Cluster analysis of WIBS single-particle bioaerosol data

N H Robinson,M Gallagher,P H Kaye,V E Foot,J D Allan,J A Huffman

doi:10.5194/amt-6-337-2013

Abstract

Abstract. Hierarchical agglomerative cluster analysis was performed on single-particle multi-spatial data sets comprising optical diameter, asymmetry and three different fluorescence measurements, gathered using two dual Wideband Integrated Bioaerosol Sensors (WIBSs). The technique is demonstrated on measurements of various fluorescent and non-fluorescent polystyrene latex spheres (PSL) before being applied to two separate contemporaneous ambient WIBS data sets recorded in a forest site in Colorado, USA, as part of the BEACHON-RoMBAS project. Cluster analysis results between both data sets are consistent. Clusters are tentatively interpreted by comparison of concentration time series and cluster average measurement values to the published literature (of which there is a paucity) to represent the following: non-fluorescent accumulation mode aerosol; bacterial agglomerates; and fungal spores. To our knowledge, this is the first time cluster analysis has been applied to long-term online primary biological aerosol particle (PBAP) measurements. The novel application of this clustering technique provides a means for routinely reducing WIBS data to discrete concentration time series which are more easily interpretable, without the need for any a priori assumptions concerning the expected aerosol types. It can reduce the level of subjectivity compared to the more standard analysis approaches, which are typically performed by simple inspection of various ensemble data products. It also has the advantage of potentially resolving less populous or subtly different particle types. This technique is likely to become more robust in the future as fluorescence-based aerosol instrumentation measurement precision, dynamic range and the number of available metrics are improved.

Highlights

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It can reduce the level of subjectivity compared to the more standard analysis approaches, to identify the date, this has glarrogueplytobweehnicahScahoimelveiedadsuEbreyadtrPhtBehAusPeboefloonfgfs-.liTnoe which are typically performed by simple inspection of var- techniques, which, whilst allowing accurate identification of ious ensemble data products
We demonstrate the application of a cluster analysis technique to the Wideband Integrated Bioaerosol Sensor (WIBS) single-particle data, allowing for robust statistical resolution of different Primary biological aerosol particles (PBAPs) subgroups

Summary

Methods and Data

Asymmetry and three different fluo- Primary biological aerosol particles (PBAPs) are those which rescence measurements, gathered using two dual Wideband are emitted or suspended directly from the biosphere to the Integrated Bioaerosol Sensors (WIBSs). EThsere is evidence that PBAPs may influence the hydrological cycle and climate ing: non-fluorescent accumulation mode aerosol; bacterial by initiating warm ice nucleation processes To our knowledge, this is 2008; Mohler et al, 2007; Pratt et al, 2009; Prenni et al, the first time cluster analysis has been applied to long-term online primary biological aerosol particle (PBAP) measure-. In order to predict these potential without the need for any a priori assumptions concerning effects under future emissions scenarios, it is useful to be able the expected aerosol types It can reduce the level of subjectivity compared to the more standard analysis approaches, to identify the date, this has glarrogueplytobweehnicahScahoimelveiedadsuEbreyadtrPhtBehAusPeboefloonfgfs-.liTnoe which are typically performed by simple inspection of var- techniques, which, whilst allowing accurate identification of ious ensemble data products. We demonstrate the application of a cluster analysis technique to the WIBS single-particle data, allowing for robust statistical resolution of different PBAP subgroups

The Wideband Integrated Bioaerosol Sensor

Analysis techniques

Introduction

Findings

Conclusions