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Developing a New Machine-Learning Algorithm for Estimating Chlorophyll-a Concentration in Optically Complex Waters: A Case Study for High Northern Latitude Waters by Using Sentinel 3 OLCI
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-09-04)
The monitoring of Chlorophyll-a (Chl-a) concentration in high northern latitude waters has been receiving increased focus due to the rapid environmental changes in the sub-Arctic, Arctic. Spaceborne optical instruments allow the continuous monitoring of the occurrence, distribution, and amount of Chl-a. In recent years, the Ocean and Land Color Instruments (OLCI) onboard the Sentinel 3 (S3) A and B ...
Does your lab use social media? Sharing three years of experience in science communication
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-06-27)
Effective science communication is essential to share knowledge and recruit the next generation of researchers. Science communication to the general public can, however, be hampered by limited resources and a lack of incentives in the academic environment. Various social media platforms have recently emerged, providing free and simple science communication tools to reach the public and young people ...
Shock location and CME 3D reconstruction of a solar type II radio burst with LOFAR
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-07-19)
<p><i>Context - </i>Type II radio bursts are evidence of shocks in the solar atmosphere and inner heliosphere that emit radio waves ranging from sub-meter to kilometer lengths. These shocks may be associated with coronal mass ejections (CMEs) and reach speeds higher than the local magnetosonic speed. Radio imaging of decameter wavelengths (20–90 MHz) is now possible with the Low Frequency Array ...
Isotope effect on filament dynamics in fusion edge plasmas
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-04-20)
The influence of the ion mass on filament propagation in the scrape-off layer of toroidal
magnetised plasmas is analysed for various fusion relevant majority species, like hydrogen
isotopes and helium, on the basis of a computational isothermal gyrofluid model for the plasma
edge. Heavy hydrogen isotope plasmas show slower outward filament propagation and thus
improved confinement properties ...
The long sunspot cycle 23 predicts a significant temperature decrease in cycle 24
(Journal article; Tidsskriftartikkel; Peer reviewed, 2012-02-16)
Relations between the length of a sunspot cycle and the average temperature in the same and the next
cycle are calculated for a number of meteorological stations in Norway and in the North Atlantic region.
No significant trend is found between the length of a cycle and the average temperature in the same
cycle, but a significant negative trend is found between the length of a cycle and the ...
Retrieving horizontally resolved wind fields using multi-static meteor radar observations
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-08-27)
Recently, the MMARIA (Multi-static, Multi-frequency Agile Radar for Investigations of the Atmosphere) concept of a multi-static VHF meteor radar network to derive horizontally resolved wind fields in the mesosphere–lower thermosphere was introduced. Here we present preliminary results of the MMARIA network above Eastern Germany using two transmitters located at Juliusruh and Collm, and five receiving ...
The asymmetric geospace as displayed during the geomagnetic storm on 17 August 2001
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-11-29)
Previous studies have shown that conjugate auroral features are displaced in the two hemispheres when the interplanetary magnetic field (IMF) has a transverse (<i><sub>Y</sub></i>) component. It has also been shown that a <i>B<sub>Y</sub></i> component is induced in the closed magnetosphere due to the asymmetric loading of magnetic flux in the lobes following asymmetric dayside reconnection when the ...
Observing Mesospheric Turbulence With Specular Meteor Radars: A Novel Method for Estimating Second-Order Statistics of Wind Velocity
(Journal article; Peer reviewed, 2019-07)
There are few observational techniques for measuring the distribution of kinetic energy within the mesosphere with a wide range of spatial and temporal scales. <br>This study describes a method for estimating the three‐dimensional mesospheric wind field correlation function from specular meteor trail echoes. Each radar echo provides a measurement of a one‐dimensional projection of the wind velocity ...
Assessment of the RISAT-1 FRS-2 Mode for Oil Spill Observation
(Peer reviewed; Chapter, 2017-12-04)
Synthetic aperture radar data acquired by the Radar Imaging Satellite (RISAT-1) over experimental oil spills is here investigated. One quad-polarization scene in the Fine Resolution Alternate Polarization Stripmap (FRS-2) mode is analyzed to evaluate the potential of using this mode for oil spill observation.<br> Oil slicks of varying type and age are clearly detected in the HH and VV channels, with ...
UAV-BORNE UWB RADAR FOR SNOWPACK SURVEYS
(Research report; Forskningsrapport, 2018)
In this report we summarize the capabilities and technical characteristics of our UAV-borne UWB radar
system, designed for conducting snow surveys. We developed an ultrawideband snow sounder that is
capable of imaging snow stratigraphy with a 5 cm range resolution. The radar can be carried by an octocopter
UAV in order to carry out airborne snowpack surveys.
During a demonstration on Andøya, we ...