\justify A high resolution 2 m ^ { 2 } tracking detector , based on timing Resistive Plate Chamber ( tRPC ) cells , has been installed at the Faculty of Physics of the University of Santiago de Compostela ( Spain ) in order to improve our understanding of the cosmic rays arriving at the Earth ’ s surface .
Following a short commisioning of the detector , a study of the atmospheric temperature effect of the secondary cosmic ray component was carried out .
A method based on Principal Component Analysis ( PCA ) has been implemented in order to obtain the distribution of temperature coefficients , W _ { T } ( h ) , using as input the measured rate of nearly vertical cosmic ray tracks , showing good agreement with the theoretical expectation .
The method succesfully removes the correlation present between the different atmospheric layers , that would be dominant otherwise .
We briefly describe the initial calibration and pressure correction procedures , essential to isolate the temperature effect .
Overall , the measured cosmic ray rate displays the expected anticorrelation with the effective atmospheric temperature , through the coefficient \alpha _ { T } = -0.279 \pm 0.051 % /K .
Rates follow the seasonal variations , and unusual short-term events are clearly identified too .