TITLE:

HDDMA 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 size distributions in the range of 10-400 nm using HDDMA mostly over investigator-defined sampling periods (the data during the period when HDDMA is under zero test is set as NaN). It covers most of the ICE-T campaign period except RF01, RF02, and RF09. Two files with different particle size ranges are submitted, for each flight. For example RF03_HDDMA100_ICET_v1.txt contains particle size distribution for RF03 for particle sizes smaller than 100 nm, while RF03_HDDMA400_ICET_v1.txt contains particle size distributions for RF03 for particle size distributions smaller than 400nm.

2.0 INSTRUMENT DESCRIPTION:

The High-flow Dual-channel Differential Mobility Analyzer (HDDMA) sizes particles based on their electrical mobility. If particles are singly charged, selected particle sizes are proportional to the applied voltage on the HDDDMA. The HDDMA differs from the standard DMA in several ways. First, the instrument can be operated at high aerosol flow rates to minimize the diffusional loss and smearing times. Second, high sheath flow rates are possible with the instrument, allowing for scanning time down to 20 seconds or less. Third, the instrument is designed to minimize any distortion in its transfer functions due to fast scanning. Fourth, the HD-DMA has two sample ports, extending the particle size measurement range without loss of resolution. The sheath flow rate, aerosol flow rate, scanning time are program-adjustable. During ICE-T, the lower port is operated to size particles in the range of ~ 30-400 nm while the lower port is operated to size particles in the range of 10 nm to ~ 100 nm.  

3.0 DATA COLLECTION AND PROCESSING:

Durign each scan, all the flow rates, high voltage, temperatur, pressure, RH, and two CPC signals are recorded. The raw data is sampled at 10 Hz. To improve the signal noise ratio, the CPC signals are binned to 1 Hz before inversion. After the campaign, the offset time, smearing time, and high voltage effective factor are obtained based on laboratory tests. The signals are desmeared based on an expotential probability distribution. Three different inversion methods (zeroth order, fitted multiple charging correction, and Hoppel multiple charging correction; He and Dhaniyala, 2013) are used to obtain particle size distributions. In the data file, the reported particle size distributions are only from zeroth order inverison.

4.0 DATA FORMAT:

Data are reported in ASCII format as rows containing particle size distibution at each size channel (dN/dlogDp) for a selected time. All concentrations are reported at ambient temperature and pressure. Times are reported as YYYYMMDDHHmmss. The concentration has unit of #/cubic centimeter.

5.0 DATA REMARKS:

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

6.0 REFERENCES:

Meilu He, Suresh Dhaniyala, 2013: A multiple charging correction algorithm for scanning electrical mobility spectrometer data, Journal of Aerosol Science, 61, 13-26.