In Glacsweb we have used Topcon and Leica dGPS equipment to continuously monitor glacier flow. Normal GPS is accurate to a few metres and would be too inacurate to measure small movements of the glacier. Differential GPS (dGPS) can be much more accurate (millimetres) but requires specialised hardware and software. We installed several dGPS recorders on the glacier to measure the surface changes over the years.Each recording is processed on our server (together with a “fixed” location recording) to produce a long term record of movement and melting. The NERC equipment pool loan of Leica units allowed us to measure points over a wide area on the glacier as well as place a “fixed” point on the moraine. Read our report here.
We have also experimented with simpler (L1 only) chips (LEA-6) which are much lower cost – at the price of some accuracy (we obtained 9cm accuracy, 17cm vertically, with a 2hr recording run against the Leica reference station on the moraine 100m away).