Bibliography

Investigation of the Causes of the Longitudinal and Solar Cycle Variation of the Electron Density in the Bering Sea and Weddell Sea Anomalies

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

Investigation of the Causes of the Longitudinal Variation of the Electron Density in the Weddell Sea Anomaly

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

Investigation of sudden electron density depletions observed in the dusk sector by the Poker Flat, Alaska incoherent scatter radar in summer

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

ion temperature; plasma convection; plasma troughs

Solar and Heliospheric Physics General Contributions II Posters

Richardson, Ian; Millan, Robyn; Paxton, Larry; Zhao, Lingling;

Published by:       Published on:

YEAR: 2014     DOI:

Magnetospheric Physics General Contributributions Posters

Millan, Robyn; Paxton, Larry; Richardson, Ian;

Published by:       Published on:

YEAR: 2014     DOI:

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:

YEAR: 2014     DOI:

On the consistency of satellite measurements of thermospheric composition and solar EUV irradiance with Australian ionosonde electron density data

Richards, P.; Meier, R.; Wilkinson, P.;

Published by: Journal of Geophysical Research      Published on: Jan-01-2010

YEAR: 2010     DOI: 10.1029/2010JA015368

LWS FST: Determine and Quantify the Responses of Atmospheric/Ionospheric Composition and Temperature to Solar XUV Spectral Variability and Energetic Particles

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:

YEAR: 2010     DOI:

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

Measured and modeled ionospheric densities, temperatures, and winds during the international polar year

Richards, PG; Nicolls, MJ; Heinselman, CJ; Sojka, JJ; Holt, JM; Meier, RR;

Published by: Journal of Geophysical Research: Space Physics      Published on:

YEAR: 2009     DOI:

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

Photoelectrons; Solar flares; XUV solar irradiance

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

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:

YEAR: 2005     DOI:

Influence of geomagnetic-ionospheric disturbances on SABER measurements of 4.3 um emission and the retrievals of kinetic temperature and carbon dioxide

Mertens, CJ; Richards, PG; , Winick; Picard, RH; Paxton, LJ; Wintersteiner, PP; Team, Saber;

Published by:       Published on:

YEAR: 2004     DOI:

Characterizing Polar Layered Deposits at the Martian North Pole: An Assessment of Local Variations

Milkovich, SM; , Head; Milliken, RE; Mustard, JF; Minitti, ME; Hamilton, VE; Wyatt, MB; Mischna, MA; McCleese, DJ; Richardson, MI; , others;

Published by:       Published on:

YEAR: 2003     DOI: