Participation in the Ice in Clouds Experiment - Layered Clouds (ICE-L) Field Experiment with the Stratton Park Engineering Company (SPEC) Learjet and Analysis of Data

Stratton Park Engineering Co., Inc., Boulder CO

Investigators

Abstract

More than 50% of the earth's precipitation originates in the ice phase. Poorly understood ice nucleation processes result in large uncertainties in the ability to model precipitation production and to determine the impact of clouds/precipitation on the Earth's climate. The Ice in Clouds Experiment - Layer Clouds (ICE-L) is aimed at employing new airborne measurement strategies to gain an improved understanding of ice initiation due to heterogeneous nucleation mechanisms. The field phase of the ICE L will utilize two aircraft: The National Science Foundation (NSF) C-130 research aircraft and, under the aegis of this research, the SPEC Learjet. The C-130, while well equipped for both aerosol and cloud microphysics measurements, has a practical ceiling of about 23,000 ft (7 km) msl, which sometimes will not allow the documentation of the full vertical extent of wave clouds. The Learjet, which does not have this altitude limitation, has previously made 133 penetrations of wave clouds and results from these studies are in publication. In summary, the Lear was able to carefully document regions of supercooled water drops, mixed-phase and glaciated regions of cloud, including images of ice particles that were automatically classified into habits. The high-resolution images also supported analysis of the degree of riming and side plane. Based on the Learjet studies, it was found that the location of first ice was not predictable and that rapid ice production was almost always observed where supercooled water rapidly evaporated. The nucleation mechanism of this "glaciation signature" and the location of first ice could not be explained without detailed aerosol measurements, which were not available on the Learjet. For the ICE-L field campaign the Principal Investigator will operate the SPEC Learjet in a coordinated two aircraft study with the NSF C-130. The Learjet is equipped with a comprehensive array of microphysical instruments, including a new imaging probe (the 2D-S) that is capable of imaging small ice. SPEC will also furnish a 2D-S probe for the C-130, so that both aircraft working simultaneously will rapidly document the entire vertical wave cloud structure and identify ice that may fall from above into regions of primary nucleation. The two aircraft will be utilized in a variety of coordinated flight patterns that will allow aerosol characteristics of the inflow air and detailed microphysical measurements in the ice initiation regions of cloud. Quick-look Learjet data will be placed on the ICE-L website within 48 hours. Preliminary and final datasets will be made available to all ICE-L PI's within 30 days and 90 days, respectively, after the close of the field campaign. SPEC scientists will concentrate their research on correlating C-130 aerosol characteristics with possible heterogeneous nucleation mechanisms, focusing on a new candidate, "inside-out contact nucleation", which was recently demonstrated in laboratory experiments. Broader Impacts of the work embrace significant societal consequences, including strong potential influence on the earth radiative balance and global climate change. In addition, the research will continue to contribute significantly to broader impacts through outreach programs, including dissemination of information to the scientific community, training and educational support for student interns at SPEC, Incorporated.