Abstract
Augustine Volcano (located in the Cook Inlet of South Central Alaska at 59.4oand 153.4oW) erupted in January 2006 and released, among other things, water vapor, radiation heat, and aerosols into the atmosphere. To determine the potential impact of volcanic emissions and ashfall on local weather, 16 simulations assuming artificial emission and ashfall scenarios were performed with the Weather Research and Forecasting model for 24 consecutive days starting the day before the first eruption. These simulations include (1) the control simulation without consideration of any volcanic perturbation, (2) four simulations with simplified scenarios for each individual volcanic factor [radiative heat from the caldera, water vapor, cloud condensation nuclei (CCN) and/or ice nuclei (IN) aerosols, and albedo change due to ashfall], and (3) 11 simulations containing all possible combinations of these factors. These 11 simulations serve to examine interactions among impacts of the different perturbations under the assumed scenarios. The impact of volcanic factors on local weather depends on the synoptic situation, emission strength, (combination of) volcanic factors, and interaction among impacts of factors if they occur concurrently. ANalysis Of VAriance shows that the greatest (statistically significant at the 95% or higher confidence level) volcanic impact occurs on relatively humid days and immediately downwind of the volcano (<50 km). Depending on relative humidity and temperature conditions, volcanic heat release can increase condensation and/or cloud top levels or reduce cloudiness. Due to non-linear cloud microphysical processes, meteorological responses to volcanic factors can diminish or enhance the impacts of the individual factors when factors occur concurrently. As an example, depending on the ambient conditions, concurrently occurring volcanic factors can lead to a decrease in precipitation at one time and an increase at another time. These findings indicate that in the immediate vicinity of erupting volcanoes, predicted cloud conditions and precipitation may be inaccurate due to the unknown volcanic forcing.
Highlights
Volcanic eruptions, regardless of intensity and duration, can affect the atmosphere, regional weather, and regional and global climate via various paths (Fig. 1) [1,2,3,4,5,6,7]
Theoretical exploration of the impacts of volcanic emissions and their interaction on clouds and precipitation requires a meso--scale numerical weather prediction (NWP) model modified for inclusion of volcanic effects
For polar regions WRF has a forecast skill equivalent to the well evaluated fifth-generation Pennsylvania State University-National Center for Atmospheric Research Mesoscale Model
Summary
Regardless of intensity and duration, can affect the atmosphere, regional weather, and regional and global climate via various paths (Fig. 1) [1,2,3,4,5,6,7]. A direct effect of volcanic aerosols on the atmosphere results from their scattering and absorbing of radiation in large parts of the spectrum. Hygroscopic ash particles injected into the troposphere increase the number and spectra of condensation nuclei (CCN) and/or ice nuclei (IN). The Open Atmospheric Science Journal, 2010, Volume 4 25. More R e ec ted S olar Flux bac ks c atter. Les s Upward IR Flux S olar H e a ti n g NE T
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