TITLE:

CCN Data

AUTHORS:

Suresh Dhaniyala and Meilu He Contact: sdhaniya AT clarkson DOT edu; mhe AT clarkson DOT edu; 315 268 6574 Dept. of Mechanical & Aeronautical Engineering Clarkson University Potsdam, NY 13699-5725

1.0 DATA SET OVERVIEW:

Please note this is QUALITY CONTROLLED, THOUGH STILL preliminary data THAT MAY BE SUBJECT TO FUTURE REVISION. This dataset contains ASCII text files listing particle number concentration under different supersaturation ratio using CCN mostly over investigator-defined sampling periods. It covers most of the ICE-T campaign period except RF13.

2.0 INSTRUMENT DESCRIPTION:

The Cloud Condensation Nuclei (CCN) Counter measures nucleied particle number concentration at different supersaturation. Rather than the traditional version of CCN counter where the supersaturation ratio is controlled by adjusting the temperature difference between coolers and thermocouples, in this version the supersaturation ratio is adjusted by scanning the sheath and sampling flow.   

3.0 DATA COLLECTION AND PROCESSING:

Durign sampling, the sheath and sampling flow rates and particle number concentrations are recorded. The raw data is sampled at 1 Hz. From the total flow rate, the supersaturation ratio can be calculated. Then the supersaturation is classified into ten channels 0-0.1, 0.1-0.2, 0.2-0.3, 0.3-0.4, 0.4-0.5, 0.5-0.6 0.6-0.7, 0.7-0.8, 0.8-0.9, 0.9-1.0. During each supersaturation scan only the upslope data are selected, in each supersaturation channel the CCN time and particle number concentration will be binned into one value if they are consecutive. Corresponding to this CCN time, the particle number concentration at the other supersaturation will be set as NaN. Only data after the aircraft was taken off were analyzed.

4.0 DATA FORMAT:

Data are reported in ASCII format as rows containing particle number concentration at each supersaturation channel for a selected time. Times are reported as YYYYMMDDHHmmss. The concentration has unit of #/cubic centimeter. The mean of the supersaturation at each channel is named for that channel. For example, the varialbe name Concentration_SS15 is the particle number concentration when the supersaturation is between 0.1 and 0.2 where the mean value is 0.15.

5.0 DATA REMARKS:

This is preliminary data. Please contact authors with any questions or for detailed flow rates, signal and higher resolution data.