Cooperative Institute for Research in Environmental Sciences

Science Rendezvous > 2009 Posters
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A Community Software Tool for Quality Control and Analysis of Data from the Aerodyne Time-of-Flight Aerosol Mass Spectrometers (ToF-AMS)

Donna Sueper, Aerodyne and University of Colorado, Boulder; James Allan, University of Manchester; Edward Dunlea, University of Colorado, Boulder; Jonny Crosier, University of Manchester; Joel Kimmel, Peter DeCarlo, Allison Aiken, Jose-Luis Jimenez, University of Colorado, Boulder; Doug Worsnop, Aerodyne

The ToF-AMS (Drewnick et al., 2005) and high-resolution ToF-AMS (HR-ToF-AMS, DeCarlo et al., 2006) are the new versions of the Aerodyne AMS, and are rapidly superseding the quadrupole AMS (Q-AMS). The data quality control and analysis tasks are enormous for ToF-AMS datasets, due to the size (a typical dataset size is 25 GB) and dimensionality (3-4 mathematical dimensions) of the data produced. A software tool for ToF-AMS data management and analysis called SQUIRREL will be presented (Sueper et al., 2007). As was the case with the Q-AMS analysis software, SQUIRREL is also shared with the entire AMS Users Community and improved with feedback from all users. This leads to faster development and ensures consistent processing of ToF-AMS data. The architecture of SQUIRREL is centered on the premise that most data are kept in the computer hard drive, as ToF-AMS datasets are too large to completely reside in computer memory. The ToF-AMS data acquisition software saves the data in Hierarchical Data Format (HDF5), a highly structured binary format that was developed by NCSA with NASA funding for satellite applications. HDF5 files can be accessed randomly, which greatly reduces seek times over the text file system used in the Q-AMS acquisition and analysis software. The name "SQUIRREL" reflects the ability of the software to quickly move pieces of the data ("acorns") between the memory and the hard drive. The basic principles of data analysis are adapted from those from the Q-AMS (e.g. Allan et al., 2003, 2004). Along with flexible and detailed mass calibration and baseline fitting routines, SQUIRREL incorporates techniques to handle high-speed recording and multiple ionization schemes. Additional modules can be built upon SQUIRREL for specialized analyses. An example of such a module is the code to characterize the chemical information contained in the high-resolution mass spectra from the HR-ToF-AMS. Examples of application of SQUIRREL and HR-SQUIRREL to real datasets, and directions for future development will be given.