Question

1. Describe different mode of climate variability, e.g., El Niño‐Southern Oscillation (ENSO), the Atlantic Multidecadal Oscillation (AMO) and the Pacific Decadal Oscillation (PDO) and their role in changing the magnitude and frequency of natural hazards such as drought and floods.

Answer 1

● The Atlantic Multi-decadal Oscillation (AMO) has been identified as a mode of natural variability occurring in the North Atlantic Ocean with an approximately calculated period of 60-80 years.

● The Pacific Decadal Oscillation (PDO) is a robust, recurring pattern of ocean-climate variability located over the mid-latitude Pacific basin.The PDO is detected as warm or cool surface waters in the Pacific Ocean, north of 20°N.

● El Niño Southern Oscillation (ENSO) is an periodic variation in winds and sea surface temperatures over the tropical eastern Pacific Ocean, affecting the climate of much of the tropics and subtropics.

The warming phase of the sea temperature is known as El Niño and the cooling phase as La Niña.

Their role in drought and floods:-

● The drought and floods are mainly based on (ENSO), (AMO) and (PDO) climte variables, so according to regional historical rainfall which causes floods and drought index relationships with each oscillation and combination of oscillations were statistically evaluated.

We got that the impact of ENSO fluctuation is limited to short-period rainfall variability, whereas long-period influence is from AMO and PDO.

So the magnitude and frequency of natural hazards such as drought and floods have more chances to occurr in AMO & PDO with comparison to the ENSO.

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