AVHRR, l1b

The Advanced Very High Resolution Radiometer (AVHRR) is a radiation-detection imager flown in various versions on many satellites.  AVHRR instruments typically provide four to six bands of multispectral data. The first AVHRR was a 4-channel radiometer, first carried on TIROS-N (launched October 1978). This was subsequently improved to a 5-channel instrument (AVHRR/2) that was initially carried on NOAA-7 (launched June 1981). The latest instrument version is AVHRR/3, with 6 channels, first carried on NOAA-15 launched in May 1998.


Raw (Level 1b) data consists of a single scene that was collected by a single AVHRR satellite on a specific date and time.   AVHRR data is not georegistered and does not contain coordinate system information, which can be extremely challenging to find for data sets that may be downloaded.  In most cases, it makes greater sense to work with data derived from AVHRR and published in more convenient formats, such as DDR, LAS.



To import from AVHRR .l1b format:


  1. Choose File-Import from the main menu.

  2. In the Import dialog browse to the folder containing data of interest.

  3. Double-click the file ending in .l1b for the data of interest.

  4. A table and one or more images will be created.




In this example, only one image has been created.   AVHRR data will often have multiple images, one for each of the bands that was imaged.   We can double-click the image to view it.   



As seen above, the image is upside down, a typical result with .l1b files, which might have been imaged by the satellite when it was looking to the South.



Rare - AVHRR .l1b files are rarely met in modern times.   When they contain multiple bands, they can be used to create false color RGB images by combining bands, using methods similar to those shown in the Example: Import BIL and Combine 3 Bands  topic.


Source - AVHRR files may be downloaded from the NOAA Comprehensive Large Array - Data Stewardship System (CLASS) web site at https://www.avl.class.noaa.gov/saa/products/welcome   The website provides a very wide range of data for many satellites.   However, AVHRR Level 1b data on the site is rarely provided in .l1b format.   Changing the file extension of .MO files and .WI files downloaded from the CLASS site to .l1b may result in an importable image.


See Also





Example: Import BIL and Combine 3 Bands