COMPILATION OF REGIONAL TO GLOBAL INVENTORIES OF ANTHROPOGENIC EMISSIONS

The mathematical modeling of the transport and transformation of trace species in the atmosphere is one of the scientific tools currently used to assess atmospheric chemistry, air quality, and climatic conditions. From the scientific but also from the management perspectives accurate inventories of emissions of the trace species at the appropriate spatial, temporal, and species resolution are required. There are two general methodologies used to estimate regional to global emissions: bottom-up and top-down (also known as inverse modeling). Bottom-up methodologies to estimate industrial emissions are based on activity data, emission factors (amount of emissions per unit activity), and for some inventories additional parameters (such as sulfur content of fuels). Generally these emissions estimates must be given finer sectoral, spatial (usually gridded), temporal, and for some inventories species resolution. Temporal and spatial resolution are obtained via the use of surrogate information, such as population, land use, traffic counts, etc. which already exists in or can directly be converted to gridded form. Speciation factors have been and are being developed to speciate inventories of NO{sub x}, particulate matter, and hydrocarbons. Top-down (inverse modeling) methodologies directly invert air quality measurements in terms of poorly known but critical parameters to constrain the emissions needed to explain these measurements; values of these parameters are usually computed using atmospheric transport models. Currently there are several strong limitations of inverse modeling, but the continued evolution of top-down estimates will be facilitated by the development of denser monitoring networks and by the massive amounts of data from satellite observations

Aerosol sulfate loading and shortwave direct radiative forcing over the North Atlantic Ocean

Shortwave radiative forcing of climate by anthropogenic sulfate aerosols is estimated to be equal in magnitude but opposite in sign to that of greenhouse warming, with a global annual average value of approximately -1 W m{sup -2} uncertain to at least a factor of two. Estimates of the 2 contributions to this forcing by the direct effect are -0.4 W m{sup -2}. It is therefore necessary to accurately and efficiently represent this forcing in climate models, specifically including spatial and temporal variability. Here we explore a method to expedite the process for determining this forcing. The method utilizes an approach where the forcing is computed precisely at several discrete radii (r) and then integrated over an arbitrary aerosol size distribution. Additionally, the forcing is calculated at several values of relative humidity (RH), solar zenith angle (SZA), and aerosol optical thickness ({tau}). The parameters can be interpolated to provide the forcing at specific intermediate values. Alternatively, an empirical relationship between the forcing and the above mentioned variables can be utilized to further reduce computation time. At present, the calculations are restricted to ammonium sulfate particles over an ocean surface. The advantage of the ocean surface is the constant and low albedo compared to the highly variable albedo of land surfaces. Ultimately, the sensitivity of forcing to surface albedo and composition will be included

The influence of cut off lows on sulfate burdens over the North Atlantic during April, 1987

The authors have presented examples from a modeling study of the development of sulfur burdens over North America, the North Atlantic Ocean and Europe during April, 1987 using observation-derived meteorological data to represent the actual conditions for this period, focusing on the influence of cut-off lows on SO{sub 2} and sulfate column burdens over the North Atlantic Ocean. The analysis demonstrates that these systems can serve either as sources or sinks of sulfate, and that the major factor governing their resulting effect is the position during its formative stages relative to (a) sources of moisture, and (b) sulfur emissions, which regulates the availability of sulfur, cloud liquid water for sulfur oxidation, and the amount of precipitation for sulfate removal produced in the later stages of the life cycle

Cloud susceptibility and the first aerosol indirect forcing: Sensitivity to black carbon and aerosol concentrations

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94864/1/jgrd8696.pd

A comparison of scavenging and deposition processes in global models: results from the WCRP Cambridge Workshop of 1995

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75543/1/j.1600-0889.2000.00980.x.pd