 |
| Titel |
Results and recommendations from an intercomparison of six Hygroscopicity-TDMA systems |
| VerfasserIn |
A. Maßling, N. Niedermeier, T. Hennig, E. O. Fors, E. Swietlicki, M. Ehn, K. Hämeri, P. Villani, P. Laj, N. Good, G. McFiggans, A. Wiedensohler |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1867-1381
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 4, no. 3 ; Nr. 4, no. 3 (2011-03-08), S.485-497 |
| Datensatznummer |
250001797
|
| Publikation (Nr.) |
 copernicus.org/amt-4-485-2011.pdf |
|
|
|
|
|
| Zusammenfassung |
The performance of six custom-built Hygrocopicity-Tandem Differential
Mobility Analyser (H-TDMA) systems was investigated in the frame of an
international calibration and intercomparison workshop held in Leipzig,
February 2006. The goal of the workshop was to harmonise H-TDMA measurements
and develop recommendations for atmospheric measurements and their data
evaluation. The H-TDMA systems were compared in terms of the sizing of dry
particles, relative humidity (RH) uncertainty, and consistency in determination
of number fractions of different hygroscopic particle groups. The
experiments were performed in an air-conditioned laboratory using ammonium
sulphate particles or an external mixture of ammonium sulphate and soot
particles.
The sizing of dry particles of the six H-TDMA systems was within 0.2 to 4.2%
of the selected particle diameter depending on investigated size and
individual system. Measurements of ammonium sulphate aerosol found
deviations equivalent to 4.5% RH from the set point of 90% RH compared to
results from previous experiments in the literature. Evaluation of the
number fraction of particles within the clearly separated growth factor
modes of a laboratory generated externally mixed aerosol was done. The data
from the H-TDMAs was analysed with a single fitting routine to investigate
differences caused by the different data evaluation procedures used for each
H-TDMA. The differences between the H-TDMAs were reduced from +12/−13%
to +8/−6% when the same analysis routine was applied. We
conclude that a common data evaluation procedure to determine number
fractions of externally mixed aerosols will improve the comparability of
H-TDMA measurements.
It is recommended to ensure proper calibration of all flow, temperature and
RH sensors in the systems. It is most important to thermally insulate the
aerosol humidification unit and the second DMA and to monitor these
temperatures to an accuracy of 0.2 °C. For the correct determination of
external mixtures, it is necessary to take into account size-dependent
losses due to diffusion in the plumbing between the DMAs and in the aerosol
humidification unit. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|