Anticipate Future Needs Resulting from Changing Priorities, Aging Equipment or Emerging Opportunities to Develop New Technology
At NSF’s direction, NCAR and EOL have assembled a set of facilities and instruments that serve the community well, but community priorities and technological opportunities call for continuing development so that these observing systems remain matched to community needs. Even with proper maintenance, systems become obsolete or impossible to maintain, and it is necessary to plan for their replacement or end-of-life. EOL must also be sensitive to changes in priorities and needs of the atmospheric science community and must adjust its capabilities as required to meet those needs. Imperative III calls upon EOL's scientific and engineering leadership and expertise for a healthy development effort and for the retention and training of staff who can conduct that research and development. It also requires the development of life-cycle and end-of-life plans for major facilities, instruments and software (see Imperative IV for more information on data services and software developments).
An extremely high-profile instrumentation development effort in FY 2011 was the advancement of dropsonde technology that enables this perennially-requested instrument to be used in even the newest unmanned airborne platforms. Other projects include the Compact Atmospheric Multi-species Spectrometer (CAMS) for the GV, the Laser Air Motion Sensor (LAMS), and the Ka-Band radar. Other, longer-horizon developments, such as the 449 MHz profiler system, are discussed in our Frontiers.
Starting in FY 2009, EOL and NOAA partnered to develop a first-of-its-kind dropsonde system for use on the NASA/NOAA Global Hawk (GH) unmanned aircraft. The AVAPS team worked on the design, manufacturing and testing of the system, which resulted in a fully-automated dropsonde system where all operations are remotely controlled from the ground, literally with the click of a mouse. This next generation AVAPS system was tested and completed for installation on one of the NASA Global Hawk Unmanned Airborne Systems (UAS) in January 2011. It can dispense up to 88 Miniature In-situ Sounding Technology (MIST) sondes during a single flight, and the data system installed on the aircraft was designed to process up to eight sondes in the air at once. This will have a major positive impact on researchers' ability to take more accurate global warming and ozone depletion measurements, better predict hurricane tracking and landfall, and improve weather forecasting.
In February and March 2011 the dropsonde-equipped Global Hawk completed three long duration flights over the Pacific Ocean during the Winter Storms and Pacific Atmospheric Rivers (WISPAR) campaign. Creation of the Global Hawk dropsonde system provided a strong head start for EOL to create a more automatic, next generation dropsonde system for the NSF/NCAR GV. That system is currently being developed, and is expected to be operational by FY 2013. The improved capabilities of the new GV Dropsonde system will give EOL the ability to support a wider range of science objectives and flight conditions, including high turbulence. The new system will use the smaller MIST sonde and will allow rapid ejection of sondes, up to one per minute as opposed to the current rate of one every 3 to 5 minutes. The ability to deploy a "curtain" of sondes will result in higher resolution profiles of weather and other atmospheric phenomena.
EOL plans to continue to stay abreast of developments in atmospheric UAS technology since there is synergism between traditional research aviation and UAS airborne research, especially with respect to sensor development, miniaturization of instruments, remote operations of instruments from the ground, and the use of satellite communications for real-time data transfer. Further development and/or modifications of other EOL instrumentation for use on the GH or other large UAS platforms are likely in the future.
The Compact Atmospheric Multi-species Spectrometer (CAMS) is a trace gas chemistry instrument that is being developed for Upper Troposphere/Lower Stratosphere (UTLS) research on the GV. This instrument,will detect formaldehyde and potentially other trace gases such as methanol, acetylene, ethylene, formic acid, and/or ethanol. The CAMS instrument is based upon Difference Frequency Generation (DFG) technology and includes a number of advances to further improve measurement performance, extend capabilities for additional gases, and to achieve significant weight and size reductions along with capabilities for autonomous operation.
CAMS was successfully tested during the DC3 Test flights in May 2011 and in subsequent laboratory tests. It was shown to have a detection limit of 40-50 pptv for 30-second average measurements. This detection limit meets the goal of the DC3 PIs, who requested a limit of 50 pptv for 30-second averaged data to sample the background upper troposphere mixing rations of CH20.
High-resolution wind measurements from aircraft enable flux measurements using eddy-correlation methods. Air motion relative to an aircraft is usually measured with a 5-hole gust probe, which employs pressure sensors. Although robust, the method is not highly accurate, in part because the aircraft shape and motion modify the air flow field. Ideally, air motions should be measured some distance from the aircraft, where the airflow has not been modified by deformation around the fuselage. To address this issue, EOL engineers developed the Laser Air Motion Sensor (LAMS) for deployment on the GV and the C-130. By focusing a continuous-wave coherent laser beam about 20 m ahead of the aircraft, the instrument is able to make accurate wind velocity measurements in undisturbed air and measure the aircraft’s true air speed.
The current version of the LAMS sensor measures the air speed towards the aircraft with an accuracy of about 10 cm/s; this is almost a factor of 10 more accurate than what can be obtained using in-flight aircraft calibration maneuvers. Fabrication of LAMS subsystems occurred in FY 2011, including an in-house 5W fiber amplifier, while additional fiber amplifiers are still needed to complete the 3-beam system. In early FY 2012, the existing single beam system will be loaded onto the C-130 for test flights during the fourth Instrument Development and Education in Airborne Science (IDEAS IV) campaign. A complete test of the 3-beam instrument is planned for 2012.
EOL’s radar capabilities were upgraded in FY 2011 to include a second Ka-band (0.86 cm) wavelength radar in response to PI-requested simultaneous dual-wavelength measurements for the FY 2012 DYNAMO field campaign. The development of the Ka-band dual-polarization, Doppler radar, mounted on the lower right edge of the S-Pol radar, extends measurements of precipitation to cloud scale processes in two ways. First, as a stand-alone sensor, the Ka-band radar expands EOL’s remote sensing capability into measuring kinematic and microphysical properties of clouds. Second, when mounted on S-Pol, the two radars become S-PolKa and have matched beam widths, range resolution and pointing angles.
These scanning dual-wavelength measurements are unique in the atmospheric sciences. Most importantly, when S-PolKa is paired with other EOL remote sensing instruments such as HCR and HSRL, EOL can provide unique multiple wavelength capabilities (S- Ka- W- lidar) with applications in several research disciplines. These combined sensors will contribute to understanding the climate system through a better understanding of humidity profiles in clear air, microphysical processes in clouds and cloud aerosol interactions.
EOL is in a unique position to play a leading role in airborne phased array technology, specifically with respect to the airborne antenna. The availability of and direct access to the C-130 combined with in-house scientific and engineering expertise create an exceptional opportunity for EOL to make significant contributions to the next generation radar capability.
Due to the limitations imposed by mounting ELDORA on a non-NCAR aircraft and the instrument’s aging components, it is necessary to explore new technology such as electronically scanned phased array antennae to replace ELDORA after its useful lifetime. Such phased array technology would help advance science in several areas related to mesoscale meteorology, in that higher temporal and spatial resolution measurements are needed to investigate detailed storm structures and evolution. For airborne applications, reduced attenuation using a longer wavelength would allow for deeper beam penetration into severe weather.
To help meet these needs, EOL continued its collaboration in FY 2011 with MIT Lincoln Labs on the development of the next generation phased array radar that we envision will eventually replace ELDORA. Initial activities with MIT centered on risk assessment of the project: the evaluation of phased array element designs that best match science community needs for these high-resolution measurements. EOL's Remote Sensing Facility will prepare a phased array radar development white paper in FY 2012 outlining a staged approach for the APAR development.
To complement the HAIS projects, EOL is developing the HIAPER Cloud Radar, which will be mounted in a wing-pod on the GV, providing high resolution, research-quality data at altitudes not previously available to the atmospheric research community. HCR will be the only cloud radar available on the GV. EOL is using a phased approach to build the HCR. Construction of a ground-based prototype (Phase 0) was completed in FY 2010 and Phases A and B are currently underway. Phase A consists of a pod mounted W-band Doppler radar capable of flying on the NSF/NCAR GV. Pulse compression and dual polarimetric capability are planned for Phase B, and a second wavelength (Ka-band) is planned for Phase C. In addition, the HCR will be deployable in a ground-based container that also houses the High Spectral Resolution Lidar (HSRL), thus providing simultaneous radar/lidar observations. Both instruments run unattended on the ground, enabling longer-term and remote observations.
In FY 2011 EOL received critical components for the single-antenna, airborne configuration of HCR. Performance and functionality of subsystems such as the transmitter, T/R switch network, controls, power and data acquisition, were verified and documented. Mechanical parts and electrical wiring for front-end electronics were manufactured, implemented and tested, and core software for data acquisition, display and control has been tested and functions correctly. Some changes were made in current mechanical and electrical design after review by RAF, and the airborne data acquisition system is being implemented. With the front-end electronics, transmitter and current data acquisition system, HCR is ready for radar performance tests on ground, and in 2012 it will be tested in an altitude chamber to simulate and monitor the performance under low-pressure conditions.