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| Collecting coarse aerosols (up to 10 microns) by diffuser and curved-tube samplers on research aircraft has been less efficient than needed, and the LTI was designed to improve sampling of such particle populations. The LTI was developed jointly by scientists from the University of Hawaii and Denver University, and ATD's Design and Fabrication Services (DFS). It employs a porous tip through which the air being sampled is drawn, with turbulence being suppressed by suction. This prevents separation of the boundary layer. The efficiency of the LTI is near enough to unity to produce reliable studies of the distributions and impacts of both mineral dust and sea salt; this was demonstrated last year in test flights in the Carribbean flow by the C-130 (see ATD's ASR 2000) outfitted with the LTI and three other samplers for comparison. |
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| A three-dimensional portrayal of the LTI produced by ATD's Desgn and Fabrication CAD system. |
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The first research deployment of the LTI occurred in March-April 2001, in the Asian-Pacific Regional Aerosol Characterization Experiment (ACE-Asia), led by B. Huebert of the University of Hawaii. ACE-Asia was designed to improve understanding of how atmospheric aerosol particles affect Earth's climate system. This field program is the fourth in a series organized by the International Global Atmospheric Chemistry project. The field program took place off the coast of China, Japan, and Korea, where many types of aerosol particles of widely-varying composition and sizes, derived from one of the largest aerosol source region on Earth, are to be found. Results from ACE-Asia will improve our understanding of how atmospheric aerosols influence the chemical and radiative properties of Earth's atmosphere and our ability to predict how changes in aerosol composition and concentration may influence future changes in the climate system. |
Many institutions and scientists from around the world participated in ACE-Asia, which was supported by a number of US and foreign agencies, and employed a variety of observing platforms and systems. ATD's participation was through deployment of the NSF C-130, equipped with the LTI and SABL. Air leaving Eastern Asia was surveyed to characterize aerosol physical, chemical, and optical properties emphasizing variations with altitude and distance from shore. The data collected will be used, along with data from the three previous ACE projects, to improve modeling the effects of different emission scenarios on Earth's climate.
 The Automated Dropsonde Launcher installed on the ER-2 |
The GPS Dropsonde, developed by ATD, is now in use in six nations, on 20 aircraft and in operations of the USAF and NOAA. The utility and flexibility of the Dropsonde was significantly enhanced with the development of an automatic pod-based launcher. This was a joint development project between ATD and NASA Dryden. The launcher was successfully deployed during a NASA/Marshall Space Flight Center sponsored project called the Convection and Moisture Experiment (CAMEX), led by J. Rothermel of NASA. |
CAMEX was carried out in August and September 2001 over the Atlantic and Gulf of Mexico. Its main goal was to improve hurricane forecasting models by obtaining high quality profiles of temperature, humidity, and wind that could be used to improve the parameterization of the dynamic and thermodynamic structure of the tropical cyclone. Improved parameterizations would lead to refined hurricane models, particularly with respect to intensification and tracking.
In this first deployment of the automated launcher, the GPS Dropsonde, in eight out of eight drops into the inner core of Hurricane Erin, delivered excellent thermodynamic and wind data. One sonde was dropped into the eye of the hurricane; it functioned perfectly and produced the first profile of eye conditions from 65,000 feet to sea level.
The Dynamics and Chemistry of Marine Stratocumulus Phase I Entrainment Studies Experiment (DYCOMS II), an NSF-sponsored project carried out off the coast of southern California. The primary research goal of DYCOMS II, led by B. Stevens (UCLA), was to evaluate large-eddy simulations (LES) of nocturnal stratocumulus.
ATD technicians and engineers outfitted the NSF C-130 with the GPS Dropsonde system, the University of Wyoming cloud radar, SABL, and instruments to make fast in situ meansurements of trace gases, including H20, O3, and DMS. The data collected will provide an accurate description of the large-scale environment and turbulent fluxes within, and at the top of, the PBL. Entrainment measurements were used to test parameterizations developed on the basis of LES, and accompanying data provide additional information needed to develop a suite of test cases for subsequent simulations. Data collected will also support secondary objectives of DYCOMS II, including testing recently proposed techniques to measure large-scale divergence; testing our ability to close scalar budgets under ideal situations; and increasing our understanding of the statistical signature of the diurnal cycle in marine stratocumulus.
The overall research goal of
the Improvement of Microphysical Parameterization through
Observational Verification Experiment IMPROVE) is to
gather a comprehensive data set, including both basic state (eg wind,
temperature, humidity) and cloud microphysical and precipition
information that will allow the verification and improvement of the
moist processes in mesoscale models. Funded primarily by the NSF,
IMPROVE also received support from the USNavy and DOE; the project was
led by C. Maas and P. Hobbs of the University of Washington.IMPROVE-I was carried out in January-February 200l, off the shore of Washington and Oregon; its focus was on offshore frontal precipitation with a particular empahsis on improving quantitative precipitation forecasting in mesoscale models. ATD installed the S-Pol radar near the Pacific Ocean and the radar operated in a 24/7 mode for the duration of the project. Eleven Intensive Observational Periods (IOPs) occurred during the one-month period. The Wyoming cloud radar sampled 14 moving rainbands that were simultaneously scanned by the S-POL dual polarization radar. The rainbands sampled were associated with the upper level cold fronts of warm type occlusions, surface cold and occluded fronts, and warm frontal type within warm occlusions. Initial assessment of the data including use of NCAR's MMM5 forecast model as well as the radar data, indicates that IMPROVE I was a success. The project evaluation form states "A key to the success of the project was the willing spirit, the competence, and the facilities of ATD."
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| The NSF Electra in its early research configuration with the nose boom, during TOGA COARE, during the first ELDORA deployment and on its last flight during MAP. |
POST SCRIPT: Although previews aren't the norm for ASR's we'd like to note that successful negotiations with Gulfstream were held early in December 2001, and a contract was signed before the end of the month. Proceeding with the negotiations was enabled by appropriation of $35million for HIAPER, to NSF and NCAR. The green airframe is to be delivered by Gulfstream to Lockheed for modification in June of 2002, and delivery of the modified HIAPER to NCAR and NSF is scheduled to occur in the Fall of 2004. Next year's report will be able to describe significant progress on the modifications.
A
schematic representation of the HIAPER aircraft, produced by
Gulfstream and Lockheed showing the many modifications to be made to
produce a research-ready aircraft.
IMG SRC="images/hiaper4.gif">
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| NRL P-3 tail modified for installation of ELDORA |
TDL water vapor instrument to be mounted on the NRL P-3 |
Because the IHOP scientists requested that Leandre be operated pointing horizontally as well as vertically up and down, DFS, in collaboration with B. Patten, a former NOAA employee, designed and built a fairing that includes a turning mirror. Platform Systems Inc.(PSI), a commercial design and application firm that routinely contracts with NRL, helped NCAR to build and repackage the ELDORA equipment into 20G standard racks to comply with Navy requirements. PSI will also help with the installation of the TDL, which will be mounted onto a pallet system to the outside of the aircraft and with the installation of two communications antennas.
Working with NRL has been a learning experience for ATD. All modifications done to the airplane, inside the aircraft as well as to the outside, have to comply with Naval Air Systems Command design requirements. In addition, all ATD and project personnel who want to fly on the aircraft, have to pass a two-day swim and survival training class at Patuxent River in Maryland.
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| Turning mirror fairing for the Leandre II lidar |
Stalwart users geared for the Navy's "Swim and Survival" test. |
 The C-130 at the refurbishment shop
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The C-130 was taken to SPAR in Edmonton, Canada for her required
inspection in September of 2000, as reported in last year's ASR.
After replacement of the four high-time engines, with low-time engines
(from NASA's C-130-B), and the rewiring required to accommodate those
engines, the routine refurbishment began and was completed in January
of 2001, just in time for the C-130 to fly to support ACE-Asia. This
"routine" work included overhaul of the propellers, replacement and
rebuilding of major structures, such as the landing gear and the
flaps, a corrosion-based inspection and application of improved
corrosion coating, repair or replacement of about 300 other individual
items, and a new paint job. In an interesting note, stripping the
plane of its multiple coats of paint and replacing with new paint,
reduced the weight of the plane by a few hundred pounds. Planning for future use of the C-130 to meet community needs is an ongoing process, and users are invited to register their needs, plans, and opinions on an RAF website which summarizes current capabilities of the plane and its instrumentation, and seeks community input as a part of planning for the future.
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Since its earliest days and springing from a field of research also strongly dependent on observational studies – solar physics – NCAR has had a first-class machine shop that over the years has evolved to its modern day version in ATD. Complete with the most advanced CAD capabilities, and computer numerical controlled machine tools. DFS has produced an impressive array of specialized instruments and equipment. Over 960 projects dating to 1963 have been supported.
Jobs are brought to the group in many different forms, from conceptual information which requires input from the design group, to complete detailed designs generated by the customer. On occasion, the customer supplies solid digital models of the instrument and its components electronically. These are opened using any one of a variety of Computer Aided Machining (CAM) software tools which are maintained in house. These CAM programs produce the tool paths required to produce the part. The material is selected and mounted in the machine tool, the tool path is downloaded to the machine via RS-232 link and the machining operations are performed. This method minimizes the requirement for detailed mechanical drawings and can greatly shorten production time.
Here we demonstrate how an instrument is made, from original concept through design, fabrication and testing, before it is ready for research use. We have chosen the 4 Channel Chemical Ionization Mass Spectrometer as our example.
In the early stages of the design, hand drawn sketches are effective in communicating the basic concepts and requirements of the instrument.
Once the basic concept is conveyed to the designer, a set of solid models of the components are detailed and put into an assembly. A very useful tool used during the design development process is provided by the software vendor SolidWorks - Download Software. The solid models can be shipped via the internet to the customer, opened and viewed using the free viewer, which provides the ability to rotate the images, do cross section views and zoom in and out to magnify details of the models. A customer has the ability to do a design review at a remote location and discuss the design simultaneously with the designer. This has proven to be an extremely effective tool.
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| A special cutaway view is used to look "inside" the assembly. Having this capability aides the designer and the Scientist in determining proper treatment of all aspects of the design. An extremely useful tool, at this stage, is the SolidWorks Viewer. | Different colors are used for separate components for better visualization of the assembly. This is the solid model representation of the HNO3 Inlet. |
Once the solid model is produced a design review is held with all interested parties. Upon review and approval by the investigator, the parts are detailed and hard copies are printed so that all dimensional information is available to the instrument maker in the shop.
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In the machine shop, the raw material is set up in the machine and material
is removed. With the use of highly advanced software and computer
controlled machine tools, complex shapes can be manufactured that were not
possible a few years ago.
3D surfacing procedure being performed on an aluminum strut part. The part is being held in two precision vices. The jointed tubes direct cooling fluid to the part that helps remove chips and provide a better finish.
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In order to insure proper fit of all components, parts are assembled, and
to some extent, tested in the shop prior to delivery to the customer. In
some cases advanced testing of the assemblies is required.
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 The fully assembled Cloud Particle Extinctionometer. |
 Wind tunnel testing of the CIMS inlet provided valuable information on the performance of the shroud design. |
The 4 Channel Chemical Ionization Mass Spectrometer mounted on the NCAR C-130 Aircraft for TOPSE.
In the research arena RTF scientists have prepared the Scanning Water Vapor DIAL design study. Using Leandre 2 and MPI water vapor DIAL data, showing that significant boundary layer moisture variability (~1.5 g/kg) occurs even in the absence of horizontal convective rolls, frontal zones or gust fronts. (See below for more information about DIAL.)
In collaboration with R. Borys and D. Lowenthal (DRI), ATD staff investigated the ability of wind profilers to detect regions of riming in snow and the measurement of ice crystal size distributions from profiler Doppler spectra. The research suggested an ability to detect riming with reasonable certainty. Measurements of size distributions were found to require simultaneous measurement of air and snow motion. Dissimilar fall speeds associated with ice crystals having the same diameter but different crystal habits introduce uncertainty in estimated size distributions.
RTF scientists showed that for coincident soundings taken during TRMM LBA in 1999, VIZ-measured RH was drier than Vaisala-measured RH by more than 10% for RHs from 20% to 60%, but more moist than Vaisala-measured RH by ~5% at RHs>60%. After correcting the dry bias in Vaisala humidity data, Vaisala and VIZ humidity data agreed well at RHs >60%. Understanding the dry bias in VIZ data at RHs from 20% to 60% requires further work.
In collaboration with A. Dai (NCAR/CGD) and R. Ware (UCAR GST), RTF studied diurnal variations of temperature and water vapor profiles by analyzing microwave profiling radiometer (MWRP) data from a system deployed for several months in Oklahoma. Water vapor mixing ratios (MR) in the upper troposphere (above ~6 km) were significantly higher in the early morning hours. MR in the lower troposphere seemed lower in the morning than in the afternoon and the night with a minimum around 08 LST and a maximum around 18 LST. Relative humidity showed similar diurnal variations as MR in the middle and upper troposphere but was out of phase with MR in the lower troposphere. Total precipitable water vapor peaked around 17 LST. The observed diurnal upper tropospheric variations appear to be linked to large-scale vertical motions, downward from late morning to afternoon and upward from midnight to early morning.
A three-month nowcasting experiment, the Sydney 2000 Forecast Demonstration Project, ended December 2000. NCAR fielded its Auto-nowcaster expert system. Along with other international teams, RTF staff began extensive evaluation of the capabilities of all systems to forecast convective storms. RTF staff found that explicit ingest of boundary layer winds and convergence lines into the expert systems was essential to successful nowcasts of storm initiation, growth and decay. Retrieval of boundary layer winds using high-resolution observations and a boundary layer model showed significant skill. RTF staff identified the lack of detailed stability fields and the failure to include orographic influences on storm evolution as primary areas that need attention. Overall, the project emphasized the need for human participation in the nowcasting process, the need for forecaster training, and the need for close coordination between users and forecasters. Synergism generated by this project will accelerate worldwide development of nowcasting systems.
ATD is collaborating with NOAA's Advanced Technique Development Division in the development of a compact, low-cost, eye-safe, automated remote-sensing lidar that is capable of continuously profile water vapor. Water vapor concentrations will be measured using the Differential Absorption Lidar (thus the name DIAL) technique. See http://www2.etl.noaa.gov/DIAL.html. Dial will be deployed in the upcoming IHOP, in which ATD will be involved scientifically and in a support mode to the many scientists who will participate.
The International H2O Project (IHOP_2002) is a field experiment scheduled to take place over the Southern Great Plains (SGP) of the United States from 13 May to 30 June 2002. The chief aim of IHOP_2002 is to improve characterization of the four-dimensional (4-D) distribution of water vapor and its application to improving the understanding and prediction of convection. The region is an optimal location due to existing experimental and operational facilities, strong variability in moisture, and active convection. Several community workshops have been organized by ATD to plan for IHOP, whose lead funding agendy is the NSF.
