Use of volcanic aerosols to study the tropical stratospheric reservoir

Abstract

Aerosol data obtained by the advanced very high resolution radiometer on NOAA 11, the improved stratospheric and mesospheric sounder on the upper atmospheric research satellite, one airborne lidar system, and several ground‐based lidar systems up to 2‐1/2 years after the eruption of Mount Pinatubo are used to study stratospheric dynamics. In particular, this study focuses on the tropical stratospheric reservoir and transport from it to northern midlatitudes following the eruption of Mount Pinatubo. This includes: The build‐up and removal rates for sulfate aerosol, the position and motion of the center of the reservoir, and the position and width of its boundaries at altitudes of the volcanic aerosols. Ozone data from the total ozone mapping spectrometer were also used to study the position and width of the reservoir boundaries. In addition, ground‐based lidar stratospheric aerosol data are used to study aerosol transport from the reservoir to the northern hemisphere as it relates to winds in the tropical stratosphere. Finally, historical in situ and satellite data were used to examine how the time and location of volcanic injections into the stratosphere affect the aerosol decay rates and seasonal variations of aerosol optical depth in the midlatitude stratosphere.

Volcanic eruptions recorded in the Illimani ice core (Bolivia): 1918–1998 and Tambora periods

“…5 and from yearly mean concentrations presented in Table 2. that sulfate input at the Illimani site was perturbed for two years, until mid 1993, while noticeable effects lasted only one year for halogens. The duration of sulfate perturbation is consistent with stratospheric aerosol measurements in the tropics (20 • S to 30 • N, Grant et al, 1996 Devine et al (1984) and Sigurdsson et al (1985), the total mass erupted during the 1963 Mount Agung eruption (2.4×10 3 Tg) was 2 orders of magnitude lower than that during the Tambora eruption. The same figure is valid for the estimated masses of HCl and HF (1.5 and 0.8 Tg, respectively, for Agung eruption).…”

“…For Agung (March 1963), this occurred by the end of 1964. This is consistent with a stratospheric residence time (1/e) of approximately 1 year for sulfate aerosols at these latitudes (Grant et al, 1996).…”

Isentropic, diabatic, and sedimentary transport of Mount Pinatubo aerosol

“…ISAMS measurements, Lambert et al [1993] showed that by December 1991, most of the Mount Pinambo aerosol cloud still remained in the tropics, confirming the suggestion of Hitchman et al [1994] and Grant et al [1996] that the tropical stratosphere cotfid be regarded as a partially isolated reservoir of trace constituents. Trepte and Hitchman [1992] and Choiet al [1998] showed that the isolation of the tropical reservoir in the lower stratosphere is dependent 405! upon the phase of the quasi-biennial oscillation (QBO).…”

Short-term climatic impact of the 1991 volcanic eruption of Mt. Pinatubo and effects on atmospheric tracers

“…The e-folding time for SO 2 removal from the stratosphere has been estimated using satellite measurements: estimates are 33 days in the 21-31 km layer from the UARS Microwave Limb Sounder (MLS) instrument (Read et al, 1993) and 35 days from TOMS (Bluth et al, 1992). The e-folding time for aerosol decay in the whole stratosphere is estimated to be 11.4 months from the Stratospheric Aerosol and Gas Experiment (SAGE-II) (Weisenstein et al, 1997) and 8.8 months from the Advanced Very High Resolution Radiometer (AVHRR) for the 20S to 30N region (Grant et al, 1996).…”