NEXRAD Dual Polarimetric Hazard Products for Aviation

NEXRAD Dual Polarimetric Hazard Products for Aviation*

David J. Smalley, Michael F. Donovan, Earle R. Williams,
Betty J. Bennett, James M. Kurdzo, Richard F. Ferris
Massachusetts Institute of Technology, Lincoln Laboratory
Lexington, MA 02420

The U.S. Federal Aviation Administration (FAA) has sponsored the development and operational deployment of NEXRAD dual‐polarimetric‐based hazard detection algorithms for icing and hail. MIT Lincoln Laboratory (MIT LL) continues with developing next‐generation versions of the Icing Hazard Levels (IHL) and Hail Hazard Layers (HHL) algorithm products. The development over the years included university, and national and international laboratory partnerships. The operational deployment is in conjunction with the tri‐agency NEXRAD Radar Operations Center (ROC).

IHL and HHL are per‐radar volumetric products assessing the icing and hail hazard, respectively. Both feature altitude bounds of the hazard in a polar coordinate reference frame. HHL additionally includes severity and confidence information. Further development of IHL is benefitting from the analyses of MIT LL’s two Buffalo Area Icing and Radar Study in situ icing field campaigns (BAIRS I 2013; BAIRS II 2017) operated with the National Research Council of Canada and Environment and Climate Change Canada. The graupel‐classification‐based, operational IHL performance, evaluated against BAIRS II icing verification, shows excellent capability. The IHL capability is to be augmented further in conditions without graupel classification through interpretation of radar features such as the crystal sandwich associated with the icing hazard examined during BAIRS II. To support better winter weather NEXRAD monitoring, MIT LL, the ROC, and select National Weather Service weather forecast offices in the Midwest evaluated a modified Volume Coverage Pattern (VCP) scan strategy during the FAA’s ICICLE field campaign in winter 2019. Recommendations from that and development strategies for IHL and HHL will be discussed.

These dual polarimetric products should be embedded into next generation aviation weather systems and decision support tools for the National Airspace System (NAS) and integrated with multi‐platform approaches for hazard detection and alerting. The IHL product is applicable to icing impacts on general aviation, hold positions for commercial aviation, and also useful as a mosaic of radar‐based, rapidly-updating virtual icing pilot reports (PIREPs). The HHL is particularly useful to identify potential giant‐hail hazards at en route altitudes. It also can provide distinction for severity potential of incipient convection. Some applicable examples will be shared.
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* DISTRIBUTION STATEMENT A. Approved for public release. Distribution is unlimited.
This material is based upon work supported by the Federal Aviation Administration under Air Force Contract No. FA8702‐15‐D‐0001. Any opinions, findings, conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the Federal Aviation Administration.