BASICS OF BASICS OF EL NIÑO-EL NIÑO-

SOUTHERN SOUTHERN OSCILLATION OSCILLATION

(ENSO)(ENSO)

Ernesto R. VercelesErnesto R. Verceles

PAGASAPAGASA

WHAT IS EL NIÑO ?WHAT IS EL NIÑO ?

Common notions:Common notions:

““El Niño means no water in faucets and El Niño means no water in faucets and showers”showers”““El Niño means no planting for the El Niño means no planting for the season or two”season or two”

These are partially true… these are all These are partially true… these are all impactsimpacts of the of the EL NIÑOEL NIÑO

One newspaper headline: PAGASA insists El One newspaper headline: PAGASA insists El Niño already in RP - Despite heavy rains and Niño already in RP - Despite heavy rains and typhoons typhoons (Panay News dated 13 January 2005)(Panay News dated 13 January 2005)

““El Niño means severe El Niño means severe drought”drought”

WHAT ISWHAT IS EL NIÑO EL NIÑO ((LA NIÑALA NIÑA)?)?El Niño (La Niña) is a condition in the Pacific El Niño (La Niña) is a condition in the Pacific ocean and characterized by the cyclic warming ocean and characterized by the cyclic warming (cooling) of the central and eastern equatorial (cooling) of the central and eastern equatorial Pacific (CEEP). Pacific (CEEP).

Observed Observed Sea Surface Sea Surface TemperaturTemperatur

ee

Analyzed Analyzed Sea Surface Sea Surface TemperaturTemperatur

ee

EL EL NIÑONIÑO

LA LA NIÑANIÑA

LoweLower r

temptemp

LoweLower r

temptemp

HigheHigher r

temptemp

HigheHigher r

temptemp

CooleCooler r

temptemp

CooleCooler r

temptemp

WarmeWarmer tempr temp

WarmeWarmer tempr temp

CEEP warmingCEEP warming CEEP coolingCEEP cooling

Monthly Monthly observation observation and analysis of and analysis of OCEAN OCEAN SURFACE SURFACE during El Niño during El Niño 1997-98 and La 1997-98 and La Niña 1998-99Niña 1998-99

El Nino 1997 started in El Nino 1997 started in MarchMarch

La Nina 1998 started in La Nina 1998 started in JulyJuly

Monthly Monthly observation observation and analysis and analysis of OCEAN of OCEAN DEPTH (~300 DEPTH (~300 meters) meters) during El during El Niño 1997-98 Niño 1997-98 and La Niña and La Niña 1998-991998-99

ASIAASIA

AUSTRALIAAUSTRALIA

North and North and South South

AMERICAAMERICA

El Nino 1997 El Nino 1997 started in Marchstarted in March

La Nina 1998 La Nina 1998 started in Julystarted in July

MEASURING OCEAN PARAMETERSMEASURING OCEAN PARAMETERS

THE NIÑO REGIONSTHE NIÑO REGIONS

                                                                                                      

                                                                                                                                                                                               

Sample Data for NIÑO REGIONSSample Data for NIÑO REGIONS

Thus, Thus, “EL NIÑO” is a condition in the “EL NIÑO” is a condition in the central and eastern equatorial Pacific central and eastern equatorial Pacific OceanOcean where unusual warming is where unusual warming is occurring. (Note that the occurring. (Note that the formation/development of El Niño is formation/development of El Niño is very far from the countryvery far from the country.. ).. )Then, why is it affecting the Then, why is it affecting the philippines.. philippines.. The answer lies in the atmosphere…The answer lies in the atmosphere…

The phenomenon is called The phenomenon is called SOUTHERN OSCILLATION…SOUTHERN OSCILLATION…

Southern Oscillation is the atmospheric Southern Oscillation is the atmospheric component of ENSO and measured in terms of the component of ENSO and measured in terms of the difference in standardized pressure anomalies difference in standardized pressure anomalies over Tahiti and Darwin, and wind anomaly at low over Tahiti and Darwin, and wind anomaly at low level winds (850 mbs level). level winds (850 mbs level).

WHAT IS SOUTHERN WHAT IS SOUTHERN OSCILLATION ?OSCILLATION ?

EL NIÑO CONDITIONEL NIÑO CONDITION LA NIÑA CONDITIONLA NIÑA CONDITION

Australia

HH LL HHLL

Australia

 

COMBINED EFFECT OF EL NIÑO-SOUTHERN COMBINED EFFECT OF EL NIÑO-SOUTHERN OSCILLATION (ENSO) IN THE TROPICAL PACIFICOSCILLATION (ENSO) IN THE TROPICAL PACIFIC

GLOBAL IMPACT OF EL NIÑO-SOUTHERN GLOBAL IMPACT OF EL NIÑO-SOUTHERN OSCILLATION (ENSO)OSCILLATION (ENSO)

EL NIÑOEL NIÑO LA NIÑALA NIÑA

EL NIÑOEL NIÑO LA NIÑALA NIÑA

IMPACTS OF ENSO and NON-ENSO ON IMPACTS OF ENSO and NON-ENSO ON PHILIPPINE ANNUAL RAINFALLPHILIPPINE ANNUAL RAINFALL

REDRED colored years arecolored years are EL NINOEL NINO years, years,

Legend: Legend: Potential Areas Potential Areas Under Under Severe drought Severe drought impactsimpacts

Drought Drought impacts with impacts with major lossesmajor lossesModerate Moderate drought drought impactsimpactsNear normal to Near normal to above normal above normal conditioncondition

Way above Way above normal normal conditionconditionFlood damageFlood damage

Severe flood Severe flood damagedamage

BLUEBLUE colored years are colored years are LA NINALA NINA yearsyearsand and BLACKBLACK colored years are colored years are NON_ENSONON_ENSO

yearsyears

During El Niño Episode During La Niña Episode 

               

Drier weather conditions

Wetter weather conditions

Initial results of diagnostic and statistical studies on Initial results of diagnostic and statistical studies on general influences of ENSO on Philippine climategeneral influences of ENSO on Philippine climate

Weak monsoon activity

Weak tropical cyclones activity

Below normal rainfall

Above normal air temperatures

- occurrence of isolated heavy rainfall in short duration

- delayed onset of the rainy season- early termination of the rainy season

- tropical cyclones follow tracks further off the Philippines

- less number of tropical cyclones entering the Philippine Area of Responsibility (PAR)

Above normal rainfallNear-to-below normal air temperatures

Moderate to Strong tropical cyclones activity

Moderate to strong monsoon activity

- increased cloudiness and widespread rains

- near normal cyclone tracks (near and/or crossing the country)

- near normal to early onset of the rainy season

- near-to-above normal cyclone occurrences in the PAR- rain-effective cyclones

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