Gnanadesikan, Anand: Johns Hopkins University (Project Lead)
Project Funding:
2007 - 2010
NRA: 2006 NASA: Interdisciplinary Research in Earth Science
Funded by NASA
Abstract:
This proposal examines links between ocean circulation and biogeochemical cycling using coupled climate models. It builds on three recent results in our group. The first shows that tropical ocean color can act as a positive feedback on climate change and variability. Removing ocean color from the near-equatorial zones can actually result in warming the equator and reducing the magnitude of vertical exchange in this region. The second result shows that the tropical circulation in the ocean and atmosphere of appears to be slowing down under climate change in a manner consistent with anthropogenic climate change. The third result is that the efficiency of the oceanic biological pump, which plays an important role in regulating atmospheric carbon dioxide, is determined by the circulation of the Southern Ocean. Changes in the preformed nutrient content can greatly alter the biological pump, and simulations with ideal age tracers indicate that the processes that ventilate the deep Southern Ocean with high preformed nutrients are very sensitive to climate and the numerical representation of ocean circulation.
We propose to build on these results by
Performing studies which seek to better understand the mechanisms and processes determining shortwave absorption.This will involve analyzing satellite and in situ estimates of ocean color and chlorophyll (revisiting the bio-optical approximation), performing sensitivity studies where the impacts of colored dissolved organic matter and chlorophyll are separately considered, and developing prognostic models of ocean color.
Including prognostic biogeochemical models in a coupled model built around GFDL's isopycnal ocean model. This model (which was used to do the simulations in which ocean color was removed) has a much more realistic representation of oceanic overflows than previously run level-coordinate models. This model will be used to build prognostic models of ocean color and run under changed and changing climates.
The work will involve a close collaboration between researchers at Princeton/GFDL developing state-of-the-art coupled models, and researchers at UCSB who have worked over the past decade to characterize shortwave absorption in the deep ocean. It will advance IDS objectives by quantifyingthe impact of ocean color on climate and by identifying key feedbacks and processes that needs to be modeled to simulate the entire earth system.
Publications:
Henson, S. A., Sarmiento, J. L., Dunne, J. P., Bopp, L., Lima, I., Doney, S. C., John, J., Beaulieu, C. 2010. Detection of anthropogenic climate change in satellite records of ocean chlorophyll and productivity. Biogeosciences. 7(2), 621-640. DOI: 10.5194/bg-7-621-2010
2011 NASA Carbon Cycle & Ecosystems Joint Science Workshop Poster(s)
- Ocean color and Arctic seasonal cycling
-- (Anand Gnanadesikan)
[abstract]
2008 NASA Carbon Cycle & Ecosystems Joint Science Workshop Posters
- Regional impacts of ocean color on El Nino
-- (Whit G Anderson, Anand Gnanadesikan)
[abstract]
More details may be found in the following project profile(s):
