diff --git a/docs/examples/ex_gnss_tec.rst b/docs/examples/ex_gnss_tec.rst index aecc920..ee900a6 100644 --- a/docs/examples/ex_gnss_tec.rst +++ b/docs/examples/ex_gnss_tec.rst @@ -1,18 +1,21 @@ .. _ex-gnss-tec: -Plot GNSS TEC -============= +GNSS TEC +======== The Global Navigation Satellte System (GNSS) Total Electron Content (TEC) is one of the most valuable ionospheric data sets, given its long and continuous operational duration and expansive coverage. :py:mod:`pysatMadrigal` currently -only supports Vertical TEC (VTEC) data handling through -:py:mod:`pysatMadrigal.instruments.gnss_tec`. +supports Vertical TEC (VTEC), Line-of-Site (LoS) Slant TEC, and ground receiver +data handling through :py:mod:`pysatMadrigal.instruments.gnss_tec`. -The VTEC measurements are median filtered to fill 1 degree latitude by 1 -degree longitude bins. This can be represented with spatially representative -coverage as shown in the example below. Start by obtaining the desired data -and loading it. +Plot VTEC Maps +-------------- + +The Madrigal VTEC maps are made up of median filtered data placed in 1 degree +latitude by 1 degree longitude bins. This can be represented with spatially +representative coverage as shown in the example below. Start by obtaining the +desired data and loading it. .. code:: @@ -81,3 +84,39 @@ a regular grid with VTEC value indicated by color. :width: 800px :align: center :alt: Mapped median Vertical Total Electron Content over the globe. + + +Load LoS TEC +------------ + +The data used to create the Madrigal VTEC maps is available in the LoS TEC +files. These files contain both the Vertical and Slant TEC from the available +GNSS satellite networks. These files are large (several GB) and may not +successfully download through the MadrigalWeb interface. In such instances, it +may be simpler to download the desired data directly from the Open Madrigal +website. + +Once downloaded, the data is best loaded in subsets. Current load options +include loading data by a unique receiver name ('site'), a unique satellite ID +('prn', 'sat', 'sat_id'), a time ('time', 'unix', 'ut1_unix', or 'ut2_unix'), +an orientation ('azm', 'elm'), or a location ('gdlatr', 'gdlat', 'gdlonr', +'glon'). If specifying a time, orientation, or location a range may also be +specified, as illustrated in the following example. + +.. code:: + + tec = pysat.Instrument(inst_module=pysat_mad.instruments.gnss_tec, + tag='los') + ftime = dt.datetime(2013, 1, 1) + + # If this fails, access data at: + # http://cedar.openmadrigal.org/single?isGlobal=on&categories=17&instruments=8000&years=2013&months=1&days=1 + # Then save the data with a '.hdf5' extension in the directory found by: + # print(tec.files.data_path) + if not ftime in tec.files.files.index: + tec.download(start=ftime, user='firstname+lastname', password='myname@email.address') + + # Load only the GPS data from -40 to -20 degrees longitude + tec.load(date=ftime, los_method='glon', los_value=-30, los_range=10, + gnss_network='gps') +