Brian Greene - April 19

Recent Advances and Applications of Utilizing Unmanned Aircraft Systems for Atmospheric Research

Boundary Layer, Urban Meteorology, and Land-Surface Processes

Brian Greene

April 19, 2019

2:00pm/ NWC 5600

Abstract: In recent years, the commercial accessibility of unmanned aircraft systems (UAS) and miniaturized sensor payloads have increased significantly, making it feasible to sample and characterize the planetary boundary layer (PBL)  using this new technology. Efforts at the Center for Autonomous Sensing and Sampling (CASS) have focused on development and optimization of custom rotary wing UAS (rwUAS) for thermodynamic and kinematic profiling of the PBL. Previous work has led to the first generation “CopterSonde” rwUAS, with emphasis on temperature and humidity sensor placement underneath the propellers for aspiration while mitigating the effects of heat sources on the aircraft itself.

While the first generation CopterSonde enjoyed many successes as the CASS pioneer rwUAS, additional field experience in the past two years has led to the production of a second iteration. The “CopterSonde 2.0” was first developed in early 2018, and was changed from an octorotor to a quadrotor aircraft with a much smaller footprint. From a meteorological standpoint, one of the key features of the new CopterSonde was the addition of a ducted fan on the front of the body for aspiration and solar shielding of the temperature and humidity sensors.

This seminar will begin with an overview of the CopterSonde 2, and discuss the results from recent experiments in sensor integration. While utilizing a ducted fan is a tradeoff in terms of payload and battery life and therefore total flight endurance, we have shown that there is in fact an improvement in measurement precision over using propeller wash aspiration. Moreover, we have shown that improper solar shielding can significantly bias temperature measurements even with aspiration. Another key influence is the orientation of the aircraft heading relative to the oncoming wind.

Next, preliminary results from the 2018 Innovative Strategies for Observations in the Arctic Atmospheric Boundary Layer (ISOBAR) field campaign will be presented. ISOBAR leveraged a unique combination of UAS, surface eddy covariance towers, sodars, and a Doppler wind lidar was leveraged to improve the conceptual understanding of stable boundary layers (SBL) over sea ice in the Bothnian Bay. To properly take advantage of each of these measurement systems as a composite analysis tool, it is necessary to first standardize the observations to a common reference.

Finally, an outlook of future directions for rwUAS characterization and applications will be presented, including comparisons to sonic anemometers, eddy covariance towers, ground-based remote sensors, and large eddy simulations (LES).