indian monsoon variability & climate change madhav khandekar, canada expert reviewer ipcc 2007...

Indian Monsoon Variability & Indian Monsoon Variability & Climate ChangeClimate Change

Madhav Khandekar, CANADAMadhav Khandekar, CANADA

Expert Reviewer IPCC 2007 Climate Expert Reviewer IPCC 2007 Climate Change Change

September 15, 2015September 15, 2015 GWPF UK PresentationGWPF UK Presentation11

Short AbstractShort Abstract

An analysis of Indian Summer Monsoon An analysis of Indian Summer Monsoon Rainfall (ISMR) reveals that droughts Rainfall (ISMR) reveals that droughts and floods have occurred irregularly and floods have occurred irregularly throughout a 200-year long excellent throughout a 200-year long excellent dataset with NO Link to “global dataset with NO Link to “global warming OR climate change” at this warming OR climate change” at this point in time.point in time.

September 15, 2015September 15, 201522GWPF UK PresentationGWPF UK Presentation

Monsoon: General NotesMonsoon: General Notes

Indian/Asian monsoon is the largest seasonal abnormality in Indian/Asian monsoon is the largest seasonal abnormality in the global climate systemthe global climate system

Indian/Asian monsoon affects about 4 billion people of south Indian/Asian monsoon affects about 4 billion people of south Asia. Timely arrival and well distributed rainfall during the Asia. Timely arrival and well distributed rainfall during the summer season (May-October) is critical for agriculturally summer season (May-October) is critical for agriculturally dominated countries of south Asia.dominated countries of south Asia.

Climate models have achieved only a limited success so far in Climate models have achieved only a limited success so far in simulating many features of global and regional monsoon. simulating many features of global and regional monsoon. Most climate models project monsoon circulation to intensify Most climate models project monsoon circulation to intensify in a warmer future climate. In reality, Monsoon circulation has in a warmer future climate. In reality, Monsoon circulation has weakened in the last fifty years. weakened in the last fifty years.


Basic Facts on Indian Summer Basic Facts on Indian Summer Monsoon Monsoon

1.1. Summer (June-September) rains most important for Summer (June-September) rains most important for whole of India for agriculture & water supplywhole of India for agriculture & water supply

2.2. Mean rainfall ~90 cm; On west coast ( Mumbai-Goa-Mean rainfall ~90 cm; On west coast ( Mumbai-Goa-Kerala Coast)~ 150-200 cm; central India ~100-125 cm; Kerala Coast)~ 150-200 cm; central India ~100-125 cm; northwest India ~50 cmnorthwest India ~50 cm

3.3. Monsoon onset on west coast tip of India ~June 7Monsoon onset on west coast tip of India ~June 7thth

4.4. Despite year-to-year variability, this onset date is robust: Despite year-to-year variability, this onset date is robust: Over Bay of Bengal & northeast, monsoon arrival ~1-12 Over Bay of Bengal & northeast, monsoon arrival ~1-12 JuneJune

5.5. By 25 June, monsoon spreads over most of India By 25 June, monsoon spreads over most of India


Cherapunji

GWPF UK PresentationGWPF UK PresentationSeptember 15, 2015September 15, 2015 55

Highest/Lowest RainfallHighest/Lowest Rainfall

Highest One Year Rainfall: Cherrapunji 2646 cmHighest One Year Rainfall: Cherrapunji 2646 cm Aug 1860- July 1861Aug 1860- July 1861

Highest One Month Rainfall: Cherrapunji 930 cm Highest One Month Rainfall: Cherrapunji 930 cm July 1861July 1861

Highest 2-day Rainfall: 41 in ( ~105 cm) Mumbai Highest 2-day Rainfall: 41 in ( ~105 cm) Mumbai July 2005July 2005

Lowest seasonal Rainfall: 33mm (1918), 49mm (1899) in West Lowest seasonal Rainfall: 33mm (1918), 49mm (1899) in West Rajasthan: Both the years ( 1899 &1918 ) were severe drought years Rajasthan: Both the years ( 1899 &1918 ) were severe drought years over whole of Indiaover whole of India


Seasonal Forecasting Seasonal Forecasting Historical NotesHistorical Notes

Sir Gilbert Walker’s pioneering research on correlation with Sir Gilbert Walker’s pioneering research on correlation with worldwide weather elements led to first operational forecast worldwide weather elements led to first operational forecast issued in 1906. issued in 1906.

Walker’s work was extended to include various regional and Walker’s work was extended to include various regional and worldwide land/ocean parameters. Present seasonal worldwide land/ocean parameters. Present seasonal forecasting algorithm includes five or more such parameters.forecasting algorithm includes five or more such parameters.

Walker’s work was analyzed by Jacob Bjerknes, who Walker’s work was analyzed by Jacob Bjerknes, who envisaged an east-west circulation in the equatorial vertical envisaged an east-west circulation in the equatorial vertical plane and named it as “Walker’s Circulation” in 1969. plane and named it as “Walker’s Circulation” in 1969.


Depressions traveling along Monsoon trough

Regional controls of Monsoon

Low Pre

ssure

s strength

en w

estcoast rain

Axis of Monsoon trough

Weste

rn G

hats

Western Disturbances


Large-scale controls of Indian Large-scale controls of Indian MonsoonMonsoon

ENSO phase in the equatorial Pacific (El Nino linked to ENSO phase in the equatorial Pacific (El Nino linked to drought)drought)

Eurasian snow cover, previous winter (Heavy snow cover Eurasian snow cover, previous winter (Heavy snow cover weakens monsoon)weakens monsoon)

Equatorial stratospheric wind oscillation (QBO: quasi-biennial Equatorial stratospheric wind oscillation (QBO: quasi-biennial oscillation)oscillation)

Indian Ocean Dipole (IOD)Indian Ocean Dipole (IOD)

These large-scale controls and their various phases, produce These large-scale controls and their various phases, produce major droughts/floods in summer monsoon major droughts/floods in summer monsoon


The 1997/98 El Nino structure at about Sep 1997


Eurasian winter snow coverEurasian winter snow cover

Blanford (1884) first identified adverse impact of Blanford (1884) first identified adverse impact of heavy winter snow cover on subsequent monsoon heavy winter snow cover on subsequent monsoon rainsrainsSir Gilbert Walker used snow cover as one of the Sir Gilbert Walker used snow cover as one of the important parametersimportant parameters

Barnett et al (1989) simulated snow/monsoon Barnett et al (1989) simulated snow/monsoon adverse relationship using climate modelsadverse relationship using climate modelsIn general, heavier snow cover produces weaker In general, heavier snow cover produces weaker monsoon and vice-versamonsoon and vice-versa


A schematic of Indian Ocean Dipole (IOD)Positive phase: warmer SSTs in west equatorial oceanNegative phase: warmer SSTs in east equatorial ocean GWPF UK PresentationGWPF UK PresentationSeptember 15, 2015September 15, 2015 1313

Quasi-Biennial Oscillation (QBO) at Equatorial Stratosphere


This jet (peak winds ~100 knots at 15 km level) is due to reversal of north-south temperature gradient. The jet disappears by October.


Decadal and longer-scale variability in Monsoon


Indian monsoon exhibits decadal variability and is not influenced by Global Warming at this time

Indian Monsoon Rainfall standardized values 1871-2001 (Top)Cramer’s t-statistic for 11-year running mean depicting decadalvariability and epochs (Bottom)


20y running average of summer monsoon showing ~ 60y cycles

solar cycles ? GWPF UK PresentationGWPF UK PresentationSeptember 15, 2015September 15, 2015 1818

Major drought years 1868, 1877, 1899, 1918, 1951, 1972, 1987

Major Flood Years 1892, 1917, 1933, 1961, 1970, 1975


IOD Indian Ocean DipolePositive phase

IOD Indian Ocean DipoleNegative phase

Drought

Flood

Conceptual flow model for drought and flood


Recent summer Monsoon performance

During Years, 2009, 2010, 2015


Major Drought


2010 surplus with flooding in Pakistan


Monsoon 2015Monsoon 2015Most climate models had projected a major drought by mid-Most climate models had projected a major drought by mid-May 2015. May 2015.

So far, Monsoon 2015 is below normal BUT NOT A MAJOR So far, Monsoon 2015 is below normal BUT NOT A MAJOR DROUGHTDROUGHT

Heavy rains in third week of June and later end of July Heavy rains in third week of June and later end of July produced localized floodingproduced localized flooding

In Mumbai and in northern States and also in nearby In Mumbai and in northern States and also in nearby Bangladesh and Myanmar/Burma. Bangladesh and Myanmar/Burma.

Once again, Monsoon has defied model projections Once again, Monsoon has defied model projections


Mumbai Suburban Scene June 23-24 2015GWPF UK PresentationGWPF UK Presentation

September 15, 2015September 15, 2015 2626


Satellite map after cyclone Komen over Bangladesh

Flooding in North India First Week of August 2015


Summary & ConclusionsSummary & ConclusionsIndian Monsoon is a robust system and its inter-annual variability is governed Indian Monsoon is a robust system and its inter-annual variability is governed by large-scale atmosphere-ocean patterns.by large-scale atmosphere-ocean patterns.

Droughts/floods have occurred irregularly throughout a 200-year long dataset.Droughts/floods have occurred irregularly throughout a 200-year long dataset.

Indian Monsoon appears to exhibit a decadal variability with approximately 30-Indian Monsoon appears to exhibit a decadal variability with approximately 30-year period of above/below rainfall. Also a 60-year cycle is identified suggesting year period of above/below rainfall. Also a 60-year cycle is identified suggesting a possible SOLAR LINK.a possible SOLAR LINK.

Indian monsoon is NOT impacted by ‘Global Warming’ or climate change. Indian Indian monsoon is NOT impacted by ‘Global Warming’ or climate change. Indian and global monsoon circulations have weakened in the last 30 to 50 years. and global monsoon circulations have weakened in the last 30 to 50 years.

A conceptual flow model of Indian Monsoon based on selected large-scale A conceptual flow model of Indian Monsoon based on selected large-scale indices can help predict Monsoon droughts and floods with a lead time of few indices can help predict Monsoon droughts and floods with a lead time of few weeks or longer.weeks or longer.


indian monsoon variability & climate change madhav khandekar, canada expert reviewer ipcc 2007...

Documents

monsoon arrival

regional monsoon

monsoon spreads

indian summer monsoon

year rainfall

distributed rainfall

month rainfall

day rainfall