Benjamin de Foy, Ph.D.

Professor
Department of Earth and Atmospheric Sciences


Courses Taught

Earth's Dynamic Environment II - Atmospheres; Earth's Dynamic Environment II - Atmospheres Lab; Climate Change; Fundamentals of the Climate System; Air Pollution; Journal Club; Communication in Science; Hands-on Lab: Weather Research & Forecasting Model; Environmental Aspects of Sustainability

Research Interests

Inverse Modeling

De Foy has been working on inverse modeling to improve emissions inventories using long time series of hourly measurements at fixed sites.

The inverse model was used to estimate emissions of elemental mercury from lake surface outgasing, forest fires, power plants and unreported sources using measurements in Milwaukee (de Foy et al., 2012).

It was then expanded to analyze sources of reactive mercury and to differentiate the impacts of direct emissions, transport from the free troposphere and different oxidation pathways (de Foy et al., 2014).

He is currently working on using it to evaluate diurnal and annual patterns of emissions of elemental and organic carbon (de Foy et al, 2014).

The model is based on a least squares simplification of the classic Bayesian formulation. This can be done if one considers only the transport of pollutants or if one can represent the impact of chemical formation with a time series at the measurement site. Using Iteratively Reweighted Least Squares (IRLS) makes the results much more robust to outliers. The beauty of the least squares inversion is the speed at which it can be done. Uncertainty estimates can therefore be obtained by using block-bootstrapping. If one assumes that measurement errors are randomly distributed, and if model errors are different on any given day, then one can simulate the uncertainty in the results by selecting the days to be included in the inversion at random. This provides larger, yet more realistic, error bars than the normal least squares standard errors. Another strength is that it does not require a priori estimates of the uncertainty as in Monte Carlo Error Propagation, but rather deduces what these are from the data itself. A second advantage of the least squares method is that it is straightforward to include different types of sources in the analysis from different models. For example, the model can combine both Eulerian and Lagrangian models.

Satellite Data Analysis

Most air quality products from satellites have a grid size larger than 10 by 10 km2. With swath data that has varying resolution and grids in different places from day to day, it is possible to use oversampling to obtain information on finer grids. de Foy used this in Mexico City to obtain high resolution maps of the sulfur dioxide plumes from the Popocatepetl volcano and from an industrial complex (de Foy et al., 2009).

He is working on getting improved estimates of emissions from large point sources as well as chemical lifetimes. The accuracy of different methods was tested using a numerical transport model (de Foy et al., 2014).

Mexico City

De Foy did his postdoc with Prof. Mario Molina and Dr. Luisa Molina in the Mexico City Project at MIT. During this time, he was involved as a weather forecaster and computer modeler in the MCMA-2003 and the MILAGRO field campaigns. Many of the papers from the field campaigns are available in Atmospheric Chemistry and Physics in the special issues for MCMA-2003 and for MILAGRO.

He used numerical simulations from MM5 and WRF as input to the FLEXPART particle trajectory model. Even though winds in the Mexico City basin are very complex and there are large errors in the simulations of instantaneous wind fields, the researchers showed that overall the atmospheric transport is correctly characterized by the models (de Foy et al., 2009). The simulations were used by multiple groups to help analyze the field campaign measurements.
In de Foy et al., 2011, the researchers compared measurements made with the High Spectral Resolution Lidar (HSRL) with particle trajectory simulations to analyze the sources and transformation of particles in the atmosphere in Mexico City. This showed that the HSRL detected atmospheric tar balls in fresh biomass plumes.

In de Foy et al., 2007 the researchers analyzed surface and column measurements, along with Concentration Field Analysis and Residence Time Analysis to study the transport of pollutants and to evaluate emissions inventories for Mexico City.

As a result of the field campaigns, the researchers found that there was rapid and effective ventilation of pollutants in Mexico City (de Foy et al., 2006). On most days, the pollutants are flushed out of the basin on the same day. In this way, Mexico City is actually more similar to Houston where the sea breeze cleans out the city every day than it is to Los Angeles where a capping inversion leads to multi-day accumulation.

Urban Heat Island

Many tropical cities have an urban heat island at night and a cool island during the day. The behavior of the heat island varies with the seasons. There are different ways of measuring the urban heat island. One way is to compare meteorological observations of the air temperature in the city and in the surrounding country side. Another way is to use satellite remote sensing of the land surface temperature. de Foley and his studentshowed that the seasonal behavior of the urban heat island is different depending on which measurement method is used (Cui and de Foy, 2012). They also showed that daytime urban heat island were a function of vegetation differentials between the city and its surroundings, and that the nighttime urban heat island was a function of atmospheric stability.

Humming earth due to ocean waves

In an interdisciplinary project, de Foley contributed model and satellite data analysis to studies of the earth's hum by Keith Koper which led to several joint publications starting with Koper and de Foy, 2008.

Publications and Media Placements

61. De Foy, B., Z.F. Lu, and D.G. Streets, Satellite NO2 retrievals suggest China has exceeded its NOx reduction goals from the twelfth Five-Year Plan. Scientific Reports, 2016. 6: p. 9. (http://rdcu.be/l4qC)

60. De Foy, B., Z.F. Lu, and D.G. Streets, Impacts of control strategies, the Great Recession and weekday variations on NO2 columns above North American cities. Atmospheric Environment, 2016. 138: p. 74-86.

59. De Foy, B., Y.D. Tong, X.F. Yin, W. Zhang, S.C. Kang, Q.G. Zhang, G.S. Zhang, X.J. Wang, and J.J. Schauer, First field-based atmospheric observation of the reduction of reactive mercury driven by sunlight. Atmospheric Environment, 2016. 134: p. 27-39.

58. Wang, Y.Q., Y. Zhang, J.J. Schauer, B. de Foy, B. Guo, and Y.X. Zhang, Relative impact of emissions controls and meteorology on air pollution mitigation associated with the Asia-Pacific Economic Cooperation (APEC) conference in Beijing, China. Science of the Total Environment, 2016. 571: p. 1467-1476.

57. De Foy, B., Y.Y. Cui, J.J. Schauer, M. Janssen, J.R. Turner, and C. Wiedinmyer, Estimating sources of elemental and organic carbon and their temporal emission patterns using a least squares inverse model and hourly measurements from the St. Louis-Midwest supersite. Atmospheric Chemistry and Physics, 2015. 15(5): p. 2405-2427.

56. De Foy, B., Z. Lu, D.G. Streets, L.N. Lamsal, and B.N. Duncan, Estimates of power plant NOx emissions and lifetimes from OMI NO2 satellite retrievals. Atmospheric Environment, 2015. 116: p. 1-11.

55. De Foy, B. and J.J. Schauer, Origin of high particle number concentrations reaching the St. Louis, Midwest Supersite. Journal of Environmental Sciences-China, 2015. 34: p. 219-231.

54. Heo, J., B. de Foy, M.R. Olson, P. Pakbin, C. Sioutas, and J.J. Schauer, Impact of regional transport on the anthropogenic and biogenic secondary organic aerosols in the Los Angeles Basin. Atmospheric Environment, 2015. 103: p. 171-179.

53. Lu, Z., D.G. Streets, B. de Foy, L.N. Lamsal, B.N. Duncan, and J. Xing, Emissions of nitrogen oxides from US urban areas: estimation from Ozone Monitoring Instrument retrievals for 2005-2014. Atmospheric Chemistry and Physics, 2015. 15(18): p. 10367-10383.

52. Cui, Y.Y., A. Hodzic, J.N. Smith, J. Ortega, J. Brioude, H. Matsui, E.J.T. Levin, A. Turnipseed, P. Winkler, and B. de Foy, Modeling ultrafine particle growth at a pine forest site influenced by anthropogenic pollution during BEACHON-RoMBAS 2011. Atmospheric Chemistry and Physics, 2014. 14(20): p. 11011-11029.

51. De Foy, B., J. Heo, and J.J. Schauer, Estimation of direct emissions and atmospheric processing of reactive mercury using inverse modeling. Atmospheric Environment, 2014. 85: p. 73-82.

50. De Foy, B., J.L. Wilkins, Z.F. Lu, D.G. Streets, and B.N. Duncan, Model evaluation of methods for estimating surface emissions and chemical lifetimes from satellite data. Atmospheric Environment, 2014. 98: p. 66-77.

49. Sufri, O., K.D. Koper, R. Burlacu, and B. de Foy, Microseisms from Superstorm Sandy. Earth and Planetary Science Letters, 2014. 402: p. 324-336.

48. Duncan, B.N., Y. Yoshida, B. de Foy, L.N. Lamsal, D.G. Streets, Z.F. Lu, K.E. Pickering, and N.A. Krotkov, The observed response of Ozone Monitoring Instrument (OMI) NO2 columns to NOx emission controls on power plants in the United States: 2005-2011. Atmospheric Environment, 2013. 81: p. 102-111.

47. Heo, J., J.E. McGinnis, B. de Foy, and J.J. Schauer, Identification of potential source areas for elevated PM2.5, nitrate and sulfate concentrations. Atmospheric Environment, 2013. 71: p. 187-197.

46. Lu, Z.F., D.G. Streets, B. de Foy, and N.A. Krotkov, Ozone Monitoring Instrument Observations of Interannual Increases in SO2 Emissions from Indian Coal-Fired Power Plants during 2005-2012. Environmental Science & Technology, 2013. 47(24): p. 13993-14000.

45. Smyth, A.M., S.L. Thompson, B. de Foy, M.R. Olson, N. Sager, J. McGinnis, J.J. Schauer, and D.S. Gross, Sources of metals and bromine-containing particles in Milwaukee. Atmospheric Environment, 2013. 73: p. 124-130.

44. Streets, D.G., T. Canty, G.R. Carmichael, B. de Foy, R.R. Dickerson, B.N. Duncan, D.P. Edwards, J.A. Haynes, D.K. Henze, M.R. Houyoux, D.J. Jacobi, N.A. Krotkov, L.N. Lamsal, Y. Liu, Z.F. Lu, R.V. Martini, G.G. Pfister, R.W. Pinder, R.J. Salawitch, and K.J. Wechti, Emissions estimation from satellite retrievals: A review of current capability. Atmospheric Environment, 2013. 77: p. 1011-1042.

43. Cui, Y.Y. and B. de Foy, Seasonal Variations of the Urban Heat Island at the Surface and the Near-Surface and Reductions due to Urban Vegetation in Mexico City. Journal of Applied Meteorology and Climatology, 2012. 51(5): p. 855-868.

42. De Foy, B., A.M. Smyth, S.L. Thompson, D.S. Gross, M.R. Olson, N. Sager, and J.J. Schauer, Sources of nickel, vanadium and black carbon in aerosols in Milwaukee. Atmospheric Environment, 2012. 59: p. 294-301.

41. de Foy, B., C. Wiedinmyer, and J.J. Schauer, Estimation of mercury emissions from forest fires, lakes, regional and local sources using measurements in Milwaukee and an inverse method. Atmospheric Chemistry and Physics, 2012. 12(19): p. 8993-9011.

40. Smyth, A.M., S.L. Thompson, D.S. Gross, J.J. Schauer, and B. de Foy, Particle sources in Milwaukee, WI studied with single-particle mass spectrometry. Abstracts of Papers of the American Chemical Society, 2012. 243.

39. De Foy, B., S.P. Burton, R.A. Ferrare, C.A. Hostetler, J.W. Hair, C. Wiedinmyer, and L.T. Molina, Aerosol plume transport and transformation in high spectral resolution lidar measurements and WRF-Flexpart simulations during the MILAGRO Field Campaign. Atmospheric Chemistry and Physics, 2011. 11(7): p. 3543-3563.

38. Quintana, R., J. Serrano, V. Gomez, B. de Foy, J. Miranda, C. Garcia-Cuellar, E. Vega, I. Vazquez-Lopez, L.T. Molina, N. Manzano-Leon, I. Rosas, and A.R. Osornio-Vargas, The oxidative potential and biological effects induced by PM10 obtained in Mexico City and at a receptor site during the MILAGRO Campaign. Environmental Pollution, 2011. 159(12): p. 3446-3454.

37. Aiken, A.C., B. de Foy, C. Wiedinmyer, P.F. DeCarlo, I.M. Ulbrich, M.N. Wehrli, S. Szidat, A.S.H. Prevot, J. Noda, L. Wacker, R. Volkamer, E. Fortner, J. Wang, A. Laskin, V. Shutthanandan, J. Zheng, R. Zhang, G. Paredes-Miranda, W.P. Arnott, L.T. Molina, G. Sosa, X. Querol, and J.L. Jimenez, Mexico city aerosol analysis during MILAGRO using high resolution aerosol mass spectrometry at the urban supersite (T0) - Part 2: Analysis of the biomass burning contribution and the non-fossil carbon fraction. Atmospheric Chemistry and Physics, 2010. 10(12): p. 5315-5341.

36. DeCarlo, P.F., I.M. Ulbrich, J. Crounse, B. de Foy, E.J. Dunlea, A.C. Aiken, D. Knapp, A.J. Weinheimer, T. Campos, P.O. Wennberg, and J.L. Jimenez, Investigation of the sources and processing of organic aerosol over the Central Mexican Plateau from aircraft measurements during MILAGRO. Atmospheric Chemistry and Physics, 2010. 10(12): p. 5257-5280.

35. Molina, L.T., S. Madronich, J.S. Gaffney, E. Apel, B. de Foy, J. Fast, R. Ferrare, S. Herndon, J.L. Jimenez, B. Lamb, A.R. Osornio-Vargas, P. Russell, J.J. Schauer, P.S. Stevens, R. Volkamer, and M. Zavala, An overview of the MILAGRO 2006 Campaign: Mexico City emissions and their transport and transformation. Atmospheric Chemistry and Physics, 2010. 10(18): p. 8697-8760.

34. Salcedo, D., T.B. Onasch, A.C. Aiken, L.R. Williams, B. de Foy, M.J. Cubison, D.R. Worsnop, L.T. Molina, and J.L. Jimenez, Determination of particulate lead using aerosol mass spectrometry: MILAGRO/MCMA-2006 observations. Atmospheric Chemistry and Physics, 2010. 10(12): p. 5371-5389.

33. Song, J., W. Lei, N. Bei, M. Zavala, B. de Foy, R. Volkamer, B. Cardenas, J. Zheng, R. Zhang, and L.T. Molina, Ozone response to emission changes: a modeling study during the MCMA-2006/MILAGRO Campaign. Atmospheric Chemistry and Physics, 2010. 10(8): p. 3827-3846.

32. Subramanian, R., G.L. Kok, D. Baumgardner, A. Clarke, Y. Shinozuka, T.L. Campos, C.G. Heizer, B.B. Stephens, B. de Foy, P.B. Voss, and R.A. Zaveri, Black carbon over Mexico: the effect of atmospheric transport on mixing state, mass absorption cross-section, and BC/CO ratios. Atmospheric Chemistry and Physics, 2010. 10(1): p. 219-237.

31. Voss, P.B., R.A. Zaveri, F.M. Flocke, H. Mao, T.P. Hartley, P. DeAmicis, I. Deonandan, G. Contreras-Jimenez, O. Martinez-Antonio, M.F. Estrada, D. Greenberg, T.L. Campos, A.J. Weinheimer, D.J. Knapp, D.D. Montzka, J.D. Crounse, P.O. Wennberg, E. Apel, S. Madronich, and B. de Foy, Long-range pollution transport during the MILAGRO-2006 campaign: a case study of a major Mexico City outflow event using free-floating altitude-controlled balloons. Atmospheric Chemistry and Physics, 2010. 10(15): p. 7137-7159.

30. Aiken, A.C., D. Salcedo, M.J. Cubison, J.A. Huffman, P.F. DeCarlo, I.M. Ulbrich, K.S. Docherty, D. Sueper, J.R. Kimmel, D.R. Worsnop, A. Trimborn, M. Northway, E.A. Stone, J.J. Schauer, R.M. Volkamer, E. Fortner, B. de Foy, J. Wang, A. Laskin, V. Shutthanandan, J. Zheng, R. Zhang, J. Gaffney, N.A. Marley, G. Paredes-Miranda, W.P. Arnott, L.T. Molina, G. Sosa, and J.L. Jimenez, Mexico City aerosol analysis during MILAGRO using high resolution aerosol mass spectrometry at the urban supersite (T0) - Part 1: Fine particle composition and organic source apportionment. Atmospheric Chemistry and Physics, 2009. 9(17): p. 6633-6653.

29. De Foy, B., N.A. Krotkov, N. Bei, S.C. Herndon, L.G. Huey, A.P. Martinez, L.G. Ruiz-Suarez, E.C. Wood, M. Zavala, and L.T. Molina, Hit from both sides: tracking industrial and volcanic plumes in Mexico City with surface measurements and OMI SO2 retrievals during the MILAGRO field campaign. Atmospheric Chemistry and Physics, 2009. 9(24): p. 9599-9617.

28. De Foy, B., M. Zavala, N. Bei, and L.T. Molina, Evaluation of WRF mesoscale simulations and particle trajectory analysis for the MILAGRO field campaign. Atmospheric Chemistry and Physics, 2009. 9(13): p. 4419-4438.

27. Fast, J., A.C. Aiken, J. Allan, L. Alexander, T. Campos, M.R. Canagaratna, E. Chapman, P.F. DeCarlo, B. de Foy, J. Gaffney, J. de Gouw, J.C. Doran, L. Emmons, A. Hodzic, S.C. Herndon, G. Huey, J.T. Jayne, J.L. Jimenez, L. Kleinman, W. Kuster, N. Marley, L. Russell, C. Ochoa, T.B. Onasch, M. Pekour, C. Song, I.M. Ulbrich, C. Warneke, D. Welsh-Bon, C. Wiedinmyer, D.R. Worsnop, X.Y. Yu, and R. Zaveri, Evaluating simulated primary anthropogenic and biomass burning organic aerosols during MILAGRO: implications for assessing treatments of secondary organic aerosols. Atmospheric Chemistry and Physics, 2009. 9(16): p. 6191-6215.

26. Johansson, M., C. Rivera, B. de Foy, W. Lei, J. Song, Y. Zhang, B. Galle, and L. Molina, Mobile mini-DOAS measurement of the outflow of NO2 and HCHO from Mexico City. Atmospheric Chemistry and Physics, 2009. 9(15): p. 5647-5653.

25. Koper, K.D., B. de Foy, and H. Benz, Composition and variation of noise recorded at the Yellowknife Seismic Array, 1991-2007. Journal of Geophysical Research-Solid Earth, 2009. 114.

24. Lei, W., M. Zavala, B. de Foy, R. Volkamer, M.J. Molina, and L.T. Molina, Impact of primary formaldehyde on air pollution in the Mexico City Metropolitan Area. Atmospheric Chemistry and Physics, 2009. 9(7): p. 2607-2618.

23. Rivera, C., G. Sosa, H. Wohrnschimmel, B. de Foy, M. Johansson, and B. Galle, Tula industrial complex (Mexico) emissions of SO2 and NO2 during the MCMA 2006 field campaign using a mobile mini-DOAS system. Atmospheric Chemistry and Physics, 2009. 9(17): p. 6351-6361.

22. Rutter, A.P., D.C. Snyder, E.A. Stone, J.J. Schauer, R. Gonzalez-Abraham, L.T. Molina, C. Marquez, B. Cardenas, and B. de Foy, In situ measurements of speciated atmospheric mercury and the identification of source regions in the Mexico City Metropolitan Area. Atmospheric Chemistry and Physics, 2009. 9(1): p. 207-220.

21. Bei, N., B. de Foy, W. Lei, M. Zavala, and L.T. Molina, Using 3DVAR data assimilation system to improve ozone simulations in the Mexico City basin. Atmospheric Chemistry and Physics, 2008. 8(24): p. 7353-7366.

20. De Foy, B., J.D. Fast, S.J. Paech, D. Phillips, J.T. Walters, R.L. Coulter, T.J. Martin, M.S. Pekour, W.J. Shaw, P.P. Kastendeuch, N.A. Marley, A. Retama, and L.T. Molina, Basin-scale wind transport during the MILAGRO field campaign and comparison to climatology using cluster analysis. Atmospheric Chemistry and Physics, 2008. 8(5): p. 1209-1224.

19. Herndon, S.C., T.B. Onasch, E.C. Wood, J.H. Kroll, M.R. Canagaratna, J.T. Jayne, M.A. Zavala, W.B. Knighton, C. Mazzoleni, M.K. Dubey, I.M. Ulbrich, J.L. Jimenez, R. Seila, J.A. de Gouw, B. de Foy, J. Fast, L.T. Molina, C.E. Kolb, and D.R. Worsnop, Correlation of secondary organic aerosol with odd oxygen in Mexico City. Geophysical Research Letters, 2008. 35(15).

18. Koper, K.D. and B. de Foy, Seasonal Anisotropy in Short-Period Seismic Noise Recorded in South Asia. Bulletin of the Seismological Society of America, 2008. 98(6): p. 3033-3045.

17. Lei, W., M. Zavala, B. de Foy, R. Volkamer, and L.T. Molina, Characterizing ozone production and response under different meteorological conditions in Mexico City. Atmospheric Chemistry and Physics, 2008. 8(24): p. 7571-7581.

16. Moffet, R.C., B. de Foy, L.T. Molina, M.J. Molina, and K.A. Prather, Measurement of ambient aerosols in northern Mexico City by single particle mass spectrometry. Atmospheric Chemistry and Physics, 2008. 8(16): p. 4499-4516.

15. Thornhill, D.A., B. de Foy, S.C. Herndon, T.B. Onasch, E.C. Wood, M. Zavala, L.T. Molina, J.S. Gaffney, N.A. Marley, and L.C. Marr, Spatial and temporal variability of particulate polycyclic aromatic hydrocarbons in Mexico City. Atmospheric Chemistry and Physics, 2008. 8(12): p. 3093-3105.

14. De Foy, B., W. Lei, M. Zavala, R. Volkamer, J. Samuelsson, J. Mellqvist, B. Galle, A.P. Martinez, M. Grutter, A. Retama, and L.T. Molina, Modelling constraints on the emission inventory and on vertical dispersion for CO and SO2 in the Mexico City Metropolitan Area using Solar FTIR and zenith sky UV spectroscopy. Atmospheric Chemistry and Physics, 2007. 7: p. 781-801.

13. Fast, J.D., B. de Foy, F.A. Rosas, E. Caetano, G. Carmichael, L. Emmons, D. McKenna, M. Mena, W. Skamarock, X. Tie, R.L. Coulter, J.C. Barnard, C. Wiedinmyer, and S. Madronich, A meteorological overview of the MILAGRO field campaigns. Atmospheric Chemistry and Physics, 2007. 7(9): p. 2233-2257.

12. Lei, W., B. de Foy, M. Zavala, R. Volkamer, and L.T. Molina, Characterizing ozone production in the Mexico City Metropolitan Area: a case study using a chemical transport model. Atmospheric Chemistry and Physics, 2007. 7: p. 1347-1366.

11. Molina, L.T., C.E. Kolb, B. de Foy, B.K. Lamb, W.H. Brune, J.L. Jimenez, R. Ramos-Villegas, J. Sarmiento, V.H. Paramo-Figueroa, B. Cardenas, V. Gutierrez-Avedoy, and M.J. Molina, Air quality in North America's most populous city - overview of the MCMA-2003 campaign. Atmospheric Chemistry and Physics, 2007. 7(10): p. 2447-2473.

10. Stevens, G., B. de Foy, J.J. West, and J.I. Levy, "Developing intake fraction estimates with limited data: Comparison of methods in Mexico City" (vol 41, pg 3672, 2007). Atmospheric Environment, 2007. 41(31): p. 6688-6689.

9. Velasco, E., B. Lamb, H. Westberg, E. Allwine, G. Sosa, J.L. Arriaga-Colina, B.T. Jobson, M.L. Alexander, P. Prazeller, W.B. Knighton, T.M. Rogers, M. Grutter, S.C. Herndon, C.E. Kolb, M. Zavala, B. de Foy, R. Volkamer, L.T. Molina, and M.J. Molina, Distribution, magnitudes, reactivities, ratios and diurnal patterns of volatile organic compounds in the Valley of Mexico during the MCMA 2002 & 2003 field campaigns. Atmospheric Chemistry and Physics, 2007. 7: p. 329-353.

8. De Foy, B., A. Clappier, L.T. Molina, and M.J. Molina, Distinct wind convergence patterns in the Mexico City basin due to the interaction of the gap winds with the synoptic flow. Atmospheric Chemistry and Physics, 2006. 6: p. 1249-1265.

7. De Foy, B., L.T. Molina, and M.J. Molina, Satellite-derived land surface parameters for mesoscale modelling of the Mexico City basin. Atmospheric Chemistry and Physics, 2006. 6: p. 1315-1330.

6. De Foy, B., J.R. Varela, L.T. Molina, and M.J. Molina, Rapid ventilation of the Mexico City basin and regional fate of the urban plume. Atmospheric Chemistry and Physics, 2006. 6: p. 2321-2335.

5. Johnson, K.S., B. de Foy, B. Zuberi, L.T. Molina, M.J. Molina, Y. Xie, A. Laskin, and V. Shutthanandan, Aerosol composition and source apportionment in the Mexico City Metropolitan Area with PIXE/PESA/STIM and multivariate analysis. Atmospheric Chemistry and Physics, 2006. 6: p. 4591-4600.

4. De Foy, B., E. Caetano, V. Magana, A. Zitacuaro, B. Cardenas, A. Retama, R. Ramos, L.T. Molina, and M.J. Molina, Mexico City basin wind circulation during the MCMA-2003 field campaign. Atmospheric Chemistry and Physics, 2005. 5: p. 2267-2288.

3. San Martini, F.M., J.J. West, B. de Foy, L.T. Molina, M.J. Molina, G. Sosa, and G.J. McRae, Modeling inorganic aerosols and their response to changes in precursor concentration in Mexico City. Journal of the Air & Waste Management Association, 2005. 55(6): p. 803-815.

2. De Foy, B. and W. Dawes, The design of improved smoothing operators for finite volume flow solvers on unstructured meshes. International Journal for Numerical Methods in Fluids, 2001. 36(8): p. 903-923.

1. De Foy, B. and W. Dawes, Unstructured pressure-correction solver based on a consistent discretization of the Poisson equation. International Journal for Numerical Methods in Fluids, 2000. 34(6): p. 463-478.