UC Santa Cruz Cloud Microphysics 1-Hz Data Data Set Name: UC Santa Cruz Cloud Microphysics 1-Hz Data Project: LASP/DYNAMO Platform: NOAA/AOC WP-3D N43RF Format: netCDF Latest version: 20Feb2014 PI and contact: Patrick Chuang Earth & Planetary Sciences Department University of California Santa Cruz Earth and Marine Science Bldg. 1156 High St. Santa Cruz, CA 95064 USA 831-459-1501 pchuang@ucsc.edu http://people.ucsc.edu/~pchuang Mikael Witte Earth & Planetary Sciences Department University of California Santa Cruz Earth and Marine Science Bldg. 1156 High St. Santa Cruz, CA 95064 USA 831-459-1501 mkwitte@ucsc.edu 1.0 DATA SET OVERVIEW: This data set contains time series of cloud drop number concentration. Measurements were taken by a Droplet Measurement Technologies (DMT) Cloud Imaging Probe (CIP) and a DMT Precipitation Imaging Probe (PIP). The instruments operate on the same operating principle but measure different drop size ranges. Each instrument measures over 62 bins and concentration is in units of cm-3. Time period covered by the data = start: 11 November 2011; end: 08 December 2011. Physical location: below left (port side) wing tip of NOAA P-3 N43RF. 2.0 INSTRUMENT DESCRIPTION: The CIP and PIP are optical array shadow instruments. A laser is aimed at a photodetector array consisting of 64 diodes. Particles passing through the laser beam shadow the diodes. Images are sized according to the number of diodes shadowed. For more on the theory of operation, see Strapp et al. 2001. Corrections are made for hollow/out of focus drops as detailed in Korolev 2006. The CIP measures particles with diameter between 25 and 1550 μm with 25 μm resolution and the PIP measures particles from 100 to 6200 μm with 100 μm resolution. While CIP/PIP both detect ice particles, the flights mostly avoided ice and we ignore it in our analysis. Note that the probes sample different air volumes. The cloud probe instrumentation also included a Cloud Droplet Probe and a Cloud and Aerosol Spectrometer (both from DMT), neither of which were satisfactorily operational during DYNAMO. 3.0 DATA COLLECTION AND PROCESSING: The CIP and PIP continuously record individual particle transits across a diode array which are exported as binary files. The binary files record a time stamp and a 2 dimensional map of the particle transit. The raw binary files are converted to images, each particle is characterized individually (size, aspect ratio, ice habit, etc.) and particle records are binned over 1 second intervals to make a 1 Hz time series. We use the NOAA P-3 1-Hz Navigation and State Parameters data set for 1-Hz reference time (netCDF variable name 'GPS_Fxtime.1') and true air speed ('TASF.1'). The processing algorithm was provided by Greg McFarquhar and Robert Jackson (University of Illinois) and modified by Mikael Witte (UCSC). Drops are rejected based upon their aspect ratio, position in the diode array, "hollow" appearance, and ice habit (i.e. no ice accepted). The continuous particle data is binned into 62 arithmetically spaced bins (CIP: 25 um spacing, PIP: 100 um spacing) and compiled into 1-Hz time series. The output contains three 1-Hz time series and 5 variables describing the bins. 4.0 DATA FORMAT: Data file structure = netCDF Data variable information (INST=CIP/PIP): netCDF variable name Full variable name Units time Time (UTC) as hhmmss hh hrs mm min ss sec INSTcorr_conc 1-Hz binned number concentration cm-3 INSTcorr_n 1-Hz total number concentration cm-3 INSTcorr_bin_min Bin minimum diameter um INSTcorr_bin_max Bin maximum diameter um INSTcorr_bin_mid Bin arithmetic mean diameter um INSTcorr_bin_mid_geo Bin geometric mean diameter um INSTcorr_bin_dD Bin width um Sampling interval: continuous Frequency: binned to 1 Hz Data version (number and date): 1.0, 20 Feb 2014. 5.0 DATA REMARKS: Flights with RCE modules will be of greatest interest (16Nov2011, 22Nov2011, 24Nov2011, 30Nov2011, 04Dec2011) for microphysics. Boundary layer and flux modules for the most part avoided cloud. The instruments were calibrated 15 Nov 2011, 17 Nov 2011, 21 Nov 2011, and 29 Nov 2011. 6.0 REFERENCES: Korolev, A, 2006. Reconstruction of the Sizes of Spherical Particles from Their Shadow Images. Part I: Theoretical Considerations. J. Atmos. Oceanic Technol., 24, 376-389. Strapp, J.W. et al., 2011. Laboratory Measurements of the Response of a PMS OAP-2DC. J. Atmos. Oceanic Technol., 18, 1150-1170.