Allgemein

1
Status of WG1 Science Plan Issues
Christoph SchraffDeutscher Wetterdienst,
Offenbach, Germany

• KENDA
• LETKF at CNMCA talk by Lucio Torrisi
• 3DVar at HMC (Sochi area) not (yet) as good
  as interpolated GME analyses
• will test use of radar radial winds
• ARPA-SIM (Virginia Poli) comparison of
  1D-Varnudging and LHN
• 1D-Var not as good as LHN
• Problem bias between moist physics of COSMO and
  diagnostic scheme used in 1D-Var
• work will be stopped
• at DWD
• Direct nudging of radial velocity
• LHN for COSMO-EU
• Nudging of GPS-IWV

2
nudging of radar radial velocityverif. vs.
radar precipitation (1 27 May 2012)
FSS, 11 g.pts. (30 km)
ETS
threshold 0.1 mm / h
control (C-DE setup, with LHN) use of radial
velocity added
00-UTC forecast runs
12-UTC forecast runs
3
nudging of radar radial velocity summary
4
Latent Heat Nudging for COSMO-EU

• Motivation
• Reanalysis Project of HErZ would like to use LHN
  also on its larger domainconfiguration
  (COSMO-CORDEX, ?x 7km)
• Does it work ?
• Is there a negative interaction between LHN and
  the deep convection scheme ?

• Experiments
• 2 periods Summer August 2012 (incl.
  convective cases)
• Winter 1 Nov. 15 Dec. 2012 (incl. snow
  cases)
• operational COSMO-EU setup (Cosmo V4_27,
  tk?min0.4)
• operational LHN setup except
• no blacklist information used
• no bright band detection
• LHN within first 25 minutes of forecast (will
  be 2.5h in operational run)

5
LHN for COSMO-EU radar data coverage

• same data as for COSMO-DE,
• currently
• 17 German Doppler radar stations
• quality controlled
• 2 Dutch stations
• 2 Belgian stations
• 9 France stations
• 3 Swiss stations
• 2 Czech stations
• soon extended by 2 Polish stations
• every 5 minutes
• future can be extended by OPERA composite
  outside COSMO-DE domain

6
LHN for COSMO-EU case study
hourly precipitation at 2 Aug. 2012, 00 UTC
4h
Radar Control (rout) LHN
Experiment
7
LHN for COSMO-EUverif. vs. radar precipitation
(August 2012)
00 UTC 2.0 mm/h
00 UTC 0.1 mm/h
12 UTC 2.0 mm/h
12 UTC 0.1 mm/h
8
LHN for COSMO-EU Summary

• LHN in COSMO-EU is beneficial forecast impact
• Summer
• precipitation improved (esp. convective cases)
• most surface parameters slightly improved
• Winter neutral
• Work started to extend data coverage using OPERA
  radar composite

9
Status of OPERA

• three 2-D composites are available every 15
  minutes
• current rain rate, sum over last hour, current
  maximum reflectivity
• Phillipe Lopez (ECMWF) found out
• quality has increased in 2013 (with Baltrad QC)
  but is still not sufficient everywhere
• best quality over UK, France, Poland and Germany
• underestimation over southern Europe
• underestimation in snow cases
• lots of spurious ground echoes
• software transforming it to COSMO grids available
  (Stephan)

10
Status of OPERA
ODC composite 12 Aug 2013, 15 UTC
11
Status of OPERA
EY composite Input for LHN at DWD, 4
different storm-dep. Z-R relationships
OPERA DC composite (C-DE domain) 1 Z-R
relationship
12 Aug. 2013 15 UTC
differences particularly for low precip rates
(erroneous spaital alignment ?)
12
Status of OPERA

• 3-D reflectivity and radial wind
• reflectivity sent by almost all member states,
• radial wind only by few
• (but increasing)
• (Courtesy Hidde Leijnse, indicates
  max. number)
• HIRLAM already gets access to volume data, but
  possible also for other consortia
• dissemination of volume data to member states
  planned for end of 2014
• (to be decided with or without quality
  information ?)
• discussion about meta data / quality issues are
  ongoing
• (e.g. to distinguish zero echo no data
  (compare with raw data))

13
COSMO Science Plan Issues on DAGeneral strategy

• overall strategic goals of COSMO
  convective-scale EPS
• convective-scale ensemble-based DA
• other consortia focus on 3D-/4D-Var for
  deterministic, EnKF for EPS
• hybrid
• Hybrid 4D-EnVar without need of TL / adjoint
• Environment Canada ! UKMO ? HIRLAM ?
• DWD hybrid 3D-EnVar for global ICON ?
  for COSMO ?
• advantages of EnVar over LETKF (for
  deterministic run !)
• localization on B, not in obs space ? better
  for non-local obs
• hybrid approach mitigates sampling error
• disadvantages of EnVar over LETKF
• 4D approach limited Use only obs times where
  Grib fields used
• costs
• ? COSMO continue with LETKF

14
COSMO Science Plan Issues on DAAction items
2015 ? 2017 (and beyond !)

• consolidation of LETKF scheme, wherever found
  required,
• may include extensions
• intrinsic stochastic physics (links to WG3a,
  WG7)
• (other types of) additive covariance inflation
• iterative (e.g. running in place like) approaches
  or latent heat nudging (LHN) in view of improving
  convection initiation
• use of ensemble members with lagged valid time to
  reduce phase errors
• blending techniques to combine information from
  the larger scales of the nesting model

15
COSMO Science Plan Issues on DAAction items
2015 ? 2017 (and beyond !)

• integrated forecasting system for nowcasting
  (NWC) and
• very short-range-forecasting based on NWP
• towards very high resolution (1 km / sub-km)
• (link to SFP project COSMO-Airport, incl. Mode-S
  data sub-km)
• towards very high frequent analysis and forecast
  update
• (link to HErZ TB1, KENDA with 5-min update using
  3-d radar data)
• main issue quality ! (need to match obs, but
  maintain balance)
• optional higher weights for latest
  observations (smaller obs errors, weaker data
  thinning) ? smaller localization scales ?
• optional evaluation of assimilation of NWC
  products as pseudo-obs
• such as stability indices and objects (using
  non-conventional metrics)

16
COSMO Science Plan Issues on DAAction items
2015 ? 2017 (and beyond !)

• extended use of obs (particularly PBL,
  low-level humidity, cloud, precip)
• consolidate obs focused in KENDA PP radar, GPS
  slant path, SEVIRI cloud
• improved use of screen-level obs (T2m, RH2m,
  uv10m)
• SEVIRI WV (water vapour) channels
• AMDAR humidity high-resolution aircraft Mode-S
  (wind) data
• microwave radiometer ( Raman lidar) T-, q-
  profiles, Doppler wind lidar, ceilometer cloud
  base height
• (SEVIRI VIS for cloud properties, cloud radar
  data (CALIPSO, EarthCARE 2015)
• renewable energy power data from wind mill
  farms and solar power systems satellite
• no aerosol assimilation
• for COSMO-ART accurate description of aerosol
  sources
• would require substantial resources

17
COSMO Science Plan Issues on DAAction items
2015 ? 2017 (and beyond !)

• lower BC (analysis (link to WG3b)
  perturbations (link to WG7) !)
• soil moisture SM (soil temperature, etc.), e.g.
  by
• include SM in control vector, add SMOS / ASCAT
  satellite SM
• separate 2-D column analysis LETKF, or EPS used
  in Var-SMA
• snow cover and depth
• SST (perturbations e.g. by pattern generator)

• diagnosis (explore in EnKF framework) use of
• FSO (Forecast Sensitivity to Observations) (?
  link to HErZ project)
• DFS (Degrees of Freedom for Signal) diagnostics
• (to assess usefulness of different observation
  types)

• 2017 adapt LETKF to ICON-LAM (review
  decision LETKF EnVar)

18
COSMO Science Plan Issues on DAAction items
2018 ? 2020

• see previous slides
• MTG-IRS
• MW IR radiance over land in cloudy areas
  (dep. on experience in global DA)
• parameter estimation ?
• observation error correlations ?

19
COSMO Science Plan Issues on DArisks

• insufficient quality of LETKF (? develop EnVar
  ?)
• need to maintain / increase (often temporary)
  human resources ! Depends on
• continuation of HErZ after 2014
• new fixed position for radar DA
• new temporary positions ?
• EUMETSAT fellowship submitted by CNMCA sat data
  on soil moisture
• further increase of involvement e.g. by MCH,
  ARPA-SIM, CNMCA,
• new projects / collaboration with academia
• new flexible portable scripts may facilitate
  experimentation collaboration
• with other institutes on a technical level
  observation error correlations ?

20
Science Plan issues on data assimilationSummary

• consolidate / refine LETKF wherever required
• (enhancement techniques e.g. to correct phase
  errors RIP, LHN )
• integrated forecasting system for NWC (V)SRNWP
• obs radar, GPS slant, cloud screen-level
  SEVIRI WV, MTG IRS,
• lower BC
• diagnosis FSO , DFS
• adapt to ICON-LAM (develop EnVar ?)

21
Science Plan issues on data assimilationSummary
22
developments / plansat other consortia

• AROME
• EDA 3DVar with perturbed obs incl. surface ana
  (AROME 2014, Arpege LBC)
• later revisit breeding / ETKF
• multiplicative inflation of forecast
  perturbations 1.15 (every 3 hrs)
• stochastic physics tendencies (SPPT)
  large-scale, slowly evolving
• also tried microphysics turbulence parameter
  perturbations
• perturbed surface initial conditions (SST, SM,
  Rsmin, LAI, Cveg, Z0oro)
• coupling with large-scale analysis tests with
  Jk term in Var
• (weak constraint towards coupling data in Var,
  truncate Jk info at k20)
• Tests with 1-hrly cycles (3DVar)
• use of SEVIRI WV over land
• issue model bias with strong diurnal cycle

23
developments / plansat other consortia

• UKMO
• NWP nowcasting system Nowcasting Demonstration
  Project (NDP)
• 1hrly 4DVar with sub-hrly obs (, MSG WV AMVs,
  radar radial winds hourly cloud obs (sat
  surf), T2m, RH2m, uv10m) LHN (!)
• 12-hour forecast every hour
• 40km-FSS beats STEPS (Lagrangian-extrapolation
  NWC) after 1.8 hrs
• forms basis for next-generation UK NWP nowcasting
  system
• generally towards 4D-EnVar (without need of TL
  / adjoint ?)