----------------------------------------------------- Metadata for UAF Sea Ice Mass Balance Site 2008 ----------------------------------------------------- Chris Petrich petrich@gi.alaska.edu Daniel Pringle pringle@gi.alaska.edu ----------------------------------------------------- In 2008, the site was about 1000 meters offshore of Niksuiraq, the hook at the end of the road out to Pt. Barrow. Site installed by Chris Petirch, Jonas Karlsson. GPS location: (71° 21' 56.45" N, 156° 32' 39.01" 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. Hydraprobe dielectric measurements were not made this year. The code was written for 3 snow pingers. 1 Cambpell SR50 was installed intially, with two more (SR50 + SR50a) to be added during spring/ summer melt season to look at ice surface ablation and pond drainage. 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) with hardware-set SDI address = 0. SR50 + SR50a to be added in melt season (with hardware-set SDI addresses = 1,2) 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), 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 15 minutes. ----------------------------------------------------- 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 c(S,T). An offset of -0.45 C was added to T measured, based on lab tests in a snow/ ice water bath. (iii) 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). (iv) 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 (v)The reference resistor is a low-temperature co-efficient resistor. Its variability indicates the noise in the temperature measurements. ----------------------------------------------------- April: Snow pinger SR50(0) was replaced with SR50(1) on April 12. SR(0) was malfucntioning - returning intermittent data and zeroes. The online data processing was changed on April 14. April: Logger time changed to AK Daylight savings time at 11:12 am, April 9. March: A Polar bear collapsed the tower with downward looking snow pinger and CS500 air temp + humidity probe in early MArch (day 70) shortly after the battery failed. The site came back on line with new abttereies on day 74, with the tower still collapsed. It was repaired by CP the following week with all original cables and sensors retained. ----------------------------------------------------- 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) 2 year 3 day 4 time (hhmm) 5 logger temp [C] 6 bat volts [V] 7 T107 water temp [C] 8 CS500 rel hum [%] 9 SC500 air temp [C] 10 snow depth SR0 [m] 11 snow depth SR1 [m] 12 snow depth SR2 [m] 13 ice thickness [m] 14 sea level [m] 15 Ref. res. equiv.temp[C] 16 T1 (+ 40 cm) [C] 17 T2 (+ 30 cm) [C] …… … … 44 T29 (-240 cm) [C]