The nine MISR cameras acquire measurements every 275 m across track (250 m for the An camera). However, the data rate that would be required to transmit all the measurements from the nine cameras in the four spectral bands at that full resolution would exceed the capacity allocated to the MISR instrument on the Terra platform. To retain some of the high spatial resolution of the sensors without exceeding the data transfer quotas, MISR can be operated in two different data acquisition modes:
- In global (default) mode, a special averaging scheme is conducted on-board such that the data from all cameras other than An and all spectral bands other than red are averaged to 1.1 km before transmission to the receiving station. The spectral data (all 4 bands) from the An camera and the directional data in the red spectral band from all 9 cameras are therefore always available at the full spatial resolution.
- In local mode, it is possible to transmit all the data at the full resolution, but only for limited periods of time and therefore for limited regions, typically about 300 km in length (along track). Please refer to the MISR technical documentation for a detailed description of the various programming modes. Users may contact the ASDC User and Data Services office to request local mode observations.