Interactive system for geomagnetic data analysis

Transcription

1 Interctive system for geomgnetic dt nlysis Igor Solovev * Institute of Cosmophysicl Reserch nd Rdio Wve Propgtion FEB RAS, Kmchtk region, Elizovskiy district, Prtunk, Mirny str., 7, Russi Abstrct. The pper suggests the methods for nlyzing geomgnetic field vritions, which re implemented in "Auror" softwre system for complex nlysis of geophysicl prmeters. The softwre system llows one to perform detiled mgnetic dt nlysis. The methods llow one to estimte the intensity of geomgnetic perturbtions nd to llocte incresed geomgnetic ctivity periods. The softwre system is publicly vilble ( This reserch ws supported by the Russin Science Foundtion (Project Nо ). 1 Introduction In this pper, we described softwre tools for geomgnetic dt nlysis, bsed on the ppliction of modern mthemticl methods nd informtion technologies. Implemented softwre methods re imed t studying of complex dynmic processes in the mgnetosphere. The stte of the mgnetosphere is determined by the prmeters of the interplnetry spce, which hs negtive effect on stellite opertion, rdio communictions nd other importnt spects of humn life. Therefore, this field of reserch is of gret scientific nd prcticl interest tody [1, 2]. Vritions of the Erth's mgnetic field contin importnt informtion on the processes in the mgnetosphere tht occur during the period of high solr ctivity. Currently, methods [3-6] nd ppliction softwre for the processing nd nlysis of geophysicl dt re being developed. They provide the users with convenient tools for conducting experimentl nd theoreticl studies (eg Over the pst 20 yers, the network of terrestril mgnetic observtories hs incresed significntly, nd lrge mount of informtion hs been ccumulted. But t the sme time, there re still unsolved problems, such s digitiztion of previously ccumulted mgnetogrms [7-8], development of utomtic systems for dt collection nd for initil dt processing [9-11]. Due to the continuous ccumultion of dt nd the trnsition to second registrtion formt, the relevnce of these tsks is growing. Anthropogenic interference rising in signl does not llow us to monitor nd to ssess the Erth's mgnetic field utomticlly. The uthors of the works [2, 9-11], on the * Corresponding uthor: kmigsol@yndex.ru The Authors, published by EDP Sciences. This is n open ccess rticle distributed under the terms of the Cretive Commons Attribution License 4.0 (

2 bsis of DtMining pplictions, developed methods for utomting the work of experts (creting so-clled "electronic experts") to solve the problems of primry dt processing, to detect industril nd physicl nomlies nd to form world dtbses. Moreover, n lgorithm bsed on the ppliction of continuous wvelet trnsform [12] nd threshold functions, first proposed in [3], showed high efficiency in detection of industril noise. To use the geomgnetic dt effectively nd to obtin qulittively new results, it is necessry to crete dequte utomted dt processing nd nlysis systems. Difficulties in solving these problems re relted to the nonsttionry structure of the field vritions, the presence of locl fetures of vrious shpes nd durtions tht crry importnt informtion bout the stte of the erth's mgnetic field. Tking into ccount the complex structure of field vritions, modern mthemticl methods nd technologies re currently used. Thus, for exmple, to solve the problems of utomtic detection of the periods of mgnetic storm initil phse [13], of removing noise, nd excluding the periodic component of geomgnetic field vritions cused by Erth rottion [14, 15], wvelet trnsform ws used. On the bsis of this tool, the problem of utomtic clcultion of geomgnetic ctivity index [16] ws lso solved, which mde it possible to reduce the error of its clcultion in comprison with the trditionl methods [17-19] by 20%. When solving the problems of the modeling of field vritions [20] nd prediction of the trvel time of the interplnetry shock wve [21], neurl networks re pplied. The developed pproch llowed us to improve the qulity of the mgnetic storm forecsting technique (by 9% of cses) in comprison with the method bsed on the logistic regression model [21]. In the ppers [3, 22], bsed on the combintion of neurl networks nd wvelet trnsform, method for utomtic estimtion of the stte of the geomgnetic field ws proposed, nd it ws implemented s softwre ppliction. The lgorithms presented in this pper re bsed on the proposed geomgnetic signl model [23, 24], including methods for identifiction of typicl field component nd vrious scle disturbnces during the periods of high solr ctivity. The obtined numericl solutions mke it possible to distinguish periods of wek nd strong geomgnetic ctivity nd to estimte the intensity of geomgnetic disturbnces. Bsed on the processing of 1- second dt, geomgnetic disturbnces cn be nlyzed in the rnges of Pc1-Pc5 nd Pi1- Pi3 pulstions. We lso constructed wvelet portrit of the mgnetic storm which shows the distribution of the disturbnce intensity long the nlyzed meridin of observtions. Numericl solutions formed the bsis of the developed softwre component of "Auror" system, which is in open ccess t (mirror linkhttp://urors2.ikir.ru:8580) nd http: // The development of the progrm system ws supported by the grnt of the RNF No Geomgnetic dt nlysis methods implemented in the softwre system 2.1 Estimte of geomgnetic disturbnces intensity is bsed on the following opertions: 1. Wvelet trnsform of minute dt is performed: W 1/ 2 t b 2 fb, : f ( t) dt, f L ( R),, b R, 0 (1.1), 2

3 where is the scle, is the bsic wvelet. In the decomposition (1.1) we use n orthonorml third-order Dubechies wvelet bsis, which ws determined by minimizing the error in dt pproximtion [23]. Wvelet is window function nd hs zero men nd, when the scle tends to be zero, coefficients W f b, describe the properties of the function f in the neighborhood of t b. 2. Then the intensity of field perturbtions t time t b is estimted by the formul [24]: where e b, W fb,. E b e b, (1.2) Fig. 1. illustrtes the result of clculting the intensity of geomgnetic disturbnces bsed on opertion (1.2) for the period December 19-21, Fig. 1. The result of the opertions (1.1), (1.2) for dt sttions "Mgdn" nd "Prtunk" during the period December 19-21, 2015; ) H-components of the Erth s mgnetic field; b) clcultion of the geomgnetic disturbnces intensity, bsed on opertion (1.2). The dshed line indictes the beginning of the mgnetic storm 2.2 Isoltion of the periods of wek nd strong geomgnetic ctivity bsed on the ppliction of threshold functions: KT,1 ( e b, 0, если eb, T,1 ) eb,, если eb, T,1 0, если eb, T,2, KT ( e, ),,2 b (1.3) eb,, если eb, T,2 The threshold vlues of T, 1 llow us to identify wek nd strong perturbtions, nd the threshold vlues of T, 2 llows us to identify strong perturbtions. Identifiction of the thresholds T, 1 nd T, 2 ws performed by ssessing posteriori risk [25], the estimtes used the dt of the observtory "Prtunk" (Kmchtk region) for the period The results of clculting the vlues of T, 1 nd T, 2 for different scle levels re shown in Fig. 2. 3

4 Fig. 2. The results of clculting the vlues of T, 1 nd T, 2. On the xis oy, the vlues of T, 1 nd T,2 re shown Fig. 3 shows the result of the ppliction of threshold functions (1.3) to detect the periods of wek nd strong geomgnetic ctivity for the period December 19-21, Fig. 3 Result of detection of periods of wek nd strong geomgnetic ctivity ccording to the dt of Mgdn nd Prtunk sttions for the period December 19-21, ) H-components of the Erth s mgnetic field; b) detected periods of wek nd strong geomgnetic ctivity (the threshold T,1 ws pplied); с) detected periods of strong geomgnetic ctivity (the threshold T, 2 ws pplied). The dshed line indictes the beginning of the mgnetic storm The softwre system supports the generlly ccepted IAGA-2002 dt formt nd uses minute dt for the processing. Fig. 4 presents the results of the minute dt nlysis of Prtunk nd Mgdn sttions during the mgnetic storm on August 15, According to spce wether dt ( on August 15, 2015, shrp increse in the solr wind speed ws registered, cused by the coronl ejection of solr mtter (CME from August 12) nd high-speed solr wind from the coronl hole (reched the centrl meridin on August 11). At "Prtunk" nd "Khbrovsk" sttions there were shrp increses in the horizontl component of the field t 08:30 UT (Fig. 4). Anlysis of the geomgnetic disturbnces intensity (Fig. 4b) shows tht, pproximtely 12 hours before the beginning of the mgnetic storm, short-term increses were observed. During the min phse of the 4

5 storm (the period of significnt decrese in the Dst-index), the mximum vlues of the geomgnetic disturbnces intensity were recorded (Fig. 4b). This exmple shows the effectiveness of the proposed softwre for geomgnetic dt nlysis tsks, which, in contrst to the nlogues, llows obtining ccurte quntittive estimtes of the degree of geomgnetic field disturbnce. Fig. 4 Softwre processing of minute geomgnetic dt during the period August 12-15, 2015 ) H- components of the Erth s mgnetic field; b) clcultion of the geomgnetic disturbnces intensity, bsed on the opertion (1.2); c) detected periods of wek nd strong geomgnetic ctivity (the threshold T, 1 ws pplied); d) Dst index. The dshed line indictes the beginning of the mgnetic storm 2.3 Estimtion of the geomgnetic disturbnces intensity in the rnge of geomgnetic pulstions According to (1.2), the intensity of positive (increse in field vrition reltive to the chrcteristic level) nd negtive (decrese in the vrition of the geomgnetic field with respect to the chrcteristic level) geomgnetic disturbnces on the scle t time point t b W f ( b, ). (1.4) e b, Then the intensity of the field disturbnce t time point t b cn be estimted: 5

6 2 E b e b 1,. (1.5) Fig. 5 shows the result of n estimte of the geomgnetic disturbnces intensity in the rnge of Pi2 pulstions (periods from 45 to 150 seconds) bsed on opertion (1.5) within the period from 7:00 UT to 10:00 UT on August 15, Fig. 5 The result of estimtion of geomgnetic disturbnces intensity in the rnge of Pi2 pulstions t Mgdn nd Prtunk sttions on August 15, 2015 from 7:00 UT to 10: 00 UT. ) H-components of the Erth s mgnetic field; b) clcultion of geomgnetic disturbnces intensity, bsed on the opertion (1.5). The dshed line indictes the beginning of the mgnetic storm Geomgnetic disturbnces in the rnge of pulstions re extrcted on the bsis of decomposition of vritions of the horizontl component of the geomgnetic field into wvelet pckets: f ( t) c j, n j, n ( t) d j, nj, n ( t) d j, nj, n ( t, (1.6) n j, k P n j, k n 0,0 ) where j k j, k n n Z scling function; j k j, n n Z i P i,, is bsis in the node k, is the wvelet-bsis in the node k j, of wvelet pcket tree obtined by j, of the wvelet pckets tree; coefficients c j, n f, j, n ; d j, n f,j, n ; P i is set of index pirs, j, k is node of the wvelet pcket tree, where j is the scle, k is the component number, the subscript (0,0) indictes the origin of the discrete dt. Approximting component c ( ) describes the trend of the geomgnetic n j, n j, n t field vrition, detiling components ( j, k) P i n d j ( t describe pulstions from, n j, n ) rnge determined by set of indexes P i. Component d j, n j, n ( t) is tken s jd i n noise. Fig. 6 shows the scheme of decomposition into wvelet pckets up to the 2nd level. 6

7 Fig. 6. Scheme of decomposition f ( ) into wvelet pckets 0,0 t In order to extrct the pulstions in the rnges Pc1, Pc2, Pc3, Pc4, Pc5 we use the Pc1 Pc2 Pc3 (1,1);(3,3) (3,2) P (3,1);(4,1), (6,3), following sets of index pirs: P 1, P 2, 3 Pc4 Pc5 P 4 (6,2);, P5 (7,1);(8,1),(10,3) Pi1 P Pi 2 1,1 ;(2,1);(2,2);(3,1);(4,1);(5,1), P Pi3 6,1 ;(7,1), P 8,1 ;(9,1), 6 respectively. nd to extrct the pulstions Pi1, Pi2, Pi3 we use Construction of wvelet-portrit of mgnetic storm: 1. According to sttion network dt on the bsis of opertion (1.2), geomgnetic disturbnces intensity is clculted; 2. On the bsis of opertion (1.1) wvelet spectrum of geomgnetic disturbnce intensity vlues is constructed. The second geomgnetic dt of the ground sttion network re used to construct the wvelet-portrit. The obtined geomgnetic disturbnces intensity wvelet-spectr show the disturbnce distribution dynmics in the nlyzed regions. Fig. 7 shows the result of constructing wvelet-portrit during the mgnetic storm on August 15, The constructed wvelet-portrit shows sptil-temporl pttern of the disturbnce dynmics before nd during the mgnetic storm long the meridin of the observtions. In the initil phse of the storm from 8:00 UT to 9:30 UT, disturbnces were observed in wide rnge of frequencies t ll sttions. During the min phse of the storm from 10:00 UT, the disturbnces t MGD, PET, MMB sttions were of generl nture, which chrcterizes lrge-scle processes in the mgnetosphere. At the high-ltitudinl KTN sttion, the mximum disturbnces were observed within the period from 11:20 UT to 15:00 UT nd coincided with the mximum vlues of the indices AE, AU, AL. Moreover, within the period from 12:30 UT to 13:10 UT, ctive regions were detected t the northern sttions of KTN nd MGD (mrked by the ovl in Fig. 7). They re likely to be ssocited with urorl processes. 7

8 Fig. 7. Second Erth mgnetic field dt processing by the «Auror» system during the mgnetic storm on August 15, 2015 ) H-components of the Erth s mgnetic field; b) wvelet-spectrum of the geomgnetic disturbnces intensity; c) indices AE (blue line), AU (yellow line) nd AL (red line); d) Dst index. The dshed line indictes the beginning of the mgnetic storm Conclusion The pper presents softwre system for geomgnetic dt processing nd nlysis tht llows us to perform the detiled nlysis of the occurrence nd dynmics of geomgnetic field perturbtions in the res under considertion during the periods of incresed solr ctivity. The implemented softwre modules re vilble in the Internet ( Comments nd suggestions on the ppliction of the softwre cn be sent to uror@ikir.ru. The work ws supported by the RNF Grnt No The uthor expresses grtitude to the orgniztions tht re registering the geomgnetic dt tht were used in the work nd to the Institute of Applied Physics for the continuous implementtion nd publiction of spce wether survey in the Internet. 8

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