FWAT-BFF

Fast Water And Temperature Balloon Flights in Fall

1 September 2024 - 30 November 2024

Lead Scientist: Manish Gupta

Observatory: SGP (Southern Great Plains)

The response of clouds to global climate change remains poorly understood, with the equilibrium climate sensitivity (temperature change associated with doubling of CO2 concentration) critically dependent on the cloud feedback parameter. For example, low-altitude, liquid-only clouds are expected to decrease as the Earth warms, reducing overall albedo and further increasing temperatures (positive feedback). Conversely, for higher-altitude clouds that include both water and ice, the water fraction is expected to increase, increasing the clouds albedo, and cooling the Earth (negative feedback) with a significant dependence on the number of ice nucleation particles.

Cloud droplet size and growth (and the related albedo) depend on local environmental conditions, especially in supersaturated regimes. Since such entrainment happens on the centimeter-scale, aircraft flying through these zones require very fast measurements. At an aircraft speed of 10 m/s, researchers require instrumentation that can provide 50–100 Hz, in situ measurements of both water vapor and temperature in and near clouds.

Nikira Labs proposes using the FWAT instrument (developed under the DOE-funded Phase II Small Business Innovation Research program) to measure water vapor and temperature aboard the ARM tethered balloon system (TBS) to demonstrate the functionality of the FWAT design under flight conditions.

Because the scientific goal is measurement of cloud boundaries, but TBS is not permitted to fly in clouds, the campaign will emphasize flight times when local variability of near-ground humidity is highest, specifically, early morning or dusk when radiation fog is most common. Additionally, and to the extent possible, the campaign will try to select flight locations that presents geography with entrapment features, such as vegetation-rich river valleys.