  Transmission spectroscopy with ground-based, high-resolution instruments
provides key insight into the composition of exoplanetary atmospheres.
Molecules such as water and carbon monoxide have been unambiguously identified
in hot gas giants through cross- correlation techniques. A maximum in the
cross-correlation function (CCF) is found when the molecular absorption lines
in a binary mask or model template match those contained in the planet. Here,
we demonstrate how the CCF method can be used to diagnose broad-band
spectroscopic features such as scattering by aerosols in high-resolution
transit spectra. The idea consists in exploiting the presence of multiple water
bands from the optical to the near-infrared. We produced a set of models of a
typical hot Jupiter spanning various conditions of temperature and aerosol
coverage. We demonstrate that comparing the CCFs of individual water bands for
the models constrains the presence and the properties of the aerosol layers.
The contrast difference between the CCFs of two bands can reach about 100 ppm,
which could be readily detectable with current or upcoming high-resolution
stabilized spectrographs spanning a wide spectral range, such as ESPRESSO,
CARMENES, HARPS-N+GIANO, HARPS+NIRPS, SPIRou or CRIRES+.
