The Airborne Phased Array Radar (APAR) Observing Simulator

The National Science Foundation (NSF) of the United States approved the Airborne Phased Array Radar (APAR) Mid-scale Research Infrastructure-2 proposal in 2023 to develop the next generation airborne polarimetric, Doppler weather radar mounted on the NSF/National Center for Atmospheric Research (NCAR) C-130 aircraft. Development of anew observing system iscritical for the advancement of scientific understanding of weather phenomena. These instruments establish a proving ground for future operational transition while also providing tools for the research community. One of the issues with developing newinstrumentation is the unknown performance characteristics of the instrument and the subsequent unknowns inuncertainty in measurements. The APAR Observing Simulator (AOS) was developed to understand APAR's measurementcapabilities for high-impact weather events. Using Cloud Model 1 (CM1) and Weather Research and Forecasting (WRF) modeloutput to provide various storms of interest and their surrounding environments, simulated NCAR C-130 flights areoperated within the model space. Radar moments are determined using the Cloud Resolving Model Radar Simulator (CR-SIM). The output can be examined directly or passed through additional tools to analyze various aspects of the data collected during each flight.

AOS is developed as an open-source software. The first version of AOS software will be released to the research and operational community in the last quarter of 2024. This paper will provide an overview of the AOS and report the recent development of the AOS to better simulate the characteristics of a phased array radar on a moving platform. In addition, the authors will outline how AOS will be used as a component in the future APAR data analysis software system.