# Presentation: 064908

## Beyond Chlorophyll:Ocean color ESDRs and new products

- S. Maritorena, D. A. Siegel and T. Kostadinov
- Institute for Computational Earth System Science
- University of California at Santa Barbara

## Beyond Chlorophyll: Ocean color ESDRs and new products

**Motivations and rationale.**
- CHL is the historical product derived from satellite ocean color observations
- Progress in ocean color modeling and improved sensors now allow various other variables to be retrieved from satellite-measured  normalized water-leaving radiance spectra.
- Because more and more bio-optical and biogeochemical variables are now routinely measured at sea, it is possible to evaluate and validate some of these products.
- Once validated this products have the potential to become Earth Science Data Records (ESDR).
- Some other products cannot be directly validated, generally because there is  no or few validation data currently available but it is conceivable that they can be validated in the next decade.
- Through our participation in NASA’s EOS, REASoN CAN and MEaSUREs programs we have or are developing new ocean color products. These products are described and some are presented here.

## Ocean color products (REASoN, MEaSUREs and EOS programs)

| Product | Link to biogeochemistry | Algorithm |
| --- | --- | --- |
| Chlorophyll-a  | Phytoplankton biomass; Primary Production  | GSM semi-analytical model  |
| acdm() | Photochemistry; Heterotrophic production; Light budget | GSM & 
QAA algorithms |
| aph() | Physiology and type of phytoplankton; Primary Production; trophic state | GSM &
QAA algorithms |
| bbp( | Particulate material; POC | GSM & QAA
Loisel et al. (2006) |
| S - acdm() spectral slope | Photochemistry, CDOM origin & bleaching history | GSM semi-analytical model
QAA algorithm |
|  - bbp( spectral slope | Particle size distribution
Export flux | Loisel et al., (2006) |
| Kd(UV) | Light Budget, Photochemistry | Siegel et al. (2007) |
| Phytoplankton Functional Types | Primary Production
Carbon fluxes | Alvain et al. (2004, 2006) |
| Net Primary Production  | Primary Production
Carbon fluxes | VGPM & CbPM  |
| Merged products
(chl, acdm(443), bbp(443) | Phytoplankton biomass, Primary & secondary production, Particulates, POC, Photochemistry | Maritorena & Siegel (2005) |

**Ocean color products ****(REASoN, MEaSUREs and EOS programs)**

## Merged data sets

- Temporal coverage

- Spatial coverage

- Matchups

-  ftp:ftp.oceancolor.ucsb.edu/pub/org/oceancolor/REASoN/
-  OPeNDAP server: http://dap.oceancolor.ucsb.edu/cgi-bin/nph-dods/data/oceancolor/

## New products = Kd(UV)

- Model development relies on 2 main assumptions:
- Kd(λUV) can be modeled using the single scattering approximation.
- Kd(λUV) = f[a(λUV), bb(λUV)]
- CDOM is mostly responsible for Kd(λUV) variability
- Model uses the products from the GSM model (CHL, CDM, BBP) in the visible (443 nm) to predict Kd(λUV)
- Kd(λUV) = Kw(λ) + CC(CDM)exp(-S(CDM)(λ-443)) + aph*(λ0) + β0 BBP (λ-443)-1

**Notes:**
CC(CDM) and S(CDM) are polynomial functions of CDM(443). All parameters of the model are determined using a large in situ LwN (to get GSM products) – Kd(UV) data set. Downhill simplex.

## New products - PSD (Tiho Kostadinov)

- m = n – ik = Complex index of refraction
- ξ = Junge slope of the PSD
- D = particle diameter [m]
- D0 = reference diameter (2 μm)
- N0 = N(D0) = number of particles per volume of seawater normalized by the bin size width (m-4) for the reference Diameter

- Measured

- bbp() efficiency
- solved by Mie theory

- Retrievals

- N(D) = N0 (D/D0)-

- PSD follows a Junge distribution

- Mie theory provides a link between measurable optical properties and the Junge PSD!

## New products - PSD

- log10(particles/m-4)

**Associated products:**
- Total Biovolume
- Partitioned Biovolumes (phytoplankton size classes)
- Partitioned Number concentration

**Current Plans**
- Validation – need more PSD & bbp() !!!
- Complete error and sensitivity analysis

## GSM model development - Global

**Original GSM01 with NOMAD data**
**aph(********) parameterization is not ideal**

**“****Improved” GSM tuned with NOMAD data**
**aph(********) parameterization is more realistic**

- Working on solving for CDOM slope, backscattering slope
- Drop the quadratic formulation
- IOP workshop

## GSM model development – Coastal waters

**Use of Coastlooc data (European coastal waters)**
** ****Run original GSM model**
** ****Adapt the model so it can handle any wavelength**
** ****Use bands in the 570-700 nm range**

- Original 5 bands version

- All bands version

**Notes:**
Fluorescence component to be added

## Thank you.