Physics of auroral phenomena : proceedings of the 33rd Annual seminar, Apatity, 02 - 05 March, 2010 / [ed.: A.G. Yahnin, A. A. Mochalov]. - Апатиты : Издательство Кольского научного центра РАН, 2011. - 206 с. : ил.

“P hysics o f Auroral P henom ena”, Proc. XXXIII A nnu al Seminar, A patity, pp. 125 -1 2 8 , 2011 © Kola Science Centre, Russian Academy of Science, 2011 Polar Geophysical Institute VALIDATION OF THE MODEL IRI - 2007 BY THE LATEST EXPERIMENTAL DATA IN AURORAL IONOSPHERE L.N. M akarova, A.V. Shirochkov, A.V. Frank-Kamenetsky, V.D. N ikolaeva Arctic and Antarctic Research Institute, 38 Bering Street, 198397 Saint-Petersburg, RussianFederation e-mail: lumak@aari.nw.ru. phone: 7-812-3373157 Abstract. Numerical calculations of ionospheric parameters by means of the model IRI-2007 were compared with the corresponding experimental data of vertical ionospheric sounding made at the auroral station Tromse (q>= 69°40’ N; X = 18°56’ E ) during September of 2009 - February 2010. Experimental and calculated parameters of the ionograms as well as of vertical profiles o f electron density were compared for the same periods of time. It was found that the model values of the heights o f electron density maximum dining noontime exceed the corresponding experimental values. The same effect was obtained in comparison o f the model and experimental foF2 values. This difference could be explained by the fact that empirical model IRI-2007 is compiled by the data of the epoch before 2008 and could not contain the data of the year 2009. However epoch of 2009 is characterized by extremely low level of the solar activity which was expressed in complete absence of the sunspots as well as by very low values of parameters of the solar wind (its magnetic field, density and velocity). Such very low level of the solar activity was responsible for comparatively low intensity of the ionospheric electric fields which in its turn resulted in the low values o f h maxF2 and foF2. Our conclusion is that the model IRI-2007 could not adequately describe a real situation in the auroral ionosphere in the periods of very low solar activity. Results of comparison numerical calculations and experimental ionospheric parameters The main goal o f this work is validation of the model IRI - 2007 by the latest experimental data in auroral ionosphere. We choose the ionospheric model IRI because of several reasons: 1. IRI - is a global empirical model. We may use it in high latitudes. 2. IRI is based on the real ionospheric data from 1994 to 2007 year. IRI is persistently updating and has several versions. In current work we use the latest modification IRI 2007. 3. Model IRI covers all kinds o f ionospheric observations (incoherent scatter, vertical sounding and satellite data) 4. Using this model we can plot the vertical electron density profile from 50 to 1500 km. Sun spot number, AP and F10.7 indexes are used in IRI as input parameters of magnetic and solar activity. For the correct simulation data file AP.dat was supplement with real data of AP and F10.7 indexes from 2007 till 2010. For the investigated period Wolf numbers were entered manually. For the model accuracy estimation was made the comparison with the real data from the ionosonde Tromso. Tromso station is situated in Norway at 69°40’n.l. and 18°56’e.l. - in the middle of the auroral zone. Sounding data are located in the Internet in real time with 15 minutes resolution in graphical form (ionograms). From the ionograms we obtained the following parameters: foF2 - critical frequency o f F2 layer hmF2 - maximal altitude of F2 layer f0E - critical frequency o f E layer hmE - maximal altitude of E layer In the following analyses we used near-noon hourly data from 10 to 15 hours LT from September 2009 till February 2010. Table 1 represents the comparison results o f simulation data with real sounding parameters of high-latitude ionosphere in values o f standard deviation (o). Also in this table one can see mean monthly values of o. 125