# Bogdan Nita

**Bogdan G. Nita** is being honored with the J. Clarence Karcher Award for contributions to exploration seismology, specifically the removal of free-surface and internal multiples using the inverse scattering approach. Nita received his doctorate from the University of Texas at Dallas in 2001 and is now an assistant professor of mathematical sciences at Montclair State University in Montclair, New Jersey and is serving as associate editor of the International Journal of Applied Mathematics and Statistics. He has authored or co-authored 14 papers in refereed journals and contributed four abstracts for SEG or EAGE meetings.

## Biography Citation for the J. Clarence Karcher Award

*Contributed by Adriana Citlali Ramirez*

It is a privilege and honor to write this citation for Bogdan Nita for the J. Clarence Karcher Award. This award recognizes his technical contributions in the area of forward and inverse scattering for multiple attenuation and depth imaging.

A native of Romania, Bogdan obtained a BS in mathematics in 1997 from the University of Bucharest. Ieronim Mihaila and Varujan Pambuccian supervised his thesis “On the geometry of Schwarzschild spaces.” Bogdan was the recipient of the Romanian Ministry of Education Scholarship and Fellowship and a travel award from the Soros Foundation for an Open Society. He left Romania to pursue doctoral studies on applied mathematics at the University of Texas at Dallas (UTD) in the United States. His PhD advisor is one of the most prolific and internationally recognized mathematicians working on general relativity, Ivor Robinson. Bogdan obtained his doctorate in 2001 for his research on pure gravitational radiation with twisting rays. These accomplishments would have been enough to guarantee a satisfactory career in applied mathematics; nevertheless, Bogdan decided to become a multidisciplinary scientist and, in 2001, joined the Mission-Oriented Seismic Research Program (M-OSRP), a research program and petroleum industry consortium led by Arthur B. Weglein in the physics department of the University of Houston.

Working as a visiting/research assistant professor, Bogdan soon made important contributions to geophysics. In 2005, Bogdan became assistant professor of mathematical sciences at Montclair State University. I met Bogdan in 2004, when I joined M-OSRP to do research as a PhD candidate with Professor Weglein. As a student, I highly benefited from Bogdan’s teaching abilities and his deep math-physics knowledge and understanding. His multidisciplinary background allows him to digest complicated material and explain it in simple terms. In 2004, Bogdan was working on the forward-scattering series (FSS) description of prestack events (including critical and postcritical events). He then further developed and generalized that work using high-frequency approximations and Padé approximants. A thorough understanding of the FSS benefits subsequent studies of the inverse-scattering series (ISS). Bogdan studied the ISS by focusing on internal multiple attenuation (IMA) and depth imaging.

Araújo and Weglein found the IMA algorithm in the ISS based on Feynman diagrams and physical intuition. IMA is a data-driven, nonlinear, and multidimensional algorithm which is independent of the model type defining the subsurface. Five years ago these characteristics of the algorithm were known; however, there was no clear understanding of the algorithm’s ability to process different types of an internal multiple’s subevents beyond the intuitive ones defined by specular reflections. Internal multiples with critical/postcritical subevents are observed in field data with large offsets (e.g., WAZ and RAZ data). Bogdan addressed this problem and demonstrated that the algorithm processes data containing internal multiples with subevents represented not only by specular reflections but also by critical and postcritical reflections (including head waves). He also defined the conditions that a medium needed to satisfy to have internal multiples predicted by the algorithm, hence providing a firmer mathematical basis to the IMA algorithm. Continuing on this path, he moved to work on velocity-independent depth imaging, where he participated in the pioneering developments of this technology for a multidimensional subsurface in collaboration with Fang Liu, Kris Innanen, Simon Shaw, and Weglein.

I feel very fortunate to have gotten to know Bogdan Nita on both a professional and personal basis. He is an exceptionally bright and thorough young scientist who places high standards for his work. He is a role model for younger geophysicists. Bogdan is a most deserving recipient of the Society’s Karcher Award.