The weather radar is the exclusive technical means, which enables remote sensing (teledetection) of the atmosphere condition and the phenomena like clouds, rainfall, snow and hail, thunderstorms and the wind convergence zones. These can be detected in real time and over a large area, 150 to 200 kilometres from the radar itself. Unlike the standard methods, the radar detection allows for continuous monitoring of the phenomena above referred to and determination of convergence between their development and the relevant forecasts. This is of particular importance for detection and monitoring of the intense precipitation zones. Within the radius of up to 100 kilometres from the radar the precipitation may be roughly quantified (the intensity, hourly totals and 24 hour totals and the average total precipitation in a given basin). This is crucial for model hydrodynamic hydrological and meteorological models.

Penetration of the fixed precipitation measurement networks is - due to the very nature of such networks - quite low and the information coming from the measurement facilities is delayed to various extents, depending on the network automation level. The surface precipitation points, connected to the radar network are used for radar calibration. Together with the system for automated meteorological and hydrological measurements developed under the B-2.1 component the radar system will be a very up-to-date tool for the effective and credible hydrological and meteorological protection of the population and the national economy.

The aim of the Project is to enhance, integrate and launch the system of weather radar for the purposes of the hydrological and meteorological protection of the national economy and the population, in particular in the cases of hazards. The July 1997 and May 1998 floods evidenced the importance of the knowledge on precipitation range and intensity and occurrence of other dangerous atmospheric phenomena for the effective hydrological and meteorological management and early warning.

Enhancement of the weather radar system POLRAD

Radar Pastewnik

Radar Ramża

Radar Legionowo

The construction of the IMGW radar system started in the 80-ties, although the studies and preparatory work were launched much earlier. On the basis of the data, received from the then operated MRL-2 radar advanced scientific research was carried out relating to the use of the radar data for the meteorological and hydrological purposes. In 1992 the installation of the later MRL-5 radar in Legionowo enabled intensification of work and development of, inter alia, the algorithms and programmes for the quantitative precipitation estimates.

In 1995, thanks to the loan extended by the World Bank another radar was commissioned, i.e. the modern Doppler radar produced by GEMATRONIK. This unit has been located on the Ram?a hill near Katowice. In 1999 own funds and subsidies coming from various sources were spent for the purchase of another GEMATRONIK radar, to be installed near Pastewnik . The actions have been undertaken and are continued to settle the formal location issues relating to the subsequent structures in Pozna?, Szczecin, Gda?sk and in the vicinity of Tarnów and Rzeszów. Substantive cooperation has been entered into with the meteorological organizations of the Germany, Czech Republic and Slovak in terms of the use of data and research results.

The CERAD CEE radar system, as in 1998

Assembly of antenna of the Ramża radar, 1995

Single weather radar supports the hydrological and meteorological management of the area at between 100 and 200 kilometre radius. Thus for the protection of the entire country a system of radar is necessary, comprising 8 units in the case of Poland. Additional advantage of the radar network is the capacity of simultaneous monitoring of the same phenomena by 2 or 3 radar, which many times increases the probability of dangerous phenomena detection and preparation of the appropriate warning. The programme for the development of the weather radar system POLRAD covers the erection and commissioning of 8 radar stations, based on the modern weather Doppler radar, coherent if practicable. In view of the operating cost optimisation all radars should be automated and should not require on-site operators, since their operation, control and maintenance would be remote. Supreme performance and reliable telecommunication links will be used for data transmission to the central control, processing and maintenance system. The radar data will be used both for the online hydrological and meteorological management and for complex hydrodynamic hydrological and meteorological models. The radar system will be, in functional terms, coupled with the systems of the automated hydrological and meteorological measurements, the automated lightning detection network, the system for hydrological and meteorological forecasting and the forecasting and decision making system

Thus organised system will enable precise identification the precipitation area. Given the intense and spread precipitation, particularly in the mountain regions this is of a decisive importance for the quality of meteorological forecasting and hydrological protection.

The radar network data will be used in all fields of management provided by IMGW. Pre-dominantly this will be the flood management and the system of early warning on the dangerous phenomena. This concerns mainly the protection of the civil aviation, energy sector and water management facilities, railway transport, agriculture and provision of information for media and tourism.

The technical work will include:

• Erection and commissioning of 4 new radar stations near Poznań, Szczecin, Tarnów and Rzeszów.
• Their integration with currently operated radar stations, namely Legionowo near Warsaw and Ramża near Katowice and the radar in Pastewnik near Wrocław. The MRL-5 radar in Legionowo is obsolete in technical terms and worn out. In order to achieve uniformity of the system and obtain the tool for the research and implementation work important for the entire system the radar should be replaced with the unit of the type used for the entire network. The Ramża and Pastewnik stations are equipped with the GEMATRONIK Doppler radar. This station should be integrated within the uniform system of data transmission, processing and conversion into graphical form.
• Preparation of location for the radar near Gdynia. The limited resources of the B-2.9 subcomponent render impossible the installation of the Gdynia radar. However, it would be of value to start the location-related and preparatory work, so that the radar station is built, once the required funds are mobilised.
• Launch of the communication and data transmission system, which is critical for operations of the weather radar system. The data transmission through the fixed lines, unreliable in Poland, should be replaced with the satellite links of at least 64 kB/s flow capacity.
• The equipment and launch of the Data Processing Centre, the central point for reception of the data coming from all radars within the system, the data processing, preparation of the collective radar map and data forwarding to the users and for further processing by other systems and forecasting models. Collective radar map will be transmitted through the satellite or fixed link and available for reception to in Local Offices and by other users having the appropriate equipment.
• Introduction of POLRAD data to the following electronic data interchange systems: COST-75 (European weather radar network), CERAD (Central Europe weather radar network), NORDRAD (Scandinavian radar network) and Internet.

Radar ddisplay of a large thunderstorm cell 17 June 1991, 8 Pm, Legionowo radar

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Vertical radar cross-section of large, thunderstorm cell 17 June 1991, 8 PM, Legionowo radar

• Database and data management module;
• The collective radar map module;
• The module for combination of the radar and satellite data
• Nowcasting module;
• The precipitation module, enabling determination of:
  • Showers;
  • Precipitation in the catchment
  • Basin precipitation;
  • Potential precipitation.
• Warning modules:
  • Detection of strong wind and front zones
  • Detection of thunderstorm turbulence;
  • Hail detection;
  • Intense precipitation detection;
  • Vertical cross-section module (up to more than 10 kilometres);
  • Object tracking module.

Ramża radar near Katowice

Control panel of the MRL-5 radar at Legionowo; from left radar automation equipment

Since the radar does not measure the precipitation directly at the ground level, but rather the albedo of a certain air mass distant from the earth surface, the radar precipitation estimate must be preceded with the appropriate revision procedure. This includes, inter ail, identification and rejection of the clearly false images, identification by combination of satellite and radar data, comparisons and the network radar calibration on the basis of the real-time hourly data from the pluviometry network and calibration against the longer measurement series, for instance the weekly ones, the vertical albedo correction relating to the physical conditions of the wave, propagation in the atmosphere and revision of maps from the individual radar based on the collective map.

Due to the movements of the precipitation areas within the range of the given radar, occurring during the 6-hours forecasting time it is necessary to expand the range by using the high resolution METEOSAT satellite data coming in two spectrum ranges. This enables detection of the precipitation, even if outside the range of the given radar. The collective radar map (i.e. based on the observations of a few radar units), the precipitation areas indicated in the satellite images and the measurement data, combined in an optimum fashion should be the preliminary field for the forecast.

The forecast of precipitation intensity and the cumulated precipitation for the following 6 hours should be repeated every 30 minutes. At the first stage the vectors should be determined of the precipitation fields' movement, the inertial forecast for the following hour prepared and comparison should be made of the result with the forecast wind area derived from the mezoscale or local model. Depending on the precipitation type the method should be selected, i.e. the advective method using the forecast wind field or the combined one.

The precipitation forecasts should be continuously verified and assessed by means of comparison with the actual precipitation recorded, and the comparison results should be used for correction of the analysis and forecasting practice [algorithms]

The system will be automated and provide synopticians, meteorologists and hydrologists with access to most credible analytical and forecast data

The software should be open for the user modification, in particular for integration of the modules, developed in the course of the IMGW research and obtained through the cooperation with other countries.

Level of radiowave emissions as compare to security standars