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The comprehensive suite of in-situ cloud microphysical instruments that were operated onboard the Environment Canada Convair-480 during ISDAC 2008 provided a rich dataset for investigating the effect of cloud microphysics on cloud...
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The comprehensive suite of in-situ cloud microphysical instruments that were operated onboard the Environment Canada Convair-480 during ISDAC 2008 provided a rich dataset for investigating the effect of cloud microphysics on cloud radiative properties and the effects of aerosol on clouds. The combination of CDP, 2D-S and 2D-P probes allowed for quantitative measurement of particle sizes spanning the range from 1 Ym to > 1 mm and particle concentrations spanning the range from 10-5 to 105 L-1. The faster electronics of the 2D-S probe compared to older instruments allowed for more accurate sizing and concentration measurements. The reduced effect of ice shatter artifacts as a result of modifications to the 2D-S probe tips and the ability to identify ice particle shatter events using particle interarrival times was particularly valuable for accurate analysis of particles in the size range <400 um. Furthermore, the use of a sophistical multi-dimensional algorithm for estimating particle mass on a particle by particle basis, using the particle perimeter, cross sectional area, length and perpendicular width, was applied for 2D-S data for the first time. Altogether, these state-of-the-art measurements and analysis techniques provided the most accurate and detailed glimpse to date of mixed-phase Arctic stratus.
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During the first 30 days SPEC delivered to the Naval Post Graduate School an aerosol inlet calibration device with instructions for use on the Navy Twin Otter research aircraft. Since then, SPEC has continued work on the design of...
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During the first 30 days SPEC delivered to the Naval Post Graduate School an aerosol inlet calibration device with instructions for use on the Navy Twin Otter research aircraft. Since then, SPEC has continued work on the design of the 2D-S (stereo) cloud particle probe. The custom 128-photodiode array has been fabricated and tested by Thermo Centrovision (TCV) and is, from the tests so far conducted, behaving beyond the requirements specified prior to manufacture. Work is ongoing for the both the digital and analog electronics. The digital electronics have been simulated and a prototype design is being pursued for the analog electronics. Footprint constraints for the analog electronics have been estimated and design of the laser and optical system are currently under way.
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All of the Phase I research objectives have been completed for the design, manufacture, and testing of the aerosol inlet calibration device. Optical simulations have been performed that indicate the presence of the inlet calibrati...
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All of the Phase I research objectives have been completed for the design, manufacture, and testing of the aerosol inlet calibration device. Optical simulations have been performed that indicate the presence of the inlet calibration device will have minimal effect on measurements from the FSSP 100. The mechanical design, manufacture, and assembly of the inlet calibration device were successfully completed. The inlet calibration device has been successfully tested in the laboratory with an FSSP 100. The measurements from the FSSP 100 with and without the inlet calibration device were nearly identical for Operating Ranges 1 and 2. The laboratory results confirm that the effect of the inlet calibration device on the measurements is negligible. At this time, SPEC recommends proceeding to Phase II, based on the results of the Phase I effort.
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During the four-month transition period between Phase I and Phase II, we will complete Solidworks TM mechanical and ZemaxTM optical designs for inlet calibration devices for the additional three conductive tubing diameters commonl...
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During the four-month transition period between Phase I and Phase II, we will complete Solidworks TM mechanical and ZemaxTM optical designs for inlet calibration devices for the additional three conductive tubing diameters commonly used in aerosol measurements. We will begin to design the inlet(s) to be installed on the SPEC Learjet research aircraft and work with Navy personnel to determine the best way to adapt the inlet calibration devices for use on the Navy Twin Otter. The diffuser inlet for the Learjet will be designed and engineering for FAA approval will be initiated. We will also begin to design the new 2D-S imaging probe and finalize the engineering parameters for ordering the custom I 28-photodiode array.
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The research conducted in Phase I led to the design and laboratory testing of a device that aids in the evaluation of the efficiency of aerosol inlets. The device will be tested in Phase II on a research aircraft by comparing the ...
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The research conducted in Phase I led to the design and laboratory testing of a device that aids in the evaluation of the efficiency of aerosol inlets. The device will be tested in Phase II on a research aircraft by comparing the particle size distribution measured by a forward scattering spectrometer probe (FSSP) in the aerosol inlet with an FSSP mounted on the wing. Figure 1 shows a Solidworks(TM) drawing and a photograph of the inlet calibration device. Laboratory tests showed that the device reliably measures the size distribution of glass beads in a predictable airflow through the FSSP sample volume.
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SPEC incorporated designed, built and operated a new instrument, called a pi-Nephelometer, on the NASA DC-8 for the SUCCESS field project. The pi-Nephelometer casts an image of a particle on a 400,000 pixel solid-state camera by f...
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SPEC incorporated designed, built and operated a new instrument, called a pi-Nephelometer, on the NASA DC-8 for the SUCCESS field project. The pi-Nephelometer casts an image of a particle on a 400,000 pixel solid-state camera by freezing the motion of the particle using a 25 ns pulsed, high-power (60 W) laser diode. Unique optical imaging and particle detection systems precisely detect particles and define the depth-of-field so that at least one particle in the image is almost always in focus. A powerful image processing engine processes frames from the solid-state camera, identifies and records regions of interest (i.e. particle images) in real time. Images of ice crystals are displayed and recorded with 5 micron pixel resolution. In addition, a scattered light system simultaneously measures the scattering phase function of the imaged particle. The system consists of twenty-eight 1-mm optical fibers connected to microlenses bonded on the surface of avalanche photo diodes (APDs). Data collected with the pi-Nephelometer during the SUCCESS field project was reported in a special issue of Geophysical Research Letters. The pi-Nephelometer provided the basis for development of a commercial imaging probe, called the cloud particle imager (CPI), which has been installed on several research aircraft and used in More than a dozen field programs.
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A research aircraft was equipped with imaging probes and an airborne KA Band radar, along with the standard compliment of cloud physics instrumentation, and was flown in the melting layer of stratiform clouds. Heavy precipitation ...
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A research aircraft was equipped with imaging probes and an airborne KA Band radar, along with the standard compliment of cloud physics instrumentation, and was flown in the melting layer of stratiform clouds. Heavy precipitation events during the research period were scarce, and the data presented here reflect analysis of precipitation from storms of light to occasionally moderate intensity. The dearth of strong precipitation events did not favor the formation of a deep melting layer with strong microwave attenuation characteristics, and this inhibited attempts to correlate observed attenuation of microwave signals with in situ cloud physics measurements. Results of comparisons between the airborne KA-band radar and the PMs imaging probes show a considerable variation in the echo returns as well as the cloud hydrometeor characteristics. Thus the microwave scattering properties through the melting layer are also highly variable. The observed vertical profiles of the evolution of precipitation particles shows that rapid aggregation occurs near the -2 C level, and that some large aggregates fall to temperatures as warm as +4 C before melting. Thus there is a region of approximately 800 m where partially melted aggregates can substantially influence the propagation of microwaves. Keywords: Cloud physics; Melting layer; Microwave attenuation; Brightband; Airborne radar; Ka band radar; Aggregation; Precipitation; Airborne instrumentation.
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