Ionospheric Measurements made at Halley Bay

Bellchambers, W. H.; Piggott, W. R.

doi:10.1038/1821596a0

Cited by 113 publications

(88 citation statements)

References 2 publications

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“…The ionospheric phenomena of MSNA have intensively been studied (e.g., Bellchambers and Piggott, 1958;Penndorf, 1965;Burns et al, 2008;He et al, 2009;Thampi et al, 2009;Lin et al, 2009Lin et al, , 2010Liu et al, 2010). All these authors revealed that during local summer, the electron density in these regions is much larger at nighttime than at daytime.…”

Section: Comparison Of Mass Density Variations With Ionospheric Msnamentioning

confidence: 99%

“…The MSNA refers to the phenomena of nighttime electron density anomalous enhancements at midlatitudes during local summer seasons. In the Southern Hemisphere, the MSNA (also named Weddell Sea anomaly -WSA) was first observed by ground-based ionosondes in the 1950s (e.g., Bellchambers and Piggott, 1958;Penndorf, 1965) and further detailed by using satellite observations in recent years (Burns et al, 2008;Lin et al, 2009;He et al, 2009). The northern WSA-like features (with two electron density anomalous regions) have later been widely investigated by various observations (Lin et al, , 2010Thampi et al, 2009;Liu et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

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Tidal signatures of the thermospheric mass density and zonal wind at midlatitude: CHAMP and GRACE observations

et al. 2015

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Abstract. By using the accelerometer measurements from CHAMP and GRACE satellites, the tidal signatures of the thermospheric mass density and zonal wind at midlatitudes have been analyzed in this study. The results show that the mass density and zonal wind at southern midlatitudes are dominated by a longitudinal wave-1 pattern. The most prominent tidal components in mass density and zonal wind are the diurnal tides D0 and DW2 and the semidiurnal tides SW1 and SW3. This is consistent with the tidal signatures in the F region electron density at midlatitudes as reported by Xiong and Lühr (2014). These same tidal components are observed both in the thermospheric and ionospheric quantities, supporting a mechanism that the non-migrating tides in the upper atmosphere are excited in situ by ion-neutral interactions at midlatitudes, consistent with the modeling results of Jones Jr. et al. (2013). We regard the thermospheric dynamics as the main driver for the electron density tidal structures. An example is the in-phase variation of D0 between electron density and mass density in both hemispheres. Further research including coupled atmospheric models is probably needed for explaining the similarities and differences between thermospheric and ionospheric tidal signals at midlatitudes.

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Section: Comparison Of Mass Density Variations With Ionospheric Msnamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Tidal signatures of the thermospheric mass density and zonal wind at midlatitude: CHAMP and GRACE observations

et al. 2015

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“…A classic example of this is the Weddell Sea Anomaly (WSA), which occurs during the southern hemispheric summer period (e.g., Bellchambers and Piggott, 1958;Horvath andEssex, 2000, 2003;Horvath, 2006;Jee et al, 2009;Lin et al, 2009). The WSA is characterized by a reversal of the normal diurnal cycle, with electron density maximizing between 22:00 LT and local midnight, and the Correspondence to: S. V. Thampi (smithathampi.rish@gmail.com) diurnal minimum occurring near local noon.…”

Section: Introductionmentioning

confidence: 99%

Mid-latitude Summer Nighttime Anomaly (MSNA) – observations and model simulations

et al. 2011

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Abstract. In this paper, we present model simulations of the Mid-latitude Summer Nighttime Anomaly (MSNA) in the Northern Hemisphere, which is characterized by noontime dip and evening maximum in the diurnal variation of the ionospheric density. The simulations are carried out using SUPIM (Sheffield University Plasmasphere Ionosphere Model) for solar minimum at 135 • E longitude where MSNA is most pronounced in the Northern Hemisphere. The simulations are used to understand the relative importance of electric fields, and zonal and meridional winds in the formation of MSNA. The wind velocities measured by the Middle and Upper atmosphere radar (MU radar) and those obtained from the horizontal wind model (HWM93) are used. The results show that the formation of MSNA is closely related to the diurnal variation of the neutral winds with little contribution from the changes in the electric fields. The observed features of MSNA are better reproduced when MU radar winds are used as model input rather than HWM winds.

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“…Major deviations from Chapman theory (Chapman 1931), which is based on the regular variability of the electron concentrations with solar zenith angles, are named "anomalies." Many ionospheric researchers (Bellchambers and Piggott 1958;Penndorf 1965;Dudeney and Piggott 1978) studied the F2 layer over Antarctica using ground-based ionosondes. They found a region near the Antarctic Peninsula including the Weddell Sea area with an anomalous behavior in f0F2.…”

Section: Introductionmentioning

confidence: 99%

PCA analysis of the nighttime anomaly in far-from-geomagnetic pole regions from VTEC GNSS data

2015

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The Weddell Sea Anomaly (WSA) is defined when the nighttime plasma density is greater than the daytime density in the area near the Weddell Sea, more specifically in the region limited by 50°S-70°S in latitude and 225°E-315°E in longitude. A similar ionospheric anomaly is also observed near the Okhotsk Sea in the northern hemisphere, and such a feature was named as Okhotsk Sea Anomaly (OSA). The objective of this work is to infer possible physical causes of the WSA and OSA phenomena. To that end, we applied the principal component analysis (PCA) technique to the vertical total electron content (VTEC) from global International GNSS Service (IGS) in order to analyze the temporal and spatial variations of the ionosphere during noon and night in far-from-magnetic pole regions, during a 3-year period at high (2000)(2001)(2002) and low (2006)(2007)(2008) solar activity conditions. The first mode of PCA applied on VTEC scattering represents on average the 93 % of the total VTEC variability. Thus, the PCA expansions up to mode 1 resulted enough to show WSA and OSA during summer solstices in both solar activity conditions, as well as WSA during spring equinox during low solar activity. Besides, the analysis of the temporal variations of these first modes should provide the interpretation of a probable physical explanation to the observed anomalies. We conclude that the main contributors to the anomalies should be a combination of the same physical mechanisms that explain annual variation and semiannual anomaly in that regions located far from the magnetic poles.

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Ionospheric Measurements made at Halley Bay

Cited by 113 publications

References 2 publications

Tidal signatures of the thermospheric mass density and zonal wind at midlatitude: CHAMP and GRACE observations

Tidal signatures of the thermospheric mass density and zonal wind at midlatitude: CHAMP and GRACE observations

Mid-latitude Summer Nighttime Anomaly (MSNA) – observations and model simulations

PCA analysis of the nighttime anomaly in far-from-geomagnetic pole regions from VTEC GNSS data

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