ricardo letelier, mark abbott, jasmine nahorniak college of oceanic and atmospheric sciences
DESCRIPTION
Estimating Chlorophyll Concentrations using MODIS Fluorescence: A Preliminary Evaluation in Coastal Waters. Ricardo Letelier, Mark Abbott, Jasmine Nahorniak College of Oceanic and Atmospheric Sciences Oregon State University. Acknowledgment: Robert Evans et al. University of Miami. - PowerPoint PPT PresentationTRANSCRIPT
Estimating Chlorophyll Concentrations using MODIS Fluorescence: A
Preliminary Evaluation in Coastal Waters
Ricardo Letelier, Mark Abbott, Jasmine Nahorniak
College of Oceanic and Atmospheric SciencesOregon State University
Acknowledgment: Robert Evans et al. University of Miami
Natural (passive) Fluorescence
• where F = fluorescence
[chl] = chlorophyll concentrationPAR = photosynthetically available
radiationa* = chlorophyll specific absorptionF = fluorescence quantum yield
• Absorbed Radiation by PhytoplanktonARP = a* x [chl] x PAR (calculated independently from [chl])
• F/ARP = Chl Fluor. Efficiency (CFE) F • ARP / ([chl] x PAR) = a*
*[ ] ( )F
F chl PAR a
If p + f + h = 1 & h = const.
then p = const. – f
PP = [chl] x (PAR x a*) x (const. – f)
or PP ARP x (const. - FLH/ARP)
(const./ARP) - FLH
Can we use FLH to tell us about chlorophyll?
• Absorption-based algorithms fail in waters where there are other materials that absorb and scatter and are not correlated with chlorophyll– Sediment– Dissolved organic matter
• Chlorophyll fluorescence is specific to chlorophyll– But it also depends on physiology
Goddard DACC weekly declouded 36 km starting 12/02/2000 (Quality=0 L2 V 4.2.2)
MODIS ARP
MODIS FLH
Goddard DACC weekly declouded 36 km starting 12/02/2000 (Quality=0 L2 V 4.2.2)
MODIS CHL
MODIS CFE
Chlorophyll December 4, 2000
FLH December 4, 2000
Chlorophyll June 25, 2002
FLH June 25, 2002
A
B
C
(From Frank Hoge)
MODIS_Chl MODIS_FLH MODIS_CFE MODIS_ARP
OSU Direct Broadcast October 04, 2001
Field Approach
• Mesoscale Surveys (Cowles/Barth)
Some Survey Measurements
-Continuous from Flow-through system-Temperature/ Salinity- Active Fluorometry- Fast Repetition Rate Fluorometry- Total and dissolved absorption and attenuation
-Discrete- Pigments (Fluor/HPLC)- Nutrients (autoanalyzer)- Particulate absorption
- Other Platforms- Optical Drifters, tethered
buoys- Moorings- Satlantic MicroSAS
underway reflectance- Satellites (SeaWiFS, MODIS, AVHRR,…)
Comparison between field measurements and Remote Sensing data
(Mesoscale Survey August 2000And MODIS Image from August 2nd)
(In situ chl derived from the calibration of the flow through fluorometer withHPLC chlorophyll determinations )
-Blue = all mesoscale survey data (July 31st – August 7th)-Red = Within 0.5 days of the MODIS Image Time stamp
In situ chl (mg m-3) In situ chl (mg m-3)
MO
DIS
chl
_2 (
mg
m-3)
MO
DIS
FLH
, W
m-2 u
m-1 s
r-1
0 0.005 0.01 0.015 0.02 0.025 0.030
500
1000
1500
2000
2500
3000
Range covering mostoceanic regions(Gordon, 1979;Carder & Steward,1985; and others)
East Coast Image 2001095.1605Oregon Coast DB Image 2001150#
occu
renc
es
# oc
cure
nces
CFE CFE
, m
g m
-2
, m
g m
-2
East Coast Image 2001095.1605Oregon Coast DB Image 2001150
Fischer and Kronfeld(1990) AssumingCFE = 0.003,
W m
-2
m-1 s
r-1
, W
m-2
m-1 s
r-1, mg m-2 , mg m-2
Chlorophyll biomass proxy Optimum photosynthesis max yield
(From Rachel Sander’s work)
25.8
24.8
23.8
22.7
21.723.3
24.3
25.3 PS
II
Longitude
Lat
itud
e
2625
24
23
22
23
24
25
Fv/
Fm
Longitude
Lat
itud
e
Optimum Absorption Quantum Yield August 2000(Nighttime)
Absorption Cross-section of Photosystem II
0.2
0.4
0.6
0.8
1
1.2
45° N
44° N
43° N
42° N
41° N
123° W 124
° W 125
° W 126
° W 127
° W
Coos Bay
New port
Cape Blanco
Heceta Head
Lat
itud
e
Longitude
PP/PS
Photoprotective:Photosynthetic pigment ratio
0.0903226
0.298387
0.506452
0.714516
0.922581
1.13065
1.33871
30 30.5 31 31.5 32 32.5 33 33.5 349
10
11
12
13
14
15
16
17
18
19
2625
24
23
2223
24
25
Salinity (ppt)Te
mpe
ratu
re (C
)PP/PS
Other alternatives : - Changes in ARP (We just finished analyzing the filter pad particulate absorption samples)- Heat dissipation processes not accounted for
However:
• FLH and CFE are very different MODIS products in terms of validation.
- FLH is based on nLw at 678 nm after baseline correction - CFE is a proxy for f (a physiological
parameter) that requires the previous validation of ARP ([chl] x a*). - Further use of f to infer p requires
the characterization of the variability in energy distribution within the photosystem.
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
Summary
• Fluorescence and chlorophyll– Generally a linear relationship between absorption-based
estimates and fluorescence-based estimates of chlorophyll• Exceptions are apparent, for example near the coast
– Slope of line relating FLH to chl is related to CFE
• Can we estimate chlorophyll from FLH?– Challenge is that many processes affect F
• Photoprotective pigments, absorption cross-section
– Appears, though, that CFE appears to fall into 2 clusters so problem may be tractable
– High values of CFE appear to be associated with communities far from equilibrium
• Time history of CFE may be key