Energy to destroy

' ... cyclones form when the sea surface temperature is above 26°C up to a depth of about 60m. Regions near the equator ... will surely increase in the future

'

An area devastated by Tropical Cyclone Pam. The authors says TCS are 11 in fact natural energy distributors".

Picture REPEKA NASIKO

By DR SUSHIL KUMAR and ASHNEEL CHANDRA

of the International Dateline ly when it was established. in.20Q3. weather hazards forecasts. to the Greep.wich Meridian; and Lightning dat_a. suggest!:( light-· :·,<(:;For. updates on the status of "typhoons"· in the Pacific north niJi_g activity is-greatly ·enhanced .~Y,clones in the South Pacific one

THIS is the time we get to of the EquatOr and·weSt of the In- in the ;i'ailibands with seCOndary c_An go to different web resources see cyclones ·occurring in te·rnationalDateline. maxiin'tl.Rl in tlie._eyewaQ~dur:ing :sUch ·as http://www.met.gov.fj/ the Southern Hemisphere. The major structures forming the int-ensification o'f a· tropical current_warnings.php, www.na­

Although our cyclone season is a cyclone are; the eye, a usually cyclone. drika.com, http://www.met.gov. coming to an end this month, the cloud free region with mostly The WWLLN has now grown fj/satellite.php and follow the occurrence of a Tropical Cyclone calm winds extending to about 60 with about 45 detectors at univer- weather bulletins from the Fiji Pam, TC Pam, made us to write km from the centre, followed by sities/national institutes all over Meteorological Services, http:// this article. the eyewall, where the most in- the world with a website where www.met.gov.fj/ and instruction

TCs are technically defined as tense :winds occur. Following the globaldatawithreal timecontin- on National Disaster Manage­warm-core non-frontal synoptic- eyewall, we have the inner and uous pictures of cloud coverage ment Office (NDMO) http://www. scale cyclones, originating over outer rainbands where we get a shows depressions superimposed ndmo.gov.fj. tropical or subtropical waters, lot of rain and thunderstorms ex- with strong lightning. Please Most of us would blindly as­with organised deep convection tending to about 500 km and over. viSlt-the web http://wwlln.net/ for sume that because of global and a closed surface wind circula- Although larger tropical cy- status of the depression and asso- warming and climate change, tion about a well-defined centre. clones do affect a more tropical cy-

TCs are natural hazards which greater area, so far, clones will occur in can and usually become natural there has been no ' the future. However, disasters. These cyclonic storms link relating the the frequency and in-are associated with strong winds, size of a cyclone to tensity are different rainfall and thunderstorms gen- its intensity. In fact, things to consider erating strong lightning dis- a recent study has when trying to pre-charges which can cause damage seen that cyclones diet future events of to physical structures, agricul- starting out smaller These structures are extraordinary this natural hazard. ture, and property and even claim in size have more Although the rise in livesofpeople.TCsalsoaffectthe chance of rapid in- and although We understand ... thiS temperature will in overall economy of the nations tensificatiOn. fact increase the sea that it encounters. Pacific Island TCs are detected natural hazard, ... , We WOUld not have area conditions need-countries (PICs) are specifically and monitored us- ed for the formation vulnerable to TCs. ing satellite remote been able tO imagine SUCh a thing .... of a tropical cyclone,

Rotating clockwise in the sensing and also us- there are other gen-southern part of our globe, tropi- ing ground based ra- ' esis factors to con-cal cyclones are in fact natural dio wave techniques. sider. energy distributors, harnessing One such radio wave Tropical cyclones their energy from the ocean and technique is using form when the sea converting it into the kinetic en- the Extremely Low surface temperature . ergy of the wind we experience Frequency (ELF) and is above 26°0 up to a as it passes. These structures are Very Low Frequency (VLF) radio ciated lightning. depth of about 60m. Regions near extraordinary and although we waves generated by lightning as- The data on web is not real time the equator meeting this require-understand most of the physics sociated with TCs. but the real time data is available ment will surely increase in the behind this natural hazard, had Using the ELF and VLF radio for commercial purposes which future. we not observed these cyclones, waves, a global lightning detec- can be purchased from the net- Weak vertical wind shear is we would not have been able to tion network called the "World work director. another contributing factor for imagine such a thing to exist. Wide Lightning Locations Net- The measurements of strong tropical cyclone formation. Re-

Tropical cyclones are known work" (WWLLN) was established lightnings associated thunder- gions meeting the threshold by different names depending on in 2002 by the Otago University, storms, which are a major natu- weak vertical wind shear and sea where they originate. They are New Zealand, which Physics (for- ral hazard to the public, aviation, surface temperature conditions known as "hurricanes" in the merly Department of Physics), power companies, and wildfire, may not increase ·consistently Northern Atlantic and Northeast SEP, USP, joined in 2003. are also extensively used by me- together. Pacific; .''tropical cyclones" east WWLLN had 11 stations global- teorological offices for severe Even though one genesis fac-

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tor will increase, all genesis con­ditions must be met for tropical cyclones to form. The frequency of tropical cyclones may not in­crease, but the intensity may. Since tropical cyclones get their energy from the ocean (which will store more energy in the fu­ture because of increasing tem­peratures), future cyclones may be more intense but not as fre­quent.

With research headed by Dr. Sushi! Kumar (associate profes­sor of Physics), our Communica­tions and Atmospheric (Space) Physics Group is trying to study this natural hazard. It is hoped that our findings will develop new techniques to determine intensi­fication of a cyclone from VLF ra­dio waves produced during light­ning within a tropical cyclone.

Ashneel Chandra's working for his Master's Degree investigat­ing the relationship between sus­tained wind velocity and light­ning activity of cyclones in the South Pacific.

'J;'h.understorms influence the clita'hte system by the redistri­butiOn of heat, moisture, and momentum in the atmosphere and are linked nonlinearly with lightning, temperature, upp8r tropospheric water vapour and cloud cover and thus may provide a useful tool for tracking climate change in the future.

The interested reader is re­ferred to the. research article, "Lightning Applications in Weather and Climate Research" by Colin G. Price, in Surveys in Geophysics. • This is the view of the authors and not of this newspaper. They can be contacted on kumar_su@usp. ac.fj and phone numbers 3232144, 9926567. Mr Chandra can be con­tacted on chandra_as@usp.ac.fj, and on this phone number 3232644.