Stephen Ogle

crops in bloom
crops in central america
Dr. Stephen Ogle digging for soil samples
Lake Maggoire with vineyards in foreground
Sugarcane stands

Laboratory Staff - Ogle

Cody Alsaker, Research Associate III

Dr. Cody Alsaker is a statistician with a background in environmental and survey statistics. Dr. Alsaker became keenly interested in statistics during his years as an undergraduate student in mathematics at the South Dakota School of Mines & Technology. After graduating with a B.S. in Applied & Computational Mathematics and minor in Computer Science in 2010, he began his graduate studies in Statistics at Colorado State University, receiving his Master’s degree in 2012 and his Ph.D. in 2016. For his dissertation research, Dr. Alsaker worked with Dr. F. Jay Breidt to perform NSF-funded research in statistical methods for molecular biology applications of small-angle X-ray scattering (SAXS) data. SAXS is a technique which yields low-resolution images of biological macromolecules by exposing the molecule in solution to a powerful X-ray beam. Dr. Alsaker’s SAXS research dealt with the development of improved methodology for estimating the radius of gyration of a molecule from SAXS data. He also created an estimation method for a new molecular parameter using SAXS intensity data, and studied the properties of the estimator via asymptotic approximations and experimental examples. His work has additionally involved writing and optimizing open-source user-friendly R code to accompany publications.

Dr. Alsaker’s research interests include time series analysis, statistical modeling, outlier detection, sampling techniques, statistical computing, and missing data. He is extremely interested environmental statistics, including advanced statistical methods applied to complex agricultural survey data.

Dr. Alsaker is currently a postdoctoral researcher at NREL working under the supervision of Dr. Stephen Ogle on the national greenhouse gas inventory. In particular, his works focuses on imputing the Conservation Effects Assessment Survey management data to all National Resources Inventory cropland points. The imputed management data will be incorporated into the DayCent ecosystem model to give estimates of nitrous oxide emissions and soil carbon for U.S. agriculture lands. If successful, this endeavor will provide important information regarding greenhouse gas emissions from various agricultural practices over time.


Ph.D. in Statistics from Colorado State University, Fort Collins, Colorado, 2016

M.S. in Statistics from Colorado State University, Fort Collins, Colorado, 2012

B.S. in Applied and Computational Mathematics from South Dakota School of Mines and Technology, Rapid City, South Dakota, 2010

Ram Gurung, Research Associate III

Ram Gurung is a Research Associate III that specializes in statistical analyses.  He has a M.S. degree from the Department of Statistics, Colorado State University under the direction of Dr. F. Jay Breidt.  For his M.S. research, he built statistical models to predict Enhanced Vegetation Index curves into the past and future for ecological modeling applications. He assists in estimating soil carbon and nitrous oxide emissions from agricultural lands for U.S. National Greenhouse Gas Inventory. His primary role is to estimate uncertainty of the emission estimates. He is involved in developing meta-models to inform decision support systems about greenhouse gas mitigation options in agricultural lands. He is also a Ph.D. candidate in the Graduate Degree Program in Ecology at Colorado State University, working with Dr. Stephen Ogle to develop a biogeochemical model for Enhanced Efficiency Nitrogen Fertilizers (EENF) and nitrogen loss from agroecosystems, and to produce an assessment of greenhouse gas emissions from agricultural lands with climate change.

Brahadeesh Guhan Dheenadayalan Sivakami, Research Associate III

Guhan is a Research Associate III that specializes in software and computer code development.  He has a degree in Electrical and Electronics Engineering from Thiagarajar College of Engineering in Madurai, India, and a Master’s in Electrical Engineering from Colorado State University in 2012.  He designs, develops and implements user-interfaces that simplify data entry for conducting greenhouse gas emission inventories using the Agriculture and Land Use (ALU) Greenhouse Gas Inventory Tool. He also assists with estimation of emissions in the U.S. National Greenhouse Gas Inventory. He likes to hike, bike, ski and play badminton in his free time.

Shannon Spencer, Research Associate IV

Shannon is a Research Associate IV who has M.S. in Natural Resources, Forestry from the University of New Hampshire and B.S. in Forestry from the University of Florida. He is the team lead for the Agriculture and Land Use National Greenhouse Gas Inventory tool and participates in data analysis and management of the U.S. National Greenhouse Gas Inventory. Shannon is married and has three children, and enjoys spending free time in Colorado’s outdoor environment with his family.

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