International Forum on Tornado Disaster Risk Reduction for Bangladesh - To Cope with Neglected Severe Disasters - 13-14 December 2009, Dhaka, Bangladesh Early Warning System for Tornado and other hazardous winds in Japan Osamu Suzuki Meteorological Research Institute Japan Meteorological Agency Photo:Saroma tornado, 7 November 2006, Courtesy of Ms. Takai
Two tornadoes in 2006
Nobeoka, Miyazaki Tornado on 17 September 2006, F2 3 fatalities and 143 injuries Typhoon assosiated mini- supercell tornado Damage path length 7.5km and width 300 m.
Saroma, Hokkaido tornado on 7 November 2006, F3 9 fatalities and 26 injuries Largest fatalities since 1942 Possible supercell tornado 1320JST Radar (color) and Surface pressure (color line, 1 hpa) Temperature (black line, 1 deg)
Short lecture on Tornadoes in Japan
Annual frequency of Tornadoes 13 7 /yr 13.7 / yr (1991-2008)
Death and Injuries by Tornadoes and other hazardous winds Event Number of Average peoples per year Fatalities Tornadoes Tornadoes and other hazardous winds Injuries Tornadoes Tornadoes and other h d i d 28 0.58 46 096 0.96 1862 2324 38.8 48.2 hazardous winds (1961-2008) Fatalities and injuries by tornadoes are 12 and 193, respectively in 2005 and 2006. Fatalities and injuries by all the events are 17 and247, respectively in the same period.
Geographical distribution and damage path size of Tornadoes A significant numb of tornadoes occur near Average of damage path width is 260m. the coastlines. Inland tornadoes occur And average of damage path length is 3.2 mainly in large plains km but longest track was 42 km length. Damage path width ditribution 140 Numb ber 120 100 80 60 40 mean stdev mode 160.4 259.4 80.00 20 0 ~16 16~51 51~161 161~509 509~1609 1609~ width (m) Damage path length ditribution 140 Number 120 100 80 60 40 mean stdev mode 3.2 4.3 1.7 20 0 ~1.6 1.6~5.1 5.1~16.1 16.1~50.9 50.9~160.9 160.9~ Length (km)
Fujita-scale Fujita scale of events 140 120 100 80 (1961-1993) (1961-2008) No tornado severe than F3. Reported F0 and F1 tornado increased. Number 60 40 20 0 0 1 1 2 3 2 4 3 5 4 6 5 F-scale
Supercell Tornado Supercell An often dangerous convective storm that consists primarily of a single, quasi-steady rotating updraft. It may exist for several hours and usually forms in an environment with strong vertical wind shear. (from AMS glossary of meteorology) Rotating updraft in a supercell is called mesocyclone. Identified supercells in JAPAN (not all) 1978/2/28 Tornado (F2-3) Derailed (Low) 1990/9/19 Mibu tornado (F2) (Typhoon, mini) 1990/12/11 Mobra tornado (F3) (Low) 1996/7/5/ Chiba tornado (F2) (Low, mini) i) 1996/7/15 Hail storm with downburst (F2) in Ibaraki 1999/9/24 Toyohashi forward (F3) (Typhoon, mini) 2000/5/24 Hail storm with downburst in Chiba and Ibaraki 2001/5/11 Hail storm with strong ggust in Chiba and Ibaraki 2001/8/22 Tornado (F1) in Saitama, straight line wind in Gumma 2001/9/10 Tornado in Tokyo (F1) (Typhoon ) 2002/7/10 Sakai-town tornado (F2) (Typhoon, mini) 2004/9/30 Tornado at Haneda airport (F1-2)(Typhoon) 2005/5/15 Straight line winds in Tokyo and Kanagawa (F0-1) 2005/6/4 Downburst at Ohsaka airport 2006/7/5 Tornado in Kochi (F0-1) 2006/9/17 Nobeoka tornado (F2) (Typhoon, mini) 2007/3/15 Tornado in Okinawa (F1) Schematic illustration of a supercell. Lemon and Doswell, 1979
First Doppler-radar-identified supercell in Japan Mobara tornado (F3) on December 11, 1990 Mesocyclone signature is detected in Doppler velocity field. from Suzuki and Niino, 1991 Mesocyclone movement. from Niino et al., 1993
Mini-supercells on Sept. 19, 1990 mini-supercell Convective storm that contains similar radar characteristics to those of a supercell (e.g., hook echo, WER, BWER), but is significantly smaller in height and width. (from AMS Glossary of Meteorology) The PPI display of reflectivity (a) and Doppler velocity (b) of storms E, F, and G with elevation angle of 2.2 deg at 2146 JST. The RHI display of reflectivity (c) and Doppler velocity (d) of storm G with azimuth angle 250 deg at 2153 JST. The MCs are indicated by open circles in the PPI displays. Arrows in (d) indicate wind directions relative the radar deduced from the Doppler velocity field. from Suzuki et al., 2000
Mini-supercells and tornadoes on Sept. 19, 1990 A 2012 B 2103 1922 D 1951 2117 Inagi City C 2131 2040 2017 2140 2222 E 1944 2145 2122 1937 F 2112 2103 2053 G TOKYO H Mibu Town 2215 2145 2215 MRI 0027 0020 2154 2343 I 2320 0005 2343 N Shimotsuma Chiyokawa Azuma Village Pacific 2112 Ocean 20 km 9 identified mini-supercells were idenfied. 3 mini-supercells out of 9 spawned tornadoes and one caused wind damage within 6 hours. Movement of mesocyclones and storms detected by the MRI Doppler radar on the night of 19 September 1990. The solid triangles connected by thin lines show the locations of mesocyclones. Numerals by the triangles indicate the beginning g or end time of the detection of mesocyclones. Mesocyclone paths in the same storms are connected with dashed lines. Thick lines and solid circles show the location of damages by tornadoes (Inagi City, Mibu Town, and Azuma village) and heavy winds (Chiyokawa and Shimotsuma), respectively. from Suzuki et al., 2000 This fact indicated possibilities of tornado warning using Doppler radar as in US.
Non-Supercell Tornado A tornado that occurs with a parent cloud in its growth stage and with its vorticity originating in the boundary layer. The parent cloud does not contain a preexisting midlevel mesocyclone. (from AMS glossary of meteorology) from Wakimoto and Wilson, 1989
Building an Early Warning System for Tornadoes and other hazardous winds
JMA's Action JMA decided to build an early warning system for tornadoes and other hazardous winds. Speed up upgrade plan for existing conventional radar to Doppler Re-construct tornado database (not shown) Develop a techniques for forecasting of tornadoes Develop Mesocyclone detection algorithm Environmental indices calculated from NWP data Set up an advisory committee Disseminate tornado watch Raise Public Awareness
Radar network upgrade Doppler Conventional TDWR as as of of 2010/3(planed) 2006/11
MC detection algorithm MRI s MC detection algorithm consist of following steps; i) pre-processing Radar data (first QC) ii) fitting observed Doppler velocity fields with wind models iii) checking size, vorticity, i and the fitness of each MC to meet a MC criteria i iv) declearing MC if temporal continuity is satisfied (2nd QC) Wind fields models : RCV+Divergence modified Rankine's combined vortex DIV VOR ( u, v ) = [ ( x, y ) + ( y, x )] s 2 2 L s L s = 1 L if ( r = = r r c 2 x 2 L if ( r > + r c y ) 2 r c ) Vmaxc rc rc rc rc RCV Axsimmetric Divergence Axsymmetirc V+D
Examination of algorithm with real data (Example of real data) Sakai town tornadoonjuly on July, 10, 2002 A total of 4 mesocyclones were detected on the day. MC3 MC4 MC1 14:03 15:57 PPI display of Dopler velocities by Narita DRAW (Doppler Radar for Airport Weather) at 1403 JST and 1557 JST on July, 10, 2007. Locations of 3 mesocyclones are indicated by black circle. Elev 0.7 deg. max range 120km,
Comparison of MCs detected by proposed method with manualy analyzed ones. Compirson with peak-to-peak method - Sakai tornado on July, 10, 2001 - MC2~4 MC2~4 MC1 Proposed method peak-to-peak method Plots of detected mesocyclones indicate good agreement.
Environmental indices for tornado warning CAPE (Convective Available Potential Energy) A measure of instability of the atmosphere. SReH (Storm Relative Helicity)] A measure of vertical wind shear used for evaluating possibility of mesocyclone generation EHI (Energy Helicity Index)(Rasmussen,2003). A measure of supercell/tornado possibility. EHI = CAPE*SReH/160000 - EHI>1 possible supercell, EHI>4 strong tornado Storm motion Note:These indices can be calculated from upper air sounding or NWP data.
Example of indices calculated from MSM (NWP) in Japan Time of Nobeoka tornado on September 17, 2006 (mini-supercell) Time of Saroma tornado on November 9, 2006 (possibly supercell)
Example of indices calculated from upper air sounding at Dhaka on a tornado day Applied to the day of a deadly tornado. Upper air sounding at Dhaka on 13 May, 1996 CAPE = 3350.0 0 J/kg SReH(estimated) = 260 (m^2/s^2) EHI = 5.4 -> Supercell possible and strong tornados
Techniques for forecasting of hazardous winds by the courtesy of Mr. Doi
Dissemination of tornado watch by the courtesy of Mr. Doi
Tornado Watch (March 2008~)
Raising Public Awareness by the courtesy of Mr. Doi
How to utilize the Watch? Developing a guideline by the courtesy of Mr. Doi
by the courtesy of Mr. Doi Possible Scenario
Designing information in collaboration with users Set up an advisory committee composed of professors of meteorology, sociology and risk management, and media people and asked for advice on information contents and how to convey the risk of hazardous winds. Sought opinions from potential users such as construction firms, schools, railway companies. Outcomes from the discussion Name of the information The word tornado should be included, because this word draws people s attention for its risk, while the information of downbursts and gust fronts is also included. Valid time period of the Watch Indication of the valid time period of the Watch (one hour) helps to understand exactly when people should pay attention to severe weather. Support this service The JMA should provide the information, even if the accuracy is rather low; the information can save people s lives when used properly. by the courtesy of Mr. Doi
Summary After the deadly tornadoes in 2006, JMA and MRI cooperated to built an Early Warning System for tornado and other hazardous winds. The system is in operation since March 2008. Although It is new and under developing, I hope our experience of building an EWS may be useful for other countries like Bangladesh.
Thank you for your attentions!