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Found 54 entries in the Bibliography.
Showing entries from 1 through 50
| 2020 |
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An outstanding issue in the general circulation model simulations for Earth\textquoterights upper atmosphere is the inaccurate estimation of Joule heating, which could be associated with the inaccuracy of empirical models for high-latitude electrodynamic forcing. The binning methods used to develop those empirical models may contribute to the inaccuracy. Traditionally, data are binned through a static binning approach by using fixed geomagnetic coordinates, in which the dynamic nature of the forcing is not considered and therefore the forcing patterns may be significantly smeared. To avoid the smoothing issue, data can be binned according to some physically important boundaries in the high-latitude forcing, that is, through a boundary-oriented binning approach. In this study, we have investigated the sensitivity of high-latitude forcing patterns to the binning methods by applying both static and boundary-oriented binning approaches to the electron precipitation and electric potential data from the Defense Meteorological Satellite Program satellites. For this initial study, we have focused on the moderately strong and dominantly southward interplanetary magnetic field conditions. As compared with the static binning results, the boundary-oriented binning approach can provide a more confined and intense electron precipitation pattern. In addition, the magnitudes of the electric potential and electric field in the boundary-oriented binning results increase near the convection reversal boundary, leading to a ~11\% enhancement of the cross polar cap potential. The forcing patterns obtained from both binning approaches are used to drive the Global Ionosphere and Thermosphere Model to assess the impacts on Joule heating by using different binning patterns. It is found that the hemispheric-integrated Joule heating in the simulation driven by the boundary-oriented binning patterns is 18\% higher than that driven by the static binning patterns. Zhu, Qingyu; Deng, Yue; Richmond, Arthur; Maute, Astrid; Chen, Yun-Ju; Hairston, Marc; Kilcommons, Liam; Knipp, Delores; Redmon, Robert; Mitchell, Elizabeth; Published by: Journal of Geophysical Research: Space Physics Published on: 01/2020 YEAR: 2020 DOI: 10.1029/2019JA027270 Electric field; high latitude; Joule heating; particle precipitation |
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Global-scale observations and modeling of far-ultraviolet airglow during twilight The NASA Global‐scale Observations of the Limb and Disk ultraviolet imaging spectrograph performs observations of upper atmosphere airglow from the sunlit disk and limb of the Earth Solomon, Stanley; Andersson, Laila; Burns, Alan; Eastes, Richard; Martinis, Carlos; McClintock, William; Richmond, Arthur; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2020 DOI: 10.1029/2019JA027645 |
| 2018 |
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We present the results of complex obser-vationsof various parameters of the middle and upper atmosphere over Siberia in December 2012 \textendashJanuary 2013, during a major sudden stratospheric warming (SSW) event. We analyze variations in ozone concentra-tion from microwave measurements, in stratosphere and lower mesosphere temperatures from lidar and satellite measurements, in the F2-layer critical frequency (foF2), in the total electron content (TEC), as well as in the ra-tio of concentrations of atomic oxygen to molecular nitrogen (O/N2) in the thermosphere.To interpret the observed disturbances in the upper atmosphere, the ex-perimental measurements are compared with the results of model calculations obtained with the Global Self-Consistent Model of Thermosphere\textemdashIonosphere\textemdashProtonosphere (GSM TIP). The response of the upper atmosphere to the SSW event is shown to be a decreasein foF2 and TEC during the evolution of the warming event and a prolonged increase in O/N2, foF2, and TEC after the SSW maximum. For the first time, we observe the relation between the increase in stratospheric ozone, thermospheric O/N2, and ionospheric electron densityfor a fairly long time (up to 20 days) after the SSW maximum at midlatitudes. Ясюкевич, Анна; Yasyukevich, Anna; Клименко, Максим; Klimenko, Maksim; Куликов, Юрий; Kulikov, Yury; Клименко, Владимир; Klimenko, Vladimir; Бессараб, Федор; Bessarab, Fedor; Кореньков, Юрий; Korenkov, Yuriy; Маричев, Валерий; Marichev, Valery; Ратовский, Константин; Ratovsky, Konstantin; Колесник, Сергей; Kolesnik, Sergey; Published by: Solnechno-Zemnaya Fizika Published on: 08/2018 YEAR: 2018 DOI: 10.12737/issue_5c1b83b913d443.7589563310.12737/szf-44201807 |
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This paper investigates and quantifies the longitudinal, solar cyclical, and diurnal variation of the ionosphere peak electron density observed by six ionosondes located between 18 and 151\textdegreeE near 60\textdegreeN. Embedded within this region is the Bering Sea anomaly (BSA) where the midnight peak electron density exceeds the midday peak electron density in summer. The BSA is a region West of Alaska extending from approximately 100\textdegree to 200\textdegree east geographic longitude and 55\textdegree to 70\textdegree north geographic latitude at its widest. By comparing a physical model with ionosonde data from the 1970s and 1980s, it is found that longitudinal changes in the neutral winds and neutral densities are the most likely explanation for the electron density variation between 18 and 151\textdegreeE near 60\textdegreeN. Longitudinal differences in magnetic declination and inclination are small and have a negligible effect on the electron density behavior. Our definition of and the behavior of the BSA are analogous to the Weddell Sea anomaly (WSA), a region in the Southern Hemisphere where the midnight peak electron density also exceeds the midday peak electron density in summer. Although the overall BSA electron density is a factor of 2 smaller than that in the WSA, the two anomalies have similar midnight to midday electron density ratios. It is found that the BSA gets stronger with increasing solar activity, while the WSA gets weaker. It is also demonstrated that including vibrationally excited N2 in an ionosphere model is crucial for producing the observed midnight to midday electron density ratios. Richards, P.; Meier, R.; Chen, Shihping; Dandenault, P.; Published by: Journal of Geophysical Research: Space Physics Published on: 08/2018 YEAR: 2018 DOI: 10.1029/2018JA025413 |
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Key developments have been made to the NCAR Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension (WACCM-X). Among them, the most important are the self-consistent solution of global electrodynamics, and transport of O+ in the F-region. Other ionosphere developments include time-dependent solution of electron/ion temperatures, metastable O+ chemistry, and high-cadence solar EUV capability. Additional developments of the thermospheric components are improvements to the momentum and energy equation solvers to account for variable mean molecular mass and specific heat, a new divergence damping scheme, and cooling by O(3P) fine structure. Simulations using this new version of WACCM-X (2.0) have been carried out for solar maximum and minimum conditions. Thermospheric composition, density, and temperatures are in general agreement with measurements and empirical models, including the equatorial mass density anomaly and the midnight density maximum. The amplitudes and seasonal variations of atmospheric tides in the mesosphere and lower thermosphere are in good agreement with observations. Although global mean thermospheric densities are comparable with observations of the annual variation, they lack a clear semiannual variation. In the ionosphere, the low-latitude E \texttimes B drifts agree well with observations in their magnitudes, local time dependence, seasonal, and solar activity variations. The prereversal enhancement in the equatorial region, which is associated with ionospheric irregularities, displays patterns of longitudinal and seasonal variation that are similar to observations. Ionospheric density from the model simulations reproduces the equatorial ionosphere anomaly structures and is in general agreement with observations. The model simulations also capture important ionospheric features during storms. Liu, Han-Li; Bardeen, Charles; Foster, Benjamin; Lauritzen, Peter; Liu, Jing; Lu, Gang; Marsh, Daniel; Maute, Astrid; McInerney, Joseph; Pedatella, Nicholas; Qian, Liying; Richmond, Arthur; Roble, Raymond; Solomon, Stanley; Vitt, Francis; Wang, Wenbin; Published by: Journal of Advances in Modeling Earth Systems Published on: 01/2018 YEAR: 2018 DOI: 10.1002/jame.v10.210.1002/2017MS001232 |
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Changes in the Stratosphere and Ionosphere Parameters During the 2013 Major Stratospheric Warming The paper presents the results of the complex experiment (lidar and ozonometric observations), carried out during the period of the 2013 major sudden stratospheric warming (SSW) in the North Asia region. The data of this experiment were supplemented by the ionospheric parameters observations. We considered variations in the critical frequency and peak height of the ionospheric F2-layer (foF2) from ionosonde measurements in Tomsk and Irkutsk, as well as the behavior of the total electron content (TEC) based on the phase dual-frequency GPS/GLONASS receivers\textquoteright data. We revealed significant variations in the stratosphere ozone concentration, ionospheric electron density, as well as in the thermosphere O/N 2 ratio with the similar pattern during the SSW. The ionospheric response to SSW in the middle and high-latitude regions is suggested to be caused by changes in the neutral composition at the thermosphere altitudes. Yasyukevich, Anna; Kulikov, Yury; Klimenko, Maxim; Klimenko, Vladimir; Bessarab, Fedor; Korenkov, Yury; Marichev, Valery; Ratovsky, Konstantin; Kolesnik, Sergey; Published by: Published on: YEAR: 2018 DOI: 10.23919/URSI-AT-RASC.2018.8471322 |
| 2017 |
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The Global-Scale Observations of the Limb and Disk (GOLD) Mission The Earth\textquoterights thermosphere and ionosphere constitute a dynamic system that varies daily in response to energy inputs from above and from below. This system can exhibit a significant response within an hour to changes in those inputs, as plasma and fluid processes compete to control its temperature, composition, and structure. Within this system, short wavelength solar radiation and charged particles from the magnetosphere deposit energy, and waves propagating from the lower atmosphere dissipate. Understanding the global-scale response of the thermosphere-ionosphere (T-I) system to these drivers is essential to advancing our physical understanding of coupling between the space environment and the Earth\textquoterights atmosphere. Previous missions have successfully determined how the \textquotedblleftclimate\textquotedblright of the T-I system responds. The Global-scale Observations of the Limb and Disk (GOLD) mission will determine how the \textquotedblleftweather\textquotedblright of the T-I responds, taking the next step in understanding the coupling between the space environment and the Earth\textquoterights atmosphere. Operating in geostationary orbit, the GOLD imaging spectrograph will measure the Earth\textquoterights emissions from 132 to 162 nm. These measurements will be used image two critical variables\textemdashthermospheric temperature and composition, near 160 km\textemdashon the dayside disk at half-hour time scales. At night they will be used to image the evolution of the low latitude ionosphere in the same regions that were observed earlier during the day. Due to the geostationary orbit being used the mission observes the same hemisphere repeatedly, allowing the unambiguous separation of spatial and temporal variability over the Americas. Eastes, R.; McClintock, W.; Burns, A.; Anderson, D.; Andersson, L.; Codrescu, M.; Correira, J.; Daniell, R.; England, S.; Evans, J.; Harvey, J.; Krywonos, A.; Lumpe, J.; Richmond, A.; Rusch, D.; Siegmund, O.; Solomon, S.; Strickland, D.; Woods, T.; Aksnes, A.; Budzien, S.; Dymond, K.; Eparvier, F.; Martinis, C.; Oberheide, J.; Published by: Space Science Reviews Published on: 10/2017 YEAR: 2017 DOI: 10.1007/s11214-017-0392-2 |
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This paper investigates and quantifies the causes of the Weddell Sea Anomaly (WSA), a region near the tip of South America extending from approximately 30\textdegree to 120\textdegreeW geographic longitude and 50\textdegree to 75\textdegreeS geographic latitude at solar minimum between 2007 and 2010. This region is unusual because the midnight peak electron density exceeds the midday peak electron density in summer. This study is far more quantitative than previous studies because, unlike other models, it assimilates selected data parameters to constrain a physical model in order to investigate other aspects of the data. It is shown that the commonly accepted explanation that the WSA is related to the magnetic field declination and inclination effects on the neutral wind does not explain the longitudinal variation of the electron density. Rather, longitudinal changes in the neutral winds and neutral densities are the most likely explanation for the WSA. These longitudinal wind and density changes are attributed to the varying latitudinal distance from the auroral zone energy input. No contributions from the plasmasphere or other sources are required. Furthermore, it is shown that a widely used empirical thermosphere density model overestimates the longitudinal changes in the WSA region. Richards, P.; Meier, R.; Chen, Shih-Ping; Drob, D.; Dandenault, P.; Published by: Journal of Geophysical Research: Space Physics Published on: 05/2017 YEAR: 2017 DOI: 10.1002/2016JA023565 |
| 2016 |
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High-latitude energy input and its impact on the thermosphere This paper presents a quantitative assessment of high-latitude energy input and its partitioning in the polar cap by synthesizing various space and ground-based observations during the 17 January 2005 geomagnetic storm. It was found that Joule heating is the primary form of magnetospheric energy input, especially during active times when the hemispheric-integrated Joule heating can be an order of magnitude larger than the hemispheric-integrated auroral power. Most of magnetospheric energy is dissipated in the auroral zone rather than in the polar cap. On average, only about 22\textendash25\% of the total hemispheric energy input is dissipated into the polar cap region bordered by the convection reversal boundary (CRB) and the poleward auroral flux boundary (FXB). The impact of high-latitude energy input was also investigated to unveil the causal relationship between Joule heating and the formation of polar cap mass density anomalies. Our numerical simulation demonstrated that thermosphere dynamics readily redistributes composition, temperature, and mass through upwelling and atmospheric gravity waves. The polar cap mass density anomalies observed by the CHAMP satellite during the storm were largely a result of large-scale atmospheric gravity waves. Therefore, an increase in local thermospheric mass density does not necessarily mean there is direct energy input. Lu, G.; Richmond, A.; Lühr, H.; Paxton, L.; Published by: Journal of Geophysical Research: Space Physics Published on: 07/2016 YEAR: 2016 DOI: 10.1002/2015JA022294 |
| 2015 |
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We analyze how the evening equatorial plasma vortex and the prereversal enhancement (PRE) of the vertical drift are influenced by the distributions of conductivity in the E and F regions in relation to the wind, through numerical simulations with the thermosphere-ionosphere-electrodynamics general circulation model coupled with the global ionosphere-plasmasphere model. The nightside electric potential satisfies an approximate minimization principle that unifies the connection of the horizontal and vertical components of plasma convection to the wind and conductivity distributions. The relative roles of E and F region conductivities on the convection and current closure are clarified. Evening time F region zonal winds at latitudes that encompass the equatorial ionization anomaly (EIA) region provide the main energy source to drive the convection, including the PRE. The E region helps regulate both the meridional and the zonal convection through drag on the meridional convection associated with Cowling current. For large nighttime E region conductivities, additional drag on the zonal convection comes from the Pedersen conductance. The minimization principle favors meridional plasma inflow to the EIA region from lower rather than higher magnetic apex heights, so long as the E region Cowling conductance is not too large. This upward/poleward inflow maximizes on field lines that traverse the lower F layer near the equatorward edge of the EIA region, producing a PRE with maximum vertical velocity within the equatorial F layer. Published by: Journal of Geophysical Research: Space Physics Published on: 03/2015 YEAR: 2015 DOI: 10.1002/2014JA020935 equatorial ionosphere convection; night-time ionization; pre-reversal enhancement |
| 2014 |
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This paper investigates unusually deep and sudden electron density depletions (troughs) observed in the Poker Flat (Alaska) Incoherent Scatter Radar data in middle summer of 2007 and 2008. The troughs were observed in the premidnight sector during periods of weak magnetic and solar activity. The density recovered to normal levels around midnight. At the time when the electron density was undergoing its steep decrease, there was usually a surge of the order of 100 to 400 K in the ion temperature that lasted less than 1 h. The Ti surges were usually related to similar surges in the AE index, indicating that the high-latitude convection pattern was expanding and intensifying at the time of the steep electron density drop. The convection patterns from the Super Dual Auroral Radar Network also indicate that the density troughs were associated with the expansion of the convection pattern to Poker Flat. The sudden decreases in the electron density are difficult to explain in summer because the high-latitude region remains sunlit for most of the day. This paper suggests that the summer density troughs result from lower latitude plasma that had initially been corotating in darkness for several hours post sunset and brought back toward the sunlit side as the convection pattern expanded. The magnetic declination of ~22\textdegree east at 300 km at Poker Flat greatly facilitates the contrast between the plasma convecting from lower latitudes and the plasma that follows the high-latitude convection pattern. Richards, P.; Nicolls, M.; St.-Maurice, J.-P.; Goodwin, L.; Ruohoniemi, J.; Published by: Journal of Geophysical Research: Space Physics Published on: 12/2014 YEAR: 2014 DOI: 10.1002/jgra.v119.1210.1002/2014JA020541 |
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Solar and Heliospheric Physics General Contributions II Posters Richardson, Ian; Millan, Robyn; Paxton, Larry; Zhao, Lingling; Published by: Published on: |
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Magnetospheric Physics General Contributributions Posters Millan, Robyn; Paxton, Larry; Richardson, Ian; Published by: Published on: |
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The NCAR TIE-GCM: A community model of the coupled thermosphere/ionosphere system Qian, Liying; Burns, Alan; Emery, Barbara; Foster, Benjamin; Lu, Gang; Maute, Astrid; Richmond, Arthur; Roble, Raymond; Solomon, Stanley; Wang, Wenbin; Published by: Modeling the Ionosphere-Thermosphere System Published on: |
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The International Reference Ionosphere 2012--a model of international collaboration Bilitza, Dieter; Altadill, David; Zhang, Yongliang; Mertens, Chris; Truhlik, Vladimir; Richards, Phil; McKinnell, Lee-Anne; Reinisch, Bodo; Published by: Journal of Space Weather and Space Climate Published on: |
| 2012 |
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Marsal, S.; Richmond, A.; Maute, A.; Anderson, B.; Published by: Journal of Geophysical Research Published on: Jan-01-2012 YEAR: 2012 DOI: 10.1029/2011JA017416 |
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This paper presents our effort to assimilate FORMOSAT-3/COSMIC (F3/C) GPS Occultation Experiment (GOX) observations into the National Center for Atmospheric Research (NCAR) Thermosphere Ionosphere Electrodynamics General Circulation Model (TIE-GCM) by means of ensemble Kalman filtering (EnKF). The F3/C electron density profiles (EDPs) uniformly distributed around the globe which provide an excellent opportunity to monitor the ionospheric electron density structure. The NCAR TIE-GCM simulates the Earth\textquoterights thermosphere and ionosphere by using self-consistent solutions for the coupled nonlinear equations of hydrodynamics, neutral and ion chemistry, and electrodynamics. The F3/C EDP are combined with the TIE-GCM simulations by EnKF algorithms implemented in the NCAR Data Assimilation Research Testbed (DART) open-source community facility to compute the expected value of electron density, which is \textquoteleftthe best\textquoteright estimate of the current ionospheric state. Assimilation analyses obtained with real F3/C electron density profiles are compared with independent ground-based observations as well as the F3/C profiles themselves. The comparison shows the improvement of the primary ionospheric parameters, such as NmF2 and hmF2. Nevertheless, some unrealistic signatures appearing in the results and high rejection rates of observations due to the applied outlier threshold and quality control are found in the assimilation experiments. This paper further discusses the limitations of the model and the impact of ensemble member creation approaches on the assimilation results, and proposes possible methods to avoid these problems for future work. Lee, I.; Matsuo, T.; Richmond, A.; Liu, J; Wang, W.; Lin, C.; Anderson, J.; Chen, M.; Published by: Journal of Geophysical Research Published on: 10/2012 YEAR: 2012 DOI: 10.1029/2012JA017700 data assimilation; ensemble Kalman filter; FORMOSAT-3/COSMIC; Ionosphere |
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Emery, B; Roble, Raymond; Ridley, Cicely; Richmond, Arthur; Knipp, Delores; Crowley, Geoff; Evans, David; Rich, Frederick; Maeda, Sawako; Published by: NCAR Tech. Note NCAR/TN-491+ STR Published on: |
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Emery, B; Roble, Raymond; Ridley, Cicely; Richmond, Arthur; Knipp, Delores; Crowley, Geoff; Evans, David; Rich, Frederick; Maeda, Sawako; Published by: NCAR Tech. Note NCAR/TN-491+ STR Published on: |
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Reversed two-cell convection in the northern and southern hemisphere during northward IMF Lu, G; Li, W; Raeder, J; Deng, Y; Rich, F; Ober, D; Zhang, Y; Paxton, L; Ruohoniemi, M; Hairston, M; , others; Published by: Published on: |
| 2011 |
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Lu, G.; Li, W.; Raeder, J.; Deng, Y.; Rich, F.; Ober, D.; Zhang, Y.; Paxton, L.; Ruohoniemi, J.; Hairston, M.; Newell, P.; Published by: Journal of Geophysical Research Published on: Jan-01-2011 YEAR: 2011 DOI: 10.1029/2011JA017043 |
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Modeling Density Variation in the Thermosphere when this function is imposed at the lower boundary of the TIEGCM, neutral density variation consistent with satellite drag data, and O/N2 consistent with measurements by TIMED/GUVI Published by: Published on: |
| 2010 |
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Electric fields and large-scale undulations in the evening sector of the diffuse auroral zone Baishev, D.; Barkova, E.; Stepanov, A.; Rich, F.; Yumoto, K.; Published by: Geomagnetism and Aeronomy Published on: Jan-02-2010 YEAR: 2010 DOI: 10.1134/S0016793210010056 |
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Richards, P.; Meier, R.; Wilkinson, P.; Published by: Journal of Geophysical Research Published on: Jan-01-2010 YEAR: 2010 DOI: 10.1029/2010JA015368 |
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Huang, Chao-Song; Rich, Frederick; de La Beaujardiere, Odile; Heelis, Roderick; Published by: Journal of Geophysical Research Published on: Jan-01-2010 YEAR: 2010 DOI: 10.1029/2009JA014503 |
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Talaat, Elsayed; Fuller-Rowell, Tim; Qian, Liying; Richards, Phil; Ridley, Aaron; Burns, Alan; Bernstein, Dennis; Chamberlin, Phillip; Fedrizzi, Mariangel; Hsieh, Syau-Yun; , others; Published by: 38th COSPAR Scientific Assembly Published on: |
| 2009 |
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Solar wind structure sources and periodicities of auroral electron power over three solar cycles We assess the contributions of various types of solar wind structures (transients, coronal hole high-speed streams (HSS), and slow-speed wind) to hourly average auroral electron power (Pe). The time variation of the solar wind velocity (Vsw) and Pe are determined by HSS, which contribute ∼47\% to Pe and Vsw. Transients contribute ∼42\% of Pe in solar maxima, and ∼6\% in solar minimum. Cross-correlations of Pe with Vsw|B| for negative Bz are significant. Pe exhibits solar rotational periodicities similar to those for Vsw, with strong 7- and 9-day periodicities in 2005–2008 and equinox semiannual periodicities in 1995–1999. Emery, Barbara; Richardson, Ian; Evans, David; Rich, Frederick; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: YEAR: 2009 DOI: https://doi.org/10.1016/j.jastp.2008.08.005 Electron auroral energy fluxes; Solar wind speed structures; Solar cycle variations; Periodicities |
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Solar wind structure sources and periodicities of auroral electron power over three solar cycles We assess the contributions of various types of solar wind structures (transients, coronal hole high-speed streams (HSS), and slow-speed wind) to hourly average auroral electron power (Pe). The time variation of the solar wind velocity (Vsw) and Pe are determined by HSS, which contribute ∼47\% to Pe and Vsw. Transients contribute ∼42\% of Pe in solar maxima, and ∼6\% in solar minimum. Cross-correlations of Pe with Vsw|B| for negative Bz are significant. Pe exhibits solar rotational periodicities similar to those for Vsw, with strong 7- and 9-day periodicities in 2005–2008 and equinox semiannual periodicities in 1995–1999. Emery, Barbara; Richardson, Ian; Evans, David; Rich, Frederick; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: YEAR: 2009 DOI: https://doi.org/10.1016/j.jastp.2008.08.005 Electron auroral energy fluxes; Solar wind speed structures; Solar cycle variations; Periodicities |
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Richards, PG; Nicolls, MJ; Heinselman, CJ; Sojka, JJ; Holt, JM; Meier, RR; Published by: Journal of Geophysical Research: Space Physics Published on: |
| 2008 |
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Photoelectron flux variations observed from the FAST satellite This paper examines high resolution (ΔE/E\ =\ 0.15) photoelectron energy spectra from 10\ eV to 1\ keV, created by solar irradiances between 1.2 and 120\ nm. The observations were made from the FAST satellite at \~3000\ km, equatorward of the auroral oval for the July\textendashAugust, 2002 solar rotation. These data are compared with the solar irradiance observed by the Solar EUV Experiment (SEE) on the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite and fluxes calculated using the Field Line Interhemispheric Plasma (FLIP) code. The 41\ eV photoelectron flux, which corresponds to solar EUV fluxes near 20\ nm, shows a clear solar rotation variation in very good agreement with the EUV flux measurements. This offers the possibility that the 41\ eV photoelectron flux could be used as a check on measured solar EUV fluxes near 20\ nm. Because of unexpected noise, the solar rotation signal is not evident in the integral photoelectron flux between 156 and 1000\ eV corresponding to EUV wavelengths between 0.1 and 7\ nm measured by the SEE instrument. Examination of daily averaged photoelectron fluxes at energies between 25 and 500\ eV show significant changes in the photoelectron spectra in response X and M class flares. The intensity of photoelectrons produced in this energy region is primarily due to two very narrow EUV wavelength regions at 2.3 and 3\ nm driving Auger photoionization in O at 500\ eV and N2\ at \~360\ eV. Comparison of calculated and daily averaged electron fluxes shows that the HEUVAC model solar spectrum used in the FLIP code does not reproduce the observed variations in photoelectron intensity. In principle, the 21 discrete photoelectron energy channels could be used to improve the reliability of the solar EUV fluxes at 2.3 and 3\ nm inferred from broad band observations. In practice, orbital biases in the way the data were accumulated and/or noise signals arising from natural and anthropogenic longitudinally restricted sources of ionization complicate the application of this technique. Peterson, W.K.; Woods, T.N.; Chamberlin, P.C.; Richards, P.G.; Published by: Advances in Space Research Published on: Jan-09-2008 YEAR: 2008 DOI: 10.1016/j.asr.2007.08.038 |
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XUV Photometer System (XPS): Improved Solar Irradiance Algorithm Using CHIANTI Spectral Models Woods, Thomas; Chamberlin, Phillip; Peterson, W.; Meier, R.; Richards, Phil; Strickland, Douglas; Lu, Gang; Qian, Liying; Solomon, Stanley; Iijima, B.; Mannucci, A.; Tsurutani, B.; Published by: Solar Physics Published on: Jan-08-2008 YEAR: 2008 DOI: 10.1007/s11207-008-9196-6 |
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Eriksson, S.; Hairston, M.; Rich, F.; Korth, H.; Zhang, Y.; Anderson, B.; Published by: Journal of Geophysical Research Published on: Jan-01-2008 YEAR: 2008 DOI: 10.1029/2008JA013139 |
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The PECOS mission of small space weather satellites in the post DMSP era de La Beaujardiere, O; Hanscom, AFB; Rich, FJ; Cooke, DA; Mozer, J; Ober, D; Huang, C; Gentile, LC; Published by: Published on: |
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Hecht, JH; Mulligan, T; Strickland, DJ; Kochenash, AJ; Murayama, Y; Tanaka, Y-M; Evans, DS; Conde, MG; Donovan, EF; Rich, FJ; , others; Published by: Journal of Geophysical Research: Space Physics Published on: |
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Effects of high-latitude ionospheric electric field variability on the Joule heating and mechanical energy transfer rate are investigated by incorporating realistic spatial and temporal characteristics of electric field variability derived from observations into the forcing of a thermosphere ionosphere electrodynamic general circulation model. First, the characteristics of subgrid-scale variability are examined from a spectral analysis of Dynamic Explorer-2 (DE-2) plasma drift measurements. The analysis reveals that the subgrid-scale electric field varies with magnetic latitude, magnetic local time, interplanetary magnetic field (IMF), and season in a manner distinct from that of the resolved-scale electric field and of the climatological electric field. The subgrid-scale electric field varies strongly with season, and its magnitude averaged over the polar region does not depend on IMF. On the other hand, the resolved-scale electric field depends less on season but more on IMF. Second, the spatial-temporal structure of resolved-scale electric fields are characterized from various electromagnetic observations taken during the storm period of January 10–11, 1997, using a space-time covariance model derived from the DE-2 observations. Finally, the modeling results show that the amount of Joule heating and mechanical energy transfer rate in the thermosphere is significantly altered by taking into account the electric field variability and its space-time structure. Additional electromagnetic energy due to the electric field variability dissipates in the ionosphere almost exclusively as Joule heating if the variability has no spatial and temporal correlation. However, the spatially and temporally correlated electric field variability has seasonally dependent effects on the mechanical energy transfer rate. Matsuo, Tomoko; Richmond, Arthur; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2008 DOI: https://doi.org/10.1029/2007JA012993 Joule heating rate; mechanical energy transfer rate; electric field variability |
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Effects of high-latitude ionospheric electric field variability on the Joule heating and mechanical energy transfer rate are investigated by incorporating realistic spatial and temporal characteristics of electric field variability derived from observations into the forcing of a thermosphere ionosphere electrodynamic general circulation model. First, the characteristics of subgrid-scale variability are examined from a spectral analysis of Dynamic Explorer-2 (DE-2) plasma drift measurements. The analysis reveals that the subgrid-scale electric field varies with magnetic latitude, magnetic local time, interplanetary magnetic field (IMF), and season in a manner distinct from that of the resolved-scale electric field and of the climatological electric field. The subgrid-scale electric field varies strongly with season, and its magnitude averaged over the polar region does not depend on IMF. On the other hand, the resolved-scale electric field depends less on season but more on IMF. Second, the spatial-temporal structure of resolved-scale electric fields are characterized from various electromagnetic observations taken during the storm period of January 10–11, 1997, using a space-time covariance model derived from the DE-2 observations. Finally, the modeling results show that the amount of Joule heating and mechanical energy transfer rate in the thermosphere is significantly altered by taking into account the electric field variability and its space-time structure. Additional electromagnetic energy due to the electric field variability dissipates in the ionosphere almost exclusively as Joule heating if the variability has no spatial and temporal correlation. However, the spatially and temporally correlated electric field variability has seasonally dependent effects on the mechanical energy transfer rate. Matsuo, Tomoko; Richmond, Arthur; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2008 DOI: https://doi.org/10.1029/2007JA012993 Joule heating rate; mechanical energy transfer rate; electric field variability |
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The linkage between the ring current and the ionosphere system The coupling between the ring current and the ionosphere is briefly reviewed and discussed. Given global energetic neutral atom (ENA) observations of the ring current, the three-dimensional current system driven by ring current plasma pressure (the region 2 system) is derived to illustrate where the ring current connects to the ionosphere. Special attention is given to how the ring current and ionospheric conductance set up the sub-auroral polarization streams (SAPS) through the closure of the region 2 current through the ionospheric trough region. Brandt, PC; Zheng, Y; Sotirelis, TS; Oksavik, K; Rich, FJ; Published by: Midlatitude ionospheric dynamics and disturbances, edited by: Kintner, PM, Coster, AJ, Fuller-Rowell, T., Mannucci, A. J., Mendillo, M., and Heelis, R., Geophys. Monog. Series Published on: |
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High Latitude Thermosphere-Ionosphere Variability During the Solar Minimum IPY Period Crowley, G; Curtis, N; Richmond, A; Carlson, H; van Eyken, T; Published by: Published on: |
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A data-model comparative study of ionospheric positive storm phase in the midlatitude F region Lu, G; Goncharenko, LP; Coster, AJ; Richmond, AD; Roble, RG; Aponte, N; Paxton, LJ; Published by: Published on: |
| 2007 |
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Storm-time ionospheric disturbance electric fields are studied for two large geomagnetic storms, March 31, 2001 and April 17–18, 2002, by comparing low-latitude observations of ionospheric plasma drifts with results from numerical simulations based on a combination of first-principles models. The simulation machinery combines the Rice convection model (RCM), used to calculate inner magnetospheric electric fields, and the coupled thermosphere ionosphere plasmasphere electrodynamics (CTIPe) model, driven, in part, by RCM-computed electric fields. Comparison of model results with measured or estimated low-latitude vertical drift velocities (zonal electric fields) shows that the coupled model is capable of reproducing measurements under a variety of conditions. In particular, our model results suggest, from theoretical grounds, a possibility of long-lasting penetration of magnetospheric electric fields to low latitudes during prolonged periods of enhanced convection associated with southward-directed interplanetary magnetic field, although the model probably overestimates the magnitude and duration of such penetration during extremely disturbed conditions. During periods of moderate disturbance, we found surprisingly good overall agreement between model predictions and data, with penetration electric fields accounting for early main phase changes and oscillations in low-latitude vertical drift, while the disturbance dynamo mechanism becomes increasingly important later in the modeled events. Discrepancies between the model results and the observations indicate some of the difficulties in validating these combined numerical models, and the limitations of the available experimental data. Maruyama, Naomi; Sazykin, Stanislav; Spiro, Robert; Anderson, David; Anghel, Adela; Wolf, Richard; Toffoletto, Frank; Fuller-Rowell, Timothy; Codrescu, Mihail; Richmond, Arthur; Millward, George; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: YEAR: 2007 DOI: https://doi.org/10.1016/j.jastp.2006.08.020 Magnetosphere–ionosphere–thermosphere coupling; Ionospheric electrodynamics; low-latitude ionosphere; Penetration electric fields; disturbance dynamo electric fields; Numerical modeling |
| 2006 |
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Basu, S; Basu, S; Makela, J; Miller, E; Dasgupta, A; Roy, S; Huba, J; Groves, K; Rich, F; Published by: Eos Trans. AGU Published on: |
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Basu, S; Makela, J; Miller, E; Dasgupta, AK; Ray, S; Groves, K; Rich, FJ; Published by: Published on: |
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The effects of mid and low latitude electric fields upon the ionosphere and magnetosphere Garner, TW; Crowley, G; Richmond, A; Roble, RG; Published by: Published on: |
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The impact of sub-auroral polarization streams on GPS-based navigation systems Basu, Su; Basu, S; Makela, J; Doherty, P; Wright, J; Rich, F; Published by: Published on: |
| 2005 |
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Lin, C.; Richmond, A.D.; Liu, J.Y.; Yeh, H.C.; Paxton, L.; Lu, G.; Tsai, H.F.; Su, S.-Y.; Published by: Journal of Geophysical Research Published on: Jan-01-2005 YEAR: 2005 DOI: 10.1029/2004JA010900 |
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Lin, CH; RichmondJ Y Liu, AD; Yeh, HC; Paxton, LJ; Lu, G; Tsai, HF; Su, SY; Published by: Journal of Geophysical Research-Part A-Space Physics Published on: |
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The GPS-derived total electron content (TEC), ion drift measurements from the ROCSAT-1 spacecraft at around 600 km altitude, and far-ultraviolet airglow measured by the Global Ultraviolet Imager (GUVI) carried on board the NASA TIMED satellite are utilized for studying large disturbances of the low-latitude ionosphere during the October–November 2003 superstorm period. Two chains of GPS receivers, one in the American sector (∼70°W) and the other in the Asian/Australian sector (∼120°E), are used to simultaneously observe the daytime equatorial ionization anomaly (EIA) during the entire storm period. It is found from the GPS-TEC measurements that the EIA expanded to very high latitudes with large increases of TEC right after the storm started. The large expansion of the EIA was associated with strong upward E × B drifts measured from the Ionospheric Plasma and Electrodynamics Instrument (IPEI) on board the ROCSAT-1, providing evidence of a penetration electric field and a strong plasma fountain effect. Suppression of the EIA was observed during the storm recovery, associated with downward E × B drifts that were observed by the ROCSAT-1. Significant negative storm effects in the southern hemisphere were also observed in the GPS-TEC during the first day of the recovery phase. The areas of negative storm effects are in good agreement with reductions in the [O]/[N2] density ratio inferred from the ratio of OI (135.6 nm) to LBH emissions measured from GUVI. An enhancement of the EIA was observed on the day, 1 November, that the storm was about to fully recover. Lin, C.; Richmond, A.; . Y. Liu, J; Yeh, H.; Paxton, L.; Lu, G.; Tsai, H.; Su, S.-Y.; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2005 DOI: https://doi.org/10.1029/2004JA010900 |
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Determination of Density at High Altitudes Using Rayleigh and Raman Scattering of Solar Radiation The concept of determining the density (particles/unit volume) of atomic and molecular species at high altitudes (100-600 km) by passive remote sensing of the Rayleigh and Raman Wise, John; Sharma, Ramesh; Sioris, Christopher; Chance, Kelly; Richards, E; Sullivan, B; Published by: Published on: |
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Knight, HK; Strickland, DJ; Kochenash, AJ; Hecht, JH; Morrison, D; Zhang, Y; Paxton, LJ; Burke, WJ; Rich, FJ; Published by: Published on: |
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Lin, CH; Richmond, AD; Liu, JY; Yeh, HC; Paxton, LJ; Lu, G; Tsai, HF; Su, S-Y; Published by: Journal of Geophysical Research: Space Physics Published on: |
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