Borehole temperature monitoring in glaciers, permafrost and ice sheets
What is the borehole doing through the winter, when nobody can get there?
What is the borehole doing through the winter, when nobody can get there?
The interesting months are the ones when the site is unreachable. The instrument sleeps between profiles, draws under a watt on average, keeps everything on local storage, and sends summaries whenever the link is up.
- An hourly or four-hourly profile of the whole borehole, every day of the season.
- The zero-degree isotherm, active-layer depth and basal gradient tracked automatically.
- Refreezing of a hot-water-drilled hole followed from the first profile.
- Data completeness, battery and link status in a daily line, so you know it is alive.
The event, and the signal
- Nobody visits for months. The instrument wakes once an hour, records the profile, sleeps.
- The surface swings with the seasons; a few metres down the swing has died out.
- The zero-degree line and the active layer are read off every profile, all winter.
Setup
| Fibre | Whatever is in the hole, multimode or single-mode, looped or single-ended. For a new hole, a slim cable rated for the cold comes with the rental. |
| Depth | Tens of metres to over a kilometre. |
| Power | A battery, a panel and if needed a small wind turbine. At one profile every four hours, a 100 Ah battery lasts about two months on its own. |
| Link | Satellite or cellular when available. The box keeps its schedule without one and catches up when it returns. |
| Term | A season or a year, month by month. |
The measurement
The instrument wakes on schedule, powers the optics, records one profile and sleeps again. Each profile is calibrated against the reference coils inside the box, so a season of data is consistent without anyone touching it. Isotherm depths and gradients are read off every profile and plotted as time series.
Deliverables
- Depth-time heatmap with the zero-degree isotherm drawn
- Time series of active-layer depth, basal gradient and minimum temperature
- Daily status line and alarms for missed profiles, low battery, link down
- netCDF and CSV for every profile
On the dashboard, through the API, and as files. All three, always.
Asked before
- How cold can the box go?
- It is specified to minus twenty degrees in the field case. Below that it lives in an insulated enclosure with the battery, which is standard practice for polar sites.
- What happens if the link is down for weeks?
- Nothing is lost. Profiles stay on local storage and upload when the link returns.
- Can several holes share one instrument?
- Yes, through the optical switch, if they are within cable reach of one box.
Other things the same box does
- Streams and lakes
Where does groundwater enter the stream, and how much?
You get Inflow zones marked along the reach, ranked by strength, from the damping and phase lag of the daily cycle.
Read more - Geothermal
What is the ground made of, layer by layer, and is the field slowly cooling?
You get Thermal conductivity and borehole resistance per depth interval, with uncertainty, from one test.
Read more - Wells
Where is the injected fluid going, and is the well behaving?
You get Time-lapse temperature profiles against the pre-injection baseline, with injection and shut-in periods marked.
Read more
Put your fibre to work.
Tell us about your fibre and your question. You get a call, a plan for your site and a monthly price.