Himawari

Himawari-8 and -9 are geostationary weather satellites operated by the Japan Meteorological Agency (JMA). They are successors to JMA's Multi-functional Transport Satellite (MTSAT) series, offering significant improvements in frequency, resolution and precision.

Like the MTSAT series, Himawari-8 and -9 are three-axis-stabilised satellites - increasing or decreasing the rotational speed of any of 'wheels' in each axis can adjust the satellites' orbital path or correct for roll, pitch and yaw.

The Advanced Himawari Imager (AHI) instrument carried by both Himawari-8 and -9 records more data than previous geostationary meteorological satellites - 16 channels, including three visible wavelength bands (red, green and blue) to create 'true-colour' images of the Earth. Different channels give us greater insights into different characteristics of the atmosphere.

Imagery from the AHI instruments also has finer spatial resolution (0.5 to 2 km, compared to 1 to 4 km for MTSAT) and precision (12 to 14-bit images, vs 10-bit for MTSAT). It also has higher temporal resolution; that is, new images are recorded more frequently, with one 'full disk' scan of the observable area every ten minutes (compared to hourly from MTSAT).

Unlike the MTSAT orbital configuration (with MTSAT-1R at 140E, MTSAT-2 at 145E), Himawari-8 and Himawari-9 orbit in close formation, both at around 140.7E (in line with Japan, Papua and central Australia). This will offer the same view when operations are switched between the satellites.

Band Central wavelength (µm) Spatial resolution (km)
1 0.43 - 0.48 1
2 0.50 - 0.52 1
3 0.63 - 0.66 0.5
4 0.85 - 0.87 1
5 1.60 - 1.62 2
6 2.25 - 2.27 2
7 3.74 - 3.96 2
8 6.06 - 6.43 2
9 6.89 - 7.01 2
10 7.26 - 7.43 2
11 8.44 - 8.76 2
12 9.54 - 9.72 2
13 10.3 - 10.6 2
14 11.1 - 11.3 2
15 12.2 - 12.5 2
16 13.2 - 13.4 2