Imperative III

Anticipate Future Needs Resulting from Changing Priorities, Aging Equipment or Emerging Opportunities to Develop New Technology

The set of facilities and instruments assembled and maintained by NCAR and EOL serve the community well; however, there is a constant, ongoing process of acquiring new capabilities and retiring and replacing those that become outdated. Community priorities and technological opportunities call for continuing development so that the available observing systems remain matched to scientific needs and advancements. 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. In addition to such evolutions, systems become obsolete or too costly to maintain, and it is therefore necessary to plan for their replacement or end-of-life. Thus, 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).

Development efforts in FY 2012 included continued work on the new dropsonde system for the NSF/NCAR GV, construction and testing of a prototype mid-troposphere 449 MHz profiler consisting of 7 antenna/transmit/receive modules, and work to advance the development of CentNet, an expandable network of up to 100 ground-based stations with flux-measuring capabilities. The HIAPER Cloud Radar (HCR), Front Range Observational Network Testbed (FRONT), Airborne Phased Array Radar (APAR) and Water Vapor Differential Absorption Lidar (WV DIAL) also figured prominently in EOL’s development work in FY 2012. The longer-term plans for several of these developments are also discussed in our Frontiers. We have also strengthened and expanded our partnership with DLR, the German Aerospace center, in hopes of pursuing joint development of critical-need new instruments that could fly on both the DLR HALO and NSF/NCAR HIAPER aircraft. 

 

AVAPS Dropsonde System for HIAPER (NSF/NCAR GV)

A new and improved Airborne Vertical Atmospheric Profiling System (AVAPS) remains a high priority instrument so that HIAPER can meet the scientific community’s needs for high altitude dropsonde operations. The current AVAPS system, located in the baggage compartment, requires that the dropsonde be manually loaded into the launcher. As a result, the AVAPS operator is required to move between the console and the aft baggage compartment to load active dropsondes into the launcher. Safety procedures limit the number of times per hour the baggage compartment can be opened during the flight, thus limiting the number of sondes that can be dropped during flight. During turbulent conditions, all cabin personnel are required to remain seated for safety, and dropsonde operations are suspended.

The new HIAPER AVAPS system will implement remote features for safe operations above 40,000 feet, reducing the amount of time the operator needs to spend in the aft baggage compartment, and therefore significantly reducing exposure to hazardous conditions. This will also serve to increase the total sonde capacity during a single flight. The new system design is leveraged from the development of the fully automated dropsonde system for the NASA/NOAA Global Hawk (GH). The GH AVAPS system was successfully deployed in January 2011 during the Winter Storms and Pacific Atmospheric Rivers (WISPAR) campaign, and in August 2012 during the HS3 campaign. Building on this work, the system for HIAPER will be automated, will use the mini-dropsonde, and will allow 8 sondes in the air simultaneously. The increased safety of operation and doubling the number of sondes that can be in the air simultaneously are major improvements over the current system. This added capability will allow finer scale evaluation of rapidly evolving mesoscale systems.

NSF/NCAR GV AVAPS system schematic

Figure 21: NSF/NCAR GV AVAPS system schematic

 

The development of the AVAPS for HIAPER satisfies the following EOL priorities:

(1) Support observing needs of research programs at a level that serves NSF, Universities and NCAR program needs.

(2) Improve observing capabilities for weather and climate phenomena with high socio-economic impact. Specifically develop a new dropsonde system for HIAPER and use its capabilities to support studies that bridge the gap between mesoscale weather and climate studies.

(3) Continue and complete the acquisition of the HAIS and other instruments that were developed as part of the HIAPER acquisition and plan for their operation in support of the research community.

(4) Develop capabilities that implement new technologies and lead to smaller size instrumentation.

 

(5) Develop remotely controlled and operated instrumentation to eliminate the need for onboard operators, allowing for additional aircraft payload and/or extended mission range.

(6) Develop capabilities that emphasize safe facility operations.

(7) Collaborate and cost share development efforts with other agencies.

EOL has several decades of experience developing dropsonde hardware and software for use on high-altitude balloon and aircraft platforms, and is therefore especially well suited for this task. In FY 2012, EOL made progress in the design and fabrication of the launcher for the HIAPER AVAPS system, which was built but has not yet been tested.  Updates were also made to the mini-sonde, and progress was made on the design of the control and communication, which determine how the HIAPER AVAPS system will interface with the HIAPER data system, and how ground-to-air control will take place.

 

449 MHz Wind Profiler

EOL is developing 449 MHz wind profiler technology to improve measurements within and above the atmospheric boundary layer, improving height coverage and measurement frequency for wind and temperature profiles.  The new 449 MHz network will eventually replace the current 915 MHz wind profilers, increase the deployable network size (number of systems), and provide more deployment flexibility for investigators.

The 449 MHz wind profiler development incorporates a modular and flexible design based upon individual panels that are combined in various configurations.  Advanced signal processing techniques are an integral part of the new profiler and are critical to its combination of high sensitivity, high vertical resolution, and ground-clutter cancellation. The 2011 tests of our prototype 3-antenna wind profiler showed that its sensitivity and altitude coverage exceeded that of our collocated 915 MHz profiler. In FY 2012, EOL began construction and testing of a prototype mid-troposphere profiler consisting of 7 antenna/transmit/receive modules. The goal is to have this system tested in early FY 2013, with plans to have a more deployable (hardened) capability of one 7-antenna or two 3-antenna 449 MHz profilers available in 2013. A future goal is to expand to a 19-antenna (full troposphere) capability, also providing two 7-antenna (mid-troposphere), and six 3-antenna (boundary layer) options. Upcoming algorithm development will take full advantage of the flexibility of this modular system.

The modular wind profiler development is well aligned with broader needs identified by national workshops. The 2009 National Research Council report Observing Weather and Climate from the Ground Up: A Nationwide Network of Networks identifies vertical profiles of wind and temperature and boundary layer height as among high priority measurement needs. A 2003 workshop by the U.S. Weather Research Program (Dabberdt et al., BAMS 2005) includes measurement of the three-dimensional wind field in the lower troposphere among the most needed observations. The 449 MHz wind profiler advances create improved options for these national needs.

3-panel 449 MHz profler system during PCAPS

  Figure 22: A 3-panel 449 MHz profler system during PCAPS

 

CentNet

There is now broad recognition within the geosciences that the multi-scaled features characterizing landscapes present unique challenges that hinder progress in multiple fields connected to climate, air quality, atmospheric composition, surface hydrology, and ecology.  Flows over complex terrain or within the rough sublayers of vegetative or urban canopies have obvious physical inhomogeneities. Fragmentation in landscapes introduces roughness, albedo and soil moisture gradients that can in turn introduce complexity in seemingly simple situations. To make scientific progress when these features are present requires measuring and modeling spatial gradients in state variables and their concomitant fluxes at unprecedented spatial scales.

The consensus of an EOL-convened 2008 Adaptive Sensor Array workshop was that a large network of ground-based sensors would facilitate research in the biogeosciences, hydrology, and urban meteorology, in addition to the mesoscale meteorological research traditionally supported by tower networks.  Measurements of turbulent fluxes and radiation were among those listed as essential by workshop attendees.  The workshop participants’ research interests included understanding turbulent flow over complex terrain, predicting convective initialization, characterizing the exchange of trace gases within a vegetative canopy, understanding above and subsurface water pathways, and the effect of the planetary boundary layer on pollution transport in an urban environment. These perspectives were reiterated at a Discussion Forum in 2010, scheduled during joint American Meteorological Society Symposia on Boundary Layers and Turbulence, Agricultural and Forest Meteorology, and Urban Environment.  All of these groups have endorsed the concept of a large network and provided valuable guidance on needed capabilities.

EOL plans to address this challenge by constructing a new surface network facility of up to 100 self-contained flux systems to be deployable at a broad range of spatial scales (1m to100km) in support of a wide variety of biogeophysical field studies.  Called CentNet, this system at its core would allow direct research-quality measurements of all components of the surface energy and water budgets. This would be complemented by measurements of key elements of the carbon budget, including eddy-covariance measurements of the fluxes of momentum, carbon dioxide, sensible and latent heat, soil heat flux, and incoming/outgoing visible/infrared radiation.

Scalable up to 100 stations, CentNet is designed to minimize the staff time required for deployment, operation, and data handling. Radio Frequency (RF) communications will be utilized as much as possible to reduce cabling, which in turn reduces set-up time, failure modes, and weight.   Each station will have two-way communication via the Internet for real-time data display and control.  The data system will run EOL’s NIDAS software, which time-tags and archives every sample so that users have the largest choice of data analysis methods. This system also has the ability to cycle power on any sensor, e.g. one that is not reporting. In FY 2012, EOL continued work to develop automatic cleaning systems to minimize field maintenance of sensors.  We also designed new tower infrastructure to be lightweight, easily deployed, and have a minimal footprint. The development effort so far has focused on sensor evaluation and infrastructure design with the goal of completing prototype station construction by the end of 2012.

 Two possible experiemental designs that could use CentNet

Figure 23: Two possible experiemental designs that could use CentNet. The design on the left would study CO2 advection within a sparse forest canopy using the box budget method with several clusters of multiple-level CO2 flux towers.  The design on the right would employ an extensive array of multiple-level towers to produce a flow map over complex terrain. This map would be used as a validation data set for wind turbine siting models.

 

HIAPER Cloud Radar (HCR)

The HIAPER Cloud Radar in its pod configuration.

Figure 24: The HIAPER Cloud Radar in its pod configuration.

To complement the HAIS projects, EOL is developing the HIAPER Cloud Radar, which will be mounted in a wing-pod on the GV, and will provide high resolution, research-quality data not previously available to the atmospheric research community.  In FY 2012 EOL transitioned the HIAPER Cloud Radar (HCR) from a ground-based instrument to an airborne configuration. As part of this process, we completed a thermal evaluation of the data system and relocated the data system inside the pressure vessel to ensure that integrity of the data system is maintained in all flight conditions. Essential airborne components such as the pressure vessel, the pod mounting hardware, the antenna reflector, the antenna controls, and an inertial navigation system (INS) have been configured and integrated on the GV. EOL also upgraded the data acquisition system to handle the HCR’s high data rate, and we tested the real time B-scan and Ascope displays as well as the radar control GUI software.

The transmitter/receiver (T/R) switch network and the installation of the second receiver channel provide HCR with polarimetric capability. With the extensive electrical and mechanical efforts in transitioning the HCR to an airborne platform in FY 2012, and the front-end electronics and transmitter validation performed in FY 2011, HCR is ready and scheduled for its first electrical and mechanical integration with HIAPER in October 2012. The first test flights for HCR will follow in February 2013.

 

Front Range Observational Network Testbed (FRONT)

The Front Range Observational Network Testbed (FRONT) is an observational infrastructure for the collection of comprehensive mesoscale and climate process study data sets and for the testing of new observational technologies and retrieval methods. The backbone of the network is the unique dual-polarization, multi-wavelength and Doppler remote sensing capabilities of the Colorado State University (CSU) CHILL National Radar Facility near Greeley, CO and the NCAR EOL S-PolKa Radar Facility near Firestone, CO.  While these two radars provide the foundation, there is vast scientific and engineering potential in the integration and testing of other research and operational instruments within the FRONT coverage domain.

The FRONT domain

Figure 25: The FRONT domain, showing the layout of radars for FRONT overlaid on Front Range topography. Colored circles indicate dual-Doppler lobes between nearby radar pairs.

In addition to CHILL and S-PolKa, data from the CSU Pawnee radar (located near Nunn, CO) and the KFTG (Denver International Airport) and KCYS (Cheyenne, WY) WSR-88D radars will be integrated into FRONT and their measurements routinely archived. This expansive radar coverage will provide dual-Doppler wind retrievals extending from Cheyenne to south of Denver. The dual-polarimetric radar capabilities will be used to assess microphysical characteristics of storms. S-PolKa (when not deployed remotely) and CHILL at FRONT will be operated daily during the convective season and during significant weather events.  FRONT will also be available through the NSF Lower Atmospheric Observing Facility (LAOF) request process, thereby expanding the utilization of the NSF facilities.

The FRONT network is ideally suited to provide Front Range observational datasets to advance the knowledge in hydrometeorology, mesoscale weather and climate process studies and to test new observational technologies and retrieval methods. The establishment of this readily-available infrastructure will provide a dual-polarization, multi-Doppler, multi-wavelength radar network for hydrometeorology and climate process studies; for developing and testing new algorithms; for testing and validating new instruments; for studying sensor integration technologies; for applied data assimilation activities; for validating numerical models; for testing advanced networking concepts; and for enhanced educational opportunities.

It is envisioned that the existing ground-based instruments maintained and operated by the two organizations, such as the Integrated Surface Flux Systems (ISFS), Integrated Sounding System (ISS), GPS ground-based receivers, High-Spectral Resolution Lidar (HSRL), HIAPER Cloud Radar (HCR) operated by EOL, and LMA (Lightning Mapping Array) operated by CSU, could be made available in conjunction with FRONT through the NSF LAOF request process. New instruments, such as the joint Montana State University-EOL Water Vapor DIAL (WV DIAL) venture, are expected to be tested and to become available for request, and could also be used in conjunction with FRONT. The combination of satellite data, Front Range observing networks of surface stations, precipitation gauges and stream flow observations, operated by various public and private entities, provide a data-rich environment for FRONT. The combination and integration of these diverse and complementary datasets will allow the NSF research and education communities, as well as the National Weather Service (NWS) and other interested parties, free and open online access to rich datasets that will address a multitude of scientific and educational objectives.

Preparations for the FRONT Firestone site continued in FY 2012 and will be completed in FY 2013. S-PolKa will be moved once the site is completed and FRONT operations will begin after setup and testing of the radar at Firestone.

 

Research radars of FRONT

Figure 26: Research radars serve as anchors for FRONT. The Colorado State University CHILL radar is on the left and the EOL S-PolKa radar is on the right.

 

Water Vapor Differential Absorption Lidar (WV DIAL)

Engineers from Montana State University (MTU) have developed a lab-based, low-cost, eye-safe, diode-based water vapor Differential Absorption Lidar (WV DIAL) system for remote sensing of water vapor in the atmosphere. EOL is partnering with MTU to enhance the system for operating in the field and for long periods of time that would be required for use in a field campaign.  The goal of this effort is to evaluate the technology and, if appropriate, build and deploy a network of WV DIALs for the NSF community.

Work on the WV DIAL system in FY 2012 included a 6-week test period in Boulder, CO; radiosonde and microwave profiling radiometer (MWR) intercomparisons; a 3-week test period at Howard University (Beltsville, MD); radiosonde, Raman lidar and MWR intercomparisons;  a 1-week demonstration at the Dallas - Fort Worth, TX National Weather Service Forecast Office; and radiosonde, infrared spectrometer (AERI) and MWR intercomparisons.

In the future, work on this system will include: lowering the minimum range from ~800 m to ~100 m; improving its daytime range to 2-3 km; stabilizing/ruggedizing the system to account for temperature variations; packaging the system into a temperature-controlled container for unattended operations; developing software for subsystem automated control; and analyzing the potential for scanning.

The figure below shows the first continuous observations from by the WV DIAL system operated at the NCAR Foothills campus. By operating it continuously, EOL is learning a great deal about tuning, aligning, operating, and analyzing data from the system. These “first look” data are preliminary but show great promise in providing continuous moisture profiles in day and night.

 WV DIAL continuous observations

 Figure 27: The first continuous observations of the WV DIAL, from NCAR's Foothills Lab.

 

Airborne Phased Array Radar (APAR)

EOL is in a unique position to play a leading role in airborne phased array radar 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 such a next-generation radar capability.

Panels on the C-130 representing APAR

Figure 28: The NSF/NCAR C-130 with a model (styrofoam panels) of the Line Replaceable Units (rectangular elements) and the full sized aperture (the four by four matrix) for APAR.

As a result, the development of an APAR with dual-Doppler and dual-polarimetric capabilities to replace the Electra Doppler Radar (ELDORA) has been identified as a specific action for Frontier I in the current EOL Strategic Plan. At X-band, ELDORA has experienced severe attenuation in heavy rain situations, and its lack of dual polarization capability severely restricts its scientific usefulness in advancing quantitative precipitation estimates and water cycle research in those regions not covered by ground-based operational radars. APAR will address these issues. APAR design envisions it being flown on the NSF/NCAR C-130, and would consist of four distinct apertures strategically located about the fuselage. This APAR design could also be adapted to C-130s in the U.S. Air Force hurricane reconnaissance fleet.  The potential to improve hurricane track and intensity forecasts by continuously assimilating APAR data from those reconnaissance missions into operational numerical models may provide even greater societal impacts for the general public beyond the benefits to be gained by the scientific research community.

Development of APAR requires substantial effort and resources. As such, EOL has taken a phased approach to APAR development and is partnering with MIT/Lincoln Laboratory and V. Chandrasekar (EOL Affiliate Scientist from Colorado State University) on this effort. In FY 2012, this partnership worked to develop a small, low cost, prototype, dual-pol phased array antenna. The antenna will serve as a building block for a larger sub-panel, designated as a Line Replaceable Unit (LRU).

The next phase would be development of an APAR LRU, as several LRUs can be combined to form a full sized aperture. This is a multi-disciplinary effort, requiring the skills of scientists, technicians, instrument makers, and mechanical, electrical, antenna, RF and software engineers. Input from the community is a critical part of APAR development and EOL is currently developing an APAR white paper to outline the full project. EOL will seek collaborative partners for the full APAR project when the full proposal is developed.

 

DLR Collaboration

DLR, the German Aerospace center, is Germany's national research center for aeronautics and space. Its extensive research and development work in aeronautics, space, transportation, energy, defense and security research is integrated into national and international cooperative ventures. One of the cooperative ventures is working with EOL on a variety of complementary topics associated with aircraft and airborne instrumentation.  DLR operates HALO, the High Altitude and Long Range Research Aircraft, which is a Gulfstream G-550 that is similar to the HIAPER, NSF/NCAR Gulfstream V aircraft. Below are some key areas of collaboration that EOL and DLR are exploring.

NCAR's capabilities in airborne radar and DLR's in airborne lidar are complimentary, and EOL's extensive experience in instrument flight certification would also be helpful to this collaboration.  The timing for developing joint projects between EOL and DLR is excellent, as EOL is in the process of planning for the next round of instrument development activities.  Leveraging expertise from both EOL and DLR would reduce the time and cost associated with developing new, critical-need instruments, and would allow EOL and DLR to pursue joint development of such instruments that could fly on both HALO and HIAPER.