Calibration scans are important for the maintenance of data and the quality of the information that radars output. In this study we looked for a temperature dependency in a full year’s worth of differential reflectivity (ZDR) calibration scan data collected by the X-band Teaching and Research Radar (XTRRA) located near the Purdue University campus. In a vertically pointing calibration scan, the radar scans the drops from below while rotating. From this angle, the overall shape will be circular, which corresponds to a ZDR value of approximately 0 dB. To process the data for the year 2021, a Python script was written to be used by the students in Radar Meteorology (EAPS 523) as part of their Course-based Undergraduate Research Experience (CURE). The ZDR mean values were then compared to the temperature data from the FAA Automated Surface Observing System (ASOS) station located at the Purdue Airport in West Lafayette (KLAF). In cases where temperatures changed quickly diurnally, the ZDR mean changed inversely to temperature, a quick rise in environmental temperature corresponded to a decrease in ZDR mean relative 0 dB, and vice versa. A positive correlation of 0.79 indicated a relationship between ZDR and temperature. The XTRRA is housed in a radome and has temperature regulation via the internal air conditioning systems in Wang Hall. We speculate that there isn’t a stronger relationship due to the KLAF ASOS station experiencing more solar radiation and therefore being warmer than the cooled radar, as well as the fact that XTRRA and the station are situated 3.6 km apart.
"Characterizing Differential Reflectivity Calibration Dependence on Environmental Temperature Using the X-band Teaching and Research Radar (XTRRA): Looking for a Relationship between Temperature and Differential Reflectivity Bias,"
The Journal of Purdue Undergraduate Research:
Vol. 13, Article 6.