Compact Laser Hygrometer for In Situ Measurement of Water Vapor from Small Unmanned Aerial Vehicles

Physical Sciences Inc. (PSI) has been awarded a research contract from the Department of Energy to demonstrate the feasibility of a compact laser hygrometer payload to make high precision measurements of water vapor from a small unmanned aircraft. The payload is based on a diode laser optical absorption sensor and sensitive detection technology.

The rate of climate change in the Arctic is larger than elsewhere on Earth. The Arctic has unique and complex couplings and feedbacks between the surface and the atmosphere that in turn modify the radiative balance there differently than elsewhere. Current understanding holds that an increase in downwelling long wave radiative flux, driven by increased water vapor and mixed phase clouds, may be accelerating climate change. There is a need to measure the thermodynamic state (water vapor, temperature and pressure) of the Arctic troposphere in order to better understand the development and impact of these clouds. A new compact sensor payload deployed on a small Unmanned Aircraft System is an efficient route to providing the data needed to advance our understanding.

Predictions of global climate change rely on models incorporating precise knowledge of greenhouse gases such as H2O and clouds. Measurements using the high sensitivity instrument for monitoring water vapor that this program will develop can be used to decrease the uncertainties that still remain. PSI’s laser hygrometer will enable measurements of water vapor from low altitude long endurance unmanned air systems to support studies of mixed phase clouds and their role in climate change in the Arctic. As larger unmanned aircraft are integrated into the national airspace, they will be used to collect meteorological data for numerical weather predictions. This is a logical extension of the Aircraft Meteorological Data Relay program that collects meteorological data worldwide from commercial aircraft. This laser hygrometer will be a key component of that meteorological payload.

For more information, contact:

Dr. David Sonnenfroh
Area Manager, Atmospheric Sciences
Physical Sciences Inc.
Telephone: (978) 689-0003