Peculiarities of the behavior of the Ionosphere and HF Propagation Parameters in September 2017

Transcription

1 INTERNATIONAL JOURNAL OF MATHEMATICS AND COMPUTERS IN SIMULATION Volume 1, 018 Peculartes of the behavor of the Ionosphere and HF Propagaton Parameters n September 017 Donat V. Blagoveshchensky, Olga A. Maltseva, Tatyana V. Nktenko, Gennady A. Zhbankov Abstract Due to ncreasng of economc and scentfc actvty n the hgh lattude regons nterest to nformaton tools has been rased. One of the basc ways of exchangng nformaton s the propagaton of hgh-frequency (HF) waves, whch requres knowledge of the state of the onosphere. One of the man ways to descrbe ths state s to use models. In the present paper, the most wdespread model IRI016 s used, however t has not been adequately tested n the hgh lattude regons, especally from oblque soundng and durng dsturbances. Results of testng the state of the onosphere and the characterstcs of HF propagaton are presented for the perod of September 017, the month wth the strongest dsturbance at the end of the year. Two methods: analytcal and numercal modellng, based on ray tracng, were used to determne the maxmum usable frequency MUF on the paths of Gorkovskaya- Lovozero and Cyprus-Lovozero. A specal feature of the study s the use of vertcal and oblque soundng data wth a 15-mnute resoluton. It s shown, that durng the perod of September 6-8, the MUF experenced a postve dsturbance. The model values corresponded to the expermental magntudes rather well. The possblty of usng the analytcal method for obtanng the MUF s confrmed by ray tracng. It s shown, that for montorng of onospherc condtons along any path t s possble to use the total electron content measured by means of navgaton satelltes GPS, GLONASS. Keywords dsturbance, hf propagaton, onosphere, maxmum useable frequency. I. INTRODUCTION Knowledge of the behavor of onospherc parameters s mportant for theoretcal studes and technologcal applcatons, such as the functonng of telecommuncatons, broadcastng, and navgaton systems [1]. Ionospherc models play a specal role. Ths s especally true of the hgh lattude The work of D. V. B. D. and O. A. M. was supported by Grant from Russan Foundaton for Basc Research. The work of T. V. N. and G. A. Z. was supported by Grant under the state task N /8.9 from Mnstry of Educaton and Scence of Russa. D. V. B. s wth Sant-Petersburg State Unversty of Aerospace Instrumentaton, 67, Bolshaya Morskaya street, Sant-Petersburg , Russa (e-mal: donatbl@mal.ru) O. A. M. s wth Insttute for Physcs, Southern Federal Unversty, Stachk, 194, Rostov-on-Don , Russa (correspondng author to provde phone: , e-mal: mal@p.rsu.ru) T. V. N. s wth Insttute for Physcs, Southern Federal Unversty, Stachk, 194, Rostov-on-Don , Russa (e-mal: nk-ta195@mal.ru) G. A. Z. s wth Insttute for Physcs, Southern Federal Unversty, Stachk, 194, Rostov-on-Don , Russa (e-mal: zhbankov@p.rsu.ru) regon, whch s nsuffcently provded wth means of measurement. The most wdely used here are the VOACAP, ICEPAC, ITUREC533 (e.g. [-3]) models, but recently there has been nterest n usng the IRI model [4-5]. In the paper [6], the possblty of usng the IRI model n the hgh-lattude regon was shown. In papers [4, 7-8], examples of the use of ths model n hgh lattudes are gven, ncludng durng the dsturbance March 17, 015. To confrm ths use, a comparson s made for model values of the parameters wth expermental magntudes. The parameters relatng to the maxmum of the F layer were studed most fully: the crtcal frequency fof and the heght of the maxmum hmf. However, there s another parameter M3000F, whch can play an mportant role n montorng and forecastng the state of the onosphere as a medum for the propagaton of rado waves, as t drectly determnes the maxmum usable frequency MUF3000F = M3000F * fof. Despte the creaton of models [9-10], ths parameter s not gven suffcent attenton, especally n hgh lattudes. The pecularty s that lke the parameters fof and hmf, the parameter M3000F can be predcted usng the model. All parameters depend on the levels of solar and geomagnetc actvty therefore t s necessary to nvestgate the behavor of the onosphere n each new tme perod to dentfy features that may not be descrbed by models. For ths, t s necessary to compare the model and expermental values of the parameters. In ths paper, ths s done for the least studed regon of suffcently hgh lattudes accordng to the data of vertcal soundng at Moscow statons (55.5 N, 37.3 E), Gorkovskaya (60.7 N, 9.38 E), Lovozero (67.97 N, 35.0 E) and oblque soundng on the paths of Gorkovskaya-Lovozero (path length 900 km) and Cyprus-Lovozero (path length 3,600 km), provded by AARI on the ste ( For the study perod, September 017 was selected - the month wth the strongest dsturbance (the mnmum value s Dst = -14 nt) at the end of the year. IRI016 was used as the IRI model [11]. A feature of ths study s the use of vertcal and oblque soundng data wth a 15-mnute resoluton. Snce such data may have more varablty than sentnels, t s mportant to estmate the devaton of model values from expermental ones. In the frst secton, modellng methods are descrbed. In the second secton, results of modellng n the September 017 ncludng the strongest dsturbance of the end of year are yelded. ISSN:

2 INTERNATIONAL JOURNAL OF MATHEMATICS AND COMPUTERS IN SIMULATION Volume 1, 018 Despte the ncrease n the number of onosondes n ths zone n recent years, ther number s not suffcent for detaled montorng. Addtonally, we can use recevers of sgnals from navgaton satelltes of systems such as GPS, GLONASS provdng nformaton about the total electronc content TEC. In the paper [1], the possblty of usng TEC to obtan crtcal frequences has shown. In the end of the second secton, the possblty to use ТЕС to estmate the onospherc state s shown n the large number of ponts n a consdered zone. The last secton ncludes the concluson. II. METHODS OF MODELING To calculate the maxmum usable frequency MUF(F), two methods were used: analytcal and numercal modellng. The analytcal method conssts n usng the product of the propagaton coeffcent M3000F to the crtcal frequency fof. For comparson wth the expermental values of MOF(F) on the Gorkovskaya-Lovozero path, the coeffcent M3000F was recalculated to the MD coeffcent for the correspondng path length D = 900 km n accordance wth the algorthm [13]. The method of numercal modellng s brefly as follows. In general, the calculaton of trajectores follows the classcal ray tracng procedure [14]. Snce the onosphere s an nhomogeneous medum, t s mpossble to fnd a trajectory n t by analytcal methods. The most consstent and effectve problem of fndng the trajectory and energy characterstcs of HF rado waves s realzed wthn the framework of the geometrc optc approxmaton on the bass of the method of characterstcs [15-16] consstng of a numercal soluton of the local dsperson equaton F t, r, k, 0 n t,, r, k, H, by transformng t to a system of dfferental characterstc equatons wth respect to spatal and ray coordnates. A system of characterstc equatons for fndng trajectores n canoncal form can be wrtten as follows: dr d F p p 1 n p dp F 1 n d r r where n t,, r, k, H s the complex refractve ndex of Appleton, H s the vector of the external geomagnetc feld, r r,, s the radus vector n the sphercal k coordnate system, p p s the normalzed wave k 0 vector, and s an ndependent auxlary varable. Snce the allowance for the collson n the onospherc plasma has lttle effect on the trajectory of the ray, n can be replaced by ts real part. The calculatons use a two-dmensonal nhomogeneous model for the dstrbuton of electron concentraton n the onosphere. The dstrbuton of Ne along the plane of propagaton of rado waves s gven as the sum of the basc unperturbed part and an addtonal perturbaton: Ne N0 1 L T where N 0 s the unperturbed "base" part descrbed by the nternatonal model IRI-016 wth allowance for the possblty of correcton n the presence of vertcal soundng data [17], L s a perturbaton created by sngle large-scale nhomogenetes wth the relatve ampltude of the perturbaton N L, T s a perturbaton created by nhomogenetes wth a wave-lke structure (TID) wth ampltudes N Т.To construct the onzaton dstrbuton accordng to the IRI-016 model, takng nto account the correcton, an electron concentraton s calculated at the nodes of a gven grd plane at a gven tme. Subsequently, the values of the concentraton at an arbtrary pont are found usng, for nterpolaton, cubc splnes satsfyng the requrements of the contnuty of the functon and ts dervatve. The perturbed part of the electron concentraton δ s generally gven n the form of a sum of ellpsods: δ L = N S = dn exp x x Lx 0 y y Ly 0 z z Lz where dn (r, ) s the relatve ampltude of the wave nhomogenetes wth a perod dependng on the coordnates; 0 - the ntal phase, - the wavelength, R 0 = 3670 km - the radus of the Earth. The output of auxlary nformaton s provded: 1) N(h) profles above the transmtter and recever and at the mddle pont of the path, what s especally mportant to see when adaptng the model, ) the onzaton dstrbuton contour representng the poston of nhomogenetes, for example, the Es layer or travelng onospherc dsturbances (TID), and 3) patterns of trajectores that make t possble to dentfy the type of trajectory. Fg. 1 gves an example of the presentaton of ths nformaton. Fg. 1 an example of nformaton that makes t possble to understand the nature of wave propagaton n the model onosphere III. RESULTS OF THE IONOSPHERIC STATE ASSESSMENT IN SEPTEMBER 017 Fg. shows the behavor of the ndces of solar F10.7 and geomagnetc Dst actvty n September 017. The Dst ndex s represented by the perod ncludng the dsturbance under study. 0 ISSN:

3 INTERNATIONAL JOURNAL OF MATHEMATICS AND COMPUTERS IN SIMULATION Volume 1, 018 Fg solar F10.7 and geomagnetc Dst ndces n September 017 It can be seen that ths month stands out by a burst of solar actvty, and a strong geomagnetc dsturbance. The behavor of the parameters fof and hmf s shown n Fg. 3 for the staton Moscow, located n the mddle pont of the path Cyprus-Lovozero. On the left, the curves for the monthly medans are shown, on the rght - for the selected days, ncludng the dsturbance. Based on these data, the model was corrected n calculatng the trajectores. It can be seen that the expermental medans and model values correspond to each other qute well. For fof, the mean monthly devaton was MHz, whch ndcates that model values exceed the expermental medans. As can be seen from Fg. 3, ths refers to the evenng hours. The average absolute devaton was 0. MHz, RMS = 0.5 MHz, the relatve devaton s equal to 6.4%. For the parameter hmf, these values are km (strong excess throughout the day), km, 6.67 km and 10.37%. Perhaps such fgures are assocated wth low level of solar actvty (IRI ndex Rz1 = 16.3). Durng the selected days, the ncreased values of fof took place. On September 6, these values were ncreased due to ncreased values of F10.7, as can be seen from Fg.. On September 7, the transton from postve values of the Dstndex to negatve values has happened. The fof curve for the model shows that t descrbes the varatons durng the negatve phase very well and does not feel the postve phase. For the Gorkovskaya-Lovozero path, accordng to the data of vertcal soundng, the expermental values of the M3000F coeffcent were obtaned and the correspondng model IRI values were calculated. The values of the MUF recalculated for the length of the path are shown n Fg. 4. The symbols GRK and LOZ mean the staton (Gorkovskaya and Lovozero), the data of whch were used n the calculaton of the MUF. On the left panel, the expermental medans ("med" con) are compared wth the model values (the "IRI" con). Snce Gorkovskaya staton s located at the southern pont of the path, ts fof s hgher and t gves the upper lmt of the MUF. Lovozero staton s located at the northern pont of the path, ts fof s lower and t gves the lower lmt of the MUF. The average absolute devatons are 0.75 MHz for Gorkovskaya staton and 0.56 MHz for Lovozero staton, what leads to relatve devatons of 15.4% and 11.%. These estmates can be consdered satsfactory, what s confrmed by the results of the rght-hand panel, whch gves a comparson of the values measured drectly on the path wth model values calculated n accordance wth two optons: 1) for the ntal IRI model; ) for the model adapted to the expermental values of fof. The moments of observaton were for the perod UT = 7-13,.е. values le wthn the lmts of the left panel. For the rght-hand panel, the absolute devatons are 0.5 MHz and 0.6 MHz, the relatve devatons are 6.63% and 8.3%. Ths ndcates that the analytcal method can be fully used n hgh lattudes. The MUF values for the 1st and nd hops on the Cyprus- Lovozero path are shown n Fg. 5, together wth a 5-fold decrease n the values of the Dst-ndex. The values have gaps, and on the evenng of September 8 they seem to be below the mnmum measurement frequency of 8 MHz. The left panel shows that the MUF follows the fof values of the staton Moscow and experence the same varatons. The rght panel shows the values of the MUF of the frst hop (trangles) and the model values of the MUF calculated for the ntal model (dots) and for the model corrected for the expermental fof values (crcles) of the staton Moscow. Two ponts can be emphaszed: 1) adaptaton of the model sgnfcantly mproves the correspondence between the expermental and model values of the MUF durng the postve phase of the dsturbance, ) the values of one staton located even near the mdpont of the path durng the negatve phase of the dsturbance are nsuffcent. Ths can be seen from the example of the September 8 dsturbance, when the behavor of the onosphere at one pont does not reflect the behavor along the path. For llustraton, Fg. 6 shows the lattudnal varaton of the total electron content TEC at the merdan 30, near whch the path passes, for September 6-8, 017 at the moments UT = 10 and 18 together wth the monthly medan. It can be seen that durng the day the postve dsturbance covers the entre regon on September 6 and 7, ncludng Moscow. On September 8, the onosphere over Moscow s close to the average condton and the correcton yelded a correspondence wth the MUF. At the tme UT = 18, Moscow was n the center of the shfted trough wth a mnmal value of the TEC, hence, a mnmal value of the fof, but ths value does not correspond to the state of the onosphere along the path and the MUF value seemed to be greatly underestmated. ISSN:

4 INTERNATIONAL JOURNAL OF MATHEMATICS AND COMPUTERS IN SIMULATION Volume 1, 018 Fg. 4 the behavor of the MUF of the Gorkovskaya-Lovozero path n September 017 Fg. 5 measured and model values of MUF durng the perod September 6-8 on the path Cyprus-Lovozero Fg. 3 behavor of the onospherc parameters n September 017 accordng to the staton Moscow data ISSN:

5 INTERNATIONAL JOURNAL OF MATHEMATICS AND COMPUTERS IN SIMULATION Volume 1, 018 Fg. 6 lattudnal sectons of the behavor of TEC on September 6-8, 017 at the moments UT = 10 and 18 Pecularty of the onospherc behavour durng ths perod s that postve dsturbance took place on September, 7 th, before the man phase of a magnetc storm wth the mnmum value Dst =-14 nt on September, 8th. To show role ТЕС more clearly, we wll notce, that relatve devatons ТЕС from a medan δтес were 50 % n the afternoon and 80 % at nght for the staton Lovozero, 65 % and 135 % accordngly for the staton Gorkovskaya and 7 % and 50 % for the staton Moscow. Thereupon, t s necessary to notce, that n September 017 one more magnetc storm took place wth the mnmum value Dst =-100 nt on September, 8th, and the postve dsturbance on September, 7th took place. Ths dsturbance s characterzed by the followng δтес: 80 % at day and nght for the staton Lovozero, 80 % n the afternoon and 40 % at nght for the staton Gorkovskaya and 70 % n the afternoon for the staton Moscow. As well as n the prevous case, behavour of an АЕ ndex was absolutely quet n prevous days , and on September, 7th there were strong dsturbances. IV. CONCLUSION The hgh lattude regon s a problem area as from the pont of vew of expermental researches, and modellng. In the gven paper, the most wdespread model IRI was used. Comparson of model and expermental values of parameters fof and hmf has shown good enough conformty. Now n the paper [18], the new model of parameters fof and hmf s descrbed specally for the hgh lattude regon nstead of, probably, IRI. Its testng accordng to data of Russan onosondes can be the purpose of the future work as soon as t wll be avalable on a correspondng ste. Comparson of parameters of HF propagaton testfes that the model IRI can be used as yet, especally at adaptaton to data of the current dagnostcs, allowng consder even 15-mnute fluctuatons of MUF. It was shown that n the perod of September 6-8, the MUF on the Cyprus-Lovozero path experenced a postve dsturbance. The possblty of usng an analytcal method for obtanng the maxmum usable frequency MUF s confrmed by ray tracng. Use of the total electron content allows us to descrbe a state of the onosphere wth the larger spatal resoluton, than use of a rare network of onosondes. Processng and use of data of future network of GPS recevers are supposed. REFERENCES [1] J. M. Goodman, Operatonal communcaton systems and relatonshps to the onosphere and space weather, Adv. Space Res. vol. 36, pp. 41 5, 005. [] R. Atheno, P. T. Jayachandran, D. R. Themens, and D. W. Danskn, Comparson of observed and predcted MUF(3000)F n the polar cap regon, Rado Sc. vol. 50, pp , 015. [3] E. M. Warrngton, A. Bourdllon, E. Bento et al., Aspects of HF rado propagaton, Annals of Geophyscs. vol. 5, pp , 009. [4] D. R. Themens, P. T. Jayachandran, M. J. Ncolls, and J. W. MacDougall, A top to bottom evaluaton of IRI 007wthn the polar cap, J. Geophys. Res. Space Physcs, vol. 119, pp , 014. [5] N. Y. Zaalov, E. V. Moskaleva, and T. S. Burmakna, Applcaton of the IRI model to the HF propagaton model wth optmzaton of the onosphere parameters to day-to-day varaton, Adv. Space Res. vol. 60, pp. 5 67, 017. [6] O. A. Maltseva, N. S. Mozhaeva, and T. V. Nktenko, Comparson of model and expermental onospherc parameters n the auroral zone, Adv. Space Res. vol. 51, pp , 013. [7] D. V. Blagoveshchensky, O. A. Maltseva, M. M. Anshn, D. D. Rogov, and M. A. Sergeeva, Modelng of HF propagaton at hgh lattudes on the bass of IRI, Adv. Space Res. vol. 57(3), pp , 016. [8] D. V. Blagoveshchensky, O. A. Maltseva, M. M. Anshn, and D. D. Rogov, Sporadc Es Layers at Hgh Lattudes Durng a Magnetc Storm of March 17, 015 Accordng to the Vertcal and Oblque Ionospherc Soundng Data, Radophyscs and Quantum Electroncs. vol. 60, pp , 017. [9] D. Pancheva, and P. Mukhtarov, A sngle-staton spectral model of the monthly medan fof and M(3000)F, Studa geoph. et geod. vol. 4, pp , [10] M. Petrella, Emprcal regonal models for the short-term forecast of M3000F durng not quet geomagnetc condtons over Europe, Ann. Geophys. vol. 31, pp , 013. [11] D. Bltza, D. Altadll, Y. Zhang, C. Mertens, V. Truhlk, P. Rchards, L.-A. McKnnell, and B. Rensch, The Internatonal Reference Ionosphere 01 a model of nternatonal collaboraton, J. Space Weather Space Clm. vol. 4, A07, pp. 1-1, 014. [1] O. A. Maltseva, and N. S. Mozhaeva, Obtanng onospherc condtons accordng to data of navgaton satelltes Internatonal Journal of Navgaton and Observaton, Artcle 70168, pp. 1-19, 016. [13] G. V. Kotovch, A. G. Km, S. Ya. Mkhalov, V. P. Grozov, and Ya. S. Mkhalov, Determnng the fof Crtcal Frequency at the Path Mdpont from Oblque Soundng Data Based on the Smth Method, Geomagnetsm and Aeronomy vol. 46, 4, pp , 006. [14] L. J. Ncksch, Practcal Applcatons of Haselgrove s Equatons for HF Systems, Rado Scence Bulletn vol. 35, pp , 008. [15] J. A. Kravtsov, and J.I. Orlov, Geometrcal optcs of non-unform envronments (Nauka, Moscow, 1980), pp [16] D. S. Lukn, and J.G. Sprdonov, Applcaton of a method of characterstcs for the decson on the computer of problems of propagaton of electromagnetc waves n non-unform ansotropc envronments, In Beam approach and questons of propagaton of rado-waves (Nauka, Moscow, 1971), pp [17] J G. A. Zhbankov, and V.V. Tkhonov, Method of correcton of the onospherc (IRI-007) model accordng to vertcal soundng for the selected regon, In Scentfc-methodcal collecton (CSII, Tver, 016) vol. (544), pp. 15-0, 016. [18] J D. R. Themens, P. T. Jayachandran, I. Galkn, and C. Hall, The Emprcal Canadan Hgh Arctc Ionospherc Model (E-CHAIM): NmF and hmf, J. Geophys. Res. Space Physcs, vol. 1, pp , 017. ISSN:

6 INTERNATIONAL JOURNAL OF MATHEMATICS AND COMPUTERS IN SIMULATION Volume 1, 018 Acknowledgment I The authors would lke to thank the anonymous revewers for ther valuable comments and suggestons to mprove the qualty of the paper. Acknowledgment II The work of D. V. B. D. and O. A. M. was supported by Grant from Russan Foundaton for Basc Research. The work of T. V. N. and G. A. Z. was supported by Grant under the state task N /8.9 from Mnstry of Educaton and Scence of Russa. ISSN: