Introduction to alos satellite

Satellite profile

The Japanese earth observation satellite program consists of two series ： be used for Atmospheric and oceanic observations The satellite is used for Land observation Satellite of .

ALOS The satellite program follows the Japanese earth resources satellite 1 （JERS-1） And advanced earth observation satellites （ADEOS） Then the land observation program .

ALOS（Advanced Land Observing Satellite） satellite , also called Daichi( In Japanese, it means “ land ”), It was Japan in 2006 The earth observation satellite program launched in . The main purpose of the project is to collect high-resolution land observation data around the world , For scientific research and commercial use . At present, the satellite is planned to launch 4 star ,ALOS-3 The satellite will be launched in the near future （2022 year ）.

Satellite chronology

name	Launch time	End time	remarks
ALOS	2006 year 1 month 24 Japan	2011 year 5 month 12 Japan	3 Instruments
ALOS-2	2014 year 5 month 24 Japan	On track	Radar satellite
ALOS-3	In the near future （ expect 2022 year ）	Undetermined	Optical satellite
ALOS-4	Undetermined	Undetermined	Radar satellite

ALOS satellite

The satellite

On 2006 year 1 month 24 Japan launched from Japan's seed island ;

On 2008 year , ALOS The resulting image is too blurred , Cannot be used for map making ;

On 2011 year 4 month ,ALOS The satellite was found to have deteriorated its solar array , Has switched itself to power saving mode ;

On 2011 year 5 month 12 Japan , The Japan Aerospace Exploration Agency issued an order to the satellite , Turn off its battery and shut down .

ALOS There are three kinds of remote sensing instruments ：

Phased array for day night and all-weather land observation L Type a synthetic aperture radar (PALSAR) instrument ;

Advanced visible and near infrared radiometers for accurate land cover observations 2 type (AVNIR-2) instrument ;

Panchromatic remote sensing for digital elevation stereo mapping (PRISM) instrument .

Instrument parameters

For synthetic aperture PALSAR The instrument parameters are as follows ：

Band	frequency (GHz)	The resolution of the (m)
SAR-L	1.3	10 、100

At present, it is the highest in the market 12.5m Resolution free DEM The image is from ALOS Satellite PALSAR instrument .

Used in optics AVNIR-2 The instrument parameters are as follows ：

Band	wavelength	The resolution of the (m)
1	0.42-0.50 (blue)	10
2	0.52-0.60 (green)	10
3	0.61-0.69 (red)	10
4	0.76-0.89 (near-IR)	10
panchromatic	0.52-0.77（PAN）	2.5

For elevation mapping PRISM The instrument parameters are as follows ：

Band	Wavelength Region (µm)	Resolution (m)
PAN	0.52-0.77	2.5

PRISM It is an optical instrument , In the visible band 2.5 m Observation of the earth's surface with a spatial resolution of . Its data is used to create high-precision digital elevation models (DEM).
The instrument has three optical systems , Used to obtain terrain data with altitude information . It is in three directions along the satellite orbit at the same time （ Forward direction 、 Lowest point and backward ） Collect data .
Each optical system consists of three off-axis mirrors for push broom scanning . The width of the observation band is 70 km , Front and back observation belt 35 km .

ALOS-2 satellite

ALOS-2 yes ALOS Follow up tasks for .JAXA （ Japan Aerospace Research and Development Agency ） stay ALOS After stopping operation , Start to ALOS-2 Carried out research and development activities , The satellite is on 2014 launch , Currently, it is the only one in orbit ALOS satellite .

Main task

The satellite improved ALOS Wide range and high-resolution satellite observation technology , Further meet the social needs . The main task of the satellite is ：

1. Carry out detailed disaster monitoring in the affected areas ;
2. Update data archives related to national land and infrastructure information ;
3. Effective monitoring of cultivated land ;
4. Global monitoring of tropical rain forests to identify carbon sinks .

Band parameters

ALOS-2 Satellites have a variety of observation modes , As shown in the figure below ：

See the table below for resolution and relevant parameters under each mode ：

** SP: HH or HV or VV, DP: HH+HV or VV+VH, FP: HH+HV+VH+VV, CP: compact pol. (experimental)

ALOS-3 satellite

ALOS-3 The satellite is ALOS-1 Successor to the satellite optical mission . And ALOS comparison ,ALOS-3 On board sensors can be used to expand the size and upgrade the performance , The ground resolution is 0.8m And the width is expanded to 70km.ALOS-3 The observation range covers all land areas in the world .

Band parameters

Band number	Band	wavelength （μm）	The resolution of the （ rice ）	width of cloth （ km ）
Band 1	Coastal（ Translated into ： Coast blue ） Band	0.40-0.45	3.2	70
Band 2	blue band	0.45-0.50	3.2	70
Band 3	Green band	0.52-0.60	3.2	70
Band 4	Red band	0.61-0.69	3.2	70
Band 5	Red edge band	0.69-0.74	3.2	70
Band 6	Near infrared band	0.76-0.89	3.2	70
PAN	Panchromatic band	0.52-0.76	0.8	70

Imaging mode

【 Strip chart viewing mode 】 Default observation mode . Coverage area of each track 70 km , Along the track 4000 km .、

【 Stereoscopic viewing mode 】 The stereo pair image of a ground point is obtained from two different directions .

【 Pointing observation mode 】 After receiving the request 24 Within hours , Use the pointing function to align with the lowest point of the satellite in all directions 60 Observe any point in Japan at an angle of degrees .

【 Wide area observation mode 】 During the orbital path, more than... Are observed by multiple scans 200 km x200 A wide area of kilometers .

【 Change direction observation mode 】 By controlling the attitude of the satellite and changing the observation direction , Observe continuously for more than 1500 Kilometer long area .

ALOS-4 satellite

ALOS-4 Will carry airborne phased array L Band synthetic aperture radar (PALSAR-3) . And PALSAR-2 comparison ,PALSAR-3 The observation performance is further improved . meanwhile ALOS-4 An automatic vessel identification system will be provided (AIS,Automatic Identification System) Receiver , Therefore, the satellite will also receive signals from ships AIS Signal and acquisition PALSAR-3 Images to monitor the ocean , For commercial and military purposes .

Band parameters

at present ALOS-4 The satellite has not yet been launched , The radar related parameters found are as follows ：

Pattern	width of cloth
Stripmap mode (Resolution 3 m, 6 m, 10 m)	100km-200km
ScanSAR mode (Resolution 25 m)	700km
Spotlight mode (Resolution 1 m x 3 m)	35km X 35km

be relative to ALOS-2 satellite ,ALOS-4 The effect is obvious :

Data download

DEM Product data download

Go to the website ：https://search.asf.alaska.edu/#/, Click login sign in, Input NASA Account password of . without , You can use my account ： account number :ruiduobao password ：Ruiduobao123

Then filter the dataset , Choose here ALOS PRISM instrument ：

Then outline the study area , And filter the data , Then select the appropriate data to download ：

In the selected image , choice DEM Download the image ：

Use the downloaded image GIS Software on ：

in addition , We need to pay attention to 12.5m Of DEM Not global , Pay attention to the missing data zone when using . If the study area does not 12.5m Of DEM, It is recommended to use 30m Resolution DEM Resampling acts as 12.5m Use .

Other data download

If additional data is required , Use official data ordering address ：https://alos-pasco.com, Fill in relevant information to place an order , Pay attention to other data ：

Reference resources

JAXA.https://global.jaxa.jp/

ALOSsatellite.https://ja.wikipedia.org/

PASCO.https://alos-pasco.com/

https://eoportal.org/web/eoportal/home