 |
| Titel |
Differential optical absorption spectroscopy (DOAS) and air mass factor concept for a multiply scattering vertically inhomogeneous medium: theoretical consideration |
| VerfasserIn |
V. V. Rozanov, A. V. Rozanov |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1867-1381
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 3, no. 3 ; Nr. 3, no. 3 (2010-06-29), S.751-780 |
| Datensatznummer |
250001119
|
| Publikation (Nr.) |
 copernicus.org/amt-3-751-2010.pdf |
|
|
|
|
|
| Zusammenfassung |
The Differential Optical Absorption Spectroscopy (DOAS) technique
is widely used to retrieve amounts of atmospheric species from
measurements of the direct solar light transmitted through the Earth's
atmosphere as well as of the solar light scattered in the atmosphere or
reflected from the Earth's surface. For the transmitted
direct solar light the theoretical basis of the
DOAS technique represented by the
Beer-Lambert law is well studied. In contrast, scarcely investigated is
the theoretical basis and validity range of the DOAS method for those cases
where the contribution of the multiple scattering processes is not
negligible. Our study is intended to fill this gap by means of a theoretical
investigation of the applicability of the DOAS technique for the retrieval of
amounts of atmospheric species from observations of the scattered solar light
with a non-negligible contribution of the multiple scattering.
Starting from the expansion of the intensity logarithm in the functional
Taylor series we formulate the general form of the DOAS equation.
The thereby introduced variational derivative of the intensity
logarithm with respect to the variation of the gaseous absorption coefficient,
which is often referred to as the weighting function, is demonstrated to be
closely related to the air mass factor.
Employing some approximations
we show that the general DOAS equation can be rewritten in the form of
the weighting function (WFDOAS), the modified (MDOAS), and the
standard DOAS equations. For each of these forms a specific
equation for the air mass factor follows which, in general, is not
suitable for other forms of the DOAS equation. Furthermore,
the validity range of
the standard DOAS equation is quantitatively investigated using a suggested
criterion of a weak absorption.
The results presented in this study are intended to provide a basis for a
better understanding of the applicability range of different forms of the
DOAS equation as well as of the relationship between the air mass factor
and the weighting function. To facilitate the understanding of the paper
content for unexperienced reader we start our discussion considering
in detail the standard DOAS technique applied to the observations
of the direct solar light transmitted through the Earth's atmosphere. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|