TURKISH WEATHER RADAR NETWORK Ismail TEMİR1 Abdurrahman MACİT2 1Turkish State Meteorological Service, Keçiören, Kalaba, Ankara,[email protected] 2Turkish State Meteorological Service, Keçiören, Kalaba, Ankara,[email protected] (Dated:31 March 2016) 1. Introduction

Weather radar systems are one of the most important instruments for observing weather and early warning systems in the world. Turkish State Meteorological Service (TSMS) has operated 15 CBand Doppler weather radars which were established in Ankara, Istanbul, Zonguldak, Balıkesir, İzmir, Muğla, Antalya, Hatay, Samsun, Trabzon, Bursa, Afyonkarahisar, Karaman, Gaziantep and Şanlıurfa. Firstly, Ankara radar was installed as C- Band with dual polarization capability in 2001. At the end of 2013 it has upgraded analog receiver to digital receiver in SELEX SI. Then the network was formed by adding three C-Band single polarization weather radars from Mitsubishi in 2003. According to the TSMS feasibility report, TSMS has decided to add six (6) C- Band radars in it’s network. Four of them will have the dual polarization capability while two of them will have the single polarization capability. İnstallation and provisional acceptance

of six (6) C- Band radars has finished in

2013.Warranty period and final acceptance of six radars have just finished in 2016. By the help of feasibility report, TSMS has decided to extended and completed to its radar network and added seven magnetron tube C-Band radars with dual polarization capability. Now TSMS has 15 C- Band Doppler weather radars. At the end of 2016, TSMS is going to be completed its C- Band weather radar network with 17 C-Band. TSMS also installed one dual polarization magnetron tube Mobile X- Band radar for aviation, research and testing purpose in Ataturk airport in 2013. According to results of evaluations, new X Band Radar Network for cities, airports and gaps in the C Band Radar Network is planned. TSMS has decided to upgraded to three single polarization Mitsubishi radar to new generation radars in coming three years. In this paper, new C Band Weather Radar Network of TSMS is going to be presented in details and future plans for other type of weather radars like X Band Radars is going to be mentioned.

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2. The Absttract All TSMS’’s radars except Ankara Radar R will bee capable off performing of intensity and velocityy calibrattion. Autom matic multi point p receiveer calibrationn should be done by usiing the signnal generatorr which iis be mounteed at each raddar system. It I will be posssible to makke the intensiity check andd to measuree the phaase noise by means m of thee maintenancce software.

3. Expansioon of Turkissh Weather Radar Netw work In last fifteeen years, TSMS T have lots of imprrovements on o weather radar r system ms including g differennt radar equiipments as well w as on rad dar network.. Now TSMS S operate tenn C- Band Klystron K tubee weatheer radars andd five C- Baand Magnetrron tube weeather radarss, it will be 17 at the end of 2016.. Turkishh C- Band Weather W Radaar network haave been com mpleted at th he end of 201 16. There aree many typess of impprovements on our weeather radarr systems. These are mainly harrdware, softtware, radarr infrastrructure and other o improvvements. I will w briefly exxplain hardw ware improveements on w weather radarr system m in this paperr.

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Pict. New toower for radaar

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Pict. TSMS whole w radar Network

3.1- Haardware Im mprovementss: 3.1.a-) Duaal Type: Switch or Simu ultaneous All of our radars r have 5625 5 MHZ frequency f annd 250 kW peeak power. TSMS's T havee ten C-Band d Doppleer weather raadars with klyystron tube and a five C- Band B Doppleer magnetronn tube twelvee of them aree dual poolarization capability c annd TSMS will w be installed two C- Band Dopppler weather radars with h magnettron tube in end of 20166. TSMS firstt radar whichh is name off Ankara Radar has upgrraded switch h type duual polarizatiion mode to Simultaneou S us Transmitting and Receeiving (STAR R) mode In 2013, 2 Simultaneo ous Transmittting and Recceiving (STA AR) mode shhall be used in i our all raddars (Pict. 1).. Also only o horizonttal or only vertical or both b horizonntal and verrtical polarizzation capabiility will bee availabble. Although h the transmiitter’s peak power p is 2500kW at first, the transmittted power iss sent half off the peaak power (1225kW) to atm mosphere in STAR modde after RF signal s passess from power splitter forr simultaaneous transm mitting. Thuus radar can receive RF signals refleected from taargets in botth horizontall and verrtical channeel. So in thiss type of duaal polarizatioon the transm mitted peak power decreeases half off power bbut much mo ore informatiion can be obbtained from m the targets in i the atmospphere at the same time.

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P Pict. 1 Simulltaneous Duaal Polarizatio on Channel

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In TSMS’ 7 radar projject both of them will haave dual pollarization caapability withh magnetron n tube. T TSMS have decided d to coomplete wholle Radar netw work with magnetron m traansmitter tube because off there soo many imprrovements onn the magnettron type Traansmitter Tuube. In last teen years maggnetron tubess are gettting more an nd more staable like as klystron k tubee. Magnetron n tubes also have some advantages.. These are; a -less mainttenance cost -less system m price -long life tiime (similar to Klystron tube) t

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Pict.2 Weather Radar with magnetrron tube

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3.2- Sooftware Imp provements 3.2.a-) Duaal Polarizatiion Products All TSMS’s polarimettric radars will w producee dual polarization prodducts such as: a Rainfalll Accum mulation prod duct, Hydrom meteor Classsification Prooduct, Precippitation Efficciency Rate Products. In n these products p Z- Reflectivity, R ZDR- Differeential Reflecctivity, KDP P- Specific Differential D P Phase, LDR-Linear Depolarization Ratio, ØDP- Differeential Phase Shift, ρHV- Polarimetricc-Correlationn Coefficientt parameeters have beeen used. Thhese productss shall be geenerated by using u the hyydrometeor classification c n algorithhms based onn Fuzzy Loggic and/or Arrtificial Neural Network.

Pict 3. Rain nfall Accumu ulation Produ uct

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3.2.b-) Recceiver Calibration All operatiional and under installatiion radars arre digital recceiver and dyynamic rangge are biggerr than 955. All operational and still under instaallation radarrs have autom matic multi-p point receiveer calibration n tool in their maintennance softwaare. Automatic signal generrator (Pict.4)) should be installed i in thhe radar systtem for automatic multi-point ccalibration. The T signals from noise level l to satuuration level are appliedd automaticallly by using g signal ggenerator foor multi-poinnt calibrationn. So a receivver responsee curve is plotted by caliibration tooll (Fig. 1)) and calibraation results are a saved. Receiver caalibration muust be done by b us at leastt in every 6 months m perioodical mainteenance.

Pict. 44- Automaticc Signal Geneerator mounted to the radar syystem

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Fig. 1- Receiver Calibration C T Tool

Calibrationn for Receiveer

3.2.c-) Sun n Calibration n The sun maay serve as an a external raadiation sourrce for calibrration of the radar r system ms. The sun’ss power can also be useful u techniique for monnitoring the ccalibration off the receivee chain of thee radar when n used inn conjunction n with indepeendent measu urements of solar flux deensity. In our first radar, sun calibration c toool shows thee position off the sun, corrrect time annd longitude-latitudee of the radaar. We can coompare and the actual anntenna positiion according g to the valuues from sun n cal tooll. However inn three radarrs sun calibraation is done manually byy using sun cal c tool. If we w get correctt time annd correct poosition of thee sun then wee do sun traccking. At the antenna anyy error occurrs during sun n trackinng test (Pict.5 5), then we ddo some adju ustment. Firsst we do adju ustments elecctrically (Picct.6) to makee the erroor zero, the second s stage may be need ded by slidinng the angle measuring m bar mechanicaally (Pict.7).. After thhese adjustm ments sun callibration is done d again. IIf the errors don’t exceed d the given llimit values,, sun callibration becoomes ok. Othherwise it is not ok.

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Pict. 5- Sun n Calibrationn Tool

Pict.. 6- Electricaally adjustmeent by using dip switch

Pict. 7- Mechanical adjustment bby using anteenna scale In six radaars and sevenn radar projeect there is automatic suun cal utilityy. The sun calibration c iss carriedd out automaatically and angle a errors during the ccalibration are a ignored and a corrected values forr angles are stored automatically a y by using software. Thee sun cal utiility can be run interactiively from a commaand line and d does not use u a graphiccal interfacee. The sun cal c utility ouutputs a BEA AM productt (Fig.2). The BEAM M product wiill contain SN NR (Signal too Noise Ratiio) data with no thresholdding and can n be view wed on an IR RIS system,, but is not automatically a y inserted innto an IRIS product dicttionary. Thee BEAM M product is then t processsed to produuce a final caalibration ressults file. Thhe calibrationn results filee produced contains lots l of inform mation derived from the calibration such s as the tiime, locationn and the sitee name. A Also there arre radar calibbration numbbers such as the t noise lev vel and the reeceiver bandw width.

Fig.. 2- BEAM Product P from SUNCAL Utility U showinng sun

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Also some methods shaall be provided for the caalibration of dual d polarizaation. For exxample, ZDR R calibrattion (Pict.8) shall be fullfilled and recorded by the values which w are recceived after the antennaa shall poositioned upw wards full veertical positio on and turned on horizonntal position at least oncee per day. Also radaar system shall measure the sun eneergy daily an nd record th he values forr purpose off checkinng the data quality. q

Pict.8 ZDR R Calibrationn

3.3- M Mobile X Ban nd Radar TSMS now w operate one X Band Mobile M Radarr with Magneetron tube (P Pict.9) in Ataatürk airportt in İstannbul. It ıs used for testingg and checkiing rain and other echos between C band b and Mobile radars.. If testinng period wiill be successsful and suffi ficient for us TSMS will have planning to fill to gap g between n C Bandd radars and the to fill thee others airpo ort for aviation purpose.

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Pict.9 Mob bile X-Band Radar with Magnetron M tuube

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3.4- HF F Radars H radars (Picct.10) used to t determinee wavelengthh and currentt And finally TSMS have operating HF directioon of the watter in two sides of the boosphorus in Aisa A and Eurrope.

Pict.10 HF F Radars

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Pict.111HF Radar Products P

4. Con nclusion TSMS hass been compplete their CC Band raddar network in the end d of 2016. Day D by day y technollogy is addin ng new featuures to the raadar systems. Therefore TSMS T would d like to havve these new w technollogical impro ovements acccording to th he necessitiess. TSMS has been planniing to expannd its networrk to add the X-Band raadars by connsidering thee topograaphy, coveraage and the meteorologic m cal targets. In future, to fill the gap between b C- Band radarss 15 X-B Band Weatheer Radars are proposed too be installedd. Also TSMS has been planning to add Low Level L Wind Shear Alert System (LL LWAS) with h LİDAR R and X Bandd all together in their Network by endd of 2016. Now N we madee a tender annd evaluation n will gooing on. The LLWAS is installed in Antalya A airpport and if wee getting succcess to alertt system, wee have pllan to install our big airpoort such as Isstanbul, Ankkara,Izmir. TSMS has been tryingg to improve its observattion capabiliity by establlishing modeern and welll developped observinng systems inn order to prrovide the meteorologica m al services an nd products to the users.. Regionnal and internnational coopperation is one critical coomponent to improve thee capacity off the agency,, and to increase i the quality of thhe service. Thhis is why TS SMS is alwaays open for any a cooperattion activity.

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Ronaald E. Rinehaart, August 1997, Radar for f Meteorollogists 18

2.

Doviak R.J. and Zrnic D.S., 1993, Doppler Radar and Weather Observations

3.

Merrill I. Skolnik, Introduction to Radar System

4.

Gematronik GmbH, 12.July.2001, Meteor 1000CUser Manuel and Documentation-Doppler Weather Radar System

5.

Mitsubishi Electric Corp., 2002, RC-57A Weather Radar Training Document and User Manuel

6.

Ercan Buyukbas, Oguzhan Sireci, Aytac Hazer, Ismail Temir, Cihan Gozubuyuk, Abdurrahman Macit, M. Kemal Aydın, Mustafa Kocaman, 2002, Turkish Radar Network, Hardware Maintenance of Weather Radars, Training Notes

7.

Radar Lecture Notes and Articles available in internet

8.

Technical Brochures of Radar Manufacturers and Technical Correspondances with Manufacturers (Vaisala, Mitsubishi, Selex, EEC, Metstar, Baron and Radtec)

9.

Commission of Technical Specifications, 2008, TSMS Technical Specifications for The Tender of 6Unit C-Band Doppler Weather Radars for Aegean, Mediterranean and Eastern Black Sea Regions

10.

Commission of Technical Specifications, 2013, TSMS Technical Specifications for The Tender of 7Unit C-Band Doppler Weather Radars

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