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Dr. Luke Madaus -- 16 May 2019 -- Sea Level Solutions Center Rainfall Workshop

A hybrid dynamical-statistical analog downscaling technique to efficiently explore changes in extreme precipitation. Dr. Luke Madaus -- 16 May 2019 -- Sea Level Solutions Center Rainfall Workshop.

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Dr. Luke Madaus -- 16 May 2019 -- Sea Level Solutions Center Rainfall Workshop

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  1. A hybrid dynamical-statistical analog downscaling technique to efficiently explore changes in extremeprecipitation Dr.LukeMadaus--16May2019--SeaLevelSolutionsCenterRainfallWorkshop

  2. Jupiter FloodScore Planning providesphysical floodrisk at street-levelresolution

  3. PhysicalhazardsthatdrivefloodinginS.Florida • Extremerainfall • Coastalsurge • resultingfromtropicalcyclones • Seasonal (‘king-tide’)flooding

  4. Jupiter MethodOverview Goal:Howareextremeprecipitationeventsexpectedto changeinfrequencyandmagnitudeinafutureclimate?

  5. Jupiter MethodOverview Goal:Howareextremeprecipitationeventsexpectedto changeinfrequencyandmagnitudeinafutureclimate? Definecriteriaforcandidate“extremeprecipitation”events Produceandtunedynamically-downscaledsimulations(to~1km resolution)forhistoricaleventsthatmeetthesecriteria Projectchangesineventfrequencywithanalogmethod Projectchangesineventmagnitudewithstatisticalscaling Produceclimatestatisticsandfeedintofloodmodels

  6. Selection of extremeevents

  7. Selection of ExtremeEvents AlleventswhereeitherMiami-DadeorMiamiBeachASOS/GHCNstations showatleast30mmofprecipitationin24hours FloodreportstoNCEI/NCDC rarebelowthislevel

  8. Dynamical downscalingof historicevents

  9. WRF DownscaledSimulations • Downscalehistoriceventsfromreanalysesto1kmgridspacing • ChooseWRFconfigurationsuitedto South Florida’sclimate • Convection-allowingmodel resolution • Cancaptureindividualthunderstorms • GoddardMicrophysics • Designedforsubtropicalwarmrain • NoahLandSurfaceschemewith NationalLand Cover Dataset • Satellite-basedestimatesofland surfaceproperties

  10. WRF DownscaledSimulations Choose configurations for WRF best suited to South Florida’sclimate(e.g.warm rain processesdominate)

  11. WRF 1-hr PrecipitationDistributions

  12. WRF 24-hr PrecipitationDistribution WRFunderdoesmoreextremehourly and24-hourprecipitationamounts Bias correction through quantile mappingcanalleviatemuchofthis

  13. Changes in eventfrequency with an analogfinder

  14. AnalogFinder Use a global climate model (here, the CESM-LENS; Kay etal.2015)andmatchfuture days to historicones Representative analog precipitation field“matches” Cross-validationtechnique to determine optimum predictors for analog matches

  15. Analog EventDurations Mostly 1-2 day events, afew 5-7 dayevents

  16. AnalogFinder Analogs are found after bias correctingtheclimatemodeland arecomputedbasedonanomalies The analog finder samples the historical spectrum of possible extremeprecipitationeventswell

  17. AnalogEventsSelectedperYear Analog resampling alone does not find an increase in the annual frequency of extreme precipitation events ->Mostextremeprecipitationevents in South Florida is determined by localized thunderstorms/convection and not by large-scale atmospheric patterns

  18. Changes in eventmagnitude with statisticalscaling

  19. FutureScaling • Analog-based samplingonly samples historicalevents • Given the same “historical” eventinthefuture,weexpect theeventtoevolvedifferently inafutureclimate • Needtocorrectforlocal thermodynamicchanges

  20. FutureScaling • Leverage existingdynamically-downscaled datasetstoexplorethesechanges • Liuetal.(2017)dynamicallydownscaled dataset over NorthAmerica • “Recent”climate(2000-2013)and “End-of-Century” climate(~2090) • Same sequence of large-scale weather patterns,butwithend-of-centuryclimate • Cancomputescalingfactorsforlocalized precipitation • Increaseinextreme(>93rdpercentile;~10mm)hourly precipitationamounts

  21. Projections andapplications

  22. FutureProjections Combine analog and scaling methodstoproducedownscaled futureprojections <-Example:Numberofdays with non-zero precipitation decrease,butdayswith>30 mm of precipitation can possiblyincrease

  23. Applications atJupiter We use our library of analog-draw and amplitude scaled precipitation events as inputstohydraulicmodelstotranslateprecipitationchangestofloodriskchanges Can also search for frequency of“design” storms Example:5.7inchesin1hr

  24. Jupiter MethodHighlights • Efficient--computationalexpenseismainlylimitedtohistorical simulationsand analog search • Calibrated--rootingthemethodinhistoricaleventsallowsfor calibration againstobservations • Projectionindependent--anyglobalclimatemodelcanbeusedinthe analogfinder • Buildsonexistingdatasetsandacademicwork--previousworktobuild dynamicdownscalingdatasetscanbebuiltuponandexpandedwiththis method

  25. References • Liu, C., Ikeda, K., Rasmussen, R., Barlage, M., Newman, A.J., Prein, A.R., Chen, F., Chen, L., Clark, M., Dai, A., Dudia, J., Eidhammer, T., Gochis, D., Gutmann, E., Kurkute, S., Li, Y., Thompson, G., Yates, D., 2017. Continental-scale convection-permitting modeling of the current and future climate of north america. Clim. Dynam. 49,71–95. • Kay, J.E., Deser, C., Phillips, A., Mai, A., Hannay, C., Strand, G., Arblaster, J., Bates, S., Danabasoglu, G., Edwards, J., Holland, M., Jushner, P., Lamarque, J.F., Lawrence, D., Lindsay, K., Middleton, A., Munoz, E., Neale, R., Oleson, K., Polvani, L., Vertenstein, M., 2015. The Community Earth System Model CESM Large Ensemble Project: A community resource for studying climate change in the presence of internal climate variability. Bull. Amer. Meteor. Soc. 96,1333–1349. • Skamarock, W.C., Klemp, J.B., Dudhia, J., Gill, D.O., Liu, Z., Berner,J., Wang, W., Powers, J.G., Duda, M.G., Huang, D.M.B.X.Y.,2019.A description of the advanced research WRF Version 4. Technical Report TN-556. National Center for Atmospheric Research.doi:DOI:http://dx.doi.org/10.5065/1dfh-6p97

  26. Modelingstreet-levelflood-perilwithclimatechange: Precipitation-basedflooding Extreme precipitation events We develop a catalog ofhistoric extreme precipitation eventsinthelocal area based on observations Eventsimulation: WRF H&Hmodeling: HEC-RAS Analog-based resampling forfuture frequency Scaled precipitation distributions forfuture intensity The Weather Research and Forecasting(WRF) model is used to simulate historical eventsatkilometer and hourlyscales Climate model projections are used to evaluate howfrequently eventslikethishistorical events will occur in the future Climate model simulations are usedto determine how the future intensity of rainfall will change locally 2Dmodeling forced by scaled WRF precipitation output

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