Divisional Activities: Technology
In ATD, FY03 has seen extensive upgrades, improvements, overhauls and creation new state-of-the-art observing systems the global scientific community routinely depends upon for precise measurements and critical data that allows for deeper understanding of our atmospheric systems. This document outlines these changes in ATD's fleet of observing facilities, both the Ground-Based Observing Systems and Airborne Observing Systems, as well as the accomplishments in our Data Services and Design and Fabrication.
3) Developments in Ground-Based Observing Systems
Radars and Profilers
The 2nd frequency upgrade to the S-Pol radar is nearing completion. This addition consists of a .8 cm (35 GHz), 1 degree beamwidth Doppler radar with dual polarization capability. The antenna points congruently with the 10 cm S-band, both in space and time. Polarization configurations are: transmit horizontal-receive horizontal and vertical, and transmit both horizontal and vertical (45 deg) - receive horizontal and vertical. The former mode gives reflectivity and LDR, and the latter gives reflectivity, ZDR and PhiDp.
NCAR is developing a new processor named the Hi-Q. This is a relatively simple processor targeting the upgrading of foreign radars for field programs. The purpose of this board is to allow acquisition of research quality data from existing radars having limited capabilities. It is presently being prototyped at the UAE radar at Al Ain, and will be used on four radars in western Mexico for the NAME project.
NCAR continues to support the Rapid Dow development. The rapid Dow is an advanced truck mounted radar using a flat plate frequency steered beam. This system currently transmits and receives six simultaneous beams, effectively improving the volume scanning rate by a factor of six. Processing is done using NCAR PIRAQ III processors. So far the radar has acquired data for tornado studies and hurricane eyewall studies.
The venerable CP-2 radar has been moved to Australia and awaits set up. After an extensive refurbishment in Boulder the radar will be set up near Brisbane and operate continuously for the Australian BOM. CP-2 is a dual frequency, dual polarization radar utilizing S-band and X-band frequencies. CP-2 will use the developing PIRAQ III processor. This effort continues a scientific and engineering collaboration between the two institutions.
Multiple Antenna Profiler (MAPR)
During the past year improvements to MAPR were made in the front-end hardware to improve sensitivity, dynamic range, and reliability. Development has focused on refinement of the temporary hardware arrangements. ATD's Design and Fabrication replaced the initial steel box containing all the front end circuitry. This front end box contains a new system which will allow for more organized testing of components, repair and experiments with hardware configurations. A new control circuit board for the FDI frequency switching was constructed making the switching more accurate and the entire system more robust. Also, the frequency switching electronics which allow MAPR to also use the Frequency Domain Interferometry (FDI) Range Imaging (RIM) technique were consolidated onto circuit boards. FDI RIM allows much finer vertical resolution measurements when a distinct scattering layer is present (see section on Boundary-Layer Fine-Scale Structure).
MAPR was also modified to be mounted on a scanning platform at NCAR's Marshall field site. For the Scanning MAPR experiment at the Marshall field site, an old radar pedestal was resurrected and adapted for mounting the MAPR antenna so it could be pointed at potential convective targets. The Scanning MAPR tests are intended to explore direct measurement of the full three-dimensional wind field with a single scanning radar (see section on Scanning Radar Wind Field measurements). Work also continued on wind measuring technology with collaborators in RAP and Dr R Doviak of NOAA/NSSL.
Mobile Integrated Sounding System (MISS)
ATD's goals for the Mobile Integrated Sounding System (MISS) are easy mobility and fast deployment. The system consists of the standard Integrated Sounding System components: a wind profiling radar, enhanced surface station and radio sonde launching capability. Individually, these components provide wind vectors, pressure, humidity and temperature vs. height. At the surface they can measure temperature, humidity, pressure and solar radiation. Further data is available for high level meteorological analysis. The MISS allows pursuit of storm fronts such as the landfall of hurricane Isabel, which could help with evacuations and predictions of tornados from large thunderstorms. The fact that it is mobile also allows the location to be corrected if the desired results are not being obtained or if the front has passed and relocation ahead of the front is desired.
During
the past year, engineers and technicians made some of the
final modifications to the MISS in preparation for its first deployment.
During the past year:
- The wind profiling radar has been mounted to a trailer,
- The rapidly deployable surface station has been completed,
- The trailer leveling and electronic compass orientation have been integrated,
- The camper has been modified to handle numerous amounts of computer equipment, and generate power for the entire system, and
- practice deployments have been done.
The picture to the left shows the MISS as it was deployed for verification of an experiment for a radar positioned 5 miles away. Due to interference caused by other RF equipment in the area during the second deployment, ATD technicians were able to quickly move the system 5 miles away. This is one of the many benefits of a mobile version over the stationary ISS, which takes 3 days to deploy, and requires a power source at whatever location operations are to occur.
The purpose of the NEXRAD
Data Quality Optimization Program, funded
by the National Weather Service's (NWS) Radar Operations Center (ROC),
is
to provide scientific and engineering expertise to enhance NEXRAD data
quality, focusing on two areas: 1) Range-Velocity Mitigation and 2) Anomalous
Propagation Mitigation with Reflectivity and Velocity Compensation. During
FY03, ATD continued to develop new and improved software tools for
the analysis
and verification of a Range-Velocity (RV) mitigation algorithm which
uses phase coding of the radar transmit pulses.
A new SIGMET RVP8 radar receive/processor (same processor that is to be deployed
on the NWS NEXRAD radars) was installed into NCAR's S-Pol radar for real time
testing of RV and other data quality algorithms that will potentially be deployed
on the NEXRAD radars. Installation was successful and a RV algorithm was designed,
developed and implemented. Data were gathered showing significant data quality
improvement when phase coding is employed.
The ATD Anomalous Propagation (AP) clutter mitigation scheme consists of a fuzzy logic-based radar echo classifier as well as a reflectivity and radial velocity compensation algorithm. The radar echo classifier (REC) detects AP clutter echoes and precipitation echoes. The compensation algorithms correct the bias in the reflectivity and radial velocity fields that exist from the application of the ground clutter filter. Output from the REC ensures that the compensation algorithms are only applied to precipitation echoes. The AP clutter mitigation scheme has been deployed on each S-POL field experiment since STEPS in 2000. Ongoing research with the REC has been to add a sea clutter detection algorithm. This algorithm has been deployed on the United Arab Emirates radars in collaboration with the Research Applications Program (RAP). Ongoing research with the reflectivity compensation algorithm has been to devise a confidence algorithm.
Phase coding the transmit pulses of weather radar make possible the
separation of multi trip echoes, thereby extending the unambiguous range
of the radar while not compromising the unambiguous velocity. For example,
if the
transmit pulses are separated by 1 millisecond, then the unambiguous range
is 150 km while the maximum unambiguous velocity is 25 meters/second (at S-band
or 10 cm wavelength).
Figures 1-3 show data gathered by NCAR's RVP8 receiver on S-Pol and demonstrate the improvement in data quality that phase coding can provide. The three data scans are gathered within a few minutes each other.
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Figure 1 shows a" truth" reflectivity scan at 0.5 degree elevation angle using a PRT (pulse repetition time) of 2.7 milliseconds so that the unambiguous range is 405 km.
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Figure 2 shows the same storm scanned using a PRT of 1.04 milliseconds so that the second trip echos are folded into ranges 0 to 155 km thus creating a false radar image. This same area is then scanned with phase coding at a PRT of 1.04 milliseconds and via signal processing, the overlaid echoes are separable.
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The resulting processed radar image is shown in Figure 3 and should be compared to Figure 1 (the "truth"). The increase in data quality and image clarity when comparing Figure 2 to Figure 3 is dramatic. It is estimated that in the next few years all of the NWS NEXRAD radars will use this technology.
Sounding Systems
During FYO3 ATD achieved all Phase I objectives of the Driftsonde development. ATD launched three additional (two previous flights were made in FY02) development test flights from the Global Solutions for Science and Learning (GSSL) Flight Facility in Tillamook Oregon. The Executive Summary page gives an in-depth description of the Driftsonde's team's achievements over the past fiscal year.
Tethered Atmospheric Observing System (TAOS)
TAOS
was redesigned and will be deployed in the Hudson Valley Ambient Meteorology
Study (HVAMS), October 2003. The redesign addressed
mechanical interface issues, improved sensor integration and data reliability.
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GPS/Loran Atmospheric Sounding System (GLASS)
ATD
Engineers began planning a redesign of GLASS during FY03. System components
are under scrutiny and
overall system layout will be
completed
by year-end. Delivery of three systems to the National Severe Storms
Lab will occur spring of 2004. Major improvements will include; capability
for multiple, simultaneous soundings, digital system design, low power
requirement, and small light mechanical footprint.
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Surface Flux Systems
Integrated Surface Flux Facility (ISFF)
In
FY03 development work started on the new data acquisition system for ISFF.
This work has been done in conjunction with the development of the Intelligent
Sensor Array. Based on the PC-104 bus, a prototype of the new data acquisition
system was built. Initial work has focused on replacement of the 13 year
old ASTER data acquisition system. A majority of this effort has been porting
the original ASTER code to the new platform. Preliminary tests performed
on the serial communication channels have been very successful being able
to handle 8 sonics running at 60 Hz with the goal to handle 16 sonics at
60 Hz. Another highlight in the design is the reduction in power consumption
from a 400 watt AC system to a less than 20 watt DC system. In addition
there were new developments in data software products. Spectra, profile,
and time-series plots are now standard near real-time WWW products for ISFF
field projects. Extensive amounts of high-rate and reduced ISFF data are
available on the WWW for projects dating back to 1998.
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Long-Wave Blackbody Calibrator
Progress has been made on the blackbody calibration system. Design and construction of the major parts of the system were completed early in the year. Initial tests presented unexpected challenges, e.g., the development of frost in the blackbody cavity at extreme low temperatures. This was overcome by the addition of a separate nitrogen purge line-feeding into the cavity space. ATD is currently in the phase of testing the isothermal stability of the blackbody cavity when installed in the temperature-controlled oil bath. Upon completion of these tests, ATD will start calibration runs and inter-comparison tests with NOAA and the National Renewable Energies Laboratory (NREL).
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Intelligent Sensor Array (ISA)
Last spring ATD, under NCAR’s Advanced Observing Systems Initiative, began to develop a new environmental and meteorological observing system to keep NCAR at the forefront of geoscience observing system technology. This technology is called the ISA or Intelligent Sensor Array.
A detailed description of this project is located on the Executive Summary page.
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Lidar Developments
ATD completed development of an eye-safe aerosol backscatter lidar prototype
during the summer of 2003. Over 150 hours of data were collected from
the FL-1 lidar lab during tests. The system performs extremely well and
is capable of "seeing" aerosol features to more than 10 km
range. Efforts are under way to install the system in a seatainer with
a beam-steering unit for field deployment in FY04. A manuscript describing
the system has been prepared and will be
submitted to a scientific journal very soon. Results
of the summer tests can be viewed on the ATD website.
The
eye-safe aerosol backscatter lidar (laser radar) is novel in that
it works at a wavelength (1.5 microns) which poses no hazard to the eyes
and has sufficient sensitivity to detect both naturally occurring and
anthropogenic aerosols (wind blown dust, smoke, pollution, etc.) Because
the laser beam poses no ocular hazard, it can be used by
atmospheric scientists in locations where non-eye-safe lidars could not
be used (such as cities). ATD scientists envision this technology maturing
for continuous monitoring and automated display aerosol pattern maps
over urban areas.
High-power water-vapor DIAL
In FY03, ATD continued to collaborate with the University of Hohenheim in Stuttgart, Germany, on the development of a high-power lidar to measure atmospheric water vapor. Both parties made substantial progress towards their commitments. ATD completed the optical design of the receiver and ordered required telescope optics, including a 1.0 meter diameter primary telescope mirror. In addition to this, the roof-hatch in ATD's FL-1 was expanded to accommodate the large telescope for test of the transmitter and receiver in the summer of 2004. The University of Hohenheim recently achieved a significant milestone in laser development: 40 watts of transmit power at the wavelength necessary to pump devices that will change the wavelength to that necessary to measure water vapor.
Development in Airborne Observing Systems
Remote Sensing Systems
Scanning Aerosol Backscatter Lidar (SABL)
SABL
is a 2 wavelength aerosol backscatter lidar that can be flown on board
the NCAR C-130. It is not eye-safe within a certain distance. Due to
its age (it is around 10 years old) ATD engineers and scientists have
determined, after studying its design and performance,
many improvements that will be considered again FY04.
Pipsqueek is a radar that provides a microwave cone of protection around non-eye-safe lidar laser beams. This radar system was installed in the FL-1 lidar lab in FY03 so that non-eye-safe lidars such as SABL can be safely tested. ATD radar engineers Frank Pratte and Grant Gray published two papers in this year's radar conference on the Pipsqueek radar system.
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Airborne Imaging Microwave Radiometer (AIMR)
AIMR was deployed during the IDEAS-2 and IDEAS-3 field programs in FY03. Various objectives were addressed with these deployments, including: 1) data acquisition for development of vegetation classification and wildfire detection algorithms; 2) sensor maintenance and troubleshooting in an aircraft environment; 3) data acquisition for testing modifications to the calibration scheme; and 4) experimental detection of a surface transmitter for improved geolocation of imagery.
Flights conducted over a variety of vegetation types in Wyoming, Colorado, and New Mexico provided a range of microwave signatures for analysis. An algorithm that utilizes the microwave emissivity polarization difference (EPD) was developed to distinguish vegetation classes for detection of wildland fire fuels.
Figure
1 shows EPD signatures for various surfaces. Given the sensitivity of
AIMR, preliminary analyses suggest that this method can be used to distinguish
between major vegetation classes (e.g., forest vs. grassland), but not
between vegetation sub-classes. An active fire was also observed during
the IDEAS campaign.
In
Figure 2, a 90 GHz brightness temperature image clearly shows the location
and extent of two burning areas, while the accompanying visual image
is obscured by smoke. Given the ability of AIMR to “see” through
the smoke, there is potential for this sensor to be used for fire mapping
purposes. (This work was sponsored by the NCAR Wildland Fire Collaboratory
(WFC) Initiative)
A problem with the AIMR scanning rate adjustment system was identified during IDEAS-2. Extensive troubleshooting was conducted in-flight, and the problem was discovered to reside in software communication with the stepper motor. ATD was able to correct the problem following the experiment, and tests conducted during IDEAS-3 indicate that the system now functions properly.
Analysis of the calibration system modifications and geolocation methods is ongoing as part of the dissertation research of an ASP graduate fellow.
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MCR (Multichannel Cloud Radiometer)
The MCR
is a downward-looking, seven-channel (visible, IR, and thermal) scanning
radiometer. During July 2003, the MCR was deployed aboard an ONR
Twin
Otter during CSTRIPE,
a field experiment designed to quantify the effects of pollution
on clouds.
The Twin Otter flew over marine stratocumulus clouds near Monterey,
CA, and was about 700m above the cloud deck as the MCR recorded the
image in Figure 1.
MCR
observations at CSTRIPE are being analyzed to infer cloud drop effective
radius and liquid water path of the coastal marine clouds. Figure 2 is
a plot of a visible MCR channel (channel 1, 0.64 um) vs. a water-absorbing
channel (channel 5, 1.64 um). The black points are the data from the
image in Figure 1. The cross-hatch lines are the cloud drop effective
radius (solid lines, labeled in um) and liquid water path (dashed lines,
in g/m^2) as modeled by a radiative transfer program that simulates the
conditions (e.g. solar geometry, atmospheric constituents) during this
observation. By comparing the observed to the modeled radiances, the
cloud characteristics can thus be obtained.
The MCR was also deployed aboard the C-130 during IDEAS II & III during FY03. A new channel (870 nm), selected to distinguish vegetation, shows "crop circles" in southern Colorado in Figure 3 (bottom part of image). This channel can be used with channel 1 to map vegetation using a standard vegetation index (NDVI).
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ELectra DOppler RAdar (ELDORA)
The ELDORA Receiver was re-designed in FY03 in order to move the LNA's (low noise amplifiers) for each radar closer to the antennas. Eliminating most of the waveguide run on the receive path lowered the system noise figure and thereby increased sensitivity by about 3 dB.
A new data display and archiving system was added to complement the
new integrated scientific display station. Antiquated display hardware
and recording hardware were replaced by redundant, high-end rack-mount
PC's,
thus eliminating a major bottleneck in system performance. Real-time
data are
now recorded on removal disk drives rather than tapes. This greatly improved
the efficiency and latency of data post-processing.
The ELDORA Rotodome was inspected and refurbished. The rotodome slowdown after a few hours of operation that was experienced in 2002 was resolved.
The science display on NRL P3 was upgraded so that six images can be displayed simultaneously for ELDORA flight scientists to direct missions. New additions to the display suite include the WSI real-time WSR-88D composite image and the regional WSR-88D composite image with flight track overlay. These two images were uploaded to the NRL P3 via satellite phone. Limited Internet capability was made available via satellite phone so scientists could "chat" with scientists on other aircraft, scientists and ops directors in the operation center, and other supporting staff on the ground. This real-time "chat" function (see Real-Time Display and Coordination Center, below) was extensively used during BAMEX to not only exchange current information among all airborne facilities but also resolve onboard instrumentation problems with ground staff.
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Chemical Sensor Systems
Development of New High Performance Airborne Instrument for the Measurement of CH2O
The trace gas CH2O is one of many important atmospheric species involved in ozone production and radical formation (see section on advances in tropospheric chemistry), and the APOL group has devoted a significant effort over the past several years to carry out ever more accurate and precise measurements of this gas. Although the present airborne system, which employs a liquid-nitrogen cooled lead salt diode laser, yields satisfactory results for most regions of the atmosphere, improved sensitivity is clearly needed in the background atmosphere where CH2O levels approach 30 to 50 parts-per-trillion (pptv). The present instrument sensitivity (15 – 50 pptv, 1? precision for 1 minute of averaging) needs to be improved for routine measurements in the background atmosphere, particularly in the upper troposphere/lower stratosphere where CH2O decomposition becomes a major source of reactive hydrogen radicals. To address this critical need as well as the need to develop smaller, lighter, and autonomous-operation instruments for future HIAPER campaigns, the APOL group has been developing a new high performance airborne instrument based upon difference frequency generation (DFG). In this approach, mid-infrared (IR) laser light at 3.53-?m, a spectral region where there are strong CH2O absorption lines, is generated employing well characterized room temperature operation near-IR telecommunication lasers. The mid-IR light retains all the high quality spectral and spatial qualities of the near-IR pump lasers (see Richter et al., Applied Physics B, DOI 1007/s00340-002-0948, 2002), a significant advantage when compared to more traditional lead-salt diode lasers. Moreover, the ultimate instrument size will be significantly smaller and more rugged than our present lead-salt diode system. Figure 1 shows an optical schematic of the laser sources and the non-linear crystal used in generating the difference frequency.
This
new DFG system has been extensively characterized in the laboratory over
the past year. An important source of optical noise has been identified
and present strategies are being implemented to circumvent this problem.
Preliminary performance measurements employing one solution are extremely
encouraging, and more rigorous laboratory tests are underway.
In addition to progress in the development of new and improved laser sources for the near-IR spectral, where a host of gases like CH2O exhibit strong absorption features, significant progress has also been achieved this past year in the development and testing of a new multipass absorption cell. The long optical pathlengths of multipass absorption cells (100 – 200 meters) are required to achieve detection sensitivities in the pptv range. In such cells, the laser beam is reflected back and forth hundreds of times, and this requires very high spatial beam quality as well as high beam pointing stability and cell alignment stability. The new DFG laser source addresses the first two requirements and significantly helps in achieving the third (to be discussed). By contrast, presently employed lead-salt diode laser systems and multipass cells fall short in all three areas on airborne platforms. In addition to poor beam quality, lead-salt laser systems, including our state-of-the-art airborne system, must employ numerous discrete optical elements before and after the multipass cell. As a result of cabin pressure changes, aircraft vibrations, and changes in aircraft attitude, the present components, including the multipass cell, all undergo slight alignment changes. Such changes degrade instrument performance and require human intervention for active rectification. Although ATD has been quite successful operating with these problems, a mechanically more robust optical system would reap significant benefits.
The APOL group has expended a great deal of time and effort this past year to address optical mechanical stability of the entire optical system, including the multipass cell and transfer optics. In addition to the very high spatial beam quality and beam pointing stability offered by DFG laser sources, the DFG module can be directly coupled to the multipass cell in a pressure-stabilized semi-sealed compartment. This not only avoids dust contamination on the transfer optics but also eliminates pressure-induced alignment changes. To be completely successful, this approach also required the development of a new pressure-insensitive multipass absorption cell. A visiting graduate engineering student, Christoph Dyroff, from the University of Applied Sciences, Emden, Germany has completed a 6-month project designing, constructing, and testing such a new cell for this purpose. In addition, this student has carried out extensive sensitivity tests, including alignment sensitivity of the multipass cell output beam to the shape of the initial input beam. The high quality DFG input beam was found to be far superior to that from lead-salt diode lasers in this regard.
Figure
2 shows a schematic of the new absorption cell with carbon fiber stabilizing
rods and the new DFG laser stage directly coupled to the end of the cell.
A number of preliminary tests have been carried out with this new cell
in the laboratory, and the results directly indicate improvements in
stability with changes in pressure. Additional studies are planned for
this new cell. Once completed, the new
system will be employed next year on NASA’s INTEX airborne study.
Ultimately, ATD anticipates that this new laser source/multipass absorption
cell system will require no active alignment in flight, a requisite for autonomous
operation on HIAPER.
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Development of a New Laser Spectrometer for High Precision Measurements of 13CO2/12CO2 Isotopic Ratios
The APOL group has embarked upon a 3-year NSF-funded effort to exploit the developments in new DFG laser sources discussed above for high precision carbon dioxide isotopic ratio measurements. New approaches are badly needed to acquire such measurements in real time. Present ultra high precision measurements acquired by flask sampling and mass spectrometry can only process a limited number of samples. The APOL group in collaboration with partners from the University of Colorado and Rice University have made considerable progress in the development of a new instrument. Figure 3 illustrates the optical schematic of such a system, which is presently under construction. The signals from two cells containing the sample gas and an isotopic reference standard are rapidly compared using the setup shown in this figure.
In addition to the optics, a comprehensive inlet system was designed, which allows multiple combinations of calibration reference gases and/or sample gases to be directed into one or both cells. This system is presently under construction and comprehensive tests will be carried out this upcoming year. A graduate student from Rice University, Chad Roller, has joined our group and is working on multiple aspects of the new system, including the data acquisition and retrieval algorithms.
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Airborne Carbon Dioxide and Carbon Monoxide Measurements
As part of the Biogeosciences Strategic Initiative, the NCAR Airborne Community Trace Gas Measurement Group (ATD/ACD) designed and constructed an instrument that measures CO2 mixing ratios or fluxes. Precise and accurate airborne measurements of its mixing ratio is a key tool in understanding regional scale land-atmosphere-ocean carbon exchange, which can reveal much about the health of the regional environment.
Vertical flux measurements using the eddy correlation method yield information on dynamic exchange at interfaces, including for example, the surface - boundary layer and boundary layer - free tropospheric interfaces. The highly modified instrument is based on a commercial broadband infrared absorption instrument. The new design represents a novel approach to data acquisition and processing which are expected to improve instrument noise specifications to meet or exceed present state-of-the-art capabilities.
Initial flight tests were conducted as part of the IDEAS-III test program in September, 2003. Preliminary assessments give some hope that airborne flux measurements may be possible with small or no artifact produced from interaction between the sensor components and aircraft motion. The instrument hardware and processing software will be refined in FY04 to provide further precision improvements for both mixing ratio and flux measurement modes of operation.
Lower tropospheric carbon monoxide is a useful though non-specific combustion tracer. CO mixing ratio measurements are quite powerful air mass indicators when combined with other tracer measurements such as ozone, carbon dioxide, and/or hydrocarbons. A new design was developed to modify our commercial vacuum ultraviolet resonance fluorescence carbon monoxide instrument for more improved reliability and ease of field deployment. The existing instrument has been successfully deployed on several airborne missions. Most recently the instrument underwent a successful laboratory intercalibration exercise in April, 2003, as part of the CRYSTAL-FACE experiment. Collaborators included Dr. Teresa Campos (NCAR), Dr. Max Loewenstein, Dr. Jimena Lopez, and Dr. Hans-Jurg Jost (all of NASA-Ames). A proposal was submitted during the summer of 2003 by Dr. Ian Faloona (UC-Davis) to collaboratively explore the potential for improvement of the sensor's time response beyond its present 0.5- to 1-Hz capability.
Miniaturized gas modules were designed and constructed to allow significant weight and size reduction of support and calibration gas installations used in both CO2 and CO instruments. This approach will also allow standard gas calibration under controlled laboratory conditions.
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Airborne Water Vapor Measurements
Intercalibration activities were conducted between several CRYSTAL-FACE water vapor sensor investigators, including Dr. Teresa Campos (NCAR), Dr. Linnea Avallone and Gannet Hallar (University of Colorado), Dr. Cindy Twohy (Oregon State University) and Dr. Gregory Kok (Droplet Measurement Technologies). As a result of insights from this and earlier laboratory tests, instrument modifications were initiated to allow more accurate determination of lower tropospheric water vapor mixing ratios. Also included among design goals was development of software processing tools to enable rapid processing of field data. These modifications are being undertaken in consultation with the NCAR ATD Analytical Photonics and Optoelectronics Laboratory (APOL).
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Commercial Ozone Sensor Evaluation
A compact commercial ozone sensor developed originally for balloon sonde measurements was evaluated during IDEAS-2 flights. Although its performance has been established to be adequate for balloon-borne payloads, the pump supplied with the instrument was replaced with a more powerful unit to enable air flow from an inlet through the instrument at typical C-130 inlet pressures. It was observed that ozone measured with this instrument deviated significantly from the RAF standard UV absorbance sensor at flight altitudes. The conclusion at this point is that significant modifications would be required to enable accurate ozone mixing ratio measurements using this instrument on an aircraft platform.
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State Parameters
Improvements in inertial systems
The Inertial Navigation System provides half of the data necessary for the measurement of airborne turbulence and winds (the other half is a flow angle system). Flight testing is currently underway to evaluate new technology to improve the measurements of wind and turbulence with the goal of developing a smaller, faster and lighter-weight system that will lend itself to a pod-mounted location.
Aviation Infrastructure
In the past year, new emphasis has been placed on pursuing airflow studies at RAF. These studies include modeling and measurements and are a continuation of earlier work. They will support a variety of issues on NCAR aircraft, including instrument placement, instrument design, and analysis of observational data. The new emphasis was prompted by advances in computational fluid dynamics (CFD) software, computer performance, the need for airflow studies to support HIAPER instrumentation issues, and to connect with Gulfstream Corporation airflow studies in support of HIAPER. Activities in FY03 included a survey of investigators, a small flow-modeling workshop, and CFD software training. These activities are outlined below.
A web-based survey was taken of NCAR and university atmospheric science investigators to gauge their interests in air flow studies at RAF that can support their airborne research in both the C-130 and the G-V aircraft. Thirty-three people contributed to the survey. Their airflow interests included particle trajectories, concentration enhancements and shadow zones, flow speed and angles, boundary layer and pressure distributions, dynamic heating and placement of inlet and exhaust ports. Survey replies were very supportive of this ATD/RAF effort and confirmed the importance of airflow issues.
In February, a small flow-modeling workshop was held to review current capabilities of FLUENT CFD software. A FLUENT CFD expert (Philippe Nacass) visited RAF and provided instruction and advice for ATD researchers (Twohy, Rogers, Friesen and Jensen).
In July, two ATD scientists attended training to use STAR-CD, another advanced CFD software package. The plan is to compare the performance of STAR-CD and FLUENT for some critical studies, such as compressible flow simulations around under-wing pods on the G-V, including particle trajectories, shock regions, and boundary layer resolution.
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Research Aviation Facility (RAF) staff continues to write and upgrade flight operations and aircraft maintenance operations procedures in response to the ICAP inspection recommendations from 2001. The C-130 minimum equipment list (MEL) has been completed and inspected for content, format, and completeness by an ICAP maintenance inspector, who is a member of Southwest region FAA, Oklahoma City. All suggestions by the FAA have been incorporated into the MEL. Deferred maintenance placards similar in design to airline (FAR Part 121) operators have been implemented. Many flight and maintenance forms have been modified and updated.
The NCAR/RAF general maintenance manual (GMM) is in preparation. Work continues on the GMM which includes numerous form generations and research on relevant content applicable to NCAR's operations. The C-130 Progressive Maintenance Program (Lockheed Martin SMP 515C) has been revised and updated by Lockheed with the most current requirements. All maintenance manuals have been updated and placed on the manufacturers' revision service. Final edits to the operations manual are in progress.
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A number of critical engineering meetings and design reviews for HIAPER took place in FY03. In December 2002 a Technical Interchange Meeting (TIM) was held at NCAR between Gulfstream, Lockheed Martin, NCAR, and UCAR staff. This meeting provided an opportunity for the meeting participants to further refine the specifications (e.g., locations, loads, etc.) for the modifications to be made to the GV and provided a framework for the work to be done during the time period leading up to the HIAPER Preliminary Design Review (PDR). The PDR itself was held in late March 2003 in Greenville, SC. During the PDR, all modifications to be made to the aircraft were reviewed in detail, and owing to the ongoing efforts of NCAR, Gulfstream, and Lockheed personnel to resolve technical issues in the preceding months, a number of the modification specifications were finalized during the PDR.
During the Critical Design Review (CDR) for the HIAPER project, which was held in late June 2003 in Greenville, NC, Gulfstream and Lockheed personnel presented comprehensive information regarding the modifications to be made to the GV, and UCAR and NCAR gave verbal approval to proceed with the design and fabrication of the various modification components. Formal UCAR and NCAR approval of the HIAPER modifications will occur following the preparation and acceptance (by UCAR, NCAR, Gulfstream, and Lockheed) of the Statements of Work (SOWs) for the HIAPER project in early FY04. Also during the CDR, the HPO formally approved the external paint scheme and internal material and color selections for the GV.
Jacking
and shoring of the GV were successfully accomplished from 5-6 August
2003, with the aircraft
leveled to well within factory tolerances for the airframe.
Leveling of the GV will be checked continuously over the course of the
modification effort.
In addition to monitoring the performance of the project subcontractors in FY03, the HPO also oversaw the start of work to develop the various infrastructure systems (data acquisition system, data display and access software, intercommunication system [ICS], SATCOM, etc.). IPT subgroups established in FY02 made significant progress in FY03 in establishing specifications for and beginning development of the various infrastructure components. Specifically, PDRs were held for both the data acquisition system and data display and access development activities, and a preliminary request for proposals (RFP) was written and released for the GV ICS. Additionally, the co-chairs of the data acquisition system subgroup began a survey of commercially available SATCOM systems for possible use on the GV. Members of the state parameter and air motion sensing systems subgroup also began determining which state parameter sensors should be used on the aircraft and ordered one static pressure sensor for initial testing and evaluation at the RAF.
HPO staff continued their efforts in FY03 to provide information on
the HIAPER project to the larger scientific community. To that end, HPO
staff members partnered with ATD and NSF personnel to give presentations
on HIAPER during the Fall 2002 AGU Meeting, the February 2003 AMS Meeting,
and the EGS/AGU/EUG Joint Assembly in April 2003.
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An RFI for the FY2005 NSF/NCAR C-130 corrosion inspection was issued in early September. Responses were due in October 2003. It is anticipated that a formal RFP for the inspection will be issued in December 2003.
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The Research Aviation Facility (RAF) took advantage of a limited C-130 field deployment schedule in 2003 to upgrade both the scientific and operational infrastructure of this research platform. ATD was able to complete the following tasks during that time:
- Enhanced onboard data displays by adding larger monitors
- Added aft cabin access to visual position referencing via a video projection of the forward video camera
- Improved flux measurement capabilities by adding two mounting pads to radome sensor ring
- Improved aircraft position reference by changing over to a WAAS Global Positioning System receiver
- Increased the capacity and pressure integrity of the sub-floor community chemical exhaust system by changing tubing
- Improved aft cabin work environment by adding more overhead lighting fixtures
- Refurbished all observer seats and individual storage compartments
- Enhanced of mission scientist cockpit station through the addition of SATCOM access to real time WSI weather information
- Added flight deck and aft cabin storage bins
- Improved the versatility of the right side wing pod by adding new power and signal wiring
- Refurbished cockpit carpeting, wall coverings and observer seats
- Added a backup research pitot tube for redundant air speed measurement
- Added a C-MIGITS mini-inertial system to provide backup measurements of aircraft position, ground speed, and platform attitude
- Improved onboard computer networking by replacing the master network hub
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Developments in Data and Network Services
Real-Time Display and Coordination Center (RDCC)
ATD staff provided an extraordinary level of real-time data and communication service to BAMEX: real-time high-bandwidth communications among mobile and fixed sites; data integration to provide data set overlays, for example of aircraft tracks on radar images, radar images on satellite images, etc.; real-time Internet chat with three aircraft and project participants; and real-time data (not just image) access and backup. In addition, ATD staff supplied all of the day-to-day computer networking needs for the BAMEX project office at MidAmerica Airport near St. Louis, Missouri. BAMEX operations depended on daily planning coordinated among sites, quick data analysis with multiple sensor quality control, and real-time communication with and control of ground and aircraft resources. Those functions could not have occurred without ATD support and services. Network, wireless, and satellite technologies, coupled with rapid affordable data storage and multiplatform data display tools, allow ATD to provide these services—information technology applied to real-world research. Most large field projects now require these kinds of information and coordination capabilities.
Developments in Design and Fabrication
ATD’s Design and Fabrication Services staff played a major role in instrument developments and field project support. DFS staff worked to complete modifications to the ELDORA system on the NRL P-3 platform for the BAMEX project.
DFS is working in conjunction with HAO on the Sunrise
balloon-borne solar telescope. The project requires mechanical design and analysis
of the gondola structure as well as the azimuth over elevation pointing
system
for the telescope. Much of the system will be fabricated in-house, with some
of the larger gondola components provided by vendors.
Other projects in which DFS participated include the preparation of the CP-2 radar for transfer to the Australian Bureau of Meteorology, development of the Driftsonde system, work on the Rapid Scan Mobile Doppler Lidar, and the design and fabrication of HIAPER instrument racks and wing mounted pod systems.
DFS staff work to increase capabilities by learning and implementing new CFD (Computational Fluid Dynamics) software. ATD utilizes both Star CD and Fluent packages to develop flow characteristics in the vicinity of instruments and inlets attached to the various aircraft.