DOI: 10.5061/dryad.0cfxpnwcw
title: Data from: Sensitivity of simulated ammonia fluxes in Rocky Mountain National Park to measurement time resolution and meteorological inputs

description: Gas phase ammonia (NH3) measurements were made in Rocky Mountain National
 Park (RMNP) at the base of Longs Peak. Biweekly passive NH3 data was
 collected at two heights on a National Ecological Observatory Network
 (NEON) tower site (40.275903, -105.54596). Continuous NH3 data was
 collected at a nearby National Park Service (NPS) shelter (approximately
 500 meters north of the NEON tower), using ion mobility spectroscopy.
 Continuous NH3 data had a time resolution of 30 seconds. The sites were
 located at 2750 meters above sea level. All data are ambient
 concentrations reported as mixing ratios. The data was used, with a suite
 of micrometeorology measurements, to simulate bidirectional fluxes of NH3
 above the RMNP forest. The tower is surrounded by lower montane forest,
 comprised of predominantly evergreen needleleaf species, including
 ponderosa pine, juniper, and Douglas fir. There are also groves of quaking
 aspen located in the region.
description: <strong>Biweekly NH3 Measurements</strong>
 Biweekly NH3 ambient air concentration was measured using
 Radiello (https://radiello.com/)
 passive diffusion samplers. The Radiello sampling system includes a
 diffusive body and adsorbing cartridge, which is coated with phosphoric
 acid. NH3 (g) diffuses across the exterior diffusive body and is collected
 on the adsorbing cartridge as ammonium (NH4+) over two weeks. Collected
 ammonia (as NH4+) is extracted from the cartridge into deionized water and
 analyzed using ion chromatography (IC) [Li et al., 2016]. NH3 passive
 samples were collected in duplicate (σ = ±0.25 µg m-3) on top of the NEON
 tower (25.35 m-agl). Passive NH3 sampling methods have been shown to have
 a low bias when compared with other sampling methods, including University
 Research Glassware Denuders and Picarro Cavity Ringdown spectroscopy
 methods [Pan et al., 2020; Puchalski et al., 2011].<br>  
 <strong>Continuous NH3
 Measurements</strong> NH3 (g) air concentration
 was also measured using an ion mobility spectrometer (IMS). Ion mobility
 spectroscopy separates ionized molecules based on their mobility through a
 carrier gas, under the influence of an electric field. The instrument used
 was the AirSentry II Point-of-Use IMS from Particle Measuring Systems
 (Boulder, CO). The instrument was in the National Park Service shelter
 (located at 40.278129, -105.545635) 500 meters north of the NEON site with
 an inlet located approximately 2 m above natural grassland. The sampling
 inlet was ¼” Teflon tubing, heated to 40 C to reduce NH3 loss to the
 sampling tube. Inlet length was kept as short as possible to further
 prevent NH3 loss. Particles were removed by a fiber filter at the tip of
 the inlet. Due to the high altitude of the site location, the instrument
 was zeroed to account for pressure differences upon installation.
 Multi-point calibrations were conducted at the beginning and end of
 sampling. Calibration was confirmed using a known concentration ammonia
 gas sample split between the instrument and a phosphoric acid-coated
 denuder where the NH3 collected by the denuder is extracted into deionized
 water and analyzed using ion chromatography. Zero measurements were made
 periodically by overflowing the inlet with ultra-high purity clean air.
 The AirSentry samples at a 30-second frequency. The limit of detection is
 70 pptv.
description: # Data from: Sensitivity of simulated ammonia fluxes in Rocky Mountain
 National Park to measurement time resolution and meteorological inputs
 [https://doi.org/10.5061/dryad.0cfxpnwcw](https://doi.org/10.5061/dryad.0cfxpnwcw) ## Description of the data and file structure Gas phase ammonia (NH3) measurements were made in Rocky Mountain National Park (RMNP) at the base of Longs Peak. ### Files and variables #### File: RMNP_Passive_NH3_2021_2022.csv **Description:** Biweekly passive NH3 data collected from the NEON tower site located at the base of Longs Peak (40.275903, -105.54596). Site is located at 2750 meters above sea level. Passive NH3 samples were collected in duplicate at two levels on the NEON tower. Tower level is defined by the "Channel" Variable. Passive NH3 samples were made using the Radiello passive NH3 sampling system, which consists of an absorbing cartridge (part number: RAD168), diffuse body (part number: RAD120), and mounting system (part number: RAD 122). Passives were prepared in a NH3-free laminar flow hood (Envirco Corporation) and then sealed for transport. Samples were changed by LN, DP, and AS from 08/23/2021 to 10/11/2021. Samples collected after 10/11/2021 were changed by NEON site operators and shipped to Colorado State University. All samples collected were extracted in deionized water at CSU and analyzed using Ion Chromatography. Passive NH3 is collected as NH4+ on the absorbing cartridge and was analyzed on a cation IC using a 20 mM methanesulfonic acid eluent (0.5 mL min−1 ) on a Dionex CS12A ion exchange column with a CSRS ULTRA II suppressor and Dionex conductivity detector. Values below the detection limit are listed as -8888. ##### Variables * Sampling Code: Sample identification code used for sample collection and processing. Includes site location (RM is for RMNP), date and channel information.  * Channel: Tower level that the sample was mounted on. Channels A and B where mounted at the top of the tower (25.35 meters above ground level). Channels C and D where mounted at 15.6 meters above ground level.  * StartTime (Local Time): Date and time when the sample was installed, in local time. * EndTime (Local time): Date and time when the sample was taken down, in local time. * Elapsed Time (min): Elapsed time of sampling. * NH3 (ppb): Ammonia mixing ratio measured by ion chromatography. #### File: RMNP_AirSentry_NH3_2021_2022.csv **Description:** Continuous NH3 measurements made at a NPS shelter (40.278129, -105.545635) approximately 500 meters north of the NEON tower site. NH3 mixing ratio is collected at 30-second resolution. The limit of detection is 70 pptv (parts per trillion by volume). The instrument used was the AirSentry II Point-of-Use IMS from Particle Measuring Systems (Boulder, CO). The Teflon inlet was heated to avoid surface interactions and fitted with a filter to prevent particles from entering. The instrument inlet was install approximately 1 meter above ground level and kept as short as possible. Values below the detection limit are listed as -8888. ##### Variables * StartTime (Local Time): Time of beginning of sample collection, in local time. * EndTime (Local Time): Time of end of sample collection, in local time. * Ammonia (ppb): NH3 mixing ratio measured by ion mobility spectroscopy