KCMP Minnesota Tall Tower Ammonia Observations and Emission Estimates Dataset 2017-2018

This data set contains NH3 mixing ratios, net ecosystem NH3 exchange, and supporting information measured at a tall tower (KCMP, 244 meter) site near St. Paul, Minnesota, USA. The data include NH3 and H2O mixing ratios measured at the 100 meter level, as well as NH3 mixing ratio measured at the 56 meter level. Wind data was measured using a sonic anemometer at the 185 meter level. Also included in this data set are values of wet N and NH3 deposition from 2016 - 2018. This data was collected to improve understanding of the ammonia and reactive nitrogen budget for the region. Ammonia mixing ratios were filtered for periods when the NH3 analyzer measured anomalous (i.e. 10 mmol mol-1) water vapor mixing ratios based on comparison with the IRGA (LI7000). Further, we filtered out NH3 observations obtained during strongly condensing conditions. These periods were identified when the water vapor mixing ratio differences between the 100 m and 56 m levels were more negative than -0.5 mmol mol-1 (i.e. when the water vapor gradient was strong and directed toward the land surface). Finally, we filtered out NH3 fluxes when the atmosphere was strongly stable (i.e. when (z-d)/L exceeded a value of +4.5) and subject to decoupling from the surface fluxes. Approximately 35.1% of the hourly flux data were either missing due to instrument failure or filtered according to the above quality control procedures.