. shtml

NIÑO REGION SST DEPARTURES (OC) RECENT EVOLUTION The latest weekly SST departures are: Niño 4 3 1+2 1. 5ºC 2. 3ºC 1. 0ºC

Global SST Departures from Normal (o. C) During the last four weeks, tropical SSTs were above average across most of the Pacific.

Global SST Departures from Normal (o. C) During the last four weeks, tropical SSTs were above average across the most of the Pacific and the Indian Ocean.

Atmospheric Circulation over the North Pacific & North America the Last 60 Days 925 -h. Pa. During Temp. Anom. During December, above-average temperatures dominated over the East and near-to-below average temperatures were observed over the West. Since January, the Pacific jet stream has extended eastward and strengthened. Over North America during the last half of January, an anomalous trough over the eastern U. S. contributed to below-average temperatures, while temperatures remained above-average across Alaska and most of Canada.

U. S. TEMPERATURE AND PRECIPITATION DEPARTURES DURING THE LAST 30 DAYS End Date: 30 January 2016 Percent of Average Precipitation Temperature Departures (degree C)

WHAT DOES THIS MEAN FOR CENTRAL FLORIDA? • THE FOLLOWING SLIDES DESCRIBE A LITTLE OF WHAT WE HAVE BEEN EXPERIENCING, • WHAT IS TYPICAL OF EL NINO CONDITIONS IN THE PAST, • AND WHAT IS FORECASTED OVER THE NEXT FEW MONTHS.

Found at: http: //www. srh. noaa. gov/mlb/? n=cligraph_2015

U. S. SEASONAL OUTLOOKS FEBRUARY – APRIL 2016 The seasonal outlooks combine the effects of long-term trends, soil moisture, and, when appropriate, ENSO.

FINAL THOUGHTS • WHEN THE PACIFIC OCEAN IS DIFFERENT FROM AVERAGE, THE WEATHER CAN BE PREDICTABLY DIFFERENT FROM AVERAGE • EL NINO TENDS TO INCREASE THE INFLUENCE OF WESTERLY WINDS OVER FLORIDA AND THE TROPICS. • THIS CAN IMPEDE HURRICANE FORMATION, OR KEEP THEM EAST OF THE U. S. IF THEY FORM IN THE WARM SEASON. • LA NINA TENDS TO REDUCE THE INFLUENCE OF WESTERLY WINDS OVER FLORIDA AND THE TROPICS. • THIS CAN MAKE HURRICANE FORMATION MORE FAVORABLE, OR ALLOW THEM TO MOVE CLOSER TO NORTH AMERICA IF THEY FORM IN SUMMER. • ENSO CAN INFLUENCE WEATHER PATTERNS ALL ACROSS THE PLANET, AS A SHIFT OF FEATURES IN ONE LOCATION IS