Project Funding: 2013 - 2015

NRA: 2012 NASA: Ocean Biology and Biogeochemistry   

Funded by NASA

Abstract:
I propose to investigate the impact of El Niño-Southern Oscillation (ENSO) diversity on phytoplankton composition in the equatorial Pacific (EqPac) Ocean using satellite observations (e.g., ocean color-derived phytoplankton size classes and functional types), an established ocean color assimilating biogeochemical model, and in-situ data. ENSO is a global ocean-atmosphere phenomenon that significantly influences weather patterns and ocean circulations in the Pacific Ocean, which in turn affect biological production and ecosystem characteristics. Much of our existing knowledge about the relationship between ENSO and biology is with respect to the classic El Niño (EP-El Niño), which has maximum warming in the eastern EqPac. However, since the 1990s, there have been frequent occurrences of a new type of El Niño (CP-El Niño) that has maximum warming in the central EqPac and such ENSO diversity has caused variations in the classic El Niño/La Niña transition. The impact of this new flavor of El Niño and associated El Niño/La Niña transitions on biology (beyond chlorophyll-a) has not been previously investigated and is poorly understood. I hypothesize that phytoplankton composition in the EqPac will respond differently to CP- and EP-El Niño events and associated El Niño/La Niña transitions given variability in environmental factors. Statistical and dynamical analyses will be performed to understand ENSO-related phytoplankton composition anomalies in the EqPac. Main statistical analyses include (1) regression and correlation analyses of EqPac environmental conditions with indices that describe CP- and EP-El Niño events, (2) studying the evolution of EqPac phytoplankton composition anomalies associated with individual ENSO events and El Niño/La Niña transitions, and (3) composite analysis associated with CP- and EP-El Niño events. The primary dynamical analysis uses NASA Ocean Biogeochemical Model (NOBM) simulations to assess nutrient dynamics. I have extensive experience in the analysis and application of satellite observations, in- situ data, and model simulations to study synoptic to decadal changes in ocean and atmosphere responses to climatic events. Most relevant to this investigation is my work on the chlorophyll-a (chla) response and mechanistic differences responsible for chla variations observed between CP- and EP-El Niño events, as well as alterations in plankton community size structure and biophysical responses to hurricanes. Co-I Cécile S. Rousseaux has expertise in biological oceanography, NOBM simulations, and application of NOBM simulations to examine climate variability. Co-I Watson W. Gregg provides guidance related to ocean color observations and NOBM simulations. This proposal directly addresses NASA’s strategic goal to Advance Earth System Science to meet the challenges of climate and environmental change for the Earth Science focus area of Carbon Cycle and Ecosystems by specifically addressing the OBB NRA solicitation of Impacts on and vulnerability of biological oceanography . The proposed investigation is highly relevant to the OBB NRA as it addresses the relation of climate and environmental variability (diversity of ENSO and ENSO transitions) to the marine ecosystem. This proposal advances our understanding of the phytoplankton response to ENSO diversity, while improving our awareness and knowledge about our changing climate system.

More details may be found in the following project profile(s):

• NASA Ocean Biology & Biogeochemistry (OBB) Project Profile