EOS Validation Activity

Validation Activity of Desert Encroachment Zone in Sub-Sahel Africa

Department of Atmospheric and Oceanic Science
University of Maryland, College Park

Department of Atmospheric and Oceanic Science


Observation Site

Scientific Observations





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Publications resulting from project:

1. Pinker, R. T., Idemudia, G.,and Aro, T. O., 1994. Characteristic Aerosol Optical Depths During the Harmattan Season on Sahara Africa. Geophys. Res. Lett., 21, (8), 685-688.

2. Miskolczi, F., T. O. Aro, M. Iziomon , R. T. Pinker, 1997. Surface Radiative Fluxes in Sub - Sahel Africa. Journal of Applied Meteorology. 36, (5), 521- 530.

3. Pinker, R. T., G. Pandithurai, B. N. Holben, O. Dubovik, and T. O. Aro, 2001. A dust outbreak episode in sub-Sahel West Africa. J. Geophys. Res., 106, No. D19, 22,923-22,930.

4. Pandithurai, G.,  R. T. Pinker, O. Dubovik, B. N. Holben, and T. O. Aro, 2001. Remote Sensing of Dust Optical Characteristics in Sub-Sahel, West Africa. J. Geophys. Res., 106, No. D22, 28,347-28,356.

5. Holben, B. N., D. Tanre, A. Smirnov, T. F.  Eck, I. Slutsker, N. Abuhassen, W. W. Newcomb, J. Schafer, B. Chatenet, F. Lavenue, Y. J. Kaufman, J. Vande Castle, A. Setzer, B. Markham, D. Clark, R. Frouin, R. Halthore, A. Karnieli, N. T. O'Neill, C. Pietras, R. T. Pinker, K. Voss, G. Zibordi, 2001. An emerging ground-based aerosol climatology: Aerosol Optical Depth from AERONET.  J. Geophys. Res., Vol. 106, 
No. D11, 12,067-12,097.

6. Smirnov, A., B. N. Holben, T. F. Eck, I. Slutsker, B. Chatenet and R. T. Pinker, 2002. Diurnal variability of aerosol optical depth observed at AERONET (Aerosol Robotic Network) sites. Geophys. Res. Lett., 29 (23), 2115, doi:10,1029/2002GL016305.

7. Pinker, R. T., Y. Zhao, C. Akoshile, J. Janowiak, and P. Arkin, 2005. A Diurnal and seasonal variability of rainfall in the sub-Sahel as seen from observations, satellites and a numerical model. Geophys. Res. Lett., VOL. 33, L07806, doi:10.1029/2005GL025192.

8. Nwofor O. K., Chineke T. C., Pinker R. T., 2007. Seasonal characteristics of spectral aerosol optical properties at a sub-Saharan site. Atmospheric Research, 85, 38-51.

9. Pinker, R. T., Liu, H, Osborne, S. R., and C. Akoshile, 2010. Radiative effects of aerosols in sub-Sahel Africa: Dust and biomass burning, J. Geophys. Res.-Atmos., 115, Article Number: D15205.


1. Pandithurai,  G., R. T. Pinker, B. N. Holben, T. Nakajima, T. Takamura and  S. Kaneta, 1999. Optical Characteristics of Aerosols Derived with two State-of-the Art Sky Radiometers. The ‘99 Kyoto Aerosol-Cloud Workshop, the CCSR COE Symposium/3rd Aerosol-Cloud  Remote  Sensing  Workshop.

2. Pinker, R. T., 1999. Validation of Remotely Sensed Data for Land Surface Hydrology Applications, Fall AGU 1999, San Francisco, December 15-12, 1999 (invited).

3. Pinker, R. T., 1999. Use of Remote Sensing in Climate Research: Need for Validation. University of Ilorin, Faculty of Science Seminar, University of Ilorin, Ilorin, Nigeria, September 1, 1999.

4. Pandithurai, G., R. T. Pinker, and B. N.  Holben, 1999.  Annual variation of aerosols optical properties in a semi-arid region as observed within the AERONET framework. 10th Conference on Atmospheric Radiation, Madison, Wisconsin, 26 June-2 July, 1999.

Selected Manuscripts/Presentations that use data from Ilorin :

1. Iziomon, M. G., Aro, T. O., 1995. Seasonal variations of diffuse solar radiation at Ilorin (8-degrees-32' N,4-degrees-46' E), Nigeria. Astrophysics and Space Science, 228 (1-2), 1-18.

2. Philipona, R., C. Fröhlich, and Ch. Betz, 1995. Characterization of pyrgeometers and the accuracy of atmospheric long-wave radiation measurements. Applied Optics, 34 (9), 1598-1605 (1995). http://dx.doi.org/10.1364/AO.34.001598

3. Iziomon, M. G., Aro, T. O., 1998. The diffuse fraction of global solar irradiance at a tropical location. Theoretical and Applied Climatology, 61, (1-2), 77-84.

4. Iziomon, M. G., Aro, T. O., 1999. On the annual and monthly mean diurnal variations of diffuse solar radiation at a meteorological station in West Africa. Meteorology And Atmosperic Physics, 69 (3-4), 223-230, 223-230, DOI: 10.1007/BF01030423.

5. Udo, S. O., and Aro, T. O., 1999. Measurement of global solar, global photosynthetically-active and downward infrared radiations at Ilorin, Nigeria. Renewable Energy, 17, (1), 113-122.

6. Udo, S. O. and T.O. Aro, 1999. Global PAR related to global solar radiation for central Nigeria. Agricultural and Forest Meteorology, 97, 21-31.

7. Udo, S. O., 2000. Quantification of Solar Heating of the Dome of a Pyrgeometer for a Tropical Location: Ilorin, Nigeria. NOTES AND CORRESPONDENCE, J. Atmos. and Oceanic Tech., 17, 995-.

8. Kenya Airways Crash, Ivory Coast, January 30, 2000

              Last updated February 7, 2000

AERONET data from Ilorin, Nigeria show high background aerosol optical depth (AOD) values of 0.5 (smoke?) preceding dust event. AOD begins to increase on 29th, with huge values (> 3.0) on 30th, then lower, yet still large values on the 31st. The angstrom coefficient is low (0.4) indicating dust. The Dubovik retrieved size distributions show the evolution of the aerosol before and during the passage of the dust cloud. They show a large coarse mode, 3-5 um diameter.


9. Udo, S. O. And T. O. Aro, 2000. New empirical relationships for determining global PAR from measurements of global solar radiation, infrared radiation or sunshine duration. International Journal of Climatology. 20, (10), 1265–1274.

10. Morcrette, J. J., 2001. The Surface Downward Longwave Radiation in ECMWF Forecast System.  ECMWF Technical Memorandum No. 339. 

11. Lesin, G. and U. Lohmann, 2003. GCM Aerosol Radiative Effects Using Geographically Varying Aerosol Sizes Deduced from AERONET Measurements. J. Atmos. Sci., 60.

12. Jeong, M. J. and Z. Li, D. A. Chu and S.-C. Tsay, 2003. Inter-Comparison and Synergy Between the Two Long-Term Global Aerosol Products Derived from AVHRR and TOMS. Thirteenth ARM Science Team Meeting Proceedings, Broomfield, Colorado, March 31-April 4, 2003

13. Kinne, S., U. Lohmann, J. Feichter, M. Schulz, C. Timmreck, S. Ghan, R. Easter, M. Chin, P. Ginoux, T. Takemura, I. Tegen, D. Koch, M. Herzog, J. Penner, G. Pitari, B. Holben, T. Eck, A. Smirnov, O. Dubovik, I. Slutsker, D. Tanre, O. Torres, M. Mishchenko, I. Geogdzhayev, D. A. Chu, Y. Kaufman, 2003. Monthly averages of aerosol properties: A global comparison among models, satellite data, and AERONET ground data. J. Geophys. Res., 108, 4634, doi:10.1029/2001JD001253.

14. Barkana, J., H. Kutiela P. Alpert, 2004. Climatology of Dust Sources in North Africa and the Arabian Peninsula, Based on TOMS Data. Indoor and Built Environment, 13, 407-419

15. Chin, M., A. Chu, R Levy, L Remer, Y Kaufman, 2004. Aerosol distribution in the Northern Hemisphere during ACE-Asia: Results from global model, satellite observations, and Sun photometer measurements. J. Geophys. Res., 109, D23S90, doi:10.1029/2004JD004829.

16. Hsu, N. Christina, Si-Chee Tsay, Michael D. King, Senior Member, IEEE, and Jay R. Herman, 2004. Aerosol Properties Over Bright-Reflecting Source Regions. IEEE Transactions on Geoscience and Remote Sensing, 42 (3), MARCH 2004, 557. 

17. Ogunjobi, K. O., Z. He, K.W. Kim, Y. J. Kim, 2004. Aerosol optical depth during episodes of Asian dust storms and biomass burning at Kwangju, South Korea. Atmospheric Environment, 38 (2004) 1313–1323.

18. Babatunde, E. B., O. A. Falaiye, C. C. Uhuegbu, 2005. Simulated reflected sw-radiation and its characteristic variation at Ilorin, Nigeria. Nigerian Journal of Physics, 17. 

19. Ginoux, P., Larry W. Horowitz, V. Ramaswamy, Igor V. Geogdzhayev, Brent N. Holben, Georgiy Stenchikov, and Xuexi Tie, 2006. Evaluation of aerosol distribution and optical depth in the Geophysical Fluid Dynamics Laboratory coupled model CM2.1 for present climate. J. Geophys. Res., 111, D22210, doi:10.1029/2005JD006707.

20. Grey, W. M. F., Peter R. J. North, Sietse O. Los, and Ross M. Mitchell, 2006. Aerosol Optical Depth and Land Surface Reflectance From Multiangle AATSR Measurements: Global Validation and Intersensor Comparisons. IEEE Transactions on Geoscience and Remote Sensing, 44 (8), August 2006.

21. Anuforom, A. C., | Akeh, L. E., Okeke, P. N., Opara, F. E., 2007. Inter-annual variability and long-term trend of UV-absorbing aerosols during Harmattan season in sub-Saharan West Africa. Atmospheric Environment, ISSN: 13522310, 41 (7), 1550-1559.

22. Braak, R., Ben Veihelmann, Pepijn Veefkind, 2007. OMI Multiwavelength Aerosol Product Validation Status. Bremen Aerosol Workshop, 22 June 2007. 

23. Ogunjobi, K. O., 2007. Variability of column-integrated aerosol turbidity and radiative parameters in Sub_saharan West Africa. Research Journal of Applied Sciences, 2 (4), 505-511.

24. Ogunjobi, K.O., Z. He, C. Simmer, 2007. Spectral aerosol optical properties from AERONET Sun-photometric measurements over West Africa. Atmospheres, doi:10.1016/j..2007.10.004. 

25. Myhre, G., C. R. Hoyle, T. F. Berglen, B. T. Johnson, and J. M. Haywood, 2008. Modeling of the solar radiative impact of biomass burning aerosols during the Dust and Biomass-burning Experiment (DABEX). J. Geophys. Res., 113, D00C16, doi:10.1029/2008JD009857.

26. Ogunjobi, K. O., V. Ajayi, I. Balogun, J. Omotosho and Z. He, 2008. The synoptic and optical characteristics of the harmattan dust spells over Nigeria. Theoretical and Applied Climatology , 93 (1-2), 91-105, DOI: 10.1007/s00704-007-0332-2.

27. Ogunjobi, K. O., Z. He, C. Simmer, 2008. Spectral aerosol optical properties from AERONET Sun-photometric measurements over West Africa. Atmospheric Research, 88, (2), May 2008, 89-107.

28. Vidot, J., R. Santer and O. Aznay, 2008. Evaluation of the MERIS aerosol product over land with AERONET. Atmos. Chem. Phys., 8, 7603–7617, 2008. www.atmos-chem-phys.net/8/7603/2008/

29. Babatunde, E. B., C. O. Akoshile, O. A. Falaiye, A.A. Willoughby, T.B. Ajibola, A. Adimula, T. O. Aro, 2009. Observation bio-effect of SW-global solar radiation in Ilorin in the tropics. Advances in Space Research 43 (2009) 990–994.

30. Basart, S., C. P´erez, E. Cuevas, J. M. Baldasano, and G. P. Gobbi, 2009. Aerosol characterization in Northern Africa, Northeastern Atlantic, Mediterranean Basin and Middle East from direct-sun AERONET Observations. Atmos. Chem. Phys., 9, 8265–8282, 2009.

31. Cebecauer, T., Richard Perez and Marcel Suri, 2009. Comparing Performance of SOLARGIS and SUNY Satellite ModelsUsing Monthly and Daily Aerosol Data. Proceedings of the ISES Solar World Congress 2011, 28 August – 2 September 2011, Kassel, Germany.

32. Haywood, J. M. et al., 2009. Pyrogenic aerosol: current modelling capabilities in the Met Office. www.ecmwf.int/newsevents/meetings/

33. Okpani, P. E., 2009. Determination of Aerosol Mass Loading in Ilorin Using Remote Sensing Technique. The Pacific Journal of Science and Technology, 10 (2). http://www.akamaiuniversity.us/PJST

34. Quinn, K. M., 2009. Impact of Aerosols on Scene Collection and Scene Correction. Naval Postgraduate School, Monterey, California (Thesis). Thesis Advisor: Philip A. Durkee.

35. Ben-Ami, Y., I. Koren, Y. Rudich, P. Artaxo, S. T. Martin, and M. O. Andreae, 2010. Transport of North African dust from the Bod´el´e depression to the Amazon Basin: a case study. Atmos. Chem. Phys., 16 August 2010.

36. Eck, T. F., B. N. Holben, A. Sinyuk, R. T. Pinker, P. Goloub, H. Chen, B. Chatenet, Z. Li,  R. P. Singh, S. N. Tripathi, J. S. Reid, D. M. Giles, O. Dubovik, N. T. O’Neill, A.  Smirnov, P. Wang, and X. Xia, 2010. Climatological aspects of the optical properties of fine/coarse mode aerosol mixtures. J. Geophys. Res.-Atmos., 115, Article Number: D19205. 

37. Eck.,T. and the AERONET Team, 2010. AERONET-An Internationally Federated Network. Aerosol Observability. Workshop – Monterey April 28, 2010.

38. Kahn, R. A., Barbara J. Gaitley, Michael J. Garay, David J. Diner, Thomas F. Eck, Alexander Smirnov, and Brent N. Holben, 2010. J. Geophys. Res., VOL. 115, D23209, doi:10.1029/2010JD014601.

39. Lee, Y. H., and P. J. Adams, 2010. Evaluation of aerosol distributions in the GISS-TOMAS global aerosol microphysics model with remote sensing observations. Atmos. Chem. Phys., 10, 2129–2144, 2010

40. Nwofor, Okey K., 2010. Rising Dust Aerosol Pollution at Ilorin in the Sub-sahel Inferred from
10-year Aeronet Data: Possible Links to Persisting Drought Conditions. Research Journal of Environmental and Earth Sciences 2(4): 216-225, 2010. ISSN: 2041-0492. Maxwell Scientific Organization, 2010

41. Ogunjobi, K. O., Y. J. Kim, T. O. Aro, and R. T. Pinker, 2010. Column-Integrated Spectral Aerosol Optical Properties in Saharan and Asian Dust Outbreak Episodes Using Ground-Based Data. Mali Symposium on Applied Sciences, Paper/Article: 099.

42. Cebecauer T., Perez R., Suri M., 2011. Comparing performance of SolarGIS and SUNY satellite models using monthly and daily aerosol data. Proceedings of the ISES Solar World Congress 2011, 28 August–2 September 2011, Kassel, Germany.

43. Cebecauer, T., Marcel Suri, 2011. GEMS/MACC aerosols in solar radiation modeling for energy applications. MACC Conference on Monitoring and Forecasting Atmospheric Composition Utrecht, 23-27 May 2011.

44. Gueymard, C. H., 2011. Uncertainties in Modeled Direct Irradiance Around the Sahara as Affected by Aerosols: Are Current Datasets of Bankable Quality? J. Sol. Energy Eng., 133 (3). doi:10.1115/1.4004386.

45. Kim, D., Chin, M., Yu, H., Eck, T. F., Sinyuk, A., Smirnov, A., and Holben, B. N., 2011.  Dust optical properties over North Africa and Arabian Peninsula derived from the AERONET dataset, Atmos. Chem. Phys., 11, 10733-10741, doi:10.5194/acp-11-10733-2011.

46. Knippertz, P., Andreas H. Fink, Robert Schuster, Jorg Trentmann, Jon M. Schrage, and Charles Yorke, 2011. Ultra low clouds over the southern West African monsoon region. Geophys. Res. Lett., 38, L21808, doi:10.1029/2011GL049278.

47. Sundar A. Christopher, Pawan Gupta, Ben Johnson, Catherine Ansell, Helen Brindley and Jim Haywood, 2011. Multi-sensor satellite remote sensing of dust aerosols over North Africa during GERBILS. Quarterly Journal of the Royal Meteorological Society, Volume 137, Issue 658, July 2011 Part A, Pages: 11681178.

48. Von Hoyningen-Huene, W., J. Yoon, M. Vountas, L. G. Istomina, G. Rohen, T. Dinter, A. A. Kokhanovsky, and J. P. Burrows, 2011. Atmospheric Measurement Techniques Retrieval of spectral aerosol optical thickness over land using ocean color sensors MERIS and SeaWiFS. Atmos. Meas. Tech., 4, 151-171. doi:10.5194/amt-4-151-2011.

49. Barcelona Dust Forecast Center

In May 2013, the Sixty-fifth Session of the WMO Executive Council (EC-65) designates the consortium formed by the Spanish State Meteorological Agency (AEMET) and the Barcelona Supercomputing Center (BSC-CNS) to create in Barcelona the first Regional Specialized Meteorological Center with activity specialization on Atmospheric Sand and Dust Forecast (RSMC-ASDF): doc EC-65-d04-3(1). The Center shall operationally generate and distribute predictions for Northern Africa (north of equator), Middle East and Europe.

            Ilorin, Nigeria is one of the evaluation sites.

50. Babatunde, E. B., C. O. Akoshile, O. A. Falaiye, and T. B. Ajibola, Global Solar Radiation Annual
Profile, Causes and Seasonal Effects, at Ilorin, Nigeria, 2013. Covenant Journal of Physical and
Life Sciences (CJPL) Vol. 1, No. 1, August, 2013.

51.Falaiye, O. A., Yakubu, A. T., Aweda, F. O., and Abimbola, O. J., 2013. Minerological characteristics of Harmattan dust in Ilorin, sub-Sahara Africa. Ife Journal of Science vol.15, no.1.

The pyrgeometers in use at Ilorin participated in international calibration campaigns:

1. Philipona, R., E. G. Dutton, T. Stoffel, J. Michalsky, I. Reda, A. Stifter, P. Wendling, N. Wood, S. A. Clough, E. J. Mlawer, G. Anderson, H. E. Revercomb, and T. R. Shippert, 2001. Atmospheric longwave irradiance uncertainty: Pyrgeometers compared to an absolute sky-scanning radiometer, atmospheric emitted radiance interferometer, and radiative transfer model calculations. J. Geophys. Res.-Atmos. 106 (D22): 28129-28141 Nov. 27 2001.

Maintained by Chuan Li