Contrasting inherent optical properties and carbon metabolism

in four northeastern (USA) estuary-plume systems

D. Vandemark, NASA/GSFC & UNH J. Salisbury, C. Hunt, J. Campbell, Univ. of New Hampshire

W. McGillis, Columbia University - LDEO

Program Goals

• Examine freshwater control upon Gulf of Maine coastal waters in terms of carbonate, nutrient, and productivity dynamics

• Develop techniques to retrieve metabolic information from inherent optical properties and eventually from satellite measurements

This talk : first observations

1. Contrast amongst four river systems

2. Empirically relate bio-optical & metabolic terms using clustering analysis

Observational program

• UNH/COOA : NOAA-sponsored (COTS)

• Flo-thru suite: physical + fluor. + IOP + metabolic (pCO2,O2) variables

• Discrete sampling and phys. + IOP profiling along salinity gradient

• Four rivers sampled seasonally in Gulf of Maine

• Hudson river also sampled 7/1-7/2, 2004 (see McGillis)

2004 COOA Gulf of Maine measurement program

COOA shipboard measurements

Fast-rate CO2 equilibrator

Profiler: AC-9, AC-S, fl_CDOM,CHL,PEB, and CTD

Infrared CO2 gas analyzer

Camden Belle -26’ riverine sampling vessel

R/V Gulf Challenger – majority of 2004 data set

Flo-thru O2, fl_Chl, fl_CDOM, beam_c, T, S

Four rivers in four days

Androscoggin- Kennebec

Penobscot

Pleasant

Merrimack

N

EW

S

50075010001250

DOC flux (kg km-2)

Aitkenhead and McDowell (2001)

- summer climatology

• varied watersheds, 3 of GoMaine’s largest sources

• Sampled plumes -> 0 psu, 27-30 July 2004Boston

Acadia

Androscoggin- Kennebec

Penobscot

Pleasant

Merrimack

N

EW

S

255075100

DIN flux (kg km-2)

Green et al., (2004)

Four rivers in four days

Contrasts between riversJuly 2004

CDOM surrogate for DOC

Contrasts between riversJuly 2004

Relatively high DIN loads

Contrasts between riversJuly 2004

Atm

120

110

100

90

80

70

BOUNDS Merrimac – autotrophic

Pleasant – strongly heterotrophic

Study in progress

• Diverse watersheds conditions in optical, trophic, and gas flux terms

• Some consistency with modeled basin attributes• Coming work - conservative mixing vs. localized

processing along salinity gradient and vs. season• …including profile & discrete data: nutrients, TA,

pH, DIC, DOC, DON, POC, HPLC

Merrimac River

Covariance between surface variables

Classification via clustering analysis - end goal is to link satellite retrievals to ecosystem metabolism

4 Observables[ T, fl_CDOM, fl_CHL, c660 ]i = 1,n

Objective clustering n=30000 (S < 31 psu)

Present result: 22 classes

Metabolic indicator?

O2

pCO2

Surface variables under study red=training set

Clustering results n=22 (classes sorted by pCO2)