“At around 5 AM Pacific Time (1 PM GMT) today (March 7th) the GPS satellites started transmitting inconsistent health information causing Swift Navigation receivers to exclude measurements from any satellites supporting the L2C signal. This has resulted in degraded or unavailable position information and decreased ability to achieve an RTK Fixed solution.”
We kept an eye on the data coming in – as it is not easy to go to Iceland and update the firmware..
This plot shows how the gps behaviour changed after the march 7th announcement. Without knowing this we could have assumed it was caused by something like wet snow cover.
Today we set up two dGPS units to measure the speed of some of Fjallsjökull glacier. We chose an area of ice which is clearly moving forward towards the lake.
Here is the dGPS system setup on Fjallsjokull, with Jane Hart and Frey
The photo above shows a “quadpod” supporting the GPS units – which are an adaptation of those made by Matthew Roberts of the Icelandic met-office. The idea is to be strong enough to cope with winter and cast few shadows (which cause ice to grow). The system is currently measuring its position every 3hrs to an accuracy of about 2cm – using signals from the base station to help it.
the dGPS base station installed on a moraine close to the Fjallsjokull glacier. We used speaker stands burried in rocks to support the GPS antenna (top) and hold its 2.4GHz radio antenna (white stick). Shortly after this photo I accidentally kicked sand into the laptop keyboard – so it was not so easy to use after that!
View of Fjallsjokull with our deployement being almost in the middle of this photo.
Iceberg tracker temperatures from 9/8/16 to 7/10/16
We have been checking the iceberg tracker temperature as one way of telling if it is in the sea is a flatter daily variation in temperatures. Here you can see it did regularly read sub-zero at midnight then warmer an noon. Recently however it is showing mainly positive temperatures.
iceberg tracker locations up to 7/10/16
After spending weeks among the small islands in the centre of this map – it has moved south until reaching land again. This dramatic movement may be because the iceberg has broken up.
Together with the sustainability team of Formula E we were able to put a GPS tracker on an emerging Iceberg in order to see its movement in great detail. The box contains a tracker which sends the GPS location and temperature twice per day via satellite messages.
Our GPS data is showing us that the iceberg we are tracking has been drawn into some islands and has stopped moving significantly. The MODIS image data from Nasa was very clear on this day and it is possible to see ice between the islands:
Satellite image of the iceberg being tracked in Greenland – on Aug 29th 2016
This is a GPS tracker we quickly built as a test of tracking icebergs – it uses Satellite (Iridium) short text messages to send its location to us every 12hrs. Inside is a large lithium battery pack. The photo below shows a water test in the sink – just in case it ends up in the sea. We used a unit from YB Tracking. More info later!
GPS satellite tracker we built for a test on a Greenland iceberg