Convective transport of pollutants from eastern Colorado feedlots into the Rocky Mountains

Easterly upslope winds are a common feature in the warm season in Colorado in the absence of synoptic forcing. Thermally driven upslope winds can carry pollutants such as NO_x and NH₃ from agricultural and urban activities into the Rocky Mountains, endangering the biodiversity of fragile mountain ecosystems. Data from the National Atmospheric Deposition Program (NADP) were used to identify events with high amounts of wet deposition of inorganic N during summers between 1994-2013. The North American Regional Reanalysis was then used to examine the synoptic-scale meteorology surrounding two of these events (18-20 August 2006 and 06-08 July 2012), chosen from the NADP data. We hypothesized cloud-scale updrafts were equally as important as the larger-scale mountain-valley circulation. The Advanced Research Weather Research and Forecasting (ARW-WRF) model was used to simulate high-resolution meteorology around the August 2006 and July 2012 events. Using a tracer released from a 2x2 km concentrated animal feeding operation in eastern Colorado, we found convective, cloud-scale transport of pollutants was just as important as the thermally driven mountain-circulation to the overall transport of pollutants from eastern Colorado into the Rocky Mountains. Knowledge from this study was used to help develop an early warning system for future events of high wet deposition of inorganic N into Rocky Mountain National Park.