OUTLINE Brief review of Space-borne QPE (TRMM/GPM)

1. Cross Validation of Space Radar and Ground Polarimetric Radar: A Norman Ground Validation Super Site for Satellite QPE? • Yang Hong and Berry Wen, School of Civil Engineering and Environmental Science, Center for Natural Hazards and Disaster Research • http://nhdr.ou.edu and http://hydro.ou.edu • G. Zhang, ARRC and School of Meteorology • T. Schuur and J. J. Gourley, National Severe Storms Laboratory and CIMMS • OUTLINE • Brief review of Space-borne QPE (TRMM/GPM) • Cross Validation of Space Radar and Ground Pol-Radar • The way forward (Challenges/Opportunities) 2009 International Symposium on Radar and Modeling Studies of the Atmosphere……. November 10-12, 2009, Kyoto, Japan

2. Multiple Sources for QPE Observations Near Polar Orbiting Satellite PMW and Space Radar Geosynchronous Satellites VIS, IR, Sounding Radar Gauge Precipitation is arguably the most important hydro-meteo-climatic variable; Precipitation measurement is among the KEY challenges, particularly in high altitude / latitude, over ocean, complex terrains and remote regions. LABZ

3. Current Global Satellite Precipitation Products • Precipitation for Climate Studies (2.5ox2.5o Monthly; from 1979 - current ) • GPCP Version 2 (Adler et al., 2003) • NOAA CMAP Precipitation (Xie and Arkin, 1997) • NASA GSFC 1o Daily (Huffman et al., 2001) • High-Resolution Precipitation (for Weather & Hydrology) • NOAA NESDIS HE, 1-h, 0.04o (Vicent et al., 1998) -- NASA GSFC TRMM 3-h, 0.25o (3B42RT) (Huffman et al., 2002) • US/NRL 1-h, 0.1o (Turk et al., 2002) • UK Birmingham, 1-h, 0.25o (Tapoador et al., 2002) • NOAA CMORPH, 1-h, 0.08o (Joyce et al., 2004) (…have been involved in: ) • UA PERSIANN: 3-h, 0.25o (with Sorooshian et al. 2002) • UC Irvine CONUS CCS, 1-h, 0.04o, (Hong et al., 2004) • UC Irvine Global CCS, 1-h, 4-km (Hong et al., 2005) • NASA TRMM MPA, 3-h, 0.25o, (with Huffman et al. 2007)

4. http://eos.ou.edu/globalp.html

5. 2005 Joined NASA TRMM Group: Precipitation Constellation (9-satellites) With Huffman et al. 2007 JHM : TRMM-based Multi-satellite Precipitation Analysis Calibrate High-Quality (HQ) Estimates to “Best” Space Radar Instant-aneous SSM/I TRMM AMSR AMSU GOES NOAA GMS/MTSAT (Japan) 30-day HQ coefficients DMSP Aqua METEOSAT (Europe) Merge HQ Estimates 3-hourly merged HQ TRMM Match IR and HQ, generate coeffs Hourly IR Tb 30-day IR coefficients Apply IR coefficients Hourly HQ-calib IR precip Merge IR, merged HQ estimates 3-hourly multi-satellite (MS) Compute monthly satellite-gauge combination (SG) Monthly gauges Monthly SG Rescale 3-hourly MS to monthly SG TMPA-RT (mm/h) 18UTC 22 May 2002 TMPA-RT (mm/h) 15UTC 22 May 2002 Rescaled 3-hourly MS TMPA-RT (mm/h) 12UTC 22 May 2002 TMPA: quasi-global real-time update at http://trmm.gsfc.nasa.gov TMPA uses 4 Polar-orbital microwave satellites (NOAA, DoD, NASA) and 5 Geo-IR satellites (GOES8-10, GMS, MYSAT, MeteoSAT); all calibrated by TRMM Preci Radar 11+ years (‘98-09’) of 3-hr data available; Most requested TRMM product from NASA

6. TRMM Space Radar: Single path covered four different Storms/Hurricanes

7. Space-borne and Ground-based Radar • GR since WWII; but the very first space-borne weather radar , Precipitation Radar (PR), onboard NASA Tropical Rainfall Measuring Mission (TRMM) launched Nov 1997, also called space rain gauge (benchmark/calibrator for other IR/PMW space sensors). • As remote sensing systems, GR/SR share many similarities-Complimentary; still many technical challenges that have to overcome before a globally coordinated space-ground QPE observation network could be realized in the future. Image courtesy: OU ARRC and NASA TRMM

8. NASA/JAXA’s TRMM (Launched in Nov. 1997~) Carries the first space-borne weather radar called Precipitation Radar (PR). PR: a 2-mphased array radar system (128-element slotted wave guide array antenna) at 13.8GHz Ku-band; 215-km swath, with vertical and horizontal resolutions of 250m and 4.3 km, respectively at nadir; Cross-track scanning TRMM Microwave Imager (TMI) is a multichannel (10.7, 19.4, 21.3, 37, 85.5 GHz), dual-polarized microwave radiometer; Conical scanning The PR together with TMI and Visible/Infrared channels are theprimary data set for precipitation measurement and are also utilized for deriving precipitation vertical profiles.

9. POTENTIAL ROLE OF DUALPOLARIZATION RADAR IN THE VALIDATION OF SATELLITE PRECIPITATION MEASUREMENTS Rationale and Opportunities: Ground based radar, particularly dual-polarization radars provide physical insight into the development and interpretation of space-borne precipitation measurements Credit: V. CHANDRASEKAR and A. HOU et al. 2008,BAMS

10. Linking Satellite and Ground Pol- Radar • To compare and resolve discrepancies in hydrometeor and reflectivity observations between GR (OU’/KOUN) and TRMM KU PR and future GPM Dual-Frq KU/KA PR. • Vertical Profile Reflectivity comparison: • Data from TRMM PR 2A25 compared with GR volume scan data. • Hydrometeor classification comparison: • Quantitative hydrometeor vertical profiles from TRMM 2A23 compared with qualitative information from Ground Pol-Radar. • Surface Rain Rate comparison: • Data from TRMM 2B31 compared with GR at 0.5 elevation angle.

12. OU-PRIME vs. TRMM PR ARRC: The University of Oklahoma Polarimetric Radar for Innovations in Meteorology and Engineering Early OU’ surface reflectivity data, though not extensively calibrated, matched well with TRMM PR statistically

13. VPR: TRMM PR vs. OU-PRIME • OU’ better resolved the brightband feature • OU’ higher sensitivity at low Ref. range • Good agrrement at high dBZ range

14. KOUN Polarimetric Radar Events • Improved data quality (removes artifacts) • Identification of hydrometeors (rain, ice, hail)

15. TRMM PR vs. KOUN Reflectivity May 15, 2005, MCSKOUN Raw Reflectivity

16. KOUN HCA: Hydrometer Types based on Polarimetric Echo Classification AP TRMM PR Reflectivity Over classification/filtering: though moved the ground clutter Possible Wrong classification GIANGRANDE and RYZHKOV, 2008, Estimation of Rainfall Based on the Results of Polarimetric Echo Classification, JAMC

17. KOUN reflectivity (before and after HCA filtering) Comparison to TRMM PR TRMM PR Reflectivity Before and After HCA filtering CC=0.83 Bias = 3.8% RMSE=7.83 CSI=0.67 CC=0.88 Bias = 2.4% RMSE=7.40 CSI=0.87

18. TRMM Provides Quantitative Hydrometeor InfoTRMM estimated Cloud (Precip) Ice/Water; PR 2A23 provide 0o line and Bright-band Boundary

19. TRMM-KOUN Vertical Hydrometers Inter-comparison TRMM simulated Cloud/Precip Ice/Water;PR 2A23 provide 0o line and Bright-band Boundary Beam sampling HCA algorithm Beam sampling Reduced to four equivalent types, show good qualitative comparison overall; KOUN HCA miss-classification (melting snow to cloud ice or graupel) KOUN also showing sawtooth-like features KOUN detected lower brightband, possible due to radar beam sampling issue.

20. Reflectivity Vertical Profile Comparison TRMM PR

21. Reflectivity Vertical Profile Comparison

22. TRMM PR 2A23 provide convective or stratiform surface rainfall info Overall good match; better agreement at higher range for both types Convective Type Stratiform Type

23. KOUN Pol- Radar Rainfall Algorithms R(gag) = IDW on Micronet Gauges 1. NEXRAD; Z=300R1.4 2. 3. JPOLE; Ryzhkov et al. (2005a) JPOLE; Ryzhkov et al. (2005a) 4. 5. Bringi and Chandrasekar (2001) R(Z,ZDR|JPOLE,HCA)=#4, #3 in hail Giangrande and Ryzhkov (2008) 6. R(Z,ZDR|BC,HCA)=#5, #3 in hail Giangrande and Ryzhkov (2008) 7. R(syn) Ryzhkov et al. (2005b) 8.

24. Surface Rain Rate comparison Polarimetric radar QPE shows closer match with PR at low end and high rain rate range

25. Invite synergistic use of space and ground radars: discrepancy/similarity (complimentary) • Compared to Z-R, KOUN Polarimetric radar QPE show closer match at low and high rain rate range with space radar • Space Radar can be used to evaluate/improve detection of ground pol-radar (KOUN) hydrometers (either due to HCA algorithm miss-classification, beam sampling issues, or both?) • Space radar can contribute to resolve GR bright-band at medium and far range (potential to detect surface precip types) • Planned future research: • Dual-Frequency Space Radar vs. Dual-Polarization Radar • OU’ in 2011 MC3E Field Campaign: Particularly, OU’ will cross-validate with NASA planned satellite-pixel scale dense array of disdrometers with focus on sub-pulse volume scale variability and impacts on DSD retrieval. Summary and Planned Work

26. Future: From Tropical (TRMM) to Global Precipitation Measurement (GPM)1998~~~2012 (TRMM) 2007(delayed to 2013)~~GPM GPM, the next generation of Satellite Constellation, is an expanded mission of the current TRMM, to measure global precipitation (rain, snow, and ice) Core-Sensor: Dual-Frequency Precipitation Radar (DFPR) (Ku-Band-13.6 GHz; Ka-Band-35.55 GHz)) DFPR will act as benchmark sensor to calibrate GPM and other satellite sensors of the constellation GPM Targets: + Natural Hazards + Hydrology+ Weather Forecasting + Water Resources NASA PMM TRMM/GPM Science Team Member

27. Global Precip- Measurement (GPM) Challenge/Strategy • Pre-launch algorithm development and post-launch product evaluation • A Ground Validation Super Site for Satellite QPE? • Oklahoma provides a unique suite of state-of-the-art ground precipitation measuring facilities, including polarimetric radars (S-band KOUN, C-band OU-Prime, X-band mobile radars), disdrometers, a radar profiler, NWRT, as well as Micronet and Mesonet gauges. Four approaches: • Radar Network (surface): direct statistical validation to resolve their first order discrepancies (bias); • Physical process studies (Vertical column): cloud system and microphysical studies toward refinement of physical-based retrievals • Field campaign (multi-sources):2011 MC3E Field Campaign • Integrated hydrologic validation (4-dimensional): data assimilation into hydrometeorological prediction models to evaluate the strengths and limitations. • Towards a globally coordinated space-ground QPE observation network

28. Thank you for your attention! • Comments and questions? • Yang Hong • Contact: • yanghong@ou.edu • http://hydro.ou.edu : Remote Sensing Hydrology Group Site • http://eos.ou.edu: Satellite Earth Observing System and real-time Prediction Site 2009 International Symposium on Radar and Modeling Studies of the Atmosphere……. November 10-12, 2009, Kyoto, Japan