Using Independent NCDC Gauges to Analyze Precipitation Values from the

OneRain Corporation Algorithm and the National Weather Service Procedure

St M M ti itiSteven M. MartinaitisHenry E. FuelbergJohn L SullivanJohn L. Sullivan

Chandra S. PathakAmerican Meteorological Society – New Orleans, LA

ObjectiveWater management and regulatory decisions in Florida are made by the Department of Environmental Protection (FDEP) and fiveEnvironmental Protection (FDEP) and five Water Management Districts (WMDs)However FDEP and the WMDs use differentHowever, FDEP and the WMDs use different multi-sensor datasets for hydrologic modelingCan the two datasets be used interchangeably?Can the two datasets be used interchangeably?We compare and contrast the two datasets against an independent set of gaugesagainst an independent set of gauges

DatasetsFlorida State University Historical Dataset

Employs the National Weather Service (NWS) Multi-sensor Precipitation Estimator (MPE) algorithmsensor Precipitation Estimator (MPE) algorithmUses quality controlled (QC) hourly gauge data provided by the National Climatic Data Center (NCDC) and the WMDsFSU conducts a second QC of hourly gauges U h l di it l i it ti (HDPA )Uses hourly digital precipitation arrays (HDPAs)Final product is hourly on the ~ 4×4 km Hydrologic Rainfall Analysis Project (HRAP) gridRainfall Analysis Project (HRAP) gridHereafter denoted “FSU/NWS MPE”

DatasetsOneRain Corporation Algorithm

Algorithm is proprietary--little is known about its characteristicscharacteristicsProvides a near-real time and an end-of-month product (only evaluate the end-of-month product)Final end-of-month product is at 15 min intervals on a Cartesian 2×2 km gridH ft d t d “O R i ”Hereafter denoted “OneRain”

Example Monthly SumsFSU/NWS MPE OneRain

June 2005 June 2005

Independent NCDC Gauges

Evaluation over SFWMDThirteen NCDC daily yco-op gauges from 2004-2005E h dEach gauge records over different 24 h intervalsNot used in either multi-sensor algorithms

MethodologyPlace FSU/NWS MPE and OneRain data on same spatial and temporal resolution

S m OneRain 15 min data into ho rl inter alsSum OneRain 15 min data into hourly intervalsTransfer the OneRain data from its 2×2 km grid to the HRAP ~ 4×4 km grid using area weighted g g gaveraging in ArcGIS

Sum each multi-sensor product over the 24 h period of each NCDC gauge

ResultsStatistics for Combined Two Year Period of Gauges vs.

AlgorithmsTime Mean Difference (mm) Standard Deviation of R2

Period( )

Difference (mm)FSU/NWS

MPEOneRain FSU/NWS

MPEOneRain FSU/NWS

MPEOneRain

ALL 0.80 0.26 10.38 11.12 0.568 0.532WARM 0.98 0.12 11.87 12.51 0.500 0.472COOL 0.42 0.57 6.06 7.03 0.791 0.735

FSU/NWS MPE has larger mean differences, or bias, (positive values means multi-sensor is underestimating) but smaller standard deviations of those differencesbut smaller standard deviations of those differencesFSU/NWS MPE has larger R2 values

Results: Monthly Box-Whisker Plots esu ts o t y o s e otsMulti-sensor vs. NCDC

FSU/NWS MPE O R iFSU/NWS MPE OneRain

Top (bottom) of boxes represent 75th (25th) percentileT (b tt ) hi k t 90th (10th) tilTop (bottom) whiskers represent 90th (10th) percentile

Results: Monthly R2 Values

FSU/NWS MPE has greater R2 for 10 of 12 months (exceptions are August and December)(exceptions are August and December)Overall R2 characterize seasonal rainfall dynamics

Results: Time Series esu ts e Se esAccumulation for 2005 (2 of 13 Gauges)

F t L d d l O t L k 2Fort Lauderdale Ortana Lock 2

There are no coherent spatial patterns in accumulationThere are no coherent spatial patterns in accumulation differences

Results: Winter Case Studyesu ts te Case Study31 January to 1 February 2004FSU/NWS MPE O R iFSU/NWS MPE OneRain

Both multi-sensor schemes handle event very well compared to gauges (slope near 1.00 and R2 ≥ 0.90)Little difference between FSU/NWS MPE and OneRain

Hurricane Wilmau ca e aCase Study

Made landfall as a category 3 hurricane near Cape Romano, FL at 1030 UTC on 24 October 20052005Over a three day period, 15 of 39 daily gauge observations either were missing or reportedobservations either were missing or reported zero precipitation during the heavy rain event

Remains 24 daily gauge observations over a three y g gday period; only 10 of 24 gauges reported daily precipitation ≥ 10 mmC id d ti ti f i d d i iConsider under-estimation from wind-driven rain

Compare hourly multi-sensor data only

Results: Hurricane Wilmaesu ts u ca e aCase Study

P i t L df ll Aft L df llPrior to Landfall After Landfall0400 UTC 24 October 1200 UTC 24 October

Pixel-to-pixel comparison demonstrate that OneRain had greater values prior to landfall while FSU/NWS gMPE had greater values post-landfall, especially with the larger precipitation amounts

SummaryBoth multi-sensor products performed better during the cool season than the warm season

OneRain produced smaller mean differences while FSU/NWS MPE had smaller standard deviations of those differencesthose differencesFSU/NWS MPE had overall slightly greater R2

valuesBoth products under-estimated large precipitation amounts but FSU/NWS MPE appeared to handle the amounts betteramounts better

SummarySince the majority of differences are usually not major, the degree to which data from the two procedures can be used interchangeably depends on criteria specified by the userH thi i l i f thHowever, this is only a comparison of the precipitation input for hydrological modelsN d t d t i hi h l ith idNeed to determine which algorithm provides most accurate streamflow data for water management decisionsmanagement decisions

Ongoing ResearchCurrently inserting FSU/NWS MPE, OneRain, and rain gauge data at their native resolutions into the MIKE SHE hydrologic model

Results compared against observed streamflow data for the Big Cypress Basin which includes the Floridafor the Big Cypress Basin, which includes the Florida EvergladesDetermine the interchangeability of the two g yalgorithms from a hydrological standpoint

We thank the following organizations forWe thank the following organizations for their support of this project

South Florida Water Management DistrictSouth Florida Water Management DistrictFlorida Department of Environmental ProtectionNOAA / National Weather ServiceNOAA / National Weather Service

D.J. Seo (Office of Hydrologic Development)Jay Briedenbach (WFO – Boise)J d B db (S th t Ri F t C t )Judy Bradberry (Southeast River Forecast Center)Joel Lanier (WFO – Tallahassee)

United States Geological Surveyg yUniversity of Florida