initial evaluation of the hiaper cloud radar doppler velocity measurements
DESCRIPTION
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 - PowerPoint PPT PresentationTRANSCRIPT
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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
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HIAPER Cloud Radar
• NSF deployment pool instrument– Requestable community resource• http://www.eol.ucar.edu/• Contact Vivek, [email protected]• Contact Scott Ellis, [email protected]
– Presentation: Requestable NSF Lower Atmospheric Observing Facilities for Scientific Research and Project-based Education - Tuesday, 17 September 2013 6-7:30pm in Colorado Ballroom V
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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
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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
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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)
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HCR System OverviewParameter Specification
Antenna 0.3m, Cassegrain
Antenna gain 46.2 dB
Antenna 3 dB beam width 0.7 degrees
Transmit frequency 94.4 GHz
Transmitter Klystron
Peak power 1.6 kW
Pulse width 0.2 – 1.0 ms
PRF 1 – 10 kHz
System noise power -106 dBm
Range resolution 30 – 150 m
Sensitivity -39.6 dBZ at 1 km
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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
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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
Pow
er, d
Bm
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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
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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
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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
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Test Flights Completed - SAANGRIA
Ground echoes:
Mean Vr = 0.001 m/sStd dev Vr = 0.086 m/sVar Vr = 0.0074 m/s
(10 minutes of data over level ground)
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Test Flights Completed - SAANGRIA
• Verified sensitivity - ongoing• Spectra checked for spurious artifacts
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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
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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
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Thank YouQuestions?
HCR pod
Dropsonde
Various probes
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CSU-CHILL Comparison
CHILL Data HCR DataGV Skin Paint
Radius, km (approximate distance GV traveled in 60 sec)
Time, seconds060 30
Altit
ude
AGL,
km