Abstract
The Mt. Pinatubo eruption in 1991 had a severe impact on the Earth system with a well-documented warming of the tropical lower stratosphere and a general cooling of the surface. This study focuses on the impact of this event on the mesosphere by analyzing solar occultation temperature data from the Halogen Occultation Experiment (HALOE) instrument on the Upper Atmosphere Research Satellite (UARS). Previous analysis of lidar temperature data found positive temperature anomalies of up to 12.9 K in the upper mesosphere that peaked in 1993 and were attributed to the Pinatubo eruption. Fitting the HALOE data according to a previously published method indicates a maximum warming of the mesosphere region of 3.3 K and does not confirm significantly higher values reported for that lidar time series. An alternative fit is proposed that assumes a more rapid response of the mesosphere to the volcanic event and approximates the signature of the Pinatubo with an exponential decay function having an e-folding time of 6 months. It suggests a maximum warming of 5.5 K if the mesospheric perturbation is assumed to reach its peak 4 month after the eruption. We conclude that the HALOE time series probably captures the decay of a Pinatubo-induced mesospheric warming at the beginning of its measurement period.
Highlights
Explosive volcanic eruptions inject large amounts of gases and ash into the atmosphere with a potential impact on global climate
This study focuses on the impact of this event on the mesosphere by analyzing solar occultation temperature data from the Halogen Occultation Experiment (HALOE) instrument on the Upper Atmosphere Research Satellite (UARS)
Fitting the HALOE data according to a previously published method indicates a maximum warming of the mesosphere region of 3.3 K and does not confirm significantly higher values reported for that lidar time series
Summary
Explosive volcanic eruptions inject large amounts of gases and ash into the atmosphere with a potential impact on global climate. Analysing Rayleigh lidar data, Keckhut et al (1995) observed a significant warming of 5 K in the mesosphere from 60 – 80 km in the summer of 1992 and 1993 and at 44◦ N They associated this finding with the Pinatubo eruption. Annually averaged temperature data from the High Resolution Doppler Imager on the Upper Atmosphere Research Satellite (UARS) exhibited a 5 K warming at 100 km in the years 1992 and 1993 which might be related to the Pinatubo eruption according to 35 the authors (Thulasiraman and Nee, 2002). The simulations showed volcanic perturbations to the atmospheric temperature field reaching up into the lower thermosphere These responses were 40 not significant in many latitude-altitude regions and the underlying physico-chemical processes were not discussed in Ramesh et al (2020).
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