A monthly and latitudinally varying volcanic forcing dataset in simulations of 20th century climate

Average global surface air temperature with full forcings. 
 Bottom: 25-year averaged forcing contributions. 
Thin black bars: combined natural forcing (solar + volcanic).
A monthly and latitudinally varying volcanic forcing dataset in simulations of 20th century climate
Geophysical Research Letters
Vol. 30, No. 12, 1657 (June 2003).


Caspar M. Ammann, Gerald A. Meehl, and Warren M. Washington
Climate and Global Dynamics Division, National Center for Atmospheric Research, Boulder, Colorado, USA

Charles S. Zender
Department of Earth System Science, University of California, Irvine, California, USA


PCM 4-member ensemble average global surface air temperature with full forcings (red line) compared to the range of observational estimates (blue shaded area) from Jones et al. [2001], Hansen et al. [1999] and Quayle et al. [1999] . Bottom: 25-year averaged forcing contributions. Thin black bars: combined natural forcing (solar + volcanic). Click to enlarge.
ABSTRACT:
A new monthly volcanic forcing dataset is included in a coupled GCM for a more physically consistent treatment of the stratospheric sulfate aerosol history from explosive volcanism. The volcanic forcing is different from previous versions in that there is an individual evolution of the aerosol for each event. Thus the seasonal and latitudinal dependence of the volcanic aerosol can affect global climate in a more realistic way prior to the satellite period, compared to earlier volcanic forcing datasets. Negative radiative forcing from volcanic activity is greatest in the early 20th century prior to 1915 and in the late 20th century after 1960. The combination of volcanic and solar forcing contributes to an early-20th century warming, followed by relative cooling in late 20th century. Consequently, the addition of natural forcing factors to the anthropogenic GHG forcing in late 20th century is required to simulate the observed late 20th century warming.

DATA:
Download the data from this study:
Volcanic forcing data for climate modeling covering the period 1890-1999 in text or netCDF format.

To read or view the full study, please visit the AGU website.
It was published in Geophysical Research Letters Vol. 30, No. 12, 1657 (June 2003)

A portion of this study was supported by the Office of Biological and Environmental Research, US Department of Energy, as part of its Climate Change Prediction Program. C. M. A. is also grateful to B. L. Otto-Bliesner and J. T. Kiehl for support. The National Center for Atmospheric Research is sponsored by the National Science Foundation.


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28 July 2003