1 TEMPERATURE EFFECT OF MUON COMPONENT AND PRACTICAL QUESTIONS OF ITS ACCOUNT IN REAL TIME Berkova 1,2 M., Belov 1 A., Eroshenko 1 E., Yanke 1 V. 1 Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation RAS (IZMIRAN), Moscow, Russia 2 Institute of Applied Mechanics RAS (IAM RAS), Moscow, Russia Our goals: ► to develop a method of excluding the temperature effect from the cosmic ray muon component on the base of model temperature data of the Global Forecast System (GFS) representing by the National Centers for Environmental Prediction — NCEP (USA) in real-time. ► to apply the method developed to the hourly muon detectors data available in real time: Nagoya, Yakutsk, Moscow, YangBaJing. ► to compare the temperature corrections obtained by three methods (as an example year hourly data)

2 In this work the data of the Global Forecast System (GFS) temperature model representing by the National Centers for Environmental Prediction — NCEP (USA) has been made use of: GFS model makes it possible to obtain both retrospective and prognostic data of the 3D temperature field. Temperature data Vertical temperature profile in atmosphere for Moscow: model (red triangles) and measured (black circles)

3 Temperature data The forecast error for current day (red curve) differs from improved re-forecast (black curve) of daily temperature profile on 500 hPa isobaric level and on the 100 hPa height of generation level The output data of the GFS model are temperature at the 17 isobaric levels: observation level, 1000, 925, 850, 700, 500, 400, 300, 250, 200, 150, 100, 70, 50, 30, 20, 10 hPa for four times at 00, 06, 12 and 18 hours every day. The data are interpolated on the grid of 1°x1° resolution. To obtain hourly data the interpolation by the cubic spline function on five nodal points is carried out. A query about temperature distribution is carried out at the beginning of every day, realizing the forecast for current day. The accuracy of such data is about several degrees depending on isobaric level.

4 Comparison of experimental and model temperature data in the surface layer for Moscow station Daily temperature on the 1013 hPa isobaric level (red points – nodal points of cubic spline function) Analysis shows that remainder distribution of the experimental data and the model data is approximately governed by the Gaussian distribution with good enough value of σ=0.26 Сº. The most error should be expected for the observation level as the temperature is more changeable in the lower layer. For the remainder of the hourly experimental and model data in the surface layer for Moscow σ=2.8 Сº Temperature data

5 Data of continuous cosmic ray monitoring There were four muon detectors accessible in real-time : telescope Nagoya (17 directions), telescope Yakutsk – sea level (3 directions), telescope Yakutsk - 7 mwe level (3 directions), telescope YangBaJing on Tibet (9 directions) telescope Moscow (15 directions) Besides, there were data of the counter telescope Novosibirsk (5 directions). Temperature corrections in integral approximation and in mass-average temperature approximation are calculated taking account of the telescopes geometry also as a forecast. Hourly variations were under consideration relative to the 2009 base year.

6 Integral method Temperature coefficient densities for different detectors где atmospheric sounding is required

7 Method of effective generation level where This method is based on the assumption that muons are generally generated at the isobaric level usually taking for 100 mb, and its height is changing with change of the atmosphere temperature. decay factor (%/km) – negative effect positive temperature coefficient (%/C) The height of 100 mb isobaric level:  is measured;  is calculated by the barometric formula atmospheric sounding is required

8 Mass-average temperature method where The method is based on the assumption that density of the temperature coefficient for the ground-level detectors are not grossly change with the atmospheric depth h mass-average temperature positive temperature coefficient atmospheric sounding is required BUT the use of neutron monitors data enables to determine Тm without temperature sounding

9 Muon scintillation telescope YangBaJing 6 m 2, 9 directions Data of continuous cosmic ray monitoring Muon scintillation telescope Nagoya 36 m2, 17 directions

10 Muon counter telescope Yakutsk : 0 and 7 mwe levels 4 m 2, 5 directions Muon counter telescope Moscow 2,4 m 2, 15 directions Muon counter telescope Novosibirsk 6 m 2, 5 directions Data of continuous cosmic ray monitoring 0, ±14.4, ±26.6, ±36.9, ±45, ±51.3, ±56.3, ± N, 30N, 0, 30S, 60S0, 30, 40, 50, 60

11 original uncorrected data correction for the temperature effect by the integral method correction for the temperature effect by the mass-average temperature method data corrected by the integral method equatorial neutron monitor Thailand (17GeV) Results

12 original uncorrected data correction for the temperature effect by the integral method correction for the temperature effect by the mass-average temperature method data corrected by the integral method equatorial neutron monitor Thailand (17GeV) Results

13 Accuracy check of the alternative methods Correlation curve of the muon telescope variations (Nagoya, vertical) a) with 100 hPa level height ; b) with temperature T100 of the lower 100 hPa layer ; c) with atmosphere mass-average temperature Tm. The mass-average temperature method gives far better results in spite of the fact that all atmosphere layers are allowed for with equal weights. a bc a

14 Conclusions 1)The vertical atmosphere temperature profiles obtained from the atmosphere model enable to exclude the temperature effect from the hourly observable data of the muon telescopes in real-time with the required accuracy. 2) Corrections for the temperature effect of all the muon telescopes data digitally available in real-time were get by the method described above. The original and corrected data are available to address: ftp://cr0.izmiran.rssi.ru/CosRay!/FTP_TEL/ ftp://cr0.izmiran.rssi.ru/CosRay!/FTP_TEL/ 3) The hourly vertical atmosphere temperature profile for all the points concerned are to address: ftp://cr0.izmiran.rssi.ru/CosRay!/FTP_METEO/. ftp://cr0.izmiran.rssi.ru/CosRay!/FTP_METEO/ Here corrections for the temperature effect for all telescopes of the world network with taking account of the telescopes’ geometry are arranged in real-time. Corrections are relative to the base 2009 year. 4) Besides the Internet-project with detailed description of the world network of the muon detectors and their main characteristics is to the address :