SPEC Incorporated

Sterling, CO, United States

SPEC Incorporated

Sterling, CO, United States
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Paul Lawson R.,SPEC Incorporated | Woods S.,SPEC Incorporated | Morrison H.,U.S. National Center for Atmospheric Research
Journal of the Atmospheric Sciences | Year: 2015

The rapid glaciation of tropical cumulus clouds has been an enigma and has been debated in the literature for over 60 years. Possible mechanisms responsible for the rapid freezing have been postulated, but until now direct evidence has been lacking. Recent high-speed photography of electrostatically suspended supercooled drops in the laboratory has shown that freezing events produce small secondary ice particles. Aircraft observations from the Ice in Clouds Experiment-Tropical (ICE-T), strongly suggest that the drop-freezing secondary ice production mechanism is operating in strong, tropical cumulus updraft cores. The result is the production of small ice particles colliding with large supercooled drops (hundreds of microns up to millimeters in diameter), producing a cascading process that results in rapid glaciation of water drops in the updraft. The process was analyzed from data collected using state-of-the-art cloud particle probes during 54 Learjet penetrations of strong cumulus updraft cores over open ocean in a temperature range from 5° to -20°C. Repeated Learjet penetrations of an updraft core containing 3-5 g m-3 supercooled liquid showed an order-of-magnitude decrease in liquid mass concentration 3 min later at an elevation 1-1.5 km higher in the cloud. The aircraft observations were simulated using a one-dimensional cloud model with explicit bin microphysics. The model was initialized with drop and ice particle size distributions observed prior to rapid glaciation. Simulations show that the model can explain the observed rapid glaciation by the drop-freezing secondary ice production process and subsequent riming, which results when large supercooled drops collide with ice particles. © 2015 American Meteorological Society.


Lawson R.P.,SPEC Incorporated
Atmospheric Measurement Techniques | Year: 2011

Recently, considerable attention has been focused on the issue of large ice particles shattering on the inlets and tips of cloud particle probes, which produces copious ice particles that can be mistakenly measured as real ice particles. Currently two approaches are being used to mitigate the problem: (1) Based on recent high-speed video in icing tunnels, probe tips have been designed that reduce the number of shattered particles that reach the probe sample volume, and (2) Post processing techniques such as image processing and using the arrival time of each individual particle. This paper focuses on exposing suspected errors in measurements of ice particle size distributions due to shattering, and evaluation of the two techniques used to reduce the errors. Data from 2D-S probes constitute the primary source of the investigation, however, when available comparisons with 2D-C and CIP measurements are also included. Korolev et al. (2010b) report results from a recent field campaign (AIIE) and conclude that modified probe tips are more effective than an arrival time algorithm when applied to 2D-C and CIP measurements. Analysis of 2D-S data from the AIIE and SPARTICUS field campaigns shows that modified probe tips significantly reduce the number of shattered particles, but that a particle arrival time algorithm is more effective than the probe tips designed to reduce shattering. A large dataset of 2D-S measurements with and without modified probe tips was not available from the AIEE and SPARTICUS field campaigns. Instead, measurements in regions with large ice particles are presented to show that shattering on the 2D-S with modified probe tips produces large quantities of small particles that are likely produced by shattering. Also, when an arrival time algorithm is applied to the 2D-S data, the results show that it is more effective than the modified probe tips in reducing the number of small (shattered) particles. Recent results from SPARTICUS and MACPEX show that 2D-S ice particle concentration measurements are more consistent with physical arguments and numerical simulations than measurements with older cloud probes from previous field campaigns. The analysis techniques in this paper can also be used to estimate an upper bound for the effects of shattering. For example, the additional spurious concentration of small ice particles can be measured as a function of the mass concentration of large ice particles. The analysis provides estimates of upper bounds on the concentration of natural ice, and on the remaining concentration of shattered ice particles after application of the post-processing techniques. However, a comprehensive investigation of shattering is required to quantify effects that arise from the multiple degrees of freedom associated with this process, including different cloud environments, probe geometries, airspeed, angle of attack, particle size and type. © 2011 Author(s).


Ardon-Dryer K.,Tel Aviv University | Levin Z.,Tel Aviv University | Levin Z.,Cyprus Institute | Lawson R.P.,SPEC Incorporated
Atmospheric Chemistry and Physics | Year: 2011

The effectiveness of aerosols as immersion freezing nuclei at the South Pole station was investigated during January and February 2009 using the FRIDGE-TAU. The analysis consisted of testing the freezing temperature of about 100-130 drops per sample containing aerosols collected at ground level and on a balloon lifted to different heights. All the drops froze between -18 °C and -27 °C. The temperature in which 50 % of the drops froze occurred at -24 °C, while nuclei concentration of 1 L-1 at -23 °C was calculated. Meteorological conditions such as wind speed, ice precipitation as well as the trajectories of the air masses affected the ice nuclei concentrations. Higher concentrations were observed on days when the winds were stronger or when the air mass originated from the sea. © 2011 Author(s).


Lowenstein J.H.,University of Leeds | Blyth A.M.,University of Leeds | Lawson R.P.,SPEC Incorporated
Quarterly Journal of the Royal Meteorological Society | Year: 2010

Droplet size distributions (DSDs) measured within a distance of approximately 1km above the base of shallow maritime cumulus clouds during the Rain in Cumulus over the Ocean (RICO) field campaign are compared with results of a condensation and stochastic coalescence model, run in the framework of a closed parcel. New measurements of cloud droplets in the critical size range of 30 to 100μm are presented from the 2D-S probe. Observations are also presented of the large-size tail of the sub-cloud aerosol size distribution measured by the forward-scattering spectrometer probe. Results show that droplet growth in this region is dominated by condensation, and the large-size tail of the observed DSDs can be explained with the observed sub-cloud particles, including giant and ultra-giant aerosols. © 2010 Royal Meteorological Society.


Lawson R.P.,SPEC Incorporated | Gettelman A.,U.S. National Center for Atmospheric Research
Proceedings of the National Academy of Sciences of the United States of America | Year: 2014

Precious little is known about the composition of low-level clouds over the Antarctic Plateau and their effect on climate. In situ measurements at the South Pole using a unique tethered balloon system and ground-based lidar reveal a much higher than anticipated incidence of low-level, mixed-phase clouds (i.e., consisting of supercooled liquid water drops and ice crystals). The high incidence of mixed-phase clouds is currently poorly represented in global climate models (GCMs). As a result, the effects that mixed-phase clouds have on climate predictions are highly uncertain. We modify the National Center for Atmospheric Research (NCAR) Community Earth System Model (CESM) GCM to align with the new observations and evaluate the radiative effects on a continental scale. The net cloud radiative effects (CREs) over Antarctica are increased by +7.4 Wm-2, and although this is a significant change, a much larger effect occurs when the modified model physics are extended beyond the Antarctic continent. The simulations show significant net CRE over the Southern Ocean storm tracks, where recent measurements also indicate substantial regions of supercooled liquid. These sensitivity tests confirm that Southern Ocean CREs are strongly sensitive to mixed-phase clouds colder than -20°C. © 2014, National Academy of Sciences. All rights reserved.


Grant
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase II | Award Amount: 599.42K | Year: 2010

In Phase II SPEC will design, fabricate and flight test a state-of-the-art combined cloud particle probe called the Hawkeye. Hawkeye is the culmination of two decades of innovative instrument development at SPEC. The new probe will measure the size distribution of cloud and precipitation particles, provide high-resolution (2.3 micron pixel) images of cloud particles and remove artifacts from ice particle shattering. This will be accomplished by eclectic combination of technology developed in three existing SPEC optical cloud particle probes: 1) A fast FSSP, that measures size distributions from 1 to 50 microns and records individual particle statistics and remove shattered particles using inter-arrival times, 2) a cloud particle imager (CPI) with upgraded imagery capable of recording up to 500 frames per second, and 3) a 2D-S (Stereo) probe that is configured with one channel to provide full-view images of particles from 10 microns to 1.28 mm, and a second channel configured to provide full-view images of particles from 50 microns to 6.4 mm. Thus, using particle dimensions along the direction of flight will produce particle size distributions from 1 micron to several cm. Hawkeye will be designed for installation and autonomous (unattended) operation on NASA research aircraft, including the Global Hawk unmanned aerial system (UAS), and DC-8, WB-57F and ER-2 piloted research aircraft. Hawkeye will provide vastly improved measurements of particle and precipitation size distributions, particle shape, extinction coefficient, effective particle radius, ice water content and equivalent radar reflectivity. Hawkeye will be ready for installation on NASA aircraft for the upcoming ACE and GPM decadal missions, which are aimed at measurements of the effects of aerosols, clouds and precipitation on global climate change.


Grant
Agency: Department of Energy | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 149.94K | Year: 2011

It is well known now that clouds have a particularly strong nonlinear influence on the surface energy budget in the Arctic including the timing of the onset of snowmelt. The greenhouse effect produced by low-level, thin Arctic cloud cover accelerates melting and increases the amount of open water, which absorbs more incoming sunlight than ice surfaces, setting up a positive feedback process that leads to more melting and warming near the surface. Large decreases in sea ice extent and thickness have been observed in recent years and surface temperatures have increased. Satellite monitoring of the microphysical and radiative properties of low-level Arctic stratus clouds is needed to determine the rate of ice melt and global warming. However, algorithmic retrievals from satellite observations of Arctic cloud properties are a work in progress and require long-duration in situ cloud measurements to improve their performance. Research aircraft capable of making measurements of low-level Arctic stratus clouds are costly, difficult to conduct in a Polar environment and come at a risk to human life. Tethered Balloon Systems (TBS) are now widely recognized as an emerging technology that can provide long-duration measurements of low-level Arctic stratus clouds. TBS have advantages over research aircraft in that they can conduct long-duration vertical profiles through Arctic clouds all the way to the surface; the slow impact speed negates the issue of ice crystals shattering on cloud particle probe inlets; they are cost-effective and present a low risk to human life. SPEC Incorporated developed a TBS under previous DOE SBIR funding in 2004 and successfully deployed the system to Ny-lesund (79 N. Latitude) in 2008 and the South Pole in 2009. Three articles in refereed journals have been published based on data collected from these two projects. SPEC modified the TBS to include a larger balloon with approximately twice the lift of the previous 43-m3 balloon. The new TBS was deployed to the North Slope of Alaska in October 2010 and the balloon was lost when both the primary and backup tether broke. The balloon was brought to the surface using a remotely actuated deflation system and landed in the ocean. No air traffic was interrupted and there was no loss of human life. This incident highlights the fact that we are still on a learning curve with the TBS and the causes and corrections of this incident will be a major part of the Phase I effort. In addition to developing a test cell to simulate and test loads and fatigue factors, we will upgrade some existing sensors and design new sensors in Phase I. Among the new sensors that will be designed will be a long wavelength radiometer, a large particle imager and an in situ cloud lidar that makes volumetric measurements of liquid water content, effective drop radius and extinction. Instrument designs that will be upgraded will be a cloud drop size distribution probe, cloud particle imager, cloud condensation nucleus and ice nucleus measurements. In Phase II we will purchase, fabricate and test the new winch/tether deployment system, fabricate the upgraded and new sensors, integrate the entire TBS and perform field tests. Commercial Applications and Other Benefits: Long-duration, spatially extensive datasets of in situ measurements of Arctic stratus clouds are an effective way to provide the statistical basis required to improve satellite retrievals. Development of readily deployable TBS with miniaturized sensors across the Arctic has large commercial benefit and the potential to collect a dataset with adequate statistics to improve satellite retrievals. If global climate models are improved, if public awareness is stimulated and the proper steps are taken to slow or reverse global warming, the benefit to the general public could be monumental


Grant
Agency: Department of Energy | Branch: | Program: SBIR | Phase: Phase II | Award Amount: 999.93K | Year: 2012

The Arctic as a region of particular sensitivity to climate change. In the past few decades, the annual average temperature over the Northern high latitude land surface has risen at almost twice the rate of the global average, disrupting the region and its people. Clouds are the primary factors that influence radioactive fluxes in the Arctic, and thus the rate of warming and ice melt. Long-term in situ measurements of Arctic cloud properties are needed to improve climate prediction models. Tethered balloon systems with sensors to measure cloud properties have recently been flown in Arctic and Antarctic. However, the technology is still in its infancy and new and innovative approaches are needed to reliably deploy more sophisticated instrument packages. Second-generation tethered balloon systems are being designed to be more robust and the instruments are being made smaller, lighter and capable of collecting even more sophisticated measurements. In Phase I the winch and tether systems that were previously used to deploy balloons with instrument packages underwent extensive engineering and laboratory tests, resulting in a design of a far more robust deployment system. The instrument package was evaluated and new miniature instruments were designed in-house or subcontracts were arranged for them to be built in Phase II. Proof-of-concept laboratory tests were performed and a top- down design of a new tethered balloon deployment and measurement package was designed. The focus of the second-generation tethered balloon system is to improve our understanding of the properties of Arctic clouds and thereby reduce the uncertainties in climate prediction models. The results from laboratory tests and engineering designs generated in Phase I will be used to build and field-test a second-generation tethered balloon system in Phase II. A redesigned, more robust winch and tether system will loft a balloon to 2 km within a restricted area near the companys home office. An automatic balloon deflation and tracking system will be tested with a dummy instrument package. A new composite optical probe that records high-resolution digital images and size distributions of cloud particles from 1 micron to 6.4 mm will be fabricated and calibrated in the laboratory. Other new instruments that will be integrated and tested are a near infrared radiometer, filter systems to collect and analyze aerosols and ice nuclei, an optical cloud condensation nucleus counter and a lidar that makes volumetric measurements of cloud drop size and water content. The second-generation tethered balloon system will then be deployed to a DOE site at Oliktok Point on the North Slope of Alaska to conduct a demonstration project to collect data in Arctic mixed-phase clouds. Commercial Applications and Other Benefits: If global warming continues at its present rate in the Arctic, the effects on the region and its people will be devastating. In addition, if warming continues and melts the Greenland icecap, the effect on coastal areas will be disastrous. To prepare for and possibly mitigate these potential effects, improved climate prediction models are needed, which requires a better understanding of the properties of Arctic clouds. The demonstration project planned in Phase II at the DOE site, Oliktok Point on the North Slope of Alaska, will establish the viability of tethered balloon systems to make long- term in situ measurements of the properties of Arctic mixed-phase clouds, which predominate in the Arctic. Once the viability and value of the tethered balloon system is established, other sites in the Arctic are likely to be established, providing commercial opportunities and a better global representation of the effects of Arctic clouds in climate prediction models.


Grant
Agency: Department of Energy | Branch: | Program: SBIR | Phase: Phase II | Award Amount: 1.48M | Year: 2016

The 2013 report from the International Panel on Climate Change states that the spatial extent of Arctic sea ice has decreased in every season, and in every successive decade since 1979. Arctic summer sea ice retreat is unprecedented (9.4 to 13.6% per decade). Numerical simulations predict a nearly ice-free summertime Arctic after the middle of the 21st century. It is now well established that clouds and aerosols have a major impact on warming in the Arctic and a concomitant reduction in sea ice. Mixed-phase clouds, which contain both supercooled water drops and ice, are prevalent and persistent in the Arctic. Yet, relatively few in situ cloud measurements exist in mixed-phase clouds. How the Problem is Addressed: To date, research aircraft have accounted for the modest dataset of in situ measurements in Arctic clouds, but research aircraft are expensive to operate in Polar Regions, have limited duration, and present safety concerns. In contrast, unmanned aerial systems (UAS), which include small unmanned aerial vehicles (UAV’s) and tethered balloon systems, can operate for extended periods of time in the Arctic without risk to human life. Recent technological advances in small UAV have been impressive, including flights into hurricanes and across the Atlantic Ocean. Electrically-powered UAV are also making rapid gains in performance and duration due to improved composite designs and advances in battery technology. However, miniaturized sensors to measure cloud and aerosol properties lag behind the development of small UAV. This proposal is to develop a lightweight (5 kg) instrument package containing sensors to measure cloud microphysics, aerosols, position, three-dimensional winds, heading, aircraft pitch, roll, yaw, ambient temperature, humidity, airspeed and altitude. What will be Accomplished in Phase I and Phase II: Phase I research will provide solid-model designs, ray-tracing and laboratory tests of all components of the miniaturized instrument package. In Phase II, SPEC build and flight-test the instrument package on a small UAV provided by Vanilla Aircraft LLC, a leader in the design and fabrication of small unmanned aerial vehicles, or a Scaneagle provided by the DOE. Flight tests will be conducted in clear air within the Ft. Pickett restricted airspace, and in mixed-phase clouds at Ft. Pickett and/or the DOE facility at Oliktok Point, Alaska. The miniaturized instrument package will take advantage of SPEC’s previous experience developing microphysics probes for research aircraft, and advances in electronics that facilitate miniaturization of computers and signal conditioning. SPEC developed the cloud particle imager (CPI) in 1997 and its 2D-S (stereo) optical array probe in 2004. Both of these instruments have been installed on over twenty research aircraft. Highly-miniaturized versions of these instruments will be incorporated into the instrument package. Borrowing from it previous experience, SPEC will design and fabricate a combination particle probe that incorporates 1) a forward scattering probe that measures the size of particles from 1 to 50 microns, 2) a CPI that has a digital camera with 256 gray levels and at least 3-micron pixel resolution in the sample volume, and 3) a precipitation imager with 25 micron pixel resolution that fully images rain and ice particles out to 3.2 mm, and sizes all particles out to 1 cm. An off-the-shelf optical aerosol particle sizer that measures from 0.2 to 10 microns, a cloud condensation counter (CCN) developed at Scripps Institute and an ice nuclei filter system will be included, along with sensors for position, winds and state parameters. The instrument package is anticipated to weigh less than 5 kg and consume less than 50 W. A CPI with the highest possible (submicron) pixel resolution for imaging very small ice and large aerosols will also be developed and tested. Commercial and Other Benefits: Improvements to climate prediction models require better measurements of the properties of Arctic clouds and aerosols. A highly-miniaturized instrument package will be designed, built and installed on a small unmanned aerial vehicle (UAV), and deployed at Oliktok Point on the North Slope of Alaska, or other Polar location (e.g., Svalbard). A successful demonstration project in Arctic clouds will establish the viability of small, electrically-powered UAV to make long-term in situ measurements of the properties of aerosols and Arctic mixed-phase clouds, which predominate in the Arctic. The miniaturized instrument package developed in Phase II and installed on a small electrically-powered UAV will find application in other areas, including measurements of the near-field properties of volcanic ash and measurements of aerosols on battlefields and in urban areas.


Grant
Agency: Department of Energy | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 224.91K | Year: 2015

Statement of the Problem: The 2013 report from the International Panel on Climate Change states that the spatial extent of Arctic sea ice has decreased in every season, and in every successive decade since 1979. Arctic summer sea ice retreat is unprecedented (9.4 to 13.6% per decade). Numerical simulations predict a nearly ice-free summertime Arctic after the middle of the 21st century. It is now well established that clouds and aerosols have a major impact on warming in the Arctic and a concomitant reduction in sea ice. Mixed-phase clouds, which contain both supercooled water drops and ice, are prevalent and persistent in the Arctic. Yet, relatively few in situ cloud measurements exist in mixed-phase clouds. How the Problem is Addressed: To date, research aircraft have accounted for the modest dataset of in situ measurements in Arctic clouds, but research aircraft are expensive to operate in Polar Regions, have limited duration, and present safety concerns. In contrast, unmanned aerial systems (UAS), which include small unmanned aerial vehicles (UAVs) and tethered balloon systems, can operate for extended periods of time in the Arctic without risk to human life. Recent technological advances in small UAV have been impressive, including flights into hurricanes and across the Atlantic Ocean. Electrically-powered UAV are also making rapid gains in performance and duration due to improved composite designs and advances in battery technology. However, miniaturized sensors to measure cloud and aerosol properties lag behind the development of small UAV. This proposal is to develop a lightweight (5 kg) instrument package containing sensors to measure cloud microphysics, aerosols, position, three-dimensional winds, heading, aircraft pitch, roll, yaw, ambient temperature, humidity, airspeed and altitude. What will be Accomplished in Phase I and Phase II: Phase I research will provide solid-model designs, ray-tracing and laboratory tests of all components of the miniaturized instrument package. In Phase II, SPEC build and flight-test the instrument package on a small UAV provided by Vanilla Aircraft LLC, a leader in the design and fabrication of small unmanned aerial vehicles, or a Scaneagle provided by the DOE. Flight tests will be conducted in clear air within the Ft. Pickett restricted airspace, and in mixed-phase clouds at Ft. Pickett and/or the DOE facility at Oliktok Point, Alaska. The miniaturized instrument package will take advantage of SPECs previous experience developing microphysics probes for research aircraft, and advances in electronics that facilitate miniaturization of computers and signal conditioning. SPEC developed the cloud particle imager (CPI) in 1997 and its 2D-S (stereo) optical array probe in 2004. Both of these instruments have been installed on over twenty research aircraft. Highly-miniaturized versions of these instruments will be incorporated into the instrument package. Borrowing from it previous experience, SPEC will design and fabricate a combination particle probe that incorporates 1) a forward scattering probe that measures the size of particles from 1 to 50 microns, 2) a CPI that has a digital camera with 256 gray levels and at least 3-micron pixel resolution in the sample volume, and 3) a precipitation imager with 25 micron pixel resolution that fully images rain and ice particles out to 3.2 mm, and sizes all particles out to 1 cm. An off-the-shelf optical aerosol particle sizer that measures from 0.2 to 10 microns, a cloud condensation counter (CCN) developed at Scripps Institute and an ice nuclei filter system will be included, along with sensors for position, winds and state parameters. The instrument package is anticipated to weigh less than 5 kg and consume less than 50 W. A CPI with the highest possible (submicron) pixel resolution for imaging very small ice and large aerosols will also be developed and tested. Commercial and Other Benefits: Improvements to climate prediction models require better measurements of the properties of Arctic clouds and aerosols. A highly-miniaturized instrument package will be designed, built and installed on a small unmanned aerial vehicle (UAV), and deployed at Oliktok Point on the North Slope of Alaska, or other Polar location (e.g., Svalbard). A successful demonstration project in Arctic clouds will establish the viability of small, electrically-powered UAV to make long-term in situ measurements of the properties of aerosols and Arctic mixed-phase clouds, which predominate in the Arctic. The miniaturized instrument package developed in Phase II and installed on a small electrically-powered UAV will find application in other areas, including measurements of the near-field properties of volcanic ash and measurements of aerosols on battlefields and in urban areas. Key Words: unmanned aerial systems, climate change, Arctic clouds, cloud microphysics, aerosols. Summary for Congress: The Arctic, a region that is warming at twice the rate of the global average, is considered a harbinger of global warming. Long-term measurements in Arctic stratus clouds are needed to improve climate prediction models. A highly-miniaturized instrument package that measures cloud and aerosol properties will be built, installed on a small, electrically-powered unmanned aerial system (UAV), and deployed in Arctic clouds and aerosols. A demonstration field project will show proof-of-concept for collecting long-term data in Arctic stratus clouds.

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