"STUDY ON THE VARIABILITY OF SOUTHWEST MONSOON RAINFALL AND TROPICAL CYCLONES FOR 2001 2010" ESPERANZA O. CAYANAN, Ph.D. Chief, Climatology & Agrometeorology R & D Section Philippine Atmospheric Geophysical and Astronomical Services Administration (PAGASA)
OUTLINE Introduction The Philippine Climate Climate Trends in the Philippines Southwest Monsoon Rainfall Variability: 2001 2010 Tropical cyclone Variability: 2001 2010
Introduction: The Philippine Archipelago Composed of 7,107 islands w/ 32,400km coastline Geographically located in Western North Pacific: Pacific ring of fire Breeding ground of tropical cyclones Philippine Climate: tropical & maritime high relative humidity high temperature (26.6 o C) abundant rainfall Population: 91,983,000
Climate Types based on Coronas Climate Classification Type I: Two pronounced season: dry from November to April and wet during the rest of the year. Type II : No dry season with a very pronounced maximum rainfall during the month of November-December. Type III: Seasons not very pronounced, relatively dry from November to April and wet during the rest of the year. Type IV: Rainfall more or less evenly distributed throughout the year.
MONSOONS W N S E SW monsoon or Habagat NE Monsoon or Amihan
Philippine mean temperature Observed Mean Temperature Anomalies in the Philippines (1951 2010) Departures from 1971 2000 normal values An increase of 0.648 C from 1951 2010 (60 years)
Maximum & Minimum Temperature Rate of increase almost 3 times higher compared with the maximum temperature
Trend in the frequency of days with maximum temperature above the 1961-1990 mean 99th percentile (Hot days). Trend in the frequency with minimum temperature above the 1961-1990 mean 99th percentile (Warm nights)
Trend in the frequency with Maximum temperature below the 1961-1990 mean 1st percentile Cool Days Trend in the frequency with minimum temperature below the 1961-1990 mean 1st percentile Cold nights
Objective: To study the variability of southwest monsoon rainfall in terms of intensity and distribution in time and space Data: Daily rainfall observed at 49 PAGASA synoptic stations Southwest monsoon months considered: May - September
ANNUAL AND SOUTHWEST MONSOON RAINFALL 30-year Normal and 10-year Mean 30-year (1981-2010) Normal 10-year (2001-2010) Mean
SW monsoon rainfall is what % of the annual rainfall? 30 Year Period 10 Year Period
VARIABILITY OF ANNUAL, SW & NE MONSOON RAINFALL: 2001-2010 600 400 200 0 200 400 600 600 400 200 0 200 400 600 600 400 200 0 200 400 600 Annual RR Anomaly 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 SW Monsoon RR Anomaly 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 NE Monsoon Anomaly 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 ENSO Occurrence: 2001 La Nina: Jan-Mar 2002 El Nino: Apr-Dec 2003 El Nino: Feb-Apr 2004 El Nino: May-Dec 2005 El Nino: Jan-Mar 2006 El Nino: Jul-Dec 2007 El Nino: Jan-Feb, La Nina: Aug-Dec 2008 La Nina: Jan-Jun 2009 El Nino: May-Dec 2010 El Nino: Jan-May, La Nina:June-Dec SWM RR not affected by El Nino (2002-05,2009)
OCEANIC NINO INDEX Historical Pacific warm (red) and cold (blue) episodes based on a threshold of +/- 0.5 o Cfor the Oceanic Nino Index (ONI) [3 month running mean of ERSST.v3b SST anomalies in the Nino 3.4 region (5N-5S, 120-170W)], calculated with respect to the 1971-2000 base period. For historical purposes El Niño and La Niña episodes are defined when the threshold is met for a minimum of 5 consecutive over-lapping seasons. Year DJF JFM FMA MAM AMJ MJJ JJA JAS ASO SON OND NDJ 2002-0.1 0.1 0.2 0.4 0.7 0.8 0.9 1.0 1.1 1.3 1.5 1.4 2003 1.2 0.9 0.5 0.1-0.1 0.1 0.4 0.5 0.6 0.5 0.6 0.4 2004 0.4 0.3 0.2 0.2 0.3 0.5 0.7 0.8 0.9 0.8 0.8 0.8 2005 0.7 0.5 0.4 0.4 0.4 0.4 0.4 0.3 0.2-0.1-0.4-0.7 2006-0.7-0.6-0.4-0.1 0.1 0.2 0.3 0.5 0.6 0.9 1.1 1.1 2007 0.8 0.4 0.1-0.1-0.1-0.1-0.1-0.4-0.7-1.0-1.1-1.3 2008-1.4-1.4-1.1-0.8-0.6-0.4-0.1 0.0 0.0 0.0-0.3-0.6 2009-0.8-0.7-0.5-0.1 0.2 0.6 0.7 0.8 0.9 1.2 1.5 1.8 2010 1.7 2008 La Nina: Jan-Jun 2009 El Nino: May-Dec 2010 El Nino: Jan-May, La Nina:June-Dec
Extreme Climate variability (ENSO of 2010) 2008 La Nina: Jan-Jun 2009 El Nino: May-Dec 2010 El Nino: Jan-May, La Nina:June-Dec Dec. 2009 Jan. 2010 Feb. 2010 Mar. 2010 Nov. 2009 Sept. 2009 Oct. 2009 Rainfall Maps Black areas: Excessive rains Red areas: rainfall deficit
Tracks of Tropical Cyclones in the Western North Pacific Period: (1948 2010) Visited by an average 19 to 20 TYPHOONS EVERY YEAR Tracks of tropical cyclones that formed in the Western North Pacific (WNP) during the period 1948 2010 is 1,641 TC and 1,154 or 70% entered or formed in the Philippine Area of Responsibly (PAR) (Data used: JMA Data set)
Annual Number of Tropical Cyclones in the PAR Period: 1948-2010 Number of Tropical Cyclones 40 35 30 25 20 15 10 Number of Tropical Cyclones Five-year running mean Linear (Five-year running mean) y = -0.0223x + 20.124 5 0 1948 1953 1958 1963 1968 1973 1978 1983 1988 1993 1998 2003 2008 Year * Cinco,T.A.,2011.
(Cinco, 2011)
Trends in the Number of TC TRENDS IN TROPICAL CYCLONE IN THE PHILIPPINES Number 250 200 150 100 1951 80 1961 90 1971 00 51-80 61-90 71-00 50 0 LUZON Luzon VISAYAS Visayas MINDANAO Mindanao
Tracks of Tropical Cyclones that Entered the Philippine Area of Responsibility (PAR) for 2001-2010 Total = 185 Crossed landmass = 60
Comparison of long-term mean and 10-year mean of tropical cyclone occurrence in the Philippines Mean Monthly Tropical Cyclone Occurrence Number of Tropical Cyclones 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 3.3 63-year mean 3.2 3.0 10-year mean 2.6 2.1 1.5 1.4 1.0 0.4 0.3 0.3 0.5 1 2 3 4 5 6 7 8 9 10 11 12 Month
SUMMARY OF INITIAL OBSERVATIONAL STUDY: No big change in the 10-year mean annual rainfall compared to the 30-year normal There was an increase in rainfall in some part of western Mindanao during the 10-year SW monsoon months The SW monsoon rainfall was not highly affected by El Nino of 2002 2005 There was an extreme variability in the 2009-2010 ENSO event The mean number of tropical cyclones for March, April, May and September increased in the last 10 years. There was a decreased in number on the rest of the months except for November which is constant.
We did not inherit the Earth from our ancestors we borrowed it from our children and our children s children. Native American Philosophy From Commissioner Saño s presentation
THANK YOU and MABUHAY!
ACKNOWLEDGEMENTS REFERENCES: Yeb Saño, Commissioner, Climate Change Commission, Presentation on Climate Change during the 7 th Phil. Meteorological Society Convention, Nov. 17 18, 2011. Rosalina de Guzman, Asst. Weather Services Chief, PAGASA; Philippine Climate trends projections and scenarios Thelma A. Cinco, Asst. Weather Services Chief, PAGASA; Philippine Climate trends projections and scenarios