Abstract:
SHARP is the ESA Earthnet format for AVHRR and TOVS data generated to provide
an easy data access for the international Remote sensing user community.
SHARP-1 consists of two volumes: AVHRR volume and TOVS volume. In order to
save user time of extracting from the raw data the useful quantities needed for
the problem in in hand, a family of high er level products has been
... proposed by
Earthnet: this is SHARP level-2.
The SHARP level-2A (Calibrated Product) contains calibrated data from the AVHRR
channels (i.e. level 1 data calibrated and converted to measurements of
Equivalent Reflectance, spectral Radiance and Brightness Temperature) and a
classification of the image.
Each pixel contains image data (calibrate), a classification and geographical
information (boundaries, coastlines and lat/long grid flags). Each pixel
consists of 2 bytes; 10 bits are used for image data, 3 bits for the
classification and 3 bits for geographical data. The classification includes
land, cloud, sea, snow/ice and unclassified pixels.
SHARP-2 products are produced from archived SHARP-1 day-time data. SHARP-2
products will not be archived. TOVS data remains the same as for SHARP-1
products.
For the Level 2A product, Level 1 raw data is calibrated and classified
utilizing state-of-the-art algorithms. The visible channels (1 and 2) are
converted from raw data to Equivalent Reflectance, while channels 4 and 5
(infrared) are converted to Brightness Temperature, corrected by nonlinear
effects, and the third infrared channel (3) is converted to Spectral Radiance.
Image data in each band of the Level 2A product:
----------------
Band 1: Channel 1 Equivalent Reflectance
Band 2: Channel 2 Equivalent Reflectance
Band 3: Channel 3 Spectral Radiance
Band 4: Channel 4 Brightness Temperature
Band 5: Channel 5 Brightness Temperature
--------------
Note: 'Band' refers to the output data structure of the SHARP products.
'Channel' refers to the input satellite data acquired in different wavelengths.
This product can be produced with data from all the operating NOAA satellites;
however, if the data is derived from the even-numbered satellites, band 5 is
empty.
Geometric Correction:
Image navigation (location) is carried out during Level 1 data generation,
using the orbital model for the satellite location and is tested by an operator
who carries out further correction if necessary. SHARP-2 products are in the
original spacecraft projection. A location grid of tie points (lat/long) is
given in the suffix data (every 16th image file record).
To order data, please see
http://earth.esa.int/helpandmail/help_order.html 
