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Coronal mass ejections (CMEs) are routinely tracked with imagers in theinterplanetary space while magnetic clouds (MCs) properties are measuredlocally by spacecraft. However, both imager and insitu data do not providedirect estimation on the global flux rope properties. The main aim of thisstudy is to constrain the global shape of the flux rope axis from localmeasurements, and to compare the results from in-situ data with imagerobservations. We perform a statistical analysis of the set of MCs observed byWIND spacecraft over 15 years in the vicinity of Earth. With the hypothesis ofhaving a sample of MCs with a uniform distribution of spacecraft crossing alongtheir axis, we show that a mean axis shape can be derived from the distributionof the axis orientation. In complement, while heliospheric imagers do nottypically observe MCs but only their sheath region, we analyze one event wherethe flux-rope axis can be estimated from the STEREO imagers. From the analysisof a set of theoretical models, we show that the distribution of the local axisorientation is strongly affected by the global axis shape. Next, we derive themean axis shape from the integration of the observed orientation distribution.This shape is robust as it is mostly determined from the global shape of thedistribution. Moreover, we find no dependence on the flux-rope inclination onthe ecliptic. Finally, the derived shape is fully consistent with the onederived from heliospheric imager observations of the June 2008 event. We havederived a mean shape of MC axis which only depends on one free parameter, theangular separation of the legs (as viewed from the Sun). This mean shape can beused in various contexts such as the study of high energy particles or spaceweather forecast.

Global axis shape of magnetic clouds deduced from the distribution of their local axis orientation