Initial Evaluation of the HIAPER Cloud Radar Doppler Velocity Measurements S. M. Ellis, J. Vivekanandan, P. Tsai, E. Loew, C. Burghart, M. Dixon, J. Emmett, M. Strong and W.C. Lee

HIAPER Cloud Radar NSF deployment pool instrument – Requestable community resource Contact Vivek, Contact Scott Ellis, – Presentation: Requestable NSF Lower Atmospheric Observing Facilities for Scientific Research and Project-based Education - Tuesday, 17 September :30pm in Colorado Ballroom V

HCR System Overview Deployable on NCAR GV, High-performance Instrumented Airborne Platform for Environmental Research (HIAPER) – Pod-based (under wing) – Other aircraft that can support large pod Deployable on ground – Vertical pointing – Container houses both HCR and HSRL Coincident radar/lidar facilitates particle size estimates in liquid and ice (e.g. Donovan et al, 2001; Tinel et al. 2005; Eloranta et al. 2007; Delanoe and Hogan, 2008) Dual-polarization – Currently LDR mode

HCR System Overview W-band Scanning in azimuth – Mechanical scanning nominally 30 deg/sec but up to 60 In-flight, real-time aircraft attitude adjustment

High-performance Instrumented Airborne Platform for Environmental Research (HIAPER) 5,600 pounds (2,540 kilograms) Payload – For example: HCR, HSRL and microphysics/chemistry probes Max altitude 51,000 ft (less with full payload) Range of about 7,000 miles (11,265 kilometers)

HCR System Overview ParameterSpecification Antenna0.3m, Cassegrain Antenna gain46.2 dB Antenna 3 dB beam width0.7 degrees Transmit frequency94.4 GHz TransmitterKlystron Peak power1.6 kW Pulse width 0.2 – 1.0  s PRF1 – 10 kHz System noise power-106 dBm Range resolution30 – 150 m Sensitivity-39.6 dBZ at 1 km

Simulations of Performance Developed program to estimate measurement errors for different operating parameters – Navigation correction accuracy Pitch Roll Drift – Pointing accuracy – Measurement variance Dwell time Spectrum width – Unknown winds not at flight level Wind

Calibration and Ground Tests Engineering calibration Comparisons with Wyoming Cloud Radar (WCR) Real-time system monitoring For details see poster #305 Thursday at 1:30PM by Pei- Sang Tsai WCR Power, dBm HCR Power, dBm

Navigation Correction C-Migit INS/GPS system – Located at reflector for negligible moment arm – Size fits in the pod – Performance is quite good 100 Hz data Accurate to about 0.01 deg Real-time correction of pointing angle – Keeps antenna pointing in desired direction – Helps mitigate the cross wind errors Wind

Time Series Recording The HCR records the I and Q time series data for all flights – Enables investigation of advanced signal processing – Benefits data quality Spectral display tool has been developed

Test Flights Completed - SAANGRIA Test flights completed in February and March 2013 EMI tests Radar ran reliably – Pressure leak Antenna fixed at near nadir Flight patterns for pointing calibration performed based on Haimov and Rodi (2013) – Uses ground echoes – need flat terrain, with no forest, no water – Straight and level upwind/downwind – Straight and level cross wind – Left and right circles with roll angles ~ 20 to 30 deg Calibrated pointing following Haimov and Rodi (2013) Corrected radial velocity for aircraft motion following Lee et al. (1993) Analyzed ground echo velocity on other data sets

Test Flights Completed - SAANGRIA Ground echoes: Mean Vr = m/s Std dev Vr = m/s Var Vr = m/s (10 minutes of data over level ground)

Test Flights Completed - SAANGRIA Verified sensitivity - ongoing Spectra checked for spurious artifacts

Test Flights Planned- IDEAS IV Beginning this week! (delayed by floods) First implementation of real-time pointing correction First test of scanning capability Correction of issues identified during SAANGRIA – Pressure vessel leak – EMI

Future Plans Continue testing and verification of data quality – Calibration – Dual-pol – Navigation correction and pointing Deploy for CSET – Study stratocumulus clouds between California and Hawaii – Funded for summer of 2015 Add second wavelength – Beam- and resolution-matched Ka-band – Funding dependent

Thank You Questions? HCR pod Dropsonde Various probes

CSU-CHILL Comparison CHILL DataHCR Data GV Skin Paint Radius, km (approximate distance GV traveled in 60 sec) Time, seconds Altitude AGL, km