MY BIO
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I am a graduate student in Earth Sciences interested in the coevolution of the biosphere and the physical planet, which I look at through the lens of sedimentology, stable isotope geochemistry, and cosmogenic nuclide geochemistry.
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I am most interested in how large organisms (eg., plants, mammals, etc) change geomorphology, biogeochemical cycles, and climate.
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I am currently working on whether the evolution of trees in the Devonian Period (~400 Ma) altered the sensitivity of terrestrial silicate weathering and caused a drawdown in atmospheric carbon dioxide.
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I am also investigating how humans have affected erosional fluxes in the Chanel Islands in California, starting from the first humans on the island (Ancestral Chumash ~13,500 BP) to the arrival of ranchers and herder on the island (~1800 AD) to the present.
EDUCATION
I majored in Computer Engineering as an undergraduate and worked for a few years in the Bay Area (California) as a Software Engineer. I did not find that subject intellectually stimulating enough to hang on to throughout my life. Science has always fascinated me. After graduation I had the opportunity to travel across the US, multiple times. This reignited my love for the natural sciences that had probably developed in my childhood. My parents are soil scientists, and I would accompany them on field trips as well as extensive Himalayan treks; this would stimulate my curiosity, and fill me with fascination about the natural world.
After much thought, I decided to make a giant leap of career switchover to pursue graduate school in Geology. I started off by taking online courses while working full time. I then quit my job and risked my visa to take a field course at OSU; after which, I boarded the Amtrak to travel the country and meet potential advisers. This is where I met my masters adviser Dr. Jen Cotton. I started my master's program in Geological Sciences at California State University, Northridge (CSUN) in August 2019. I started my PhD at USC during the Fall of 2021 with Dr. Frank Corsetti and Dr. Josh West as my advisers.
August 2021 - Present
PH.D. IN EARTH SCIENCES, UNIVERSITY OF SOUTHERN CALIFORNIA.
ADVISER: DR. JOSH WEST & DR. FRANK CORSETTI
August 2019 - May 2021
January 2018 - December 2018
NON DEGREE STUDENT
OREGON STATE UNIVERSITY
CORVALLIS, OR
August 2012 - May 2017
BS IN COMPUTER ENGINEERING
PURDUE UNIVERSITY
WEST LAFAYETTE, IN
RESEARCH INTERESTS
I am most interested in the Earth System. Particularly, the interaction and interrelation of the macroscopic biosphere and the physical planet (climate, lithosphere, cryosphere) fascinate me.
I do not see the natural world through the lens of subjects and methods and I strive to keep my research interests broad.
TERRESTRIAL ECOSYSTEM EVOLUTION
Terrestrial primary productivity is dominated by plants. Significant events during the evolution of plants such as the Devonian spread of trees, the Cretaceous spread of flowering plants, and the Cenozoic spread of grasses shaped the global landscape. Forests altered river dynamics and sedimentation patterns, they restructured the biogeochemical cycling of elements such as C (thereby determining atmospheric pCO2), Si, Li, S, P and N, and enabled the colonization of land by animals and affected oceanic biota (by making nutrients and chemicals available to marine organisms to utilize).
COEVOLUTION OF MEGAFAUNA AND EARTH
Megafauna play an outsized role in impacting the various facets of the earth system whether it be through changing erosion rates (Cummings & Cummings, 2003) or nutrient cycling (Doughty et al., 2013).
However, these models have yet to be tested and my hope is to better understand the role of megafauna on the Earth System though the lens of field research and geochemistry.
EARTH-LIFE INTERRELATION
A fundamental connection between the biotic system and the physical planet through various climate and weathering feedbacks has been hypothesized to have kept the Earth habitable over geologic time. Evaluating this hypothesis during important events during the biotic evolution of flora and fauna allows me to gain a deeper philosophical understanding of our planet.
METHODS
*Currently used Methods
SEDIMENTOLOGY & BASIN ANALYSIS
Carbonate Reefs (hunting for Paleozoic sponge spicules and brachiopods), Fluvial and Lacustrine environments (Mesozoic and Cenozoic paleosol)
STABLE ISOTOPE GEOCHEMISTRY
Silicon, Lithium and Carbon Isotopes
CARBONATE PETROGRAPHY
Optical and Cathodoluminescent microscopy
MOLECULAR BIOMARKERS
Analysis of Polycyclic Aromatic Hydrocarbon (PAH) and long chain n-alkanes
PUBLICATIONS
Ghosh A., Cotton, J., Hauswirth, S., Hyland, E., Azmi, I., Tineo, D., Raigemborn, M.S., Hayduk, T., Insel, N. Precipitation controlled vegetation and fire regimes during the Late Miocene-Pliocene in South America. (in-prep)
Rafter, M., Cotton, J., Hyland, E., Ghosh, A., Raigemborn, M., Tineo, D. and Insel, N. New Paleoclimate proxy for growing season precipitation using paleosol geochemistry. (in-prep)
Azmi, I., Hyland, E., Cotton, J., Ghosh, A., Raigemborn, M.S., Tineo, D., Insel, N. Late Miocene expansion of grasslands in NW Argenitna linked to shifting hydroclimate. (in-prep)
Varadachari, C., Ghosh, A. Theoretical Derivations of a Direct Band Gap Semiconductor of SiC Doped with Ge. Journal of Elec Materi 44, 167–176 (2015)
SELECT POSTERS
Ghosh A., et. al. “Reconstructing the Late Miocene-Pliocene paleoenvironment and paleoclimate of southern continental South America (SA) in order to determine the factors driving expansion of C4 grasslands: δ13C isotopes, molecular biomarkers, phytoliths, and X-ray fluorescence (XRF) from Río Iruya, NW Argentina.” AGU Fall Meeting (December, 2020).
Ghosh A., et. al. “Did increasing seasonality and fire frequency cause the C4 grassland transition in South America (SA)? Investigations from two paleosol sites in NW Argentina using δ13C isotopes, molecular biomarkers, phytoliths, and X-ray fluorescence (XRF).” GSA 2020 Annual Scientific Meeting (October, 2020).
Chong, J.H., Ghosh, A., Hauswirth, S.C., “Estimating sediment discharge at a sediment filled dam using Digital Elevation Model (DEM).” Association of Engineering and Environmental Geologists (AEG) (September, 2020).
Ghosh, A., Varadachari, C. Theoretical Derivations of a Direct Band Gap Semiconductor of SiC Doped with Ge. Journal of Elec Materi 44, 167–176 (2015). https://doi.org/10.1007/s11664-014-3424-7
CONTACT
Zumberge Hall of Science (ZHS), University of Southern California
aditghos (dot) 605 (at) usc (dot) edu
