  Two-point measurements of concentration are obtained in a meandering
passive-scalar plume released at five different heights within the
fully-turbulent region of a high-Reynolds number turbulent boundary layer
(TBL). These measurements are obtained using a combination of two
photo-ionisation detectors (PIDs). A stationary PID is positioned at the plume
centreline, while the second PID traverses across the plume in the wall-normal
direction. Similar to the large-scale coherence observed in the two-point
correlation map of streamwise velocity fluctuations \citep[e.g. Marusic et
al.][]{marusic2007reynolds}, the two-point correlation results of concentration
also indicate coherence in the scalar field. Particularly, the iso-contours of
correlation indicate an inclination of scalar structures in the direction of
the flow. The corresponding inclination angle is found to be a weak function of
the location of the plume within the boundary layer. However, the inclination
angle is observed to be invariant near 30$^\circ$ for all source heights that
are below $z/\delta \leq 0.33$. This observed steepness of inclination angle
relative to the inclination angle of streamwise velocity is consistently
explained through the physical model put forth by Talluru et al.
\cite{Talluru2018} that explains the organisation of scalar around the low- and
high-speed regions in the flow which inherently also have a characteristic
inclination.
