Robert Letscher
Associate Professor of Chemical Oceanography<br>Earth Sciences<br>Assistant Director, Ocean Process Analysis Laboratory<br><br><br>I am a marine biogeochemist meaning I work to uncover and quantify the interrelated chemical, biological, and physical processes occurring within the ocean that result in transformations of the important bioactive elements carbon, nitrogen, phosphorus, and oxygen. My focus is understanding the production, transformation, and fate of biologically produced organic matter and the related cycling of chemical nutrients in the sea. My research program studies these processes at the largest scales – the global ocean, annual to millennial. I am particularly interested in studying the low nutrient ecosystems of the ocean subtropics. Covering 60% of the Earth’s surface they are the world’s largest biome, responsible for a quarter of all biological productivity. My group uses a variety of techniques and tools including collection of new chemical observations at sea, development of ocean biogeochemistry within Earth System Models, laboratory experiments, and analysis of data from autonomous platforms such as BGC-Argo.
Courses Taught
- ESCI 400: Freshman Field Seminar
- ESCI 501: Introduction to Oceanography
- ESCI 747/847: Aqueous Geochemistry
- ESCI 752/852: Chemical Oceanography
- ESCI 795/895: Top/Ocean Biogeochemistry
- ESCI 896: Topics/Deep Ocean Circulation
- INCO 590: Student Research Experience
- INCO 790: Advanced Research Experience
- OCE 999: Doctoral Research
Research Interests
- Biogeochemistry
- Ocean Modeling
- Oceanography
Selected Publications
Letscher, R. T., Smethie, W. M., & Hansell, D. A. (2025). Centennial‐Scale Storage of DOC Within Arctic Ocean Deep Waters Controlled by Subzero Temperatures. Global Biogeochemical Cycles, 39(4). doi:10.1029/2024gb008428
Letscher, R. T., & Aluwihare, L. I. (2024). A simple method for the quantification of amidic bioavailable dissolved organic nitrogen in seawater. Limnology and Oceanography: Methods, 22(7), 451-463. doi:10.1002/lom3.10622
Lin, J. S., & Letscher, R. T. (2024). Drivers of Ocean Iron Stress Variability in High-Nutrient, Low-Chlorophyll Regions from Ocean Color. Ocean-Land-Atmosphere Research, 3. doi:10.34133/olar.0073
Wang, W. -L., Fu, W., Le Moigne, F. A. C., Letscher, R. T., Liu, Y., Tang, J. -M., & Primeau, F. W. (2023). Biological carbon pump estimate based on multidecadal hydrographic data.. Nature, 624(7992), 579-585. doi:10.1038/s41586-023-06772-4
Liang, Z., Letscher, R. T., & Knapp, A. N. (2023). Global Patterns of Surface Ocean Dissolved Organic Matter Stoichiometry. Global Biogeochemical Cycles, 37(12). doi:10.1029/2023gb007788
Letscher, R. T., Primeau, F., & Moore, J. K. (2016). Nutrient budgets in the subtropical ocean gyres dominated by lateral transport. NATURE GEOSCIENCE, 9(11), 815-+. doi:10.1038/NGEO2812
Letscher, R. T., & Moore, J. K. (2015). Preferential remineralization of dissolved organic phosphorus and non-Redfield DOM dynamics in the global ocean: Impacts on marine productivity, nitrogen fixation, and carbon export. GLOBAL BIOGEOCHEMICAL CYCLES, 29(3), 325-340. doi:10.1002/2014GB004904
Letscher, R. T., Moore, J. K., Teng, Y. -C., & Primeau, F. (2015). Variable C: N: P stoichiometry of dissolved organic matter cycling in the Community Earth System Model. BIOGEOSCIENCES, 12(1), 209-221. doi:10.5194/bg-12-209-2015
Letscher, R. T., Hansell, D. A., Carlson, C. A., Lumpkin, R., & Knapp, A. N. (2013). Dissolved organic nitrogen in the global surface ocean: Distribution and fate. GLOBAL BIOGEOCHEMICAL CYCLES, 27(1), 141-153. doi:10.1029/2012GB004449
Letscher, R. T., Hansell, D. A., & Kadko, D. (2011). Rapid removal of terrigenous dissolved organic carbon over the Eurasian shelves of the Arctic Ocean. MARINE CHEMISTRY, 123(1-4), 78-87. doi:10.1016/j.marchem.2010.10.002
