South Pole Tank Test This presentation contains some information about the tank sensors and measurements

Map of temperature sensors 12 13 14 15 16 17 18 19 20 21 22 23 1 2 3 4 5 6 7 8 9 10 11 -10 -23 -41 -56 -71 -86 -102 -117 Depths (cm) of sensors. (Tank is 122cm; Ice surface is at -22 cm in Tank10 and at -34 cm in Tank09 24 is inside box; 25-29 are at various locations inside tent

Freeze rate Solve Serap’s equation with external power input: dh/dt = 1.57E-7 (m/s) x {T/20} x {1/h - 0.64 x (P/100)} (T is surface temperature of ice) Result shown by lines in figure: Crosses based on side temps Circles based on # sump cycles Data points very approximate indicate some concavity Puzzle: why is the ice not deeper? Tsurface > -20 ? Heat from Sun ?

Tank temperatures Significant diurnal and semi-diurnal variations: Sensor TT01: black, outside tank at ice surface Sensor TT04: green, 5th down on outside of tank Sensor TT12: red, at pipe elbow under middle of tank Sensor TT22: blue, at elbow of ejection pipe Sensor TT28: lavender, inside tent Significant diurnal and semi-diurnal variations: Trench axis is along grid N-S Ejection pipe elbow (blue) faces sun once per day around NZ noon (64,800 s EST) Whole tank is heated at local midnight (21,600) and local noon The fact that the sensor under the middle of the tank cycles with Sun suggests solar heating may have a major impact on freezing.

Correlated variation in freeze-rate

Sunshades On Dec 6 we set up plywood shades Starting end of Dec: Semi-diurnal temp fluctuations stopped But no speed-up of freeze rate Starting end of Dec: Remove pieces of insulation on sides of tank facing trench walls