Browsing Bergen Open Research Archive by Author "Hamre, Børge"
Now showing items 1-20 of 21
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Absorption properties of high-latitude Norwegian coastal water: The impact of CDOM and particulate matter
Cirennima, X; Frette, Øyvind; Hamre, Børge; Erga, Svein Rune; Chen, Yi-Chun; Zhao, Lu; Sørensen, Kai; Norli, Marit; Stamnes, Knut; Stamnes, Jakob J. (Peer reviewed; Journal article, 2016-09)We present data from measurements and analyses of the spectral absorption due to colored dissolved organic matter (CDOM), total suspended matter (TSM), phytoplankton, and non-algal particles (NAP) in high-latitude northern ... -
Analysis of multiple scattering errors in LISST-VSF volume scattering function measurements using Monte Carlo simulations and experimental data
Ugulen, Håvard Stavn; Sandven, Håkon; Hamre, Børge; Kristoffersen, Arne Skodvin; Sætre, Camilla (Journal article; Peer reviewed, 2021)A Monte Carlo algorithm has been developed to investigate the effects of multiple scattering on the volume scattering function measured by the LISST-VSF instrument. The developed algorithm is compared to experimental results ... -
Blue-blocking glasses as additive treatment for mania: A randomized placebo-controlled trial
Henriksen, Tone Elise Gjøtterud; Skrede, Silje; Fasmer, Ole Bernt; Schøyen, Helle Kristine; Leskauskaite, Ieva; Bjørke-Bertheussen, Janette; Assmus, Jörg; Hamre, Børge; Grønli, Janne; Lund, Anders (Peer reviewed; Journal article, 2016-05)Objectives: The discovery of the blue lightsensitive retinal photoreceptor responsible for signaling daytime to the brain suggested that light to the circadian system could be inhibited by using blue-blocking orange tinted ... -
CDOM absorption properties of natural water bodies along extreme environmental gradients
Nima, Ciren; Frette, Øyvind; Hamre, Børge; Stamnes, Jakob J.; Chen, Yi-Chun; Sørensen, Kai; Norli, Marit; Lu, Daren; Xing, Qianguo; Muyimbwa, Dennis; Ssenyonga, Taddeo; Stamnes, Knut; Erga, Svein Rune (Peer reviewed; Journal article, 2019-09-24)We present absorption properties of colored dissolved organic matter (CDOM) sampled in six different water bodies along extreme altitudinal, latitudinal, and trophic state gradients. Three sites are in Norway: the mesotrophic ... -
Cherenkov luminescence imaging for assessment of radioactive plaque position in brachytherapy of uveal melanoma: An in vivo feasibility study
Krohn, Jørgen Gitlesen; Chen, Yi-Chun; Stabo-Eeg, Nils Ole; Hamre, Børge (Journal article; Peer reviewed, 2020)Purpose: To study the feasibility of using Cherenkov luminescence imaging (CLI) to evaluate and document ruthenium-106 plaque position during brachytherapy of uveal melanoma. Methods: Ruthenium-106 decays by emitting ... -
Chlorophyll a fluorescence lifetime reveals reversible UV-induced photosynthetic activity in the green algae Tetraselmis
Kristoffersen, Arne Skodvin; Hamre, Børge; Frette, Øyvind; Erga, Svein Rune (Peer reviewed; Journal article, 2015)The fluorescence lifetime is a very useful parameter for investigating biological materials on the molecular level as it is mostly independent of the fluorophore concentration. The green alga Tetraselmis blooms in summer, ... -
Effects of an Arctic under-ice bloom on solar radiant heating of the water column
Taskjelle, Torbjørn; Granskog, Mats A.; Pavlov, Alexey K.; Hudson, Stephen R.; Hamre, Børge (Peer reviewed; Journal article, 2017-01)The deposition of solar energy in the upper Arctic Ocean depends, among other things, on the composition of the water column. During the N-ICE2015 expedition, a drift in the Arctic pack ice north of Svalbard, an under-ice ... -
Efficient Monte Carlo simulation reveals significant multiple scattering errors in underwater angular scattering measurements
Ugulen, Håvard Stavn; Sandven, Håkon; Hamre, Børge; Kristoffersen, Arne Skodvin; Sætre, Camilla (Journal article; Peer reviewed, 2022)Multiple scattering can severely affect the accuracy of optical instrumentation. Variance reduction methods have been implemented to improve a Monte Carlo model developed to simulate volume scattering functions measured ... -
In situ measurements of the volume scattering function with LISST-VSF and LISST-200X in extreme environments: evaluation of instrument calibration and validity
Sandven, Håkon; Kristoffersen, Arne Skodvin; Hamre, Børge; Chen, Yi-Chun (Journal article; Peer reviewed, 2020)The LISST-VSF and LISST-200X are commercial instruments made available in recent years, enabling underwater measurements of the volume scattering function, which has not been routinely measured in situ due to lack of ... -
Inherent optical properties of dissolved and particulate matter in an Arctic fjord (Storfjorden, Svalbard) in early summer
Petit, Tristan; Hamre, Børge; Sandven, Håkon Johan; Röttgers, Rüdiger; Kowalczuk, Piotr; Zablocka, Monika; Granskog, Mats A. (Journal article; Peer reviewed, 2022)Lysforholdene i havet spiller en nøkkelrolle for marin primærproduksjon og dermed for det hele marine økosystemet. I polområdene er det spesielt stor sesongvariasjon i lysforholdene, og mange ulike prosesser kan påvirke ... -
Laser light propagation in a turbid medium: solution including multiple scattering effects
Stamnes, Knut; Li, Wei; Stamnes, Snorre; Hu, Yong; Zhou, Yingzhen; Chen, Nan; Fan, Yongzhen; Hamre, Børge; Lu, Xiaomei; Huang, Yuping; Weimer, Carl; Lee, Jennifer; Zeng, Xubin; Stamnes, Jakob J. (Journal article; Peer reviewed, 2023)We have shown that solutions to the radiative transfer equation for a homogeneous slab yield a zenith radiance reflectance that for collimated beam incidence in the nadir direction can be expressed in terms of the lidar ... -
A method to derive satellite PAR albedo time series over first-year sea ice in the Arctic Ocean
Laliberté, Julien; Rehm, Eric; Hamre, Børge; Goyens, Clémence; Perovich, Donald K.; Babin, Marcel (Journal article; Peer reviewed, 2022)Deriving sea ice albedo from spaceborne platforms is of interest to model the propagation of the photosynthetically available radiation (PAR) through Arctic sea ice. We show here that use of the Moderate Resolution Imaging ... -
Neural network approach for correction of multiple scattering errors in the LISST-VSF instrument
Ugulen, Håvard Stavn; Koestner, Daniel Warren; Sandven, Håkon Johan; Hamre, Børge; Kristoffersen, Arne Skodvin; Sætre, Camilla (Journal article; Peer reviewed, 2023)The LISST-VSF is a commercially developed instrument used to measure the volume scattering function (VSF) and attenuation coefficient in natural waters, which are important for remote sensing, environmental monitoring and ... -
A new algorithm for simultaneous retrieval of aerosol and marine parameters in coastal environments
Stamnes, Knut; Li, Wei; Fan, Y.; Hamre, Børge; Frette, Øyvind; Folkestad, Are; Sørensen, Kai; Stamnes, Jakob J. (Peer reviewed; Journal article, 2013)We present simultaneous retrievals of aerosol and marine parameters in coastal areas from ocean color data using the OC-SMART algorithm, Ocean Color: Simultaneous Marine and Aerosol Retrieval Tool. OC-SMART uses a one-step ... -
A new algorithm for simultaneous retrieval of aerosols and marine parameters
Ssenyonga, Taddeo; Frette, Øyvind; Hamre, Børge; Stamnes, Knut; Muyimbwa, Dennis; Ssebiyonga, Nicolausi; Stamnes, Jakob J. (Journal article; Peer reviewed, 2022)We present an algorithm for simultaneous retrieval of aerosol and marine parameters in coastal waters. The algorithm is based on a radiative transfer forward model for a coupled atmosphere-ocean system, which is used to ... -
Pixelwise immersion factor calibration for underwater hyperspectral imaging instruments
Liu, Hongbo; Summers, Natalie Maria; Chen, Yi-Chun; Løvås, Håvard Snefjellå; Johnsen, Geir; Koestner, Daniel Warren; Sætre, Camilla; Hamre, Børge (Journal article; Peer reviewed, 2024)In situ spectral reflectance initially captured at high spatial resolution with underwater hyperspectral imaging (UHI) is effective for classification and quantification in oceanic biogeochemical studies; however, the ... -
Pollen-chemistry variations along elevation gradients and their implications for a proxy for UV-B radiation in the plant-fossil record
Seddon, Alistair William Robin; Festi, Daniela; Nieuwkerk, Mayke; Gya, Ragnhild; Hamre, Børge; Krüger, Linn Cecilie; Hjortland Östman, Silje Andrea; Robson, T. Matthew (Journal article; Peer reviewed, 2021)Research indicates that phenolic compounds (e.g. para-coumaric acid) found within pollen grains may be useful as a proxy to reconstruct the UV-B radiation received at the Earth's surface in the geological past. However, ... -
Seasonality and drivers of water column optical properties on the northwestern Barents Sea shelf
Sandven, Håkon; Hamre, Børge; Petit, Tristan; Röttgers, Rudiger; Liu, Hongbo; Granskog, Mats (Journal article; Peer reviewed, 2023)Hydrographic and bio-optical measurements were conducted along a south–north transect on the northwestern Barents Sea shelf from early spring to late summer in 2021. Strong climate change manifestations observed in this ... -
Spectral albedo and transmittance of thin young Arctic sea ice
Taskjelle, Torbjørn; Hudson, Stephen R.; Granskog, Mats A.; Nicolaus, Marcel; Lei, Ruibo; Gerland, Sebastian; Stamnes, Jakob J.; Hamre, Børge (Peer reviewed; Journal article, 2016-01)Spectral albedo and transmittance in the range 400–900nm were measured on three separate dates on less than 15 cm thick new Arctic sea ice growing on Kongsfjorden, Svalbard at 78:9°N, 11:9°E. Inherent optical properties, ... -
Testing Fluorescence Lifetime Standards using Two-Photon Excitation and Time-Domain Instrumentation: Fluorescein, Quinine Sulfate and Green Fluorescent Protein
Kristoffersen, Arne Skodvin; Hamre, Børge; Erga, Svein Rune; Frette, Øyvind (Peer reviewed; Journal article, 2018-09)It is essential for everyone working with experimental science to be certain that their instruments produce reliable results, and for fluorescence lifetime experiments, information about fluorescence lifetime standards is ...