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Christopher Joseph Schultz

Publications and source records attributed to Christopher Joseph Schultz.

5 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2016

Automated Storm Tracking and the Lightning Jump Algorithm Using GOES-R Geostationary Lightning Mapper (GLM) Proxy Data

This study develops a fully automated lightning jump system encompassing objective storm tracking, Geostationary Lightning Mapper proxy data, and the lightning jump algorithm (LJA), which are important elements in the transition of the LJA concept from a research to an operational based algorithm. Storm cluster tracking is based on a product created from the combination of a radar parameter (vertically integrated liquid, VIL), and lightning information (flash rate density). Evaluations showed that the spatial scale of tracked features or storm clusters had a large impact on the lightning jump system performance, where increasing spatial scale size resulted in decreased dynamic range of the system's performance. This framework will also serve as a means to refine the LJA itself to enhance its operational applicability. Parameters within the system are isolated and the system's performance is evaluated with adjustments to parameter sensitivity. The system's performance is evaluated using the probability of detection (POD) and false alarm ratio (FAR) statistics. Of the algorithm parameters tested, sigma-level (metric of lightning jump strength) and flash rate threshold influenced the system's performance the most. Finally, verification methodologies are investigated. It is discovered that minor changes in verification methodology can dramatically impact the evaluation of the lightning jump system.

lightning jump↗
NASA NTRSDate not supplied

A SATELLITE AGNOSTIC APPROACH TO QUANTIFYING HAIL DAMAGE SWATHS ACROSS THE CENTRAL UNITED STATES AND OTHER AGRICULTURAL REGIONS

Intense thunderstorms can bring damaging winds and large hail to agricultural regions during the prime growing season. In certain cases, large swaths of damage from the wind and hail are left behind and visible to satellite remote sensing instruments. Often times, Earth observing optical remote sensing from low to high spatial resolutions are able to view these damaged swaths. With the large number of moderate to high-resolution instruments in orbit, these damaged areas have potential to be viewed daily. However, during the prime growing season, clouds frequently block the viewing of the land surface by these optical instruments. Space-borne synthetic aperture radar (SAR) instruments allow for the viewing of the land surface in most weather conditions, but instead measure backscatter as opposed to optical sensors measuring reflected or emitted radiation. Additionally, the number of SAR instruments with free and open data lags behind the number of optical sensors. This paper describes the development of a methodology that attempts to characterize hail damaged swaths, through independent use of multiple optical and SAR platforms. This satellite-agnostic approach will focus statistical analysis by comparing undamaged areas to suspected damaged areas by using commonly derived indices from optical instruments and SAR backscatter from multiple polarizations.

Jordan R Bell↗
NASA NTRSDate not supplied

Changes in Lightning Characteristics as Hurricane Dorian (2019) Reached Peak Intensity

Previous work using land-based lightning detection networks and lightning imagers in low Earth orbit has established that lighting is a useful predictor of TC intensification. Increases in the number of lightning flashes in both the inner core and outer rainbands of hurricanes are linked to hurricane intensification. Sometimes, however, lightning outbreaks can occur in storms that weaken during or after the outbreak. Environmental conditions such as vertical wind shear and land interaction or inner-core structural changes such as secondary eyewall formation can account for some of this discrepancy. Hurricane Dorian (2019), however, exhibited a distinct inner-core lightning outbreak in a low-shear environment with minimal land interaction. The lightning flashes during this outbreak were located on the inner edge of the eyewall, which is not the expected location of enhanced convection during secondary eyewall formation. Regardless, Dorian weakened during and after this lightning outbreak. This presentation will analyze Dorian’s lightning evolution using data from the Geostationary Lightning Mapper (GLM) aboard the GOES-16 satellite. GLM provides continuous observations of not only the number and polarity of lightning flashes, but also the size and optical energy of the flashes. Here we show marked differences in the distributions of average flash area and total optical energy between the two most pronounced lightning outbreaks in Dorian’s lifetime: one while the storm was rapidly intensifying and another while the storm began to weaken. During intensification, lightning flashes were fewer but larger and more energetic, whereas during weakening, lightning flashes were much more numerous, but were smaller and less energetic. We present evidence that barotropic mixing between the eye and eyewall could have contributed to both the increase in inner-core lightning and the weakening of Dorian’s storm-scale maximum wind speed. These results suggest that average flash area and total optical energy could help to distinguish between lightning outbreaks that correspond to intensification and outbreaks that correspond to weakening.

Hurricanes↗