----------------------------------------------------- Metadata for UAF Sea Ice Mass Balance Site 2007 ----------------------------------------------------- Daniel Pringle pringle@gi.alaska.edu ----------------------------------------------------- In 2007, the site was about 100 meters offshore of Niksuiraq, the hook at the end of the road out to Pt. Barrow. Site installed by Daniel Pringle, Guy Dubuis with help from Chris Petrich and Nok Acker (BASC). GPS location: (71° 21' 47" N, 156° 31' 42" W) The following measurements are recorded: (i) snow and ice thickness and local sea level; (ii) temperature profile through air-snow-ice-water; (iii) air temperature and relative humidity at 2m above the ice; (iv) developmental sea ice dielectric measurements with Vitel Water Monitoring 'Hydraprobes'. Probes at depths (from initial upper ice surface) 0.8 and 0.95 m operated. Probe at 1.10m failed. Mass Balance Site: Campbell CR10X Data logger, AM1664 multiplexer, SM4M storage module, SC32A adaptor. FreeWave Spread-spectrum, no-license radio: FGR 115-WC, 900 MHz Bluewave 10 dB directional Yagi Antenna (BMY890K). Campbell SR50 Sonic Ranger (snow pinger), Shielded 107 air temperature probe, Benthos underwater acoustic altimeter PSA-916 (one upward looking, one downward looking), CRREL-design thermistor strings (3 x 1 meter sections), UAF dielectric array: 3 Vitel Water Hydraprobes. Batteries: 2 (of 4 total) UAF 12V cells currently stored at BASC (85 Amp-hr Exide). BASC Site: Bluewave 10 dB omni-directional Antenna and RF coaxial cabling to: FreeWave Spread-spectrum, no-license radio: FGR 115-RC, 900 MHz, connected to the serial port of a dedicated control PC with an internet connection. ----------------------------------------------------- Measurement intervals: The measurement interval was originally 30 minutes, but this was changed to 1 minute (to potnentially observe high frequency motion during the spring),and then to 5 minutes (to conserve battery life). Two data sets are available: the full one, and one down-sampled to only give half-hourly measurments. ----------------------------------------------------- Listed below are examples of the entries in each column in the data files. Notes: (i) All depths are referenced to the ice/water interface at the time of installation. (ii) T107 water temp is used by the data logger program to calculate the underwater depths using a speed of sound, vs,water = ... Similarly, the snow pinger uses a correction from the air temperature measurement, vs,air = .. (This shielded sensor at 2.25 m above ice/snow interface bottoms out at – 39.67 C). (iii) Time* is the time as day of year in a decimal format, here 11:00 am on day 75 (March 16, 2006 ) gives 75.45833 (iv)The reference resistor is a low-temperature co-efficient resistor. Its variability indicates the noise in the temperature measurements. (v) the deepest HP - the last to freeze in, was erratic. All data included here must treat with caution. UAF (Pringle) analyzed only HP1 and HP2. ----------------------------------------------------- Quality: These data have been processed to compute the physical values from the measured quantities. Periods of 'bad' data have been removed. However the time-series is not complete due to battery failure, and intermittent 'bad' values are returned. Plotting time-series as points not lines at least during inspection is recommended. ----------------------------------------------------- Column Description Value 1 Time* (decimal) 99.75 2 year 2007 3 day 99 4 time (hhmm) 1800 5 logger temp [C] -15.19 6 bat volts [V] 12.39 7 T107 water temp [C] -1.992 8 CS500 rel hum [%] 83.5 9 SC500 air temp [C] -16.30 10 snow depth [m] 0.1805 11 ice thickness [m] 1.2209 12 sea level [m] 6.221 13 Ref. res. equiv.temp[C] -5.9032 14 T1 (- 5 cm) [C] -10.5835 15 T2 (-15 cm) [C] -9.53011 etc …… … … 32 T19 (-185 cm) [C] -1.87687 33 Hydraprobe1 ID 1 34 real permittivity 13.18 35 imag permittivty 22.92 36 probe head temp [C] -3.22 37 Hydraprobe1 ID 2 38 real permittivity 10.24 39 imag permittivty 14.52 40 probe head temp [C] -3.48 41 Hydraprobe1 ID 3 42 real permittivity 12.91 43 imag permittivty 28.47 44 probe head temp [C] -2.23