Overview of the CP2 Radar Facility

Technical Characteristics of the CP2 Radar

Redbank Plains Radar Site Maps and views

Introduction

The Australian Bureau of Meteorology has acquired the CP2 weather radar for the purposes of research activities within Australia. Present plans call for the radar to be deployed within the greater Brisbane area. It will function as a state of the art Doppler /Polarimetric weather radar, designed primarily to aid atmospheric research. It will also serve to provide weather information to weather forecasters as required. It will form the basis of a research and development program between the Commonwealth Bureau of Meteorology Research Centre (BMRC) and the University Corporation for Atmospheric Research, Atmospheric Technology Division (ATD) USA.

It is currently proposed to site the CP2 Radar at a location that ensures the major

Population centres and rainfall catchments of South-East Queensland, particularly

Brisbane and the Gold Coast are covered. There are a number of sites being considered which will allow the radar to be strategically located to provide maximum benefit to the communities of South-East Queensland.

Expected Outcomes

From the use of this radar facility and the joint research and development activities there are a number of expected outcomes including:

Improved Quantitative Precipitation Estimates (QPE) based on radar and in-situ measurements;
Improved understanding of precipitation processes with emphasis on orographic rainfall;
Improved Quantitative Precipitation Forecasts (QPF) for near-real-time forecasting (nowcasting - radar) and short range forecasting using computer modelling techniques on the Numerical Weather Prediction (NWP) systems;
Improved rainfall mapping and hydrological modelling based on radar and NWP techniques;
Regional hourly rainfall accumulations, 100 km scale;
Urban QPE for 5-10 minute flash flood forecasts;
Improved nowcasting of convective weather systems and severe weather including, hail, windshear, downbursts, lightning;
Development of NWP data assimilation techniques based on radar data;
Establishment of verification procedures in QPE, QPF and nowcasting;
Improved radar calibration and signal processing algorithms.

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Technical Characteristics of CP2

Characteristic	CP2 S-Band	CP2 X-band
Wavelength (cm)	10.7	3.2
Peak Power (kW)	1000	200
Pulse length(ms)	0.17-1.0	1.0
PRF (s^-1)	<1700	<1000
Antenna Type	Centre feed paraboloid	Two cassegrain paraboloids
Feed Type	Potter horn	Rectangular Waveguide
Beamwidth (degrees)	0.93	0.94
Az coverage (degrees)	360	360
El Coverage (degrees)	90	90
Polarisations radiated	LIN H, LINV	LIN H
Simultaneous 2 channel reception	N	Y
Polarisation Received	Copolar to TX	LIN H & LIN V
Max Sidelobe level (dB)	-21	~-30
Max Antenna Linear X-POL lobes (dB)	-21	-36
Polarisation Control Method	Ferrite Switch	NA
Polarisation Control rate	Pulse by pulse	NA
Channel to Channel Isolation (db) ex Antenna	>30	>30
Doppler Capability	Y	N
Number of Range Gates	1024	1024
Range Resolution (m)	> 30 typically 150	> 30 typically 150
Polarisation Quantities measured	Z, Z_DR, fdp, r_HV	Z, LDR,

As summarised above CP2 is capable of measuring Doppler velocity and dual-frequency reflectivity at S and X-Band along matched beams. Polarimetric variables are also derived at S and X-band.

The CP2 digital receiver signal processing system is planned to employ a state of the art signal processing system. Currently under consideration is the new NCAR PIRAQ 3 unit. Prior to its purchase by the Bureau CP2 was extensively refurbished by NCAR to provide as good as new status and subjected to extensive acceptance testing.

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Radar Site

The siting requirements for such a facility are unique and require careful consideration of the local environment and the effects associated with it. The CP2 radar is limited to being installed on the ground due to the nature of its mechanical structure and the protective inflatable fabric dome cover (radome) associated with it (refer to the example pictures on the first page).

An ideal site is one where the radar will have an unobstructed horizontal line-of-sight view to the horizon in all directions. This means no obstructions from trees, terrain and structures from the location of the radar dish to the horizon. Also, to be effective for the early detection of developing storms and associated severe weather phenomena, the radar needs to be located in lower altitudes (less than 100m), closer to the coast. This rules out locating it on the nearby hills and mountains to the west of Brisbane. To achieve this, the CP2 radar will ideally need to be located on a small hill or mound. Also, we aim to find a site where no people are residing within 200-300 meters (minimum) of the facility due to the likely public outcry and reaction. These factors make the task of finding a site very difficult in the Brisbane Coastal area.

The current site under consideration is located at Redbank Plains to the WSW of Brisbane near Ipswich. Some maps and views of the proposed site can be viewed at: Redbank Plains Maps and Views

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Proposed Site Infrastructure

The site for the radar will comprise the radar antenna installed on a concrete foundation with an air pressurised fabric Radome cover over it. The 13 Tonne (plus) antenna structure requires significant reinforced concrete foundations on stable ground. The Radome must remain pressurised at all times and is kept pressurised by a primary air blower with a second higher capacity blower used to add extra pressure, and therefore rigidity, in the event of high winds. A third petrol-operated blower is included as an emergency in the event of mains power failure. The radar electronics and equipment are intended to be housed in a building either under the radar platform or alongside the Radome. There will also be an emergency diesel powered generator to supply power to the site to maintain operations in the event of a mains power failure.

The CP2 radar is a one-off radar facility for Australia and as such it is intended that we locate all its spare parts and components with it. This means that the building will require a storage area within. There are also some spare antenna panels and components that will need to be stored within the radar compound.

Below are some draft proposed site and building layout plans that are currently under consideration and similar to those likely to be implemented. Note: there are two building concepts currently under consideration, both shown below. The first is a building constructed under the antenna platform being used as a concept to elevate the radar to a higher level and the other is a building alongside the Radar dome. In the drawings below there is a fairly large, permanent style building shown in the adjacent building concept which will probably not be the style used if this concept is chosen, it will more likely be a demountable style building.

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Weather Forecasting Group

Overview of the CP2 Radar Facility

Introduction

Expected Outcomes

Technical Characteristics of CP2

Radar Site

Proposed Site Infrastructure