Investigation of First Order Line Settings for MARAC OOS High Frequency Radars Investigation of First Order Line Settings for MARAC OOS High Frequency Radars Erick Rivera Erick Rivera 1 , Hugh Roarty , Hugh Roarty 1 , John Kerfoot , John Kerfoot 1 , Josh Kohut , Josh Kohut 1 , Mike Smith , Mike Smith 1 , Ethan Handel , Ethan Handel 1 , Colin Evans , Colin Evans 1 , Scott Glenn , Scott Glenn 1 , Belinda Lipa , Belinda Lipa 2 , Bruce Nyden , Bruce Nyden 2 , Hector Aguilar, Hector Aguilar2 , Bill Rector, Bill Rector2 1 Rutgers University Instit ute of Marine and Coastal Sciences, Rutgers University Instit ute of Marine and Coastal Sciences, 2 Codar Ocean Sensors, Inc. Codar Ocean Sensors, Inc. An An impor tant important requirement requi reme nt ofof the the SeaSonde SeaSonde data data proce ssing processing softwa re sof twa re is is the the corre ct corr ect deline ation del ineati on ofof the the fir st fir st ord erord er Bra gg Bra gg reg ion region. Eff ect ive Effective first first orderorde r delineation delineation can ca n be be ach iev ed ach iev ed usi ng u si ng a a combination combination ofof CODAR CODAR recommendations reco mme ndati ons and and ca reful care ful exa minat ion ex aminatio n ofof the the loca l loc al condit ions conditions influencing influe ncin g the the rela tive rela tive posit ions pos iti ons ofof fi rst fir st and and second second orde ror der sea se a echo echo. . Using Using cross cross spec tra spec tra maps maps and and powe rpowe r plots plots (Rang e (Rang e Slice s), Slices), appropriate appropriate boundaries bounda ries can ca n be be set, set, resul ting res ult ing in in th e the bes t best ove rall ove rall qualit y qualit y data data. . Th e The following following is is a a disc ussio n disc ussio n ofof st eps , ste ps, examples examples and and recomme ndations recomme ndations to to help helpachieve achie ve the the properproperFirst irst OrderrderLine ine (FOL FOL) ) sett ings settings. 5 mHz systemshowing Second Order features 13 m Hz systemshowing Second Order features X(PEAK POWER) X/ FNULL x X/ FNULL The The MARACOOS MARACOOS regio n reg ion con sis ts consists of offourteen fo urteen long lo ng range ra nge syst ems syst ems that that measure measure sea sea surf ac e surfa ce curre nts cur rents alo ng along the theMid Mid- -Atlantic Atlantic coast coast. In In thi s this post erpost er we we have have ident ified ident ified fourfour doma ins doma ins that that show show different diff ere nt chara cter istic cha racteris tic in in first fi rst or der orderregion region. The The set tings settings were wereset set acco rding according to to visua l visua l inspe ctio ns inspe ctio ns in in Ran ge Range cell ce ll 3 3, 6 and and 11 11 and an d by by chan ging chan ging time time with with each each cross cross spectra spec tra file file Findings Findings It is critical to understand factors It is critical to understand factors affecting flow in the area sensed by each affecting flow in the area sensed by each individual radar when determing first orderindividual radar when determing first orderline settings line settings The settings of FOL for each site differs The settings of FOL for each site differs along the Mid along the Mid- -Atlantic from north to south. Atlantic from north to south. We identified four different current We identified four different current regimes. For large networks, we found it regimes. For large networks, we found it helpful to analyze each site in dependently helpful to analyze each site in dependently to get high quality radials to get high quality radials Careful inspection of both power plots Careful inspection of both power plots and cross spectra maps significantly and cross spectra maps significantly increase the accuracy of Bragg peak increase the accuracy of Bragg peak delineation delineation Accurat e Bragg peak delineation is Accurat e Bragg peak delineation is achieve on 5 MHz systems without achieve on 5 MHz systems without looking for second order features (nulls) looking for second order features (nulls) Recognizing First and Second Order Features Determining First Order Line Settings Type of Site 5 MHz 13 MHz 25 MHz = Decide not to look for Null (Nsec= 0) = Decide to Look for Null (Nsec= 1) ± FromPeak Power down by Peak Drop off20 ±25 dB 5 MHz 13 MHz 25 MHz ± FromPeak Power down to Peak Drop off20 ±25 dB From peak Power down to Peak Null ~6 dB Sets the boundaries Finds the Null Sets the boundaries Dominant Features: Fast curre nts Strong tidal influence Dominant Features: Coastal shelf environme nt Some tidal influen ce SITE Signal Above Noise (Factor) Max Velocity (cm/s) Peak Dropp off(dB) Peak Drop off(Factor) NAUS 6 dB (3.98) 150 21 125.89 NANT 6 dB (3.98) 150 21 125.89 MVCO 6 dB (3.98) 150 21 125.89 BLCK 6 dB (3.98) 150 21 125.89 MRCH 6 dB (3.98) 150 20 100.0 HOOK 6 dB (3.98) 150 20 100.0 LOVE 6 dB (3.98) 150 20 100.0 BRIG 6 dB (3.98) 150 20 100.0 ASSA 7 dB (5.01) 150 21.8 151.36 CEDR 7 dB (5.01) 150 21.8 151.36 LISL 7 dB (5.01) 150 21.8 151.36 DUCK SITE DOWN HATY 7 dB (5.01) 250 26 398.11 Dominant Features: Coastal environment Fresh water discharge from two estuaries Dominant Features: Shelf/Coasta l environment Strong Western Boun dary Current Introduction Identify Ide ntif y the the typ e type of offrequency fre quenc y that tha t radarradarwill wil l be be oper ating oper atingat at Decide Decide to to lo ok lo ok or ornot not to to look look forfor null nullto to set set the the bounda rie s boundaries surrounding su rr ou n di ng Fi rs t First OrderOrde r Lines Lines Figu re sho ws the boundaries between Fir st Ord er (shaded dar k) and Seco nd Or der (shaded li ght). Our pr imary object ive is to ide nt if y t he bo unda ri es surr ou nd in g th e fi rst or de r re gi on (dar k blue ) fo r ea ch spec tr a. The se boundaries ar e based on the inter action of the ra dar withthe oce an wav es. Since Since the the lowerlower freque ncy freque ncy syste ms systems hav e have grea tergreate r separa tion separa tion between between the the fir st fir st and and second second orderorder peaks peaks (abov e), (abov e), settin gs set tings forfo ra 5 MHz MHz system system DO DO NOT NOT look lookforfor nul ls nulls. The The bound aries bound aries are are identif ied identif ied with wit h the the Pea k Pea k Drop Drop offof f (F (F DOWN DOWN ) ) fro m fromthe thepeak peak powerpower. Since Si nce the the hi gher higher freq uency freq uency systems systems typica lly typica lly have have less less separation separation between bet wee n the the fir st fir st and and sec ond secon d orderorder region s, region s, setting s set ting s forfo r a 13 13 & & 25 25 MHz MHz system system DO DO look look for for null s nulls. The The algor ithm algor ithm looks looks for for nul ls nul ls from fro m the the Peak Peak PowerPower down down by by the the Pea k Pea k Nul l Null (F (F NULL NULL ) to to constr ain const rain the the bounda ries bounda ries ofof th e the first first orderorder regi on region. IfIf no no null s nul ls are are found, found, it it will will go go down down by by Pea k Pea k Drop Drop offoff(F (F DOWN DOWN ) When When lookin g lookin g forfor nul ls nul ls it itis is IMPORTANT IMPORTANT , that that Peak PeakNull Nul l (F (F NULL NULL ) < < Peak Peak Drop Drop offof f (F (F DOWN DOWN )
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8/6/2019 Investigation of First Order Line Settings for MARACOOS High Frequency Radars