[1] We perform an observationally based evaluation of the cloud ice water content (CIWC) and path (CIWP) of present-day GCMs, notably 20th century CMIP5 simulations, and compare these results to CMIP3 and two recent reanalyses. We use three different CloudSat + CALIPSO ice water products and two methods to remove the contribution from the convective core ice mass and/or precipitating cloud hydrometeors with variable sizes and falling speeds so that a robust observational estimate can be obtained for model evaluations. The results show that for annual mean CIWP, there are factors of 2-10 in the differences between observations and models for a majority of the GCMs and for a number of regions. However, there are a number of CMIP5 models, including CNRM-CM5, MRI, CCSM4 and CanESM2, as well as the UCLA CGCM, that perform well compared to our past evaluations. Systematic biases in CIWC vertical structure occur below the mid-troposphere where the models overestimate CIWC, with this bias arising mostly from the extratropics. The tropics are marked by model differences in the level of maximum CIWC ($250-550 hPa). Based on a number of metrics, the ensemble behavior of CMIP5 has improved considerably relative to CMIP3, although neither the CMIP5 ensemble mean nor any individual model performs particularly well, and there are still a number of models that exhibit very large biases despite the availability of relevant observations. The implications of these results on model representations of the Earth radiation balance are discussed, along with caveats and uncertainties associated with the observational estimates, model and observation representations of the precipitating and cloudy ice components, relevant physical processes and parameterizations. F., et al. (2012), An observationally based evaluation of cloud ice water in CMIP3 and CMIP5 GCMs and contemporary reanalyses using contemporary satellite data,
[1] A unified tropospheric chemistry-aerosol model within the Goddard Institute for Space Studies general circulation model II 0 is applied to simulate an equilibrium CO 2 -forced climate in the year 2100 to examine the effects of climate change on global distributions of tropospheric ozone and sulfate, nitrate, ammonium, black carbon, primary organic carbon, secondary organic carbon, sea salt, and mineral dust aerosols. The year 2100 CO 2 concentration as well as the anthropogenic emissions of ozone precursors and aerosols/aerosol precursors are based on the Intergovernmental Panel on Climate Change Special Report on Emissions Scenarios (SRES) A2. Year 2100 global O 3 and aerosol burdens predicted with changes in both climate and emissions are generally 5-20% lower than those simulated with changes in emissions alone; as exceptions, the nitrate burden is 38% lower, and the secondary organic aerosol burden is 17% higher. Although the CO 2 -driven climate change alone is predicted to reduce the global O 3 burden as a result of faster removal of O 3 in a warmer climate, it is predicted to increase surface layer O 3 concentrations over or near populated and biomass burning areas because of slower transport, enhanced biogenic hydrocarbon emissions, decomposition of peroxyacetyl nitrate at higher temperatures, and the increase of O 3 production by increased water vapor at high NO x levels. The warmer climate influences aerosol burdens by increasing aerosol wet deposition, altering climate-sensitive emissions, and shifting aerosol thermodynamic equilibrium. Climate change affects the estimates of the year 2100 direct radiative forcing as a result of the climate-induced changes in burdens and different climatological conditions; with full gas-aerosol coupling and accounting for ozone and aerosols from both natural and anthropogenic sources, year 2100 global mean top of the atmosphere direct radiative forcings by O 3 , sulfate, nitrate, black carbon, and organic carbon are predicted to be +0.93, À0.72, À1.0, +1.26, and À0.56 W m À2 , respectively, using present-day climate and year 2100 emissions, while they are predicted to be +0.76, À0.72, À0.74, +0.97, and À0.58 W m À2 , respectively, with year 2100 climate and emissions.
Abstract. We calculate decadal aerosol direct and indirect (warm cloud) radiative forcings from US anthropogenic sources over the 1950-2050 period. Past and future aerosol distributions are constructed using GEOS-Chem and historical emission inventories and future projections from the IPCC A1B scenario. Aerosol simulations are evaluated with observed spatial distributions and 1980-2010 trends of aerosol concentrations and wet deposition in the contiguous US. Direct and indirect radiative forcing is calculated using the GISS general circulation model and monthly mean aerosol distributions from GEOS-Chem. The radiative forcing from US anthropogenic aerosols is strongly localized over the eastern US. We find that its magnitude peaked in , with values over the eastern US (east of 100 • W) of −2.0 W m −2 for direct forcing including contributions from sulfate (−2.0 W m −2 ), nitrate (−0.2 W m −2 ), organic carbon (−0.2 W m −2 ), and black carbon (+0.4 W m −2 ). The uncertainties in radiative forcing due to aerosol radiative properties are estimated to be about 50 %. The aerosol indirect effect is estimated to be of comparable magnitude to the direct forcing. We find that the magnitude of the forcing declined sharply from 1990 to 2010 (by 0.8 W m −2 direct and 1.0 W m −2 indirect), mainly reflecting decreases in SO 2 emissions, and project that it will continue declining post-2010 but at a much slower rate since US SO 2 emissions have already declined by almost 60 % from their peak. This suggests that much of the warming effect of reducing US anthropogenic aerosol sources has already been realized. The small positive radiative forcing from US BC emissions (+0.3 W m −2 over the eastern US in 2010; 5 % of the global forcing from anthropogenic BC emissions worldwide) suggests that a US emission control strategy focused on BC would have only limited climate benefit.
Our findings indicate that cranberry-containing products are associated with protective effect against UTIs. However, this result should be interpreted in the context of substantial heterogeneity across trials.
Highly efficient red phosphors with superior intrinsic properties that are excited by ultraviolet or blue light-emitting diodes are important white light sources for our daily life. Nitride-based phosphors, such as Sr2Si5N8:Eu(2+) and CaAlSiN3:Eu(2+), are commonly more red-shifted in photoluminescence and have better thermal/chemical stability than oxides. Cation substitutions are usually performed to optimize photoluminescence and thermal quenching behavior. However, the underlying mechanisms are unclear in most cases. Here we show that neighboring-cation substitution systematically controls temperature-dependent photoluminescence behavior in CaAlSiN3:Eu(2+) lattice. Trivalent cation substitution at the Ca(2+) site degrades the photoluminescence in high-temperature environments but achieves better thermal stability when the substituted cation turns monovalent. The neighboring-cation control of lifetime decay is also observed. A remote control effect that guides Eu(2+) activators in selective Ca(2+) sites is proposed for neighboring-cation substitution while the compositional Si(4+)/Al(3+) ratio adjusts to the valence of M(n+) (n = 1-3) cation. In the remote control effect, the Eu(2+) activators are surrounded with nitride anions which neighbor with M(3+)-dominant and Si(4+)/Al(3+)-equivalent coordination when M is trivalent, but shift to the site where surrounded nitride anions neighbor with M(+)-dominant and Si-rich coordination when M is monovalent. This mechanism can efficiently tune optical properties, especially thermal stability, and could be general to luminescent materials, which are sensitive to valence variation in local environments.
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