State-of-the-art, accurate observations and measurements of the atmosphere and other parts of the Earth system continue to be the driver for scientific discovery and impetus for advances in geosciences. Such observations are also critical inputs for the robust performance and continued development of weather, climate, and chemistry models.  Therefore, our first Imperative is the maintenance of NSF-funded Lower Atmosphere Observing Facilities (LAOF) for research in atmospheric science, with emphasis on systems that are beyond the capabilities of most universities or smaller groups.

Manage LAOF

EOL conducts countless day-to-day efforts to preserve and consistently improve the NSF LAOF resources that are entrusted to NCAR, and to maintain readiness for a vigorous deployment schedule. In the run-up to each field campaign, all instruments undergo exhaustive testing by EOL engineers and technicians to ensure optimal campaign performance. After the field phase commences, it often becomes necessary to make adjustments or upgrades to overcome difficult or unforeseen environmental conditions in order to meet scientific objectives. Then, upon completion of the field phase, calibrations, repairs and reconditioning are often required to maintain instrumentation readiness state for the next activity. The activities described below are a sampling of these efforts for FY 2017.


AVAPS New Registered Trademark

On 28 June 2016, the United States Patent and Trademark Office issued "AVAPS" as a registered trademark.  The trademark is registered in international class 009 as an atmospheric instrument that measures vertical profiles of ambient temperature, pressure, humidity, wind speed, and wind direction. Registration No. 4,986,828.


AVAPS Users Group Meeting

The 19th AVAPS users group meeting took place 25 through 26 April 2017. This annual meeting brings users of the NCAR dropsonde system together to present and discuss technical issues and advances as well as scientific results that were achieved using the NCAR dropsonde systems. Dropsonde observations are heavily used in hurricane research but also find widespread use in other field programs, such as studying satellite validation, low-level marine clouds, and gravity waves. This year’s meeting brought together 33 scientists, engineers, and dropsonde operators from 12 organizations to discuss new developments, current issues, data formats (e.g., BUFR), data QC topics, and important science results. There were 25 presentations with topics revolving around hurricane forecasting and targeted observations to study large-scale dynamics in mid and high latitudes.

Attendees at the 2017 AVAPS Users' Group meeting
Attendees at the 2017 AVAPS Users' Group meeting

The dropsondes are used by research agencies in seven other countries outside of the United States, including Germany, France, Great Britain, Taiwan, and Hong Kong. Due to the reduction in winter storm observations, the overall number of dropsonde measurements has been below average during the past year. However, the number of sondes provided by NCAR directly to the research community has remained steady.

The AVAPS dropsonde is undergoing a significant upgrade due to parts obsolescence but also to modernize the sonde electronics technology and data processing procedures. Initial atmospheric tests of the updated dropsonde show very promising results and are expected to lead to significant reduction in measurement uncertainty in particular for humidity, combined with an extension of the vertical profile due to faster response times for both the temperature and humidity sensors.

Extensive discussions revolved around the new capability to generate and transmit WMO BUFR messages and the benefits and challenges for numerical model centers using these data. Another section presented initial studies for a new Japanese dropsonde and the progress developing a “Multipurpose Above Surface/Below Surface Expendable Dropsonde”. These developments highlight the continuing need for targeted airborne vertical atmospheric profiling.


C-130 Inspection

Approximately every four years, the NSF/NCAR C-130 undergoes a "heavy" check, which is complementary to the normal maintenance performed daily at RAF. These checks usually entail removing and/or closely examining major assemblies of the airframe (e.g., landing gear, engines, flight controls, empennage [tail], wings, fuselage) and inspecting for damage or wear beyond limits, such as corrosion issues, cracks in structural members, damaged fasteners, etc. The heavy check can be broken down into approximately 5 phases: arrival and "open up" (removal of all access panels or components); the inspection procedure, itself; repair, overhaul, or replacement of any damage or worn items; "close up" or reassembling the aircraft, including repainting as necessary (not this time); and a Functional Check Flight (FCF) to ensure that all systems are working properly and the aircraft is airworthy.

The latest heavy inspection of the NSF/NCAR C-130 was conducted at Cascade Aerospace in Abbotsford, Canada beginning 27 March 2017. This particular inspection cycle looked in-depth at the wings and fuel tanks, which involved opening up all access panels, and performing X-ray or ultra-sonic NDI (Non Destructive Inspection), as well as visually inspecting the tanks, wiring, fuel pumps, control valves, etc. RAF sent personnel from the maintenance staff to act as technical representatives during the course of the inspection to keep an eye on the company asset and assist with the engineering and technical questions that inevitably arise during the process (the representatives particularly needed with such a heavily modified research aircraft such as ours).  The inspection was successfully completed in summer 2017.


C-130 Power Upgrade System

C-130 power system part
A DFS-manufactured part for the new NSF/NCAR C-130 power system.

An upgrade to the C-130 power system to better handle data and operations began in FY 2017. The previous system had reached its limit of ability to power instrumentation. This was a joint effort between DFS and RAF, in which RAF was the lead and DFS created new frames and hardware to fit the new components. The new system will be finalized and tested in early FY 2018.

RAF Emergency Response Exercise

On 15 June 2017, EOL/RAF organized an Emergency Response Exercise to assess EOL’s and UCAR’s preparedness for an aircraft emergency.  Several staff were involved in the project, including pilots, project managers and administration.  In addition to EOL, representatives from UCAR level were actively engaged in the exercise, including the UCAR President, the Vice President of Finance and Administration, the Interim UCAR Human Resources Director, the UCAR Communications Director, and the Director of Facilities. RAF worked closely with an outside consultant to help with simulating the emergency.

A sequence of events was simulated for the exercise, including an emergency aircraft landing and a mock media frenzy that would result from such an incident.  Those on the emergency response team handled the situation with successful outcomes, showing the readiness of both EOL and UCAR for such an event.

As a result of the five-hour exercise, EOL staff will be making some changes to the EOL Aviation Emergency Response Plan. Follow-up discussions with UCAR on how to further improve the process are also planned.  Once the plan is revised and finished, all staff who fly on either of the NSF/NCAR aircraft are encouraged to familiarize themselves with the document.


ICARE 2017 Meeting (10-13 July 2017)

In July, several EOL staff traveled to Oberpfaffenhofen, Germany to participate in the second International Conference on Airborne Research for the Environment (ICARE). Theconference was organized by the European Facility for Airborne Research (EUFAR) and was attended by users of research aircraft, operators, and representatives from several funding agencies. The conference reviewed scientific drivers for future airborne measurements across a broad range of topics in environmental science. Other sessions were focused on the organization of future field campaigns, the development of future airborne science capabilities, instrumentation and platforms, and data needs and services.

ICARE 2017 Meeting attendees
ICARE 2017 Meeting attendees



Deploy LAOF in NSF-funded Observational Field Campaigns

Field program planning and implementation is a critical community service, and EOL’s efforts here are part of NCAR’s Strategic Imperative to provide observational facilities that meet the science community’s needs. EOL employs and trains project staff, assists principal investigators (PIs) with project planning and preparation, supports observing programs by operating facilities and instruments, and preserves quality of collected data for decades in support of research and field programs worldwide. EOL enables science for each campaign’s PIs through this support, and, when we are a science lead or participant, directly engages in that science. EOL provided field program planning and implementation for 4 NSF-funded, 1 NASA-funded, 2 NOAA-funded, and 1 Department of Energy (DOE) research campaigns, as well as 3 NSF-approved instrumentation tests. These were:

  • Perdigão
  • VERTical Enhanced MiXing (VERTEX)
  • Seeded and Natural Orographic Wintertime Clouds: The Idaho Experiment (SNOWIE)
  • "Sensing Hazards with Operational Unmanned Technology (SHOUT) (NOAA)
  • East Pacific Origins and Characteristics of Hurricanes (EPOCH) (NASA/NOAA)
  • Eclipse test flights
  • Eclipse
  • Western wildfire Experiment for Cloud chemistry, Aerosol absorption and Nitrogen (WE-CAN) test flights
  • Airborne Research Instrumentation Testing Opportunity (ARISTO) 2017
  • Land-Atmosphere Feedback Experiment (LAFE) (DOE)

In FY 2017, EOL’s work on these campaigns entailed direct support of more than 49 scientists, 30 graduate and 20 undergraduate students, and the science teams for these campaigns came from 31 different institutions.



The Perdigão field study took place from 15 December 2016 to 15 June 2017 and was EOL’s largest ground-based field deployment in recent history.  The aim of the project was to illuminate fundamental properties of boundary-layer (BL) structure in flow over complex terrain in order to help scientists improve representation of BL processes in  atmospheric models and to facilitate decisions on where to place wind turbines for harvesting wind energy in complex terrain. Perdigão capitalized on recent technological advances in remote sensing and included over 30 scanning and profiling units to map a valley located in the Serra do Perdigão region of Central Portugal. Along an estimated 4-mile-long, 1-mile-wide swath of a valley in Central Portugal, researchers set up an array of instruments which included close to 50 masts primarily outfitted with NCAR-provided instruments to measure wind speed, direction, temperature, humidity and other factors, both along and perpendicular to two main ridges.  Scanning and profiling lidars including NCAR’s Water Vapor DIAL (WV DIAL) studied small-scale wind flow in three dimensions.

The project was a collaborative effort between NCAR’s Earth Observing Laboratory, the University of Notre Dame, the University of Colorado, Cornell University, the University of California at Berkeley, the University of Oklahoma, and the Army Research Laboratory.  Perdigão was funded by NSF and leveraged by resources from the European Union under the European Research Area Network (ERANET)+ Program.  The ultimate goal of the ERANET+: New European Wind Atlas (NEWA) project is to create and publish a European Wind Atlas in electronic form, building a model chain of computational models, and field measurement campaigns. Perdigão was the largest project of several wind-mapping studies and experiments associated with the NEWA project.

The Perdigão site (courtesy of N. Vasiljevic)

Perdigão was the first international deployment for NCAR/EOL’s Water Vapor Differential Absorption Lidar (WV DIAL) repackaged into a refrigerator-size box (see Figure below).  This new configuration is easy to deploy with a forklift.

The image below shows WV DIAL data that were collected during a 10-day period from 24 May to 3 June 2017. The top panel shows the aerosol concentration  from the ground up to 12 km ASL; the bottom panel shows the absolute humidity from the ground  to 6 km above sea level (ASL).  Water vapor variations both in content and depth were detected by the WV DIAL.  Multiple layers of aerosol were detected between 30 May and 1 June 2017 (top panel). The high amount of water vapor between 27 and 30 May was accompanied by fog in the valley, leading to severe attenuation of the WV DIAL signals (lower panel).

10 days (5/24/17-6/3/17) of relative backscatter and water vapor data in Perdigão field study

The project was challenging, with weather delays, complex multi-government and –agency negotiations and collaborations, and personnel emergencies all playing a role.  However, in the end the project collected a reference data set at unprecedented spatial resolutions, characterizing both the mean and turbulent wind fields in a natural setting. For more information on this massive effort see the Perdigão project page; the Perdigão Field Catalog;  the UCAR AtmosNews story, Capturing a Detailed Portrait of Wind; or the story Monitoring Wind in Portugal’s Mountains Down to Microscales



The Seeded and Natural Orographic Wintertime Clouds: The Idaho Experiment (SNOWIE) project occurred in Idaho, with the goals of understanding the natural dynamical and microphysical processes by which precipitation forms and evolves within orographic winter storms, and determining the physical processes by which cloud seeding, either from ground generators or aircraft, impacts the amount and spatial distribution of snow falling across a river basin.  In addition to the instrumentation deployed for the project, EOL’s Catalog Maps was a great asset to SNOWIE. The Center for Severe Weather Research (CSWR) deployed DOWs to the project and lead Josh Wurman said:  “Real-time imagery revealed what appears to be the most convincing ever direct radar evidence of the effects of SNOWIE cloud seeding. SNOWIE's PIs’ ability to see these images in real time enhances the project's science and may positively affect the planning of future IOPs and scanning strategies”.  

Eclipse 2017 and Eclipse Test Flights

While many of us watched the 21 August 2017 total solar eclipse from the ground, EOL’s Research Aviation Facility (RAF) team along with scientists from the Harvard-Smithsonian Astrophysics Observatory (SAO) successfully sampled this once in a lifetime event at 47,000 feet on board the NCAR/NCAR GV. The GV was based in Chattanooga, Tennessee and flew southeast along the eclipse track from central Missouri through Tennessee. The optimal flight path, increased altitude, and speed of the GV allowed scientists to sample the eclipse for a four-minute duration (versus approximately two on the ground).

This project, called Eclipse 2017, aimed to measure, for the first time, the infrared spectrum of the solar corona from 2 to 12 µm during the total solar eclipse on 21 August 2017.  Three experiments flew on the NSF/NCAR GV to accompany a spectral survey from the ground, producing images of the corona and polarization measurements during the extended eclipse. The need to measure coronal magnetic fields is driven by several natural science problems also of importance to modern society (e.g., coronal mass ejections). The “mystery of the solar corona” (why it is several hundred times hotter than the solar surface) is related to the magnetic field threading the corona and remains one of the outstanding problems in 21st century physics. This project was headed by PIs from NCAR’s High Altitude Observatory and Atmospheric Chemistry, Observations and Modeling Laboratory, as well as SAO.

EOL/RAF Pilots and Project Manager during Eclipse Test Flights
EOL/RAF Pilots Lee Baker (left) and Bo Lemay (right) and Project Manager Lou Lussier (center) during the Eclipse 2017 flight

In preparation for the flight during the eclipse, the Air Spec instrument, which was developed by SAO, was flown aboard the GV for a series of three test flights originating from Rocky Mountain Municipal Airport. The tests ensured successful integration of the instrument onto the GV, initial calibrations and tests – in particularm testing an image stabilization system that was developed by a graduate student at SAO to keep the moon clear and stable in the frame of a camera on Air Spec even with the movement and vibrations of the aircraft. 


After months of preparation including several test flights from RMMA, the aircraft was able to fly the eclipse track with near perfect timing, and the Air Spec instrument, specifically designed for this event, observed at least one of the four spectral lines the PIs expected to see in real time (and they anticipate that they will see more once the data is fully analyzed). Identifying the presence of these emission lines in the sun’s corona could eventually lead to improved understanding of the sun’s magnetic field. For more information on this project, please see the New York Times article titled “Scientists to Take Flight for Longer Views of the Eclipse”.




ARISTO logoFlight operations for the Airborne Research Instrumentation Testing Opportunity (ARISTO) 2017 project began 22 February and ended 10 March 2017. This year's two main groups of instruments were tested on the NSF/NCAR GV: (1) a subset of instruments on which modifications had to be tested before being deployed on the approved Southern Ocean Clouds Radiation Aerosol Transport Experimental Study (SOCRATES) project in 2018; and (2) new instruments that had never flown before. The former group included the HIAPER Cloud Radar (HCR), the Cloud Flow Diffusion Chamber (CFDC) from Colorado State University (CSU), the Counterflow Virtual Impactor (CVI), the Giant Nuclei Impactor (GNI), a 2D stereo imaging probe (2DS), an upgraded Cloud Droplet Probe (CDP), the AVAPS ® system, and a new aircraft pressure measurement system comprised of an off-the-shelf transducer and short tubing to prevent resonance in the line. The latter included University of Colorado’s POLAR lidar. The project had a number of test flight objectives that are summarized here. All the planned objectives were successfully achieved.

WE-CAN Test Flights

The WE-CAN test flights, which occurred from 20 to 30 September 2017, had a substantial payload and a resultant integration period on the NSF/NCAR C-310 of almost seven weeks. These flights are in preparation for the FY 2018 WE-CAN campaign, and as part of that prep the PIs began to evaluate the flight objectives, and started identifying potential wildfire target areas and laying out flight plans. 


SOCRATES Planning Meeting and Dry Run

A planning meeting and dry run was held for the FY 2018 Southern Ocean Clouds Radiation Transport Aerosol Transport Experimental Study (SOCRATES) during the week of 19 June 2017 at NCAR.  Meeting activities included a review of the science objectives, updates from instrument operators regarding planned measurements, and an overview of platforms including the NSF/NCAR GV and R/V Investigator, an Australian research vessel that will hold the ISS.  Travel, shipping, scheduling, and other logistics were also discussed along with education and outreach that will take place in Hobart, Tasmania, where the GV operations will be based. 

During the dry run, the team went through data collected in the EOL Field Catalog from January - March 2017, conducted forecasts, and came up with target investigation areas, which were then verified.  The meeting provided a good opportunity for project participants to discuss SOCRATES operations and come up with plans for optimizing flights to collect the necessary data.


Manage the LAOF Request and Assessment Process

EOL manages all aspects of the LAOF request and facility request assessment process on behalf of NSF. This entails expert evaluation of facility requests and experimental designs of the proposed field campaigns with the aim of optimizing support of NSF-sponsored observational science and assuring that the scientific objectives of each campaign can be successfully accomplished. Aiding us in this effort is the Observing Facilities Assessment Panel (OFAP), an independent advisory body to EOL and the other NSF LAOF partner organizations, which is convened by EOL twice per year in spring and fall. Maintaining the transparency and existing high standards of the request and assessment process is essential for ensuring equal access to LAOF by all NSF-funded researchers and ensuring that allocations made by NSF result in safe and successful field deployments in which deployment facilities are well matched to the requestor needs. 

In FY 2017, EOL hosted two Observing Facilities Assessment Panel (OFAP) meetings, one in fall 2016, and one in spring 2017. We created Experimental Design Overview (EDO) assessments/feasibilities and cost estimates for a total of 17 distinct projects requiring LAOF support (Fall 2016 - 6 projects / Spring 2017 - 11 projects); prepared two Global Feasibilities (Fall 2016 and Spring 2017), outlining project combinations and resource limitations in support of NSF funding decisions; developed 17 OFAP Summary Assessment & Recommendations documents that were shared with individual PI teams to help optimize experiment designs; and prepared 17 Project Summary Documents, which became part of EOL’s Organizational Process Assets, and were shared with NSF Program Officers and LAOF partner organization representatives.

A journal article reviewing 20 years of field campaigns was also published. Avallone, L. M., and B. Baeuerle, 2017: A 20-year history of NSF-supported atmospheric science field campaigns: Statistics and demographics. Bulletin of the American Meteorological Society, 98, 1333-1339, doi:10.1175/BAMS-D-15-00222.1.

Cooperate with Others on Support of Observational Science

EOL routinely enables and conducts multi-facility and multi-agency deployments that include instruments, resources, and collaborators from other U.S. agencies and other U.S. and foreign institutions. We also deploy EOL-managed LAOF occasionally in support of campaigns that are funded solely by other agencies. EOL fosters collaborations with outside groups in many areas, including some of the key measurements, instrument support, shared calibration and test equipment, studies related to the quality of measurements, expertise in meeting regulatory requirements, and software development. By maintaining current and developing new collaborations and cooperation, our objective is to enhance the overall scientific productivity and realization of research goals by a broad geosciences research community. 

In FY 2017, EOL supported the East Pacific Origins and Characteristics of Hurricanes (EPOCH) Project. ISF’s dropsonde group supported the joint NASA/NOAA EPOCH campaign from 1-30 August 2017 out of NASA Armstrong/Edwards Air Force Base. The NASA Global Hawk overflew three different tropical storms - Franklin, Harvey and Lidia - and collected data from three instruments including the dropsonde system. Major dropsonde-related accomplishments during EPOCH included the assimilation of dropsonde data in real time into NOAA’s operational Global Forecast System (GFS) model, and the use of dropsondes to successfully capture tropical cyclogenesis. One sonde was dropped into the center of Lidia, capturing the storm’s minimum central pressure. Thanks to the team from EOL’s Design and Fabrication Services (DFS), who made major modifications and upgrades to the automated launcher last spring, the system worked extremely well with zero issues during all flights. Also accomplished were 26 drops of the next generation dropsonde using the new Vaisala PTU sensor module and all upgraded electronics. The new RH sensor performed extremely well at the high altitudes and extreme low temperatures showing significant water vapor signatures.

That same EOL group also supported the fourth field campaign of the Sensing Hazards with Operational Unmanned Technology (SHOUT) NOAA project with the automated AVAPS system on the NASA/NOAA Global Hawk, which was based at NASA Wallops flight facility in Virginia and the NASA Armstrong Research Center in California.   

EOL's Water Vapor Differential Absorption Lidar (WV DIAL) participated in the Department of Energy Land-Atmosphere Feedback Experiment (LAFE), which deployed several state-of-the-art scanning lidar and remote sensing systems to the Atmospheric Radiation Measurement (ARM) Climate Research Facility Southern Great Plains Megasite (SGP). The instrumentation worked together to collect a data set for studying feedback processes between the land surface and the atmosphere. The novel synergy of remote sensing systems that included WV DIAL will be applied for simultaneous measurements of land-surface fluxes as well as horizontal and vertical transport processes in the atmospheric convective boundary layer (CBL).