Unraveling secondary ice production in winter orographic clouds through a synergy of in-situ observations, remote sensing and modeling

Recent years have shown that secondary ice production (SIP) is ubiquitous, affecting all clouds from polar to tropical regions. SIP is not described well in models and for this may vastly underpredict ice crystal number concentrations in warm mixed-phase clouds. Through a synergy of modeling, remote sensing and in-situ measurements carried out in an orographic environment during the Cloud-AerosoL InteractionS in the Helmos background TropOsphere (CALISHTO) campaign, we show that SIP can have a profound impact on the vertical distribution of hydrometeors and precipitation, especially in seeder-feeder configurations which are encountered in multi-layered cloud systems. The mesoscale model simulations coupled with a radar simulator strongly support a unique signature that is characteristic of SIP; because of this, our study opens the possibility of using the vast global archive of cloud radar data for systematically inferring SIP signatures and frequency of occurrence.