The NSSL ATD through NWS Eyes: An Assessment of Base Data Quality

As the National Weather Service (NWS) Weather Surveillance Radar - 1988 Doppler (WSR-88D) systems approach the end of life, research is underway toward Phased Array Radar (PAR) as a potential replacement. The National Severe Storms Laboratory (NSSL) Advanced Technology Demonstrator (ATD) is a proof-of-concept, S-band, dual-polarized PAR in Norman, OK. Research efforts with the ATD range from polarimetric calibration and advanced signal-processing and scanning techniques to meteorological analysis and interpretation of the data, with NSSL engineers and meteorologists working closely together to support our complimentary goals. A fundamental component of WSR-88D radar interpretation for NWS meteorologists is base data analysis, which is defined here in the context of NWS mission critical operations. The NWS forecaster’s reliance on radar base data interpretation (among other data sources) varies as a function of weather threats, e.g., rapidly evolving features with all types of severe convection require continuous radar data assessment. The foundation of radar base data quality must be sufficient to allow NWS forecasters to interpret the atmospheric state with minimal hindrances such as range folding or velocity aliasing, clutter contamination, noisiness (i.e., high variance), sidelobe contamination, etc. In contrast, there is one radar data artifact exception, the Three Body Scatter Spike (TBSS), which is almost always considered useful by NWS meteorologists, as it increases confidence in the presence of large hail. This NWS forecaster qualitative relationship with radar base data is complex, yet it is foundational to the cognitive domain of NWS warning decision making. The ATD offers advanced processing and scanning techniques, many of which are not used with the WSR-88D, that demonstrate value for NWS operations. For example, range oversampling provides data, especially dual-polarization variables that are significantly less noisy than the WSR-88 D. Thus signatures such as ZDR columns and KDP cores are more readily apparent for forecaster interpretation. An overview of weather events collected by the ATD is provided, with an emphasis on base data quality, and potential benefits for NWS operations.