Comparative Precipitation Analysis and Validation of NEXRAD Stage

Comparative Precipitation Analysis and Validation of NEXRAD (Stage III) Data, Stream Flow Data, and Rain Gauge Data located in the San Antonio Basin Jayar S. Griffith

Next Generation Weather Radar WSR-88 D (NEXRAD) Resolution: 1, 2, 4 (km) Temporal Resolution: 6 -10 min Maximum Reflectivity Range: 143 miles Remote Sensing Radar emits energy 160 Radars http: //www. ncdc. noaa. gov Dr. Hongjie Xie

Z-R Relation Reflectivity receiver Z ed return Precipitation R pulse Standard Z = 300 R 1. 4 Tropical Z = 250 R 1. 2 Dr. Hongjie Xie

NEXRAD Products GRLevel. II Software Level II: Reflectivity Product Level III: Rainfall Product Stage I: Hourly Digital Precipitation (HDP) Stage II: HDP Merges with Rainfall Gages Stage III: Mosaic Stage II cover a RFC area Stage IV: Mosaic Stage III for CONUS

Real Time NEXRAD DATA on the WEB http: //www. rap. ucar. edu/weather/radar

NEXRAD 0. 5 Base Reflectivity http: //www. rap. ucar. edu/weather/radar

Area of Study San Antonio Basin Watershed

San Antonio Basin Sub-Regions Jayar S. Griffith

San Antonio Basin Major River System Jayar S. Griffith

National Weather Service Rain Gage Network

Hourly Rain Gage Data COOP ID Rain Gage Station Data unavailable on Internet No Rain Gage Validation http: //nndc. noaa. gov

USGS Stream Flow Data in Hourly Discharge (cfs) is only available within the past 31 days Data must be downloaded monthly http: //waterdata. usgs. gov/nwis/rt

Analysis of Stream Flow Data Stream Flow USGS Gage: 08181500 Discharge, cfs Hour USGS 8181 500 10/23/2004 15: 15 4. 6 3 208 16 USGS 8181 500 10/23/2004 15: 30 4. 7 7 230 16 USGS 8181 500 10/23/2004 15: 45 4. 8 8 248 16 USGS 8181 500 10/23/2004 16: 00 4. 9 8 265 Discharge, cubic meters 16 951 16 Total USGS 8181 500 10/23/2004 16: 15 5. 0 2 272 17 USGS 8181 500 10/23/2004 16: 30 5. 0 6 279 17 USGS 8181 500 10/23/2004 16: 45 5. 0 6 279 17 USGS 8181 500 10/23/2004 17: 00 5. 0 7 281 269. 29 1) Download Hourly Stream Flow Data 2) Convert Text file to Excel 17 1111 17 Total 314. 60 USGS Stream Flow Data http: //waterdata. usgs. gov/nwis/rt

Where to Download NEXRAD Data Monthly-Hourly Rainfall Data is compressed multi-tarred files http: //dipper. nws. noaa. gov/hdsb/data/nexrad/wgrfc_stageiii. html

Data Collection and Analysis Establish NEXRAD Stage III Database Download Rainfall Data from NOAA (Compressed and Multi-tarred Binary file) stage 3_102004_WG. tar Uncompress Multi-tarred Binary file by automated data conversion designed by Dr. Hongjie Xie Uncompressed ASCII to GIS Grid – 1. 3 Gb Workflow of Data Conversion Re-projection from Polar-stereographic to Texas Centric NAD 83 Albers Dr. Xie

ASCII files to GIS Grid Files

NEXRAD Projected in GIS Re-Define Arcview Shapefiles to equal NEXRAD Projection. GCS_NAD 83 to Albers

Pixel Value of NEXRAD Data (4 km)

GIS Spatial Analyst • 2 km Buffer was created for each Sub-Region • Zonal Statistic for each Buffer vs Hourly Precip Data Zonal Statistics

Analysis of Rainfall Data and Stream Flow Data NEXRAD Rainfall Data Zonal Statistics with "Medina_L 2_Buffer" Medina Area = 3. 49801 X 10^9 sq meters (sum x area = cubic meters) Zonal Statistic Hourly Precip. Hour sum, mm sum, m Area NEXRAD (volume cubic m) r 10242004_16 z 16 0 0 3. 49801 E+09 0. 00 E+00 r 10242004_17 z 17 0 0 3. 49801 E+09 0. 00 E+00 r 10242004_18 z 18 1. 75 0. 00175 3. 49801 E+09 6. 12 E+06 r 10242004_19 z 19 37. 12 0. 03712 3. 49801 E+09 1. 30 E+08 r 10242004_20 z 20 618. 54 0. 61854 3. 49801 E+09 2. 16 E+09 r 10242004_21 z 21 1656. 59 1. 65659 3. 49801 E+09 5. 79 E+09 r 10242004_22 z 22 1350. 61 1. 35061 3. 49801 E+09 4. 72 E+09 r 10242004_23 z 23 834. 82 0. 83482 3. 49801 E+09 2. 92 E+09 r 10252004_00 z 0 439. 24 0. 43924 3. 49801 E+09 1. 54 E+09 r 10252004_01 z 1 570. 25 0. 57025 3. 49801 E+09 1. 99 E+09 r 10252004_02 z 2 333. 6 0. 3336 3. 49801 E+09 1. 17 E+09 r 10252004_03 z 3 67. 33 0. 06733 3. 49801 E+09 2. 36 E+08 r 10252004_04 z 4 0. 18 0. 00018 3. 49801 E+09 6. 30 E+05

Analysis of Rainfall Data and Stream Flow Data 1) Preliminary Statistics NEXRAD (volume cubic m) Discharge, cubic m 0. 00 E+00 293. 36 2. 16 E+09 293. 36 5. 79 E+09 287. 42 4. 72 E+09 266. 46 2. 92 E+09 253. 44 1. 54 E+09 258. 82 1. 99 E+09 255. 13 1. 17 E+09 250. 32 2. 36 E+08 243. 81 6. 30 E+05 Need further analysis. Repeat Methods for month of November 315. 73 1. 30 E+08 ? Problem with Stream Flow Data, NEXRAD Data, or Projection ? 314. 60 6. 12 E+06 Increase in Precipitation = Increase in Stream Flow 269. 29 243. 81

Revised NEXRAD vs Stream Flow Central Time Zone to UTC 2) Adjusted Statistics NEXRAD (volume cubic m) discharge, m 0. 00 E+00 0 6. 12 E+06 173341. 7867 1. 30 E+08 3676826. 928 2. 16 E+09 61267902. 16 5. 79 E+09 164089297. 4 4. 72 E+09 133781228. 9 2. 92 E+09 82690965. 95 1. 54 E+09 43507797. 95 1. 99 E+09 56484659. 37 1. 17 E+09 33043897. 18 2. 36 E+08 6669201. 429 6. 30 E+05 Zonal Statistic vs. Adjusted USGS Hourly Discharge 0 17829. 44092

Results Preliminary Results ► Ground-truthing is needed to validate NEXRAD data ► NEXRAD can be used when stream flow gages and rain gages are not available ► Hourly Rain Gage Data is not free or available through NOAA website ► Hourly Stream Flow Data must be downloaded monthly ► NEXRAD Rainfall Data are large files (> 1 Gb) ► Stream Flow data does not correlate with NEXRAD data ► Method must be repeated for month of November ► Problem with Projection in GIS Albers to Polar-stereographic GIS ► Develop a Geodatabase on a local server Final Results ► ► ► Linear Relationship of NEXRAD Stage III data vs Stream Flow data USGS Stream Gage hours adjusted to Universal Time Zone Relationship shows that Increase Precipitation = Increase in Stream Flow

Cibolo Creek at Selma Guadalupe River at New Braunfels Satellite Remote Sensing Water Vapor Satellite Photos 715 AM CDT Fri Jul 5, 2002 http: //www. srh. noaa. gov/ewx/html/wxevent/2002/julfld 2002. htm

GOES Remote Sensor http: //www. goes. noaa. gov

Reference Habib, E. and W. F. Krajewski, 2002. Uncertainty Analysis of the TRMM Ground. Validation Radar-Rainfall Products: Application to the TEFLUN-B Field Campaign. Journal of Applied Meteorology 41: 558 -572. Grassotti, C. , R. N. Hoffman, E. R. Vivoni, and D. Entekhabi, 2003. Multiple Timescale Intercomparison of Two Radar Products and Rain Gauge Observations over the Arkansas-Red River Basin. Weather and Forecasting 18(6): 1207 -1229 ESRI Arc. GIS 9 Xie, H. , Xiaobing, Z. , Vivoni, E. R. , Hendrickx, J. M. H, Small, E. E, 2004. GIS-based NEXRAD Stage III precipitation database: automated approaches for data processing and visualization. Xie, H. , Xiaobing, Z. , Vivoni, E. R. , Hendrickx, J. M. H, Guan, H. , Tian, Y. Q. , Small, E. E. Comparison of NEXRAD Stage III and Gauge Precipitation Estimates in Central New Mexico San Antonio River Authority. Regional Watershed Modeling System Master Plan. Section 5 NOAA Website Available at http: //www. srh. noaa. gov/forecasts/TXZ 205. php? warncounty= TXC 029&city=San+Antonio USGS Water Resource Website Available at http: //waterdata. usgs. gov/nwis/rt Weather Underground http: //www. wunderground. com/radar/help. asp#base_reflectivity