@article{2a9d9e39554b4bdabb69bd6bef28d654,
title = "A mid-latitude spread F over an extended European area",
abstract = "A three-year study (2017, 2020, 2021) of diurnal and seasonal characteristics of nighttime spread F over eight Digisonde European stations covering an extended latitude and longitude range of the European mid-latitude ionosphere is presented. The findings of the study underline the significant seasonal differences between higher and lower latitude stations which is in line with the findings of previous studies. Moreover, we attempt to correlate spread F activity and Travelling Ionospheric Disturbances (TID) over Digisondes, identified on GPS detrended TEC maps from the DRAWING-TEC project at 10-min resolution for 2017. The similarity in spread F activity at nearby stations supports the hypothesis that spread F development over nearby stations can be attributed to common TID activity affecting both stations.",
keywords = "Frequency spread F, Latitudinal variation, Mid-latitude spread F, Range spread F, Solar activity, Travelling ionospheric disturbances",
author = "Paul, {K. S.} and H. Haralambous and C. Oikonomou and Singh, {A. K.} and Gulyaeva, {T. L.} and Panchenko, {V. A.} and D. Altadill and D. Buresova and J. Mielich and T. Verhulst",
note = "Funding Information: To investigate the similarity in spread F characteristics in conjunction with TID activity affecting nearby Digisonde stations, GPS detrended TEC maps from the DRAWING-TEC project at 10-min resolution were also used in our study for 2017. The Dense Regional And Worldwide INternational GNSS-TEC observation (DRAWING-TEC) project provides high-resolution ionospheric maps of TEC, detrended-TEC and Rate of TEC Indices (ROTI) (Otsuka et al., 2011, 2013) from GPS receiver stations in Europe, Japan and North America. TEC fluctuations were extracted in these maps by subtracting the 1-h running average (average over ±30 min centred on the corresponding data) from the TEC time series for each pair of satellite and receiver. It must be noted, that estimated TEC perturbations incorporate both temporal and spatial variations. The precision of the relative change of TEC is theoretically 0.01–0.02 TECU (where 1 TECU = 1016 m−2), which corresponds to 1% of the wavelength of GPS signals L1 (0.19 m) and L2 (0.24 m) (Spilker and Parkinson, 1996). The data is available on the free accessible website (https://aer-nc-web.nict.go.jp/GPS/DRAWING-TEC/). Since d-TEC maps were not available after September 15, 2017 over Europe and the spread F statistics in this study correspond to the period of 2017, 2020 and 2021, we used the spread F events over European stations for 2017 (up to September 15, 2017) to support our hypothesis that the similarity in spread F statistics in nearby station pairs such as Chilton-Dourbes, Juliusruh-Pruhonice and Rome-Roquetes may be attributed to TID events affecting both stations.These findings suggest that over low mid-latitude stations, spread F occurrence maximizes during Summer mainly from May to July with an average spread F occurrence rate of 67%. A secondary maximum over Roquetes, Rome and Nicosia is noted during January approximately at 42%. Paul et al. (2019) reported that spread F occurrence increases during the Summer solstice over Nicosia. Chen et al. (2011) observed that the occurrence rate of nighttime spread F maximizes over the Chinese mid-latitude sector during Summer. Paul et al. (2022) noted a spread F occurrence peak from May to August (∼32.5%) with a secondary peak around January–February (∼20%) over Nicosia from 2009 to 2020. By analyzing GPS TEC, Herna{\'n}dez-Pajares et al. (2006) have reported nighttime TID activity appears over Europe most frequently pre-midnight, around June solstice which in turn supports the high spread F occurrence over low mid-latitudes. Huang et al. (2011) studied mid-latitude spread F over two Chinese stations and observed a higher spread F occurrence during Summer and Winter periods. Publisher Copyright: {\textcopyright} 2023 Elsevier Ltd",
year = "2023",
month = jul,
doi = "10.1016/j.jastp.2023.106093",
language = "English",
volume = "248",
journal = "Journal of Atmospheric and Solar-Terrestrial Physics",
issn = "1364-6826",
publisher = "Elsevier Ltd.",
}