# Presentation: 896333

## Fluorescence Line Height (FLH)

- Ricardo Letelier,
- Mark Abbott,
- Jasmine Nahorniak
- Oregon 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)

## F = PAR x ([chl] x a*) x f

- 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

## 650

- Radiance, W m-2 μm-1 sr-1

- Normalized band transmittance

- 10 mg

- 0.01 mg

- Wavelength, nm

- 670

- 690

- 710

- 730

- 750

- 770

- 0.00

- 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

- _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/

## Slide 10

## Testing the MODIS FLH Algorithm

- From Hoge et al.

- FLH vs.
- chlorophyll

- FLH vs.
- CDOM

## In situ chlorophyll, mg m-3

- In situ chlorophyll, mg m-3

- FLH, W m-2 μm-1 sr-1

- GLOBEC NEP AUGUST 2002

- [chl] = .021 + 43.4 FLH1.866

## GLOBEC NEP AUGUST 2002

- chlFLH empirical
- (this study)

- chlFLH semi-analytical
- (Huot & Cullen
- assuming f = 0.006)

- In situ chl

- 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)

- 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

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

- 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

## Slide 17

## Slide 18

## Slide 19

## Slide 20

## Seasonal patterns of 

- Seasonal patterns of
- FLH and chl a

- Southern Ocean

- Indian Ocean

## MODIS ARP

- Huot & Cullen ARP
- using in situ chl to
- Derive an average f

- chlFLH empirical
- (this study)

## Slide 23

## GLOBEC NEP 

- GLOBEC NEP
- AUGUST 2002

- MODIS CFE using
- MODIS ARP

- MODIS CFE using
- Huot & Cullen ARP

- chlFLH empirical
- (this study)

## Thalassiosira weissflogii 

*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](mailto: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)