Tenum CALITOO, Руководство пользователя

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October 2016
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3.4 Intercalibration
3.4.1 Principle
The photometer calibration consist to determine by measurements and
calculations, the light raw value given by a device at the atmosphere top, in a
precise wavelength.
In the case of the Calitoo, calibration coefficients are binary numbers and named
CN
0
( Count Numeric zero ). We have CN
0
_465 for the blue, CN
0
_540 for the
green and CN
0
_619 for the red.
3.4.2 Method
The inter-calibration is a calibration method that uses data from reference
photometer to compute AOT data that should measure the photometer to be
calibrated. With these AOT and with a reverse calculation, we find the calibration
coefficients (Cn
0
) . Ideally, you should do both photometer measures at the same
time and same place.
For now, one method of intercalibration is offered : AERONET intercalibration.
This method uses Aeronet network photometers as reference devices,. They are
a world reference for measurements of aerosols.
The CALITOO intercalibration method witch will use a Calitoo photometer as
etalon, is being validated and will be available in a future version of this software.
3.4.3 What is AERONET ?
The program AERONET (Aerosol RObotic NETwork) is a network of land aerosol
measurements made by NASA and PHOTON (photometry for Operational
Processing Standards satellite; Univ. De Lille 1, CNES and CNRS-INSU).
It is greatly expanded by the networks and employees of national agencies,
institutes, universities, individual researchers and partners.
The program feeds an active database for the long term, into the public domain
and easily accessible.
It includes the optical aerosol measurements, micro-physical and radiative
properties of aerosols for research.
Participants in AERONET provide optical observations distributed globally,
spectral depth of aerosols (AOD), the reversion products, the precipitable water in
the various aerosol systems
Aerosols data are optical depth measurements. They are distributed in three
quality levels: Level 1.0 (gross measures), Level 1.5 (cleaned measures, made
without cloud), and the level 2.0 (Quality measures ensured by a second
calibration). Inversions, precipitable water, and other AOD-dependent products
are derived from these levels and may implement additional quality control.