Engineering Evaluation of the ARM X band Precipitation Radars at SGP
Authors
V. Chandrasekar — Colorado State University
Alexander Morin — Colorado State University
Zach Mendez — Colorado State University
Sergio Daniel Graniello — Colorado State University
Amit Dutta — Colorado State University
Iosif Andrei Lindenmaier — Pacific Northwest National Laboratory
Nitin Bharadwaj — Pacific Northwest National Laboratory
Category
ARM infrastructure
Description
This paper summarizes the results of the engineering evaluation of the X-SAPR system at Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) facility, located in Billings, Oklahoma. The three X-SAPRs are deployed in a triangular array around the facility, each being a full-hemispherical scanning polarimetric Doppler radar transmitting with both H and V polarizations. Three radars are located in Billings, Garber, and Lamont, each site being designated SGP/I4, SGP/I5, SGP/I6, respectively.
The engineering evaluation conducted on each of the three radars consisted of various measurements of major radar subsystems, including a) the transmitter chain, b) the receiver chain, c) the antenna positioner, and d) data acquisition systems.
The average power, spectrum, and shape of the transmitted pulse were measured to gather information on the performance and consistency of the transmitter. Solar calibration was done for each radar in order to document any error in the antenna-pointing angle. Transmit and receive losses were measured and documented for both the horizontal and vertical waveguide channels. The receiver calibration measurements were recorded to characterize the receiver response to a CW signal at various power levels. In addition the dual-polarization performance of the entire receive, chain was characterized using an external reference source.
In addition, range time signal samples were collected and evaluated in detail to document the radar signal characteristics to be compared against theoretical properties such as the distribution of In-phase and Quadrature signals, amplitude and power distributions, precipitation parameter variances such as reflectivity, differential reflectivity, differential phase, and co-polar correlation coefficient. The results are summarized and placed in the context of the recommendation of the weather radar calibration handbook. (V. Chandrasekar, L. Baldini, N. Bharadwaj and P. L. Smith, "Calibration procedures for global precipitation-measurement ground-validation radars," in URSI Radio Science Bulletin, vol.2015,no.355,pp.45-73,Dec.2015. doi: 10.23919/URSIRSB.2015.7909473 )
