Radiative Forcing and Climatic Impact of the Mount Pinatubo Volcanic Eruption

Changes in radiative fluxes and atmospheric heating rates were computed by using the UIUC 24-layer Stratosphere/Troposphere General Circulation Model (ST-GCM) and a reconstructed dataset of the Pinatubo aerosol optical properties. Composite and the Singular Value Decomposition (SVD) analyses were used to detect and separate the signals of the Pinatubo aerosol forcing and ENSO events from the observed surface air-temperature anomalies (DeltaTs) over land. It is found that the 1991--1992 El Nino event contributed more than 50% to the observed cooling over North America in JJA 1992. The averaged DeltaTS over Eurasia, North America, South America and Africa reached -0.5°C in JJA and SON 1992 and SON 1993 with the ENSO signals removed. Ensemble simulations were performed by using the ST-GCM to explore the responses of the atmosphere to the Pinatubo aerosol forcing and/or the observed SST anomalies. It is found that the ST-GCM simulates well the ENSO-induced DeltaTS over land. When forced by the Pinatubo aerosol, the model better simulates the observed cooling in JJA 1992 than the observed warming in DJF 1991--1992 over Eurasia and North America. The simulated stratospheric temperature anomalies induced by the Pinatubo aerosol are generally 1°C to 2°C larger than observed in 1992. Empirical data analyses and model simulations showed that this discrepancy is explained in part by the influences of the quasi-biennial oscillation and the observed ozone depletion, which were not included in the ensemble simulations. The influence of the ocean on the simulated climatic responses of the atmosphere to the Pinatubo aerosol forcing was also examined using a coupled atmosphere/ocean GCM.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Atmospheric Sciences

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Yang, Fanglin

Contributors dc:contributor

• Schlesinger, Michael E.

• Geophysics

Language dc:language

eng

Identifier

(MiAaPQ)AAI9955684

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/85987