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7 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Assessing the Impact of Lightning NOx Emissions in CMAQ Using Lightning Flash Data from WWLLN over the Contiguous United States

Comparison of lightning flash data from the National Lightning Detection Network (NLDN) and from the World Wide Lightning Location Network (WWLLN) over the contiguous United States (CONUS) for the 2016–2018 period reveals temporally and spatially varying flash rates that would influence lightning NO x (LNO x ) production due to known detection efficiency differences especially during summer months over land (versus over ocean). However, the lightning flash density differences between the two networks show persistent seasonal patterns over geographical regions (e.g., land versus ocean). Since the NLDN data are considered to have higher accuracy (lightning detection with >95% efficiency), we developed scaling factors for the WWLLN flash data based on the ratios of WWLLN to NLDN flash data over time (months of year) and space. In this study, sensitivity simulations using the Community Multiscale Air Quality (CMAQ) model are performed utilizing the original data sets (both NLDN and WWLLN) and the scaled WWLLN flash data for LNO x production over the CONUS. The model performance of using the different lightning flash datasets for ambient O 3 and NO x mixing ratios that are directly impacted by LNO x emissions and the wet and dry deposition of oxidized nitrogen species that are indirectly impacted by LNO x emissions is assessed based on comparisons with ground-based observations, vertical profile measurements, and satellite products. During summer months, the original WWLLN data produced less LNO x emissions (due to its lower lightning detection efficiency) compared to the NLDN data, which resulted in less improvement in model performance than the simulation using NLDN data as compared to the simulation without any LNO x emissions. However, the scaled WWLLN data produced LNO x estimates and model performance comparable with the NLDN data, suggesting that scaled WWLLN may be used as a substitute for the NLDN data to provide LNO x estimates in air quality models when the NLDN data are not available (e.g., due to prohibitive cost or lack of spatial coverage).

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

WWLLN Energetic Lightning Events Are Different From Optical Superbolts

The most powerful optical emissions from lightning have been described as “superbolts” since the 1970s. Holzworth et al. (2019, https://doi.org/10.1029/2019jd030975) recently applied the superbolt label to the most energetic Radio Frequency emissions recorded by the World Wide Lightning Location Network (WWLLN). We compare the WWLLN energies to optical measurements by the photodiode detector on the Fast On-orbit Recording of Transient Events satellite and the Geostationary Lightning Mappers on NOAA's Geostationary Operational Environmental Satellites to assess whether these energetic WWLLN events coincide with optical superbolts. We find no overlap between optical and WWLLN superbolts. Moreover, extreme WWLLN events occur in a contrasting meteorological context to optical superbolts. Despite similarities in their overall global patterns of occurrence, WWLLN superbolts correspond to a different phenomenon.

58 GEOSCIENCES↗
DOE OSTI2024

Lightning Climatology Derived from World Wide Lightning Location Network (WWLLN) for US East Coast and European North Sea

This dataset contains gridded (1x1 km) data of lightning stroke observations during 2020, 2021, and 2022 over the US East Coast and European North Sea. Data processing involved intersecting each of the ~26 million lightning strokes over the US East Coast and ~365 thousand strokes over the North Sea within a corresponding 1x1 km grid, resulting in each grid reporting a 'strokes per square kilometer' and 'energy per square kilometer'. For the US, these results are presented as annual averages for 2020, 2021, and 2022, while for the North Sea results are presented as a 3-year annual average.

17 WIND ENERGY↗
DOE OSTI2024

Lightning Climatology Derived from World Wide Lightning Location Network (WWLLN) for US East Coast and European North Sea

This dataset contains gridded (1x1 km) data of lightning stroke observations during 2020, 2021, and 2022 over the US East Coast and European North Sea. Data processing involved intersecting each of the ~26 million lightning strokes over the US East Coast and ~365 thousand strokes over the North Sea within a corresponding 1x1 km grid, resulting in each grid reporting a 'strokes per square kilometer' and 'energy per square kilometer'. For the US, these results are presented as annual averages for 2020, 2021, and 2022, while for the North Sea results are presented as a 3-year annual average.

17 WIND ENERGY↗
DOE OSTI2023

Responses of the AC/DC Global Electric Circuit to Volcanic Electrical Activity in the Hunga Tonga-Hunga Ha'apai Eruption on 15 January 2022

Responses of the AC and DC global electric circuits (GECs) to the large eruption of the Hunga Tonga-Hunga Ha'apai (HT-HH) volcano on 15 January 2022 are discussed. The AC-related investigation is based on Schumann resonance (SR) measurements from six stations on four continents. The DC-related investigation utilizes atmospheric electric field (potential gradient, PG) measurements from six recording stations in Europe and the USA. According to data from the GLD360 and WWLLN lightning detection networks, the peak lightning stroke rate, 83/s, was dominated by negative polarity lightning, but the distributions of positive and negative lightning discharges in latitude and longitude around the volcano differed. A global intensification of SR is apparent in connection with the enhanced lightning activity caused by the eruption. SR data-based results confirm that the lightning activity in the eruption dominated the naturally occurring global activity for a period of about 1 hr. The highly localized increase in lightning activity over HT-HH was a unique point source of SR excitation. PG measurements suggest that impulse-like charging of the DC GEC, by ~15%, via negative cloud-to-ground lightning strokes took place twice during the eruption. A time constant of 7 or 8 min has been inferred for near-surface PG changes due to these enhancements. This could be the first direct measurement of the time constant of the GEC near the Earth's surface, as well as the first observation of the direct charging of the DC GEC by a unique atmospheric electrified source.

58 GEOSCIENCES↗
DOE OSTI2021

CAPE Threshold for Lightning Over the Tropical Ocean

Here, we investigate the relationship between convective available potential energy (CAPE), precipitation, the number and size of storms and overshooting tops, and lightning stroke density ($\mathcal{f}$) over the Central America region. While $\mathcal{f}$ increases almost linearly with CAPE 1/2 over land, $\mathcal{f}$ is nearly muted over the ocean when CAPE is small. In the high-CAPE regime, on the contrary, oceanic storms produce as many lightning flashes as land storms. We show that individual oceanic storms are smaller and contain fewer overshooting tops compared to land storms, although the difference exists across low- and high-CAPE regimes. While $\mathcal{f}$ increases as individual storm size increases, the storm size required to produce lightning appears to be disproportionately high in the low-CAPE regime, likely due to the stronger entrainment effect. The entrainment effect on $\mathcal{f}$ in the low-CAPE regime appears to be much weaker over land. Applying the CAPE threshold for lightning over the ocean to the CAPE-based lightning parameterization scheme of Romps et al. (2014), https://doi.org/10.1126/science.1259100 improves its performance, in particular, at representing the land-sea contrast in $\mathcal{f}$.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Interactions Between Lightning and Ship Traffic

It is important to understand connections between society and the natural environment for anticipating hazards and anthropogenic effects on the Earth system. In this study, we conduct a detailed exploration of interactions between oceanic thunderstorms and maritime traffic. Shipping traffic produces aerosols that perturb the otherwise “clean” ocean environment. Prior work proposed these aerosol effects as the cause of increased lightning over certain shipping lanes. However, introducing tall grounded objects into a high electric field environment might also facilitate lightning discharges, as we see with upward lightning over land. We consider both possibilities. Our analyses of the thunderstorms responsible for enhanced lightning activity over the shipping lane with the clearest anthropogenic signal indicate that the enhancement results from an increased frequency of lightning-producing storms. Observed variations in thunderstorm microphysics between the shipping lane and nearby oceans are small compared to natural factors such as the Indian monsoon, and are on the same scale as the local variability in the data. By contrast, matching lightning stroke data with ship transponder events in oceanic regions where public data are available reveals a strong signal from direct ship interactions. Lightning is 15× (66×) more likely to occur at a ship location compared to 2 km (25 km) away. These results highlight the central role of direct ship interactions in explaining lightning enhancements over shipping lanes. We also document the frequency of these direct lightning interactions across various categories of vessels and on individual ships present in the public data.

54 ENVIRONMENTAL SCIENCES↗