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Abstract: Daily UK Met Office stratospheric assimilated data for the Northern and Southern Hemispheres, accumulated for the period from 2004 to 2012 and pressure range of 1000–0.1hPa, are used in this paper. The paper presents and thoroughly discusses spatial–temporal distributions of stationary planetary wave (SPW) amplitudes and phases, calculated on the basis of geopotential height, temperature, zonal and meridional wind data for zonal wave numbers 1 and 2 (SPW1 and SPW2). The climatological planetary wave amplitudes and phases are calculated by extracting waves from three types of data: daily, monthly mean and climatological monthly mean. It has been established that magnitude of amplitudes and height-latitude distribution of amplitudes of SPW1 and SPW2 depend on data processing method for all parameters. It has also been established that height-latitude distribution amplitudes and phases significantly differ for geopotential height, temperature, zonal and meridional wind and depend on wave number and hemisphere. However, height-latitude distributions of phases are little different from each other for the used methods of data processing. [Copyright &y& Elsevier]

Abstract The ionospheric Nighttime Winter Anomaly (NWA) is a feature observed in the Northern Hemisphere at the American and in the Southern Hemisphere at the Asian longitude sector under low solar activity conditions. Jakowski et al. (2015) analyzed ground-based GPS derived TEC and peak electron density data from radio occultation measurements on Formosat-3/COSMIC satellites and confirmed the persistence of the phenomenon. Further, they assumed that Mid-latitude Summer Nighttime Anomaly (MSNA) and related special anomalies such as the Weddell Sea Anomaly (WSA) and the Okhotsk Sea Anomaly (OSA) are closely related to the NWA via enhanced wind-induced uplifting of the ionosphere. The aim of this paper is to study the factors causing these anomalies and also to investigate if these anomalies are re-produced by IRI. The results show that IRI model does include the NWA effect, though at a different longitude and could be improved for better predictions. The IRI-2016 model does show WSA in TEC but not in NmF2. Further, the IRI-2016 model could clearly predict the OSA both in NmF2 and TEC. [ABSTRACT FROM AUTHOR]

Measurements from TOMS and UARS-HALOE are used to estimate the effects of energetic particle precipitation (EPP) over the stratosphere during two geomagnetic storms occurred in November of the years 2003 and 2004. The EPP couples the solar wind to the Earth’s atmosphere and indirectly to the Earth’s climate. Due to particle precipitation, the ionization and dissociation increase, and create odd nitrogen (NO x ) and odd hydrogen (HO x ) in the upper atmosphere, which can affect ozone chemistry. In this paper, statistically significant variation in total ozone content at middle latitudes of the Southern Hemisphere is observed. The variations depend on the intensity of geomagnetic disturbances and the geomagnetic longitude. A significant variation in NO x concentration at altitudes from 30 to 50 km is observed from the profiles analysis. [ABSTRACT FROM AUTHOR]

The stratospheric temperature trend plays an important role in distinguishing between the climate systems responses to natural and human induced changes. A linear trend of monthly mean temperature from the NCEP/NCAR reanalysis dataset for both Hemispheres with 2.5° step in latitude and longitude for the period 1979–2011, were calculated on this paper. Four different stratospheric heights: 10 hPa, 30 hPa, 50 hPa, and 70 hPa were analyzed. The observed trend pattern changes with height as expected. The area of negative trends increases when we go up in the stratosphere. Lower and middle stratosphere shows positive trends, in a section of the latitudinal band between 50° S and 60° S. As we go down the stratosphere these positive trends are smoother. At 10 hPa all trends are negative. In Southern Hemisphere at 30 hPa significant negative trends at low middle latitudes were observed. These results were compared with others, obtained by models and observations. [ABSTRACT FROM AUTHOR]

Abstract: The paper is focused on ionospheric response to occasional magnetic disturbances above selected ionospheric stations located at middle latitudes of the Northern and Southern Hemisphere under extremely low solar activity conditions of 2007–2009. We analyzed changes in the F2 layer critical frequency foF2 and the F2 layer peak height hmF2 against 27-days running mean obtained for different longitudinal sectors of both hemispheres for the initial, main and recovery phases of selected magnetic disturbances. Our analysis showed that the effects on the middle latitude ionosphere of weak-to-moderate CIR-related magnetic storms, which mostly occur around solar minimum period, could be comparable with the effects of strong magnetic storms. In general, both positive and negative deviations of foF2 and hmF2 have been observed independent on season and location. However positive effects on foF2 prevailed and were more significant. Observations of stormy ionosphere also showed large departures from the climatology within storm recovery phase, which are comparable with those usually observed during the storm main phase. The IRI STORM model gave no reliable corrections of foF2 for analyzed events. [Copyright &y& Elsevier]

Abstract: This paper presents results from the Storm-Time Ionospheric Correction Model (STORM) validation for selected Northern and Southern Hemisphere middle latitude locations. The created database incorporated 65 strong-to-severe geomagnetic storms, which occurred within the period 1995–2007. This validation included data from some ionospheric stations (e.g., Pruhonice, El Arenosillo) that were not considered in the development or previous validations of the model. Hourly values of the F2 layer critical frequency, foF2, measured for 5–7days during the main and recovery phases of each selected storm were compared with the predicted IRI 2007 foF2 with the STORM model option activated. To perform a detailed comparison between observed values, medians and predicted foF2 values the correlation coefficient, the root-mean-square error (RMSE), and the percentage improvement were calculated. Results of the comparative analysis show that the STORM model captures more effectively the negative phases of the summer ionospheric storms, while electron density enhancement during winter storms and the changeover of the different storm phases is reproduced with less accuracy. The STORM model corrections are less efficient for lower-middle latitudes and severe geomagnetic storms. [Copyright &y& Elsevier]

Abstract: The present paper is focused on the global spatial (altitude and latitude) structure, seasonal and interannual variability of the most stable in amplitude and phase eastward propagating diurnal and semidiurnal tides with zonal wavenumbers 2 and 3 derived from the SABER/TIMED temperatures for full 6years (January 2002–December 2007). The tidal results are obtained by an analysis method where the tides (migrating and nonmigrating) and the planetary waves (zonally travelling, zonally symmetric and stationary) are simultaneously extracted from the satellite data. It has been found that the structures of the eastward propagating diurnal tides with zonal wavenumbers 3 and 2 change from antisymmetric with respect to the equator below ∼85km height, to more symmetric above ∼95km. The seasonal behavior of the DE3 is dominated by annual variation with maximum in August–September reaching average (2002–2007) amplitude of ∼15K, while that of the DE2 by semiannual variation with solstice maxima and with average amplitude of ∼8K. These tides revealed some interannual variability with a period of quasi-2years. The seasonal behavior of the eastward propagating semidiurnal tide with zonal wavenumber 2 in the southern hemisphere (SH) is dominated by annual variation with maximum in the austral summer (November–January) while that in the northern hemisphere (NH) by semiannual variation with equinoctial maxima. The SE2 maximizes near 115km height and at latitude of ∼30° reaching an average amplitude of ∼6K. The seasonal behavior of the eastward propagating semidiurnal tide with zonal wavenumber 3 in both hemispheres indicates a main maximum during June solstice and a secondary one during December solstice. The tide maximizes near 110–115km height and at a latitude of ∼30° reaching an average amplitude of ∼4.8K in the SH and ∼4K in the NH. The tidal structures of the two eastward propagating semidiurnal tides are predominantly antisymmetric about the equator. [Copyright &y& Elsevier]

Abstract: GPS technique is widely used to study the global structure and dynamics of the ionosphere. This paper presents data on the occurrence of large-scale ionospheric irregularities observed at Antarctic stations McMurdo-MCM4 (−78N, 167E, Φ =80°), Casey-CAS1 (−66N, 110E, Φ =80°), Mawson-MAW1 (−68N, 63E, Φ =71°), and Davis-DAV1 (−69N, 78E, Φ =75°) in 2001. The irregularities caused strong Total Electron Content fluctuations. The intensity of TEC fluctuations was estimated with the ROT parameter and rate of TEC index (ROTI) expressed in TECU/min. Storm-time development of TEC fluctuations are presented for two geomagnetic active periods: June and September 2001. Data on temporal variations in TEC along individual satellites passes were also analyzed. Polar patches were associated with deep TEC fluctuations as the TEC enhancements were 2–10 times larger than the background, whereas the TEC increased by 10–50 TECU in about 5–10min. The duration of such structures is 10–20min. At 4–5h interval, 3–5 strong and some weak patches were detected. The activity of patches depends to a low degree only on the magnetic activity index Kp. The intensity of TEC fluctuations increases during substorm activity. Diurnal, seasonal dependence, and longitudinal features of the occurrence of polar patches are also presented in the report. [Copyright &y& Elsevier]

A ‘ghost’ whistler group is one that follows a similar whistler group after a fixed and repeating time interval. This phenomenon was observed at Marion Island in the southern hemisphere. During a ninety minute period 11 whistler groups were followed, after a time interval of 600 ms, by ‘ghost’ groups. An explanation of this non-random time delay is that a component of the first group, on its way to the southern hemisphere resonates with counter-streaming electrons, close to the equatorial plane, causing some of them to diffuse in pitch angle and precipitate into the northern atmosphere. Entering the atmosphere the electrons trigger by some means, a second atmospheric discharge that produces the ‘ghost’ group. If this explanation is correct then the time delay between a ‘ghost’ and its whistler should vary with latitude. In this paper we calculate these time delays as a function of latitude. If ‘ghosts’ are found with delays that corresponded to these values it would be a powerful verification of the theory. [Copyright &y& Elsevier]