Response of California temperature to regional anthropogenic aerosol changes

In this paper, we compare constructed records of concentrations of black carbon (BC)--an indicator of anthropogenic aerosols--with observed surface temperature trends in California. Annual average BC concentrations in major air basins in California significantly decreased after about 1990, coincident with an observed statewide surface temperature increase. Seasonal aerosol concentration trends are consistent with observed seasonal temperature trends. These data suggest that the reduction in anthropogenic aerosol concentrations contributed to the observed surface temperature increase. Conversely, high aerosol concentrations may lower surface temperature and partially offset the temperature increase of greenhouse gases

A comparison of aerosol chemical and optical properties from the 1st and 2nd Aerosol Characterization Experiments

Shipboard measurements of aerosol chemical composition and optical properties were made during both ACE-1 and ACE-2. ACE-1 focused on remote marine aerosol minimally perturbed by continental sources. ACE-2 studied the outflow of European aerosol into the NE Atlantic atmosphere. A variety of air masses were sampled during ACE-2 including Atlantic, polar, Iberian Peninsula, Mediterranean, and Western European. Reported here are mass size distributions of non-sea salt (nss) sulfate, sea salt, and methanesulfonate and submicron and supermicron concentrations of black and organic carbon. Optical parameters include submicron and supermicron aerosol scattering and backscattering coefficients at 550 nm, the absorption coefficient at 550±20 nm, the Ångström exponent for the 550 and 700 nm wavelength pair, and single scattering albedo at 550 nm. All data are reported at the measurement relative humidity of 55%. Measured concentrations of nss sulfate aerosol indicate that, relative to ACE-1, ACE-2 aerosol during both marine and continental flow was impacted by continental sources. Thus, while sea salt controlled the aerosol chemical composition and optical properties of both the submicron and supermicron aerosol during ACE-1, it played a relatively smaller role in ACE-2. This is confirmed by the larger average Ångström exponent for ACE-2 continental aerosol of 1.2±0.26 compared to the ACE-1 average of -0.03±0.38. The depletion of chloride from sea salt aerosol in ACE-2 continental air masses averaged 55±25% over all particle sizes. This compares to the ACE-2 marine average of 4.8±18% and indicates the enhanced interaction of anthropogenic acids with sea salt as continental air masses are transported into the marine atmosphere. Single scattering albedos averaged 0.95±0.03 for ACE-2 continental air masses. Averages for ACE-2 and ACE-1 marine air masses were 0.98±0.01 and 0.99±0.01, respectively

Black Carbon Concentrations and Diesel Vehicle Emission Factors Derived from Coefficient of Haze Measurements in California: 1967-2003

We have derived ambient black carbon (BC) concentrations and estimated emission factors for on-road diesel vehicles from archived Coefficient of Haze (COH) data that was routinely collected beginning in 1967 at 11 locations in the San Francisco Bay Area. COH values are a measure of the attenuation of light by particles collected on a white filter, and available data indicate they are proportional to BC concentrations measured using the conventional aethalometer. Monthly averaged BC concentrations are up to five times greater in winter than summer, and, consequently, so is the population?s exposure to BC. The seasonal cycle in BC concentrations is similar for all Bay Area sites, most likely due to area-wide decreased pollutant dispersion during wintertime. A strong weekly cycle is also evident, with weekend concentrations significantly lower than weekday concentrations, consistent with decreased diesel traffic volume on weekends. The weekly cycle suggests that, in the Bay Area, diesel vehicle emissions are the dominant source of BC aerosol. Despite the continuous increase in diesel fuel consumption in California, annual Bay Area average BC concentrations decreased by a factor of ~;;3 from the late 1960s to the early 2000s. Based on estimated annual BC concentrations, on-road diesel fuel consumption, and recent measurements of on-road diesel vehicle BC emissions, diesel BC emission factors decreased by an order of magnitude over the study period. Reductions in the BC emission factor reflect improved engine technology, emission controls and changes in diesel fuel composition. A new BC monitoring network is needed to continue tracking ambient BC trends because the network of COH monitors has recently been retired

Emissions of Trace Gases and Particles From Savanna Fires in Southern Africa

Airborne measurements made on initial smoke from 10 savanna fires in southern Africa provide quantitative data on emissions of 50 gaseous and particulate species, including carbon dioxide, carbon monoxide, sulfur dioxide, nitrogen oxides, methane, ammonia, dimethyl sulfide, nonmethane organic compounds, halocarbons, gaseous organic acids, aerosol ionic components, carbonaceous aerosols, and condensation nuclei (CN). Measurements of several of the gaseous species by gas chromatography and Fourier transform infrared spectroscopy are compared. Emission ratios and emission factors are given for eight species that have not been reported previously for biomass burning of savanna in southern Africa (namely, dimethyl sulfide, methyl nitrate, five hydrocarbons, and particles with diameters from 0.1 to 3 μm). The emission factor that we measured for ammonia is lower by a factor of 4, and the emission factors for formaldehyde, hydrogen cyanide, and CN are greater by factors of about 3, 20, and 3–15, respectively, than previously reported values. The new emission factors are used to estimate annual emissions of these species from savanna fires in Africa and worldwide

Quality Management System in Stavropol Research Anti-Plague Institute

The analysis of the structure of quality management system and the areas of its activity is presented. Trends for its further improvement are defined