ER-2 809
Associated content: 

Lyman Alpha-Hygrometer


Instrument: Lyman Alpha-Hygrometer

Principal Investigator: Ken Kelly

NOAA/ERL/Aeronomy Laboratory
325 Broadway MS R/E/AL6
Boulder, CO 80303

Principle of Operation: A 121.6 nm light source dissociates a fraction of the water and forms excited hydroxyl radicals. These radicals will either fluoresce at 309 nm or be quenched by air molecules. A PMT measures the 309 nm light, which is proportional to the water vapor mixing ratio. A photodiode monitors the 121.6 nm intensity at the same distance as the sample chamber center. An in-flight calibration is obtained from the measured absorption of 121.6 nm light by injected water vapor, the known absorption cross section and the chamber pressure. The hygrometer will measure total water.

Accuracy: 6%
Detection Limit: 0.1 ppmv
Response Time: 1 Second
Location on ER-2: Q-Bay

Reference: Kley, D., A. Schmeltekopf, K. Kelly, R. Winkler, T. Thompson, M. McFarland. "The U-2 Lyman-Alpha results from the 1980 Panama Experiment." The 1980 Stratospheric-Tropospheric Exchange Experiment. Ed: A.P.Margozzi. NASA Technical Memo 84297 (1983): 85-125.



Point(s) of Contact: 

FSSP-300 Aerosol Spectrometer

Instrument: FSSP-300 Aerosol Spectrometer


Principal Investigator: Guy V. Ferry



NASA-Ames Research Center

M.S. 245-5

Moffett Field, CA 94035-1000


Principal Investigators: James E. Dye (303) 497-8944 Darrel Baumgardner (303) 497-1054 FAX (303) 497-8181 Organization: National Center for Atmospheric Research 1850 Table Mesa Drive Boulder, Co 80307 Principle of Operation: The Forward Scattering Spectrometer Probe (FSSP) Model 300 sizes particles by measuring the amount of laser light scattered from angles of 4 to 12&degree; by aerosol particles in situ as they pass through a focused laser beam. Comparison of voltage outputs from the signal detector and a masked slit detector is used to electro-optically define the sample area. Fig. 1 shows the configuration of the instrument. The instrument system is composed of two parts: (l) a Particle Measuring Systems model FSSP-300 aerosol spectrometer, and (2) a data acquisition and recording system. The FSSP-300 aerosol spectrometer is located on the front of the starboard spear pod of the ER-2. The data acquisition and recording system is part of the package that houses the FPCAS aerosol spectrometer located in the bottom, rear portion of the starboard spear pod of the ER-2. The FSSP-300 aerosol spectrometer sizes particles in the 0.4 to 20 micron diameter size range (depending on the refractive index of the aerosol particles measured) in the free air stream outside the ER-2. The measured particles are divided into 31 size intervals with more resolution at smaller sizes.


Detection Limit: 0.4 to 20 micrometers diameter Sampling Rate: 0.1 Hertz Location on ER-2: Nose of right pod. Reference: Baumgardner, D., et al. ~Interpretation of Measurements made by the FSSP-300 during the Airborne Arctic Stratosphenc Expedition." J. Geophys. Res. In press. 1992.


Reactive Nitrogen

Instrument: Reactive Nitrogen

Principal Investigator: David W. Fahey

NOAA Aeronomy Laboratory
325 Broadway,R/E/AL6
Boulder, CO 80303

Principle of Operation:
The instrument is designed to measure nitric oxide (NO) and the sum of reactive nitrogen oxides (NOy). Species included in NOy are NO, NO2, HNO3, N2O5 and ClONO2. 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 (CO) acting as a reducing agent. The catalyst is located outside the aircraft fuselage in order to avoid inlet line losses. Two reaction vessels are incorporated in the instrument to allow for simultaneous measurement of NO and NOy. Ca1ibration with NO or NO2 is made by standard addition several times during a flight. The baseline of each measurement is determined in part by the addition of synthetic air that contains no reactive nitrogen. The difference between the sample flow velocity in the inlet opening and the aircraft velocity cause aerosol particles in the atmosphere to be oversampled. For sizes below 5 micrometers in diameter, this feature assists in the identification of aerosol particles that contain NOy.



Accuracy: < 20% plus precision
Detection limit: < 0.1 ppbv NOy, ~0.02 ppbv NO
Response time: 1 sec
Location on the ER2: Lower Q-bay rack

Reference: D.W. Fahey et al., In situ aerosol measurements of total reactive nitrogen, total water, and aerosol in a polar stratospheric cloud in the Antarctic, J. Geophys. Res. 94 11-99-11315, 1959.

Point(s) of Contact: 

Research Scanning Polarimeter

In order to demonstrate the capabilities of polarimetry an instrument that can make either ground-based, or aircraft measurements, the Research Scanning Polarimeter (RSP) has been developed by SpecTIR Corporation. This instrument has similar functional capabilities to the proposed EOSP satellite instrument. The picture above shows the assembled RSP instrument with its liquid nitrogen dewar on the left side and scanner assembly on the right. Currently data acquisition is performed on a laptop, which is shown here and gives an indication of the size of the instrument. The scientific requirements for the polarimetric measurements are satisfied by the RSP through its high measurement accuracy, the wide range of viewing angles measured and by sampling of the spectrum of reflected solar radiation over most of the radiatively significant range. The RSP instrument uses a polarization compensated scan mirror assembly to scan the fields of view of six boresighted, refractive telescopes through ±60° from the normal with respect to the instrument baseplate. The refractive telescopes are paired, with each pair making measurements in three spectral bands. One telescope in each pair makes simultaneous measurements of the linear polarization components of the intensity in orthogonal planes at 0° and 90° to the meridional plane of the instrument, while the other telescope simultaneously measures equivalent intensities in orthogonal planes at 45° and 135°. This approach ensures that the polarization signal is not contaminated by uncorrelated spatial or temporal scene intensity variations during the course of the polarization measurements, which could create false polarization. These measurements in each instantaneous field of view in a scan provide the simultaneous determination of the intensity, and the degree and azimuth of linear polarization in all nine spectral bands.

Instrument Type: 
Point(s) of Contact: 

Enhanced MODIS Airborne Simulator

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

Instrument Type: 
Point(s) of Contact: 

Advanced Whole Air Sampler

50 samples/flight

New control system

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

Instrument Type: 
Point(s) of Contact: 

Cloud Lidar System

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

Instrument Type: 
Point(s) of Contact: 


Subscribe to RSS - ER-2 - AFRC