Lightning channel locations, LNOx production, and advection in anomalous and normal polarity thunderstorms
| dc.contributor.author | Davis, Trenton, author | |
| dc.contributor.author | Rutledge, Steven A., advisor | |
| dc.contributor.author | Barth, Mary, committee member | |
| dc.contributor.author | Fischer, Emily, committee member | |
| dc.contributor.author | Reising, Steven, committee member | |
| dc.date.accessioned | 2018-06-12T16:13:49Z | |
| dc.date.available | 2018-06-12T16:13:49Z | |
| dc.date.issued | 2018 | |
| dc.description.abstract | Tropospheric ozone is a powerful greenhouse gas and OH precursor, thus understanding its sources is important. Its production is also widely studied in atmospheric science today as global climate modelers attempt to estimate future warming within the troposphere. Nitrogen oxides (NO + NO2 = NOx), serve as a precursor to ozone production. In areas where higher concentrations of OH are present, NOx will undergo reactions to produce nitric acid, thereby shortening its lifetime and limiting the production of ozone. Due to lower concentrations of OH in the upper troposphere, NOx tends to experience a longer lifetime (on the order of days) and greater ozone production at these heights. Lightning produces an appreciable amount of NOx (a.k.a. LNOx) but the final distribution of resulting LNOx, and thus its ozone production, remains poorly understood. Therefore, it is important that this source of NOx be further investigated to improve current LNOx parameterizations. Numerical modeling methods attempt to study this issue by parameterizing the nature of lightning within thunderstorms. Often, the vertical distribution of flash channels (and LNOx) is produced according to a parameterized flash rate within a defined vertical profile and reflectivity volume threshold. The structure and intensity of thunderstorms are highly variable though, causing the location of lightning within a thunderstorm to differ from one thunderstorm to the next. Furthermore, one remaining goal of the Deep Convective Clouds and Chemistry (DC3) field campaign (May – June 2012) was to compare the lightning flash locations and contributions to upper tropospheric LNOx between storms of normal and anomalous charge polarity. To address this remaining goal, five cases with over 5600 total flashes are analyzed in detail using data from DC3, three in northern Colorado and two in northern Alabama. Lightning sources are combined into 3-dimensional (3-D) flash channels and flash channel parcels, with each parcel containing the LNOx produced by its parent flash channel. Parcels are then advected forward in time during the lifetime of each storm using 3-D wind fields produced from dual-Doppler analyses. Results reveal a greater number of flashes and flash channels within anomalous polarity thunderstorms compared to normal polarity thunderstorms at a mean initiation height around 5 km. Flashes in these storms also appear to transect areas of higher vertical velocities resulting in roughly half of flash channel parcels being advected to the upper troposphere (z > 8 km). Contrary to some assumptions, an appreciable fraction of these parcels and NOx contributions remain in the boundary layer of these storms. In the two normal polarity thunderstorm cases, flash channels tend to initiate around 8 km with roughly half of the flash channel parcels remaining near or above 8 km. While both storm types appear to transport roughly 50% of their flash channel parcels to the upper troposphere, significantly larger flash counts and total flash length in the anomalous polarity storms lead to much higher mixing ratios of LNOx in the upper troposphere. These results may help chemistry modelers in parameterizing LNOx formation in both normal and anomalous thunderstorm polarity structures, which will also improve global climate model parameterizations of tropospheric ozone production. | |
| dc.format.medium | born digital | |
| dc.format.medium | masters theses | |
| dc.identifier | Davis_colostate_0053N_14662.pdf | |
| dc.identifier.uri | https://hdl.handle.net/10217/189289 | |
| dc.language | English | |
| dc.language.iso | eng | |
| dc.publisher | Colorado State University. Libraries | |
| dc.relation.ispartof | 2000-2019 | |
| dc.rights | Copyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright. | |
| dc.subject | anomalous | |
| dc.subject | LNOx | |
| dc.subject | thunderstorms | |
| dc.subject | lightning | |
| dc.subject | advection | |
| dc.subject | normal | |
| dc.title | Lightning channel locations, LNOx production, and advection in anomalous and normal polarity thunderstorms | |
| dc.type | Text | |
| dcterms.rights.dpla | This Item is protected by copyright and/or related rights (https://rightsstatements.org/vocab/InC/1.0/). You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). | |
| thesis.degree.discipline | Atmospheric Science | |
| thesis.degree.grantor | Colorado State University | |
| thesis.degree.level | Masters | |
| thesis.degree.name | Master of Science (M.S.) |
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