Sulfur Model Function
Description:
Dimensions: 9The Sulfur Model function models the radiative forcing of sulfur, with uncertainty in the input parameters. S0 and A are the solar constant and surface area of the Earth, respectively, which are constants with approximate values S0 = 1366 W/m2 and A = 5.1*1014 m2 (Encyclopaedia Britannica).
The response is the direct radiative forcing (ΔF) by sulfate aerosols, in W/m2.
Input Distributions:
The input random variables and their distributions are given below, where c is the central value (ie. geometric mean) of the Lognormal distribution, and u is the uncertainty factor (ie. geometric standard deviation):| Tr ~ Lognormal(c=0.76, u=1.2) | transmittance of the atmospheric layer above the aerosol layer |
| 1-Ac ~ Lognormal(c=0.39, u=1.1) | 1 - fractional cloud cover |
| 1-Rs ~ Lognormal(c=0.85, u=1.1) | 1 - mean albedo of the underlying surface |
| β̅ ~ Lognormal(c=0.3, u=1.3) | backscattered fraction |
| Ψe ~ Lognormal(c=5.0, u=1.4) | mass scattering efficiency (m2g-1) |
| fΨe ~ Lognormal(c=1.7, u=1.2) | scaling factor for Ψe |
| Q ~ Lognormal(c=71.0, u=1.15) | global input flux of anthropogenic sulfur (1012 g yr-1) |
| Y ~ Lognormal(c=0.5, u=1.5) | fraction of sulfur dioxide oxidized to sulfate aerosol |
| L ~ Lognormal(c=5.5, u=1.5) | sulfate lifetime in the atmosphere (days) |
Code:
References:
Charlson, R. J., Schwartz, S. E., Hales, J. M., Cess, R. D., Coakley Jr, J. A., Hansen, J. E., & Hofmann, D. J. (1992). Climate forcing by anthropogenic aerosols. Science, 255(5043), 423-430.
Earth. (2013). In Encyclopaedia Britannica. Retrieved from http://www.britannica.com/EBchecked/topic/175962/Earth.
Penner, J. E., Charlson, R. J., Schwartz, S. E., Hales, J. M., Laulainen, N. S., Travis, L., ... & Radke, L. F. (1994). Quantifying and minimizing uncertainty of climate forcing by anthropogenic aerosols. Bulletin of the American Meteorological Society, 75(3), 375-400.
Solar constant. (2013). In Encyclopaedia Britannica. Retrieved from http://www.britannica.com/EBchecked/topic/552889/solar-constant.
Tatang, M. A., Pan, W., Prinn, R. G., & McRae, G. J. (1997). An efficient method for parametric uncertainty analysis of numerical geophysical models. Journal of Geophysical Research, 102(D18), 21925-21.
For questions or comments, please email Derek Bingham at: dbingham@stat.sfu.ca.