The aerosol ultraviolet optical depth observed at a station in the French Southern Alps

F. Guirado; J. Lenoble; A. De la Casiniere; T. Cabot; C. Brogniez

doi:10.1117/12.626803

2 November 2005 The aerosol ultraviolet optical depth observed at a station in the French Southern Alps

F. Guirado, J. Lenoble, A. De la Casiniere, T. Cabot, C. Brogniez

Proceedings Volume 5979, Remote Sensing of Clouds and the Atmosphere X; 59791L (2005) https://doi.org/10.1117/12.626803
Event: SPIE Remote Sensing, 2005, Bruges, Belgium

Abstract

Ultraviolet spectral irradiances are systematically recorded in Briancon (at an altitude of 1310 m), in the French Southern Alps. Up to now, aerosols optical depth (AOD) had never been routinely measured in Briancon, so it has appeared of great interest to take advantage of the many spectra recorded to learn more about aerosols over the spectral range: 320 nm - 448 nm. To retrieve AOD, one only has to remove the contribution of ozone and molecule from the total optical depth, obtained from the direct irradiance. The method has been implemented for every spectra acquired during clear sky days selected among the period from July 2004 to March 2005. Data recorded show that at a given wavelength, AOD is roughly constant during the day. Lowest values for AOD at 12:00 U. T. are found to be around 0.05 at 440 nm and 0.15 at 320 nm, and may increase threefold for some days. AOD range between 320 and 448 nm is larger in summer than in winter. This agrees with the way α, the Angstrom parameter, varies from one season to the other. Unfortunately, one can only make a restricted use of α, as its determination over the ultraviolet range is subject to high AOD uncertainties. The main source of AOD error rests in the 10% of uncertainty on direct irradiance measured. This gives rises to relatively high uncertainties on AOD, which increase all the more when aerosols load in the atmosphere is low. In Briancon, renowned for its air goodness, true AOD values are likely to be reached within 45% - 50% as the best in a majority of cases.

Citation Download Citation

F. Guirado, J. Lenoble, A. De la Casiniere, T. Cabot, and C. Brogniez "The aerosol ultraviolet optical depth observed at a station in the French Southern Alps", Proc. SPIE 5979, Remote Sensing of Clouds and the Atmosphere X, 59791L (2 November 2005); https://doi.org/10.1117/12.626803

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available