Search Results

You are looking at 1 - 5 of 5 items for

  • Author or Editor: Kelley Murphy x
  • Refine by Access: All Content x
Clear All Modify Search
Kelley M. Murphy
,
Eric C. Bruning
,
Christopher J. Schultz
, and
Jennifer K. Vanos

Abstract

A lightning risk assessment for application to human safety was created and applied in 10 west Texas locations from 2 May 2016 to 30 September 2016. The method combined spatial lightning mapping data, probabilistic risk calculation adapted from the International Electrotechnical Commission Standard 62305-2, and weighted average interpolation to produce risk magnitudes that were compared with tolerability thresholds to issue lightning warnings. These warnings were compared with warnings created for the same dataset using a more standard lightning safety approach that was based on National Lightning Detection Network (NLDN) total lightning within 5 n mi (1 n mi = 1.852 km) of each location. Four variations of the calculation as well as different units of risk were tested to find the optimal configuration to calculate risk to an isolated human outdoors. The best-performing risk configuration using risk (10 min)−1 or larger produced the most comparable results to the standard method, such as number of failures, average warning duration, and total time under warnings. This risk configuration produced fewer failures than the standard method but longer total time under warnings and higher false alarm ratios. Median lead times associated with the risk configuration were longer than the standard method for all units considered, whereas median down times were shorter for risk (10 min)−1 and risk (15 min)−1. Overall, the risk method provides a baseline framework to quantify the changing lightning hazard on the storm scale and could be a useful tool to aid in lightning decision support scenarios.

Free access
Aaron R. Naeger
,
Michael J. Newchurch
,
Tom Moore
,
Kelly Chance
,
Xiong Liu
,
Susan Alexander
,
Kelley Murphy
, and
Bo Wang
Full access
Aaron R. Naeger
,
Michael J. Newchurch
,
Tom Moore
,
Kelly Chance
,
Xiong Liu
,
Susan Alexander
,
Kelley Murphy
, and
Bo Wang
Full access
Christopher J. Schultz
,
Roger E. Allen
,
Kelley M. Murphy
,
Benjamin S. Herzog
,
Stephanie A. Weiss
, and
Jacquelyn S. Ringhausen

Abstract

Infrequent lightning flashes occurring outside of surface precipitation pose challenges to Impact-Based Decision Support Services (IDSS) for outdoor activities. This paper examines the remote sensing observations from an event on 20 August 2019 where multiple cloud-to-ground flashes occurred over 10 km outside surface precipitation (lowest radar tilt reflectivity < 10 dBZ and no evidence of surface precipitation) in a trailing stratiform region of a mesoscale convective system. The goal is to demonstrate the fusion of radar with multiple lightning observations and a lightning risk model to demonstrate how reflectivity and differential reflectivity combined provided the best indicator for the potential of lightning where all of the other lightning safety methods failed. A total of 13 lightning flashes were observed by the Geostationary Lightning Mapper (GLM) within the trailing stratiform region between 2100 and 2300 UTC. The average size of the 13 lightning flashes was 3184 km2, with an average total optical energy of 7734 fJ. A total of 75 NLDN flash locations were coincident with the 13 GLM flashes, resulting in an average of 5.8 NLDN flashes [in-cloud (IC) and cloud-to-ground (CG)] per GLM flash. In total, five of the GLM flashes contained at least one positive cloud-to-ground flash (+CG) flash identified by the NLDN, with peak amplitudes ranging between 66 and 136 kA. All eight CG flashes identified by the NLDN were located more than 10 km outside surface precipitation. The only indication of the potential of these infrequently large flashes was the presence of depolarization streaks in differential reflectivity (Z DR) and enhanced reflectivity near the melting layer.

Full access
A. Gannet Hallar
,
Steven S. Brown
,
Erik Crosman
,
Kelley C. Barsanti
,
Christopher D. Cappa
,
Ian Faloona
,
Jerome Fast
,
Heather A. Holmes
,
John Horel
,
John Lin
,
Ann Middlebrook
,
Logan Mitchell
,
Jennifer Murphy
,
Caroline C. Womack
,
Viney Aneja
,
Munkhbayar Baasandorj
,
Roya Bahreini
,
Robert Banta
,
Casey Bray
,
Alan Brewer
,
Dana Caulton
,
Joost de Gouw
,
Stephan F.J. De Wekker
,
Delphine K. Farmer
,
Cassandra J. Gaston
,
Sebastian Hoch
,
Francesca Hopkins
,
Nakul N. Karle
,
James T. Kelly
,
Kerry Kelly
,
Neil Lareau
,
Keding Lu
,
Roy L. Mauldin III
,
Derek V. Mallia
,
Randal Martin
,
Daniel L. Mendoza
,
Holly J. Oldroyd
,
Yelena Pichugina
,
Kerri A. Pratt
,
Pablo E. Saide
,
Philip J. Silva
,
William Simpson
,
Britton B. Stephens
,
Jochen Stutz
, and
Amy Sullivan

Abstract

Wintertime episodes of high aerosol concentrations occur frequently in urban and agricultural basins and valleys worldwide. These episodes often arise following development of persistent cold-air pools (PCAPs) that limit mixing and modify chemistry. While field campaigns targeting either basin meteorology or wintertime pollution chemistry have been conducted, coupling between interconnected chemical and meteorological processes remains an insufficiently studied research area. Gaps in understanding the coupled chemical–meteorological interactions that drive high-pollution events make identification of the most effective air-basin specific emission control strategies challenging. To address this, a September 2019 workshop occurred with the goal of planning a future research campaign to investigate air quality in western U.S. basins. Approximately 120 people participated, representing 50 institutions and five countries. Workshop participants outlined the rationale and design for a comprehensive wintertime study that would couple atmospheric chemistry and boundary layer and complex-terrain meteorology within western U.S. basins. Participants concluded the study should focus on two regions with contrasting aerosol chemistry: three populated valleys within Utah (Salt Lake, Utah, and Cache Valleys) and the San Joaquin Valley in California. This paper describes the scientific rationale for a campaign that will acquire chemical and meteorological datasets using airborne platforms with extensive range, coupled to surface-based measurements focusing on sampling within the near-surface boundary layer, and transport and mixing processes within this layer, with high vertical resolution at a number of representative sites. No prior wintertime basin-focused campaign has provided the breadth of observations necessary to characterize the meteorological–chemical linkages outlined here, nor to validate complex processes within coupled atmosphere–chemistry models.

Full access