RESEARCH INTERESTS • Deep convection and its short- and long-term impacts • Mesoscale research modeling (i.e., tropical cyclone simulations) • Atmospheric chemistry and its impact on climate change • Lightning, lightning initiation and cessation, and propagation paths • Relationship between lightning, polarimetric radar products, and storm parameters
OTHER WEB SITES http://www.linkedin.com/in/adprest
The transport of gases and aerosols to the upper troposphere/lower stratosphere (UTLS) has a subs... more The transport of gases and aerosols to the upper troposphere/lower stratosphere (UTLS) has a substantial impact on Earth's climate. Thus, we need to improve our understanding of the vertical convective transport and long-range horizontal transport of chemical species that impact the atmosphere's radiative forcing. This includes the large scale convection associated with tropical cyclones (TCs). Little is known about the atmospheric chemistry of TCs, and few studies have addressed the chemical transport associated with them. The only comprehensive chemical investigation of a TC was a DC-8 flight during NASA's PEM-West A mission through Typhoon Mireille. The SEAC 4 RS dataset from TC Ingrid will help fill the gap of information regarding TC chemistry and build upon prior research using high-resolution chemical transport modeling.
Polarimetric radar data are used to develop lightning cessation guidance for the Cape Canaveral a... more Polarimetric radar data are used to develop lightning cessation guidance for the Cape Canaveral area of central Florida. For this purpose, 80 nonsevere thunderstorm cells in 2012, mostly during the warm season, are analyzed. In-cloud and cloud-to-ground lightning data for the storms are obtained by combining information from the second-generation Lightning Detection and Ranging network and the National Lightning Detection Network. Storms are tracked using the Warning Decision Support System– Integrated Information software, producing time series of radar-and lightning-derived parameters. The 80 storms are split into two categories: 1) 50 isolated storms whose lightning initiation sources are confined to the core or anvil region of the storm and 2) 30 nonisolated cells whose lightning channels are initiated in a nearby active storm and extended to the dissipating study cell. Trends in polarimetric radar parameters at different temperature levels are studied for 40 of the 50 isolated storms to develop cessation guidance. Results based on a completely independent sample of 10 storms reveal that the best-performing cessation algorithm utilizes the presence of graupel and horizontal reflectivity > 35 dBZ at the -10 C temperature altitude. Lightning is not expected 10 min after both thresholds are no longer met. However, this relationship does not apply to nonisolated cells because a neighboring storm could still be electrically active. Results show that a stratiform cloud region connecting the decaying storm to an active storm might facilitate further channel propagation that might not have occurred otherwise. Thus, the proposed cessation guidelines are not recommended for nonisolated cells.
The horizontal distance that intracloud (IC) and cloud to ground (CG) lightning flashes extend fr... more The horizontal distance that intracloud (IC) and cloud to ground (CG) lightning flashes extend from thunderstorms is presented for warm season nonsevere storms near Cape Canaveral, FL. The Warning Decision Support System–Integrated Information (WDSS-II) software allowed us to ingest, display, and make distance calculations using radar reflectivity data from nearby National Weather Service Offices and lightning information from the National Lightning Detection Network and the local Lightning Detection and Ranging network. The flash distances were determined manually using a measuring tool within WDSS-II. Six categories of flashes were investigated: (a) CG flashes measured from the edge of the convective core (30 dBZ) to the ground strike location that is beneath the attached anvil, (b) CG " bolt from the blue " flashes measured from cloud edge (0 dBZ) to the ground strike point that contains only 0 dBZ overhead, (c) CG bolt from the blue flashes as in Category B but measured from the edge of the precipitation (18 dBZ), (d) IC flashes that exit a portion of the cloud that is not an anvil, measured from cloud edge (0 dBZ), (e) IC flashes within anvils measured from the edge of convective precipitation (30 dBZ) to the termination point within the anvil, and (f) IC flashes exiting the edge (0 dBZ) of anvils. Results for each category are presented in the forms of frequency distributions of distances and their cumulative frequency distributions.
The transport of gases and aerosols to the upper troposphere/lower stratosphere (UTLS) impacts th... more The transport of gases and aerosols to the upper troposphere/lower stratosphere (UTLS) impacts the Earth's climate. This study aims to improve our understanding of the vertical transport of surface-based species by examining the widespread convection associated with tropical cyclones (TCs). We focus on TCs in the western North Pacific (WNP) because it is the world's most active basin. It produces larger and stronger storms than any other basin, and TCs in the WNP often make landfall in East Asia, one of the world's most polluted regions.
The transport of gases and aerosols to the upper troposphere/lower stratosphere (UTLS) has a subs... more The transport of gases and aerosols to the upper troposphere/lower stratosphere (UTLS) has a substantial impact on Earth's climate. Thus, we need to improve our understanding of the vertical convective transport and long-range horizontal transport of chemical species that impact the atmosphere's radiative forcing. This includes the large scale convection associated with tropical cyclones (TCs). Little is known about the atmospheric chemistry of TCs, and few studies have addressed the chemical transport associated with them. The only comprehensive chemical investigation of a TC was a DC-8 flight during NASA's PEM-West A mission through Typhoon Mireille. The SEAC 4 RS dataset from TC Ingrid will help fill the gap of information regarding TC chemistry and build upon prior research using high-resolution chemical transport modeling.
Polarimetric radar data are used to develop lightning cessation guidance for the Cape Canaveral a... more Polarimetric radar data are used to develop lightning cessation guidance for the Cape Canaveral area of central Florida. For this purpose, 80 nonsevere thunderstorm cells in 2012, mostly during the warm season, are analyzed. In-cloud and cloud-to-ground lightning data for the storms are obtained by combining information from the second-generation Lightning Detection and Ranging network and the National Lightning Detection Network. Storms are tracked using the Warning Decision Support System– Integrated Information software, producing time series of radar-and lightning-derived parameters. The 80 storms are split into two categories: 1) 50 isolated storms whose lightning initiation sources are confined to the core or anvil region of the storm and 2) 30 nonisolated cells whose lightning channels are initiated in a nearby active storm and extended to the dissipating study cell. Trends in polarimetric radar parameters at different temperature levels are studied for 40 of the 50 isolated storms to develop cessation guidance. Results based on a completely independent sample of 10 storms reveal that the best-performing cessation algorithm utilizes the presence of graupel and horizontal reflectivity > 35 dBZ at the -10 C temperature altitude. Lightning is not expected 10 min after both thresholds are no longer met. However, this relationship does not apply to nonisolated cells because a neighboring storm could still be electrically active. Results show that a stratiform cloud region connecting the decaying storm to an active storm might facilitate further channel propagation that might not have occurred otherwise. Thus, the proposed cessation guidelines are not recommended for nonisolated cells.
The horizontal distance that intracloud (IC) and cloud to ground (CG) lightning flashes extend fr... more The horizontal distance that intracloud (IC) and cloud to ground (CG) lightning flashes extend from thunderstorms is presented for warm season nonsevere storms near Cape Canaveral, FL. The Warning Decision Support System–Integrated Information (WDSS-II) software allowed us to ingest, display, and make distance calculations using radar reflectivity data from nearby National Weather Service Offices and lightning information from the National Lightning Detection Network and the local Lightning Detection and Ranging network. The flash distances were determined manually using a measuring tool within WDSS-II. Six categories of flashes were investigated: (a) CG flashes measured from the edge of the convective core (30 dBZ) to the ground strike location that is beneath the attached anvil, (b) CG " bolt from the blue " flashes measured from cloud edge (0 dBZ) to the ground strike point that contains only 0 dBZ overhead, (c) CG bolt from the blue flashes as in Category B but measured from the edge of the precipitation (18 dBZ), (d) IC flashes that exit a portion of the cloud that is not an anvil, measured from cloud edge (0 dBZ), (e) IC flashes within anvils measured from the edge of convective precipitation (30 dBZ) to the termination point within the anvil, and (f) IC flashes exiting the edge (0 dBZ) of anvils. Results for each category are presented in the forms of frequency distributions of distances and their cumulative frequency distributions.
The transport of gases and aerosols to the upper troposphere/lower stratosphere (UTLS) impacts th... more The transport of gases and aerosols to the upper troposphere/lower stratosphere (UTLS) impacts the Earth's climate. This study aims to improve our understanding of the vertical transport of surface-based species by examining the widespread convection associated with tropical cyclones (TCs). We focus on TCs in the western North Pacific (WNP) because it is the world's most active basin. It produces larger and stronger storms than any other basin, and TCs in the WNP often make landfall in East Asia, one of the world's most polluted regions.
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Presentations and Publications by Ari Preston