Space weather capabilities of low frequency radio arrays

Radio arrays currently operating below 1 GHz have observed interplanetary scintillations of radio sources to derive valuable information on the density and velocity of the solar wind and coronal mass ejections. New large radio arrays are currently in the design and development phase, and are characterized by wide fields of view, high sensitivity, and multiple beam capabilities. One such array, the Mileura Widefield Array – Low Frequency Demonstrator (MWA-LFD) in Western Australia (26.4S, 117.3E), is being designed for operation at 80 to 300 MHz. Its characteristics include a 15-50 field-of-view, 16 simultaneous beams, and an effective collecting area of 8000 m at 200 MHz with 32 MHz instantaneous bandwidth resulting in a point-source sensitivity of 20 mJy for an integration time of one second. The array consists of 8000 dual-polarization dipoles, clustered in sub-arrays that are spread over a 1.5 km diameter and connected to a central digital signal processor. The MWA-LFD will participate in the global network of observatories that monitor solar bursts and interplanetary scintillations, and will improve the spatial and time resolution of solar wind characterization by increasing both the number of radio sources that can be used for scintillation measurements and the number of observations that can be made in a given time period. In addition, the MWA-LFD will be able to provide observations of the Faraday rotation of polarized radio sources, thus allowing the possibility of determining the evolution of the magnetic field in a coronal mass ejection. The design of the array, the signals expected to be received by the array, and the requirements and challenges for the space weather observations are discussed in this paper.