# Presentation: 201451

## Fine Particle Episode Occurring in Montgomery County, TN September 5-15, 2005

***Peak observation at MC occurred at 8am 09/09/05 and was 121.7 ******μ******g/m******3******.  Other monitors recorded levels of 42.9 ******μ******g/m******3******, 44.2 ******μ******g/m******3****** and 62.9 ******μ******g/m******3****** at this same time.***

***On average the Montgomery County monitor was 11.3 ******μ******g/m******3****** higher than the three closest monitors Sep 7-14, 2005.***

***Wind direction was taken from Clarksville Outlaw Field Airport, Nashville International Airport and Bowling Green – Warren County Regional Airport and correlated with PM******2.5****** taken from Montgomery County, Lockeland and Mammoth monitors respectively based on hourly observations throughout the time period. ***

***It is believed that long range transport along with high pressure weather conditions initially allowed the background levels to become elevated.***

***......The nostalgic aroma of smoking tobacco barns along winding country roads......***

**Fine Particle Episode Occurring in Montgomery County, TN September 5-15, 2005**

- 	The Tennessee Valley Authority (TVA) in cooperation with the state of Tennessee runs a continuous TEOM PM2.5 monitor in Montgomery County, TN which is approximately fifty miles north northwest of Nashville, TN.  This monitor recorded unusually elevated PM2.5 levels from September 5-15, 2005 compared to other monitors in and around the Tennessee Valley region.  TVA and Tennessee Department of Environment & Conservation conducted a case study analysis of this episode considering the relationship between PM2.5 levels and various meteorological variables and potential local, regional and long range sources. Surface winds throughout the period were light and had a northerly component September 5-10, were variable September 11-12, and had a southerly component September 13-15, corresponding to a high pressure system slowly progressing from west to east throughout the time frame.  Hourly dewpoint and relative humidity observations were relatively high (relative humidity generally above 90%) from 10pm-8am for each day throughout the time period, which corresponded well with several of the higher PM2.5 observations recorded in the pre-dawn hours.  It is suspected that early morning inversions and stagnant conditions throughout the day associated with the high pressure system hindered the transport and dilution of background PM2.5 levels caused by emissions from local sources such as agricultural burning, as well as long range transport of smoke from fires occurring in Idaho during the first half of the period.  Another concern of this episode is how unusually elevated PM2.5 levels occurring in a relatively short time period can influence the annual average for the site.

***The September 5-15, 2005 elevated PM******2.5****** episode at Montgomery County, TN illustrates how given conducive weather conditions, local sources as well as long range transport can work together to cause short term time spans of above normal PM******2.5****** observations.  ***
***TVA and the State of Tennessee plan to continue operating the TEOM PM******2.5****** monitor in Montgomery County, TN for at least one more year in hopes that local effect episodes can be further investigated during next year’s tobacco curing season.***

- Authors:  Jennifer M. Call, William J. Parkhurst,
-                 Pamela Barkey,  E. Robert Brawner,
-                 and Jackie L. Waynick
- Affiliation: Tennessee Valley Authority (TVA) and the
-                 Tennessee Department of Environment
-                  and Conservation (TDEC)
- Assigned Number:  10