Indian Monsoon Variability & Climate Change Madhav Khandekar, CANADA Expert Reviewer IPCC 2007 Climate Change September 15, 2015 GWPF UK Presentation 1

Short Abstract An analysis of Indian Summer Monsoon Rainfall (ISMR) reveals that droughts and floods have occurred irregularly throughout a 200-year long excellent dataset with NO Link to “global warming OR climate change” at this point in time. September 15, GWPF UK Presentation

Monsoon: General Notes Indian/Asian monsoon is the largest seasonal abnormality in the global climate system Indian/Asian monsoon affects about 4 billion people of south Asia. Timely arrival and well distributed rainfall during the summer season (May-October) is critical for agriculturally dominated countries of south Asia. Climate models have achieved only a limited success so far in simulating many features of global and regional monsoon. Most climate models project monsoon circulation to intensify in a warmer future climate. In reality, Monsoon circulation has weakened in the last fifty years. September 15, GWPF UK Presentation

Basic Facts on Indian Summer Monsoon 1. Summer (June-September) rains most important for whole of India for agriculture & water supply 2. Mean rainfall ~90 cm; On west coast ( Mumbai-Goa-Kerala Coast)~ cm; central India ~ cm; northwest India ~50 cm 3. Monsoon onset on west coast tip of India ~June 7 th 4. Despite year-to-year variability, this onset date is robust: Over Bay of Bengal & northeast, monsoon arrival ~1-12 June 5. By 25 June, monsoon spreads over most of India September 15, GWPF UK Presentation

Cherapunji GWPF UK Presentation September 15,

Highest/Lowest Rainfall Highest One Year Rainfall: Cherrapunji 2646 cm Aug July 1861 Aug July 1861 Highest One Month Rainfall: Cherrapunji 930 cm July 1861 Highest 2-day Rainfall: 41 in ( ~105 cm) Mumbai July 2005 Lowest seasonal Rainfall: 33mm (1918), 49mm (1899) in West Rajasthan: Both the years ( 1899 &1918 ) were severe drought years over whole of India September 15, GWPF UK Presentation

Seasonal Forecasting Historical Notes Sir Gilbert Walker’s pioneering research on correlation with worldwide weather elements led to first operational forecast issued in Walker’s work was extended to include various regional and worldwide land/ocean parameters. Present seasonal forecasting algorithm includes five or more such parameters. Walker’s work was analyzed by Jacob Bjerknes, who envisaged an east-west circulation in the equatorial vertical plane and named it as “Walker’s Circulation” in GWPF UK Presentation September 15,

Depressions traveling along Monsoon trough Regional controls of Monsoon Low Pressures strengthen westcoast rain Axis of Monsoon trough Western Ghats Western Disturbances GWPF UK Presentation September 15,

Large-scale controls of Indian Monsoon ENSO phase in the equatorial Pacific (El Nino linked to drought) Eurasian snow cover, previous winter (Heavy snow cover weakens monsoon) Equatorial stratospheric wind oscillation (QBO: quasi-biennial oscillation) Indian Ocean Dipole (IOD) These large-scale controls and their various phases, produce major droughts/floods in summer monsoon September 15, GWPF UK Presentation

September 15,

The 1997/98 El Nino structure at about Sep 1997 GWPF UK Presentation September 15,

Eurasian winter snow cover Blanford (1884) first identified adverse impact of heavy winter snow cover on subsequent monsoon rains Sir Gilbert Walker used snow cover as one of the important parameters Barnett et al (1989) simulated snow/monsoon adverse relationship using climate models In general, heavier snow cover produces weaker monsoon and vice-versa September 15, GWPF UK Presentation

A schematic of Indian Ocean Dipole (IOD) Positive phase: warmer SSTs in west equatorial ocean Negative phase: warmer SSTs in east equatorial ocean GWPF UK Presentation September 15,

Quasi-Biennial Oscillation (QBO) at Equatorial Stratosphere GWPF UK Presentation September 15,

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

Decadal and longer-scale variability in Monsoon GWPF UK Presentation September 15,

Indian monsoon exhibits decadal variability and is not influenced by Global Warming at this time Indian Monsoon Rainfall standardized values (Top) Cramer’s t-statistic for 11-year running mean depicting decadal variability and epochs (Bottom) GWPF UK Presentation September 15,

20y running average of summer monsoon showing ~ 60y cycles solar cycles ? GWPF UK Presentation September 15,

Major drought years 1868, 1877, 1899, 1918, 1951, 1972, 1987 Major Flood Years 1892, 1917, 1933, 1961, 1970, 1975 GWPF UK Presentation September 15,

IOD Indian Ocean Dipole Positive phase IOD Indian Ocean Dipole Negative phase Drought Flood Conceptual flow model for drought and flood GWPF UK Presentation September 15,

Recent summer Monsoon performance During Years, 2009, 2010, 2015 GWPF UK Presentation September 15,

Major Drought GWPF UK Presentation September 15,

2010 surplus with flooding in Pakistan GWPF UK Presentation September 15,

Monsoon 2015 Most climate models had projected a major drought by mid-May So far, Monsoon 2015 is below normal BUT NOT A MAJOR DROUGHT Heavy rains in third week of June and later end of July produced localized flooding In Mumbai and in northern States and also in nearby Bangladesh and Myanmar/Burma. Once again, Monsoon has defied model projections GWPF UK Presentation September 15,

GWPF UK Presentation September 15,

Mumbai Suburban Scene June GWPF UK Presentation September 15,

GWPF UK Presentation September 15, Satellite map after cyclone Komen over Bangladesh

Flooding in North India First Week of August 2015 GWPF UK Presentation September 15,

GWPF UK Presentation September 15,

Summary & Conclusions Indian Monsoon is a robust system and its inter-annual variability is governed 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- year period of above/below rainfall. Also a 60-year cycle is identified suggesting a possible SOLAR LINK. 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. 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 weeks or longer. September 15, GWPF UK Presentation