Improving the Balloon-borne Ice Cloud Particle Imager (B-ICI)

Atmospheric constituents, such as aerosols and clouds, greatly affect the
radiative properties of the atmosphere. Clouds play a substantial role in this
radiative balance. To better understand the contribution of cirrus clouds im-
proved modelling and in-situ observations are needed.
For further improving current climate-modelling parameters, accurate pa-
rameterization of these clouds are required. From in-situ measurements, the
size distribution of cirrus ice particles, their concentration and shape param-
eters can be determined. This can be achieved with the iBalloon-borne Ice
Cloud particle Imager (B-ICI). Campaigns done with the B-ICI and resulting
parameetrizations have contributed to more accurate characterization of cirrus
clouds.
The B-ICI is collecting and imaging ice particles with a pixel resolution
of 1,65 µm/pixel. With detailed image analysis at this accuracy particles >
20µm can be distinguished, dimensions and concentration can be derived, and
particles can be sorted according to their shape. An improved version of B-ICI
is currently being developed. This new version of the instrument is primarily
improving image quality to enable easier and more automated image processing.
Secondarily, changes in the design will reduce the weight of the instrument
and simplify the method for sampling of ice particles. A more light-weight
instrument will allow adding other sensors. In particular, an optical particle
counter to measure aerosol and small ice particles will be added to the B-ICI.
This addition of an optical particle counter will result in more accurate size
distributions in addition of providing complementary aerosol measurements. In
this paper, we will highlight these changes and improvements in the B-ICI set-
up.