CCN LWC Nc T Qv Rc Rainfall LWP Vertical Velocity WRF model - PowerPoint PPT Presentation

Yuan Wang , Yun Lin Renyi Zhang, Y angang Liu

 Marit ime st rat ocumuli [ Wang et al. , under review]  Bulk-OR:  fixed CCN spectrum  overestimate Nc  underestimate Rc  Bulk-2M:  prognostic Na and Qa  better agreement with S BM

 VOCALs maritime S c Cloud[ Wang et al. , under review]  The scheme incorporating the relative dispersion of the cloud droplet distribution [ Liu and Daum , 2003] and the scheme considering the effect of turbulence on the collisions and coalescences [ Franklin , 2008] outperform other schemes.  Embroynic rain drop radius is suggested to be 41 micron for S c.

 Prognostic number concentration and mass mixing ratio for cloud, rain, ice, snow graupel  Explicitly predicted water vapor mixing ratio and super saturation  S ix autoconversion options including Liu and Daum [2003]  Three moment aerosol modal approach with three prognostic Qa, S a and Na [Li et al. 2008]  Interacting with radiation scheme to consider aerosol radiative properties

 Int er-comparison wit h ot her microphysics in t he F AS TER t est bed  Invest igat ion of aerosol effect s on t he low-level clouds  Direct/ S emi-direct Effect  Indirect Effect  Examinat ion of t he paramt erizat ions in t he microphysics  Autoconversion  S aturation Adj ustment/ Predicted S aturation for Condensation  Aerosol S cavenging and Regeneration

 WRF v3.1.1 wit h TAMU t wo-moment bulk microphysical scheme  3 int eract ive domains  Innermost domains covers S GP cent ral Facilit y and RACORO flight s rout es wit h 750m spat ial, 50 vert ical res.  Nort h American Region Reanalysis  May 26-28, cumulus and drizzling st rat us, low CCN, low updraft  Two different aerosol profiles used: cont rol case (c-case) ~ 400 part icles/ cm 3 and pollut ed case (p-case) ~ 2000 part icles/ cm 3  Aerosol radiat ive effect s are considered seperat ely (prad-case)

 Obs: ARS CL  Model: 5x5 box Obs.  Qtot > 10 -6 kg/ kg  Cumulus & S t at us  Modeled cases similar Model  Timing consist ent  Overest imat ion close t o t he surface

CCN LWC Nc

T Qv

Rc Rainfall LWP Vertical Velocity

 WRF model wit h t wo-moment cloud microphysics and t hree moment aerosol scheme predict ed t he evolut ion of low lever cumulus, st rat us as well as CCN.  Over-est imat ed cloud amount near t he surface is mainly caused by biased t emperat ure simulat ion in t he WRF .  Cloud microphysics developed at TAMU show a bet t er agreement wit h field measurement t han some of t he ot her microphysics in t he WRF .  Aerosol efficient ly affect t he cloud effect ive radius, precipit at ion efficiency and t he cloud dynamics.