For complete details download pdf of the ALOS chapter from Eurimage Products and Services Guide
ALOS, Advanced Land Observing Satellite, offers the largest available combination of spectral, spatial and radiometric characteristics. The mission combines three sensors, two optical and one radar – PRISM (Panchromatic Remote-sensing Instrument for Stereo Mapping), AVNIR-2 (Advanced Visible and Near Infrared Radiometer type 2) and PALSAR (Phased Array type L-band Synthetic Aperture Radar) – on the same platform. The ALOS mission is designed to serve two main lines of application: disaster management and land mapping.
Cartography,
Regional Observation for sustainable development,
Disaster Monitoring
Resources Surveying
PRISM: the Panchromatic Remote-sensing Instrument for Stereo Mapping for digital elevation mapping;
AVNIR-2: the Advanced Visible and Near Infrared Radiometer type 2 for precise land coverage observation;
PALSAR: the Phased Array type L-band Synthetic Aperture Radar for day-and-night and all-weather land observation.
Daytime observation modes: PRISM (fore, nadir & aft) and AVNIR-2.
Nighttime observation modes: PALSAR (Note: AVNIR-2 and PALSAR are able to operate simultaneously).
The PRISM (Panchromatic Remote-sensing Instrument for Stereo Mapping) system has a 2.5 m spatial resolution.
The PRISM system provides along-track stereoscope images by means of three independent telescopes. The forward and the backward looking telescopes are inclined +/- 24º from nadir, respectively. This
configuration achieves stereoscopic vision with a Base to Height ratio of 1.0 for obtaining best stereo mapping data. Each radiometer will use electrical pointing function (within +/- 1.5 degree), to
compensate Earth rotation and thus to provide fully overlapped three-stereo (triplet) images (35 km width) without mechanical scanning or yaw steering of the satellite.
In addition to the 35 km triplet (OB1) mode), the PRISM can also acquire a 70 km nadir image but only in combination with a back-looking image (OB2) or alone (OB3). Most acquisitions are made in OB1 mode.
AVNIR-2 (Advanced Visible and Near Infrared Radiometer) is a visible and nearinfrared radiometer with 10 meters spatial resolution in four spectral bands.
The swath width is 70 km at nadir and the pointing angle can be varied across track in a +/–44º range to allow a target revisiting time of up to one day.
The PALSAR is a right-looking SAR using L-band frequency with a cross-track pointing capability of 18º – 55º.
The PALSAR has 4 basic observation modes: fine resolution, SCANSAR, polarimetric and Direct Downlink.
Fine resolution mode gives 10 m spatial resolution in both range and azimuth (70 km of swath width, -25 dB of noise equivalent backscattering coefficient, and 25 dB of Signal-to-Ambiguity (S/A) ratio at a look angle of 35º).
Single polarisation (HH or VV) or dual polarisation (HH/HV or VV/VH) modes are available.
The ScanSAR mode offers more than 250 km width of SAR images at the cost of spatial resolution (100 m). When an optimised orbit is used, one can revisit the same target area in less than five days.
Direct Downlink mode has a resolution of 20m and HH or VV polarisation. Swath is 70 km.
Polarimetric mode has a resolution of 30m on a 30 km swath, but offers a complete polarisation scheme (HH/HV or VV/VH).
ALOS instruments can observe the surface of the entire world, subject to cloud cover for the optical instruments, with the following revisit:
Anywhere within two days
Near the equator: about 60% of the area within one day
At latitudes 35º: about 70% of the area within one day
At latitudes larger than 55º: any place every day
ALOS products follow the standard CEOS format convention. The detailed product format specifications have been defined and are maintained by JAXA.
JAXA has defined an ALOS basic observation scenario based on seasonal observations, aimed at properly supporting the mission objectives. This observation plan:
covers the 3 years of nominal operations
has priority over individual user requests
does not mean systematic coverage, so planning requests compliant to the mode for that period are possible
See the following addresses for details on acquisition planning:
Input for programming can also come from customer requests for large areas or strategic projects.
Comprehensive details on ALOS can be found here
Catalogues: