Oceanic Remote Chemical/optical Analyzer (ORCA)

An autonomous profiler monitoring water quality in south Puget Sound

T,S, O2

NO3,

ORCA overall;Steven Emerson; Allan Devol

Jan Newton; Rick Reynolds

PRISM John Dunne; Wendi Ruef

General Support

Nutrient Analyzer

• Develop a robust remote chemical and biological monitoring system

• T, S, Light, Meteorology

• NO3, O2, Chl-a, turbidity

• NH4, Gas Exchange parameters

• Telemeter data back to UW

• Monitor the spectrum of time-scales

• Hourly (tides), Daily (solar), Weekly (plankton growth), Monthly (blooms), Annual (seasons, and inter-annual, e.g., El Nino)

• Describe natural variability and characterize and help evaluate potential human influence

• Validate PRISM physical and biological models

ORCA GOALS

WHAT DOES ORCA LOOK LIKE?

light

solar panel

radarreflector

superstructure

Platform and housing For Winch, electronics, etc

Atlas float(cut awayview)

ballast ring

anchoring(break inscale)

pack

age

weather station

ORCA Schematic View

4.2 m

solar panel

WHERE IS ORCA?

Seattle

Seattle

Tacoma

Tacoma

http://www.ocean.washington.edu/research/orca/

Nutrient Analysis

Spring Bloom Movie

Fall Bloom Movie

Growing Season Movie

Basic data shows varibility

July 12 - 28, 2000

enhancement

October 15-21, 2000Sept. 20- Oct. 2, 2000

no enhancement surface enhancement

Sigma-t

Chl ug/l

O2 mg/l

enhancement no enhancement surface enhancement

0

5

10

15

0 500 10000

5

10

15

20

25

0 500 10000

5

10

15

0 200 400 600

12 Oct 0025 Sep 0010 Jul 00

dep

th (

m)

primary productivity (mg C m-3 d-1)

Effect of nutrient addition on phytoplankton productivity

blue = ambient production

red = spiked with NH4 and PO4

Carr Inlet, WA Ecology

What Causes varibility ?

Tidal Advection ?

What causes high frequency variability ?

What causes high frequency variability ?

Wind and destratification ?

Analysis by Kate Edwards

Photosynthesis (J)CO2 + H2O + nutrients CH2O + O2

O2 flux

C flux

5 mMixedDeep mixing

1. How frequently do we need to sample?

2. What is gross O2 production (GP)?

3. What is net community O2 production (NCP)?

How frequently do you need to sample?

Gas Exchange = G* (O2sat-O2obs)

Gas exchange (moles m-2 d-1)

2-hr 0.012 0.012 0.012

0.012 0.012 0.012 0.012 0.012

Daily 0.021 0.020 0.021

0.019 0.021 0.022 0.021 0.020

Weekly 0.028 0.014 0.018

0.029 0.024 0.021 0.023 0.010

Bi-Weekly

0.013 0.014 0.018

0.036 0.008 0.327 0.016 0.009

Monthly 0.007 0.019 0.021

0.048 0.012 0.019 0.018 0.009

G=f(average daily wind speed)(Liss and Merlivat, 1986)

Diurnal O2 Change Model

200

250

300

350

400

450

500

850 900 950 1000

jDay

O2

mm

ole

s/m

3/d

1Apr. 10 Oct.

So, how do we get O2 production terms?

diurnal O2 change

150 day average

Time of Day (hr)

0 4 8 12 16 20 24

Ave

rag

e O

2 (

m m

ole

s m

-3d-1

)

335

340

345

350

355

360

1) night-time respiration, R = 14 mmoles m-3 (d/2)-1

2) Assume R~ constant, thus, R =28 mmoles m-3 d-1*5 m = 140 mmoles m-2 d-1

3) Since dO2/dt = 0 over 24 h, R = j = 140 mmoles m-2 d-1

(j = O2 production required to balance R)

Amplitude ~ 14 mmoles m-3

Hourly Oxygen Averages

Box Model for net oxygen production

hh**dOdO22/dt/dt = G*O2 + Kz*dO2/dz + NCP

h h ** dO dO22/dt/dt = observed box depth & oxygen change with time

G * O2 = gas exchange: wind speed; oxygen gradient

across air-water interface

Kz * dO2/dz = vertical diffusion: diffusion coefficient &

observed vertical oxygen gradient

NCP = net biological oxygen production: determined from

model

G = f (average daily wind speed) (Liss and Merlivat, 1986)

Kz = f (buoyancy frequency) (Denman and Gargett, 1983)

Simple Box Model Results

• NCP = 0.011 moles m-2 d-1

(132 mg C m-2 d-1)

• G.E. = -0.012 moles m-2 d-1

• Vertical mixing = -0.0008

• h (dO2/dt) = -0.0021

Is This Reasonable ?

regression = 380-320 mmoles m-3

(380-320)/150 = 0.4 mmoles m-3d-1

h*(dO2/dt) = 2.1 mmoles m-2d-1

(2.1mmoles m-2d-1)/(5m)=0.4mmoles m-3d-1

200

250

300

350

400

450

500

850 900 950 1000

jDay

O2

mm

ole

s/m

2/d

O2

Linear (O2)

1Apr. 10 Oct.

NCP=0.011, G.E.=-0.012, mix=-0.0008, h*dO2/dt=-0.0021

Conclusion: NCP ~0.011 mmoles m-2d-1

GP = j + G.E.

= 140 + 12

= 152 mmoles m-2 d-1

(1824 mg C m-2 d-1)

What, then is GP?

0

1000

2000

3000

4000

5000

6000

Apr May Jun Jul Aug Sep Oct Nov Dec

mg

C m

-2 d

-1 Carr Inlet

0

1000

2000

3000

4000

5000

6000

Apr May Jun Jul Aug Sep Oct Nov Dec

mg

C m

-2 d

-1

Nisqually Reach

0

1000

2000

3000

4000

5000

6000

Apr May Jun Jul Aug Sep Oct Nov Dec

mg

C m

-2 d

-1 Case Inlet

0

1000

2000

3000

4000

5000

6000

Apr May Jun Jul Aug Sep Oct Nov Dec

mg

C m

-2 d

-1 Hammersley Inlet

0

1000

2000

3000

4000

5000

6000

Apr May Jun Jul Aug Sep Oct Nov Dec

mg

C m

-2 d

-1

Totten Inlet

Figure 15. Seasonal levels of ambient primary production integrated over the euphotic zone. Data shown are Apr. 99, Jul. 00, Sep. 99 and Dec. 99.

Newton and Reynolds, 2000

Integrated Chl * Daily Ed(PAR, 0+)

[ gChl m-2 * (mol m-2 d-1) ]

10-2 10-1 100 101 102

Inte

grat

ed P

rodu

ctio

n [

gC m

-2 d

-1 ]

10-2

10-1

100

101

SPASM (N=34)Other Puget Sound (N=42)

Y = 1.22 X0.85

r 2 = 0.93

Chl Based Productivity Model*

*Rick Reynolds

Productivity Model Input Data

EdP

AR

(m

ole

m-2

d-1

)

0

20

40

60

80

Date

1/1/02 3/1/02 5/1/02 7/1/02 9/1/02 11/1/02

Ch

l (m

g m

-2)

0

20

40

60

80

100

120

140

160

180

200

Daily-IntegratedSurface Insolation

Daily depth-IntegratedChl

Date

1/1/02 3/1/02 5/1/02 7/1/02 9/1/02 11/1/02

Pri

mar

y P

rod

uct

ivit

y (g

C m

-2 d

-1)

0

2

4

6

8

10

Modeled* Daily Production atThe Carr Inlet-ORCA Site

*Rick Reynolds model

Production Summary

mmoles m-2 d-1 mg C m-2 d-1

Mixed layer net

O2 production 10 120

Mixed layer Gross O2 production

150 1900

14C-based

Model production3400

• High frequency sampling reveals high frequency features

• Some of the high frequency signal is due to tidal effects

• Frequent sampling required to capture the true value of certain fluxes, e.g. gas exchange

• Bloom starts when water air temperature becomes equal to water temperature

• Frequent summer destratification driven by wind events

• Production can be derived from oxygen distribution

Wrap Up

Orca Home Page

Longer Term Goals

• Science

• Study Bloom Dynamics/gas exchange/nutirent/physics coupling

• Mixed layer

• Aphotic zone

• Add Sensors (PO4, Eddy Correlation, micro-gradient)

• Publish Orca Results

• Expand Network:

• South Sound, Main Basin, Hood Canal, Admiralty Inlet

• Continue and Expand Outreach/Education

Advection

Production

Goals for 2003

• Science Goals:

• MIXED experiment (April 2003)

• Nutrients; NO3 and NH4

• Move Orca for Brightwater

• Publish Orca Results

• Prism Goals:

• Use Orca to Validate ABC-POM

• Carr Inlet

• Brighwater site

• Outreach

• Maintain Orca Website

• Orca School

[O2] Box Model