I-CONTENTS
------------------------
These folders contains AHS images acquired for the EUFAR BIOHYPE 2010 campaign. The details of the flight campaign are reported in a separate document. 

There is one folder per flight date, named as AHS_YYMMDD (YearMonthDay, two digits each). 
In the next level, there is a folder for the at-sensor radiance data, named L1b, a folder for the georeferenced images, named L1c, and a folder for quality assessment, named QA.

Within the L1b/L1c folders there is a separate sub-folder for each flightline, named as YYMMDD_PXXHR. In this sub-folders you will find:

For L1b images:
>AHS at-sensor radiance, in nW/(cm2 sr nm), in ENVI BSQ format:
1-AHS data, reflective bands: AHS_YYMMDD_HHMMZ_PXXHD_L10020_PT12.raw / .hdr  (only in daytime flights
2-AHS data, thermal bands: AHS_YYMMDD_HHMMZ_PXXHD_L00120_PT34.raw / .hdr
3-Image Geometry Map (IGM) files, for georreferencing (reference system: UTM 31, WGS84).
>Metadata for 1) and 2): MD_*.xml

For L1c images:
>Sample georeferenced AHS bands (reference system: UTM 31, WGS84) in ENVI BSQ format:
1-AHS data, three reflective bands: AHS_YYMMDD_HHMMZ_PXXHD_L10022.bsq / .hdr
All georeferenced images are provided in a 5 m spatial grid and have been resampled with a nearest neighbour rule.

Within QA folder, you will find a summary of statistics and background data for each image. The content of these files is reported in the document statscsv_values_2010.doc. You will also find an image displaying the number of bands which show saturation for each pixel.

The code for identifying scenes with the filename is as follows: 
P........................fixed value, standing for "Pass"
XX......................scene number according to flight plan
H........................a single code to identify the fligh height. For BIOHYPE it is I ("Intermedio", 2000 m).


II-DATA QUALITY
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RADIOMETRIC ACCURACY. The L1b radiance is computed as follows:

Ls(i,j,k) = [scale(k) * (ND0(i,j,k) - NDbb(i,k))/gain(k) ]

The scale factor was computed at INTA laboratory in September 2010. It is reported in the image_stats.csv file under column "scale". An empirical correction factor has been applied based on the INTA cal/val campaign performed May 2010; this correction factor is reported in the image_stats.csv file under column "CalError".
NDbb is the onboard blackbodies digital value averaged over a small neighbourhood for each scanline.
Gain is the electronic gain value reported in the *flight.csv file, corrected according to laboratory test. 
Band AHS21 has been calibrated with a specific non-linear model based also in laboratory tests. 
The L1b radiance for MIR and TIR bands is computed from the onboard blackbodies records. Note that band AHS67 is defective.

NOISE. Noise level is within specifications except for bands AHS44, AHS46 and AHS80.

SPECTRAL ACCURACY
The spectral responsivity (and therefore band center and FWHM) was measured on April 2010 at INTA facilities with a 0.2 nm resolution monochrometer.

GEOMETRIC QUALITY
The IMU/GPS quality was satisfactory. The georeferencing algorithm renders an accuracy better than one pixel when the provided terrain altitude is correct.


III-CONTACT
------------------
For any question on the characteristics of these images, please contact:

INTA
Area de Teledeteccion - Remote Sensing Laboratory
Cta Ajalvir s/n
Torrejon de Ardoz 
28850 Madrid
SPAIN

phone: 34-91 5201990, 34-91 5201992
email: 
Elena Prado (processing responsible): pradooe@inta.es 
Jose Antonio Gomez (project responsible): gomezsj@inta.es