Analysis of the MM5-Simulated Surface Fields with Three PBL schemes over the Eastern U.S.

during 6-16 August 2002

Winston, Mike Ku, and Gopal SistlaNYSEC-DAR

andDa-Lin Zhang

University of Maryland

1. Background

• Zhang, D.-L. and W.-Z. Zheng, 2004: Diurnal Cycles of Surface Winds and Temperatures as Simulated by Five Boundary-Layer Parameterizations. Journal of Applied Meteorology, 43, 157-169.

Observed diurnal cycles of Tsfc and Vsfc over 105 surface stations taken over an area of 800 km x 800 km during 12 – 15 July 1997

Model description – MM5

Two-way nested, Two-way nested, x = 36/12 km;x = 36/12 km; Kain-Fritsch cumulus parameterizationKain-Fritsch cumulus parameterization Simple cloud/ice parameterizationSimple cloud/ice parameterization PBL schemes being tested:PBL schemes being tested:

a) Blackadar; b) Gayno-Seaman; c) MRF;a) Blackadar; b) Gayno-Seaman; c) MRF;

d) Miller-Yamada-Jajic; e) Burke-Thompson.d) Miller-Yamada-Jajic; e) Burke-Thompson. Surface layer (half-Surface layer (half-) at 10 m) at 10 m Integration: 1200 UTC 12 - 15 June 1997Integration: 1200 UTC 12 - 15 June 1997

Comparison of diurnal cycles of Tsfc between the observed and the simulated with the Blackadar, Gayno-Seaman, MRF, Miller-Yamada-Jajic and Burke-Thompson schemes

Comparison of diurnal cycles of Vsfc between the observed and the simulated with the (new) Blackadar, Gayno-Seaman, MRF, Miller-Yamada-Jajic and Burke-Thompson schemes

Diurnal cycle of the low-level winds generated by the Gayno-Seaman and (b) Blackadar schemes

2. Summer Season of 2002 - MANE-VU

• A two-way nested (36/12 km) grid.• Three PBL schemes: 1) the Plen-Xiu scheme including the lan

d- surface processes; 2) the Blackadar scheme; 3) the Blackadar plus a land-surface sche

me.• Dynamic nudging: upper-air plus surface winds observations• Integration time: 1200 UTC 5 - 1200 UTC 16 August 2002

Nested Domains

Vsfc from the Plen-Xiu scheme

Vsfc from the Blackadar scheme

Vsfc from the Blackadar + a land-surface scheme

Tsfc from the Plen-Xiu scheme

Tsfc from the Blackadar scheme

Tsfc from the Blackadar+ a land-surface scheme

Qsfc from the Plen-Xiu scheme

Qsfc from the Blackada scheme

Qsfc from the Blackadar + a land-surface scheme

3. Summary and Conclusions:

• It appears that the Blackadar scheme exhibits a better correspondence to the observed than the other two schemes, but does not capture well the observed diurnal pattern of humidity.

• While the Plen-Xiu scheme shows a better correspondence to the observed humidity, it fails to perform well for wind speed and temperature.