Estimating the Net Radiative Impact of Stratospheric Pyrocumulonimbus Plumes
Abstract
Estimates of the global radiative impact of stratospheric plumes are continually being refined as improvements are made to measurements and the source become better understood. One such source that has long been overlooked are pyrocumulomibus storms. Plumes from these events range from short-lived, localized injections of smoke aerosols above the tropopause to the more extreme hemisphere-covering plumes that can last on seasonal timescales. In addition to the aerosol component, water vapor is present in many of these plumes in radiatively significant amounts. However, the boundary fluxes of this strong radiative forcing species have never been explored in the context of pyrocumulonimbus plumes. In this project a case study demonstrates that the downwelling flux at the surface is increased by up to 0.3 W/sq m, and an upwelling flux at the top-of-atmosphere is decreased by 0.01 W/sq m. The net effect of this forcing is a longwave heating of 0.05 K/day within the stratospheric plume. A significant discovery was made during this project that directly resulted from the heating present within these pyrocumulonimbus plumes. This discovery was unanticipated, but shows that the net heating within these plumes effect the dynamics of the statosphere. A dynamical anomaly characterized by a rotating spheroid of smoke aerosols and biomass burning gases is generated as the plume absorbs radiation and generates buoyancy through diabatic heating. This phenomenon has been termed Smoke With Induced Rotation and Lofting (SWIRL), and is shown in this report to be associated with much longer plume lifetimes and synoptic-scale weather anomalies that were unknown prior to this study. The effect of this discovery has led to a new vein of research within stratospheric dynamic models, and has successfully formed the basis of a 6.1 New Start proposal.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 04, 2022
- Accession Number
- AD1184380
Entities
People
- George P. Iii Kablick
Organizations
- United States Naval Research Laboratory