Terje Fredvik

• Zhu, Y.; Harra, L.; Barczynski, K.; Janitzek, N.; Plowman, J. & Mzerguat, S. [Show all 16 contributors for this article] (2025). Active region upflows in various coronal structures and their coupling to the lower atmosphere. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 701. doi: 10.1051/0004-6361/202555618. Full text in Research Archive Show summary

  Context. Plasma upflows with a Doppler shift exceeding −10 km s −1 at active region (AR) boundaries are considered potential sources of the nascent slow solar wind. These upflows are often located at the footpoints of large-scale fan-like loops and show temperature-dependent Doppler shifts with redshifts in the transition region and blueshifts in the lower corona. Aims. We investigate the driving mechanisms of a pair of coronal upflow regions on the western and eastern peripheries of an AR, which have different magnetic topologies and surroundings. It is aimed to explore how these upflows couple to the lower atmosphere. Methods. Using observations of the Fe  XII 19.51 nm line from Hinode, we identified two upflow regions at the western and eastern boundaries of a decaying AR. Context images for the two regions were obtained by the High Resolution Imager (HRI) telescope of the Extreme Ultraviolet Imager (EUI) on board the Solar Orbiter mission. Other instruments on Solar Orbiter and other observatories provide diagnostics to the lower atmosphere. Potential Field Source Surface (PFSS) extrapolations were used to examine the magnetic field configuration associated with the AR upflows. Results. The eastern upflow region, located over the AR moss, displays small-scale dynamic fibril structures, whereas the western region hosts fan-like loops. We found blueshifted Ne  VIII emission at the eastern site, in contrast to redshifted Ne  VIII profiles in the west. Magnetic field extrapolations reveal a pseudostreamer topology connecting both these regions. Moreover, low transition-region lines show systematically reduced redshift below the eastern footpoint. Conclusions. The observations support the scenario in which both upflows are driven by pressure imbalances created by coronal reconnection, leading to a continuous upflow above approximately 0.6 MK (i.e., Ne  VIII line formation temperature). Meanwhile, mass flows in the lower transition region beneath the eastern upflow region appear to respond passively to the pressure-driven coronal upflows.

• Varesano, T.; Hassler, D.M.; Prado, N. Zambrana; Plowman, J.; Zanna, G. Del & Parenti, S. [Show all 31 contributors for this article] (2024). SPICE connection mosaics to link the Sun's surface and the heliosphere. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 685. doi: 10.1051/0004-6361/202347637. Full text in Research Archive Show summary

  Aims. We present an analysis of the first connection mosaic made by the SPICE instrument on board the ESA/NASA Solar Orbiter mission on March 2, 2022. The data will be used to map coronal composition that will be compared with in-situ measurements taken by SWA/HIS to establish the coronal origin of the solar wind plasma observed at Solar Orbiter. The SPICE spectral lines were chosen to have varying sensitivity to the first ionization potential (FIP) effect, and therefore the radiances of the spectral lines will vary significantly depending on whether the elemental composition is coronal or photospheric. We investigate the link between the behavior of sulfur and the hypothesis that Alfvén waves drive FIP fractionation above the chromosphere. Methods. We performed temperature diagnostics using line ratios and emission measure (EM) loci, and computed relative FIP biases using three different approaches (two-line ratio (2LR), ratios of linear combinations of spectral lines (LCR), and differential emission measure (DEM) inversion) in order to perform composition diagnostics in the corona. We then compared the SPICE composition analysis and EUI data of the potential solar wind source regions to the SWA/HIS data products. Results. Radiance maps were extracted from SPICE spectral data cubes, with values matching previous observations. We find isothermal plasma of around log T = 5.8 for the AR loops targeted, and that higher FIP-bias values are present at the footpoints of the coronal loops associated with two ARs. Comparing the results with the SWA/HIS data products encourages us to think that Solar Orbiter was connected to a source of slow solar wind during this observation campaign. We demonstrate FIP fractionation in observations of the upper chromosphere and transition region, emphasized by the behavior of the intermediate-FIP element sulfur.

• Huang, Ziwen; Teriaca, L.; Cuadrado, R. Aznar; Chitta, L.P.; Mandal, S. & Peter, H. [Show all 19 contributors for this article] (2023). Imaging and spectroscopic observations of extreme-ultraviolet brightenings using EUI and SPICE on board Solar Orbiter. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 673. doi: 10.1051/0004-6361/202345988. Full text in Research Archive Show summary

  Context. The smallest extreme-ultraviolet (EUV) brightening events that were detected so far, called campfires, have recently been uncovered by the High Resolution EUV telescope (HRI EUV ), which is part of the Extreme Ultraviolet Imager (EUI) on board Solar Orbiter. HRI EUV has a broad bandpass centered at 17.4 nm that is dominated by Fe  IX and Fe  X emission at about 1 MK. Aims. We study the thermal properties of EUI brightening events by simultaneously observing their responses at different wavelengths using spectral data from the Spectral Imaging of the Coronal Environment (SPICE) also on board Solar Orbiter and imaging data from EUI. Methods. We studied three EUI brightenings that were identified in HRI EUV data that lie within the small areas covered by the slit of the SPICE EUV spectrometer. We obtained the line intensities of the spectral profiles by Gaussian fitting. These diagnostics were used to study the evolution of the EUI brightenings over time at the different line-formation temperatures. Results. We find that (i) the detection of these EUI brightenings is at the limit of the SPICE capabilities. They could not have been independently identified in the data without the aid of HRI EUV observations. (ii) Two of these EUI brightenings with longer lifetimes are observed up to Ne  VIII temperatures (0.6 MK). (iii) All of the events are detectable in O  VI (0.3 MK), and the two longer-lived events are also detected in other transition region (TR) lines. (iv) In one case, we observe two peaks in the intensity light curve of the TR lines that are separated by 2.7 min for C  III and 1.2 min for O  VI . The Ne  VIII intensity shows a single peak between the two peak times of the TR line intensity. Conclusions. Spectral data from SPICE allow us to follow the thermal properties of EUI brightenings. Our results indicate that at least some EUI brightenings barely reach coronal temperatures.

• Janvier, M.; Mzerguat, S.; Young, P.R.; Buchlin, E.; Manou, A. & Pelouze, G. [Show all 59 contributors for this article] (2023). A multiple spacecraft detection of the 2 April 2022 M-class flare and filament eruption during the first close Solar Orbiter perihelion. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 677. doi: 10.1051/0004-6361/202346321. Full text in Research Archive Show summary

  Context. The Solar Orbiter mission completed its first remote-sensing observation windows in the spring of 2022. On 2 April 2022, an M-class flare followed by a filament eruption was seen both by the instruments on board the mission and from several observatories in Earth’s orbit, providing an unprecedented view of a flaring region with a large range of observations. Aims. We aim to understand the nature of the flaring and filament eruption events via the analysis of the available dataset. The complexity of the observed features is compared with the predictions given by the standard flare model in 3D. Methods. In this paper, we use the observations from a multi-view dataset, which includes extreme ultraviolet (EUV) imaging to spectroscopy and magnetic field measurements. These data come from the Interface Region Imaging Spectrograph, the Solar Dynamics Observatory, Hinode, as well as several instruments on Solar Orbiter. Results. The large temporal coverage of the region allows us to analyse the whole sequence of the filament eruption starting with its pre-eruptive state. Information given by spectropolarimetry from SDO/HMI and Solar Orbiter PHI/HRT shows that a parasitic polarity emerging underneath the filament is responsible for bringing the flux rope to an unstable state. As the flux rope erupts, Hinode EIS captures blue-shifted emission in the transition region and coronal lines in the northern leg of the flux rope prior to the flare peak. This may be revealing the unwinding of one of the flux rope legs. At the same time, Solar Orbiter SPICE captures the whole region, complementing the Doppler diagnostics of the filament eruption. Analyses of the formation and evolution of a complex set of flare ribbons and loops, of the hard and soft X-ray emissions with STIX, show that the parasitic emerging bipole plays an important role in the evolution of the flaring region. Conclusions. The extensive dataset covering this M-class flare event demonstrates how important multiple viewpoints and varied observations are in order to understand the complexity of flaring regions. While the analysed data are overall consistent with the standard flare model, the present particular magnetic configuration shows that surrounding magnetic activity such as nearby emergence needs to be taken into account to fully understand the processes at work. This filament eruption is the first to be covered from different angles by spectroscopic instruments, and provides an unprecedented diagnostic of the multi-thermal structures present before and during the flare. This complete dataset of an eruptive event showcases the capabilities of coordinated observations with the Solar Orbiter mission.

• Yardley, Stephanie L.; Owen, Christopher J.; Long, David M.; Baker, Deborah; Brooks, David H. & Polito, Vanessa [Show all 79 contributors for this article] (2023). Slow Solar Wind Connection Science during Solar Orbiter’s First Close Perihelion Passage. Astrophysical Journal Supplement Series. ISSN 0067-0049. 267(1). doi: 10.3847/1538-4365/acd24b. Full text in Research Archive Show summary

  Abstract The Slow Solar Wind Connection Solar Orbiter Observing Plan (Slow Wind SOOP) was developed to utilize the extensive suite of remote-sensing and in situ instruments on board the ESA/NASA Solar Orbiter mission to answer significant outstanding questions regarding the origin and formation of the slow solar wind. The Slow Wind SOOP was designed to link remote-sensing and in situ measurements of slow wind originating at open–closed magnetic field boundaries. The SOOP ran just prior to Solar Orbiter’s first close perihelion passage during two remote-sensing windows (RSW1 and RSW2) between 2022 March 3–6 and 2022 March 17–22, while Solar Orbiter was at respective heliocentric distances of 0.55–0.51 and 0.38–0.34 au from the Sun. Coordinated observation campaigns were also conducted by Hinode and IRIS. The magnetic connectivity tool was used, along with low-latency in situ data and full-disk remote-sensing observations, to guide the target pointing of Solar Orbiter. Solar Orbiter targeted an active region complex during RSW1, the boundary of a coronal hole, and the periphery of a decayed active region during RSW2. Postobservation analysis using the magnetic connectivity tool, along with in situ measurements from MAG and SWA/PAS, showed that slow solar wind originating from two out of three of the target regions arrived at the spacecraft with velocities between ∼210 and 600 km s −1 . The Slow Wind SOOP, despite presenting many challenges, was very successful, providing a blueprint for planning future observation campaigns that rely on the magnetic connectivity of Solar Orbiter.

• Brooks, David H.; Janvier, Miho; Baker, Deborah; Warren, Harry P.; Auchère, Frédéric & Carlsson, Mats [Show all 31 contributors for this article] (2022). Plasma Composition Measurements in an Active Region from Solar Orbiter/SPICE and Hinode/EIS. The Astrophysical Journal (ApJ). ISSN 0004-637X. 940(1). doi: 10.3847/1538-4357/ac9b0b. Full text in Research Archive
• Löfdahl, Mats G.; Hillberg, Tomas; Rodriguez, Jaime de la Cruz; Vissers, Gregal Joan Maria; Andriienko, Oleksii & Scharmer, Göran B. [Show all 8 contributors for this article] (2021). SSTRED: Data- and metadata-processing pipeline for CHROMIS and CRISP. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 653. doi: 10.1051/0004-6361/202141326. Full text in Research Archive Show summary

  Context. Data from ground-based, high-resolution solar telescopes can only be used for science with calibrations and processing, which requires detailed knowledge about the instrumentation. Space-based solar telescopes provide science-ready data, which are easier to work with for researchers whose expertise is in the interpretation of data. Recently, data-processing pipelines for ground-based instruments have been constructed. Aims. We aim to provide observers with a user-friendly data pipeline for data from the Swedish 1-meter Solar Telescope (SST) that delivers science-ready data together with the metadata needed for proper interpretation and archiving. Methods. We briefly describe the CHROMospheric Imaging Spectrometer (CHROMIS) instrument, including its (pre)filters, as well as recent upgrades to the CRisp Imaging SpectroPolarimeter (CRISP) prefilters and polarization optics. We summarize the processing steps from raw data to science-ready data cubes in FITS files. We report calibrations and compensations for data imperfections in detail. Misalignment of Ca  II data due to wavelength-dependent dispersion is identified, characterized, and compensated for. We describe intensity calibrations that remove or reduce the effects of filter transmission profiles as well as solar elevation changes. We present REDUX, a new version of the MOMFBD image restoration code, with multiple enhancements and new features. It uses projective transforms for the registration of multiple detectors. We describe how image restoration is used with CRISP and CHROMIS data. The science-ready output is delivered in FITS files, with metadata compliant with the SOLARNET recommendations. Data cube coordinates are specified within the World Coordinate System (WCS). Cavity errors are specified as distortions of the WCS wavelength coordinate with an extension of existing WCS notation. We establish notation for specifying the reference system for Stokes vectors with reference to WCS coordinate directions. The CRIsp SPectral EXplorer (CRISPEX) data-cube browser has been extended to accept SSTRED output and to take advantage of the SOLARNET metadata. Results. SSTRED is a mature data-processing pipeline for imaging instruments, developed and used for the SST/CHROMIS imaging spectrometer and the SST/CRISP spectropolarimeter. SSTRED delivers well-characterized, science-ready, archival-quality FITS files with well-defined metadata. The SSTRED code, as well as REDUX and CRISPEX, is freely available through git repositories.

• Fludra, Andrzej; Caldwell, M.; Giunta, A.; Grundy, T.; Guest, S. & Leeks, S. [Show all 31 contributors for this article] (2021). First observations from the SPICE EUV spectrometer on Solar Orbiter. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 656. doi: 10.1051/0004-6361/202141221. Full text in Research Archive Show summary

  Aims. We present first science observations taken during the commissioning activities of the Spectral Imaging of the Coronal Environment (SPICE) instrument on the ESA/NASA Solar Orbiter mission. SPICE is a high-resolution imaging spectrometer operating at extreme ultraviolet (EUV) wavelengths. In this paper we illustrate the possible types of observations to give prospective users a better understanding of the science capabilities of SPICE. Methods. We have reviewed the data obtained by SPICE between April and June 2020 and selected representative results obtained with different slits and a range of exposure times between 5 s and 180 s. Standard instrumental corrections have been applied to the raw data. Results. The paper discusses the first observations of the Sun on different targets and presents an example of the full spectra from the quiet Sun, identifying over 40 spectral lines from neutral hydrogen and ions of carbon, oxygen, nitrogen, neon, sulphur, magnesium, and iron. These lines cover the temperature range between 20 000 K and 1 million K (10 MK in flares), providing slices of the Sun’s atmosphere in narrow temperature intervals. We provide a list of count rates for the 23 brightest spectral lines. We show examples of raster images of the quiet Sun in several strong transition region lines, where we have found unusually bright, compact structures in the quiet Sun network, with extreme intensities up to 25 times greater than the average intensity across the image. The lifetimes of these structures can exceed 2.5 hours. We identify them as a transition region signature of coronal bright points and compare their areas and intensity enhancements. We also show the first above-limb measurements with SPICE above the polar limb in C III, O VI, and Ne VIII lines, and far off limb measurements in the equatorial plane in Mg IX, Ne VIII, and O VI lines. We discuss the potential to use abundance diagnostics methods to study the variability of the elemental composition that can be compared with in situ measurements to help confirm the magnetic connection between the spacecraft location and the Sun’s surface, and locate the sources of the solar wind. Conclusions. The SPICE instrument successfully performs measurements of EUV spectra and raster images that will make vital contributions to the scientific success of the Solar Orbiter mission.

• Anderson, Mark; Appourchaux, T.; Auchère, Frédéric; Cuadrado, R. Aznar; Barbay, J. & Baudin, F. [Show all 89 contributors for this article] (2020). The Solar Orbiter SPICE instrument: An extreme UV imaging spectrometer. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 642. doi: 10.1051/0004-6361/201935574. Full text in Research Archive Show summary

  Aims. The Spectral Imaging of the Coronal Environment (SPICE) instrument is a high-resolution imaging spectrometer operating at extreme ultraviolet wavelengths. In this paper, we present the concept, design, and pre-launch performance of this facility instrument on the ESA/NASA Solar Orbiter mission. Methods. The goal of this paper is to give prospective users a better understanding of the possible types of observations, the data acquisition, and the sources that contribute to the instrument’s signal. Results. The paper discusses the science objectives, with a focus on the SPICE-specific aspects, before presenting the instrument’s design, including optical, mechanical, thermal, and electronics aspects. This is followed by a characterisation and calibration of the instrument’s performance. The paper concludes with descriptions of the operations concept and data processing. Conclusions. The performance measurements of the various instrument parameters meet the requirements derived from the mission’s science objectives. The SPICE instrument is ready to perform measurements that will provide vital contributions to the scientific success of the Solar Orbiter mission.

• Brescia, Massimo; Cavuoti, Stefano; Fredvik, Terje; Haugan, Stein Vidar Hagfors; Gozaliasl, Ghassem & Kirkpatrick, Charles [Show all 10 contributors for this article] (2019). The Design Strategy of Scientific Data Quality Control Software for Euclid Mission. Astronomical Society of the Pacific Conference Series. ISSN 1050-3390. 521, p. 228–231. Full text in Research Archive
• Kamio, S.; Hara, H; Watanabe, T; Fredvik, Terje & Hansteen, Viggo (2010). Modeling of EIS Spectrum Drift from Instrumental Temperatures. Solar Physics. ISSN 0038-0938. 266(1), p. 209–223. doi: 10.1007/s11207-010-9603-7. Full text in Research Archive
• Brynildsen, Nils; Maltby, Per; Foley, CR; Fredvik, Terje & Kjeldseth-Moe, Olav (2004). Oscillations in the umbral atmosphere. Solar Physics. ISSN 0038-0938. 221(2), p. 237–260. Full text in Research Archive
• Brynildsen, Nils; Maltby, Per; Brekke, P.; Fredvik, Terje & Kjeldseth-Moe, Olav (2003). Search for a chromospheric resonator above sunspots. Advances in Space Research. ISSN 0273-1177. 32(6), p. 1097–1102. Full text in Research Archive
• Brynildsen, Nils; Maltby, Per; Fredvik, Terje & Kjeldseth-Moe, Olav (2002). Oscillations above sunspots. Solar Physics. ISSN 0038-0938. 207, p. 259–290. Full text in Research Archive
• Fredvik, Terje; Kjeldseth-Moe, Olav; Haugan, Stein Vidar Hagfors; Brekke, Pål; Gurman, Joe B. & Wilhelm, K (2002). Variability and dynamic state of active region loops. Advances in Space Research. ISSN 0273-1177. 30(3), p. 635–640. Full text in Research Archive
• Brynildsen, Nils; Maltby, Per; Fredvik, Terje; Kjeldseth-Moe, Olav & Wilhelm, K. (2001). Sunspot plumes and flow channels. Solar Physics. ISSN 0038-0938. 198, p. 89–131. Full text in Research Archive
• Maltby, Per; Brynildsen, Nils; Fredvik, Terje; Kjeldseth-Moe, Olav & Wilhelm, K. (2000). On the sunspot transition region. Solar Physics. ISSN 0038-0938. 190(December 1999), p. 429–450. Full text in Research Archive
• Fredvik, Terje & Maltby, Per (1999). Coronal radiation and helium _l l584 emission in active regions. Solar Physics. ISSN 0038-0938. 184, p. 113–132. Full text in Research Archive

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• Fredvik, Terje (2026). Oslo SPICE Status 2026. Full text in Research Archive
• Fredvik, Terje & Enebakk, Vidar (2022). Abels bakgård - Lyden av sorte hull og jordas FIRE poler. [Radio]. Abels tårn - NRK Radio. Full text in Research Archive
• Fredvik, Terje; Melteig, Elina & Brekke, Pål (2022). Vil varsle romvær som kan slå ut strømnett og kommunikasjon. [Radio]. Universitetsplassen - en podcast fra UiO. Full text in Research Archive
• Fredvik, Terje (2022). Solar Orbiter - et skråblikk på Sola fra nært hold. Full text in Research Archive
• Fredvik, Terje (2022). Solar Orbiter - et skråblikk på Sola fra nært hold. Full text in Research Archive
• Fredvik, Terje (2022). Oslo SPICE Status. Full text in Research Archive
• Fredvik, Terje (2020). Oslo SPICE Status. Full text in Research Archive
• Fredvik, Terje (2020). Oslo SPICE Status. Full text in Research Archive
• Fredvik, Terje (2019). Oslo SPICE Status. Full text in Research Archive
• Fredvik, Terje (2019). Oslo SPICE Status. Full text in Research Archive
• Fredvik, Terje (2019). Quicklook and Analysis Tools. Full text in Research Archive
• Fredvik, Terje (2018). SPICE FITS 101. Full text in Research Archive
• Fredvik, Terje (2018). Oslo SPICE Status. Full text in Research Archive
• Fredvik, Terje (2018). SPICE Data Pipeline and Data Products. Full text in Research Archive
• Fredvik, Terje (2018). SPICE FITS Hardcore. Full text in Research Archive
• Fredvik, Terje (2010). Det er ikke Nibiru alt som glimrer (med sitt fravær). www.skepsis.no. Full text in Research Archive
• Fredvik, Terje (2005). Plasma Condensation in Coronal Loops - Observations with CDS/SOHO and TRACE. Full text in Research Archive
• Fredvik, Terje (2005). Active Region Loop Studies in Oslo. Full text in Research Archive Show summary

  In Oslo we have used CDS together with SUMER and TRACE to study active region loops at the solar limb. Systematic observations with CDS started in 1997 and early results immediately demonstrated that the emission from the plasma in the loops is highly time variable at transition region temperatures. A surprise was the first detection of large line of sight velocities, +/- 50 km/s, present in the loop plasma. To investigate the rapidly changing loops an emphasis has been on developing increasingly faster raster studies, from a cadence of 52 minutes for the first raster observations down to 2 minutes for the most recent and fastest raster. When observed at very high cadence, the plasma radiation in most loop structures appears as quasiperiodic intensity enhancements moving rapidly along the loops down to the surface of the sun. In order to understand highly variable loop systems, we need observations with high temporal, spatial and spectral resolution, and this may be obtained by combining observations from several instruments. The loop observations have therefore been part of Joint Observing Programs, involving instruments such as TRACE, SUMER, EIT and MDI. We will present the different CDS observing programs we have run, show several examples of observations from both CDS and other co-observing instruments and present some of our results.

• Brynildsen, Nils; Maltby, Per; Fredvik, Terje & Kjeldseth-Moe, Olav (2004). Oscillations above the umbra of sunspots. Full text in Research Archive
• Fredvik, Terje & Kjeldseth-Moe, Olav (2004). Multi Wavelength Observations of Solar Active Region Loops. Full text in Research Archive
• Fredvik, Terje (2004). Observational Evidence for Plasma Condensation in Coronal Loops. Full text in Research Archive
• Fredvik, Terje & Kjeldseth-Moe, Olav (2003). The Upper Temperature Limit for Rapid Intensity Variations in the Solar Transition Region. Full text in Research Archive
• Brekke, P.; Brynildsen, Nils; Maltby, Per; Fredvik, Terje & Kjeldseth-Moe, Olav (2003). Sunspot Oscillations and Acoustic Wave Propagation. Full text in Research Archive
• Brynildsen, Nils; Maltby, Per; Fredvik, Terje & Kjeldseth-Moe, Olav (2002). Sunspot oscillations in the chromosphere, transition region, and corona. Full text in Research Archive
• Hansteen, Viggo; Wikstøl, Øivind; Brynildsen, Nils; Maltby, Per; Fredvik, Terje & Kjeldseth-Moe, Olav (2002). On the nature of the 3 minute oscillations above sunspots. Full text in Research Archive
• Fredvik, Terje; Kjeldseth-Moe, Olav & Curdt, Werner (2002). An upper temperature limit for strong dynamic activity in the solar transition region. Full text in Research Archive
• Brynildsen, Nils; Maltby, Per; Fredvik, Terje & Kjeldseth-Moe, Olav (2002). 3 minute oscillations above sunspots. Full text in Research Archive
• Brekke, P.; Brynildsen, Nils; Maltby, Per; Fredvik, Terje & Kjeldseth-Moe, Olav (2002). The 6mHz oscillations above sunspots. Full text in Research Archive
• Brynildsen, Nils; Maltby, Per; Fredvik, Terje & Kjeldseth-Moe, Olav (2002). Sunspot oscillations from the chromosphere to the corona. Full text in Research Archive
• Fredvik, Terje & Kjeldseth-Moe, Olav (2002). The transition from strong to weak dynamic activity with increasing temperature in solar AR loops. Full text in Research Archive
• Fredvik, Terje; Kjeldseth-Moe, Olav & Wikstøl, Øivind (2001). Temperature structure and dynamic velocities in active region loop structures. Full text in Research Archive
• Haugan, S. V. H.; Brekke, P.; Fredvik, Terje; Kjeldseth-Moe, Olav; Wilhelm, K. & Gurman, Joe B. (2000). Observed variability and dynamics of active region loops. Full text in Research Archive
• Fredvik, Terje & Kjeldseth-Moe, Olav (2000). The continuous transience and dynamic state of active region loops. Full text in Research Archive
• Kjeldseth-Moe, Olav & Fredvik, Terje (2000). The time variable solar atmosphere. Full text in Research Archive
• Brekke, P.; Kjeldseth-Moe, Olav; Fredvik, Terje; Haugan, S. V. H.; Tarbell, T.D. & Gurman, Joe B. (1999). A transition region eruption observed with CDS, TRACE and EIT. Full text in Research Archive
• Brynildsen, Nils; Fredvik, Terje; Kjeldseth-Moe, Olav & Maltby, Per (1999). Transition region oscillations in a sunspot region. Full text in Research Archive
• Fredvik, Terje; Kjeldseth-Moe, Olav; Brekke, P. & Haugan, S. V. H. (1999). Time variation of active region loops observed with CDS on SOHO. Full text in Research Archive

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