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Cape Verde expedition 2011

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In March 2011, Christopher Benton and Jenna Tong vistited the island of Sâo Vicente, in Cape Verde, to place instruments at the Cape Verde Atmospheric Observatory. Their primary objective was to set up a GPS scintillation receiver, for detecting and studying space weather events. Data from the device is now available online. (This data will complement that from similar equipment deployed in Antarctia and in northern Scandinavia.) Their secondary objective was to test equipment for the GAARDIAN project.

Journey to Cape Verde

Christopher and Jenna arrived in Sâo Vicente on March 21st 2011. There are no regular flights between the UK and Sâo Vicente, and so the journey was made via Lisbon, Portugal, and the Cape Verdean capital, Praia, on the island of Santiago.


Christopher and Jenna's plane approaches Sâo Vicente.

The plane on arrival at Sâo Vicente.

The observatory site

The Cape Verde Atmospheric Observatory is built on the lava flow of a (hopefully) extinct volcano. Its primary purpose is to analyze air brought in from the Atlantic ocean by prevailing winds.


The Cape Verde Atmospheric Observatory. The tower is for taking air samples.

The Calhau volcanoes, which generated the pitch-black lava flow on which the observatory sits.

The observatory visible (to left of centre) from a distance.

(Click here for further images of the observatory's location.)

Scintillation receiver setup

The equipment is based around a Septentrio "PolaRxS "receiver (the blue and red box, towards the right in the below photograph). This is connected to a low-power PC (the black box in the middle). The equipment runs from an interruptible power supply (the off-white box that the other devices are sitting on), which is capable of bridging two-hour gaps in the mains electricity supply. (The grey box towards the left is a power regulator for the computer).


Equipment for the scintillation receiver station.

The black cable, entering the receiver (from the lower-right of the photograph) leads to the Antenna. It enters via a lightning protector (the gold-coloured object), which should divert excess voltages to ground (via the green and yellow earth cable).

The computer logs the raw data both internally, and to a portable hard-drive (sitting on top of the receiver in the above photograph). After a year or so, the portable drive will be returned to the UK. The computer also has a (low bandwidth) internet connection, which it uses to send a realtime summary of the data to Bath.


The antenna in position at the observatory.

GAARDIAN experiment

A secondary objective was to assess the behaviour of GAARDIAN equipment (which is designed to detect artificial sources of GPS interference) when subjected to the natural phenomenon of ionospheric scintillation. Scintillation rarely occurs at British latitudes, and so by taking the equipment to Cape Verde, the phenomenon could be observed.

For the experiment, a compact version of the GAARDIAN equipment (see the positioning navigation and timing page) was assembled. This lacked the networking hardware of the full equipment, but retained the essential GPS receiving circuitry.