@article {769, title = {Hypothesized climate forcing time series for the last 500 years}, journal = {Journal of Geophysical Research-Atmospheres}, volume = {106}, year = {2001}, note = {456yeTimes Cited:108Cited References Count:89}, month = {Jul 27}, pages = {14783-14803}, abstract = {A new compilation of annually resolved time series of atmospheric trace gas concentrations, solar irradiance, tropospheric aerosol optical depth, and stratospheric (volcanic) aerosol optical depth is presented for use in climate modeling studies of the period 1500 to 1999 A.D. Atmospheric CO2 CH4, and N2O concentrations over this period are well established on the basis of fossil air trapped in ice cores and instrumental measurements over the last few decades. Estimates of solar irradiance, ranging between 1364.2 and 1368.2 W/m(2), are presented using calibrated historical observations of the Sun back to 1610, along with cosmogenic isotope variations extending back to 1500. Tropospheric aerosol distributions are calculated by scaling the modern distribution of sulfate and carbonaceous aerosol optical depths back to 1860 using reconstructed regional CO2 emissions; prior to 1860 the anthropogenic tropospheric aerosol optical depths are assumed to be zero. Finally, the first continuous, annually dated record of zonally averaged stratospheric (volcanic) optical depths back to 1500 is constructed using sulfate flux data from multiple ice cores from both Greenland and Antarctica, in conjunction with historical and instrumental (satellite and pyrheliometric) observations. The climate forcings generated here are currently being used as input to a suite of transient (time dependent) paleoclimate model simulations of the past 500 years. These forcings are also available for comparison with instrumental and proxy paleoclimate data of the same period.}, issn = {0747-7309}, doi = {10.1029/2000jd900469}, author = {Robertson, A. and Overpeck, J. and Rind, D. and Mosley-Thompson, E. and Zielinski, G. and Lean, J. and Koch, D. and Penner, J. and Tegen, I. and Healy, R.} } @article {396, title = {Simulated time-dependent climate response to solar radiative forcing since 1600}, journal = {Journal of Geophysical Research-Atmospheres}, volume = {104}, year = {1999}, note = {id: 1945; PT: J; UT: WOS:000078242200003}, pages = {1973-1990}, abstract = {Estimated solar irradiance variations since 1500 have been used to force the GISS atmospheric GCM coupled to a mixed layer "q-flux" ocean with heat diffusion through the bottom of the mixed layer. The goal is to assess solar-induced climate change in preindustrial and postindustrial epochs. Six simulations and control runs were made to test the effects of different initial conditions, estimates of initial solar forcing conditions, and ocean heat uptake. The results show that an estimated solar forcing increase of 0.25\% accounts for a 0.45 degrees C temperature increase since 1600 and an increase of about 0.2 degrees C over the past 100 years. Global surface temperatures lag solar fluctuations by up to 10 years; the lag is greater over the oceans and so is the correlation due to reduced noise. With only a mixed layer ocean the phase lag is 5 years less. Solar forcing and water vapor feedback each directly account for 35\% of the temperature response, with cloud cover changes contributing 20\% and sea ice/snow cover 10\%. Uncertainty in the initial radiation imbalance or solar forcing affects the surface temperatures for 60-90 years. Modeled and observed periodicities show dominance of long-period forcing (>50 years), as provided by the solar input in these experiments. Tropical temperatures correlate best with solar forcing, due to the influence of water vapor feedback, especially at these multidecadal periods. Sea ice and extratropical temperatures have less long-period power, while high-frequency fluctuations dominate simulated cloud cover variations, which are relatively independent of solar forcing changes. Global and extratropical precipitation increase as the climate warms, but not low and subtropical precipitation, due to conflicting influences of absolute temperature and temperature gradient changes. Solar forcing by itself was not sufficient to produce the rapid warming during the last several decades. A comparison experiment varying trace gas forcing suggests that if the solar estimate is correct, then negative forcing by tropospheric aerosols (and perhaps volcanoes, ozone, and land use changes) has been about -1.2 W m(-)2 since 1700, implying approximately equal contribution from direct and indirect tropospheric aerosol effects.}, issn = {0747-7309}, doi = {10.1029/1998JD200020}, author = {Rind, D. and Lean, J. and Healy, R.} }