Radar and Profiler Developments

The two radars deployed during the IHOP field experiment (May/June 2002): S-Pol on the left and DOW3 on the right.

S-Band Dual Polarization Doppler Radar (SPOL) - ATD made the first substantial test, use, and validation of a surface refractivity technique for retrieving surface moisture fields from standard weather radars. This technique, instigated and guided by former ATD-ASP Post Doctoral Fellow and current colleague Fred Fabry of McGill University, uses path delay from fixed hard targets (towers, silos, etc.) to develop a low-level map of surface refractivity. At typical surface temperatures, water vapor dominates the surface refractivity signal. A surface refractivity map, developed and displayed regularly from S-Pol data during IHOP and validated using ATD surface sensors, showed exciting promise during IHOP. An eight hour time lapse of the evolution of the S-Pol radar refractivity field collected on 22 May 2002 during IHOP is available. The radar refractivity is closely related tot he near surface water vapor field. During this period, a dry line was forming in the vicinity. The dryer air is to the west and more moist to the east. The circle is the 50km range ring from S-Pol.

Doppler on Wheels (DOW) Developments - For IHOP operations ATD installed the SPOL antenna control system in the DOW2, DOW3 and DOW4 radars. This commonality enabled the scan synchronization required for operation of multiple radars on common targets. ATD also added a rapid solar alignment feature to all the mobile radars to improve pointing accuracy for multiple radar field configurations and to reduce setup time to just a few minutes. ATD and the University of Oklahoma continued efforts on the NSF-MRI RAPID DOW project. The Rapid DOW radar will use a frequency-steerable flat plate antenna developed and constructed at ATD and the new ATD PIRAQ III processor configured for six simultaneous frequencies. Initial deployment is planned for the spring 2003 tornado season.

FDI RIM on Multiple Antenna Profiler (MAPR) - A Frequency Domain Interferometric Range Imaging (RIM) technique was applied to the Multiple Antenna Profiler. The technique improves range resolution of the profiler from 100 meters down to a scale of 10 - 20 meters. Data collected during IHOP resulted in striking high-resolution images of Kelvin-Helmholz rolls, waves, and bores. ATD extended the RIM processing for high-resolution reflectivity to high-resolution wind processing, taking advantage of the fact that Doppler beam swinging, which could introduce range ambiguities, is not required for MAPR wind finding. Preliminary high-resolution winds analysis of data collected during IHOP looks very promising.

Example of RIM processing at IHOP (6 June 2002). The left panel shows signal power with standard processing on MAPR, the central panel shows RIM signal, and the right panel shows observations from a University of Massachusetts FMCW radar. The RIM processing clearly resolves billow like structures that are consistent with the FMCW observations.

Integrated Sounding System (ISS) - ATD scientific staff developed an automated mesoscale modeling system to provide forecasts specifically for ISS deployments and tested the MM5-based system in ISPA 2002, RENO 2002 and IHOP to aid in data collection strategies. During IHOP the system also assimilated AERI data. ATD continued development of a mobile ISS to enable deployment in advance of rapidly evolving weather systems such as hurricanes and convective storms. ATD performed preliminary setup tests to demonstrate that it is possible to deploy the profiler and associated clutter screen within 15 minutes. It is anticipated that full deployment tests will be carried out in FY2003.

Sounding Systems

Driftsonde - Using NSF special funds, ATD engineers focused on developing onboard driftsonde electronics, a communication system for sending instructions to the driftsonde and transmitting data back to earth, design of a gondola, and design of balloon and associated safety systems (transponder, parachute and the method for balloon cut-down). An initial successful test of the driftsonde balloon, electronics, and communication system took place on 28 February 2002 from the balloon manufacturer's (GSSL) facility in Tillamook, Oregon. A second highly-successful test of full satellite communications, automatic ballasting and cut-down, and actual dropsonde deployments occurred in Oregon in November 2002.

Tethered Atmospheric Observing System (TAOS) - ATD deployed the new TAOS in 2000 for the Vertical Transport and Mixing Experiment (VTMX). With improved system capability for greater versatility in the field, ATD again deployed TAOS in IHOP. The TAOS improvements include an improved sensor suite, reduced system electronic noise, high wind capable balloon and winch and extended battery life. The system can now fly up to 1 km with eight simultaneous levels of data.

Reference Radiosonde - With supplemental funding from the NCAR Water Cycles Initiative and from NOAA/OGP, ATD developed a reference radiosonde to serve as a reference standard for various IHOP ground and airborne water vapor sensors. The new sonde allowed direct humidity intercomparisons between two operational radiosonde humidity sensors(Sippican and Vaisala) and the reference radiosonde's Swiss Meteorlabor dew point sensor. These intercomparisons suggest substantial underestimation of upper tropospheric humidity by standard sensors.

Surface Measurement Instrumentations

Surface Flux Systems - NCAR scientists working on NCAR Water Cycle issues requested the addition of soil temperature, soil moisture and water potential measurements to Flux-PAM systems for IHOP. ATD staff designed, constructed and integrated the profiles into the existing Flux-PAM system.

CO2 - IHOP researchers also requested the integration of CO2 measurements into the Flux-PAM data system. Working with Scott Richardson from Penn State University, ATD staff developed hardware and software to ingest data from a CO2 instrument. In collaboration with Penn State and the University of Colorado, ATD developed a flexible system to sample air from multiple locations up to 350m apart and connected this system to a pair of CO2 analyzers to estimate the horizontal and vertical variability of CO2 as part of the Niwot Ridge Pilot Experiment in 2002.

Long Wave Blackbody Calibrator - ATD staff started the development of an automated system to perform calibrations on long wave radiation instruments. The ATD staff designed a blackbody calibration instrument based on a design created by the Solar Radiation Research Laboratory at the National Renewable Energy Laboratory. ATD plans to conduct intercomparison tests with NREL and NOAA upon the completion of the instrument.

Lidar Developments

Eye-safe Backscatter Lidar Development - With NCAR Opportunity Fund resources, ATD staff purchased hardware necessary for a transmitter development that employs a high pressure gas cell to convert 1 micron wavelength laser light to an eye-safe wavelength of 1.5 microns. ATD expects to transmit and characterize the 1.5-micron light within the first months of FY03 and to focus on receiver development during the remainder of FY03.

High-Power Water Vapor DIAL Development - ATD collaborates with the University of Hohenheim in Germany on this development. The University of Hohenheim is responsible for developing a transmitter. ATD is responsible for developing a receiver and for system integration. ATD hired an optical engineer to lead the activity in optical design of the telescopes and receiver.

2. DEVELOPMENTS IN AIRBORNE OBSERVING SYSTEMS

P3 Transition and ELDORA - See Highlights.

LEANDRE II Integration and the Eye Safe Radar (Pip Squeak) - ATD staff designed and built a lightweight 25 KW pulsed, X-band, radar, affectionately termed "Pip Squeak", to provide the required safety margin for horizontal pointing of the Leandre DIAL system on the NRL P3 for IHOP. The radar was configured with a special antenna in a custom aircraft fairing to allow NCAR and French investigators to use the Leandre water vapor lidar in a sideward-looking mode to provide unprecedented horizontal cross sections of water vapor in regions of sharp moisture gradients. IHOP investigators will combine the sideward-looking LEANDRE data with ELDORA winds to improve understanding and predictions of the onset of convective storms. The safety radar design, consisting of a standard transmit-receive unit with a special antenna and custom coherent processing system, performed flawlessly to provide a level of safety in airborne laser operations perceived by some as impossible.

Airborne Imaging Microwave Radiometer (AIMR)- ATD staff continued efforts to improve calibrations and overall quality of data collected by AIMR. AIMR flew during the IDEAS project flights to test these improvements. Data collected will be used to develop new algorithms for retrieval of surface properties.

Images from the Airborne Imaging Microwave Radiometer at 37 GHz (left) and 90 GHz (right) on October 17, 2002. The radiometrically warm features (red) in the upper half of the images are wildfires buringing northwest of Boulder, CO. The Poudre River can be seen along the right half of each image (dark blue). The aircraft flight track is along the vertical axis of the images; vertical white lines are distance markers separated by 1 km.

NASA Cloud Radar - ATD engineers collaborated with NASA engineers and scientists on a data acquisition and signal processing system for a 94 GHz cloud radar. This system was based on a variant of ATD's PIRAQ processing system. The radar was successfully deployed on the NASA ER-2 for the CRYSTAL-FACE field experiment.

MCR - The Multi-channel Cloud Radiometer (MCR) was upgraded with two new channels, centered at 470 and 870 nm. The 470 nm channel enhances capabilities to characterize sea ice and land cover as well as clouds, and is similar to MODIS band 3 and Landsat band 1. The 870 nm channel is responsive to vegetation density and health, and is similar to MODIS band 16, Landsat band 4 and SeaWiFS band 8. New dewars for MCR channels 6 (2.16 um) and 7 (10.9 um) have been installed to improve the signal to noise ratio. These system upgrades were tested in IDEAS.

The first MCR image was taken while the NSF/NCAR C-130 was flying at an altitude of about 6.4 km over the Rio Grande river near Socorro, NM during IDEAS I on April 30, 2002. The 1.06 um channel detects the Rio Grande, near the center of the image, and another dry riverbed near the bottom. A few clouds in blue are also present. Irrigated farmland can also be seen, just above the river. These data were acquired to show the feasibility of the MCR for detecting vegetation. The second panel shows one of the two new MCR channels, this one centered at 0.870 um, which is particularly responsive to vegetation. Note the circular farm fields in the lower part of the image. Some appear to have crops growing (in yellow), while others don't (blue). Clouds appear in red. The third picture was snapped over the same area shown in panel 1, although the coverage is smaller. The picture was taken by a digital camera and is facing with the top of the image towards the tail of the plane, so the image is backwards from the MCR. The Rio Grande river cuts through the image and irrigated farmland can be seen, as well as some shadowing from clouds in the lower left. The high-resolution camera permits analysis of what is contributing to the MCR radiances.

Chemical Analysis Systems

Development and Analysis of C130 Flask Sampling - A flask sampling system was flown during IDEAS for validating the C-130 CO2 and CO instrumentation and also to evaluate the Multiple Enclosure Device for Unfractionated Sampling of Air (MEDUSA). Switching between inlets of different sizes was done to characterize inlet effects on isotope fractionation. These systems support the NCAR Biogeoscience measurement capabilities.

The RAF Oxygen Analyzer (ROXAN) - Britt Stephens, NCAR scientist I, developed a vacuum ultraviolet absorption oxygen analyzer that can measure variations in oxygen concentration at a relative level of 1 part per million (equal to 1 per meg or 1/1000 of a per mil). This instrument has been successfully deployed on several oceanographic research vessels and has the potential to make the first measurements of atmospheric oxygen variations from an aircraft. Testing of the first airborne version is in progress as part of the IDEAS program.

Particle Systems

Upgrades to Particle Measurement Systems - ATD staff made several improvements to aerosol and cloud particle measurement systems. These included testing of inlet systems, development of RAF processing software for the Radial Differential Mobility Analyzer, testing and improvement to existing PMS cloud instruments, and procurement of a High Volume Particle Sampler. A new data system was implemented for the Counterflow Virtual Impactor and its control systems were repackaged. The new arrangement was tested successfully during IDEAS.

Video Ice Particle Sampling System - In cooperation with Andy Heymsfield, ATD conducted the first flight-tests of a Video Ice Particle Sampler (VIPS) during the April IDEAS flights. After correcting problems discovered during the test flights, this sampler was successfully deployed for the CRYSTAL project on the NASA WB-57 F.

Development of a Continuous-Flow CCN instrument - Greg Roberts, from Scripps Institute, has developed a novel instrument for measuring Cloud Condensation Nuclei (CCN) by exploiting the different rates of diffusion of heat and water vapor to generate a nearly uniform super-saturation profile. Successful flight-testing of this instrument and comparison with a standard thermal-gradient instrument was performed during the April IDEAS project.

State Parameters

Improvements to the Ophir Radiometric Temperature - During the EPIC field study, it was discovered that this instrument, ATD's only sensor for in-cloud temperature, was affected by the attitude of the aircraft, due to its sensitivity to off-line portions of the spectrum which caused the instrument to "see" farther than intended. ATD engineers worked with the PI for EPIC to determine the best correction to the Ophir data and have recently found an improved filter to reduce the off-line portion of the spectrum. Testing of this filter system occured as part of the IDEAS.

Automated Airborne Vertical Atmospheric Profiling System (AAVAPS) - ATD successfully deployed a new highly automated, pod-mounted version of NCAR's AVAPS dropsonde sounding system for NASA ER-2 operations in CAMEX-4 and most recently in CRYSTAL-FACE. In each case, dropsondes were deployed on pilot command from the NASA ER-2 at altitudes exceeding 21 km (69,000 ft). Prior to the CRYSTAL-FACE deployment, significant modifications were made to the system and sonde electronics for increased reliability in the harsh stratospheric environment. AAVAPS deployed on the ER-2 has proven the effectiveness of automated pod mounted dropsonde release mechanisms, opening the door for similar systems to be installed` on other aircraft such as HIAPER.

Aviation Infrastructure

HIAPER - In FY 2002 the HIAPER Project Office was established. The "green" G-V airframe was completed by Gulfstream in June of FY 2002 and subsequently was flown to Lockheed in Greenville, SC for modification work. The HIAPER Advisory Committee (HAC) participated in all activities and monthly SPO reports were filed with NSF. NCAR approved the $10M infrastructure budget; and eleven subgroups were created to focus on infrastructure development, instrumentation possibilities, and preparation for operations.

Aircraft Safety and Security Issues - ATD completed the fall protection system at the RAF hangar. Two RAF staff members (one pilot and the assistant chief of maintenance) traveled to the FAA facility in Oklahoma City to receive training as Aviation Safety Officers. A major review and rewrite of the RAF Flight Operations and Safety manual was begun in FY 2002 and is nearing completion. This revised manual will contain improved safety and security measures, and will incorporate an updated incident/emergency procedures section. To improve safety in the area of aircraft maintenance, work on a General Maintenance Manual was begun in FY 2002 and is nearing completion.

C-130 Upgrades - Improvements to the capacity of the galley, toilet and power distribution system were all completed this year. A single point ground was added to the power and signal systems, which should improve the electronic noise environment on the aircraft. In response to complaints from users of the C130, ATD completed a major upgrade to the intercom system. Each seat now has a complete intercom system.

Design of a new Hangar - ATD and UCAR have worked with JeffCo airport management and other regulatory groups (FAA, Fire Department, etc.) to develop specifications for the new hangar. Bids are currently being sought for the design and construction of the new hangar, so that it can be completed in time for the arrival of HIAPER. Together, the new and old hangars should accommodate up to three large aircraft (C130, the G-V, NRL P3).

3. DEVELOPMENTS IN DATA AND NETWORK SERVICES

4. DEVELOPMENTS IN DESIGN AND FABRICATION