Available online at ScienceDirect. Physics Procedia 74 (2015 )

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1 Available online at ScienceDirect Physics Procedia 74 (2015 ) Conference of Fundamental Research and Particle Physics, February 2015, Moscow, Russian Federation Studies of thunderstorm events based on the data of muon hodoscope URAGAN and meteorological radar DMRL-C A.V. Kozyrev a *, N.S. Barbashina a, T.A. Belyakova b, J.B. Pavlyukov b, A.A. Petrukhin a, N.I. Serebryannik b, V.V. Shutenko a, I.I. Yashin a a National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Kashirskoe shosse, 31, Moscow, , Russia b Federal State Budget Institution Central Aerological Observatory, Roshydromet, Dolgoprudny, Moscow Region, Russia Abstract Comparison of data of meteomaps of DMRL-C radar and muonographies of muon hodoscope URAGAN during thunderstorm event has been performed. Their good agreement is observed. The possibility of cosmic rays as a tool for remote monitoring of atmospheric phenomena, including thunderstorms, is discussed The The Authors. Published by Elsevier by Elsevier B.V. This B.V. is an open access article under the CC BY-NC-ND license ( Peer-review under responsibility of the National Research Nuclear University MEPhI (Moscow Engineering Physics Institute). Peer-review under responsibility of the National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) Keywords:cosmic rays, muons, muon hodoscope URAGAN, thunderstorm, muonography, DMRL-C, anisotropy 1. Introduction Monitoring and investigation of dangerous atmospheric phenomena such as hurricanes, thunderstorms, tornadoes is one of the actual tasks. The muon diagnostics of the atmosphere is one of the new methods of research based on the registration of muon flux changes during various atmospheric processes. Cosmic-ray muons are originated in the atmosphere at altitudes km in the interactions of the primary cosmic rays with the air nuclei. Registration of muon flux variations at the Earth s surface from different directions allows to obtain a picture of the conditions in the upper atmosphere, to trace the dynamics of their changes and to identify disturbed regions [1]. *Corresponding author. Tel.: address: AVKozyrev@mephi.ru The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license ( Peer-review under responsibility of the National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) doi: /j.phpro

2 A.V. Kozyrev et al. / Physics Procedia 74 ( 2015 ) Muon hodoscope and Doppler Meteorological Radar Muon hodoscope (MH) URAGAN [2] is a part of the experimental complex NEVOD [3] since 2006 and provides simultaneous recording of muons in a wide range of zenith angles (from 0 to 80 degrees) with a spatial and angular accuracy of about 1 cm and 0.8 degrees, respectively. A matrix method of storing information is used. Every minute one supermodule of URAGAN registers and records in a two-dimensional angular matrix about 80 thousand muons. The analysis of such matrices allows us to study zenith and azimuthal dependences of the muon flux with a single detector. To analyze variations of muon flux intensity during thunderstorm events, matrixes averaged on data of three supermodules within 5 minute exposures are used. Statistics for these matrices is more than 1 million events. These muon pictures (muonographies) provide the information about changes in the spatial and angular intensity distributions of the muon flux during various atmospheric processes, including thunderstorms. The following parameters have been used as quantitative characteristics reflecting the distortion of the zenithalazimuthal distribution of the muon flux. Vector of local anisotropy (A) indicates the average direction of muon arrival recorded by the detector [4, 5]. This value is calculated as the sum of unit vectors, each of which has a reconstructed direction of a single muon track, normalized by the total number of muons. For the analysis, the anisotropy vector module and the projections of this vector onto the horizontal axis South (A S ) and East (A E ), as well as the projection on the vertical axis (A Z ) are used. The vector of relative anisotropy (r) is the difference between the local anisotropy vector in the current time and averaged over a long period anisotropy vector. In this analysis, the value of the vector r module and its projection on the horizontal plane (r h ) are used. One of the most vivid illustrations of this method for monitoring the atmosphere is the study of thunderstorm disturbances. Today, Doppler weather radars (DMRL) are unique means of meteorological observations [6], which can provide real-time accurate information about the location and nature of the movement zone of intense turbulence, hydrometeors, thunderstorm cells, etc. Modern DMRL has a view range of km and a maximum detection height of about 20 km, and provides cyclic monitoring at intervals of 3 to 15 minutes and obtaining data with a high spatial resolution (0.5 1 km) over the area of 200 thousand sq. km. The principle of operation of such radar is the conduction by each radar a survey sequence of circular azimuthal scans of the upper hemisphere at several angles so that as a result of each survey data on cloudiness and precipitation on several conical sections are collected. 3. Thunderstorms in June 2014 Thundercloud is a localized area of pronounced convection and electrical activity. It can consist of one or more cells. The average radius of the base of a thunderstorm cell is equal to R 2 km, in the middle latitudes the top of a typical cell is located at altitudes 9 15 km. Fig. 1. Meteorological conditions in the vicinity of Moscow for June 15, In June 2014, in the area of Moscow and Moscow region several thunderstorm cells were registered. One of these thunderstorms is studied in the current paper. To check and to calibrate MH by hurricane, as well as for independent

3 488 A.V. Kozyrev et al. / Physics Procedia 74 ( 2015 ) identification of thunderstorm disturbances, data DMRL-C FGBI "CAO" [8] have been used, which are weather maps characterizing the change of cloud processes and formed atmospheric disturbances (atmospheric fronts, cyclones, hurricanes, squalls, etc.). One of the features is the presence in thunderstorm event of a characteristic peak in the atmospheric pressure, which in meteorology is called "thunderstorm nose". The conditions during the passing storm front over the territory of Moscow are presented in Fig. 1 and Fig. 2. Dark areas in the figure show hazards: thunderstorm cells, gray areas rainfalls of various intensities June 15, 2014 Thunderstorm nose P,mbar Comparison with MH URAGAN data Fig 2. Dynamics of changes in the atmospheric pressure during the thunderstorm event. During the thunderstorm disturbances, the temporal dependences of atmospheric pressure, the integral counting rate I sum, anisotropy vector A, vector of relative anisotropy r, the horizontal projection of the vector of relative anisotropy r h, and the sequence of muonographies [7] (Fig. 3 and Fig. 4) were analyzed. I sum,c -1 A r r hor P,bar 0, , , , , , , , ,834 0,833 0,832 0, ,5 1395,0 1387,5 1380,0 991,2 988,4 985,6 982,8 03:00 05:00 07:00 09:00 11:00 13:00 15:00 Time 980,0 01:00 02:00 03:00 04:00 05:00 06:00 07:00 08:00 09:00 10:00 11:00 12:00 13:00 14:00 Time Fig. 3. Spatial-angular characteristics of the muon flux for June 15, 2014.

4 A.V. Kozyrev et al. / Physics Procedia 74 (2015) Fig. 4. The distortion of the angular distribution of the muon flux during thunderstorm disturbances. 489

5 490 A.V. Kozyrev et al. / Physics Procedia 74 ( 2015 ) DMRL-C MH URAGAN Fig. 5. Comparison of areas of thunderstorm disturbances in spatial angular distribution of the muon flux with weather radar maps for time interval 06:05:00-06:40:00, June 15, 2014

6 A.V. Kozyrev et al. / Physics Procedia 74 (2015) DMRL-C MH URAGAN Fig. 6. Comparison of areas of thunderstorm disturbances in spatial angular distribution of the muon flux with weather radar maps for time interval 10:20:00-11:45:00, June 15,

7 492 A.V. Kozyrev et al. / Physics Procedia 74 ( 2015 ) As can be seen from the graphs in Fig. 3, all the characteristics of the muon flux provide a good reaction to the passage of the thunderstorm. Muon images show the areas of the storm disturbances of the intensity of muon flux as well as the size of these areas (Fig. 4). In this figures, the first row corresponds to the beginning of thunderstorms, the second one to the maxima of their development, and the third to ends. Visual analysis of muon "pictures" and characteristics of the muon flux shows that investigated disturbances occurred at the same time moments as observed on the Earth s surface powerful atmospheric processes. Disturbances exceed statistical (noise) fluctuations by three standard deviations (σ) of the daily average, which suggests strong atmospheric processes that took place during the passage of thunderstorms. To identify the passing storm fronts over the Moscow region, meteomaps of DMRL-C radar and muonographies of MH URAGAN were compared. Fig. 5 shows the results of comparison for a thunderstorm on June 15, As can be seen from the Fig. 5 and Fig. 6, comparison of weather radar maps with muonographies of MH URAGAN shows a good agreement; in both cases, one and the same storm indignation was fixed in two different ways. Results of comparison show that the values of r (in terms of the statistical errors) and the direction φ of the vector projection onto the horizontal plane indicate that the horizontal vector greatly deviates in a direction opposite to the displacement of the area of a low flux. This allows quantitative comparison in order to find correlations and to identify them. For a more accurate comparative analysis, it is necessary to adjust the binding to the terrain when processing mounographies. 5. Conclusion The study of thunderstorm events showed a good response to the passage of muons through the thunderstorm cells, which manifested in changes of the counting rate and the anisotropy parameters of the muon flux. These results indicate the prospects of the use of cosmic rays as a tool for remote monitoring of atmospheric phenomena. Acknowledgments This work was performed at the unique scientific facility Experimental complex NEVOD in the frame of the Agreement between MEPhI and CAO and was supported by the Ministry of Education and Science (project No. RFMEFI59114X0002). References [1]Yashin I.I., Ampilogov N.V., Astapov I.I. et al. Present status of muon diagnostics. J. Phys.: Conf. Ser. 2013;409: [2]Barbashina N.S., Kokoulin R.P., Kompaniets K.G. et al. The URAGAN wide-aperture large-area muon hodoscope. Instrum. Exp. Tech. 2008;51(2): [3]Saavedra O., Amelchakov M.B., Barbashina N.S. et al. NEVOD-DECOR experiment: results and future. J. Phys.: Conf. Ser. 2013;409: [4]Shutenko V.V., Barbashina N.S., Kompaniets K.G. et al. Observation of heliospheric disturbances in the muon component of cosmic rays. Bull. Russ. Acad. Sci. Phys. 2009;73(3): [5]Shutenko V.V., Astapov I.I., Barbashina N.S. et al. Long-term variations in the muon flux angular distribution. Geomagnetism and Aeronomy, 2013; 53(5): [6]Meischner P., Collier C., Illingworth A., et al. Advanced Weather Radar Systems in Europe: The COST 75 Action. Bulletin of the American Meteorological Society 1997; 78(7): [7]Yashin, I.I., Astapov I.I., Barbashina N.S. et al. Real-time data of muon hodoscope URAGAN. Adv. Space Res. 2015; [8]