THIS PROJECT AIMS TO COMBINE REMOTE SENSING PROXIES OF IRON AEROSOLS PHYTOPLANKTON PHYSIOLOGY AND BIOMASS WITH OUTPUT FROM A COUPLED PHYSICAL-BIOGEOCHEMICAL MODEL IN ORDER TO QUANTIFY PLANKTONIC DRIVERS OF PRODUCTION AND EXPORT IN THE ECOLOGICALLY AND ECONOMICALLY IMPORTANT REGION OF THE PATAGONIAN SHELF AND ADJACENT SOUTH ATLANTIC WATERS (DRAKE PASSAGE AND MALVINAS/BRAZIL CONFLUENCE ZONE). IN THIS REGION OF THE SOUTH ATLANTIC PRIMARY PRODUCTION AND CARBON EXPORT VARY STRONGLY IN SPACE AND TIME AS A FUNCTION OF DOMINANT SPECIES AND INPUTS OF IRON INTO THE SYSTEM. THE PROPOSED PROJECT WILL CHARACTERIZE THE SEASONAL CYCLE OF NON-CALCIFYING AND CALCIFYING PHYTOPLANKTON (DIATOMS/PICOPLANKTON AND COCCOLITHOPHORES RESPECTIVELY) OVER THE PATAGONIAN SHELF AND ADJACENT SOUTHERN OCEAN WATERS TO DETERMINE THEIR SIGNIFICANCE TO THE REGIONAL CYCLES OF IRON AND CARBON. SPECIFICALLY IT WILL ADDRESS THE QUESTION: WHAT ARE THE RELATIVE SPATIAL AND TEMPORAL CONTRIBUTIONS OF CALCIFYING AND NON-CALCIFYING PHYTOPLANKTON TO THE REGIONAL IRON AND CARBON CYCLES? THE PROJECT WILL UTILIZE A COMBINED REMOTELY-SENSED AND QUANTITATIVE NUMERICAL MODELING APPROACH. THE APPROACH IS AS FOLLOWS: 1) DEVELOPMENT OF A REGIONALLY FOCUSED COUPLED PHYSICAL-BIOGEOCHEMICAL MODEL WITH ROBUST IRON CYCLING. VALIDATED WITH REMOTESENSED AND IN SITU DATA MODEL ESTIMATES OF BIOMASS AND CONSEQUENT MODEL PATHWAYS WILL ELUCIDATE WHICH COMPONENTS OF THE IRON CYCLE ARE IMPORTANT IN DETERMINING SPATIAL (SHELF VS. DEEP OCEAN LATITUDINAL) AND TEMPORAL (SEASONAL ANNUAL) PATTERNS OF CALCIFEROUS AND NON-CALCIFEROUS PRODUCTION (BLOOM DYNAMICS); 2) MODEL SIMULATIONS OF BLOOM DYNAMICS WILL QUANTIFY THE DIFFERENTIAL IMPACT OF THE PHYTOPLANKTON TAXA ON REGIONAL VALUES OF IRON EXPORT AND PRODUCTION AND WILL BE CORRELATED AGAINST SATELLITE-DERIVED VALUES OF DUST DEPOSITION (AEROSOL OPTICAL THICKNESS); 3) REGIONAL SPATIOTEMPORAL PATTERNS OF CARBON EXPORT AND PRODUCTION WILL BE QUANTIFIED FROM SIMULATED RUNS OF CALCIFIERS AND NON-CALCIFIERS. FOR ALL OBJECTIVES CONSTRAINT OF MODEL PARAMETERS AND VALIDATION OF MODEL OUTPUT WILL BE ACHIEVED THROUGH THE COMBINED USE OF REMOTELY SENSED DATA FROM NASA AQUA-MODIS SEAWIFS AND VIIRS SATELLITE PRODUCTS AND IN SITU MEASUREMENTS. STATISTICAL TECHNIQUES SUCH AS EMPIRICAL ORTHOGONAL FUNCTION (EOF) ANALYSIS AND WAVELET ANALYSIS WILL QUANTIFY UNCERTAINTIES IN THE VALIDATIONS. THE RESULTS OF THIS RESEARCH WILL DIRECTLY CONTRIBUTE TO THE GOALS LAID OUT IN THE CARBON CYCLE AND ECOSYSTEM DIVISION OF NASA'S EARTH SCIENCE RESEARCH PROGRAM. SPECIFICALLY THEY WILL ASSIST IN DETECTING AND PREDICTING CHANGES IN EARTH'S ECOLOGICAL AND BIOGEOCHEMICAL CYCLES NOTABLY WITH REGARD TO BIODIVERSITY AND THE GLOBAL CARBON CYCLE (CARBON CYCLE AND ECOSYSTEMS).