Exceptional Event Console

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Console Description

The data for the 42 event days are presented using "Event Analysis Consoles" (i.e. data presentation templates) that present the relevant information in a well-defined data content and structure that is consistent from one event to another. The second key feature of the consoles is that they are dynamic, i.e. they can be adjusted to best fit the users needs. For instance, the current Event Consoles include a set of data-images selected by our group. However, users could add other data views that are relevant to their particular analysis. The data presentation template consists of a set of data views that include maps and time charts of chemical composition for fine particle organics and sulfate.

The unique feature of each chart presented in the analysis is that the chart images on the webpage are directly linked to the DataFed Viewer, thus interested analysts can explore any of the presented datasets in more detail using the interactive data Viewer. Below is a description of the Exceptional Event consoles.

The Console consists of seven data views arranged as tiles on a web page. The first view depicts the map of PM2.5 concentration arising from several networks including the FRM and STN networks in the EPA AIRS system as well as the IMPROVE network. In the map view, the measured PM2.5 concentrations are represented as both circles (bubbles) as well as shaded contour maps. The high spatial density of the integrated PM2.5 dataset provides an excellent spatial representation of daily averages every third day. This view is particularly useful to examine the spatial extent of the overall PM2.5 mass concentration.

The second map is similar to the first, except it shows the concentration of SmokeBioMass as maps and as shaded contours. The definition of SmokeBioMass is given in the section "Estimation of SmokeBioMass." See Appendix for smoke estimation procedure. This view is based on the relative amounts of the measured organic carbon (OC) and elemental carbon (EC) and it is indicative of smoke mass concentration. However, the concentration values also include the background biogenic organics as well as the smoke. This parameter explicitly excludes the (anthropogenic) Soot component of the organics. The superimposed ‘ATAD’ back-trajectories indicate the airmass histories arriving to the Chattanooga, TN and Greenville, SC locations and the Great Smoky Mountains national park (GRSM) IMPROVE monitoring site. In future analyses the quality of the trajectory calculations can be improved considerably. Possible improvements may include: (1) using transport wind fields derived from high resolution models, such as MM5; (2) inclusion of realistic vertical mixing-dispersion algorithms; and (3) performing diagnostic calculations by exploring the role of key input parameters, such as release height. This latter parameter is particularly important and challenging for buoyant smoke plumes in biomass fires where the size and heat energy of the fire drives its emission height. This question will continue to falls into realm of active research in smoke dispersion for many years to come.

The third map is identical to the second except that it depicts the sulfate ion concentration. The sulfate maps are useful to decide whether a high-PM episode is dominated by SO4 or SmokeBioMass. For example, a high concentration of SO4 and large relative amount of PM2.5 mass indicates greater influence of sources other than exceptional event fires, such as coal fired utility boilers.

The fourth and fifth charts show the time series of PM25, Sulfate and SmokeBioMass. The time charts can show if a given sample day is dominated by sulfate or smoke-related organics. Also, the time series are useful to identify spikes that may be associated with smoke events. Each time chart covers a two-month time period, centered at the particular event day. The sixth color SEAWiFS satellite image view is added to describe the overall meteorological setting for the claimed exceptional event day. The image shows the distribution of weather systems through the white clouds, the location of aerosols through the bluish haze and the pattern of surface winds measured by the 1200-station meteorological network. This view also shows the pattern of absorbing aerosol index reported from the TOMS satellite. For sake of transport analysis the back trajectories to Chattanooga , TN , Greenville SC and GRSM are also included. The wind field and trajectories are particularly useful to highlight regions of fast transport or zones of stagnation. Under the very slow-stagnating or very high transport conditions, the ATAD trajectories are considered more representative of the actual transport than during variable wind conditions.

Finally, the seventh view shows the pattern of daily aerosol optical thickness derived from the SEAWiFS satellite (2002-2004). Superimposed on the satellite image when available are fire pixels reported by the NOAA Hazard Mapping System. High density of fire pixels is indicative of higher fire emissions. Satellite images delineate both the synoptic-scale (e.g. haze) as well as fine-scale (e.g. smoke) features of PM events under cloud-free conditions. Satellite images frequently provide a clear and compelling visual picture of smoke plumes. Plumes are recognizable visually on satellite images by their shape and texture. Their shape is elongated cigar or snake-like high-Aerosol Optical Thickness (AOT) regions. Plumes have reasonably well-defined boundaries. This pattern is distinctly different from anthropogenic ‘haze’, which is spatially much more homogeneous with less distinct boundaries. Thus, satellite images can provide ‘smoking gun’ type of evidence for biomass smoke. Unfortunately, this ‘compelling evidence’ of smoke presence needs to tempered by the fact that such satellite data do not provide the vital information whether the smoke is surface based or is aloft where it normally travels. Without additional support, such as surface-based measurements of smoke signal or documentation of downward mixing, the satellite AOT data are to be considered qualitative, circumstantial evidence of smoke impact on surface air quality.

There are two versions of the Console, one for Chattanooga and another for Greenville . The focus on these two cities was based on the guidance provided by EPA.

Datasets Used

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