ATD DEVELOPMENT ACTIVITIES

    Facility Developments

    High-performance Instrumented Airborne Platform for Environmental Research (HIAPER)

     Planning for HIAPER has moved right on schedule during FY 1999. HIAPER is NSF/NCAR's next generation, high-altitude research aircraft that will serve crucial geoscience research needs over the next several decades. At the request of NSF, NCAR submitted a plan to function as the Systems Integrator for HIAPER on 16 October 1998, outlining NCAR's role in the acquisition, modification, instrumentation and eventual operation of the new aircraft. The overall process, from development of specifications through flight testing to research operations, will take approximately five years. Principal milestones achieved toward HIAPER planning and acquisition during FY 1999 included the following:

    • During the fall of 1998, NCAR formed the HIAPER Integrated Project Team (HIPT) comprised of ATD, NCAR, UCAR, and USAF Commercial Aircraft Integrated Project team staff.
    • In December 1998, UCAR prepared and issued a Request for Information to various aircraft vendors.
    • After responses were reviewed and information compiled, NCAR organized a Vendors Conference in January 1999 in Boulder. Five potential aircraft manufacturers sent representatives to this conference to exchange information.
    • A draft HIAPER Requirements Document (HRD) was written by members of the HIPT and distributed to the airborne science to prepare for an upcoming HIAPER community workshop.
    • On 24 - 26 May 1999 the HIAPER Community Workshop was held at NCAR. Participants discussed and agreed on required desired capabilities, which were incorporated into the HRD document.
    • During the summer of 1999, staff prepared a Draft Request for Proposal (RFP), which includes the final HRD as well as additional documents such as a Proposal Evaluation Plan (PEP) and an Aircraft Characterization document. The document was sent to to the vendors for review in early fiscal year 2000.
    Based on notification that funding was appropriated for HIAPER, NCAR is now recruiting for expertise in acquisition management and science coordination. Updated HIAPER activities, developments, and schedule can all be found on the ATD HIAPER web site.

    Improvements to the C-130 and Electra

    Several important, planned upgrades to the current NSF/NCAR fleet were completed in FY 1999. These include the installation of the TCAS-II and satellite communication systems, improvement of the radios in the Electra, addition of capability for upward and downward looking radiometers on the C-130, improved magnetic disks for data storage, restoration of two crews for simultaneous operation of both aircraft, and refurbishment of the Multichannel Cloud Radiometer (MCR) on the C-130. Planned upgrades of the radios and radar altimeter on the C-130 were not completed, but will likely use equipment from the NASA C-130 (below), resulting in substantial cost-savings.

    Transfer of a NASA C-130 to NSF

    Negotiations between NSF and NASA for transfer of a NASA C-130 to the NSF fleet were successfully completed. Many parts from this aircraft, especially low-time engines, will be used to enhance the NSF/NCAR C-130. RAF staff will examine this aircraft and its modifications to determine how much of the existing parts and structures can be transferred. In addition to the engines, instrument racks, avionics, and sampling ports are likely candidates for transfer. These improvements will substantially improve the capability and reliability of the NSF/NCAR C-130, while reducing the cost of maintenance and upgrades.

    S-Band Dual Polarization Radar (S-Pol)

    Most S-Pol activities centered on preparations for overseas field deployments. However, two improvements are noteworthy: A new dual polarization feed was obtained which provides improved horizontal and vertical axis orthogonality. The old feed had a 1 to 2 degree error while the new feed is orthogonal to within .1 to .2 degrees. The new feed was installed during MAP and produced a very noticeable improvement in LDR. All cross-pol variables now seem to be consistent with theoretical expectations. Also the S-Pol VIRAQ signal processor was reprogrammed to compute both vertical and horizontal cross-pol powers. This allows the fully calibrated backscatter matrix to be calculated. Additionally, absolute phase measurements were added to allow investigation of refractive index water vapor measurements. S-Pol now has a choice of four clutter filters. S-Pol data quality continues to be investigated intensively at NCAR, NSSL and CSU.

    Electra Doppler Radar (ELDORA)

    The ELDORA calibration procedure was automated and a full background calibration check was implemented in real time. ELDORA post acquisition processing software was upgraded and streamlined to be more turn key to produce corrected data sets after the completion of field programs.

    Doppler on Wheels (DOW)

    The ability to stagger the time between pulses (PRT) was added to the DOWs. This allows the maxium unambiguous velocity to be increased dramatically. Additionally the antenna scanning control systems on the DOWs were entirely redesigned and rebuild by RSF staff. The new system is much more reliable and user friendly.


     

    Integrated Surface Flux Facility (ISFF)

    Several significant improvements have been made over the past year to the NCAR Integrated Surface Flux Facility (ISFF). These include improvements to the hygrothermometer radiation shield, the ability to transmit high-rate turbulence data from Flux-PAM stations, and the development of a new sonic anemometer array.

    Observations showed that the rate of mechanical aspiration of the hygrothermometer radiation shield decreased significantly during high winds. This is caused by the formation of a region of low pressure at the vertically-oriented inlet. Wind tunnel measurements and numerical flow simulations were used to investigate this problem, and it was found that flaring the inlet significantly increases flow through the radiation shield during high winds. Environmental and wind tunnel tests are proceeding to optimize the dimensions and shape of the revised inlet.

    The second development was made at the request of scientists prior to the CASES 99 field program. This project required a network of remote flux stations to archive high-rate turbulence data, while the Flux-PAM ISFF stations were designed to transmit only summarized (5-minute) covariance data. The Flux-PAM data system software was modified to permit the transmission of the required high-rate data in a format compatible with that already used by the ASTER data acquisition system. For CASES 99 the data were transmitted over a hard-wired network, but for more wide-spread station deployments, high-rate data can also be transmitted by means of RF modems.

    Finally, new sonic anemometers were developed which combine the University of Washington non-orthogonal array design with the electronics and acoustic transducers used in Applied Technologies sonic anemometers. The principal advantage of the UW array is reduction of flow distortion, commonly called transducer shadowing, while also minimizing the separation of the three measurement paths.

    Mobile GPS/Loran Atmospheric Sounding System (MGLASS)

    SSSF staff transferred the Mobile GLASS from a standard van to a cab-over-camper van in FY 1999. The system should prove to be quite flexible. The unit can be installed on any full size heavy duty pickup truck, which means that the unit can be shipped anywhere and installed on a rented vehicle or put in place as a "fixed" site. The design gives the operators a lot of working space and a comfortable place to sleep if deployed for extended periods. The new system was deployed for the first time during CASES and performed very well. It proved to be comfortable, maneuverable, and an excellent platform for doing mobile soundings.

    Multiple Antenna Profiler Radar (MAPR)

    In FY 1999, SSSF's Multiple Antenna Profiler Radar (MAPR) spent more time in the field than ever. In April it ended a seven-month deployment at NOAA's Boulder Atmospheric Observatory 300-meter, instrumented tower near Erie, Colorado. Efforts were concentrated on software development with modifications to the data handling, diagnostics, and wind analysis routines. These efforts improved the data through-put and allowed near real-time wind measurements. Comparison of wind measurements made by MAPR and anemometers on the tower were used to refine analysis algorithms and to show that the radar works well in clear-air as well as in precipitation. Work has begun on incorporating the new ATD-designed PIRAQ data cards into MAPR which will improve the signal characteristics and data handling of the radar.

    The BAO deployment was also used to make a study of frontal systems passing along the Colorado front range. The dynamics around individual fronts are being closely examined to build up a climatology of frontal passages. MAPR was deployed at the BAO again from 1 December 1999 to continue the frontal study and development of the wind analysis algorithms.

    In addition to the BAO deployments, MAPR also had its first ship-borne deployment on the Japanese research vessel Mirai for the Nauru-99 project (see FY 1999 Field Projects).

    Tethered Atmospheric Observing System (TAOS)

    The idea for a Tethered Atmospheric Observing System has existed within ATD for several years. In FY 1999, interest in the research community and some initial funding from the ATD Director's Office has kickstarted an aggressive set of design goals. These include eight possible instrument levels providing pressure, temperature, humidity, wind speed and direction data at one second intervals for simultaneously. In addition there will be user-defined inputs for other sensors. This balloon system will be designed to fly to one km and have extended battery life to stay at altitude for long periods of time. Two way communication to each sensor will allow the user to send commands to a sensor to turn on pumps, reduce power, or anything else the user might imagine. Desirable goals for the future include power up the tether line for extended flights and kite capability for deployment in higher winds. Although the system is still in its development stage, the first possible deployment could come as early as fall of 2000.

    Reference Radiosonde

    Ground testing and balloon flight testing of a commercial full-up GPS receiver was done this past year for Reference Radiosonde in conjunction with the SEET field program. The GPS Dropsonde was used as the platform for evaluating a commercial OEM GPS receiver to be used in Reference Radiosonde. The standard GPS codeless receiver used in the Dropsonde was replaced with a code-correlating GPS receiver. Analysis of the GPS data from the balloon data showed excellent GPS wind and position results. The performance of the GPS receiver was validated by the high degree of correlation between the GPS vertical velocity and the pressure sensor derived vertical velocity in the SEET balloon flights in addition to several ground tests. The current OEM GPS receiver used for SEET has demonstrated to provide excellent GPS data throughout balloon flights and makes it a good choice as the GPS receiver to use in Reference Radiosonde.

    Instrumentation Developments

    Scanning Aerosol Lidar (SABL)

         With the help of DFS, RSF and RAF engineers completed the side scanning configuration for SABL in a C-130 wing pod. SABL was deployed in this configuration during the INDOEX program. The SABL preamplifiers were redesigned and constructed at NCAR.


    Other Lidars

    The activities of the RSF Optical Remote Sensing Program, which is a joint program between ATD and NOAA/ETL, included completion of the refurbishment of the High Resolution Doppler Lidar (HRDL), and subsequent fielding of this lidar during the Nauru99 program. A new methodology and higher bandwidth control loop solved most of the problems with vibration sensitivity of the laser cavity. Such good control has been achieved that potential airborne use of the lidar is anticipated. Work continued on an USWRP-supported development of a water-vapor DIAL profiling system intended for future use as a part of the ISS.

    Airborne Imaging Microwave Radiometer (AIMR)

    The post acquisition analysis software for AIMR was developed and matured greatly during FY-99. A skeleton scientific analysis tool was written to create products that estimate the biomass observed by AIMR. This scientific analysis tool is being used by Julie Haggerty at the University of Colorado to estimate column integrated liquid water between the aircraft and the ground.


    Airborne Turnable Diode Laser (TDL) Water Vapor

    ATD purchased a Tunable Diode Laser (TDL) instrument for measurement of water vapor and testing of this instrument has begun. The preliminary results from these tests are very encouraging and it is assumed that this new instrument will achieve substantial improvements in resolution, accuracy, detection limit, and response time. It will first be deployed during the TOPSE project in early 2000.

    Cooperative Trace Gas Instrumentation Development

    ATD/RAF is jointly working with the Atmospheric Chemistry Division to develop and improve the trace gas sampling capability for routine deployment on RAF aircraft. Ozone measurements by the standard UV absorption methods are currently available and were deployed during field projects this year. A NO/O3 chemiluminescence instrument for fast ozone measurements is currently under construction and should be available this year for routine deployment. The current IR-absorption instrument for measurements of CO will be phased out in favor of a vacuum-UV fluorescence method, which will offer substantial improvements and will be available for routine deployment later in the year. A modified non-dispersive IR CO2 instrument is currently available, but in need of several improvements in flow, temperature, and pressure control, which will be implemented during the coming year. On a longer time frame, ATD/RAF staff is currently studying the feasibility of developing a TDL system for measuring CO2 isotope ratios, which would be an important tool and new capability for CO2 budget studies. About two to three years of development will be required before an instrument is available.

    Improved Cloud Particle Instrumentation

    A Cloud Particle Imager (CPI), manufactured by SPEC, Inc., has recently been purchased by ATD. This instrument provides new high-resolution imagery of cloud and precipitation particles, but software for determining concentrations and sizes of particles is still under development. RAF and MMM scientists are evaluating the performance of this instrument and are developing software to process the data and integrate it with data from existing RAF cloud particle probes. This is a part of a larger cooperative effort between ATD and MMM to improve the RAF's cloud particle measurements and data products. NCAR's Counter-flow Virtual Impactor (CVI) instrument was tested in the NASA wind tunnel along with several other standard instruments for measuring liquid water content. These test have indicated that the instrument can provide rather unique measurements of liquid or ice water content, although careful interpretation of the data is necessary due to the effects of residual water in the sampling lines.

    Other Airborne Instrumentation Issues

    Aerosol data using the community aerosol inlet system on the C-130 has now been collected from several field studies. Analyses of these data are in progress or nearing completion. The results to-date suggest that, for large aerosol, a different inlet system may be needed. This will be an area of focus for the coming year. We are also in the process of evaluating Doppler-Lidar wind systems for NCAR/NSF's current aircraft and for application in HIAPER. The current GPS instruments on both aircraft are nearing the end of their useful life and RAF is currently evaluating possible replacement systems.

     

    3. Other Developments

    PC Integrated Radar Data Acquistion System II (PIRAQ II)

     A new version of the PIRAQ board, PIRAQ II, was developed. This board is similar to its previous version but has two DSP processors instead of one and more local memory. This board is now being used by the two Doppler On Wheels (DOW) radars, a joint program between RSF and the University of Oklahoma. The PIRAQ II boards are also being implemented into the MAPR processor by SSSF and the Mini-MOPA Lidar that is operated by NOAA's ETL. The mini-MOPA was used during the Nashville-99 program.

    SSSF Sensor Calibration Facility

    The SSSF sensor calibration lab has gone through some changes over the past few years. The main temperature chamber has been replaced with a Thermotron model S-32 chamber. This chamber operates over a temperature range of -70o C to 150o C, and has a test volume of 38" X 38" X 38". The approximate rate of change is 4o C per minute. The chamber has an IEEE-488 interface to allow for computer control.

    A new temperature bath was acquired approximately one year ago. The bath is a Hart Scientific 7040. The temperature range is from -40o C to 100o C. The bath test volume is 11" X 11" X 11". The rate of change in the bath is very slow, ~0.08o C per minute. However, stability is excellent. Similar to the new chamber, the bath has an IEEE-488 interface.

    Development work continues on automating the equipment in the laboratory. A PC has been dedicated to provide control and acquire data. To date, control software has been written for the Thunder Scientific humidity chamber, the oil bath, and the temperature reference bridge. The PC can handle up to 8 serial instruments. Analog sensors can be connected through a Keithley 2001 multimeter. The software development has been based around National Instruments LabView package. Software also continues on a sensor data base to maintain calibration, history, and repair records.

    RAF Hanger and Facility Support

    A new hanger will be required to accommodate the HIAPER aircraft. RAF and NCAR Facilities staff have begun to review the existing hanger and support buildings to develop a plan to accommodate the new aircraft, and to provide improved laboratory space for HIAPER and other RAF instrumentation.

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