fluorescence line height (flh)

Fluorescence Line Height (FLH)

Ricardo Letelier,Mark Abbott,

Jasmine NahorniakOregon State University

Outline

• FLH basic alghorithm• Comparison between field

measurements and MODIS FLH• FLH and [chl a]• Chlorophyll Fluorescence Efficiency

Acknowledgments

• Mark Abbott, Jasmine Nahorniak (OSU)• Dennis Clark (NOAA)• Wayne Esaias, Frank Hoge (NASA)• Bob Evans, Kay Kilpatrick, Howard

Gordon, Ed Kearns (Univ. Miami)• Ken Carder (USF)• John Cullen & Yannick Huot (Dalhousie)

0

0.002

0.004

0.006

0.008

0.01

0.012

0.014

0.016

400 450 500 550 600 650 700

Wavelength, nm

Lu/E

s

0

0.002

0.004

0.006

0.008

0.01

0.012

0.014

0.016

400 450 500 550 600 650 700

Wavelength, nm

Lu/E

s

Chlorophyll absorption

Increase in fluorescence

F = PAR x ([chl] x a*) x f

MODIS FLH bands: avoid oxygen absorbance at 687 nm

Weighting factor used to compensate for off-center FLH

0

2

4

6

8

10

12

650 670 690 710 730 750 770

0.00E+00

2.00E-02

4.00E-02

6.00E-02

8.00E-02

1.00E-01

1.20E-01

Rad

ianc

e, W

m-2

µm

-1 sr

-1

Nor

mal

ized

ban

d tr

ansm

itta

nce10 mg

0.01 mg

Wavelength, nm

650 670 690 710 730 750 7700.00

0.02

0.04

0.06

0.08

0.10

0.12

0

2

4

6

8

10

12

13 14 15

FLH (10 mg)

Negative FLH due to TOA curvature needs to be corrected empirically

Field Observations

-In situ open ocean - MOBY - HOT cruises

-In situ Coastal - GLOBEC - COAST

- Southern Ocean

Optical Drifters

- 29 off Oregon- 12 in the Southern Ocean- Noth Atlantic (John Cullen’s group)

http://picasso.coas.oregonstate.edu/ORSOO/

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0 0.05 0.1 0.15 0.2 0.25

Oregon Drifters FLH, W m-2 m-1 sr-1

MO

DIS

Terr

a F

LH,

W m

-2

m-1 s

r-1

From Hoge et al.

Testing the MODIS FLH Algorithm

FLH vs. chlorophyll

FLH vs. CDOM

In situ chlorophyll, mg m-3

FLH

, W

m-2 µ

m-1 s

r-1

GLOBEC NEP AUGUST 2002

[chl] = .021 + 43.4 FLH1.866

All cruise dataOnly pixels of passes within 5 hrs of sampling time

chlFLH empirical(this study)

chlFLH semi-analytical(Huot & Cullen

assuming f = 0.006)

In situ chl

GLOBEC NEP AUGUST 2002

-Both FLH derived chl algorithms appear to slightly overestimate chl a fields.-They do not seem to reproduce the low values observed in situ.-Some of the differences between in situ and FLH derived could be due to time differences and sampling depth (in situ = 5 m depth)

GLOBEC NEP AUGUST 2002 (July 31st – August 19th)

In situ chl a, mg m-3 MODIS chl a_2, mg m-3

In Situ Observations of F/[chl] suggest it can be a proxy for f

Initial slope proportional to F

Sea Surface Temperature Chl a Chl Fluorescence Line Height (°C) (mg m-3) (W m-2 m-1 sr-1)

MODIS Terra L2 1 km resolution scene from October 3rd 2001

From OSU-COAS EOS DB Station

Southern Ocean Temp. Test

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

3/15/00 10/1/00 4/19/01 11/5/01 5/24/02 12/10/02 6/28/03

Date

Ch

l a, m

g m

-3

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

FL

H, W

m-2

m

-1 s

r-1

Chl a 3

FLH

Seasonal patterns of FLH and chl a

Southern Ocean

Indian Ocean

0.02

0.03

0.04

0.05

0.06

0.07

0.08

3/15/00 10/1/00 4/19/01 11/5/01 5/24/02 12/10/02 6/28/03

Date

Ch

l a, m

g m

-3

0.05

0.07

0.09

0.11

0.13

0.15

0.17

0.19

0.21

0.23

0.25

FL

H, W

m-2

m

-1 s

r-1

MODIS ARP Huot & Cullen ARPusing in situ chl to

Derive an average f

chlFLH empirical(this study)

0 0.005 0.01 0.015 0.02 0.025 0.030

500

1000

1500

2000

2500

3000

# oc

cure

nces

CFE, non dimensional

Range covering mostoceanic regions(Gordon, 1979)

Mean oceanic value according to Fischer and Kronfeld (1990)

GLOBEC NEP AUGUST 2002

MODIS CFE using MODIS ARP

MODIS CFE using Huot & Cullen ARP

chlFLH empirical(this study)

0

0.005

0.01

0.015

0.02

0.025

0.03

0.035

0.04

0.045

0.05

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

0

0.1

0.2

0.3

0.4

0.5

0.6

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Fv/

Fm

, n.d

.9

AM

CF

E, r

.u.

/max , n.d.

Thalassiosira weissflogii Chemostat results 2001-2002

After 3 days of constant cell counts

After 14 days

Where do we stand?

• Field observations suggest that MODIS FLH is a robust product.

• Comparison of [chl]field vs FLHMODIS

suggest that FLH may prove of use to derive [chl] in turbid waters. However, and as expected, there is no single relation between FLH and [chl a]. (See also K Carder poster).

• CFE validation requires that of FLH and ARP.

• In order to interpret CFE we need field and laboratory based work that explores the effect of environmental variability and phytoplankton specific composition.

FLH working group

• Charlie Yentsch (CSYentsch@aol.com), • Dave Siegel (davey@icess.ucsb.edu), • Greg Leptoukh (Gregory.Leptoukh@nasa.gov), • Richard Sikorski (sikorski@raytheon.com), • Chuck McClain (Charles.R.McClain@nasa.gov), • Heidi Dierssen (heidi.dierssen@uconn.edu), • Chuanmin Hu (hu@seas.marine.usf.edu), • Paula Bontempi (paula.s.bontempi@nasa.gov), • Alex Cunningham (a.cunningham@strath.ac.uk), • Mike Behrenfeld (Mike.Behrenfeld@nasa.gov),• Ricardo Letelier (letelier@coas.oregonstate.edu)