Fluorescence Line Height FLH Ricardo Letelier Mark Abbott

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)

0. 016 0. 014 Chlorophyll absorption 0. 012 Lu/Es 0. 01 Increase in fluorescence 0. 008 0. 006 0. 004 0. 002 0 400 450 500 550 600 650 Wavelength, nm F = PAR x ([chl] x a*) x Ff 700

MODIS FLH bands: avoid oxygen absorbance at 687 nm Weighting factor used to compensate for offcenter FLH

12 0. 12 Radiance, W m-2 µm-1 sr-1 10 0. 10 10 mg 8 0. 01 mg 6 4 0. 04 Negative FLH due to TOA curvature needs to be corrected empirically 2 0 650 0. 06 l 13 670 l 14 690 710 Wavelength, nm 730 0. 02 l 15750 0. 00 770 Normalized band transmittance FLH (10 mg)

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/

MODIS Terra FLH, W m-2 mm-1 sr-1 Oregon Drifters FLH, W m-2 mm-1 sr-1

Testing the MODIS FLH Algorithm FLH vs. chlorophyll FLH vs. CDOM From Hoge et al.

GLOBEC NEP AUGUST 2002 FLH, W m-2 µm-1 sr-1 All cruise data Only pixels of passes within 5 hrs of sampling time [chl] =. 021 + 43. 4 FLH 1. 866 In situ chlorophyll, mg m-3

GLOBEC NEP AUGUST 2002 In situ chl. FLH empirical (this study) chl. FLH semi-analytical (Huot & Cullen assuming f = 0. 006) -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 In situ chl a, mg m-3 (July 31 st – August 19 th) 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 L 2 1 km resolution scene from October 3 rd 2001 Sea Surface Temperature (°C) Chl a (mg m-3) Chl Fluorescence Line Height (W m-2 mm-1 sr-1) From OSU-COAS EOS DB Station

Seasonal patterns of FLH and chl a Southern Ocean Indian Ocean

chl. FLH empirical (this study) MODIS ARP Huot & Cullen ARP using in situ chl to Derive an average f

Mean oceanic value according to Fischer and Kronfeld (1990) # occurences Range covering most oceanic regions (Gordon, 1979) CFE, non dimensional

GLOBEC NEP AUGUST 2002 chl. FLH empirical (this study) MODIS CFE using MODIS ARP MODIS CFE using Huot & Cullen ARP

Thalassiosira weissflogii Chemostat results 2001 -2002 Fv/Fm, n. d. After 3 days of constant cell counts 9 AM CFE, r. u. After 14 days m/mmax , n. d.

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 Mc. Clain (Charles. R. Mc. Clain@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)