Low Cloud Breakout Summary

1
Low Cloud Breakout Summary

• Presentations (apologies to co-authors)
• - Zhang (UCLA/LLNL) Mixed-layer modeling of Sc
  regions shows synoptic variability important in
  establishing relationship between LTS and low
  cloud fraction.
• - Pritchard (Scripps) Extended analysis of
  diurnal cycle of precipitation in SP-CAM. SP-CAM
  shows promise but does not capture nighttime max
  over Great Plains.
• - Cheng (ASM/NASA) Diagnosis of scale
  interactions for boundary layer turbulence in
  shallow cumulus with a variety of horizontal
  resolutions.
• - Blossey (UW) Analyzed and developed CRM
  column analogue for SP-CAM low cloud response to
  2K SSTs. Suggested physical mechanism to explain
  2K low cloud response. Column CRM analogue
  suggests that SP-CAM mean cloud are greatly
  overestimated due to coarse CRM resolution. Note
  IPHOC (ChengXu) improved on SP-CAM relative to
  LES.
• - Medeiros (UCLA/CSU) Developing column
  analogue for CAM aquaplanet runs using SCAM.
• Posters (Small subsample)
• - C. DeMott (CSU) Work on SP-CAM surface
  energy budget/potential coupling with ocean
  model. Found surface relative humidity too low
  in stratocumulus regions.
• - Marchand (UW) Developed adaptive vertical
  grid for SAM. Enables efficient simulation of
  stratocumulus (DYCOMS) with relatively few
  vertical levels. Fine vertical grid will track
  cloud.
• - Yamaguchi (CSU) Explorations of CTEI in high
  resolution LES.

2
Low Cloud Feedbacks Breakout Summary

• Research Action Items
• - Towards embedded LES in SP-CAM, start with
  big brother SAM. (Marat, possibly Blossey)
• address issues regarding different
  vertical grids, coupling of LES to parent model.
• - Revisit SP-CAM column analogue
  (Blossey/Wyant, possibly Cheng)
• Explore minimum resolution necessary for
  simulating BL cloud feedbacks.
• Apply to different cloud regimes (Sc,
  deep Cu), forcings (GHG, aerosol).
• Add synoptic variability to forcing.
• - Continue work on single column analogue for
  CAM aquaplanet runs. (Medeiros/Lappen)
• - Work to identify observational constraints
  for our models/hypothesis and for low cloud
  feedbacks. (UW, UCLA, Teixeira)
• - Analyze low cloud feedbacks in new SP-CAM
  runs, e.g. 4xCO2. (Wyant)
• - Further explore adaptive vertical grid in
  SAM. (Marchand)
• - New SP-CAM runs coming dx1km (Marchand),
  seasonal at T85. (Pritchard)
• - Explore effects of alternative scalar
  advection on low cloud representation. (Blossey)
• Administrative Action Items
• - Thanks to CMMAP headquarters for implementing
  mechanism for requesting new SP-CAM runs and for
  first run w/4xCO2 and prescribed SSTs.
• - Define further SP-CAM runs to improve (a) low
  cloud simulation and/or (b) our understanding of
  low cloud feedbacks, e.g. Morrison microphysics,
  Pincus/Stevens/RRTMG radiation, IPHOC.
• - Standardize a minimum set of SP-CAM outputs
  -- similar to those Marat generated for 4xCO2
  runs -- and document those outputs as possible
  for users. Share with other SP-CAM users.