ER-2 - AFRC

The Enhanced MODIS Airborne Simulator (EMAS) is a multispectral scanner configured to approximate the Moderate-Resolution Imaging Spectrometer (MODIS), an instrument orbiting on the NASA Terra and Aqua satellites. MODIS is designed to measure terrestrial and atmospheric processes. The EMAS was a joint development project of Daedalus Enterprises, Berkeley Camera Engineering, the USU Space Dynamics Laboratory, and Ames Research Center. The EMAS system acquires 50-meter spatial resolution imagery, in 38 spectral bands, of cloud and surface features from the vantage point of the NASA ER-2 high-altitude research aircraft.

Instrument Type: Multispectral Imager
Measurements: VNIR/SWIR/LWIR Imagery

The HIAPER Airborne Radiation Package (HARP) instrumentation is a comprehensive atmospheric radiation suite to measure spectrally resolved actinic flux and horizontally stabilized irradiance. HARP was developed in a collaborative effort between NCAR, the University of Colorado, the Leibniz-Institute for Tropospheric Research, Metcon, Inc and Enviscope GmbH. The package is part of the HIAPER Aircraft Instrumentation Solicitation (HAIS), funded by NSF.

Many changes from the original Chlorine Nitrate instrument. NO2 instrument removed. New inlet with orifice for one halogen duct, addition of vacuum scroll pump, new RF oscillators and amplifiers, new RF frequency, new lamp housings and cooling for lamp modules. Flew in MACPEX without dissociation heaters, i.e., focus on BrO and ClO measurements and not measure ClONO2 or ClOOCl.

32 samples/flight (ER-2); 50 samples/flight (WB57); 90 samples/flight (Global Hawk)

Updated control system with remote control capability

Fill times
–14 km 30 – 40 sec
–16 km 40 – 50 sec
–18 km 50 – 60 sec
–20 km 100 – 120 sec (estimated)

Analysis in UM lab: GC/MS; GC/FID; GC/ECD

The CLS is flown on the ER-2 to conduct cloud radiation and severe storm field experiments. Designed to operate at high altitudes in order to obtain measurements above the highest clouds, the instrument provides the true height of cloud boundaries and the density structure of less dense clouds. The height structure of cirrus, cloud top density and multiple cloud layers may also be profiled. The system specifications are as follows:

Laser Type: Nd:YAG I,II
Wavelength: 1064, 532 nanometer
Pulse Energy: 90, 30 mJ
Pulse repetition frequency: 10 Hz
Beam width: 1 mrad

Diameter: 0.15 m
Beam width: 1.4 mrad
Polarization: vert. and horiz.

Sample rate: Measurements at 20 m intervals at 200 m/s aircraft speed
Range Resolution: 7.5 m
Number of Channels: 4
Samples per Channel: 3310
Record Capacity: 8 hours

HIWRAP (High-Altitude Imaging Wind and Rain Airborne Profiler) is a dual-frequency radar (Ka- and Ku-band), dual-beam (300 and 400 incidence angle), conical scan, solid-state transmitter-based system, designed for operation on the high-altitude (20 km) Global Hawk UAV. HIWRAP characteristics: Conically scanning; Simultaneous Ku/Ka-band & two beams @30 and 40 deg; Winds using precipitation & clouds as tracers; Ocean vector wind scatterometry; Map the 3-dimensional winds and precipitation within hurricanes and other severe weather events; Map ocean surface winds in clear to light rain regions using scatterometry.

Measures concentration and records images of cloud particles from approximately 50-1600 microns in diameter with a resolution of 25 microns per pixel. Measures cloud droplet and aerosol concentrations within the size range of 0.5-50 microns.

The three DMT instruments included in the CAPS are the Cloud Imaging Probe (CIP), the Cloud and Aerosol Spectrometer (CAS), and the Hotwire Liquid Water Content Sensor (Hotwire LWC).

The CIP, which measures larger particles, operates as follows. Shadow images of particles passing through a collimated laser beam are projected onto a linear array of 64 photodetectors. The presence of a particle is registered by a change in the light level on each diode. The registered changes in the photodetectors are stored at a rate consistent with probe velocity and the instrument’s size resolution. Particle images are reconstructed from individual “slices,” where a slice is the state of the 64-element linear array at a given moment in time. A slice must be stored each time interval that the particle advances through the beam a distance equal to the resolution of the probe. Optional grayscale imaging gives three levels of shadow recording on each photodetector, allowing more detailed information on the particles.

The CAS, which measures smaller particles, relies on light-scattering rather than imaging techniques. Particles scatter light from an incident laser, and collecting optics guide the light scattered in the 4° to 12° range into a forward-sizing photodetector. This light is measured and used to infer particle size. Backscatter optics also measure light in the 168° to 176° range, which allows determination of the real component of a particle’s refractive index for spherical particles.

The Hotwire LWC instrument estimates liquid water content using a heated sensing coil. The system maintains the coil at a constant temperature, usually 125 °C, and measures the power necessary to maintain this temperature. More power is needed to maintain the temperature as droplets evaporate on the coil surface and cool the surface and surrounding air. Hence, this power reading can be used to estimate LWC. Both the LWC design and the optional PADS software contain features to ensure the LWC reading is not affected by conductive heat loss.

The Unmanned Aircraft Systems (UAS) Chromatograph for Atmospheric Trace Species (UCATS) was designed and built for autonomous operation on remotely piloted aircraft, but has also been used on manned aircraft. It uses chromatography to separate atmospheric trace gases along narrow heated columns, followed by precise and accurate detection with electron capture detectors. There are currently three chromatography channels on UCATS, which measure nitrous oxide (N2O) and sulfur hexafluoride (SF6); CFC-11, CFC-12, CFC-113, and halon 1211; and chloroform (CHCl3) and carbon tetrachloride. On an earlier version of UCATS, with only two channels, we also measured methane, hydrogen, and carbon monoxide, along with N2O and SF6. In addition, there is a small ozone instrument and a tunable diode laser instrument for water vapor. Gas is pumped into the instruments from an inlet outside the aircraft, measured, and vented. UCATS has flown on the Altair UAS, the GV during HIPPO, the NASA Global Hawk UAS during the Global Hawk Pacific (GloPac) and ATTREX missions, where a record was set for the longest duration research flight (more than 28 hours), the DC-8 for ATom, and the ER-2 for DCOTSS. UCATS is relatively lightweight and compact, making it ideal for smaller platforms, but it is easily adaptable to a mid-size platform like the GV or Global Hawk. The data are used to measure sources and sinks of trace gases involved in climate and air quality, as well as transport through the atmosphere.

UCATS is three different instruments in one enclosure:

1. 3-channel (formerly 2-channel, up until 2020) gas chromatograph (GC)
2. Dual-beam ozone photometer (OZ)
3. Tunable diode laser (TDL) spectrometer for water vapor (WV)

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