New Aircraft Probes in Action Again


In March, ARM Aerial Facility scientist Jason Tomlinson met with colleagues at the University of North Dakota to assist in the integration of the probes onto the Citation aircraft and to provide training on the operation of the UHSAS-A (back) and HVPS-3 (front) instruments.
In April, researchers began the Midlatitude Continental Convective Clouds Experiment (MC3E) at the ARM Southern Great Plains site, as described in this Brookhaven National Laboratory news release. As part of the airborne research portion of the campaign, NASA is sponsoring the University of North Dakota’s Citation aircraft that is providing in situ observations of precipitation-sized particles, ice freezing nuclei, and aerosol concentrations. Joining the Citation’s instrument payload for the campaign are two new aircraft probes – an airborne ultra-high sensitivity aerosol spectrometer (UHSAS-A), and a “version 3” high-volume precipitation spectrometer (HVPS-3) – purchased in 2010 by the ARM Climate Research Facility through the American Recovery and Reinvestment Act. Both probes recently completed research flights on a Gulfstream-1 aircraft for the 5-week Calwater campaign in California.

The UHSAS-A now has increased resolution for measuring a wider range of aerosol size distributions and concentrations than other instruments of a similar nature. Meanwhile, the HVPS-3 measures the number and size of precipitation particles and provides complete digital images of precipitation particles up to nearly 2 centimeters in size, which no other instrument can do. In addition, the HVPS-3 new slanted probe tip design and post-processing techniques are expected to result in more representative particle size distributions of the ice in the thunderstorm anvils and within precipitating clouds, as data collected with older probes have been questioned due to the influence of “shattering” (see YouTube video).

Using measurements from the airborne and ground-based instruments, MC3E researchers will study the entire precipitation process, from the ice that forms near the tops of clouds to the rainfall that ends up on the ground. Follow the campaign’s progress on the MC3E blog.