ARS | Publication request: Quantifying atmospheric stability conditions at a swine facility and an adjacent corn field in Iowa

Submitted to: Journal of Theoretical and Applied Climatology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 28, 2010
Publication Date: February 3, 2011
Citation: Hernandez Ramirez, G., Sauer, T.J., Hatfield, J.L., Prueger, J.H. 2011. Quantifying atmospheric stability conditions at a swine facility and an adjacent corn field in Iowa, USA. Journal of Theoretical and Applied Climatology. Available: http://www.springerlink.com/content/e63183263470g481/.

Interpretive Summary: Wind is the primary force that transfers pollutants in the atmosphere. There are times when the surface is warmed by the sun and this leads to warm air rising into the atmophere. This process can also affect the movement of dust and gases in the atmosphere. This study involved measuring air and suface temperature and wind speed near a swine production facility and in a nearby corn field. The results showed that the metal-roofed buildings got very warm during the day and warm air rising near the facility probably took dust and gases that may be related to odor or the greenhouse effect with it. Much of this air and the pollutants likely moved high into the atmosphere when winds are light and the surface is hot. This would reduce the chance of odor complaints downwind but still means that the dust and gases are going into the atmosphere. This research is of interest to scientists studying air quality and especiall the positioning of air sampling equipment.

Technical Abstract: Atmospheric stability conditions in the atmospheric surface layer can control the distance and direction of transport of air contaminants. Near confined animal facilities, these transport processes can significantly impact air quality as these sites typically act as net point sources of dust and odor constituents; however, little information is available on atmospheric stability effects. This study was conducted to assess year-round temporal patterns of atmospheric stability at a swine production facility and an adjacent commercial corn field (CF) in the US Midwest. Two towers of 20 and 10 m heights for continuous micrometeorological measurements were deployed between swine buildings (BSB) and within a CF, respectively. Each tower was equipped with an eddy-covariance (EC) system at 6.8 m height, infrared thermometers (IRT), and 6 cup anemometers with thermocouples installed at log-distributed heights. Overall results from gradient Richardson number (Ri) and Monin-Obukhov (z/L) calculations revealed predominantly more unstable conditions for BSB compared to CF. During the 13 month measurement period, unstable cases (z/L ranging from -1 to -0.01) occurred 1.4 times more frequently for BSB than CF (52 vs. 39%, respectively), while stable cases (0.01-1) were 2.1 times more frequent for CF than BSB (40 vs. 18%, respectively). These patterns were partly associated with higher surface radiometric temperatures for BSB. Relatively greater diurnal heat capture at BSB (ground and roof surfaces) and a cooling effect in CF through active canopy transpiration during the daytime could in part explain these z/L and radiometric temperature results. Prevalent diurnal atmospheric instability at BSB suggests enhanced ascendant vertical transport of air pollutants perhaps causing greater mixing/dilution with the atmospheric layer and/or their facilitated transport sorbed onto particles over greater distances. An enhanced understanding of these spatio-temporal atmospheric stability patterns can help identify effective odor mitigation strategies near commercial animal facilities.