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ER-2 Instruments

This page lists and briefly describes the investigator-sponsored instruments currently operating aboard the ER-2. More complete information on a particular sensor can be obtained from the principal investigator. For information on "core" instruments (those operated and maintained by NASA Dryden), as well as film cameras, see the main list of ER-2 sensors or contact the Airborne Science Branch.

Index of Instruments

Investigator Sponsored Sensors

Airborne Chromatograph For Atmospheric Trace Species (ACATS)

ACATS is designed to measure a variety of organic chlorine and long-lived species in the stratosphere and upper troposphere. The instrument includes four separate gas chromatographic (GC) channels each incorporating an electron capture detector. Channels can be configured by selecting different GC columns to measure the following combination of individual trace gas species: CFC-11 and CFC-113; CH3CCl3 (MC) and CCl4 (CT); CFC-12 and N2O; or HCFC-22, CH3Cl, or hydrogen, methane and carbon monoxide. The gas chromatograph can measure one sample every 2-3 minutes with a detection limit of 2% of the maximum tropospheric value. The absolute accuracy of the measurement is +/- 3% plus precision.

This research is supported by the High Speed Research Program (HSRP) of NASA and the Atmospheric Chemistry Project of NOAA's Global Climate Change Program. For more information, try the ACATS home page, or contact the principal investigator for ACATS is Dr. James Elkins, of the NOAA Climate Monitoring and Diagnostics Laboratory. Index

Aircraft Laser Infrared Absorption Spectrometer (ALIAS)

ALIAS is a very high resolution scanning tunable diode laser spectrometer designed to make direct, simultaneous measurements to nitrous oxide, nitric acid, hydro-chloric acid, methane, and either ozone or N2O, in the polar stratosphere at sub-part per billion level sensitivities over a 3-30 sec integration period.

The principal investigator for ALIAS is Dr. Chris Webster at NASA's Jet Propulsion Laboratory. Index

Advanced Microwave Precipitation Radiometer (AMPR)

AMPR is a scanning passive microwave radiometer operation at frequencies of 10, 19, 37, and 85 GHz. AMPR scans cross track +/- 45 degrees left and right of nadir. This instrument is primarily used to gather microwave image data ofcloud water and precipitation over the ocean.

For more information on AMPR, try the AMPR home page or contact Dr. Roy Spencer of NASA's Marshall Space Flight Center. Index

Aerosol Particulate Sampler(APS)

The APS is a passive sensor designed to gather high altitude dust particles for laboratory research. An APS paddle is deployed from a wingtip pod into stratosphere once the ER-2 has reached cruising altitude, and is retracted before descent. Both wire impactor and oil-film paddles are used. After approximately 40 hours of exposure, the sealed units are returned to the investigator for examination by an electron microscope, The returned particles can be the by-products of meteor decomposition in the upper atmosphere, or the products of massive volcanic eruptions.

For further information about the APS, contact Dr. Guy Ferry of NASA-Ames, or Dr. Jack Warren of NASA-Johnson Space Center. Index

Airborne Tunable Laser Absorption Spectrometer (ATLAS)

ATLAS uses a tunable laser to detect a target gas such as N2O, methane, carbon monoxide, or ozone. The laser source is tuned to an individual roto-vibrational line in an infrared absorption band of the target gas, and is frequency modulated at 2 kHz. The instrument detects the infrared target gas by measuring the fractional absorption of the infrared beam from the tunable diode laser.

The principal investigator for the ATLAS system is Dr. Max Loewenstein of NASA-Ames. Index

Cloud Lidar System(CLS)

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

For more information on the Cloud LIDAR System, try the CLS home page or call the principal investigator for CLS, Dr. James Spinhirne at NASA's Goddard Space Flight Center. Index

Condensation Nucleus Counter (CNC)

There are two CNCs which have been developed to operate on the ER-2. The first measures the number concentration of aerosol particles having diameters in the 0.01 to about 1.0 micron range. The second uses a heated (150 deg. C) inlet to vaporize volatile components and then measure the number concentration of residue particles. When used together, the CNCs discriminate between particles containing components that are non-volatile at temperatures of 150 deg. C. Twenty-five samples per flight are collected.

For further Information on the CNC, contact Dr. James C. Wilson of the University of Denver. Index

Harvard Carbon Dioxide Experiment (Harvard CO2)

This instrument consists of a non-dispersive infrared analyzer tuned to 4.26 microns, corresponding to the asymmetric stretch of carbon dioxide. To determine the concentration of carbon dioxide, the difference in absorption between a sample of stratospheric air passed through a sample cell to that of a gas of a known concentration is measured.

Information on the Harvard CO2 experiment can be obtained from Dr. Kristie Boering of Harvard University. Index

Composition and Photo-Dissociative Flux Measurement (CPFM)

CPFM is a spectral-radiometer based on a concave, holographic diffraction grating and a 1024-element diode array detector. It measures the intensities of the two linear polarization components of radiation propagating upward at the aircraft location, and from a range of elevation angles near the horizon.

The principal investigator for CPFM is Dr. C. Thomas McElroy, Atmospheric Environment Service, Environment Canada. Index

ER-2 Doppler Radar (EDOP)

EDOP is an X-band fully-coherent pulsed Doppler radar. EDOP measures the vertical reflectivity and wind structure of mesoscale precipitation systems. The data obtained by EDOP can be used to test and validate satellite based precipitation estimation algorithms. EDOP consists of one pitch-stabilized nadir pointing radar beam, and one forward pointing beam. This allows for mapping of time height sections of reflectivity and Doppler winds within the precipitation region from which vertical air motions can be obtained. In addition, the forward beam measures linear depolarization ratio (LDR), which provides useful information on the cloud micro-physical properties. The characteristics of EDOP are as follows:

Frequency / Wavelength: 9.72 GHz / 3.07 cm
Peak Transmit Power 20 kW
Pulse Repetition Frequency 2.2 of 4.4 kHz
Pulse Widths/Range Resolution 0.25, 1.0 micro-sec / 37.5, 150 m
Antenna Beam Widths 2.9 deg

The data system for the EDOP system consists of data acquisition from three logarithmic and four linear channels. Raw data rates in the Doppler mode are approximately 60 megabytes/sec. This information is processed on-board resulting in data storage of about 100 kilobytes/sec.

For further information on EDOP contact Dr. Gerry Heymsfield of NASA-GSFC. Index

Focused Cavity Aerosol Spectrometer (FCAS)

FCAS counts and sizes aerosol particles by measuring the amount of light scattered as they pass through a laser beam. The instrument consists of a sampling inlet, a Particle Measuring model Focused Cavity Aerosol Spectrometer, and a data acquisition and recording system.

The Principal investigator for the FCAS is Dr. Guy V. Ferry at NASA-Ames. Index

High Resolution Interferometer Sounder (HIS)

The ER-2 High Resolution Interferometer Sounder (HIS) is a Michelson interferometer which measures the upwelling nadir radiance within the 3.5 to 17 micron region of the spectrum. The primary use of the instrument is as an atmospheric sounder of temperature and water vapor. The spectra also contain important information of trace gases and surface properties. The upwelling radiance spectrum, defined by 4000 independent spectral elements, is observed every 6 seconds with a spatial resolution of 2 km (along the flight track of the ER-2). Spectral resolution is approximately 0.5 cm-1 from 600-1100 cm-1 (9.1-16.7 micron) and 1.0 cm-1 resolution from 1100-2700 cm-1 (3.7-9.1 micron). The instrument possesses an inflight calibration facility to provide absolute accuracies of better than 0.5K and the instrument noise is about 0.25K when viewing standard surface temperature scenes. Reduced noise level spectra are achieved by co-adding a time sequence of the 6 second interval measurements.

The HIS was developed by the University of Wisconsin at Madison and is a prototype instrument for advanced infrared satellite sounders. Further information on HIS can be obtained from the HIS home page, or from Dr. William Smith, University of Wisconsin.

Dr. William Smith
1225 West Dayton St.
Madison, WI 53706
ph: (608) 264-5325 Fax: (608) 262-5974


Harvard Hydroxyl Experiment (HOx)

In order to detect stratospheric OH, air is channeled into the instrument using a double-ducted system that both maintains laminar flow throughout the detection region as well as slowing the flow from free stream velocity (200 m/s) to 40 m/s. Laser light is then beam split and directed to two detection axes where it passes through the stratospheric air in multipass white cells. Fluorescence from the OH (centered at 309 nanometer) is detected orthogonal to both the flow and the laser propagation using a filtered PMT assembly.

The principal investigator for HOx is Dr. Paul Wennberg of Harvard University. Index

Harvard Ozone Experiment (O3)

The Harvard ozone instrument, flown with HOx, determines ozone cross section by measuring the absorption of 253.7 nanometer radiation. Ambient air is alternately drawn through a scrubber that chemically removes ozone and through a Teflon inlet tube. The absorption signal is measured with ozone scrubbed air, and then with ambient air flowing through the detection cell. The ozone concentration is then determined by comparing the ratio of the two absorption signals.

The principal investigator for the Harvard Ozone Experiment is Dr. Paul Wennberg of Harvard University. Index

Large Area Collectors (LAC)

The Large Area Collectors are flown on the ER-2 in support of the NASA-Johnson Space Flight Center Cosmic Dust Program. The LACs are used to collect comparatively unaltered cosmic dust from the stratosphere at ER-2 flight altitudes of 65,000 feet and above. Sufficient quantities of extraterrestrial materials are collected to allow chemical and mineralogical compositions of individual particles to be determined. Study of these materials whose sources may be comets, asteroid collisions, planetary impacts, and meteorite ablation provide valuable information about the origin and the history of the solar system.

The principal investigator for cosmic dust collection is Dr. Mike Zolensky, NASA-Johnson Space Center, Houston TX. Index

Lidar Atmospheric Sensing Experiment (LASE)

The LASE instrument is an autonomous differential absorption LIDAR (Light Imaging Detecting And Ranging) system that measures vertical concentration profiles of water vapor and aerosols in the troposphere. LASE characteristics are summarized below:

Pulse Repeated Frequency 2.2 of 4.4 kHz
Energy: 150 Mega-Joules
Line width: 1.1 pm
Repetition rate: 5 Hz
Wavelength: 726.5 - 732.0 nanometer
Beam Divergence: 0.73 milli-radians
Pulse Width: 300 nano-seconds

Effective Area: 0.11 square meters
Field-of-View: 1.23 milli-rad
Filter Bandwidth: 0.4 nanometers (day)

LASE is sponsored by NASA's Langley Research Center. For more information on LASE, try the LASE home page or contact the principal investigator for LASE, Dr. Ed Browell. Index

Lightning Instrument Package (LIP)

The LIP is comprised of a set of optical and electrical sensors with a wide range of temporal, spatial, and spectral resolution to observe lightning and investigate electrical environments within and above thunderstorms. The instruments provide measurements of the air conductivity and vertical electric field above thunderstorms and provide estimates of the storm electric currents. In addition, LIP will detect total storm lightning and differentiate between intracloud and cloud-to-ground discharges. This data is used in studies of lightning/storm structure and lightning precipitation relationships.

LIP is sponsored by Dr. Richard Blakeslee, at NASA-MSFC. Index

Meteorological Measurement System (MMS)

The MMS measures pressure, temperature, wind vector, position (altitude, latitude, longitude), pitch, roll, heading yaw, angle of attack, angle of sideslip, true airspeed, aircraft eastward velocity, northward velocity, vertical acceleration and time. The MMS consists of three parts. These are: (1) The air motion sensing system to measure the velocity of the air with respect to the aircraft, (2) High resolution inertial navigation system to measure the velocity of the aircraft with respect to the Earth, and (3) A data acquisition system to sample, process and record the measured quantities.

Additional information on the MMS can be obtained from Dr. Roland Chan, at NASA-Ames. Index

Microwave Imaging Radiometer (MIR)

The Microwave Imaging Radiometer is a nine channel radiometer developed for atmospheric research. Three dual pass band channels are centered about the strongly opaque 183 Hz water absorption line and a fourth channel is located at 150 GHz. These four channels have varying degrees of opacity from which the water vapor profile can be inferred.

For more information on MIR, contact Dr. James Wang at NASA-GSFC. Index

Microwave Temperature Profiler (MTP)

The MTP uses a passive microwave radiometer to measure thermal emission from oxygen molecules for a selection of elevation angles. Altitude temperature profiles are obtained once every ten seconds. The profile applies to a volume of air that is approximately 3 km deep (along the flight path) by 3 km high (centered on aircraft altitude) and 1/4 km wide. The observing frequencies are 57.3 and 58.8 GHz. The relationship between ñbrightness temperature and elevation angle is converted to a plot of air temperature versus altitude. Lapse rate at the aircraft's altitude is later compared with horizontal gradients of wind speed to derive potential vorticity. Potential vorticity determinations are used to assign an origin to the air mass being flown through.

The MTP is sponsored by Bruce L. Gary at NASA's Jet Propulsion Laboratory, Pasadena, Ca. Index

MIT Millimeter-Wave Temperature Sounder (MTS)

The MTS is a dual-band microwave radiometer system for the measurement of atmospheric temperature and other phenomena affecting transmission in the microwave absorption bands of molecular oxygen. MTS data has been used to produce images of temperature and precipitation structure, to infer precipitation cell top altitudes and to detect atmospheric waves.

The instrument is capable of either downward or upward viewing operation on the ER-2 as well as ground based operation. One radiometer is an eight channel scanning spectrometer with its radiometer centered on the 118, 75 GHz oxygen line. The bands of the eight channel radiometer are:

Channel Center freq.(Mhz) Width (Mhz)
1 660 170
2 840 210
3 1040 240
4 1260 220
5 1470 240
6 1670 220
7 1900 270
8 500 125

The second radiometer is a single channel (ch.0) nadir (or zenith) viewing system with its local oscillator tunable under computer control from 52 to 54 GHz.

The principal investigator for MTS is Dr. Jack Barret of MIT. Index

NASA Aircraft Satellite Instrument Calibration

The NASA Aircraft Satellite Instrument Calibration is a scanner developed to calibrate research and operational instruments in orbit onboard NOAA and NASA satellites. The ASCS consists of a double Ebert Monochrometer. ASCS missions are flown coincident with satellite overpasses and fly the same view vector as the satellite instrument over a selected ground scene.

Sensor parameters are as follows:

Detector: Double Monochrometer w/Holographic Grating
Across Track FOV 8 degrees
Along track FOV 4 degrees
Ground Swath 1.5 x 0.75 nmi (2.8 x 1.4 km)
Spectral Range 400-1035 nanometers
Scans/Data collection leg 36 + 2 baseline housekeeping
Data Points/Scan line 184
Data point spectral range 3.5 nanometer

Further information regarding the NASA Aircraft Satellite Instrument Calibration project, contact Peter Abel of NASA-GSFC. Index

Reactive Nitrogen Experiment (NOy)

The NOy instrument is designed to measure nitric oxide (NO) and the sum of reactive nitrogen oxides (NOy). NO is measured by detecting light from the chemiluminescent reaction between reagent ozone and NO in the ambient sample. NOy is reduced to NO by catalytic reduction on a gold surface with carbon monoxide (carbon monoxide) acting as a reducing agent. The catalyst is located outside the aircraft in order to avoid duct losses.

Further information on this instrument can be obtained from Dr. David Fahey, NOAA Aeronomy Laboratory. Index

Quartz Crystal Microbalance/Surface Acoustic Wave (QCM/SAW)

QCM/SAW was developed to perform in-situ real time measurements of aerosols and chemical vapors in the stratosphere. The instrument is integrated into a fuselage centerline pod. The instrument is controlled by an embedded micro controller. The preset sampling sequence is triggered by a single command issued by the pilot. Using an air pump, samples are collected and decelerated in two stages to match the velocity requirement at the cascade impactor. Once the sample enters the cascade impactor, aerosols contained in the sample are separated into 8 size bands. The separated particles are collected on the surface of the piezoelectric microbalance crystals. The samples are analyzed post-flight.

For further information concerning QCM/SAW, or QCM data products, contact Dr. Arthur Thorpe, at Howard University. Index

Radiation Measurement System (RAMS)

RAMS is an integrated system of several radiometers. The system provides airborne measurements to support analysis and theoretical calculations of cloud properties and radiation fields and to provide validation of satellite radiance measurements.

The airborne instruments consist of the following:

  • An electrically calibrated pyro-electric radiometer for hemispherical, broad spectral bandpass, radiative flux measurements in the solar spectral region (0.26 to 2.6 microns). The radiometer has two detectors: an IR net flux radiometer (rotating) covering the spectral range from 5 to 40 microns; and a narrow field-of-view, narrow spectral bandpass IR radiometer (2 channels in the 5 to 40 microns region). This radiometer uses a liquid nitrogen cooled black body reference, and provides upwelling infrared intensities above clouds.
  • A total-direct-diffuse multi-channel narrow spectral bandpass (about 5 to 10 nanometer) flux radiometer. This radiometer is used for optical depth determinations and direct/diffuse ratios.

The principal investigator for RAMS is Dr. Francisco Valero, of Scripps Institute of Oceanography, University of California, San Diego. Index

Water Vapor Experiment (H2O)

The H2O experiment samples stratospheric air to study the water vapor mixture it contains. A 121.6 nanometer light source dissociates a fraction of the water contained in the air sample and forms excited hydroxyl radicals. These radicals will either fluoresce at 309 nanometers or be quenched by air molecules. A photo-multiplier tube measures the 309 nanometer light, which is proportional to the water vapor mixing ratio. A photo diode monitors the 121.6 nanometer intensity at he same distance as the sample chamber center. Inflight calibration is obtained from the measured absorption of 121.6 nanometer light by infected water vapor, the Known absorption cross section and the chamber pressure. The hygrometer measures total water.

The principal investigator for the H2O instrument is Ken Kelly, NOAA/ERL Aeronomy Laboratory, in Boulder, CO. Index

Whole Air Sampler (WAS)

WAS utilizes the National Center for Atmospheric Research's proven 1.6 liter stainless steel canisters and NASA's special 4-stage metal bellows pump to collect 29 samples of 4.5 standard liters. Collection time for each of the 29 samples is approximately three minutes per sample collected. Samples are analyzed post-flight using gas chromatography and mass spectrometric techniques. A major data product of the WAS is measurement of total organic chlorine (CCl).

WAS is sponsored by the National Center for Atmospheric Research, and the San Jose State University Foundation. The principal investigator for WAS is James Vedder, at NASA-Ames. Index

Harvard Water Ozone Experiment (WOX)

The Harvard University Water Ozone eXperiment is flown with the Harvard hydroxyl experiment (HOx) in the nose of the ER-2. The water vapor instrument uses the techniques of photo-fragment fluorescence combined with dual path absorption to measure water vapor concentrations ranging from 1013 to 1016 molecules/ at pressures from 50 to 500 millibars. The detection scheme utilizes Lyman-alpha photons (121.6 nanometer) to photo-dissociate water vapor and produce excited OH molecules, which emit photons that are detected by a photo-multiplier near 314 nanometers. Dual-path absorption measurements (path length 8.9 cm), which provide a self-consistent check in the laboratory, are carried out during the ascent and descent part of each ER-2 flight to verify the fluorescence calibration. In-flight diagnostics, such as periodically changing the air flow velocity, confirm that the water vapor measurements are not contaminated by the walls of the instrument.

The principal investigator for Harvard H2O is Dr. Elliot Kushner of Harvard University. Index

Comments and Suggestions?

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