The graphic created by ADAPT shows the potential source locations for each 6-h period as indicated by the times (YYMMDDHHmm) shown along the top corners for pollutants arriving at the monitoring location. Calculations assumed a unit emission rate of one per hour. The sampled air could have come from any upwind grid cell. The grid-cell values (units m-3) represent dilution factors and can be used to make a more quantitative estimate of the emissions required to match the measurements at the monitoring site (black dot). Pollutant emissions could be from only one source, such as a power plant, or for more regional pollutants, from multiple sources. The pattern does not suggest probability, in that source regions with higher values (warmer colors) are more likely. All grid-cells are equally likely. Lower dilution values, along the off-centerline grid cells, only means that a higher emission rate is required to achieve the measured value. The circle is drawn at a radius of 100 km from the measurement point.