Applications IMOS Ocean Colour baseline products in combination with the BODB support the development and validation of regionally robust coastal water quality algorithms. One example, is the eReefs project that built on the IMOS archiving and processing facilities to develop validated coastal ocean colour products for the Great Barrier Reef Marine Park region, which are served through the Marine Water Quality Dashboard operated by the Australian Bureau of Meteorology.

At the IMOS National Reference Stations, such as Maria Island, ocean colour time series data is used to evaluate and correlate bio-optical measurements from obtained from long-term deployments of EcoTriplet and WQM sensors. Daily MODIS-Aqua chlorophyll-a imagery are also provided through IMOS Ocean Current and are merged with satellite sea surface height observations data showing geostrophic surface current velocities.

IMOS Satellite Ocean Colour Time Series Products for Australia Thomas Schroeder1, Edward King2, Roger Scott2

1CSIRO Oceans and Atmosphere, Brisbane, Queensland, Australia, 2CSIRO Oceans & Atmosphere, Hobart, Tasmania, Australia

www.imos.org.auIMOS is a national collaborative research infrastructure,

supported by Australian Government. It is led by University of Tasmania in partnership with the

Australian marine and climate science community.

ACKNOWLEDGEMENTSFOR FURTHER INFORMATIONe Thomas.Schroeder@csiro.aue Edward.King@csiro.auw http://imos.org.au/srs.html

We acknowledge the Ocean Biology Processing Group (OBPG) at the NASA Goddard Space Flight Center, Greenbelt, MD, USA and also the National Computational Infrastructure in Canberra.

Data Access The IMOS123 data portal (right) is the primary means of discovering and accessing all IMOS data. The portal allows browsing of the gridded products, download of spatio-temporal subsets in netCDF, and access via THREDDS, which supports OPeNDAP.

IMOS also operates the OceanCurrent web site (right) which provides product imagery with context from other IMOS observations and commentary for many sub-regions (see poster by Griffin & Cahill).

For users requiring direct access to any data set (including unmapped lower level products) all data are openly available on the large data storage at the NCI in Canberra, from where they are exposed in the filesystem and via WWW and THREDDS servers.

Range of Products A key benefit of the local production provided by IMOS is that the ocean colour data are available at multiple levels through the processing chain, ranging from at-sensor radiances through to at-surface reflectances, and derived in-water properties, including both standard NASA-supported and experimental products. Additionally it is possible to obtain these data at the various processing levels before they have been remapped or aggregated (in either space or time) enabling their use in a wider range of applications.

The IMOS system provides:• whole-of-mission temporal coverage for Australasian region ([5S,90E]-[55S,180E])• ability to reprocess, with up to date calibration without need to download from overseas• full resolution data (1km for SeaWiFS and MODIS, 750m for VIIRS)• unmapped single swath products for matchup analyses• a large suite of outputs such as reflectance at mean sea level, ancillary and diagnostic

products to support new algorithm development• un-averaged daily product maps for specific regional subsets

IntroductionOcean colour observations from satellite have been routinely available for nearly two decades; initially with the launch of the SeaWiFS sensor in 1997, then MODIS/Aqua in 2002 and, most recently, with VIIRS on Suomi/NPP launched in 2012. While NASA has sought to make products from these missions available, they have typically been in the form of derived products (e.g. Chlorophyll-a) binned and mapped at 4 or 9 km resolution globally and often are also time-averaged. These data sets are often less suitable for coastal applications, developing regional algorithms, or for characterising product accuracy through in-situ matchups, where finer spatial resolution data is required. To address these needs, IMOS has supported the assembly of Australasian archives of raw data from all three missions and established a processing system, based on NASA’s standard ocean colour processing software (SeaDAS), at the National Computational Infrastructure (NCI).

Product Validation

Future OutlookWith MODIS-Aqua well beyond its designed lifetime (5 years) the IMOS ocean colour sub-facility is preparing for future ocean colour missions such as the European Sentinel-3 (launch late 2015) to provide continuity of the ocean colour time series started in 1997. In addition, delivery of experimental products from geostationary Himawari-8 as well as historical data from the MERIS mission (2002-2012) will be explored.

Below: Daily chlorophyll (OC3) mosaic for Australia (left), and monthly median chlorophyll (right)

Below: Comparison of IMOS daily chlorophyll (1km, LHS) with NASA global product (4km, RHS). LHS image courtesy OceanCurrent

1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016

18.09.1997 (NASA) 11.12.201001.03.2002 (ESA) 12.04.2012

07.10.2014

(JAXA)

28.10.2011 (NASA,NOAA)

04.05.2002 (NASA)

ongoing

ongoing

ongoing

MERIS

MODIS-Aqua

VIIRS

Himawari-8

SeaWiFS

Nationally consistent evaluation of ocean colour products is achieved by match-up analysis using the IMOS Bio-Optical Data Base (BODB).

The BODB collates in-situ discrete physical, bio-geochemical, and optical data collected by the Australian bio-optical community from 1997 to date in the Australasian region. Product uncertainty depends on optical complexity of the water mass as well as accuracy of the atmospheric correction. Coastal waters are usually more complex due to terrestrial inputs compared to the open ocean.

IMOS has therefore adopted a classification of optical water types (OWT, Moore et. al 2009) in the assessment of product accuracy.

Radiometric data collected the IMOS Lucinda Jetty Coastal Observatory (LJCO) are critical to quantify atmospheric correction errors that directly impact on the accuracy of ocean colour products. In-water bio-optical measurements from LJCO are added on regular basis to the BODB and submitted to international space agencies for incorporation into their respective validation data bases (SeaBASS (NASA), Mermaid(ESA)). Data provision from the Australasian region will ultimately enhance the applicability of global standard algorithms to both hemispheres and increase product accuracy.

Products Swath (L2) Gridded Daily Gridded Monthly

Chlorophyll (OC3, OC4, OCI, GSM, Carder algorithms) Yes OC3/OC4/GSM OC3/GSM

K_490 - diffuse attenuation coefficient at 490nm Yes Yes Yes

PAR & IPAR - Photosyn. Avail. Radiation (mean and instantaneous) Yes Yes PAR

Lw_nnn, nLw_nn, rrs_nnn – Water leaving radiance, RS reflectance Yes - -

Eppley NPP – VGPM-based net primary productivity Yes Yes Yes

Zeu and Zsd - Euphotic and Secchi depths Yes - -

+ IOPs, geometry, atmospheric parameters, flags and many others

Yes - -

Above: Locally created experimental products, such as phytoplankton size classes (pico, nano, micro, LHS) and Net Primary Productivity (RHS), are available. The facility may be able to assist users to create and/or serve research products which they are prepared to share with the community.

Right: Swath subsets can be extracted for all products for

match-ups with in situ observations

Left: True colour and/or browse imagery is available to assist with scene selection

imos.aodn.org.au/imos123/

Oceancurrent.imos.org.au

A copy of all the gridded data sets is also held by CSIRO where a THREDDS server is supported (left), together with some other experimental servers. THREDDS supports direct file access, and also the OPeNDAP and OGC Web Mapping Service protocols.

A particularly useful tool within THREDDS is the GODIVA viewer which enables visualisation of all the data in the gridded data sets.

An experimental ERDDAP server (created by NOAA in the US) is also available to access selected gridded data products.

Rs-data1-mel.csiro.au (THREDDS)

Rs-data1-mel.csiro.au (GODIVA)

Rs-data1-mel.csiro.au/erddap

ERDDAP enables a GUI to subset and view data, and offers a very wide range of download formats, including netCDF, Matlab and CSV.

imos.aodn.org.au/imos123/