Dr. Matthieu Talpe – Remote Sensing from the Spire Constellation of GNSS Receivers

CESOC & DETECT kindly invites you to a joint Colloquium given by Dr. Matthieu Talpe from Spire Global, Luxembourg.

Date: 16 November 2023,
Time: 10
:00 CEST
Location: Online via ZOOM

for  participation, please contact info@cesoc.net

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Remote Sensing from the Spire Constellation of GNSS Receivers, with a focus on Geodesy and Meteorology Applications

Matthieu holds a Phd degree from Colorado University, Boulder, US. He has worked at NASA/JPL, and he is now a remote sensing product engineer at SPIRE GLOBAL. The SPIRE company has created a vast constellation of nanosatellites and pioneers the use of nanosat data for environmental monitoring and scientific applications, including sea level studies, wildfire monitoring, and weather forecast.

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Remote Sensing from the Spire Constellation of GNSS Receivers, with a focus on Geodesy and Meteorology Applications

Spire Global is an Earth Observation company operating about 100 cubesats. Spire’s main activities include remote sensing and spectrum monitoring via L-band signals, maritime tracking via Automatic identification System (AIS) signals, and aviation tracking via Automatic Dependent Surveillance-Broadcast (ADS-B) signals. This seminar provides an overview of remote sensing applications, with a focus on geodesy and meteorology.

In meteorology, we present activities related to GNSS Radio Occultations (RO). Spire Global is a world-leading provider of RO measurements to weather agencies such as EUMETSAT and NOAA, producing over 15,000 measurements daily from up to 25 cubesats. The measured bending angle of the Right-Handed Circularly Polarized (RHCP) ray is used to infer local atmospheric pressure, temperature, and humidity, which have become important operational inputs to Numerical Weather Prediction (NWP) models because of their global coverage and short latencies. Furthermore, three Polarimetric RO payloads have been tested in-orbit since early 2023, measuring H- and V-polarizations instead of just RHCP. The differential phase shifts observed by the phase delays in the H and V polarizations are shown to match with precipitation events as determined by colocations with the IMERG product. The goal of these novel datasets, which can uniquely sense hydrometeors, is to augment operational NWP models.

In geodesy, two applications are discussed: altimetry and time-variable gravity. In 2019, the RO satellites were reprogrammed to also receive signals reflected coherently from the Earth’s surface at grazing angles (less than 30 degrees of elevation), adding GNSS-Reflectometry (GNSS-R) measurements to Spire’s operational data production. The carrier phase information of the reflected and direct signals is used to estimate relative surface altimetry. We demonstrate that decimeter-level accuracy is achieved. Additionally, tracking data collected by the zenith-pointing POD antennas have been recently used to extract meaningful time-variable gravity signals [personal communication with T. Grombein et al.].

Lastly, we provide a brief overview of other remote sensing activities enabled by Spire cubesats dedicated to near-nadir GNSS-R, namely ocean winds and soil moisture.

 

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