Publications Published in 2005

1. Abatement costs of post-Kyoto climate regimes. Elzen, Michel Den; Lucas, Paul; Vuuren, Detlef van.
   Energy Policy: 2005
   Notes
   This article analyses the abatement costs of three post-Kyoto regimes for differentiating commitments compatible with stabilising atmospheric greenhouse gases concentrations at 550 ppmv CO2 equivalent in 2100. The three regimes explored are: (1) the Multi-Stage approach assumes a gradual increase in the number of Parties involved who are adopting either emission intensity or reductions targets; (2) the Brazilian Proposal approach, i.e. the allocation or reductions based on countries’ contribution to temperature increase; (3) Contraction & Convergence, with full participation in convergence of per capita emission allowances. In 2050, the global costs increase up to about 1% of the world GDP, ranging from 0.5% to 1.5%, depending on baseline scenario and marginal abatement costs. Four groups of regions can be identified on the basis of similar costs (expressed as the percentage of GDP). These are: (1) OECD regions with average costs; (2) FSU, the Middle East and Latin America with high costs; (3) South-East Asia and East Asia (incl. China) with low costs; and (4) South Asia (incl. India) and Africa with net gains from emissions trading for most regimes. The Brazilian Proposal approach gives the highest costs for groups 1 and 2. The distribution of costs for the Contraction & Convergence approach highly depends on the convergence year. The Multi-Stage approach and Contraction & Convergence (convergence year 2050) seem to result in relatively the most even distribution of costs amongst all Parties.
   
   
   
2. A consistent poleward shift of the storm tracks in simulations of 21st century climate. Yin, Jeffrey H..
   Geophysical Research Letters: 2005
   Notes
   A consistent poleward and upward shift and intensification of the storm tracks is found in an ensemble of 21st century climate simulations performed by 15 coupled climate models. The shift of the storm tracks is accompanied by a poleward shift and upward expansion of the midlatitude baroclinic regions associated with enhanced warming in the tropical upper troposphere and increased tropopause height. The poleward shift in baroclinicity is augmented in the Southern Hemisphere and partially offset in the Northern Hemisphere by changes in the surface meridional temperature gradient. The poleward shift of the storm tracks also tends to be accompanied by poleward shifts in surface wind stress and precipitation, and a shift towards the high index state of the annular modes. These results highlight the integral role that the storm tracks play in the climate system, and the importance of understanding how and why they will change in the future.
   
   
   
3. A Demonstration That Large-Scale Warming Is Not Urban . Parker, David E..
   Journal of Climate: 2005
   Notes
   On the premise that urban heat islands are strongest in calm conditions but are largely absent in windy weather, daily minimum and maximum air temperatures for the period 1950–2000 at a worldwide selection of land stations are analyzed separately for windy and calm conditions, and the global and regional trends are compared. The trends in temperature are almost unaffected by this subsampling, indicating that urban development and other local or instrumental influences have contributed little overall to the observed warming trends. The trends of temperature averaged over the selected land stations worldwide are in close agreement with published trends based on much more complete networks, indicating that the smaller selection used here is sufficient for reliable sampling of global trends as well as interannual variations. A small tendency for windy days to have warmed more than other days in winter over Eurasia is the opposite of that expected from urbanization and is likely to be a consequence of atmospheric circulation changes.
   
   
   
4. Aerosol anthropogenic component estimated from satellite data. Kaufman, Y.J.; Boucher, O.; Tanre, D; Chin, M.; Remer, L.A.; Takemura, T..
   Geophysical Research Letters: 2005
   Notes
   Satellite instruments do not measure the aerosol chemical composition needed to discriminate anthropogenic from natural aerosol components. However the ability of new satellite instruments to distinguish fine (submicron) from coarse (supermicron) aerosols over the oceans, serves as a signature of the anthropogenic component and can be used to estimate the fraction of anthropogenic aerosols with an uncertainty of ±30%. Application to two years of global MODIS data shows that 21 ± 7% of the aerosol optical thickness over the oceans has an anthropogenic origin. We found that three chemical transport models, used for global estimates of the aerosol forcing of climate, calculate a global average anthropogenic optical thickness over the ocean between 0.030 and 0.036, in line with the present MODIS assessment of 0.033. This increases our confidence in model assessments of the aerosol direct forcing of climate. The MODIS estimated aerosol forcing over cloud free oceans is therefore −1.4 ± 0.4 W/m
   
   
   
5. Aerosol invigoration and restructuring of Atlantic convective clouds. Koren, Ilan; Kaufman, Yoram J.; Rosenfeld, Daniel; Remer, Lorraine A.; Rudich, Yinon.
   Geophysical Research Letters: 2005
   Notes
   Clouds and precipitation play crucial roles in the Earth's energy balance, global atmospheric circulation and the availability of fresh water. Aerosols may modify cloud properties and precipitation formation by modifying the concentration and size of cloud droplets, and consequently the strength of cloud convection, and height of glaciation levels thus affecting precipitation patterns. Here we evaluate the aerosol effect on clouds, using large statistics of daily satellite data over the North Atlantic Ocean. We found a strong correlation between the presence of aerosols and the structural properties of convective clouds. These correlations suggest systematic invigoration of convective clouds by pollution, desert dust and biomass burning aerosols. On average increase in the aerosol concentration from a baseline to the average values is associated with a 0.05 ± 0.01 increase in the cloud fraction and a 40 ± 5mb decrease in the cloud top pressure.
   
   
   
6. Aerosol organic carbon to black carbon ratios: Analysis of published data and implications for climate forcing. Novakov, T.; Menon, S.; Kirchstetter, T.W..
   Journal of Geophysical Research: 2005
   Notes
   Measurements of organic carbon (OC) and black carbon (BC) concentrations over a variety of locations worldwide have been analyzed to infer the spatial distributions of the ratios of OC to BC. Since these ratios determine the relative amounts of scattering and absorption, they are often used to estimate the radiative forcing due to aerosols. An artifact in the protocol for filter measurements of OC has led to widespread overestimates of the ratio of OC to BC in atmospheric aerosols. We developed a criterion to correct for this artifact and analyze corrected OC to BC ratios. The OC to BC ratios, ranging from 1.3 to 2.4, appear relatively constant and are generally unaffected by seasonality, sources, or technology changes, at the locations considered here. The ratios compare well with emission inventories over Europe and China but are a factor of 2 lower in other regions. The reduced estimate for OC/BC in aerosols strengthens the argument that reduction of soot emissions maybe a useful approach to slow global warming.
   
   
   
7. Aerosol Transport in the California Central Valley Observed by Airborne Lidar. DeYoung, R. J.; Grant, W. B.; Severance, K..
   Environ Sci Technol: 2005
   Notes
   An aerosol lidar system was deployed on the NASA DC-8 and used to measure aerosol vertical profiles in the California Central Valley. The nadir-pointing Nd:YAG lidar operated at 532 and 1064 nm at 20 Hz. The resulting aerosol profiles were plotted in a unique three-dimensional format that allowed the visual observation of the aerosol scattering ratio profiles, the valley topography, and corresponding backward trajectory air masses. The accumulation of aerosols from the Bakersfield area can be seen in the southern end of the valley due to topography and prevailing winds.
   
   
   
8. A global comparsion of surface and free-air temperatures at high elevations. Pepin, N C; Seidel, Dian J.
   Journal of Geophysical Research: 2005
   Notes
   Surface and free-air temperature observations from the period 1948–2002 are compared for 1084 surface locations at high elevations (>500 m) on all continents. Mean monthly surface temperatures are obtained from two homogeneity adjusted data sets: Global Historical Climate Network (GHCN) and Climatic Research Unit (CRU). Free-air temperatures are interpolated both vertically and horizontally from the National Centers for Environmental Prediction/National Center for Atmospheric Research Reanalysis R1 2.5
   
   
   
9. A global view of aerosols from merged transport models, satellite, and ground observations. Liu, Hongqing; Pinker, R T; Holben, B N.
   Journal of Geophysical Research: 2005
   Notes
   The value restored and added by dynamical downscaling is quantitatively evaluated by considering the spectral behavior of the Regional Atmospheric Modeling System (RAMS) in relation to its domain size and grid spacing. A regional climate model (RCM) simulation is compared with NCEP Reanalysis data regridded to the RAMS grid at each model analysis time for a set of six basic experiments. At large scales, RAMS underestimates atmospheric variability as determined by the column integrated kinetic energy and integrated moisture flux convergence. As the grid spacing increases or domain size increases, the underestimation of atmospheric variability at large scales worsens. The model simulated evolution of the kinetic energy relative to the reanalysis regridded kinetic energy exhibits a decrease with time, which is more pronounced with larger grid spacing. Additional follow-on experiments confirm that the surface boundary forcing is the dominant factor in generating atmospheric variability for small-scale features and that it exerts greater control on the RCM solution as the influence of lateral boundary conditions diminish. The sensitivity to surface forcing is also influenced by the model parameterizations, as demonstrated by using a different convection scheme. For the particular case considered, dynamical downscaling with RAMS in RCM mode does not retain value of the large scale which exists in the larger global reanalysis. The utility of the RCM, or value added, is to resolve the smaller-scale features which have a greater dependence on the surface boundary. This conclusion regarding RAMS is expected to be true for other RCMs as well.
   
   
   
10. Air quality impacts of the October 2003 southern California wildfires. Phuleria, Harish; Fine, Philip M; Zhu, Yifang; Sioutas, Constantinos.
    Journal of Geophysical Research: 2005
    Notes
    In Southern California, dry summers followed by hot and dry westerly wind conditions contribute to the region’s autumn fire season. In late October 2003, 13 large Southern California wildfires burned more than 750,000 acres of land, destroyed over 3500 structures, and displaced approximately 100,000 people. The fire episode was declared the deadliest and most devastating in more than a decade, and local media advised individuals to stay indoors to avoid exposure to excessive levels of PM, CO, VOCs, and ozone caused by the wildfires. This study examines the actual impact of these wildfires on air quality in urban Los Angeles (LA) using ‘‘opportunistic’’ data from other air pollution studies being conducted at the time of the fires. Measurements of pollutant gases (CO, NOx, and ozone), particulate matter (PM), particle number (PN) concentrations, and particle size distributions at several sampling locations in the LA basin before, during, and after the fire episode are presented. In general, the wildfires caused the greatest increases in PM10 levels (a factor of 3–4) and lesser increases in CO, NO, and PN (a factor of up to 2). NO2 levels remained essentially unchanged, and ozone concentrations dropped during the fire episode. Particle size distributions of air sampled downwind of the fires showed number modes at diameters between 100 and 200 nm, significantly larger than that of typical urban air. The particles in this size range were shown to effectively penetrate indoors, raising questions about the effectiveness of staying indoors to avoid exposure to wildfire emissions.