1. PROJECT
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Title: VOLCLAB 
Dates: 1/10/2016 - 31/12/2017
Funding organisation: NERC 
Grant no.:NE/P003362/1

The radiosonde packages were funded by the UK Natural Environmental Research Council (grant number NE/P003362/1) and the field campaign to Stromboli by a National Geographic Expeditions fund. 

2. DATASET
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Title: Supplementary data for "First observations of gaseous volcanic plume electrification: a new source of charge for volcanic lightning".  Submitted to Nature Geoscience.

Description: This dataset contains the processed radiosonde and additional surface VOLCLAB sensor data for a measurement campaign at Stromboli volcano during 28th September to 4th October 2017.
Full details are given in the above titled paper.  The data for figures 1,3 and 4 are provided here. 

Creator(s): Keri A. Nicoll, Martin W. Airey, R. Giles Harrison, Graeme J. Marlton, Paul D. Williams
Organisation(s): University of Reading
Rights-holder(s): University of Reading

3. TERMS OF USE
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This dataset is licensed by the rights-holder(s) under a Creative Commons Attribution 4.0 International Licence: https://creativecommons.org/licenses/by/4.0/.

4. CONTENTS
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Readme.txt				2	Kb

Flight1_met.txt				127	Kb	
Flight1_charge.txt 			10	Kb
Flight1_droplet.txt			8	Kb
Flight1_SO2.txt				15	Kb

Flight2_met_descent.txt 		2	Kb
Flight2_charge_descent.txt		4	Kb
Flight2_met_ascent.txt			4	Kb
Flight2_charge_ascent.txt 		14	Kb

Fig4_SO2.txt				138	Kb




5. METHOD and PROCESSING
--------------------------


Full details are available from the author of the dataset – Dr Keri Nicoll (k.a.nicoll@reading.ac.uk) 

Figure1 folder 
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- contains radiosonde data from flight 1: launched from Stromboli at 11:40 UT on 30th Sept 2017 measured by a Vaisala RS92 radiosonde and the VOLCLAB sensor package 

Flight1_met.txt
- RS92 radisonde data.  Columns are as follows: counter, time (secs), height (km), Temperature (degC), RH (%)

Flight1_charge.txt 
-VOLCLAB charge sensor data.  Columns are as follows: counter, height (km), space charge density (pCm-3)
Charge sensor details in: Harrison, R.G., Marlton G.,  Nicoll K., Airey M., Williams P.,  Note: A self-calibrating wide range electrometer for in-cloud measurements, Review of Scientific Instruments, 88, 126109-12611, DOI: 10.1063/1.5011177, 2017

Flight1_droplet.txt
- VOLCLAB optical droplet sensor data.  Columns are as follows: counter, height (km), droplet concentration (cm-3), droplet diameter (microns)
Droplet sensor calibration is detailed in the supplementary information section of this paper (First observations of gaseous volcanic plume electrification: a new source of charge for volcanic lightning)

Flight1_SO2.txt
- VOLCLAB SO2 sensor (ALphasense SO2-B4). Columns are as follows: counter, height (km), SO2 concentration (ppm)



Figure3 folder
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- contains radiosonde data from flight 2: launched from Stromboli at 11:55 UT on 4th October 2017 measured by a Vaisala RS92 radiosonde and the VOLCLAB sensor package

Flight2_met_descent.txt 
- RS92 radisonde data from initial descent through volcanic plume.  Columns are as follows: counter, height (km), Temperature (degC), RH (%)

Flight2_charge_descent.txt
-VOLCLAB charge sensor data from initial descent through volcanic plume. Columns are as follows: counter, height (km), space charge density (pCm-3)
Charge sensor details and voltage to space charge calibration in Nicoll, K.A., A self-calibrating electrometer for atmospheric charge measurements from a balloon platform, 84, 096107, Rev. Sci. Instrum.,doi: 10.1063/1.4821500, 2013
and Nicoll, K.A., R.G. Harrison, Stratiform cloud electrification: comparison of theory with multiple in-cloud measurements, Q.J.Royal Met. Soc., 142, 2679-2691, 2016, doi:10.1002/qj.2858. 

Flight2_met_ascent.txt
- RS92 radisonde data from initial descent through volcanic plume. Columns are as follows: counter, height (km), Temperature (degC), RH (%)

Flight2_charge_ascent.txt 
-VOLCLAB charge sensor data from ascent through volcanic plume. Columns are as follows: counter, height (km), space charge density (pCm-3)
Charge sensor details and voltage to space charge calibration in Nicoll, K.A., A self-calibrating electrometer for atmospheric charge measurements from a balloon platform, 84, 096107, Rev. Sci. Instrum.,doi: 10.1063/1.4821500, 2013
and Nicoll, K.A., R.G. Harrison, Stratiform cloud electrification: comparison of theory with multiple in-cloud measurements, Q.J.Royal Met. Soc., 142, 2679-2691, 2016, doi:10.1002/qj.2858. 


Figure4 folder
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- contains surface measurements of SO2 from the VOLCLAB sensor package in the 1 hour (from 11-12UT) around the launch time of flight 2.

Fig4_SO2.txt
VOLCLAB SO2 sensor (ALphasense SO2-B4).  Columns are: counter, time (decimal),SO2 concentration (ppm)