The Non-Local Scheme in CAM3 Michael A. Brunke

introduction surface layer outer layer free atmosphere h 0.1h 0 z PBL

introduction surface layer outer layer free atmosphere h 0.1h 0 z PBL

introduction surface layer outer layer free atmosphere h 0.1h 0 z PBL

input and output input parameters potential temperature temperature specific humidity height above surface pressure wind speed surface wind stress surface SH flux surface constituent flux output parameters kinematic sfc. const. flux eddy diffusivities countergradient terms convective temp. excess convective hum. excess surface friction velocity Obukhov length PBL height

free atmosphere K c Ri < 0Ri > 0 (Holtslag and Boville 1993)

free atmosphere K c Ri < 0Ri > 0 25 CF

determination of h h = z where Ri = Ri cr = 0.3 (Vogelezang and Holtslag 1996)

sensitivity of h formulation Zeng et al., 2004: Marine atmospheric boundary layer height over the Eastern Pacific: data analysis and model evaluation. J. Climate, 17,

determination of h h = z where Ri = Ri cr = C3C3 F0F0

determination of K c

turbulent velocity scales z / L < 0 0  z / L  1 z / L > 1

turbulent velocity scales z / L < 0 0  z / L  1 z / L > 1

turbulent velocity scales z / L < 0 0  z / L  1 z / L > C8C8 F0F0

turbulent velocity scales z / L < 0 0  z / L  1 z / L > C8C8 F6F6

countergradient term

817 C1C1 F0F0

scheme sensitivity Tested sensitivity to choices for:  Ri cr    b  a

+25% +10% -10% -25% hKmKm KhKh hh

+25% +10% -10% -25% hKmKm KhKh hh

hKmKm KhKh hh

+25% +10% -10% -25% hKmKm KhKh hh

+25% +10% -10% -25% hKmKm KhKh hh

look-up table? Not much value added by a LUT.  Simple formulation  Module runs very quickly. Pull h’s from a LUT?  Model run to get LUT values could be run at L31.

summary CAM3 uses standard non-local turbulence scheme in PBL. 17 tunable constants and 8 arbitrary functions. Scheme not sensitive to Ri cr and  ; are sensitive to b and a Convective temperature excess is needed. LUT probably not necessary except maybe to get h.