Abstract
This study uses weather radar observations collected from Research Vessel Investigator to evaluate the Australian weather radar network calibration monitoring technique that uses spaceborne radar observations from the NASA Global Precipitation Mission (GPM). Quantitative operational applications such as rainfall and hail nowcasting require a calibration accuracy of 1 dB for radars of the Australian network covering capital cities. Seven ground-based radars along the coast and the ship-based OceanPOL radar are first calibrated independently using GPM radar overpasses over a 3-month period. The calibration difference between the OceanPOL radar and each of the 7 operational radars is then estimated using collocated, gridded, radar observations to evaluate the accuracy of the GPM technique. For all seven radars the calibration difference with the ship radar lies within ±0.5 dB, therefore fulfilling the 1 dB requirement. This result validates the concept of using the GPM spaceborne radar observations to calibrate national weather radar networks (provided that the spaceborne radar maintains a high calibration accuracy). The analysis of the day-to-day and hourly variability of calibration differences between the OceanPOL and Darwin (Berrimah) radars also demonstrates that quantitative comparisons of gridded radar observations can accurately track daily and hourly calibration differences between pairs of operational radars with overlapping coverage (daily and hourly standard deviations of ~ 0.3 dB and ~ 1 dB, respectively).
Highlights
Looking at the time series of Global Precipitation Mission (GPM) calibration estimates for other radars than 63 and considering the expected typical error of 2 dB for individual GPM overpasses as a guideline, it seems reasonable to assume that the calibration of the OceanPOL, Warruwi (77), Dampier (15), Broome (17), and Serpentine (70) radars has not changed over the observational period either, with fluctuations around the mean calibration error estimate less than ~1.5 dB
We have used collocated observations between spaceborne, ship-based, and ground-based radars collected during the YMCA and Optimizing Radar Calibration and Attenuation corrections (ORCA) experiments to gain further insights into the suitability and accuracy of using spaceborne radar observations from the GPM
Using collocated weather radar observations between the OceanPOL radar on RV Investigator and 7 operational radars off the northern and western coasts of Australia, we found that for all seven operational radars, the calibration difference with OceanPOL was within ±0.5 dB, well within the 1 dB
Summary
RV Investigator OceanPOL radar observations used in this study were collected as part of two back-to-back field experiments. The second field experiment (ORCA) was conducted during a transit voyage to relocate RV Investigator from Darwin to Perth, Western Australia. This transit voyage was an ideal opportunity to collect collocated radar samples with several operational radars along the coast (Fig. 1). In this study we will use all these collocated samples to quantify how well the calibration estimate provided for each radar by the GPM technique agree with the calibration estimates obtained using OceanPOL as a second and more accurate source of reference
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
