Atmospheric Boundary Layer Measurements Using Suites of Low-Cost Actively and Passively Controlled Sondes

It is the purpose of this project to develop an affordable sonde that can either be actively and passively controlled for coordinated sampling during weather events. Measuring of atmospheric boundary conditions is normally reserved for balloon-mounted sensors that are considered disposable. These sensors, while moderate in cost, d are at the mercy of the weather and atmospheric conditions, making them difficult if not impossible to recover and reuse. They are most often left behind and go unutilized for additional data collection. This creates a unique problem and a need to inexpensively produce passively controlled radio- or drop-sondes. When high accuracy localized measurements are required, the sonde can be fixed to an actively controlled system, i.e., unmanned aircraft or drone, to record measurements of a boundary layer at a given and adjustable location. With an actively controlled system the controller can determine the most critical point of measure and move with the weather system to maintain the optimum point of data collection.

This talk discusses a low cost all-in-one sonde system. Using high accuracy integrated sensors, high speed microcontrollers, onboard EEPROM and radio transmission, boundary layer conditions can be accurately measured by active (drone mounted) or passive controlled (balloon, rocket or dropping) systems. The data currently collected is GPS location, live time monitoring, barometric pressure, inertial data, humidity and temperature, light, and optionally wind speed and direction. The accuracy and frequency of these sensors meet or exceed requirements laid out by the national weather service and report data in NetCDF format that easily integrates into forecast models.

In order to prove accuracy and precision of these instruments, flights were conducted to validate for each sensor. Sondes mounted to a drone are deployed to a specific location. In addition to, the drone can be preprogrammed for autonomous flight to profile a given area. All data is reported, live feed, to a ground control station via 900 MHz radio links and is capable of monitoring multiple sensors at once. High speed data is recorded to the onboard EEPROM for later off loading and lower speed data is reported through radio links to give a real-time view of atmospheric conditions.

Validation tests were conducted at the DOE ARM SGP site. Results from the LAPSE-RATE (Lower Atmospheric Process Studies at Elevation - a Remotely-piloted Aircraft Team Experiment) and CLOUD-MAP (Collaboration Leading Operational Unmanned aircraft Development for Meteorology and Atmospheric Physics) fight campaigns will be presented, with data from up to 13 sondes at a single time. These occurred in Colorado's San Luis Valley, a high-altitude valley that includes farmland, grassland, rivers and sand dunes and is surrounded by tall mountain peaks. This environment provided a variety of interesting sampling opportunities related to boundary layer structure and development and its connection to complex terrain and convective initiation. In addition to, results will be presented from extreme conditions as it was flown on NASA’s WB-57 high altitude research platform. It reached and sustained an altitude of 70,000 foot where temperatures were as low as -65* C.