This effort will support participation of the SPEC, Inc. instrumented Lear-25 aircraft and scientific support staff during the Ice in Clouds Experiment - Tropical (ICE-T), whose field phase is scheduled to occur during July 2011. The Lear-25 will complement the previously supported NSF/NCAR (National Center for Atmospheric Research) C-130 research aircraft by providing a highly agile platform capable of rapid climb rates during steep banking turns that will allow the rapid successive (every 1 to 2 min) penetrations of the key cloud region characterized by temperatures of -5 to -10 degC. It is in this zone where a combination of warm-rain and first-ice processes are anticipated to develop. This will in-turn allow the C-130 aircraft to concentrate on measurements in lower/warmer regions of the cloud and subcloud region, where it will document cloud condensation nuclei, ice nuclei and drop spectra measurements as well as collect upward-looking radar and lidar data encompassing the zone of Lear-25 operations. The complementary nature of these cooperating platforms will significantly increase the probability of achieving ICE-T scientific goals. The Learjet brings with it state-of-the-art cloud microphysics probes, including a new 3V-CPI instrument that combines the best features of the 2D-S (stereo) and cloud particle imager (CPI). The 3V-CPI is particularly well suited to detection of large (i.e., > 50 micron) drops that signify initiation of the warm rain process, as well as detection of first ice, which signifies the initiation of cloud glaciation.
The intellectual merit of this effort centers on increased understanding of ice initiation within growing maritime clouds and in turn its impact on precipitation formation, latent heat release and cloud dynamics, particle scavenging and chemical processes, electrical charge separation, water vapor content, and aircraft icing potential. Broader impacts will include interface with faculty and students at the University of Puerto Rico (UPR), where SPEC scientists plan to participate in the mini-conference, and potential interactions with a subset of these students in the field. Analyses supported through ICE-T are ultimately expected to enhance predictive capability of Earth's hydrological and climate systems.
SPEC Incorporated participated in the NSF-sponsored Ice in Clouds Experiment - Tropical (ICE-T) staged out of St. Croix, USVI, in July 2011. SPEC operated its Learjet research aircraft in conjunction with the NSF C-130 research aircraft that was operated by the National Center for Atmospheric Research (NCAR). The Learjet collected data using several new instruments developed at the company, including a high-resolution particle imager that can discriminate between water drops and ice particles. The combined instrumentation measured the size distributions of the water drops and ice particles, the strength of the updraft and basic atmospheric state parameters, such as temperature, pressure, humidity and position from the Global Positioning Satellite (GPS) system. Learjet data from the ICE-T project were quality controlled and placed in archives where they can be accessed by scientists from other institutions. Scientists at SPEC analyzed data collected in the strong updrafts of tropical convective clouds and determined that a secondary ice production process was primarily responsible for the production of rain at the ocean surface. The secondary ice production process occurs when large (100's of microns in diameter) supercooled drops freeze and produce many smaller ice particles. The results are will be incorporated into numerical models that predict the hydrological cycle in the Tropics.
