Calibration and Validation of a New In Situ Atmospheric Observing System with Large Ensembles of Low-Cost Drifting Sensors

Technological advancements in electronics integration and miniaturization are being leveraged to build and test a new in situ observing system known as GlobalSense. The system features an ensemble of disposable airborne drifters, called environmental Motes or eMotes, that are carried by wind currents much like naturally occurring dandelion or maple seeds. Once deployed from balloons or aircraft, eMotes transmit ultra-low power signals up to four times per second (4 Hz). Receiver platforms contain hardware and software to gather and process packets from multiple eMotes within range and store or retransmit data to other locations.

The underlying framework for modern-day weather forecasting is numerical weather prediction (NWP). Even the current and planned weather observing platforms leave gaps that are insufficient to meet the requirements of NWP. The GlobalSense system will enable transformational forecast improvements by filling these critical data gaps.

The novel eMote design minimizes cost, complexity, size, mass, power requirements, and fall speed. The eMote target mass is one gram or less with size on the order of centimeters. Given such low mass and an aerodynamic shape, eMotes can remain airborne and make measurements for an hour or more depending on atmospheric conditions and release altitude.

Initial eMote prototypes are fabricated using commercial-off-the-shelf materials and components that pose no significant environmental hazards. The longer range vision is to leverage biodegradable electronics including batteries so that eMotes have near zero environmental impact. This design goal is highly innovative and important if large numbers of eMotes are deployed around the world.

Current eMote prototypes have a mass of around 10 grams and fall roughly 2 meters per second using rotors to create autorotation and slow descent. eMotes currently contain micro sensors to measure temperature, relative humidity, pressure, position, velocity, 3-axis rotation, 3-axis acceleration, and 3‑axis magnetic fields. The position and other kinematic data are used to estimate atmospheric wind speed and direction.

The GlobalSense system including eMote design is modular and interoperable. Different components can be integrated to measure parameters of interest for surveillance, reconnaissance, and related environmental applications. With the same fundamental system architecture, these design attributes minimize risk from parts obsolescence and enable flexibility in satisfying a much broader range of client-specific requirements.

The conference presentation will highlight efforts to calibrate and validation GlobalSense meteorological data using independent measurements obtained with other in situ (rawinsondes) and remote sensing (LIDAR) observing systems. It will conclude with a brief discussion on the upcoming field demonstration in Spring 2018 to deploy 100 eMotes in the atmosphere and future plans to develop a fully operational system for different weather applications.