9-12 April 2006EnDA Workshop, Marble Falls TX Impact of Doppler Radar Observations on the EnKF Analysis of a Developing MCS Mike Coniglio David Dowell Lou Wicker Dave Stensrud National Severe Storms Laboratory

9-12 April 2006 EnDA Workshop, Marble Falls, TX Motivation Limited real-data EnKF experiments Limited 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 using WSR-88D data? Obstacles to getting robust storm-scale analyses using WSR-88D data? Refl-only vs. refl&vel assimilation? Refl-only vs. refl&vel assimilation? Build catalog of cases from diff convective modes to prove storm-scale EnKF concept Build catalog of cases from diff convective modes to prove storm-scale EnKF concept Start with the June 2003 MCS Start with the June 2003 MCS

9-12 April 2006 EnDA Workshop, Marble Falls, TX June 2003 MCS 2129z2144z2159z2214z2229z2243z 2258z2313z2328z2343z2357z0013z 0142z0127z0112z0058z0043z0028z 0207z0221z0236z0251z0306z0321z

9-12 April 2006 EnDA Workshop, Marble Falls, TX June 2003 MCS

9-12 April 2006 EnDA Workshop, Marble Falls, TX Configuration of Experiments NCOMMAS NCOMMAS n e =20-50 members n e =20-50 members ~ 400 km by 400 km domain ~ 400 km by 400 km domain   x,y =2-3 km in model and obs analysis Data assimilated every 1-5 min for various min periods Data assimilated every 1-5 min for various min periods Modified & perturbed OUN sounding Modified & perturbed OUN sounding LFO ice with various slope/intercept parameters LFO ice with various slope/intercept parameters Only reflectivity assimilated initially Only reflectivity assimilated initially

9-12 April 2006 EnDA Workshop, Marble Falls, TX Sense from Initial Experiments Solutions very sensitive to initial sounding Solutions very sensitive to initial sounding Too little CIN – noise & spurious storms Too 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 assimilation Too much CIN – storms die after assimilation Storms/cold pool structures during assim. too small & too weak, not persistent Storms/cold pool structures during assim. too small & too weak, not persistent Perhaps REFL-only assimilation not feasible? Perhaps REFL-only assimilation not feasible? Try using reflectivity & radial velocity Try using reflectivity & radial velocity Too much convection in ground clutter Too much convection in ground clutter Automated velocity unfolding and ground clutter removal implemented Automated velocity unfolding and ground clutter removal implemented

9-12 April 2006 EnDA Workshop, Marble Falls, TX Runs after 3-4 months testing Runs are stable with good representation of two main clusters Runs are stable with good representation of two main clusters but getting too much convection in between main storms but getting too much convection in between main storms Obs Analysis EnKF Analysis

9-12 April 2006 EnDA Workshop, Marble Falls, TX Runs 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 2006 EnDA Workshop, Marble Falls, TX Dowell 8 May 2003 experiment What if TH isn’t updated with a velocity ob? What if TH isn’t updated with a velocity ob?

9-12 April 2006 EnDA Workshop, Marble Falls, TX No update of TH with Vel Anomalous cold pool gone: Anomalous cold pool gone: BUT…….. BUT……..

9-12 April 2006 EnDA Workshop, Marble Falls, TX PROBLEM Noticed storm/cold pool growth slow Noticed storm/cold pool growth slow Increase in initial sounding variability and bubbles didn’t help much Increase in initial sounding variability and bubbles didn’t help much dBZ and QR too low in low levels! dBZ and QR too low in low levels!

9-12 April 2006 EnDA Workshop, Marble Falls, TX PROBLEM dBZ and QR too low in low levels dBZ and QR too low in low levels

9-12 April 2006 EnDA Workshop, Marble Falls, TX Lack of Low-Level Reflectivity Could explain why updraft/cold pool structures too transient Could explain why updraft/cold pool structures too transient Microphysics or obs problem? Microphysics or obs problem? What if reflectivity is withheld in precipitating areas? What if reflectivity is withheld in precipitating areas? Don’t assimilate reflectivity < 15 dBZ Don’t assimilate reflectivity < 15 dBZ LFO large hail setting not appropriate? - Change to graupel/hail mixture LFO large hail setting not appropriate? - Change to graupel/hail mixture Change raindrop size distribution Change raindrop size distribution Are there more problems with using velocity? Are there more problems with using velocity? Don’t assimilate radial velocity at all Don’t assimilate radial velocity at all

9-12 April 2006 EnDA Workshop, Marble Falls, TX no assimilation of reflectivity > 15 dBZ, more graupel Reflectivity important for maintaining storms! Reflectivity important for maintaining storms!

9-12 April 2006 EnDA Workshop, Marble Falls, TX Fewer but larger raindrops

9-12 April 2006 EnDA Workshop, Marble Falls, TX Fewer but larger raindrops

9-12 April 2006 EnDA Workshop, Marble Falls, TX Fewer but larger raindrops

9-12 April 2006 EnDA Workshop, Marble Falls, TX No assimilation of velocity

9-12 April 2006 EnDA Workshop, Marble Falls, TX No assimilation of velocity

9-12 April 2006 EnDA Workshop, Marble Falls, TX Where to go from here Nail down anomalous bubble problem Nail down anomalous bubble problem Explore microphysics impacts Explore microphysics impacts Thorough comparison of refl only vs refl & vel experiments Thorough comparison of refl only vs refl & vel experiments New ways to initialize ensemble/maintain spread New ways to initialize ensemble/maintain spread Try new cases from “scratch” Try new cases from “scratch”