Scalar spatial correlations in the supersonic mixing flowfield produced by staged sonic transverse injection into a Mach 2.0 supersonic air stream were investigated using acetone planar laser-induced fluorescence (acetone PLIF) data. Gaseous helium was used for the primary injection and air was used for the secondary injection. Turbulent behavior was examined from side-view images. The single-time two-point spatial correlations based on the concentration fluctuations of injectant were obtained from the acetone PLIF data. Contour maps of the correlations indicate that significantly organized large-scale flow structures were recognized as inclined ellipses toward flow direction. They were seen in the upper jet boundary region and result in the width of the time-averaged jet boundary. By comparing with helium and air single injection cases, the staged injection exhibited enhancement of growing the large scale structure in size, and strong merging between the primary and the secondary jet which indicates the main flow air does not mix from the interface region of them but the periphery of the combined jet. PDF maps based on the instantaneous PLIF intensity revealed highly intermittent feature of the large-scale structure observed in the single-shot image and correlation maps.