iv wmo impact workshop 2008
DESCRIPTION
Regional impact studies performed in the COSMO community Alexander Cress , Reinhold Hess Christoph Schraff German Weather Service , Offenbach am Main, Germany Email: [email protected] Introduction Use of radar reflectivity measurements - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/1.jpg)
IV WMO Impact Workshop 2008 Alexander Cress
Regional impact studies performed in the COSMO community
Alexander Cress, Reinhold Hess Christoph Schraff German Weather Service , Offenbach am Main, Germany
Email: [email protected]
• Introduction
• Use of radar reflectivity measurements
• Assimilation of satellite radiances with 1D-VAR and Nudging
• Use of VAD profiles, GPS tomography data and scatterometer winds
• E-AMDAR humidity data
• Experiment testing a reduced radiosonde network over Europe (EUCOS proposal)
• Summary
![Page 2: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/2.jpg)
ww
Lokal-Model COSMO-EU (LME) und COSMO-DE (LMK)
COSMO-EU (regional model): non-hydrostatic, rotated lat-lon grid, mesh-size: 7kmterrain-following hyprid coordinate with 40 layers up to 20 hPaforecast range: 78 h every 6 hoursprognostic cloud ice, prognostic rain schemesboundary values from GME
Analysis: continuous nudging schemeobservations: radiosonde, pilots, wind profiler,
aircraft, synops, buoys, shipscut-off: 2h30minvariational soil moisture analysis
COSMO-DE (lokal model): similar to COSMO-EUforecast range 18 h every 3 hmesh-size: 2.8 km, explicit convectionlatent heat nudging of radar reflectivitiesboundary values of COSMO-EU
![Page 3: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/3.jpg)
Data base
• Reflectivity from „Precipitation scan“
(DX-Produkt):
– Elevation angle: 0.5°-1.8°
– Spatial resolution: 1km x 1°,
max. Range 128 km
– Temporal resolution: 5 Minuten
– Quality control mechanism:
Clutter, spikes, rings, AnaProp, …
• Data processing:
– Correction of orographic shading
– variable Z-R-relations
– Composit of 16 German locations
– Bright band correction
![Page 4: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/4.jpg)
IV WMO Impact Workshop 2008 Alexander Cress
Basic principles of latent heat nudging
•LHN: specific form of Nudging to assimilate radar reflectivities respectivly the derived precipitation
•Problem: precipitation is a „derived“ model parameter with limited feedback on the thermodynamic structure of the model
•Aim: Adjust the dynamic of the model, that it produces the observed precipitation at
the right place and time ⇨ relation to a thermodynamic relevant model variable (temperature, humidity) is required
•Solution: Adjustment of the latent heat in the model yields to a temperature (humidity) change
![Page 5: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/5.jpg)
Results of an operational application
Animation of hourly precipitation 26. August 2006
Assimilation: 09 UTC
Radar Without LHN With LHN
![Page 6: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/6.jpg)
Results of an operational application
Animation of hourly precipitation sum 26. August 2006
Assimilation: 10 UTC
Radar Without LHN With LHN
![Page 7: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/7.jpg)
Results of an operational application
Animation of hourly precipitation 26. August 2006
Assimilation: 11 UTC
Radar Without LHN With LHN
![Page 8: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/8.jpg)
Results of an operational application
Animation of hourly precipitation 26. August 2006
Assimilation: 12 UTC
Radar Without LHN With LHN
![Page 9: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/9.jpg)
Results of an operational application
Animation of hourly precipitation 26. August 2006
Free forecast 12 UTC + 1 H
Radar Without LHN With LHN
![Page 10: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/10.jpg)
Results of an operational application
Animation of hourly precipitation 26. August 2006
Free forecast 12 UTC + 2 H
Radar Without LHN With LHN
![Page 11: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/11.jpg)
Results of an operational application
Animation of hourly precipitation 26. August 2006
Free forecast 12 UTC + 3 H
Radar Without LHN With LHN
![Page 12: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/12.jpg)
Results of an operational application
Animation of hourly precipitation 26. August 2006
Free forecast 12 UTC + 4 H
Radar Without LHN With LHN
![Page 13: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/13.jpg)
Results of an operational application
Animation of hourly precipitation 26. August 2006
Free forecast 12 UTC + 5 H
Radar Without LHN With LHN
![Page 14: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/14.jpg)
Results of an operational application
Animation of hourly precipitation 26. August 2006
Free forecast 12 UTC + 6 H
Radar Without LHN With LHN
![Page 15: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/15.jpg)
Results of an operational application
24H precipitation sum: 26.08.2006 (6 UTC – 6 UTC)
Assimilation
Radar Without LHN With LHN
![Page 16: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/16.jpg)
Results of an operational application
Skill scores for 32 runs in AUGUST 2006
Threshold 1.0 mm/h
ASS Free forecast ASS Free forecast
ETS FBI LHNNoLHN
LHNNoLHN
![Page 17: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/17.jpg)
Results of an operational application
Skill scores for 32 runs in AUGUST 2006
Threshold 5.0 mm/h
ASS Free forecast ASS Free forecast
ETS FBI LHNNoLHN
LHNNoLHN
![Page 18: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/18.jpg)
Summary and outlook
• Radar reflectivities are assimilated within the COSMO-DE to improve the
forecasts of convective systems
• Latent Heat Nudging (LHN) of radar reflectivities prove to be a proper method
• Assumption: Precipitation rate at the surface is proportional to the vertical
integral of latent heat release within a model column
• A positive impact of the LHN during the assimilation could be demonstrated
• The positive benefit of LHN can be verified up to nine hours in the free
forecast
• Additional investigations are needed to extent the positive benefit beyond
nine hours (additional use of radar winds to adjust the dynamic structure in
the model)
• Inclusion of European radar sites
![Page 19: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/19.jpg)
COSMO-Project:Assimilation of satellite radiances with 1D-Var and
NudgingGermany, Italy, Poland
1DVAR + Nudging
i.e. RETRIEVE temperature and humidity profiles and then nudge them as “pseudo”-observations
Goals of Project:• Assimilate radiances (SEVIRI, ATOVS, AIRS/IASI) in COSMO-EU
• Explore the use of nonlinear observation operators with Nudging
![Page 20: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/20.jpg)
no thinning of 298 ATOVS 30 ATOVS by old thinning (3) 30 ATOVS, correl. scale 70%
40 ATOVS by thinning (3) 82 ATOVS by thinning (2) 82 ATOVS, correl. scale 70%
T-‘analysis increments’ from ATOVS, after 1 timestep (sat only), k = 20
Reinhold Hess, 20 Athens, 2007
![Page 21: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/21.jpg)
no thinning of 298 ATOVS 30 ATOVS by old thinning (3) 30 ATOVS, correl. scale 70%
40 ATOVS by thinning (3) 82 ATOVS by thinning (2) 82 ATOVS, correl. scale 70%
T-‘analysis increments’ from ATOVS, after 30 minutes (sat only), k = 20
![Page 22: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/22.jpg)
Reinhold Hess, 22
GME forecast for 48 hours
Athens, 2007
![Page 23: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/23.jpg)
mean sea level pressure & max. 10-m wind gusts
analysis+ 48 h, REF (no 1DVAR)
valid for 20 March 2007 , 0 UTC
+ 48 h, 1DVAR-THIN3 + 48 h, 1DVAR-THIN2
m/s
![Page 24: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/24.jpg)
Reinhold Hess, 24
ww
COSMO Priority Project: Assimilation of Satellite Radiances with 1DVAR and Nudging
Status of Developments September 2007 technical implementation ready (ATOVS/SEVIRI, including debugging) basic monitoring of radiances (day by day basis) basic set up, first case studies available tuning required
nudging coefficients/thinning of observations bias correction/stratosphere background errors/humidity correlations
long term evaluation already studies on spatially localised background error covariance matrices
(SREPS for SEVIRI) implementation for AIRS/IASI has just started
Use of 1D-Var developments already for other activities:• GPS tomography• Radar reflectivities
To be done: tuning, testing, tuning
Athens, 2007
![Page 25: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/25.jpg)
IV WMO Impact Workshop 2008 Alexander Cress
Use of VAD Wind profiles in the Lokal Modell of DWD
• Vertical Wind Profiles provided by Doppler weather radars using the Velocity-Azimuth Display (VAD) technique
• Before using VAD wind profiles extensive monitoring has to be done
• Bad measurement sides are blacklisted
• Use of VAD wind profiles in LM in the same way as pilot wind profiles
![Page 26: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/26.jpg)
IV WMO Impact Workshop 2008 Alexander Cress
VAD statistics of background(LME) - observations
Mean over used VAD stations (020207 – 120207)
Left: BIAS Right: RMS
• BIAS and RMS comparable to radiosonde statistics
• Almost no bias in wind velocity and direction
![Page 27: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/27.jpg)
IV WMO Impact Workshop 2008 Alexander Cress
02933 10204
![Page 28: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/28.jpg)
IV WMO Impact Workshop 2008 Alexander Cress
Station: 10338
blacklisted
![Page 29: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/29.jpg)
IV WMO Impact Workshop 2008 Alexander Cress
Verification of LME forecastsagainst radiosondes
Results
Mainly neutral
Slightly positive for + 48 h RMS geopotential height
![Page 30: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/30.jpg)
GPS tomography: – comprehensive monitoring (14 months) of quasi-operational tomography profiles
(at CSCS) against Payerne radiosonde and COSMO fields done
results: tomographic refractivity profiles have rather large errors unless COSMO forecasts are included as background info
– start working on assimilating humidity profiles derived from tomography retrievals
– new PhD (Perler) at ETH started working on tomography method itself
1.2 Multi-Sensor Humidity Analysis (incl. GPS-obs)
Daniel Leuenberger (MCH)
• BIAS – wet bias below 1500 m, large dry bias around 2000 m• Summer: 10 – 15 ppm (~1.5-2.5 g/kg) or ~35% • Winter: 5 ppm (~ 0.75 g/kg) or 20%• (much) larger than NWP model (+12h / +24h fc)
• STD – Summer: up to 12 ppm (~1.8 g/kg) or 10% – 30% in PBL• Winter: up to 7 ppm (~1 g/kg) or 20% – 40% in PBL• slightly smaller than NWP model (+12h / +24h fc)
![Page 31: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/31.jpg)
1.4 Assimilation of Screen-level Observations PBL Analysis
Jean-Marie Bettems, Oliver Marchand, Andre Walser (MCH),
Andrea Rossa + collaborators (ARPA-Veneto), Antonella Sanna (ARPA-Piemonte)
• main objects: data selection, extrapolation to 10 m, vertical + horizontal structure functions
• Diploma work at MCH (Lilian Blaser): 9 case studies, standard assimilation parameters
– 10-m wind ass.: analysis impact: positive at surface, also for upper-air wind speed forecast impact: neutral, except 1 positive case (+8 h)
– 2-m temperature & humidity additionally (1 convective case): clear positive impact on analysis of surface parameters, negative for upper-air wind speed
– surface pressure (1 winter case): slight negative impact on 10-m wind, not due to geostrophic correction
– need to select representative stations, need appropriate vertical structure functions (impact of screen-level obs reaching high)
» up to now: only case studies done
![Page 32: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/32.jpg)
1.4 Assimilation of Screen-level Observations PBL Analysis
Antonella Sanna, M. Milelli, D. Cane, D. Rabuffetti (ARPA-Piemonte)
• Sensitivity study (1 case with floodings, 2.8 km resolution) on assimilation of non-GTS data and soil moisture initialisation (PREVIEW framework):
– clear positive impact from ass of high-res 10-m wind and 2-m temperature data and with nudging parameters adjusted to fit denser obs network
– no benefit from replacing IC soil moisture by FEST-WB (hydrological model for floods)
5 June 2002, 12 UTCdiurnal cycle T2m
5 June 2002, 12 UTC - 18-h precipitation sum
analysis 12-h forecast
T -profiles
CTRL: interpol. anaSET2: standard nudgingSET3: + nudge T2m, v10m
adjusted parametersSET4: + init. soil moisture
![Page 33: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/33.jpg)
1.5 Assimilation of Scatterometer Wind
Heinz-Werner Bitzer (MetBw), Alexander Cress, Christoph Schraff (DWD) • nudging of scatterometer wind data as buoy observations technically implemented,
taking into account all quality control / bias correction steps developed for use in GME
• idealised case studies: model rejects largest part of 10-m wind info unless mass field is explicitly balanced
derive surface pressure analysis correction in geostrophic balance with 10-m wind analysis increments (implies need to solve Poisson equation):
implemented, model now accepts data
• first real case study computed
QSCAT 19 June 2007, 6 – 9 UTC
48N
50N
15 W
Opr (no QSCAT) – Exp (QSCAT)PMSL 19 June 2007, 9 UTC hPa
![Page 34: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/34.jpg)
1.5 Assimilation of Scatterometer Wind
Heinz-Werner Bitzer (MetBw), Alexander Cress, Christoph Schraff (DWD)
m/s 10-m wind gusts
analysis (21 June 2007, 12 UTC) + 48-h , no QSCAT + 48-h , with QSCAT
minor impact, central pressure error reduced from – 5 hPa to – 3 hPa
![Page 35: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/35.jpg)
IV WMO Impact Workshop Alexander Cress
E-AMDAR humidity measurements
Three Lufthansa airplanes are implemented with humidity sensor
First humidity data in bufr format became available at the beginning of 2007
DWD started a data monitoring (obs – bg) using its global (GME) and regional model (LME)
What additional humidity data from airplanes will be of use to regional NWP ?
What potential savings to the radiosonde network (complemt or reduction) willsuch a programme bring?
![Page 36: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/36.jpg)
IV WMO Impact Workshop Alexander Cress
00 UTC 12 UTC
All aircrafts
![Page 37: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/37.jpg)
IV WMO Impact Workshop 2008 Alexander Cress
EU4593
00 UTC 12 UTC
![Page 38: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/38.jpg)
IV WMO Impact Workshop 2008 Alexander Cress
EU5331
00 UTC 12 UTC
![Page 39: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/39.jpg)
IV WMO Impact Workshop 2008 Alexander Cress
Summary of the preliminary results
• Monitoring and blacklisting is very important for a successful use of VAD wind profiles. Quality differs substantially from station to station
• VAD wind measurements produce no additional noise in the analyses The wind and geopotential height fields are in balance for different pressure levels => wind observations are successfully used in the Lokal Modell
• Overall impact of VAD wind profiles on forecast quality is neutral
• GPS tomography refractivity profiles have rather large errors unless COSMO forecasts are included as background
![Page 40: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/40.jpg)
IV WMO Impact Workshop 2008 Alexander Cress
Summary of the preliminary results
• Assimilation of screen-level observations show positive impact on surface analysis but neutral to slightly negative for upper-air analysis
• Small positive impact of using QuikScat scatterometer winds in nudging assimilation of COSMO-EU
• Monitoring of AMDAR humidity profiles showed a strong negative humidity bias (higher than radiosondes) decreasing with height and also a warm temperature bias
![Page 41: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/41.jpg)
Experiment testing a reduced radiosonde network over Europe
• Experimentdesign
• Following a EUCOS Redesign proposal
• Only 32 Radiosondenstations in Europe (EUCOS Area)
• With emphasis on the western borders of Europe and offshore islands v No changes over eastern Europe
• All other observing systems unchanged
Time range: 09.02.2006 to 13.03.2006
• Assimilation und forecasts (00 und 12 UTC) with COSMO-EU
IV WMO Impact Workshop 2008 Alexander Cress
![Page 42: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/42.jpg)
00 UTC
![Page 43: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/43.jpg)
12 UTC
![Page 44: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/44.jpg)
Verification area: 40oN – 60oN and -5oW – 25oE
Sea surface pressure bias09.02.06 – 13.03.06
00 UTC
EUCOS ExperimentRoutine
12 UTC
IV WMO Impact Workshop 2008 Alexander Cress
![Page 45: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/45.jpg)
Frequency Bias of low level clouds09.02.06 – 13.03.06
00 UTC
Verification area: 40oN – 60oN and -5oW – 25oE
EUCOS ExperimentRoutine
12 UTC
IV WMO Impact Workshop 2008 Alexander Cress
![Page 46: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/46.jpg)
Bias of wind direction09.02.2006 – 13.03.2006
Verification area: 40oN – 60oN and -5oW – 25oE
00 UTC
EUCOS ExperimentRoutine
12 UTC
IV WMO Impact Workshop 2008 Alexander Cress
![Page 47: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/47.jpg)
12 UT
![Page 48: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/48.jpg)
12 UT
![Page 49: IV WMO Impact Workshop 2008](https://reader031.vdocuments.mx/reader031/viewer/2022020921/568159a4550346895dc6feb6/html5/thumbnails/49.jpg)
Summary
• Reducing the radiosonde network has a negative impact on the quality of COSMO-EU analysis
• Negative impact was largest on humidity fields
• Negative impact diminished after 12 hours
• Slightly negative impact on sea surface pressure
• On average scattered (broken) clouds are overestimated and strong clouds (overcasting situations) are underestimated
• Increasing wind direction bias during forecast
• Negative impact is higher at 00 UTV compared to 12 UTC (Compensation by aircraft data ?)