Observed and Model-Derived Ozone Production Efficiency over Urban and Rural New York State

Abstract

Abstract:This study examined the model-derived and observed ozone production efficiency (OPE = ∆O x /∆NO z ) in one rural location, Pinnacle State Park (PSP) in Addison, New York (NY), and one urban location, Queens College (QC) in Flushing, NY, in New York State (NYS) during photo-chemically productive hours (11 a.m.-4 p.m. Eastern Standard Time (EST)) in summer 2016. Measurement data and model predictions from National Oceanic and Atmospheric Administration National Air Quality Forecast Capability (NOAA NAQFC)-Community Multiscale Air Quality (CMAQ) model versions 4.6 (v4.6) and 5.0.2 (v5.0.2) were used to assess the OPE at both sites. CMAQ-predicted and observed OPEs were often in poor agreement at PSP and in reasonable agreement at QC, with model-predicted and observed OPEs, ranging from approximately 5-11 and 10-13, respectively, at PSP; and 4-7 and 6-8, respectively, at QC. The observed relationship between OPE and oxides of nitrogen (NO x ) was studied at PSP to examine where the OPE downturn may have occurred. Summer 2016 observations at PSP did not reveal a distinct OPE downturn, but they did indicate that the OPE at PSP remained high (10 or greater) regardless of the [NO x ] level. The observed OPEs at QC were found by using species-specific reactive odd nitrogen (NO y ) instruments and an estimated value for nitrogen dioxide (NO 2 ), since observed OPEs determined using non-specific NO x and NO y instruments yielded observed OPE results that (1) varied from approximately 11-25, (2) sometimes had negative [NO z ] concentrations, and (3) were inconsistent with CMAQ-predicted OPE. This difference in observed OPEs at QC depending on the suite of instruments used suggests that species-specific NO x and NO y instruments may be needed to obtain reliable urban OPEs.

Ozone Production Efficiencies at Rural New York State Locations: Relationship to Oxides of Nitrogen Concentrations

“…This reasonable agreement between the two OPE estimates suggests that analyzing observed OPEs over longer time periods is a good approach for PSP, as long as proper filter criteria are specified (Ninneman et al, ). Proper data filters are needed to ensure that (1) only more homogeneous meteorological conditions characterized by high temperatures and sunlit conditions are considered and (2) r 2 values are approximately 0.4 or higher (Ninneman et al, ). Overall, due to the reasonable agreement between the median summertime and daily OPEs at PSP, further discussion will focus on the summertime OPE results.…”

“…Nevertheless, when all 13 summers were considered, the median daily OPE was only 24% larger than the median summertime OPE at PSP, with values of 8.36 and 6.76 ppb ppb −1 , respectively (Table S3). This reasonable agreement between the two OPE estimates suggests that analyzing observed OPEs over longer time periods is a good approach for PSP, as long as proper filter criteria are specified (Ninneman et al, 2017). Proper data filters are needed to ensure that (1) only more homogeneous meteorological conditions characterized by high temperatures and sunlit conditions are considered and (2) r 2 values are approximately 0.4 or higher (Ninneman et al, 2017).…”

“…For the rest of the data set, the OPE at PSP was first estimated on a yearly basis. These OPEs will henceforth be called “summertime OPEs.” As was done in Ninneman et al (), two meteorological filters were applied to only examine instances where photochemistry was an important process controlling the OPE estimates. First, times where observed temperatures were less than 20 °C were neglected.…”

“…In addition, the OPE at PSP was analyzed on a daily basis for the 13 summers. These OPEs will henceforth be called “daily OPEs.” Daily OPEs were estimated because of the possibility of the summertime slopes of O 3 versus NO z being taken over data from heterogeneous meteorological and chemical conditions, despite the filters applied (Ninneman et al, ). If this occurred, then the summertime OPEs at PSP may not be representative of the true OPE at the site.…”

“…However, it is noteworthy that the variability in the median daily OPE from 2012 to 2017 (excluding 2013) was quite large, with 25th and 75th percentile values of −3.81 and 21.41 ppb ppb −1 , respectively ( Figure S13). Such large variability may have been due to measurement difficulties at lower [NO x ] and [NO y ] concentrations, additional meteorological and chemical processes (e.g., dry deposition of O 3 or NO y ) that were beyond the scope of this study, or a combination of the two (Ninneman et al, 2017). Nevertheless, when all 13 summers were considered, the median daily OPE was only 24% larger than the median summertime OPE at PSP, with values of 8.36 and 6.76 ppb ppb −1 , respectively (Table S3).…”