9-12 April 2006EnDA Workshop, Marble Falls TX

Impact of Doppler Radar Impact of Doppler Radar Observations on the EnKF Observations on the EnKF

Analysis of a Developing MCSAnalysis of a Developing MCS

Mike Coniglio David Dowell Mike Coniglio David Dowell

Lou Wicker Dave StensrudLou Wicker Dave Stensrud

National Severe Storms LaboratoryNational Severe Storms Laboratory

9-12 April 2006EnDA Workshop, Marble Falls, TX

MotivationMotivation• Limited real-data EnKF experimentsLimited real-data EnKF experiments

• Does EnKF work with a messy convective event?Does EnKF work with a messy convective event?• Obstacles to getting robust storm-scale analyses Obstacles to getting robust storm-scale analyses

using WSR-88D data?using WSR-88D data?• Refl-only vs. refl&vel assimilation?Refl-only vs. refl&vel assimilation?

• Build catalog of cases from diff convective Build catalog of cases from diff convective modes to prove storm-scale EnKF conceptmodes to prove storm-scale EnKF concept• Start with the Start with the 11-12 June 2003 MCS11-12 June 2003 MCS

9-12 April 2006EnDA Workshop, Marble Falls, TX

11-12 June 2003 MCS11-12 June 2003 MCS2129z 2144z 2159z 2214z 2229z 2243z

2258z 2313z 2328z 2343z 2357z 0013z

0142z0127z0112z0058z0043z0028z

0207z 0221z 0236z 0251z 0306z 0321z

9-12 April 2006EnDA Workshop, Marble Falls, TX

11-12 June 2003 MCS11-12 June 2003 MCS

9-12 April 2006EnDA Workshop, Marble Falls, TX

Configuration of ExperimentsConfiguration of Experiments

• NCOMMASNCOMMAS• nnee=20-50 members=20-50 members• ~ 400 km by 400 km domain~ 400 km by 400 km domain x,yx,y=2-3 km in model and obs analysis=2-3 km in model and obs analysis

• Data assimilated every 1-5 min for various Data assimilated every 1-5 min for various 45-90 min periods45-90 min periods

• Modified & perturbed OUN soundingModified & perturbed OUN sounding• LFO ice with various slope/intercept LFO ice with various slope/intercept

parametersparameters• Only reflectivity assimilated initiallyOnly reflectivity assimilated initially

9-12 April 2006EnDA Workshop, Marble Falls, TX

Sense from Initial ExperimentsSense from Initial Experiments• Solutions very sensitive to initial soundingSolutions very sensitive to initial sounding

• Too little CIN – noise & spurious stormsToo little CIN – noise & spurious storms• Need to set missing dBZs to a low value (0)Need to set missing dBZs to a low value (0)• Too much CIN – storms die after assimilationToo much CIN – storms die after assimilation

• Storms/cold pool structures during assim. Storms/cold pool structures during assim. too small & too weak, not persistenttoo small & too weak, not persistent• Perhaps REFL-only assimilation not Perhaps REFL-only assimilation not

feasible?feasible?• Try using reflectivity & radial velocityTry using reflectivity & radial velocity

• Too much convection in ground clutterToo much convection in ground clutter• Automated velocity unfolding and ground Automated velocity unfolding and ground

clutter removal implementedclutter removal implemented

9-12 April 2006EnDA Workshop, Marble Falls, TX

Runs after 3-4 months testingRuns after 3-4 months testing• Runs are stable with good representation Runs are stable with good representation

of two main clustersof two main clusters

• but getting too much convection in but getting too much convection in between main stormsbetween main storms

Obs AnalysisObs Analysis EnKF AnalysisEnKF Analysis

9-12 April 2006EnDA Workshop, Marble Falls, TX

Runs after 3-4 months testingRuns after 3-4 months testing• Too much ground clutter getting through?Too much ground clutter getting through?• No! Anomalous cold pool is an issue:No! Anomalous cold pool is an issue:

9-12 April 2006EnDA Workshop, Marble Falls, TX

Dowell 8 May 2003 experimentDowell 8 May 2003 experiment

• What if TH isn’t updated with a velocity What if TH isn’t updated with a velocity ob?ob?

9-12 April 2006EnDA Workshop, Marble Falls, TX

No update of TH with VelNo update of TH with Vel• Anomalous cold pool gone:Anomalous cold pool gone:

• BUT……..BUT……..

9-12 April 2006EnDA Workshop, Marble Falls, TX

PROBLEMPROBLEM• Noticed storm/cold pool growth slowNoticed storm/cold pool growth slow

• Increase in initial sounding variability and Increase in initial sounding variability and bubbles didn’t help muchbubbles didn’t help much

• dBZ and QR too low in low levels!dBZ and QR too low in low levels!

9-12 April 2006EnDA Workshop, Marble Falls, TX

PROBLEMPROBLEM• dBZ and QR too low in low levelsdBZ and QR too low in low levels

9-12 April 2006EnDA Workshop, Marble Falls, TX

Lack of Low-Level ReflectivityLack of Low-Level Reflectivity

• Could explain why updraft/cold pool Could explain why updraft/cold pool structures too transientstructures too transient

• Microphysics or obs problem?Microphysics or obs problem?• What if reflectivity is withheld in precipitating What if reflectivity is withheld in precipitating

areas?areas?• Don’t assimilate reflectivity < 15 dBZDon’t assimilate reflectivity < 15 dBZ

• LFO large hail setting not appropriate? -Change LFO large hail setting not appropriate? -Change to graupel/hail mixtureto graupel/hail mixture

• Change raindrop size distributionChange raindrop size distribution• Are there more problems with using velocity?Are there more problems with using velocity?

• Don’t assimilate radial velocity at allDon’t assimilate radial velocity at all

9-12 April 2006EnDA Workshop, Marble Falls, TX

no assimilation of reflectivity > 15 dBZ, no assimilation of reflectivity > 15 dBZ, more graupelmore graupel

• Reflectivity important for maintaining storms!Reflectivity important for maintaining storms!

9-12 April 2006EnDA Workshop, Marble Falls, TX

Fewer but larger raindropsFewer but larger raindrops

9-12 April 2006EnDA Workshop, Marble Falls, TX

Fewer but larger raindropsFewer but larger raindrops

9-12 April 2006EnDA Workshop, Marble Falls, TX

Fewer but larger raindropsFewer but larger raindrops

9-12 April 2006EnDA Workshop, Marble Falls, TX

No assimilation of velocityNo assimilation of velocity

9-12 April 2006EnDA Workshop, Marble Falls, TX

No assimilation of velocityNo assimilation of velocity

9-12 April 2006EnDA Workshop, Marble Falls, TX

Where to go from hereWhere to go from here

• Nail down anomalous bubble problemNail down anomalous bubble problem• Explore microphysics impactsExplore microphysics impacts• Thorough comparison of refl only vs refl & Thorough comparison of refl only vs refl &

vel experimentsvel experiments• New ways to initialize ensemble/maintain New ways to initialize ensemble/maintain

spreadspread• Try new cases from “scratch”Try new cases from “scratch”