PG

Prajnanandan GiriAIR 24

Question 17GS1GS1

The Indian monsoon complex phenomenon influenced by various climatic factors. Critically examine the role of oceanic and atmospheric factors in determining the intensity and distribution of monsoon rainfall in India.

Open scan (p.41)

Introduction

Indian monsoon is the seasonal reversal of trade winds that brings rainfall over south Asia region through south-west monsoon and north-east monsoon.

22 words

Main Body

It is a complex phenomenon due to involvement of multiple variable factors of ocean and atmosphere.

Role of oceanic factors:

1. Mascrenes highPresence of high pressure over Madagascar region of Indian oceanpushes SW monsoon.
2. Indian ocean dipole(IOD)Positive IOD (warmer West Indian ocean) helps in more rainfall over India and opposite in negative IOD.

3. ENSO - or El-Nino Southern Oscillation over south equatorial pacific ocean impact monsoon.

[E.g] El-Ninohigher oceanic temp over Peru coastLow monsoon rainfall.
La-Ninahigh temperature over AustraliaHigh monsoon rainfall.

4. Other oceanic factors like:

(i) Pacific decadal oscillation

(ii) Eurasian snow cover

Also impact monsoon in complex way.

Role of atmospheric factors:

1. Somali Jet stream, Eastern Tropical Jet stream as well as Sub-tropical polar jetstream influence or intensity of monsoon.

2. Malan-Julian oscillationeastward moving moisture-laden wind on Indian oceanPresence over North Indian ocean in monsoonHigher rainfall
2. Western disturbancesImpacts rainfall intensity over north India.

[E.g] Recent Yamuna flood due to mix convergence of WD and SW monsoon.

4. Similarly, formation of cyclones, also impact onset and movement of monsoon.

[E.g] Cyclone Nisarga - delayed monsoon

However, apart from ocean & atmosphere, the topography also decides the intensity of monsoon by shaping the direction of the wind and with lee-ward / wind-ward effect in orography rainfall.

232 words14 paragraphs

Topper

Prajnanandan Giri

AIR 24

Subject & Paper

GS1GS1

Topic

Salient features of World's Physical Geography

Indian Monsoon System

Oceanic and atmospheric factors in monsoon

Writing Stats

254

Total words

14

Paragraphs

analytical and technical

Tone