BASICS OF EL NIÑO- SOUTHERN OSCILLATION (ENSO) Ernesto R. Verceles PAGASA

WHAT IS EL NIÑO ? Common notions: “El Niño means no water in faucets and showers” “El Niño means no planting for the season or two” These are partially true… these are all impacts of the EL NIÑO One newspaper headline: PAGASA insists El Niño already in RP - Despite heavy rains and typhoons (Panay News dated 13 January 2005) “El Niño means severe drought”

WHAT IS EL NIÑO (LA NIÑA)? El Niño (La Niña) is a condition in the Pacific ocean and characterized by the cyclic warming (cooling) of the central and eastern equatorial Pacific (CEEP). Observed Sea Surface Temperature Analyzed Sea Surface Temperature EL NIÑO LA NIÑA Lower temp Higher temp Cooler temp Warmer temp CEEP warming CEEP cooling

Monthly observation and analysis of OCEAN SURFACE during El Niño and La Niña El Nino 1997 started in March La Nina 1998 started in July

Monthly observation and analysis of OCEAN DEPTH (~300 meters) during El Niño and La Niña ASIAAUSTRALIA North and South AMERICA El Nino 1997 started in March La Nina 1998 started in July

MEASURING OCEAN PARAMETERS

THE NIÑO REGIONS

Sample Data for NIÑO REGIONS

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

Southern Oscillation is the atmospheric component of ENSO and measured in terms of the difference in standardized pressure anomalies over Tahiti and Darwin, and wind anomaly at low level winds (850 mbs level). WHAT IS SOUTHERN OSCILLATION ? EL NIÑO CONDITION LA NIÑA CONDITION Australia HLHL

COMBINED EFFECT OF EL NIÑO-SOUTHERN OSCILLATION (ENSO) IN THE TROPICAL PACIFIC GLOBAL IMPACT OF EL NIÑO-SOUTHERN OSCILLATION (ENSO) EL NIÑO LA NIÑA EL NIÑO LA NIÑA

IMPACTS OF ENSO and NON-ENSO ON PHILIPPINE ANNUAL RAINFALL RED colored years are EL NINO years, Legend: Potential Areas Under Severe drought impacts Drought impacts with major losses Moderate drought impacts Near normal to above normal condition Way above normal condition Flood damage Severe flood damage BLUE colored years are LA NINA years and BLACK colored years are NON_ENSO years

During El Niño EpisodeDuring La Niña Episode  Drier weather conditionsWetter weather conditions Initial results of diagnostic and statistical studies on general 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 rainfall Near-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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