Observations of the Formation and Evolution of the Dawn-side Low Latitude Boundary Layer by the MMS.

Data from the MMS spacecraft are used to investigate the features of formation of the Low Latitude Boundary Layer (LLBL) at the dawn side of the magnetosphere for evolving orientations of the interplanetary magnetic field using dawn-side orbital segments of MMS within two hours of 6 MLT. The MMS orbit was very suitable for this study because at the flanks the spacecraft resided close to equatorial plane - an appropriate location for observing the different types of reconnection that can be responsible for formation of the dawn-side LLBL - and an apogee near 12 R_E. We present a broad view of the plasma environment in the LLBL over several days in which the interplanetary magnetic field clock angle varied between 0^oand 180^o. Case studies, based on analyses FPI distribution functions, show that reconnection close to spacecraft location and in the cusp are the main sources for populating the dawn-side LLBL of the Earth magnetosphere.