Twilight tropospheric and stratospheric photodissociation rates derived from balloon borne radiation measurements

ATMOSPHERIC CHEMISTRY AND PHYSICS (Impact Factor: 5.3). 01/2003; DOI: 10.5194/acpd-2-715-2002
Source: DOAJ

ABSTRACT A new ligthweight multichannel moderate bandwidth filter instrument designed to be flown on balloons, is described. The instrument measures the radiation field within the short UV (center wavelength at 312 nm) and long UV (center wavelength at 340 nm). The angular and spectral characteristics of the instrument are discussed and the calibration procedure outlined. Measurements made during a stratospheric balloon flight at twilight conditions from Gap-Tallard, France, are presented and compared with state-of-the-art radiative transfer model simulations. The model simulations and the measurements agree within ±10% (±20%) for solar zenith angles smaller than 93° (90°) for the 340 (312) nm channel. Based on the model simulations of the measured radiation, actinic flux spectra are reconstructed. These are used to calculate various photodissociation rates.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
    ChemInform 09/2007; 38(37). DOI:10.1002/chin.200737278
  • [Show abstract] [Hide abstract]
    ABSTRACT: FastRT is a fast, yet accurate, UV simulation tool that computes downward surface UV doses, UV indices, and irradiances in the spectral range 290 to 400 nm with a resolution as small as 0.05 nm. It computes a full UV spectrum within a few milliseconds on a standard PC, and enables the user to convolve the spectrum with user-defined and built-in spectral response functions including the International Commission on Illumination (CIE) erythemal response function used for UV index calculations. The program accounts for the main radiative input parameters, i.e., instrumental characteristics, solar zenith angle, ozone column, aerosol loading, clouds, surface albedo, and surface altitude. FastRT is based on look-up tables of carefully selected entries of atmospheric transmittances and spherical albedos, and exploits the smoothness of these quantities with respect to atmospheric, surface, geometrical, and spectral parameters. An interactive site,, enables the public to run the FastRT program with most input options. This page also contains updated information about FastRT and links to freely downloadable source codes and binaries.
    Optical Engineering 04/2005; 44(4). DOI:10.1117/1.1885472 · 0.96 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Spectral albedo measurements have been made by three airborne systems (two aircraft and one balloon) over the flat arable land of East Anglia, UK, and above clouds. The spectral albedos measured at the various flight altitudes include the backscattering of the atmosphere beneath the aircraft/balloon, which has to be removed to get the areal spectral surface albedo. Data derived from the airborne spectroradiometers showed the areal surface albedo to be about 0.02 in the UVB (wavelength range between 280–320 nm), increasing with wavelength to about 0.05 at 500 nm. The cloud albedos were measured above two different stratus layers, one completely overcast and one broken. Above the overcast cloud sheet the albedo was independent of wavelength with values between 0.62 and 0.85 depending on position above cloud and altitude. Above the broken cloud layer the averaged albedo spectra showed clear spectral reflection features from the underlying surface mixed with the cloud albedo signatures.
    Journal of Geophysical Research Atmospheres 01/2004; 109. DOI:10.1029/2004JD004768 · 3.44 Impact Factor

Full-text (2 Sources)

Available from
May 21, 2014