PDI Concentration Data Chuang, Patrick Earth and Planetary Sciences Department University of California, Santa Cruz Earth and Marine Sciences Building 1156 High St Santa Cruz, Ca 95064 831-459-1501 pchuang@pmc.ucsc.edu http://people.ucsc.edu/~pchuang/ Rossiter, Dione Earth and Planetary Sciences Department University of California, Santa Cruz Earth and Marine Sciences Building 1156 High St Santa Cruz, Ca 95064 831-459-1724 drossite@es.ucsc.edu 1.0 DATA SET OVERVIEW: This data set is comprised of time and drop concentration data. Concentration was calculated using data collected by the Phase Doppler Interferometer and is in units of dN/dlog Dp per cm3 for our 128 bins. Time period covered by the data = start: 19 October 2008; end: 13 November 2008 Physical location: left inboard of Twin Otter aircraft. 2.0 INSTRUMENT DESCRIPTION: The Artium Flight Phase Doppler Interferometer is based on the phase-Doppler interferometry technique. One advantage of the PDI over other standard cloud probes in the same size range is the independence of drop sizing from light intensity, making the measurement more robust under conditions of optics contamination and electronic noise. The PDI fundamentally measures the diameter, velocity and arrival time of individual cloud drops. Drops are assumed to be spherical with known refractive index, assumptions that are typically satisfied in warm clouds. From the fundamental quantities, we derive drop size distributions at fixed frequency by determining the instrument view volume. Although the full size range of the PDI during POST is ~3 to 150 microns diameter, counting statistics limit the practical size range to 3 to 100 microns diameter. Coincidence is theoretically predicted to be a very minor issue (less than 1% of events should suffer from coincidence), and no attempt to correct such a small effect is made. For POST, we will not report velocity distributions but they are available on request. For more information, see a recently published paper that describes the instrument principle and treatment of data in great detail: Chuang, P. Y., E. W. Saw, J. D. Small, R. A. Shaw, C.M. Sipperley, G. A. Payne, and W. D. Bachalo, .Airborne phase Doppler interferometry for cloud microphysical measurements,. Aerosol Sci. Tech., 42, 685-703, 2008. Specifications: Size range: 3 to 100 microns diameter Size accuracy: ~1 to 2 microns Size bins: 128 log-spaced bins Concentration accuracy: ~5% for each size bin + counting uncertainty View volume: approx. 0.5 mm^2 typical (depends on drop size and can be varied) 3.0 DATA COLLECTION AND PROCESSING: The ARTIUM AIMS software provides raw measurements of individual drops measured by the PDI. This includes the arrival time, size, velocity, PVC weight, signal to noise ratio and the rejection criteria. This data is fed into a processing code written primarily by Jennifer D. Small (UCSC). This program reads the PDI data and calculates a corrected PDI view volume for each measured droplet event using the AIMS correction equation and a probe volume diameter equation created and provided by Patrick Y. Chuang (UCSC). The data is binned into 128 logarithmically spaced size bins and a number distribution file is created. The number distribution file is then used with the probe volume diameter calculations and information from plane measurements (the Twin Otter) to calculate the concentration of drops within each size bin. The concentration file is then used to calculate the liquid water content, volume, surface area, spectral widths, and equivalent radar reflectivity. Several quality control procedures take place before data is posted. Before a research mission, the PDI is inspected by ARTIUM Technologies to ensure the instrument is working properly. Before each flight, a basic evolution of instrument is also preformed. During these evaluations, drops of an approximately known velocities and speeds are sent through the PDI beam intersection. Drop size, speed, and rejection rate are inspected to ensure measured values are reasonable. Droplets are rejected during collection if their trajectory or other qualities are not validated. During flight, drop size, speed, and rejection rates are also inspected periodically to ensure in-cloud values are reasonable. A data intercomparison is preformed after PDI data has been processed. Derived PDI LWC data is compared to Gerber Probe LWC data. This is our main method for post-processing quality control and is a final check for ensuring the data is in its most accurate form. 4.0 DATA FORMAT: Data file structure = Tab delimited ASCII Data format, layout, parameters with units = Column Nr: Description: 1 Date/time in Seconds Since Midnight (SSM) 2-129 Concentration ('Conc') data in units of dN/dlog Dp per cm3 for 128 bins Boundaries for the 128 bins in microns: Dmin Dmax Geometric Mean D 2.000020125 2.073332555 2.036346443 2.073332555 2.149332315 2.110990446 2.149332315 2.228117911 2.188370587 2.228117911 2.309791459 2.268587164 2.309791459 2.39445882 2.351744146 2.39445882 2.482229735 2.437949319 2.482229735 2.573217967 2.527314415 2.573217967 2.66754145 2.619955264 2.66754145 2.76532244 2.715991942 2.76532244 2.866687674 2.815548926 2.866687674 2.971768538 2.918755255 2.971768538 3.080701229 3.025744699 3.080701229 3.19362694 3.136655933 3.19362694 3.310692039 3.251632711 3.310692039 3.432048258 3.370824061 3.432048258 3.557852892 3.49438447 3.557852892 3.688269002 3.622474091 3.688269002 3.823465624 3.755258945 3.823465624 3.963617993 3.89291114 3.963617993 4.108907766 4.035609093 4.108907766 4.259523258 4.183537761 4.259523258 4.415659689 4.336888879 4.415659689 4.577519433 4.495861212 4.577519433 4.745312282 4.66066081 4.745312282 4.919255721 4.831501277 4.919255721 5.099575203 5.008604046 5.099575203 5.286504449 5.192198668 5.286504449 5.480285745 5.382523105 5.480285745 5.681170258 5.579824045 5.681170258 5.889418363 5.784357219 5.889418363 6.105299978 5.996387729 6.105299978 6.329094917 6.216190398 6.329094917 6.561093249 6.444050118 6.561093249 6.801595676 6.68026223 6.801595676 7.050913923 6.925132897 7.050913923 7.309371141 7.178979506 7.309371141 7.577302327 7.442131076 7.577302327 7.855054758 7.714928691 7.855054758 8.14298844 7.997725932 8.14298844 8.441476574 8.290889347 8.441476574 8.750906043 8.594798914 8.750906043 9.071677912 8.909848543 9.071677912 9.404207945 9.236446584 9.404207945 9.748927148 9.575016352 9.748927148 10.10628232 9.925996681 10.10628232 10.47673666 10.28984249 10.47673666 10.86077031 10.66702538 10.86077031 11.25888104 11.05803422 11.25888104 11.67158485 11.46337583 11.67158485 12.09941668 11.88357557 12.09941668 12.54293104 12.3191781 12.54293104 13.00270279 12.770748 13.00270279 13.47932787 13.23887057 13.47932787 13.97342404 13.72415258 13.97342404 14.48563173 14.22722301 14.48563173 15.01661482 14.74873391 15.01661482 15.56706155 15.28936124 15.56706155 16.13768537 15.84980572 16.13768537 16.72922588 16.43079377 16.72922588 17.34244982 17.03307842 17.34244982 17.978152 17.65744033 17.978152 18.63715638 18.30468875 18.63715638 19.32031712 18.97566261 19.32031712 20.0285197 19.67123159 20.0285197 20.76268204 20.39229723 20.76268204 21.52375573 21.13979415 21.52375573 22.31272722 21.9146912 22.31272722 23.13061912 22.71799275 23.13061912 23.97849154 23.55074001 23.97849154 24.85744345 24.41401232 24.85744345 25.76861408 25.30892861 25.76861408 26.71318444 26.23664881 26.71318444 27.69237883 27.19837538 27.69237883 28.70746642 28.19535485 28.70746642 29.7597629 29.22887945 29.7597629 30.8506322 30.30028877 30.8506322 31.98148824 31.4109715 31.98148824 33.15379676 32.56236725 33.15379676 34.36907725 33.75596839 34.36907725 35.62890486 34.99332198 35.62890486 36.93491253 36.27603182 36.93491253 38.28879302 37.60576048 38.28879302 39.69230114 38.98423146 39.69230114 41.14725603 40.41323146 41.14725603 42.65554353 41.89461267 42.65554353 44.21911859 43.43029516 44.21911859 45.84000781 45.0222694 45.84000781 47.5203121 46.67259879 47.5203121 49.26220937 48.38342241 49.26220937 51.06795735 50.15695771 51.06795735 52.93989656 51.99550346 52.93989656 54.88045328 53.90144265 54.88045328 56.89214275 55.87724566 56.89214275 58.9775724 57.92547339 58.9775724 61.13944524 60.04878066 61.13944524 63.38056336 62.24991954 63.38056336 65.70383156 64.53174304 65.70383156 68.11226112 66.8972087 68.11226112 70.60897371 69.34938251 70.60897371 73.19720541 71.89144283 73.19720541 75.88031094 74.52668453 75.88031094 78.66176797 77.25852323 78.66176797 81.54518166 80.0904998 81.54518166 84.53428932 83.02628487 84.53428932 87.63296525 86.06968362 87.63296525 90.84522577 89.22464073 90.84522577 94.17523443 92.49524547 94.17523443 97.62730736 95.88573698 97.62730736 101.205919 99.40050984 101.205919 104.9157076 103.0441197 104.9157076 108.7614817 106.8212891 108.7614817 112.7482258 110.7369139 112.7482258 116.8811075 114.7960692 116.8811075 121.1654834 119.0040163 121.1654834 125.6069068 123.3662092 125.6069068 130.2111343 127.8883021 130.2111343 134.9841336 132.576156 134.9841336 139.9320913 137.4358473 139.9320913 145.0614206 142.4736746 145.0614206 150.3787697 147.6961677 150.3787697 155.8910308 153.1100958 155.8910308 161.6053485 158.7224759 161.6053485 167.5291294 164.5405827 167.5291294 173.6700514 170.571957 173.6700514 180.0360742 176.8244165 180.0360742 186.6354489 183.3060651 186.6354489 193.4767292 190.0253041 193.4767292 200.5687825 196.9908425 Sampling interval: continuous Frequency: binned to 1 Hz Range: 0-8000 Data version (number and date): 1.0; 10, July 2009 5.0 DATA REMARKS: The PDI was not on-board the CIRPAS Twin Otter during Flight 1 and 2 and, therefore, no data is presented for those two flights. During the Flight 3, an auto-setup (a processor feature) was preformed during flight. In short, this feature will allow the PDI to sample cloud air and, from the range of drops measured during a particular time range, determine the most appropriate processor settings to use. These settings should stay the same throughout the remainder of the mission. Before Flight 6, the PDI stopped working and, therefore, no data is presented for this flight. The PDI was up and running properly for Flight 7, an auto-setup was preformed again, and all flights after this went as planned. 6.0 REFERENCES: Chuang, P. Y., E. W. Saw, J. D. Small, R. A. Shaw, C.M. Sipperley, G. A. Payne, and W. D. Bachalo, .Airborne phase Doppler interferometry for cloud microphysical measurements,. Aerosol Sci. Tech., 42, 685-703, 2008.