CALIOP and CloudSat Revelations of Ice Cloud Properties within Dust-Infused Baroclinic Cyclones

The occurrence of mid-latitude cyclones lofting and entraining dust to ice-forming altitudes in the desert regions of northern Africa and eastern Asia is shown to be a routine annual phenomenon. The nature of these Dust-Infused Baroclinic Storms (DIBS) is largely unknown from a climate context since they can possess significantly unusual micro- and macrophysical cloud properties that fall within the broad definitions of aerosol indirect effects. For example, DIBS ice particles are typically much smaller than non-DIBS counterparts and possess colder cloud top temperatures on the order of 10s of degrees Celsius. Cloud lifetimes are also distinctly longer for DIBS, lasting days longer than cirrus formed in clean environments. In addition, DIBS clouds are shown to form shallow convective cells at the tops of the cirrus shield that are similar in appearance and structure to low-level marine stratocumulus. It has been hypothesized that this upper-level convection is a result of the interplay between shallow turbulence caused by radiative cooling at the cloud top and latent heating of secondary ice formation. This study uses the combined measurements of CALIOP and CloudSat to characterize these DIBS and—in combination with WRF-Chem—lidar and radar simulators to determine cloud properties necessary to produce such unique signatures.