scholarly journals A Case Study of Stratospheric Ozone Transport to the Northern San Francisco Bay Area and Sacramento Valley during CABOTS 2016

2019 ◽  
Vol 58 (12) ◽  
pp. 2675-2697 ◽  
Author(s):  
Jodie Clark ◽  
Sen Chiao
Keyword(s):  
San Francisco ◽  
Sierra Nevada ◽  
Stratospheric Ozone ◽  
Surface Ozone ◽  
Sacramento Valley ◽  
Surface Sites ◽  
Ozone Data ◽  
Ozone Transport ◽  
Bodega Bay ◽  
Daily Changes

AbstractThe California Baseline Ozone Transport Study (CABOTS) was a major air quality study that collected ozone measurements aloft between mid-May and mid-August of 2016. Aircraft measurements, ground-based lidar measurements, and balloon-borne ozonesondes collected precise upper-air ozone measurements across the central and Southern California valley. Utilizing daily ozonesonde data from Bodega Bay, California, and Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2), reanalysis data for 25 July to 14 August 2016, three stratospheric intrusion events are identified over Northern California influencing air masses above Bodega Bay and Sacramento simultaneously. Calculated percent daily changes in afternoon ozonesonde observations indicate increasing ozone concentrations from the point of likely stratospheric air injection with the arrival of higher potential vorticity, confirmed by ensemble back trajectories. An analysis of the onsite surface monitoring ozone data indicates ozone increases in the observations for dates of plausible low-level stratospheric air influence. Further, a comparison of Bodega Bay surface ozone observations and 14 Sacramento Valley nonattainment zone surface sites show that the surface ozone observed at the higher-elevation surface sites in the lower Sierra Nevada foothills were positively correlated with elevated ozone captured by the ozonesondes within the lowest 0.5–1 km. The strongest correlations observed (~0.61) were between elevated Bodega Bay ozonesonde data and the Placerville (~612 m) afternoon surface ozone data, an indication that these regions separated by 200 km would be influence by the same ozone source. A comparison of daily changes in afternoon ozone show that the two locales often experience similar daily ozone increases or decreases. While this study leads to a basic quantification of stratospheric influence on surface ozone in the Sacramento nonattainment zone, a future campaign that examines ozone and winds aloft at both locales is suggested to improve the quantification of stratospheric ozone.

scholarly journals Summertime free tropospheric ozone pool over the Eastern Mediterranean/Middle East

2013 ◽  
Vol 13 (8) ◽  
pp. 22025-22058 ◽  
Author(s):  
P. Zanis ◽  
P. Hadjinicolaou ◽  
A. Pozzer ◽  
E. Tyrlis ◽  
S. Dafka ◽  
...  
Keyword(s):  
Middle East ◽  
Atmospheric Chemistry ◽  
Tropospheric Ozone ◽  
Eastern Mediterranean ◽  
Stratospheric Ozone ◽  
Surface Ozone ◽  
Eastern Mediterranean Region ◽  
Near Surface ◽  
Ozone Data ◽  
The Mediterranean

Abstract. Observations show that the Mediterranean troposphere is characterized by a marked enhancement in summertime ozone with a maximum over the Eastern Mediterranean. This has been linked to enhanced ozone photochemical production and subsidence under cloud-free anticyclonic conditions. The Eastern Mediterranean region has among the highest levels of background tropospheric ozone around the globe and it can be considered as a global air pollution hotspot. A 12 yr climatological analysis (1998–2009) of free tropospheric ozone was carried out over the region based on ECMWF (European Centre for Medium-Range Weather Forecasts) ERA-interim reanalysis data and simulations with the EMAC (ECHAM5-MESSy for Atmospheric Chemistry) atmospheric chemistry climate model. EMAC is nudged towards the ECMWF analysis data and includes a stratospheric ozone tracer. A characteristic summertime pool with high ozone concentrations is found in the middle troposphere over the Eastern Mediterranean/Middle East (EMME) by ERA-interim ozone data, which is supported by Tropospheric Emission Spectrometer (TES) satellite ozone data and simulations with EMAC. The enhanced ozone over the EMME is a robust feature, propagating down to lower free tropospheric levels. The investigation of ozone in relation to potential vorticity and water vapour and the stratospheric ozone tracer indicates that the dominant mechanism causing the free tropospheric ozone pool is downward transport from the upper troposphere and lower stratosphere associated with the enhanced subsidence and the limited outflow transport that dominates the summertime EMME circulation. The implications of these summertime high free tropospheric ozone values on the seasonal cycle of near surface ozone over the Mediterranean are discussed.

scholarly journals Summertime free-tropospheric ozone pool over the eastern Mediterranean/Middle East

2014 ◽  
Vol 14 (1) ◽  
pp. 115-132 ◽  
Author(s):  
P. Zanis ◽  
P. Hadjinicolaou ◽  
A. Pozzer ◽  
E. Tyrlis ◽  
S. Dafka ◽  
...  
Keyword(s):  
Middle East ◽  
Atmospheric Chemistry ◽  
Tropospheric Ozone ◽  
Eastern Mediterranean ◽  
Stratospheric Ozone ◽  
Surface Ozone ◽  
Ozone Production ◽  
Near Surface ◽  
Ozone Data ◽  
The Mediterranean

Abstract. Observations show that the Mediterranean troposphere is characterized by a marked enhancement in summertime ozone, with a maximum over the eastern Mediterranean. This has been linked to enhanced photochemical ozone production and subsidence under cloud-free anticyclonic conditions. The eastern Mediterranean is among the regions with the highest levels of background tropospheric ozone worldwide. A 12 yr climatological analysis (1998–2009) of free-tropospheric ozone was carried out over the region based on the ECMWF (European Centre for Medium-Range Weather Forecasts) ERA-Interim reanalysis data and simulations with the EMAC (ECHAM5–MESSy) atmospheric chemistry–climate model. EMAC is nudged towards the ECMWF analysis data and includes a stratospheric ozone tracer. A characteristic summertime pool with high ozone concentrations is found in the middle troposphere over the eastern Mediterranean–Middle East (EMME) in the ERA-Interim ozone data, Tropospheric Emission Spectrometer (TES) satellite ozone data and simulations with EMAC. The enhanced ozone over the EMME during summer is a robust feature, extending down to lower free-tropospheric levels. The investigation of ozone in relation to potential vorticity and water vapour and the stratospheric ozone tracer indicates that the dominant mechanism causing the free-tropospheric ozone pool is the downward transport from the upper troposphere and lower stratosphere, in association with the enhanced subsidence and the limited horizontal divergence observed over the region. The implications of these high free-tropospheric ozone levels on the seasonal cycle of near-surface ozone over the Mediterranean are discussed.

scholarly journals Transport analysis of ozone enhancement in Southern Ontario during BAQS-Met

2010 ◽  
Vol 10 (6) ◽  
pp. 15559-15593 ◽  
Author(s):  
H. He ◽  
D. W. Tarasick ◽  
W. K. Hocking ◽  
T. K. Carey-Smith ◽  
Y. Rochon ◽  
...  
Keyword(s):  
Dispersion Model ◽  
Stratospheric Ozone ◽  
Surface Ozone ◽  
Weather Forecast ◽  
Forecast Model ◽  
Atmospheric Infrared Sounder ◽  
Ozone Data ◽  
Geostatistical Interpolation ◽  
Global Environmental ◽  
Weather Forecast Model

Abstract. Twice-daily ozonesondes were launched from Harrow, Ontario (east of Detroit) during the BAQS-Met (Border Air Quality and Meteorology Study) campaign in the summer of 2007. A co-located radar windprofiler measured tropopause height continuously. Simulation results from the dispersion model FLEXPART, using the output of the Environment Canada Global Environmental Multiscale (GEM) weather forecast model, indicate the occurrence of stratospheric ozone intrusion events during the BAQS-Met campaign. This interpretation is supported by the ozonesonde observations, one-minute average surface ozone data measured by the chemistry supersite at Harrow, and geostatistical interpolation results of satellite ozone data that were observed from TES (Tropospheric Emission Spectrometer) onboard NASA's Aura satellite and AIRS (Atmospheric Infrared Sounder) onboard NASA's Aqua satellite. Source-receptor analysis using the GEM-FLEXPART model shows the stratosphere over the Northwest Territories region close to the Beaufort Sea to be the main source of the enhanced ozone at Harrow on 1 July 2007.

Transportation and the Environment

2017 ◽  
Vol 94 (3) ◽  
pp. 37-61
Author(s):  
Douglas R. Littlefield
Keyword(s):  
Nineteenth Century ◽  
San Francisco ◽  
Sierra Nevada ◽  
Mississippi River ◽  
San Joaquin Valley ◽  
Eastern United States ◽  
Major Health ◽  
San Joaquin River ◽  
Natural Wetlands ◽  
Prevailing View

Some histories of California describe nineteenth-century efforts to reclaim the extensive swamplands and shallow lakes in the southern part of California's San Joaquin Valley – then the largest natural wetlands habitat west of the Mississippi River – as a herculean venture to tame a boggy wilderness and turn the region into an agricultural paradise. Yet an 1850s proposition for draining those marshes and lakes primarily was a scheme to improve the state's transportation. Swampland reclamation was a secondary goal. Transport around the time of statehood in 1850 was severely lacking in California. Only a handful of steamboats plied a few of the state's larger rivers, and compared to the eastern United States, roads and railroads were nearly non-existent. Few of these modes of transportation reached into the isolated San Joaquin Valley. As a result, in 1857 the California legislature granted an exclusive franchise to the Tulare Canal and Land Company (sometimes known as the Montgomery franchise, after two of the firm's founders). The company's purpose was to connect navigable canals from the southern San Joaquin Valley to the San Joaquin River, which entered from the Sierra Nevada about half way up the valley. That stream, in turn, joined with San Francisco Bay, and thus the canals would open the entire San Joaquin Valley to world-wide commerce. In exchange for building the canals, the Montgomery franchise could collect tolls for twenty years and sell half the drained swamplands (the other half was to be sold by the state). Land sales were contingent upon the Montgomery franchise reclaiming the marshes. Wetlands in the mid-nineteenth century were not viewed as they are today as fragile wildlife habitats but instead as impediments to advancing American ideals and homesteads across the continent. Moreover, marshy areas were seen as major health menaces, with the prevailing view being that swampy regions’ air carried infectious diseases.

Intercomparison of Odin/SMR ozone measurements with MIPAS and balloon sonde data

2007 ◽  
Vol 85 (11) ◽  
pp. 1111-1123 ◽  
Author(s):  
A Jones ◽  
D Murtagh ◽  
J Urban ◽  
P Eriksson ◽  
J Rösevall
Keyword(s):  
Stratospheric Ozone ◽  
Atmospheric Species ◽  
Ozone Data ◽  
Current Product ◽  
Level 2

The Sub-Millimetre Radiometer (SMR) on board Odin measures various important atmospheric species, including stratospheric ozone. In this study, we compare the three versions (v1.2, v2.0, and v2.1) of level 2 Odin/SMR global stratospheric ozone data to coincident level 2 MIPAS V4.61 and balloon sonde stratospheric ozone data during 2003. The most current product from Odin/SMR (at time of writing), the v2.1, showed the smallest systematic differences when compared to coincident MIPAS and sonde data. Between 17 and 55 km, v2.1 values agreed with MIPAS within 10% (a maximum of 0.42 ppmv), while comparisons to sonde measurements showed an agreement of typically 5–10% between 22 and 35 km (less than 0.5 ppmv below 33 km). Tropical latitudes below 35 km presented the largest absolute systematic differences between v2.1 and sonde coincidences, where Odin/SMR was systematically lower by ~0.9 (more than 10% difference) at approximately 30 km. Comparisons concerning the previous two Odin/SMR versions showed much larger systematic differences, especially at the higher and lower stratospheric altitudes. The main conclusion here is that we suggest that v2.1 of Odin/SMR ozone data should be used for scientific studies. PACS Nos.: 92.60.hd, 95.75.Rs, 95.85.Fm

scholarly journals Transport analysis of ozone enhancement in Southern Ontario during BAQS-Met

2011 ◽  
Vol 11 (6) ◽  
pp. 2569-2583 ◽  
Author(s):  
H. He ◽  
D. W. Tarasick ◽  
W. K. Hocking ◽  
T. K. Carey-Smith ◽  
Y. Rochon ◽  
...  
Keyword(s):  
Air Quality ◽  
Numerical Models ◽  
Stratospheric Ozone ◽  
Weather Prediction ◽  
Surface Ozone ◽  
Air Quality Model ◽  
Quality Model ◽  
Stratospheric Intrusion ◽  
Continuous Surface ◽  
Consistent Picture

Abstract. Twice-daily ozonesondes were launched from Harrow, in southwestern Ontario, Canada, during the BAQS-Met (Border Air Quality and Meteorology Study) field campaign in June and July of 2007. A co-located radar windprofiler measured tropopause height continuously. These data, in combination with continuous surface ozone measurements and geo-statistical interpolation of satellite ozone observations, present a consistent picture and indicate that a number of significant ozone enhancements in the troposphere were observed that were the result of stratospheric intrusion events. The combined observations have also been compared with results from two Environment Canada numerical models, the operational weather prediction model GEM (as input to FLEXPART), and a new version of the regional air quality model AURAMS, in order to examine the ability of these models to accurately represent sporadic cross-tropopause ozone transport events. The models appear to reproduce intrusion events with some skill, implying that GEM dynamics (which also drive AURAMS) are able to represent such events well. There are important differences in the quantitative comparison, however; in particular, the poor vertical resolution of AURAMS around the tropopause causes it to bring down too much ozone in individual intrusions. These campaign results imply that stratospheric intrusions are important to the ozone budget of the mid-latitude troposphere, and appear to be responsible for much of the variability of ozone in the free troposphere. GEM-FLEXPART calculations indicate that stratospheric ozone intrusions contributed significantly to surface ozone on several occasions during the BAQS-Met campaign, and made a moderate but significant contribution to the overall tropospheric ozone budget.

scholarly journals Entrainment and Mixing of Transported Ozone Layers: Implications for Surface Air Quality in the Western U.S.

2020 ◽  
Vol 237 ◽  
pp. 03012
Author(s):  
Christoph Senff ◽  
Andrew Langford ◽  
Raul Alvarez ◽  
Tim Bonin ◽  
Alan Brewer ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
Mixed Layer ◽  
Las Vegas ◽  
Surface Ozone ◽  
Ground Level ◽  
San Joaquin Valley ◽  
Fire Emissions ◽  
Ozone Transport ◽  
The Impact

Recently, two air quality campaigns were conducted in the southwestern United States to study the impact of transported ozone, stratospheric intrusions, and fire emissions on ground-level ozone concentrations. The California Baseline Ozone Transport Study (CABOTS) took place in May – August 2016 covering the central California coast and San Joaquin Valley, and the Fires, Asian, and Stratospheric Transport Las Vegas Ozone Study (FAST-LVOS) was conducted in the greater Las Vegas, Nevada area in May – June 2017. During these studies, nearly 1000 hours of ozone and aerosol profile data were collected with the NOAA TOPAZ lidar. A Doppler wind lidar and a radar wind profiler provided continuous observations of atmospheric turbulence, horizontal winds, and mixed layer height. These measurements allowed us to directly observe the degree to which ozone transport layers aloft were entrained into the boundary layer and to quantify the resulting impact on surface ozone levels. Mixed layer heights in the San Joaquin Valley during CABOTS were generally below 1 km above ground level (AGL), while boundary layer heights in Las Vegas during FAST-LVOS routinely exceeded 3 km AGL and occasionally reached up to 4.5 km AGL. Consequently, boundary layer entrainment was more often observed during FAST-LVOS, while most elevated ozone layers passed untapped over the San Joaquin Valley during CABOTS.

scholarly journals On the role of tropopause folds in summertime tropospheric ozone over the eastern Mediterranean and the Middle East

2016 ◽  
Vol 16 (21) ◽  
pp. 14025-14039 ◽  
Author(s):  
Dimitris Akritidis ◽  
Andrea Pozzer ◽  
Prodromos Zanis ◽  
Evangelos Tyrlis ◽  
Bojan Škerlak ◽  
...  
Keyword(s):  
Middle East ◽  
Atmospheric Chemistry ◽  
Tropospheric Ozone ◽  
Eastern Mediterranean ◽  
Stratospheric Ozone ◽  
Surface Ozone ◽  
Free Troposphere ◽  
Near Surface ◽  
Grid Points ◽  
High Concentrations

Abstract. We study the contribution of tropopause folds in the summertime pool of tropospheric ozone over the eastern Mediterranean and the Middle East (EMME) with the aid of the ECHAM5/MESSy Atmospheric Chemistry (EMAC) model. Tropopause fold events in EMAC simulations were identified with a 3-D labeling algorithm that detects folds at grid points where multiple crossings of the dynamical tropopause are computed. Subsequently the events featuring the largest horizontal and vertical extent were selected for further study. For the selection of these events we identified a significant contribution of the stratospheric ozone reservoir to the high concentrations of ozone in the middle and lower free troposphere over the EMME. A distinct increase of ozone is found over the EMME in the middle troposphere during summer as a result of the fold activity, shifting towards the southeast and decreasing altitude. We find that the interannual variability of near-surface ozone over the eastern Mediterranean (EM) during summer is related to that of both tropopause folds and ozone in the free troposphere.

scholarly journals A model-based analysis of foliar NO<sub><i>x</i></sub> deposition

2020 ◽  
Vol 20 (4) ◽  
pp. 2123-2141 ◽  
Author(s):  
Erin R. Delaria ◽  
Ronald C. Cohen
Keyword(s):  
Sierra Nevada ◽  
Large Fraction ◽  
Surface Ozone ◽  
Nox Reduction ◽  
Soil Water Potential ◽  
Substantial Impact ◽  
Mixing Ratios ◽  
Nitrogen Inputs ◽  
Leaf Level ◽  
The Impact

Abstract. Foliar deposition of NO2 removes a large fraction of the global soil-emitted NOx. Understanding the mechanisms of NOx foliar loss is important for constraining surface ozone, constraining NOx mixing ratios, and assessing the impacts of nitrogen inputs to ecosystems. We have constructed a 1-D multibox model with representations of chemistry and vertical transport to evaluate the impact of leaf-level processes on canopy-scale concentrations, lifetimes, and canopy fluxes of NOx. Our model is able to closely replicate canopy fluxes and above-canopy NOx daytime mixing ratios observed during two field campaigns, one in a western Sierra Nevada pine forest (BEARPEX-2009) and the other in a northern Michigan mixed hardwood forest (UMBS-2012). We present a conceptual argument for the importance of NO2 dry deposition and demonstrate that NO2 deposition can provide a mechanistic explanation for the canopy reduction of NOx. We show that foliar deposition can explain observations suggesting as much as ∼60 % of soil-emitted NOx is removed within forest canopies. Stomatal conductances greater than 0.1 cm s−1 result in modeled canopy reduction factors in the range of those used in global models, reconciling inferences of canopy NOx reduction with leaf-level deposition processes. We show that incorporating parameterizations for vapor pressure deficit and soil water potential has a substantial impact on predicted NO2 deposition in our model, with the percent of soil NOx removed within one canopy increasing by ∼15 % in wet conditions compared to dry conditions. NO2 foliar deposition was also found to have a significant impact on ozone and nitrogen budgets under both high- and low-NOx conditions.

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