Transcript PowerPoint Presentation - Operational Use of the Rapid

The NOAA Rapid Update Cycle
(RUC) 1-h assimilation cycle
Stan Benjamin
Steve Weygandt
John Brown
NOAA
Forecast Systems
Lab – Boulder CO,
USA
GOAL:
• Provide high-frequency (1h) mesoscale
3-d analyses and short-range (1-12+h)
forecasts for aviation, severe weather,
hydrology, …
RUC web site - http://ruc.fsl.noaa.gov
WWRP Symposium -- Nowcasting & Very Short Range Forecasting –
8 Sept 2005 – Toulouse, France
RUC Hourly Assimilation Cycle
1-hr
fcst
Background
Fields
11
1-hr
fcst
1-hr
fcst
1-hr
fcst
1-hr
fcst
1-hr
fcst
Analysis
Fields
3DVAR
3DVAR
3DVAR
Obs
Obs
Obs
12
13
14
3DVAR 3DVAR
Obs
15
Obs
16
Time
(UTC)
RUC Hourly Assimilation Cycle + Forecasts > 1h
9-hr
fcst
Background
Fields
11
9-hr
fcst
12-h
fcst
9-hr
fcst
9-hr
fcst
12-h
fcst
Analysis
Fields
3DVAR
3DVAR
3DVAR
Obs
Obs
Obs
12
13
14
3DVAR 3DVAR
Obs
15
Obs
16
Time
(UTC)
Run-time at NCEP for RUC 12h fcst – 17 min
Data type
~ Number
Frequency
Rawinsonde
~85
/12h+spec
Aircraft
1600-6000
/1h
NOAA profiler
32
/1h
VAD winds
~125
/1h
PBL profilers
25
/1h
Surface METAR
1600-1800
/1h
Mesonet
~6000
/1h
Buoy/ship
100-1500
/1h
GOES precip water
1500-3000
/1h
SSM/I precip water
1000-4000
/6h
GPS precip water
~280
/1h
GOES cloud-drift wind
1000-2500
/1h
GOES cloud-top (p,T)
~10km
/1h
Radar ref / /lightning
1km13km
/1h
RUC
Obs
Sources
- experimental
13km RUC
-- As of
6 Sept 05
1
3
6
9
12
Analysis
~ ‘truth’
6
RUC20
Wind forecast
Accuracy
-Sept-Dec
2002
8
10
12
(kts)
Verification against rawinsonde data over RUC domain
RMS vector difference (forecast vs. obs)
RUC is able to use recent obs to improve forecast skill
5
down to 1-h projection for winds
Application of Digital Filter Initialization (DFI) in RUC
Model
• Critical for 1-h assimilation cycle
• 45 min forward, 45 min backward – no physics
• Average over DFI period
• Applicable for diabatic application, nudging to radar obs
during DFI ‘pre-forecast’
Noise in surface pres
at 1h forecast is
much lower with DFI
6
Rapid Update Cycle Model
Vert Coord
Hybrid isentropic-sigma –
50 levels
Stable clouds, NCAR mixed-phase (cloud
Precipitation water, rain water, snow,
graupel, ice, ice particle
number. concen.
Sub-grid
precipitation
Grell-Devenyi ens scheme
(144 members, closure/CIN
Land-surface
RUC LSM - 6-level soil/veg
model, 2-layer snow model
- Smirnova
9-12-hr
fcst
Current operational RUC: 13-km
7
Recent changes to RUC13 3DVAR analysis
(among many):
1. Use of surface obs throughout PBL (NCEP Fall 2004)
2. Cloud analysis (GOES, METAR ceiling/vis/curr-wx)
PBL-based METAR assimilation
-- create additional obs corrections thru PBL
Use METAR data through PBL depth from 1h fcst
RUC oper analysis
18z 3 Apr 02
IAD
Effect of PBL-based
METAR assimilation
x
x
x
x
9
CAPE impact from two RUC enhancements
0000 UTC
21 Apr 2004
3h fcst
OPERATIONAL
RUC enhancements:
3h fcst WITH
enhancements
Tornadoes
1. Use of METAR obs through
boundary-layer depth (Sept 04)
2. Assimilation of GPS precipitable
water observations (RUC13 - ~Jun05)
NWS SPC
Norman, OK
Severe
10
reports
RUC Cloud Analysis
Use GOES CTP, radar reflectivity, lightning,
METAR (clouds,wx,vis) to modify 1h fcst 3-d q* fields
• Clear/build (change qc, qi, qv) with logical arrays
• Safeguards for pressure-level assignment problems
(marine stratus, convective clouds)
• Use nationwide mosaic radar data to modify water
vapor, hydrometeor fields – in testing, crude
• Lightning data used as a proxy for radar reflectivity
• Feedback to cumulus parameterization scheme – bypass
convective inhibition via radar/lightning, GOES ECA
11
GOES cloud top pressure
Radar/lightning data
100
100
200
200
300
300
Qv
400
RH
400
500
500
600
600
700
700
800
Qc
Qi
dBZ
Qs
800
Qr
900
900
999
999
PRES
PRES
Cloudwater, water vapor and
relative humidity before ( )
and after (----) GOES Cloudtop pressure adjustment
Rainwater, snow, cloud ice and
reflectivity before ( ) and after
(----) GOES radar/lightning 12
adjustment
Sample ceiling
analysis impact
Analysis
WITH
cld/wx/
vis obs
Ceiling from RUC hydrometeors
Observations
1800 UTC
17 Nov 2003
LIFR IFR
Aviation Flight Rules
MVFR
VFR
CLR
cloud ceiling height (meters)
Analysis
NO
cld/wx/
13
vis obs
Data type
3-d reflectivity data
NASA Langley experimental GOES
cloud products
Experimental
or future
NSSL mosaicked data RUC Obs
Sources
~ Number
TAMDAR aircraft regional carriers
– T/V/RH – lower-mid
troposphere
65 aircraft
Radar radial wind
120 WSR-88D radars
GPS zenith wet delay
(replacing prec water retrievals)
280, increasing
QC’d mesonet data
6000, but many not
usable due to poor
siting and lack of QC
monitoring/metadata
To be added in
next 6 months to
experimental
13km RUC
Radar reflectivity
assimilation - experimental
RUC13 init 09z - 3-6h precip
Valid 12-15 UTC 6 Sept 2005
Control – oper RUC
Obs – 1345 UTC
Exp RUC13
W/ rad ref assim
15
Sample 3DVAR analysis with radial velocity
Cint =
2 m/s
0800 UTC
10 Nov 2004
Dodge
City, KS
*
*
*
*
*
*
Vr Amarillo, TX
Dodge City, KS
*
K = 15
wind
Vectors
and
speed
Cint =
1 m/s
*
Vr
Amarillo, TX
500 mb Height/Vorticity
Analysis
WITH
radial
velocity
*
Analysis
difference
(WITH
radial
velocity
minus
without)
Planned Rapid Refresh domain
Current RUC CONUS domain
Rapid Refresh
-replace RUC –
2007-08
- 13km resolution
- use WRF model
Goals:
Hourly NWP
update in
- Alaska
- Wider E.
Pacific
-- Canada
- Caribbean
Sea
17
The RUC by 2008, testing in 2006
• “Rapid Refresh”
• Simple  more complex assimilation
of radar reflectivity and radial winds
• Improved use of sat data, GPS,
aircraft, surface/mesonet
• Use of WRF model w/ RUC-like
physics
• Use of NCEP data assimilation (GSI)
with RUC-specific enhancements – use
of sfc data, cloud analysis
• North American coverage
18