The Anatomy of an ER-2 Aircraft - Site Equipe Taperá

The Anatomy of an
ER-2 Aircraft
•Instrumentation
•Observation
•Experimentation
By Cerese Albers

The ER-2 helps with the TCSP
missions objectives:
TCSP research will address the following
topical areas:
1) tropical cyclone structure, genesis, intensity
change, moisture fields and rainfall;
2) satellite and aircraft remote sensor data
assimilation and validation studies pertaining to
development of tropical cyclones; and
3) the role of upper tropospheric/lower
stratospheric processes governing tropical
cyclone outflow, the response of wave
disturbances to deep convection and the
evolution of the upper level warm core.

The ER-2
typically
operates at
altitudes above
65,000 feet,
above 95
percent of the
earth's
atmosphere,
allowing the
aircraft to use
many of the
same sensors
similar to those
used by
orbiting
satellites.
Two ER-2s fly over The Golden Gate Bridge, San Francisco CA
The ER-2 High Altitude Research Aircraft carries a
single pilot and up to 2600 pounds of payload to
altitudes approaching 70,000 feet. It is a modified
version of the U-2 aerial reconnaissance airplane.

A typical mission lasts up to six-and-one-half hours and covers 2,200 nautical
miles. Under certain conditions, it is possible to extend this to eight hours and
3,000 nautical miles. The maximum-altitude mission profile involves a steady
climb from 60,000 feet to 70,000 at a constant mach number.
View out the window of the ER-2 near max altitude

The ER-2 is equipped with an Inertial Navigation System that can
get position updates from an on-board GPS receiver. It also has a
data recording and distribution system that records aircraft
performance and navigation data and distributes it to each of the
payload areas. The ER-2 core instruments include:
•Daedalus multi-spectral scanners with the following
configurations:
•Thematic Mapper Simulator
•Multi-spectral Airborne Mapping System
•Airborne Ocean Color Imager
•MODIS Airborne Simulator
•Three types of aerial cameras that provide high-resolution
photography at several scales and resolutions
•A video imaging system.

Anatomy of the ER-2 Aircraft
Named parts of the plane

The ER-2 is equipped with UHF, VHF, and HF radio
systems for two-way voice communication. An Air Traffic
Control (ATC) transponder enables surveillance radar to
identify the aircraft via coded transmissions.
The ER-2 can navigate with respect to ground based
radio beacons, as selected by the pilot. Navigation aids
used for this include: low-frequency Automatic Direction
Finding (ADF), Tactical Air Navigation (TACAN) for
bearing and range information, and a VHF
Omnidirectional Range/Instrument Landing System
(VOR/ILS).
Inertial Navigation Systems
The Inertial Navigation System (INS) on the ER-2
operates by sensing accelerations from a gyro-stabilized,
all-attitude platform. This information is integrated by a
digital computer to provide an indication of present
position (latitude and longitude), attitude data (pitch and
roll), and course line computation referenced to great
circle routes. A control display unit in the cockpit allows
the pilot to store navigation way points and to change the
flight track enroute. A self-contained system, the INS
offers world-wide navigation capability.
An update function allows for GPS updating of the INS to
provide navigation independent of the drift errors.

Anatomy of the ER-2 Aircraft

Instruments onboard the TCSP
ER-2 Aircraft
• Advanced Microwave Precipitation Radiometer (AMPR)
• Cloud Radar System (CRS)
• ER-2 Doppler Radar (EDOP)
• High Altitude MMIC Sounding Radiometer (HAMSR)
• Lightning Instrument Package (LIP-ER-2)
• Microwave Temperature Profiler (MTP -ER-2)
• MODIS Airborne Simulator (MAS)
• Research Environment for Vehicle-Embedded Analysis on
Linux (REVEAL)

INTRODUCTION TO THE INSTRUMENTS ONBOARD THE ER-2
Undercarriage of an ER-2 in flight

Advanced Microwave Precipitation Radiometer (AMPR)
Type: Passive Microwave Radiometer
Principal Investigator: Robbie Hood
Co-Investigators: Daniel Cecil, Frank LaFontaine
•Temporal Resolution: 50 milliseconds per sample
Spatial Resolution: sampling, 800 meters at 20 km altitude
85.5 GHz, 640 meters at 20 km altitude
•In-Field Quick Look Products: Brightness Temperatures (TB)
Direct Products: TB data (swath) and imagery (swath and grid)
Derived Products: Precipitation Index
Potential Products: Instantaneous rain rate, inland/coastal surface water
mapping
•Preferred Atmospheric Conditions: Over cloud-free ocean near a radiosonde
launch site/time and AMSR-E overpass location/time
•Desired Data Sources: radiosonde data sets, passive microwave satellite
images, radar images, visible and infrared satellite images

Cloud Radar System (CRS)
Type: Radar
Principal Investigator: Gerry Heymsfield
Co-Investigator(s): Lihua Li, Lin Tian, Larry Belcher
•Temporal Resolution: 0.5 sec
Spatial Resolution: 0.15 km at surface
•In-Field Quick Look Products: Quick-look reflectivity and velocity plots for
selected flight lines.
Direct Products: Reflectivity, Doppler velocity, and spectral width from
nadir and forward beams in Universal Format. Software
readers for IDL will be provided.
Derived Products: Ice content.
Potential Products: Vertical velocities, path attenuation, surface
backscatter
•Preferred Atmospheric Conditions: Clear or clouds for hurricanes.
Desired Data Sources: All

ER-2 Doppler Radar (EDOP)
Type: Radar
Principal Investigator: Gerry Heymsfield
Co-Investigator(s): Lihua Li, Lin Tian, Larry Belcher
•Temporal Resolution: 0.5 sec
Spatial Resolution:: 1.1 km at surface; ~250 m at 15 km altitude
•In-Field Quick Look Products: : Quick-look reflectivity and velocity plots for
selected flight lines.
Direct Products: Reflectivity, Doppler velocity, and spectral width from
nadir and forward beams in Universal Format. Software
readers for IDL will be provided.
Derived Products: Rain-rate, ice content.
Potential Products: Vertical velocities, rain rate, path attenuation, surface
backscatter
Preferred Atmospheric Conditions: Clear or clouds for hurricanes
•Desired Data Sources: All

EDOP antennae
EDOP schematic in the nose of the ER-2

ER-2 EDOP
Functionality
•Each Antenna measures the doppler velocity, doppler spectral width, and
reflectivity factor.
•Doppler velocities provide a measure of the pulse volume-weighted hydrometer
motion (hydrometer fallspeed + air motion.)
•Vertical air motion can be calculated from the nadir beam by removing the
fallspeed contribution with an approximation
•Along-track horizontal air motion can be calculated by combining doppler wind
speeds from forward and nadir beams.
•The linear depolarization ratio (the ration of the cross-polar to the co-polar
reflectivites) can be measured along forward beam.

High Altitude MMIC Sounding Radiometer (HAMSR)
Type: Radiometer
Principal Investigator: Bjorn Lambrigtsen
Co-Investigator(s): Alan Tanner, Evan Fishbein, Eric Fetzer
•Temporal Resolution: 1.1 sec
Spatial Resolution: 6 deg IFOV, 3 deg. sample cell (2 km, 1km, at
nadir from 20 km)
•In-Field Quick Look Products: Preliminary calibrated brightness temperatures
Direct Products: Definitive calibrated brightness temperatures
Derived Products: a) temperature profiles b) humidity profiles
Potential Products: a) liquid water profiles b) scattering parameters c) rain rates
Desired Data Sources: a) radiosondes b) surface temperature & sea state
c) high resolution GCM forecast/analysis d) Aqua AIRS and AMSR-E (observations
and retrievals) e) NOAA-16/17 AMSU-A/B (observations and retrievals) f) GOES
images

Lightning Instrument Package (LIP-ER-2)
Type: Electric Field Mills, Conductivity Probe
Principal Investigator: Richard Blakeslee
Co-Investigator(s): Monte Bateman, Doug Mach
•Temporal Resolution: 10 Hz
Spatial Resolution: ~20m
•In-Field Quick Look Products: Quick looks at atmospheric conductivity, electric
field components, and aircraft charge
Direct Products: Atmospheric conductivity, electric field components, and
aircraft charge
Derived Products: Total lightning count & rates; lightning statistics; storm
current output, storm charge structure
Potential Products: Quantified lightning related with precipitation, convective
mass/ice flux, latent heat, storm current output
•Desired Data Sources: Passive microwave, aircraft Radar, in-situ
Microphysics (NOAA P3s), TRMM observations, ground-based lighting (Costa Rican
and long-range NLDN

Microwave Temperature Profiler (MTP- ER-2)
Type: Microwave Radiometer
Principal Investigator: M.J. Mahoney
•Temporal Resolution: 10s(ER-2)
Spatial Resolution: 2km
•In-Field Quick Look Products: Uncalibrated curtain plots of temperature field
along flight track
Direct Products: Temperature profiles along flight track
Derived Products: Tropopause height, lapse rate at aircraft, theta at
aircraft
Potential Products: : Isentrope fields
•Preferred Atmospheric Conditions: Clear air
•Desired Data Sources: sondes

MODIS Airborne Simulator (MAS)
Type: Imaging Spectrometer
Principal Investigator: Jeff Myers
Co-Investigator(s): Roseanne Dominguez
•Temporal Resolution: Data collected continuously at 6.25 scans per second during
ER-2 flight (at altitude)
Spatial Resolution: 50 meter pixels at nadir at 15 km altitude Swath width is 36 Km.
•In-Field Quick Look Products: Quick-look (Level-0) JPEG images of straight and
level flight line tracks. Text file of Nadir brightness temperature and radiance for
selected bands
Direct Products: Level-1B multispectral visible and infrared imagery calibrated to atsensor
radiance.
Derived Products: To be determined
Potential Products: To be determined
•Preferred Atmospheric Conditions: Clear or clouds for hurricanes
•Internet access: Required for field workstations & posting quick look products

Research Environment for Vehicle-Embedded Analysis on Linux (REVEAL)
Type: Generic Instrument Interface and Investigator support package
Principal Investigator: Lawrence C. Freudinger
Co-Investigator: Carl E. Sorenson
•Temporal Resolution: Multiple products simultaneously at different rates (typically
10 Hz, 1Hz, & 0.1Hz process rates)
•In-Field Quick Look Products: Quick looks at vehicle state, fuel temperature
monitoring, various environmental parameters.
Direct Products: Vehicle data bus interfaces, vehicle time-space-position information,
sun angle calculations, and custom real-time and post-flight data products. Provides
real-time data feeds to LIP displays and TCSP Team.
Potential Products: Generic instrument interface for vehicle state data and onboard
compute services. Disruption tolerant gateway for managing multiple data links; onboard
recorder service; dynamically configurable on-board computing; Sensor Web
development and support.
•Miscellaneous: Providing real-time and post-flight mission support items for TCSP
as part of research objective.

ER-2 used to validate the TRMM satellite
The vertical velocities from wind fields are used to validate TRMM's algorithms for
separation of convective from stratiform rainfall (using EDOP). This needs
complementing with a network of tipping bucket rainfall gauges. For TRMM purposes
the ER-2 is made available, and a microphysics plane is also needed (which can be
the ER-2). Lightning detectors (3) are also needed to correlate rainfall with lightning,
like the LIP.
NASA's ER-2 and DC-8 collect high-altitude
thunderstorm rainfall and lightning
measurements. Information gathered from the
mission helps calibrate measurements from the
rainfall measuring satellite (TRMM-related).

Therefore, note that the EDOP radar and
the LIP are the primary sensors used to
calibrate the TRMM satellite.
In the past, the MAS instrument aboard the ER-
2 has been used to calibrate the GOES and the
AVHRR radiance measurements as well.