New science drivers and technological advances call for continued development of our facilities and services. As a nimble and flexible organization, EOL dynamically adjusts and evolves its observing capabilities and services to meet the evolving science needs. This evolution occurs both over short- and longer-term time scales and is informed through the Laboratory’s processes for anticipating new needs and directions. Activities under this Imperative are categorized into the following priority areas: 1) agile development to meet current deployment needs, 2) advancement of priority developments to meet future needs, and 3) life-cycle-management and anticipation of new needs.


The Airborne Phased Array Radar (APAR), to be flown on the NSF/NCAR C-130, will be a fast-scanning C-band, dual Doppler, dual polarimetric radar that will open new frontiers in Earth System Science research including high-impact weather events and studies in remote areas of the globe.  In partnership with NOAA, EOL has made significant strides in the APAR development and advanced many critical aspects of the APAR Preliminary Design.  Some FY 2019 highlights of this effort include completing development of an end-to-end phased array radar (PAR) prototype.  The PAR prototype is a technology demonstrator that was used to collect data during multiple weather events in winter of 2019 and is currently being used for characterization and calibration studies (in collaboration with the University of Oklahoma Advanced Radar Research Center).  

EOL PAR prototype (left) and display output (right) from a winter snow storm.

EOL PAR prototype (left) and display output (right) from a winter snow storm.

EOL is also working on data quality and forecast improvement studies through the development of the APAR Observing System (AOS).  The AOS “flys” APAR through high resolution numerical models to simulate APAR data. Additionally, the NOAA Hurricane Research Division is using synthetic APAR data to examine the impact of APAR data assimilation on hurricane forecasts.  While these studies are in the early stages, they are beginning to illustrate the promise of APAR to advance understanding and improve prediction of high-impact weather events.  

Examples of AOS output for hurricane simulation

Examples of AOS output for hurricane simulation

EOL continues to complete feasibility studies to assess the readiness of current technologies to build APAR.   One of the major accomplishments in FY 2019 was the completion of two Trade Studies with industry partners. These Trade Studies evaluated APAR requirements and and compared them with currently available PAR technologies.  The outcome of all of the studies indicate that APAR can be built with current technologies and will be able to meet the needs of the scientific community. Finally, EOL worked to submit a Mid-Scale Research Infrastructure 2 Proposal (MSRI-2) to NSF for build of the entire APAR system.  The proposal has undergone several stages of review and notification of the outcome is expected in mid-2020.

Video showing a model of APAR on the NSF/NCAR C-130 flying through clouds, with scanning from APAR shown by green and orange colored bands.


The Lidar Radar Open Source Environment (LROSE), an NSF-funded joint project between NCAR/EOL and the Colorado State University, aims to provide high-quality, open source software to the community of scientists, researchers and operational organizations using atmospheric lidars, radars and profilers.

In FY 2019, the LROSE team focused on streamlining the software installation procedure on Linux and Mac OS operating systems, upgrading functions in previous LROSE releases, and adding tropical cyclone related algorithms. Those algorithms will be included in the next LROSE release - “Cyclone” - in December 2019.  The LROSE team also held a half-day user workshop at the 2019 AMS Annual Meeting in Phoenix, AZ to inform the user community about the status of LROSE and receive feedback.   


As part of our mission, EOL scientists and engineers work with our scientific community to identify measurement and observing needs. We then apply the latest technologies to design and develop new observing systems that address important research challenges that require observational data. An example of this is the HOLODEC instrument, which is a holographic detector designed to determine the size, two-dimensional shape, and three-dimensional position of hydrometeors via digital in-line holography. This instrument was developed to meet measurement needs in the scientific community so that the sample volume is not size dependent, relative positions of hydrometeors in the sample volume can be determined in three dimensions, and effects produced by shattering from the aperture edges can be identified and eliminated. Automated analysis programs have been developed to process the holograms collected and produce size distributions, and the instrument has sufficient resolution to determine the sizes and locations of cloud droplets as well as ice crystals. 

HOLODEC instrument mounted on the NSF/NCAR GV aircraft

HOLODEC instrument mounted on the NSF/NCAR GV aircraft


Giant sea-salt aerosol particles (also called coarse-mode sea spray particles, with dry radius greater than 0.5 μm) are an important part of the atmospheric aerosol population.  They have been hypothesized to be very efficient hygroscopic nuclei for forming rain drops in warm clouds. EOL has now finalized the development of a new sampling instrument, the Automatic Giant Nucleus Impactor (AutoGNI), for sampling such particles from outside a research aircraft.  The AutoGNI can selectively expose 32 polycarbonate microscope slides, that are stored in a pressurized metal vessel just inside the skin of the aircraft. Using computer control, five motors are used to pick up a given slide, release it and transport it on a metal rod to be exposed outside the aircraft.  After about 10 seconds (depending on expected salt loading), the rod is retracted, and the slide is stored in the original position in a cassette inside the AutoGNI pressure vessel. A total of 17 position switches are used to ensure that the mechanics and motor drives are accurately positioned. While the aircraft is flying, the AutoGNI can be remotely controlled from an operator on the ground, using a satellite internet connection.  After the flight, the slides are stored in desiccated test tubes, and transported to NCAR for subsequent laboratory microscope analysis.

During the 2018 Southern Ocean Clouds, Radiation, Aerosol Transport Experimental Study (SOCRATES) deployment over the Southern Ocean, more than 250 microscope slides were exposed at low altitude from the NSF/NCAR GV, in a region of typically strong wind and wave activity, the so-called ‘roaring forties’ (and even fifties and sixties) for the hiles-per-hour speed of the winds in the region.

The AutoGNI and its usage during SOCRATES. A: Schematic of the AutoGNI mechanicals; slides are picked up from the octagonal carousel and exposed by being moved out through the bottom strut.  B: Photo of the carousel with 32 slides through the access port in the top of the AutoGNI containment vessel. C: Iceberg encountered during flight over the Southern Ocean; the sea shows very strong wave-breaking activity, which produces the giant sea-salt aerosol particles.  D: Microscope image of impacted sea-salt particles; the slide was imaged at 90% relative humidity, and the salt particles form near-hemispheric spherical cap drops. The image is one of 350 total images for the slide, and the largest particle has a diameter of 11.2 μm, which is about 100 times larger than more common aerosol particles.  E: Resulting sea-salt aerosol particle size distribution. The x-axis shows dry radius, and the y-axis shows the count of particles as a function of dry radius. The slide was exposed for 8 seconds at an altitude of 160 m, where the wind speed was 16 m/s.

MicroPulse DIAL (MPD)

The 5-unit MicroPulse DIAL (MPD) network, jointly developed by NCAR/EOL and Montana State University, was deployed to Oklahoma at the US Department of Energy’s (DOE) Atmospheric Radiation Measurement (ARM) facility Southern Great Plains (SGP) site from 17 Apr 2019 to 22 Jul 2019 to evaluate the engineering performance and how the systems would perform during long-term unattended operation in a high humidity environment. A unique dataset was collected that could be evaluated against more mature instruments (e.g., radiosondes, Raman lidar, and passive remote sensors) and determine the impact of such a network on predicting high-impact weather events.

Data taken by MPD #5 from 18 Apr to 28 Jun 2019 is shown in the figure below. Relatively dry conditions occur at the start of the test with absolute humidity values typically < 5 g m-3 in the boundary layer (lower panel). Periods of MPD signals were completely attenuated by the significant amounts of rain and cloudy conditions occurred from late April to early May.  Water vapor increased in June as the values of absolute humidity exceeded 15 g m-3 in the boundary layer.   

The first 10 weeks of data from the MPD Network Demonstration. Attenuated backscatter from 0-12 km AGL (top) and absolute humidity from 0-6 km (bottom) measured by MPD#5. This unit was located at the central facility of DOE ARM SGP site and was collocated with radiosondes launched every 3 hours during this demonstration. 

The next figure shows the frequency histogram (left) and scatter plot (right) of the correlation between the absolute humidity measured by the MPD #5 and the radiosondes launched every three hours. The correlation coefficient of 0.93 indicates a very high correlation between the two measurement methods, validating the quality of the water vapor measured by MPDs.

Frequency histogram (left) and scatter plot (right) showing the correlation between MPD#5 and collocated radiosondes. For the frequency histogram, the colors indicate the number of sample pairs per bin, 0.1x0.1 g/m3 bin sizes.   For both plots, the solid black line shows the ideal one-to-one relationship, and the dashed red line shows the least-square linear fit.  

The low-cost MPD network has achieved a major milestone by demonstrating the ability to collect continuous, high-vertical-resolution water vapor profiles over this 97-day period of unattended operations.