OCS Study

BOEM 2020-046

U.S. Department of the Interior

Bureau of Ocean Energy Management

Sterling, VA

NASA Resources to Monitor Offshore

and Coastal Air Quality
OCS Study

BOEM 2020-046

U.S. Department of the Interior

Bureau of Ocean Energy Management

Sterling, VA

NASA Resources to Monitor Offshore 

and Coastal Air Quality

December 2020

Authors:

Dr. Bryan N. Duncan

Prepared under Interagency Agreement M17PG00026

By:

National Aeronautics and Space Administration (NASA)

NASA Goddard Space Flight Center

8800 Greenbelt Road

Greenbelt, MD 20771
DISCLAIMER

This study was funded, in part, by the U.S. Department of the Interior, Bureau of Ocean Energy 

Management (BOEM), Environmental Studies Program, Washington, DC, through Interagency 

Agreement Number M17PG00026 with the U.S. National Aeronautics and Space 

Administration (NASA). This report has been technically reviewed by BOEM, and it has been 

approved for publication. The views and conclusions contained in this document are those of 

the authors and should not be interpreted as representing the opinions or policies of the U.S.

Government, nor does mention of trade names or commercial products constitute endorsement 

or recommendation for use.

REPORT AVAILABILITY

To download a PDF file of this report, go to the U.S. Department of the Interior, Bureau of 

Ocean Energy Management Data and Information Systems webpage

(http://www.boem.gov/Environmental-Studies-EnvData/), click on the link for the Environmental 

Studies Program Information System (ESPIS), and search on 2020-046. The report is also 

available at the National Technical Reports Library at https://ntrl.ntis.gov/NTRL/.

CITATION

Duncan BN. 2020. NASA resources to monitor offshore and coastal air quality. Sterling (VA):

U.S. Department of the Interior, Bureau of Ocean Energy Management. OCS Study BOEM 

2020-046. 32 p.

ABOUT THE COVER

The SCOAPE logo was designed by Russell Yerkes, Visual Information Specialist, BOEM.

ACKNOWLEDGMENTS

This work was funded by the U.S. Department of the Interior, Bureau of Ocean Energy 

Management (BOEM) with additional funds provided by the U.S. National Aeronautics and 

Space Administration (NASA) Applied Sciences Program. BOEM donated the time of two 

additional personnel to participate in the SCOAPE field campaign in May 2019. The Royal 

Dutch Meteorological Office (KNMI) also donated the time of one employee to participate in the 

field campaign.
ABSTRACT

In this report, we present the suite of National Aeronautics and Space Administration (NASA)

datasets and tools, which are free and publicly available, that will enable Bureau of Ocean 

Energy Management (BOEM) personnel to monitor air pollution offshore and along coastal 

environments of the continental U.S. We provide three case studies to demonstrate the current 

capabilities of these resources in the Gulf of Mexico region and discuss how they may be 

integrated into BOEM’s standard operating procedure (SOP) for assessing offshore air quality.

In addition, we make three high-level recommendations to BOEM:

1) We recommend that BOEM adopts an integrated approach to monitoring air quality (AQ)

that combines the strengths of various monitoring technologies, including regulatorygrade AQ monitors and non-traditional sources of AQ data: satellite data, AQ models,

low-cost portable sensors, in situ monitors, and other ancillary datasets. As a first step, 

we recommend that BOEM personnel take advantage of the NASA Applied Remote 

SEnsing Training (ARSET) and Health and Air Quality Applied Sciences Team 

(HAQAST) programs to explore NASA’s free and publicly available resources, so that 

BOEM personnel may identify the potential of these resources for BOEM’s various 

applications and to begin integrating them into BOEM’s SOP. Most of these resources 

are easily accessed via webtools, though accessing, processing, and analyzing satellite 

data (beyond visualization with webtools) will require more effort on the part of BOEM 

personnel.

2) We recommend that BOEM personnel continue to interact with NASA personnel, and 

potentially personnel from the U.S. Environmental Protection Agency (EPA) and National 

Oceanic and Atmospheric Administration (NOAA), to identify mutually beneficial 

collaborations that will advance BOEM’s goals to monitor AQ in U.S. offshore and 

coastal waters. Several potential examples of these collaborations are given (e.g., field 

campaigns to measure air pollution).

3) We recommend that BOEM personnel continue to work with NASA personnel to 

understand the relation between quantities observed from space and pollutant 

concentrations within the boundary layer, including offshore and along the coast. In a 

companion report (i.e., Thompson, 2020), we show that pollutant concentrations can 

have complex 3-d distributions offshore (e.g., from the vertical structure of pollutant 

emissions) and in coastal environments (e.g., from complex sea breezes). BOEM 

personnel would benefit from working with NASA personnel, who have developed the 

NASA data and simulated products and, therefore, know their strengths and limitations 

for BOEM’s applications, as well as how to avoid common mistakes when analyzing 

them.
i

Contents

List of Figures................................................................................................................................................ ii

List of Abbreviations and Acronyms............................................................................................................. iv

1 Introduction ...........................................................................................................................................1

2 Capacity Building: Tools for BOEM’s “Toolbox”....................................................................................1

2.1 Satellite Data for AQ Applications.................................................................................................2

2.1.1 How Do Satellite Data of Air Pollutants Translate to Surface Concentrations and 

Emissions?............................................................................................................................................5

2.1.2 Relevant New and Upcoming Satellite Capabilities..............................................................6

2.1.3 NASA Tutorials on Satellite Data ..........................................................................................7

2.2 In Situ Observations and Other Ancillary Datasets.......................................................................8

2.3 NASA AQ Forecasts ...................................................................................................................10

2.4 The Potential of Low-Cost Sensors.............................................................................................13

2.5 Illustrative Case Studies..............................................................................................................16

2.5.1 Case #1: Offshore Flow (September 5, 2019) ....................................................................19

2.5.2 Case #2: Onshore Flow (September 11, 2019) ..................................................................23

2.5.3 Case #3: Pollution from Outside GoM (May 13, 2019).......................................................27

3 Summary and High-level Recommendations to BOEM......................................................................30

4 References..........................................................................................................................................31
ii

List of Figures

Figure 1. An integrated approach for AQ monitoring. ..................................................................................2

Figure 2. Tropospheric column nitrogen dioxide (TropC NO2) vertical column density (VCD; x1015

molecules/cm2) data from the NASA Aura Ozone Monitoring Instrument (OMI), as annual averages for 

(top) 2005 and (bottom) 2019. ......................................................................................................................4

Figure 3. OMI TropC NO2 vertical column density (VCD; x1015 molecules/cm2) in (top) 2005 and (middle) 

2019 with the (bottom) absolute difference between 2019 and 2005...........................................................5

Figure 4. Diagram depicting various surface AQ instruments in relation to the TROPOMI pixel size.........6

Figure 5. Pandora instruments on the roof of the LUMCON building in Cocodrie, LA, in May 2019...........9

Figure 6. The dedicated SCOAPE domain on FLUID................................................................................11

Figure 7. Example of pollutants at various points that may be plotted with FLUID....................................11

Figure 8. An example of spatial maps of pollutants, including tracers of various sources. .......................12

Figure 9. Example of a tailored local forecast using machine learning (ML) applied to the NASA AQ 

modeled concentrations of O3.....................................................................................................................13

Figure 10. The low-cost NO2 sensor has been deployed in numerous photochemical environments and 

on various platforms (e.g., mobile, tethered balloon, drone) around the world. .........................................14

Figure 11. Same as the previous figure, except this figure shows data collected along a path from 

Cocodrie to Burns Point State Park, LA......................................................................................................15

Figure 12. Demonstrating its capabilities, the low-cost NO2 sensor observed a wide range of levels, from 

relatively clean to highly polluted, along the path from Cocodrie to Burns Point State Park, LA, on May 15, 

2019. ...........................................................................................................................................................15

Figure 13. NOAA Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) back trajectories 

initiated every hour at Cocodrie, LA, for April and May 2019. ....................................................................16

Figure 14. TROPOMI TropC NO2 (VCD) on a day (i.e., Case #1) with offshore flow near the surface from 

Louisiana, Mississippi, and Alabama and weak onshore flow in East Texas (left) and relatively stronger 

onshore flow (i.e., Case #2) for the same area (right). ...............................................................................17

Figure 15. May cloud climatology: ERA-Interim Reanalysis averaged total cloud fraction for May, from 

1979–2014. .................................................................................................................................................18

Figure 16. Wind speed and direction from the NASA AQ model and backward trajectories from the NOAA 

HYSPLIT model on September 5, 2019......................................................................................................19

Figure 17. Simulations of concentrations for CO (top), NO2 (middle), and O3 (bottom) from the AQ model 

accessed via FLUID....................................................................................................................................20

Figure 18. NASA Terra/Aqua MODerate resolution Imaging Spectrometer (MODIS) True Color Imagery 

of the GoM at midday on September 5, 2019.............................................................................................21

Figure 19. TROPOMI (left) TropC NO2 VCDs (x1015 molecules/cm2) and (right) TC CO VCDs (x1018

molecules/cm2) on September 5, 2019.......................................................................................................21

Figure 20. NASA Terra Measurement of Pollution in the Troposphere (MOPITT). ...................................22
iii

Figure 21. Onshore flow near the surface over the Louisiana coast on September 11, 2019...................23

Figure 22. Simulated concentrations of CO (top), NO2 (middle), and O3 (bottom) accessed via FLUID...24

Figure 23. MODIS True Color Imagery of the GoM at midday on September 11, 2019............................25

Figure 24. Though much of the western part of the GoM has missing TROPOMI data because of clouds 

(Figure 23), there are generally higher CO VCDs in the eastern part of the GoM than the western part..25

Figure 25. Flare event was detected by a satellite on September 11, 2019..............................................26

Figure 26. MODIS True Color Imagery illustrates the widespread smoke from agricultural fires (red dots 

indicate detected fires) that polluted the GoM. ...........................................................................................27

Figure 27. Aerosol optical depth (AOD) is an indicator of the concentration of the smoke with the warmest 

colors being the highest concentrations......................................................................................................27

Figure 28. TROPOMI shows that high levels of CO were transported from Mexico into the GoM............28

Figure 29. The AQ forecast simulates the northeastward transport of smoke from Mexican agricultural 

fires..............................................................................................................................................................28

Figure 30. The AQ forecast predicts high levels of organic carbon (OC) and BC associated with the fires 

early in the forecast period over Cocodrie, LA, but a cold front moved south off the coast clearing out the 

smoke..........................................................................................................................................................29

Figure 31. The smoke was predicted to impact offshore for a longer period, such as at the Atlantis 

platform. ......................................................................................................................................................29

Figure 32. A clear increase in elevated O3 and BC concentrations from trajectories originating over the 

Yucatan peninsula, where agricultural burning was occurring....................................................................30
iv

List of Abbreviations and Acronyms

Acronym/Name Phrase/Description

Chemical Species

AOD 

CH4

CO 

HCHO 

NO2

NOx

O3

PM, PM2.5 

SO2

VOC

Aerosol Optical Depth

Methane

Carbon Monoxide

Formaldehyde, a VOC

Nitrogen Dioxide

Nitrogen Oxides (NOx = NO + NO2)

Ozone

Particulate Matter, < 2.5 μm in size

Sulfur Dioxide

Volatile Organic Compound

Instruments

MOPITT

MODIS 

OMI 

TEMPO 

TROPOMI 

VIIRS 

Measurement of Pollution in the Troposphere

MODerate resolution Imaging Spectrometer

Ozone Monitoring Instrument

Tropospheric Emissions: Monitoring of Pollution

TROPOspheric Monitoring Instrument

Visible Infrared Imaging Radiometer Suite

Agencies/Programs

ARSET

BOEM 

EPA 

ESA 

HAQAST 

KNMI

NASA

NOAA

NASA Applied Remote SEnsing Training

Bureau of Ocean Energy Management

Environmental Protection Agency 

European Space Agency

NASA Health and Air Quality Applied Sciences Team

Royal Dutch Meteorological Office

National Aeronautics and Space Administration

National Oceanic and Atmospheric Administration

Other

AQ 

AQS

CEMS 

CONUS 

GoM 

HYSPLIT

LOOP

ONG 

SCOAPE 

SOP

TC NO2

TropC NO2

VCD

Air Quality

U.S. Air Quality System

Continuous Emission Monitoring System

CONtinental United States

Gulf of Mexico

NOAA Hybrid Single Particle Lagrangian Integrated Trajectory Model

Louisiana Offshore Oil Port

Oil and Natural Gas

Satellite Coastal & Oceanic Atmospheric Pollution Experiment

Standard Operating Procedure

Total Column NO2 = atmospheric column

Tropospheric Column NO2 = tropospheric column

Vertical Column Density = the total number of molecules between the 

satellite and Earth’s surface per unit area, such as molecules/cm2.
1

1 Introduction

The Outer Continental Shelf Lands Act (OCSLA) requires the Bureau of Ocean Energy 

Management (BOEM) to ensure compliance with the National Ambient Air Quality Standard 

(NAAQS) so that Outer Continental Shelf (OCS) oil and gas exploration, development, and 

production do not significantly impact the air quality (AQ) of any state. In July 2015, BOEM 

personnel first approached the National Aeronautics and Space Administration (NASA) to inquire

if satellite data could be used to help monitor offshore AQ in BOEM’s jurisdiction, that portion of 

the OCS west of 87°30’ West longitude in the Gulf of Mexico (GoM) Region and the Chukchi and 

Beaufort Sea Planning Areas in the Alaska Region. An interagency agreement was signed in 

2017 to begin a study, which was named the Satellite Coastal and Oceanic Atmospheric Pollution 

Experiment (SCOAPE). 

The ultimate goal of SCOAPE is to enable BOEM personnel, through the use of a suite of NASA 

and non-NASA resources (e.g., satellite data, in situ observations, and AQ forecasts), to assess

how pollutants from offshore oil and natural gas (ONG) exploration, development, and production 

activities affect AQ on land. That is, we present a cost-effective and integrated approach to air 

pollution monitoring. To this end, this document provides an overview of NASA resources and 

demonstrates their potential, including through case studies.

As we demonstrate in Section 2, NASA resources have the potential to advance BOEM’s goal to 

monitor the impact of air pollution from offshore oil and gas sources in the GoM on onshore AQ; 

this is also likely the case for coastal waters in all of the continental U.S. (CONUS). However, 

observing air pollution with satellites in BOEM’s Arctic jurisdiction is currently challenging as 

discussed in a recent review article led by Duncan (see Sections 5.1 and 5.2 of Duncan et al., 

2020 for details). Therefore, the focus of this report is on the GoM Region.

As we demonstrate in a companion document (Thompson, 2020), satellite data of nitrogen dioxide 

(NO2), a product of fossil fuel combustion, correlate well with surface and in situ observations, 

including from the SCOAPE field campaign in May 2019 in the GoM, supporting that satellite data 

may be used to monitor offshore AQ.

We make recommendations throughout the report and provide a high-level summary of our 

recommendations in Section 3.

2 Capacity Building: Tools for BOEM’s “Toolbox”

Point of Contact: Bryan Duncan (Bryan.N.Duncan@nasa.gov)

⇒ Recommendation to BOEM: In this section, we present the suite of NASA datasets and tools, 

which are free and publicly available, that would enable BOEM personnel to monitor offshore air

pollution. Rather than relying on one monitoring technology, we recommend a cost-effective and

integrated approach to air pollution monitoring, which includes satellites (Section 2.1), in situ 

instruments and other ancillary datasets (Section 2.2), AQ models (Section 2.3), and low-cost 

portable sensors (Section 2.4), and that combines the strengths of these monitoring technologies

(Figure 1). In Section 2.5, we provide three case studies to demonstrate the current capabilities 

of these resources and discuss how they may be integrated into BOEM’s standard operating 

procedure (SOP).
2

Figure 1. An integrated approach for AQ monitoring.

Source: Cromar et al., 2019

2.1 Satellite Data for AQ Applications

⇒ Recommendation to BOEM: This section is meant to be a brief overview of satellite data for 

AQ applications. For a more in depth overview, the reader is referred to Duncan et al. (2014) and 

the webpage, Air Pollution: Observations from Space (https://airquality.gsfc.nasa.gov), which is 

maintained by Duncan. The latter source is updated regularly and will serve as a resource for 

BOEM of new developments in using satellite data to monitor AQ.

The major pollutants that can be measured from space are nitrogen dioxide (NO2), sulfur dioxide 

(SO2), carbon monoxide (CO), formaldehyde (HCHO), and aerosol optical depth (AOD), from 

which surface particulate matter (PM) may be inferred. NO2 is reliably detected from space and 

serves as an excellent tracer of fossil fuel combustion. With today’s technology, it is not currently 

feasible to monitor surface levels of ozone (O3) from space, though it is possible to observe the 

precursors to O3: a component of NOx (i.e., NO2) and volatile organic carbons (VOCs; i.e., 

HCHO—an oxidation product of many VOCs). However, the HCHO data product has large 

uncertainties associated with it, especially over the ocean where its emission sources are low. 

SO2 also has large uncertainties, especially because its concentrations are low in the GoM due 

to emissions controls. Large emissions of SO2 associated with Mexican-operated ONG activities 

in the GoM are easily detected from space (Zhang et al., 2019). 

AQ managers take advantage of the primary strength of satellite instruments over typical groundbased monitoring networks of instruments—spatial coverage (Figure 2). For example, the 

efficacy of environmental controls to improve U.S. air pollution over land is clearly demonstrated 

by satellite data of multiple pollutants: NO2, SO2, and PM. From 2005 to 2018, there has been a 

20–60% decrease in NO2 over polluted areas of the U.S. (Figure 2; Duncan et al., 2016). Visit 

https://airquality.gsfc.nasa.gov for images, animations, and general information of how satellite 

data have been used to monitor trends in major air pollutants.

Figure 3 is the same as Figure 2, but zooms in the GoM. ⇒ Relevance to BOEM: The top and 

middle panels illustrate that offshore NO2 levels are only a fraction of the magnitude of onshore 
3

levels. The bottom panel also shows that NO2 levels over land (e.g., Houston, New Orleans) 

decreased dramatically (20–60%) between 2005 and 2019 as shown in Figure 2. Levels over 

open waters along the U.S. coast of the GoM decreased significantly as well, especially near 

large onshore sources, indicating that large decreases in onshore NO2 levels likely resulted in 

relatively large decreases over open water from 2005 to 2019. That is, onshore sources for 

some pollutants likely contributed significantly to offshore levels on average, especially during 

meteorological conditions of offshore flow as discussed in Section 2.5.

The satellite data products, which are free and publicly available, are primarily collected by 

instruments on satellites operated by NASA, the National Oceanic and Atmospheric 

Administration (NOAA), the European Space Agency (ESA), and the space agencies of some 

individual countries (e.g., Korea, Japan). Atmospheric composition satellite data have proven 

valuable to the AQ community for a number of applications (Duncan et al., 2014), such as the 

following:

• Estimating ozone (O3) and aerosol precursor emissions;

• Monitoring events (e.g., wildfires);

• Monitoring regional long-term trends in ozone (O3) and PM precursors;

• Validating AQ models;

• Tracking long-range transport of pollution.

⇒ Relevance to BOEM: Although satellite data for AQ applications have been evaluated over a 

range of land environments (e.g., urban to rural; tropical to high latitude), there has been little 

evaluation thus far over open ocean and coastal waters.
4

Figure 2. Tropospheric column nitrogen dioxide (TropC NO2) vertical column density (VCD; x1015

molecules/cm2) data from the NASA Aura Ozone Monitoring Instrument (OMI), as annual averages for 

(top) 2005 and (bottom) 2019.

Source: NASA Science Visualization Studio (SVS).
5

Figure 3. OMI TropC NO2 vertical column density (VCD; x1015 molecules/cm2) in (top) 2005 and (middle) 

2019 with the (bottom) absolute difference between 2019 and 2005.

Source: Lok Lamsal (NASA).

2.1.1 How Do Satellite Data of Air Pollutants Translate to Surface Concentrations and 

Emissions?

Most satellite instruments that collect data relevant for AQ applications are spectrometers that 

detect electromagnetic (EM) radiation from the sun. The incoming radiation, which is absorbed, 

re-emitted, reflected, and scattered by the Earth and its atmosphere, is measured as a function 

of wavelength with the infrared (IR), visible, and ultraviolet (UV) regions of the EM spectrum 

containing the most useful information for observing pollutants from space. Satellite-observed 

pollutants, either gases or aerosols, absorb IR wavelengths (e.g., CO) or scatter visible and UV 

wavelengths (e.g., NO2). Unlike remote sensing of aerosols that use the signature of aerosol 

scattering, remote sensing of trace gases uses the signature of gas absorption at distinct 

absorption spectra. By knowing how and by what amount different molecules absorb radiation at 

different wavelengths, we can identify a "fingerprint" for each atmospheric constituent and 

estimate physical measurements (such as number density, partial pressure, column amount) of 

the different gases (i.e., NO2, SO2, etc.) with limited information on the vertical structure of the 

pollutant in the atmosphere. The accuracy of the measurements will vary with meteorology, 

chemistry, polluted versus non-polluted regions, and exceptional events.
6

Satellite vertical column densities (VCD) can provide observations of the spatial variability of air 

pollutants, such as NO2, on daily, monthly, and yearly time scales (depending on the satellite 

instrument and product), with the benefit of spatial coverage over most ground-based monitoring 

networks that measure "nose-level" surface concentrations. For example, in polluted 

environments, trends in the total column NO2 can be a proxy for trends in surface NOx as most of 

the column resides near the surface. Figure 4 shows an example of the down-looking satellite 

instrument, the ESA TROPOspheric Ozone Monitoring Instrument (TROPOMI), and its 

observable, (VCD), and its relation to "nose-level" surface concentrations. (A VCD equals the total 

number of molecules between the satellite and Earth’s surface per unit area, such as 

molecules/cm2.)

To infer "nose-level" concentrations from satellite data, an atmospheric model can be used, which 

takes into account the vertical distribution of the pollutant within the total column. For a deeper 

discussion, the reader is referred to the overview article, which is written in plain language, of 

Duncan et al. (2014). The article provides an overview of how satellite data of air pollutants are 

being used by the AQ community, giving examples of applications, a summary of end-user 

resources, and answers many frequently asked questions. 

Figure 4. Diagram depicting various surface AQ instruments in relation to the TROPOMI pixel size. 

Notes: 1. The Pandora instrument has similar capabilities as the satellite instruments, OMI and TROPOMI, which 

observe NO2, HCHO, and SO2. Therefore, Pandora instruments are deployed for satellite validation purposes. 2. The 

in situ instrument, such as those used by EPA, monitor surface level pollutant concentrations. 3. Tropospheric Ozone 

Lidar Network (TOLNET) observes the vertical structure of ozone within the troposphere. 4. The ceilometer is an 

instrument that measures the height of clouds and aerosol layers. 5. The TROPOMI satellite. Source: Alexander 

Kotsakis of the NASA Pandora effort. 

2.1.2 Relevant New and Upcoming Satellite Capabilities

Several new satellite instruments, that were recently launched or are nearing launch, promise to 

provide much better data, including over the ocean, on air pollutants than can be obtained from 

current satellites.
7

• Higher Spatial Resolution: The ESA TROPOspheric Monitoring Instrument (TROPOMI; 

launched in 2017) collects data on NO2, SO2, CO, and methane (CH4) at sub-urban spatial 

resolutions (e.g., a few kilometers) and at resolutions much finer than current instruments. 

TROPOMI has many superior capabilities to its predecessor, OMI, such as finer spatial 

resolution and better signal-to-noise. ⇒ Things to Know: The TROPOMI data products are 

still being refined. A new release is anticipated by the end of 2020, which will address 

several shortcomings of the current products.

• Higher Temporal Resolution: A satellite in geosynchronous orbit will appear to remain 

in a fixed location in the sky relative to an observer on the ground. Currently, there are 

several satellites (e.g., NOAA GOES-R) in geosynchronous orbits that provide information 

on aerosols. A satellite in geosynchronous orbit is planned to observe NO2, SO2, CO, and 

CH4 over North America (NASA Tropospheric Emissions: Monitoring Pollution, TEMPO) 

with a planned launch date in 2022. TEMPO is an instrument that will have similar 

capabilities as OMI.

These new capabilities are/will improve BOEM’s ability to monitor air pollution, infer surface 

concentrations of air pollutants, and constrain pollutant emissions from satellite data. 

2.1.3 NASA Tutorials on Satellite Data

NASA’s Applied Sciences Program (ASP) promotes innovation in public and private sector 

organizations to apply NASA satellite data, model products, and scientific findings in AQ 

management and policy activities that benefit human health and safety. To this end, ASP supports 

several capacity building programs, which will benefit BOEM’s mission by educating BOEM 

personnel on what satellite data are available and how to access and process the data. 

⇒ Recommendation to BOEM: We highly encourage BOEM personnel take advantage of two free 

NASA programs:

• NASA ARSET: The complexity of accessing, processing, and properly interpreting satellite 

products is often difficult for end-users without the technical skill required. NASA’s Applied 

Remote SEnsing Training (ARSET) program (https://arset.gsfc.nasa.gov) offers satellite 

remote sensing training that builds the skills to integrate NASA Earth Science data into an 

agency’s decision-making activities, including AQ monitoring. They provide lessons on 

pertinent basics of pollutant detection and products and give a tour of NASA’s satellite 

data products and some applications (i.e., what is available/applicable for AQ studies).

• NASA HAQAST: The NASA Health and AQ Applied Sciences Team (HAQAST; 

https://haqast.org) members work directly with stakeholders to facilitate the use of NASA 

resources for their applications. (Duncan, a HAQAST member, leveraged his NASA 

HAQAST funding to work with BOEM on SCOAPE.) In addition, HAQAST members 

develop review articles and how-to materials for end-users. For example, Streets et al. 

(2013) reviewed the use of satellite data to inform about the distributions of pollutants and 

pollutant emissions for AQ applications. Duncan et al. (2014) described in more detail the 

helpful resources available for viewing satellite observations, including guidance on web 

tools for visualizations and sample applications. 

We recommend the following HAQAST and ARSET tutorials for BOEM personnel to begin 

discovering NASA resources:
8

HAQAST

Points of Contact: HAQAST is currently being recompeted, though Tracey Holloway 

(taholloway@wisc.edu) is the current lead and Duncan is a current

HAQAST member.

Introductory

• Upgrading the Toolbox: NASA Resources to Support Air Quality Management

• Visualizing Air Quality: How to Use NASA’s Giovanni to Plot Satellite Tropospheric NO2

Columns

ARSET

Point of Contact: Ana Prados (aprados@umbc.edu)

Introductory

• An Inside Look at how NASA Measures Air Pollution

• Introduction to Satellite Remote Sensing for Air Quality Applications

• Application of Satellite Observations for Air Quality and Health Exposure

• Satellite Remote Sensing of Dust, Fires, Smoke, and Air Quality

Advanced (TEMPO (not yet launched), TROPOMI)

• High Temporal Resolution Air Quality Observations from Space

• Advanced Webinar: High Resolution NO2 Monitoring from Space with TROPOMI

⇒ Recommendation to BOEM: Assign several BOEM employees with differing skill sets to view 

the above webinars to gain a more comprehensive overview of NASA resources than presented 

in this report. These webinars would enable BOEM personnel to identify which resources may be 

brought to bear on particular BOEM applications. 

⇒ Recommendation to BOEM: Accessing, processing, and properly interpreting satellite data 

require BOEM personnel to invest time in acquiring the necessary skills. Of course, the 

necessary skills ultimately depend on BOEM’s desired applications. For instance, tracking 

pollution requires minimal investment as demonstrated by the illustrative case studies in 

Section 2.5 and could easily be done by one person part time. However, using satellite data to 

infer emission source strengths (e.g., from individual platforms) requires a more sophisticated 

data user. Therefore, it is recommended that BOEM management clearly identifies specific 

desired applications and works with NASA personnel to design the best strategy for achieving 

these goals.

2.2 In Situ Observations and Other Ancillary Datasets

Point of Contact: Bryan Duncan (Bryan.N.Duncan@nasa.gov)

In situ instruments on board various platforms (e.g., stationary, ship, aircraft) and other ancillary 

datasets are necessary to independently validate and interpret satellite data, such as for 

understanding the correspondence of the quantity observed by a satellite and the observation at 

the surface (e.g., from an AQ monitor). Here are some of the techniques:

• Ground-based remote sensing instruments: As illustrated in Figure 4, column data from 

satellites may be compared to similar ground-based instruments. For example, the 

portable Pandora instrument (Figure 5) is used to evaluate the magnitude, variations and 
9

trends of OMI and TROPOMI data. However, there are issues of 1) "representativeness" 

of a small Pandora footprint to the large footprint of a satellite (e.g., Kim et al., 2016; Judd 

et al., 2019) and 2) comparing data from a satellite that looks down to a ground instrument 

that tracks the sun’s movement throughout the day (Figure 4). Nevertheless, the satellite 

data generally compare well, except under polluted conditions (e.g., in urban areas), with 

differences of 20% or less to the Pandora data under partially cloudy to clear weather 

conditions. 

⇒ Recommendation to BOEM: We recommend that BOEM contact Tom Hanisco (NASA; 

thomas.hanisco@nasa.gov), the Pandora PI, to discuss the possibility of Pandora 

instruments becoming part of BOEM’s integrated observing strategy. For example, a 

Pandora instrument placed next to an in situ monitor in a coastal location would facilitate 

understanding of the relationship between the total column (TC) NO2 and NO2 surface 

concentration. ⇒ Things to Know: There could be potential issues of siting Pandoras in 

coastal environments because of high humidity and salt air.

⇒ Recommendation to BOEM: As part of a feasibility study, EPA has sited several 

Pandora instruments next to EPA surface AQ monitors in the northeast U.S. We 

recommend that BOEM personnel contact Luke Valin (EPA; Valin.Lukas@epa.gov) to 

discuss their findings, which may provide BOEM guidance on the utility of having Pandora 

instruments sited near in situ monitors along the coast of BOEM’s GoM domain.

Figure 5. Pandora instruments on the roof of the LUMCON building in Cocodrie, LA, in May 2019. 

Image courtesy of Duncan.

• Airborne remote sensing instruments: There are other OMI-like sensors (e.g., 

GEOstationary Coastal and Air Pollution Events (GEO-CAPE) Airborne Simulator 

(GCAS); Nowlan et al., 2018), in addition to Pandora, that NASA regularly deploys on 

aircraft. These sensors may be useful for BOEM, such as mapping NO2 concentrations in 

the GoM. 

⇒ Recommendation to BOEM: We recommend that BOEM personnel contact NASA 

personnel (Barry Lefer; barry.lefer@nasa.gov; NASA HQ) about the possibility of mutually

beneficial deployments. For instance, we recommend that BOEM remain in contact with 

Bill Swartz (Johns Hopkins University Applied Physics Lab; bill.swartz@jhuapl.edu), to 

continue discussion (telecon on January 1, 2020) of the possible collaboration of BOEM 

with the NASA Compact Hyperspectral Air Pollution Sensor – Demonstrator (CHAPS-D), 

which derives heritage from TROPOMI. The demonstration will likely be on an aircraft over 
10

a region yet to be determined; BOEM could potentially negotiate for the demonstration to 

be over the GoM in BOEM’s jurisdiction. For instance, the flight pattern could help to 

validate NOx emissions in BOEM’s emission inventory.

• Surface Monitors: A number of studies have compared trends and surface concentrations 

inferred from OMI NO2 data to those estimated from surface AQ monitors, such as those 

part of the EPA AQS (Lamsal et al., 2008, 2015; Duncan et al., 2016). The results indicate 

that satellite-observed trends complement the AQS-observed trends, and both show the 

decrease in NO2 levels (on the order of 20–60%) since 2005 over U.S. cities due to a 

combination of environmental policies and technological changes (Figure 2). 

• Continuous Emissions Monitoring System (CEMS): Several studies have compared NOx

emissions inferred from OMI NO2 data to emissions independently reported for power 

plants (Duncan et al., 2013; de Foy et al., 2015; Liu et al., 2016). There is a clear response 

of OMI NO2 data to NOx emission reductions from power plants with the implementation 

of mandated emission control devices and generally have good agreement between the 

bottom-up inventory (i.e., CEMS) and the top-down emissions estimates based on the 

satellite data. 

⇒ Recommendation to BOEM: We recommend that BOEM consider using satellite data

(e.g., from TROPOMI or TEMPO) to infer NOx emissions from offshore ONG activities in 

the GoM and to validate the distribution and intensity of emissions from BOEM’s emission 

inventory. There are several techniques to infer emissions from satellite data, including 

ones developed at NASA.

• Field Campaigns: Although field campaigns are typically of short duration (e.g., 1–2 

weeks), the data collected by the suite of instruments may be used to validate satellite 

data. In Thompson (2020), we show how data collected during the SCOAPE cruise in May 

2019 validate the satellite data over the GoM.

2.3 NASA AQ Forecasts

Point of Contact at GMAO: mission-support@gmao.gsfc.nasa.gov

The NASA Global Modeling and Assimilation Office (GMAO) develops and maintains the GEOS 

system of models, which has a suite of capabilities including simulating weather, climate, 

chemistry-climate interactions, and now air pollution. They assimilate satellite and in situ data of 

some variables that affect weather and AQ into the GEOS model. The assimilation of these data 

improves the simulation of weather and AQ by providing the best representation of the 

atmosphere at the start of the forecast period.

Of relevance to BOEM, the GEOS system produces 5-day AQ forecasts of common air pollutants, 

such as ozone, NOx, CO, and PM2.5. The model output may be accessed directly, if BOEM 

personnel wish to perform their own analysis, or the forecasts may be easily visualized with a 

webtool called FLUID. FLUID includes BOEM's GoM domain (Figure 6-Figure 8).

⇒ Recommendation to BOEM: The learning curve is minimal (estimated time: < 1 day) to begin 

effectively using the NASA AQ forecasts to track pollution transport through the FLUID interface. 

Therefore, it is recommended that BOEM personnel integrate the AQ forecasts into BOEM’s SOP

immediately. The learning curve is steeper, though reasonable, for downloading and processing 

the forecast data.

⇒ Things to Know: The NASA AQ forecasts have been evaluated using numerous in situ and 

satellite datasets and have been found to perform well. The validation paper is in preparation.
11

Figure 6. The dedicated SCOAPE domain on FLUID.

Figure 7. Example of pollutants at various points that may be plotted with FLUID. 

This image shows the forecasted temporal evolution of the (top) vertical distribution of PM2.5 over Cocodrie, LA, 

(middle) total aerosol speciation near the surface, and (bottom) weather variables.
12

Figure 8. An example of spatial maps of pollutants, including tracers of various sources. 

This figure shows CO VCDs from onshore sources only (i.e., North American fossil fuel CO) that affect offshore 

during offshore flow. This capability allows a forecasted period to animate, which is useful for attributing the various 

sources of pollution that affect the GoM. ⇒ Things to Know: The forecast system carries tracers of CO that are 

“colored” or “tagged” by source as illustrated on the panel on the right of this image. This capability will allow BOEM 

personnel to estimate the impacts of various sources on AQ in the GoM.

⇒ Things to Know: The forecasts are archived since the beginning of 2018. They may be 

accessed and processed using commonly available software to understand past AQ events or 

seasonal variations, for instance.

⇒ Things to Know: The GMAO system currently does not include the BOEM emission inventory 

or any offshore emissions from ONG extraction activities. Nevertheless, the forecasts proved 

critical for interpreting satellite data and observations collected during the SCOAPE cruise, as 

discussed in Thompson (2020). BOEM could contact GMAO if it is desired to discuss the possible 

implementation of the latest BOEM emission inventory into their forecast system.

Tailored Forecasts

Point of Contact at GMAO: Christoph Keller (christoph.a.keller@nasa.gov).

The current horizontal spatial resolution of the forecast system is about 25x25 km2. Although this 

spatial resolution is not as fine as the resolutions of current regional AQ models, the model 
13

forecasts are for the entire globe. The near-term (< 2 year) goal is to move to about 12x12-km2

resolution forecasts, which will be made possible by continuing advances in computing resources 

and efficiency improvements.

Christoph Keller (NASA GMAO) provides tailored local forecasts for a given location using a 

machine learning algorithm that he developed (Keller et al., submitted). Using local AQ monitor 

data in combination with co-located NASA AQ model output, the algorithm generates biascorrection factors that correct for systematic model-observation mismatches (e.g., due to 

uncertainties in emission estimates or sub-gridscale local influences [i.e., representational error]). 

Once developed, these correction factors can be applied to the AQ forecasts on an ongoing basis 

to generate localized forecasts that capture the observations much better (e.g., Figure 9). 

Figure 9. Example of a tailored local forecast using machine learning (ML) applied to the NASA AQ 

modeled concentrations of O3. 

The ML drastically reduces the model bias.

⇒ Recommendation to BOEM: We recommend that BOEM upload AQ monitor data (1 year 

minimum) from along the GoM to the OpenAQ platform so that Keller can add provide automated 

tailored forecasts, which are delivered daily.

2.4 The Potential of Low-Cost Sensors

Point of Contact: Bryan Duncan (Bryan.N.Duncan@nasa.gov)

Most satellite datasets (Section 2.1) of pollutants do not provide much information, if any, on the 

3-d distribution of pollution. (For example, satellite data of NO2 are given in units of the total 

number of molecules of NO2 between the satellite and Earth’s surface, which is referred to as an 

atmospheric column [molecules/cm2] or VCD—a 2-d quantity.) An AQ network (Section 2.2) of 

regulatory-grade monitors across BOEM’s jurisdiction would only provide information on the 

distribution of air pollution at the surface and is prohibitively expensive to install and maintain.

Although an AQ model (Section 2.3) does provide information on the 3-d distribution of pollutants, 

most models do not have detailed emission inventories (as input) with a realistic distribution of 

emissions in the vertical (e.g., ships, aircraft, platforms, flares with plume rise).

The accuracy and precision of low-cost sensors (e.g., NO2, PM, O3) are improving with time and 

have become an indispensable tool for many AQ managers and NASA scientists to, for instance, 

identify pollution sources and high concentrations, understand hour-to-hour variations in pollution, 

and map out pollution gradients. Low-cost sensors could be deployed on various platforms, such 

as tethered balloons and drones, to collect the vertical data necessary to determine the complex 

3-D concentration structure of pollution from sources (e.g., onshore, offshore, including ships, 
14

helicopters, rigs, flares with plume rise) and the transport of pollution onshore. For instance, a 

low-cost sensor could be deployed on a Department of Interior drone and flown along a coastline 

through the depth of the mixed layer to understand the complex transport of pollution with landsea breezes. 

During the SCOAPE campaign, a low-cost, lightweight, and portable NO2 sensor (Sluis et al., 

2010) was deployed on a mobile platform (Figure 10–Figure 12) as a proof-of-concept for 

BOEM’s applications. By taking co-located observations, the sensor was calibrated with NO2 data 

from a regulatory-grade monitor sited at the LUMCON facility in Cocodrie, LA, before and after 

deployment.

⇒ Things to Know: The low-cost NO2 sensor was developed and deployed in the field by 

personnel from the Royal Dutch Meteorological Institute (KNMI). The sensor is currently 

undergoing commercialization for easy operation. Low-cost sensors for O3 (e.g., ozonesondes) 

and PM are already commercially available. 

⇒ Recommendation to BOEM: We recommend for BOEM to explore the potential of low-cost 

sensors for BOEM’s needs. Low-cost NO2, O3, and PM sensors are lightweight and may be 

deployed on mobile, drone, and tethered balloon platforms. Their versatility could prove very 

useful for BOEM for many applications, especially in areas with sparse or no observations from 

more traditional data sources.

Figure 10. The low-cost NO2 sensor has been deployed in numerous photochemical environments and on 

various platforms (e.g., mobile, tethered balloon, drone) around the world. 

The sensor was deployed on a mobile platform during the SCOAPE campaign to detect NO2 from offshore sources

along the coast. The image shows data collected at an industrial facility in Port Fourchon and demonstrates the 

power of the sensor to collect data with fine spatial resolution. Image and analysis courtesy of Mirjam den Hoed 

(KNMI), who participated in the SCOAPE campaign.
15

Figure 11. Same as the previous figure, except this figure shows data collected along a path from 

Cocodrie to Burns Point State Park, LA. 

Image and analysis courtesy of Mirjam den Hoed (KNMI), who participated in the SCOAPE campaign.

Figure 12. Demonstrating its capabilities, the low-cost NO2 sensor observed a wide range of levels, from 

relatively clean to highly polluted, along the path from Cocodrie to Burns Point State Park, LA, on May 15, 

2019.

Image and analysis courtesy of Mirjam den Hoed (KNMI), who participated in the SCOAPE campaign.
16

2.5 Illustrative Case Studies

In this section, we present three illustrative case studies to demonstrate the methodology of how 

to use a suite of cost-effective NASA and non-NASA resources to monitor and understand 

variations in pollution within the GoM (and all coastal waters of the continental U.S.), and to 

attribute sources. Two of the case studies highlight the differences in pollution over the GoM under 

predominately offshore and onshore flows. Typically, air from the GoM has lower levels of NO2

than air originating over land (Figure 13 and Figure 14). The other case study highlights the 

impact of agricultural fires in Mexico on the GoM—an unusual event. These case studies were 

developed by Dan Anderson (NASA; postdoctoral fellow of Duncan) and all images in this section 

are courtesy of him, except where noted.

⇒ Things to Know: The resources and methodology illustrated in the case studies are employed

to assess the daily state of AQ during NASA field campaigns, including SCOAPE, to determine, 

for instance, where to send research vessels to intercept plumes or to sample concentration 

gradients. They have been refined over the past several decades, integrating new datasets and 

tools as they become available.

Figure 13. NOAA Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) back trajectories 

initiated every hour at Cocodrie, LA, for April and May 2019. 

The colors indicate the NO2 concentrations observed at Cocodrie, LA, when each trajectory arrived. The NO2 data 

are from the Pandora instruments deployed on the roof of the LUMCON facility. (right) The average NO2 VCD (DU) 

for the two flow regimes show that air masses originating deep within the GoM are typically cleaner than air 

originating over land. ⇒ Things to Know: Typically, satellite data of NO2 are reported in units of molecules/cm2 for 

either the total column (i.e., TC NO2 = total atmosphere column) or tropospheric portion of the total column (i.e., 

TropC NO2). The data reported from the Pandora network are total columns, but in units of DU (Dobson Unit = 

2.687×1016 molecules/cm2).
17

Figure 14. TROPOMI TropC NO2 (VCD) on a day (i.e., Case #1) with offshore flow near the surface from 

Louisiana, Mississippi, and Alabama and weak onshore flow in East Texas (left) and relatively stronger 

onshore flow (i.e., Case #2) for the same area (right). 

The near-coastal environment of the GoM has higher VCDs during offshore flow than onshore. White areas indicate 

“no data”, such as may result from when clouds are present.

We use the following resources in our analyses as presented in the case studies:

• NASA AQ forecasts: https://fluid.nccs.nasa.gov/missions/mission_SCOAPE/ . 

Skill level* required: beginner.

• NOAA Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) Model: 

https://ready.arl.noaa.gov/HYSPLIT.php. 

Skill level required: beginner.

• NASA WorldView: https://worldview.earthdata.nasa.gov/ for visualizing NASA data.

Skill level required: beginner.

• EO Browser: http://apps.sentinel-hub.com/eo-browser/ for visualizing ESA data, including 

TROPOMI.

Skill level required: beginner.

• Satellite Data: The TROPOMI data were downloaded from the NASA EarthData website 

(https://search.earthdata.nasa.gov/search?q=S5P_L2__NO2____HiR_1) and plotted

with MATLAB software. Other software sources may be used: 

http://www.tropomi.eu/tools; general information on accessing NO2 data: 

https://earthdata.nasa.gov/learn/articles/feature-articles/health-and-air-qualityarticles/find-no2-data

Skill level required: intermediate-advanced.

*Skill level refers to using the tool, not necessarily accurately interpreting the data.

⇒ Things to Know: The GoM typically has some clouds (Figure 15), which reduces the spatiotemporal coverage of remote sensing instruments, whether on platforms in space (i.e., satellite) 

or on the surface (e.g., Pandora). Satellites with fine pixels (e.g., TROPOMI) will be able to collect 

more cloud-free data than those with coarser pixels (e.g., OMI). Therefore, AQ forecast output in 

concert with satellite data will allow BOEM personnel to better interpret the AQ state than relying 

on satellite data alone.
18

Figure 15. May cloud climatology: ERA-Interim Reanalysis averaged total cloud fraction for May, from 

1979–2014. 

May is one of the least cloudy months on average (i.e., only ~30–40% cloud cover). Figure courtesy of Ryan Stauffer 

(NASA).
19

2.5.1 Case #1: Offshore Flow (September 5, 2019)

There was offshore flow near the surface over the Louisiana coast on September 5, 2019, as 

simulated by the NASA AQ forecast and NOAA HYSPLIT models (Figure 16). In this flow pattern, 

pollution from the land pushed offshore over the areas of ONG operations in the GoM as shown 

by multiple tracers from the AQ forecast (Figure 17). Clear skies extended far offshore (Figure 

18), allowing for satellite data collection over most of the region (Figure 19 and Figure 20).

Interpretation and other details are given in the captions of each figure.

Figure 16. Wind speed and direction from the NASA AQ model and backward trajectories from the NOAA 

HYSPLIT model on September 5, 2019. 

(left) The flow at 925 hPa was predominately from the continent at Cocodrie, LA. The red line indicates the location of 

vertical cross-sections shown in subsequent figures. The red dots represent the locations of specialized forecasts on 

FLUID, which correspond to cities, major ONG platforms and the Louisiana Offshore Oil Port (LOOP). (right) 

Backward trajectories from HYSPLIT indicate that air (from the surface to 3 km) that arrived at Cocodrie, LA, had 

originated inland. ⇒ Relevance to BOEM: Note that pollution from offshore flow over Louisiana is transported back 

over land in Texas. Recirculation of continental pollution in the GoM is a common feature, which highlights the need 

for the AQ forecasts to help identify pollution sources and source regions.
20

Figure 17. Simulations of concentrations for CO (top), NO2 (middle), and O3 (bottom) from the AQ model 

accessed via FLUID. 

Near-surface concentrations (left). The red line indicates the location of the cross-section plots (right). The plots show 

onshore pollution flowing into the GoM, primarily near the surface. ⇒ Things to Know: Though the simulated O3 tends 

to be biased high in the model, the regional transport of O3 is simulated well.
21

Figure 18. NASA Terra/Aqua MODerate resolution Imaging Spectrometer (MODIS) True Color Imagery

of the GoM at midday on September 5, 2019. 

Shows clear skies over much of the GoM. Image processed and downloaded from Worldview. 

Figure 19. TROPOMI (left) TropC NO2 VCDs (x1015 molecules/cm2) and (right) TC CO VCDs (x1018

molecules/cm2) on September 5, 2019.

Given its short lifetime (~hours), the highest NO2 VCDs are near emissions sources. NO2 levels are relatively high 

near the shore, which is likely associated with onshore pollution that was transported offshore, mixing with offshore 

pollution, such as from shipping and offshore ONG activities. High NO2 concentrations from large offshore sources, 

such as the LOOP, are visible. There is less of a gradient in CO, which has a longer lifetime (~month). However, the 

data indicate rather widespread levels of pollution in the GoM, which is consistent with offshore flow. The white areas 

indicate where TROPOMI data are missing due to clouds. ⇒ Things to Know: The various data products from the 

same instrument may be processed differently, so that their spatial coverages can differ as in this example.
22

Figure 20. NASA Terra Measurement of Pollution in the Troposphere (MOPITT).

TC CO and OMI TropC NO2 VCDs do not indicate enhanced pollution levels over the GoM for this day despite 

offshore flow. The datasets have gaps over most of the region of interest on September 5, 2019. These instruments 

are on an older generation of satellites (Aqua, launched 2002, and Aura, launched 2004) relative to TROPOMI 

(launched 2017). ⇒ Things to Know: OMI has part of its field of view blocked, which results in areas of no data in 

clear skies.
23

2.5.2 Case #2: Onshore Flow (September 11, 2019)

There was onshore flow near the surface over the Louisiana coast on September 11, 2019, as 

simulated by the NASA AQ forecast and NOAA HYSPLIT models (Figure 21). In this flow pattern, 

pollution from offshore sources in the GoM pushes onshore as shown by multiple tracers from the 

AQ forecast (Figure 22). Partly to mostly sunny skies extended over the GoM (Figure 23), 

allowing for satellite data collection over most of the region (Figure 14 and Figure 24). 

Interestingly, a flare was detected at about 1:30 am using NOAA Suomi National Polar-orbiting 

Partnership (Suomi NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) thermal imagery, but

neither TROPOMI nor OMI (not shown) detected elevated levels of NO2 12 hours later at their 

1:30 pm overpasses (Figure 25). Interpretation and other details are given in the captions of each 

figure.

Figure 21. Onshore flow near the surface over the Louisiana coast on September 11, 2019.

(left) Wind speed and direction at 925 hPa from the NASA AQ forecast on September 11, 2019. The red line indicates 

the location of vertical cross-sections shown in subsequent figures. (right) Backward trajectories from HYSPLIT 

indicate air (from the surface to 3 km) arrived at the Brutus platform from the east.
24

Figure 22. Simulated concentrations of CO (top), NO2 (middle), and O3 (bottom) accessed via FLUID. 

Near-surface concentrations (left). The red line indicates the location of the cross-section plots (right). The plots show 

tropical air flowing into the GoM in the western part of the domain and continental polluted air in the eastern part, 

which originated from the southeast U.S., particularly Florida.
25

Figure 23. MODIS True Color Imagery of the GoM at midday on September 11, 2019. 

Shows partly to mostly sunny skies extended over the GoM. Image processed and downloaded from WorldView.

Figure 24. Though much of the western part of the GoM has missing TROPOMI data because of clouds 

(Figure 23), there are generally higher CO VCDs in the eastern part of the GoM than the western part.
26

Figure 25. Flare event was detected by a satellite on September 11, 2019.

The VIIRS instrument that detects nighttime lights captured a flare (circled) at 1:30 am, its overpass time, (top). 

Image produced with WorldView. (bottom left) The HYSPLIT model indicates that the plume was transported slowly 

to the northwest (bottom right). However, elevated NO2 concentrations are not evident in TROPOMI data 12 hours 

later. Some of the NO2 in the plume may have been dispersed and/or converted to NO at the 1:30 pm TROPOMI 

overpass time. The plume is not evident in OMI NO2 either (not shown).
27

2.5.3 Case #3: Pollution from Outside GoM (May 13, 2019)

During the SCOAPE field campaign, pollution from widespread agricultural fires in Mexico polluted 

the GoM, significantly elevating pollutants, such as aerosol and CO (Figure 26–Figure 29). The 

AQ forecasts indicate that Cocodrie, LA, was less impacted than farther offshore, such as the 

Atlantis platform (Figure 30–Figure 32). Interpretation and other details are given in the captions 

of each figure.

Figure 26. MODIS True Color Imagery illustrates the widespread smoke from agricultural fires (red dots 

indicate detected fires) that polluted the GoM.

Figure 27. Aerosol optical depth (AOD) is an indicator of the concentration of the smoke with the warmest 

colors being the highest concentrations.

Interestingly in this example, much of the smoke was so thick that some of the data are marked as “missing” because 

they were likely flagged as clouds.
28

Figure 28. TROPOMI shows that high levels of CO were transported from Mexico into the GoM.

Figure 29. The AQ forecast simulates the northeastward transport of smoke from Mexican agricultural fires. 

Black carbon (BC) is used as an indicator of the smoke.
29

Figure 30. The AQ forecast predicts high levels of organic carbon (OC) and BC associated with the fires 

early in the forecast period over Cocodrie, LA, but a cold front moved south off the coast clearing out the 

smoke. 

Figure 31. The smoke was predicted to impact offshore for a longer period, such as at the Atlantis platform.
30

Figure 32. A clear increase in elevated O3 and BC concentrations from trajectories originating over the 

Yucatan peninsula, where agricultural burning was occurring. 

24-hour HYSPLIT back trajectories were initiated every hour along the SCOAPE ship track for May 12, 2019. The 

trajectories are colored by the concentration of O3 (top) and BC (bottom) observed on the SCOAPE ship.

3 Summary and High-level Recommendations to BOEM

In this report, we show that satellite data and other NASA resources may be used to monitor AQ 

in the GoM, including the coastal environments. Here we provide a high-level summary of our 

recommendations that are given throughout the report.

⇒ High-level Recommendation #1: We recommend that BOEM adopts an integrated approach to 

monitoring AQ in the GoM, which consists of regulatory-grade AQ monitors and non-traditional 

sources of AQ data, including satellite data, AQ models, and in situ monitors (Section 2). As a 

first step, we recommend that BOEM personnel take advantage of the NASA ARSET and 

HAQAST programs to explore NASA’s free and publicly available resources, so that BOEM 

personnel may identify the potential of these resources for BOEM’s various applications and to 

begin integrating them into BOEM’s SOP. Most of these resources are easily accessed via 

webtools, though accessing, processing, and analyzing satellite data (beyond visualization with 

webtools) will require more effort on the part of BOEM personnel.

⇒ High-level Recommendation #2: We recommend that BOEM personnel continue to interact 

with NASA personnel, and potentially personnel from EPA and NOAA, to identify mutually 

beneficial collaborations that will advance BOEM’s goals to monitor AQ in the GoM. Several 

potential examples of these collaborations are given in Section 2.2.

⇒ High-level Recommendation #3: We recommend that BOEM personnel continue to work with 

NASA personnel to understand the relation between quantities (e.g., VCDs) observed from space 

and pollutant concentrations within the boundary layer, including offshore and along the coast. In 

Thompson (2020), we show that pollutant concentrations can have complex 3-d distributions 
31

offshore (e.g., from the vertical structure of pollutant emissions) and in coastal environments (e.g., 

from complex sea breezes). BOEM personnel would benefit from working with NASA personnel, 

who have developed the NASA data and simulated products and, therefore, know their strengths 

and limitations for BOEM’s applications, as well as, how to avoid common mistakes when 

analyzing them.

4 References

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Duncan, Bryan N., Lesley Ott, et al. (2020). Space-based observations for understanding changes 

in the Arctic-Boreal Zone, Review of Geophysics, 58, e2019RG000652. 

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