ewglam oct 2003 1 some recent developments in the ecmwf model mariano hortal ecmwf thanks to: a....
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EWGLAM Oct 2003 1
Some recent developments in the ECMWF model
Mariano Hortal ECMWF
Thanks to: A. Beljars (physics),
E. Holm (humidity analysis)
EWGLAM Oct 2003 3
Linear least square fit interpolation
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EWGLAM Oct 2003 4
SETTLS with LLSI at both departure and arrival in the vertical trajectory computation
H+12 from 26-09-2002 at 00z H+12 Z10 from 28-12-2002 at 12z
EWGLAM Oct 2003 5
Recent developments in the ECMWF physics
Radiation (aerosol climatology) Convection and clouds Clouds and boundary layer Land surface Simplified physics for linear and adjoint applications Orography (MAP reanalysis, turbulent orographic form drag)
EWGLAM Oct 2003 6
Radiation
26R3:•Radiation on a separate grid to save costs (instead of 1 out of 4 points). In T511 model radiation is done on T255 grid.
•New aerosol climatology
•Post-processing of PAR and UV-B
Under development: •RRTM short wave
•McICA: Monte Carlo Independent Column Approximation to represent cloud overlap and inhomogeneous clouds by using different samples of the clouds in the different computational intervals (140 g-points in 16 spectral intervals)
EWGLAM Oct 2003 7
Convection and clouds
26R3:•Clean-up of code and improved numerics leading to better representation of ice fallout
•New cloud base/top algorithm based on entraining plume
•Convection from any layer in lowest 300 hPa
•Revised initiation of convection with perturbed parcels (in T and q) starting from mixed layer properties
•Reduced water load in updrafts through more efficient microphysics
•Increased entrainment
EWGLAM Oct 2003 10
Clouds and boundary layer
•A statistical cloud scheme based on variance of total water is under development
•Moist boundary layer mixing scheme is nearly finished (better
stratocumulus)
EWGLAM Oct 2003 11
Land surface
•Fully implicit tile coupling with less noisy results for the tiles with small fraction
Tiles:• Water• Ice• Wet skin• Low vegetation• Exposed snow• High vegetation• Snow under vegetation• Bare soil
EWGLAM Oct 2003 12
Land surface•An Extended Kalman Filter (EKF) has been developed for soil moisture analysis (as part of the EU project ELDAS).
•EKF can assimilate SYNOP-T/RH, Meteosat heating rates, and microwave brightness temperatures
Single column simulation for MUREX (France), 1. Control with no data assimilation, 2. EKF with microwave Tb 3. EKF with SYNOP T/RH, 4. EKF with surface heating rates
EWGLAM Oct 2003 13
Physics in relation to data assimilation
•Linear and adjoint of radiation code has been developed and is currently under test
•Simplified cloud and convection schemes have been developed for linear and adjoint applications
•Experiments are under way to evaluate assimilation of microwave rain products and brightness T in rainy areas via 1DVAR of TCWV which is assimilated in 4DVAR
•TRMM precipitation radar is used for verification
EWGLAM Oct 2003 14
Physics in relation to data assimilation
TRMM-PR
assim. of TMI Tb
assim. of TMI-rain rate
first guess
EWGLAM Oct 2003 15
Orography: MAP reanalysis
• Reanalysis with all the additional MAP data is available
TCWV from GPS 21-10-1999
TCWV from MAP reanalysis, T511
TCWV from operations 1999, T319
EWGLAM Oct 2003 16
New scheme for turbulent orographic form drag•Alternative to effective roughness length concept•Drag is distributed in vertical and implemented on model levels (Brown and Wood, 2003)•Scales between 5 km and 10 m are represented by this scheme •Universal orographic spectrum is assumed to account for scales smaller than 5 km•Standard deviation of orography at scales between about 10 to 2 km is used to drive the scheme (from 1 km data base)
Comparison of orographic drag and turbulent surface drag (from vegetation) from new scheme with fine scale model results. Expressed as drag coefficient versus terrain slope.
EWGLAM Oct 2003 17
Nonlinearities in the humidity analysis
Humidity is bounded from below (>0) and restricted close to saturation by condensation.
Analysis increments behave asymmetrically at different levels of relative humidity.
A new humidity analysis accounts for this through nonlinear flow-dependent change of variable,
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EWGLAM Oct 2003 18
Some humidity analysis results
With a better background error description, better use is made of humidity observations.
An example is given by HIRS-12 humidity sensitive radiances.
The new humidity analysis (bottom) has removed unrealistic outliers in the background error description.
This results in better humidity forecasts.