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Arne Dahlback

Bio: Arne Dahlback is an academic researcher from Norwegian Institute for Air Research. The author has contributed to research in topics: Ozone depletion & Skin cancer. The author has an hindex of 9, co-authored 18 publications receiving 670 citations.

Papers
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Journal ArticleDOI
TL;DR: In this article, a solution of the radiative transfer equation valid for a spherical atmosphere is presented, based on a perturbation technique combined with the discrete ordinate method, for large solar zenith angles.

286 citations

Journal ArticleDOI
TL;DR: A method to derive biologically effective UV dose rates, total ozone abundances, and cloud optical depths from irradiance measurements with moderate bandwidth filter instruments that have only a few channels in the UV region is described.
Abstract: I describe a method to derive biologically effective UV dose rates, total ozone abundances, and cloud optical depths from irradiance measurements with moderate bandwidth filter instruments that have only a few channels in the UV region. These quantities are determined when the measured irradiances are combined with radiative transfer calculations. The method was applied to a four-channel filter instrument with center wavelengths at 305, 320, 340, and 380 nm and bandwidths of 10 nm. I compared the instrument with a high-wavelength-resolution spectroradiometer during a 1-week period in San Diego, California, with variable cloudiness. The relative difference in Commission Internationale de l’Eclairage (CIE)-weighted UV dose rates for solar zenith angle’s (SZA’s) < 80° was 1.4 ± 3.2%. The relative difference for clear sky was 0.6 ± 1.5% for SZA’s < 80°. The total ozone inferred from the irradiance measurements with the filter instrument is insensitive to clouds. The instrument was compared with a Dobson and a Brewer instrument in Oslo, Norway, 60 °N, for more than 1 year. The relative difference in derived ozone abundance for the entire period, including cloudy days, was 0.3 ± 2.9%. The standard deviation was reduced to 1.9% when only clear sky and SZA’s < 60° were included. By using the total ozone and the cloud optical depth derived from the filter instrument as input to a radiative transfer model, one can compute a complete spectrum from 290 to 400 nm with 1-nm resolution. Such calculated spectra are in good agreement with spectra measured simultaneously with a high-wavelength-resolution spectroradiometer for clear as well as cloudy sky conditions and can be used to determine dose rates for any desired action spectrum. Only one UV-B channel and one UV-A channel are required to compute the spectra.

145 citations

Journal ArticleDOI
TL;DR: Comparisons of relative densities of CMM, SCC, LMM and SCC falling per unit area of skin at different parts of the body indicate that sun exposure is the main cause of these cancer forms although other unknown factors may play significant roles as well.
Abstract: During the period 1957-1984 the annual age-adjusted incidence rate of cutaneous malignant melanoma (CMM) increased by 350% for men and 440% for women in Norway. The annual exposure to carcinogenic sunlight in Norway, calculated by use of measured ozone levels, showed no increasing trend during the same period. Thus, ozone depletion is not a cause of the increasing trend of the incidence rates of skin cancers. The incidence rates of basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) increase with decreasing latitude in Norway. The same is true for CMM in Norway, Sweden, and Finland. Our data were used to estimate the implications of a future ozone depletion for the incidence rates of skin cancer: a 10% ozone depletion was found to give rise to a 16-18% increase in the incidence rate of SCC (men and women), a 19% increase in the incidence rate of CMM for men and a 32% increase in the incidence rate of CMM for women. The difference between the numbers for men and women is almost significant and may be related to a different intermittent exposure pattern to sunlight of the two sexes. The increasing trend in the incidence rates of CMM is strongest for the trunk and lower extremities of women, followed by that for the trunk of men. The increasing incidence rates of skin cancers as well as the changing pattern of incidence on different parts of the body is most likely due to changing habits of sun exposure. Comparisons of relative densities of CMM, SCC, LMM and SCC falling per unit area of skin at different parts of the body indicate that sun exposure is the main cause of these cancer forms although other unknown factors may play significant roles as well. For the population as a whole sun exposure during vacations to sunny countries has so far been of minor importance in skin cancer induction.

81 citations

Journal ArticleDOI
TL;DR: In this article, the ozone DIAL system at the ALOMAR facility at Andoya showed significant reduction of ozone mixing ratios in the 430 to 580 K potential temperature region, reaching a maximum reduction of almost 50% occurred at about 500 K between early January and early March.
Abstract: In winter 1995/96, the stratospheric ozone layer over most of the European Arctic was exposed to extremely low temperatures and strong PSCs. At the same time, total ozone monitoring instruments at Tromso and Andoya, Northern Norway, observed values up to 50% below the long-term average values of the Dobson instrument at Tromso. The deviation increased systematically with time of the year, reaching a maximum in early March. Measurements with the ozone DIAL system at the ALOMAR facility at Andoya showed significant reduction of ozone mixing ratios in the 430 to 580 K potential temperature region. A maximum reduction of almost 50% occurred at about 500 K between early January and early March. Comparison with 3D model calculations revealed large reductions with respect to passive tracer ozone profiles in the 400 to 600 K region, reaching a maximum of about 60% by the end of March at the 475 K level. The 3D chemical model showed ozone depletion in the same altitude region as the measurements but seemed to underestimate the depletion systematically. The comparison also indicated ozone depletion of up to 30% in the 475 to 675 K region in extra-vortex air which remained close to the vortex edge during a period in mid-March.

65 citations

Book ChapterDOI
01 Jan 1993
TL;DR: Skin cancer is a serious problem in the Scandinavian countries, as it is in most countries with white populations (Magnus, 1989, 1991; Muir and Nectoux, 1982).
Abstract: Skin cancer is a serious problem in the Scandinavian countries, as it is in most countries with white populations (Magnus, 1989, 1991; Muir and Nectoux, 1982). Scandinavia is located at high latitudes (>54°N) and therefore receives relatively small annual exposures of ultraviolet (UV) radiation from the sun. In spite of this, skin cancer (cutaneous malignant melanoma, squamous cell carcinoma, and basal cell carcinoma) is more frequent than any other cancer form.

38 citations


Cited by
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Journal ArticleDOI
TL;DR: The code is a marriage of a sophisticated discrete ordinate radiative transfer module, low-resolution atmospheric transmission models, and Mie scattering results for light scattering by water droplets and ice crystals that are well suited for a wide variety of atmospheric radiative energy balance and remote sensing studies.
Abstract: SBDART is a software tool that computes plane-parallel radiative transfer in clear and cloudy conditions within the earth's atmosphere and at the surface. All important processes that affect the ultraviolet, visible, and infrared radiation fields are included. The code is a marriage of a sophisticated discrete ordinate radiative transfer module, low-resolution atmospheric transmission models, and Mie scattering results for light scattering by water droplets and ice crystals. The code is well suited for a wide variety of atmospheric radiative energy balance and remote sensing studies. It is designed so that it can be used for case studies as well as sensitivity analysis. For small sets of computations or teaching applications it is available on the World Wide Web with a user-friendly interface. For sensitivity studies requiring many computations it is available by anonymous FTP as a well organized and documented FORTRAN 77 source code.

1,392 citations

Journal ArticleDOI
TL;DR: The uvspec program, a suite of tools for radiative transfer calculations in the Earth's atmosphere, and additional tools included with libRadtran are described and realistic examples of their use are given.
Abstract: . The libRadtran software package is a suite of tools for radiative transfer calculations in the Earth's atmosphere. Its main tool is the uvspec program. It may be used to compute radiances, irradiances and actinic fluxes in the solar and terrestrial part of the spectrum. The design of uvspec allows simple problems to be easily solved using defaults and included data, hence making it suitable for educational purposes. At the same time the flexibility in how and what input may be specified makes it a powerful and versatile tool for research tasks. The uvspec tool and additional tools included with libRadtran are described and realistic examples of their use are given. The libRadtran software package is available from http://www.libradtran.org.

1,309 citations

Journal ArticleDOI
05 Aug 1999-Nature
TL;DR: It is shown that 2-methylbacteriohopanepolyols occur in a high proportion of cultured cyanob bacteria and cyanobacterial mats and are abundant in organic-rich sediments as old as 2,500 Myr, which may help constrain the age of the oldest cyanobacteria and the advent of oxygenic photosynthesis.
Abstract: Oxygenic photosynthesis is widely accepted as the most important bioenergetic process happening in Earth's surface environment1. It is thought to have evolved within the cyanobacterial lineage, but it has been difficult to determine when it began. Evidence based on the occurrence and appearance of stromatolites2 and microfossils3 indicates that phototrophy occurred as long ago as 3,465 Myr although no definite physiological inferences can be made from these objects. Carbon isotopes and other geological phenomena4,5 provide clues but are also equivocal. Biomarkers are potentially useful because the three domains of extant life—Bacteria, Archaea and Eukarya—have signature membrane lipids with recalcitrant carbon skeletons. These lipids turn into hydrocarbons in sediments and can be found wherever the recordis sufficiently well preserved. Here we show that 2-methylbacteriohopanepolyols occur in a high proportion of cultured cyanobacteria and cyanobacterial mats. Their 2-methylhopane hydrocarbon derivatives are abundant in organic-rich sediments as old as 2,500 Myr. These biomarkers may help constrain the age of the oldest cyanobacteria and the advent of oxygenic photosynthesis. They could also be used to quantify the ecological importance of cyanobacteria through geological time.

924 citations

Journal ArticleDOI
TL;DR: In this paper, the authors proposed a more detailed and reliable spectral information from the UV (280-nm) to the near infrared (4000-nm), which is typical of a cleaner atmosphere where solar applications can be deployed more advantageously.

535 citations

01 Jan 2002
TL;DR: In this paper, the authors provide a primer on radiative transfer: absorption and scattering opacity, Stokes parameters, Poincare sphere, and the Mueller matrix, as well as the principle of reciprocity for the bidirectional reflectance.
Abstract: Preface 1. Basic properties of radiation, atmospheres and oceans 2. Basic state variables 3. Interaction of radiation with matter 4. Formulation of radiative transfer problems 5. Approximate solutions of prototype problems 6. Accurate numerical solutions of prototype problems 7. Emission-dominated radiative processes 8. Radiative transfer in spectrally-complex media 9. Solar radiation driving photochemistry and photobiology 10. The role of radiation in climate Appendix 1. A primer on radiative transfer: absorption and scattering opacity Appendix 2. Stokes parameters, Poincare sphere, and the Mueller matrix Appendix 3. Nomenclature: glossary of symbols Appendix 4. Principle of reciprocity for the bidirectional reflectance Appendix 5. Isolation of the azimuth-dependence Appendix 6. The streaming term in spherical geometry Appendix 7. Reflectance and transmittance of the invariant intensity (I n2) Appendix 8. Scaling transformation for anisotropic scattering Appendix 9. Reciprocity, duality and effects of surface reflection Appendix 10. Removal of overflow problems in the intensity formulas.

515 citations