Rene Servranckx

Observations of boreal forest fire smoke in the stratosphere by POAM III, SAGE II, and lidar in 1998

A substantial increase in stratospheric aerosol was recorded between May and October 1998 between 55° and 70°N. This phenomenon was recorded in the absence of reported volcanic eruptions with stratospheric impact potential. The POAM III and SAGE II instruments made numerous measurements of layers of enhanced aerosol extinction substantially higher than typical values 3 to 5 km above the tropopause. A comparison of these observations with lidar profiles, TOMS aerosol index data, and forest fire statistics reveals a strong link between stratospheric aerosol and forest fire smoke. Our analysis strongly suggests that smoke from boreal forest fires was lofted across the tropopause in substantial amounts in several episodes occurring in Canada and eastern Russia. Observations reveal a broad zonal increase in stratospheric aerosol that persisted for at least three months.

Pyro‐cumulonimbus injection of smoke to the stratosphere: Observations and impact of a super blowup in northwestern Canada on 3–4 August 1998

[1] We report observations and analysis of a pyro-cumulonimbus event in the midst of a boreal forest fire blowup in Northwest Territories Canada, near Norman Wells, on 3–4 August 1998. We find that this blowup caused a five-fold increase in lower stratospheric aerosol burden, as well as multiple reports of anomalous enhancements of tropospheric gases and aerosols across Europe 1 week later. Our observations come from solar occultation satellites (POAM III and SAGE II), nadir imagers (GOES, AVHRR, SeaWiFS, DMSP), TOMS, lidar, and backscattersonde. First, we provide a detailed analysis of the 3 August eruption of extreme pyro-convection. This includes identifying the specific pyro-cumulonimbus cells that caused the lower stratospheric aerosol injection, and a meteorological analysis. Next, we characterize the altitude, composition, and opacity of the post-convection smoke plume on 4–7 August. Finally, the stratospheric impact of this injection is analyzed. Satellite images reveal two noteworthy pyro-cumulonimbus phenomena: (1) an active-convection cloud top containing enough smoke to visibly alter the reflectivity of the cloud anvil in the Upper Troposphere Lower Stratosphere (UTLS) and (2) a smoke plume, that endured for at least 2 hours, atop an anvil. The smoke pall deposited by the Norman Wells pyro-convection was a very large, optically dense, UTLS-level plume on 4 August that exhibited a mesoscale cyclonic circulation. An analysis of plume color/texture from SeaWiFS data, aerosol index, and brightness temperature establishes the extreme altitude and ‘‘pure’’ smoke composition of this unique plume. We show what we believe to be a first-ever measurement of strongly enhanced ozone in the lower stratosphere mingled with smoke layers. We conclude that two to four extreme pyro-thunderstorms near Norman Wells created a smoke injection of hemispheric scope that substantially increased stratospheric optical depth, transported aerosols 7 km above the tropopause (above 430 K potential temperature), and also perturbed lower stratospheric ozone.

The Untold Story of Pyrocumulonimbus

Wildfire is becoming the focus of increasing attention. It is now realized that changes in the occurrence frequency and intensity of wildfires has important significant consequences for a variety of important problems, including atmospheric change and safety in the urban–wildland interface. One important but poorly understood aspect of wildfire behavior—pyrocumulonimbus firestorm dynamics and atmospheric impact—has a curious history of theory and observation. The “pyroCb” is a fire-started or fire-augmented thunderstorm that in its most extreme manifestation injects huge abundances of smoke and other biomass-burning emissions into the lower stratosphere. The observed hemispheric spread of smoke and other biomass-burning emissions could have important climate consequences. PyroCbs have been spawned naturally and through anthropogenesis, and they are hypothesized as being part of the theoretical “Nuclear nuclear winter” work. However, direct attribution of the stratospheric aerosols to the pyroCb only occur...

Capturing the Acoustic Fingerprint of Stratospheric Ash Injection

More than 100 separate incidents of interactions between aircraft and volcanic ash were documented between 1973 and 2003. Incidents on international flight paths over remote areas have resulted in engine failures and significant damage and expense to commercial airlines. To protect aircraft from volcanic ash, pilots need rapid and reliable notification of ash- generating events. A global infrasound array network, consisting of the International Monitoring System (IMS) and other national networks, has demonstrated a capability for remote detection of Vulcanian to Plinian eruptions that can inject ash into commercial aircraft cruise altitudes (approximately 12 kilometers) near the tropopause. The identification of recurring sound signatures associated with high- altitude ash injection implies that acoustic remote sensing can improve the reliability and reduce the latency of these notifications.

Correction to “Pyro‐cumulonimbus injection of smoke to the stratosphere: Observations and impact of a super blowup in northwestern Canada on 3–4 August 1998”

[1] In the paper ‘‘Pyro-cumulonimbus injection of smoke to the stratosphere: Observations and impact of a super blowup in northwestern Canada on 3–4 August 1998’’ by M. Fromm, R. Bevilacqua, R. Servranckx, J. Rosen, J. P. Thayer, J. Herman, and D. Larko (Journal of Geophysical Research, 110, D08205, doi:10.1029/2004JD005350), the following was left out of the Acknowledgments section. [2] We thank all the referees for their thorough and constructive criticism of the manuscript. The POAM III instrument was sponsored by the Office of Naval Research. The French Centre National d’Etudes Spatiales operates the SPOT 4 spacecraft and has generously waived the uplink fees. Launch and initial operation of POAM were sponsored by the Air Force Space Test Program; continuing operations are performed by the Air Force Space and Missile Command. Support for scientific analysis of the data comes from the Naval Research Laboratory and NASA. JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 110, D12202, doi:10.1029/2005JD006171, 2005