The ASWAN project

Towards a very high resolution HiRLAM.

created at 06-09-1999.

Limited area modelling is moving more and more towards the very high resolution mesoscale. The models that produce these forecasts have their own analysis and have to be initialized just like the normal limited area models. The observations that are used in the analysis must contain information on the scales that are resolved in these models (5-20 km). The conventional observation network can deliver these measurements near the surface in the Netherlands, due to the high density of synoptic stations. However, little information is available above the surface. A radiosounding is launched every 6 hours, but at the intermediate hours and at different places there is no information about the state of the upper air. Relatively new (remote sensing) measuring techniques do provide information about the lowest few kilometers of the atmosphere. A few of these relatively new systems are the wind-profiler and Radio Acoustic Sounding System (RASS). These systems provide vertical profiles of the wind (direction and speed) and temperature with a high resolution in time and space.

Aims

The impact of these new observation types on the mesoscale analysis and short-term forecast is studied in the ASWAN-project at KNMI. ASWAN stands for ASsessment of the inpact of Wind profiler/sodar data on the mesoscale wind Analysis in the Netherlands. The specific aims within ASWAN are:

to study the impact of the profiler/sodar observations on the mesoscale analysis and short-term forecast over the Netherlands and its surroundings;
to study the impact on the mesoscale analysis and short-term forecast of the shallow (100-200 m) artificial profiles created with the flux-routines (De Rooy, 1999);
to determine the optimum configuration of a profiler/RASS/sodar network in the Netherlands.

This study will be performed with a high resolution (5-10 km) version of HiRLAM (High Resolution Limited Area Model). This is a much higher resolution than the reference version of HiRLAM, which uses a resolution of 50 km.

Below you can find an examples of high-resolution analys and short-term forecasting as produced with the high resolution HiRLAM:

Health warning: these plots are experimental products. The validity and timely updates are not guaranteed. At this page you will only find outdated, comercially unattractive information.

todays animation

An animation example.

yesterdays analysis in gif-format or postscript.

a 3-hour forecast based on yesterdays analysis in gif-format or postscript.

For more information about ASWAN, please contact:

Sander Tijm (tel 030-2206518, email tijm@knmi.nl)

Hong Tong Wu (tel 030-2206887, email wu@knmi.nl)

This project is (partially) funded by the Ministry of Defense