The Advanced Microwave Scanning Radiometer (AMSR) instrument on the Japan Aerospace Exploration Agency's (JAXA) Advanced Earth Observation Satellite-II (ADEOS-II) provided global passive microwave measurements of land, ocean, and atmospheric variables for the investigation of global water and energy cycles.
The AMSR/ADEOS-II L1A Raw Observation Counts (AMSR-L1A) data set was processed from Level 0 science packet data by the JAXA Earth Observation Center (EOC) in Japan. Each half-orbit data granule consists of observation counts, antenna temperature coefficients, offsets for calculating antenna temperatures, calibration temperature counts, land/ocean flags, time, latitude, longitude, and navigation fields in Hierarchical Data Format (HDF).
AMSR is a conical scan sensor that sweeps the surface of the Earth at about ±90 degrees centered at the direction of the satellite flight. The swath width is about 1600 km. It measures horizontally and vertically polarized radiance at 6.9, 10.65, 18.7, 23.8, 36.5, and 89.0 GHz; and vertically polarized radiance at 50.3 and 52.8 GHz. AMSR collected 290 data points per scan for the 6 GHz to 36 GHz channels and 580 data points per scan for the 89 GHz channel. Data are available via FTP, CD-ROM, DVD, or DLT.
The following example shows how to cite the use of this data set in a publication. For more information, see our Use and Copyright Web page.
Japan Aerospace Exploration Agency (JAXA), T. 2007. AMSR/ADEOS-II L1A Raw Observation Counts. Version 2. [indicate subset used]. Boulder, Colorado USA: NASA DAAC at the National Snow and Ice Data Center. http://dx.doi.org/10.5067/ADEOS-II/AMSR/AMSR-L1A.002.
|Spatial coverage and resolution||Southernmost Latitude: -90° N
Northernmost Latitude: 90° N
Westernmost Longitude: -180° E
Easternmost Longitude: 180° E
The sampling interval at the Earth's surface is 5 km for the 89.0 GHz channel and 10 km for all other channels. Spatial resolutions range from 5 km to 50 km.
|Temporal coverage and resolution||2003-01-28 (00:03) to 2003-10-24 (20:50)
|File naming convention||A2AMS03011815MD_P01A0000000|
|File size||Each half-orbit granule is approximately 38 MB.|
|Procedures for obtaining data||Please see the AMSR/ADEOS-II Data at NSIDC: Order Data Web page for information on how to order AMSR products.|
1. Contacts and Acknowledgments
2. Detailed Data Description
3. Data Access and Tools
4. Data Acquisition and Processing
5. References and Related Publications
6. Document Information
Japan Aerospace Exploration Agency
Earth Observation Center
Chuo-ku, Tokyo, 104-6023
NSIDC User Services
National Snow and Ice Data Center
CIRES, 449 UCB
University of Colorado
Boulder, CO 80309-0449 USA
phone: +1 303.492.6199
fax: +1 303.492.2468
form: Contact NSIDC User Services
Level-1A data are in HDF with the following contents:
The dimension of observation count data is 290 observations by approximately 2022 scans for all channels except 89.0 GHz. The dimension of 89.0 GHz data is 580 observations by approximately 2022 scans. The number of scans may fluctuate slightly. Missing data are indicated by a value of -9999.999.
This section explains the file naming convention used for this product with an example.
Example file name: A2AMS03011815MD_P01A0000000
Refer to Table 1 for the valid values for the file name variables listed above.
|Variable for Granule ID||
|Year of data acquisition|
|Month of data acquisition|
|Day of data acquisition|
|Path number at the observation start point (01 - 57)|
|M or R (M = regular process or reprocess, R = near real time process)|
|orbit direction flag (A = ascending, D = descending)|
Variable for Product ID
|P or N (P = regular process or reprocess, N = near real time process)|
|0 (spare field)|
|1A (for Level-1A)|
|0 (spare fields)|
Each half-orbit granule is approximately 38 MB.
Southernmost Latitude: -90° N
Northernmost Latitude: 90° N
Westernmost Longitude: -180° E
Easternmost Longitude: 180° E
AMSR is a conical scan sensor that sweeps the surface of the Earth at about ±90 degrees centered at the direction of the satellite flight. The swath width is about 1600 km.
The sampling interval at the Earth's surface is 10 km for the 6.9 GHz to 52.8 GHz channels, and 5 km for the 89.0 GHz channel. The spatial resolution of each channel is listed in Table 2.
2003-01-28 (00:03) to 2003-10-24 (20:50)
The scanning period is 1.5 s and the data-sampling interval is every 2.6 ms for the 6 GHz to 36 GHz channels, and 1.3 ms for the 89 GHz channel. AMSR collects 580 data points per scan for the 89 GHz channel and 290 data points per scan for all other channels.
A granule of AMSR is defined as a half orbit between the South and North Poles for its observed position on the Earth. An observed position of AMSR is not nadir but a little forward to the satellite flight direction. Therefore, a scan location shifts about 2.5 minutes earlier from the satellite nadir on the orbit, but its center is positioned to the satellite nadir. Each half-orbit granule spans 50 minutes.
See the Level-1A Data Fields document.
The AMSR Instrument Description Web page provides details on potential errors associated with radiometer calibration.
Please see the AMSR/ADEOS-II Data at NSIDC: Order Data Web page to order AMSR products.
Please refer to the AMSR Instrument Description Web page.
AMSR calibration is defined as the task for evaluation and adjustment of Brightness Temperature (TB) data. Radiometeric calibration of the TB data includes an absolute evaluation of the TB value and relative evaluation of the scan bias. The TB calibration also includes regular monitoring of radiometric noise and physical temperature. Geometric calibration evaluates the rough beam patterns, inter-channel co-registration, and absolute position accuracy, as well as regular monitoring of antenna rotation speed and attitude notation. Data quality evaluations were also performed on the quality of initial data, the soundness of all engineering values, and deductive algorithms.
AMSR provides geophysical information relevant to water by receiving weak microwaves naturally radiated from the Earth's surface and atmosphere such as atmospheric water vapor, precipitation, sea surface wind speed, sea surface temperature, soil moisture, sea ice extent, and snow water equivalent. AMSR observes microwaves instead of optical data, and it can observe from day to night, under any weather condition, and in the presence of clouds.
AMSR is an eight-frequency, total-power microwave radiometer with dual polarization (except two vertical channels in the 50 GHz band). Conical scanning is employed to observe the Earth's surface with a constant incidence angle of 55 degrees. Multi frequency measurement is performed by an array of primary horns. Calibration counts are obtained every scan by using the hot load target (around 300 K) and the cold-sky mirror to introduce the temperature of deep space (around 3 K). Table 3 summarizes the AMSR instrument specifications.
|Center Frequency (GHz)||6.925||10.65||18.7||23.8||36.5||50.3||52.8||89.0||89.0|
|Band Width (MHz)||350||100||200||400||1000||200||400||3000|
|Polarization||Vertical and Horizontal||Vertical||Vertical and Horizontal|
|3dB Beam Width (° )||1.8||1.2||0.65||0.75||0.35||0.25||0.25||0.15||0.15|
|Sampling Interval (km)||10×10||5×5|
|Temperature Sensitivity (K)||0.34||0.7||0.7||0.6||0.7||1.8||1.6||1.2|
|Incidence Angle (° )||55.0||54.5|
|Dynamic Range (K)||2.7 - 340|
|Swath Width (km)||Approximately 1600|
The Japan Aerospace Exploration Agency (JAXA) processes AMSR Level 0 data into Level-1A observation count data.
Level-1A processing is performed to derive geometric and radiometric information from edited AMSR data. AMSR Level 0 data pre-processing starts with a quality check for detecting missing data, then all data gaps are filled by dummy data, and then the interpolation of anomalous data is carried out. Once those pre-processing operations are performed, the observation data is extracted to a scene of a half orbit from pole to pole. If a scene is composed of several Level 0 data, the divided input data is edited to make the data for one scene. Initially, Level 0 data includes redundant data so the redundant data is deleted before generating the scene data. In redundant deletion processing, the quality information on corresponding data is compared and the data of the higher quality is chosen.
Earth Observation Research and Application Center (EORC). 2003. ADEOS-II:Midori-II Science Project. http://sharaku.eorc.jaxa.jp/ADEOS2/index.html. Accessed March 2004.
Japan Aerospace Exploration Agency (JAXA). 2003. AMSR Overview. http://www.eorc.jaxa.jp/en/index.html. Accessed March 2004.
Japan Aerospace Exploration Agency (JAXA). 2003. ADEOS-II Data Users Handbook. Tokyo, Japan: JAXA. View PDF file.
National Space Development Agency of Japan. Date unknown. ADEOS-II Reference Handbook. View PDF file.
For more information regarding related publications, go to the Research Using AMSR Data Web page.
The following acronyms and abbreviations are used in this document:
|AMSR||Advanced Microwave Scanning Radiometer|
|ASCII||American Standard Code for Information Interchange|
|DAAC||Distributed Active Archive Center|
|EOS||Earth Observing System|
|EOSDIS||EOS Data and Information System|
|FTP||File transfer protocol|
|HDF-EOS||Hierarchical Data Format - EOS|
|JAXA||Japan Aerospace Exploration Agency (JAXA)|
|JPL||Jet Propulsion Laboratory|
|NASA||National Aeronautics and Space Administration|
|NSIDC||National Snow and Ice Data Center|
|PO.DAAC||Physical Oceanography Distributed Active Archive Center|
|RSS||Remote Sensing Systems|
|SIPS||Science Investigator-led Processing System|
|SMMR||Scanning Multi channel Microwave Radiometer|
|SSM/I||Special Sensor Microwave/Imager|
|URL||Uniform Resource Locator|