Real-time Doppler Wind Quality Control and Analysis

Qin Xu

National Severe Storms Laboratory/NOAAPengfei Zhang, Shun Liu, and Liping Liu

CIMMS/University of Oklahoma

WSR-88D Network

Volume Coverage Pattern (VCP)

Reflectivity

KTLX

4 VCPPrecipitation ModeVCP11: 14 tilts, 5 minVCP21: 9 tilts, 6 min

Clear Air ModeVCP31: 5 tilts, 10 minVCP32: 5 tilts, 10 min2 new VCP

VCP 21

Resolution ComparisonLevel II velocity, Mesonet, & RUC20

20km

RUC Wind

Mesonet

KTLX 02:13UTC, 22 June 2004

Level II Doppler Velocity

Spatial resolution1o, 250 mTemporal resolution5, 6 or 10 min

50 km5km

Aliasing

Range Folding

KTLX

Real-Time Radar Wind Analysis and Monitoring System

LDM

Real Time Level II data

LDM

Real Time Level II data

WGConvert dataformat and

display

WGConvert dataformat and

display

Workstation

Web Display

Web Display

QC QC

Real-timeWind

Retrieval

Real-timeWind

Retrieval

Monitoring System

Raw Data NetCDF Data eps File

PC

Management System for Real-time Radar Wind Analysis

Automated functions:• Auto-monitor the data flow & computer usage in the RWR (Real-time Wind Retrievals), display the current & past 24 h status on the web;• Auto-restart & backup RWR (if it is down) to maintain uninterrupted operation;• Auto-collect and display statistical parameters & indices for radar data quality control and related research developments. QCQC

Monitoring 9 radars in Oklahoma & vicinityDisplaying current status and time series of past 24 h

Monitoring 8 radars in New England

Doppler velocity quality problems

1) Bird contamination

2) Noisy velocity field

3) Anomalous propagation (AP) caused ground clutter

4) Doppler velocity aliasing and range folding

Noisy velocity field

KBOX 00:22UTC 28 Oct. 2002

Quality control (QC) parameter: Percentage of sign change (PSC)

Too Noisy

Normal

AP Ground Clutter DetectionExisting Method

Raw AP Mitigated Expert Truth

Information used for AP detection (Kessinger et al. 2003):Texture of reflectivity, radial velocity, vertical gradient of reflectivity,and spectrum width

Saint Louis KLSX 03:34UTC , July 07,1993

AP Ground Clutter DetectionAdditional method to deal with problems caused by moving vehicles

DetectedDoppler Velocity

Salt Lake radar (KMTX) 23:51UTC, Sept. 19,1999

Migrating-bird QC Parameters

0 400 800 1200 1600 2000 2400

0

2

4

6

8

10

time

MR

F (

dB

Z)

20

30

40

50

60

70

VD

C (

%)

27

30

33

36

39

42

VS

C (

%)

Hour

KTLX May 1, 2003Z

Vr

2dVar Wind Analysis Flowchart

Real-time WSR-88D level II data

2dVar wind analysis (with Rd = 60 km & then 20 km)

dealiasing

Produce VAD background

QC

Real-Time Vector Wind Retrieval (Product)

120km 20m/s

120k

m

KTLX 20:03UTC 02 June 2004

Reflectivity Doppler Velocity

Resolution comparison Radar retrievals vs Mesonet winds

KTLX 16:01UTC, 19 May 2004

Full Spatial Resolution Display

10 km

KTLX

KTLX 02:13 UTC, 22 June 2004

Mosaic Wind Field ?

KTLX

KINX

KSRX

NOT on Constant Altitude!

17:14 UTC, 27 April 2004

High Resolution Real-Time 2dSA Wind Retrieval

2dSA (at 0.5o)41x41 grid with∆x=∆y=250mMoving FrameU = 8.3 m/sV = 5.3 m/s

KTLX 22:15 to 22.20 UTC, 8 May 2003

NSSL Polarimetric Radar: KOUN

KOUN KTLX

HV Reflectivity

Bird

Storm

08:52UTC 24 May 2003

Phased Array Radar at NWRT

Tornado Vortex Signature (TVS) Observed by Phase Array Radar May 30 2004 02:36UTC

Reflectivity Doppler Velocity

TVS

Squall Line Observed by Phase Array Radar

June 2 2004 21:50UTC

Reflectivity Doppler Velocity

Elev.angle =0.75o Elev.angle =0.75o

BeamWidth=1.6o, GateWidth=240m, NyqVel=23.40m/s