Ocean Time Series Data Products from Systematic Satellite Missions: Moderate Resolution - AVHRR/SeaWiFS/MODIS/VIIRS

Stéphane Maritorena, Whit Anderson, Peter Minnett, Bob Evans, Sam Lavender, Odile Hembise

Science and ApplicationsOC and SST

OC and SST are important variables for• Climate variability, trends• Weather and ocean forecasting• Ocean and atmospheric models (forcing, data assimilation

and validation)• Primary Production• Carbon budget• Heat transfer • …

Satellite data provide best mechanism for producing globally consistent data sets.

SS

T C

han

ges

( 0C

) +3

-1

+2

-2

+1

-3

0

0

-30

+60

-60

+30

NP

P C

han

ges (

%) b

a

cN

PP

NP

PS

ST

SS

T

A few SST time-seriesTime-Series Data Spatial Resolution

Temporal resolution

Time period

GHRSSTL2PL4

1/4 degree - 6km Daily 1985 - Present

MODISThermal IR

Mid-IR4.5 km – 9 km

Daily8-Day

MonthlyAnnual

Feb. 2000 – Present (T)Jul. 2002 – Present (A)

AVHRRPathfinder

v5 4 km

Daily5 Day7 Day8 Day

MonthlyAnnual

1985 - 2006

AVHRR MCSST

NAVOCEANOMiami

2 km – 18 kmWeeklySwath

Nov. 1981 – Feb. 2001Aug. 2001 – Oct. 2005

Aug. 2001 - Present

GOES(Regional)

6 km Hourly May 2003 - Present

NCEP Reynolds

OI – MCSSTIn Situ

2 degreesWeeklyMonthly

1981 - Present

NASA Carbon Cycle and Ecosystems Joint Science Workshop

April 28, 2008

NASA Carbon Cycle and Ecosystems Joint Science Workshop

April 28, 2008

GHRSST-PPGHRSST-PP• GODAE (Global Ocean Data

Assimilation Experiment) High-Resolution SST Pilot Project

• International project begun in late 2004.

• To produce SST fields that contain error statistics for each SST pixel.

• The traceability of the accuracy of the SST pixels through the atmospheric correction and cloud screening algorithms is important to establishing confidence in the SST fields.

• Validation of satellite derived SSTs from a range of sensors, using various in situ radiometers, each with NIST-traceable calibration, is an important component of this project.

SST time-series

• More than 20 years of data• Highly successful data sets • Merged data sets (thermal IR and microwave,

biases correction among sensors)• Perennial (no data gap in sight ?)• NASA MEaSUREs: Merged Ultra High

Resolution (1 km) SST product

Ocean Color time-series (Level-3)

http://www.globcolour.info/index.html

Satisfy emerging demand for validated merged ocean colour derived information

Demonstrate the current state of the art in merging together data streams from different ocean-colour sensors:

MERIS (ESA), SeaWiFS (NASA), MODIS-AQUA (NASA)

Provide a long time-series (10 years) of ocean-colour informationDemonstrate a global NRT ocean-colour service based on merged satellite dataPut in place the capacity to continue production of such time series inthe future and to prepare for full exploitation of Sentinel 3 (ESA) As such, be the initial step of the Ocean Colour Thematic assembly Centre, part of the future EU GMES Marine Core Service

www.globcolour.infohttp://www.enviport.org/globcolour/validation/

GlobColour Objectives NASA CC & E - April 28, 2008

European Service for Ocean Colour

GlobColour ProductsNASA CC & E - April 28, 2008

Global ocean colour data set at 4.6 km, 1/4°, 1° resolution covering 1997-2008 daily, weekly, monthly products:

•Chlorophyll concentration (Chla)•Diffuse attenuation coefficient @ 490nm (Kd490)

•Total Suspended Matter•CDM absorption (aCDM443)•Particle backscattering coefficient (bbp443)•Aerosol Optical Thickness (T865)•Exact normalised water-leaving radiance @ 412, 443, 490, 510, 531, 555, 620nm•Water-leaving radiance @ 670, 681, 709nm•Data quality flags •Cloud fraction •Excess of radiance at ~ 555 nm (turbidity index) (EL555) •Error estimates per pixel for each layer

MODIS-only, MERIS-only

Ocean Color time-series (Level-3)

o Most products are available as Level-2 datao Many other products available through SeaDAS data processingo CZCS (Nov. 1978 – June 1986) and OCTS data are also availableftp://oceans.gsfc.nasa.gov/ http://oceancolor.gsfc.nasa.gov/cgi/level3.pl

Ocean Color time-series (Level-3) Cont’d

Data available at: • ftp:ftp.oceancolor.ucsb.edu/pub/org/oceancolor/REASoN/• OPeNDAP server: http://dap.oceancolor.ucsb.edu/cgi-bin/nph-dods/data/oceancolor/• NASA GIOVANNI (Monthly): http://reason.gsfc.nasa.gov/Giovanni/

Other local/regional time-series exist, e.g. NOAA’s COASTLOOKUpcoming OC sensors: VIIRS (NPP/NPOES), OCL (S3, ESA), OCM-2 (Oceansat-2, ISRO)

ESDRs, CDRs and CAL/VAL

NASA Carbon Cycle and Ecosystems Joint Science Workshop

April 28, 2008

NASA Carbon Cycle and Ecosystems Joint Science Workshop

April 28, 2008

Climate Data RecordsClimate Data Records

• National Academy of Sciences Report (NRC, 2000): “a data set designed to enable study and assessment of long-term climate change, with ‘long-term’ meaning year-to-year and decade-to-decade change. Climate research often involves the detection of small changes against a background of intense, short-term variations.”

• “Calibration and validation should be considered as a process that encompasses the entire system, from the sensor performance to the derivation of the data products. The process can be considered to consist of five steps:

– instrument characterization, – sensor calibration, – calibration verification, – data quality assessment, and – data product validation.”

GHRSST Matchups

Ocean Color Matchups

CAL/VAL

NASA Carbon Cycle and Ecosystems Joint Science Workshop

April 28, 2008

NASA Carbon Cycle and Ecosystems Joint Science Workshop

April 28, 2008

M-AERI cruises and MODIS validation statisticsM-AERI cruises and MODIS validation statistics

ISSUES/CONCERNS

Ocean color time-series

•Bias among sensors exist.This needs to be reconciled to develop CDRs or ESDRs

•Quality issues (aging sensors.e.g. SeaWiFS) ?

•Concerns about the possible interruption of the current time-series

•Is VIIRS going to be a sub-PAR ocean color sensor ?

NASA Carbon Cycle and Ecosystems Joint Science Workshop

April 28, 2008

NASA Carbon Cycle and Ecosystems Joint Science Workshop

April 28, 2008

Long-time series measurements of SSTLong-time series measurements of SST

Multi-decadal time series require accurate measurements from several series of satellites and sensors. All have particular sampling and accuracy problems:

– Infrared polar orbiters (AVHRRs, (A)ATSRs, MODIS’s, Met-Op AVHRR/3… VIIRS):· More complex instruments (MODIS, VIIRS) leads to more instrumental artifacts· Limited degrees of freedom for atmospheric corrections

– Microwave polar orbiters (AMSR-E… AMSR follow-on GCOM-W ):· Calibration issues· Footprint size· Side-lobe contamination

– Infrared geostationary (GOES Imager, MSG SEVIRI… GOES-R ABI ):· No high latitude coverage· Diurnal heating cycle of s/c and instrument (3-axis GOES s/c)

NASA Carbon Cycle and Ecosystems Joint Science Workshop

April 28, 2008

NASA Carbon Cycle and Ecosystems Joint Science Workshop

April 28, 2008

Concerns about sustaining SST CDRsConcerns about sustaining SST CDRs

• Complex instruments need very careful pre-launch characterization

• Accurate validation must be sustained throughout s/c missions

• Overlap of missions of ~1yr desired

NASA Carbon Cycle and Ecosystems Joint Science Workshop

April 28, 2008

NASA Carbon Cycle and Ecosystems Joint Science Workshop

April 28, 2008

Concerns about sustaining validation capabilitiesConcerns about sustaining validation capabilities

• CDRs require traceability to NIST standards

• For AVHRR, (A)ATSR, MODIS, AMSR-E through M-AERI’s and Calibration Facilities at UM-RSMAS

• M-AERI’s > 10yrs old, >3500 sea-days, rely on obsolete components, need replacing

• Calibration Facilities must be sustained

• Ship-based radiometry for validation must be sustained into the NPOESS era

Objectives of this breakout

• Discuss the scientific questions and issues that are being addressed by existing space-based observations.

• Discuss current time series data products and their scientific application• Discuss their future as Climate Data Records (CDRs) and/or Earth System Data

Records (ESDRs).• Discuss calibration/validation, airborne science, in situ observational needs• Identify opportunities, recommend priorities, raise issues or concerns

Questions:• What are the key products (CDR or ESDR) for understanding the ocean over time ?• What does the carbon cycle and ecosystems community and modelers expect or

need of this effort?• What are our biggest challenges in this area, and how do we address them?• Is our list of identified data records complete, or is something missing?• Does the carbon cycle and ecosystems community need to establish priorities for

these and other activities, and, if so, how should they be established?