The Bureau’s new satellite viewer uses imagery from Himawari-8—a geostationary weather satellite operated by the Japan Meteorological Agency (JMA).
This demonstration product, released on 30 September 2015, will go through a period of testing, feedback and improvement.
The satellite is situated 35 800 km above the equator at longitude 140.7°E (above the western Pacific, in line with Papua and central Australia), so it provides excellent coverage of the Australian region.
To return to the Satellite Viewer, select the website logo web in the top navigation bar.
Himawari-8 provides observations that enable the Bureau to create true-colour images of the Australian region, every ten minutes, based on reflected visible light. These are useful, for example, for identifying fog and low cloud, which may not be visible in thermal infrared images because it has a similar temperature to the ground below. The visible light images only show parts of the Earth that are in daylight during the scan. Areas with no sunlight to reflect are replaced in our ‘Day + Night’ view with greyscale thermal infrared imagery. To match the familiar colour of clouds, the infrared imagery colour table is inversed, which shows cloud as shades of white.
You can also view greyscale images based on one single visible wavelength (in comparison to the true colour image which combines three). These images will appear black in regions of no sunlight, i.e. night-time.
Infrared (IR) images are derived from radiation emitted from the Earth and its atmosphere at thermal-infrared wavelengths (10–12 µm). These images provide information on the temperature of the underlying surface or cloud. IR images are available 24 hours per day because temperatures can always be measured. This is in contrast to visible images, which are only available during daylight hours.
Temperatures are represented by a greyscale, where black and white represent the hottest and coldest areas respectively. As clouds tend to be cooler than the ground or sea below (not always the case for low-lying clouds), they appear as light grey to white.
Ray Zehr from the US National Oceanic and Atmospheric Administration developed the Zehr enhancement, which applies temperature colour ranges to the cold end of the scale. This highlights deep convection that is generally associated with tropical cyclones and thunderstorms.
These images can be useful in tracking the movement of tropical cyclones.
Satellite images are timestamped in ‘UTC’ (Coordinated Universal Time). The timestamp on the images is the start time of the observation of the top of the image from the satellite. It takes approximately ten minutes for Himawari-8 to complete a scan.