Dynamic coupling of volcanic CO₂ flow and wind at the Horseshoe Lake tree kill, Mammoth Mountain, California

Abstract

[1] We investigate spatio-temporal relationships between soil CO 2 flux (F CO2 ), meteorological variables, and topography over a ten-day period (09/12/2006 to 09/21/ 2006) at the Horseshoe Lake tree kill, Mammoth Mountain, CA. Total CO 2 discharge varied from 16 to 52 t d À1 , suggesting a decline in CO 2 emissions over decadal timescales. We observed systematic changes in F CO2 in space and time in association with a weather front with relatively high wind speeds from the west and low atmospheric pressures. The largest F CO2 changes were observed in relatively high elevation areas. The variations in F CO2 may be due to dynamic coupling of wind-driven airflow through the subsurface and flow of source CO 2 at depth. Our results highlight the influence of weather fronts on volcanic gas flow in the near-surface environment and how this influence can vary spatially within a study area.

Six-week time series of eddy covariance CO2 flux at Mammoth Mountain, California: Performance evaluation and role of meteorological forcing

“…Studies have reported large diurnal to seasonal fluctuations in time series of soil CO 2 concentrations, surface CO 2 fluxes, and total CO 2 discharges that appear to be due to variations in meteorological and hydrologic processes (e.g., McGee and Gerlach, 1998;McGee et al, 2000;Rogie et al, 2001). Also, Lewicki et al (2007) showed that large spatiotemporal variations in surface CO 2 fluxes over multiple days can be driven by slow-moving cold fronts. Furthermore, longterm monitoring suggests that emissions have markedly declined over the past decade.…”

“…Furthermore, longterm monitoring suggests that emissions have markedly declined over the past decade. For example, the average estimated CO 2 discharge from the tree kill area was~250 t d − 1 for 1995 to 1997 and 93 t d − 1 for 1997 to 2000 , whereas the average discharge measured in 2006 was 38 t d − 1 (Lewicki et al, 2007).…”

“…Extensive monitoring of subsurface CO 2 concentrations and surface CO 2 fluxes has been conducted at the HLTK (e.g., Farrar et al, 1995;Rahn et al, 1996;Gerlach et al, 1998;McGee and Gerlach, 1998;McGee et al, 2000;Gerlach et al, 2001;Anderson and Farrar, 2001;Rogie et al, 2001;Lewicki et al, 2007). Studies have reported large diurnal to seasonal fluctuations in time series of soil CO 2 concentrations, surface CO 2 fluxes, and total CO 2 discharges that appear to be due to variations in meteorological and hydrologic processes (e.g., McGee and Gerlach, 1998;McGee et al, 2000;Rogie et al, 2001).…”

“…Furthermore, it is important to understand the link between temporal variations in deeply derived CO 2 emissions, and meteorologic and hydrologic processes, as these near-surface processes can drive large changes in CO 2 emissions (e.g., Connor et al, 1993;McGee and Gerlach, 1998;Rogie et al, 2001;Granieri et al, 2003;Lewicki et al, 2007) that may pose health and environmental hazards or be misinterpreted to reflect changes at depth.…”

Assessing the application of a laser rangefinder for determining snow depth in inaccessible alpine terrain

“…Laser rangefinders have been used previously in diverse research applications such as structural bedrock mapping of the Sheep Mountain anticline (Allwardt et al, 2007), mapping of ground fissures involved in coal bed fires (Ide et al, 2010) and recording positions of rutting elk and their behaviour with regards to vehicle traffic (St. Clair and Forrest, 2009). A laser rangefinder has also been used to create small scale digital terrain models by interpolating point measurements (Lewicki et al, 2007). To our knowledge, use of a laser rangefinder for determining distributed snow depth is a unique application of this technique.…”