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K. Krishna Kumar CIRES Visiting Fellow ( kkrishna@colorado.edu ). Asian Monsoon…. Outline. Monsoon Mechanisms Scales of Variability MONSOON-ENSO links and some plausible explanations of recent weakening Empirical/Dynamical Prediction of Monsoon Rainfall. Monsoons.
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K. Krishna Kumar CIRES Visiting Fellow (kkrishna@colorado.edu) Asian Monsoon… Hydro-Climate Course March 2004, CU, Boulder
Outline • Monsoon Mechanisms Scales of Variability • MONSOON-ENSO links and some plausible explanations of recent weakening • Empirical/Dynamical Prediction of Monsoon Rainfall Hydro-Climate Course March 2004, CU, Boulder
Monsoons The term ‘MONSOON’ is derived from the Arabic word ‘mausim’, which means season.. Since early times, the term monsoon has been used to signify any annual climate cycle with a dominant seasonal wind reversal. Ramage’s (1971) criteria to delineate the monsoon areas of the world: • Prevailing wind direction shifts by at least 120º between Jan and July • Average frequency of prevailing wind direction in Jan and July exceeds 40% • Mean resultant wind in at least one of the months exceeds 3 m/s Hydro-Climate Course March 2004, CU, Boulder
Global Monsoons(after C.S. Ramage, 1971) Hydro-Climate Course March 2004, CU, Boulder
Schematic of Winter (NE) and Summer (SW) Monsoons over Asia Hydro-Climate Course March 2004, CU, Boulder
Sea Level Pressure and Wind Distribution during January and July in the Tropics Hydro-Climate Course March 2004, CU, Boulder
Migration of Tropical Rain belts from Austral Summer to Boreal Summer Hydro-Climate Course March 2004, CU, Boulder
Monsoon –A Gigantic Land-Sea Breeze Hydro-Climate Course March 2004, CU, Boulder
Role of Mountains and the Orography on Monsoons Hydro-Climate Course March 2004, CU, Boulder
Indian Summer Monsoon Flow Hydro-Climate Course March 2004, CU, Boulder
Impact of Mountain Uplift on Asian Monsoon:850 hPa Winds(Kitoh 2004 15Feb, J. Climate) Hydro-Climate Course March 2004, CU, Boulder
Impact on Rainfall Distribution Hydro-Climate Course March 2004, CU, Boulder
Impact of Mountains on the Northward propagation of Rainfall in East Asia and the very existence of Baiu Rainfall in Japan Hydro-Climate Course March 2004, CU, Boulder
Impact of Mountain Uplift on the formation of Warm Pool in the west Pacific and the east Indian Oceans Hydro-Climate Course March 2004, CU, Boulder
Indian Summer Monsoon Hydro-Climate Course March 2004, CU, Boulder
Semi-Permanent Systems of Indian Monsoon Hydro-Climate Course March 2004, CU, Boulder
Dates of Normal Onset and Withdrawal of Monson Rains in India Withdrawal Onset Hydro-Climate Course March 2004, CU, Boulder
Mean Rainfall PatternsData Source: CMAP (1979-2000) Summer Monsoon (mm/season) Annual (mm/year) Hydro-Climate Course March 2004, CU, Boulder
Indian Summer Monsoon Contribution to Annual Rainfall and its VariabilityData Source : CMAP (1979-2000) Monsoon/Annual (%) Coefficient of Variation (%) Hydro-Climate Course March 2004, CU, Boulder
Mean Annual Cycle of All-India Mean Monthly Rainfall Hydro-Climate Course March 2004, CU, Boulder
Monsoon Variability Features Factors Hydro-Climate Course March 2004, CU, Boulder
Intra-seasonal Oscillations:Active/Break CyclesMadden-Julian (30-60 day) Oscillations Hydro-Climate Course March 2004, CU, Boulder
Daily Evolution of Rainfall on all-India Scale 2002 2003 Hydro-Climate Course March 2004, CU, Boulder
OLR Anomalies Associated with prolonged break situations in the Indian region Hydro-Climate Course March 2004, CU, Boulder
Madden-Julian Oscillations: Hydro-Climate Course March 2004, CU, Boulder
Eastward Propagating Tropical OLR Anomalies (MJO) Hydro-Climate Course March 2004, CU, Boulder
Northward Propagation of Cloud bands in the Indian region known as 30-60 day Oscillations Hydro-Climate Course March 2004, CU, Boulder
Interannual Variability of Indian Monsoon Rainfall and Links with El Niño – Southern Oscillation Hydro-Climate Course March 2004, CU, Boulder
The Stability of the Indian Summer Monsoon Hydro-Climate Course March 2004, CU, Boulder
Quasi-Biennial Cycle in Monsoon Rainfall Cycles/year Biennial cycle in monsoon rainfall is attributed to the response of land-sea to strong/weak monsoons Stronger monsoon leading to the cooling of the Indian land-mass And the adjoining seas resulting in a weaker land-sea gradient in the Next year and a weaker monsoon (refer to Gerry Meehl’s work for further understanding) Hydro-Climate Course March 2004, CU, Boulder
MonRF epochs Hydro-Climate Course March 2004, CU, Boulder
Schematic view of sea surface temperature and tropical rainfall in the the equatorial Pacific Ocean during normal, El Niño, and La Niña conditions . Hydro-Climate Course March 2004, CU, Boulder
Global Impacts of ENSO Hydro-Climate Course March 2004, CU, Boulder
Low-frequency co-variability of Monsoon Rainfall and ENSO Hydro-Climate Course March 2004, CU, Boulder
Difference in the Composites of Winter (Prior to Monsoon) Surface Air Temperatures over the Eurasian Region during El Nino Events pre-1980 and post-1980 periods (1981-97) – (1951-80) Diff. Climatologies of these Periods El Ninos Hydro-Climate Course March 2004, CU, Boulder
Relation between Indian Monsoon Rainfall and 200 (A,B) and the Composites of 200 for El Nino Events pre-,post-80’s (C,D) Hydro-Climate Course March 2004, CU, Boulder
Sea Surface Temp Anomalies in 1982 & 1997 JJA 82 SON 82 Monsoon Rainfall: -13% JJA 97 SON 97 Monsoon Rainfall: +2% Hydro-Climate Course March 2004, CU, Boulder
Sea Surface Temp Anomalies: 1987 & 2002 JJA 87 SON 87 Monsoon Rainfall: -18% SON 02 JJA 02 Monsoon Rainfall: -19% Hydro-Climate Course March 2004, CU, Boulder
Precipitation Anomalies: JJA 1982 1997 Monsoon Rainfall: -13% Monsoon Rainfall: +2% 2002 1987 Monsoon Rainfall: -19% Monsoon Rainfall: -18% Hydro-Climate Course March 2004, CU, Boulder
Precipitation Anomaly in NE Australia (DJF) and NE Brazil (JFM) in 1988 and 1998 1988 1998 1988 1998 Hydro-Climate Course March 2004, CU, Boulder
Surface Temp Anomaly over North America: DJF 1983 1998 1988 2003 Hydro-Climate Course March 2004, CU, Boulder
Precipitation/Forecasts of SST and Precipitation in JAS 2002 by Different GCMs Hydro-Climate Course March 2004, CU, Boulder