HR: 16:45h
AN: A34B-04    [Abstracts]
TI: An Assessment of the ECMWF Model Simulations of the Arctic Clouds Observed During the ARM Mixed-Phase Arctic Cloud Experiment
AU: * Xie, S
EM: xie2@llnl.gov
AF: Lawrence Livermore Nat'l Lab, ASD/L103, LLNL, Livermore, CA 94550 United States
AU: Klein, S
EM: klein21@llnl.gov
AF: Lawrence Livermore Nat'l Lab, ASD/L103, LLNL, Livermore, CA 94550 United States
AU: Beljaars, A
EM: Anton.Beljaars@ecmwf.int
AF: ECMWF, ECMWF, Reading, RG29AX United Kingdom
AU: Boyle, J
EM: boyle5@llnl.gov
AF: Lawrence Livermore Nat'l Lab, ASD/L103, LLNL, Livermore, CA 94550 United States
AU: Fiorino, M
EM: fiorino@llnl.gov
AF: Lawrence Livermore Nat'l Lab, ASD/L103, LLNL, Livermore, CA 94550 United States
AU: Hnilo, J
EM: jhnilo@llnl.gov
AF: Lawrence Livermore Nat'l Lab, ASD/L103, LLNL, Livermore, CA 94550 United States
AU: Long, C
EM: chuck.long@pnl.gov
AF: PNNL, PNNL, Richland, WA 99352
AU: Phillips, T
EM: phillips14@llnl.gov
AF: Lawrence Livermore Nat'l Lab, ASD/L103, LLNL, Livermore, CA 94550 United States
AU: Potter, G
EM: potter2@llnl.gov
AF: Lawrence Livermore Nat'l Lab, ASD/L103, LLNL, Livermore, CA 94550 United States
AU: Zhang, M
EM: mzhang@notes.cc.sunysb.edu
AF: SUNY Stony Brook, MSRC/SUNY at Stony Brook, Stony Brook, NY 11794
AB: The performance of the European Centre for Medium-Range Weather Forecasts (ECMWF) model in simulating Arctic clouds and their associated radiative properties is evaluated using observations collected during the Atmospheric Radiation Measurement (ARM) October 2004 Mixed-Phase Arctic Cloud Experiment (M-PACE) at its North Slope of Alaska (NSA) site. The model shows overall good skill in predicting the bulk characteristics of the observed Arctic cloud systems but it tends to overestimate the high level clouds and substantially underestimate the middle level and boundary layer clouds. The latter leads to a large underestimation of cloud liquid path during that period. The surface upward shortwave radiation is largely underestimated, mainly due to the underestimation of the surface downward shortwave radiation and surface albedo. The problem in the surface albedo is primarily associated with errors in surface snow prediction. In the presence of boundary layer clouds, the model largely underpredicts the surface downward longwave radiation and overpredicts the outgoing longwave radiation at the top of the atmosphere, consistent with the model underproduction of boundary layer cloudiness and cloud liquid water path. Principally due to the underestimation of the surface downward longwave radiation, the model shows a much larger energy loss (-20.9 W m-2) than the observed (-9.6 W m-2) at the surface during the M-PACE period. For comparison, the Arctic clouds simulated by the NCAR CAM3 and GFDL AM2 in their short-range weather forecasts will be also discussed in the meeting.
DE: 0321 Cloud/radiation interaction
DE: 1223 Ocean/Earth/atmosphere/hydrosphere/cryosphere interactions (0762, 1218, 3319, 4550)
DE: 1699 General or miscellaneous
DE: 3310 Clouds and cloud feedbacks
DE: 3349 Polar meteorology
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005