Hydrometeorology and Hydrometeorology and Polarimetric Radar Polarimetric Radar How can Polarimetric How can Polarimetric radar aid in flash flood radar aid in flash flood forecasting? forecasting? James J. Stagliano, Jr James J. Stagliano, Jr .1, .1, James L. James L. Alford Alford 1 , Dean Nelson , Dean Nelson 1 , J. William , J. William Conway Conway 2 , , Barbara Gibson Barbara Gibson 3 and Don Hyde and Don Hyde 3 1 Enterprise Electronics Corporation Enterprise Electronics Corporation 2 Weather Decision Technologies Weather Decision Technologies 3 Choctawhatchee, Pea and Yellow Rivers Watershed Choctawhatchee, Pea and Yellow Rivers Watershed Authority Authority
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Hydrometeorology and Polarimetric Radar How can Polarimetric radar aid in flash flood forecasting? James J. Stagliano, Jr.1, James L. Alford 1, Dean Nelson.
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Hydrometeorology and Hydrometeorology and Polarimetric Radar Polarimetric Radar
How can Polarimetric radar aid in How can Polarimetric radar aid in flash flood forecasting? flash flood forecasting?
James J. Stagliano, JrJames J. Stagliano, Jr.1,.1, James L. Alford James L. Alford11, , Dean NelsonDean Nelson11, J. William Conway, J. William Conway22, ,
Barbara GibsonBarbara Gibson33 and Don Hyde and Don Hyde33
Numerous meteorological and physical effects Numerous meteorological and physical effects limit accurate rainfall estimationlimit accurate rainfall estimation– Marshall – Palmer (Z-R) RelationshipMarshall – Palmer (Z-R) Relationship
Different DSD Different DSD Varies from event to event Varies from event to event Different DSD Different DSD Varies within precipitation event Varies within precipitation event Mie Resonance EffectsMie Resonance Effects
Rainfall Estimates given by Marshall-Palmer Rainfall Estimates given by Marshall-Palmer RelationshipRelationship
– Dependent on sixth power of diameterDependent on sixth power of diameter
Drop SizeDrop Size QuantityQuantity ZZ Water VolumeWater Volume
1 mm1 mm 40964096 36 dBZ36 dBZ 17,160 mm17,160 mm33
4 mm4 mm 11 36 dBZ36 dBZ 270 mm270 mm33
A factor of 63 difference
baRz
Radar – Drop Size DistributionRadar – Drop Size Distribution
Similar Reflectivity, Different Drop Size Distributions
ScatteringScattering
Precipitation ScatteringPrecipitation Scattering
Assumption is all scattering is RayleighAssumption is all scattering is Rayleigh– True for S bandTrue for S band– Not true for C and X band (Ryzhkov, 2005)Not true for C and X band (Ryzhkov, 2005)
Transmits microwave energy in both Transmits microwave energy in both horizontal and vertical polarizationshorizontal and vertical polarizations– Able to measure entire scattering matrixAble to measure entire scattering matrix– Much more information of scattering mediumMuch more information of scattering medium
Standard Base Moments: ZStandard Base Moments: ZHH, V, VHH, W, WHH
Polarimetric Base Moments : ZPolarimetric Base Moments : ZDRDR, , DPDP, , HVHV, L, LDRDR
– Estimate the average Drop Size DensityEstimate the average Drop Size Density– Identify average particle shape Identify average particle shape Hydrometeor Classification Hydrometeor Classification– Immunity from beam blockageImmunity from beam blockage– Variables change due to rainfall Variables change due to rainfall Much better rainfall Much better rainfall
Raindrops are oblate spheroidsRaindrops are oblate spheroids
Horizontal Returns greater than vertical returnsHorizontal Returns greater than vertical returns Phase shift in horizontal is more than in vertical Phase shift in horizontal is more than in vertical
DPDP increases with range through rain increases with range through rain
HistoryHistory 1990 – Watershed Authorities created throughout state1990 – Watershed Authorities created throughout state
– After devastating Elba Flash FloodsAfter devastating Elba Flash Floods– CPYRWA only active authorityCPYRWA only active authority
SE AL SE AL only region in the state with extensive data on its water only region in the state with extensive data on its water resources and needsresources and needs
– Initially just Choctawhatchee – Pea RiversInitially just Choctawhatchee – Pea Rivers– Started with 3 rain gaugesStarted with 3 rain gauges
1994 - COE Installed Network of Stage and Rain Gauges1994 - COE Installed Network of Stage and Rain Gauges 1997 – Yellow River Added1997 – Yellow River Added 1998 – Major Flood1998 – Major Flood 2005 – Conecuh River under consideration2005 – Conecuh River under consideration
EDRP-9 Signal ProcessorEDRP-9 Signal ProcessorIntermediate Frequency 60.00 MHzDigitization rate 80 MHzLinear dynamic range >100 dBMinimum discernable signal <110 dBClutter suppression >50 dBRange resolution >45 metersPRF <250 Hz to >1300 HzPhase noise <-53 dBc integrated over the
2 Installed2 Installed– UK Met (250 kW)UK Met (250 kW)– EEC (1 MW)EEC (1 MW)
2 more installations this year2 more installations this year– Valpraiso University (Indiana, USA) (1 MW)Valpraiso University (Indiana, USA) (1 MW)– Austria (250 kW)Austria (250 kW)
– UniversitiesUniversities University of South AlabamaUniversity of South Alabama University of Alabama - HuntsvilleUniversity of Alabama - Huntsville Auburn UniversityAuburn University University of Alabama - TuscaloosaUniversity of Alabama - Tuscaloosa
– Federal AgenciesFederal Agencies NASANASA
– State Agencies State Agencies Watershed Management AuthoritiesWatershed Management Authorities State EMAState EMA
– Local AgenciesLocal Agencies County EMA’sCounty EMA’s Local First RespondersLocal First Responders
– EECEEC
Integration Research LaboratoryIntegration Research Laboratory Fully integrated and Fully integrated and
operational operational hydrometeorological hydrometeorological forecasting centerforecasting center
Located at EECLocated at EEC Operational testbed for new Operational testbed for new
technologytechnology Data freely shared with Data freely shared with
consortium partnersconsortium partners
– All data streams integratedAll data streams integrated SatelliteSatellite RadarRadar AWS sensorsAWS sensors NWPNWP