Abstract
Abstract. A new comprehensive data collection by Damboldt and Suessmann (2012a) with monthly foF2 and M(3000)F2 median values is an excellent basis for the derivation of long-term trends in the ionospheric F2 region. Ionospheric trends have been derived only for stations with data series of at least 22 years (124 stations with foF2 data and 113 stations with M(3000)F2 data) using a twofold regression analysis depending on solar and geomagnetic activity. Three main results have been derived: Firstly, it could be shown that the solar 10.7 cm radio flux F10.7 is a better index for the description of the solar activity than the relative solar sunspot number R as well as the solar EUV proxy E10.7. Secondly, the global mean foF2 and hmF2 trends derived for the interval between 1948 and 2006 are in surprisingly good agreement with model calculations of an increasing atmospheric greenhouse effect (Rishbeth and Roble, 1992). Thirdly, during the years 2007 until 2009, the hmF2 values and to a smaller amount the foF2 values strongly decrease. The reason for this effect is a reduction of the thermospheric density and ionization due to a markedly reduced solar EUV irradiation and extremely small geomagnetic activity during the solar cycle 23/24 minimum.
Highlights
Model DGeevoeslocipemnteifnictiittfioiFAns1ssn0iet.nh7ceedwsiifsnafaseflrryuueesntenotdciueoisnnoesofttsehtphaehdeeosMorpoifctliRaomkre.duaymceptialsvroiDatGlymareceeaatvecuortesissevlfsiocotDymFipies2iancmrnaudknseetedsxdiifohnitvnocmastrFdiae2-, Long-term trends in the upper atmosphere/ionosphere have rive the small ionospheric long-term trends
The trend analyses presented in this paper are based on the data collection of Damboldt and Suessmann (2012a) with monthly median values of foF2 and M(3000)F2 from more than 200 different stations (foF2: 259 stations, M(3000)F2: 240 stations)
In the first two of three subsections, trends in hmF2- and foF2 data series are separately derived by use of the solar sunspot number R as well as the solar 10.7 cm radio flux F10.7
Summary
Model DGeevoeslocipemnteifnictiittfioiFAns1ssn0iet.nh7ceedwsiifsnafaseflrryuueesntenotdciueoisnnoesofttsehtphaehdeeosMorpoifctliRaomkre.duaymceptialsvroiDatGlymareceeaatvecuortesissevlfsiocotDymFipies2iancmrnaudknseetedsxdiifohnitvnocmastrFdiae2--, Long-term trends in the upper atmosphere/ionosphere have rive the small ionospheric long-term trends. In the present been initiated by model calculations of Roble and Dickin- paper, trend analyses are carried out for more than 100. Son (1989), Rishbeth (1990), and Rishbeth aHndyRdorbolel(o1g99y2).andworldwide distributed ionosonde Hstaytidonrsoulosinggythaenir dfoF2. They predicted −10 to −20 km a lowering of the and a reduction of. F2 the cpreitaickalhEferiaegqhruttehhnmcSyF2fyoFbsy2temamnodnthhmlyFm2 eddaiatan series values cooflltehcetseedpainrEamaaenrtetehrws Bremer: Long-term trends in the ionospheric F2 region with different solar activity indices latitude −45 −45 longitude
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
