1. The Use of WSR-88D Radar Data at
NCEP
Shun Liu1
Geoff DiMego2
, Wan-Shu Wu2
, Matthew Pyle2
, Jacob Carley1
, Shucai
Guan2
, David Parrish2
,John Derber2
1
I. M. System Group, Rockville, Maryland
2
NOAA/National Centers of Environmental Prediction, College Park, Maryland

2. OUTLINE
2
•Radar data processing at NCEP
•New Velocity-Azimuth Display (VAD) Wind
•Forecast initialization with radar data

3. Radar Data Processing at NCEP
3
Flow chart of level-II radar data processing at NCEP
Radar data collection via LDM
Radar data decoding
SW Radial wind
Radial wind and Reflectivity QC
BUFR tank
Level II BUFR
product
GSI analysis
Reflectivity
Interpolating to
Cartesian grid
SRC tank
Reflectivity
mosaic
NAM, NAMRR, RAP
and HRRR forecast
HiRes
Verification
Mixing-layer
Height
VAD
Zdr, CC, KDP
NAMRR—next generation of NCEP’s regional forecast system (See 4.4.1 by J. Carley)

4. Performance of Radial Wind QC
4
before QC after QC

5. Radar Mosaic vs Satellite Product
5
Cloud phase (http://www-pm.larc.nasa.gov)

6. 6
Performance of Reflectivity QC
Equitable Threat Score and False Alarm Ratio of composite reflectivity
coverage against cloud coverage

7. New VAD Wind
7
new VAD old VAD
data ncep radar station
QC after Vr QC no Vr QC
Vertical Res 50 m 304.8 m
Time Res 5-10 minutes 30-40 minutes
• Velocity-Azimuth Display
Wind
• VAD wind is wind profile
from 3D radial wind
observation.

8. 8
New VAD vs Old VAD
old VAD new VAD
NDAS analysis

9. 9
U and V BIAS and RMS averaged over CONUS domain
Test from 04/03/2012 to 04/24/2012 (best guess)
New VAD vs Old VAD

10. 10
V- component BIAS 700 hPa
UNIT: KNOT
New VAD vs Old VAD

11. 11
•12 km resolution for
parent domain
•4 km resolution for
CONUS nest
Forecast Initialization with Radar Data
NAM: North American Model
NDAS: NAM Data Assimilation

12. 12
Forecast initialization with radar data
• Hybrid varational-Ensemble GSI are used (Wu, et. al (2002), Wang et. al (2007), Kleist et. al (2013)).
• The radial wind is directly analyzed by GSI.
• GSD cloud analysis + DFI is used to assimilate radar reflectivity
• Metar and Satellite observations are used in cloud analysis to detect cloud.
• Latent heat rate estimated from reflectivity.
• Wind, cloud water and cloud ice mixing ratio and specific humidity are upgraded.

13. 13
OBS NOREF REF
Performance of Reflectivity Assimilation
with Cloud Analysis

14. 14
3 h PCP verification 24 h PCP verification
From 20130223 to 20130712
-------
with refl
-------
no refl
Precipitation (PCP) Verification:
Reflectivity DA vs No Reflectivity DA

15. 15
Future Plan
 Improvement of radar data quality control package at NCEP is
constantly needed. We will need to process TDWR and
Canadian radar data in near future.
 Current radar data processing at NCEP will be combined with
NSSL’s Multi-radar Multi-sensor System (MRMS) system
 Analyze hydrometeors derived from cloud analysis in hybrid
ensemble data assimilation system.
 Tune radial wind assimilation algorithm and keep more
convective scale features