Effects of local meteorology and aerosols on ozone and nitrogen dioxide retrievals from OMI and pandora spectrometers in Maryland, USA during DISCOVER-AQ 2011

An analysis is presented for both ground- and satellite-based retrievals of total column ozone and nitrogen dioxide levels from the Washington, D.C., and Baltimore, Maryland, metropolitan area during the NASA-sponsored July 2011 campaign of Deriving Information on Surface COnditions from Column and VERtically Resolved Observations Relevant to Air Quality (DISCOVER-AQ). Satellite retrievals of total column ozone and nitrogen dioxide from the Ozone Monitoring Instrument (OMI) on the Aura satellite are used, while Pandora spectrometers provide total column ozone and nitrogen dioxide amounts from the ground. We found that OMI and Pandora agree well (residuals within ±25 % for nitrogen dioxide, and ±4.5 % for ozone) for a majority of coincident observations during July 2011. Comparisons with surface nitrogen dioxide from a Teledyne API 200 EU NOx Analyzer showed nitrogen dioxide diurnal variability that was consistent with measurements by Pandora. However, the wide OMI field of view, clouds, and aerosols affected retrievals on certain days, resulting in differences between Pandora and OMI of up to ±65 % for total column nitrogen dioxide, and ±23 % for total column ozone. As expected, significant cloud cover (cloud fraction \u3e0.2) was the most important parameter affecting comparisons of ozone retrievals; however, small, passing cumulus clouds that do not coincide with a high (\u3e0.2) cloud fraction, or low aerosol layers which cause significant backscatter near the ground affected the comparisons of total column nitrogen dioxide retrievals. Our results will impact post-processing satellite retrieval algorithms and quality control procedures

THE IMPACT OF UPPER TROPOSPHERIC DYNAMICS ON SURFACE AIR QUALITY OVER THE UNITED STATES

Monitoring air quality and source attribution at the surface requires a vast understanding of radiative and dynamical effects in the lower atmosphere to capture influential processes affecting human health, the environment, and current pollutant standards. In order to accurately determine all sources impacting lower atmospheric composition, a more thorough comprehension of the dynamical, chemical, and radiative coupling of the stratosphere and troposphere is required. Particularly significant is the transport or exchange of trace gases (i.e. ozone), both natural and anthropogenic, between the stratosphere and troposphere also known as stratosphere-troposphere exchange (STE). During previous research campaigns, STE was found to contribute to the tropospheric ozone budget. In this work, a plan was designed to determine whether or not stratosphere-to-troposphere transport (STT) was a viable mechanism for elevated ozone at the surface, particularly in cases where unhealthy air quality conditions were detected. An investigation of several case studies in which high levels of surface ozone appear to originate from the stratosphere shows that a variety of dynamical processes from the boundary layer to the lower stratosphere are involved. Starting with the quasi-geostrophic equations of vertical and horizontal motion, dynamical parameters can be derived and evaluated from the North American Regional Reanalysis (NARR) meteorological fields. Reanalysis diagnostics, such as Q-vector, can locate the prevailing STT mechanism and capture the extent of vertical transport and mixing into the lower troposphere. Back trajectories from the UMBC-LT model released at the ground sites present additional support for stratospheric contribution to measured ozone levels. Along with the reanalysis dataset, a combination of satellite-retrieved and surface observations of chemical tracers were utilized to demonstrate the plausibility of a stratospheric source and to rule out anthropogenic surface contributions where possible. The practicality of Atmospheric InfraRed Sounder (AIRS), Tropospheric Emission Spectrometer (TES), and HIgh Resolution Dynamics Limb Sounder (HIRDLS) satellite observations to infer stratospheric transport as the probable source was tested for these case studies and the results supported dynamical evidence of STE using tracer correlations, as in the ozone-water vapor relationship. The overall strategy of implementing satellite, reanalysis, and surface measurements together provided strong evidence that unhealthy ozone anomalies at the ground were incurred primarily by STE in these events and setup future studies of resulting ozone signatures

THE IMPACT OF UPPER TROPOSPHERIC DYNAMICS ON SURFACE AIR QUALITY OVER THE UNITED STATES

Monitoring air quality and source attribution at the surface requires a vast understanding of radiative and dynamical effects in the lower atmosphere to capture influential processes affecting human health, the environment, and current pollutant standards. In order to accurately determine all sources impacting lower atmospheric composition, a more thorough comprehension of the dynamical, chemical, and radiative coupling of the stratosphere and troposphere is required. Particularly significant is the transport or exchange of trace gases (i.e. ozone), both natural and anthropogenic, between the stratosphere and troposphere also known as stratosphere-troposphere exchange (STE). During previous research campaigns, STE was found to contribute to the tropospheric ozone budget. In this work, a plan was designed to determine whether or not stratosphere-to-troposphere transport (STT) was a viable mechanism for elevated ozone at the surface, particularly in cases where unhealthy air quality conditions were detected. An investigation of several case studies in which high levels of surface ozone appear to originate from the stratosphere shows that a variety of dynamical processes from the boundary layer to the lower stratosphere are involved. Starting with the quasi-geostrophic equations of vertical and horizontal motion, dynamical parameters can be derived and evaluated from the North American Regional Reanalysis (NARR) meteorological fields. Reanalysis diagnostics, such as Q-vector, can locate the prevailing STT mechanism and capture the extent of vertical transport and mixing into the lower troposphere. Back trajectories from the UMBC-LT model released at the ground sites present additional support for stratospheric contribution to measured ozone levels. Along with the reanalysis dataset, a combination of satellite-retrieved and surface observations of chemical tracers were utilized to demonstrate the plausibility of a stratospheric source and to rule out anthropogenic surface contributions where possible. The practicality of Atmospheric InfraRed Sounder (AIRS), Tropospheric Emission Spectrometer (TES), and HIgh Resolution Dynamics Limb Sounder (HIRDLS) satellite observations to infer stratospheric transport as the probable source was tested for these case studies and the results supported dynamical evidence of STE using tracer correlations, as in the ozone-water vapor relationship. The overall strategy of implementing satellite, reanalysis, and surface measurements together provided strong evidence that unhealthy ozone anomalies at the ground were incurred primarily by STE in these events and setup future studies of resulting ozone signatures

Two Air Quality Regimes in Total Column NO2 Over the Gulf of Mexico in May 2019: Shipboard and Satellite Views

Abstract The Satellite Coastal and Oceanic Atmospheric Pollution Experiment (SCOAPE) cruise in the Gulf of Mexico was conducted in May 2019 by NASA and the Bureau of Ocean Energy Management to determine the feasibility of using satellite data to measure air quality in a region of concentrated oil and natural gas (ONG) operations. SCOAPE addressed both technological and scientific issues related to measuring NO2 columns over the outer continental shelf. Featured were nitrogen dioxide (NO2) instruments (Pandora, Teledyne API analyzer) at Cocodrie, LA (29.26°, −90.66°), and on the Research Vessel Point Sur operating off the Louisiana coast with measurements of ozone, carbon monoxide, and volatile organic compounds (VOCs). The findings: (a) all NO2 observations revealed two atmospheric regimes over the Gulf, the first influenced by tropical air in 10–14 May, the second influenced by flow from urban areas on 15–17 May; (b) comparisons of OMI v4 and TROPOMI v1.3 TC (total column) NO2 data with shipboard Pandora NO2 column observations averaged 13% agreement with the largest difference during 15–17 May (∼20%). At Cocodrie, the satellite–Pandora agreement was ∼5%. (c) Three new‐model Pandora instruments displayed a TC NO2 precision of 0.01 Dobson Units (∼5%); (d) regions of smaller, older natural gas operations showed high methane readings from leakage; elevated VOCs were also detected. Neither satellite nor spectrometer captured the magnitude of ambient NO2 variability near ONG platforms. Given an absence of regular air quality monitoring over the Gulf of Mexico, SCOAPE data constitute a baseline against which future observations can be compared

A Post‐2013 Dropoff in Total Ozone at a Third of Global Ozonesonde Stations: Electrochemical Concentration Cell Instrument Artifacts?

An international effort to improve ozonesonde data quality and to reevaluate historical records has made significant improvements in the accuracy of global network data. However, between 2014 and 2016, ozonesonde total column ozone (TCO; O3) at 14 of 37 regularly reporting stations exhibited a sudden dropoff relative to satellite measurements. The ozonesonde TCO drop is 3–7% compared to satellite and ground‐based TCO, and 5–10% or more compared to satellite stratospheric O3 profiles, compromising the use of recent data for trends, although they remain reliable for other uses. Hardware changes in the ozonesonde instrument are likely a major factor in the O3 dropoff, but no single property of the ozonesonde explains the findings. The bias remains in recent data. Research to understand the dropoff is in progress; this letter is intended as a caution to users of the data. Our findings underscore the importance of regular ozonesonde data evaluation