Summary of the ARM activities at ECMWF from 2007-2009

Maike Ahlgrimm ; Anton Beljaars

关键词: CLOUDS;    RADIATIONS;    CLIMATE MODELS clouds;    radiation;    climate models;    numerical weather prediction;    cloud lidar;   

DOI  :  10.2172/983195
RP-ID  :  DOE/ER/64400-1
PID  :  OSTI ID: 983195

学科分类：环境科学（综合）

美国|英语

来源: SciTech Connect

【 摘 要 】

The European Centre for Medium-Range Weather Forecasts (ECMWF), as one of the leading centres in numerical weather prediction, has been an active user of observations for model evaluation for many years. Many examples exist where detailed experimental studies have inspired model improvement. To establish a link between the Atmospheric Radiation Measurement (ARM) research and ECMWF's model development, funding was provided for an \u201cARM fellow\u201d at ECMWF. Furthermore, ECMWF has been working closely with ARM related projects for many years. ECMWF provides operational analysis data for the ARM stations (permanent and mobile) as background meteorological information and ECMWF has implemented the Rapid Radiative Transport Model long wave and short wave schemes as radiation codes in the operational system. These codes were developed at Atmospheric and Environmental Research Inc. with ARM support and were extensively evaluated using detailed ARM observations. This short report describes the history of the ARM-fellowship at ECMWF and summarizes the achievements over the last 3 years. The emphasis of the ARM funded work over the last 3 years has been on further development and evaluation of a new shallow convection scheme in the context of ECMWF's Numerical Weather Prediction (NWP) system. The shallow convection scheme is based on the DualM approach which combines Eddy Diffusion with a Dual Mass flux concept. One of the mass fluxes describes the dry updraughts, whereas the second updraught saturates at cloud base and penetrates into the cloud. The new scheme was optimized using single column cases from a wide range of climatological regimes. Further evaluation of the 3-dimensional model using Lidar data from space (CALIPSO) clearly indicates that the resulting cloud structures are much more realistic than the ones produced by the control model (Tiedtke mass flux scheme). Additionally, data from the ARM mobile facility in 2006 in Niamey has been used to evaluate the surface energy balance in the ECMWF model. It turns out that substantial errors exist in the radiative and turbulent fluxes in the Sahel. These energy budget errors are believed to be detrimental to the simulated flow over West Africa. This was the first time that such verification was possible. It is obvious that the radiative impact of aerosols needs further investigation.