GNSS-RO is a technique that provides unique temperature, pressure, and moisture vertical soundings through the atmosphere, similar to the type of data collected by a weather balloon. Rather than data being available only twice per day from specific sites, GNSS-RO utilizes Spire’s satellite constellation to collect soundings 24/7 on a global basis and over remote regions like the oceans and the poles. In addition to being an important input for weather forecasting, GNSS-RO is also a climate quality measurement. 


GNSS-RO data is output using the BUFR format convention. BUFR files are a binary data format that include bending angle, refractivity, and dry temperature as a function of altitude during a radio occultation event. The three sets of profile information (bending angle, refractivity, and dry temperature) represent increasing levels of Spire processing of the excess phase measurements recorded by the CubeSat GNSS receiver. BUFR files are commonly used by the World Meteorological Organization (WMO) for ingestion into Numerical Weather Prediction (NWP) models for data assimilation, and radio occultation is one of several remote sensing datasets that can be converted into BUFR files to describe meteorological data. The BUFR files produced by Spire comply with the BUFR files produced by the COSMIC Data Analysis and Archive Center (CDAAC) for COSMIC radio occultation data products.


A full description of the BUFR file contents, including data description, data templates, and software applications for decoding BUFR files, can be found here. Radio occultation is assigned to the global section of Table D as descriptor "3 10 026" within the BUFR standard. Within the comprehensive BUFR document, the BUFR Section 4 Data Template listed in Table 5 describes the binary data, including the three sets of profile information (bending angle, refractivity, and dry temperature as a function of altitude).


Available Data

Precise Orbit Determination (POD) files

LEO Attitude files

BUFR Atmospheric Retrievals

Data Statistics

Coverage: Global

Vertical Resolution: 100 m

Temperature Accuracy: <1℃

Constellations Tracked: GPS, Galileo, GLONASS, QZSS



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