Preliminary results of refined site analysis for the Antarctic node of the Latin American Giant Observatory

Preliminary results of refined site analysis for the Antarctic node of the Latin American Giant Observatory A.M Gulisano 1,2,3, V.E López. 4, S. Dasso 2,3,5, for the LAGO collaboration 6 1 Instituto Antártico Argentino/Dirección Nacional del Antártico 2 Instituto de Astronomía y Física del Espacio UBA-CONICET 3 Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires 4 Servicio Meteorológico Nacional. vlopez@smn.gob.ar 5 Departamento de Ciencias de la Atmósfera y los Océanos, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires 6 The Latin American Giant Observatory Collaboration: www.lagoproject.org

Road map of the talk Brief introduction of the LAGO Collaboration The scientific aims The detectors The site description The motivation for this study Previous results New approach and Methodology Preliminary results and conclusions

LAGO Scientific objectives:

Schematic of the detector

Space Weather Program of the LAGO Collaboration Through solar modulation of low energies cosmic rays Interactions: RC Flux Solar Activity Modulated Flux Modulated Flux Geomagnetic Field primaries Primaries Atmosphere conditions secondary particles Secondary particles detector response Signal Sinergy: Variations of the CR flux signal Solar Activity LAGO capabilities : Multi-spectral Analysis simultaneaus measurements of secondary particles at ground level and different heights and rigidity cut-off in three bands: EM, µ and multi-particle dominated.

First Antarctic Node of LAGO: planned location at Marambio Station (Lat. 64 14 24.96" S, Long. 56 37 30.34" W), (196 m a.s.l.). Instituto Antártico Argentino/DNA IAFE (UBA-CONICET) CAB (Non nuclear essays laboratory) LAGO: Space Weather dedicated site

Motivation The geographical location of the Marambio Station (north of the Antarctic Peninsula) makes it vulnerable to solar events such as Geomagnetic Storms. the purpose of this study is to find out if these phenomena can alter the structure of the upper troposphere and the lower stratosphere to eventually find a perturbed profile in a period of geomagnetic storm that can be used to improve the numerical simulations of the cascade of secondary particles of cosmic rays.

To make the simulations of the CR cascades it is necessary to calculate the atmospheric depth. Comparison between the density profile obtained from observations and the MODTRAN standard model Atmophere characterization Procedure: Characterization of height atmospheric profiles of Temperature and Pressure in Marambio using balloon soundings data from 1998 up to 2014 Comparison between the profile obtained from observations and from GDAS We also took averages for each heigh level of GDAS (Global Data Assimilation System) data From Pressure and Temperatura profiles we computed the density profile using the standard atmosphere composition and the molecular weights. We compared this profiles with the MODTRAN atmosphere models usually used at CORSIKA simulations

Previous Results for the site characterization We characterized the height profile Temperature and Pressure with balloon soundings data from 1998 up to 2014 and with GDAS data from 2008 up to 2014 We compute the height density profile from Temperature and Pressure data We compare results with the MODTRAN models The MODTRAN atmosphere profiles (Standard and Sub-Arctic) differs in the first 7 km height at least in 10% while the ones obtained from GDAS data modeled better the observed profile with percentage differences lower than 3%.

New approach In the period 1994-2016, the highest number of TG occurred in the fall and less frequently during the summer.

Data and Methodology: Seasonally we classified the 50 Geomagnetic Storms (TG) stronger and of greater Geoeffective impact for the period 1994-2016, TGs include G2 to G4 intensities as a consequence of coronal mass ejections (CMEs) and / or high velocity solar wind currents from coronal holes. For the Marambio station, we characterized in summer and winter the vertical profiles of Temperature and Atmospheric Pressure above 300 hpa (between 8 and 38 km), using radiosonde data, for the period 1998-2016, to obtain the associated climatology We study the behavior of these variables in the Marambio Station, for 9 TGs occurred in winter, characterizing the vertical profiles in a 14-day time window, using the median and first and third quartiles as error bars for the same. The climatology obtained for Winter was then compared with the behavior studied during TG at that time of the year.

CLIMATOLOGY for SUMMER and WINTER

CLIMATOLOGY for SUMMER and WINTER WINTER: Cooling in the vertical profile of Temperature about 2 km, consistent with the location of the polar vortex. (Atmospheric pressure tends to be constant above 2 km). SUMMER: the increase of temperature with height (indicates that the levels reached by the probe balloon, corresponds to the region of the ozone layer, with the upper edge of the troposphere below 8 km). The atmospheric pressure has a behavior similar to winter. greater availability of data in the Marambio Station, occurs in spring and winter. To avoid the effect of the polar vortex breaking in spring, in this work, vertical profiles around TG events were characterized for winter

Height (m) Height (m) Procedure Seasonal classification of the 50 Geomagnetic Storms (TG) stronger and of greater Geo-effective impact for the period 1994-2016, of intensities G2 to G4. Summer and winter climatology at the Marambio Station, with vertical profiles of Temperature and Atmospheric Pressure above 300 hpa (between 8 and 38 km), using radiosonde data for the period 1998-2016. Study of the behavior of these variables in the Marambio Station, during TG events occurring in winter, characterizing the vertical profiles in a 14-day time window, using the median and first and third quartile as error bars. Comparison of the climatology in Winter with the temporal evolution of the vertical profiles during TG. 36000 Winter 36000 Winter 32000 32000 28000 24000 20000 16000 Climatología Día TG 28000 24000 20000 16000 Climatología Días posteriores TG 12000 12000 8000-95 -90-85 -80-75 -70-65 -60-55 -50-45 Temperature ( C) 8000-90 -85-80 -75-70 -65-60 -55-50 -45 Temperature ( C)

Summary and preliminary Conclusions COMPARING THE CLIMATOLOGY OF TEMPERATURE, WITH THE OCCURRENCE OF TG EVENTS WE FIND THAT: Above 18 km: Prior to TG, levels are warmer than climatology. When the TG occurs, the temperature is reestablished, generally following the climatology, which gives notion of cooling. After the TG, although the temperature in general continues around the climate, it is noted that about 30 km is observed a warming, ie, the temperature seems to try to restore the initial conditions (before TG). And instead between 18 and 20 km there is a clear cooling, which continues after TG. Below 18 km: Prior to TG, they behave according to the climatology, with some Small differences, which would indicate that these levels are slightly colder than normal. When TG arrives, no noticeable changes are observed. After TG, and above 10 km, there is a strong cooling that is away from the climatology for the season. When comparing the atmospheric pressure climatology, with the occurrence of TG events, no significant changes are observed as a consequence of the occurrence of the events.

Next steps: Analize the profiles case by case Extend to other seasons Use these profiles to compare the expected cosmic ray flux using CORSIKA simulations with the MODTRAN atmosfere, the actual atmosfere non perturbed by TG, and the perturbed atmosfere after the event

Thank you! Stay tunned with us at @lagoproject Contact email: agulisano@dna.gov.ar Web Page: www.dna.gov.ar

Design improvements and characterization of the detector Temperature and pressure sensors calibration and asociated electronics Numerical simulations to find the best aspect ratio for the volumen of the detector Characterization of the best charge voltage

A system of acquisition and storage of two different types of atmospheric pressure, temperature and ambient humidity sensors was developed. Once the communication and acquisition of the data were achieved, the calibration of the sensors was carried out at the National Meteorological Service For this they developed two different communication and storage systems, one with a raspberry pi (with raspbian operating system) and the other with an arduino board. A comparison was made between the two systems to determine advantages and disadvantages between them. From the acquisition of pressure and temperature, it was possible to perform the barometric correction of the cosmic particle flow.

Detector count rate corrected for pressure and without pressure correction.

Trace histogram simulations for the new detector. The new design improvements are quantified

Charge histogram with different control voltage

Photographs of the development of the improved Antarctic detector

Relative deviation [%] Relative deviation of the counting rate corrected by presure from 19 th January up to 14 th April 2015 measured at IAFE and the comparison with the low energy scalers of the Pierre Auger Observatory Forbush decrease measured at IAFE