Supplement 3.2: SeaWiFS

SeaWiFS stands for Sea-viewing Wide Field-of-View Sensor. It is an optical sensor on-board the OrbView-2 satellite (also called SeaStar) which is operated by the American company GeoEye. Launched 1st August 1997 the SeaWiFS instrument began scientific operations on 4th September 1997.

The SeaStar satellite over North America
The SeaStar satellite over North America.
Source: NASA

The SeaWiFS instrument has been specifically designed to monitor ocean characteristics such as chlorophyll-a concentration and water clarity. It thus looks at ocean colour.

Global biosphere map
This SeaWiFS image of our world depicts the Global Biosphere - the ocean's long-term average phytoplankton chlorophyll concentration acquired between September 1997 and August 2000 combined with the SeaWiFS-derived Normalized Difference Vegetation Index (NDVI) over land.
Source: NASA
More information about the global biosphere image ↓

The SeaWiFS Mission is a part of NASA's Earth Science Enterprise, which is designed to look at our planet from space to better understand it as a system in both behaviour and evolution.

the SeaWiFS instrument
The SeaWiFS instrument
Source: NASA

The instrument is able to tilt up to 20 degrees to avoid sunlight from the sea surface. This feature is important at equatorial latitudes where glint from sunlight often obscures water colour.







The spatial resolution of the SeaWiFS sensor is 1.1 km at nadir (looking straight down on the Earth). It records information in the following bands:

Band Wavelength Colour
1 402-422 nm Violet
2 433-453 nm Blue
3 480-500 nm Blue
4 500-520 nm Green
5 545-565 nm Green
6 660-680 nm Orange
7 745-785 nm Near-Infrared
8 845-885 nm Infrared

Mission characteristics

  • Orbit Type: sun synchronous at about 705 km altitude
  • Equator Crossing: noon +20 min, descending
  • Orbital Period: 99 minutes
  • Revisit Time: 1 day

Some interesting links about SeaWiFS

Where is SeaWiFS now? Design your own SeaWiFS globe The SeaWiFS project
Where is SeaWiFS now? Design your own SeaWiFS globe The SeaWiFS project