1. Status of S-PolKa Data Sets Bob Rilling, Mike Dixon, Scott Ellis, John Hubbert and Scot Loehrer EOL, NCAR, Boulder, CO DYNAMO radar workshop University of Washington, Seattle 22-24 August 2012

2. QC-1 Data Set QC version 1 data set released July 7 Format is CfRadial – http://www.ral.ucar.edu/projects/titan/docs/radial_formats/CfRadialDoc.pdf Times are given in UTC – Filename contains start and end times of volume: cfrad.20111210_063031.993_to_20111210_063528.867_SPOL_v9373_SUR.nc – Time variable in file is relative to the start time Available for download: – URL: http://data.eol.ucar.edu/codiac/dss/id=347.017http://data.eol.ucar.edu/codiac/dss/id=347.017 – Max download per session: 16 GB – Mean data size per observed data: 7 GB Available on ~1 TB USB external disks containing: – QC version 1 data set – Image browser – Web cam images

3. QC-1 Data Set Web documentation is available at: http:// www.eol.ucar.edu/projects/dynamo/spol/SpolKa_DYNAMO_UsersGuide.toc.html http:// www.eol.ucar.edu/projects/dynamo/spol/SpolKa_DYNAMO_UsersGuide.toc.html This contains: – Project information – Data set description – Data quality and calibration reports – Download procedures – Links to format documents

4. Summary of Data Quality and Calibration Procedures Tower targets: for checking range accuracy Solar scans: for pointing, leveling and power calibration Engineering calibration for S-band and Ka-band S and Ka systems sensitivity checks S/Ka comparisons Self-consistent method for S-band calibration (PHI-cal) Vertical pointing for Zdr bias determination LDR sensitivity check Monitoring using Automated Test Equipment (ATE) Monitoring of data transfer and recording

5. Spol-Ka QC-1 fields

6. Overview of Changes/Improvements Merged data set created: – S-band data – Ka-band data – PID – Rain rates Noise power for all S-band and Ka-band power quantities has been re-estimated on a beam-by-beam basis impacting: – all noise-power corrections – censoring/thresholding at low measured powers. Advanced techniques for data censoring have been developed, resulting in a more reliable elimination of bad data. A new and improved computation of radial velocity was developed

7. Overview of Changes/Improvements A new and improved computation of correlation coefficient was developed Ka-band reflectivity was corrected to account for the change in magnetron – Changed by ?? dB on ????? S-band atmospheric attenuation was estimated using Doviak and Zrnic (Doppler Radar and Weather Observations, 2nd ed., 1993, pp44-45) – Applied to reflectivity data (DBZ_S) – Uncorrected data also included (DBZ_NAA_S) Test pulse removed S-band power and Zdr calibrations unchanged from the field data

8. Known Issues Beam blockage Ka-band sensitivity KDP estimation

9. Vertically Pointing Zdr Calibration Rain looks spherical at vertical incident – Intrinsic Zdr = 0 dB – Can be used to calibrate Zdr 29 vertical data collections Mean offset of 0.2844 removed from Zdr data throughout project Std dev = 0.0112 dB Max – Min = 0.0370 dB

10. Self-consistency Calibration Used as a calibration check Utilize relationship between Z, Zdr and Kdp – Kdp = aZ b Z dr c – Zdr is independently calibrated – Kdp is independent of calibration Integrate computed Kdp with range to obtain  DP Use rays with large  DP Compare computed and measured  DP DateTime (UTC)Estimated bias (dB) Oct 12, 20111400 to 15000.43 Nov 17, 20112000 to 21000.21 Dec 23, 20111745 to 18000.01

11. Comparison of Ka-band Z to S-band Z Used as a calibration check Compare S- and Ka-band reflectivity Rayleigh scattering only Account for atmospheric attenuation at Ka-band – Use Liebe microwave propagation model – Compare Z at close ranges – Near sounding time and site Bias < 0.5 dB Date/timeMean bias (dB)Variance (dB)Number of comparisons 2011 1223 06050.120.6615 2011 1223 10500.050.736 2011 1223 10200.450.233 2011 1223 16050.080.2614 2011 1223 16500.110.135 2011 1008 2005-0.330.0565 2011 1017 17200.390.4012 2011 1106 19200.280.896 2011 1107 23350.220.7812