LESIA Observatoire de Paris-PSL CNRS vopdc cdpp Sorbonne Université cnes Université de Paris


Monday 4 March 2019, by Baptiste Cecconi

The Das2 and Autoplot system allows to stream data with adaptive temporal resolution. The MASER datasets are served from Das2 servers and can be visualized through Autoplot.


Das2 is a server framework developed by University of Iowa [1], which allows to stream data using the das2stream [2] protocol.

This protocol can stream data with adaptative temporal resolution. The client sends a query including the request temporal resolution, and the server sends back data at the requested resolution. The data is either resampled on the fly, or extracted from the server cache, upon server-side configuration.

Each Data Source on a Das2 server is configured with a simple text file, which defines how the server shall process the original data, the levels of cache, the data temporal span, and a set of example intervals. An example data source definition file (.dsdf) for a das2stream served from Nançay:

description = 'Nancay/NDA/Routine Jupiter dataset - LH polarized power'
reader = '/usr/local/bin/das2rdr/das2nancay/das2_maser_nda_routine.py jup 0'
das2Stream = 1
techContact = 'contact.maser@obspm.fr'
sciContact = 'Laurent Lamy <laurent.lamy@obspm.fr>'
readAccess = 'AGE:1m|GROUP:NDA'
securityRealm = 'Nancay Decameter Array Team Access'
validRange = '1990-10-01T00:00:00 to NOW'
exampleRange_00 = '2015-07-01T17:14:00 to 2015-07-01T17:15:00'
exampleRange_01 = '2012-12-03T07:15:00 to 2012-12-03T08:30:00'
exampleRange_02 = '2014-09-03T11:17:00 to 2014-09-03T11:22:00'
cacheLevel_00 = '60 s | hourly'
cacheLevel_01 = '1200 s | daily'
cacheLevel_02 = '86400 s | monthly'
dataproductType = 'ds'
measurementType = 'phys.flux.density;phys.polarization.circular;em.radio'
targetName = 'Jupiter'
targetClass = 'planet'
targetRegion = 'magnetosphere'
featureName = 'radio emissions#DAM'

The reader parameter is the script to be launched to read the data internally, with adequate input parameters. Additional VESPA related metadata are provided for direct ingestion of .dsdf files into an EPNcore catalogue.

The Das2 server can be downloaded from the University of Iowa Svn server: [https://saturn.physics.uiowa.edu/svn/das2/servers/stable/pyserver/]


Autoplot is a stand-alone client application developed by University of Iowa [3]. This client is including many client interfaces and can read most of the space physics community data formats. The figure below shows a plot done in Autoplot, with Cassini/RPWS/HFR/N2 dataset, accessed through a das2 server interface.


[1Chris Piker et al., AGU 2018, ESSOAr, doi:10.1002/essoar.10500359.1

[2Piker, C. et al, 2017. Das2 ICD

[3Faden, J, et al. 2010. “Autoplot: a Browser for Scientific Data on the Web.” Earth Sci. Inform. 3: 41–49. doi:10.1007/s12145-010-0049-0