ACCESS NUMBER: M07AC13332/M07AC12463 

STUDY TITLE: Evaluation of NASA Aura’s Data Products for Use in Air 

Quality Studies over the Gulf of Mexico

REPORT TITLE: Evaluation of NASA Aura’s Data Products for Use in Air 

Quality Studies over the Gulf of Mexico

CONTRACT NUMBERS: M07AC13332/M07AC12463 

SPONSORING OCS REGION: Gulf of Mexico 

APPLICABLE PLANNING AREAS: Central and Western Gulf of Mexico 

FISCAL YEARS OF PROJECT FUNDING: 2007 

COMPLETION DATE OF REPORT: October 2009 

COSTS: FY 2007: $120,348; CUMULATIVE PROJECT COST: $120,348 

PROJECT MANAGER: Arastoo Pour Biazar 

AFFILIATION: University of Alabama in Huntsville 

ADDRESS: University of Alabama in Huntsville, Huntsville, Alabama 35899 

PRINCIPAL INVESTIGATORS*: Arastoo Pour Biazar, Richard T. McNider 

KEY WORDS: Air quality modeling, transboundary pollution, boundary/initial 

condition, satellite assimilation, Aura, OMI, MODIS, satellite observed trace 

gases, PM2.5, aerosols, IONS-06, air quality impacts assessment, boundary 

layer, free troposphere, Gulf of Mexico, criteria pollutants, NAAQS, MM5, CMAQ. 

BACKGROUND: The assessment of potential environmental impact of oil and gas 

operations in the Gulf of Mexico (GoM) and in particular the onshore air quality impact 

of such operations is important to State and Federal regulatory agencies. GoM region is 

home to some of the most precious and sensitive habitats. Several coastal areas in the 

northeastern Gulf of Mexico have been designated as Wildlife Refuges and National 

Preserves. Some of these areas are assigned Class I and II status by the U.S. 

Environmental Protection Agency (EPA), and are subject to the most rigorous 

requirements for air quality. Due to such sensitivities, confidence in air quality 

assessments and reducing the uncertainties in the air quality studies over the GoM region 

is imperative. Furthermore, in adapting sound policies for control strategies, it is crucial 

to assess the impact of local pollution versus transboundary air pollution, and in a region 

such as GoM with scarce monitoring capability over open waters such distinctions 

represents a challenge. Furthermore, GoM region might be impacted by the recirculation 

of pollution in the southeastern United States (a hypothesis that was tested in this 

project). High pressure systems such as Bermuda high can transport pollution from 

northeast over the waters off the east coast and recirculate it to the GoM region through 

southerly/southeasterly flow. 
Understanding the background atmosphere and transboundary pollution is important to 

properly assessing air quality impacts. Since air quality models are utilized for assessing 

the impacts of offshore operations, the inaccuracies in the model predictions of pollutants 

can significantly affect the outcome of impacts analysis. In assessing the potential 

onshore impact of ozone from the outer continental shelf (OCS) sources, one source of 

uncertainty in photochemical models is the specification of the background air. Errors in 

the specification of background concentrations of ozone and its precursors will propagate 

in the model and impact model predictions of ozone. Therefore, decreasing such 

reducible errors is of interest to the regulatory agencies. Newly available satellite 

observations of aerosols and trace gases potentially can be utilized for proper 

specification of the background and transboundary air which is critical to air quality 

impacts assessment. 

The University of Alabama in Hunstville (UAH) has had a long history of working with 

National Aeronautics and Space Administration (NASA), National Oceanic and 

Atmospheric Administration (NOAA) and applied agencies such as the National Weather 

Service, the U.S. Environmental Protection Agency (USEPA) and State air quality 

programs in developing and transferring satellite products and techniques to the user 

community. At the present UAH is supported by a NASA Applications Grant to transfer 

some of the techniques outlined in the present report into the USEPA Community Air 

Quality (CMAQ) modeling system. Through this process USEPA works with UAH and 

the user community in testing the techniques. The techniques then become part of the 

USEPA supported system that can be broadly disseminated and used by states and air 

quality consultants. The UAH expects that this synergistic relationship between NASA, 

NOAA and EPA in remote sensing tools will allow the results supported by this project 

to be extended to a broad user community. 

OBJECTIVES: The overall goal of this project is to improve the performance of the 

meteorological/air quality models used in the State Implementation Plan (SIP) 

applications by using satellite data. The key question addressed is whether the satellite 

data can be utilized in air quality assessments, either for improving model performance or 

for evaluation. The main objectives are (1) to evaluate several satellite products, namely 

TES and OMI ozone profiles, and the Moderate Resolution Imaging Spectroradiometer 

(MODIS) aerosol products, (2) to devise techniques for the utilization of satellite data in 

the model, and (3) to perform model simulations for August 2006 and evaluate the results 

against ozonesonde and surface observations.

DESCRIPTION: The work presented in this report is directed at improving the 

specification of background and transboundary air through the use of satellite data. The 

tools and techniques using the satellite data are tested in the context of the type of current 

regulatory air quality models (i.e., MM5/CMAQ). In particular, the techniques using 

satellite data for specifying initial and lateral boundary conditions for CMAQ are 

examined in the context of recent national level air quality studies undertaken (e.g., 

Intercontinental Chemical Transport Experiment Ozonesonde Network Study 2006 

(IONS-06) campaign and Texas Air Quality Study).
ACCESS NUMBER: M07AC13332/M07AC12463 

SIGNIFICANT CONCLUSIONS: The utilization of OMI ozone profiles significantly 

improved model performance in the free troposphere and the use of MODIS aerosol 

products substantially enhanced model prediction of aerosols in the boundary layer. 

Neither OMI nor TES provide adequate information in the boundary layer with respect to 

O3 and as a result they can only marginally impact ozone predictions in the boundary 

layer. Our overall assessment of the utility of satellite ozone observations for air quality 

studies is that the quality of the data for the boundary layer is not satisfactory. OMI 

observations are valuable in improving ozone fields in the free troposphere which in turn 

can affect ozone abundance in the boundary layer, but are not adequate to explain the low 

background ozone concentration in the boundary layer. Ozone in the mid- to uppertroposphere is largely dominated by transport, while the ozone within boundary layer is 

mostly affected by fast production/loss mechanisms that are impacted by surface 

emissions, chemistry and removal processes. 

The utilization of the satellite data for lateral boundary condition (BC) was helpful in 

the realization of transboundary transport of pollution. Our hypothesis that the 

recirculation of pollution from Northeast Corridor can play a role over the Gulf of 

Mexico (GoM) was tested and model simulations showed evidence of such possibility. 

The episodic transport of pollution by easterlies over the GoM and the southeastern 

region suggests that in particular the specification of the lateral boundaries and the 

background air in modeling practices in this region is important. 

With respect to the use of MODIS aerosol products, while satellite data improved 

model performance with respect to PM2.5 total mass concentration, aerosol speciation 

remains a challenge. The incorporation of satellite data relied on a key assumption that 

the aerosol partitioning within the model is reliable. Therefore, revisiting this assumption 

or improving the aerosol model within CMAQ takes higher priority. 

The current project did not examine the role of assimilation in improving the physical 

atmosphere. Future efforts should include an improved physical atmosphere in 

conjunction with the assimilation of satellite trace gases. For example, it has been shown 

that the assimilation of satellite-observed clouds greatly improves model predictions of 

ozone within the boundary layer. It also eliminates one component of inconsistency 

between the model and the observations. One of the problems in satellite data 

assimilation is that the observed physical/chemical world is not always consistent with 

the model world. A major manifestation of this inconsistency is with respect to the 

clouds. A discrepancy between model clouds (clear sky) and the satellite clouds (clear 

sky) impacts the radiation fields, vertical transport and local circulations, the chemistry 

and microphysical properties. This means that when one component of physical or 

chemical atmosphere is perturbed (adjusted) by the assimilation of satellite data, the 

complete environment for supporting and sustaining the adjustment does not exist. 

Therefore, as we continue to introduce more chemical observations into the modeling 

framework, it is essential that in a parallel effort we make the physical environment more 

realistic. This means the inclusion of assimilation of satellite observed skin temperature, 
moisture, albedo, insolation, and clouds in conjunction with the assimilation of trace 

gases and aerosols. 

Finally, while satellite observation of ozone alone did not fulfill our expectations for 

air quality studies, the use of satellite observation of ozone and other trace gases in 

conjunction with surface observations needs to be investigated. For example, there are 

complementary satellite observations such as nitrogen dioxide (NO2), formaldehyde 

(HCHO), and carbon monoxide (CO) that can help in specifying the background air. 

Also, the routine surface observations can be used to scale satellite observation and 

introduce diurnal variation to the measurements. Surface measurements, while detailed 

and continuous, are point measurements and lack the ability of representing a larger 

region. On the other hand, the information from A-Train polar orbiting satellites is an 

early afternoon snap shot of the atmosphere and represents an average quantity over a 

larger area. A natural extension of the efforts documented in this report would be to 

examine the feasibility of such approaches. 

The modeling simulations reported here used relatively coarse grid spacing over the 

continental United States and was able to explain the large scale impact of long range 

transport. However, a future study should examine the utilization of the techniques and 

the data used in this study for a smaller domain over the southeastern U.S. with finer grid 

spacing. 

STUDY RESULTS: The utility of OMI O profiles and MODIS aerosol products in 

CMAQ was demonstrated. Use of OMI O profiles to privide BC reduced ozone bias by 

more than 30 ppb in the mid- to upper-troposphere. In this project, daily information 

from the satellite was also utilized to improve the initial condition (IC) in the model. 

This effort can lead to effectively assimilate the satellite data into the model fields. Since 

the initial conditions greatly impact the short term predictions, use of satellite data for IC 

can also potentially improve air quality forecasts. The utilization of MODIS aerosol 

optical depth (AOD) in specifying IC greatly improved model prediction of PM2.5 

concentrations. 

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The results and conclusions from this study are based on the evaluation of model 

results against IONS-06 ozonesonde measurements, satellite observations, surface 

monitoring stations, and comparison with a global transport model that had assimilated 

column ozone observations. OMI ozone profiles were in reasonable agreement with 

ozonesonde measurements in the free troposphere with a mean bias of less than 10 ppb 

and a normalized bias of less than 5%. Combining satellite observations with CMAQ 

fields to generate BC presented advantage over the use of a global chemical transport 

model to create BC. 

The use of MODIS AOD for IC/BC reduced PM2.5 mean fractional bias (MFB) by 

more than 30% over the entire domain, while its utilization for BC only reduced MFB by 

5%. Since most of the aerosols were within the boundary layer with relatively shorter 

lifetime, the impact of the BC on a modeling domain that covered the continental United 

States were limited to the regions closer to the lateral boundaries of the domain. In 
ACCESS NUMBER: M07AC13332/M07AC12463 

contrast, daily readjustment of the aerosol fields (based on satellite observations) reduced 

model errors significantly over the entire domain. 

The results from this project were presented in several scientific meetings and have 

been documented in a report to Minerals Management Service. 

STUDY PRODUCTS: 

Biazar, A.P., R.T. McNider, M. Newchurch, M. Khan, Y.H. Park, and L. Wang. 2010. 

Evaluation of NASA AURA’s data products for use in air quality studies over the Gulf of 

Mexico. U.S. Dept. of the Interior, Bureau of Ocean Energy Management, Regulation 

and Enforcement, Gulf of Mexico OCS Region, New Orleans, LA. OCS Study BOEMRE 

2010-051. 82 pp. 

Pour Biazar,Arastoo, Richard T. McNider, Maudood Khan, Mike Newchurch, Xiong 

Liu, Yun-Hee Park, Lihua Wang, Daewon W. Byun, Use of Ozone Monitoring 

Instrument (OMI) Ozone Profiles in Air Quality Assessment Studies, 30th European 

Association of Remote Sensing Laboratories (EARSeL) Symposium, UNESCO 

Headquarters, Paris, France, May 31-June 3, 2010. 

Pour-Biazar, A., M. Khan, M. Newchurch, L. Wang, Y. Park, X. Liu, D. W. Byun, 

Examining the Utility of Satellite Observations in Improving Air-Quality Predictions, 

International Workshop on Air Quality Forecasting Research, NOAA CSD/ESRL, 

Boulder, CO, December 2-3, 2009. 

Pour Biazar, A., R. T. McNider, M. Khan, M. Newchurch, W. Koshak, G. Jedlovec, 

J. Pleim, X. Liu, G. Osterman, D. W. Byun, K. Chance, T. P. Kurosu, Incorporating 

Space-borne Measurements to Improve Air Quality Decision Support System, NASA 

Applied Science Air Quality Team meeting, Washington DC, October 27-29, 2009. 

Wang, Lihua, A. P. Biazar, M. J. Newchurch, Application of OMI ozone profiles in 

CMAQ, 7th Annual CMAS Conference, Chapel Hill, NC, October 6-8, 2008. 

Pour Biazar, Arastoo, Y. H. Park, M. Khan, S. Christopher, Application of Satellite Fine 

Aerosol Product in CMAQ, 7th Annual CMAS Conference, Chapel Hill, NC, October 6-

8, 2008. 

Pour Biazar, Arastoo, R. T. McNider, K. Doty, M. Newchurch, L. Wang, Y. H. Park, M. 

Khan, X. Liu, D. W. Byun, S. J. Roselle, R. Cameron, Examining the Impact of Satellite 

Cloud Correction Together with the Assimilation of Satellite-Derived Ozone and Aerosol 

Products in Improving Air Quality Model Predictions, 7th Annual CMAS Conference, 

Chapel Hill, NC, October 6-8, 2008. 

Yang, Eun-Su., A. P. Biazar, S. Christopher, CMAQ air quality forecasts using satellite 

aerosol retrievals, in Proceedings of American Meteorological Society 88th Annual 
Meeting, 10th Conference on Atmospheric Chemistry (10atchem), New Orleans, LA, 

January 20-24, 2008.