Context : Classical T Tauri stars are variable objects on several timescales , but just a few of them have been studied in detail , with different observational techniques and over many rotational cycles to enable the analysis of the stellar and circumstellar variations on rotational timescales .

Aims : We test the dynamical predictions of the magnetospheric accretion model with synoptic data of the classical T Tauri star V2129 Oph obtained over several rotational cycles .

Methods : We analyze high resolution observations obtained with the HARPS , ESPaDOnS , and SMARTS spectrographs and simultaneous photometric measurements , clearly sampling four rotational cycles , and fit them with cold/hot spot models and radiative transfer models of emission lines .

Results : The photometric variability and the radial velocity variations in the photospheric lines can be explained by the rotational modulation due to cold spots , while the radial velocity variations of the He i ( 5876 Å ) line and the veiling variability are due to hot spot rotational modulation .
The hot and cold spots are located at high latitudes and about the same phase , but the hot spot is expected to sit at the chromospheric level , while the cold spot is at the photospheric level .
The mass accretion rate of the system is stable overall around ( 1.5 \pm 0.6 ) \times 10 ^ { -9 } M _ { \odot } yr ^ { -1 } , but can increase by three times this value in a rotational cycle , during an accretion burst .
The H \alpha and H \beta emission-line profiles vary substantially and are well-reproduced by radiative transfer models calculated from the funnel flow structure of three-dimensional magnetohydrodynamics simulations , using the dipole+octupole magnetic-field configuration previously proposed for the system .
Our diskwind models do not provide a significant contribution to the emission or absorption H \alpha line profile of V2129 Oph .

Conclusions : The global scenario proposed by magnetospheric accretion for classical T Tauri stars is able to reproduce the spectroscopic and photometric variability observed in V2129 Oph .