Our meeting this month is a special event for several reasons.   Copies of Andrew's book will be available to the first 50 attendees, and the HDF Group will be providing refreshments for us.  Also, this may be our last meeting at the Boulder Outlook Hotel, as the hotel has been sold.  So, please join us in the Crown Rock room (not our usual room) at the Outlook for:

Improving Science with Open Formats and High-Level Languages: Python and HDF5

Andrew Collette, Laboratory for Atmospheric and Space Physics (LASP)

This talk explores how researchers can use the scalable, self-describing HDF5 data format together with the Python programming language to improve the analysis pipeline, easily archive and share large datasets, and improve confidence in scientific results.  The discussion will focus on real-world applications of HDF5 in experimental physics at two multimillion-dollar research facilities: the Large Plasma Device at UCLA, and the NASA-funded hypervelocity dust accelerator at CU Boulder.  This event coincides with the launch of a new O’Reilly book, Python and HDF5: Unlocking Scientific Data, complimentary copies of which will be available for attendees.

As scientific datasets grow from gigabytes to terabytes and beyond, the use of standard formats for data storage and communication becomes critical.  HDF5, the most recent version of the Hierarchical Data Format originally developed at the National Center for Supercomputing Applications (NCSA), has rapidly emerged as the mechanism of choice for storing and sharing large datasets.   At the same time, many researchers who routinely deal with large numerical datasets have been drawn to the Python by its ease of use and rapid development capabilities. 

Over the past several years, Python has emerged as a credible alternative to scientific analysis environments like IDL or MATLAB.  In addition to stable core packages for handling numerical arrays, analysis, and plotting, the Python ecosystem provides a huge selection of more specialized software, reducing the amount of work necessary to write scientific code while also increasing the quality of results.  Python’s excellent support for standard data formats allows scientists to interact seamlessly with colleagues using other platforms.

Schedule (more or less)

4:00 - 5:00 presentation
5:00 - 6:00 social

Regridding of data is a common problem faced by many scientific software developers.   If regridding is part of your world, this talk may be of interest to you.  Come join us at the Boulder Outlook Hotel for this month's talk:

There is more to conservative interpolation--- interpolating edge and face centered fields in the geo-sciences

Alexander Pletzer, Tech-X

Interpolation is one of the most widely used postprocessing tasks, according to a survey of Ultrascale Visualization Climate Data Analysis Tools (UV-CDAT) users. Most geo-postprocessing tools (UV-CDAT, NCL, Ferret, etc) support a choice of both bilinear and conservative regridding with conservative interpolation guaranteeing that the total amount of "stuff" (energy, water, etc) remains unchanged after regridding. The SCRIP and ESMF are examples of libraries implementing these interpolation methods.

We argue that the type of interpolation is dictated by the type of field and that cell centered fields require conservative interpolation whereas nodal fields require bilinear (or higher order) interpolation. Moreover, the wind velocity fields used by finite-volume atmospheric codes, which are neither cell-centered nor nodal but face-centered (Arakawa D staggering), require different interpolation formulas. Interpolation formulas of face-centered and edge-centered (Arakawa C) fields have been known as Whittney forms since 1957 and are widely used in electromagnetics. We present interpolation methods new to the geo-sciences that conserve flux and line integrals for Arakawa D, respectively Arakawa C, stagggered fields.

This talk should be of interest to anybody in need to regrid velocity and other vector fields whose components are staggered with respect to each other.

Schedule (mostly)

4:00 - 5:00 Presentation
5:00 - 6:00 Social