Algeria-gdps-2000

WORLD WEATHER WATCH TECHNICAL PROGRES REPORT
ON THE GLOBAL DATA-PROCESSING SYSTEM FOR THE YEAR 2000

ALGERIA

National Meteorological Center
(BP 153, Avenue khemisti Dar-El-beida Alger)

This report summarize the global data processing system activities carried out at the National Meteorological Center of Algiers.

1. SUMMARY OF HIGHLIGHTS

The major events during 2000 are :

Implementation of a New version of the ETA/model.
Increase in the resolution of the ETA/model, from 50 km to 25 km.
Adaptation of some derived fields using the outputs of the ETA/model.
Quality control of the ETA/model.
Implementation and rent into service of the wam/model developped by Max-Plank Institut fur meteorologie, Hamburg, Germany, using the outputs (10 m winds) of the ETA/model.
Installation and operation of SADIS.
Installation and operation of MESSIR Aero.

2. COMPUTING FACILITIES

Main computer : 02 CDC CYBER 932 (Operating System NOS/VE)
Secondary computer : 02 Data General MV7800
SUN Workstations : 03 (Ultra30, sparc5) (Operating System UNIX)
PC: 10 with printers Laser or Epson
PDUS station : 01

3. DATA AND PRODUCTS FROM GTS IN USE

3.1 Data in Use

SYNOP + SYNOP/SHIP : 300

TEMP + TEMP/SHIP : 100

AIREP

SATEM

SATOB

3.2 Products in Use

GRIB Meteo-France : 620

GRIB KWBC : 620

GRIB EGRR : 520

GRIB ECMWF : 70

4. DATA INPUT SYSTEM

Fully automated system

5. QUALITY CONTROL SYSTEM

Automated quality control of incoming data based on horizontal consistency check for synop messages (comparison with climatological data) and hydrostatic vertically control for TEMP messages bye the WADE. When some data are not accepted by the system, the operator correct them and inject them again in the system.

6. MONITORING OF THE OBSERVING SYSTEM

Surface observations and upper data are monitored on the national level.

7. FORECASTING SYSTEM

The ETA limited area model (ETA/Algeria) is operationnally launched twice a day (networks 0000 GMT and 1200 GMT) providing 72 hours forecasts.

7.1 System Run Schedule

The forecasting system at the national meteorological center is based on the limited area model ETA/Algeria, which is launched twice a day (networks 0000 and 1200 GMT), providing 72 hours forecasts. The initial and the boundary conditions are downloaded via Internet from NCEP/Washington.

We also use in the forecasting centre, the outputs of the followoing models : Arpege, CEPMMT and Bracknell. The outputs of Arpège and Bracknell are used for short range forecasting (00-72 Hours), the outputs of the CEPMMT are used for medium range forecasting (96–144 hours).

The ensemble forecasts (120-240 hours) are used of ECMMT are used since March 2000.

7.2 Medium range forecasting system (4-10 days)

- Not available

7.2.1 Data assimilation, objective analysis and initialization

- Not available

7.2 .2 Forecast model

- There isn’t medium range forecasting model which is integrated at Algiers.

7.2.3 Numerical weather prediction producst

-The Numerical Weather Prediction products which are used at the National

Meteorological Center of Algiers are :

a. Arpege : (00-72 h)

H + T 500 hPa

H + RH 700 hPa

H + T 850 hPa

MSLP + Thickness 1000/700 hPa

Accumulated precipitations (12-24-36-48h)

b. CEPMMT : (24-144h)

MSLP

Geop 500 hPa

Wind +T 850 hPa

c. Bracknell (00-72h)

MSLP

Accumulated precipitation

Wafs

KWBC (00-72h)

Wafs

N.B: The products of Bracknell and the 850 hPa winds of the CEPMMT are received everyday by FAX.

7.2.4 Operational techniques for application of the NWP products

The NWP products of Arpege (Meteo-France) are used in the computation of

some derived fields as :

- LAPOT instability index, which is based on the equivalent potential

temperarture and combines the potential and latent instabilities.

- Divergence fields

- Vertical velocity at 850 and 700 hPa

- Q Vector

- Relative vorticity

- Isentropic poptential vorticity

- Symetric instability

7. 3 Short-range forecasting system (00 – 72h)

7.3.1 Data assilmilation, objective analysis and initialisation

The operational limited area model ETA/Algeria which is integrated at the NMC of Algiers uses the initial and lateral boundary conditions of the NCEP global model.

However, data assimilation process based on IO method is under development and the one based on Cressman method is running operationally.

7.3.2 Model

The limited area model ETA/Algérie, based on eta (h ) coordinate, was adapted to the Algerian region.

- Basic equations: Primitive equations

- Independent variables: Latitude, Longitude, h , Time

- Dependent variables: Temperature, horizontal wind components, specific humidity

- Diagnostic variables: Precipitation, vertical velocity, turbulent exchange coefficient

- Integration domain: 10° N to 60°N ; 30° W to 30° E

- Vertical coordinate: ETA (h ) coordinate with 24 levels

- Grid : Arakawa E grid

- Resolution: 55 km

- Advection scheme : Semi –Lagrangien advection scheme

- Boundary data : Lateral boundary conditions from the NMC global model, based on the networks of 0000 and 1200 GMT and updated every 6 hours up to 48 h, and every 12 hours from 48 to 72h.

- Time integration : Split explicit , Euler backward advection adjustment, time step 3 minutes.

- Orography : Silhouette mountains

- Physical parametrisation :

Large scale condensation
Modified Arakawa-Shubart convection scheme
Betts-Miller deep and shallow convection scheme
Mellor-Yamada level 2.5 turbulence closure model
for planetary layer, level 2 for surface layer.
GFDL radiation scheme
Ground surface processes and surface hydrology
Large scale and convective precipitation

7.3.3 Numerical Weather Prediction Products

The products (outputs of the ETA/Algeria model) which are available operationally are :

	Model	Model high resolution
Resolution	0.5 °	0.25°
Integration Domain	30 W - 30 E 10 N - 60 N	05 W - 11 E 27 N - 42 N
Time Forecasts	72 H	48 h
NWP Outputs	Z+T 1000, 850, 700, 500 hPa RH 850, RH 700 hPa Vertical velocity 850, 700 hPa Vorticity 500 hPa Pmer, T2m, DC (Dust Concentration), CL (Cloud Cover). Accumulated Precipitation (12h) every 06 h	Pmer, T2m, DC (Dust Concentration), CL (Cloud Cover). LI (latent instability) 1000/850 LI 850/700 hPa LI 700/500 hPa Potential Vorticity 315 K Potential Vorticity 330 K Divq Surface Divq 850 hPa Tetae surface Tetae 850 hPa Spe Humidity Surface Accumulated Precipitation (06) every 03 h

7.3.4 Utilisation of the NWP products at the National Meteorological center of

Algiers :

- Computation of derived fields, with the outputs of the following models : ETA/Algérie, Arpege and Bracknell.

- Synoptic interpretation on both screen (workstation and PC-software) and charts.

7.4 Specialized forecasts

The WAM model developped by the Max Plank Institut fur meteorology, Hamburg, Allemagne, is running operationnally, on a workstation. It uses the outputs (10 m winds) of the model ETA/Algeria.

7.4.1 Assmilation, objective analysis and initialisation

Not available

7.4.2 Models

Two models are available at the National Meteorological Center of Algiers : ETA/Algeria and WAM model (cycle 4). The first one is used for synoptic and meso-scale forecasts and also for research and development. The second one is used for the forecast of wave heights over the mediterranean sea.

The acquisition of transport and dispersion model of the pollution is sharply Wished.

7.4.3 Numerical weather products

Same as in 7.3.3

8. Verification of prognostic products

The following scores concerne the LAM ETA/Algeria which is running with about 50 km of resolution. The period of the control is three months (September to November 1999) and the parameter is : 2m temperature in °C.

The scores are realised for specified regions : The North-West, The Center, the North-East, the North sahara and the Southern of Algeria.

North-West

Validity	12h	24h	36h	48h
Bias	0.47	1.75	-0.41	1.66
Rmse	1.46	2.28	1.44	1.95

Center

Validity	12h	24h	36h	48h
Bias	0.04	0.82	-0.23	1.76
Rmse	1.90	2.41	3.31	2.36

c. North-East

Validity	12h	24h	36h	48h
Bias	0.39	1.64	-0.69	1.32
Rmse	2.22	2.80	2.79	2.12

North-sahara

Validity	12h	24h	36h	48h
Bias	- 0.38	1.03	1.53	2.60
Rmse	1.46	2.28	1.44	1.95

e. Southern Algeria

Validity	12h	24h	36h	48h
Bias	0.98	2.56	1.48	4.97
Rmse	1.90	3.14	1.53	5.30

9. Plans for the year 2001

Diffusion of the ETA/Algeria outputs to our national regions via the national network, (Algiers is identified by WMO as a CMRS type G). This products are also available on our web site. Diffusion of the wam model outputs, via our national network and via internet.

Development of a data assimilation based on OI method, and quality control based on three (03) checks.

The goal of the National Meteorological Center weather prediction system, with the collaboration of the World-Laboratory, is to provide accuracy meteorological forecasts, with a special priority to severe weather as storms, dust, deep cyclogenesis…

For this, a new version of the ETA model (meso-NH), will be implemented on a PC (Pentium III), before the end of the year 2000.

REFERENCES

On the impact on Forecast Accuraracy of the step-mountain (ETA) vs. Sigma coordinate, by Fedor Mesinger and Thomas L. Black

Scientific documentation of the ETA model, by Slobodan Ni-Kovic, Dragutin Mihailovi, Birrivoj Rajkovi

Documentation of the UB/NMC ETA model, by Lazi Lazid and Bosko Telenta