maac Research Group

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Modeling and Analysis of Atmospheric Composition


Postdoctoral Researchers:

Vanessa Brocchi (Ph.D., 2017 University of Orleans). Her research revolves around identifying emergent patterns of anthropogenic signatures over growing urban agglomeration and megacities in Africa, through regional-to-global chemical transport modeling, and analysis of remotely-sensed and airborne-based observations of air quality in the region. She is interested in tracking air quality over these cities (incl. gas flaring and venting activities) especially as these cities grow and socio-economically developed in the near future. An overarching goal of her research is to quantify the contributions of these cities to changes in global air quality and climate.


Brocchi, V., A.F. Arellano, W. Tang, and B. Gaubert (2020), Impact of African Urban Agglomerations to Global Air Quality, Poster 1283, poster presented at 22nd Conference on Atmospheric Chemistry as part of the AMS 100th Annual Meeting, Boston, MA, 12-16 Jan.

Brocchi, V., A.F. Arellano, W. Tang, and B. Gaubert (2019), Understanding Anthropogenic Combustion in Major Cities of Africa from Multiple Data Streams, Abstract A31E-05, talk presented at 2019 AGU Fall Meeting, San Francisco, CA, 9-13 Dec. 

Kavitha Mottungan (Ph.D., 2019 University of Kerala). Her research revolves around substantiating synergies between co-emitted products of anthropogenic combustion (e.g., CO, NO2, CO2, CH4). There is unique opportunity to augment our current observing system (OCO-2, GOSAT) to monitor fossil fuel CO2 emissions and understand the strong chemical coupling between O3 precursors and CH4 abundance and variability. She is interested in elucidating the utility of air quality observations (CO, NO2) especially remotely-sensed retrieval products (MOPITT, IASI, OMI, TROPOMI) in disentangling the anthropogenic sources of greenhouse gases.


Mottungan, K., A.F. Arellano, V. Brocchi and B. Gaubert (2020). “Utilizing the synergies between air quality and greenhouse gas measurements in constraining anthropogenic CO2 and CH4 over Sub-Saharan Africa”. Abstract 670. Presented at IWGGMS-16, 2-5 June 2020 (Virtual Conference).




Sunyi Yuan (M.S. 2019 to present). Sunyi's research revolves around atmospheric dispersion of pesticide particles in Arizona. He uses an ensemble framework consisting of CALPUFF model driven by WRF meteorology to study the fate of particles that are emitted from agricultural pesticide applications.  



Yuan, S., A. Arellano, and M. Furlong (2020), Modeling atmospheric dispersion of pesticide particles in Yuma County and Maricopa County, poster presented at 2020 Virtual El Dia, Tucson, AZ, 20 Apr.



Chayan Roychoudhury (Ph.D. 2020 to present). Chayan's research revolves around understanding the role of light-absorbing aerosols (LAP: black carbon, dust, brown carbon) on the regional climatic changes in High Mountain Asia (HMA) in recent decades. He is using WRF-Chem and satellite retrievals of AOD from MODIS to identify the relative importance of different sources affecting HMA, and assess the impact of LAP deposition on snowmelt, runoff characteristics, and water resources in downstream Asian regions. 



John McKinnon (Ph.D. 2020 to present). John's research revolves around developing more effective algorithms for data assimilation and inverse analysis of atmospheric composition measurements. He uses ground-, aircraft-, and remote sensing-based datasets in conjunction with chemical transport modeling to infer emissions of key air quality and greenhouse trace gases.


Christoforus Bayu Risanto (Ph.D. 2016 to present, Co-Advised by Prof. Chris Castro). Bayu's research revolves around numerical weather prediction (NWP) in semi-arid to arid environment and complex terrain. He focuses on finding solutions to improve forecast of rainfall through data assimilation  and ensemble modeling approaches.  



Risanto, C.B., C. Castro, A.F. Arellano, L. Mendoza-Fierro, and J.M. Moker (2020), Forecasting North American Monsoon Precipitation with Data Assimilation, Abstract 10.2, talk presented at 24th Conference on Integrated Observing and Assimilation Systems for the Atmosphere, Oceans, and Land Surface (IOAS-AOLS) as part of the AMS 100th Annual Meeting, Boston, MA, 12-16 Jan.

Risanto, C. B, C. L. Castro, H. I. Chang, I. Hoteit, and T. M. Luong (2020), Simulating Extreme Precipitation over the Arabian Peninsula Using a Convective-Permitting Subseasonal Reforecast Product. Abstract 14C.6, talk presented at 30th Conference on Weather Analysis and Forecasting (WAF)/26th Conference on Numerical Weather Prediction (NWP), as part of the AMS 100th Annual Meeting, Boston, MA, 12-16 Jan.

Chang H.-I, C. L. Castro, T. Luong, C. B. Risanto (2019),  Extreme weather impact assessments in arid and semi-arid regions through sub-seasonal regional climate forecasting. Abstract A53E-04, talk presented at A53E - Regional Climate: Modeling, Analysis, and Impacts I, as part of the AGU 100th Fall Meeting, San Francisco, CA, 9-13 December.

Chang, H.-I, C. L. Castro, I. Hoteit, C. B. Risanto, T. Luong, R. Attada (2019), Extreme weather impact assessment in Saudi Arabia and operational sub-seasonal forecasting. Poster at LATSIS SYMPOSIUM 2019, High-Resolution Climate Modeling:
Perspectives and Challenges, at ETH, Zurich, Switzerland, 21-23 August 2019.

Risanto, C.B., C.L. Castro, J.M. Moker, A.F. Arellano, D.K. Adams, L.M. Fierro, and C.M. Minjarez Sosa (2019), Evaluating Forecast Skills of Moisture from Convective-Permitting WRF-ARW Model during 2017 North American Monsoon Season, Atmosphere, 10(11), 694, 10.3390/atmos10110694, electronic journal.

Risanto, C.B., C. Castro, J.M. Moker, A.F. Arellano, D.K. Adams, and L.M. Fierro (2019), CAZMEX 2017: Improving Monsoon Precipitation Forecast in Northwest Mexico and Southwest U.S., Abstract 18.4, talk presented at 23rd Conference on Integrated Observing and Assimilation Systems for the Atmosphere, Oceans, and Land Surface (IOAS-AOLS) as part of the AMS 99th Annual Meeting, Phoenix, AZ, 6-10 Jan.



James Moker (Ph.D. 2013-2019, Co-Advised by Prof. Chris Castro and Yolanda Serra (now at UW) ). Now a Meteorologist Technician US Air Force (Luke AFB). His research at UA revolved around improving convective precipitation forecasts in the North American Monsoon region through ensemble-based data assimilation of ground GPS-derived total precipitable water (PWV).

Jamie successfully defended his dissertation on April 15, 2019.


Moker, J.M., C.L. Castro, Y.L. Serra, A.F. Arellano, and D.K. Adams (2017), Convective-permitting hindcast simulations during The North American Monsoon GPS Transect Experiment 2013: Establishing Baseline Model Performance Without Data Assimilation, J. Appl. Meteor. Climatol., doi:10.1175/JAMC-D-17-0136.1, electronic journal.

Serra, Y., D. Adams, C. Minjares-Sosa, J. Moker, A. Arellano, C. Castro, A. Quintanar, L. Alatorre, A. Granados, E. Vasqueze, K. Holub, and C. DeMets, (2016), The North American Monsoon GPS Transect Experiment 2013, Bull. Am. Meteorol. Soc., 2103-115, doi:10.1175/BAMS-D-14-00250.1.electronic journal.

Moker, J., Y. Serra, C. Castro and A.F. Arellano (2015), Impact of Precipitable Water on Forecasting the 2013 North American Monsoon, Abstract 8.4, presented at  the 29th Conference on Hydrology as part of the AMS 95rd Annual Meeting, 3-8 Jan.

Wenfu Tang (Ph.D., 2016 to 2019; M.S., 2014-2016). Now an ASP Postdoctoral Fellow at National Center for Atmospheric Research (NCAR). Her research at UA revolved around understanding fire dynamics, emissions, and the impact of combustion on atmospheric composition, using smoke and combustion signatures observed from satellites (CO, CO2, NO2, AOD, SO2), KORUS-AQ field campaign, regional to global chemical transport modeling (CESM/CAM-Chem, WRF-Chem) and data assimilation.

Wenfu successfully defended her dissertation on March 29, 2019. 


Tang, W., Gaubert, B., Emmons, L., Choi, Y., DiGangi, J. P., Diskin, G. S., Xu, X., He, C., Worden, H., Tilmes, S., Buchholz, R., Halliday, H. S., and Arellano, A. F.: On the relationship between tropospheric CO and CO2 during KORUS-AQ and its role in constraining anthropogenic CO2, Atmos. Chem. Phys. Discuss.,, in review, 2020

Tang, W., A.F. Arellano, B. Gaubert, K. Miyazaki, and H. Worden (2019), Satellite Data Reveals a Common Combustion Emission Pathway for Major Cities in China, Atmos. Chem. Phys., 19, 4269-4288, 10.5194/acp-19-4269-2019, electronic journal.

Tang, W., L.K. Emmons, A.F. Arellano, B. Gaubert, C. Knote, S. Tilmes, R.R. Buchholz, G.G. Pfister, G. Diskin, D.R. Blake, N.J. Blake, J.P. DiGangi, Y. Choi, J-H. Woo, C. He, J.R. Schroeder, I. Suh, H-J. Lee, H-Y Jo, Y. Kanaya, J. Jung, Y. Lee, and D. Kim (2019), Source Contribution to Carbon Monoxide Concentrations during KORUS-AQ based on CAM-Chem model applications, J. Geophys. Res., 10.1029/2018JD029151, electronic journal.

Tang, W., B. Gaubert, A.F. Arellano, L.K. Emmons,  J. DiGangi, Y. Choi, G. Diskin, and H. Halliday (2018), Tracking Fossil Fuel Emissions in East Asia by Combining Model Simulations, Satellite Observations, and Field Measurements of the CO-to-CO2 Ratio, Abstract A52A-06, talk presented at 2018 AGU Fall Meeting, Washington DC, 10-14 Dec. 

Tang, W., A.F. Arellano, B. Gaubert, K. Miyazaki, and H. Worden (2018), Satellite Data Reveals a Common Combustion Emission Pathway for Major Cities in China, Atmos. Chem. Phys. Discuss., 10.5194/acp-2018-1121, electronic journal.

Tang, W., Arellano, A. F., DiGangi, J. P., Choi, Y., Diskin, G. S., Agustí-Panareda, A., Parrington, M., Massart, S., Gaubert, B., Lee, Y., Kim, D., Jung, J., Hong, J., Hong, J.-W., Kanaya, Y., Lee, M., Stauffer, R. M., Thompson, A. M., Flynn, J. H., and Woo, J.-H. (2018), Evaluating High-Resolution Forecasts of Atmospheric CO and CO2 from a Global Prediction System during KORUS-AQ Field Campaign, Atmos. Chem. Phys., 18, 11007-11030, electronic journal.

Tang, W., L.K. Emmons,  A.F. Arellano, and B. Gaubert (2018), CO Source Contributions and Combustion Characteristics during KORUS-AQ, AOGS Annual Meeting, Honolulu, HI, USA, 3-8, June.

Tang, W., B. Gaubert,  A.F. Arellano,  L.K. Emmons (2018), Tracking CO2 in CAM-chem/CESM, CESM workshop 2018, Boulder, CO, USA, 18-20, June.

Tang, W.,  A.F. Arellano, L.K. Emmons, and B. Gaubert (2018), Ensemble Simulation of Anthropogenic and Biomass Burning CO2 and CO in CAM-chem, Abstract 1102, poster presented at 20th Conference on Atmospheric Chemistry as part of the AMS 98th Annual Meeting, Austin, TX, 7-11 Jan.

Tang, W., A.F. Arellano, Y. Choi, J.P. DiGangi, J-H. Woo, G.S. Diskin, A. Agusti-Panareda, M. Parrington, S. Massart, M. Lee, Y. Kanaya, J. Jang, Y. Lee, J. Hong, J.H. Flynn, A.M. Thompson, and D-B. Kim  (2017), Joint Evaluation of Copernicus Atmosphere Monitoring Service (CAMS) High-resolution Global Near-Real Time CO and CO2 Forecasts during KORUS-AQ Field Campaign, Abstract A53A-2210, poster presented at 2017 AGU Fall Meeting, New Orleans, LA, 11-15 Dec.

Tang, W., and A.F. Arellano (2017), Investigating Combustion and Emission Trends in Megacities through Synthesis of Combustion Signatures Using Multiple Dataset, Abstract 684, presented at  the 19th Conference on Atmospheric Chemistry as part of the AMS 97th Annual Meeting, 23-26 Jan.

Tang, W., and A. Arellano  (2017), Investigating the dominant characteristics of fires across the Amazon during 2005–2014 through satellite data synthesis of combustion signatures, J. Geophys. Res., 121, doi:10.1002/2016JD025216, electronic journal.

Tang, W., and A. Arellano (2016), Investigating Combustion and Emission Trends in Megacities trhough Synthesis of Combustion Signatures Using Mulitple Datasets, Abstract 1.040 presented at 2016 International Global Atmospheric Chemistry (IGAC) Project Science Conference, Breckenridge, CO, 26-30 Sep.

Tang, W., A. Arellano, and M. Deeter (2015), Joint Analysis of Bulk Wildfire Characteristics from Multiple Satellite Retrievals, Abstract A23A-0275 presented at 2015 Fall Meeting, AGU, San Francisco, Calif., 14-18 Dec.

Tang, W., A. Arellano, A. Raman, and M. Deeter (2015), A Comparative Analysis on the Temporal and Spatial Distribution of Fire Characteristics in the Amazon and Equatorial Southern Africa Using Observations from Space, Abstract EGU2015-637 presented at 2015 EGU Meeting, Vienna, Austria, 12-17 Apr.


Aishwarya Raman (Ph.D. 2013 to 2017). Now a Research Scientist at NASA GMAO/SSAI. Her research at UA revolved around  understanding the mechanisms driving and controlling extreme air quality (AQ) events in southern Arizona and across United States, in order to improve predictive capability of models for extreme AQ events (dust storms and wildfires), in conjunction with observations of weather and AQ from space.

She finished her M.S. in Atmospheric Science in 2013. Aishwarya Raman won best oral presentation award for the 15th Conference on Atmospheric Chemistry at the 2013 American Meteorological Society (AMS) meeting. She has been featured in the Joint Center for Satellite Data Assimilation Quarterly Newsletter as one of the students who participated in the JCSDA's summer colloquium in 2012.


Raman, A., and A.F. Arellano (2017), Spatial and temporal variations in characteristic ratios of elemental carbon with carbon monoxide and nitrogen oxides across the United States,  Envi. Sci. Tech., 51(21), 6829-6838, doi:10.1021/acs.est.7b00161, electronic journal.

Raman, A.,  A.F. Arellano and R. Kumar (2016), Estimating black carbon concentrations from combustion tracers: synergistic perspective using in-situ measurements, multi-satellite retrievals, and chemical transport model, Abstract A52B-02 presented orally at 2016 Fall Meeting, AGU, San Francisco, Calif., 12-16 Dec.

Arellano, A.F., A. Raman, J. Brost, and A. Sorrooshian (2016), Modeling and observations of dust aerosols during the North American Monsoon, Abstract A41N-08 presented orally at 2016 Fall Meeting, AGU, San Francisco, Calif., 12-16 Dec.

Kumar, R., A. Raman, L. Delle Monache, S. Alessandrini, W.Y. Cheng, B. Gaubert, and A. Arellano (2016), A novel method to improve MODIS AOD retrievals in cloudy pixels using an analog ensemble approach, Abstract A31E-0091 presented at 2016 Fall Meeting, AGU, San Francisco, Calif., 12-16 Dec.

Raman, A., A.F. Arellano, and A. Sorooshian (2016), Decreasing aerosol loading in the North American Monsoon region, Atmosphere,7(2), 24;doi:10.3390/atmos7020024, electronic journal.

Lopez, D., M. Rabbani, E. Crosbie, A. Raman, A. Arellano, and A. Sorooshian (2015), Frequency and Character of Extreme Aerosol Events in the Southwestern United States: A Case Study Analysis in Arizona, Atmosphere, 7(1), 1; doi:10.3390/atmos7010001, electronic journal.

Raman, A., A. Arellano, and R. Kumar (2015), Using Combustion Tracers to Estimate Surface Black Carbon Distributions in WRF-Chem, Abstract A33D-0207 presented at 2015 Fall Meeting, AGU, San Francisco, Calif., 14-18 Dec.

Raman, A., A.F. Arellano, and R. Kumar (2014), Using chemical ratios to disentangle sources of particulate matter pollution: Implications for population exposure and mortality, International Global Atmospheric Chemistry (IGAC) Science Conference on Atmospheric Chemistry, Natal, Brazil, 22-26 Sep.

Raman, A.,A.F. Arellano, and R. Kumar (2014), Quantifying regional emissions using WRF-Chem tagged tracers: Implications for cross-state pollution transport and extreme air quality events, 15th Annual WRF Users' Workshop, Boulder, CO, 23-27 June.

Raman, A., A.F. Arellano, and J.J. Brost (2014), Revisiting haboobs in the southwestern United States: An observational case study of the 5 July 2011 Phoenix dust storm, Atmos. Environ., 89, 179-188, doi: 10.1016/j.atmosenv.2014.02.026, electronic journal.

Raman, A., and A.F. Arellano, (2013), A WRF/CHEM sensitivity study towards high resolution air qualityforecasting for southwestern United States, 14th Annual WRF Users' Workshop, Boulder, CO, 24-28 June.

Raman, A.*, and A.F. Arellano (2013), Modeling and Data Analysis of 2011 Phoenix Dust Storm, Abstract 5.5, presented at  the 15th Conference on Atmospheric Chemistry as part of the AMS 93rd Annual Meeting, 6-10 Jan.

Raman, A., and A.F. Arellano (2012), Investigating Massive Dust Events Using a Coupled Weather-Chemistry Model, Abstract A33E-207 presented at the 2012 Fall Meeting, AGU, San Francisco, Calif., 3-7 Dec.


Sam Silva (UA AMP 2012 to 2014).  Finished his Ph.D. at MIT in Summer 2019). Now a Linus Pauling Distinguished Postdoctoral Fellow at Pacific Northwest National Laboratory (PNNL). His research at UA revolved around satellite data analysis of atmospheric constituents from combusted-related processes. His work focused on the synergistic use of satellite retrievals of CO2, CO, and NO2 to investigate combustion characteristics in urban environments and to further provide important constraints on our current estimates of anthropogenic sources of CO2.

He finished his B.S. in Physics in 2013 at University of Arizona.



Silva, S. and A.F. Arellano (2017), Characterizing regional-scale combustion using satellite retrievals of CO, NO2 and CO2, Remote Sensing, 9(7), 744; doi:10.3390/rs9070744, electronic journal.

Silva, S.J., A.F. Arellano, and H. Worden (2014), Exploring the utility of satellite-based CO2/CO and CO2/NO2 sensitivities over urban regions and point sources as constraints on anthropogenic combustion, Paper presented at the International Workshop on Greenhouse Gas Measurements from Space (IWGGMS-9), Noordwijk, The Netherlands, 05-07 May.

A.F. Arellano and Sam Silva (2014), Combustion signatures as seen from space: Implications for tracking anthropogenic CO2, OCO-2 Applications Workshop, JGCRI, Maryland, 3-4 Apr.

Silva, S., A. Arellano, M. Yang, and E. Crosbie (2013), Exploring the utility of satellite-based CO2-CO-NO2 sensitivities over urban regions and point sources as constraints on anthropogenic combustion, Abstract A53E-0232 presented at 2013 Fall Meeting, AGU, San Francisco, Calif., 9-13 Dec.

Silva, S., A.F. Arellano, and H. Worden  (2013), Towards anthropogenic combustion emission from space-based analysis of urban CO2/CO sensitivity, Geophys. Res. Lett., 4049714976, doi: 10.1002/grl.50954, electronic journal.

Silva, S.J., A.F. Arellano, and H. Worden (2013), Patterns of CO2 Sensitivity to CO from Space and their Implications for Carbon Monitoring, Paper presented at the International Workshop on Greenhouse Gas Measurements from Space (IWGGMS-9), Yokohama, Japan, 29-31 May.

Silva, S.J., and A.F. Arellano (2012), Towards an Analysis of CO2 - CO Correlation Patterns Over Megacities, Abstract A43L-07 presented at the 2012 Fall Meeting, AGU, San Francisco, Calif., 3-7 Dec.

Student Opportunities:

Please contact me if you are interested in working on special topics in chemical data assimilation, inverse modeling, and data analysis. An ample background in programming (e.g. matlab, fortran, idl) with interest in the application of mathematics/statistics to problems in atmospheric sciences is desirable.