Stratospheric Particle Measurements during the 2010 Concordiasi long duration balloon project from McMurdo Station, Antarctica


University of Wyoming stratospheric aerosol concentration measurements available on the anonymous ftp site: cat.uwyo.edu.
Principal Investigator: Terry Deshler, Professor, Department of Atmospheric Science, University of Wyoming, Laramie, WY 82071, USA, 307-766-2006, deshler@uwyo.edu


Collaboration: The measurements were collected from Wyoming particle counters (WPCs) flown on long duration balloon platforms released from McMurdo Station, Antarctica (78 S, 167 E) in September 2010 as part of the Concordiasi project (Rabier et al., 2010). These measurements were the culmination of the field aspect of the multi-year Concordiasi project which was an international collaboration between the Centre National d'Etudes Spatiales (CNES), Toulouse, the Laboratoire de M�t�rologie Dynamique (LMD), Paris, the University of Colorado (CU), the National Center for Atmospheric Research (NCAR), Purdue, and the University of Wyoming (UW).


Support: The Wyoming participation in this project was supported by the US National Science Foundation under grant OPP-0636946.


Instrument: The data are from in-situ balloon-borne size resolved aerosol concentration measurements collected using the Wyoming particle counter (WPC), a laser optical particle counter developed in a collaboration between Particle Metrics Inc., Boulder, and the University of Wyoming, Laramie. The nominal particle radii are: 0.075, 0.15, 0.25, 0.50, 1.0, 2.5, 5.0, and 15 um. These sizes vary slightly for 3 of the 4 instruments based on post flight calibrations. The adjusted sizes are included in each data file. For two instruments the flow rates were set to near 10 liters per minute (167 cm3 s-1) and two near 30 liters per minute (475 cm3 s-1).

Sampling periods: The WPCs were required to have an intermittant duty cycle due to constraints of power and the pump life time. Upon power up the WPC sampled, at 0.1 Hz, for 15 minutes and then 2 of every subsequent 15 minutes until powered off. The sampling strategy varied between continuous (2 of every 15 minute) sampling and long periods with no sampling. The sampling decisions depended on scientific interest and the anticipated life of pump and gondola.


Post flight checks: Surprisingly, three of the four WPCs were recovered after flight. Post fight checks on the nominal size thresholds found all to be within 10-20% of their nominal pre flight values. A description of the post flight checks is found here.

 

Access: If these data are useful for your work and/or publication, I would appreciate inclusion and/or proper referencing and acknowledgment for the source of these data.

 

Data: The data and summary plots can be found within the directory ftp://cat.uwyo.edu/pub/permanent/balloon/Aerosol_InSitu_Meas/Lagrangian_Meas_South_of_60S/  where there are the following subdirectories:
       .../PSC14_2010_0914_0916/             aka PSC1-1, WPC-J9 - lost       - data file: psc14_j9_100914-100916_drft_oz_tfilt.dat

       .../PSC15_2010_0908_0914/             aka PSC1-2, WPC-J6 - recovered McMurdo - October 2010 -  data file: psc15_j6_100908-100914_drft_oz_tfilt.dat

       .../PSC16_2010_0911_0930/             aka PSC3-1, WPC-J8 - recovered McMurdo - October 2010 -   data file: psc16_j8_100911-100930_drft_oz_tfilt.dat

       .../PSC17_2010_0914_1014/             aka PSC3-2, WPC-J7 - recovered Tasmania - December 2010 - data file: psc17_j7_100914_101014_drft_oz_tfilt.dat  -- Warning!
                                                                  The large particle data, at sizes above the third channel, from PSC17 are highly questionable and should not be used for
                                                                   scientific purposes.

Files: In addition to the data files, each folder contains image files in .ps format which summarize the measurements in the data files.


Structure of the data files pscNN_jN_yymmdd-yymmdd_drft.dat:


The yymmdd-yymmdd corresponds to the time span of the measurements. The files are ascii files with 24 columns and 66 header lines which explain the file structure. The data files are a composite of measurements from the WPC, LMD, and CNES's payload managements system ISBA. When both LMD and ISBA provide the same quantity, I include first LMD data if available and then ISBA. The source for the data in each data column is indicated below.


Column - Data

1  - year month day (yymmdd) - PSB
2  - hour minute sec (hms) - PSB
3  - decimal day of the current year, calculated. Convention 12:00:00 UT on January 1 = 1.50000
4  - aerosol concentration (cm-3) radius > .075 micrometers -WPC
5  - aerosol concentration (cm-3) radius > 0.15 micrometers -WPC
6  - aerosol concentration (cm-3) radius > 0.25 micrometers -WPC
7  - aerosol concentration (cm-3) radius > 0.50 micrometers -WPC
8  - aerosol concentration (cm-3) radius > 1.00 micrometers -WPC
9  - aerosol concentration (cm-3) radius > 2.50 micrometers -WPC
10 - aerosol concentration (cm-3) radius > 5.00 micrometers -WPC
11 - aerosol concentration (cm-3) radius > 15.0 micrometers -WPC
12 - temperature (C) - LMD/ISBA
13 - pressure (hPa) - LMD/ISBA
14 - altitude (km) GPS - LMD/ISBA
15 - potential temperature calculated
16 - latitude GPS (decimal degrees) - LMD/ISBA
17 - longitude GPS (decimal degrees, 0-360) - LMD/ISBA
18 - solar zenith angle (degrees) - LMD
19 - super pressure (hPa) - ISBA
20 - laser voltage (V) - WPC
21 - laser current (A) - WPC
22 - battery voltage (V) - ISBA
23 - WPC pump temperature (�C) - WPC
24 - laser temperature (�C) - ISBA
25 - ozone (ppb) - from LMD (PSC14, 15) and from CU (PSC16, 17)
 The minimum concentration measurable with these instruments is given by S / F, for sample frequency, S=0.1 Hz, and flow rate, F. The minimum concentration detectable is 6 and 2 x 10-4 cm-3 for F = 167 and 475 cm3 s-1. When the aerosol concentration is below the detection threshold of the instrument the concentration is given as 1.01E-39.


Poisson statistics define the fractional uncertainty of a counting measurement as its inverse square root, C-0.5 for C counts in one sample, becoming important at low concentrations. The aerosol concentration, N = C S / F. Thus the Poisson error fraction, in terms of concentration, is (N F / S)-0.5. For these instruments: S = 0.1 Hz, F = 167 and 475 cm3 s-1. This leads to uncertainties of 85, 25, and 8% for concentrations 0.001, 0.01, 0.1 cm-3 at the low flow rate, decreasing a factor of approximately 1/sqrt(3) for the higher flow rate. This error dominates at concentrations below 0.01 cm-3. At higher concentrations a concentration error of �10% reflects comparisons of concentration measurements from two instruments using identical aerosol in the laboratory.



Rabier, F., et al., The Concordiasi project in Antarctica, (2010), Bull. Amer. Meteor. Soc., DOI :10.1175/2009BAMS2764.1, 69-86.