AIMS Remote Sensing Atlas Data Description
Introduction
The AIMS Remote Sensing Atlas (atlas) is a web based facility which
provides access to ocean related data products derived from satellite
remote sensing measurements. There are three products available
currently with more to be added in the future. The current products
are Sea Surface Temperature (SST), Chlorophyll a (Chl a) and the
diffuse attenuation coefficient at 490nm (K490). The data is presented
as a daily "snapshot" for the region bounded by 7 deg S to 28 deg S
latitude and 142 deg E to 158 deg E longitude. The atlas provides
facility to view, query and download (with limitations) the data for
these products.
Please read the following caveats before applying data downloaded
from this site.
Disclaimer
Care in interpretation –
Users of this data should be aware that it is experimental and
significant errors may exist. It is being made available for
educational and research purposes particularly by CRC Reef Research
affiliates. In particular some of the data may have errors due to
undetected cloud and other aerosols. This may produce reductions in
the apparent SST.
SST is measuring only the skin layer (<1mm) and is a spatial
average of over 1km. Algorithms are dependant upon wind speed and the
relationship with the so called bulk water temperatures that are
usually referenced to be at 1m below the surface.
So care needs to be taken when comparing with other in situ
measurements,
Ocean colour in shallow coastal regions can see the bottom and may
not indicate true water column colour. The Chl a algorithms are
designed for open ocean waters only. Nevertheless significant features
shown in the data allow the complexity of coastal and ocean waters to
be revealed.
Data Sources
The satellite data used to derive the current products were
received at AIMS using the local HRPT direct broadcast receiving
station. Future products may include data obtained from other sources.
The SST data is derived from the AVHRR/2 or AVHRR/3 sensor on board
the NOAA series of satellites. The Chl a and K490 products are both
derived from the SeaWiFS sensor on board the Seastar or Orbview 2
satellite. The NOAA satellites are operated by the US National Oceanic
and Atmospheric Administration. The data from these platforms is
freely available to anyone with a receiving system and there is no
limitation on data distribution. The Seastar satellite is operated by
GeoEye (formerly Orbimage Inc.) and the distribution of data from this
platform is restricted by a research agreement with that company.
Product Details
The SST product is based only on the overpasses from the satellite
NOAA designates as the "primary PM" satellite. This refers to the
satellite with the best current performance (usually
the most recently launched of those still operating) which has the
daylight part of its orbit occurring in the local solar afternoon.
This is significant in that recent research has shown that these
"afternoon passes" can give a biased estimate of the SST due to
diurnal variation in surface temperature. Future improvements planned
include using the morning and night-time overpasses.
The SST calculation is performed using a method very similar to
that used for the
NOAA Coastwatch Region SST
and use the
NOAA/AVHRR operational SST algorithms and coefficients
Further details of the processing can be obtained from the authors.
The Chl a and K490 (ocean colour products) have been produced using
the
and
K490
Acknowledgements
If you use data or products from this resource please acknowledge
the source with a reference such as shown below.
SST data was provided by the AIMS Remote Sensing and Data Centre,
Townsville, Queensland, Australia, from their web site at:
www.aims.gov.au/pages/remote-sensing.html
In publications:
Mahoney M, Slivkoff MM, Rehbein MA, Crossman D and Steinberg CR
(2006) AIMS-CRC Reef Remote Sensing Web Atlas. Australian Institute of
Marine Science.
Research
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