TY - JOUR T1 - Plans for Expanded 14C Analyses at the NOSAMS Facility--a status and progress report. 9th International Conference on Accelerator Mass Spectrometry, Nagoya, Japan, 9/2002 JF - Nuclear Instruments and Methods in Physics Research Y1 - 2004 A1 - von Reden, K. A1 - Donoghue, J. A1 - Elder, K. A1 - Gagnon, A. A1 - Gerlach, D. A1 - Griffin, V. S. A1 - Healy, R. A1 - Long, P. A1 - McNichol, A. P. A1 - Percy, D. A1 - Roberts, M. L. A1 - Schneider, R. J. A1 - Xu, L. A1 - Hayes, J. VL - B 223-224 N1 - id: 1810 ER - TY - JOUR T1 - Modeling the d180 in precipitation over the Americas: 1. Simulation of the stable isotope in Andean ice cores JF - JGR Y1 - 2003 A1 - Vuille, M. A1 - Bradley, R. S. A1 - Healy, R. A1 - Werner, M. A1 - Handy, D. R. A1 - Thompson, L. G. A1 - Keimig, F. VL - 108 IS - D6 N1 - id: 1771 ER - TY - JOUR T1 - Modeling the d18O in precipitation over the Americas: 1. Simulation of the stable isotope in Andean ice cores JF - JGR Y1 - 2003 A1 - Vuille, M. A1 - Bradley, R. S. A1 - Healy, R. A1 - Werner, M. A1 - Hardy, D. R. A1 - Thompson, L. G. A1 - Keimig, F. VL - 108 IS - D6 N1 - id: 1691 ER - TY - JOUR T1 - Modeling the d18O in precipitation over the Americas: 2. Interannual variability and climatic controls JF - JGR Y1 - 2003 A1 - Vuille, M. A1 - Bradley, R. S. A1 - Werner, M. A1 - Healy, R. A1 - Keimig, F. VL - 108 IS - D6 N1 - id: 1692 ER - TY - CONF T1 - Plans for expanded 14C analyses at the NOSAMS facility - a status and progress report T2 - International Conference on Accelerator Mass Spectrometry Y1 - 2002 A1 - von Reden, K. F. A1 - Donoghue, J. A1 - Elder, K. A1 - Gagnon, A. A1 - Gerlach, D. A1 - Griffin, V. A1 - Healy, R. A1 - Long, P. A1 - McNichol, A. A1 - Percy, D. A1 - Roberts, M. L. A1 - Schneider, R. J. A1 - Xu, L. A1 - Hayes, J. M. JF - International Conference on Accelerator Mass Spectrometry CY - Nagoya, Japan N1 - id: 1685 ER - TY - JOUR T1 - Hypothesized climate forcing time series for the last 500 years JF - Journal of Geophysical Research-Atmospheres Y1 - 2001 A1 - Robertson, A. A1 - Overpeck, J. A1 - Rind, D. A1 - Mosley-Thompson, E. A1 - Zielinski, G. A1 - Lean, J. A1 - Koch, D. A1 - Penner, J. A1 - Tegen, I. A1 - Healy, R. AB - 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. VL - 106 IS - D14 N1 - 456yeTimes Cited:108Cited References Count:89 JO - Hypothesized climate forcing time series for the last 500 years ER - TY - JOUR T1 - Tropical cooling and the isotopic composition of precipitation in general circulation model simullations of the ice age climate JF - Climate Dynamics Y1 - 2001 A1 - Charles, C. D. A1 - Rind, D. A1 - Healy, R. A1 - Webb, R. VL - 17 N1 - id: 1716 ER - TY - RPRT T1 - Global Distribution of Total Inorganic Carbon and Total Alkalinity Below the Deepest Winter Mixed Layer Depths Y1 - 2000 A1 - Goyet, C. A1 - Healy, R. A1 - Ryan, J. AB - Modeling the global ocean-atmosphere carbon dioxide system is becoming increasingly important to greenhouse gas policy. These models require initialization with realistic three- dimensional (3-D) oceanic carbon fields. This report presents an approach to establishing these initial conditions from an extensive global database of ocean carbon dioxide (CO2) system measurements and well-developed interpolation methods. These methods are limited to waters below the deepest mixed layer. The data used for these interpolations include the recent high-quality data sets from the World Ocean Circulation Experiment (WOCE), Joint Global Ocean Flux Study (JGOFS), and Ocean-Atmosphere Carbon Exchange Study (OACES) programs. Prior to analysis, all carbon data were adjusted to established reference material listed in http://andrew.ucsd.edu/co2qc/. The interpolation methodology employs correlation between CO2 system properties and other more widely measured properties: potential temperature, salinity, and apparent oxygen utilization. The correlations are computed for each profile, and the coefficients are interpolated to the 1°×1°×32 vertical-layer grid at a monthly temporal resolution. Finally, the gridded coefficients are applied to a global monthly climatology of ocean temperature, salinity, and oxygen to compute total CO2 (TCO2) and total alkalinity (TALK) for the 3-D grid. This approach offers advantages over spin up of a single profile in defining spatial variation in CO2 system properties because it reduces initialization time and provides a more accurate carbon field. The results provide an unprecedented "view" of the global distribution of TALK and TCO2 in the ocean. These results as well as those from the monthly mixed layer depths can be used in diagnostic and prognostic global ocean models. The data set of the gridded climatological fields of TCO2, TALK, and mixed layer depths is available free of charge as a numeric data package from the Carbon Dioxide Information Analysis Center (CDIAC). The interpolated data set includes seasonal TCO2 and TALK fields as well as the coefficients used to estimate these concentrations and the monthly mixed layer depths. PB - Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory CY - Oak Ridge, Temessee VL - ORNIJCDIAC-127 NDP-076 N1 - id: 1970 ER - TY - JOUR T1 - Simulated time-dependent climate response to solar radiative forcing since 1600 JF - Journal of Geophysical Research-Atmospheres Y1 - 1999 A1 - Rind, D. A1 - Lean, J. A1 - Healy, R. AB - 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. VL - 104 IS - D2 N1 - id: 1945; PT: J; UT: WOS:000078242200003 JO - Simulated time-dependent climate response to solar radiative forcing since 1600 ER -