August is here and so slightly belatedly I've started updating the Great White Con ice mass balance buoy visualisations. The CRREL's IMB 2013B is lookly decidedly dodgy. It's now heading towards the Bering Strait at a rate of knots, and the top and bottom sounders have ceased to report anything for a few days. The thermistors seem to be fine though, and this is what they reveal.
Would anyone care to open a book on the date of 2014B's ultimate demise?
That buoy melted out some time between July 15 and Aug 01. Comparing the sounders and the thermistor trace, I interpret it as the following:
Jun 01 traceThermistors 1 -> 4: in air at -4 degrees
Thermistors 5 -> ~21: in snow+ice layer, collective thickness a bit over 1.5m
Jun 15 traceThermistors 1 -> 4: in air at >= 4 degrees above a melt pond
Thermistor 5: at air/water interface
Thermistor 6 -> 7 in the melt pond
Thermistor 8: water/ice boundary
Thermistors 9 -> ~21: in snow+ice layer, collective thickness a bit over 1.5m
(sounders fooled by pond on surface, appears to show no major thickness loss yet, but actually there's been ~20-30cm of surface melt)Jun 18 traceThermistors 1 -> 5: in air at >= 4 degrees above a melt pond
Thermistor 6: at air/water interface
Thermistor 7 -> 12 in melt water (likely melt pond and/or drainage around the string)
Thermistor 13: apparent water/ice boundary
Thermistors 14 -> ~21: in ice layer, collective thickness a bit over 1.5m
(sounders still fooled by pond on surface, no apparent loss by sonar)Jul 01 traceThermistors 1 -> 5: in air at >= 6 degrees above a melt pond
Thermistor 6: at air/water interface, cooled by evaporation (?)
Thermistor 7: just under surface of melt pond, slightly warmer than 6 as the pond absorbs energy
Thermistors 8 -> ~15: In the melt pond, slightly below zero (brackish water now since it's mostly composed ice meltwater now rather than snow meltwater)
Thermistors 16 -> 20: In ice
(amazingly, sonar still shows almost no loss at top or bottom, but only ~40cm of actual ice left)Jul 15 traceThermistors 1 -> 9: in air at >= 6 degrees above a melt pond, 3-9 cooled by evaporation layer (?)
Thermistors 10 -> ~15: In the melt pond, slightly below zero (brackish water now since it's mostly composed ice meltwater now rather than snow meltwater)
Thermistors 16 -> 18: In ice
(sonar has now noticed ~30-40cm of top melt and ~20cm of bottom melt)Aug 01 trace1-5 in air at ~2 degrees
6 at water interface
Remainder in water at ~-1.5
(buoy is now floating in water with no ice)