Ozone (O₃) in the lower stratosphere (LS) is responsible for absorbing much of the biologically damaging ultraviolet (UV) radiation from the sunlight, and thus plays a critical role in protecting Earth's environment. By absorbing UV light, O₃ heats the surrounding air, leading to the vertical stratification and dynamic stability that define the stratosphere. Halogen species from anthropogenic compounds such as CFCs can cause significant damage to the O₃ layer in the LS and have led to the formation of the Antarctic ozone hole. Accurate measurement of O₃ in the LS is the first step toward understanding and protecting stratospheric O₃. The UAS Ozone Photometer was designed specifically for autonomous, precise, and accurate O₃ measurements in the upper troposphere and lower stratosphere (UT/LS) onboard the NASA Global Hawk Unmanned Aircraft System (GH UAS) and other high altitude research platforms such as the ER-2 and WB-57. With a data rate of 2 Hz, the instrument can provide high-time-resolution, detailed information for studies of O₃ photochemistry, radiation balance, stratosphere-troposphere exchange, and air parcel mixing in the UT/LS. Furthermore, its accurate data are useful for satellite retrieval validation.  Contacts: Troy Thornberry, Ru-Shan Gao

NOAA Ozonesonde payloads include an Electrochemical Concentration Cell (ECC) ozonesonde, and a radiosonde to telemeter data to the ground and provide in situ measurements of temperature, pressure, relative humidity (surface to upper troposphere), and GPS coordinates. Sounding data typically reach an altitude of 28 km.

NOAA Balloonsonde payloads include a NOAA Frost Point Hygrometer (FPH), an Electrochemical Concentration Cell (ECC) ozonesonde, and a radiosonde to telemeter data to the ground and provide in situ measurements of temperature, pressure, relative humidity (surface to upper troposphere), and GPS coordinates. Sounding data typically reach an altitude of 28 km.

The NOAA Balloon-borne Frost Point Hygrometer is based on the chilled mirror principle. The FPH measures the temperature of a small mirror controlled to maintain a constant, thin layer of frost. Under stable conditions the mirror temperature equals the frost point temperature of the air passing over the mirror. The frost coverage on the mirror is detected by a photodiode that senses the light of a light-emitting diode (LED) reflected off the mirror surface. Both optical components are rigorously temperature controlled, minimizing drift in the LED's intensity and the photodiode's sensitivity. The reflectance signal is used to control the temperature of the mirror using P-I-D logic. The mirror temperature is measured by a well-calibrated bead thermistor. The mirror temperature is telemetered to the ground station (along with a large array of other data) by a radiosonde that also provides in situ measurements of ambient temperature, pressure, relative humidity (only in the lower and middle troposphere), and GPS coordinates.

The Cloud Droplet Probe (CDP), manufactured by Droplet Measurement Technologies, measures the concentration and size distribution of cloud droplets in the size range from 2-50 µm. The instrument counts and sizes individual droplets by detecting pulses of light scattered from a laser beam in the near-forward direction, using a sample area of 0.24 mm2 or a sample rate of 48 cm3 at a flight speed of 200 m/s. The probe is mounted in an underwing canister and is designed to operate at up to 200 m/s; the G-V often exceeds this flight speed, but usually not in penetrations of clouds containing cloud droplets. Droplet sizes are accumulated in 30 bins with variable sizes, as specied in the header of the netCDF data files. Measurements are usually provided at a rate of 1 Hz in the standard data files but can be made available at 10 Hz in special high-rate processing. The instrument is similar to, and might be considered a high-speed replacement for, the Forward Scattering Spectrometer Probe. At high droplet concentration (> 500 cm-3), coincidence losses have been observed with this probe, and these are especially serious at G-V flight speeds. The probe is designed for cloud droplets, and its response to ice crystals is not intended to be quantitative; measurements in ice clouds should not be used except as qualitative indications of cloud.