Browsing NTNU Open by Author "Espy, Patrick Joseph"
Now showing items 21-40 of 65
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Electrojet Estimates From Mesospheric Magnetic Field Measurements
Laundal, Karl Magnus; Yee, J.H.; Merkin, V.G.; Gjerløv, Jesper; Vanhamäki, H.; Reistad, Jone Peter; Madelaire, Michael; Sorathia, K.; Espy, Patrick Joseph (Peer reviewed; Journal article, 2021)The auroral electrojet is traditionally measured remotely with magnetometers on ground or in low Earth orbit (LEO). The sparse distribution of measurements, combined with a vertical distance of some 100 km to ground and ... -
Electromagnetic Principles for In Situ Ice Thickness Determination - Field Experiments and Development of New Methods for Interpretation
Lorentzen, Johannes P (Master thesis, 2015)During the spring of 2014 fieldwork in three different locations on Svalbard was conducted in order to investigate the application of electromagnetic methods on sea ice and ice ridges. Two validation grids, one transect ... -
Gravity Wave Refraction in the Atmosphere:: Ray tracing versus Geometric Location from a Single Image
Nærø, Karoline (Master thesis, 2013)This thesis presents two methods of finding the sources of gravity waves observed in the night-time hydroxyl airglow; ray-tracing and geometric localisation by fitting concentric circles onto the curvature of the gravity ... -
Hydroxyl airglow observations for investigating atmospheric dynamics: Results and challenges
Wüst, Sabine; Bittner, Michael; Espy, Patrick Joseph; French, W. John R.; Mulligan, Frank J. (Peer reviewed; Journal article, 2023)Measurements of hydroxyl (OH*) airglow intensity are a straightforward and cost-efficient method which allows the derivation of information about the climate and dynamics of the upper mesosphere/lower thermosphere (UMLT) ... -
Ice ridge keel size distributions: Analysis of ice ridge keel thickness from Upward Looking Sonar data from the Fram Strait using extreme value theory.
Kvadsheim, Synnøve (Master thesis, 2014)The present thesis explored sea ice ridges in the Fram Strait from data collected at 79 degrees N, 65 degrees W in 2006/2007 by an Upward Looking Sonar instrument, IPS4, and used extreme value analysis to provide an estimate ... -
Målinger i troposfæren med ALOMAR RMR lidar: Temperaturmålinger med bruk av rotasjons Raman spektrum og bestemmelse av dens optiske overlap.
Heimly, Simen (Master thesis, 2019)Alomar troposfæriske lidar var ikke operativ grunnet en feil med laseren og trengte en erstatter. Den fikk en ny laser under skrivingen av denne oppgaven. I denne oppgaven ble det prøvd en midlertidig løsning hvor RMR-lidaren ... -
Mesoscale gravity wave activity in the Mesosphere over Northern-Norway
Tjelle, Erlend Magnus (Master thesis, 2014)The purpose of this study is to examine wind data retrieved from the SKiYMET-radarsat Trondheim and Andenes during the time period of the 27th of November to the 02ndof December 2012. These dates surrounds the night between ... -
Mesospheric CO above Troll station, Antarctica observed by a ground based microwave radiometer
Straub, Corinne; Espy, Patrick Joseph; Hibbins, Robert; Newnham, David (Journal article; Peer reviewed, 2013)This paper presents mesospheric carbon monoxide (CO) data acquired by the ground-based microwave radiometer of the British Antarctic Survey (BAS radiometer) stationed at Troll station in Antarctica (72° S, 2.5° E, 1270 m ... -
Mesospheric nitric oxide model from SCIAMACHY data
Bender, Stefan; Sinnhuber, M; Espy, Patrick Joseph; Burrows, John P. (Journal article; Peer reviewed, 2019)We present an empirical model for nitric oxide (NO) in the mesosphere (60–90 km) derived from SCIAMACHY limb scan data. Our model relates the daily (longitudinally) averaged NO number densities from SCIAMACHY as a function ... -
Meteor Radar Observations of the Atmospheric Tides
Skarvang, Kristina Shizuka Yamase (Master thesis, 2020)Denne oppgaven undersøker muligheten for interhemisfærisk kobling av atmosfæriske bølger under "Sudden stratospheric warming" (SSW) hendelser. Meteor-radar lokalisert ved Rothera (68S, 68W) på Antarktishalvøya har blitt ... -
Migrating tide climatologies measured by a high-latitude array of SuperDARN HF radars
van Caspel, Willem Elias; Espy, Patrick Joseph; Hibbins, Robert; McCormack, John (Peer reviewed; Journal article, 2020)This study uses hourly meteor wind measurements from a longitudinal array of 10 high-latitude SuperDARN high-frequency (HF) radars to isolate the migrating diurnal, semidiurnal, and terdiurnal tides at mesosphere–lower-t ... -
Modelled effects of temperature gradients and waves on the hydroxyl rotational distribution in ground-based airglow measurements
Franzen, Christoph; Espy, Patrick Joseph; Hibbins, Robert (Journal article; Peer reviewed, 2020)Spectroscopy of the hydroxyl (OH) airglow has been a commonly used way to remotely sense temperatures in the mesopause region for many decades. This technique relies on the OH rotational state populations to be thermalized ... -
Modelling the descent of nitric oxide during the elevated stratopause event of January 2013
Orsolini, Yvan; Limpasuvan, Varavut; Pérot, Kristell; Espy, Patrick Joseph; Hibbins, Robert; Lossow, Stefan; Raaholt Larsson, Katarina; Murtagh, Donal (Journal article; Peer reviewed, 2017)Using simulations with a whole-atmosphere chemistry-climate model nudged by meteorological analyses, global satellite observations of nitrogen oxide (NO) and water vapour by the Sub-Millimetre Radiometer instrument (SMR), ... -
Multi-Instrument Investigation of Spectral Width in the Polar Ionosphere
Luque, Lidia (Master thesis, 2020)Spektralbredden er en av parameterne målt av Super Dual Auroral Radar Network (SuperDARN) radarer. På tross av at de er mye brukt i litteraturen, er det foreløpig ikke enighet om årsaken til spektralbreddevariasjonene sett ... -
Observation of Quasiperiodic Structures in the Hydroxyl Airglow on Scales Below 100 m
Franzen, Christoph; Espy, Patrick Joseph; Hibbins, Robert; Djupvik, Anlaug Amanda (Journal article; Peer reviewed, 2018)Gravity waves are known to transport energy and momentum to the middle atmosphere. The breaking processes associated with divergence of fluxes of energy and momentum into the atmosphere occur on scales that cannot be ... -
Observational evidence of the influence of Antarctic stratospheric ozone variability on middle atmosphere dynamics
Narukull, Venkateswara Rao; Espy, Patrick Joseph; Hibbins, Robert; Fritts, David C.; Kavanagh, Andrew J. (Journal article; Peer reviewed, 2015)Modeling results have suggested that the circulation of the stratosphere and mesosphere in spring is strongly affected by the perturbations in heating induced by the Antarctic ozone hole. Here using both mesospheric MF ... -
Observations of gravity wave forcing of the mesopause region during the January 2013 major Sudden Stratospheric Warming
De Wit, Rosmarie Johanna; Hibbins, Robert; Espy, Patrick Joseph; Orsolini, Yvan; Limpasuvan, Varavut; Kinnison, Douglas E. (Journal article; Peer reviewed, 2014)Studies of vertical and interhemispheric coupling during Sudden Stratospheric Warmings (SSWs) suggest that gravity wave (GW) momentum flux divergence plays a key role in forcing the middle atmosphere, although observational ... -
Observations of nitric oxide in the Antarctic middle atmosphere during recurrent geomagnetic storms
Newnham, David A.; Espy, Patrick Joseph; Clilverd, Mark A.; Rodger, Craig J.; Seppälä, Annika; Maxfield, David J.; Hartogh, Paul; Straub, Corinne; Holmén, Kim; Horne, Richard B. (Journal article; Peer reviewed, 2013)We report ground-based measurements of the polar middle atmosphere made using a 230–250 GHz passive microwave radiometer deployed at Troll station (72°01′S 02°32′E, L shell of L = 4.8), Antarctica. Our observations show ... -
Observations of planetary waves in the mesosphere-lower thermosphere during stratospheric warming events
Stray, Nora Henriette; Orsolini, Yvan; Espy, Patrick Joseph; Limpasuvan, Varavut; Hibbins, Robert (Journal article; Peer reviewed, 2015-05-04)This study investigates the effect of stratospheric sudden warmings (SSWs) on planetary wave (PW) activity in the mesosphere–lower thermosphere (MLT). PW activity near 95 km is derived from meteor wind data using a chain ... -
On-board, Fourier-Based Image-Analysis System for Satellite Observation of Gravity Waves
Hatlen, Morten (Master thesis, 2013)The main objective of this thesis is obtaining data on gravity waves from images taken by the NTNU Test Satellite (NUTS). The satellite's main payload consists of a camera intended to capture images of gravity waves in the ...