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Polarimetric and multi-doppler radar observations of electrified and unelectrified wildfire smoke plumes (Document No: 20140003202)
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Rison, William Krehbiel, Paul Dolan, Brenda Lindsey, Daniel T. Lang, Timothy J. Rutledge, Steven A. |
| Copyright Year | 2013 |
| Description | Pyrocumulus clouds above three Colorado wildfires (Hewlett Gulch, High Park, and Waldo Canyon; all occurred during summer 2012) electrified and produced small intracloud discharges whenever the smoke plumes grew to high altitudes (over 10 km above mean sea level, or MSL). This occurred during periods of rapid wildfire growth, as indicated by the shortwave infrared channel on a geostationary satellite, as well as by incident reports. In the Hewlett Gulch case, the fire growth led to increased updrafts within the plume, as inferred by multipleâ Doppler radar syntheses, which led to the vertical development and subsequent electrification â a life cycle as short as 30 minutes. The lightning, detected by a threedimensional lightning mapping network, was favored in highâaltitude regions (~10 km MSL) containing modest reflectivities (25 dBZ and lower), ~0 dB differential reflectivity, and reduced correlation coefficient (~0.6â0.7). This indicated the likely presence of ice particles (crystals and aggregates, possibly rimed) mixed with ash. Though neither multipleâDoppler nor polarimetric observations were available during the electrification of the High Park and Waldo Canyon plumes, their NEXRAD observations showed reflectivity structures consistent with Hewlett Gulch. In addition, polarimetric and multipleâDoppler scanning of unelectrified High Park plumes indicated only irregularly shaped ash, and not ice, was present (i.e., reflectivities < 25 dBZ, differential reflectivity > 5 dB, correlation < 0.4), and there was no broaching of the 10 km altitude. Based on these results, the electrification likely was caused by iceâbased processes that did not involve significant amounts of graupel. The results demonstrate the scientific value of multipleâDoppler and polarimetric radar observations of wildfire smoke plumes â including the ability to distinguish between regions of pure hydrometeors, regions of pure ash, and mixtures of both â and also suggest a possible new application for lightning data in monitoring wildfires. |
| File Size | 42870 |
| Page Count | 1 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_20140003202 |
| Archival Resource Key | ark:/13960/t1vf1tq6x |
| Language | English |
| Publisher Date | 2013-09-16 |
| Access Restriction | Open |
| Subject Keyword | Meteorology And Climatology Lightning Electrification Radar Tracking Hydrometeors Polarimetry Smoke Doppler Radar Intracloud Discharges Plumes Forest Fires Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
